# Speed of light constant

The treadmills are synchronized at rest one is then put on board the ship ( I am using these instead of clocks as I think it may be easier to visualize) Yhe diagram being used is linked to in another earlier post.
I thought E=hf was the total energy of a wave. Are you saying that waves are made of smaller components. what happens to the rest of the wave once it has lost part of its energy as a photon.
I have tried to do some reading. Of course if the pulse of light was regular then speed relative to the number of pulses counted would remain constant but the distance between them would change according to motion of the emitter, this I think is the doppler effect.
You mention a change in energy which of course leads to the question if energy is conserved how can 2 observers measure different energy levels for the same thing.
Problem with books is cost. If available at library then fine otherwise cant justify expense. Have been trying youtube but without being able to ask questions is limited use.
Another thing books can seem to be contradictory. For example Wonders of the universe by Proff Brian Cox (also TV series). Page 27 Star HE 1523-0901 est age 13.2 billion yrs in our galaxy 2nd generation star, P 55 the most distant galaxy over 13 billion light years away as it was 600,000 yrs after BB, P 71 on CMB by the time the universe was 1/5 its current size just over a bill yrs after BB these regions would have been twice as dense as thier surroundings. By this time the matter in these regions was dense and cool enough to begin collapsing under own gravity. The numbers dont match 1 bill yrs after the BB is 12.75 b ys ago we have galaxies and 2nd generation stars older than this.
Books tell you things but cant answer questions.

#### Drakkith

Staff Emeritus
2018 Award
The treadmills are synchronized at rest one is then put on board the ship ( I am using these instead of clocks as I think it may be easier to visualize) Yhe diagram being used is linked to in another earlier post.
Ah ok.

I thought E=hf was the total energy of a wave. Are you saying that waves are made of smaller components. what happens to the rest of the wave once it has lost part of its energy as a photon.
No, I'm saying the wave INTERACTS through photons, not that it is MADE of photons. But that is a Quantum Physics question, not a Relativity question. If you want to know more I suggest making a post in the Quantum Physics forum. Once some of the energy is transmitted to something else, the wave simply has less energy.

You mention a change in energy which of course leads to the question if energy is conserved how can 2 observers measure different energy levels for the same thing.
The same way you can measure different energy for any moving object. Think about you in your car. You are moving with it so it has no energy, but an observer at rest with respect to the ground will measure you with a LOT of kinetic energy. I know the energy is conserved, but I don't know how to explain it properly, sorry.

#### harrylin

It just seems to get more complicated.
[..] the MM experiment seems to assume a moving aether, would it make any difference if it was a stationary field just producing resistance so as to cause a wave to form, as waves seem to form due to the resistance of the medium or am I way out here.
(that was wrong, as I next explained; see posts #40 and #45.)
[..]I have tried to do some reading. Of course if the pulse of light was regular then speed relative to the number of pulses counted would remain constant but the distance between them would change according to motion of the emitter, this I think is the doppler effect. [..]
Books tell you things but cant answer questions.
I'm afraid that no book reading can compensate for not doing your "homework". I don't know anyone who managed to understand physics without doing calculation exercises, or by jumping over stuff that they hardly understood, to stuff that they can't understand as a result. The only way to understand correct answers on such questions is to work yourself up from layman to informed person.

Did you try to work out the MMX prediction by doing the calculations by yourself that are explained on that web course and in Wikipedia? You don't need much more than Pythagoras for that.

The next step would be to get the meaning of length contraction and time dilation, and how they are calculated (if you don't know yet). And then you can hopefully follow my explanation to dubiousraves in post #50.

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Unfortunately most if not all relevant calculations use symbols the meaning of which you have to try to find out. I can follow numerical calculations but not those with symbols that mean nothing to me and the explanation of those is not always clear.
The only way of understanding for me is to picture what is happening. I need to understand where the maths comes from in order to picture what is going on.

#### harrylin

Unfortunately most if not all relevant calculations use symbols the meaning of which you have to try to find out. I can follow numerical calculations but not those with symbols that mean nothing to me and the explanation of those is not always clear.
The only way of understanding for me is to picture what is happening. I need to understand where the maths comes from in order to picture what is going on.
Fair enough; however it is much more economical and useful if you ask those details, than us having to reproduce full textbooks plus additional explanations in conversation style! :yuck:

And now that we are at it, http://galileoandeinstein.physics.virginia.edu/lectures/michelson.html gives nice examples without needing to know the definition of any symbols:

- the swimmer illustration (did you check the calculation?)

