I remember seeing something a little while ago about a possible new theory about the fact that the speed of light has not remained constant throughout the lifetime of the universe. The theory suggested (I think) that in fact the speed of light has changed during the development of the known universe and has in fact slowed down (I think that was it).

It was suggested this would then be a way that the universe has developed certain traits and with this as a "controlling" variable, would explain a lot about the "steady state" universe.... or was it the "big bang" theory? .... You see, my memory of what I read and saw seems to be failing me already!

Does anyone else know anything about this (refered to as VSL Theory - Variable Speed of Light) or has it been proved/disproved yet? There were some things there that seemed to me to make a kindf of sense, but being basically an engineer, I don't necessarily believe everything I see or read. I like to research things and discuss it with people in the know more than myself. I would then try to independently verify such information.

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The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!) but rather, 'hmm.... that's funny...'
- Isaac Asimov

Are we alone in the Universe? Are we the only intelligent life? Who knows? But the universe is so BIG, it somehow seems such a waste of space if we are ....

Light is the limit. And it is constant.
If, in all frames of reference, we are to believe that the laws of physics do indeed hold sway, then light has to be constant and time the variable.
If not, then the laws of physics wouldn't apply to any reference frame, which is against every major indication...

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Feynman
>~~~~<
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.

Religion is a culture of faith; science is a culture of doubt.

Are you sure what you read surgested a change in the speed of light of the difference between results for different experiments. Or is it the change of the speed of transmission through dense objects. Or was it one of the "the speed of light has been changing since the dawn of time! but our theory didn't last past a math check".

Okay i've become extremely skeptical about changing speed of light as they normally turn out to be bad science.

I have been doing some further digging and I have found the references etc. There was a program on UK Channel 4 in the Equinox series about it. Equinox is a fairly respected science programme series, tackling many interesting topics and trying to put them forward in understandable terms.

It was about someone called Joao Magueijo who put forward the theory. He was at the time based at Imperial College, London, and the web link to his page reflected this. However, the link I had no longer works so I was wondering if his theory has been taken down or he has just "moved on"...

Does anyone know anything about this? There was also an article soon afterwards showing the same theory in the Sunday Times magazine, which again is a fairly well respected publication....

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The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!) but rather, 'hmm.... that's funny...'
- Isaac Asimov

Are we alone in the Universe? Are we the only intelligent life? Who knows? But the universe is so BIG, it somehow seems such a waste of space if we are ....

I have seen the variable speed of light brought up by creationists in their pathetic attempts to prove that the universe is only 7000 years old.

I must admit though that I have often wondered why, if gravity can bend light rays it could not also speed them up or slow them down.

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Dave(The Admiral)Nelson

Forgive me if this is ignorant...

Light moves slower the denser the medium, right?

Wasn't the universe much denser early on?

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Channel 4 still works for ratings but it does put some good science on tv like the nova programs. I remember seeing the program you're talking about and i wouldn't put my money on it as being their best researched program.

I think the subject of changing speeds of light is a dangerous subject and unless you're the next Einstein, Feynman or Hawking not many people are going to take you seriously.

Well I don't think it's ignorant, I think it's a good point.
I think though that at the time when the universe was dense enough to slow the speed of light our solar system or perhaps our galaxy had yet to form.

I however am no scientst. My meager scientific knowege was gained from reading Clarke, Asimov, Gardener, Sagan and others.

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Dave(The Admiral)Nelson

VSL is a non-standard cosmology, aart from the obvious though I don't know much about it.

The work done on it is credible enough to be be published in peer-reviewed papers (unlike alot of the other theories posted on this forum, mentioning no names) and Joao Magueijo is no crank.

Right. If you search google for this issue, it's remarkable that nearly 9 out of 10 sites mentioning this question are fundamentalist religion sites. Apparently they're following the dictum, "If you don't have the facts, flood the discussion with gobbledegook."

But there is serious scientific research into the question (hence the news reports). It normally focuses on the question of the constancy of the fine structure constant, which is mathematically tied to the speed of light. I believe recent research has tightly constrained any variability in these fundamental constants. In other words, if they vary at all over the history of the universe, it can't be by much! And certainly not nearly enough to conclude that the age of the universe is 10 orders of magnitude smaller than we think it is, as the creationists are attempting to show.

When searching for meaningful discussions on this topic, I would stick to sites hosted by universities and other educational enterprises. And I would avoid sites with urls such as "lordibelieve.org".

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Everyone is entitled to his own opinion, but not his own facts.

