Physics Page
Gravity as the theory of geometry for spacetime
At the moment, I am an associate professor at the Yukawa Institute for Theoretical Physics (YITP), Kyoto University, Kyoto, Japan. My topic is Gravity.
What is Gravity? Its effects, the gravitational force, was probably the first force ever studied in physics. Galileo studied the motion of bodies in the constant gravitational field of the Earth. He guessed what today is one of the fundamental points of General Relativity: all bodies fall exactly in the same way in a gravitational field. Fantastic!
But once more, what is gravity? So far we have a classical theory which can explain the behaviour of gravity in many situations, except when quantum effects begin to play an important role.
Not to know the quantum behaviour of gravity is indeed a challenge for today's theoretical physics. However, already at a classical level, we still do not exactly know what gravity is and how it behaves.
The problem is not at the level of our solar system. The problems come only when we look at large scales experiments. We indeed find that the universe is accelerating, or in other words, General Relativity plus radiation plus galaxies, are not able to fit current data.
At the moment, there is no solution to this problem! Good!