Got asked this one this morning – a classic philosophical question which one can argue over endlessly. What interests me most about this question is the effect quantum mechanics has on the question. If we apply quantum mechanics, the question changes and becomes:
If a tree falls in the forest, and there’s no-one there to see it, does it fall at all?
Quantum mechanics tells us that in fact it falls, and it doesn’t fall. Both states exist as possibilities until someone comes walking through the forest to look at the tree. As soon as they observe the tree, the wave function collapses and the tree decides whether or not it fell yesterday, last week or last year. If it turns out it did fall, it rushes back in time, and falls. The observer just sees a tree that fell at some time in the past.
If you think that’s confusing, just check out quantum tunneling!
