Why does Electron spin?

[IPDO]

Why does an electron spin. Do we ahve any explanation for that?

[Salmon Trout]

We neither have, nor need (in my opinion) an explanation. Electrons, like all fundamental particles, have a property known as “spin”.  In other words they have an angular momentum. This property is intrinsic. However fundamental particles do not have dimension, they are not little spinning balls. The spin angular momentum associated with fundamental particles has some properties that are very strange, and completely unlike the behaviour of spinning basketballs, or gyroscopes, or figure skaters, or whatever. They have spin because they do. That's what "intrinsic" means. To ask "why" is either a silly question, or else a theological one.

[IPDO]

What causes the electron to spin? There must be a reason.

[Salmon Trout]

As I said before, electrons don't literally spin, it's just called 'spin' because the magnetic field that's generated appears as though it comes from an infinitesimal current loop (i.e. it appears as though there's an extremely small amount of charge running in a loop, so it's as if the electron is spinning around). I suppose one answer might be that if they didn't have spin, then there would be no elements, and we wouldn't be here to measure it.

[Geek-9pm]

Next, Why is the Sky Blue?

[Salmon Trout]

Next, Why is the Sky Blue?

Well, you can kind of "explain" that by saying that the earth's atmosphere scatters sunlight, and scatters the blue part of the spectrum most strongly and you could explain the scattering by saying that Lord Rayleigh discovered that light is elastically scattered by particles much smaller than the wavelength of the light, and you could maybe explain Rayleigh scattering by saying that the size of a scattering particle is parameterized by the ratio x of its characteristic dimension r and wavelength λ:



You could go on to explain that the amount of Rayleigh scattering that occurs for a beam of light depends upon the size of the particles and the wavelength of the light. Specifically, the intensity of the scattered light varies as the sixth power of the particle size, and varies inversely with the fourth power of the wavelength. The intensity I of light scattered by a single small particle from a beam of unpolarized light of wavelength λ and intensity I0 is given by:



However to explain "why" the light is scattered is a kind of pointless question, the answer to which, rather unhelpfully, must be "because that's the way things are". This brick wall is reached much quicker when asking "why do electrons spin?", especially when you have been told that they don't really spin. One is reminded of the serial questions posed by small children.

[Salmon Trout]

Subatomic particles have properties, some of whose names are the same as properties of macroscopic objects, however this can be misleading. Spin, colour, charm, strangeness, upness, These are just analogies. Electrons don't really spin and a red quark isn't really red.

[patio]

Electrons do spin...however i'll concede the red quark statement.

[Geek-9pm]

Some believe that 'spin' is observed only while they are being watching,  otherwise they stay still. To date nobody has seen them while they were not being watched. To resolve  the +++++, we need an observer who does not exist.

+++++ refers to a tern that has yet to be identified, if it even exists.


The spin really comes for the PR people that lobby for the SubatomicCcoalition.

[patio]

How can one see something when it's not being watched ? ?

That's close to the most ridiculous statement you have ever posted here.

So if it's not being watched it doesn't move ? ? and when it notices one watching it moves ? ?

[Geek-9pm]

Patio, I am making a joke out of the explanations given in textbooks.
The theory  is something like this: 'A large object can not observe a very small object without  interference.' Therefore only a quark could tell us about an electron. But if  we approach the quark, our presence will destroy it.   It gets ridiculous. Think about the problem of measuring something small with a very large instrument. Like trying to  see  the gap of a spark plug  by hitting it with a with a sledge hammer.  We see things because of Photons. But photons can not correctly  show the position of an electron. 

The ide  of "Seeing inside the Atom" is about the use of any tool to understand the nature of the atomic layout. Are neutrons really in the middle?  How do we know the electrons are on the outside?

http://www.newton.dep.anl.gov/askasci/phy05/phy05232.htm
"Seeing" Inside Atoms

Question: How do you "see" inside an atom?

Replies: We cannot really 'see' inside atoms, but we can watch how atoms affect other things to figure out what the atoms are like. Imagine "Harry Porter" with an invisibility cloak -- you cannot see him, but if you see a vase knocked over, you might deduce that he is there. Or perhaps a better example would be to launch tennis balls at him and see where they bounce to figure out his size, shape, etc. The same is true for atoms -- you hit atoms with electrons, light, other atoms, and more, and can learn about the atom based on what happens.

Safety note: DO NOT put a sheet over your little brother's head (telling him it is for 'science') and launch tennis balls at him. That is a bad idea.

Hope this helps,

No, it does not help. 

[Salmon Trout]

Electrons do spin

Let's get the terminology straight (just in case)... in an atom, an electron 'orbits' the nucleus. When an object spins it rotates around its own axis. The earth spins. Spin is a distinct property from spatial motion. (mostly anyway) The property of the electron called 'spin' does not correspond to rotation around its own axis, although that was the original idea (briefly held in the 1920's), hence the name.

The term "electron spin" is not to be taken literally in the classical sense as a description of the origin of the magnetic moment [...] To be sure, a spinning sphere of charge can produce a magnetic moment, but the magnitude of the magnetic moment obtained above cannot be reasonably modeled by considering the electron as a spinning sphere. High energy scattering from electrons shows no "size" of the electron down to a resolution of about 10-3 fermis, and at that size a preposterously high spin rate of some 1032 radian/s would be required to match the observed angular momentum.

http://hyperphysics.phy-astr.gsu.edu/hbase/spin.html

[patio]

Both the nucleus and the protons /electrons orbiting the nucleus spin...

[Salmon Trout]

Both the nucleus and the protons /electrons orbiting the nucleus spin...

They have the property called "spin" that fundamental particles have, but they do not spin, i.e. rotate on their own axis. If you disagree, please point me to a reference.

[Salmon Trout]

The word spin means 'rotate', it does not mean 'orbit'. (let's get that clear). A wheel spins. A rolling ball spins. Electrons don't. This is despite them having the property physicists call 'spin'. I don;t know how to say it any clearer than that. back tomorrow with references.

[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 +˝ or -˝

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.