How would you explain string theory to non-physicists such as myself? I'm especially interested in how plausible is it and what is needed to successfully prove it?
I've noticed that none of these answers actually answer the question.
The simplest explanation of string theory I can think of:
Particles we currently consider "point particles" (electrons, quarks, photons, etc.) are actually tiny pieces of string with each a characteristic vibration. They interact in a sort of harmony that results in/manifests as the physical laws we observe.
If anyone with more knowledge in the field can correct me, I ask for improvements. This is just how I personally explain it to people who ask, and I'd hate to give out false information.
String theory is the theory of gravity which starts out by postulating that only things at the boundary of space-time make sense. The local space and time have to be reconstructed from the boundary description. This is called the holographic principle. In the 1960s, a primitive vesion of this idea was called the S-matrix principle.
There are two kinds of boundaries, those far away from everything, called "cosmological" and those which are on top of matter, called "black hole horizons". The description of these two horizons are similar. The oscillations of these boundaries describe the entire space-time nearby.
The detailed form of string theory begins with the postulate that there are black holes that make extended, light, 1 dimensional lines. The vibrations of these black holes then must account for all the particles in the theory, because the vibrations of a black hole encodes anything that can fall through.
Some of the leaders in the field are Brian Greene and Michio Kaku. Both have made some Sci channel or Nova series that seemed appropriate for non-physicists.
I haven't been following the latest in physics for a while, but I thought that M-Theory had supplanted string theory some time ago. If so, then Kaku would be the guy. Greene's series and book "The Elegant Universe" also goes into some Quantum mechanics, which might help as well.
These are really the only two players I know of that simplify string theory. Does anyone else have some ideas?
Great question! Classical physics is known as the physics of the very large, objects that you can see with the eye. I can deterministically tell you exactly where something will stop, or how it will move if I have it’s velocity , and direction of travel. These things move like particles.
Quantum physics is known as the physics of the very small, stuff smaller than atoms. We’ve discovered that when you have mass , it’s easy to make super accurate guesses of how you will move in gravity but when you barely have any mass at all, like an electron, it becomes very difficult to guess how it will move. These particles do not obey the laws that rule the world we see around us. These things have properties of waves and particles.
There are big mathematical , and theoretical problems, when trying to put these two types of physics theories together. String theory tries to explain that if the universes smallest possible form was a string, it could satisfy being a particle, and a wave.
String theory goes beyond what is physically provable , to mathematically supported , hence it’s usually lumped in the theoretical bucket. Like religion, however much you want to have faith in it, no one can prove or disprove it. The particles are too small to see , just like the push, and pull of a magnet, we can only feel around in the dark. We know something is going on , but not enough to say it’s definitely an apple. Only that it feels curvy.
We need another Einstein and Newton. Big break throughs will happen, but you need a once in every several generations genius , thousands of years of scientific work, and technology we don’t have, and will not have for a long time.
I wrote a simple intro piece on string theory , which can be found here. Referencing string theory experts