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Schrödinger’s Cat Experiment and the Conundrum That Rules Modern Physics

Why schrödinger (figuratively speaking) put his cat in the box — and why it may never get out..

Schrodinger's cat - dead and alive - shutterstock 227038018 (1)

Long before cats conquered the internet, two of the greatest physicists of our time — Erwin Schrödinger and Albert Einstein — devised what almost seems like an evil thought experiment.

It goes something like this: You have a cat in a completely sealed box impervious to any observation from outside. Inside is a kind of device involving a Geiger counter, poison, and radioactive material whose atoms may or may not enter a state of decay in equal probability over the course of an hour. If one atom does decay, the Geiger counter detects the radiation and triggers a hammer that breaks open the vial of poison, killing the cat. If no atom decays, then the cat lives.

Of course, the device was only theoretical. Schrödinger developed the scenario in a discussion with Einstein in response to misinterpretations of quantum mechanics at the time. It was a way to describe how a concept that seemed to apply to minute electrons in atoms might apply to a complex object in the macroscopic world — in this case, a cat.

While Schrödinger’s cat remains something of an infamous thought experiment, the original equation he originally derived the scenario from has gone on to represent the foundation of quantum mechanics. It involves the idea that something can be in two simultaneous states and only becomes one or the other when observed, detected, or even when it interacts with other particles. That fundamental theory of physics has modern-day applications that include everything from supercomputers to chemistry and superconducting magnets.

“[The Schrödinger equation] is like a modern version of Newton’s law,” says Chen Wang , an assistant professor of physics at the University of Massachusetts Amherst.

The Theory in Question

In the 1920s, Schrödinger and other physicists were concerned with a problem that couldn’t be explained by classic physics. The smaller a particle becomes, the less clear its position or speed becomes.

“Quantum mechanics adds a level of fuzziness to the position of particles,” says Wang.

Electrons form the base of the theory — in particular, the single electron in a hydrogen atom. Whereas scientists previously described electrons as orbiting the nucleus in an atom, quantum physicists observed that things weren’t quite this simple. Rather, they seemed to exist in several places at once. Or they blinked back and forth, between specific areas without appearing in between. In fact, the only thing you can say for sure is that an electron is not in one place at one time.

“It’s fundamentally uncertain where exactly the position [of an electron] is,” Wang says.

Instead, you have to describe an electron’s position as a wave function, or a probability distribution that describes where the electron is more likely to occur. The term superposition in quantum physics is used to describe how an electron in this case can seem to exist in multiple positions at the same time.

Tying Things Up

If you’re not lost yet, the idea gets even wilder when you add an extra electron. In helium, for example — which has two electrons — each one can only be described as probably being in a given area at a given time. But they also can interact and affect each other despite their distance in a process known as quantum entanglement, or “spooky action at a distance,” as Einstein called it.

Another way to think of it is that changing the state of one electron means the state of the other has to change as well.

“The description for two electrons cannot be directly produced by thinking of two independent shapes,” says Frederick Strauch , a physicist at Williams College in Massachusetts. “We can think of them as somehow jumping between the different shapes.”

Nine Lives or Two States?

The scenario involving Schrödinger’s dead — or undead — cat in a box involves a thought experiment to describe how the state of electrons might conceivably affect something much larger, in the macro world. He created it in response to a theory of quantum mechanics by other physicists called the Copenhagen interpretation to show the potential shortcomings of their view.

Since we can’t see in the box at the end of the hour or send any type of probe inside, according to the Copenhagen theorists, the radioactive atoms remain in a superposition of both decay or non-decay. The cat, in turn, depends on this superposition, as we don’t know whether it’s alive or dead. In a quantum sense, its superposition remains in both states at the same time, as a wave function that is both alive and dead. The entanglement is represented by the connection between the radioactive atoms and the cat, says Strauch.

When we open the box and look inside, or if the outside world somehow interacts with the inside of the box, the wave function is forced to collapse into one state, and the cat becomes dead or alive.

The thing is, Schrödinger didn’t actually mean for the situation to be taken seriously. The fact that an observing scientist’s curiosity could kill the cat was meant to show how an earlier interpretation of quantum mechanics was ludicrous.

“He’s kind of alluding to the fact that the theory is sort of silly to apply to the macroscopic world,” Wang says. “There might be something missing.”

But his thought experiment has since taken on a life (or death) of its own, with many people believing that the cat would be dead and alive at the same time. The only shortcoming of such a thought experiment may rest in our technical inability to carry such an experiment out.

Cats, Present, and Future

Even if Schrödinger himself didn’t believe the cat theory was possible, modern researchers are trying to put some of these theories into practice. In 2016, Wang and his colleagues managed to demonstrate that it’s possible to entangle multiple particles. They managed to measure the entanglement of up to 80 photons, or light particles, placed in special boxes connected by a supercurrent that flows without voltage. In basic terms, it meant the spin they put on photons in one box could be observed in the other box even though they hadn’t spun the latter. Photons without spin also existed in both boxes. Metaphorically, it’s like a live cat and a dead cat were found in two different boxes that were correlated.

Quantum mechanics is already leading to practical applications. Quantum computing is one method, in which the harnessing of superposition and entanglement allows faster calculations than classical computers. Strauch says there are many potential applications of this, but researchers are already on the cusp of using them to calculate chemical formulas in a virtual space to design drugs.

But it may still take a long time before researchers figure out a way to run Schrödinger's experiment. If they ever do, and even the man himself thought this was unlikely, then it could show how the microscopic quantum world might affect the macroscopic world.

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Schrödinger’s cat

By Joshua Howgego

Sven Puth/EyeEm/Getty Images

Devised in 1935 by the Austrian physicist Erwin Schrödinger, this thought experiment was designed to shine a spotlight on the difficulty with interpreting quantum theory .

Quantum theory is very strange. It says that an object like a particle or an atom that adheres to quantum rules doesn’t have a reality that can be pinned down until it is measured. Until then, its properties, such as momentum, are encoded in a mathematical object known as a wave function that essentially says: if you make a measurement, here are a range of possible outcomes. The inevitable question that arose as the theory developed was: what, then, is the thing doing before that?

The most prominent answer in the 1930s came from the Copenhagen interpretation , developed in the Danish city by luminaries of quantum theory, Niels Bohr and Werner Heisenberg . This says that there really is no definitive reality before the measurement, and the object is in an undefined state known as a superposition.

Schrödinger’s thought experiment probed how this plays out when a quantum object is coupled to something more familiar. He imagined a box containing a radioactive atom, a vial of poison and a cat. Governed by quantum rules, the radioactive atom can either decay or not at any given moment. There’s no telling when the moment will come, but when it does decay, it breaks the vial, releases the poison and kills the cat.

If the Copenhagen interpretation is correct, then before any measurement has occurred, the atom, and so also the cat, are in a superposition of being decayed/dead and not decayed/alive. The absurdity of speaking of a simultaneously living and dead moggie was supposed to show that the Copenhagen interpretation must be lacking something.

The experiment played an important part in spurring other ways of thinking about quantum theory, including the many worlds interpretation, which says that the different possible realities of a quantum object crystallise into different parallel universes at the point of measurement.

The quantum experiment that could help find evidence of the multiverse

Scars of collisions with other universes could show up in radiation from the big bang. A new experiment aims to mimic these collisions and help us look for them

These days the thought experiment has taken on a kind of cult status. There are Schrödinger’s cat T-shirts, memes and hundreds of articles on the subject. In 2018, scientists published a more complicated variant of the thought experiment that appears to show that all existing interpretations of quantum theory are incomplete .

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Science Questions with Surprising Answers

What did Schrodinger's Cat experiment prove?

Category: Physics Published: July 30, 2013 Updated: November 27, 2023

By: Christopher S. Baird, author of The Top 50 Science Questions with Surprising Answers and Associate Professor of Physics at West Texas A&M University

"Schrodinger's Cat" was not a real experiment and therefore did not scientifically prove anything. Schrodinger's Cat is not even part of any scientific theory. Schrodinger's Cat was simply a teaching tool that Schrodinger used to illustrate how some people were misinterpreting quantum theory. Schrodinger constructed his imaginary experiment with the cat to demonstrate that simple misinterpretations of quantum theory can lead to absurd results which do not match the real world. Unfortunately, many popularizers of science in our day have embraced the absurdity of Schrodinger's Cat and claim that this is how the world really works.

In quantum theory, quantum particles can exist in a superposition of states at the same time and collapse down to a single state upon interaction with other particles. Some scientists at the time that quantum theory was being developed (1930's) drifted from science into the realm of philosophy, and stated that quantum particles only collapse to a single state when viewed by a conscious observer. Schrodinger found this concept absurd and devised his thought experiment to make plain the absurd yet logical outcome of such claims.

In Schrodinger's imaginary experiment, you place a cat in a box with a tiny bit of radioactive substance. When the radioactive substance decays, it triggers a Geiger counter which causes a poison or explosion to be released that kills the cat. Now, the decay of the radioactive substance is governed by the laws of quantum mechanics. This means that the atom starts in a combined state of "going to decay" and "not going to decay". If we apply the observer-driven idea to this case, there is no conscious observer present (everything is in a sealed box), so the whole system stays as a combination of the two possibilities. The cat ends up both dead and alive at the same time. Because the existence of a cat that is both dead and alive at the same time is absurd and does not happen in the real world, this thought experiment shows that wavefunction collapses are not just driven by conscious observers.

Einstein saw the same problem with the observer-driven idea and congratulated Schrodinger for his clever illustration, saying, "this interpretation is, however, refuted, most elegantly by your system of radioactive atom + Geiger counter + amplifier + charge of gun powder + cat in a box, in which the psi-function of the system contains the cat both alive and blown to bits. Is the state of the cat to be created only when a physicist investigates the situation at some definite time?"

Since that time, there has been ample evidence that wavefunction collapse is not driven by conscious observers alone. In fact, every interaction a quantum particle makes can collapse its state. Careful analysis reveals that the Schrodinger Cat "experiment" would play out in the real world as follows: as soon as the radioactive atom interacts with the Geiger counter, it collapses from its non-decayed/decayed state into one definite state. The Geiger counter gets definitely triggered and the cat gets definitely killed. Or the Geiger counter gets definitely not triggered and the cat is definitely alive. But both don't happen.

Roger Penrose, a Nobel Prize winner and one of the most brilliant physicists of the last sixty years, wrote about Schrodinger's Cat in his book The Road to Reality as follows: "So the cat is both dead and alive at the same time! Of course such a situation is an absurdity for the behavior of a cat-sized object in the actual physical world as we experience it... There is a 50% chance that the cat will be [definitely] killed and a 50% chance that it will [definitely] remain alive. This is the physically correct answer, where 'physically' refers to the behavior of the world that we actually experience." Penrose goes on to explain that any physical theory or philosophical interpretation of quantum physics that leads to the cat being both dead and alive at the same time must be a faulty theory or interpretation, because that is not what happens in the real world.

Despite that fact that the Schrodinger's Cat story is not a real experiment, does not prove anything, does not match physical reality, and was intentionally designed to be absurd, this line of thinking does indeed lead to a meaningful question. Why does the cat in this setup not end up in a state of dead and alive at the same time in the real world? In other words, why does a measurement collapse a quantum object from a superposition of states to a single definite state? This question has not yet been fully answered by quantum physics. This is known as the "measurement problem" of quantum physics. Note that the measurement of a quantum object in a superposition of states collapsing down the object to a definite single state is very well predicted by the mathematics of quantum physics. Therefore, the "measurement problem" is more a problem of philosophical interpretation and incomplete scientific explanation, than a problem of the theory being incorrect.

In summary, quantum state collapse is not driven just by conscious observers. Unfortunately, many popular science writers in our day continue to propagate the misconception that a quantum state (and therefore reality itself) is determined by conscious observers. They use this erroneous claim as a springboard into unsubstantial and non-scientific discussions about the nature of reality, consciousness, and even Eastern mysticism. To them, Schrodinger's Cat is not an embarrassing indication that their claims are wrong, but proof that the world is as absurd as they claim. Such authors either misunderstand Schrodinger's Cat, or intentionally misrepresent it to sell books.

Topics: Schrodinger's Cat , observation , quantum , superposition , wavefunction collapse

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What is Erwin Schrödinger best known for?
Why does physics work in SI units?

Adolf Hitler (Nazi, nazism, German leader).

What was Erwin Schrödinger’s most famous thought experiment?

