Rachel's Blog: How long is a piece of string?

Mon, 17 Nov 2003

Just finished reading A Brief History of Time by Stephen Hawking. And although everyone I've spoken to about it so far (OK Richard and Xander) has said they didn't get the last bit, I am happy to report that I think this is a fault of the writing and not my family's brains. I know I've seen better explanations of string theory in tv documentaries. Perhaps it's the age of the book (it was first published in 1988), but it seems to me to lack a couple of paragraphs on the actual why of strings, as opposed to the how and what.

So I went searching for more and have discovered the Official String Theory Web Site (of course!). In particular this made a lot of sense to me:
But it wasn't enough that there be a graviton predicted by string theory. One can add a graviton to quantum field theory by hand, but the calculations that are supposed to describe Nature become useless. This is because, as illustrated in the diagram above, particle interactions occur at a single point of spacetime, at zero distance between the interacting particles. For gravitons, the mathematics behaves so badly at zero distance that the answers just don't make sense. In string theory, the strings collide over a small but finite distance, and the answers do make sense.

Comment by Freeman R. Williams on Sat, 28 Feb 2004

I'm a 88 year old man and I've heard the phrase "How long is a piece of string" and in all my 88 years I've found only one answer. It's twice as long if it's folded in the center, and measured.

Comment by Jennie on Fri, 04 Feb 2005

Theres a book called 'the elegant universe' which is about string theory and is very readable. Unfortunatly I do't get much time to read cuch things these days as I'm busy completing my fashion and clothing degree in London.

Comment by Bill on Sun, 08 May 2005

I agree with Freeman, a piece of string is twice the distance from the middle to either end.