Origins/Foundations of Einstein's Relativity

C

camilus

the villain with x-ray glasses
Registered Senior Member
What was the main axiom which gave special/relativity its validity? Most people assume its just the simple fact that manifest all the apparent anomalies when traveling at the speed of light.

Does anyone know what the real postulate which Einstein used to imagine relativity? I just learned what it was, and it wasnt what I mentioned above
about the consequences of traveling close to the speed of light.

Any suggestions? :cool::D:)
 
Around about the turn of the 20th century people began to discover that measurements of the speed of light produced the same results no matter how fast the measuring device was moving. A few years later Michelson and Morley put it to the test. The postulate was that the speed of light was the same no matter the movement of the observer.

Lorentz produced the same equations earlier with the postulate: the final irreducible constituent of all physical reality is the electromagnetic field. But we forgot about Lorentz; too bad.
 
And the fact that c has to be constant in all reference frames leads to some amazing transformations that nobody would have believed before
 
Einstein used to imagine the speed of light quite frequently. One of the famous legacies is where Einstein used to imagine he was holding a mirror and moving at the speed of light. He was somewhat ''annoyed'' by the idea that he would not see his reflection, and thus proposed the notion that even at light speed, the speed of light remains relative.

Theoretically speaking, its also known that you can derive all the mathematical equations of relativity without this law.
 
gluon said:
and thus proposed the notion that even at light speed, the speed of light remains relative.
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The speed of light remains constant.

Theoretically speaking, its also known that you can derive all the mathematical equations of relativity without this law.
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I've never heard this. Do you have a reference?
 
camilus said:
What was the main axiom which gave special/relativity its validity? Most people assume its just the simple fact that manifest all the apparent anomalies when traveling at the speed of light.

Does anyone know what the real postulate which Einstein used to imagine relativity? I just learned what it was, and it wasnt what I mentioned above
about the consequences of traveling close to the speed of light.

Any suggestions? :cool::D:)
Click to expand...

You might check the Equivalence Principle, which says (loosely) that a uniformly accelerated observer is the same as a static observer in a gravitational field. You might ask DH, he seems to know more than a little about GR.
 
yes, light remains constant, excuse me. It's very early in the morning, and i've been awake all night.

I will look for the reference. A mathematician recently (some teacher i recall) said that the equations of relativity (or rather what it postulates in the long run) even if the speed of light was not constant in all frames.

I will look for it... He even did the math and everything.
 
I can't find it. My memory serves me well though on the topic, and was posted in this forum some weeks back...

Perhaps someone could elaborate on this.
 
now i have a serious question

if light is slowed what does that mean to relativity?

for example: is the photon now of less energy?

Slowing light may be easier than you think. Physicists who recently slowed a light signal to a glacial 17 m/s using the exotic state of matter known as a Bose-Einstein condensate (BEC) received tremendous attention, but now a team demonstrates how to slow light on the cheap. They show in the 28 June PRL that an ordinary gas of heated rubidium atoms can slow light signals almost as well, to just 90 m/s--more than a million times less than the speed of light in air or vacuum. The new concept should make a wide range of advanced optics experiments more feasible and could also be useful for devices
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or what about in 2001

Researchers say they have slowed light to a dead stop, stored it and then released it as if it were an ordinary material particle.

The achievement is a landmark feat that, by reining in nature's swiftest and most ethereal form of energy for the first time, could help realize what are now theoretical concepts for vastly increasing the speed of computers and the security of communications.

Two independent teams of physicists have achieved the result, one led by Dr. Lene Vestergaard Hau of Harvard University and the Rowland Institute for Science in Cambridge, Mass., and the other by Dr. Ronald L. Walsworth and Dr. Mikhail D. Lukin of the Harvard-Smithsonian Center for Astrophysics, also in Cambridge.

Light normally moves through space at 186,000 miles a second. Ordinary transparent media like water, glass and crystal slow light slightly, an effect that causes the bending of light rays that allows lenses to focus images and prisms to produce spectra.

Using a distantly related but much more powerful effect, the Walsworth-Lukin team first slowed and then stopped the light in a medium that consisted of specially prepared containers of gas. In this medium, the light became fainter and fainter as it slowed and then stopped. By flashing a second light through the gas, the team could essentially revive the original beam
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how is this possible if the photon is not 'held upon mass'......?
 
I must admit, i have seen that second report, and i find it contradictory to every known law i thought i knew about the photon.
 
Maybe it is that light moving through a medium does so by repeatedly being absorbed and emitted. Feynman described the process as doing a little dance through the substance.
 
To BentheMan:

gluon: Theoretically speaking, its also known that you can derive all the mathematical equations of relativity without this law. ”

BentheMan: I've never heard this. Do you have a reference?

cinci: I'm not sure because it's hard to find a lot of Lorentz's work, but I don't think he postulated constancy of the speed of light for all observers.
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To camilus: have you read Eisntein's 1905 paper? It is posted at this site: (Sorry, I haven't made enough posts to be permitted to post a link)

You'll have to type it into your computer after the usual stuff
phys.lsu.edu/mog/100/elecmovbodeng.pdf
 
gluon said:
I must admit, i have seen that second report, and i find it contradictory to every known law i thought i knew about the photon.
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but it is experimental evidence

yes, light remains constant, excuse me. It's very early in the morning, and i've been awake all night
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so what is the view; are the mathematics is correct, is the evidence just rediculous?

then if the evidence is reproducible, what happens to the energy of the 'photon' ..........( held upon mass.)

