paper folding

[matthay]

is it true you can't fold a piece of paper in half more than 7 times

[Lonnie]

Yes you can, its nine you can't do, try it with a double page of a newspaper, and post your results back.

[PhilBy]

Scroll half way down the page:

http://www.cmis.csiro.au/helixstories.htm

[PhilBy]

So much for that link! Copy & Paste >>>>>

Did you know that it is physically impossible to fold it in half more than eight times? The reason is exponential growth.

Starting with a piece of paper and folding it in half, you�ll notice that its thickness doubles to become two sheets thick. If you fold it again it becomes four sheets thick. This is double what you had before. In fact, each fold doubles the thickness of the stack of paper.

This relationship can be expressed mathematically as 2 x 2 x 2 x . . ., and so on, or 2n where n is equal to the number of folds.

When the paper is folded once, n equals one, therefore the thickness of the pile is 21 or two. When you fold it again, the thickness is 22 or 2 x 2 = 4. After the seventh fold, the thickness of the stack is 27 = 2 x 2 x 2 x 2 x 2 x 2 x 2 = 128.

What prevents the paper from folding any further is its inability to wrap around the thickness of the stack.

If you measure a stack of 10 sheets of paper, you�ll find that they have a thickness of approximately one millimetre. Therefore, each sheet averages 0.1 millimetres thick.

If this sheet were folded in half seven times, then its thickness would be 12.8 mm.

What if it was possible to continue folding the paper? Amazingly, the stack of paper would be over 1.6 metres thick (as tall as you are), after the 14th fold!

In fact, by the 28th fold it would be higher than Mount Everest and only five more folds would see it tower past the Moon (over 400 000 kilometres).

Many organisms, such as bacteria, multiply according to this simple mathematical principle. It�s amazing how a simple thing like doubling can cause such a rapid increase.

[lia*]

after reading this question, i decided to try. well, i could barely make it to the eight fold.

[anthomson]

When I was a kid in the 70/80's I remember them doing this experiment on Magpie (ITV equilvalent of Blue Peter). They got an absolutely hugh sheet of paper and used a brush between each fold to remove air. I belive they managed about 12 folds. It was certainly more than seven.

[CT]

It's usually a standard piece of A$ that can't be folded more than seven times. I guess if it's a bit thinner than normal, then more might be possible.

[JudgeJ]

I don't know where the arithmetic came from in your cut & paste, PhilBy. I�m right with you up to 1.6m. However, by the 27th fold the paper would have reached 13.4 km � considerably exceeding Everest�s 8.8km. It would take another 25 folds (making 52) to reach the 400,000km to the Moon. After 33 it would only be 429km thick.