Erwin Schrödinger’s most famous thought experiment became known as “Schrödinger’s cat”: A cat is in a box with a vial of poison. The vial breaks if an atom inside the box decays. The atom is superposed in decay and non-decay states until it is observed, and thus the cat is superposed in alive and dead states.

Schrödinger's Cat

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Two worlds "splitting off"- one where the cat is alive and one where the cat is dead. Taken from [MWI].

Schrödinger's cat is a thought experiment designed to show how certain interpretations of quantum mechanics lead to counterintuitive results.

In the experiment, a cat is placed inside a box with a vial of poisonous gas. A mallet is set up such that it breaks the vial of gas if a particular radioactive atom decays, killing the cat. Since the radioactive decay is a quantum system, whether the cat lives or dies is determined by quantum mechanical behavior. This leads to the conclusion that before the box is opened, the cat is simultaneously alive and dead.

Erwin Schrödinger originally proposed the idea as an absurd example showing that the Copenhagen Interpretation of quantum mechanics - the most popular philosophical interpretation at the time - could not possibly be true [1]. However, it has lived on as a thought experiment fueling both physical theories and the popular imagination.

Quantum States and Superposition

The many-worlds interpretation.

The two main ideas behind quantum theory are the idea of quantized , or discrete, states, and the idea of superposition.

A physical system is defined by the set of possible states in which it can be observed . For instance, an electron can be observed either in a spin up state or in a spin down state, but never a combination of the two. Similarly, a particle emitted in radioactive decay is observed to be either emitted or not emitted, never partway emitted. However, particles prepared in identical ways will not always be observed to have the same state. Identical uranium atoms will decay or not decay at random times, though the more time has passed, the more likely the atom is to decay. The state of the system will change such that it becomes more likely to decay.

To determine how states change over time, the idea of a superposition of states is required. A superposition is a vector addition of two states. Quantum states can be in any superposition of the observable states in the system. For instance, an electron can be in a state that is 50% spin up and 50% spin down. As time passes, the electron may change states, perhaps smoothly oscillating between 100% spin up and 100% spin down, passing through the 50/50 state at each time. The Schrödinger equation , the analog of Newton's laws for quantum mechanics, describes exactly how the electron will transition between these different superpositions of states.

But this seems to be at odds with the previous statement. How can a system be an a superposition of states if it can only ever be observed in one state? The Copenhagen interpretation of quantum mechanics holds that when an observer observes a system, it "collapses" from a superposition of multiple states down to a single state in a probabilistic way. This is distinct from the smooth changes in superposition that happen due to the Schrödinger equation.

When Schrödinger's cat is observed, it is either alive or dead. But when it isn't, it is in a superposition of alive and dead.

Technical note: the space of valid states is the set of complex vectors with an eigenbasis given by the observable states and magnitude 1. For linear combinations of eigenvectors, the probability of observing each component of the state vector is given by the magnitude of the coefficient of that component. Linear algebra is important for a deep understanding of quantum mechanics: most results come directly from the properties of operators on complex vector spaces.

The collapse interpretation has an issue, though. Instead of just you observing a cat in a box, imagine putting yourself and the cat in a room and having your friend wait outside the room. You run the experiment, open the box, record your observations, and only then have your friend open the room and see what your observations were. From your perspective, the cat is in a superposition of alive and dead until you open the box, at which point a collapse occurs. You are then in the definite state of having seen the cat, a state which persists until your friend opens the door. But from your friend's perspective, up until they open the door, you are still in a superposition of having seen the cat dead and having seen it alive.

Even worse, this setup can be repeated again and again, such that every new observer is placed in a larger room. Observer $n$ always thinks that the state has collapsed before observer $n + 1$. The idea that different observers will disagree on the state of reality in this experiment is problematic.

The many-worlds interpretation of quantum mechanics solves this problem by rejecting the idea of collapse entirely. It instead claims that there is always a superposition of two "world-branches," one where the cat is dead and one where the cat is alive. When you open the box, there is now a superposition of two worlds with two versions of you. In one world, the cat is alive and you see the cat is alive. In the other world, the cat is dead and you see the cat is dead.

[1] Schrödinger, Erwin; Translated by Trimmer, John. The Present Situation in Quantum Mechanics. Proceedings of the American Philosophical Society . Retrieved on 7 Mar 2016 from http://www.tuhh.de/rzt/rzt/it/QM/cat.html

[flickr] Flickr user chwalker01. Retrieved on 7 Mar 2016 from https://www.flickr.com/photos/31690139@N02/2965956885

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Erwin Schrödinger, one of the fathers of quantum mechanics, is famed for a number of important contributions to physics, especially the Schrödinger equation, for which he received the Nobel Prize in Physics in 1933.

The Physics Behind Schrödinger's Cat Paradox

Google honors the physicist today with a Doodle. We explain the science behind his famous paradox.

His feline paradox thought experiment has become a pop culture staple , but it was Erwin Schrödinger's work in quantum mechanics that cemented his status within the world of physics.

The Nobel prize-winning physicist would have turned 126 years old on Monday and to celebrate, Google honored his birth with a cat-themed Doodle , which pays tribute to the paradox Schrödinger proposed in 1935 in the following theoretical experiment.

A cat is placed in a steel box along with a Geiger counter, a vial of poison, a hammer, and a radioactive substance. When the radioactive substance decays, the Geiger detects it and triggers the hammer to release the poison, which subsequently kills the cat. The radioactive decay is a random process, and there is no way to predict when it will happen. Physicists say the atom exists in a state known as a superposition—both decayed and not decayed at the same time.

Until the box is opened, an observer doesn't know whether the cat is alive or dead—because the cat's fate is intrinsically tied to whether or not the atom has decayed and the cat would, as Schrödinger put it, be "living and dead ... in equal parts" until it is observed. (More physics: The Physics of Waterslides .)

In other words, until the box was opened, the cat's state is completely unknown and therefore, the cat is considered to be both alive and dead at the same time until it is observed.

"If you put the cat in the box, and if there's no way of saying what the cat is doing, you have to treat it as if it's doing all of the possible things—being living and dead—at the same time," explains Eric Martell , an associate professor of physics and astronomy at Millikin University. "If you try to make predictions and you assume you know the status of the cat, you're [probably] going to be wrong. If, on the other hand, you assume it's in a combination of all of the possible states that it can be, you'll be correct."

Immediately upon looking at the cat, an observer would immediately know if the cat was alive or dead and the "superposition" of the cat—the idea that it was in both states—would collapse into either the knowledge that "the cat is alive" or "the cat is dead," but not both.

Schrödinger developed the paradox, says Martell, to illustrate a point in quantum mechanics about the nature of wave particles.

"What we discovered in the late 1800s and early 1900s is that really, really tiny things didn't obey Newton's Laws," he says. "So the rules that we used to govern the motion of a ball or person or car couldn't be used to explain how an electron or atom works."

At the very heart of quantum theory—which is used to describe how subatomic particles like electrons and protons behave—is the idea of a wave function. A wave function describes all of the possible states that such particles can have, including properties like energy, momentum, and position.

"The wave function is a combination of all of the possible wave functions that exist," says Martell. "A wave function for a particle says there's some probability that it can be in any allowed position. But you can't necessarily say you know that it's in a particular position without observing it. If you put an electron around the nucleus, it can have any of the allowed states or positions, unless we look at it and know where it is."

That's what Schrödinger was illustrating with the cat paradox, he says.

"In any physical system, without observation, you cannot say what something is doing," says Martell. "You have to say it can be any of these things it can be doing—even if the probability is small."

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Schrodinger's Cat (Simplified): What Is It & Why Is It Important?

In 1935 – two years after winning the Nobel Prize for his contributions to quantum physics – Austrian Physicist Erwin Schrödinger proposed the famous thought experiment known as Schrödinger’s cat paradox.

What Is Schrödinger’s Cat Paradox?

The paradox is one of the most well-known things about quantum mechanics in popular culture, but it isn’t merely a surreal and funny way to describe how the quantum world behaves, it actually strikes at a key criticism of the dominant interpretation of quantum mechanics.

It endures because it proposes the absurd idea of a simultaneously alive and dead cat, but it has some philosophical weight because, in a sense, this really is something that quantum mechanics might suggest is possible.

Schrödinger came up with the thought experiment for precisely this reason. Like many other physicists, he wasn’t completely satisfied by the Copenhagen interpretation of quantum mechanics, and he was looking for a way to convey what he saw as the central flaw in it as a way of describing reality.

The Copenhagen Interpretation of Quantum Mechanics

The Copenhagen interpretation of quantum mechanics is still the most widely-accepted attempt to make sense of what quantum physics actually means in a physical sense.

It essentially says that the wave function (which describes a particle’s state) and the Schrödinger equation (which you use to determine the wave function) tell you everything you can know about a quantum state. This might sound reasonable at first, but this implies a lot of things about the nature of reality that don’t sit well with many people.

For example, a particle’s wave function spreads across space, and so the Copenhagen interpretation states that a particle doesn’t have a definitive location until a measurement is made.

When you make a measurement, you cause wavefunction collapse, and the particle falls into one of several possible states instantly, and this can only be predicted in terms of a probability.

The interpretation says that quantum particles actually don’t have values of observables such as position, momentum or spin until an observation is made . They exist in a range of potential states, in what is called a “superposition” and can essentially be thought of as all of them at once, although weighted to acknowledge that some states are more likely than others.

Some take this interpretation more strictly than others – for example, the wave function could simply be viewed as a theoretical construct that allows scientists to predict the results of experiments – but this is broadly how the interpretation views quantum theory.

Schrödinger’s Cat

In the thought experiment, Schrödinger proposed placing a cat in a box, so it was hidden from observers (you can imagine this to be a sound-proof box, too) along with a vial of poison. The vial of poison is rigged to break and kill the cat if a certain quantum event takes place, which Schrödinger took to be the decay of a radioactive atom which is detectable with a Geiger counter.

As a quantum process, the timing of radioactive decay can’t be predicted in any specific case, only as an average over many measurements. So with no way to actually detect the decay and the vial of poison breaking, there is literally no way to know whether it has happened in the experiment.

In the same way as particles are not considered to be in a particular location prior to measurement in quantum theory, but a quantum superposition of possible states, the radioactive atom can be considered to be in a superposition of “decayed” and “not decayed.”

The probability of each could be predicted to a level that would be accurate over many measurements but not for a specific case. So if the radioactive atom is in a superposition, and the life of the cat depends entirely on this state, does this mean the cat’s state is also in superposition of states? In other words, is the cat in a quantum superposition of alive and dead?

Does the superposition of states only happen at the quantum level, or does the thought experiment show that it should logically apply to macroscopic objects too? If it can’t apply to macroscopic objects, why not? And most of all: Isn’t this all a bit ridiculous?

Why Is It Important?

The thought experiment gets to the philosophical heart of quantum mechanics. In one easy-to-understand scenario, the potential issues with the Copenhagen interpretation are laid bare and proponents of the explanation are left with some explaining to do. One of the reasons it’s endured in popular culture is undoubtedly that it vividly shows the difference between how quantum mechanics describes the state of quantum particles, and the way you describe macroscopic objects.

However, it also tackles the notion of what you mean by “measurement” in quantum mechanics. This is an important concept, because the process of wave function collapse depends fundamentally on whether something has been observed.

Do people need to physically observe the outcome of a quantum event (for example, reading the Geiger counter), or does it simply need to interact with something macroscopic? In other words, is the cat a “measuring device” in this scenario – is that how the paradox is resolved?

There isn’t really an answer to these questions that’s widely-accepted. The paradox perfectly captures what it is about quantum mechanics that is hard to stomach for humans accustomed to experiencing the macroscopic world, and indeed, whose brains ultimately evolved to understand the world in which you live and not the world of subatomic particles.

The EPR Paradox

The EPR paradox is another thought experiment intended to show issues with quantum mechanics, and it was named after Albert Einstein, Boris Podolsky and Nathan Rosen, who devised the paradox. This relates to quantum entanglement , which Einstein famously referred to as “spooky action at a distance.”

In quantum mechanics, two particles can be “entangled,” so that any one of the pair cannot be described without reference to the other – their quantum states are described by a shared wave function that cannot be separated into one for one particle and one for another.

For example, two particles in a specific entangled state can have their “spin” measured, and if one is measured as having spin “up,” the other must have spin “down,” and vice-versa, although this isn’t determined beforehand.

