# Talk:Speed of light/Archive 1

## Untitled

If I am at the Sun, and want to travel to the Earth at just a bit over the speed of light, what is to stop me? Light from the sun will get to the Earth in 8 min. So say that I leave when that ray of light leaves. I will get to the sun, say, in 7 min. So I am there i min ahead of the light. But light and time are not connected in any way. Time does not pass just because light is there. I will be at the Earth 7 min after I left the sun, which means that 7 min will have passed on Earth.

## Theoretical limitations on the speed of communications on Earth

The article currently gives "The speed of light is of relevance to communications. For example, given that the equatorial circumference of the Earth is 40,075 km and c, the theoretical shortest amount of time for a piece of information to travel half the globe is 0.067 seconds." Though not particularly well-versed in physics, I believe the circumference of the Earth shouldn't play into this calculation (see this section's heading title). I don't disagree with that the quotation apparently gives the theoretical shortest amount of time for light to travel across the Earth circumferentially. However, since AFAIK a piece of information could be encoded in any number of frequencies of electromagnetic radiation (and that radiation could penetrate the Earth), the actual shape of interest is a straight line between opposite poles of the planet, not the circumference between them. 07:04, 22 Dec 2004 (UTC). Light second gives "The mean diameter of the Earth is 0.0425 light seconds". I feel this is a more relevant measure and recommend said part of the article be rewritten using it. 07:44, 22 Dec 2004 (UTC) Further data, from Ping: "To have some comparison for internet ping times, consider that the shortest possible ping to the other side of our planet is 95 ms. That is because 95 ms is the time the light needs to travel to the other side and back in a straight line through the earth. No signal can travel faster than light. The shortest possible ping would be 133 ms if we avoided a subterranean route." 12.223.239.28 05:02, 23 Dec 2004 (UTC)

## Reworking content

The following needs to be reworked to make it fit in the context of an encyclopedia article. As it is it is a bit too chatty.

=== How Fast is the Speed of light ===
I like to use the vacation analogy to give people a feel for how fast the speed of light is. It goes like this. Let’s say I wanted to take a vacation on the moon. Fortunately there is a highway called Pretend that connects the earth to the moon. The speed limit on highway Pretend is 100 mph and I can only drive 10 hours a day. I had better pack a big trailer with plenty of food and pull it behind my SUV because under these conditions it is going to take me about 250 days to get from the earth to the moon. Light can travel the same distance in one and one forth seconds or about 5 beats of the drum at one-quarter time.

## Faster than c

As a layman, I don't understand how it's possible for something to travel faster than c but not carry information faster than c. Could someone explain this? -- User:Evercat

A very rough explanation is that the "something' that travel faster than light doesn't carry energy. -- looxix 00:43 Apr 19, 2003 (UTC)
Also, it is only in a vacuum than nothing (no information) can travel faster than light; in a medium thing can travel faster than light (see Cherenkov effect) -- looxix 00:49 Apr 19, 2003 (UTC)

Irrelevant. The electrons involved in the Cherenkov effect are still going slower than c. (It is true that light travels even slower than those electrons in that medium).

The fact that Group velocity is greater than c doesn't mean that there is really a particle moving (travelling) at that speed but rather that something is changing at this speed, in this case the waveform. (See also Phase velocity) -- ReiVaX 16:44, 18 Jul 2004 (UTC)

Sure. Take a laser pointer. Make a spot on the moon. Then turn your wrist to make a spot on the earth. It takes over a second for light to travel from the moon to the earth, yet I can move that little spot the same distance in far less than one second. --68.229.240.25 03:54, 20 Jul 2004 (UTC)

Similar, probably better, explanations:

## Wave equation?

"It is a solution to the wave equation"

How is the speed of light be a solution to a vector equation? Κσυπ Cyp 08:08, 13 Nov 2003 (UTC)
As my electromagnetics professor explained it (and you'll have to bear with me - it's been almost 2 years), it's not that the speed is the solution, per se. It just doesn't have a solution for any other speed besides C. --Raul654 08:28, 13 Nov 2003 (UTC)
One more thing. Here is the exact derivation you are looking for: http://people.ccmr.cornell.edu/~muchomas/P214/Notes/OtherWaves/node18.html --Raul654 08:36, 13 Nov 2003 (UTC)

