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Speed of Light Inconstant?
DHR writes "Australian scientists have discovered that light isn't quite as fast as it used to be." We've done previous stories on these findings. Those of you with subscriptions to Nature can read the actual paper, the rest of us will just have to suffer.
So, does that explain the ever changing warp scale in Star Trek?
Fascism starts when the efficiency of the government becomes more important than the rights of the people.
I've noticed it takes a while for flourescent lightbulbs to turn on. I guess all of the technology bloat has finally taken a noticable performance hit on light.
Would this perhaps be linked to the idea that there's a limited amount of energy in the universe, which is more and more being turned into kinnetic potential as objects get further and further from the center point?
Or perhaps we're just setting aside another 'unbreakable' barrier.
-GiH
the rest of us will just have to suffer.
And given our new knowledge about changes in the speed of light, you'll suffer a little more slowly then you are used to.
"Can of worms? The can is open... the worms are everywhere."
eh their mate, thats not a light.
Now that's a light.
> "That's illegal. It would be like a cup of coffee sitting on your desk getting hotter," Lineweaver says
Placing a coffee cup on top of my laptop and running Microsoft Outlook provides the exactly same effect. Where can I get my Nobel prize?
Since most of us don't have the subscription I deduce that the majority of replies will come from AC's and be composed of nonsense.
Appended to the end of comments you post. 120 chars.
There were a group of people in a room of different professions, and a theorem was put forth onto the board that stated that all Odd Numbers Are Prime. Each person was supposed to disprove this.
The mathematician started off by looking at each number.
1, 3, 5, 7, 9.... 9 is not prime, the theorem is false.
The social worker turned in a long sheet of paper going "2 is prime, 4 is prime, 6 is prime..." etc.
The physicist turned in the following:
1... 3... 5... 7... 9 (Experimental Error), 11, 13.....
/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i
Light's just getting a bit older and isn't as fast as it used to be. See how you feel after a 30 nano seconds of pick-up basketball, the parts just don't work the same when you get that old.
One possibility, though, is that the structure of the vacuum in space has changed. This is where we get into the rather spooky world of quantum physics. When light travels through a medium other than a vacuum, such as glass or water, it slows down. A vacuum, far from being empty, is teeming with quantum "virtual" particles that flit in and out of existence.
Sometimes those particles become real, such as under a strong electric charge, Lineweaver says. If the vacuum of space is changing uniformly across the universe, just as the universe is expanding uniformly, it could affect the speed of light.
Well... this was the hypothesis that was given in the article... and from the looks of this, it seems that there is a possibility that light didn't slow down at all. Here he explains that it is the medium that light is travelling in that is slowing it down. So light's top speed in a vacuum may still be the same... c, but the medium, the universe, is changing. Who knows.
But if light is slowing down, then that faster than light travel maybe possible. However, how the hell do you see anything when your going faster than any signal? Well... maybe you can communicate with the spooky particles and get instant communication while travelling at faster than light speeds. Of course you'd best be sure your data arrived promptly, as you'll never see the planet you just rammed.
Back in my day, light was blimblamming all over the place! We had GOOD light in those days. Yessiree, you couldn't go outside with your onion strapped to your belt (as was the fashion at the time) without getting knocked over by rays of light all the time! Not like today's LAZY light, mind you.
--------
Bleah! Heh heh heh... BLEAH BLEAH!!! Ha ha ha ha...
This is exactly the case put forward by Dr. Walt Brown (Ph. D.).
Daniel
Well, let's see here:
The speed of light -is- always constant in one sense,
simply because the length of 1 meter is defined by the distance light travels in a set time.
Now, from a more physical standpoint: We need more evidence.
Quite a few measurements of c have been done, and a single measurement isn't about to upend all this.
Extraordinary claims require extraordinary evidence, remember?
Now, nobody says that relativity is a complete and final theory. It probably isn't. But you still need lots
of evidence to replace it with another theory.
