# Space and time, light and gravity

What is gravity? What is spacetime and why does it get curved? How are quantum fields

and spacetime related? What is string theory? Do we really need it to describe the world?

Since the discovery of quantum mechanics and Einstein's theory of relativity, scientists have been trying to combine them into one single unified theory. This is a difficult task

because the perspectives offered by these two theories are radically different. One of the results of these attempts is string theory.

String theory suggests that the fundamental constituents of nature are one dimensional strings and not point particles. This innocuous looking modification turns out to have profound consequences, changing completely the way we view the fundamental laws of

nature and even spacetime itself. For instance, it leads to the surprising result that light and gravity can be different sides of the same coin. It is a story that is still evolving, with many unexpected twists still to come.

In this talk, Robert de Mello Koch will review what the issue is, explain our current

understanding of the problem and speculate shamelessly on the structure of its final solution.

Afterwards, contemplation of the nature of space and time will be enhanced by relativistic cocktails at the bar and stringy jazz by the Peter Sklair Quartet.

Entrance to the event costs R20. Doors open at 18:30. No registration is necessary, but bookings can be made via The Orbit.

#### Robert de Mello Koch

# Space and time, light and gravity

What is gravity? What is spacetime and why does it get curved? How are quantum fieldsand spacetime related? What is string theory? Do we really need it to describe the world?