[Flipside]

http://www.bbc.co.uk/news/science-environment-26605974

As I understand this, there is certain behavior in very distant light sources that could only be attributed to an incredibly fast level of expansion in the first instants of the universe existing, something that had been theorized (since it was the only way deep space could look as it did) but very little solid evidence existed.

[watsisname]

Finally! This is really big news for cosmology.

Basically we're looking at the Cosmic Microwave Background (CMB), a relic radiation field from when the universe was ~300,000 years old and the first atoms formed.  Inflation is a theoretical era which preceded that -- it happened within a tiny fraction of a second after the Big Bang, and lasted just as briefly, but during that instant the size of the universe grew exponentially, doubling in size some ridiculous number of times. 

Inflation was hypothesized as a solution to a number of weird observations about the universe, like why is the mass density so close to the critical density?  If it is correct, then it should have left behind imprints in the CMB due to gravi[t]ational waves, which would show up as certain polarization modes.  Apparently this evidence has now been found.

I didn't think this would come from surface observations though -- I was expecting it out of Planck data.  I'll have to do some reading on the team working on it.

edit:  graviational?  Mmm, gravioli.

[Mongoose]

So if I'm reading this right, these results not only serve as a smoking gun for inflation, but also provide direct evidence of heretofore-unobserved gravitational waves?  Hot damn.

[666maslo666]

So if I'm reading this right, these results not only serve as a smoking gun for inflation, but also provide direct evidence of heretofore-unobserved gravitational waves?  Hot damn.

And on top of that, this is an imprint of processes happening at 12 orders of magnitude higher energy than what is studied at the LHC. The implications not only for cosmology, but for high energy particle physics and "theories of everything" are potentialy huge.

[watsisname]

So if I'm reading this right, these results not only serve as a smoking gun for inflation, but also provide direct evidence of heretofore-unobserved gravitational waves?  Hot damn.

Yup!

There is also very powerful indirect evidence for gravitational waves from the orbits of binary neutron stars -- they should slowly spiral in at a particular rate due to gravitational wave emission, which carries off some of their orbital energy.  Observed rates are in very good agreement with the theoretical prediction.

So gravity waves are kind of like black holes at the moment -- good reasons to think that they exist, and powerful evidence that they do, but it's damn hard to see them directly.

[Flipside]

A random thought occurred to me, I have no clue what the answer is, but would this expansion happen at close to the speed of light? Would those rules even exist at that point of the Universe' life? I've read before that some constants may not be as 'constant' in deep time as we think.

[General Battuta]

Inflation actually occurs much, much faster than the speed of light, but that's kind of a misleading way of thinking about it. Nothing is moving relative to anything else, space itself is expanding, and there's still no way for information to cross a given volume of space faster than light. So there's no need for the value of C to be any different.

[Luis Dias]

João Magueijo studied the idea that c could have altered through time. The models that have come up with this idea in mind do not work well in comparison with the standard ones.

[Flipside]

I think I understand that, it's not really a question of 'speed' because speed is a factor of distance over time, if both are expanding at the same rate, it would kind of make sense that the term would be irrelevant with regards to this.

[Luis Dias]

well if t is getting faster at the same "speed" that c is getting slower then it all cancels out and you might well ask what that even meant (since t is canonically and theoretically measured against c and vice-versa).

[Flipside]

What I mean is, it's like asking if 4/2 is the same as 8/4 or 16/8?

[Luis Dias]

exactly.

[General Battuta]

I don't think that metaphor quite works and I would explain why but alas crunch calls.

[An4ximandros]

Mmm... GameDev. Sweet on the outside, Crunchy on the inside...

[Luis Dias]

everyday is crunch time. i don't pity him though when he says he gets to work at 9 am and only leaves at 1 am. I've left my office at 6 am many many times.

[General Battuta]

I think inflation is much more interesting than work hour dickwaving

[666maslo666]

It doesnt make much sense to talk about whether inflation was faster than the speed of light or not, because it is metric expansion of space. Which means that any two points recede from each other, and their relative speed always depends linearly on how far away they are from each other, speed of light be damned. So there will always be some distance where two points move away from each other at superluminal speeds.

However it does make sense to ask how far two points have to be in order to recede faster than light. I guess for Hubble expansion of the universe it is many billions of light years. I read somewhere that during inflation the expansion was so powerful that this distance was on the order of Planck length.

[Phantom Hoover]

The distance at which the expansion exceeds c is precisely the radius of the Hubble volume: 14 billion light-years.

[Luis Dias]

Interesting. I thought 13.7 billion years was the time distance between us and the back radiation, not the distance towards the event horizon of our region. I also wasn't aware those are the exact same (we even know they will be extremely different in the future, when future astronomers won't even be able to watch other galaxies). Are they the same as of now?

[Phantom Hoover]

The Hubble radius isn't the same as that of the observable universe, though — the latter is about three times larger, because of expansion-related screwiness I can visualise but not explain.