What is String Theory ?

hi

I recently got a copy of Joseph Conlon’s new book Why String Theory? and was pleasantly surprised to find that it’s quite good. Conlon is a lively, entertaining writer, generally sensible about the scientific issues involved, and I think does a great job of explaining the point of view of typical physicists now working on string theory.

He also very ably explains the “sociology” of the field, the different kinds of people who work in this area and their varying sorts of goals and motivations.

The book is explicitly motivated by the desire to answer a lot of the criticism of string theory that has become rather widespread in recent years (wasn’t always so…).

It gets the main point quite right, that string theory unification is untestable, having failed to make any predictions, and by the conventional understanding of the scientific method, it’s past the time at which most theorists should have abandoned it and moved on.

I don’t see at all the point to arguing about the term “scientific theory”.

Sure, it’s a scientific theory, a failed one.

I’ve personally never noticed any consistent usage by physicists of terms like “theory”, “model” and “hypothesis” in ways that accurately indicate degree of experimental support, don’t see why some writers insist that there is one.

I also very strongly object to the article’s standard move of trying to make a failed theory a “mathematical theory”.

Mathematics is about well-defined ideas, and there is currently no such mathematical construct as “string theory”.

The problems with string theory have nothing do with mathematics, rather have to do with a physical idea that didn’t work out.

We live in a wonderfully complex universe, and we are curious about it by nature. Time and again we have wondered--- why are we here? Where did we and the world come from?

To a large extent the problems Conlon is struggling with are ones that the community of string theorists has inflicted on itself.

The great majority of writing for the public by string theorists is characterized by large amounts of outrageous hype. For a very recent example, see Daniel Harlow here, who seems to think string theory is a huge success at explaining the standard model

What is the world made of? It is our privilege to live in a time when enormous progress has been made towards finding some of the answers. String theory is our most recent attempt to answer the last (and part of the second) question.

I’ve always found reading this kind of thing quite puzzling. My impression of most string theorists is that they’re smart and rather sensible, well aware of the difference between ridiculous hype and an actual scientific argument

String theory, in particle physics, a theory that attempts to merge quantum mechanics with Albert Einstein’s general theory of relativity.

We live in a wonderfully complex universe, and we are curious about it by nature. Time and again we have wondered--- why are we here? Where did we and the world come from? What is the world made of? It is our privilege to live in a time when enormous progress has been made towards finding some of the answers.

The name string theory comes from the modeling of subatomic particles as tiny one-dimensional “stringlike” entities rather than the more conventional approach in which they are modeled as zero-dimensional point particles.

The theory envisions that a string undergoing a particular mode of vibration corresponds to a particle with definite properties such as mass and charge.

String theory is our most recent attempt to answer the last (and part of the second) question.

In the 1980s, physicists realized that string theory had the potential to incorporate all four of nature’s forces—gravity, electromagnetism, strong force, and weak force—and all types of matter in a single quantum mechanical framework, suggesting that it might be the long-sought unified field theory.

So, what is the world made of? Ordinary matter is made of atoms, which are in turn made of just three basic components: electrons whirling around a nucleus composed of neutrons and protons. The electron is a truly fundamental particle (it is one of a family of particles known as leptons), but neutrons and protons are made of smaller particles, known as quarks. Quarks are, as far as we know, truly elementary.

While string theory is still a vibrant area of research that is undergoing rapid development, it remains primarily a mathematical construct because it has yet to make contact with experimental observations.

Relativity And Quantum Mechanics


In 1905 Einstein unified space and time (see space-time) with his special theory of relativity, showing that motion through space affects the passage of time.