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Fiction | What is a spin?
Fiction | What is a spin?
Once we figured out what the absolute zero and can I recover the information that was eating the black hole , the order of the day there is another interesting question. The issue is complex, as is in the field of quantum physics. It sounds like this:
“What the hell is a spin?”
What kind of spin?
If you think that the expression was unnecessary, you are wrong. Spin – one of those strange things in quantum mechanics, trying to understand that, do you think that intuition and personal experience will help you. But it is not. On the contrary, your intuition is more likely to fall on their knees in front of you. Try not to trust her.
Let’s start with the fact that all fundamental particles have spin. Spin – “axis” of the English spin. Just as electric charge or mass, spin, helps determine the type of particle.
Some particles, such as electrons, positrons, and quarks (protons and neutrons are made of quarks, as the fundamental particles of the Standard Model) have spin ½. They are known as “fermions”. Others, photons, gluons, and the W-and Z-particles have spin 1. They are known as “bosons”. Obviously, fermions and bosons behave differently.
If all this time you nod in agreement, little voice in your head is probably saying something like “polspina what? ‘. It should be noted, to the inner voice is good to listen, so let’s talk about how the spin of the electron.
It’s like a little gyro, but not quite.
Why electrons? Because if you understand what the spin of the electron, the rest is easy. Try to imagine that the electron – a small gyroscope. It spins and spins without stopping. Regardless of what you do with it, you can not slow down or speed up the rotation of the electron, and you just might change his position.
Whatever you do, there will always be that of the electron spin ½. ½ But what? Number, known as the “reduced Planck’s constant.” This is a very small number. Very much.
Here’s a strange fact first. Usually, you can slow down the rotating body. Superman was able to stop the rotation of the Earth, for example.
On the other hand, we are dealing with a small rotating gyroscope. Angular momentum – this is one of those constants that are maddening physics. When the direction of the electron spin angular momentum is transferred anywhere – from the orbit to the other electron.
Since the electron has a charge, and because he “rotates on an axis”, it creates a small magnetic field. This is how any electromagnet. We can detect the magnetic field of the electron or reject individual electrons using other magnets to figure out which direction the electron. But …
The magnetic field does not work like that.
Take a small charged ball and twist it around the axis. You will create a magnet. Regardless of how large or small ball, it turns out that the magnetic field will be accurately predicted multiple angular momentum. There are a bunch of constants associated with the charge and mass of the ball, but not with the size.
The problem is that if the electron present in the same manner above described procedure is generally ride. The magnetic field is twice. More precisely, in 2.0023193044 times. This number is measured with an insane level of precision and calculated theoretically. The game takes the damn “quantum field theory”, because we can make some accurate predictions.
Weird fact number two: you can not, do not have the right to think of an electron as a tiny microscopic charged sphere. Just turn out wrong numbers.
The spin of an electron determines the accident.
Although the electron spin is fixed, you can assume that the components of the spin in a certain direction can be any old value, which we like. Think about this in the following example. Let’s say I had a meter stick (1 meter long) with one end stuck in the ground at an angle. Can measure the height from the upper end to the ground, and depending on the angle now value between 0 and 1 meter.
You know that the Earth rotates, but if you’ve ever seen a globe, you know that it is tilted at an angle of around 23 and a half degrees to the plane of the orbit. In other words, if you measure the “axis” (or spin) of the Earth from top to bottom, you will get less than the full length of the axis. Axis is a bit cranky from side to side.
Since electrons is not working. If you have created a small magnetic field to distinguish them, you find out that a single electron is 100% of the spins up and 100% of the spins down, depending on the case, and never – between. What is more strange, it does not matter how you configure your instrumentation, you always come to the same primary outcome: either one side or the other, no middle ground.
And here we are born the third strange fact. Suppose you measure the electron, and you discover that it has a top spin. After you are trying to measure the spin of the left-to-right. Common sense will tell you that the number is zero, since you know that the electron spins from the bottom up, rather than left to right. But as we noted above, common sense will help you. It turns out that: a) half the time, when you measure the electron, it will be “left” in half – the “right”, and b) the right and left is determined by the absolute fluke. It is true. Nothing in the universe can not tell you which way to choose the electron. This kind of accident severely distressed Einstein (remember his saying that God does not play dice.)
You need to turn the double-electron, so that it looks “as before”
In the past we have often talked about the wave function of the particles. The square of the wave function tells you the probability of finding the particle at a certain place at a certain time. What is remarkable in the electron (and all particles with spin ½), is the fact that if you turn the entire universe of 360 degrees, the wave function will be a minus sign at the beginning.
This is the fourth strange fact. Need twice rotate around the axis of the electron, and it will look the same as in the beginning.
It would seem that nothing strange. After all, why worry about the wave function if the minus sign does not do anything. -2 = 2 two two.
The same effect occurs if you present, if substituting one electron others. Nothing changes, but there is a minus sign in front of the whole wave function. It seems insignificant, until you realize that …
The minus sign – that’s what makes you possible.
Плюс и минус
Imagine two electrons with spins in one direction, and the other one – to the top (the experts also have to understand that the two electrons is the same impulse). Now change their positions. For us, nothing has changed, but in quantum mechanics, the whole universe was plunged into chaos. The wave function does not seem to have changed, as no significant difference of one electron from the other is not, but either way, we put a minus sign at the beginning.
Again, nothing has changed, but is multiplied by -1. The only number with which it works is 0. In other words, the wave function is zero probability zero, or no chance at all.
Another way to say this: electrons (and all fermions: quarks, positrons, neutrinos, etc.) can not be in the same place with the same spin. This is the famous “Pauli”. It predicts that the electrons in the atoms can not be in the same state, but instead occupy different orbitals. If it were not so, the electrons would occupy the lowest levels, and the elements would behave boring as hydrogen. Boring and not conducive to the origin of life.
Bosons, another type of particles that do not operate on this principle. Swap two boson, and nothing will change. Turn boson once, and everything will return to normal. They spin is equal to one, which means only that they behave exactly as you expect. But these are only bosons are discovered to date. In the Higgs boson ( if it exists ) spin 0, y graviton (if it exists) is the spin 2, but we still can not talk about them. Bosons may be in the same location and have the same spin. That’s why we can get the Bose-Einstein condensate, which is a bunch of bosons in the same state.
“Chip” is not that the spin – a strange thing, but this one does not argue. “Chip” is that the spin is in the center of a much more serious and fundamental things, based on their work than you might suspect.
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Tags: quantum mechanics , spin , electrons .
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