Perfectly Rigid Bodies and Quarks

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Discussion Overview

The discussion revolves around the nature of quarks and their behavior under compression, particularly in relation to the concept of perfectly rigid bodies and the implications for information transmission. Participants explore the theoretical limits of compression at the quark level, the implications of special relativity, and the nature of quarks as fundamental particles or bound states.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that quarks, like other particles, cannot be perfectly rigid and question how they might behave under compression.
  • There is a suggestion that when solids are compressed, the atoms get closer together rather than being compressed themselves, raising questions about the behavior of quarks in this context.
  • One participant mentions that under extreme conditions, such as in neutron stars, protons and electrons can merge to form neutrons, potentially leading to a 'soup' of free quarks.
  • Another participant expresses uncertainty about whether thinking of quarks in a classical way might lead to misconceptions about their properties, particularly regarding information transmission.
  • It is proposed that quarks are treated as strict point particles in quantum field theory, making compression difficult to conceptualize.
  • Some participants discuss the idea that if quarks are bound states of more fundamental entities, then sufficient pressure could alter their structure, similar to atomic behavior under pressure.
  • There is a comparison made between quarks and electrons, noting that both are considered indivisible particles, but quarks do not exist independently and are always found in combinations.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nature of quarks and their behavior under compression, with multiple competing views and uncertainties remaining throughout the discussion.

Contextual Notes

The discussion highlights limitations in understanding the behavior of quarks, particularly regarding the assumptions about their rigidity, independence, and the implications of special relativity on information transmission.

Meatbot
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Forgive me if this is a noob question. I know there are no perfectly rigid bodies so that if you had a light-year long rod and pushed it, the other end would not move immediately because if it could, then information could be transmitted FTL.

But, what if you pushed on a quark in the same manner? Would it get compressed as well for a brief moment since it would take time for the movement to reach the other side of it? I would suppose quarks can't be rigid either and it must get compressed somehow. How can you compress a quark though?
 
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Going down to the quark level is too extreme. When a solid is compressed, the atoms that make it up are not compressed, they just get closer together.
 
Mentz114 said:
Going down to the quark level is too extreme. When a solid is compressed, the atoms that make it up are not compressed, they just get closer together.

There is a caveat to that under extreme conditions. While this is correct for normal pressure, the gravity of a neutron star does in fact compress the electron orbitals into the nucleus. Protons and electrons merge to form neutrons, and some theories suggest that there might in fact be a 'soup' of free quarks in the centre. That's out of my area, though, so someone like Space Tiger would have to sort it out.
 
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Mentz114 said:
Going down to the quark level is too extreme. When a solid is compressed, the atoms that make it up are not compressed, they just get closer together.

Yeah...I knew that part actually. Sorry I was imprecise. But if no compression can take place in a quark and there are no quark constituents that can get closer, then it would seem you could transmit information FTL over the diameter of the quark. That can't be right though. Or am I thinking of a quark in too much of a classical way?
 
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Meatbot said:
Or am I thinking of a quark in too much of a classical way?

I suspect that to be the case. While I'm neither a particle physicist nor an astrophysicist, I've done a bit of reading in both subjects (ie: I know nothing). It seems to me that since a quark (which can't normally exist in isolation) is so much smaller than a quantum of whatever information-carrying bosun you choose, the question is irrelevant. Again, though, wait for an expert to answer it.
 
Hi Meatbot,
... then it would seem you could transmit information FTL over the diameter of the quark. That can't be right though. Or am I thinking of a quark in too much of a classical way?

Quarks don't exist independently at our temperatures but are bound inside nuclei, and so cannot be 'pushed' in the normal sense. I understand your question, and probably nature has arranged that this kind of FTL transmission is impossible.
 
Meatbot said:
Would it get compressed as well for a brief moment since it would take time for the movement to reach the other side of it? I would suppose quarks can't be rigid either and it must get compressed somehow. How can you compress a quark though?

In QFT, quarks are strict point particles. Or better, the bookkeeping of strict point particles like quarks, together with requirements from special relativity, give rise to the existence of quantum fields. So when considering them as strict points, it is going to be difficult to compress them. However, if ever it turns out that quarks are bound states of more fundamental things, then they become structures such as atoms, and sufficient pressure will then probably result in a change in the structure of this bound state (such as sufficient pressure can change the binding distance between atoms in a crystal for instance).

So, or quarks are fundamental point particles (as is assumed in QCD), and then you cannot "compress" them, or they are bound structures (such as in technicolor for instance), and then of course you can change their structure, but this will have a dynamics, which will respect special relativity, just like in our steel rod.
 
Meatbot said:
But if no compression can take place in a quark and there are no quark constituents that can get closer, then it would seem you could transmit information FTL over the diameter of the quark.
That can't be right though. Or am I thinking of a quark in too much of a classical way?

I would suppose quarks can't be rigid either and it must get compressed somehow. How can you compress a quark though?

Your question would be exactly the same for an electron - electrons and quarks are both indivisible particles (erm … so far as we know!).

And we know how to deal with individual electrons, while individual quarks don't seem to exist (so far as we know, they can only come in pairs or threes).

Electrons are normally considered to be point particles with no diameter (or waves!), so there's nothing to compress, and no distance to transmit information.
 

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