Naked Science Forum

General Science => General Science => Topic started by: Eric A. Taylor on 26/02/2011 00:05:31

Title: Is a book who's pages are in order at a low entropy?
Post by: Eric A. Taylor on 26/02/2011 00:05:31

Entropy is the number of ways you can arrange the parts in a system. The book I'm reading (Fabric of the Cosmos by Brian Greene. He stated that the book War and Peace with the pages in the correct order is in a state of low entropy while if the pages are scrambled it's high entropy. I think this is wrong because no mater what order you randomly place the pages in the chances of THAT order are the same whether it's 1, 2, 3, 4... or 3, 1, 4, 2... or whatever.

We're biased when it comes to letters or numbers because they have a "correct" and "incorrect" order. But both letters and numbers are really just arbitrary. To a person unfamiliar with Latin letters or Arabic numbers the way they are arranged can be completely arbitrary.

I'd argue that a book with say 900 pages has the same entropy no matter what way the pages are arranged as long as they are stacked neatly like you find in most books (I really hate the "rough cut" style of pages in some book) but I could be wrong. Brian Greene has a PhD and I'm just a dumb welder...

Title: Is a book who's pages are in order at a low entropy?
Post by: Madidus_Scientia on 26/02/2011 03:30:14

I agree that its not really a good analogy, and that the chance of any specific sequence occurring would be equal, but maybe he means because the book starts in that sequence, any shuffling will drive it away from that?

Title: Is a book who's pages are in order at a low entropy?
Post by: Eric A. Taylor on 26/02/2011 10:23:20

Quote from: Madidus_Scientia on 26/02/2011 03:30:14

I agree that its not really a good analogy, and that the chance of any specific sequence occurring would be equal, but maybe he means because the book starts in that sequence, any shuffling will drive it away from that?

He's trying to explain entropy which is commonly misunderstood as the amount of disorder in a system. It's really the number of different ways it could be ranged.

It's like one of those locks with the wheels with numbers. you need to spin the numbers so the correct combination is reached. A lock with 3 wheels will have 999 incorrect combination (you'd have 1 chance in a thousand of guessing the right one) where a 4 wheel lock will have 9999 incorrect combination.

The German Enigma machine worked in this way. At the start of the war it had four wheels (I don't know how many different settings each wheel had) after the English captured one they were reading the orders for the U-boats before their captains. When the Germans added another wheel to Enigma it shut off this flow of information.

Title: Is a book who's pages are in order at a low entropy?
Post by: ricbritain on 27/02/2011 04:31:08

That's a fantastic book isn't it. I took me several attempts to get through as each tine I stopped for a few weeks I had to go back to the beginning again, but it gets better as you get through it.