Last Week's Announcement About Gravitational Waves and Inflation May Be Wrong

KentuckyFC (1144503) writes "If you've been living under a stone, you might not have heard last week's announcement that astrophysicists from the BICEP2 experiment have found the first evidence of two extraordinary things. The first is primordial gravitational waves--ripples in spacetime from the very first moments after the Big Bang. The second is that these waves are evidence of inflation, the theory that the universe expanded rapidly, by twenty orders of magnitude in the blink of an eye after the Big Bang. But that can only be possible if the gravitational waves formed before inflation occurred. Now critics have begun to mutter that the waves might have formed later and so provide no evidence of inflation. The new thinking is that as the universe cooled down after inflation, various phase changes occurred in the Universe which generated the laws of physics we see today. These phase changes would have been violent events that generated their own ripples in space time, which would look very much like the primordial gravitational waves that the BICEP2 team claims to have found. So the BICEP2 team must rule out this possibility before they can claim evidence of inflation. But the critics say the data does not yet allow this to be done. That doesn't mean inflation didn't occur. Indeed, the critics say this is still the most likely explanation. But until the phase change possibility is ruled out, the result must be considered ambiguous. So put the champagne back in the fridge."

Comments

No confirmation

[cciechad]

Um also this is one experiment with no confirmation yet. No one else has repeated the results as of yet so how about putting the champagne away until another group of experimenters confirms?

Re:No confirmation

[i kan reed]

Oh yeah, because controlled experiments haven't established any of the laws being applied, right?

Are you a moron who'd say "we don't know what gravity on Jupiter is like because we haven't experimented there"?

No? Then why are you a moron who says "Carbon dioxide doesn't retain heat on a planetary scale because our experiments that clearly establish that mechanism have only been on a small scale"?

Observational evidence is evidence, and controlled experiments are only necessary for the process of establishing and challenging the laws that we use to assess the real world.

Phase changes

[P-niiice]

I think phase changes on a universal scale is an amazing thing to ponder.

Re:Phase changes

[ObsessiveMathsFreak]

Absolutely. Regardless of whether the results confirm or are consistent with the theory of Inflation, the every existence of coherant structure the scale of the universe itself is an amazing result. By default, there is no reason to expect any structure whatsoever at the highest cosmic sale. (I would argue that up to now this, there was essentially no struture to the CMB)

Yet here we have "waves" of polarisation over a gigantic region of the night sky. The Universe has uniform strutures at the most enormous scales. It's a deep and awesome result that must be addressed, by inflation or whatever other theory we can propose for it.

Creationisticism

[dingleberrie]

This aspect of the story is great as an example of science.
It seems stubborn to hold onto a single interpretation of evidence during pursuit a theory, including the origin of the universe.
Science is the willingness to relegate that evidence to be less significant than what some people want it to be.
When you won't relegate the evidence, then you are practicing faith (in the evidence) instead of science.

Re:Jumping the gun

[MightyMartian]

The media hyped this up. The BICEP2 team did nothing wrong.

Re:Jumping the gun

[Baloroth]

Over the last... long while now scientists have developed a bad habit of getting really excited and presenting findings as concrete, only to get shot down. Besides, doesn't an experiment have to be repeated for the results to be confirmed? Regardless, if the alternate interpretation proves true, I find it no less significant.

It's customary in science to present your findings exactly as they are, with the statistical certainty associated with the findings. They never said their results were confirmed or "concrete", they said their findings confirmed several other theories and that they were highly certain of the results given the known sources of error and the model they were using. You can always come up with other theories that would also fit the observational data: heck, half the point of publishing your data is so the scientific community can look at it and see if you did something wrong, or if there are other interpretations that fit the data better.