New Theory?

[kotake]

When photons are absorbed by glass molecules, do they decelerate? Do they stop insantly? When Photons are emitted do they Start at velocity C or do they accelerate from 0m/sec to C?

I think that the energy that the photons were carrying gets absorbed into the glass atoms, so for a moment there is no photon, but an excited atom. Then the energy gets emitted in the form of a new photon. So the delay is caused by the brief disappearance of the photons.

[Lowemack]

I believe it was the Michelson-Morley experiment that seemed to show that the speed of light was constant, and this experiment was performed a few years before Lorentz or Einstein introduced the famous theory of SR.

 

What I meant was, was it because light speed is constant that the Michelson-Morley experiment resulted as it did, or just because of the way reletivistic velocity additions are calculated.

 

What if for example an particle was travelling towards a space ship laboratory at .9999999999999999999999999999C. What speeds would we measure for the particle when for example the lab was (a) travelling towards the particle at 30,000m/s and (b) away from the particle at 30,000m/s.

 

From what I know about relativity, both answers would be very close to C, not C + 30,000m/s and C - 30,000m/s

 

Michelson-Morley would have been expecting Newtonian velocity additions.

 

So is light speed a constant or is it so close to C that we can't measure any relative changes in its velocity accurately enough.

[[Tycho?]]

All experiments to measure the speed of light came to the same value' date=' C. So Einstien used this 'fact' to make his Special Theory of Relativity. This then gave us a new way of calculating relative velocities.

 

If you use the formulae to calculate the relative velocity of a light beam when you are travelling towards it at 0.5C, the answer will be still be C, which is what we actually measure.

 

Obvously the formulaes are correct, but what if the speed of light is always measured to be C, because of the formulaes.

 

I believe that C is the maximum possible Relative velocity for everything in the universe INCLUDING light.

 

It is slightly different from saying the "speed of light is a constant" and everything else in the universe has a maximum relative velocity.

 

If an object was travelling towards you at C and you accelerated towards it at 0.5C you would still measure its velocity to be C, just like we do with a light beam.

 

I think that light can reach C (or very close) because it has no mass.

 

Also what happens to light when it is absorbed? Does it stop, slow down? This isn't constant velocity.

 

P.S. I know an object can't travell at C, but hyperthetically.[/quote']

 

If c was not a constant then relativity would not work.

[Lowemack]

'']If c was not a constant then relativity would not work.

 

Why Not? (Not doubting, just interested)

[kotake]

If c was not a constant then relativity would not work.

Why Not? (Not doubting' date=' just interested)[/quote']

As far as I know, all experiments give the results that light travels at c, but I don't know how many decimals they have. I also assume that experiments with addition of relativistic velocities give positive results, something that supports special relativity.

 

I think it would depend on the manner of c not being a constant for us to determine whether relativity would work. For instance, if c were changing over the period of time past big bang, we could use relativistic calculations within a given period. c would still be constant, in a way, but it would continually change over time.

 

I cannot see any other way in which c would not be a constant.

[Janus]

All experiments to measure the speed of light came to the same value' date=' C. So Einstien used this 'fact' to make his Special Theory of Relativity. This then gave us a new way of calculating relative velocities.

 

[/quote']

 

There's more to it than that. There are strong theorectical reasons for the invarience of the speed of light in a vacuum.

 

The Maxwell equations, which describe the behavior of all electromagnetic radiation shows that the speed of light in a vaccuum depends on two properties of the vacuum, its permittivity and its permeability. These two properties are constant regardless of whether you are moving or not. (If they weren't, you'd end up violating laws of conservation for one thing.)

 

At first it was thought that this speed was with respect to an aether, but when experiments failed to detect such, Einstein postulated that it was with respect to what ever frame it was measured from.

 

Also, the Maxwell equations tell us something else, if the speed of light were not invarient, then the equations do not transform between moving frames properly. The upshot being that an electromagnetic wave in one frame does not exist as such in a frame moving with respect to the first. A practical result of this is that you wouldn't be able to pick up a radio station in your car if you were moving with respect to the broadcast station.

 

Since it is obvious that we can listen to the radio while driving, it stands to reason that the speed of light is invarient.

[Lowemack]

There's more to it than that. There are strong theorectical reasons for the invarience of the speed of light in a vacuum.

 

The Maxwell equations' date=' which describe the behavior of all electromagnetic radiation shows that the speed of light in a vaccuum depends on two properties of the vacuum, its permittivity and its permeability. These two properties are constant regardless of whether you are moving or not. (If they weren't, you'd end up violating laws of conservation for one thing.)

 

At first it was thought that this speed was with respect to an aether, but when experiments failed to detect such, Einstein postulated that it was with respect to what ever frame it was measured from.

 

Also, the Maxwell equations tell us something else, if the speed of light were not invarient, then the equations do not transform between moving frames properly. The upshot being that an electromagnetic wave in one frame does not exist as such in a frame moving with respect to the first. A practical result of this is that you wouldn't be able to pick up a radio station in your car if you were moving with respect to the broadcast station.

 

Since it is obvious that we can listen to the radio while driving, it stands to reason that the speed of light is invarient.[/quote']

 

But were the Maxwell equations based on relativistic velocity addition calculations or Newtonian?

[swansont]

But were the Maxwell equations based on relativistic velocity addition calculations or Newtonian?

