A question for the REers.

Momentum, along with energy, also bends space-time.

both things quite closely linked with mass

Quote from: E.Jack on October 16, 2008, 08:12:42 AM

Momentum, along with energy, also bends space-time.

both things quite closely linked with mass

So photons don't have momentum or energy?

I thought since Mass and Energy are interrelated, that photons would curve spacetime slightly.

I thought since Mass and Energy are interrelated, that photons would curve spacetime slightly.

They do.

Quote from: ragnarr on October 16, 2008, 03:04:23 PM

I thought since Mass and Energy are interrelated, that photons would curve spacetime slightly.

They do.

when you say photons, your talking about light right?

Quote from: iznih on October 16, 2008, 11:26:11 AM

Quote from: E.Jack on October 16, 2008, 08:12:42 AM

Momentum, along with energy, also bends space-time.

both things quite closely linked with mass

So photons don't have momentum or energy?

From this statement I thought you were implying that they do not.  I guess I'm confused by what you are questioning.

when you say photons, your talking about light right?

Yes.

From this statement I thought you were implying that they do not.  I guess I'm confused by what you are questioning.

iznih claimed that momentum and energy are closely linked with mass. Since photons are massless, I'm asking him if he is saying that they don't have momentum or energy either.

Quote from: Kingcosmo7 on October 16, 2008, 03:13:05 PM

when you say photons, your talking about light right?

Yes.

Quote from: ragnarr on October 16, 2008, 03:15:22 PM

From this statement I thought you were implying that they do not.  I guess I'm confused by what you are questioning.

iznih claimed that momentum and energy are closely linked with mass. Since photons are massless, I'm asking him if he is saying that they don't have momentum or energy either.

ahhh, gotcha.   

a photon has no mass when v=0m/s is given. its gravitational mass is 0. when travelling at a certain speed v (c in most cases) a photon has the energy E=hv. with E=mc² you can assign a inertial mass to the photon. when creating a pair of matter / antimatter particles with photons you can observe that this inertial mass and the energy is conserved. the momentum of the photon can be calculated by p=mv or by p=h/lambda. it´s easy to show that these two equations give the same result.

that´s what i wanted to express by saying momentum, mass and energy are closely linked.

a photon has no mass when v=0m/s is given. its gravitational mass is 0. when travelling at a certain speed v (c in most cases) a photon has the energy E=hv. with E=mc² you can assign a inertial mass to the photon. when creating a pair of matter / antimatter particles with photons you can observe that this inertial mass and the energy is conserved. the momentum of the photon can be calculated by p=mv or by p=h/lambda. it´s easy to show that these two equations give the same result.

that´s what i wanted to express by saying momentum, mass and energy are closely linked.

Nice save.

thanks