Faster than light

[Raider]

Why is that?

 

It seems like we'd just see their future as our past but otherwise normal.

[Radical Edward]

Originally posted by MajinVegeta

The most important point, Radical Edward, is that if electrons did travel at c+, then, we wouldn't be able to detect them in the first place.

 

yes we would, they would emit Cherenkov radiation, unless there is some physical law forbidding superluminal particles from interacting with subluminal and luminal particles*. If there were some law, then superluminal particles would be empirically non existant to us. Furthermore, that point has nothing to do with anything much that I have seen in the topic so far.

 

*yes yes, wave particle duality is important. I am referring to photons as particles purely for simplicity.

[MajinVegeta]

Originally posted by Raider

Why is that?

Well, my reasoning (which excluded Chrenkov radiation) was on the premise that when a particle travels faster than light, it...well E=mc2; it turns into energy. What I was forgetting was that it looses energy and as it looses more energy, it goes faster. That's the key; the particle would emit Chrenkov radiation, which I believe is blue shifted(?).

 

It seems like we'd just see their future as our past but otherwise normal.

 

??? no comprehendo.

 

[fafalone]

why would it turn into energy above c?

 

e^2=(pc)^2+m^2c^4

 

and p=mv.

[JaKiri]

Originally posted by MajinVegeta

Well, my reasoning (which excluded Chrenkov radiation) was on the premise that when a particle travels faster than light, it...well E=mc2; it turns into energy.

 

Nah, that's just an equivilency with c^2 as the constant.

 

What you want are the lorenz transforms, I think they're described in a sticky on this board.

[MajinVegeta]

I read about the Lorenz trans. and I didn't quite study them as much as I would have liked. How do you apply it to particles and the sort?

 

 

fafalone: I was discussing E=mc^2 on another forum, and my interpretation of mass turning into energy when traveling at c^2 was correct. Do you have a different answer?

[fafalone]

If we're always wrong and the other forums are always right, why don't you just proceed to refrain from departing this forum with magical entities who are never wrong.

 

That interpretation is NOT correct. It implies conventional acceleration to c^2, which is obviously impossible. Your idea comes from the fact that under the current set of laws, only massless particles can travel at c. By this logic, light that's travelling slower than c could have mass. Furthermore, mass increases as speed increases; it goes towards infinity, not zero.

 

Second of all, it's not even e=mc^2, if you use only this equation to talk about anything like this, you're wrong. You have to use the complete equation, not the simplification for circumstances that cannot exist.

[JaKiri]

Originally posted by MajinVegeta

fafalone: I was discussing E=mc^2 on another forum, and my interpretation of mass turning into energy when traveling at c^2 was correct. Do you have a different answer?

 

If that's right, then I'm wrong, and all the special relativity I was taught last term was wrong.

 

Between the University of Cambridge, Richard P Feynman (who's lectures I referred to on occasion) et al, and the other forum, I think I'll go with the physicists.

[Radical Edward]

Originally posted by MajinVegeta

I was discussing E=mc^2 on another forum, and my interpretation of mass turning into energy when traveling at c^2 was correct. Do you have a different answer?

 

the full equation is:

 

E²=p²c² + m²c⁴

 

so the E=mc² equivalence only applies to a particle with mass, in it's rest frame.

[fafalone]

It applies to massless particles too, since p = hf/c

[Radical Edward]

yopu're right of course, but that is the E=pc equivalence (having set the rest mass to zero).... sorry If I didn't make myself clear on that. I was just trying to point out to him where the E=mc² thing comes from.

[MajinVegeta]

Originally posted by fafalone

It applies to massless particles too, since p = hf/c

 

Massless particles? Does that mean that a particle is just made up of energy?

[Radical Edward]

like a photon, they are massless... though calling them particles is a bit flawed too as a result of wave-particle duality.

 

saying they are "made of energy" is a bit of a grey area, since what is energy? Energy is always manifest in some form, in an excitation of some field, or electron, or momentum or something, but it never exists as an entity in itself. Energy is merely a conserved quantity which may take one of many different forms. Photons in particular being excitations of the electomagnetic field.

[KHinfcube22]

Originally posted by Radical Edward

like a photon, they are massless... though calling them particles is a bit flawed too as a result of wave-particle duality.

 

saying they are "made of energy" is a bit of a grey area, since what is energy? Energy is always manifest in some form, in an excitation of some field, or electron, or momentum or something, but it never exists as an entity in itself. Energy is merely a conserved quantity which may take one of many different forms. Photons in particular being excitations of the electomagnetic field.

 

So couldn't this mean that energy is an illusion?

[JaKiri]

Originally posted by KHinfcube22

So couldn't this mean that energy is an illusion?

 

No. Energy is conserved through all measureable interactions.

 

Mass is just a type of energy.

[MajinVegeta]

I've finally got it! Tell me if this is right: energy is made up of massless particles!!

What confused me (and the confusion is still lingering) was that energy could be made up of particles with mass. Now, I'm wondering about the subatomic particles inside the particles that have mass. Yes, what about them? don't they have mass?

[JaKiri]

Nope. Mass is a form of energy. (Your E = mc^2 and the like.)

 

Of the other forms of energy, there are two types.

 

The first is potential energy in a field (be it from the strong nuclear force, weak nf, electromagnetic or gravitational), the interaction taking place by carrier particles (eg. the photon, or the graviton).

 

The second is kinetic energy, which is from movement relative to the rest frame, and so is a bit more ambiguous.

 

ps. I'm assuming the graviton exists.

[MajinVegeta]

Lets go step by step:

 

Energy is made up of massless particles. Right?

[Preston Taist]

If you look at it like that than yes.

[Preston Taist]

If you talk strings than everything is energy.

[Radical Edward]

Originally posted by MajinVegeta

Lets go step by step:

 

Energy is made up of massless particles. Right?

 

no, energy doesn't exist like that. I think you are talking about photons, which are an excitation of a field, which comes under the category potential as MrL described (in this case an oscillating potential) MrL was right in saying that the three forms of energz are:

 

mass, kinetic and potential energy.

[KHinfcube22]

What type of energy is created when one turns an object of mass into energy?

[JaKiri]

Originally posted by KHinfcube22

What type of energy is created when one turns an object of mass into energy?

 

If we're talking Fission or Fusion, kinetic and photons.

 

If we're talking matter/antimatter reactions, photons.

[MajinVegeta]

Originally posted by Preston Taist

If you talk strings than everything is energy.

 

Yes, but in a sense, everything is energy. Forms of energy.

 

Originally posted by Radical Edward

no, energy doesn't exist like that. I think you are talking about photons, which are an excitation of a field, which comes under the category potential as MrL described (in this case an oscillating potential) MrL was right in saying that the three forms of energz are:

 

mass, kinetic and potential energy.

 

What is energy made up of?

[JaKiri]

Originally posted by MajinVegeta

What is energy made up of?

 

Particles, of varying spins.