If the Universe is Teeming With Aliens... Where is Everybody?

Serious scientific answers to absurd hypothetical questions

The universe is weird. Existential short stories by Exurb1A

What if you could have made different choices in life?

I always thought it was cool when someone could make a plausible estimate from reasonable guesses. I recently learned that these are sometimes named after Enrico Fermi, the famous physicist, and its the same technique used to create his famous Fermi paradox. You build a rough logic chain using a few sliders and fixed quantities (e.g. weeks per year), and the goal is to get within an order of magnitude of the true answer. The math is simple; the thinking is the game. Would love feedback.

Energy, evolution, and the origins of complex life

Some months ago @andrewrn tried to create a Wordle-style site for order-of-magnitude thinking. This was a wonderful idea, but the actual site was somewhat over-engineered and confusing. (https://news.ycombinator.com/item?id=43632278) In the past week, I looked at this idea again and built a very simple site which gives you a new Fermi estimation question every day: How many new cars were sold in the US in 2024?; How many humans have ever lived (including those currently alive)?; How many chickens are slaughtered for meat every year? To win, you need a guess within ±20% of the…