Favorite Paradoxes

You know you’re a geek when…
You name a blog entry Favorite Paradoxes

The Birthday Paradox

I love probability. (I was even a math major for a while in college.) One example of explaining probability theory in real life is the Birthday Paradox: Given a group of 23 (or more) randomly chosen people, the probability is more than 50% that at least two of them will have the same birthday. For 60 or more people, the probability is greater than 99%.

I've tried it out at a few parties I've attended over the years, and it has always held true. Try it the next time you’re with a large group of people.


The Grandfather Paradox

I've always been fascinated with time travel. The Grandfather Paradox states: Suppose you traveled back in time and killed your biological grandfather before he met your grandmother. As a result, one of your parents (and by extension, you) would never have been conceived. But this would imply you could not have traveled back in time after all, which in turn implies your grandfather would still be alive and you would have been conceived, allowing you to travel back in time and kill your grandfather.

There are theories on how to get around this paradox – such as the creation of a parallel universe by your actions or the laws of nature forbidding the action – but I’ll have to tackle those in another entry.

I’ll leave you with this link to a web site called Temporal Anomalies in Time Travel Movies that discusses most of the popular time travel movies. I've spent hours there! I think my favorite entry at that site is the one that discusses the 1986 Disney movie Flight of the Navigator.