October 4, 2011

expert reaction to announcement of the Nobel Prize for Physics

This years Nobel Prize for Physics was awarded 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”.

Prof Michael Rowan-Robinson, Professor of Astrophysics at Imperial College London, said:

“The two astrophysics teams, one led by Saul Perlmutter, the other by Brian Schmidt and Adam Riess, found evidence of the accelerated expansion of the Universe at approximately the same time using data from exploding white dwarf stars in distant galaxies.

“The signals were somewhat fainter than expected, suggesting the galaxies were further away than originally predicted. This suggested that galaxies are being pushed apart by some mysterious repulsive force, the so-called dark energy. A repulsive force acting on large scales in the universe was first proposed by Einstein in 1916, when he was trying to construct a static model of the universe. There is still no consensus among physicists on the nature of this dark energy.

“The impact of this finding on cosmology has been huge. The dominant role of dark energy in the universe has been confirmed by the WMAP mission, analysing fluctuations in the microwave background radiation left over from the earliest stages of the Big Bang.

“I have a particular interest as I was part of a group that looked for other reasons to explain how the Universe can appear to be expanding at an ever-faster rate. We were unable to undermine the findings of the two teams and it’s now momentous to see the research which indicated the existence of dark energy being rewarded so prestigiously.

“These astrophysicists’ research revolutionised our common perception of the Universe and unveiled an array of mysteries that we are still trying to fathom.”

Prof Carlos Frenk, Director of the Institute for Computational Cosmology, at Durham University, said:

“”This Nobel Prize recognises one of the most unexpected and dramatic discoveries in Physics in recent decades.

“It is unexpected because it shows that the expansion of our Universe is accelerating, not decelerating as physicists thought 15 years ago.

“It is dramatic because it implies that we do not inhabit a simple, elegant Universe made only of matter but a Universe that, in addition to matter, contains a strange substance, so bizarre that we call it ‘dark energy’.

“We have no idea of what the dark energy revealed by the supernovae data is – unravelling its identity ranks as one the great scientific challenges of the 21st Century.”

Prof Roger Davies, President of the Royal Astronomical Society & Philip Wetton Professor of Astrophysics, Department of Physics, University of Oxford, said:

“It is wonderful to see the award of the Nobel prize in Physics to the supernova cosmology teams. This recognises a transformative discovery in astrophysics that was a huge surprise at the time. The discovery set the direction for work over the last decade or so and stimulated some of the most ambitious proposals for future space missions and ground based surveys.

“The surprise is perhaps best illustrated by the fact that before the discovery of the accelerating universe astronomers had been attempting to measure its deceleration hypothesised to be caused by the mass of galaxy halos slowing the universal expansion. The discovery led to the realisation that empty space exerts a pressure that pushes the galaxies apart – something that demands new physics and a new understanding of space-time.”

Lord Martin Rees, Astronomer Royal & Emeritus Professor of Cosmology and Astrophysics at the University of Cambridge, said:

“This award recognises an important and surprising discovery. Even empty space contains energy and exerts a kind of ‘antigravity’ which causes cosmic expansion to accelerate. It will be a long time before theorists understand this force — it is part of the bedrock nature of space and time. This discovery has been subsequently strengthened and corroborated by other advances: the evidence from the cosmic microwave background (especially the Boomerang and WMAP experiments) that the geometry of the universe is ‘flat’, and an accumulation of evidence from observations with large telescopes that atoms and ‘dark matter’ amount to no more than 30 percent of density needed to make it so.

“I think, however, that this is one of the increasingly frequent instances when the Nobel Committee is damagingly constrained by its tradition that a prize can’t be shared between more than three individuals. The key papers recognised by this award were authored by two groups, each containing a dozen or so scientists. It would have been fairer, and would send a less distorted message about how this kind of science is actually done, if the award had been made collectively to all members of the two groups.”

Dr Mark Sullivan, Department of Physics, University of Oxford, said:

“I think this is fantastic news, and thoroughly well-deserved. Their direct discovery of the accelerating universe in the late 1990s, using distant cosmic explosions known as supernovae, has rewritten textbooks, and was one of the landmark breakthroughs of 20th Century physics. The nature of the dark energy that propels this accelerating universe remains a mystery, preoccupying physicists ever since, and is at the forefront of modern astrophysical research – it’s the motivation for many ongoing, and future, ground and space-based experiments.”

Dr Sullivan led the team that recently discovered the nearest type 1a supernova to be discovered for 40 years: http://www.ox.ac.uk/media/news_stories/2011/110825_1.html; http://www.ox.ac.uk/media/news_stories/2011/110907.html

Prof Sir Peter Knight, President of the Institute of Physics, said:

“The recipients of today’s award are at the frontier of modern astrophysics and have triggered an enormous amount of research on dark energy. These researchers have opened our eyes to the true nature of our Universe. They are very well-deserved recipients.”