Light and gravity

[j-man123]

...My question is if photons are "massless" then why do massive bodies perturb their natural course..?

 

Another question is if light does create a space time flux, which produces gravity....why does the moon still orbit earth in its Umbra?

[5614]

...My question is if photons are "massless" then why do massive bodies perturb their natural course..?

Because photos move in straight lines, wrong! It's because photos follow the shortest path possible, this is normally a straight line. However gravity warps or bends space-time, when this occurs it is quicker for a photon to follow the curvature of space-time then it is to cut across the curve. It's about the shortest path not straight lines.

[5614]

Another question is if light does create a space time flux, which produces gravity....why does the moon still orbit earth in its Umbra?

I don't understand why it wouldn't!

[j-man123]

hm....the shortest path possible..sounds like photons are pretty smart huh

 

So how does space time curvature do this?

[MetaFrizzics]

So how does space time curvature do this?

By acting as an 'aether'. Einstein cleverly removed the aether by calling it a manifold.

[5614]

Photons have to take the shortest route otherwise distance/time wouldnt equal c and that wouldnt be right (we're talking in a vacum for simplicity, it works elsewhere too, but it's a pointless few sentences more!)

 

Also going against the curvature of space-time is like going against gravity, now lets not have an anti-grav thread, but, well, as of yet scientists believe anti gravity is impossible, now go discuss it in another thread!

[danny8522003]

This shortest path is know as a Geodesic.

[ydoaPs]

By acting as an 'aether'. Einstein cleverly removed the aether by calling it a manifold.

you can't be serious

[bascule]

...photons are "massless"...

 

While photons have a rest mass of zero, they still have a relativistic mass... you can calculate this using Planck's constant and good old E=mc^2

[ydoaPs]

no. m is still zero in that equation(which you only posted part of).

[MetaFrizzics]

you can't be serious

It seems clear and accurate to say that Einstein began by postulating that the aether was unnecessary in Special Relativity, but found himself putting it back as the gravitational field in General Relativity, disappointing both himself and his mentor Mach.

[ydoaPs]

It seems clear and accurate to say that Einstein began by postulating that the aether was unnecessary in Special Relativity, but found himself putting it back as the gravitational field in General Relativity, disappointing both himself and his mentor Mach.

how is that clear? can i have some of what you are smoking?

[CPL.Luke]

metafrizzics GR works by altering the metric for space time. basicly all it is is defining the distance between to points to be longer or shorter depending on the mass around the space. its only the graphic representations of GR that make it look like an aether

[ydoaPs]

no. m is still zero in that equation(which you only posted part of).

the equation is [imath]E^2=(mc^2)^2+({\rho}c)^2[/imath]. you may say "wait, [imath]\rho=mv[/imath], so if m is 0, then energy is still zero." that is not the case. p=mv is the classical definition of momentum. [math]\rho=\frac{h}{\lambda}[/math]. also, you can use the equation E=hf.

[CPL.Luke]

yourdad I'm sorry to say but the equation for energy in special relativity that you posted only works for low speeds (not so well for velocities above 1/3 C)

 

its best to just use the tried and true L m C^2 where L is the lorentz factor

[swansont]

yourdad I'm sorry to say but the equation for energy in special relativity that you posted only works for low speeds (not so well for velocities above 1/3 C)

 

its best to just use the tried and true L m C^2 where L is the lorentz factor

 

No' date=' the equation he posted applies at all speeds. He said [i']not[/i] to use p = mv for momentum.

[ydoaPs]

yourdad I'm sorry to say but the equation for energy in special relativity that you posted only works for low speeds (not so well for velocities above 1/3 C)

 

its best to just use the tried and true L m C^2 where L is the lorentz factor

how so? there is no velocity term in it.

[MetaFrizzics]

how is that clear? can i have some of what you are smoking?

Silly rabbits:

The classical 'aether' concept suffered not from a lack of existance per se, but from a self-contradictory philosophical foundation and a lack of mathematical structures to adequately describe its observed behaviour. General Relativity solved both those problems, by adequately describing the behaviour of the aether via embedding Special Relativity in a geometric meta-manifold.

[ydoaPs]

Silly rabbits:

The classical 'aether' concept suffered not from a lack of existance per se' date=' but from a self-contradictory philosophical foundation and a lack of mathematical structures to adequately describe its observed behaviour. General Relativity solved both those problems, by adequately describing the behaviour of the aether via embedding Special Relativity in a geometric meta-manifold.[/quote']

what the hell?

[CPL.Luke]

No, the equation he posted applies at all speeds. He said not to use p = mv for momentum.

 

woopsy, I confused it with the equation E~mc^2 + 1/2mv^2

 

my bad

[GeminiinimeG]

dont photons have inertial mass or somehting like that(I forgot the exact word so dont laugh at me)

[5614]

They have a relativistic mass, they have no rest mass, it's all been said in this thread, read before you post, esp. in this kinda thread where it isn't very long.