# Light and Gravity

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#### dryson

##### Guest
Here is a question to theorize about. We know that light can be bent around a planet by the planets gravity. What if we were able to introduce gravity inside of the light photon and bend the very particle components that make up the light photon? Would we be able to in essence split the light photon into more than one photon thus gaining maybe two to five times the number of energetic releases from one photon?

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#### Mee_n_Mac

##### Guest
dryson":tqrv3x4n said:
Here is a question to theorize about. We know that light can be bent around a planet by the planets gravity. What if we were able to introduce gravity inside of the light photon and bend the very particle components that make up the light photon? Would we be able to in essence split the light photon into more than one photon thus gaining maybe two to five times the number of energetic releases from one photon?
I thought a photon was an elementary particle, it has no internal components. Moreover when we do "split" photons (spontaneous parametric down-conversion) we get more photons, each of which is of a lesser energy. I'm not sure what you meant to imply (if anything) by your last sentence.

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#### MeteorWayne

##### Guest
Useless word salad. It has no meaning within the world of real physics.. but dyson doesn't live there.

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#### Gravity_Ray

##### Guest
Mee_n_Mac":25cytgln said:
I thought a photon was an elementary particle, it has no internal components.
This has always thrown me for a loop. For some reason my brain always hurts when I think that a photon is mass less. After all Energy = mass times the speed of light squared. Therefore how can there be energy without mass? But if there is mass how can light travel at the speed of light? Man I need another cup of coffee now.

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#### ramparts

##### Guest
Oh, dryson, how I missed you.

Gravity_Ray, E=mc^2 is an equation with only a limited applicability. The full equation looks something like:

E^2 = (mc^2)^2 + (pc)^2

Where p is the particle's momentum, which photons certainly have. This reduces for photons (which have no mass) to E=pc.

Einstein's famous E=mc^2, as you may be able to tell (if you remember your high school algebra!), is what that equation reduces to when p=0; that is, when an object is at rest. So mc^2 is a massive particle's rest energy, the energy it intrinsically has when it has no momentum.

E=mc^2 is also very much valid for moving non-relativistic particles - that is, particles moving at speeds much less than the speed of light, so they don't feel strong effects of Einstein's relativity. Photons, however, are pretty much by definition relativistic since they move at the speed of light. So E=mc^2 doesn't hold in the relativistic régime, and certainly not for photons!

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#### drwayne

##### Guest
Photons have their own energy equation,

E = hv = hc/l

where v = nu = frequency

h = Planck's constant

l = wavelength

My energy equation in the morning:

E = 0

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#### ramparts

##### Guest
Just to connect my and wayne's posts:

From the full version of E=mc^2 you get:
E=pc
As I said. Wayne put out an altogether more useful equation, which is:
E=hv
Put these together and you get the also-useful relation for the photon's momentum:
p=hv/c
Max Planck was able, right around 1900, to show that observed properties of radiation, the so-called blackbody, could only be explained if the energy (and in turn, momentum) of light was quantized - that is, came in discrete chunks. One of Einstein's three breakthroughs in 1905 - most would say the second-greatest of the three (behind special relativity), but nevertheless the one for which he received his Nobel prize - was that this could be explained if light itself came out in discrete chunks, thus giving birth to the notion of a photon, or light particle, as well as quantum mechanics.

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#### dryson

##### Guest
The photon is a particle yes, but it is also governed by it's wavelength. If the photon's wave vector could be somehow split in two where one new wavelength is formed from the initial wavelength by allowing one part of the wavelength to remains at it's constant rate of velocity of propogation and the other slowed down somehow then it would be possible to generate more photonic power from one single photon. Physic's is not a law set in stone but a formula in which too build upon and discuss what has already been discovered.

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#### ramparts

##### Guest
Dryson, I will say to you what I have said to you many, many times before:

Wha...?

What do you mean by split a photon's wave vector in two? How do you split a vector in two? How can one wave have two wavelengths? It seems that at that point you have yourself two particles. Why would half of a photon slow down.... and would the other half continue to propagate at c? And then there would be more "photonic power" (whatever on Earth that is). Physics isn't set in stone but that doesn't mean that you can throw out words and expect them to just make sense.

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