 

Maxwell's equations were well in place before Einstein came up with relativity. There is no velocity addition explicitly in them - it's a set of equations describing the electric and magnetic fields. It was noticed, after the fact, that the speed of light was the wave speed in the equations, dependent on the permittivity and permeability.

[J.C.MacSwell]

I think that the energy that the photons were carrying gets absorbed into the glass atoms, so for a moment there is no photon, but an excited atom. Then the energy gets emitted in the form of a new photon. So the delay is caused by the brief disappearance of the photons.

 

I had always pictured it as a longer route. Like slalom skiing around atoms, still at c but effectively longer. Your view sounds more consistent with QED though.

[J.C.MacSwell]

There's more to it than that. There are strong theorectical reasons for the invarience of the speed of light in a vacuum.

 

The Maxwell equations' date=' which describe the behavior of all electromagnetic radiation shows that the speed of light in a vaccuum depends on two properties of the vacuum, its permittivity and its permeability. These two properties are constant regardless of whether you are moving or not. (If they weren't, you'd end up violating laws of conservation for one thing.)

 

At first it was thought that this speed was with respect to an aether, but when experiments failed to detect such, Einstein postulated that it was with respect to what ever frame it was measured from.

 

Also, the Maxwell equations tell us something else, if the speed of light were not invarient, then the equations do not transform between moving frames properly. The upshot being that an electromagnetic wave in one frame does not exist as such in a frame moving with respect to the first. A practical result of this is that you wouldn't be able to pick up a radio station in your car if you were moving with respect to the broadcast station.

 

Since it is obvious that we can listen to the radio while driving, it stands to reason that the speed of light is invarient.[/quote']

 

Invariant in rest frames.

 

I like your radio/driving reference. I've used "still see stuff after you start moving" kind of thing and noone knows what I'm talking about.

[kotake]

I think that the energy that the photons were carrying gets absorbed into the glass atoms' date=' so for a moment there is no photon, but an excited atom. Then the energy gets emitted in the form of a new photon. So the delay is caused by the brief disappearance of the photons.[/quote'']I had always pictured it as a longer route. Like slalom skiing around atoms, still at c but effectively longer. Your view sounds more consistent with QED though.

Maybe, but perhaps the brief disappearance is so brief that it actually happens in no time, ergo, causes no delay. So the explanation might be a different one.

[Lowemack]

Since it is obvious that we can listen to the radio while driving' date=' it stands to reason that the speed of light is invarient.[/quote']

 

We can hear sounds when travelling (pitch changes), also see we see moving objects with red shift.

 

Also driving a car is hardly close to relativistic speeds.

[Janus]

We can hear sounds when travelling (pitch changes)' date=' also see we see moving objects with red shift.

 

Also driving a car is hardly close to relativistic speeds.[/quote']

 

1. The speed of sound is not invarient for all inertial frames, so any comparison between light and sound in this matter is useless.

 

2. We are not talking about a change of frequency of the electromagnetic wave between relatively moving frames, we are talking about the nonexistance of any type of electromagnetic wave in one of the frames. An electromagnetic wave in one of the frames would not exist as any electromagnetic wave of any frequency in the other.

 

3. I never said that we can't see moving objects, but that if light were not invarient for relatively moving frames, we wouldn't be able to. We can, so it is.

 

4. It wouldn't take relativistic speed for this effect to show up, as any difference in velocity would cause the electromagnetic wave of the source to disappear entirely as an electromagnetic wave for the receiver.

[fuhrerkeebs]

What I meant was, was it because light speed is constant that the Michelson-Morley experiment resulted as it did, or just because of the way reletivistic velocity additions are calculated.

 

It's because the speed of light is constant. The Michelson-Morley experiment was done before we knew how to add velocities relativistically.

[Lowemack]

It's because the speed of light is constant. The Michelson-Morley experiment was done before we knew how to add velocities relativistically.

 

Light speed = 300,000m/sec

Earth speed around sun 30m/sec

 

So Michelson-Morley would have been expecting to see speeds of 300,030m/sec in summer and 299,970m/sec in winter. This did not happen and as we know because how relative velocities "happen" because of relativity. But does this mean that light speed is constant, or it is just very close to C and we cant measure the velocity of it accurately enough to detect our motion.

 

For example if we repeated the Michelson-Morley experiment, but tried to measure the speed of some imaginary particles travelling at 299,999.9999999999999999999999999999m/sec, from a distant star.

 

Using relative velocity additions, what speeds would we expect to measure in winter (travelling towards the source @30m/sec) and summer(Travelling away from the source @ 30m/sec)? Would it appear constant just like light speed?

[Lowemack]

Can anybody do the maths for this problem?

 

I believe that the answer will show that we could not measure the speed, of the imaginary particles accurately enough, to show a difference in the relative velocity of the particles, when measured in winter and again, in summer.

 

This is what I believe happens when we measure light speed!

[swansont]

M-M used an interferometer to measure phase shifts, not speeds.

[Lowemack]

M-M used an interferometer to measure phase shifts, not speeds.

Thought they used a rotating mirror?

[swansont]

A rotating mirror is a way to measure the pseed of light, but I don't think anyone has used that to try and measure the small shifts you want to try and do - you're right, you'll never see that small of a change.

 

The Michelson interferometer experiment of Michelson and Morley