Physics Question EPR experiments show that locality and reality can t coexist? 40

Yes, it cannot coexist.

Locality, which stems from the fact that the ultimate speed of energy, matter, and information transmission is the speed of light (special relativity.

requirements); In this way, if the time difference t between the two events of two systems at a certain distance (set to x) is less than x c (c is the speed of light), then there will be no causal relationship between the two events.

i.e. they do not affect each other; Both events, which may have a causal relationship, are all limited to their respective light cones.

, this is the domain.

Reality refers to the fact that the various attributes (or elements of reality) of related entities exist and are determined before they are measured; Measurement simply makes those properties that already exist known; Although measurement also changes the original state (the specific value of the property) to a greater or lesser extent, it is by no means created out of nothing. This view of reality is naturally embedded in classical physics, but in quantum mechanics.

was severely challenged.

EPR experiments (all that has been done in practice are validation of Bell's inequality.

A series of experiments, such as the Spector experiment, show that either the physical entity is real, but at the same time non-localized—the properties of the two systems can be pre-existing and can be faster than the speed of light.

of some kind of information transmission to influence each other; Either the physical entity can retain locality, but not the reality - the respective states of the two systems are completely uncertain and non-existent before the measurement (but some general state of the two systems can be determined and known), so that there is no need to interact with each other.

EPR paradox is a paradox proposed to explain the incompleteness of quantum mechanics, I once thought about it for a long time when I was an undergraduate, and I also found a little book in the library, and I realized a little:

The superficial divergence between locality and reality: reality refers to the definite state in which we observe an object (definite physical quantity); Locality means that the range of interaction of isolated systems is determined (two isolated systems after the separation of electron pairs with opposite spins in EPR).

First of all, we must make clear that there is a basic assumption in modern quantum mechanics that matter is in the superposition of different quantum states, and each state exists, but the probability that we can observe is different, and we can only observe one state at a time, (the reason for the explanation is that when we observe it, it will inevitably have an impact on it, causing the state to collapse into a coherent quantum state, and then the result of observation must be that matter is in a single coherent state); But the state before the observation is meaningless to those who do not observe, and once we make observations, the state in which the object is in collapse into a coherent state;

Therefore, there is no overdistance interaction between the two electrons in the above EPR, because only after the observation, the physical quantity will have a real value, and it does not exist before the observation, so after the first electron is measured for spin, even if we know that they are electron pairs before, but the state before the second electron is measured, we still can't be sure. Because the first measurement leads to the collapse of the quantum state of the first electron, the correlation between the pair of electrons before the separation has been broken, and it cannot be the electron pair we knew at the beginning, and when the measurement of the second electron begins, the measurement causes the quantum state to collapse again, at this time, after two measurements, the relationship between the current electron pairs is re-established (becoming an electron pair); I see?

But if that's the case, idealism emerges, and when we think about it, its quantum state is uncertain, and once we observe it, it will cause its quantum state to change. I've been confused too!

Later, when I thought about it, I saw that everything in the philosophical book was interrelated, and the absolutely isolated system of our main imagination was itself irrational! Perhaps Marx said that everything is related, which is very meaningful!

These are just a few thoughts of mine that I hope will inspire you.