Thread: Physical Properties of Particles

Do subatomic particles have literal physical properties like size, shape, momentum, and texture? Do these factors affect it's mathematical model and behavior?

Originally Posted by Catalyst

Do subatomic particles have literal physical properties like size, shape, momentum, and texture? Do these factors affect it's mathematical model and behavior?

Quarks and leptons are fermions that have momentum, energy, spin, mass, parities of several kinds, electric and other charges, baryon number or lepton number, and nothing else I can think of offhand. They are points, or are at least smaller than we can detect, and have no properties like shape or texture.

Baryons and mesons are bound states of quarks and antiquarks. Accordingly, they have extent and could in principle have distorted shapes under appropriate conditions. Texture would be a bit surprising to say the least, and any non-spherical shape they might have as a result of interactions has never been detected. Baryons are fermions and mesons are bosons.

I'm sure you will hear quickly and gleefully of anything I have overlooked.

Originally Posted by mvb

Quarks and leptons are fermions that have momentum, energy, spin, mass, parities of several kinds, electric and other charges, baryon number or lepton number, and nothing else I can think of offhand. They are points, or are at least smaller than we can detect, and have no properties like shape or texture.

Baryons and mesons are bound states of quarks and antiquarks. Accordingly, they have extent and could in principle have distorted shapes under appropriate conditions. Texture would be a bit surprising to say the least, and any non-spherical shape they might have as a result of interactions has never been detected. Baryons are fermions and mesons are bosons.

I'm sure you will hear quickly and gleefully of anything I have overlooked.

Thanks for the reply, where do particles stand on size? Are their sizes theoretical or have they been observed?

Originally Posted by Catalyst

Thanks for the reply, where do particles stand on size? Are their sizes theoretical or have they been observed?

Quarks and leptons are point-sized as far as experiment is concerned. It has not been possible to detect any finite size for them. Nucleon sizes are of the order of a fermi (10^-15 m), and the internal distribution of charge has been well measured. Interestingly, the charge density pretty well matches what you would get if the binding potential was an infinite square well.

Originally Posted by Catalyst

Do subatomic particles have literal physical properties like size, shape, momentum, and texture? Do these factors affect it's mathematical model and behavior?

Bold added.

If the texture is rough the behavior is termed abrasive.

Originally Posted by DrRocket

Bold added.

If the texture is rough the behavior is termed abrasive.

What I meant by that is, do subatomic particles have a physical surface? Are they in 3-dimensional space?

Originally Posted by Catalyst

What I meant by that is, do subatomic particles have a physical surface? Are they in 3-dimensional space?

Of course they are in 3-dimensional space. Everything is in 3-dimensional space in current quantum field theories. If you look at exotic, speculative theories like string theory then space is of a higher dimension.

That has nothing whatever to do with any physical surface on the particles. In quantum field theory elementary particles are point-like, which is what mvb told you. Points themselves are zero-dimensional. Composite particles are comprised of a relatively small number of elementary particles.

You are trying to apply everyday adjectives to the quantum world. That will not work.

Originally Posted by Catalyst

What I meant by that is, do subatomic particles have a physical surface? Are they in 3-dimensional space?

Particles are fields, and fields have a (characteristic) size. But no texture or surface.

Originally Posted by DrRocket

Of course they are in 3-dimensional space. Everything is in 3-dimensional space in current quantum field theories. If you look at exotic, speculative theories like string theory then space is of a higher dimension.

That has nothing whatever to do with any physical surface on the particles. In quantum field theory elementary particles are point-like, which is what mvb told you. Points themselves are zero-dimensional. Composite particles are comprised of a relatively small number of elementary particles.

You are trying to apply everyday adjectives to the quantum world. That will not work.

Thank you for the clarification, this question has been making me hazy for a while now.