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Wednesday, July 09, 2014

Dust in the Cosmic Wind

In the middle of writing my post Creation Myth, big news was announced regarding the Big Bang Theory:
On March 17th researchers from the Harvard-Smithsonian Centre for Astrophysics, led by John Kovac, held a press conference at which they announced that they had discovered interesting patterns in the cosmic microwave background, a type of weak radiation left over from the universe’s earliest moments. They said they had spotted the signatures of primordial gravitational waves, ripples in space formed just after the Big Bang. 
The existence of such waves would give strong support for the theory of inflation, which holds that the early universe underwent a brief burst of faster-than-light expansion. Inflation was put forward in the 1980s by theorists as a way to resolve various knotty problems with the standard theory of the Big Bang. But although it is widely assumed to be true, direct evidence that it happened had been lacking.
Because of that announcement, I almost didn't bother publishing my post, but since my post was a light and humorous piece (filed under "chocolate" and "humor"), I decided to publish it anyway, even though the Big Bang suddenly had yet more compelling observations matching the theory.

And those observations may still be correct.  However, the claim was, according to The Economist, possibly a little premature:
This concluded that Dr Kovac’s data, which came from an Antarctic telescope called BICEP-2, may well have been contaminated by space dust, and that the purported gravitational waves may be much weaker than the team first claimed—if they exist at all.
Fortunately, the controversy should be at least partly resolved soon and I will no doubt report on it when the new data becomes available:
New data expected within weeks from the Planck satellite of the European Space Agency and other experiments should help clarify the situation, the authors say.
In other words, how much dust, if any, impaired the BICEP-2 observations? It must be a bit of a roller coaster for those working in the dusty field of the Big Bang Theory. One picosecond, compelling evidence is presented regarding inflation of the universe, the next picosecond the evidence deflates, and in the near future it might inflate yet again.

Not that it really matters.  Just because a theory can explain what's observed, doesn't mean that the theory does explain what's observed.  Turning "can" into "does" requires a leap of faith and there's no reason the Big Bang Theory faith would've been shaken for its adherents by this bit of dust in the cosmic wind.

4 comments:

Clovis e Adri said...

Well, thanks for the provocation, that's a good one.

A few points:

1) It's been always that roller coaster. It is part of the fun in science. Up to 1998 we did not even know the Universe is accelerating its expansion again, and upon learning that our models changed once more.


2) The Big Bang is not really into question here. It is Inflation which is.
What we call the "Big Bang theory" is basicaly the realization that the universe was much smaller and hotter in past, more so when more into the past you look. We have very good confidence in that overall picture, substantiated by a trove of observations.


3) Inflation, on the other hand, is a theory about how the universe could have evolved up to the part we have confidence about (less than its first second). It is, and always has been, a more speculative matter, and the popular notion that it is somehow "proven" by science is a reflex of how our science popularization mechanisms are too addicted to hypes.

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Turning "can" into "does" requires a leap of faith and there's no reason the Big Bang Theory faith would've been shaken for its adherents by this bit of dust in the cosmic wind.
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And here is where you go wrong, assuming you've meant "Inflation-based Big Bang theory" (since, as mentioned above, the "inflation" part is the only one touched here).

Believe me, though inflation looks a strong contender, it is far from being faith. I can point to you good papers, even from the founders of the inflationary scenario, that seriously question it all.

Bret said...

Clovis wrote: "...thanks for the provocation..."

You're welcome. The fact that you're both a physicist and a reader did make this post a little more fun.

Clovis wrote: "The Big Bang is not really into question here."

Hmmm. Well, perhaps I don't know what the Big Bang is. I've only really ever read popular descriptions like this one:

"Moreover, the Big Bang model suggests that at some moment all matter in the universe was contained in a single point, which is considered the beginning of the universe."

So we have a singularity, then sometime later (13+ billion years) we have what we have now. Don't we need something like inflation to get from there to here for the Big Bang to be viable?

Clovis wrote: "...though inflation looks a strong contender, it is far from being faith."

You're speaking for yourself, you faithless cynic. :-)

I have friends for whom Inflation-based Big Bang is indeed Truth and therefore Faith (though they'll vociferously deny the Faith part - it's only Truth to them). I think you'll find, if you look carefully, that many in the media and many science teachers also have the Faith.

Peter said...

there's no reason the Big Bang Theory faith would've been shaken for its adherents by this bit of dust in the cosmic wind

"...and I will show you fear in a handful of dust."

--T.S. Eliot.

Clovis e Adri said...

Bret,

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So we have a singularity, then sometime later (13+ billion years) we have what we have now. Don't we need something like inflation to get from there to here for the Big Bang to be viable?
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Not really. Inflation plays a role not to bridge the singularity with us 13 billion years later, but only to bridge the singularity with aprox. the first 10^-30 seconds or our history. As I said, it is a very speculative matter (such tiny time scale!), but one with many implications. (I will not enter in details, but the singularity itself is another thing beyond our understanding too.)

From those 10^-30s to the present 4.3 x 10^17s, which is the time scale of standard big bang theory, our knowledge gets a lot more solid, requiring much less faith.

If you want to be absolutely conservative, by what I mean to depend the least of theoretical considerations and draws the most of pure observations, our most remote direct measurements of the universe past goes up to when it was 300.000 years old. That's the so called surface of last scattering (when light and matter were finally completely separated). The radiation then "liberated" is precisely what we now call the cosmic microwave background, measurable even from antennas you can build at your own home.

So up to that Universe age, your faith is reduced to measuring some microwave radiation that pretty much anyone can do - doesn't look to be a lot of faith then, does it?


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You're speaking for yourself, you faithless cynic.
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I am speaking for a lot of people. If you can access it, I think you'll have fun reading this SciAm article:

http://www.scientificamerican.com/article/the-inflation-summer/

The author is one of the leading proponents of inflationary scenarios, yet nowadays he's one of the most skeptic about it.

Inflation suffers from a very basic problem that is at the heart of our scientific method: once you create a theory to solve a set of problems, that theory itself leads to another set of more basic problems. Usually, the tradeoff is good and you end up understanding more after that anyway. In the Inflation case that tradeoff, many people would say, doesn't really pay enough.