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Don't Let Yourself Get Tangled Up by These 4 Quantum Mechanics Misconceptions

The theory of quantum mechanics, which governs the microcosm of atoms and particles, unquestionably possesses the X factor.

It is bright and fascinating because, in contrast to many other branches of physics, it is strange and illogical.

Excitement and debate were sparked when Alain Aspect, John Clauser, and Anton Zeilinger were given the 2022 Nobel Prize in Physics for their work illuminating quantum mechanics.

But due to a number of enduring myths and misconceptions, discussions about quantum physics - whether they occur on chat forums, in the media, or in science fiction - may frequently become confused. I'll list four.

1. A cat can be both alive and dead.

It's unlikely that Erwin Schrödinger could have foreseen that his thought experiment, Schrödinger's cat, would become a popular internet meme in the twenty-first century.


It implies that a cat trapped in a box with a kill switch that is activated by a chance quantum event, like radioactive decay, maybe both alive and dead at the same time, provided that the box is not opened to check.

Long ago, it became clear that quantum particles might exist simultaneously in two states, such as two places. It's a superposition, that's what.


In the well-known double-slit experiment, where a single quantum particle—such as a photon or electron—can pass through two distinct slits in a wall simultaneously—scientists have been able to demonstrate this. Where did we learn that?


Each particle's state in quantum physics is also a wave. However, when we send a stream of photons through the slits one at a time, it produces a pattern on a screen behind the slit of two waves interfering with one another.

Each photon must have simultaneously passed through both slits while interfering with itself since there were no other photons for it to interfere with when it passed through the slits (image below).


An example of the double slit experiment shows two slits with a flashlight shining through them, with the light's waves passing through each slit in a different pattern.

The states (waves) in the superposition of the particle passing through both slits must, however, be "coherent"—having a clearly defined relationship with one another—for this to function.

These superposition tests can be performed on objects that are getting bigger and more complicated.


With the use of huge carbon-60 molecules known as "buckyballs," Anton Zeilinger established quantum superposition in one well-known experiment in 1999.


How does this affect our poor cat, then? If we don't open the box, is it really both living and dead at the same time?


A cat is obviously considerably larger and more intricate than a single photon in a controlled lab environment.

The trillions of trillions of atoms that make up the cat have very little time to maintain any kind of coherence with one another.


This does not imply that quantum coherence cannot exist in biological systems, only that it is unlikely to occur in large animals like cats or a human.


2. Entanglement can be explained using basic analogies

No matter how far apart they are, the quantum property of entanglement connects two separate particles so that when you measure one, you instantly and automatically know the state of the other.

Common theories for it frequently involve commonplace items from our traditional macroscopic world, including dice, cards, or even odd-colored pairs of socks.


Consider telling your pal, for instance, that you put a blue card in one envelope and an orange card in another. Your friend will know you have the orange card if they remove and open one of the envelopes and discover the blue card.


The two cards inside the envelopes must be imagined to be in a shared superposition, which means they are both orange and blue at the same time (more particularly, orange/blue and blue/orange). This is how you can grasp quantum mechanics.

One randomly chosen color is shown when one envelope is opened. But because the second card is "spookily" connected to the first, opening it always displays the opposite hue.


Similar to performing a new type of measurement, it is possible to have the cards appear in a different set of colors. We may crack open an envelope and ask, "Are you a red or a green card?"


Once more, the response would be arbitrary: green or red. But more importantly, if the cards were intertwined, the other card would always answer the identical question with the opposite result.

Albert Einstein made an attempt to use classical intuition to explain this, speculating that the cards may have been given a set of internal instructions that told them what hue to show in response to a certain query.


Additionally, he disregarded the cards' obviously "spooky" ability to quickly affect one another, as this would indicate that they were communicating at a pace faster than the speed of light, which is against Einstein's ideas.


Bell's theorem, a theoretical test developed by the physicist John Stewart Bell, and investigations carried out by the Nobel laureates of 2022 ultimately disproved Einstein's theory. It is untrue to say that measuring one entangled card alters the status of the other.

As opposed to what Einstein had believed, quantum particles are simply inexplicably connected in ways that defy logic and language. They are neither communicative or encoded, as he had believed.


Therefore, do not consider common items when thinking about entanglement.


3. Nature is fictitious and "non-local,"

Bell's theorem is frequently cited as evidence that nature isn't "local" and that a thing is affected by its surroundings indirectly as well. The idea that the characteristics of quantum things aren't "real," or that they don't exist before being measured, is another prevalent interpretation of this statement.

However, Bell's theorem only allows us to conclude that nature isn't both real and local if we make a few other simultaneous assumptions.


These presumptions include the notions that measurements only have one result (and not several, possibly in parallel universes), that cause and effect move forward in time, and that we do not live in a "clockwork universe" in which everything has been preset since the beginning of time.


In spite of Bell's theorem, nature might still be local and real if you were to allow for other deviations from what we normally take for granted, such time moving forward. Additionally, more investigation should help to focus the many possible interpretations of quantum physics.

However, most of the possibilities are at least as ludicrous as losing up on the idea of local reality, such as time going backward or there being no free will.


4. No one is familiar with quantum mechanics.

A famous saying goes, "If you think you understand quantum physics, you don't comprehend it," paraphrasing Niels Bohr in this form but ascribed to physicist Richard Feynman.


In public, many people share this opinion. Even physicists claim that it is impossible to comprehend quantum physics. However, quantum physics is not particularly mathematically nor conceptually challenging for scientists in the twenty-first century.

We fully comprehend it to the point where we can simulate incredibly complicated quantum systems, forecast quantum events with great precision, and even begin to create quantum computers.


When stated in terms of quantum information, superposition and entanglement don't require knowledge beyond high school mathematics. There is no need for any quantum physics in Bell's theorem. It may be obtained in a few lines using linear algebra and probability theory.

How to integrate quantum physics with our intuitive experience may be where the main challenge resides. We won't be prevented from developing quantum technology further even if we don't have all the solutions. We may just be silent and do the math.

For the benefit of humanity, Nobel laureates Aspect, Clauser, and Zeilinger would not stop asking why. They and others like them could one day assist in bridging quantum strangeness and our perception of reality. The Discussion

Mehul Malik, a professor of physics at Heriot-Watt University, and Alessandro Fedrizzi are also involved in this study.

A Creative Commons license has been used to republish this article from The Conversation.

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