If I understood correctly. <- This sentence was written by me. Κσυπ Cyp 21:30, 16 Nov 2003 (UTC) The rest wasn't. -> Faster than light transmission of information follows some uncertainty principals, it also sidesteps a couple rules. When information is transmitted at such speeds, it can never be proven that the light recieved is the light that was transmitted. Photons subjected to this process have their frequency changed, their overall energy content is different due to the processes that caused this feat. However, if those people in line were to shout in sequence, the information would have to be previously known, this caused it's own speculation. As with the noted experiment of 300c, the photons arrived faster than light accounts for, the arrival of the photons is information, it arrived at it's destination faster than C, there IS NO explanation. - GouRou

## Scientific notation

Wile, why are you removing the scientific notation approximation? In 99% of cases when I'm performing a calculation involving the speed of light, the number I'm looking for is 3 × 108. I'm pretty sure this approximation, in this format, is useful to other people as well. Fredrik (talk) 18:49, 8 Jun 2004 (UTC)

Well, it is cluttering, as it doesn't serve any obvious purpose. Anyone who is actually making use of c in computations is surely capable of approximating it as 3 times 10^8 or 0.2998 times 10^9 or whatever they please. The vast majority of the remainder of the readers will be much more at home with "thousands of somethings" instead of scientific notation. -- I feel pretty strongly that the introductory sentences of an article must get right straight to the point. Naturally it is quite possible that the introduction still isn't getting there, so let's work in that direction. Regards, Wile E. Heresiarch 20:45, 8 Jun 2004 (UTC)
How would you know that anyone actually making use of c is capable of approximating it? Every high school student? It isn't immediately obvious to everybody that 100,000 kilometers equals 108 meters. And sure, they might be able to figure it out, but our job is to make this information available as conveniently as possible. Perhaps the note should be placed elsewhere, but there's no reason not to provide it. Fredrik (talk) 21:02, 8 Jun 2004 (UTC)
We don't seem to be discussing anything very fundamental here; the article is about the speed of light, not scientific notation. That 299,792,458 is close to 3 x 10^8 seems to be a footnote that is useful in some contexts. Maybe there is a place for it somewhere in the article (or maybe not) but it seems far from central. Wile E. Heresiarch 21:24, 8 Jun 2004 (UTC)
This is not an article about scientific notation, but it is neither an article about obsolete imperial units (the mile). The question is indeed whether the information is central (useful to someone), and I hold that it is. It would be nice to get input from a few other people with regard to this matter. Fredrik (talk) 07:36, 9 Jun 2004 (UTC)
I've put the 3 × 10^8 m/s just before 30 cm/ns (under the heading "Overview"). It is appropriate since both are convenient approximations. Wile E. Heresiarch 16:21, 9 Jun 2004 (UTC)
Thank you. Fredrik (talk) 16:30, 9 Jun 2004 (UTC)

I'd like to support Fredrik on this point. It's far simpler to get a quick idea of the scale of c without having to count the number of digits in 300,000,000. Cederal 16:52, 9 Jun 2004 (UTC)

I think that perhaps it should be clearly stated that by adding two velocities with the Einstein velocity addition formula we cannot get a speed greater than c. (Because the interval (-c,c) with that operation is an Abelian group.) I know that its said that c is a "speed limit" but what its not said is that the formula is consistent with that. -- ReiVaX 18:09, 18 Jul 2004 (UTC)

## Definition of the metre

The article currently says:

Definition of the Metre
Since the speed of light in vacuum is constant, it is convenient to measure both time and distance in terms of c . Both the SI unit of length and SI unit of time have been defined in terms of wavelengths and cycles of light. In 1983 the metre was redefined in terms of c .

I'm fairly certain that is correct for "distance", but incorrect for "time". If you read http://www.bldrdoc.gov/timefreq/general/precision.htm#Anchor-60273 carefully, you see that "transitions of the cesium atom" are the reference for time, not the speed of that light.

