From the ceiling of a passenger car, light ray is emitted down. When the moving car is filled with water, diagonal of light ray may be more gentle to an observer who stands on the ground. And the diagonal (depends only on c/n and v) may be simple appearance. It may be the same about air or vacuum too (Galilean transformations may stand up about all).
From the ceiling of passenger car, light ray is emitted down somewhat to the right. One passenger car is moving to the right, another passenger car is moving to the left at the same speed. To an observer who stands on the ground, the length of two light rays is not the same.
http://www.geocities.co.jp/Technopolis/2561/eng.html
I'd love to see you fill a passenger car with water. The water, of course, slows the light and so refracts it. Where's the problem here?
Didn't they do that (amusingly of course) on Top Gear?Originally Posted by Mulder
On topic though.
Last edited by Mongrel; 22nd April 2009 at 09:28 AM. Reason: Cleaning up tags
Allow me to repeat to quote, please.
Einstein's theory stands up only on vertical light ray (in a passenger car) ? Einstein's theory does not stand up on diagonal light ray (in a passenger car) ?
From the ceiling of a passenger car, a few light rays are emitted to lower right. The angle (of these) is different (one is vertical). How does Einstein's theory explain this (passenger car is moving to the left) ?
Sorry, if it's invalid.
The whole point of relativity is that there is no unique frame of reference. So the concept of 'diagonal rays' is meaningless in relativity.
The time light takes to arrive at any point depends on the distance travelled (which is rarely a straight line because time space is curved br gravity) and the medium through which it travels - water will both slow light down and change its direction.
So, are you saying there is an experiment that has demonstrated that light takes longer or shorter than it should to reach a point in space, given the distance travelled and the mediums traversed? If so, do you have a link?
To Mr.Mulder,
Thank you for relevant reply. As you say, "diagonal light ray" may be meaningless in relativity.
Sorry, i can't understand well the third part of your writing (i am weak in English). All my view and idea is shown in my web site (in English) below (Fortunately, it entered into Google's directory : Physics > Relativity > Alternative)
http://www.geocities.co.jp/Technopolis/2561/eng.html
I speak English reasonably well and I don't undrrstand this from your link:
"Two stars glitter on the right and on the left. Two mirrors are set at 45 degrees (like letter V), and are reflecting star light down. Speed of two reflected lights is always equal (maybe). Therefore, when two mirrors move together to the right or the left, wave length of two reflected lights is changed. In other words, wave density (number of waves that stay within an unit length of light path) of reflected light is changed by mirror's motion. But how about incident light ? Wave density is not changed by mirror's motion ! In short, wave density of reflected light and incident light is generally not the same. The theory of constancy of light speed may be impossible to explain this situation."
Light changes wavelength when it is reflected by a moving object (red or blue shift) to observers in most frames of reference. The strange bit here is 'wave density', which the writer defines as 'the number of waves that stay within an unit length of light path'. I don't see why anyone would want this concept - it serves to confuse matters.
The simpler way to look at it is that changing wavelength also changes frequency but not speed. In fact, speed = frequency x wavelength. What the wavelength of the photons of light is makes no difference to its speed. Nor does it matter how many times the wave goes up and down in any particular distance or time.
So when the light is reflected, its wavelength is changed but not its speed.
Relativity will be replaced one day by a better theory but only when there is evidence that it is wrong. If the writer of the article can show that reflection changes light speed as well as wavelength then good luck to them!
Last edited by Mulder; 29th April 2009 at 03:46 PM.
To Mr.Mulder,
This time, i may understand all of your writings. But allow me to limit my reply on two points.
You write, "when the light is reflected, its wavelength is changed but not its speed". i write, "when the light is reflected, incident light's wavelength is not changed but its speed". Look at not reflected light but incident light.
The word "wave number" is in encyclopedia of physics. It's inverse number of wavelength. The concept of this word may be fatal to relativity (the word "extinction" may be also).
The incident light is not affected by reflection (how could it be?). The reflected light has BOTH wavelength and frequency changed but NOT speed!
Using wave number makes a very simple thing look complicated. As you say, 'wave number' is the inverse of wavelength. Why use the inverse?The word "wave number" is in encyclopedia of physics. It's inverse number of wavelength. The concept of this word may be fatal to relativity (the word "extinction" may be also).
But if you want to use wave number, here it is:
Reflection changes wave number AND frequency (and therefore inverse of frequency) but not speed. The incident light is not changed AT ALL.
