Saturday, January 26, 2013

Where Are All The Aliens - Ted Talk

If you like science, mysteries, and cosmic-scale ideas, then you’re going to love a recent TED talk by Anders Sandberg. In his presentation, Sandberg discusses the Fermi Paradox, first posed by Enrico Fermi in 1950.



What exactly is the Fermi Paradox, you ask? Well, according to Wikipedia:
The Fermi Paradox (or Fermi’s paradox) is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilization and humanity’s lack of contact with, or evidence for, such civilizations. The basic points of the argument, made by physicists Enrico Fermi and Michael H. Hart, are:
  • The Sun is a young star. There are billions of stars in the galaxy that are billions of years older;
  • Some of these stars likely have Earth-like planets which, if the Earth is typical, may develop intelligent life;
  • Presumably some of these civilizations will develop interstellar travel, as Earth seems likely to do;
  • At any practical pace of interstellar travel, the galaxy can be completely colonized in just a few tens of millions of years.
According to this line of thinking, the Earth should have already been colonized, or at least visited. But no convincing evidence of this exists. Furthermore, no confirmed signs of intelligence elsewhere have been spotted, either in our galaxy or the more than 80 billion other galaxies of the observable universe. Hence Fermi’s question, “Where is everybody?”
As you’ll see in the video, no discussion of Fermi’s Paradox is complete without an attempt to estimate how many alien civilizations are out there, which quickly leads to the Drake Equation, which is a simple mathematical tool used to statistically estimate how many intelligent, technological races are likely to exist in our galaxy and the universe at large. Again quoting from The Hitchhiker’s Guide, er, Wikipedia, the original formulation of the Drake Equation was:
N = R* fp ne fl fi fc L
where:N = the number of civilizations in our galaxy with which communication might be possible (i.e. which are on our current past light cone);
and
R* = the average rate of star formation per year in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of the above that actually go on to develop life at some point
fi = the fraction of the above that actually go on to develop intelligent life
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space
Depending on the values you choose for any of the coefficients, you can calculate wildly varying estimates of the number of civilizations in our galaxy. Drake’s initial estimate was that there are probably between 1,000 and 100,000,000 civilizations in our galaxy alone. Of course, the appearance of intelligence involves many other factors beyond the basics Drake considered, so there are numerous variants on his calculation, and plenty of opportunity for people to argue about the values of the coefficients.
As expected, the Drake Equation is discussed in Anders Sandberg’s TEDx talk below. Sandberg is a researcher at Oxford University. His work centers on societal and ethical issues surrounding human enhancement, new technology and global catastrophic risks, which explains his interest and expertise on the issues involved in the Fermi Paradox:

And finally, if you’re interested in whimsical answers to the Fermi Paradox, check out Terry Bisson’s short story, They’re Made of Meatat the author’s website


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