Deductively proving the conservation of momentum

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Discussion Overview

The discussion centers on the possibility of deductively proving the conservation of momentum without relying on observation or empirical evidence. Participants explore philosophical implications and the relationship between fundamental principles in physics, such as Newton's third law and Pauli's exclusion principle.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions whether conservation of momentum can be proven deductively, noting that while it can be shown using Newton's third law, that requires inductive reasoning.
  • Another participant cites Noether's theorem, suggesting that if the laws of physics are invariant under spatial translations, then momentum is conserved, but they also note that this approach relies on assumptions.
  • There is a challenge to the idea of proving conservation of momentum purely through logic, with one participant asserting that it is not possible and referencing hypothetical scenarios like reactionless drives.
  • Some participants express skepticism about the relevance of non-scientific questions in a science forum, particularly those that do not allow for empirical testing.

Areas of Agreement / Disagreement

Participants generally disagree on the feasibility of a deductive proof for the conservation of momentum without empirical evidence. There are competing views on the applicability of Noether's theorem and the relevance of philosophical inquiries in a scientific context.

Contextual Notes

The discussion highlights limitations in the assumptions made regarding the nature of proof in physics and the definitions of concepts like force and momentum. There are unresolved questions about the implications of using philosophical reasoning in scientific discourse.

Mektrik
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I won't go into all the details but, to summarize, I'm planning on writing something on the philosophy of science and I was wondering if it's possible to deductively prove, that is without the use of observation or experience, the conservation of momentum. I know that it's possible to prove it using Newton's third law, but that itself requires induction.

As a side note, without meaning to sound too pretentious, is it possible to prove Newton's third law using Pauli's exclusion principle? If so, is the exclusion principle deductive?

Anyway, apologies for my naivety and I look forward to seeing your responses.
 
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Yes, it's called Noether's theorem. If you make the assumption that the laws of physics are invariant under translations in space - that is the laws of physics are the same here as they are in China or on the moon or in another galaxy, then the quantity we define as [itex]m\vec{v}[/itex] in classical mechanics is conserved.

Pauli exclusion principle is purely quantum mechanical, and has nothing to do with Newton's third law. The whole concept of a force is a purely classical idea.
 
dipole said:
Yes, it's called Noether's theorem. If you make the assumption that the laws of physics are invariant under translations in space - that is the laws of physics are the same here as they are in China or on the moon or in another galaxy, then the quantity we define as [itex]m\vec{v}[/itex] in classical mechanics is conserved.

Pauli exclusion principle is purely quantum mechanical, and has nothing to do with Newton's third law. The whole concept of a force is a purely classical idea.

Ahh, for reasons which I won't go into, is there a way to do it without using Noether's theorem? Sorry for not mentioning this earlier and thanks for the reply!
 
Is there a way to prove conservation of momentum based on the pure force of logic along the lines of "cogito ergo sum" without recourse to experiment? Nope, certainly not.

One can conceive of a universe in which reactionless drives exist. Science fiction is full of such creations.
 
jbriggs444 said:
Is there a way to prove conservation of momentum based on the pure force of logic along the lines of "cogito ergo sum" without recourse to experiment? Nope, certainly not.

One can conceive of a universe in which reactionless drives exist. Science fiction is full of such creations.

One could 'conceive' the Moon being made of green cheese but is it relevant to Science?
 
sophiecentaur said:
One could 'conceive' the Moon being made of green cheese but is it relevant to Science?

Certainly not. But the question that was posed was not about science. It specifically repudiated the use of observation and experience.
 
jbriggs444 said:
Certainly not. But the question that was posed was not about science. It specifically repudiated the use of observation and experience.

I have to ask what the point is of considering deliberately non-Science questions* in a Science Forum.
*questions / hypotheses that are not testable.
 

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