Exploring the Hypothetical Graviton: Is It Truly Massless?

In summary, the graviton is a hypothetical particle that is massless. It is also possible for a particle to have a mass that is so small that it is 0, which is the case for photons.
  • #1
FeDeX_LaTeX
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I was just reading a Wikipedia article about a hypothetical particle known as the graviton. It stated that it was massless -- but how is this possible? I thought that every particle has to have a mass.
 
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  • #2
Yes it would be massless. So is the photon. In the standard model, all particles are massless, but they appear massive because of their interactions with the hypothetical Higgs particle.

Torquil
 
  • #3
Photons are particles that don't have mass, and that enables them to travel at the speed of light. :wink:
 
  • #4
So a particle has to have a mass of 0 to reach the speed of light on the dot?

An electron has a mass of 9.11*10^-31 kg... is that why we say that an electron can get very close to the speed of light, but not exactly to the speed of light?

Also, when we say 'massless', do we mean the mass is so small that it is 0? I am probably wrong...

EDIT: Just did a google search on photon mass and it yields '0'. So if F = ma, then;

F/a = m

F/a = 0

So F/a must be 0? Confused...

http://www.aip.org/pnu/2003/split/625-2.html - this article also seems to be talking about the limit of a photon mass...
 
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  • #5
FeDeX_LaTeX said:
So a particle has to have a mass of 0 to reach the speed of light on the dot?

An electron has a mass of 9.11*10^-31 kg... is that why we say that an electron can get very close to the speed of light, but not exactly to the speed of light?

It is why it cannot move at the speed of light. But any massive particle can get arbitrarily close to the speed of light. The higher the mass, the more energy is needed to reach a given speed. Massless particles move atthe speed of light in a vaccuum. Massive particles move at any speed less than the speed of light.

Also, when we say 'massless', do we mean the mass is so small that it is 0? I am probably wrong...

EDIT: Just did a google search on photon mass and it yields '0'. So if F = ma, then;

F/a = m

F/a = 0

So F/a must be 0? Confused...

Photon movement is out of the domain of Newtonian dynamics. So it doesn't make sense to apply Newtons law as you have written it to a photon. To describe movements of massless particles, you need to apply Einsteins theory of relativity.

http://www.aip.org/pnu/2003/split/625-2.html - this article also seems to be talking about the limit of a photon mass...

This means that experiments have shown that the poton mass is less than some experimentally observed amount. The accepted theory says that the photon is massless, so theory and experiment are consistent. Everything must be checked experimentally, and experiments always have uncertainties, so it would not show directly that m=0 for a photon. Experiments will never determine that the mass of the photon is exactly zero, because that is impossible.

Torquil
 
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  • #6
FeDeX_LaTeX said:
So a particle has to have a mass of 0 to reach the speed of light on the dot?

Yes! :smile:

(or rather, it doesn't reach the speed of light, it can only be at the speed of light :wink:)
Also, when we say 'massless', do we mean the mass is so small that it is 0? I am probably wrong...

No, we mean the mass (the rest-mass, of course) actually is zero.
EDIT: Just did a google search on photon mass and it yields '0'. So if F = ma, then;

F/a = m

F/a = 0

So F/a must be 0? Confused...
torquil said:
Photon movement is out of the domain of Newtonian dynamics. So it doesn't make sense to apply Newtons law as you have written it to a photon. To describe movements of massless particles, you need to apply Einsteins theory of relativity.

No, I disagree.

This is the danger of using the "easy" version of Newton's second law … F = ma

The official version is "force = rate of change of momentum", or F = dp/dt.

For an ordinary particle, m ≠ 0, and so p = mv, and therefore F = dp/dt = ma.

For a photon, m = 0, but the Newtonian F = dp/dt is still valid. :smile:
 
  • #7
tiny-tim said:
No, I disagree.

This is the danger of using the "easy" version of Newton's second law … F = ma

The official version is "force = rate of change of momentum", or F = dp/dt.

For an ordinary particle, m ≠ 0, and so p = mv, and therefore F = dp/dt = ma.

For a photon, m = 0, but the Newtonian F = dp/dt is still valid. :smile:

Agreed! :smile:

Torquil
 

Related to Exploring the Hypothetical Graviton: Is It Truly Massless?

1. What is a graviton?

A graviton is a hypothetical particle that is theorized to be the carrier of gravity in the universe. It is a fundamental particle, meaning it cannot be broken down into smaller pieces, and is thought to have zero mass and travel at the speed of light.

2. Why is the graviton considered to be massless?

The graviton is considered to be massless because it is a type of boson, which are particles that do not have mass. This is based on the Standard Model of particle physics, which describes the fundamental particles and forces in the universe.

3. How is the graviton related to gravity?

The graviton is thought to be the mediator of gravity, meaning it carries the force of gravity between particles with mass. Just as photons are the carriers of the electromagnetic force, gravitons are believed to be the carriers of the gravitational force.

4. Is there any evidence for the existence of gravitons?

Currently, there is no direct evidence for the existence of gravitons. However, their existence is supported by the mathematical framework of quantum field theory and the Standard Model. Additionally, experiments such as the detection of gravitational waves indirectly support the existence of gravitons.

5. How do scientists plan to explore the hypothetical graviton?

Scientists plan to explore the hypothetical graviton through experiments and observations. This includes studying the behavior of particles at the smallest scales, such as in particle colliders, and observing the effects of gravity on a cosmic scale. Researchers also continue to develop new theories and models that can potentially explain the nature of gravitons and their role in the universe.

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