Here's something that I wrote and posted on another more basic closed forum a few days ago

Basic Science Background

True science began when mankind went beyond just observing and measuring the world and all its phenomena and started making mathematical models of things that enabled predictions of other events to be made. The classic example of this is that the ancient peoples knew how the sun moon and planets moved round in the sky with great precision and could even predict eclipses but they had no idea why the moved the way they did and just put it down to "God". Isaac Newton changed all this when he realised that if all bodies attracted each other with a force that was dependant on their mass and inversely proportional to the square of their distance apart (the inverse square law) the observed behaviour could be predicted. This allowed him to calculate how they would move from first principles not just observation. A major part of science science therefore depends on turning observations into models and using the models to predict new observations that can be made to help to prove that the model is correct. Of course another part of science is associated with testing the models to ever better accuracy to check if there are any slight deviations (but that is another story!).

The situation before string theory

The behaviour of sub atomic particles had been measured in great detail and very accurate models (the most accurate in all science) had been created and tested showing how the electrical charges that hold atoms together worked and the precise limits of observation and behaviour (quantum theory) had been developed, BUT there was a big problem. Certain of the fundamental particles, notably electrons and the quarks that make up the protons and neutrons in the atom. Although they had clearly complex properties like mass, charge and spin etc. they did not appear to have any measurable size or shape and were to all intents and purposes mathematical points. This is very unsatisfactory because a mathematical point cannot have any properties other than where it is and all the inverse square relationships go off to infinity and make no sense. How should this be solved?

The Basic Concept of String Theory

Some mathematicians decided that this unsatisfactory situation should not continue so they arbitrarily decided that instead of a mathematical point they should try to build a model based on the idea that a particle was a tiny string with rigidity or tension that could vibrate in many different ways. In order to allow this model to work they needed at leas ten different ways (dimensions) for this string to vibrate. These could be physical dimensions, like we have three dimensions of space and one of time (space-time) of which we are familiar, or, they might be other sorts of ways of looking at things like little loops or twists in this string. These ideas involved more than just how to describe the particles, all the laws of physics like electrical charge and gravity came out of the model. It was starting to look like a "theory of everything". There was one big problem however. There were around six different approaches to creating this model that could be taken, each of which proved to have many alternatives. Eventually is was realised by adding one more "dimension" to make eleven they could link all the different models together. This then resulted in a vast choice of possible models for the way that the laws of the universe originated. The approximate number was 10 followed by 500 zeros! Most of these models would produce universes totally unlike ours. The big problem is that if you consider the physical laws, our complex universe that contains life looks exceedingly improbable because the laws are finely balanced to allow atoms to form and stars to make them and eventually life to evolve. Identifying the possible models from the vast number available is an enormous searching task way beyond anyone at the moment. It is only when a reasonable range of possible models is defined quite accurately that some fine tests may be devised to try to prove which one is the right one. And that is the way things lie at the moment.