I recently discovered a very, very good way to understand quantum mechanics. Even people who don't understand quantum mechanics can easily understand the counterintuitive phenomena in quantum mechanics!
As for me, I have been doing popular science on quantum mechanics for many years. I have found that when many people hear about concepts such as the double-slit interference experiment, wave-particle duality, probability waves, measurement collapse, and quantum entanglement, they will first ask why: Why is the quantum world like this?
Most of the time, when we do science popularization, we can only tell you: Don't ask why! Because the basic phenomena of the microscopic world are like this, and science only summarizes the phenomena, not explains them.
First of all, before you understand quantum mechanics, you should know that quantum mechanics is the phenomenon of the microscopic world. Generally speaking, it refers to the movement of particles smaller than atoms. These phenomena include wave-particle duality, probability waves, quantum entanglement, etc.
But you will find that there is a common point behind these quantum phenomena, that is, all microscopic particles are uncertain and vague, that is to say: microscopic particles do not have a definite shape or definite boundaries.
When we humans first understood microscopic particles, we always thought that these particles were a kind of solid sphere. But soon physicists discovered the wave-particle duality and the idea that particles were solid spheres was passed!
That is to say, these particles are both waves and particles. This sentence still sounds difficult to understand. It seems that it is still difficult for the human brain to imagine an obxt that is both a wave and a particle. But it doesn't matter. Anyway, this concept of wave-particle duality is outdated. The latest understanding of microscopic particles in the physics community is a view based on quantum field theory.
In quantum field theory, wave-particle duality is just an appearance. In fact, any elementary particle is a field. The so-called particle is just a kind of energy excited by the quantum field. Different particles have different quantum fields!
Now stretch out your right hand and pinch your nose. Do you find that the shape of your nose has changed? Then think again, how does the force work when you pinch your nose?
In fact, when you can magnify this behavior to a microscopic scale, you will find that pinching your nose with your hand is just an electromagnetic interaction between the extranuclear electrons on the surface of your hand skin and the extranuclear electrons on the surface of your nose. The extranuclear electrons are all negatively charged, so when the extranuclear electrons are not in complete contact, they produce a repulsive effect by relying on the electromagnetic force.
At this point, think about it more deeply: the electrons in your hand and the electrons in your nose are obviously not in contact, and there is only a vacuum area between them, so how could there be any effect?
This seems to be a kind of action at a distance, so the first idea that violates common sense was born! In order to make the counterintuitive phenomenon of action at a distance logically self-consistent, we assume that an extranuclear electron and another extranuclear electron have an action force. There must be an obxt in the middle that transmits this force, and this substance is called a propagator.
The propagator of electromagnetic force is virtual photon. When two extranuclear electrons interact with each other, virtual photons are constantly exchanged between them to transmit this force. If you think about it again, if we regard microscopic particles as solid balls, you will find that there is a big problem here.
The interaction between electrons relies on propagators such as virtual photons. So how does the interaction between propagators and electrons occur? Since microscopic particles have been assumed to be solid spheres, there will always be a vacuum between propagators and electrons, which is a kind of action at a distance. So once we identify microscopic particles as small spheres in the classical physical world, it is impossible for these particles to interact with each other.
Because there is always a vacuum between them, which is like a wall, making it impossible for all particles to interact with each other, so there can only be one possibility for the form of microscopic particles to explain the logical bug caused by this long-distance action. That is, microscopic particles themselves are vague and fill the entire space. There is no boundary between them, and the particles themselves are also a kind of intertwined quantum field!
In fact, the laws of physics do not recognize action at a distance. The so-called action at a distance of quantum entanglement is itself an illusion. Newton has the most say on action at a distance. As early as when Newton was alive, he found that action at a distance was intolerable! Newton found that there was a vacuum zone between planets. There was no propagator between two planets, but they still produced gravity. Isn't this action at a distance?
In order to solve this problem, Newton introduced the concept of ether proposed by Aristotle more than 2,000 years ago. He believed that ether was evenly distributed in every corner of the universe and acted as a propagator of gravity. Of course, Michelson-Morley later falsified the ether!
The action at a distance between gravity was eventually replaced by the curvature of space-time in general relativity, which holds that gravity is an illusion.
The so-called gravitational effect is just the mass bending the space! obxts moving in the curved space behave like gravitational effects! Therefore, there is no need to introduce additional propagators between gravity!
But quantum mechanics doesn't think so. Quantum mechanics must give gravity a propagator, which is the graviton. Of course, there is still a lot of controversy about the graviton because general relativity believes that gravity is not a force, so there is no need for a propagator. But quantum mechanics still believes that gravity is a force and needs a propagator.
Back to the original question, it is precisely because the laws of physics do not recognize action at a distance that microscopic particles can only be in a vague form to solve this problem. You see, the electromagnetic force acts at an infinite distance, which requires that the vague boundaries of microscopic particles are also infinitely far away. It is precisely because particles are vague that they cannot have a clear position like a solid ball.
So we can only describe it with probability, and that's it. If you look at quantum entanglement again, the so-called entangled particles are actually the same particle. The direct energy is split into two and becomes two entangled particles, but the entangled particles still use the same quantum field.
This quantum field can extend to every corner of the universe, so the so-called superluminal interaction between two entangled particles is actually the simultaneous action of the same particle. If one of the entangled particles is changed, the other particle will definitely change at the same time. It is easier to understand the double-slit interference experiment of electrons with this idea.
What is most difficult for us to understand is why electrons pass through the double slits at the same time and why an electron interferes with itself.
In fact, let alone double slits, even if there are countless slits, electrons can pass through them at the same time! Because of the fuzzy form of electrons, it is destined that electrons can be in multiple positions at the same time.
Finally, let's summarize: Matter in the universe is interacting with each other all the time. If we magnify this interaction, we will find that there is a huge vacuum zone between all particles. If the particles are small balls, then the vacuum will hinder the occurrence of super-distance action. Therefore, microscopic particles can only be blurred to resolve this super-distance action.
You will understand after hearing this: the vague concept of microscopic particles is the most logical! The concept of particles as solid balls is counterintuitive.