Accelerating universe expansion discovery snags Nobel Prize
A discovery first published in 1998 has won the Nobel Prize for Physics for three astronomers, including Brian Schmidt of the Australian National University. Competing with Saul Perlmutter of the University of California and the Lawrence Berkeley National Laboratory, and working with Adam Riess of the Johns Hopkins University …
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Bloody clever
I always think its funny how the greatest discoveries so often have a particularly beautiful but logical simplicity to them - the simplicity at least being very much in hindsight. It's that ability to cut through the chaff, peppered with a little intuition and good fortune, that separates the great from the merely very, very good.
Can someone remind me why scientists are so often poorly paid, but bankers are too often paid the equivalent to the budgets of important scientific projects?
Hats off to you gents for shining a little more light into the dark corners.
Why Perlmutter? He only confirmed the findings of the Aussie and his team. Perlmutter had no idea of the acceleration, ----- his studies concerned the slowing down of the universe. Aussie and co only requested him to look in his data to confirm their findings. Perlmutter came on strong to the media claiming to be part of the discovery. He may have had the data but he sure didn't know it. According to the records it was a race between two teams and the Aussie folks won, so why does a self appointed leader get the lion's share of the prize? It's a bit thick I say, ---- It's like Michelson and Morely having a joint claim on Einstein's fame since they started the study.
What if They're Wrong?
What if the universe isn't homogenous and we are in a localized "current" that only makes the universe look like it's expanding, requiring "dark energy" to make all the pieces fit? Do they have to give the award and money back?
given the daft way it was phrased
probably. it's a pity, it was a profound discovery that at its most innocuous revolutionised cosmology, and at its most pervasive could even revolutionise high-energy and fundamental physics. as such it's surely worthy of a nobel prize. unfortunately the announcement was phrased so poorly that it locked it straight into the standard model, which is certainly not immune to criticism.
"What if the universe isn't homogenous"
The problem is, we will never know.
....
Yes, yes we will. We already know it's not homogeneous. The chair I'm sitting on is a pretty whacking great inhomogeneity. The question is whether it's homogeneous on average, and future large-scale surveys (such as the ongoing LOFAR, the just-approved EUCLID and the hope-to-God-it-will-happen SKA) should be able to prove large enough scales to find where the universe becomes homogeneous, or not. People are already teasing hints out of the SDSS that we're beginning to see homogeneity in the matter power spectrum. (They're working out of hope, I suspect, since the errors are pretty big on those scales, but it *is* indicative, even if if a particle physicist would laugh himself hoarse at the kind of errors we're talking about.)
Congratulations to a fellow Canberran!
(although I still think the universe will eventually reach a state of equilibrium where it is neither expanding nor contracting: the symmetry of this just works for me)
It's quite interesting how people are always keen to talk about two competing teams. Politics, sports, science, it always has to be two competing teams. There's something odd in human nature, it seems.
http://de.arxiv.org/abs/astro-ph/9804065
Names on that paper, posted to the arxiv a month before the Riess et al "bombshell" which wasn't quite a bombshell: Riess, Kirschner (part of the Riess/Schmidt collaboration) and... Perlmutter. (Of the other two authors, Filippenko co-authored the Riess et al paper, while Nugent co-authored the Perlmutter et al).
Not arguing with your point although you're stating it strong - don't really know enough of the details, though I've seen both Kirschner and Riess talking about things then (and there's no evident rancour), and Perlmutter et al *was* posted to the arxiv in December while Riess et al was posted in May.
Another interesting thing to note is that people had for a long time been arguing that the universe should be dominated by a cosmological constant - see the note at the end of the abstract to http://de.arxiv.org/abs/astro-ph/9608192 (authors including Perlmutter and Filippenko), "The results for Omega_Lambda-versus-Omega_M are inconsistent with Lambda-dominated, low density, flat cosmologies that have been proposed to reconcile the ages of globular cluster stars with higher Hubble constant values." Accelerating universes have been touted since the late 80s, and perhaps earlier.
