Would there be an upper limit to density in QM?

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    Density Limit Qm
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Discussion Overview

The discussion revolves around the concept of whether there is an upper limit to the density of an object in quantum mechanics (QM), particularly in the context of black holes. Participants explore theoretical implications and interpretations related to density, quantum behavior, and the nature of black holes.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions if there is an upper limit to density for objects at the smallest size allowable in QM, particularly considering the nature of black holes.
  • Another participant states that, according to current understanding, there is no upper limit to density in QM or classical mechanics, but acknowledges that this has not been tested at extremely high densities and suggests unknown physics may emerge.
  • A participant recalls the particle in a box concept and wonders if it could be applied to particles within a black hole, suggesting the event horizon might act as an infinite potential wall.
  • Another participant counters that the event horizon of a black hole does not function like a wall or barrier, implying a misunderstanding of the concept.

Areas of Agreement / Disagreement

Participants express differing views on the implications of density limits in QM and the nature of black holes. There is no consensus on whether an upper limit exists or how concepts like the event horizon should be interpreted.

Contextual Notes

The discussion touches on theoretical aspects of QM and classical mechanics, with limitations regarding the application of these theories at high densities and the interpretation of black hole physics remaining unresolved.

benorin
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Admitted I know very little about QM, but I've been thinking about black holes and I wondered if there would be an upper limit to density of an object of the smallest size allowable if the particles are not being observed by anyone (since black holes are black)? I ignorantly wondered that classically perhaps even though an atom is 99.99% empty space or so there seemly would be a logical upper limit to the density of an object because 0.01% of that atom is not empty but in QM all is waves and probability so this might not be the case here. Please make your answers understandable (I've taken a standard 3 semester sequence course of physics and math through analysis). Thanks for your time physicists, hope you don't mind a noob question.
 
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As far as quantum mechanics (and also classical mechanics with its point particles) is concerned, there is no upper limit to the density of an object.
However, nether of these theories have been tested at arbitrarily high densities and it's quite likely that some as-yet-unknown physics will come into play at some point.

So the answer to your question is basically "as far as we know QM doesn't enforce a limit, but that doesn't mean there isn't one".
 
It's been 10+ years since I took physics in college and clearly I've forgotten some things (thanks for being kind) but I remember the particle in a box lecture quite well (barrier tunneling). Could this approach be applied to particle in a black hole? Because when I think what in nature might qualify as an infinite potential wall I think the event horizon of a black hole might just be it.
 
benorin said:
Could this approach be applied to particle in a black hole? Because when I think what in nature might qualify as an infinite potential wall I think the event horizon of a black hole might just be it.
No. The event horizon of a black hole is nothing like a wall or barrier.
 
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