Sorry Phil, I just beat you to the Ig Nobel Prize**!

*Okay, anyone not realizing it… #3 is a joke.
**Follow-up to #22 Chris’ joke.

Wasn’t the pay-off the actual discovery of accelerating expansion? It’s probably nice to get an award and some money, but I’d hope most scientists are driven by a desire for knowledge, not prizes.

Maybe these two links will help with some of the confusion: http://curious.astro.cornell.edu/question.php?number=274

This is a very good question which is not at all easy to give a satisfactory answer to! The first time I tried to write an answer to this, we got so many follow-up questions from people who were still confused that I decided to try to answer it again, this time much more comprehensively. The long explanation is below. However, if you just want a short answer, I’ll say this: if the universe is infinitely big, then the answer is simply that it isn’t expanding into anything; instead, what is happening is that every region of the universe, every distance between every pair of galaxies, is being “stretched”, but the overall size of the universe was infinitely big to begin with and continues to remain infinitely big as time goes on, so the universe’s size doesn’t change, and therefore it doesn’t expand into anything. If, on the other hand, the universe has a finite size, then it may be legitimate to claim that there is something “outside of the universe” that the universe is expanding into. However, because we are, by definition, stuck within the space that makes up our universe and have no way to observe anything outside of it, this ceases to be a question that can be answered scientifically. So the answer in that case is that we really don’t know what, if anything, the universe is expanding into.

Or http://www.physicsforums.com/showthread.php?t=179053

http://www.abc.net.au/news/2011-10-04/australian-astrophysicist-wins-nobel-prize/3209216

&

http://www.abc.net.au/lateline/content/2011/s3332319.htm

Plus this :

http://www.abc.net.au/lateline/content/2011/s3332323.htm

via Lateline ion the new ALMA array that featured onthe same show. Great news!

I know “dark energy” is cool, but unless you have evidence this is NOT the cosmological constant, there is no reason to promote new (fundamental?) fields to solve the “mystery” of this problem – Occam’s razor.

“Cosmological constant” is also just a fancy term for “we don’t know”, only one that smuggles in an additional unfounded assumption – namely that it’s constant. We don’t know if it’s constant or not. All we know is that the rate of expansion currently seems to be increasing, when viewed from here. We have absolutely no idea why, so it doesn’t really make much difference what name you use to paper over that absence of knowledge – although it’s probably better if it doesn’t include any extra assumptions about the thing that we don’t know anything about.

Adam and I were both grad students at the time; after I got my PhD I went to work on a different Hubble project, and Adam stayed with the team, cracked the supernova code, and now has a Nobel Prize.

I suspect that was the right move for him.

Hah! But does he have his own TV show? I think not!

Exactly. As Sean Carroll pointed out, essentially everything has energy and lots of things are dark. “Dark energy” is just a stupid “marketing” term which is all style and no substance, all presentation and no content, something from a spin doctor or an add agency. Scientists should promote understanding the universe, not trying to sound cool.

As to whether we need a deeper understanding of “what” the cosmological constant “is”: do we need a deeper understanding of what gravitation “is”, i.e. “why” it exists, or is it enough that GR describes it well?

Nobel originally specified “invention or discovery”, so there is no problem that all the details are not understood. In fact, discoveries which are difficult to understand are more interesting.

Note also that Hubble came to believe that the expansion of the universe was not real, though of course he discovered the relation between apparent magnitude and redshift.

I know “dark energy” is cool, but unless you have evidence this is NOT the cosmological constant, there is no reason to promote new (fundamental?) fields to solve the “mystery” of this problem – Occam’s razor.

Are you a scientist, or do you work in PR?

I’m not saying that it is the cosmological constant, but most of the arguments against it are theoretical problams rather than empircal.

By the way, if you enjoyed the beautiful Oddie telescope when you were at Mt. Stromlo, the telescope (and I’m told the mount and clockwork drive) had been faithfully reproduced. Although the loss of the then rarely-used 74-inch telescope and the 50-inch Melbourne (among others) was quite tragic, the Oddie was just such a beautiful work of art and everyone loved it – I can’t wait for Oddie-II to go into a dome and see it in action.

Edwin Hubble found that the universe was expanding.
Hubble Telescope found the Universe expansion rate is accelerating.

Yeah, Hubble recognized that the universe was expanding, but not that it was accelerating. That’s why, up until the observations that resulted in this prize, it was an open question whether the fate of the universe was to eventually collapse, reach a steady state, or to expand forever, depending on the amount of mass-energy in the universe and thus its overall geometry. However even in the last case the rate of expansion was still expected to decrease, asymptotically approaching zero.