Why is schrodingers cat a paradox

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, 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. 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. 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. All rights reserved.

Share Tweet Email. Why it's so hard to treat pain in infants. But if you dare to go and measure them — therefore determining which slit they go through — they only travel through one slit or the other, and no longer produce that interference.

It makes one thing very clear: the act of observing a quantum system can, in fact, very much change the outcome. But that, like most discoveries in physics, only brings up more questions. Under what conditions does an observation change the outcome? What constitutes making an observation? And is a human required to be an "observer," or could an inorganic, non-living measurement suffice? The results of the 'masked' double-slit experiment. Note that when the first slit P1 , the second It goes something like this:.

Is the cat dead or alive? While we might think that the cat itself is in a superposition of There's only an indeterminate probability that the atom has decayed, and therefore the atom must be in a superposition of decayed and non-decayed states simultaneously. Because the atom's decay controls the door, the door controls the food, and the food determines whether the cat lives or dies, the cat itself, then, must be in a superposition of quantum states.

Somehow, the cat is both part-dead and part-alive until an observation is made. In a traditional Schrodinger's cat experiment, you do not know whether the outcome of a quantum Inside the box, the cat will be either alive or dead, depending on whether a radioactive particle decayed or not. If the cat were a true quantum system, the cat would be neither alive nor dead, but in a superposition of both states until observed.

However, you can never observe the cat to be simultaneously both dead and alive. He didn't devise it to ask deep questions about the role of a human being in the observation process. He didn't actually claim that the cat itself would be in a superposition of quantum states, where it's part-dead and part-alive simultaneously, the way a photon appears to pass partly through both slits in the double-slit experiment.

His true purpose? To illustrate how easy it is to arrive at an absurd prediction — such as a prediction of a simultaneously half-dead and half-alive cat — if you misinterpret or misunderstand quantum mechanics. Charlie and Debbie are not actually human friends in this test. Rather, they are beam displacers at the front of each interferometer. Or she can allow the photon to continue on its journey, passing through a second beam displacer that recombines the left and right paths—the equivalent of keeping the lab door closed.

Throughout the experiment, Alice and Bob independently choose which measurement choices to make and then compare notes to calculate the correlations seen across a series of entangled pairs.

Tischler and her colleagues carried out 90, runs of the experiment. The team could also modify the setup to tune down the degree of entanglement between the photons by sending one of the pair on a detour before it entered its interferometer, gently perturbing the perfect harmony between the partners.

This result proved that the two sets of bounds are not equivalent and that the new local-friendliness constraints are stronger, Tischler says.

Each of these options has profound—and, to some physicists, distinctly distasteful—implications. She notes that physicists studying quantum foundations have often struggled to come up with a feasible test to back up their big ideas. Still, he notes, proponents of most quantum interpretations will not lose any sleep. Fans of retrocausality, such as himself, have already made peace with superdeterminism: in their view, it is not shocking that future measurements affect past results. Meanwhile QBists and many-worlds adherents long ago threw out the requirement that quantum mechanics prescribes a single outcome that every observer must agree on.

And both Bohmian mechanics and spontaneous collapse models already happily ditched locality in response to Bell. Furthermore, collapse models say that a real macroscopic friend cannot be manipulated as a quantum system in the first place. Because no physicist questions whether a photon can be put into superposition, Maudlin feels the experiment lacks bite. Tischler accepts the criticism. The most dramatic result, he says, would involve using an artificial intelligence, embodied on a quantum computer, as the friend.

Some philosophers have mused that such a machine could have humanlike experiences, a position known as the strong AI hypothesis, Wiseman notes, though nobody yet knows whether that idea will turn out to be true.

But if the hypothesis holds, this quantum-based artificial general intelligence AGI would be microscopic. So from the point of view of spontaneous collapse models, it would not trigger collapse because of its size. In turn, that conclusion would suggest that Wigner was right that consciousness causes collapse. 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.

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.