This is a little difficult to accept anyway, but what if, the EPR paradox proposes, the two particles were separated by a huge distance. The first measurement is made and reveals “spin down,” but then very shortly afterward (so fast that even a light signal couldn’t have traveled from one location to the other in time) a measurement is made on the second particle.

How does the second particle “know” the result of the first measurement if it’s impossible for a signal to have traveled between the two?

Einstein believed this was proof that quantum mechanics was “incomplete,” and that there were “hidden variables” at play that would explain seemingly illogical results like these. However, in 1964, John Bell found a way to test for the presence of the hidden variables Einstein proposed and found an inequality that, if broken, would prove that the result couldn’t be obtained with a hidden variable theory.

Experiments performed on the basis of this have found that Bell’s inequality is broken, and so the paradox is just another aspect of quantum mechanics that seems strange but is simply the way quantum mechanics works.

Is teleportation possible in real life, who discovered the particle theory, the famous physicist who discovered photons, cern plans to search for mysterious fifth force particle, is the multiverse real, difference between law and principle in physics, james chadwick atomic theory, how does light travel, difference between metaphysics & quantum physics, what is the theory of everything scientists talk about.

University of California, Riverside: Does Bell's Inequality Rule out Local Theories of Quantum Mechanics?
APS Physics: Einstein and the EPR Paradox
CERN: On the Einstein Podolsky Rosen Paradox
IFL Science: Schrödinger’s Cat: Explained
National Geographic: The Physics Behind Schrödinger's Cat Paradox
University of Oregon: Copenhagen Interpretation

About the Author

Lee Johnson is a freelance writer and science enthusiast, with a passion for distilling complex concepts into simple, digestible language. He's written about science for several websites including eHow UK and WiseGeek, mainly covering physics and astronomy. He was also a science blogger for Elements Behavioral Health's blog network for five years. He studied physics at the Open University and graduated in 2018.

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What Is Schrödinger’s Cat?

Schrödinger’s Cat is a famous thought experiment that illustrates a paradox of quantum superposition. Here’s how it works.

Schrödinger’s Cat is a thought experiment devised by the Austrian physicist Erwin Schrödinger, which he designed to illustrate a paradox of quantum superposition wherein a hypothetical cat may be considered both alive and dead simultaneously because its fate is linked to a random event that may (or may not) occur.

What Is Schrödinger’s Cat in Simple Terms?

Schrödinger’s Cat, as a thought experiment, states that if you seal a cat in a box with something that can eventually kill it, you won’t know if the cat is alive or dead until you open the box. So, until you open the box and observe the cat, the cat is simultaneously dead and alive.

How Does Schrödinger’s Cat Work?

We often use Schrödinger’s thought experiment to explain the concept of superposition . The experiment states that a hypothetical cat is locked in a box with some radioactive substance controlling a vial of poison. When the substance decays, it triggers a Geiger counter that causes the poison to be released, thereby killing the cat.

Since the box is locked, and we on the outside don’t know whether or not the radioactive substance has decayed and released the poison, we can’t tell if the cat is dead or alive. So, until we open the box to know for sure, the cat is both dead and alive. Mathematically speaking, there’s a 50 percent chance the cat is dead and a 50 percent chance the cat is alive.

More From Built In’s Tech Dictionary What Is Superposition?

How Is Schrödinger’s Cat Both Alive and Dead?

In quantum mechanics terms, the cat’s ability to be in an ambiguous state of both alive and dead until it’s observed (i.e. when someone opens the box) is referred to as quantum indeterminacy or the observer’s paradox . The paradox states that an event or an experiment’s observer affects its outcome. In this case, whomever is performing this hypothetical experiment can affect whether the cat remains in an unknown state or they can open the box and know if the cat is dead or alive with 100 percent certainty.

The experiment also points out when the resolution of possibilities occurs. The experiment is intended to make people ask themselves if it was logical for the observation to trigger the answer. After all, wouldn’t the cat be either dead or alive even if we never open the box?

Schrödinger’s Cat and the Role of the Observer

In quantum mechanics, the observer (the person conducting the experiment) has a role in the results of the experiment. In this case, we are unaware of the cat’s state until the observer opens the box. Until the observer opens the box, the cat exists in a superposition state; that is, the cat is both alive and dead. Only by opening the box and looking at what’s inside (i.e., observing it) is the cat’s state confirmed to be one of the two states. This is called The Copenhagen interpretation of quantum mechanics, which basically explains that a quantum system exists in all of its possible states at the same time. Only when we make an observation can we confirm the true state of the system.

More Quantum Reading From Built In Experts Why Do Quantum Objects Keep Getting Weirder?

Why Do We Use Schrödinger’s Cat?

We still use this thought experiment today to explain quantum physics concepts in an easy-to-understand way. Some people also use Schrödinger’s Cat to talk more philosophically about how the thought experiment can be extended to other situations in life. For example, let’s say you meet your friend for a night out and you’re both unsure about what to have for dinner; until you reach an agreement or one of you decides for the group, the possible food option is “every option that can exist where you and your friend are.” Looking at things from this perspective has led many people to think of everything in life as “quantum” because until the future is here, it technically (according to Schrödinger ) exists in a state of superposition of all possible scenarios.

Frequently Asked Questions

What is schrödinger's cat in simple terms.

Schrödinger’s Cat is a famous thought experiment that demonstrates the idea in quantum physics that tiny particles can be in two states at once until they’re observed. It asks you to imagine a cat in a box with a mechanism that might kill it. Until you look inside, the cat is both alive and dead at the same time.

Is Schrödinger’s Cat a metaphor?

Schrödinger’s Cat is a thought experiment and is also considered a metaphor or a paradox.

Is Schrödinger’s Cat literal?

Schrödinger’s Cat is not meant to be taken literally, but as a thought experiment designed to show the counterintuitive idea of quantum superposition.

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Erwin Schrodinger was one of the key figures in quantum physics , even before his famous " Schrodinger's Cat " thought experiment. He had created the quantum wave function, which was now the defining equation of motion in the universe, but the problem is that it expressed all motion in the form of a series of probabilities—something which goes in direct violation to how most scientists of the day (and possibly even today) like to believe about how physical reality operates.

Schrodinger himself was one such scientist and he came up with the concept of Schrodinger's Cat to illustrate the issues with quantum physics. Let's consider the issues, then, and see how Schrodinger sought to illustrate them through analogy.

Quantum Indeterminancy

The quantum wave function portrays all physical quantities as a series of quantum states along with a probability of a system being in a given state. Consider a single radioactive atom with a half-life of one hour.

According to the quantum physics wave function, after one hour the radioactive atom will be in a state where it is both decayed and not-decayed. Once a measurement of the atom is made, the wave function will collapse into one state, but until then, it will remain as a superposition of the two quantum states.

This is a key aspect of the Copenhagen interpretation of quantum physics—it's not just that the scientist doesn't know which state it's in, but it's rather that the physical reality is not determined until the act of measurement takes place. In some unknown way, the very act of observation is what solidifies the situation into one state or another. Until that observation takes place, the physical reality is split between all possibilities.

On to the Cat

Schrodinger extended this by proposing that a hypothetical cat be placed in a hypothetical box. In the box with the cat we would place a vial of poison gas, which would instantly kill the cat. The vial is hooked up to an apparatus which is wired into a Geiger counter, a device used to detect radiation. The aforementioned radioactive atom is placed near the Geiger counter and left there for exactly one hour.

If the atom decays, then the Geiger counter will detect the radiation, break the vial, and kill the cat. If the atom does not decay, then the vial will be intact and the cat will be alive.

After the one-hour period, the atom is in a state where it is both decayed and not-decayed. However, given how we've constructed the situation, this means that the vial is both broken and not-broken and, ultimately, according to the Copenhagen interpretation of quantum physics the cat is both dead and alive .

Interpretations of Schrodinger's Cat

Stephen Hawking is famously quoted as saying "When I hear about Schrodinger's cat, I reach for my gun." This represents the thoughts of many physicists, because there are several aspects about the thought experiment that bring up issues. The biggest problem with the analogy is that quantum physics typically only operates on the microscopic scale of atoms and subatomic particles, not on the macroscopic scale of cats and poison vials.

The Copenhagen interpretation states that the act of measuring something causes the quantum wave function to collapse. In this analogy, really, the act of measurement takes place by the Geiger counter. There are scores of interactions along the chain of events—it is impossible to isolate the cat or the separate portions of the system so that it is truly quantum mechanical in nature.

By the time the cat itself enters the equation, the measurement has already been made ... a thousand times over, measurements have been made—by the atoms of the Geiger counter, the vial-breaking apparatus, the vial, the poison gas, and the cat itself. Even the atoms of the box are making "measurements" when you consider that if the cat falls over dead, it will come in contact with different atoms than if it paces anxiously around the box.

Whether or not the scientist opens the box is irrelevant, the cat is either alive or dead, not a superposition of the two states.

Still, in some strict views of the Copenhagen interpretation, it is actually an observation by a conscious entity which is required. This strict form of the interpretation is generally the minority view among physicists today, although there remains some intriguing argument that the collapse of the quantum wavefunctions may be linked to consciousness. (For a more thorough discussion of the role of consciousness in quantum physics, I suggest Quantum Enigma: Physics Encounters Consciousness by Bruce Rosenblum & Fred Kuttner.)

Still another interpretation is the Many Worlds Interpretation (MWI) of quantum physics, which proposes that the situation actually branches off into many worlds. In some of these worlds the cat will be dead upon opening the box, in others the cat will be alive. While fascinating to the public, and certainly to science fiction authors, the Many Worlds Interpretation is also a minority view among physicists, though there is no specific evidence for or against it.

Edited by Anne Marie Helmenstine, Ph.D.

The Copenhagen Interpretation of Quantum Mechanics
Introduction to the Dirac Delta Function
The Photoelectric Effect
Using Quantum Physics to "Prove" God's Existence
How Quantum Levitation Works
EPR Paradox in Physics
The Many Worlds Interpretation of Quantum Physics
Quantum Entanglement in Physics
Understanding the Heisenberg Uncertainty Principle
Can Quantum Physics Be Used to Explain the Existence of Consciousness?
Quantum Physics Overview
Quantum Computers and Quantum Physics
Everything You Need to Know About Bell's Theorem
What the Compton Effect Is and How It Works in Physics
The Casimir Effect
What Is Quantum Optics?

Schrödinger's cat: The favorite, misunderstood pet of quantum mechanics

Reference article: A brief, simple explanation of Schrödinger's cat.

Artist's depiction of Schrödinger's cat.

The thought experiment known as Schrödinger's cat is one of the most famous, and misunderstood, concepts in quantum mechanics . By thinking deeply about it, researchers have come to spectacular insights about physical reality.

Who came up with Schrödinger's cat?

The Austrian physicist Erwin Schrödinger, who helped found the discipline of quantum mechanics, first conceived of his feline conundrum in 1935 as a commentary on problems originally posed by the luminary Albert Einstein, according to an article in Quanta Magazine .

While developing their new understanding of the subatomic realm, most of Einstein and Schrödinger's colleagues had realized that quantum entities exhibited extremely odd behaviors. The Danish physicist Niels Bohr championed an understanding that particles like electrons did not have well-defined properties until they were measured. Before that, the particles existed in what's known as a superposition of states, with, for example, a 50% chance of being oriented "up" and a 50% chance of being oriented "down."

Einstein, in particular, did not like this indecisive explanation. He wanted to know how, exactly, the universe knows that someone is measuring something. Schrödinger highlighted this absurdity with his notorious conceptual cat.

Suppose one builds a strange contraption, Schrödinger wrote in a 1935 paper called " The Current Situation in Quantum Mechanics ." The apparatus consists of a box with a sealed vial of cyanide, above which is suspended a hammer attached to a Geiger counter aimed at a small lump of mildly radioactive uranium. Inside the box, there's also a kitty (and remember, this is a thought experiment that's never actually been carried out).

The box is sealed, and the experiment is left to run for some set amount of time, perhaps an hour. In that hour, the uranium, whose particles obey the laws of quantum mechanics, has some chance of emitting radiation that will then be picked up by the Geiger counter, which will, in turn, release the hammer and smash the vial, killing the cat by cyanide poisoning.

According to folks like Bohr, until the box is opened and the cat's status is "measured," it will remain in a superposition of both living and deceased. People like Einstein and Schrödinger balked at such a possibility, which doesn't accord with everything our ordinary experience tells us — cats are either alive or dead, not both at the same time.

