Scale model of the Earth and the Moon, with a beam of light travelling between them at the speed of light. It takes approximately 1.26 seconds.
Wikipedia, via Jorn Barger.
Scale model of the Earth and the Moon, with a beam of light travelling between them at the speed of light. It takes approximately 1.26 seconds.
Wikipedia, via Jorn Barger.
Caltrain commuters accustomed to facing long delays without warning will finally be able to check ahead and see if their train is running on schedule.
Caltrain officials said this week they have reached a deal with a private vendor to install global positioning system trackers in their locomotives, and use the sensors to provide real-time delay information to riders.
The expected arrival times of trains will appear at existing electronic signs at all station platforms from San Francisco to San Jose, on 511.org and by calling 511. The project should allow riders to determine ahead of time whether they should instead drive or take comparable routes such as BART north of Millbrae or Valley Transportation Authority light rail south of Palo Alto.
The project will cost $1.8 million and is part of Caltrain’s $8.7 million initiative to install a new rail operations control system. The agency’s board of directors is expected to approve the contract Thursday, though it is unknown when the system will start running.
Caltrain’s roughly 40,000 average weekday riders have grown frustrated over lack of access to official real-time delay information. Fed up, they took matters into their own hands in May 2008 by launching a Twitter feed with delay information that has attracted roughly 3,000 followers.
In the meantime, the Twitter feed is useful.
The water-policy debate in California, more often than not, ignores the fact that the lion’s share of water (hmm, that doesn’t really make sense, but…) goes to agriculture, and in particular to crops such as rice and cotton that really shouldn’t be grown in an arid state.
This is a good move, though the acreage is minuscule compared to major crops (a quick check shows more than half a million acres of rice in California in 2004).
An oil boom is underway in the state’s agricultural heartland, as evolving tastes and a trend toward healthy fare have transformed a profession as old as civilization: olive production for the extra virgin market.
Gnarly trees picked by hand are being supplanted. This year California’s olive oil production will top 1 million gallons for the first time, the lion’s share from 8-foot trees planted in hedgerows and mechanically harvested, then pressed into oil within 90 minutes.
Growers have invested millions laying the groundwork to become a player in the global olive oil market, now controlled by Spain, Italy and Greece.
In the past 10 years, roughly 7.5 million trees have been tightly planted on 12,500 acres, an experiment growers hope will make California olive oil cheaper and fresher than that of their competitors. State officials estimate that in another decade there will be 100,000 acres of hedgerow trees producing 20 million gallons of oil to help sate Americans’ 75 million gallons-a-year thirst — 99.99 percent of it now imported.
The Condorcet voting paradox, in voting theory, says that it’s possible to have (for example) three candidates A, S & V such that the voters collectively prefer A to S, S to V and V to A. It sounds impossible, but that’s why it’s called a paradox.
There seems to be something like that for cellphone service providers. Sprint is bad. AT&T is worse than Sprint. Verizon is worse than AT&T. And Sprint is worse than Verizon. Follow that?
Sprint has the worst coverage by far, though I use it because it happens to cover my house in the boonies. iPhone lovers hate AT&T, and many iPhone prospects won’t buy one until it show up on another network. So that leaves Verizon, right? Not so fast, says David Pogue.
… The more Verizon gouges, the worse it looks. Every single day, I get e-mail from people saying they’re switching at the first opportunity, or would if they could. In time, the only people who will stay with Verizon are people who have no coverage with any other carrier.
Every company’s dream, right? A base of miserable customers who stick with you only because they have no choice. …
Each provider is worse than all the others. That’s Condorcet’s paradox applied to cellphones. As Pogue asks,
Why wouldn’t it be a hugely profitable move to start pitching yourself as the GOOD cell company, the one that actually LIKES its customers?
That, of course, is crazy talk. Next thing you know he’ll be suggesting that there could be a GOOD airline company, and we’ll have to call the men in the white coats.
More than a year after an explosion of sparks, soot and frigid helium shut it down, the world’s biggest and most expensive physics experiment, known as the Large Hadron Collider, is poised to start up again. In December, if all goes well, protons will start smashing together in an underground racetrack outside Geneva in a search for forces and particles that reigned during the first trillionth of a second of the Big Bang.
Then it will be time to test one of the most bizarre and revolutionary theories in science. I’m not talking about extra dimensions of space-time, dark matter or even black holes that eat the Earth. No, I’m talking about the notion that the troubled collider is being sabotaged by its own future. A pair of otherwise distinguished physicists have suggested that the hypothesized Higgs boson, which physicists hope to produce with the collider, might be so abhorrent to nature that its creation would ripple backward through time and stop the collider before it could make one, like a time traveler who goes back in time to kill his grandfather.
Holger Bech Nielsen, of the Niels Bohr Institute in Copenhagen, and Masao Ninomiya of the Yukawa Institute for Theoretical Physics in Kyoto, Japan, put this idea forward in a series of papers with titles like “Test of Effect From Future in Large Hadron Collider: a Proposal” and “Search for Future Influence From LHC,” posted on the physics Web site arXiv.org in the last year and a half.