Suggested replacement:

Definition of the Metre
Since the speed of light in vacuum is constant, it is convenient to measure distance in terms of c and time. In 1983, the SI unit of length (the meter) was redefined in terms of c and time.
Sounds good to me. Go ahead and change it if you want, I'll do it if you don't get around to it. Wile E. Heresiarch 03:15, 21 Jul 2004 (UTC)

For a Featured Article this should have some graphics. Yes, I know it it is hard to find a good graphic for speed of light, but perhapse Google Image search will have something we can use? --Piotr Konieczny aka Prokonsul Piotrus 21:37, 31 Jul 2004 (UTC)

A diagram of the Fizeau apparatus would fill the requirement, and might be useful in explaining that experiment. Dandrake 08:25, Aug 6, 2004 (UTC)

## Galileo

In Two New Sciences Galileo claimed to have performed his experiment, not just proposed it (though in a more ambiguous way than I'd realized); he also said explicitly, long before Hooke, that his experiment couldn't prove that the speed was infinite. Assuming he did perform it, this is the first known case of anyone's trying to make an actual measurement of the speed. The criticism by Descartes is interesting and looks as if it would be valid; does anyone know the argument in enough detail to say? Dandrake 08:25, Aug 6, 2004 (UTC)

## begging the question

According to the theory of special relativity, all observers will measure the speed of light as being the same, regardless of the reference frame of the observer or the velocity of the object emitting the light. A simple three-step analysis is sufficient to show that this is the case:

1. the speed of light in vacuum can be derived from Maxwell's equations;
2. special relativity requires the laws of physics, such as Maxwell's equations, to be identical in all unaccelerated frames, and so
3. observers in all such frames must observe the same speed of light.

The constant speed of light derives from the Lorentz transforms, which distort distances and times for observers travelling at large velocities in the same way.

Isn't 3 precisely what we are trying to show is the case? "all observers will measure the speed of light as being the same" because "observers in all such frames must observe the same speed of light"? Also, as the speed of light in a vaacum is a defined value, the fact that it can be derived from Maxwell's equations needs to be explained. anthony (see warning) 19:00, 12 Aug 2004 (UTC)

Er - to précis - "ToSR says SoL is constant. How? Because (i) SoL comes directly from Maxwell, (ii) Maxwell is a law of physics, (iii) laws of physics must be the same in all inertial frames; hence, (iv) SoL same in all inertial frames. Plus Lorentz gives you a way to work out how it all works." I don't think this is begging the question, is it? -- ALoan (Talk) 19:14, 12 Aug 2004 (UTC)

I guess I see what is being said. 3 is the conclusion from 1 and 2. This seems to be worded strangely, though. anthony (see warning) 19:41, 12 Aug 2004 (UTC)

Feel free to copyedit. :) -- ALoan (Talk) 19:48, 12 Aug 2004 (UTC)

As you've perhaps seen I've already made a number of copyedits. This one I'm not sure how to reword, though, in part because I'm not 100% sure what the point is. anthony (see warning) 20:12, 12 Aug 2004 (UTC)

I've tweaked slightly - is that better? -- ALoan (Talk) 02:05, 15 Aug 2004 (UTC)
I guess. I'm still confused as to what we are showing to be the case. Are we showing that "all observers will measure the speed of light as being the same" or are we showing that this is a result of the theory of relativity? Because it's not really a result of the theory or relativity, it's a postulate of the theory or relativity (I think, I'll double-check that one). anthony (see warning) 02:21, 15 Aug 2004 (UTC)
Yes, "We will raise this conjecture (the purport of which will hereafter be called the "Principle of Relativity") to the status of a postulate, and also introduce another postulate, which is only apparently irreconcilable with the former, namely, that light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body." Well, sort of. Einstein goes beyond saying that "all observers will measure the speed of light as being the same", and actually posits that the speed of light always is the same. anthony (see warning) 02:27, 15 Aug 2004 (UTC)

The article looks great! But... (ther's always a but):
(a) in 1: «The constant speed of light derives from the Lorentz transforms, which distort distances and times for observers travelling at large velocities in the same way» - I think it's the other way around. The Lorentz transforms derives from Maxwell's equations and Einstein's constant speed of light postulate.