"[Q]uantum physics lacked an important component, a story about how it lined up with things in the world," wrote science journalist Adam Becker in his book " What Is Real? " (Basic Books, 2018). "How does a phenomenal number of atoms, governed by quantum physics, give rise to the world we see around us?"

Is Schrödinger's cat real?

Schrödinger's cat cut to the heart of what was bizarre about Bohr's interpretation of reality: the lack of a clear dividing line between the quantum and everyday realms. While most people think it provides an example in support of particles lacking clearly-defined properties until they are measured, Schrödinger's original intention was the exact opposite—to show that such an idea was nonsensical. Yet, for many decades, physicists largely ignored this problem, moving on to other quandaries.

But starting in the 1970s, researchers were able to show that quantum particles can be created in states that always correspond to one another — so if one shows an "up" orientation, the other will be "down" — a phenomenon that Schrödinger called entanglement. Such work has been used to underpin the emerging field of quantum computing , which promises to produce calculating machines that are far faster than current technologies.

In 2010, physicists also managed to create a real-world version of Schrödinger's cat , albeit in a way that doesn't involve felicide (aka, kitty murder). University of California, Santa Barbara, scientists built a resonator, basically a tiny tuning fork, the size of the pixel on a computer screen. They put it into a superposition in which it was both oscillating and not oscillating at the same time, showing that relatively large objects can occupy bizarre quantum states.

More-recent experiments have put groups of up to 2,000 atoms in two different places at the same time , further blurring the dividing line between the microscopic and macroscopic. In 2019, researchers at the University of Glasgow even managed to take a photo of entangled photons using a special camera that snapped a picture whenever a photon showed up with its entangled partner.

While physicists and philosophers have yet to agree on how to think about the quantum world, Schrödinger's insights have produced many fruitful research avenues and are likely to continue doing so for the foreseeable future.

Additional resources:

Read how one physicist reconciles the conundrum of Schrödinger's cat, from The Conversation .
Learn more about the basics of quantum mechanics from Stanford University .
Watch "The Real Meaning of Schrödinger's Cat," from Ask A Spaceman, with Paul Sutter .

Sign up for the Live Science daily newsletter now

Get the world’s most fascinating discoveries delivered straight to your inbox.

Adam Mann is a freelance journalist with over a decade of experience, specializing in astronomy and physics stories. He has a bachelor's degree in astrophysics from UC Berkeley. His work has appeared in the New Yorker, New York Times, National Geographic, Wall Street Journal, Wired, Nature, Science, and many other places. He lives in Oakland, California, where he enjoys riding his bike.

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18 September 2018

Reimagining of Schrödinger’s cat breaks quantum mechanics — and stumps physicists

Davide Castelvecchi

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In the world’s most famous thought experiment, physicist Erwin Schrödinger described how a cat in a box could be in an uncertain predicament. The peculiar rules of quantum theory meant that it could be both dead and alive, until the box was opened and the cat’s state measured. Now, two physicists have devised a modern version of the paradox by replacing the cat with a physicist doing experiments — with shocking implications.

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Nature 561 , 446-447 (2018)

doi: https://doi.org/10.1038/d41586-018-06749-8

Frauchiger, D. & Renner, R. Nature Commun. 9 , 3711 (2018).

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What is Superposition? Schrödinger’s Cat Experiment Explained

The tale of physics’ most famous cat is one that is familiar to many, but what is the inside story of the feline so demanding it requires its own universe, and how does it illustrate the 'weirdness' of the quantum world.

Home → Features → Natural Sciences → Physics → Quantum Mechanics

The tale of physics’ most famous cat is one that is familiar to many, but what is the inside story of the feline so demanding it requires its own Universe, and how does it illustrate the 'weirdness' of the quantum world?

Of all the counter-intuitive elements of quantum physics introduced to the public since its inception in the early days of the twentieth century, it is quite possible that the idea that a system can be two (or more) contradictory things at once, could be the most challenging.

As well as defying a well-known aspect of logic — the law of non-contradiction — thus irritating logisticians, this idea of the coexistence of states, or superposition, was even a challenge to the fathers of quantum physics. Chief amongst them Erwin Schrödinger, who suggested a diabolical thought experiment that would show what he believed to the ludicrous nature of a system existing in contradictory states.

The thought experiment would go on to become perhaps the most well-known in the history of physics, weaving its way on to witty t-shirts, hats, bags and badges, infiltrating pop-culture, TV and film. This is the strange tale of Schrödinger’s cat, and what it can teach us about quantum physics and the nature of reality itself.

Before delving into the experiment that Schrödinger devised, it is worth examining the circumstances that led him to consider the absurd situation of a cat that is both living and dead at the same time.

Wanted: Dead or Alive! How the cat got put in the box

In many ways, Erwin Schrödinger’s place in the history of quantum mechanics is overshadowed by his feline-based thought experiment. The Austrian physicist was responsible for laying the foundation of a theoretical understanding of quantum physics with the introduction of his eponymous wave equation in 1926. As Joy Manners describes in the book ‘Quantum Physics: An Introduction’ :

“The Schrödinger equation did for quantum mechanics what Newton’s laws of motion had done for classical mechanics 250 years before.” Joy Manners, Quantum Physics: An Introduction

What Schrödinger’s equation shows is that the state of a system — the collection of all of its measurable qualities — can be described as a wavefunction — represented by the Greek letter Psi (Ψ). This wavefunction contains all the information of a system that it is possible to hold. Each wavefunction is a solution to Schrödinger’s equation, but here’s the crazy part; two wavefunctions can be combined to form a third, and this resultant wavefunction can contain completely contradictory information.

When the wavefunctions of a system are combined it is in a ‘superposition’ state. There is also no limit no how many of these wavefunctions cam be combined to form a superposition.

Yet, infinite though a wavefunction can be, eternal it is not. The act of taking a measurement on the system in question seems to cause the wavefunction to collapse — something there is as yet no physical or mathematical description for. There are, however, interpretations of what happens, which go to the very heart of reality.

Before tackling these interpretations, first, we should get to our cat in the box before he gets too impatient.

A most diabolical device

It was in 1935, whilst living in Oxford fleeing the rise of the Nazis, that Schrödinger first published an article that expressed his concern with the idea of measurement, wave function collapse, and contradictory states in quantum mechanics. Little would he know, it would lead to him becoming history’s most infamous theoretical-cat-assassin.

Below Schrödinger describes the terrible predicament that his unfortunate moggy finds himself in.

“A cat is placed in a steel chamber with the following hellish contraption… In a Gieger counter a tiny amount of a radioactive substance, so that maybe within an hour one of the atoms decays, but equally probable is that no atom decays…”

So, there is a 1/2 chance that an atom of the substances decays and causes the Gieger to tick over the hour duration of the experiment.

“If one decays the counter triggers a little hammer which breaks a container of cyanide.”

So, if the atom decays over the hour, the cat is killed. If it doesn’t, the cat survives. Treating the box and the cat as a quantum system how would we describe its wavefunction (Ψ)?

The wavefunction of the system now exists in a superposition of the individual wavefunction that describes the cat as being alive, and the one that declares it dead. According to the rules of quantum physics, the cat is currently both dead and alive.

Our unfortunate feline isn’t doomed to live out its existence as some bizarre quantum zombie, though. A quick peek inside the box constitutes a measurement of the system. Thus, by opening the box we collapse the wavefunction and determine the fate of Schrödinger’s cat. It really is curiosity that kills the cat, in this case.

Let’s end our analogy on a happy note. We open our box and fortunately the substance has not undergone decay. The cyanide bottle remains intact. Our moggy survives, unscathed if irritated. The wavefunction collapsed leaving the blue sub-wavefunction intact, but what actually just happened here? How was the cat’s fate determined?

The short answer is, we don’t know, but we have some interpretations. Next, we compare the two most prominent.

Way more than nine lives. The many-worlds interpretation

What we have discussed thus far consists of a very rough description of the Copenhagen interpretation of quantum mechanics. The reason it’s common sense to present this first is that it is generally the interpretation that is most widely accepted and taught.

As you’ve seen, the Copenhagen interpretation describes a system with no established values until a measurement occurs or is taken and a value — in our case ‘alive’ — emerges. If this sounds deeply unsatisfactory, well, it is. One of the questions it leaves open is ‘why does the wavefunction collapse?’ In 1957, an American physicist Hugh Everett III, asked a different question: ‘What if the wavefunction doesn’t collapse at all? What if it grows?’ From this emerged Everett’s ‘relative state formulation’, better known to fans of science fiction, comic books and fantasy as the ‘Many Worlds Hypothesis/interpretation’.

Below we see what happens to the wavefunction in the Copenhagen interpretation. The box is opened and the wavefunction collapses.

So what happens in the ‘many worlds’ interpretation? Rather than collapsing, as the box is opened the wavefunction expands. The cat does not cease to be in a superposition, but that superposition now includes the researchers and the very universe they inhabit. We become part of the system.

In the many-worlds interpretation, the researchers do not open the box to discover if the cat is dead or alive, they open the box to see if they are in the universe where the cat survived or the universe in which it was dispatched. They and their world have become part of the wavefunction. An entirely new universe in superposition with the old. The only difference.

One less cat.

Schrodinger’s Kittens: Some words of caution

Again, as with the Copenhagen interpretation, there is no real experimental evidence of many worlds concept. In many ways, any interpretation of quantum mechanics is really more a realm of philosophy than science. Also, when considering ‘many worlds’ it’s worth noting that this is a different concept than the idea of a ‘multiverse’ of different universes created at the beginning of time.

Further to this, there are some real problems with considering the ‘cat in a box’ as a quantum system. Researchers are constantly finding quantum effects in larger and larger systems, the current record seems to be 2,000 atoms placed in a superposition. To put that into perspective; a humble cat treat contains around 10²² atoms!

Many physicists have suggested reasons why larger systems fail to display quantum effects, with Roger Penrose suggesting that any system that has enough mass to affect space-time via Einstein’s theory of general relativity can’t be isolated. Via the influence of gravity, it is constantly having ‘measurements’ taken. This would definitely apply to even the most minuscule moggy.

It is worth noting here that the general description of the thought experiment and the opening of the box has led some to speculate that it is the addition of a ‘consciousness’ that actually causes the wavefunction collapse.

This is an idea that has sold a million or so books on ‘quantum woo’ and it arises from the unfortunate nomenclature of quantum physics. The use of the words ‘measure’ and ‘observe’ imply the intervention of a conscious observer. The truth is that any interaction with another system is enough to collapse a quantum wavefunction, as they tend to exist in incredibly delicate, easily disturbed states.

Sources and further reading

Schrödinger. E,

Griffiths. D. J, ‘Introduction to Quantum Mechanics,’ [2017], Cambridge University Press.

Broadhurst. D, Capper. D, Dubin. D, et al, ‘Quantum Physics: An Introduction,’ [2008], Open University Press.

Nomura. Y, Poirer. B, Terning. J, ‘Quantum Physics, Mini Black Holes, and the Multiverse,’

Orzel. C, ‘How to Teach Quantum Physics to your Dog,’ [2009], Simon & Schuster.

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©Lorenzo Ranieri Tenti

Why Schrödinger's Cat is still the most controversial thought experiment in science

Nearly a century after its formulation, the paradox remains hotly debated among researchers.

Dr Katie Mack

One of the most important tools in the theoretical physicist’s toolkit is the thought experiment. If you study relativity, quantum mechanics , or any area of physics applying to environments or situations in which you cannot (or should not) place yourself, you’ll find that you spend a lot more time working through imaginary scenarios than setting up instruments or taking measurements.

Unlike physical experiments, thought experiments are not about collecting data, but rather about posing an imaginary question and working through an ‘if/then’ logical sequence to explore what the theory really means.

Asking “what has to happen if the theory is true?” is invaluable for developing intuition and anticipating new applications. In some cases, a thought experiment can reveal the deep philosophical implications of a theory, or even present what appears to be an unsolvable paradox.

Probably the most famous of all physics thought experiments is that of Schrödinger’s Cat – both because it involves (purely hypothetical!) carnage, and because its implications for the nature of reality in a quantum world continue to challenge students and theorists everywhere.

The basic – again, purely hypothetical – experimental setup is this. Imagine you have a radioactive material in which there is a 50 per cent chance of a nuclear decay in some specified amount of time (let’s say, one hour).

