Speed Quanta: Is There a Lower Limit?

  • Context: Graduate 
  • Thread starter Thread starter Physonic
  • Start date Start date
  • Tags Tags
    Limit Speed
Click For Summary

Discussion Overview

The discussion revolves around the concept of whether there is a lower limit to speed, akin to the established upper limit of the speed of light. Participants explore the implications of quantum mechanics and the uncertainty principle in relation to speed quantization.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants propose that there is no quanta for speed, suggesting that a particle's speed can approach zero given sufficient uncertainty in its position.
  • Others argue that the uncertainty principle applies specifically to momentum and position, and not directly to speed, indicating a distinction in how these concepts are related.
  • A participant mentions that in the case of light, the lower limit is defined as the speed of light (c), while also referencing the de Broglie relation for particles, suggesting that momentum might be a more relevant quantity to consider.
  • There is a challenge to the interpretation of the uncertainty principle, with a participant asserting that the relationship between speed and uncertainty is not as straightforward as presented.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether there is a lower limit for speed. Multiple competing views remain regarding the implications of the uncertainty principle and the definitions of speed and momentum.

Contextual Notes

Participants express differing interpretations of the uncertainty principle and its application to speed and momentum, highlighting the complexity of these concepts in quantum mechanics. There are unresolved nuances regarding the definitions and relationships between speed, position, and momentum.

Physonic
Messages
5
Reaction score
0
we all know that there is upper limit for speed that is speed of light, but is there a lower limit, I mean is there quanta for speed.
 
Physics news on Phys.org
There is no quanta for speed.
The effective "lower limit" for speed will be the uncertainty principle, because of the wave-particle duality. The speed of a particle can be arbitrarily close to zero as long as the uncertainty in the position is sufficiently large (i.e. the particle is delocalized).

If a particle is confined to any discrete region of space, there will be a lower limit on its velocity. Hope this helps.
 
lzkelley said:
There is no quanta for speed.
The effective "lower limit" for speed will be the uncertainty principle, because of the wave-particle duality. The speed of a particle can be arbitrarily close to zero as long as the uncertainty in the position is sufficiently large (i.e. the particle is delocalized).

If a particle is confined to any discrete region of space, there will be a lower limit on its velocity. Hope this helps.

Thank you that helped.
 
No, not at all.

The uncertainty principle applies for dXdP, not dXd(mv) which is a slight difference; in the case of light the uncertainty applies to its wavelength, frequency and energy via the relation P = hf/c where f is the frequency or alternatively, P = h/w where w is the wavelength.

Correct me if I'm wrong but that's how it seems.
 
Last edited:
In the case of light, the lower limit is quite well defined... its still just c. but even in the not photon case, by the deBroglie equation the same relation applies (p=h/L).
dst : your point, thought true, is trivial and semantical. In quantum mechanics there is no way to define an instantaneous (accurate) velocity; however, the concept of spatial motion does apply very closely to momentum --> hence it is the term that we should be looking at, in the "lower limit of velocity."
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 18 ·
Replies
18
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 20 ·
Replies
20
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 15 ·
Replies
15
Views
2K