Quantum computer, quantum encryption and quantum often appear in the news. Articles about them will inevitably involve entanglement, which is a feature of quantum physics and makes all these magical devices possible.
Einstein called entanglement "strange behavior in the distance", and the name became stuck and became more and more popular. Besides building a better quantum computer, understanding and using entanglement is also useful in other aspects.
For example, it can be used to measure gravitational waves more accurately and better understand the characteristics of special materials. It also appears subtly in other places: I have been studying how atoms collide with each other to understand how it affects the accuracy of atomic clocks.
But what is entanglement? Is there any way to understand this "weird" phenomenon? I will try to explain it with two concepts in physics: conservation law and quantum superposition.
The law of protection is the most profound and universal concept in all physics. The law of conservation of energy shows that the total energy in an isolated system remains unchanged (although it can be converted from electrical energy to mechanical energy to thermal energy, etc.). This law is the foundation of all our machines, whether steam engines or electric cars. The law of conservation is an accounting statement: you can exchange some energy, but the total amount must remain the same.
Maintaining momentum (momentum is mass times speed) is the reason why the lighter skater moves faster than the heavier skater when two skaters with different masses push away from each other. This law is also a famous motto: "Every action has the same and opposite reaction." Why maintain angular momentum-back to the skater-a rotating figure skater can rotate faster by pulling his arm closer to his body.
Hard core science in quantum mechanics;
If the bare theory is described in the simplest language, we can say that quantum mechanics describes how the quantum state of the system evolves and what results will be obtained by observing a system with a certain quantum state. In short, there are two things, one is evolution and the other is observation.