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Inside the proton, the ‘most complicated thing you could possibly imagine’

quantamagazine.org

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Re: Inside the proton, the ‘most complicated thing you could possibly imagine’

#31

Post by exmadscientist »

Tagbert wrote: post #14
drdeca wrote: post #10

Earlier quoted context omitted.

Huh? With a little bit more what? Complexity? I expected that they would be pretty much the same except with a different mix of the different quarks and such (and also, unstable without having a nucleus to be a part of, and with a neutral charge)

I've heard neutrons described as a union of a proton and an electron based on masses. The reality is probably much more complex.

The neutron and the proton are pretty similar. Of course, there's that tiny little bit of extra mass, but other than that:

Strong-force-wise, they are very hard to tell apart.

Weak-force-wise, you have the obvious changes in allowed interactions, but it's all stuff that's plain once you understand the theory of the weak force. No surprises.

Electromagnetism is actually the interesting one: just how neutral is this neutral garbage can? There are some interesting measurements to be made here. ILL in particular has done a lot with neutrons.

And the there's gravity. Gravity, you ask? Really? Yeah! If neutrons are really neutral, they don't interact electromagnetically, it's hard to get the strong force to come out and play, and the weak force only really does its thing here on the predictable* timescales of neutron decay... so all that's left is gravity. And thus, neutrons get used (or, I guess, more commonly just proposed...) as probes for gravitational effects! Fun, huh?

(* Mostly. See neutron lifetime controversy....)

Re: Inside the proton, the ‘most complicated thing you could possibly imagine’

#32

Post by jkhdigital »

andy_xor_andrew wrote: post #18

I just had a really stupid thought, after finishing reading the article. So, the electron is an elementary particle, right? Compared to the proton, the electron is "simple", yes? Despite this difference in complexity, an electron has a charge of -e and a proton has a charge of +e. They are exactly complementary regarding charge (if I am understanding right, I am not a smart person). my question is... why? why must pr…

Because if it were any other way then you wouldn’t exist to sit there and ponder the question. That’s the unsatisfying answer.

I think it makes sense to draw an analogy to evolution—stable arrangements of elementary particles that (somehow) reinforce similar arrangements around them will come to dominate the observable universe.

Re: Inside the proton, the ‘most complicated thing you could possibly imagine’

#33

Post by gweinberg »

Tagbert wrote: post #4

Then there are neutrons that are like protons with just a little bit more. It's sort of like infinity + 1. Is it bigger or is it equal? (I know, infinity is not a number, really)

Yes, just what I was thinking: a neutron is actually more complicated than a proton, it's like a proton with an electron stuck inside it.

Re: Inside the proton, the ‘most complicated thing you could possibly imagine’

#34

Post by calibas »

Reductionist philosophy is very common in science. It's essentially the idea that you can break things down into simpler parts to better understand how everything works.

It's kind of "common sense", if you understand how all the components on a circuit board function individually, then you can piece together how the entire board will function. In computer science, you can reduce everything to operations comparing 1s and 0s, then use that to deterministically recreate higher-level abstractions like strings, floats, and colors on a monitor.

Then there's quantum physics, which turns reductionism on its head. Things are supposed to get less complicated as you get smaller, not more complicated! It's like the more we learn, the more we realize how much we don't know.

Re: Inside the proton, the ‘most complicated thing you could possibly imagine’

#35

Post by SECProto »

andy_xor_andrew wrote: post #18

I just had a really stupid thought, after finishing reading the article. So, the electron is an elementary particle, right? Compared to the proton, the electron is "simple", yes? Despite this difference in complexity, an electron has a charge of -e and a proton has a charge of +e. They are exactly complementary regarding charge (if I am understanding right, I am not a smart person). my question is... why? why must pr…

Not a physicist at all but I'd offer the following thoughts on the question of "why":

- Take a neutron, pull out an electron (and an antineutrino), and you're left with a proton.

- Asking why protons and electrons are so different is a little bit like asking why hydrogen and iodine have exactly opposite charges even though iodine is so much more complex: they're made of different things

Re: Inside the proton, the ‘most complicated thing you could possibly imagine’

#36

Post by exmadscientist »

pdonis wrote: post #13
OldGuyInTheClub wrote: post #5

Is it surprising there are signs of the heavy quarks? The diagrams that include them have tiny but nonzero values. Hearken back to Hitchhiker's - it is not impossible, just highly improbable.

No, it's not surprising theoretically, but experimentally it's still quite an achievement to be able to spot even these rare events.

It was a bit of an open question what would happen with the heavy charm quarks, given that they each mass more than the entire proton, but yeah... anything else would have been a major surprise.

Re: Inside the proton, the ‘most complicated thing you could possibly imagine’

#37

Post by rimunroe »

andy_xor_andrew wrote: post #18

I just had a really stupid thought, after finishing reading the article. So, the electron is an elementary particle, right? Compared to the proton, the electron is "simple", yes? Despite this difference in complexity, an electron has a charge of -e and a proton has a charge of +e. They are exactly complementary regarding charge (if I am understanding right, I am not a smart person). my question is... why? why must pr…

So first off: charge is quantized. Glossing over some weird particles (like quarks) which can't exist by themselves an integer multiple of e as their charge.

It's been a while since I finished undergrad so my knowledge is rusty, but I don't recall any isolatable particles whose charge wasn't -1e, 0, or 1e. If that's the case, the easiest explanation for why they have the same charge is that if they didn't have opposite charges there wouldn't be anything holding them together in an atom.

Re: Inside the proton, the ‘most complicated thing you could possibly imagine’

#38

Post by JumpCrisscross »

Tagbert wrote: post #14
drdeca wrote: post #10

Earlier quoted context omitted.

Huh? With a little bit more what? Complexity? I expected that they would be pretty much the same except with a different mix of the different quarks and such (and also, unstable without having a nucleus to be a part of, and with a neutral charge)

I've heard neutrons described as a union of a proton and an electron based on masses. The reality is probably much more complex.

> neutrons described as a union of a proton and an electron based on masses

If you squish an electron and proton really hard, you'll get a neutron [1].

[1] https://en.wikipedia.org/wiki/Electron_degeneracy_pressure

Re: Inside the proton, the ‘most complicated thing you could possibly imagine’

#40

Post by wiml »

lIl-IIIl wrote: post #28
andy_xor_andrew wrote: post #18

I just had a really stupid thought, after finishing reading the article. So, the electron is an elementary particle, right? Compared to the proton, the electron is "simple", yes? Despite this difference in complexity, an electron has a charge of -e and a proton has a charge of +e. They are exactly complementary regarding charge (if I am understanding right, I am not a smart person). my question is... why? why must pr…

There's also a anti-proton which has a negative charge. I think this is probably the smallest charge there is. A neutron can decay into a proton, electron, and anti-neutrino. So maybe one way to think of it is that a proton is a neutron that is missing an electron, that's why it has the opposite charge of the electron.

The quarks that make up a proton (or neutron, etc) have charges that are multiples of 1/3 the electron charge. So in one sense that is the real unit charge. But because as far as we know quarks can never exist in isolation we can only ever see particles with multiples of the electronic charge.
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