Still, the Riess et al and Perlmutter papers were persuasive direct observational evidence, while the previous suggestions were always a step or two away from observations. My only issue is not the award or to whom it was given - although the restriction to three scientists is a bit harsh on other members of both teams - but the phrasing of the announcement, which gives a staggeringly unscientific lustre to things. They awarded it for "the discovery of the acceleration of the universe", which implies that the authors discovered that the universe was accelerating. This cannot be proven. What the authors discovered was that distant supernovae are fainter than expected and that this cannot be accounted for by dust extinction, and that *when interpreted naively through a Robertson-Walker model the scale factor is accelerating*. There are other ways to get those supernovae to be fainter, and there are many questions about exactly how seriously we should take a model that is - and no offense meant to my colleagues here - pure phenomenology. Perhaps the universe *is* accelerating, but the question remains very open, but you wouldn't know that listening to the Nobel committee. For such a respected institution to declare to the public as true something that cannot be demonstrated and remains somewhat controversial is... impressive.
If only they'd awarded it for "the discovery of the apparent acceleration of the universe". I don't think any cosmologist would have had a problem with that. It's one small word but it makes one hell of a difference.
Rant over.
That was a reply to hybrid
Not sure why it came here but user incompetence can never be discounted.
"For such a respected institution to declare to the public as true something that cannot be demonstrated and remains somewhat controversial is... impressive"
Isn't this the same institution that gave Obama the Peace Prize?
The Nobel organization
Technically, no. The Nobel Peace Prize is handed out in Oslo, Norway and not in Sweden.
A group of old washed out politicians are put into a dark pit and asked to fight it out. The winner gets to decide who wins the peace prize.
The Nobel Peace Prize committee do not consult with any professionals, nor do they publish any papers with detailed information on why they picked the winner.
The other Nobel prize winners are mostly judged by their peers, and it is my understanding that they publish a thorough paper explaining why they picked that winner.
The peace prize, quite frankly, is currently a joke. (I realize your smiley means you probably know this already, but I just wanted to emphasize that there are some vital differences between the Peace Prize and the other Nobel awards)
nb:
"Still, the Riess et al and Perlmutter papers were persuasive direct observational evidence"
And this is what counts: the Nobel Prizes (at least in Physics) /tend/ to be awarded for practical and/or experimental results, rather than theoretical breakthroughs or concepts.
Oh, I totally agree. Though in the past (until the 1980s) they were quite keen on presenting prizes to the people who *made* a theory once it was shown experimentally, and then maybe reward the experimentalists a bit later. Otherwise people like Feynman, Schwinger and Tomonaga, or Chandrasekhar, or Salam and Weinberg would never have won prizes. This doesn't seem to happen in cosmology, alas, which is evidently why Penzias and Wilson got a prize but Peebles didn't. That may be that it's not fundamental physics, or testable in a lab... except that Penzias and Wilson can get a prize but Peebles can't. Hmm.
But anyway, I agree. The main thrust of my rant was that they've misrepresented the science, not that they overstated the importance of the discovery.
Dark Energy ?
Why invent new stuff just to explain things ? Surely the simplest explanation is usually correct.
I would postulate that benevolent noodly appendages are pushing those nasty novas away from His chosen people.
Keeping that 2005 vibe going...
it probaby best
to consider "dark energy" as a sort of placeholder for a better explanation. It make be turn out to be some kind of exotic (or perhaps even unexpectedly dull) energy or matter inhabiting a conventional General-Relativistic universe, or it might be that GR needs fixing and that "dark energy" is merely a symptom of some theoretical failing.
"Dark energy" might or might not be a good name for the answer, whatever it is. But the discrepancy between expected behaviour and measured behaviour has to be called something, and ATM it looks a bit like there's some energy there we can't see. Hence "dark energy".
hmmm...
So what is the force driving the acceleration?
Or is it attraction to something "outside" the universe?
As to the missing 70% mass of the universe? that's easy - sleeping cats.
