A Walk in the Woods

By Bill Bryson

Bryson walked 800 miles of the Appalachian trail. The full trail is over 2000 miles. At one point in the book, he muses over the contrast-- 800 miles is a amazing amount of hiking, yet he is a failure at hiking the whole trail.

Part travelog, and part history, the book is a good read.

Symmetry and the Monster: One of the greatest quests of mathematics

By Mark Ronan.

I took a lot of Group & Ring theory in University. What I like about the book Symmetry and the Monster is that it discusses much of the history behind Group theory. I got a better sense of the people who were involved and the problems they were trying to solve.

Said another way, in school I learnt many mathematical theories that could be used to do various things, or solve various problems. SATM tells the story of these people, and the problems they were trying to solve.

My one complaint is that the author sometimes uses easy to remember phrases instead of technical terms. While it makes things a little easier to read, it also makes it more difficult for me to branch out from the book, to the actual mathematics being discussed.

Through two doors at once

By Anil Ananthaswamy

This is a good history of the double slit experiment in physics.

Amongst other things, the book describes a variation of the double slit experiment that took place on the canary islands. This experiement confirms that QM & Nature really doesn't want you to know the position and velocity of a partical, even if it means going back into the past to erase the evidence.

1. Start out with the normal double slit experiement. This shows that a partical can be a wave.

2. Put filters in front of the two slits such that horizontal polarized photons only pass through one slit and vertical polarized photons pass through the other. The double slit experiement still works. If you know the polarization of the photon, then the interference goes away.

3. Create a stream of engtangled photons. Send on half of the engtagled pair to the slits. Send the other away.

4. If you put a polarizer in front fo the photos that were fired away from the experiment, then the interference pattern goes away when you use the polarizer to filter out H or V photons. Filtering entangled photons still causes interference patterns to happen, or go away, as appropriate.

5. Move the filter added in step #4 miles away from the experiment. Randomly choose the polarization position after the entangled particle has hit the screen. The interference pattern will still appear (or dissappear) even if you choose to look at the entangled-away-photon long after the entangled-slit-photon has hit the screen.