Unequally Yoked
I’m totally delighted by these mischievous bridges. Euro notes apparently each feature a picture of a bridge, drawn in different architectural styles, but none modelled on a real bridge, so that the nations of the EU wouldn’t be divided into “included in/excluded from currency” factions. But the Netherlands has scuppered that compromise — they’ve built all seven!
The local council responsible for constructing a new housing development in Spijkenisse, a suburb of Rotterdam, heard about the idea and approached Stam about using his designs.
…The bridges are exact copies of those shown on the banknotes, down to the shape, crop and colour.
“I wanted to give the bridges an exaggerated theatrical appearance – like a stage set,” adds Stam, who poured dyed concrete into custom-made wooden moulds to make them.
Stam converted these fictional bridges into real live spans, and, in this next link, scientists converted real-life pulses into drawings, and ,now, have reconverted them into sound.
Until the mid-19th century, charting a pulse required the doctor to cut into an artery and place a metal device or a glass tube inside. There were no human volunteers, and studies were limited to animals. The first known recording occurred Dec. 12, 1846, when a German physician, Carl Ludwig, took the pulse of a horse.
It was Karl von Vierordt, a German physiologist, who invented the elaborate device that charted human pulses noninvasively. He called it thesphygmograph, or “pulse writer,” and in 1854 he used it to trace 45 feeble pulses of Johann Hahn, a 71-year-old patient who suffered from pulmonary emphysema.
Now that these paper records have been digitized, we can listen to the heartbeat of a man who was born in 1769.
And speaking of visualizing sounds and rhythms, Flowing Data provides this link to a “pianogram” — a histogram of the relative frequency of notes in a song.
This one is Rachmaninov’s Prelude in C-Sharp.
Ach, you may say, it’s all very well using computers to graph songs, but where will we be when they get out of hand? Well, you probably won’t be reassured by this next link, “Watch As A Hacker Frees This Telepresence Robot From Its Confinement.” A telepresence robot company let people test drive their robot, which was safely shut up in a conference room.
The operative word in that last sentence is “was.”
The persistence and cleverness of the person who piloted the robot out of its chamber is fun to watch, but also a good reminder that limited machines can be used for more than just their intended purposes, whether animated by mischievous humans or insufficiently precise code.
I’m pretty sure I know at least one person who’d be hesitant about using a telepresence robot anyway, for fear of getting motion-sick. Which brings me to this interesting Nautilus story on treatment for mal de debarquement syndrome (the swaying feeling that you’re at sea, long after your cruise is over).
On Monday, during Perry’s first treatment session, Dai set out to measure her perceived motions. Perry stood on a Wii Balance Board that contains pressure sensors; on a connected computer, Dai and a colleague watched Perry’s center of balance shift in a slow, clockwise circle. Next the doctors told Perry to sit down, strapped an accelerometer to her wrist, and asked her to move her arm in time with her perceived circular swaying motions. Both of these tests revealed the same frequency of motion: Perry’s internal deck was completing its rocking motion once every seven seconds.
Once the scientists knew the period of Perry’s phantom swells, they could work on retraining her brain and her balance. The trick they use is pretty cool, and you can find it in the full story.
Can I tell a story abounding in pilish using its trick? Alleluia!
Ok, back to Standard English. Pilish is an English variant, which constrains how long all your words can be. You must start with a three letter word, then a one letter one, then four, then one again, then five, and by now you’ve probably twigged that the pattern of pilish is the digits of pi. Turns out people have written poems and even novellas in this form, but I would have had trouble with just the twelve words above, were it not for scrabble dictionaries that let you search by length of word.
Pilish is a joke that relies on math, but isn’t a particularly mathy matter, itself. But this final link, an explanation of zero-knowledge proofs, is fascinating, and it’s written for laypeople, so please give it a try–I was awestruck by this topic. I’ll give you the lead-in here, and I really recommend going over for the explanation:
Prior to Goldwasser et al., most work in this area focused the soundness of the proof system. That is, it considered the case where a malicious Prover attempts to ‘trick’ a Verifier into believing a false statement. What Goldwasser, Micali and Rackoff did was to turn this problem on its head. Instead of worrying only about the Prover, they asked: what happens if you don’t trust the Verifier?
The specific concern they raised was information leakage. Concretely, they asked, how much extra information is the Verifier going to learn during the course of this proof, beyond the mere fact that the statement is true?
It’s important to note that this is not simply of theoretical interest. There are real, practical applications where this kind of thing matters.
Here’s one: imagine that a real-world client wishes to log into a web server using a password. The standard ‘real world’ approach to this problem involves storing a hashed version of the password on the server. The login can thus be viewed as a sort of ‘proof’ that a given password hash is the output of a hash function on some password — and more to the point, that the client actually knows the password.
Most real systems implement this ‘proof’ in the absolute worst possible way. The client simply transmits the original password to the server, which re-computes the password hash and compares it to the stored value. The problem here is obvious: at the conclusion of the protocol, the server has learned my cleartext password. Modern password hygiene therefore involves a good deal of praying that servers aren’t compromised.
What Goldwasser, Micali and Rackoff proposed was a new hope for conducting such proofs. If fully realized, zero knowledge proofs would allow us to prove statements like the one above, while provably revealing no information beyond the single bit of information corresponding to ‘this statement is true’.
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