So the fabric of space according to Einstein is nice and flat if there is no matter or energy present, but the presence of something like the sun causes the fabric to warp and now an object, like the earth in this case, would be rolling around the distorted spatial fabric caused by the presence of the sun and in that way according to Einstein, the sun affects the motion of the earth gravitationally. So the key idea is that the fabric of space warps in response to the presence of objects, and that warp is what Einstein said actually is gravity. So, that has become what the physicists think of what's happened with large objects but along behind Einstein came people who were looking at smaller objects, microscopic and they came up the theory of quantum mechanics. They knew that they needed to develop a new theory. Quantum mechanics is that theory, and it paints a strange picture of the microscopic world that says, for instance, that there is a wild turbulent frenzy happening on microscopic scales.
Particles pop in to and out of existence all the time.
Energy fluctuates up and down. It's a very turbulent arena, according to quantum mechanics. And that's the conflict. In the search to resolve that conflict, physicists began investigating the notion of super string theory. So the string theory is our first hope to resolve the central conflict of 20th century physics.