if photons had mass

[Daniel-K]

just wondering if photons did have mass would our cameras become heavier after taking a picture? dont know how hard if would be to measure that though lol

[VigdisVZ]

I doubt stars would be as long lasting, and planets could stay in orbit if that was the case (yet alone form if the igniting suns started to blast away at their gas disks).

Interesting thought however.

[Daniel-K]

ah well just a thought

[sologuitarist61]

Not sure we would be here at all if photons had mass. You cannot really change just one thing in Physics without altering almost everything else in the process (happy to be proved wrong of course ), and we probably wouldn't exist at all.

[Cath]

I think if protons had mass we'd be in serious trouble lol!

[andrew s]

While photons don't have rest mass they do have energy and via E=mc2 they have an equivalent mass. In fact Einstein derived the equivalence of mass and energy by considering a thought experiment in which a photon is emitted from one end of an enclosed box and absorbed at the other. Form the shift in the centre of gravity of the box and relation between the energy and momentum of a photon he got E=mc2. So in fact absorbing a photon (all else being equal) does increase the mass of the CCD. Mark you as it is emitting and absorbing photons from its case all the time you would have a difficult job isolating it specifically!

Regards Andrew

[VigdisVZ]

Now that you say it, solar sails are possible on paper atleast.

[sologuitarist61]

Now that you say it, solar sails are possible on paper atleast.

That is true

[Earl]

Now that you say it, solar sails are possible on paper atleast.

They are a bit big though

[Islander]

If photons had mass, it would have serious implications for the speed of light apart from anything else.

[Naemeth]

If photons had mass, it would have serious implications for the speed of light apart from anything else.

Beyond what Variable Speed of Light implicated?

If we were to take the speed of light as a variable, rather than a constant, we'd probably have to rewrite a lot of physics.

[Islander]

Well the speed of light is variable anyway - it;s only a constant in a vacuum.

I know what you mean though it would cause a somewhat major rewrite of the laws of physics if it did have mass. Photons are the only gauge boson (force carrier) to have no mass.

[Ronnie67]

Neutrons and Protons have approximately the same mass, and electrons have comparatively almost no mass!

Protons do have mass, but not very much. A proton's mass is 1.66 x 10-24g, and it takes 6.02 x 1023 of them to make a gram (with thanks to the Italian chemist Avogadro, whom that number is named for).

[Islander]

Neutrons and Protons have approximately the same mass, and electrons have comparatively almost no mass!

Protons do have mass, but not very much. A proton's mass is 1.66 x 10-24g, and it takes 6.02 x 1023of them to make a gram (with thanks to the Italian chemist Avogadro, whom that number is named for).

We were discussing the photon - the gauge boson for the electromagnetic force rather than the proton which is a hadron consisting of two up quarks and one down quark.

[badgerchap]

I think the OP kinda means, do photons stay in the camera when they arrive?

I suppose even how it is they confer energy to the camera and due to e=mc^2 they will impart some small (very) mass. However, this energy presumably is radiated out as heat over time.

As for solar sails, aren't the Japanese testing one out at the moment? I'm fairly sure I read a few years ago that they put a small proof of concept sail in orbit...

[Islander]

They don't stay in the camera - they're gauge bosons or charge carriers. When they reach the CCD they change the energy state of electrons in atoms in the CCD cells and this effect is amplified to produce a signal (yes I know it's a very basic description). Once they give up their energy they no longer exist.

[badgerchap]

Yeah so the energy they give to electrons in the CCD should infer an infinitesimally small amount of mass

[Islander]

No, it either moves the electron up a level or liberates it (absorption). When the CCD is 'read' the electron moves back to its original energy state releasing another photon as it does so (emission). This produces heat. Again a simplification but the mass of the electron doesn't change, only its energy level.

[Ronnie67]

Oooppsss, mistaken on the topic guys. sorry

[badgerchap]

Dude I agree completely, but I mean something else. On a larger scale, if you were to leave the camera (sensor or no sensor) in the sun, it would get warm, I.e. have more energy and therefore more mass. True it is a minuscule amount and even less in the case here, but it still holds.

[Islander]

Nope, energy or mass not energy and mass.

[George Jones]

Photons have zero rest mass, but a box that contains only photons weighs more than the same box that has a vacuum inside.

[Islander]

The box would have to be made from medium that reflects perfectly (i.e. totally lossless) at any frequency/energy though.

[E621Keith]

Now that you say it, solar sails are possible on paper atleast.

On paper? There is one working in practice onboard IKAROS.

http://www.jspec.jax...ity/ikaros.html

[J_M_Franklin]

One of the fundamental issues is modern physics is that we actually do not know if Photons have mass or not. It has not been shown with current technology that they have mass, and all indications are that they do not, but this could be a limitation of our technology.

It's a very long time since I did anything along these lines, but one thing that intrigues me is that is all photons are travelling at the same speed (exactly), what determines their energy? I understand that atomic level reactions to the cause of this energy, ie, a gamma ray photon gets emitted when, for example, a high energy proton collides with either another proton or an atomic nucleus, but if the photon leaves the nucleus at the exact same speed as the visible light photon also produced, then what is the cause of the energy difference...is it that they do not leave at the exact same speed, perhaps billionths of a meter per second difference, or do they in fact have different masses that have so far remained undetermined due to their low level...or will we discover something even more fundamental out about sub-atomic particles that has so far remained elusive...