Otherwise, we won't even know if the theory we're replacing it with is better!
It's an interesting theory and experiment, but even so, I'd bet on this being a
freak result, for the simple reason that scientific breakthroughs don't come around that often.
I knew this performer once. Her stage name was "Infinity". I always wanted to take her out to dinner, just so when they said "how many in your party?", I could say "infinity plus one".
If the very early Universe, when all the matter and energy could be contained in a microdot, was such an exotic place that the speed of light approached infinity -- then what happened to the speed of sound?
Two points. First, the idea that the whole mass of the "universe" was contained in a microdot just at the Big Bang isn't really right (depending on what you mean by "universe"). The whole mass of today's observable universe, yes. But if you take the cosmological models at face value, the universe is probably infinite in extent, and always was (at least as far back as you can go without worrying about unknown theories of quantum gravity). It's more accurate to say that the density of the universe approached an arbitrarily large value; then you don't have to worry about a "smaller infinity" or similar.
Now, to what you actually asked: the speed of sound is not a fundamental quantity the way the speed of light is. "Speed of light" generally means "speed of light in a vacuum", which according to standard theory is a fundamental contant. (In material other than vacuum, light tends to travel at speeds less than the "speed of light".) Sound doesn't travel in a vacuum, but needs a medium to travel through. It's speed is entirely dependent on that medium. What we call the "Speed of sound" (when, say, timing distance to lightning strikes based on the delay before we hear the thunderclap) is the speed of sound in air at a typical density and pressure found on the surface of the Earth. The speed of sound in water is a lot higher. In rock, higher still.
In the very early universe, I would expect the speed of sound to be very, very high, but it will always be less than the speed of light in a vacuum (whatever that value happens to be at any given moment).
-Rob
Interesting they suggest that time and motion are different between two frames of reference travelling at different speeds.
Isn't this kinda the idea of relativity? How does it change the speed of light?
The reason Astronomers don't want to accept this is becuase it would change the nature of every cosmological theory they have. They've invested large amounts of time in old theories, why should they learn new ones? It's all about ego for them.
While there is a possible grain of truth in what you say, it's probably vastly overstated.
It would be better to say that extraordinary claims require extraordinary proof. To almost everybody, the claim that the fine structure constant has been changing is pretty extraordinary, and as such requires pretty solid proof before any measurable fraction of people who care about these things will casually accept it.
There is a danger in the iconoclastic argument. Yes, if a new truth is revolutionary and will require everybody to throw out everything they know, everybody will resist accepting that truth. It does not follow that therefore every revolutionary idea which meets widespread resistance must be a new truth.
-Rob
Yes, they laughed at the Wright brothers. But they also laughed at the Marx brothers. --From A Demon-Haunted World
So if the speed of light is slowing down, could we convert matter to energy, wait millions of years for the speed of light to change, and then convert it back - violating the conservation of energy laws?
Good question, but I would think probably not. E=mc^2 doesn't really tell you about some remarkable physical process that lets you convert between two differen things "mass" and "energy". Mass is just another form of energy, and that equation tells you how much energy you have in (say) one kilogram of mass.
I'd have to think harder whether or not there is a problem with conservation of energy here. Here's the challenge: come up with a thought experiment that lets you get "something for nothing" from a changing speed of light. Just counting the energy in the universe isn't good enough (see below); what you need is some way of increasing (say) the stored energy in a localized object or particle *without* introducing any energy or work from outside. I can't think of a way to do it, but maybe somebody else might. (I haven't really posed my thought experiment well; can somebody suggest a better way to pose it?)
The reason that just talking about the total energy in the universe isn't good enough is that in fact General Relativity already does *not* have a global law of conservation of energy! There is a *local* conservation of energy, which is expressed in terms of derivatives of the stress-energy tensor. However, the fact that there is no single global inertial reference frame for the whole universe makes it difficult to say what is the "energy of the universe".