Yes, but is he really doing anything more than saying, "What if the fundamental constants varied in the distant past?", and then following through and claiming that this could explain various observations. Of course, this is a big IF, and judging from some very recent research (Aug 2004), any variation is severely constrained, and the "big if" is quickly evaporating. To summarize the cited abstract (which is very technologically dense)....
That is, any variation is on the order of a couple parts in a million. Please remember that a million is a very, very big number.

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Everyone is entitled to his own opinion, but not his own facts.

Its a theory that was brought into serious discusion by Joao Magueijo, a cosmologist.

He wrote this book:

http://www.amazon.com/exec/obidos/tg...ce&amp;s=books

Look around online for cosmology pubs, papers on VSL are out there. A large number of cosmologists are taking a look at it now.

-Mcdugan

I knew he was a cosmologist, but I wasn't sure if his work was still "accepted", or whether he had been "sidelined" by the mainstream.

Reading the book reviews on Amazon he is getting a rather varied response! I remember the theories he put forward were somewhat radical.

I did email him after the programme and looking this up his comments in relpy (it was a general email response) were to the effect that all scientists should be very careful of taking anything as "gospel", we should all edeavour to search for and research thoroughly any ideas put forward by an individual.

I was particularly interested to know if the VSL idea/theory was still around in Cosmologists thinking or whether it had now been "debunked", or whatever.

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The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!) but rather, 'hmm.... that's funny...'
- Isaac Asimov

Are we alone in the Universe? Are we the only intelligent life? Who knows? But the universe is so BIG, it somehow seems such a waste of space if we are ....

After reading about inflation and VSL, I tend to lean towards a VSL type idea more than inflation. Not saying it's correct but I like the path taken a bit better.

I relate inflation to dark energy/matter. They seem like idea excuses to make the math work. I'd rather hear someone say "we don't know why this does this but were trying to figure it out" rather than "It does this because of dark matter, and we don't know what dark matter is but were trying to figure it out." Seems like an unecessary step is being added to the understanding process to make it seem like we are farther than we are.

Just my two pennys.

-Mcdugan.

I tend to lean towards the VSL on this vs. inflation too. Currently there's no real good explanation for either (that I know of), but I can imagine the speed of light slowly changing much easier than the universe suddenly jumping in size.

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The path? Have you read Alan Guth's papers or his book? How do you know the path he took to arrive at Cosmological Inflation? Certainly there are unanswered questions and unverified assertions, but once one starts picking theories because they like them better, one has left science behind and entered the realm of religion.

The East African Masai wear jewelry with certain symbols on it that "wards off evil." What a great idea! I like it a lot. I also know it to be a baseless superstition, and if there's any effect, it's only in the mind of believers.

If you start choosing the science you accept according to what you can "imagine easier", you're going to have to reject all of the past 100 years' progress in quantum mechanics. Day-to-day human experience is no longer a very good guide in determing the universe's ultimate reality. But why should it be? Humans have only been a part of the goings-on in the universe for the last speck of universal time....

Actually, there IS an explanation behind the inflationary scenario. There is some support that it is correct, but it is certainly not verified at this point. But it's not just a "made-up" speculation. Its basis is firmly grounded in particle physics and general relativity.

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Everyone is entitled to his own opinion, but not his own facts.

And is this a case of people simply ignoring evidence that they don't like to hear about? My previous December 31 post linked to research tightly constraining the possibility that the speed of light has varied over the history of the universe. I believe other research has also found that any variation is either minescule or zero. If you want to continue "liking" the VSL theory, I think you're going to have to start showing the errors in all this research that concludes VSL isn't viable.

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Everyone is entitled to his own opinion, but not his own facts.

Oklo also provides a pretty good independant check on the variation in the fine structure constant out to ~ 2 billion years. (There was a hint, just slightly above the noise, of a slight variation, but I haven't heard anything since the initial announcement.)

(As an aside, as the metre is defined in terms of the distance travelled by light in a vacuum in a certain period of time, this pretty much defines c to be a constant. If you, 2 gigayears ago, set up an experiment using the current SI definitions of the second and the metre, you can't help but get the same answer as we do today. This sounds silly, but it's one reason why I prefer to talk in terms of the fine structure constant, rather than c. Perhaps it means that one day we may want to change our definition to allow for a wandering value of c? )

Cougar

Something you need to keep in mind is that not everyone is a scientist. I have a busy life, and can read a book here and there about cosmology or astronomy when I find the time. I am by no means an expert on the various theory nor could I "show" why I like some better than others. I’ve taken Astronomy 101 and read forums and books (once in a while). I’m in no position to show anything but I would still like to participate and throw out my two cents once in a while.

