Cosmic Inflation

Tags: Cosmic inflation, New Scientist, Universe, Dark Matter, CERN, LHC, Big Bang, Physics

Date: 26 May 2010 12:00:06

[caption id="attachment_201" align="alignright" width="300" caption="Image: Detlev Van Ravenswaay/SPL"][/caption]

There's an interesting article in the current issue of New Scientist about cosmic inflation. Allow me to explain.

We've known since the 1920s that the predictions of Einstein's general relativity about the expansion of the universe are correct, and that the further away one looks, the faster distant galaxiesare moving away from us. Extrapolating back in time, the universe is thought to have exploded out from an infinitesimally small point of infinite energy and spacetime curvature, known as a singularity. This explosion has come to be known as the big bang theory.

Current physical theories can take us back in time to within a tiny fraction of a second after this explosion. Very close to the explosion, we have to rely on quantum theory, which is essentially the science of fundamental, subatomic particles. One quirk of the theory is Heissenberg's Uncertainty Principle, which tells us we cannot know the position and momentum of a particle with perfect accuracy simultaneously; the more accurately we know one, the less accurately we know the other.

Now, in the early universe (in that tiny fraction of a second after the big bang) there would have been fluctuations in the energy field caused by this uncertainty, as having zero energy at a given point is too precise to be allowed by the Uncertainty Principle. It is thought that these fluctuations gave rise to a period of rapid expansion of the universe, which is known as cosmic inflation.

From this stage of expansion, we have a mixture of fundamental particles, quarks and gluons, floating around. How we get from those to the protons and neutrons that make up the nuclei of atoms, the building blocks of life, is a mystery. Recent research by Tillmann Boeckel and Jürgen Schaffner-Bielich at the University of Heidelberg in Germany suggests that this may have been caused by a second, less dramatic period of inflation.

Why do we care? Well, in the Large Hadron Collider (LHC) at CERN in Geneva, they are hoping (when they can get the thing working!) to find evidence of dark matter. Dark matter is the extra matter that theory predicts is necessary to produce the universe we currently experience but is not the usual matter we can see around us and that makes up stars, planets and life. The properties that this matter has under this theory of an extra period of inflation will be quite different from what is currently being looked for at CERN. It raises big questions about what the early universe looked like and what's out there now. Exciting stuff... :D