(b) in 4.1: «Einstein took [the Michelson-Morley experiment] result as a given fact» contradicted by «It is uncertain whether Albert Einstein knew the results of the Michelson-Morley experiment» (in 5.4). - I don't know wich is true.
(c) I failed to understand the concept of "light slowing". Can someone elaborate on that?--Nabla 00:12, 2004 Aug 13 (UTC)

re (a): Yes, that's the same point I argued. In a way, the very notion of "distance" requires some means of measuring it. Einstein's reasoning was to require everything to be done locally, at one point. So, he defined distance as the quantity that you can measure by sending a light pulse to a mirror and wait for it to come back, than halve the time it took and devide it by c. You need this definition to derive the Lorentz transform. But the definition is only compatible to the usual notion of distance if you assume c to be constant.
re (b) I remember having read that Einstein said, that he was unaware of the works of Lorentz and Fitzgerald, who had found the Lorentz transformation and the relativistic length contraction before Einstein. (However, they only postulated them heuristically in order to explain the Michelson-Morley experiment and the anomalies of the Thompson parabolas, without being able to give a derivation.) But I doubt that Einstein was unaware of the whole aether discussion as otherwise he surely must have slept well during his university studies.
But let's check his origibnal 1905 paper which is translated here: "Examples of this sort, together with the unsuccessful attempts to discover any motion of the earth relatively to the "light medium," suggest that the phenomena of electrodynamics as well as of mechanics possess no properties corresponding to the idea of absolute rest." So what else could he have had in mind when referring to these "unsuccesful attempts" other than the Michelson-Morley experiment? => The second sentence is wrong.
re (c): It's not well written. First one should mention that of course light is always slower than c when travelling through media. But, usually, the light speed is perhaps 3/4 of it (in water), or maybe half of it (Flint glass) - but recently, people managed to reduce the speed down to only a few meters per second, using additional laser fields which modify the optical properties of the medium. In my opinion this should go in a seperate article - or maybe we have one already.
Simon A. 08:57, 13 Aug 2004 (UTC)
Thanks.
Re (a): of course, Lorentz formulated his transforms before Einstein thought up relativity, but I see what you mean. The intention here was simply to explain how a person travelling at 0.9c could still measure a speed of light of c because distances and times are dilated. If you can think of a better way of doing it, please be my guest.
Re (b): One of the sentences must be wrong. I've seen it reported a couple times that Einstein was not aware (or said he was not aware) of the Michelson-Morley result in 1905, so I've fixed the first passage (in any event, I think there were other, also unsuccessful, attempts to measure the velocity of the aether, apart from Michelson-Morley).
Re (c): I've reworded substantially. -- ALoan (Talk) 02:05, 15 Aug 2004 (UTC)
Deleted:
A simple analysis can be used to suggest that this is the case:
• the speed of light in a vacuum can be derived from Maxwell's equations, and
• special relativity posits that the laws of physics (such as Maxwell's equations) are identical in all unaccelerated frames; therefore:
• observers in all such frames must observe the same speed of light.
from Overview
It is stating that the speed of light being a constant may be derived from Maxwell's equations. AFAIK there is no (known) reason why it is constant. It just is. That is a postulate of Albert Einstein's Special Relativity. I quote from On the Electrodynamics of Moving Bodies: We will raise this conjecture [that the same laws of electrodynamics and optics will be valid for all frames of reference for which the equations of mechanics hold good] to the status of a postulate, and also introduce another postulate, which is only apparently irreconcilable with the former, namely, that light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body. (my bolds and wikilink)
True. Well found quote. One might, however argue, that the postulate that the speed of light is constant is not an independet postulate but rather a direct corrolary to Galilei's postulate of relativity when looking at Maxwell's equation and cutting away any aether with Occam's razor. This, in a way, how Einstein actually thought, but as the whole aether controversy was precisely about how to interprete Maxwell's equations in the light of the principle of relativity, Einstein did well in making clear that he was convinced of a specific interpretation of the principle of relativity, namely the one saying that also the speed of light is the same anywhere, as all other laws are the same anywhere. So, he made the principle of relativity more specific, i.e. added something to it. Now where you call this addition a part or implication of the old, now clarified principle or a new principle is just a matter of taste. Einstein, I think put it sometimes this way and sometimes the other way. Simon A. 12:17, 20 Aug 2004 (UTC)

I am the speed of light

## Varying speed of light

An anon recently added the following:

"Several physicist like Joao Magueijo, John Moffat have proposed that, in the past, light travelled much faster than the current speed of light. This theory is called VSL (varying speed of light), and it has the ability to explain most of the cosmological puzzles and is a rival of the inflation model of the universe."

