A father-daughter team from an interdisciplinary science center in India has published creative new thinking about the biggest problems in physics and cosmology. They address three if the issues that have stumped physicists for decades
- Einstein’s theory of gravity governs space, time and matter on large scales, and quantum mechanics rules on small scales. The two theories seem completely incompatible, and since their realms do not overlap, no experiments are possible that might lead to a quantum theory of gravity.
- During the last 20 years, observations of the most distant galaxies indicate that the expansion of the universe is governed not by the familiar gravity we understand but by a gravity-like force that pushes where gravity pulls. It is a universal repulsion which has been named “dark energy”, but we have no idea what it is or where it comes from or why it is just the right strength to come to dominate the dynamics of the universe just in the present epoch and not before.
- The early universe was mostly smooth and uniform, but contained just a tiny amount of clumpiness on the right scale that the clumps could condense (via gravity) into galaxies as the universe expanded. Where did the clumpiness come from, and why was its scale just right to make galaxies the features of our universe?
Thandu and Hamsa Padmanabhan have published an idea this year that connects all these problems to the entropy content of space. On the smallest scale (far smaller than any sub-atomic particle yet discovered), space and time themselves are pixelated and not continuous. The size of the pixels dictates the maximum amount of information that a region of space-time can contain, and in Padmanabhan’s theory, this quantity dictates both the amount of dark energy and the clumpiness of the cosmos. (I don’t want to spoil the ending for you, but it turns out that the answer is 4π.)