The Complete Idiot’s Guide to String Theory is one way for you to attempt to understand String Theory. While any such effort will probably not work, you will probably learn some things along the way as long as you are not a theoretical physicist. If you are a theoretical physicist, this book will just make you mad, so don’t even go there.
String theory describes the universe much like Newtonian Physics describes the universe … in a way that explains what we observe and what we think is possible. Newtonian Physics falls short of explaining some basic observations, and has been replaced by Einsteinian Physics. However, Einstein did not conceptualize his theories of relativity because he saw things in nature that Newton could not explain. Instead, there were certain ‘knowns’ that had been well demonstrated regarding the physical universe, and certain PGT’s (pretty good theories) about how the universe worked, which, when you thought about them enough, caused a theoretical conflict with the “knowns.” Einstein re-described the universe more accurately than Newton prior to the invention of tools that would allow observations to be made that contradicted Newton and required Einstein. In other words, Einstein thought us to the next level of thinking.
This is not quite so with the other major theory of the Universe, which I’ll call the Standard Model but you may know of as Particle Physics or even Quantum Physics or Quantum Mechanics. In this case, the initial formulation of the model, which came in several stages, included coming up with theory to explain unexpected observations, as well as theory based on simple measurement and observation. Eventually, the Standard Model congealed enough that it started popping out its own predictions (much like Einstein’s models did), which mostly take the form of as yet observed particles. In other words, the Standard Model is a combination of thinking ahead of observation and thinking about observation.
String theory is pure thinking.
There is no observation that one can make using an instrument that gives some goofy result that can best be explained by String Theory. String Theory is a very high level mathematical formulation that gains its prowess not from making natural question marks turn into explanation points (as the other theories of physics tend to do) but rather, from the dubious distinction of making mathematicians get all Squeeeeee over the fact that several once-thought-to-be utterly different complex formulas are really all the same, simultaneously deep and overarching single one-formula-to-rule-them-all formula.
The essence of string theory is actually very simple. String theory links together certain key feature of particle physics with certain key features of dimensions to extend both concepts in a way that describes, and thus kinda explains, all forces including subatomic forces and gravity. Any detail beyond that is almost incomprehensible so don’t even try.
But what about this book? Does it explain string theory in a way that makes sense and is convincing?
Certainly not. String theory makes no sense and is not even close to convincing. So if the theory does not manage those tasks, then some dumb book certainly is not going to be able to do them.
String theory is essentially intractable from a human perspective. We are physically and psychologically incapable of understanding string theory. I think I have a good metaphor for this dilemma.
Imagine that for some reason you had to believe that any behaving multi-celled organism … a frog, a dog, a nematode, another human … had a human like mind and human like senses and sensibilities. You do not have the option of having any other form of belief. If that was true, you would never be able to really get what was going on in the natural world, but you would have explanations for everything. You would explain the nectar foraging behavior of bees, the drumming of the prairie chicken on the lek, the sounding of whales, and the schooling of fish in purely human terms. If someone came along with an alternative theory that said that different types of organisms have a) different types of brains and b) different sets of senses, that would be hard to believe as it would conflict with your view of everything. Furthermore, a theory that explains the behaivor of an earthworm, a duck, a monkey, and a grasshopper needs to operate not at the level of the mind, not at the level of the brain, not at the level of the five sense, visually oriented world of humans. Rather, it would operate at the level of the neuron. It would be “Neuron Theory.” You would have to grasp what a neuron was, how it worked, how there could be certain different kinds of neurons. Then you would be asked to accept how a bunch of these neurons linked together, and even communicating with each other across space using senses, can produce the diversity of behaviors that you were previously assuming all had a very different explanation. The gap between this “neuron” thing and the diverse complex world “neuron theory” purported to explain would be so huge that you would have a hard time accepting it.
String theory is like that but much harder.
Like so many other things in the physical sciences (even basic engineering) there is a gap between the typical human understanding of a phenomenon and the mathematical model that fits the phenomenon. The human understanding may lead to a set of predictions or descriptions that are just plain wrong, while the mathematical formulation leads to predictions or descriptions that are just plain right, and that actually tell us about things we cannot really otherwise guess at. In some cases, the math forces us (through the proximate mechanism of curiosity) to find a way to make an observation that we would never otherwise make …. to make detectable a particle normally hidden from our human senses, for instance.
String theory has yet to produce a description that outlines a gap in physical (observed) knowledge that can be filled with a doable experiment. If the large hadron collider manages certain amazing tricks, a couple of predictions of String Theory may be tested, but first they’ve got to get that machine to run for more than a few days.
If you don’t know much about String Theory and you are not a physicist, I do recommend this book. The other book that is good for this sort of thing is The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory
. Either way, you won’t get String Theory, but you’ll have fun getting there, until near the end when you realize that the driver of this particular bus is as lost as you are.