variable light speed

[Si W]

Hi All

I recently watch a documentary by Joao Magueijio (Cosmologist), he has proposed a theroy of variable light speed to get around the problem of cosmic inflation and the Horizon problem. He certainly rattled the cosmology community, enough to call him a heretic, Rebel Physicist, Charlatan, and the bad boy of cosmology, plus loads of other things, enough to side line him from the general cosmology community. At this point i whould like to say This is a Theory, Not a proven Fact. He proposed that the speed of light was a lot faster in the early universe than it is today. The consiques of this is it would completely disprove the theroy of relitivaty as the C in E=mc 2 is a constant even at the beginning of time, (Thats why he was called a Heretic as it would disprove Albert Einstein), imagin the ramifications if Joao was right. I do like his attitude towards the Cosmology community though, he said "if i'm wrong, so what, i've got a lot of other great idea's"

[Astro Imp]

I'm not in a position to say if he is right or wrong, but would say that a number of past thinkers were thought heretics - think Galileo, Copernicus, Giordano Bruno.

[Superewza]

Would it disprove the theory of relativity? Or would it just conclude that there was more E in the early universe?

Because that doesn't sound... urgh, forget it

[scogyrd]

Is this the documentary?

[Si W]

Is this the documentary?

Yep, that's the one, well worth watching.

[scogyrd]

Yep, that's the one, well worth watching.

Thanks, I'll check it out later.

[blackparticle]

I'll have to watch this. If we're going to have any meaningful chance at space travel then we require heretics as Einstein's theories have really limited us and confined humans to the solar system. At least in any physical sense and capability.

[George Jones]

I'll have to watch this. If we're going to have any meaningful chance at space travel then we require heretics as Einstein's theories have really limited us and confined humans to the solar system. At least in any physical sense and capability.

How so? According to Einstein, we can travel any arbitrarily large distance in any arbitrarily short time.

[blackparticle]

If c is constant then isn't the energy part of the equation prohibitive?

I am talking in a "real-world" humans in spaceships approach. I read somewhere that it would take approx 4,900,000,000 megatons of energy to propel the Space Shuttle to the speed of light.

According to the documentary if c is variable, or has been, then it may be possible to fudge the equation to allow for travel at speeds greater than 300,000 km/s.

It's either that or the infinite improbability drive.

[Ags]

Of course the speed of light varies - it goes slower in a slow scope than a fast scope! :-)

[George Jones]

If c is constant then isn't the energy part of the equation prohibitive?

Yes, even though time isn't (much of) a problem, energy certainly is.

It's either that or the infinite improbability drive.

Or wormholes (as in Contact)!

[Superewza]

Or wormholes (as in Contact)!

Or warp drive? If it's not possible to physically travel faster than light then all you have to do is figure out a way of getting from one point to another in less time than it would take light to

[Si W]

There is the Theory of warp speed, so in effect you can travel faster than the speed of light, the universe is itself expanding fast than the speed of light, by warping space in front and behind the space craft the space craft would effectively surf a wave, in effect the space craft is staying still a bit like a surfer, it's the wave that pushes him towards the beach, if there was no wave he would be stationary, on paper it looks good, but we don't have the technology to implement it, michio kaku once said "nothing can travel faster than the speed of light, which in itself is correct as space is nothing", that's why there is the horizon problem, because, if the light speed was constant at the beginning of time opposite side of the universe are unable to exchange information, and as long as the universe is expanding they never will, so that why the variable light speed theory was suggested to overcome this problem at the big bang.

[blackparticle]

Another way to fudge the equation is to invent the gravity drive which could change the relative mass of an object. That would still limit us to sub-light speed travel though.

[toml42]

I don't see why E=mc^2 couldn't hold in an earlier universe with a higher c. I suppose you'd have to sacrifice energy conservation instead then or something though...

I don't think there's a good reason to think c has ever varied, but we have to explore every avenue.

[RogerTheDodger]

The speed of light is variable depending on what it is travellling through, f'instance down a fibre optic cable it only runs at 200,000KM/sec.

I'll have to have a watch of that documentary, sounds interesting.

[toml42]

No, the speed of light is a constant. It only appears to vary in materials because it interacts with it

[Multi-Coated]

The speed of light is variable depending on what it is travellling through, f'instance down a fibre optic cable it only runs at 200,000KM/sec.

I'll have to have a watch of that documentary, sounds interesting.

Is this due to the fact that light is not traveling in a straight point to point line and is actually reflecting within the material , so therefore takes more "time" point to point which is not the same as speed ?

[RogerTheDodger]

No, the speed of light is a constant. It only appears to vary in materials because it interacts with it

Yes, the refractive index of the medium determines how much it slows down, but it does slow down all the same. c the constant is only defined as a constant in a vacuum.

[Superewza]

Is there such a thing as a vacuum?

[dc509]

I read his book a while back when it first came out: Faster Than The Speed Of Light: The Story of a Scientific Speculation: Amazon.co.uk: Joao Magueijo: Books

As interesting for his story about the reaction from his peers as for the theory itself.. Worth a read

d

[JulianO]

It's an interesting idea, but an awful lot of physics is built on the fact c is a constant. It's almost like saying 1+1 hasn't always equalled 2.

[Dave R]

Is there such a thing as a vacuum?

Yes, 'er indoors has got one.

Re the VSL thing, there was a paper published a few years ago that ruled out any change in C over the last century, explained in this blog post.

[RogerTheDodger]

I'm happy with the NIST definition of the meter, which also confirms the speed of light in a vacuum Base unit definitions: Meter I'm sure they also have a definition of a vacuum, but cba to look for it

[ColB]

It's an interesting idea, but an awful lot of physics is built on the fact c is a constant. It's almost like saying 1+1 hasn't always equalled 2.

I disagree, 1+1 = 2 is fairly intuitiive, regardless of your culture, c the speed of light in a vacuum is constant, regardless of your frame of reference, is that intuitive? nope. We've been told that and it fits our current models and we can nod our heads and say it is as obvious as '1+1=2', but i would suspect there is a lot more to it than that.