Why does Electron spin?

[patio]

The Moon for example orbits...and rotates on it's axis...=spin.

[Geek-9pm]

The notion of 'electron spin' is in a class of its own.

Simply put, electrons are not spinning. It's unfortunate that the term "spin" has perpetuated from the earliest days of the development of the atomic theory. We can't apply classical, macroscopic concepts to the quantum world.

The "spin" of an electron is actually a magnetic property, not an actual rotation. Like a bar magnet with its north and south poles, electrons which are paired have opposite magnetic properties. Except in the case of an electron, the magnetic field is an electro-magnetic field and not a permanent magnet like the bar magnet.

From yet another source:

Electron Spin Definition
Chemistry Glossary Definition of Electron Spin

By Anne Marie Helmenstine, Ph.D.

Definition: A property of an electron that is loosely related to its spin about an axis. Two electron spin states are allowed, which are described by the quantum number ms, with values of +½ or -½

The general definition of 'spin' is not literally true to the electron. The word is used as a label  to identify a property. It is a quantum thong.

[Salmon Trout]

The Moon for example orbits...and rotates on it's axis...=spin.

Orbiting and spinning/rotating are separate things. One does not imply the other.

[BC_Programmer]

The Moon for example orbits...and rotates on it's axis...=spin.

The moon Revolves around the Earth and Rotates on it's axis, yes.

But as Salmon Trout has described, the property of "spin" that is given to fundamental particles is not a case of the particles physically rotating. I don't know the specifics of it's history but the term sounds like a etymological remnant from a earlier theory about the properties the particles would have. This should come as no surprise, in fact- the typical visualization of an atom- a nucleus with electrons with visualized orbits- is equally based on previously posited theories about the nature of the atom which we have since learned are not accurate (Electrons don't really "orbit" the nucleus in the classical sense, rather they are distributed in a probability cloud within their respective electron shell.

The reason an electron, Proton, or neutron cannot be said to have "spin" in the classical sense (eg. the Moon or Planets rotating) is because they have no surface, or other similar property, that could be used as a reference point to determine said spin*. in this sense their "spin" is only expressed through the release or absorption of energy, in the same sense that a seismic wave has no "surface", but is otherwise measurable.

[IPDO]

Can anyone tell me how does an electron look like. And what is he/She doing on earth? 
I am leading you to creation of world!   

[BC_Programmer]

Can anyone tell me how does an electron look like.

No. Nobody can tell you what an "electron looks like".

How exactly would you "see" something that is small enough that the very wave/particle that light consists of (photons) would interact in a way that transfers the photon's energy to the Electron? The answer is you can't. All we can do is observe the effects of those unobservable particles and classify those effects to create a consistent set of postulations backed by observations about what the particles are.

And what is he/She doing on earth? 

This seems a bit irrelevant. Earth is one planet among 8 orbiting one star among billions resident in a galaxy that itself is one among any number of trillions of other galaxies of similar composition. Electrons are an elementary particle and their existence in Matter on Earth is a result of their existence in matter.

I am leading you to creation of world!   

Not really. Asking how an electron spins doesn't seem particular relevant to the accretion disk of the sun and the collapse of matter within that accretion disk to the center or to smaller proto-planetary disks that started to orbit that forming center. The Earth formed from one of those protoplanetary disks and solidified at least* 4.5 Billion years ago, based on calculations based on reliable radioactive processes. (Potassium Argon dating, for example, in which a radioactive isotope of Potassium decays into Argon, a gas, can reliably show the age of a rock containing it- when said Rock is formed, since Argon is a reasonably rare element in our atmosphere which does not otherwise bind with rocks in a crystal lattice due to it being a inert, stable gas that cannot easily form covalent bonds, will not exist in a freshly formed rock from cooled magma, since any such gas would easily escape from said rock. Thus by measuring the amount of Argon-40, it is possible to calculate the time since the formation of said rock by using the known half-life of Potassium-40, of about 1.2 Billion years. There is no stronger or better evidence about the age of the Earth that indicates otherwise. It's notable that Potassium-40 also decays to Calcium-40, but that is less useful than the Argon-40 decay since Calcium-40 is a very common isotope and determining the original amount of Calcium-40 is not possible.

While it is true that electron spin (and the nuclear spin of other particles) is involved in isotope decay, asking "why" doesn't seem to be a particularly fruitful question who's answer could change the calculation, any more than asking why we use arabic numerals to indicate numbers would change the accuracy of mathematics.

[Salmon Trout]

I am leading you to creation of world!   

I expected this. Religious propaganda. Time to lock?

[patio]

Done.