At first it sounded like pseudoscience, but a quick google search turned up a number of references that at least appeared to have a chance to be legit. Is anyone else more familiar with this? - Taxman 20:15, Sep 13, 2004 (UTC)

I'd like to add my request for a bit more clarification on that point, either in this page or in a link. I've heard of the idea that the speed of light was higher at the beginning of the universe, then decayed to the current level and is now constant, but that particular concept is a load of creationist hogwash (see http://www.talkorigins.org/faqs/c-decay.html ). The only person behind they theory mentioned in the above link is one Barry Setterfield, not either of the two names in this article. Is this a different (and more reputable) theory? Should there be something in there (or in a link) explaining so, if they are different? - Mokele 17:00, Oct 2 2004

Joao Magueijo lectures (at least until recently) at the Department of Physics of Imperial College in London, and he seems to know what he is talking about. I think the New Scientist had an article on the VSL theory. I think that most physicist view the VSL as highly speculative at the best, but certainly not pseudoscience. As far as I can see from following the link, Setterfield's theory is not part of regular science. Disclaimer: I'm not a physicist. -- Jitse Niesen 23:28, 29 Oct 2004 (UTC)

A changing speed of light has been proposed to explain observations of "the accelerating Universe". Link at: http://www-conf.slac.stanford.edu/einstein/Talks/aspauthor2004_3.pdf

If it is left in, I hope that someone could square it with the following: "This exact speed is a definition, not a measurement, as the metre is defined in terms of the speed of light and the second." If the speed is defined to be <so big> how can it vary? -- a different anon.

The size of the metre would change with the speed of light. --Doradus 21:35, Nov 3, 2004 (UTC)

## Disambiguating Node

The page node (a disambig page) is currently in the process of being successfully split. Which use of the word "node" should be linked to in this sentence: "The speed of light can also be of concern on short distances. In supercomputers, the speed of light imposes a limit on how quickly data can be sent between nodes"? --MatrixFrog 07:15, 19 Sep 2004 (UTC)

I believe a more specific question would be whether it should be node (physics) or node (networking). GPHemsley 03:22, Sep 23, 2004 (UTC)
It appears this issue is moot, as the reference to node was changed to processor. GPHemsley 18:56, Oct 11, 2004 (UTC)

## Replace picture at top of article?

Hello all. This is a great article, thanks to everyone who has worked on it. I wonder if we really need the picture at the top of the article. It shows two nerdy guys playing with a laser, which is fun, but beside the point. Can we find another picture that directly addresses the topic? The caption does state something interesting about the speed of light but, strangely enough, doesn't describe something illustrated in the picture. Maybe someone can state what it is about the speed of light that it illustrates. Regards & happy editing, Wile E. Heresiarch 13:52, 11 Oct 2004 (UTC)

Well, if you have a better picture, be my guest! Although light itself is quite visual, the speed of light is rather hard to see. Cherenkov effect?. -- ALoan (Talk) 19:09, 11 Oct 2004 (UTC)
Thanks for the suggestion. I've replaced the laser guys with the picture from Cherenkov effect. Although it is a very lovely shade of blue, the picture is a little fuzzy and hard to read. We could improve it with a sharper image; I guess I'll keep my eyes open. Wile E. Heresiarch 03:44, 12 Oct 2004 (UTC)
I've put the guys back lower down, in the "slower than light" section where it makes more sense. -- ALoan (Talk) 11:36, 12 Oct 2004 (UTC)
I guess I'm a bit mystified by the longevity of the laser guys picture in this article. The caption is correct, the speed of light is less in air than vacuum, but one can't see that from the picture. The picture is also somewhat misleading since it might be construed as an illustration of the light-slowing experiments referenced in the text. A picture of a glass lens or a diamond would show an observable effect of the different speeds of light, come to think of it. I'll keep my eyes open. Wile E. Heresiarch 13:38, 12 Oct 2004 (UTC)
File:PrismAndLight.jpg
Light refraction in a prism

