S. D. Odintsov

The universe in its first moments is like an inflating balloon. Cosmologists are trying to figure out what makes it puff up, and there's no shortage of ideas. One idea is to tweak Einstein's gravity slightly — adding an 'extra ingredient' that only kicks in at mind-boggling energies.

Baking bread starts with nearly homogeneous dough, in which tiny gas bubbles are already hidden. They grow, and the rate of their growth determines the future structure of the crumb. In cosmology, the role of such bubbles is played by the seeds of galaxies — barely noticeable density enhancements in the hot 'soup' of the early universe.