variable light speed

[Superewza]

But 1+1=10?

[blackparticle]

Going back to the documentary. How soon did matter / anti-matter form after the big bang?

Is it possible the expansion of the universe started slow enough for information to be exchanged and then boom.. matter / anti-matter explosions provide the energy to rapidly expand the universe... possibly leaving vast spaces of nothing in between?

This leads to the question does anti-matter have anti-mass and anti-gravity? If it does, then wouldn't the existence of black holes be the thing that lumped matter together.

And where are all the "anti-black holes" ?

[JulianO]

Going back to the documentary. How soon did matter / anti-matter form after the big bang?

Depends what you mean by matter in some respects. Protons, neutrons and electrons about 1 second after the big bang. Atoms as such not for about 300,000 years when it was cool enough for electrons to stick to nuclei.

Is it possible the expansion of the universe started slow enough for information to be exchanged and then boom.. matter / anti-matter explosions provide the energy to rapidly expand the universe... possibly leaving vast spaces of nothing in between?

That's basically what inflation theory suggests. Everything was very close, then suddenly expanded at an unimaginable rate for a while. From the size of a proton to the size of (well I've heard a football, or the solar system) but very very much bigger anyway. It is a staggering expansion whatever way you look at it. There are a few problems with inflation, and other models try and work around it.

This leads to the question does anti-matter have anti-mass and anti-gravity? If it does, then wouldn't the existence of black holes be the thing that lumped matter together.

No - anti matter has mass, the same as its partner. It also has positive gravity just the same, normally the only way to distinguish it is a difference in charge, and the fact it blows up when it meets its anti particle.

And where are all the "anti-black holes" ?

There aren't any. White holes have been discussed, but I think they're speculative.

[Adamski]

Hi si. I have posted a related question this morning. While watching a steven hawking program it is said that at the age of 10 minutes the universe was many light years across. How can this be? Surely when 10 minutes old it should only be 10 light minutes across.

[JulianO]

Hi si. I have posted a related question this morning. While watching a steven hawking program it is said that at the age of 10 minutes the universe was many light years across. How can this be? Surely when 10 minutes old it should only be 10 light minutes across.

That's inflation for you :-)

[jamespels]

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.

Not sure about this (though my understanding is very limited). I read an article in New Scientist a year or so back about a state of matter that actually slows light down. This is definitely due to some sort of interation but not diffraction, etc. I don't know if it's the same thing or not but this article describes something similar:

Physicists Slow Speed of Light

Again, I might be talking utter rubbish but variance in c doesn't seem sucha biggie to me. We had an entire era at the start of the universe we refer to as "inflation" that we really have very little grasp of - various universal "funadamentals" were set / created during that time (e.g. strong neclear force / electorweak force) so is it that hard to believe that c could have changed in this time?

Way over my head in terms of what did / might have happened but when we are dealing with theories are are barely understood, let alone proven, I don't think we can take too much as gospel.

[Earl]

But 1+1=10?

10 types of people understand binary those that do and those that dont.

always has made me chuckle that one.

[Psychobilly]

10 types of people understand binary those that do and those that dont.

always has made me chuckle that one.

and 0.1 of them understand binary fractions and the other 0.1 don't...

[ollypenrice]

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.

Copernicus wasn't thought a heretic in his own lifetime. His church superiors were always trying to persuade him to publish, not the reverse. The bother was caused by Gallileo getting too big for his boots in the eyes of the Church. Indeed Copernicus's book was only suspended at the time of the Gallileo spat. It could have been banned. This part of the story is often mis-told.

Although the final version of his theory (De Revolutionibus) was published on his death bed, Copernicus had circulated his heliocentric manifesto as the Commentariolus when a young man nearly thirty years earlier. This did not land him in any difficulty with his superiors, many of whom had seen it.

Olly

[JulianO]

Not sure about this (though my understanding is very limited). I read an article in New Scientist a year or so back about a state of matter that actually slows light down. This is definitely due to some sort of interation but not diffraction, etc. I don't know if it's the same thing or not but this article describes something similar:

Physicists Slow Speed of Light

Well - its difficult to tell if light has been slowed down, or its merely getting absorbed and re-emited. It may go at c between atoms, but then hang around in an excited state in the electron before being passed on. Do this enough times, and it appears to be going very slowly, a but like a man going through a town on a bus, but calling in for a swift half at every pub. The bus goes at constant speed, but the man is busy in between!

Again, I might be talking utter rubbish but variance in c doesn't seem sucha biggie to me. We had an entire era at the start of the universe we refer to as "inflation" that we really have very little grasp of - various universal "funadamentals" were set / created during that time (e.g. strong neclear force / electorweak force) so is it that hard to believe that c could have changed in this time?