I agree that the image on top is not good enough. It does not demonstrate the speed of light at all, although it looks somewhat fancy. But an encyclopedia should have a more illustrative image. I tried to find a PD image of light refraction in a prism. What about this one. -- [[User:Solitude|Solitude\talk]] 08:48, Oct 29, 2004 (UTC)

Also, the image used on top at the moment does not seem to be free at all. It is used with permission, but it is not stated how far this permission reaches. Can it be used commerially at all? As far as I know we can't use NC images, especially in featured articles, especially on TOP. -- [[User:Solitude|Solitude\talk]] 08:53, Oct 29, 2004 (UTC)

## Meter or metre?

I have noticed that the article uses both spellings. Which is the appropriate spelling for this article?

Thanks - metre is far more common in the article, so I've changed the other couple of occurences. -- ALoan (Talk) 19:09, 11 Oct 2004 (UTC)

## Bogus argument

I don't think this is sufficient:

Experiments show that the second particle takes up its quantum state instantaneously, as soon as the first observation is carried out. However, it is impossible to control which quantum state the first particle will take on when it is observed, so no information can be transmitted in this manner.

The telegraph is able to transmit information, and it also provides no control of the state that the remote key will take when observed; all the operator can control is when the key will move.

The real reason information can't be transmitted this way must be more subtle. --Doradus

Yes, but the timing of the movement of the key is the factor that transmits the information in a telegraph.
But the first sentence I quoted above seems to imply that one can determine exactly when the second particle "takes up its quantum state", and hence when the first particle was "observed". Let me be clear: I'm sure entangled particles can't be used as a telegraph. My point is that the above quote is not convincing in this regard. --Doradus
Hmm - I wonder if you would transmit a stream of entangled particles, and use that stream like a telegraph... -- ALoan (Talk) 10:26, 29 Oct 2004 (UTC)
Well, for one thing, those entangled particles would only travel at the speed of light, and for another thing, if you think you have thought of a way to transmit information faster than light in a vacuum, then it almost certainly won't work. --Doradus 18:11, Oct 29, 2004 (UTC)

## Refractive index

The phrasing "speed of light ... is less than c due to the refractive index." suggests to me at least that the refractive index is some sort of phenomenon that causes the SOL to be lower in some medium, when it is really defined as a measure of how much slower light moves through a particular medium than through vacuum. I suggest a re-phrasing to avoid the possible confusion. Even to just say "... is less than c (see refractive index)" would be better in my opinion. --Schnolle 10:46, 29 Oct 2004 (UTC)

I'm not sure what two concepts you fear will be confused. The concepts of the speed of light being "lower in some medium" and "how much slower light moves through a particular medium than through vacuum" seem equivalent to me. --Doradus
The confusion is not about the concepts, rather that someone might be led to believe that "A is due to B" means that "B is the cause of A", which is not the case here. --Schnolle 18:32, 29 Oct 2004 (UTC)
(Doradus) Sorry, can you spell this out for me? What are A and B?

In a recent article I read that understood "speed of light" has been altered to a considerable faster speed. Perhaps the creater of this page might want to address that note, althought it is my understanding for the sake of physic's discussions the speed of 186K MPS is still the accepted number.

That is absurd. For such a radical change in the laws of physics, you ought to at least provide some kind of reference. As Carl Sagan once said, "extraordinary claims require extraordinary proof". --Doradus

I've reverted to put back the image of Cherenkov radiation as the lead image: a featured article ought to have a lead image, and this is the best example I can think of the image the actually shows "the speed of light" in a visible form. But I'd happily defer if someone can think of a better example. -- ALoan (Talk) 11:30, 16 Dec 2004 (UTC)

## Limitation to the current theories?

Well, I do not have any proof or any references that support what I am going to say. It is just something at the back of my mind that refuses to accept speed of light is the maximum speed attainable. All the formulas, explanations and examples of the formulas that I have come across always came back to point out that nothing could travel faster than speed of light: either the mass becomes infinity or something went into an imaginary number (square-root of negative one). For some reason, nothing I have read could explain to me what is the meaning of imaginary number with respect to physical manifestation (ps: imaginary number is not the number you imagine :D ). The only thing I know is that imaginary number is used in wave theory and in math when converting from one coordinates to another such as cartesian vs polar coordinates. Does it mean things that travel faster than light are all in wave or can be explained in wave theories?