A cat while awake is easily lifted. Once the cat is asleep, on top of the duvet behind your knees, the cat has become an immovable object hence its mass must have increased by several orders of magnitude.
Surely when the cat is asleep you have to consider its rest mass instead?
Red-shift Does Not Necessarily Indicate Velocity - Hence No Expansion At All?
Essentially it appears that all universe expansion theories are predicated on the assumption also used here that "red-shift indicates velocity". Not necessarily! For example in galaxy NGC 4319, there is a quasar ejected from its parent galaxy that has a very different red shift from the galaxy itself. http://lempel.pagesperso-orange.fr/red_shift_NGC_4319_uk.htm. If both were accelerating away from us, the red shift should be the same.
Anyway, clearly red-shift does not necessarily equate to accleration or velocity, so something else is going on - if this were to disprove expansion of the universe, then a lot of scientists having invested zillions in research into this would be a bit embarrassed - or hopefully open minded enough to digest new data, facts and observations dispassionately and adapt their theories accordingly. (But odd how photo press releases were issued of this phenomenon with the 'bridge' of material between the galaxy and quasar removed).
Not sure why he got downvoted - he's correct. Redshift isn't necessarily due to acceleration. Wave particle duality says so.
You can think of redshift in the classical sense of the wavelength being "stretched" by the acceleration, however wavelength in photons is related to their energy. Drop the energy and you increase the wavelength (i.e. get redshift).
If you have the photons absorbed and re-emitted at a lower energy you get redshift, it's just not acceleration based.
Personally I'm not 100% convinced of the acceleration of the outer bodies of the universe - there's so much crap between them and us re-emission is pretty much guaranteed. The work done by these guys is still pretty darned impressive, I just remain to be convinced.
but
in the standard model of cosmology the redshift is actually gravitational in origin and not coming from a physical "velocity".
When Theories Don't Match Observation
"in the standard model of cosmology the redshift is actually gravitational in origin and not coming from a physical "velocity"."
Isn't that the point? Can we demonstrate gravitational origin of red-shift? When theories do not match observation and laboratory experiments, then the theory should be changed. My worry is that there are so many vested interests and reputations built on the 'standard model of cosmology', I wonder whether inconvenient new evidence that doesn't fit the model is sidelined rather than embraced and the model updated.
Cosmological redshift
In astronomy, there are just three types of redshift, (a) Doppler, due to motion (b) Gravitational (c) Cosmological, due to expansion. Doppler redshift is demonstrated in the laboratory, gravitational redshift is testable in space. But cosmological redshift is basic made up (sorry, a theory) to explain its high values.
Most other kinds of redshift, such as tired light theories, don't work because they are not frequency/wavelength independent, and so would cause blurring, or doublets/triplets in spectra. However, under some circumstance, the Wolf Effect will produce frequency independent redshifts that is indistinguishable from the Doppler redshift, AND, has been demonstrated in the laboratory. The only other type of redshift that looks promising is the plasma redshift. See:
http://www.plasma-universe.com/Wolf_effect
http://adsabs.harvard.edu/abs/2009ASPC..413..169B
"Can we demonstrate gravitational origin of red-shift?"
Yes, it's been tested in controlled conditions. Gravitational redshift is a real effect, and one of the major tests of GR.
As for the standard model, it's a cludge. Phenomenology, in the jargon. Every theoretician who works on it is very well aware of this, although they don't always seem to communicate that to the public. The thing is that it's a model, and an astoundingly successful one. Being able to use CMB and supernova data to get out the standard model, use it to predict the wavelength of ripples in the galactic distribution and *finding those ripples with exactly that wavelength* is pretty impressive, given that small changes to the model yield big changes to those ripples. Being able instead to use CMB and those ripples to predict the dimming of distant supernovae and *finding that dimming* is pretty impressive too. Those are predictions of the model, not things inserted after the event.
I don't like the standard model much. As I say, it's a cludge. But phenomenology or not, it works pretty damned well, and every alternative cleverer minds than I have proposed has failed, one way or another. And, ultimately, that's all physics (and indeed science as a whole) is: phenomenology.