According to the so-called Standard Model that rules almost all physics, the Higgs is responsible for imbuing other elementary particles with mass.
“It must be our prediction that all Higgs producing machines shall have bad luck,” Dr. Nielsen said in an e-mail message. In an unpublished essay, Dr. Nielson said of the theory, “Well, one could even almost say that we have a model for God.” It is their guess, he went on, “that He rather hates Higgs particles, and attempts to avoid them.”
This malign influence from the future, they argue, could explain why the United States Superconducting Supercollider, also designed to find the Higgs, was canceled in 1993 after billions of dollars had already been spent, an event so unlikely that Dr. Nielsen calls it an “anti-miracle.”
xkcd is particularly profound:
Geoff Pullum at Language Log. He’s right, I suppose, but this is one of those cases in which any apology at all must be too little, too late. Too late not just for the obvious reason that any apology for this sorry series of events would have been too late after the fact, but also because it can no longer come (or at least does not come) from those directly responsible (Brown was born three years before Turing died). Still.
In an age where (as Language Log has often had occasion to remark) many purported public apologies are just mealy-mouthed expressions of regret (“I’m sorry it all happened”), or grudging self-exculpatory conditionals (“If some people think I shouldn’t have said it, I’m sorry they were upset”), it is good to see a genuine and direct apology for once, addressed (though more than half a century too late) to a man who deserved admiration, gratitude, and respect, but was instead hounded to death. The UK Prime Minister, Gordon Brown, has released a statement regarding the treatment of Alan Turing in the early 1950s, and the operative words are:
…on behalf of the British government, and all those who live freely thanks to Alan’s work I am very proud to say: we’re sorry, you deserved so much better.
That’s how to say it (ignoring the punctuation error — the missing comma after work): not a bunch of evasive mumbling about how unfortunate it all was, but a simple “We’re sorry.”
Turing did indeed deserve so much better. He created modern theoretical computer science; opened fundamental new areas of mathematical logic; made very important contributions to other areas of mathematics (e.g., the technique known as Good-Turing frequency estimation in statistics); and most importantly, he gave up his academic work during the Second World War to work at Bletchley Park on the extremely difficult task of decrypting German communications encrypted with the Enigma machine. The Bletchley Park team did succeed, and thus the Royal Navy became able to read the content of all the Nazis’ messages to U-boats in the North Atlantic. It was a crucial turning point in the war. But a mere seven years later, a young man shared Turing’s bed for the night in Manchester, and later helped someone burgle the house, and Turing naively reported the theft to the police. The police reaction was to arrest Turing, because they guessed what had been going on. “Gross indecency” was the charge (it is the British legal euphemism for cocksucking). Turing had a choice between serving prison time or agreeing to chemical castration, a medicalized “cure” for his presumed abnormality. He bore the latter for two years and then took cyanide. The way British mid-20th-century sex law drove him to suicide was genuinely something for the country to be ashamed of. It was good to see the official apology (which hundreds of eminent scientists had asked the Prime Minister to express).
The Massachusetts Group Insurance Commission had a bright idea back in the mid-1990s—it decided to release “anonymized” data on state employees that showed every single hospital visit. The goal was to help researchers, and the state spent time removing all obvious identifiers such as name, address, and Social Security number. But a graduate student in computer science saw a chance to make a point about the limits of anonymization.
Latanya Sweeney requested a copy of the data and went to work on her “reidentification” quest. It didn’t prove difficult. Law professor Paul Ohm describes Sweeney’s work:
At the time GIC released the data, William Weld, then Governor of Massachusetts, assured the public that GIC had protected patient privacy by deleting identifiers. In response, then-graduate student Sweeney started hunting for the Governor’s hospital records in the GIC data. She knew that Governor Weld resided in Cambridge, Massachusetts, a city of 54,000 residents and seven ZIP codes. For twenty dollars, she purchased the complete voter rolls from the city of Cambridge, a database containing, among other things, the name, address, ZIP code, birth date, and sex of every voter. By combining this data with the GIC records, Sweeney found Governor Weld with ease. Only six people in Cambridge shared his birth date, only three of them men, and of them, only he lived in his ZIP code. In a theatrical flourish, Dr. Sweeney sent the Governor’s health records (which included diagnoses and prescriptions) to his office.
Boom! But it was only an early mile marker in Sweeney’s career; in 2000, she showed that 87 percent of all Americans could be uniquely identified using only three bits of information: ZIP code, birthdate, and sex.
Such work by computer scientists over the last fifteen years has shown a serious flaw in the basic idea behind “personal information”: almost all information can be “personal” when combined with enough other relevant bits of data.
If the coin is tossed and caught, it has about a 51% chance of landing on the same face it was launched. (If it starts out as heads, there’s a 51% chance it will end as heads).
In retrospect, this is not all that surprising. It’s good to keep in mind.
Commenter Michael Ash suggests a mechanism for compensating for the bias:
Flip the coin twice. If the first one is heads and the second tails, take one choice. If the first is tails and the second heads, take the other choice. If you get the same face both times, start over. This last part is key: you must start over and flip two more times, and keep flipping in pairs until you get two different faces. It’s not enough to just flip in sequence until you see a change. You have to completely discard the result and begin anew.
