Is quantum entanglement really beyond the speed of light?
Quantum entanglement is one of the most puzzling fields in quantum mechanics. It is an unknown field of physics, which is not clear to the public, and the knowledge structure is complex.
Even Einstein himself was puzzled by the amazing performance of microscopic particles, believing that we fundamentally misunderstood the quantum mechanics of the universe. Einstein’s theory proved wrong, but it will take some time to explain what went wrong with him and what really happened in the quantum world. Let’s begin to unravel some of the mysteries.
One of the most important lessons of quantum mechanics is that we have to completely rewrite our concept of “particles,” instead of describing a hard, solid, precise point in space and time. Today scientists think of particles as fuzzy probabilities (fuzzy probabilities),. When we look for particles, we describe them accordingly, but until we measure them, we still don’t know exactly what they are.
These particle fuzzy probabilities are not only applicable to the position of a particle, they are also related to particle velocity, angular momentum, rotation and so on. If we are interested in measuring particles, it is likely that we do not know what discovery will be made in advance.
Particle fuzzy probabilities, also known as quantum states (quantum states), are concise mathematical equations that sum up all the probabilities that we want to probe into the properties of particles. But when two particles share a quantum state, it is very difficult to understand. In some cases, we can connect two particles by quantum, so that such a mathematical equation can describe the probability of two groups of particles at the same time.
What confuses Einstein.
At first, it’s very likely that only scholars would care about it, but something interesting has come up, which is what we call a “entangled state” of two particles, which seems to us to be a very simple but surprising fact.
We’re going to be preparing a super-special entangled quantum state so that there are two possible outcomes, each of which, when we measure it, has a perfect probability of 50:50. In the first result, one particle rotates upward and the other rotates downward, in which case it rotates in the opposite direction.
All of these conclusions are quite correct, and we started to prepare for the entanglement quantum state test, let these particles leave in a free way, and start measuring.
Looking at particles for the first time, we find a rotational direction. It’s easy to look down, but it’s like flipping a coin when we’re just in time for the particles that spin up. Will this tell us the state of the second particle? Because we arrange entangled quantum states very carefully, we are now 100% certain that the second particle must be downward. Its quantum state is entangled with the first particle, and once a revelation emerges, both cases are discovered.
What if the second particle is on the other side of the room? Or on the other side of the galaxy? According to quantum theory, once a “choice” is made, the companion particle will immediately know how to spin and communicate at speeds close to the speed of light, which Einstein thought would not be possible.
Pandora quantum box.
For Einstein, quantum mechanics was clearly wrong. In a short paper he wrote with Boris Podolsky and Nathan Rosen in 1935, he used a similar line of thought to point out that novel quantum theories do not agree with him, a blow to the widely accepted theory of nature. Einstein argued that quantum mechanics does not fully describe the subatomic world, and that particles carry so-called “hidden variables” that enable them to coordinate their states before being measured.
But in decades of testing, over and over again, there has been no such hidden variable. The tests also showed that this “spooky action at a distance” did occur instantaneously. Even if we separate the entangled particles as far as possible, it will do so.
But physicists are still talking about how important the speed of light is, and that nothing can exceed that limit. Have we not noticed this apparent contradiction?
Living in a quantum world.
Suppose I keep one of a pair of entangled particles and send the other to you. As usual, I studied my particles, performed all the most important measurements, and found an upward rotation of the particles. Then send out a beam of light and tell you what you found.
But before the light signal arrives, you look at your particle and measure the downward rotation of the particle in quantum theory. But since my message hasn’t arrived yet, you don’t know if you’re the first to see it, or just randomly get a downward spin or force your particle into this state if I open it first. It is only after a comparative analysis that we find that the two particles are really entangled together, and that the measurement of one particle depends entirely on the other. Until then, we can’t tell if we’re dealing with particles that already exist.
So while the process of untangling the quantum entanglement is instantaneous, there is no sign of it. We must use traditional communication methods that do not exceed the speed of light to piece together the correlations needed for quantum entanglement. Thus Einstein’s cosmic speed limit was preserved, as was, fundamentally, the quantum worldview.