While everything in science is derived indirectly when we can't go there directly like the inside of the sun. To be true it must be testable, reproducible and falsifiable. For String Theory that test will be to perfectly derive the mass of a proton using string theory equations. That is how close we are and yet far away.

It turns out we do get something from nothing. The energy in the Universe equals zero when the positive energy of matter and radiation is equal to the negative energy of gravity, or when adding all the different galaxy spins turn out to be zero. Hawking used to say the dirt you remove from a hole equals the volume of the hole.