You put this material in a box along with a small glass vial of poison and a device that will break the vial if a radioactive decay is detected. Then, you put a live cat in the box, close the lid, wait an hour, and then open the box once again.

Based on this setup, it’s straightforward to deduce that since the chance the atom decays and triggers the poison is 50 per cent, half the time you do the experiment, you should find a living cat, and half the time, you should find a dead one, assuming you’re not re-using the same cat each time.

But when Erwin Schrödinger described the thought experiment to Albert Einstein in 1935, he did so to highlight an apparent consequence of quantum theory that seemed to both scientists to be complete nonsense: the idea that before you open the box, the cat is both alive and dead at the same time.

Ultimately, it comes down to the principle of uncertainty in quantum mechanics. Unlike classical mechanics (the kind of physics that applies to our everyday experiences), in quantum mechanics, there seems to be a fundamental uncertainty built into the nature of reality.

When you flip a coin (a classical event), it’s only “random” because you’re not keeping careful enough track of all the motions and forces involved. If you could measure absolutely everything, you could predict the outcome every time – it’s deterministic.

But in the quantum mechanical version of a coin flip, the radioactive decay, nothing you measure can possibly tell you the outcome before it occurs. As far as an outside observer is concerned, until the measurement of the quantum coin flip occurs, the system will act like it’s in both states at once: the atom is both decayed and not decayed, in what we call a superposition.

Superposition is a real phenomenon in quantum mechanics, and sometimes we can even use it to our advantage. Quantum computing is built on the idea that a quantum computer bit (or qubit), instead of being just one or zero, can be in a superposition of one and zero, massively increasing the computer’s ability to do many complex calculations at once.

In the case of Schrödinger’s Cat, the apparently absurd conclusion that the cat is both alive and dead comes from considering the whole apparatus – the atom, the trigger device, and the poison vial, and the cat – to be a single quantum system, each element of which exists in a superposition.

The atom is decayed and not, the device is triggered and dormant, the vial is broken and intact, and the cat is therefore simultaneously dead and alive, until the moment the box is opened.

Whether this conclusion is actually absurd is an open question. What both Schrödinger and Einstein concluded was that true, fundamental uncertainty simply cannot apply to the real, macroscopic, world. These days, most physicists accept that uncertainty is real, at least for subatomic particles, but how that uncertainty 'collapses' when a measurement is made remains up for debate.

In one interpretation, any measurement that’s performed fundamentally alters reality – though it is usually argued that the trigger device, or, at least, the cat itself, provides a measurement for that purpose. In another interpretation, called Many Worlds, the entire Universe duplicates itself every time a quantum coin is flipped, and the measurement simply tells you whether you’re in the dead-cat or alive-cat universe from now on.

While we can’t say how long it will take before we fully understand what’s really going on in the black box of quantum superposition, applications of quantum theory are already bringing us incredible technological advances, like quantum computers. And in the meantime, clever thought experiments allow us to follow our curiosity, without running the risk of killing any cats.

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Physicists Have Finally Figured Out a Way to Save Schrödinger's Cat

The famous cat-in-a-box thought experiment by Austrian physicist Erwin Schrödinger is an illustration of one of the defining characteristics of quantum mechanics - the unpredictable behaviour of particles at the quantum level.

It makes working with quantum systems incredibly difficult; but what if we could make quantum predictions? A team of physicists believes it's possible. In a new study, they have demonstrated their ability to predict something called a quantum jump, and even reverse the process after it's started.

They have, they said, 'saved' Schrödinger's cat.

But first, a quick refresher on who Schrödinger's cat even is. The physicist imagined the scenario thus: There is a cat, in a closed box. Also in the box is a source of radioactive decay, a Geiger counter, and a sealed flask of poison. If the Geiger counter detects the radioactive decay of a single atom, it shatters the poison flask, which kills the cat.

There's no way to peer inside, so you can't know if the cat is alive or dead. It exists in a state of both, until you open the box. The instant you do so, it is immediately either one or the other, completely at random, and can no longer be both at the same time.

This whole imaginary setup is a metaphor for something called quantum superposition, whereby a particle (such as an atom, or an electron, or a photon) can exist in multiple energy states at the same time - right up until the point at which you observe it.

Once it's observed, its sudden, random transition between energy states is known as a quantum jump.

And it's this jump that physicists have now been able not just to predict, but manipulate, deliberately changing the outcome. The researchers, led by a team at Yale University, did so using artificial atoms called qubits, which are also used as the basic units of information in a quantum computer .

Every time you measure a qubit, it performs a quantum jump. These are unpredictable in the long run, which can cause problems in quantum computing .

"We wanted to know if it would be possible to get an advance warning signal that a jump is about to occur imminently," said physicist Zlatko Minev of Yale University .

The team designed an experiment to indirectly observe a superconducting qubit, using three microwave generators to irradiate the qubit in a sealed 3D enclosure made of aluminium.

This microwave radiation switches the qubit between energy states, while another beam of microwave radiation monitors the box. When the qubit is in a ground state, the microwave beam produces photons. A sudden absence of photons means that the qubit is about to make a quantum jump into an excited state.

The research showed that it wasn't so much a jump as a transition; not a flick of a switch, but the slide of a lever, perhaps.

Hence another, perfectly timed pulse of radiation can reverse the quantum jump after it has been detected, sending the qubit back to its ground state; or, to lean on the Schrödinger's cat metaphor, prevent the cat from dying (excited) and bring it back to life (ground).

There's still a long-term unpredictability; the researchers can't, for example, predict exactly when a quantum jump is going to occur. It could be in five minutes, or five hours.

But once the jump has started, it always follows the same path. Across 6.8 million jumps the team observed, the pattern was consistent.

"Quantum jumps of an atom are somewhat analogous to the eruption of a volcano," Minev said . "They are completely unpredictable in the long term.

"Nonetheless, with the correct monitoring we can with certainty detect an advance warning of an imminent disaster and act on it before it has occurred."

The research has been published in Nature .

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What counts as "observation" in Schrödinger's Cat, and why are superpositions possible?

So if I understood correctly, Schrödinger's Cat is a thought experiment that puts a cat inside a box, and there's a mechanism that kills the cat with 50% probability based on a quantum process. The argument is that the cat now must be in a superposition of dead and alive.

This makes sense at first, but the state of the cat inside the box will affect the outside world in an observable way, right? For example if the cat dies, it might meow loudly which would be audible. If it didn't meow, it would produce a thud on the ground when it dies. And even if the ground was very solid, the redistribution of mass inside the box will affects its gravity field which means the whole universe theoretically immediately observe's the cat's death.

So extending this argument to all superpositions, the different states would cause different effects on the rest of the universe, usually a slight change in the gravity field is the minimum. This gravity perturbation would propagate throughout the universe, and even all the experimenters go to sleep with thick, thick earplugs, somebody or something in the universe is going to inadvertently observe the event and the superposition immediately collapses. Thus superpositions cannot exist beyond an extremely short amount of time .

What's wrong with my reasoning?

quantum-mechanics
schroedingers-cat

7 Answers 7

Nothing! In fact you have more or less described decoherence . The idea is that any system inevitably interacts with its environment, and the more degrees of freedom the system has, i.e. the more complex it is, the faster it will interact with the rest of the universe and the superposed states will decohere.

2 $\begingroup$ I don't think this addresses the issue. A decoherent superposition is still a superposition. The decoherence of the cat would be relevant if you were trying to diffract the cat through a double slit. Decoherence can be eliminated in principle. The fundamental issue raised by Schrodinger's cat is the possibility of nonclassical correlations between things that are separated from each other by macroscopic distances. This possibility is a fundamental type of weirdness in quantum mechanics. $\endgroup$ – user4552 Commented May 4, 2013 at 16:13
2 $\begingroup$ @BenCrowell You forget that the Physicist making the experiment is himself Decoherent. $\endgroup$ – Kile Kasmir Asmussen Commented Jun 21, 2013 at 2:31

You don't explicitly say so, but you're assuming the Copenhagen interpretation (CI) rather than the many-worlds interpretation (MWI).

Your analysis is a perfectly good example of why the CI doesn't fundamentally make much sense. The CI treats measurement as a process that's different from other processes, even though measurement is a physical interaction that proceeds according to the same laws of physics as any other process. The CI says that measurement has the magic power to collapse the wavefunction, but that doesn't make sense because measurement isn't different from other physical processes. There is no fundamental distinction between a process in which a human looks inside the box and a process in which the cat interacts with the outside world through some other mechanism (the meow or the disturbance in the gravitational field).

The distinction between measurement and other processes is a psychological one, not a fundamental physical one, and the CI succeeds because it does a good job of describing the psychological experience of making a measurement.

7 $\begingroup$ +1 Best argument against CI I've seen yet. Unfortunately I really dislike MWI too! $\endgroup$ – Brandon Enright Commented May 4, 2013 at 16:42
$\begingroup$ @BrandonEnright CI is a kludge, but it is a very useful and tested kludge that allows us to do complex, sensitive experiments and interpret the results we see. I don't understand how MW allows one to interpret the results of laboratory experiments in a practical way (end rant). $\endgroup$ – Jason A Commented May 4, 2013 at 18:21
5 $\begingroup$ The fact that CI isn't perfect doesn't mean MWI is the right one. $\endgroup$ – Martino Commented May 4, 2013 at 20:44
$\begingroup$ @JasonA: I agree that CI is a useful and tested kludge. However, I don't think that it's necessary to give experiments an interpretation, if "interpretation" means a psychologically compelling story about the experiment we've just done. MWI just isn't psychologically compelling because we can't feel our own brains to be in a superposition of states. $\endgroup$ – user4552 Commented May 4, 2013 at 21:10
1 $\begingroup$ @EricDong: I don't think that's a correct characterization of MWI. MWI doesn't describe the universe as undergoing bifurcations at discrete moments in time, although people may depict it that way cartoonishly. $\endgroup$ – user4552 Commented May 5, 2013 at 14:31

I have always disliked this thought experiment because, even though it was proposed as an amplifier of quantum mechanical effects, it is really nothing more than a game on probability, and one can get random probabilities by many classical means.

Toss a coin, heads cat alive tails cat dead. The concept of both alive and dead is ridiculous in the macroscopic context. Certainly the cat would not care if it were a quantum mechanical or classical poison machine.

It appeals to people who cannot wrap their head around the concept that the square of the QM wave-function predicts a probability distribution in (x,y,z,t) for finding the whole particle at that (x,y,z,t), not a fraction of it. It says nothing about the particle being spread out all over the place: we know nothing until a measurement tells us, and in the case of the cat it is just an inhumane detector. An on-off light as a QM detector would do instead, it either will be be on or off: the neither on or off concept is ridiculous and unscientific, even if one were not looking at the light..

$\begingroup$ The cat might care, since the coin is large enough that we can predict its motion, given enough information, using completely deterministic Newtonian physics to a sufficiently accurate degree to predict head/tails. Or so I think ;) $\endgroup$ – ithisa Commented May 6, 2013 at 1:13

In my view you've muddied the waters. The cat is assumed to be unobservable. But if you allow sight and sound, then you are in fact observing the cat and the corresponding superimposition of wave functions will collapse.

If you want to worry about something, imagine the cat in a cage embedded in a wall but visible from both sides of the wall. On one side the cage is covered and the usual observers are present. They describe the cat as having a superimposition of wave functions. Now on the other side (and the two sides are not in communication) the cat is perfectly visible. In that case the cat is described by a single "pure state" wavefunction at all times. If the cat dies during the period of observation, those watching the cat describe the change in wavefunction as a change in state, much as we'd describe the electron in a hydrogen atom moving from energy level to energy level.

So in this situation we have TWO different but equally valid quantum descriptions for the cat. Rationalize this!

Superpositions can exist without problem until infinity. Basically everything including me only exists if your look (measure it). QM is very weired and that why most who are responsible for QM like Schrödinger and Einstein felt very uncomfortable with its philosophical side effects. Thats where the cat comes in. From the scientist point of view it does matter when its decided if the cat dies or not.

The box is of course supposed to be "closed" such that any observations that may be collected "at the outside" allow the conclusion that "the cat is inside, not outside", but under no circumstance any characterization of the cat in terms of "live or dead" or "having survived or having died".

A " meow from the box", however loud and shrill and indeed unavoidably audible "at the outside", is in this sense not supposed to be in any way indicative of whether or not the cat is about to expire; a " thud on the ground " is meant to be attributable to a "cat having fallen dead" just as well as to a "cat having fallen asleep, but living on".

