Irish Class, July 8, 2013
Rang Gaeilge, 8 lá Mí na Iúil 2013
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Monday Night Irish Class, July 8, 2013
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Fractal Humor
What does the B stand for in Benoit B. Mandelbrot?
Thinking Globally
We have had some chilly months here in Minnesota, but ….
Earth had third warmest May on record (tie with 1998 and 2005)
The global temperature has been above average now 339 straight months (more than 28 years). The last time global temperatures were below average (February, 1985), the Chevrolet Celebrity was among the top selling cars.
More on the problems of PRISM
Thomas Bayes looks through the NSA’s “Prism”
This story has received a lot of coverage in the last few days, even extending to Jay Leno’s monologue. Understandably, there is a lot of concern about the civil liberties implications. But there is also another question, answered by Corey Chivers: How likely is the NSA PRISM program to catch a terrorist?
We don’t really know anything about how PRISM works (NSA = Never Say Anything), but with some plausible assumptions we can estimate the answer. Suppose
- If a terrorist is in the system, the probability is 99% that PRISM will flag him/her.
- An good guy has only a 1/100 chance of being flagged as potential terrorist.
- The actual number of terrorists is quite small, say 1 in 1,000,000.
Using Bayes’ rule, Chivers shows that only 1 in 10,102 of the people flagged as suspects will actually be a terrorist!
Continue reading
Bayes’ Rule in daily life
From Bayes: How one equation changed the way I think
Bayes’ Rule is a simple formula that tells you how to weigh evidence and change your beliefs. I don’t go around plugging numbers into a formula all the time, but nevertheless, becoming familiar with Bayes has shifted the way I think in some important ways.
Monday Night Irish Class, June 3, 2013
Irish Class, JUne 3, 2013
Rang Gaeilge, 3ú lá Mí na Mheiteam 2013
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Now you see it, now you don’t
No Planet of Alpha Centauri B?
Last October astronomers announced big news: the discovery of a rocky, scorching hot, Earth-sized planet circling our closest stellar neighbor, the orange dwarf star Alpha Centauri B just 4.3 light-years away. Exoplanet astronomer Debra Fischer (Yale) told the New York Times that the planet next door was the “story of the decade.” Almost lost in the excitement was the caveat that the planet’s detection was still iffy and required heroic efforts to extract any sign of it from the background noise of the star’s radial-velocity measurements.
Now the plot has become more muddled. A new analysis of the data by an independent researcher has failed to confirm the planet’s existence.
How to resolve this issue: Get a lot more data. Everybody involved agrees on that. This is science at work. Finding a planet in the Alpha Centauri system would be really cool (ask any science fiction fan), but we need to be sure it is really there.
Dark Age Greece
The Lost Community of Lefkandi
I particularly noticed:
From around 1250 BC onwards, post-Mycenaean ‘refugee’ settlements began to appear, establishing a pattern that was to continue throughout the Dark Ages (Whitley 2011: 77-78). The characteristic Dark Age remote, defensible positions, often over 500m above sea level – as in evidence at Karphi (ibid: 78) – exhibited a continuity of older traditions and no obvious change in population levels (ibid.).
This pattern was noted by Robert Drews in The End of the Bronze Age as evidence that the disasters in the Eastern Mediterranean c. 1200 BC were the result of human action, not natural causes. The only reason the survivors would rebuild in such difficult locations is fear of an attack by raiders or invaders. See also my post on From Bronze to Iron.
More on Dyson Spheres and similar feats of mega-engineering
Hunting for Alien Megastructures
See also The Best Way to Find Aliens: Look for Their Solar Power Plants, which I referenced here and the Chicon Dyson Sphere Update.
From Hilbert Space to Dilbert Space, and beyond 