# What is Spin? Understanding Electron Spin & Its Importance

• FeDeX_LaTeX
In summary, the concept of spin in physics is a property of particles that can be measured through various experiments. It is represented in an abstract vector space and for spin-1/2 particles, it can take on two values. Spin is an intrinsic property that is important in understanding the behavior of particles and their interactions with electromagnetic fields.

#### FeDeX_LaTeX

Gold Member
Hello;

I am having trouble understanding what this phenomenon is. The spin of an electron is 1/2 - but I don't understand what this is trying to say. What is 1/2? I know the electron isn't actually 'spinning'... I've heard the term "it's a kind of intrinsic angular momentum" a lot, but that doesn't really help. What is the difference between a spin of 1 and a spin of 1/2? What does it do? Why is it important?

Thanks.

What is charge? It is an intrinsic property of fundamental paticles that can be measured by the particle's response to an electromagnetic field. What is inertial mass? It is an intrinsic property of a macroscopic body that can be measured by determining it's acceleration in response to a known force. What is spin? It's a property of a particle that can be measured by performing Stern-Gelasch experiments or Spin Resolved Photoemission experiments on the surface of a metal.

The thing is all of these physical quantities are at there basis, something that can be measured. We can also talk about our mathematical mapping of these physical quantities to a theoretical representation. For example, mass and charge are scalar quantities represented by real numbers (charge has the additional constraint that it has to be an integer multiple of the electron charge - this constraint is experimentally derived).

Spin must be represented a bit more abstractly. The spin degree of freedom of a particle (let's take a spin-1/2 particle for simplicity) is represented in an abstract vector space. The state of the electron (or electron ensemble depending on your interpretational preference) can be represented in a two-dimensional space. Why you ask? Well when we put a spin-1/2 through a Stern-Gelasch apparatus (wiki it) you get out two beams and only two beams. So the particles have some degree of freedom that only takes two values. That's spin.

## What is spin?

Spin is a fundamental property of subatomic particles, such as electrons, that describes their intrinsic angular momentum. It is a quantum mechanical property that cannot be explained by classical physics.

## How is spin related to electron spin?

Electron spin specifically refers to the spin of an electron, which is one of the subatomic particles that make up an atom. It is important to understand electron spin because it plays a crucial role in determining the properties and behavior of atoms and molecules.

## Why is electron spin important?

Electron spin is important because it is one of the quantum numbers that helps to define the energy levels and electronic configurations of atoms. It also plays a critical role in many physical phenomena, such as magnetism and chemical bonding.

## How is spin measured?

Spin is measured in units of angular momentum, such as h-bar (ħ) in the International System of Units (SI). The value of electron spin is always a half-integer multiple of ħ, with the two possible values being +1/2 and -1/2. It can also be measured using specialized instruments, such as a Stern-Gerlach apparatus.

## Can spin be changed?

Spin is considered an intrinsic property of particles and cannot be changed or manipulated in the same way that, for example, the direction of a spinning top can be changed. However, spin can interact with external forces, such as magnetic fields, and change in direction or orientation as a result.