Can a photon have a rest mass despite being massless?

Click For Summary

Discussion Overview

The discussion revolves around the concept of whether a photon can possess a rest mass despite being classified as massless. Participants explore implications from string theory, the nature of mass, and the characteristics of point-like versus extended objects in physics.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the assumption that a string, which has measurable spatial dimensions, must have mass, and relates this to the concept of a photon having rest mass.
  • Another participant argues that strings can be massless despite having finite spatial extent, referencing the existence of tachyons and the implications for stability in string theory.
  • A different viewpoint suggests that mass arises from interactions with the Higgs field, implying that without such interactions, massless particles can exist.
  • Further discussion raises the philosophical question of whether a massless point-like particle can be said to "exist" and how this compares to the existence of a massless string.
  • One participant notes that current theories suggest answers to these questions are speculative and not definitively established.
  • Another proposes a conceptual framework where the distinction between massive and massless particles could relate to their orientation in time versus spacelike dimensions.

Areas of Agreement / Disagreement

Participants express various viewpoints, and no consensus is reached regarding the nature of mass in relation to photons and strings. The discussion remains unresolved with multiple competing ideas presented.

Contextual Notes

Participants acknowledge the speculative nature of their discussions, particularly regarding the implications of string theory and the role of the Higgs field in defining mass.

zachfoltz
Messages
27
Reaction score
0
I'm new to physics, so I'm sorry if this is a dumb question. If a string cannot be point like, it has measurable spatial dimensions, then it must have mass. Well if a string was vibrating at the resonant frequency of a photon, and at rest it must have mass and therefore a nonzero rest mass. This is obviously wrong because according to SR a photon must have 0 rest mass. what am I getting wrong here?

Thanks
 
Physics news on Phys.org
You're right, a string does have a finite spatial extent. However, just because it is not point like does not mean it has to have mass. In fact, when bosonic string theory was first being studied, people discovered objects with negative mass squared. The presence of tachyons (objects with imaginary mass) showed that the vacuum was unstable and showed the need for fermions.

It certainly is strange to think about, but string theory does have objects that are massless but not pointlike. To me a massless point like object is just as strange when you think about it!
 
A naive way of looking at is that strings are 1 dimensional, so they don't necessarily have mass. Current theory seems to say that mass results from interaction with the Higgs field. Without Higgs nothing would have mass.
 
Your right, that is pretty weird as well!

But that raises the question, if a point like particle has no mass, it "doesn't exist", or at least isn't observable. However if a string doesn't have mass, do we treat it the same as a point particle? or does it exist spatially but have no mass?

Thanks for the help it's much appreciated!
 
Current state of physics theory is such that any answer to your questions are very speculative.
 
One way to get some particles that are massive, while others are massless, is to conceptualize the distinction as related to an orientation to timeline v. spacelike dimensions respectively.
 

Similar threads

  • · Replies 19 ·
Replies
19
Views
3K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 11 ·
Replies
11
Views
2K
Replies
3
Views
2K
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 4 ·
Replies
4
Views
5K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 8 ·
Replies
8
Views
1K
  • · Replies 19 ·
Replies
19
Views
4K
  • · Replies 3 ·
Replies
3
Views
2K