Saturday, April 02, 2005

Numb3rs 1x08

Really good stuff in this episode. At last a question I had in my mind for years was resolved:

- How do we know that everyone has their own unique fingerprint?

- Because no 2 people have ever been found to have the same prints. It's an assumption we make based on 100 years of empirical evidence.

- How often does one part of someone's print resembles someone else's?
- We've never done this type of population surveys.
- Isn't random match propability the only way you have of knowing the likelihood of two prints matching?

- Random match is used in DNA analysis.

- Exactly. That's why when experts make a DNA match they don't say it's a sure thing. They say it is 1 in 4 billion chance that the DNA comes from the same person. But fingerprints don't have odds. They just match or they don't match...

Plus a small dose of Quantum Mechanics:

- It's like the evidence proves him rigth and wrong at the same time.
- Oh, yeah, the old paradox oh Schrodinger's cat. There is a cat in a box, 50-50 chance it's been poisoned. But now here's the paradox: until such time as we can open the box and observe the cat, for that time, that cat is both alive and dead.
- I fail to see the analogy though. In reality he can't be both right and wrong at the same time.
- No no no... The truth with Schrodinger's cat is that the question itself is meaningless until we look inside the box.