We will understand the moment of the big bang

Sean Carroll forecasts the future

• 18 November 2006

The most significant breakthrough in cosmology in the next 50 years will be that we finally understand the big bang.

In recent years, the big bang model - the idea that our universe has expanded and cooled over billions of years from an initially hot, dense state - has been confirmed and elaborated in spectacular detail. But the big bang itself, the moment of purportedly infinite temperature and density at the very beginning, remains a mystery. On the basis of observational data, we can say with confidence what the universe was doing 1 second later, but our best theories all break down at the actual moment of the bang.

There is good reason to hope that this will change. The inflationary universe scenario takes us back to a tiny fraction of a second after the bang. To go back further we need to understand quantum gravity, and ideas from string theory are giving us hope that this goal is obtainable. New ways of collecting data about dark matter, dark energy and primordial perturbations allow us to test models of the earliest times. The decades to come might very well be when the human race finally figures out where it all came from.