How to Predict the Future

I should say something about predicting the future here. As soon as you get fog, that's exponential fall off. You lose a certain fraction of the light per unit distance. And so relative to what you're used to, which is quadratic fall off, fog, you can see the first time to just perfectly clearly. That makes you think you're going to be able to see 1000 years moderately clearly. But actually, 200 years a wall comes down and you can't see anything beyond 200 yards. We're hopeless, a predicting future in the long term.