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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