Space and time may be illusions
One of the deepest philosophical questions is: why is there something rather than nothing? A more tractable question is: why is there space and time even when there is no matter?
Most things in physics are represented as fields, continuous functions defined over space and time. There are electromagnetic fields, matter fields, strong and weak fields. All of these fields have what is called a “ground state”, a state in which they exist at their lowest energy level. In classical physics, the physics of Newton, Lagrange, Hamilton, and even Einstein’s relativity, fields tend to have zero ground states. For example, if I do not have anything charged around, I can expect that there will be no electric field around either. The electric field is in its ground state where there is nothing there to disturb it and make it active.
The one fundamental theory in classical physics that I know of that has a non-zero ground state is Einstein’s general relativity. It predicts that you can have something when there is nothing.
General relativity is, of course, the theory of gravity and how curvature in space and time create the illusion of a gravitational force, but when you have no masses, no planets, stars, galaxies, or anything to curve space and time, you still have space and time. They are just flat.