So the wave equation becomes (wave number) times (inverse of frequency) equals (inverse of light speed)
Wave number is not fatal to relativity, it is fatal to the simple understanding of an easy concept. Science is easier if you simplify things. Making them more complicated just makes it hard for no reason.
To Mr.Mulder,
About incident light : Image rail road and look at ahead of train (moving forward). Wavelength (sleepers) is unchangeable. Frequency and speed both are changeable (When incident light hits a moving (at changing speed) black body, it has changeable frequency also).
About the latter part : i don't agree to you. In addition, the paragraph "Reflection changes wave number AND frequency" is wrong (terribly). Yes, wave number of incident light and reflected light (in other word, before and after reflection) is not the same (reflection changes). But frequency of incident light and reflected light is the same (reflection doesn't change). Look at not light source but incident light. About further more, if you want, see the first part of my web-site.
In your analogy, you are talking about a object moving directly towards the source of the incident light. Therefore the light, in this example, is being reflected directly back towards its source. However, the case we were talking about above was starlight at 45 degrees! Maybe that is why there is confusion.
In the example you give here, you use railway sleepers as an analogy for light waves. Obviously, the sleepers are always the same distance apart physically. However, what we are concerned with is how the APPEAR to the train driver. They will arrive more quickly, as the train moves, so their APPARENT frequency will increase (ie. more sleepers will pass by per second as speed increases). However, they will also LOOK closer together, eventually blurring together at high speed, ie. their APPARENT wavelength will shorten too. This is the Doppler Effect.
If the train is approaching a source of sound directly ahead, which is a source of real waves (not just an analogy) of constant wavelength and frequency, its frequency will sound higher than if the train was stationery. This is, again, the Doppler Effect which applies as much to classical physics as relativity. Sound is a much better analogy here as railway sleepers don't really behave like waves.
I think you misunderstand. I said the incident light was NOT changed by reflection - its wavelength and frequency stay the same. The reflected light has both its wavelength AND frequency changed according to the wave equation, so that the speed is the same as in the incident light. If you think this is wrong, please explain why.About the latter part : i don't agree to you. In addition, the paragraph "Reflection changes wave number AND frequency" is wrong (terribly). Yes, wave number of incident light and reflected light (in other word, before and after reflection) is not the same (reflection changes). But frequency of incident light and reflected light is the same (reflection doesn't change). Look at not light source but incident light. About further more, if you want, see the first part of my web-site.
Last edited by Mulder; 7th May 2009 at 11:01 AM.
To Mr.Mulder,
About the first part : In this analogy (rail way and train), i am talking about incident light only. 45 degrees, 30 degrees or black body all has not any effect on incident light.
About the second part : In this analogy, rail way is moving (to train at high speed) and train is at a stand-still (or is moving at low speed). You write in the previous post, "The incident light is not changed AT ALL". Yes, wavelength is not changed AT ALL.
About the third part : Sorry, i may not understand your writing well (i'm not good in English). About Doppler effect, i write my view in my web-site. It's contrary to view of main stream. The view of main stream says, "By the motion of observer, wavelength of the incident light (for example, from an observer to a star or a galaxy) changes". Recall, wavelength, in other ward, is wave number !! Can you imagine change of wave number ? It's quite pseudo !!
About the last part : Sorry, i may not understand your writing well also. Any way, light speed isn't constant (to observer). In my web-site, 6 proofs are (all is simple at all).
Sorry, because of private affair, i must stop to post to this forum for the time being. Sorry, my English was bad.
Allow me to add, please.
Two light paths are coming from a star. When two observers move along each light path at different speed, wave length of the two light paths (lead to the star) differ (If Einstein's theory is right). Note : Light speed = frequency x wavelength
So you don't agree with Doppler Effect? Do you have any evidence that it is wrong.
You've got 6 'proofs' but do you have any evidence to support any of them? A theory is no good unless it is tested.About the last part : Sorry, i may not understand your writing well also. Any way, light speed isn't constant (to observer). In my web-site, 6 proofs are (all is simple at all).
I've quoted that formula several times but you appeared to be disputing it! If two observers are moving at different speeds relative to a star then, yes, they will see it at a different frequency AND wavelength. The speed of light, however, will appear the same to both.Two light paths are coming from a star. When two observers move along each light path at different speed, wave length of the two light paths (lead to the star) differ (If Einstein's theory is right). Note : Light speed = frequency x wavelength
All this sort of stuff has been looked at and tested years ago. Relativity has survived all its tests. It will be replaced by a better theory one day but not because of stuff like wave numbers!
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