Fermi’s Paradox and Galaxy Probes

January 21, 2007

The Fermi paradox (1950) can be formulated as follows

If there are extraterrestrial civilizations out there, then where are they?

In a recent paper, Rasmus Bjork of the Niels Bohr Institute argues that finding other life in the Galaxy by using space probes, and possibly solving the paradox, might take extremely long time. A time which is comparable to the age of the universe. More precisely, he estimates that with 8 probes each having 8 subprobes around 4% of the Galaxy can be explored in 9.6 billion years.

So, if we sometimes feel lonely in the Universe it is because Aliens still haven’t had the time to visit us…

See also the discussion at Mangan’s Miscellany.


The End of Astrology?

August 24, 2006

It has just been decided by the International Astronomical Union (IAU), that Pluto has lost its status as a planet.

A “planet” is now defined as (IAU):

…a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

Pluto fails on the third criteria, (c).

Does this mean the end of astrology? What theories will be invented to revive it?

Well, I’m sure it’s not the end of days for astrologers (and other crackpots) yet – for example, you can still obtain a free computer-generated horoscope here.

Update: there is a critical discussion about the definition of a “planet”, and whether we should really care much about such a definition, at Bad Astronomy; and Alan Stern, leader of NASA’s New Horizon’s mission to Pluto, thinks that the definition stinks.