Well, the good news is that after reading this article about the speed of light, some of what I believed has been affirmed --- speed of light is just like speed of sound: it is constant in a given medium. Light in each medium has its own speed. I have argued about this with my roommates for many weeks sometime in the early 1980s till we agreed to disagree. We were college students then. My roommates had GPA close to 4.0 while mine was closer to 2.8. They quoted a few theories that stated speed of light was absolute and constant regardless of medium. I was not convinced.

However, there is still one more unresolved issue. I believe, just like speed of sound, there are things out there that can travel faster than speed of light and capable of carrying meaningful information. From what I have read, this is contrary to the currently accepted view of things.

Here is my basic reasoning: speed of light is the maximum speed that we, as a human being, can perceive. Every single one of our observations were based on light --- we use our eyes to see every single one of our experiments, measurements and results. In addition, our brains are used to translating everything around us into the terms we understand --- both consciously and sub-consciously. These two combined, I believe, is the reason for the "distortions" that we perceive when an object approaches the speed of light.

Well, many of you will argue that our instrument are not affected and should show us the truth. Well, I have a few "arguments" to that. Some of the arguments is based on the fact that we "see" things from bounced light which, in itself, distort what we see. Here are the arguments:

1. we build and interpret those instruments which means they may be subject to our limitations;
2. those instruments use light (or something slower than light such as sound) to detect whatever they are designed to detect;
3. I do not believe we have taken into consideration the effect of speed of light in our basic definitions and our instruments. For example: how does it affect our definition of "meter", "gram", etc. Also, how does it affect the count of the spin of electron of cesium which, in turn, is used by our most "accurate" clock (atomic clock) to define a "second";
4. most of our instrument can only detect what we design them to detect based on the knowledge we have. Very rarely we come across an instrument that detects what it was not designed to detect and appreciated --- most of the instruments that detected something they are not designed to are thrown away as junk or considered to have malfunctioned.

Well, I hope someone can convince me that those scientists have removed/nullified/compensated the effect of light from their experiments. If so, I would like to know how they did it instead of saying that they just did. Personally, I hope I am right: Speed of light is just like speed of sound --- something we can safely exceed if we have the technology. If so, it will open up a lot of possibilities. I am, however, open to suggestions.

Food for thought: What makes you think you have not seen anything that moves faster than speed of light? Do you know how they look like? Do you think those unduplicated and unexplained "blips" or errors on an otherwise perfect experiments that "you can safely ignore" are really errors or ..... (For example, how do you detect a car travelling at 100 KPH with a pellet gun fired at 1 bullet per second perpendicular to the direction of the car's travel at a fixed point on the road? Will you take the bounce of a bullet versus a hundred that went through the air as the desired result or an error?)

Anyway, have fun everyone.

Regards, The Wondering Mind Sept. 7, 2005

## Limitation of current theories?

Well, I do not have any proof or any references that support what I am going to say. It is just something at the back of my mind that refuses to accept speed of light is the maximum speed attainable. All the formulas, explanations and examples of the formulas that I have come across always came back to point out that nothing could travel faster than speed of light: either the mass becomes infinity or something went into an imaginary number (square-root of negative one). For some reason, nothing I have read could explain to me what is the meaning of imaginary number with respect to physical manifestation (ps: imaginary number is not the number you imagine :D ). The only thing I know is that imaginary number is used in wave theory and in math when converting from one coordinates to another such as cartesian vs polar coordinates. Does it mean things that travel faster than light are all in wave or can be explained in wave theories?

Well, the good news is that after reading this article about the speed of light, some of what I believed has been affirmed --- speed of light is just like speed of sound: it is constant in a given medium. Light in each medium has its own speed. I have argued about this with my roommates for many weeks sometime in the early 1980s till we agreed to disagree. We were college students then. My roommates had GPA close to 4.0 while mine was closer to 2.8. They quoted a few theories that stated speed of light was absolute and constant regardless of medium. I was not convinced.

However, there is still one more unresolved issue. I believe, just like speed of sound, there are things out there that can travel faster than speed of light and capable of carrying meaningful information. From what I have read, this is contrary to the currently accepted view of things.

