Monthly Archives: May 2010

Never the Twain Shall Meet

Posted on by

Never, in this case, is 100 years.

After keeping us waiting for a century, Mark Twain will finally reveal all

The creator of Tom Sawyer, Huckleberry Finn and some of the most frequently misquoted catchphrases in the English language left behind 5,000 unedited pages of memoirs when he died in 1910, together with handwritten notes saying that he did not want them to hit bookshops for at least a century.

That milestone has now been reached, and in November the University of California, Berkeley, where the manuscript is in a vault, will release the first volume of Mark Twain’s autobiography.

OK, what gets me is not that Samuel Clemens aka Mark Twain, did not want his autobiography released until 100 years after his death. What gets me is that he died April 21, 1910, and the first edition won’t be out until November of 2010. What? Not enough lead-time to get the project done?

GPS, New and Improved

Posted on by

GPS is getting an $8-billion upgrade

[S]cientists and engineers — including those at a sprawling satellite-making factory in El Segundo — are developing an $8-billion GPS upgrade that will make the system more reliable, more widespread and much more accurate.

The new system is designed to pinpoint someone’s location within an arm’s length, compared with a margin of error of 20 feet or more today. With that kind of precision, a GPS-enabled mobile phone could guide you right to the front steps of Starbucks, rather than somewhere on the block.

The story mentions that a predecessor of GPS was Transit, to support Polaris submarines. I went to a talk recently which mentioned other programs as well: there was SECOR (SEquential COllation of Range), 621B and TIMATION. I found a brief history of these programs. The military was testing various strategies for geolocation, and each had its strengths and weaknesses. You could have the satellites be autonomous or rely on ground stations; autonomous satellites need good space-qualified clocks, which were tough to come by in the 60s, but if ground station was lost, the whole system would go down. Orbital altitude was another variable — geostationary satellites had poor coverage at high latitudes, but you required more satellites as you got into lower orbits, with progressively shorter observation windows. (A low-earth orbit (LEO), like the ISS, would require of order 100 satellites for good coverage) And various communication strategies could be employed.

They were able to draw on the experiences of each program and come up with a system that seems to have worked out pretty well.

Mmmm. Haaaash.

Posted on by

Built on Facts: Sunday Function

Take an integer – one of at least several digits – and multiply it by itself twenty times. The result is going to be some really gargantuan number. Take the last 10 digits of that number. That’s the output of our function, which we’ll call h(n).

…

The resistance can use this property of hash functions to make their resistance network more secure. Instead of distributing a list of all the agent’s passwords, the resistance can distribute a list of the hashes of their passwords. Thus if Bob knows that Alice’s hash is 7001140801, Alice can verify her identity by saying that her password is 314159, which has that as its hash. But if a Nazi double agent (let’s call her Eve) has managed to steal the list of hashes, she still can’t impersonate Alice. Eve doesn’t know what password to use to generate that hash. She could try thousands or millions of guesses and hope that eventually she found one with a hash that matches Alice’s hash, but with all the possible hashes that would be a herculean task.

Screwball Spotting

Posted on by

Hermits and Cranks: Lessons from Martin Gardner on Recognizing Pseudoscientists

Martin Gardner died Saturday. I’ve read some of his books, and I think also a few of his columns when I would read Scientific American in the science library in college. His description of crackpot characteristics is still spot-on.

(1) “First and most important of these traits is that cranks work in almost total isolation from their colleagues.” Cranks typically do not understand how the scientific process operates—that they need to try out their ideas on colleagues, attend conferences and publish their hypotheses in peer-reviewed journals before announcing to the world their startling discovery. Of course, when you explain this to them they say that their ideas are too radical for the conservative scientific establishment to accept. (2) “A second characteristic of the pseudo-scientist, which greatly strengthens his isolation, is a tendency toward paranoia,” which manifests itself in several ways:

(1) He considers himself a genius. (2) He regards his colleagues, without exception, as ignorant blockheads….(3) He believes himself unjustly persecuted and discriminated against. The recognized societies refuse to let him lecture. The journals reject his papers and either ignore his books or assign them to “enemies” for review. It is all part of a dastardly plot. It never occurs to the crank that this opposition may be due to error in his work….(4) He has strong compulsions to focus his attacks on the greatest scientists and the best-established theories. When Newton was the outstanding name in physics, eccentric works in that science were violently anti-Newton. Today, with Einstein the father-symbol of authority, a crank theory of physics is likely to attack Einstein….(5) He often has a tendency to write in a complex jargon, in many cases making use of terms and phrases he himself has coined.