The suitably idealized measurement operators "fate of the cat" (with value range "having survided" or "having died") and "confinement of the cat" (with value range "inside the box" or "outside the box") are meant to be strictly incompatible operators. Observations which are sufficient for determining the "fate of the cat" should therefore in turn not in any way indicate whether the cat "has been entirely inside the box, or outside the box". Just as the state of "being in the box" can formally be expressed as superposition of "having survived" and "having died" (and correspondingly the state of "being outside the box", too), the state of "having survived" should be formally expressible as superposition of "being in the box" and "being outside" (and likewise the state of "having died".

Specificly, after lifting the lid of the box (and vigorously shaking it, just in case), and again closing the lid, the cat might in any case be found "outside the box"; and it might then count as "having survided" if, after again lifting and then closing the lid even repeatedly it would at least sometimes be found again "inside the box"; or correspondingly as "having died in the box" if, after lifting and closing the lid repeatedly, it would always be found "outside the box".

What counts as “observation” in Schrödinger's Cat

When considering any particular measurement operator one can distinguish the (sets of) observations which allow some particular value to be derived as "result of the measurement", by applying the operator under consideration on one hand, and on the other hand any other (set of) observations. Both cases may include observations which were collected in actual trials as well as hypothetical descriptions of observations.

As sketched above, the (actual, or hypothetically imaginable) sets of observations which count towards determining whether "the cat is inside" or "the cat is outside" are different from the (actual, or hypothetically imaginable) sets of observations which count towards determining whether "the cat had survided" or "the cat had died".

And of course there are many other (actual, or hypothetically imaginable) observations which have no relevance to either determination.

and why are superpositions possible?

The salient description of the state of the cat before the lid had been lifted is of course "the cat is inside, not outside", which is an eigenstate of the "confinement operator". Expressing this state instead as "half surviving and half dead, with a suitable phase between these parts" makes the relation to eigenstates of the "fate operator" explicit, and depends on the relations between the correspondingly relevant sets of observations.

So -- writing some particular state as superposition is certainly possible as an abstract expression. However, and here I believe to side with Schrödinger, it seems unpalatable to consider any formal superposition if it couldn't be primarily understood as eigenstate of a suitable operator.

Based on past experience and researching Schroëdinger's cat and superpositions, I would say that this is incorrect. Hearing a sound wave would technically be observation, and so would a photon of light(the redistribution of mass inside the box), so your points would be valid, except that they completely corrupt the experiment.

3 $\begingroup$ I'm not exactly sure what the main point of the answer is, but hearing a sound wave from the cat is an observation that confirms it is alive. $\endgroup$ – David Z Commented Jun 20, 2013 at 17:22
$\begingroup$ When I say sound wave, I mean the supposed thud from the cat, or the loud meow before it dies. $\endgroup$ – user1861805 Commented Jun 22, 2013 at 14:09

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August 9, 2024

Experiments Prepare to Test Whether Consciousness Arises from Quantum Weirdness

Researchers wish to probe whether consciousness has a basis in quantum mechanical phenomena

By Hartmut Neven & Christof Koch

Human brain, Neural network, Artificial intelligence and idea concept

nopparit/Getty Images

The brain is a mere piece of furniture in the vastness of the cosmos, subject to the same physical laws as asteroids, electrons or photons. On the surface, its three pounds of neural tissue seem to have little to do with quantum mechanics , the textbook theory that underlies all physical systems, since quantum effects are most pronounced on microscopic scales. Newly proposed experiments, however, promise to bridge this gap between microscopic and macroscopic systems, like the brain, and offer answers to the mystery of consciousness.

Quantum mechanics explains a range of phenomena that cannot be understood using the intuitions formed by everyday experience. Recall the Schrödinger’s cat thought experiment , in which a cat exists in a superposition of states, both dead and alive. In our daily lives there seems to be no such uncertainty—a cat is either dead or alive. But the equations of quantum mechanics tell us that at any moment the world is composed of many such coexisting states, a tension that has long troubled physicists.

Taking the bull by its horns, the cosmologist Roger Penrose in 1989 made the radical suggestion that a conscious moment occurs whenever a superimposed quantum state collapses. The idea that two fundamental scientific mysteries—the origin of consciousness and the collapse of what is called the wave function in quantum mechanics—are related, triggered enormous excitement.

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Penrose’s theory can be grounded in the intricacies of quantum computation . Consider a quantum bit, a qubit, the unit of information in quantum information theory that exists in a superposition of a logical 0 with a logical 1. According to Penrose, when this system collapses into either 0 or 1, a flicker of conscious experience is created, described by a single classical bit.

Penrose, together with anesthesiologist Stuart Hameroff, suggested that such collapse takes place in microtubules , tubelike, elongated structural proteins that form part of the cytoskeleton of cells, such as those making up the central nervous system.

These ideas have never been taken up by the scientific community as brains are wet and warm, inimical to the formation of superpositions, at least compared to existing quantum computers that operate at temperatures 10,000 times colder than room temperature to avoid destroying superposition states.

Penrose’s proposal suffers from a flaw when applied to two or more entangled qubits. Measuring one of these entangled qubits instantaneously reveals the state of the other one, no matter how far away. Their states are correlated, but correlation is not causation, and, according to standard quantum mechanics, entanglement cannot be employed to achieve faster-than-light communication. However, per Penrose’s proposal, qubits participating in an entangled state share a conscious experience. When one of them assumes a definite state, we could use this to establish a communication channel capable of transmitting information faster than the speed of light, a violation of special relativity.

In our view, the entanglement of hundreds of qubits, if not thousands or more, is essential to adequately describe the phenomenal richness of any one subjective experience: the colors, motions, textures, smells, sounds, bodily sensations, emotions, thoughts, shards of memories and so on that constitute the feeling of life itself.

In an article published in the open-access journal Entropy , we and our colleagues turned the Penrose hypothesis on its head, suggesting that an experience is created whenever a system goes into a quantum superposition rather than when it collapses. According to our proposal, any system entering a state with one or more entangled superimposed qubits will experience a moment of consciousness.

You, the astute reader, must by now be saying to yourself: But wait a minute here—I don’t ever consciously experience a superposition of states. Any one experience has a definitive quality; it is one thing and not the other. I see a particular shade of red, feel a toothache. I don’t simultaneously experience red and not-red, pain and not-pain.

The definitiveness of any conscious experience naturally arises within the many-worlds interpretation of quantum mechanics . A metaphysical position first put forward by physicist Hugh Everett in 1957, the many-worlds view, posits time’s evolution as an enormously branched tree, with every possible outcome of a quantum event splitting off its own universe. A single qubit entering a superposition gives birth to two universes, in one of which the qubit’s state is 0 while in a twin universe everything is identical except that the qubit’s state is 1.

Entanglement potentially offers something else for brain scientists by providing a natural solution to what is called the binding problem, the subjective unity of every experience that has long posed a key challenge to the study of consciousness. Consider seeing the Statue of Liberty: her face, the crown on her head, the torch in her raised right hand, and so on. All these distinctions and relationships are bound together into a single perception whose substrate might be numerous qubits, all entangled with each other.

To make these esoteric ideas concrete, we propose three experiments that would increasingly shape our thinking on these matters. The first experiment, progressing right now thanks to funding from the Santa Monica–based Tiny Blue Dot Foundation, seeks to provide evidence of the relevance of quantum mechanics to neuroscience in two very accessible test beds: tiny fruit flies and cerebral organoids, the latter lentil-sized assemblies of thousands of neurons grown from human-induced pluripotent stem cells. It is known that the inert noble gas xenon can act as anesthetic in animals and people. Remarkably, an earlier experiment claimed that its anesthetic potency, measured as the concentration of the gas that induces immobility, depends on the specific isotopes of xenon. Two isotopes of an element contain the same number of positively charged protons but different numbers of noncharged neutrons in their nuclei. The chemical properties of isotopes—that is, what they interact with—are similar, by and large, even though their masses and magnetic properties differ slightly.

If fruit flies and organoids can be used to detect different xenon isotopes, the hunt will be on for the exact mechanisms by which a gas that is inert and that remains aloof from binding to proteins or other molecules achieves this. Is it the tiny difference in the mass of these isotopes (131 versus 132 nucleons) that makes the difference? Or is it their nuclear spin, a quantum mechanical property of the nucleus? These xenon isotopes differ substantially in their nuclear spin; some have zero spin and others 1 / 2 or 3 / 2 .

These xenon experiments will inform a second follow-on experiment in which we will attempt to couple qubits to brain organoids in a way that allows entanglement to spread between biological and technical qubits. The final experiment, which at this stage is still a purely conceptual one, aims to enhance consciousness by coupling engineered quantum states to a human brain in an entangled manner. The person may then experience an expanded state of consciousness like those accessed under the influence of ayahuasca or psilocybin.

Both quantum engineering and the design of brain-machine interfaces are progressing rapidly. It may not be beyond human ingenuity to directly probe and expand our conscious mind by making use of quantum science and technology.

This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.

JD Vance says mass deportations should 'start with 1 million,' defends 'thought experiment' giving parents extra votes

The GOP vice presidential candidate discussed several issues with Jonathan Karl.

Republican vice-presidential candidate JD Vance defended his past comments on women and families without children, the Trump campaign's proposals to deport undocumented immigrants and more in a wide-ranging interview with "This Week" co-anchor Jonathan Karl, which airs in full on Sunday morning.

Despite the race tightening in recent weeks as Vice President Kamala Harris has taken over the Democratic ticket, the Ohio senator emphasized that he and Trump are "extremely confident" in their chances of winning the election.

"I think we're going to win. I also think that we have to work as hard as possible for the remainder of the election to try to persuade Americans to vote for us," Vance told Karl. "That's the name of the game."

Vance elaborates on 'pro-family' views

The senator has come under fire for repeated comments made about childless Americans, including one during an interview in July 2021 with then-Fox News host Tucker Carlson where Vance described leading Democrats including Harris as "childless cat ladies."

In a speech before a conservative group, the Intercollegiate Studies Institute, which preceded that interview, Vance also suggested that people with children should have extra votes.

"The Democrats are talking about giving the vote to 16-year-olds, but let's do this instead," Vance said in the speech. "Let's give votes to all children in this country, but let's give control over those votes to the parents of those children. When you go to the polls in this country as a parent, you should have more power."

Vance told Karl his notion was a "thought experiment” in response to Democratic proposals to allow younger voters, and not a policy stance.

MORE: Vance responds to 'childless cat ladies' backlash, claims Democrats are 'anti-family'

"Do I regret saying it? I regret that the media and the Kamala Harris campaign has, frankly, distorted what I said," he said. "They turn this into a policy proposal that I never made. … I said, I want us to be more pro-family, and I do want us to be more pro-family."

Vance added there are "policy positions behind my view that the country should become more pro-family." He went on to talk about the economic struggles that families are facing, citing the increased cost of goods, rising medical bills and other costs.

The senator said that he and Trump have a plan to lower the cost of housing and food but didn't provide details during the interview.

Trump said in an interview with Fox News last week that his solution to bringing down costs was, "We're gonna drill, baby, drill."

Trump has also advocated for more tariffs and tax cuts as part of his economic policies.

Vance responds to mass deportation plan: 'Let's start with 1 million'

The senator brought up the ongoing migrant crisis and again blamed Harris and the Biden administration's policies, such as ending "Remain in Mexico."

When asked how he and Trump would accomplish their stated goal of mass deporting as many as 20 million immigrants – a proposal experts previously told ABC News would be a "nightmare" -- Vance said they would take a "sequential approach."

"I mean do you go knock on doors and ask people for their papers? What do you do," Karl asked.

"You start with what's achievable," Vance said. "I think that if you deport a lot of violent criminals and frankly if you make it harder to hire illegal labor, which undercuts the wages of American workers, I think you go a lot of the way to solving the illegal immigration problem."

MORE: Trump again vows to deport millions of migrants. Could he really do it?

"I think it's interesting that people focus on, well, how do you deport 18 million people? Let's start with 1 million. That's where Kamala Harris has failed. And then we can go from there," Vance said.

Vance agrees with Trump that VP picks don't matter to most voters

During an interview at the National Association of Black Journalists conference in Chicago last month, and just a short time after Trump announced Vance as his running mate, the former president raised some eyebrows when asked whether Vance would be ready to be president "on Day 1" if needed.

