Nobel win for Aussie dark energy discovery

Every year, all eyes turn north to see who takes out the Nobel Prizes, the most prestigious scientific awards Sweden has to offer. And in 2011, Australian eyes got to see one of our own, Professor Brian P. Schmidt, receive the Nobel Prize in Physics.

Professor Brian P. Schmidt, of the Australian National University
Professor Brian P. Schmidt, seen here observing the expanding universe (Photo by Belinda Pratten, ANU)

Professor Schmidt shared the prize with Saul Perlmutter, from the Lawrence Berkeley National Laboratory and University of California USA, and Adam G. Riess, Johns Hopkins University and Space Telescope Science Institute USA (actually, in the complex way the Nobel Prize works, Saul Perlmutter got 50% and Brian Schmidt and Adam Reiss each got 25%).

The trio won it for showing that the universe is not only expanding – the first evidence for which was found by Edwin Hubble in 1929 – but its expansion is actually accelerating.

They showed this by observing distant Type Ia supernovae (or supernovas, if you prefer). These incredible explosions occur when white dwarf stars get too big, specifically 1.38 times the mass of our Sun (they usually do this by pulling matter off a nearby star). When they reach this threshold, they collapse under their own weight, and their core compresses further until the pressure sets off a tremendous nuclear fusion reaction that blows the whole thing to smithereens.

What makes these Type Ia supernovae so special is that we know exactly how they work and they’re all exactly the same. So they make great markers that we can look at across the universe. From their brightness we can calculate how far away they are, and from their Doppler redshift we can figure out how fast they’re moving away from us.

The findings that Schmidt, Reiss and Perlmutter announced in 1998 demonstrated that the more distant the supernovas are, the faster they’re moving away from us – and this expansion is getting faster all the time.

The best known explanation for this acceleration is the existence of dark energy, a mysterious, invisible force that permeates all of space. We discussed dark energy – as well as dark matter – and some recent discoveries concerning them a few months ago on Lost in Science (see ‘Help our mass is missing‘). But it’s great to see the original discovery getting such recognition!

Incidentally, according to Wikipedia, Brian P. Schmidt is the 11th Australian to win the Nobel Prize, and our 2nd laureate in physics. Physiology and Medicine is clearly our strong point, with no less than 7 winners, but here’s hoping the physicists are on their way to catching up!

For more on his prize-winning work, see Brian P. Schmidt’s homepage.

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