Seems that when they re-release the 'color' the same energy is retained as when the photon enters the medium (rubidium).....

what are the physics behind this; that can allow energy (light) to be held upon mass and retain its state?
 
I know that if you have a reasonably thick medium, light could slow down to zero speed. I wouldn't know have to get the factors mathematically, but it would be many times greater than the density of spacetime right now. So i don't know if it's a matter of reaching a specific density, is it, to balance out the speed of the photon to stand like a physical particle?
 
I believe the correct answer is that Einstein began with the assumption that Maxwell's equations have to be valid in all reference frames, or in other words the equations have to be relativistically invariant. In Newtonian space and time, the equations only work if you pick a reference frame and do all the calculations from within this reference frame. Charge and current distributions, space and time, and electric and magnetic fields all have to be adjusted in order to obtain a consistent result when converting the results from one reference frame to the other. If you assume Newtonian physics and try to do the same electromagnetic calculations in two different reference frames, you'll get contradictory results.

Bishadi said:
now i have a serious question

if light is slowed what does that mean to relativity?

for example: is the photon now of less energy?
Click to expand...

Light is never slowed in relativity, because as far as we know, the numerical constants of Maxwell's equations are unchanging with time, and the speed of light depends directly on these constants. Light can be slowed down when it's travelling through a material such as water, but that's because the light is being continuously absorbed and re-emitted inside the material. Any time light is actually travelling from one point to another without interruption, it travels at the fixed value we call "the speed of light". When you lower the energy of a beam of light, it experiences a drop in amplitude (i.e. number of photons in the beam) and/or a drop in frequency (each individual photon's energy is directly proportional to its frequency).
 
Bishadi said:
now i have a serious question

if light is slowed what does that mean to relativity?

for example: is the photon now of less energy?




or what about in 2001



how is this possible if the photon is not 'held upon mass'......?
Click to expand...

None of these experiments actually "slow" a photon. They "delay" the propagation of light through the medium. Along the way the photons are absorbed by atoms of the medium, and their energy transformed into excitation energy of the atom. Then, after a delay, this energy is re-emitted as a photon again, The photons themselves still travel at c in between the atoms.

When they "stop" light, they have just developed a medium that can absorb and "store" the light's energy, until such time as they trigger it to emit it as light again.
 
CptBork said:
I believe the correct answer is that Einstein began with the assumption that Maxwell's equations have to be valid in all reference frames, or in other words the equations have to be relativistically invariant. In Newtonian space and time, the equations only work if you pick a reference frame and do all the calculations from within this reference frame. Charge and current distributions, space and time, and electric and magnetic fields all have to be adjusted in order to obtain a consistent result when converting the results from one reference frame to the other. If you assume Newtonian physics and try to do the same electromagnetic calculations in two different reference frames, you'll get contradictory results.
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a lucid understanding of the assumption (but you forgot that maxwell used a 'fluid' sense; an aether (for the pressure/motion)

or folks can read over Maxwells paper themselves http://vacuum-physics.com/Maxwell/maxwell_oplf.pdf

Light is never slowed in relativity, because as far as we know, the numerical constants of Maxwell's equations are unchanging with time, and the speed of light depends directly on these constants.
Light can be slowed down when it's travelling through a material such as water, but that's because the light is being continuously absorbed and re-emitted inside the material. Any time light is actually travelling from one point to another without interruption, it travels at the fixed value we call "the speed of light". When you lower the energy of a beam of light, it experiences a drop in amplitude (i.e. number of photons in the beam) and/or a drop in frequency (each individual photon's energy is directly proportional to its frequency).
Click to expand...

seems you just defined the 'red shift' of astronomy

hence a distance or momentum of objects would have no consequence but that the material/energy between the line of sight (maxwell again) would be the cause of the changes to the light between points

what does that do for Hubble?

a conundrum seems to have surfaced

Is the speed constant in all reference frames or does the mass/energy cause the changes l/f within 'line of sight'?


That would mean, perhaps it was not space bending, but energy 'fields' that allowed the stars behind the sun to be seen during the eclipse. (per maxwell of course but not Eddington/Einstein 1919)

all i am asking is, since you are well versed and capable of articulating the history and knowledge, are there valid issues between the renditions being suggested?

and then, as you suggest, it must be observed that a photon can be held upon mass........ (you share feynman's rendition, which i liken to bohrs 'quantum jump')

in both, the energy of the exchange between mass can be viewed as the 'photon' itself, and thus has nothing to do with the speed but the f of the state (em/photon)...

(as l (amplitude) is only required when 2 combine, agreed)
 
Janus58 said:
None of these experiments actually "slow" a photon. They "delay" the propagation of light through the medium. Along the way the photons are absorbed by atoms of the medium, and their energy transformed into excitation energy of the atom.
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could the wavelength show itself as a resonance?

perhaps causing motion/momentum?


Then, after a delay, this energy is re-emitted as a photon again, The photons themselves still travel at c in between the atoms.
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if that be so, then if i add up all the exchanges (between the atoms), there should be no 'delay' but we find that cannot be, as there is a 'slowing' occuring.

Apparently when that photon becomes a part of the mass, the mass absorbs the impact (lamb shift) so to speak, which shares that state with the rest within the abutting environment. Almost like a shock wave which spreads the momentum over time/space/mass... causing the 'slowing' to the unit photon

When they "stop" light, they have just developed a medium that can absorb and "store" the light's energy, until such time as they trigger it to emit it as light again.
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works for me

that could perhaps offer an kind of esoteric logic that;
the energy of mass could simply be the light upon mass (electromagnetism/photon)

interesting concept :D
 
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