"You can have a vice president who's outstanding in every way, and I think JD is, I think that all of them would've been, but you're not voting that way. You're voting for the president. You're voting for me," Trump said, without addressing whether Vance would be ready on "Day 1."

MORE: Video JD Vance 'absolutely' sure Trump thinks he could be president if needed

In the interview with ABC News, Vance said he agreed with Trump's view.

"They're voting for Donald Trump or for Kamala Harris, not for JD or Tim Walz," he said. "I also think that he's right that the politics of this really don't matter that much."

However, Vance stressed he's "absolutely" sure Trump is confident he could step up as a commander in chief if needed.

"What I think that he does believe because he made it the main focus of his vetting process, is, 'Do I think this person can be president on day one if, God forbid, something happens? Yes,'" Vance said.

Vance repeats false claims about Tim Walz's policies

During a rally in Montana on Friday night, Trump pushed falsehoods about Democratic vice presidential candidate Gov. Tim Walz's policies concerning transgender youth, accusing the Minnesota governor of signing "a law letting the state kidnap children to change their gender."

Walz has signed legislation aimed at protecting the rights of transgender individuals to access gender-affirming care, which can include gender-affirming surgeries but also services like counseling and non-surgical medical procedures like hormone therapy and puberty suppressants. The law does not allow what Trump claimed.

Vance said he didn't fully watch the late-night rally but repeated some of those false claims in the interview with Karl, saying Walz "supported taking children away from their parents if the parents don't consent to gender reassignment."

He referenced Walz's recent statement at a rally accusing Republicans of not "minding their own damn business."

PHOTO: Republican vice presidential candidate Sen. JD Vance on Aug. 6, 2024, in Philadelphia | Minnesota Gov. Tim Walz, the running mate of Democratic presidential nominee Vice President Kamala Harris in Philadelphia, Aug. 6, 2024.

"One way of minding your own damn business, Jon, is to not try to take my children away from me … if I have different world views than you."

Karl pushed back, calling the "kidnapping" characterization "crazy."

The April 2023 law that Walz signed in the wake of other states curtailing or banning access to gender-affirming care has been mischaracterized by Republicans.

The Minnesota law protects patients who come to the state to receive gender-affirming health care, even if the patients live in a state where such care is illegal. The law also specifically allows the state's courts to assume "temporary emergency jurisdiction" in cross-state child custody disputes where a child has been unable to obtain gender-affirming care and is in Minnesota to do so.

The executive director of LGBTQ+ advocacy group OutFront told The Washington Post that under the law, courts can settle parental disputes over whether their child should get this care, but it doesn't result in the parent against such care losing custody of their child.

Vance pushes back on white supremacist Trump once dined with who recently insulted his wife's race

Karl also asked Vance about a racist attack targeting his wife, Usha, from white nationalist live-streamer, Nick Fuentes, who Trump dined with in November 2022.

In a recent livestream, Fuentes said, "What kind of man marries somebody named Usha? Clearly, he doesn’t value his racial identity."

MORE: JD Vance's wife faces racist online backlash from far-right social media posts

"My attitude to these people attacking my wife is, she's beautiful, she's smart. What kind of man marries Usha? A very smart man and very lucky man," Vance said of his wife during the ABC News interview. "If these guys want to attack me or attack my views, my policy views, [or] my personality, come after me. But don't attack my wife. She's out of your league."

PHOTO: Republican vice presidential nominee Sen. JD Vance and his wife Usha Vance take the stage to introduce Republican Presidential nominee former President Donald Trump during a rally on July 27, 2024, in St Cloud, Minnesota.

Trump faced significant blowback for dining with Fuentes, along with rapper Ye (formerly Kanye West) back in November 2022 at his Mar-a-Lago club in Florida. At the time, Trump said he did not know who Fuentes was and that he was brought to the dinner by Ye. In a statement given exclusively to Fox News Digital, Trump said, "I had no idea what his views were, and they weren’t expressed at the table in our very quick dinner, or it wouldn't have been accepted."

But the former president has not denounced Fuentes' white nationalist views beyond that, or the recent comments about Usha Vance.

MORE: Election 2024 updates

In the interview, Vance contended Trump had "issued plenty of condemnations," and did not question the former president's dinner with Fuentes.

"The one thing I like about Donald Trump, Jon, is that he actually will talk to anybody. But just because you talk to somebody doesn't mean you endorse their views," Vance said, adding that Trump has been close and friendly with his family.

ABC News' Quinn Scanlan contributed to this report.

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'Thought experiment': J.D. Vance furiously backpedals away from giving parents more votes

David Edwards

Senior editor, david edwards has spent over a decade reporting on social justice, human rights and politics for raw story. he also writes crooks and liars. he has a background in enterprise resource planning and previously managed the network infrastructure for the north carolina department of correction..

'Thought experiment': J.D. Vance furiously backpedals away from giving parents more votes

Republican vice presidential nominee J.D. Vance worked to do damage control over the weekend after he suggested that parents should be given more votes than single citizens.

During a Sunday interview with ABC News, host Jonathan Karl said he was putting Vance's "childless cat ladies" remark aside to focus on his proposal to give more votes to parents.

"And you said you advocated giving extra votes to people with children," Karl explained.

"Well, John, it's not a policy proposal," Vance said defensively. "It's a thought experiment, right?"

"Some Democrats had said we're going to give children the right to vote," he claimed. "And I said, well, if we're going to give the rights to the children, then we should actually just allow the parents to cast those votes, right?"

"So it's a thought experiment."

Vance admitted, "Sometimes family doesn't work out for people, and that's okay."

"You said, when you go to the polls in this country as a parent, you should have more power," Karl noted. "You should have more of an ability to speak your voice in a democratic republic than the people who don't have kids."

ALSO READ: Why ‘vanilla’ Tim Walz is the ingredient to beat Trump: Dem lawmakers

"I mean, you are directly saying that people with kids should have more of a voice in our democracy," the ABC host added. "Thought experiment or not about how that is done, but that is the principle."

"Again, John, it's a thought experiment," Vance replied, sticking to his talking points.

Watch the video below from ABC or at the link.

Stories Chosen For You

Do you think vice president kamala harris should be the next president, 'money where your mouth is': pete buttigieg pounces on j.d. vance over his family attacks.

Following an extensive CNN interview with GOP vice presidential candidate J.D. Vance , Treasury Secretary Pete Buttigieg , speaking in a personal capacity, took the Ohio Republican to task for a multitude of comments he made to "State of the Union" host Dana Bash before getting personal about Vance's beliefs about his family. Addressing Vance's remarks that Democrats are anti-family, the Indiana Democrat called out the Ohio senator for not "putting his money where his mouth is." Using Vance's criticism of "childless cat ladies," which has cast a could of his selection as a running mate by Donald Trump , as a jumping-off point, Buttigieg told the CNN host, "Let's be clear, we're the ones trying to get the Child Tax Credit expanded and J.D. Vance couldn't be bothered to show up in the Senate and vote for it and Republicans have blocked that from being expanded or it'd be the law of the land right now." "So if you want to talk about promoting children, promoting family, put your money where your mouth is," he continued. Addressing Bash's interview with Vance moments before, he elaborated, "Look, when you asked him and pressed him on whether my family was legitimate, he said yes because I think he felt shamed into it. But let's remember also, the last time I checked, he doesn't even think I should legally be able to have a family." "Now, if he really got his way in his anti-marriage equality views, I don't know if that means that he would want me and my husband to be forcibly divorced and separated from our children or if he'd be satisfied just to have us lose legal protections like the ability to do our taxes together, visit them in a hospital," he added. "I don't know exactly what his vision of us not having a family looks like, but I know that it's not pro-family for me." Watch below or at the link :

'Total loser': J.D. Vance fumes after Trump's white supremacist pal attacks his wife

Republican vice presidential nominee J.D. Vance refused to say that former President Donald Trump disavowed a white supremacist acquaintance who has reportedly made racist comments about his wife, Usha.

In an interview that aired Sunday on CBS, Vance admitted that right-wing white supremacists had attacked his family because his wife was not white.

"Well, look, it's going to follow us wherever we go, because that's the nature of public life in America, and it's disgraceful," Vance said.

The Republican nominee pivoted to place blame on Democratic presidential nominee Kamala Harris.

"I frankly think that, unfortunately, a lot of people on the left have leaned into this by trying to categorize people by skin color and then give special benefits or special amounts of discrimination," he said.

CBS host Margaret Brennan noted that white supremacist Nick Fuentes had made racist attacks on Vance's wife after dining with Donald Trump at Mar-a-Lago.

"Well, in your own movement, that's what I want to ask about," Brennan said. "Because one of the supremacists who was saying things like this about your family. Nick Fuentes, an avowed anti-Semite. Went after your wife. He had previously dined at Mar-a-Lago with Donald Trump."

ALSO READ: Tim Walz's personal finances are extraordinarily boring — and that may help Harris

"Does this have any room in your movement, in the MAGA movement?" she wondered.

"Of course, it doesn't have any room in the MAGA movement," Vance insisted without explaining Trump's association with Fuentes. "Donald Trump has criticized this person. Look, I think the guy's a total loser. Certainly, I disavow him."

Watch the video below from CBS or at the link. .

Trump’s 'political suicide' makes winning Georgia nearly 'impossible': analysis

After Donald Trump's rally at a Georgia State University arena earlier this month, the Atlanta Journal-Constitution's (AJC) Greg Bluestein reported that several Republican activists and strategists were unhappy with the former president's attacks on Georgia Governor Brian Kemp, predicting that they could even tank his campaign.

"A lot of Republicans like me might just decide not to vote at all in the presidential election because of stupid antics like tonight," former Georgia lawmaker Allen Peake told the AJC . " Trump may have just lost Georgia."

A week later, the MAGA hopeful has campaigned little to none, and given a rambling, hourlong press conference that led political experts to question his mental acuity. Furthermore, Wall Street Journal reporter Cameron McWhirter reports that Georgia GOP leaders and strategists remain unmoved and unconvinced that Trump can win the state in November.

READ MORE: 'Georgia can go either way': Expert says Harris is now erasing Trump’s lead in swing states

"Georgia Republicans, Georgia independents, and swing voters don’t want divisiveness," GOP consultant Stephen Lawson told the WSJ. "They don’t want a relitigation of 2020."

Lawson, who worked on ex-US Senator Kelly Loeffler's (R-GA) failed 2020 campaign, added: “We know exactly how this story ends. If he’s not running on the issues, he’s going to lose."

State Senator Larry Walker III — a top Georgia Republican — "called Trump’s comments 'definitely unproductive and unwarranted,' adding: 'If we continue with this kind of feud, it will make it more difficult' to win Georgia," according to McWhirter.

Veteran Georgia GOP strategist Ryan Mahoney — who believes Trump is committing "political suicide" — insisted, "We’ve seen this movie before, and the former president’s baseless and ill-advised remarks will make it damn near impossible for Republicans to prevail in November."

READ MORE: 'Cult of personality': Ex-GA lieutenant gov. warns 'Trump’s obsession with power' will destroy GOP

McWhirter reports , "A Trump spokeswoman didn’t respond to a request for comment on whether Trump and Kemp would appear together on the campaign and whether the two camps are talking. Earlier, when asked about Trump’s Atlanta speech, the spokeswoman referred to Trump’s Truth Social post criticizing Kemp."

McWhirter's full analysis can be read here (subscription required).

How Harris and Walz are fighting Trump with joy and positivity — and winning

Trump's insatiable ego is destroying the former president, lawmakers caught in controversy as congressional stock trading debate rages on.

Copyright © 2024 Raw Story Media, Inc. PO Box 21050, Washington, D.C. 20009 | Masthead | Privacy Policy | Manage Preferences | Debug Logs For corrections contact [email protected] , for support contact [email protected] .

Artificial Intelligence

Our technology-powered thought laboratory, ai and neurotech are reinventing the very nature of the thought experiment..

Posted August 8, 2024 | Reviewed by Jessica Schrader

From Plato to Einstein, thought experiments have driven major breakthroughs in science and philosophy.
AI, brain interfaces, and thought-to-text tech are poised to supercharge mental exploration.
Human-AI symbiosis promises to solve complex problems rapidly, sparking a new age of discovery.

