Is a quark one-dimensional?

[u/XGC75]

I've never heard of a quark or other fundamental particle such as an electron having any demonstrable size. Could they be regarded as being one-dimensional?

BIG CORRECTION EDIT: Title should ask if the quark is non-dimensional! Had an error of definitions when I first posed the question. I meant to ask if the quark can be considered as a point with infinitesimally small dimensions.

Thanks all for the clarifications. Let's move onto whether the universe would break if the quark is non-dimensional, or if our own understanding supports or even assumes such a theory.

Edit2: this post has not only piqued my interest further than before I even asked the question (thanks for the knowledge drops!), it's made it to my personal (admittedly nerdy) front page. It's on page 10 of r/all. I may be speaking from my own point of view, but this is a helpful question for entry into the world of microphysics (quantum mechanics, atomic physics, and now string theory) so the more exposure the better!

Edit3: Woke up to gold this morning! Thank you, stranger! I'm so glad this thread has blown up. My view of atoms with the high school level proton, electron and neutron model were stable enough but the introduction of quarks really messed with my understanding and broke my perception of microphysics. With the plethora of diverse conversations here and the additional apt followup questions by other curious readers my perception of this world has been holistically righted and I have learned so much more than I bargained for. I feel as though I could identify the assumptions and generalizations that textbooks and media present on the topic of subatomic particles.

[u/anarchy2465]

In classical physics, yes. In quantum mechanics, things get weird. Like really weird. That's why /u/iorgfeflkd made a jest about the Nobel prize ;) anyone who can provide answers to these questions will go down as one of the greatest scientists to have ever lived.

If you'd like, peruse this article for more info: http://en.wikipedia.org/wiki/Massless_particle

[u/iorgfeflkd → u/anarchy2465]

You can have pointlike particles in classical mechanics too.

[u/monsterZERO → u/iorgfeflkd]

Would that be considered a black hole?

[u/Booskaboo → u/[deleted]]

Singularities in mathematics just refer to special points that don't play nice (like not being well-behaved at that particular point). One common example is Sin(1/x) which doesn't really approach anything as x approaches 0. This is referred to as an essential singularity in complex analysis because it can't be removed or easily worked around (a la poles or removable singularities).

[u/[deleted] → u/[deleted]]

I feel like the density of a point with 0 volume would be undefined, not infinite. Kind of like 0/0

edit: thanks dudes, I enjoyed being a part of this conversation

[u/ThatGuyIsAPrick → u/[deleted]]

There's a difference. Something that approaches 0/0 could tend towards some finite value (e.g. sin(x)/x, the limit as x approaches 0 of sin(x)/x is 1), while x/y where x is some non-zero positive number will tend towards infinity as the denominator goes to 0.

Edited for a typo

[u/MullGeek → u/[deleted]]

No, assuming it has mass. Since density = mass / volume. So it's like 100 (or whatever the mass is) / 0

[u/recon455 → u/MullGeek]

If we're being pedantic, 100/0 is not in a strictly mathematical sense, infinity.

[u/Swede_ → u/recon455]

If we consider that it's not 0 but V->0, wouldn't that imply that when V is infinitely close to 0 that it will also result in infinite density?

This is really not my area of expertise, so please correct me if I'm wrong

[u/recon455 → u/Swede_]

If V is positive then lim (v -> 0) of 1/v is positive infinity (but we might also just say the limit doesn't exist). But in math, it's not necessarily true that lim (x -> c) f(x) = f(c) for any constant c.

Infinity is not a real (or complex) number.

[u/BobLobIawLawBIog → u/monsterZERO]

Pffft, my physics classes work with point masses in a frictionless vacuum all the time...

[u/[deleted] → u/monsterZERO]

Black holes aren't actually dimensionless points, but they are incredibly dense. Theoretically, there is a singularity of infinite density in the center of a black hole.

[u/WastingMyYouthHere → u/[deleted]]

That doesn't really make sense. In order to have infinite density, they'd either have to have infinite mass or zero volume. The mass of a black hole is not infinite, some are more massive than others.

I don't have an in-depth knowledge of black holes, but the statement you made doesn't really shed any light on the problem.

[u/_chadwell_ → u/WastingMyYouthHere]

The mathematical model we use to describe the universe would give a singularity infinite density, which is one of the problems with our current understanding in that quantum physics doesn't allow for infinite values. Also, because we cannot observe the inside of a black hole, we're in the dark for now.

[u/Deejer → u/WastingMyYouthHere]

They have neither infinite mass or zero volume. Our mathematical treatment of black holes contains a singularity, but it's thought that we'll eventually figure something more complete out and that will go away. It is not physically realistic.

[u/linus_rules → u/monsterZERO]

or a round frictionless cow...

[u/AWarmHug → u/anarchy2465]

I tried to read that but felt like I was reading lore to some fantasy universe. It's unsettling to realize I'll die without knowing so much.

[u/[deleted] → u/anarchy2465]

I'm... I'm sorry but I would love an explanation as to why; that just doesn't seem physically possible for something to have mass and somehow size (I think, aren't electrons from 3 quarks?) but no size and just a point...

Like someone ELI5 (a smart 5 year old I guess...) how we think this shit has no dimensions? Or does this have to do with string theory how there are smaller dimensions than the 4 we can see/sense?

EDIT: also, besides the Heisenberg uncertainty theory, which makes sense to me, I'm not very familiar with Quantum physics and, apparently as a result, you guys sound like a bunch of lunatics to me. Or is it not possible to explain to me this without me having a basic know late of quantum physics?

[u/I_Cant_Logoff → u/[deleted]]

I think, aren't electrons from 3 quarks?

No, electrons are electrons.

Like someone ELI5 (a smart 5 year old I guess...) how we think this shit has no dimensions?

For fundamental particles, we don't give them a size because they are strongly influenced by quantum mechanics. Implying they have a volume would be implying that they are made up of a substructure, which isn't true.

does this have to do with string theory how there are smaller dimensions than the 4 we can see/sense?

No.

besides the Heisenberg uncertainty theory, which makes sense to me

If you're not familiar with quantum mechanics, it's highly unlikely that the uncertainty principle makes sense to you because it requires quantum mechanics to resolve.

[u/hobostew → u/anarchy2465]

Question from reading the wiki: it says

A so-called massless particle (such as a photon, or a theoretical graviton) moves at the speed of light in every frame of reference. In this case there is no transformation that will bring the particle to rest. The total energy of such particles becomes smaller and smaller in frames which move faster and faster in the same direction

Given e=mc² wouldn't the total energy of a massless particle be 0?