I think science is great for two reasons. It creates very complex conclusions and theories for other scientists to mull over, and it makes thing more easily understandable to the common man (me).

If anything, scientists should be happy as all heck that people like me -try- to participate in discussions because it gives a clearer insight into what the general population is understanding and not understanding. That insight, I assume, would give great thinkers some direction in how to make information easily understandable to the masses.

-Mcdugan

Variable speed of light

Hi Skyfire

Yes it is possible to have a varible speed of light, but I do not think you have to be, as Electromagneticpulse stated

“the next Einstein, Feynman or Hawking. “


The way to have the speed of light change is to keep all local measures of intervals of time their same proportional value and have all local measures of time change at some kind of geometrically described rate over the passage of absolute or Cosmic time. (Absolute or cosmic time is another dimension of time that describes a points location historically. Relativistic time describes the time interval between two points). Locally the speed of light remains constant, but if observed outside of, or from an “absolute” perspective, it would be possible to see that the speed of light, and the locally observed passage of time varies.

How could a light clock, ( a photon traveling between two mirrors), a vibrating crystal, chemical reactions, the swing of a pendulum, and orbital periods all change yet keep their proportional value? This would keep the locally valid relationship between distance and time as required for relativity (c = d/t) but such a thing seems impossible.

The answer to this impossible situation is to consider that the expansion of space-time is uniform; meaning that matter itself is expanding. This expansion also has to conform to specific geometric rules in order to preserve or establish stability.

The formulas describing the uniform expansion of space-time are fairly simple and only require a knowledge of 9th grade math to use. At it’s simplest form of expression it could be stated that the absolute volume of space-time increases with the square of the passage of absolute time. Double the age of the universe and the size of the universe increases 4 times. There is no local measure of this expansion since all local rulers are also proportionally expanded. Objects observe in the past would appear to be moving too fast for the amount of matter observed, hence the creation of “dark matter”.

Would anyone like to see how the proposed formulas keep all relative measures of time constant yet they change from an absolute or historical perspective?

John M. Kulick
AKA snowflake

Are you living in flatland?

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Everyone is entitled to his own opinion, but not his own facts.

Hi cougar

You got me, I should have said the volume increases 4 times. Thanks for the correction

snowflake

Sorry about dragging up an old topic, but I just wanted to add that I recently read Joao Maguerijo's book on VSL (my girlfriend bought it for me as a present) and wanted to share my thoughts on it.

Sadly, there's not a lot of science in the book supporting his ideas. In between his (quite excellent) descriptions of relativity, and endless diatribes against the upper authorities at Imperial College, string theorists and anyone else who has irked him over the last 20 years, there's precious little on the mechanics of VSL except for a "trust me, I'm a physicist" type condescension. It's a pity because he spends the first third of the book being very careful to get the reader onside and I have no doubt that he is a cosmologist or great intelligence. He just needs to credit his reader with some, that's all.

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The plural of "anecdote" is not "data".

I just hope that he is right. I think there was something about the speed of light being higher near and along cosmic superstrings--therefore a spacecraft could stay under c near the string--but be over c with respect to the surroundings.

If the universe is expanding faster due to gravity leakage---and if that article in SCI AM which describes constants as being different with respect to age of the universe--then perhaps VSL is worth taking a look at after all.

Not to mention, some of the sites I have seen base the whole "slowing light" idea on a couple of early measurements--that is, nineteenth century or so--that have the speed of light just a bit higher. There is no way that the universe has changed enough in the last century to measurably change a constant like that. And if it had, we would notice a continuing slowdown . . .

I think that some of this is legitimate speculation focused on the distant, distant past--but if they talk about the speed of light changing during the lifetime of the human race, it is more biological than cosmological. Bovine biology, to be specific.

Izunya

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Mal: Define "interesting!"
Wash: Oh God, oh God, we're all going to die?

- from Serenity

I should add that Maguerijo makes no mention of creationist theories and indeed there is nothing in his book that a creationist could actually use to support their "slowing speed of light" claptrap.

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The plural of "anecdote" is not "data".

There was a paper based upon a Cassini ranging experiment that severely constrained Joao Magueijo's theory...

...But the paper was withdrawn. I don't know why.

Magueijo points out in his book that relativity can also be interpreted as a variation in the speed of light rather than a time differential. This can be either another way of expressing general relativity, or a new or different theory, depending upon how light, time and gravity are treated.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

It's another way of expressing GR. Mathematically, it doesn't matter if light takes a greater amount of time because it actually slows down or it takes a longer path due to curvature. Note though that in both, light moves at c in flat space or in the absense of a gravitational field.

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Neptune- The original Dark Matter.

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