Debunking Claims about Bypassing Newton's 3rd Law and Conservation of Momentum

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Discussion Overview

The discussion revolves around claims regarding potential methods to bypass Newton's 3rd Law and the Conservation of Momentum, particularly in the context of propulsion systems that do not expel mass. Participants explore theoretical concepts and examples, including the use of light and electromagnetic fields, while questioning the validity of such claims.

Discussion Character

  • Debate/contested
  • Exploratory
  • Conceptual clarification

Main Points Raised

  • One participant inquires about claims that suggest it is possible to circumvent Newton's 3rd Law and Conservation of Momentum.
  • Another participant proposes a hypothetical vehicle that uses a heated tungsten piece and a parabolic mirror to propel itself in a vacuum without expelling mass.
  • Some participants argue that methods like solar sails and laser propulsion do not violate Newton's 3rd Law, as they involve mass loss.
  • A participant mentions the concept of a reactionless drive, suggesting that it might be possible to violate Newton's 3rd Law, but not in the manner previously suggested.
  • There is a discussion about the applicability of Newton's 3rd Law in different contexts, particularly in electrodynamics and quantum mechanics.
  • One participant expresses skepticism about the existence of working designs that could violate Newton's laws, while another claims that the law does not always hold true.
  • Examples involving moving charges and magnetic fields are introduced as potential exceptions to the law.
  • A participant describes a hypothetical scenario involving attraction and repulsion between objects, referencing a "Relativistic Effect Capacitor" as a concept that simulates such effects.

Areas of Agreement / Disagreement

Participants generally disagree on the possibility of violating Newton's 3rd Law, with some asserting that no working designs exist that can do so, while others propose theoretical models that might challenge the law under specific conditions.

Contextual Notes

The discussion highlights the limitations of applying Newton's laws universally, particularly in scenarios involving electromagnetic fields and quantum mechanics, without resolving the implications of these limitations.

Jedi_Sawyer
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Does anybody know of claims that there is a way to get around Newton's 3rd Law and Conservation of Momentum and have a link to where I might find that write up?
 
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In what context do you think you can 'get around' those laws?
 
I mean something propelling itself in a vacuum wthout throwing off mass.
For example a vehicle that uses a heated piece of tungsten at the focal point of a parabolic mirror that sends a focused light beam backwards would qualify, although I am looking for solutions that don't use flashlights.
 
Would that really qualify as violating Newton's 3rd law?
 
Jedi_Sawyer said:
I mean something propelling itself in a vacuum wthout throwing off mass.
For example a vehicle that uses a heated piece of tungsten at the focal point of a parabolic mirror that sends a focused light beam backwards would qualify, although I am looking for solutions that don't use flashlights.

Well, I'm not sure, but a solar sail might fit your example. Also, even though light is "massless", whatever you used to generate the power for the light would be losing mass as it's energy stores got lower, with the light carrying away that mass as momentum.
 
You guys are right solar sails, flash lights, and ground based lasers are not violations of Newton's 3rd. There are proposals out there that may be and I am looking for a specific one that i remember.
 
Nothing out there will violate Newtons laws. At least not working designs.
 
Do you mean a reactionless drive? I learned from another thread that it is possible to violate Newton's third law, but not in the manner that you are suggesting. And I'm guessing that it would be against forum rules to provide a link to such a site.
 
Turtlemeister, I don't care what you call such a propulsion method.

Are you saying that Newton's 3rd Law is some sort of scientific religious idea and any thought that it could be violated is forbidden ?
 
  • #10
Jedi_Sawyer said:
Turtlemeister, I don't care what you call such a propulsion method.

Are you saying that Newton's 3rd Law is some sort of scientific religious idea and any thought that it could be violated is forbidden ?

Violating it? Yes. Not violating it but designing a reactionless drive? No. As long as it follows the accepted views of science then you are fine.
 
  • #11
Drakkith said:
Nothing out there will violate Newtons laws. At least not working designs.

Well, I have no idea if it has any relation to a working design, but "every action has an equal and opposite reaction" doesn't always hold.
 
  • #12
olivermsun said:
Well, I have no idea if it has any relation to a working design, but "every action has an equal and opposite reaction" doesn't always hold.

Can you give me an example?
 
  • #13
Hint: Electrodynamics.
 
  • #14
Drakkith said:
Can you give me an example?

Think moving charges and magnetic fields. (I can't claim credit for this textbook example).

Edit: Doc Al beat me to it. :approve:
 
  • #15
Jedi_Sawyer said:
Turtlemeister, I don't care what you call such a propulsion method.

Are you saying that Newton's 3rd Law is some sort of scientific religious idea and any thought that it could be violated is forbidden ?

No, that's not what I'm saying at all. How did you get that out of my post? Anyway, here is the link to the thread that I mentioned. https://www.physicsforums.com/showthread.php?t=521781
 
  • #16
Doc Al said:
Hint: Electrodynamics.

olivermsun said:
Think moving charges and magnetic fields. (I can't claim credit for this textbook example).

Edit: Doc Al beat me to it. :approve:

I guess I should have said: Nothing violates the 3rd law when you use it where it applies.
 
  • #17
Drakkith said:
I guess I should have said: Nothing violates the 3rd law when you use it where it applies.

:smile:
That is very true. But then, the third law applies in most scenarios, but not everywhere. Then why are they called Newton's Universal Laws of Motion? They should be the Universal Except for Scenarios Involving Electromagnetic Fields and Quantum Mechanics Laws of Motion.
 
  • #18
I went to the posting that Turtlemeister referred me to and the guy who posted it thought that the link he referred to claimed a violation of Newton's 3rd but actually it didn't.

An example of what I'm talking about; Suppose that Object 1 is attracted to Object 2 which is repelled by Object 1. Together they would accelerate away with Object 1 chasing Object 2. As long as there is energy to chase and run. The Relativistic Effect Capacitor where each plate is switched individually to one of three state purports to simulate this effect.

Still that is not what I am looking for.
 

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