Massless Particles: Can Photons Travel Faster than Light?

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Discussion Overview

The discussion centers on the nature of photons, specifically whether they are massless and if they can travel faster than the speed of light. Participants explore concepts from special relativity, the implications of mass on particle speed, and the interpretation of various sources on the topic.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions the requirement for particles to be massless to travel at the speed of light, expressing confusion over the concept of mass in relation to photons.
  • Another participant asserts that photons are massless according to special relativity, but expresses uncertainty about whether this is an exception or a general rule.
  • There is a claim that photons cannot exceed the speed of light in a vacuum, although they can travel slower in mediums like glass, where massive particles can briefly exceed light speed and emit Cherenkov radiation.
  • Several participants express difficulty in understanding the concept of massless particles and the implications of the sources provided, indicating conflicting information about whether photons have mass.
  • A participant requests a simpler explanation of the statement that "photons are traditionally said to be massless," highlighting their struggle with the material.
  • One participant acknowledges their limited knowledge in physics but expresses gratitude for the discussion, indicating a desire to contribute further.

Areas of Agreement / Disagreement

Participants exhibit a lack of consensus regarding the mass of photons and their ability to travel faster than light, with multiple competing views and ongoing confusion about the topic.

Contextual Notes

Participants reference various sources that appear to present differing interpretations of photon mass and speed, leading to uncertainty and a lack of clarity in the discussion.

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Hey, well I've just been having a discussion with someone this minute, about traveling at the speed of light. We said that for something to travel at the speed of light, the partcile will need to be massless, but when I looked it up, I found that a particle has to have mass? Does a photon have a mass? It can be made to go faster than the speed of light? How does that work? I mean, how can something with mass, travel faster than the speed of light?
 
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I've always thought, that there is no such thing as a massless particle? Special relativity gives a photon no mass, I don't understand that is that like an exception or something?

AND I've read a photon can travel faster than the speed of light, but yet has a mass?
 
CrawfordK said:
I've always thought, that there is no such thing as a massless particle?
Read Ranger's links, particularly the first one.

AND I've read a photon can travel faster than the speed of light
The speed of light in a medium (e.g., glass) is less than the speed of light in a vacuum. Photons, which are indeed massless, cannot travel faster than speed of light, period. Massive particles traveling near the speed of light can briefly exceed the speed of light in when the enter some medium, in which case they emit http://en.wikipedia.org/wiki/Cherenkov_radiation" .
 
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^ I have read the first link, but I am really struggling to understand it? Can anyone explain it more simply?

"Photons are traditionally said to be massless."

I'm really struggling to understand what it is saying? Sorry, it just doesn't make sense to me? Some places say yes and some say no? Or is it not taking its mass into account as it is negligable?

I don't want it to come across as if I haven't read through it, I have a few times it's just not making sense to me =/ cheers for the help so far =]
 
CrawfordK said:
AND I've read a photon can travel faster than the speed of light, but yet has a mass?
Where did you read this?
 
CrawfordK said:
^ I have read the first link, but I am really struggling to understand it? Can anyone explain it more simply?

"Photons are traditionally said to be massless."

I'm really struggling to understand what it is saying? Sorry, it just doesn't make sense to me? Some places say yes and some say no? Or is it not taking its mass into account as it is negligable?

I don't want it to come across as if I haven't read through it, I have a few times it's just not making sense to me =/ cheers for the help so far =]

Doc Al said:
Where did you read this?

Well, as I've said above, I am not sure if a photon has mass yet, because I've always been taught that there is no such thing as a massless object.


I am really struggling to get to grasps with this, the links proved very difficult to understand.

I just really want to know what I posted in my first post, could anyone explain it to me?
 
Which part of "Photons are traditionally said to be massless" did you not understand?

You should also read the Physics Forums FAQ in this subforum.

Zz.
 
^ It's just clicked, thank you so much guys/gals my knowledge of this area of physics is very near to 0 so things take a while to make sense but thank you so much, now atleast I can contribute towards a discussion on such matters, even if it is still limited.
 

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