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8
votes
7answers
1k views

Why do physicists believe that particles are pointlike?

String theory gives physicists reason to believe that particles are 1-dimensional strings because the theory has a purpose - unifying gravity with the gauge theories. So why is it that it's popular ...
31
votes
6answers
4k views

Do electrons have shape?

According to the Wikipedia page on the electron: The electron has no known substructure. Hence, it is defined or assumed to be a point particle with a point charge and no spatial extent. Does ...
18
votes
4answers
5k views

Can you split a photon?

I was wondering if a photon is divisible. If you look at a photon as a particle, then you may be able to split it (in theory). Is it possible and how do you split it?
4
votes
2answers
794 views

Why do physicists think that the electron is an elementary particle?

When we first discovered the proton and neutron, I'm sure scientists didn't think that it was made up of quark arrangements, but then we figured they could be and experiments proved that they were. ...
13
votes
3answers
505 views

Why are all force particles bosons?

All of the force-particles in the standard model are bosons, now my question is pretty short, namely: Why are all force particles bosons? This can't be a coincidence.
2
votes
2answers
556 views

What experiment(s) have or can refute the existence of an electron-particle “system” over the separate existence of a neutron within itself?

This question actually came about from a discussion of another question posed here The neutron is known to be comprised of an electron and a proton, and there are observations that the neutron can be ...
1
vote
2answers
157 views

Can we make usable energy from subnuclear particles?

I understand mass and energy are the same, but in this question I will be talking about mass being turned into usable energy (electricity/heat/etc). We can make our energy through chemical reactions ...
12
votes
3answers
2k views

An electron has no known internal structure, does that imply it has an unknown one?

I'm currently reading Alonso and Finn's Electromagnetism book. It explains that the spin contributes to the magnetic moment and is somewhat comparable to a rotation of the particle around its own ...
9
votes
5answers
1k views

How can a point-particle have properties?

I have trouble imagining how two point-particles can have different properties. And how can finite mass, and finite information (ie spin, electric charge etc.) be stored in 0 volume? Not only that, ...
8
votes
3answers
2k views

Why do quarks have a fractional charge?

I am aware that evidence exists that strongly suggests the existence of quarks and do not doubt it. It is just simply really weird to me that they can have a fractional charge. While other ...
0
votes
1answer
124 views

Is everything in the physical world composite?

In philosophy there is a principle that anything composite cannot have existed eternally, since it is preceded by its parts and whatever forces assembled it. Is everything in the physical world ...
3
votes
4answers
963 views

Must Matter Particles Have A Hard Edge?

It's my understanding that electrons are particles, and it's also my understanding that their location while orbiting an atom cannot be determined precisely and must be determined by statistics and ...
5
votes
1answer
1k views

Is a photon technically a set of two particles?

When looking at the classification of massless particles, one finds that there is the (half-integer) quantum number "helicity" $h$. For every possible $h$ there is a certain particle kind. In the case ...
3
votes
1answer
603 views

Is it dangerous if one elementary particle with high energy penetrates our brain?

We might be killed if a bullet penetrates our brain. How about an elementary particle moving with high energy penetrates our brain? Assume that we can have exactly a single elementary particle for ...
4
votes
1answer
120 views

Why should I believe that “elementary” particles are indeed elementary?

Atoms were once thought to be indivisible (i.e. have no substructure), until it was discovered that they are made of protons and neutrons. Protons and neutrons in turn are made of quarks, and that's ...
2
votes
1answer
126 views

Is it possible to measure the radius of an elementary particle?

The only way to describe the electron radius that I found in literature is the "classical electron radius". Is it possible to experimentally measure this? Is there a better way to describe the ...
9
votes
2answers
675 views

Is everything made of massless particles?

Photons have no mass. Yet they interact gravitationally, as all energy does, with other energetic and massive particles. This means that if you put multiple photons in a system, you get something that ...
6
votes
1answer
246 views

Is color confinement detected?

I'm a graduate student studying QFT. I'm quite interested that is color confinement detected or proved? (both directly and indirectly) Or it is just an assumption?
3
votes
1answer
118 views

Magnetic moment of uncharged particles

As we know that particles, only having charge, can have magnetic moment, then how particle like neutrino (having mass) can have magnetic moment? Don't bother about neutron because it has charge ...
1
vote
3answers
136 views

What is the smallest observable structure in the universe?

I've been wondering about the Planck length recently, but it is not observable. What is the smallest actually observable structure in the universe?
0
votes
2answers
52 views

Since nucleons are not elementary particles more, how we call nucleons and electrons together now? [closed]

In the time before the discovery of quarks the nucleon particle proton and neutron together with electrons were called elementary particles. It's a little bit boring to have only the possibility to ...
-2
votes
1answer
156 views

Emission and absorption of photons by electrons [closed]

Two questions occur at a critical review of the two famous experiments devised by Millikan in 1914, respectively Duane, Hunt and others in 1917-1920, which confirmed the action constant calculated by ...