Science Questions

What exactly is string theory?

Sat, 16th Jun 2012

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Catherine Hiscox asked:

What exactly is the string theory? Do these 'strings' really exist? And how can we know they exist if they have not been proven? I would really like to know! I love your programme and am telling all my friends about it. Take care and keep up the good work.


Catherine Hiscox


Dave - String theory is essentially trying to explain why we have all the fundamental particles we have.  So, protons and neutrons are made up of even smaller particles called quarks, and you get electrons and higher energy, more exotic particles – things like muons, and all sorts of different particles.  They can combine in different ways and they all have different masses.

People who are much better at maths than I am have spent a long time trying to find mathematical constructs, so ways of putting maths together to produce objects which look like the particles that we see and have similar properties which we can call mass. 

One of the ways they've done this is with some maths which look a bit like strings.  You can have oscillations on a string.  If you wobble the string slowly, you get one wobble in it as it wobbles left and right.  If you wobble it faster, you can get it to start making a snaking wobble.  As you make it faster and faster, these different vibrations could be associated with different particles.

The actual strings themselves are probably just maths.  We have no evidence to say there are actual little bits of cotton wobbling very, very rapidly.  So all we know is that there is some maths which gives rise to things which look a bit like the particles we have.  I'm not even sure that there's any actual evidence to say that string theory is better than any other particular theory.  They haven’t actually got that far, but that's what the guys in CERN are trying to do.


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Conventional particle theory had the concept of a point particle but this creates mathematical problems because at a precise geometrical point standard inverse square law forces all go of to infinity.  These can be avoided with a few mathematical tricks like defining the calculations on a way that runs a line around the mathematical point and gets arbitrarily close to it and showing that the results are good right up to the limit.

String theory is another way of avoiding the problem by defining the particle as finite lines  this makes many aspects of the maths more difficult and has vastly more possible solutions. However it avoids the infinity problems. Soul Surfer, Wed, 20th Jun 2012

Can we be sure they are not just stringing us along? Geezer, Thu, 21st Jun 2012

possibly not - it's definitely a brane-teaser. imatfaal, Thu, 21st Jun 2012

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