Nobel stars

The Nobel prize in physics has been awarded to Saul Perlmutter and Adam Riess of the US and Brian Schmidt of Australia,whose work revolutionised,at the end of the last century,what we know about the construction of the universe. Two teams,one led by Perlmutter and the other by Riess and Schmidt,worked feverishly to examine the kind of light that supernovae across the galaxy were emitting; depending on the composition of a supernovas light,they could work out how fast it was moving relative to Earth. They discovered that supernovae further away were moving faster demonstrating that the universe was expanding,and even accelerating.

This needed physicists to rethink the building blocks of the universe. They had already surmised that a vast amount of matter was not visible to light or electromagnetic radiation,otherwise galaxies that stayed together because of gravity would have split apart long ago. Now they needed to imagine some sort of undetectable energy that would push galaxies apart from each other too,overcoming gravity and dark energy was born. The numbers are astounding: dark energy is three-fourths of the universes total mass-energy; and dark matter is most of the remaining quarter. Normal matter and energy are a tiny fraction,around 4.6 per cent.

The story of this Nobel underlines two things about pure science. First,that an enormous amount is still not understood about the galaxy,and empirical work can still revolutionise theory. And second,that competition works well for it. The two teams that raced to examine the supernovae that were honoured released similar results within weeks of each other,spurred by each others efforts. And their rivalry helped convince sceptics of the truth of their independently acquired results,in a demonstration of the strength of the scientific method.