How can photons interact if they travel at the speed of ligh

In summary, the podcast discusses the solar neutrino problem and how interactions with other particles have led to the deduction that neutrinos have mass. They also mention that a particle traveling at the speed of light is "frozen in time and state," but this oversimplifies the concept of neutrino oscillations. The idea is that if all mass eigenstates travel at the same velocity, they cannot acquire a relative phase, which is key to neutrino oscillations. This explanation also raises the question of how photons can interact and change states if they travel at the speed of light.
  • #1
freetheparticle
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I was listening to a podcast about the solar neutrino problem, and they discussed how we have deduced that neutrinos are not massless due to the fact that they interact with other particles (even if this interaction occurs rarely). I paraphrase: "a particle traveling at the speed of light is frozen in time and is frozen in its state. It can never change states." If that is the case, then how come we can see photons coming into and out of existence on Feynman diagrams? If they travel at the speed of light how is it possible for them to interact and change states?
 
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You are misinterpreting what they are saying. They are not saying a massless particle cannot interact. They are also hugely oversimplifying what neutrino oscillations are.
 
  • #3
Orodruin said:
You are misinterpreting what they are saying. They are not saying a massless particle cannot interact. They are also hugely oversimplifying what neutrino oscillations are.
What do you think they mean by "frozen in its state"?
 
  • #4
greswd said:
What do you think they mean by "frozen in its state"?

A more accurate (although still very over simplified) description would be that if all the mass eigenstates travel at the same velocity, which they would if they were massless, they cannot acquire a relative phase. It is the mass eigenstates acquiring different phases that is the basis of neutrino oscillations.
 
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freetheparticle said:
I was listening to a podcast about the solar neutrino problem, and they discussed how we have deduced that neutrinos are not massless due to the fact that they interact with other particles (even if this interaction occurs rarely). I paraphrase: "a particle traveling at the speed of light is frozen in time and is frozen in its state. It can never change states." If that is the case, then how come we can see photons coming into and out of existence on Feynman diagrams? If they travel at the speed of light how is it possible for them to interact and change states?

which podcast is this?
 

1. How can photons have mass if they travel at the speed of light?

Photons do not have mass in the traditional sense. They have energy and momentum, which can be thought of as equivalent to mass. This allows them to interact with matter and other particles, despite their high speed.

2. What is the mechanism for photon interactions at the quantum level?

At the quantum level, photons interact through the exchange of virtual particles. These interactions are described by quantum field theory, which is a mathematical framework that explains the behavior of particles and their interactions.

3. How do photons interact with each other?

Photons can interact with each other through a process called photon-photon scattering. This occurs when two photons collide and exchange energy and momentum. However, the likelihood of this interaction is very low due to the small size of photons and their high speed.

4. Can photons interact with anything other than matter?

Yes, photons can interact with other forms of energy, such as other photons or gravitational fields. This is because photons are not affected by the strong and weak nuclear forces, but only by electromagnetic and gravitational forces.

5. Is it possible for photons to interact with objects without being absorbed or reflected?

Yes, photons can also interact with matter through a process called diffraction. This occurs when photons pass through an object and are scattered, causing a change in their direction. This interaction does not involve absorption or reflection of the photons.

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