NYT Guesstimation Quiz. Enrico Fermi estimated the yield of the Trinity A-bomb test by dropping some shredded paper. He also asked his students to estimate unusual quantities like the number of piano tuners in Chicago - to show that just about anything can be estimated without detailed knowledge.
posted by Electric Dragon on Apr 1, 2009 - 54 comments

In March 2007, the FermiLab Office of Public Affairs in Batavia, IL "received a curious message in code" via USPS. In May 2008, scientists posted a facsimile image of the letter to their blog in the hopes of soliciting cryptologists to decipher the letter. [more inside]
posted by subbes on Jul 16, 2008 - 45 comments

The "Great Filter" is a hypothetical barrier to explain why civilisations are so unlikely to progress to the point of inter-stellar colonisation that we have not encountered any in 40 years of looking. Maybe humanity has already negotiated the filter - as some massive evolutionary improbability - or perhaps it lies in our future as an almost-certain threat to our existence? We should hold our breath as we look for evidence of life on Mars.
posted by rongorongo on May 12, 2008 - 85 comments

A View from the Back of the Envelope - approximations and the fun behind them.
posted by Gyan on Oct 18, 2005 - 25 comments

The site of the world's first nuclear reactor? Gabon. About 1.7 billion years ago several deposits of uranium in Oklo, Gabon spontaneously began to undergo nuclear chain reactions fed by small drips of water. These natural breeder reactors ran for almost a million years, producing both intense heat and plutonium byproducts. Aside from the strangeness of naturally occurring reactors, Oklo provides the only existing case of how highly radioactive waste behaves over a period of tens of millions of years -- exactly the problem faced by the DOE's Yucca Mountain nuclear waste site.
posted by blahblahblah on Feb 16, 2005 - 19 comments

Another thwack at answering Fermi's question. Which is, after scribbling a fairly convincing equation on the blackboard, "If there's intelligent life out in the universe, where are they?" An interesting sidelight is the principal donors: Paul Allen and Nathan Myhrvold of Microsoft... Both of whom are known for unverifibly abstract big-picture thinking, but maybe it'll pay off this time...
posted by aurelian on Aug 1, 2000 - 0 comments