'Vibrating strings' may hold the key

The next time you pour a drink of sparkling water, stop and look at the bubbles. Could our universe be like one of them, a single bubble among many other universes?

That’s was one of the mind-blowing (if speculative) concepts outlined by Prof Brian Greene in his keynote address at Euroscience Open Forum 2012 in the Convention Centre in Dublin.

The focus of his talk was string theory, which, he explained, is an attempt to realise Einstein’s dream of a unified theory of physics.

“It should be a single idea, a single equation that perhaps would describe the big things in the universe such as the stars and galaxies, the small things such as the atoms and molecules and then everything in between,” he told The Irish Times.

So where do the vibrating strings come in?

“The approach is to rewrite our understanding of the basic constituents of nature,” said Prof Greene, who is professor of mathematics and physics at Columbia University.

“Instead of thinking of little tiny dots or particles that come together to make bigger things, the dots are replaced by string-like filaments that can vibrate in different ways, and the different vibrations correspond to difference kinds of particles. Everything is basically built from the music of these vibrating strings.”

For now the concept remains hypothetical, he noted, and the strings are so small they are well beyond reach of today’s technology: “String theory has put gravity and quantum mechanics together into one consistent framework, and that’s a big achievement, but we have not been able to experimentally test the theory.”

An even more speculative notion is the "multiverse", which puts forward the concept of many bubble-like universes. Researchers are analysing cosmic background microwave radiation to look for potential signs of other bubble universes having collided with ours. If such signs are found then it could offer indirect evidence for the multiverse, explained Prof Greene, but it is still early days.

More generally, will knowing about vibrating strings in sub-atomic particles or colliding universes really change how we live? Probably not for now, according to Prof Greene, but we don’t know what lies in the future.

“If you had asked quantum [physicists] in the 1920s what is quantum mechanics good for, it was very far from every day life,” he said.

“But today the integrated circuit inside [mobile] phones, computers and medical technologies come from quantum mechanics. Basic science can flourish into things that do affect us.

"Also, did the Mona Lisa or starry night or Beethoven’s 9th symphony change your everyday life, put more food on the table? No, but it makes life worth living and this is the kind of idea that, if it’s true, changes our idea of how it fits into the broad cosmos. I think that is part of what makes life worth living.”