Regarding quantum mechanics, there is a lot of discussion on the Internet, especially various self-media, but they boast that it is amazing and weird. In fact, the most mysterious and difficult to understand quantum entanglement is mainly in the following three aspects:
First, the quantum superposition state, the so-called superposition state is the superposition of different states, including the contradictory states in the macroscopic world. For example, before a particle is observed, its state cannot be determined, it is in a state of rotating left and rotating right at the same time. This is inconceivable in the macro world and contrary to common sense, but it does exist in the micro world. In the words of Mr. Schrödinger Xue, it is “a cat that is both alive and dead.”
Second, the determination of the quantum state has been controversial throughout history. Two entangled particles, when are their respective states determined? A point of view is that it is established when they are created, which is a point of view on the side of Einstein, just like a pair of shoes, one is the right foot, and the other is definitely the left foot.
Another view is that it is only determined when the wave function collapses when they are observed. This is the view of the Copenhagen School headed by Bohr. Before observing it, it is in a superposition state, or an indeterminate state, and only by observing it will it have a definite state. (In the EPR paradox, Einstein believed that observation cannot interfere with particles, while Bohr believed that observation equipment and particles should be a whole, and the state of particles should be determined by observation)
Neither of the two viewpoints can convince the other, but all the experimental results so far support Bohr’s viewpoint, and the current judgment method is to strictly verify Bell’s inequality.
Third, the quantum communication mechanism, two entangled particles fly in opposite directions respectively. When we observe a certain particle, no matter how far apart another particle is, it will make corresponding changes in an instant as if we have a heart-to-heart, that is, it has a super-distance effect.
Here comes the question, is there any communication between two entangled particles? If there is no communication, how does one particle know that the state of another particle is determined? If there are communications, what mechanisms are they and what is the speed of the communications? So far, no communication between them has been found.
Of course, for the first and second points above, it is not the focus of our discussion for the time being, and we focus on the third point. Two entangled, when we do not observe them, their states are both random and uncertain. Once we observe one of them, the other will instantly determine the state, and this process is irreversible and cannot be repeated twice. implement. The question arises, when we observe one particle, how does the other particle know and make corresponding changes? Sadly, it’s still a mystery because we haven’t discovered anything, as if they really knew it spontaneously, and this only exists between quantum systems.
Even if it is “telepathy”, then there is also a transmission time. Although we can’t entangle in a very far place now, in the case of the 1200-kilometer experiment, we have not found that there is a time difference between the changes of the two particles. Perhaps our current instrument has insufficient precision, but if the speed of communication is the speed of light, the current instrument is enough to measure a delay of 0.004 seconds, but unfortunately not. This means that even if there is some kind of communication between them, the speed must be faster than the speed of light!
But the current physical knowledge tells us that the highest speed in the universe is the speed of light. Wouldn’t the “communication” between quanta go against the current physical cognition? In fact, even if there is entangled communication, it does not violate the current laws of physics. The premise of not being able to exceed the speed of light is that it does not carry information and has no mass. At present, the communication of quantum entanglement cannot be measured at all, nor can we use it to carry out any information transmission. Their changes are constant and only the transmission of state determination. So the so-called quantum “communication”, which we don’t currently think exists, is just an incomprehensible state of entanglement.
In theory, the distance of quantum entanglement is infinite, but there is currently no way to prove that the farthest entanglement distance is the 1200-kilometer experiment conducted in my country. What Pan Jianwei’s team hopes most at present is that they can conduct quantum entanglement experiments on the moon in the future, so that the distance can reach more than 300,000 kilometers!
Of course, science is a process of continuous breakthroughs, and quantum mechanics is also constantly being completed. One day, more hidden secrets will be discovered by humans and will be used by us!
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