Here is my basic reasoning: speed of light is the maximum speed that we, as a human being, can perceive. Every single one of our observations were based on light --- we use our eyes to see every single one of our experiments, measurements and results. In addition, our brains are used to translating everything around us into the terms we understand --- both consciously and sub-consciously. These two combined, I believe, is the reason for the "distortions" that we perceive when an object approaches the speed of light.

Well, many of you will argue that our instrument are not affected and should show us the truth. Well, I have a few "arguments" to that. Some of the arguments is based on the fact that we "see" things from bounced light which, in itself, distort what we see. Here are the arguments:

1. we build and interpret those instruments which means they may be subject to our limitations;
2. those instruments use light (or something slower than light such as sound) to detect whatever they are designed to detect;
3. I do not believe we have taken into consideration the effect of speed of light in our basic definitions and our instruments. For example: how does it affect our definition of "meter", "gram", etc. Also, how does it affect the count of the spin of electron of cesium which, in turn, is used by our most "accurate" clock (atomic clock) to define a "second";
4. most of our instrument can only detect what we design them to detect based on the knowledge we have. Very rarely we come across an instrument that detects what it was not designed to detect and appreciated --- most of the instruments that detected something they are not designed to are thrown away as junk or considered to have malfunctioned.

Well, I hope someone can convince me that those scientists have removed/nullified/compensated the effect of light from their experiments. If so, I would like to know how they did it instead of saying that they just did. Personally, I hope I am right: Speed of light is just like speed of sound --- something we can safely exceed if we have the technology. If so, it will open up a lot of possibilities. I am, however, open to suggestions.

Food for thought: What makes you think you have not seen anything that moves faster than speed of light? Do you know how they look like? Do you think those unduplicated and unexplained "blips" or errors on an otherwise perfect experiments that "you can safely ignore" are really errors or ..... (For example, how do you detect a car travelling at 100 KPH with a pellet gun fired at 1 bullet per second perpendicular to the direction of the car's travel at a fixed point on the road? Will you take the bounce of a bullet versus a hundred that went through the air as the desired result or an error?)

Anyway, have fun everyone.

Regards, The Wondering Mind Sept. 7, 2005

## Sorry for the double submission

Sorry for the double submission. My web page gave me an error when I posted the first one. I did not see the article posted until after I posted the second one.

Regards, The Wondering Mind Sept. 7, 2005

## Applied Light Physics

Relative speed of light is less important to the nature of light than the fact that the speed of light is the speed at which the matter that makes up a body has neglidgible ability to react with matter moving at a similar speed (including friction wich would lead to near exact translation), which suggests four things, that any body moving the speed of light is for all purposes light, that light travel would be posible if you could actually slow the speed of light, rather than just refract it in place, and through refraction you would be able to freeze all reaction over an indefinite time a body, the last important difference this would make is proof that actual speeds (speed relative to a stationary point) of greater than light are impossible for the sole reason that they are unable to react in any way that would create further prepulsion.

- Nicho I.

## Assessment comment

The comment(s) below were originally left at Talk:Speed of light/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Press [show] to view → Comment(s) The following sentence, which appears in the article, is either contradictory in itself, or implies some kind of speed-of-light travel which occurs, but not through space. It needs clarification: If this is true, an object may travel at the speed of light, but it will not travel through space when this is done, as no time will pass while it is at the speed of light. --4.239.0.189 17:56, 23 February 2007 (UTC) If we send a light ray to the moon and wait approximately 2 1/2 seconds, we will receive a returned reflection. So we have existed in a time dimension for a time period we have quantified as 2 1/2 seconds. We then say that the time dimension existing for the moving light ray (and anything associated with it) is reduced to zero, and that it can go anywhere in zero time. This sounds unreasonable, But does involve the more reasonable proposition that there is an interrelationship between our methods of measuring time and space, and that they are not independent of each other. So now we're embroiled in the mathematical intricacies of an interdependent spacetime continuum, without having developed any particular reason why the velocity of light is what it is, or even a willingness to consider that it is the result of some physical process involving a moving particle.WFPM (talk) 18:05, 17 August 2009 (UTC)

Last edited at 18:07, 17 August 2009 (UTC). Substituted at 22:04, 3 May 2016 (UTC)