- a full animation of MMX :tongue2:
(did you check it out? notice that there is a factor 10 difference in scaling between the two speeds)

- next, he gives equations but immediately introduces the meaning of all symbols. If you did the swimmer example calculations for yourself, then you will recognise these equations as doing the same thing. Of which symbols is the meaning not clear?

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#### ghwellsjr

Gold Member
Unfortunately most if not all relevant calculations use symbols the meaning of which you have to try to find out. I can follow numerical calculations but not those with symbols that mean nothing to me and the explanation of those is not always clear.
The only way of understanding for me is to picture what is happening. I need to understand where the maths comes from in order to picture what is going on.
I made a series of animations with explanations that graphically provide a way for you to understand how the Michelson-Morley Experiment led to Einstein's theory of Special Relativity. There's no math, no equations, no calculations, no symbols--just animated pictures. Please study this thread and see if it helps you:

Have been thinking, probably not wise, I hope I dont go outside the boundaries allowed on this forum.
Have been looking at Georges animations and thinking about how waves work and some of the other links. I dont see how the MM experiment could possible detect an aether if it exists.
While energy passes through a medium as a wave the medium itself just moves up and down so is in effect stationary. The speed of the wave appears to depend at least to some extent on the density of the medium, the denser the faster the wave.
I would be interested to know how the medium however affects the amplitude, I am unable to find any information on this but feel it important as the shorter the wave the faster the up and down in the medium but I cant picture how or what affects the amplitude and how, I understand that all light waves have the same amplitude.
I am assuming that waves lose energy to the medium they pass through and so gradually get longer untill they dissipate altogether.

So the potential properties of any aether, very dense, as the speed of light is constant then as near motionless as is possible, possibly being zero, which would mean in effect all directions would be forward. As the light that reaches us from the stars is still in the visible range energy dissipation to the aether would be very slight.
My conclusion would be that the only way to detect it would be a known wavelength of light measured over a huge distance and see if the wavelength changed (lengthened)which could be due to energy dissipation to the aether if it existed.

I repeat I would be interest to know about amplitude if anyone can help, simple explainations would be appreciated if possible.

#### harrylin

Have been thinking, probably not wise, I hope I dont go outside the boundaries allowed on this forum.
Just as you feared: personal ether model speculations are not permitted on this forum. See the Rules, linked at the top of this page.
Have been looking at Georges animations and thinking about how waves work and some of the other links. I dont see how the MM experiment could possible detect an aether if it exists. [..]
That is correct, the kind of velocity effect that Michelson hoped to detect could not possibly be detected; however that is for reasons that seem to escape you (just as it escaped him at the time, and astonishingly, Fowler still today; I suppose that you have read the section that I asked you in post #40 to skip). See post #17 with a link to a discussion on that topic.

Of course, we can help you to calculate here how an MMX measurement with a "moving" interferometer can have no effect, according to a "stationary" frame's calculations.

BTW, did you try the swimmer calculations for yourself? Do you understand the equations now, or do we need to better explain some symbols?

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#### Drakkith

Staff Emeritus
2018 Award

1. Light isn't a wave in a physical medium that moves up and down. In fact, many waves are not like this at all. For example sound waves are usually longitudinal waves, meaning they oscillate in the direction of motion and not transverse like EM waves are.

2. If the medium is moving, or if you are moving with respect to the medium, waves will have different speeds since they have to travel in the medium. For example, if you are traveling faster than the speed of sound in an aircraft, you will NEVER hear a sound wave that is emitted behind you because it will never reach you!

3. EM waves do not have the same amplitude.

4. Waves do not lose energy in the sense that the wavelength changes. Instead as the wave propagates the wavefront expands. The total power must stay the same in the wavefront, so as it expands less and less energy is available per area of space. Hence we get the inverse square law, which states that the power or intensity of the wave decreases to 1/4 when you double the distance from the source. Triple the distance and it's 1/9. Etc. The final effect this has is that you have fewer photons per second hitting a surface as you move it further away from the source, not that the wavelength changes.