Think about it. There may be no greater engine of transformation than the human brain. And throughout history, thought experiments have been the silent engines of intellectual progress, driving paradigm shifts in science, philosophy , and human understanding. From Plato's Allegory of the Cave to Einstein's elevator, these mental exercises have allowed thinkers to transcend the limitations of their physical world and explore the realm of pure ideas.

The power of thought experiments lies in their ability to distill complex concepts into digestible narratives, making the abstract tangible and the impossible imaginable. In ancient Greece, Zeno's paradoxes challenged our understanding of motion and infinity, laying the groundwork for calculus two millennia before its formal development. During the Scientific Revolution, Galileo's thought experiment of dropping balls from the Leaning Tower of Pisa (which he likely never actually performed) helped overturn Aristotelian physics and pave the way for Newton's laws of motion.

Revolutionizing Science and Philosophy

Perhaps no field has benefited more from thought experiments than physics. Einstein's famous musings about riding alongside a beam of light led to the development of special relativity, revolutionizing our understanding of space and time. Schrödinger's cat, a paradoxical feline both alive and dead, illuminated the bizarre implications of quantum superposition. These mental exercises have pushed the boundaries of human knowledge, allowing us to probe realms far beyond the reach of contemporary technology or experimentation.

The Dawn of Neuro-Enhanced Thinking

Now, as we stand on the brink of a new technological revolution, the humble thought experiment is poised for a dramatic evolution. The convergence of brain-computer interfaces ( BCIs ) like Neuralink, "thought-to-text" technologies, and large language models (LLMs) promises to transform the landscape of intellectual exploration in ways our predecessors could scarcely have imagined.

Imagine a world where the barriers between mind and machine dissolve, where thoughts can be transmitted at the speed of neurons firing. This is the promise of advanced BCIs and thought-to-text technologies. No longer constrained by the relatively slow process of typing or speaking, this new technology could potentially transfer complex ideas, hypotheses, and entire thought experiments directly from their brains to computer systems in ways that make "the blink of an eye" seem antiquated and sluggish.

AI as the Cognitive Amplifier

Enter large language models, the artificial intelligences that have already demonstrated remarkable capabilities in processing and generating human-like text. When coupled with the rapid influx of direct "pre-language thought" input, these LLMs could serve as cognitive amplifiers of unprecedented power.

As thoughts flow directly from the mind mind into the AI system, the LLM could instantaneously expand on the initial concepts, drawing connections across vast databases of scientific knowledge. It could generate multiple variations and permutations of the original thought experiment, identify potential flaws or inconsistencies in the logic, and suggest novel approaches or angles that the human mind might not have considered.

The Expanded Laboratory of the Mind

This symbiosis of human creativity and AI processing power could create a feedback loop of innovation, with each iteration refining and elevating the original concept. In this new and startling reality, a modern-day Einstein could conceive of a thought experiment akin to riding a beam of light, and within seconds have the concept fully articulated and modeled by the AI, receive instant feedback on its implications across multiple fields of physics, see visualizations of how this thought experiment interacts with our current understanding of the universe, and explore dozens of variations and extensions of the original idea.

The potential for scientific breakthroughs in this environment is staggering. Complex problems that might have taken years of contemplation and collaboration could potentially be unraveled in days or even hours. We're not just enhancing thought experiments—we're creating an entirely new domain of intellectual exploration, a "laboratory of the mind" where the boundaries between imagination and computation blur, where abstract ideas can be manipulated, tested, and evolved with unprecedented speed and precision.

Thinking About Ethics

However, this brave new world of thought experimentation is not without its challenges and ethical considerations. Privacy concerns are paramount—how do we ensure the sanctity of one's innermost thoughts when they can be so easily externalized? There's also the question of cognitive equality—would such technology create an insurmountable gap between those with access to these advanced systems and those without?

It's also critical to consider the potential for cognitive dependency. If we rely too heavily on AI-augmented thought processes, do we risk atrophying our natural cognitive abilities? How do we maintain the uniquely human aspects of creativity and intuition in this new landscape?

Future Thought

Despite these challenges, the potential benefits of this technology are too profound to ignore. We stand at the threshold of a new Cognitive Age , one in which the constraints on human thought and creativity are dramatically loosened. This fusion of direct brain-computer interfaces, thought-to-text technology, and advanced AI could spawn a new generation of thinkers—modern-day Einsteins equipped with cognitive tools beyond anything we've seen before.

The future of thought experimentation is no longer confined to the limits of individual human cognition . Instead, it expands into a vast, collaborative space where human creativity and artificial intelligence dance in a symphony of ideas, pushing the boundaries of what's possible and redefining the very nature of thinking itself. As we stand on the shoulders of giants like Plato, Galileo, and Einstein, we prepare to take a leap into a future where the power of thought knows no bounds.

John Nosta is an innovation theorist and founder of NostaLab.

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IMAGES

Schrödinger's Cat Thought Experiment with Multiple Cats Stumps
Schrodinger's Cat In A Box Thought Experiment
10 Famous Thought Experiments That You Need To Try
The Cat In The Box Theory
Schrodinger's Cat Theory
Scheme of the Schödinger's cat thought experiment proposed in 1935 [4

COMMENTS

Schrödinger's cat
Schrödinger's cat: a cat, a flask of poison, and a radioactive source connected to a Geiger counter are placed in a sealed box. As illustrated, the quantum description uses a superposition of an alive cat and one that has died. In quantum mechanics, Schrödinger's cat is a thought experiment concerning quantum superposition.
Schrödinger's Cat Experiment and the Conundrum That Rules Modern
Long before cats conquered the internet, two of the greatest physicists of our time — Erwin Schrödinger and Albert Einstein — devised what almost seems like an evil thought experiment. It goes something like this: You have a cat in a completely sealed box impervious to any observation from outside. Inside is a kind of device involving a ...
This Twist on Schrödinger's Cat Paradox Has Major Implications for
Take his fellow physicist Erwin Schrödinger's famous thought experiment in which a cat is trapped in a box with poison that will be released if a radioactive atom decays.
Schrodinger's cat
Schrödinger's cat, thought experiment designed by theoretical physicist Erwin Schrödinger in 1935 as an objection to the reigning Copenhagen interpretation of quantum mechanics. ... Schrödinger's cat argues that, in the Copenhagen interpretation, until an observer opens the box and reveals the cat's fate, the cat is both alive and dead ...
Schrödinger's cat: A thought experiment in quantum mechanics
View full lesson: http://ed.ted.com/lessons/schrodinger-s-cat-a-thought-experiment-in-quantum-mechanics-chad-orzelAustrian physicist Erwin Schrödinger, one o...
What is Schrodinger's cat?
Schrödinger's cat. A thought experiment that highlights the strangeness of quantum theory. By Joshua Howgego. Sven Puth/EyeEm/Getty Images. Devised in 1935 by the Austrian physicist Erwin ...
What did Schrodinger's Cat experiment prove?
Schrodinger found this concept absurd and devised his thought experiment to make plain the absurd yet logical outcome of such claims. In Schrodinger's imaginary experiment, you place a cat in a box with a tiny bit of radioactive substance. When the radioactive substance decays, it triggers a Geiger counter which causes a poison or explosion to ...
What was Erwin Schrödinger's most famous thought experiment?
The Editors of Encyclopaedia Britannica. Erwin Schrödinger's most famous thought experiment became known as "Schrödinger's cat": A cat is in a box with a vial of poison. The vial breaks if an atom inside the box decays. The atom is superposed in decay and non-decay states until it is observed, and thus the cat is superposed in alive ...
Schrödinger's Cat
Schrödinger's cat is a thought experiment designed to show how certain interpretations of quantum mechanics lead to counterintuitive results. In the experiment, a cat is placed inside a box with a vial of poisonous gas. A mallet is set up such that it breaks the vial of gas if a particular radioactive atom decays, killing the cat. Since the radioactive decay is a quantum system, whether ...
The Physics Behind Schrödinger's Cat Paradox
His feline paradox thought experiment has become a pop ... proposed in 1935 in the following theoretical experiment. A cat is placed in a steel box along with a Geiger counter, a vial of poison, a ...
Schrodinger's Cat (Simplified): What Is It & Why Is It Important?
Schrödinger's Cat. In the thought experiment, Schrödinger proposed placing a cat in a box, so it was hidden from observers (you can imagine this to be a sound-proof box, too) along with a vial of poison. The vial of poison is rigged to break and kill the cat if a certain quantum event takes place, which Schrödinger took to be the decay of ...
What Is Schrödinger's Cat? (Definition, How It Works)
We often use Schrödinger's thought experiment to explain the concept of superposition. The experiment states that a hypothetical cat is locked in a box with some radioactive substance controlling a vial of poison. When the substance decays, it triggers a Geiger counter that causes the poison to be released, thereby killing the cat.
Erwin Schrödinger and the Schrödinger's Cat Experiment
He created a different thought experiment, called Schrödinger's Cat, to illustrate his concerns. In the Schrödinger's Cat experiment, a cat is placed inside a sealed box with a radioactive substance and a poisonous gas. If the radioactive substance decayed, it would release the gas and kill the cat. If not, the cat would be alive.
Here's How Schrodinger's Cat Works
Erwin Schrodinger was one of the key figures in quantum physics, even before his famous "Schrodinger's Cat" thought experiment.He had created the quantum wave function, which was now the defining equation of motion in the universe, but the problem is that it expressed all motion in the form of a series of probabilities—something which goes in direct violation to how most scientists of the ...
Schrödinger's cat: The favorite, misunderstood pet of quantum mechanics
Inside the box, there's also a kitty (and remember, this is a thought experiment that's never actually been carried out). The box is sealed, and the experiment is left to run for some set amount ...
Reimagining of Schrödinger's cat breaks quantum mechanics
In the world's most famous thought experiment, physicist Erwin Schrödinger described how a cat in a box could be in an uncertain predicament. The peculiar rules of quantum theory meant that it ...
What's the physics behind Schrodinger's Cat experiment
So, there is a 1/2 chance that an atom of the substances decays and causes the Gieger to tick over the hour duration of the experiment. "If one decays the counter triggers a little hammer which ...
Reimagining of Schrödinger's Cat Breaks Quantum Mechanics—and Stumps
In the world's most famous thought experiment, physicist Erwin Schrödinger described how a cat in a box could be in an uncertain predicament.
Schrödinger's Cat: Dead, Alive or Both? (video)
Inside this box is an adorable cat, a jar of Kitty Killer ® Gas, a hammer, and a radioactive atom. This setup was the basis for a famous thought experiment from the physicist Erwin Schrödinger, known as "Schrödinger's Cat". There's a 50% chance that the atom decays. If it does, the hammer smashes the glass and releases the poison, killing ...
Why Schrödinger's Cat is still the most controversial thought
Discover how Schrödinger's Cat, a paradoxical thought experiment, challenges our understanding of quantum physics and reality.
Schrodinger's Cat Theory
This cat in a box thought experiment was imagined by Erwin Schrodinger in 1935 in a discussion with Albert Einstein. Schrodinger was trying to illustrate to Einstein problems with the Copenhagen ...
Physicists Have Finally Figured Out a Way to Save Schrödinger's Cat
The famous cat-in-a-box thought experiment by Austrian physicist Erwin Schrödinger is an illustration of one of the defining characteristics of quantum mechanics - the unpredictable behaviour of particles at the quantum level. It makes working with quantum systems incredibly difficult; ...
What counts as "observation" in Schrödinger's Cat, and why are
So if I understood correctly, Schrödinger's Cat is a thought experiment that puts a cat inside a box, and there's a mechanism that kills the cat with 50% probability based on a quantum process. The argument is that the cat now must be in a superposition of dead and alive.
Experiments Prepare to Test Whether Consciousness Arises from Quantum
Recall the Schrödinger's cat thought experiment, in which a cat exists in a superposition of states, both dead and alive. In our daily lives there seems to be no such uncertainty—a cat is ...
JD Vance says mass deportations should 'start with 1 million,' defends
Vance told Karl his notion was a "thought experiment" in response to Democratic proposals to allow younger voters, and not a policy stance. MORE: Vance responds to 'childless cat ladies ...
'Thought experiment': J.D. Vance furiously backpedals away from giving
"Again, John, it's a thought experiment," Vance replied, sticking to his talking points. Watch the video below from ABC or at the link. 2024 Elections Media SmartNews Trump News Video
Our Technology-Powered Thought Laboratory
The power of thought experiments lies in their ability to distill complex concepts into digestible narratives, making the abstract tangible and the impossible imaginable. ... Schrödinger's cat, a ...