Archive for October 4, 2011

Dark Energy’s Day

Posted in The Universe and Stuff with tags , , , on October 4, 2011 by telescoper

Following hard on the heels of the announcement of a Nobel Prize for cosmology earlier this morning, the European Space Agency has this afternoon officially announced the two candidates which have been chosen for its next M-class missions from a shortlist of three.

One of the successful candidates, EUCLID, is directly relevant to the topic covered by the Nobel Prize announced this morning. “Euclid will address key questions relevant to fundamental physics and cosmology, namely the nature of the mysterious dark energy and dark matter. Astronomers are now convinced that these substances dominate ordinary matter. Euclid would map the distribution of galaxies to reveal the underlying ‘dark’ architecture of the Universe.”

Now that it’s definitely been selected, I hope to devote time in due course for a longer post about EUCLID’s capabilities and intentions, but in the meantime I’ll just say that it’s been a very good day for Dark Energy.

P.S. The other successful candidate is called Solar Orbiter. Commiserations to advocates of the third mission on the shortlist of three, PLATO. Close, but no cigar…

Another Nobel Prize for Cosmology!

Posted in The Universe and Stuff with tags , , , , , , , on October 4, 2011 by telescoper

Just time in between teaching and meetings for a quick post on today’s announcement that the 2011 Nobel Prize for Physics has gone to Saul Perlmutter, Brian P. Schmidt and Adam G. Riess “for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.”

I’ve taken the liberty of copying the following text from the press release on the Nobel Foundation website

In 1998, cosmology was shaken at its foundations as two research teams presented their findings. Headed by Saul Perlmutter, one of the teams had set to work in 1988. Brian Schmidt headed another team, launched at the end of 1994, where Adam Riess was to play a crucial role.

The research teams raced to map the Universe by locating the most distant supernovae. More sophisticated telescopes on the ground and in space, as well as more powerful computers and new digital imaging sensors (CCD, Nobel Prize in Physics in 2009), opened the possibility in the 1990s to add more pieces to the cosmological puzzle.

The teams used a particular kind of supernova, called type Ia supernova. It is an explosion of an old compact star that is as heavy as the Sun but as small as the Earth. A single such supernova can emit as much light as a whole galaxy. All in all, the two research teams found over 50 distant supernovae whose light was weaker than expected – this was a sign that the expansion of the Universe was accelerating. The potential pitfalls had been numerous, and the scientists found reassurance in the fact that both groups had reached the same astonishing conclusion.

For almost a century, the Universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago. However, the discovery that this expansion is accelerating is astounding. If the expansion will continue to speed up the Universe will end in ice.

The acceleration is thought to be driven by dark energy, but what that dark energy is remains an enigma – perhaps the greatest in physics today. What is known is that dark energy constitutes about three quarters of the Universe. Therefore the findings of the 2011 Nobel Laureates in Physics have helped to unveil a Universe that to a large extent is unknown to science. And everything is possible again.

I’m definitely among the skeptics when it comes to the standard interpretation of the supernova measurements, and more recent complementary data, in terms of dark energy. However this doesn’t diminish in any way my delight that these three scientists have been rewarded for their sterling observational efforts. The two groups involved in the Supernova Cosmology Project on the one hand, and the High Z Supernova Search, on the other, are both supreme examples of excellence in observational astronomy, taking on and overcoming what were previously thought to be insurmountable observational challenges. This award has been in the air for a few years now, and I’m delighted for all three scientists that their time has come at last. To my mind their discovery is all the more exciting because nobody really knows precisely what it is that they have discovered!

I know that Brian Schmidt is an occasional reader and commenter on this blog. I suspect he might be a little busy right now with the rest of the world’s media right to read this, let alone comment on here, but that won’t stop me congratulating him and the other winners on their achievement. I’m sure they’ll enjoy their visit to Stockholm!

Meanwhile the rest of us can bask in their reflected glory. There’s also been a huge amount of press interest in this announcement which has kept my phone ringing this morning. It’s only been five years since a Nobel Prize in physics went to cosmology, which says something for how exciting a field this is to work in!

UPDATE: There’s an interesting collection of quotes and reactions on the Guardian website, updated live.

UPDATE on the UPDATE: Yours truly gets a quote on the Nature News article about this!