#### ghwellsjr

Gold Member
Have been thinking, probably not wise, I hope I dont go outside the boundaries allowed on this forum.
Have been looking at Georges animations and thinking about how waves work and some of the other links. I dont see how the MM experiment could possible detect an aether if it exists.
While energy passes through a medium as a wave the medium itself just moves up and down so is in effect stationary. The speed of the wave appears to depend at least to some extent on the density of the medium, the denser the faster the wave.
I would be interested to know how the medium however affects the amplitude, I am unable to find any information on this but feel it important as the shorter the wave the faster the up and down in the medium but I cant picture how or what affects the amplitude and how, I understand that all light waves have the same amplitude.
I am assuming that waves lose energy to the medium they pass through and so gradually get longer untill they dissipate altogether.

So the potential properties of any aether, very dense, as the speed of light is constant then as near motionless as is possible, possibly being zero, which would mean in effect all directions would be forward. As the light that reaches us from the stars is still in the visible range energy dissipation to the aether would be very slight.
My conclusion would be that the only way to detect it would be a known wavelength of light measured over a huge distance and see if the wavelength changed (lengthened)which could be due to energy dissipation to the aether if it existed.

I repeat I would be interest to know about amplitude if anyone can help, simple explainations would be appreciated if possible.
I'm sorry that my animations did not fit your request for an easy explanation. It appears that they were nothing more than a launching pad for you to go off in many different directions having nothing to do with with the content of my posts or the purpose of this forum which is to help people learn relativity. It appears that most of your other responses on this thread fall into the same category. You don't appear motivated to learn anything about relativity but only to diverge off the topic of your own thread.

Sorry George unfortunately that the way my mind works. It is most annoying at times especially when reading books, you read something which sends the mind off on a what if tangent and you have to read 1/2 page over. I am not interested in the fact 2+2=4, I want to know why that is so. Problem is Im on my own, doesnt tend to happen in conversation. I need to build a picture of what is going on which means understanding what is right and discarding what is wrong, however how do you decide between right and wrong, all arguments have 2 sides I am probably one of the few people that can see the pros and cons of both sides have an argument with myself and still leave things unresolved due to lack of information. I am in this position partly because you read one thing that is presented as true which you later find to be inaccurate. I get the impression from the rules that einstein would have been banned from this site as a crackpot which limits disscussions severely, if theories like aether have been discarded in the past I need to know why to check nothing was overlooked, we have dark matter and dark energy to find an explaination for.

As far as the swimmer goes you dont need to work the maths out to see what is being said.
Post 59 point 1 tells me that light waves are not what I thought, it does not really tell me what they are so that sends me on a speculative journey
Point 2 is obvious so requires no further thought
Point 3 is no help at all.
Point 4 takes us back to waves and photons which I thought you said were unrelated. I will have to check earlier post.

#### Drakkith

Staff Emeritus
2018 Award
Please, don't bring Einstein into this. You have no idea what you are talking about.

You need to learn basic physics before you need to know why the aether idea was discarded. The reason why is because you don't understand enough to know why the aether idea was discarded when you are told why!

I need to build a picture of what is going on which means understanding what is right and discarding what is wrong, however how do you decide between right and wrong, all arguments have 2 sides I am probably one of the few people that can see the pros and cons of both sides have an argument with myself and still leave things unresolved due to lack of information.
Pick up a physics book and read it. That will immediately tell you what is right.

#### harrylin

[..] if theories like aether have been discarded in the past I need to know why to check nothing was overlooked, we have dark matter and dark energy to find an explaination for.
Ether is not a theory but a concept, a class of models, which has been discarded by most people because it is not needed for the calculations. If you would like to invent your own model (for yourself, not on this forum), then you need to know how the calculations work to which your model must fit. Or if you want to know how Lorentz's model worked in the context of special relativity, you can ask here (see again the Rules: "discussion in a purely historical context").
As far as the swimmer goes you dont need to work the maths out to see what is being said.
The equations that you did not understand are the same for the swimmers as for MMX, and with further explanation these calculations and related explanations will get more complex - too complex for most people to correctly understand the physics merely from reading "what is being said". Without doing the math, most people cannot get much further than the level of understanding of the ancient Greek philosophers.

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