I won't deny it can be hard to get funding for crazy alternatives, but it's actually not impossible to make your career all the way through with non-standard alternatives. It's more normal to work in both - because, ultimately, the standard model is very successful and as a result is worth considering more closely...
I'm sorry, AC, but "But cosmological redshift is basic made up (sorry, a theory) to explain its high values" is simply not true. "Cosmological redshift" is nothing other than gravitational redshift. It comes from a change in the metric the light propagates through. Now, we can argue whether that even makes sense at a fundamental level, since light does not propagate through a cosmological metric but instead through an enormous tangle of inhomogeneous metrics that we assume looks like Robertson-Walker on large scales, but that's a totally different issue (and linked to my own objections to the standard model). The model is a background metric that describes the universe as a whole. Using that metric and the Einstein equations gives you a gravitational redshift. Don't like the model? Don't use it (although it would be helpful to see credible alternatives that can fit as much data; like it or not, Lambda CDM is extremely successful), but don't try and claim it's anything other than a gravitational redshift.
Now, whether the redshift we *observe* is that "cosmological redshift" is again a different question and that's where the alternatives come in. Personally I feel the model fits far too much to discount it, even if I think its underpinnings are pretty shaky. We can ignore the supernovae altogether and still end up with Lambda CDM - using that Lambda CDM to predict the supernova dimming we get something amazingly close to the observation. That's pretty persuasive, to my mind. Unless you can produce a CMB and BAOs with such wildly different redshifts (~1100 compared to ~0.5) and with features that agree in the same way -- the wavelength of the oscillations, hell even the amplitude of the oscillations -- and still manage to get the supernovae working, for now I think the community will stick with the standard model, as unsatisfactory and clearly ludicrous as it is.
Cosmological/gravitational redshift
"Cosmological redshift" is nothing other than gravitational redshift
The Cosmological Redshift is considered to be due to the expansion of space, and has nothing to do with gravity,
Quantum Celestial Mechanics(QCM), considers that some "Cosmological redshifts" are gravitational, butt QCM is itself yet another new theory. See:
http://www.ptep-online.com/index_files/2007/PP-09-06.PDF (PDF)
It's All Crazy Until We Investigate and Find Out It's Not!
You've lost me in the detail a bit there. But I still think the main issue is that 'conventional' science can charge headlong into propogating a theory, not necessarily correct, that becomes self-perpetuating and self-sustaining killing off all other alternatives.
Galileo of course was considered crazy in his time by supporting the idea that the earth orbitted the sun rather than vice versa.
If just perhaps 1% of the research budget used to build the CMB model over the years was spent investigating seriously other 'crazy' ideas, perhaps we'd find they were not so crazy after all? This would save us pushing further down research avenues that will ultimately end in a dead-end, spending millions of pounds in the process.
I used to think that Nobel prizes were given out to people that have undertaken great work in the advancement and for benefit of mankind. Silly me, but detecting that galaxies are moving faster and faster away from us, not really sure how that benefits mankind.
Yup, silly you
From Nobel's will:
“The said interest shall be divided into five equal parts, which shall be apportioned as follows: /- - -/ one part to the person who shall have made the most important discovery or invention within the field of physics ...”
"... as judged by El Reg commentard TkH11", it fails to continue.....
The importance of discoveries and inventions is judged by the prize committees. That's why they exist.
What exactly does "rate accelerating" mean?
The article says that the "rate of expansion of the universe is accelerating". Does that mean that the 2nd derivitive of expansion rate with respect to time is positive? Or just that the rate of expansion is increasing (1st derivitive is positive)?
second derivative. we've known that the first derivative, the expansion rate (known as the hubble rate) is positive since the 1920s, although i wouldn't trust hubble's value very much.
So
Who was the chap who said that the rate of expansion is not increasing, such an illogical thought.
According to this article it was the same guy who won the Nobel Prize.
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