I believe the current thinking is that these "constants" were set at the birth of the universe, so well before inflation and other things (if you can talk of 10^-38 s in terms of well before!)

All the reactions that proceed after the planck interval rely pretty much on known physics, so use the constants as they are. Of course no one was there, so its mostly theory and the CMB that are used to back it up.

You're right though - I wouldn't bet much on any of these theories being completely correct.

[michael.h.f.wilkinson]

I have had a look at Google Scholar and Joao Magueijo has published in many respectable journals (still does) and has been cited a lot. He has worked on several different ways of varying various constants such as the electric charge and fine structure constant. It looks like valid theoretical research that has not been badly received (violent disagreement is common in science, it's what keeps things moving along). I get the impression that he is generally considered less of a heretic than he himself claims to be. And even if he is considered a heretic, science tends to treat them differently. If I review a paper by someone I think is talking out of unsuitable orifices, I cannot just state: this is ludicrous, I have to give sound arguments, or the editor of the journal may not take me seriously.

Heretics are very useful to science. Especially later in his career, Fred Hoyle had such a role in astronomy: proposing theories which rile a number of people, but cannot be dismissed off-hand. A lot of good science has been done just to prove Hoyle wrong. In that slightly odd way, Hoyle has been very useful to the science of astronomy (apart from other more direct contributions).

[Si W]

Hi si. I have posted a related question this morning. While watching a steven hawking program it is said that at the age of 10 minutes the universe was many light years across. How can this be? Surely when 10 minutes old it should only be 10 light minutes across.

And this is the basis of the Horizon problem, how can information be exchange from one side if the young universe to the other or even present day?, look at it like this, if you look a a distant Galaxy lets say 10 billion light years away for sake of argument, the light your are seeing has to 10 billion years to get to us, the you turn to the opposite diriection and see another galaxy at the same distance, from any of these galaxies you could not see the other as they are 20 billion light years away and the universe is only 13.75 ± 0.11 billion years old. So as Joao has suggested for this information to be exchanged the speed of light must of been faster.

[Macavity]

Is there any reason information need be exchanged, beyond the time of cosmic inflation. But it triggered a silly idea of a (slow!) "semaphore" system to relay information between the disparate parts.

"Constants aren't, variables should..." - Or sumpin?

At one time I was genuinely stuck by the (dimensionless) beauty of:

Fine-structure constant - Wikipedia, the free encyclopedia

I see they're STILL (comfortingly!) measuring and philosophising...

And the VISIBLE beauty of:

Cherenkov radiation - Wikipedia, the free encyclopedia

==> Phase velocity - Wikipedia, the free encyclopedia (!)

But, so many gaps in my knowledge! <sigh>

[Si W]

The current theories, no information can travel faster than light. Information means any sort of physical interaction. Heat will naturally move from a hotter area to cooler one’s, and in physics/cosmology this is just one example of information exchange. Two galaxies for instance cannot have shared any sort of information, they are not in contact. So you would expect that their physical properties would be different, and more generally, that the universe as a whole would have varying properties in different parts. Thats the Horizan problem.

Edit: look at it like this, you have a spiral galaxy 10 billion light year in one direct, and another spiral galaxy 10 billion light years in the other, they look similar in structure, yet there distance is greater than the age of the universe, but are observable horizon is only 13.7 billion light years i all directions, we can see them both, but from there prostective they can only see us but not each other.

[Superewza]

No information can travel faster than light? What about through Quantum Entanglement? If you moved each member of the pair far enough away from each other that the time taken to monitor a change would be less than the time taken for light to get between the two points... or is that just 'effectively' faster than light, not physically? Like warping space is effective FTL travel.

[Si W]

No information can travel faster than light, but you do make a good point with Quantum mechanics, a particle can exist in two place's at the same time, so information could be exchanged at the Quantum level, only problem is Quantum mechanics and General relativity dont work together.

[toml42]

The many worlds interpretation solves that apparent paradox.

In that interpretation you don't have to worry about whether any information was transmitted, you're just finding out what universe 'you' ended up in

[Si W]

The many worlds interpretation solves that apparent paradox.

In that interpretation you don't have to worry about whether any information was transmitted, you're just finding out what universe 'you' ended up in

They can also exist in are universe, take the 2 slit experiment, the same photon can exist in two place's in are universe at the same time .

[michael.h.f.wilkinson]

They can also exist in are universe, take the 2 slit experiment, the same photon can exist in two place's in are universe at the same time .

Or it exists at neither. Or it is at one location but in such an unpredictable way that you cannot determine it without disrupting the interference pattern (see David Bohm's take on quantummechanics).

[yeti monster]

Perhaps it is the speed of time that is limiting our space exploration?