Massless Particles: Can Photons Travel Faster than Light?

In summary, there is a common misconception that photons are massless, but they do have a small mass. This is due to the fact that they are traditionally taught to be massless in order to simplify the concept of light and its properties. However, in reality, photons do have a very small mass. This can be seen in their interactions with other particles and their ability to travel at the speed of light. Although some sources may claim that photons can travel faster than the speed of light, this is not true as the speed of light is a fundamental limit in the universe. Overall, the concept of a massless photon is a simplification for teaching purposes and should not be taken as a literal description of its properties.
  • #1
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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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  • #3
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?
 
  • #4
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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  • #5
^ 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 =]
 
  • #6
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?
 
  • #7
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?
 
  • #8
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.
 
  • #9
^ 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.
 

1. Can massless particles travel faster than light?

According to the theory of relativity, the speed of light is the maximum speed at which any object can travel. Therefore, it is not possible for massless particles, such as photons, to travel faster than the speed of light.

2. How can photons have energy if they have no mass?

Although photons have no mass, they still possess energy through their electromagnetic fields. This energy is transferred through the photons' interactions with matter.

3. Do massless particles experience time?

In the theory of relativity, time is relative and can be affected by an object's speed and gravity. Since photons travel at the speed of light, time does not appear to pass for them. This is known as time dilation.

4. Can massless particles be affected by gravity?

Yes, massless particles can be affected by gravity. In fact, gravity is one of the fundamental forces that influences the behavior of photons. This can be seen in the phenomenon of gravitational lensing, where the path of light is curved by the presence of massive objects.

5. What implications do massless particles have for the study of the universe?

Massless particles, such as photons, play a crucial role in the study of the universe. They are responsible for carrying and transferring energy, allowing us to observe and understand distant objects in the universe. They also help us understand the fundamental forces and interactions that govern the universe.

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