You can come up with things that look like they violate conservation of energy with plain vanilla GR and cosmology right now. For instance, the cosmological redshift. Start with a universe that has one photon in it. The universe expands, and the photon redshifts. Now the photon has less energy. What happened to conservation of energy? Similarly, if you have a cosmological constant (vacuum energy), and your universe gets bigger, you have more vacuum, thus more energy. What happened to the conservation of energy? With an infinite universe you can always say that you're pushing work out to further and further reaches of the universe, and since you never reach an "edge" you don't have to worry about somebody ever having to absorb all that work. (With a closed universe, I believe that formally some of the energy goes into the curvature.) But, really, conservation of energy is a local concept in a GR rather than a universe-wide concept.
-Rob
It's that same group saying the same thing again.
Well, you are the same guy posting the same thing again, although I notice you have a different username than last time. Please tell me you didn't honestly go back to the previous story, pick a random message that got modded up to +5, and repost it here... that would be the ultimate in karma whoring.
-a
How to rationalize theft.
As other people have pointed out, the fine-structure-constant-is-changing work came out a year ago. The fine structure constant is a function of the speed of light, c, and the charge of the electron, e.
This particular article argues that e can't change much over time without causing inconsistencies, so they conclude that c must have been changing. No new data, no new support for the constant-is-changing theory. (And the original study was pretty damn flawed. This paper isn't bad.)
The discovery means faster-than-light travel, which is prohibited by the law of relativity, may one day be possible.
I think this is an error on the reporter's part. I don't see how this is at all related to the paper, unless the reporter thinks: "Speed of light changing therefore Einstein was wrong... Einstein was wrong, therefore we can travel faster than light."
If the speed of light was close to infinity, immediately after the Big Bang,
Again, a problem with the reporter here. "Close to infinity" means nothing. What this probably means is that the further back you travel in time, the bigger the speed of light was, and as you approach the Big Bang, the speed of light goes off to infinity. A physicist would say that the speed of light diverges, rather than saying it gets close to infinity.
The photons [...] interact with the electrons in the gas clouds, charged particles that orbit the nuclei of the metal atoms. This leaves a fingerprint on the light as it arrives on Earth, called the fine structure constant, Murphy explains.
This is actually close to correct, though it's misleading. The fine structure constant equals 2(pi)e^2/hc (if I recall correctly) where e is the charge of the electron, h is the Planck constant, and c is the speed of light. The value of that constant is related to the electromagnetic force, which, in turn, affects the spacing of the lines in an element's spectrum. Conversely, by looking at the spacing of the lines in elements' spectra, you can figure out the fine structure constant.
Let me guess: you didn't take her out to dinner, because you knew that if you did that (which you undoubtedly would), she would never go out with you again.
I got my Linux laptop at System76.
First of all, according to relativity there is no such thing as speed "in absolute terms". Second, all observers, regardless of motion, measure the same value for the speed of light. That is why time and distance will appear differently to two observers in relative motion.
Hey kids, there's only 5 days left 'til Yak Shaving Day!
This one came from my old chemistry teacher:
A philosopher, a mathematician and a physicist are at one end of a very, very long room. An observer tells them that there's a bottle of fine whisky on a table at the other end of the room, and that they can take as many leaps as they like to get to the other side and claim the prize but that every step must cover half the remaining distance, no more, no less.
The philosopher stands still, and contemplates whether or not the table and the whisky are there at all.
The mathematician does some quick thinking, and works out that he can never really reach the table as there will always be a finite distance, no matter how small, left to cover. He too stands his ground.
The physicist sets off across the room. He makes one, two, three, four jumps until he's withing arm's length of the table, shouts "that's close enough!" and grabs the bottle for himself.
(And after all that, what did I go on to do at university? Yep, astrophysics. Part astronomy, part physics, part mathematics and, at least with the options I took, part philosophy. No wonder I'm not a scientist by profession any more.)
"Accept that some days you are the pigeon, and some days you are the statue." - David Brent, Wernham Hogg