This works (I think), but only if the two flips are independent of each other, a non-trivial assumption.
Most days, I ride Caltrain to work. Setting aside its insane policy (not entirely its fault) of cutting service and raising fares as a means of dealing with just about any problem, my main gripe is that it’s really hard to get any prompt information about service and schedule problems. This despite the installation a couple of years ago of a centralized electronic billboard system that ought to be able to provide this information to all platforms in real time.
Well, technology to the rescue, just not Caltrain technology: Caltrain Tweets. The idea is this. Caltrain is full of passengers connected to the net (generally by mobile phone, since Caltrain has no wifi). Recruit those passengers as reporters, funnel the reports through Twitter (not forgetting the mobile-friendly version), and you’ve got a surprisingly effective real-time status system.
Here’s the feed so far this morning:
To use the service passively, just bookmark the main or mobile Twitter feed; no need for a Twitter account. The mobile feed works fine on my Palm Centro, whose web browser isn’t exactly state of the art.
To participate actively, visit the Caltrain Tweets and request a key that authorizes you to send your own messages (via email; again, no Twitter account required). (The key is a simple but effective measure to prevent spamming.) And next time you’re stuck on a late Caltrain (not all that common, but it happens), let the rest of us know; we’ll do the same for you.
Update: This was a busy morning, with several posts after those shown above. Simultaneously, here was the transit report from the SF Gate traffic site:
Transit: No Incidents Reported
511.org doesn’t even pretend to try.
You can generally trust xkcd to feed you the straight scoop. This piece is more than usually helpful. Listen, people: this is how we geeks do it. Really. Try this at home.
Listen to this fine NPR story on crows recognizing individual people. There’s a video on the page as well, but the original story is better than the video.
Aside from the inherent interest of the immediate story, it’s a nice example of science at work in the wild, where unexpected observations are investigated, complete with controls and new opportunities for research.
Betelgeuse, one of the brightest stars visible to the naked eye, has shrunk in diameter by more than 15 percent since 1993.
In 1921, Betelgeuse became the first star for which astronomers measured a size. Over the years, different interferometers, observing Betelgeuse over a wide range of wavelengths, have recorded diameters for the star that disagree with each other by as much as 30 percent. That’s not surprising because stars often look considerably bigger or smaller at different wavelengths. But the star hasn’t previously been found to vary significantly in size at any one wavelength, Townes says.
As hefty as 15 suns, Betelgeuse is nearing the end of its life and could soon go supernova. Continued close monitoring of Betelgeuse could lead to a better understanding of the evolution of massive stars near the end of their lifetime.
via Jorn Barger
New software has enabled researchers to recreate a long forgotten musical instrument called the Lituus.
The 2.7m (8.5ft) long trumpet-like instrument fell out of use some 300 years ago.
Bach’s motet (a choral musical composition) “O Jesu Christ, meins lebens licht” was one of the last pieces of music written for the Lituus.
Now, for the first time, this 18th Century composition has been played as it might have been heard.
Researchers from the Engineering and Physical Sciences Research Council (EPSRC) and the University of Edinburgh collaborated on the study. …
STS-125 is the Space Shuttle mission to update and repair the Hubble Space Telescope one last time. The second EVA (replacing gyros and batteries) is just now complete. I finally tracked down a real-time news feed that fits my needs; give it a try tomorrow.
Wikipedia has a nice article that includes a summary of the five EVAs.
Via Mark Thoma. Lots more, mainly on spurious data mining.
Laboratory experiments show that rats outperform humans in interpreting data… The amazing finding on rats is described in an equally amazing book by Leonard Mlodinow. The experiment consists of drawing green and red balls at random, with the probabilities rigged so that greens occur 75 percent of the time. The subject is asked to watch for a while and then predict whether the next ball will be green or red. The rats followed the optimal strategy of always predicting green (I am a little unclear how the rats communicated, but never mind). But the human subjects did not always predict green, they usually want to do better and predict when red will come up too, engaging in reasoning like “after three straight greens, we are due for a red.” As Mlodinow says, “humans usually try to guess the pattern, and in the process we allow ourselves to be outperformed by a rat.” …
In the last month or two, I’ve taken to using my MacBook Pro with an external monitor, keyboard and mouse, both at home and at my office. I don’t find a second monitor all that useful, so I went looking for a stand for the notebook that would minimize its footprint while not blocking access to its IO ports or DVD slot.
The purpose-built products I came across where either stunningly expensive, unavailable, or both. A friend suggested a cookbook holder, which sounded promising, but the wire holder I have was too flimsy for my largish (17″) notebook. But in searching for similar holders, I came across this:
It’s available via Amazon for $17 plus shipping. It’s sturdy, stable and attractive. I now have two, and recommend them for anyone with a similar application.
(On a related note, I was pleased to discover that you can get a very nice monitor for very little money, as long as you stay under 24″ or so. Even 24″ isn’t all that bad, but 22″ seems like a real sweet spot right now. I bought an HP w2207h for home use.)
Because, of course, you can’t spell πράγματος without π.
Pi Day is also Einstein’s birthday, so we’ll take as our text for today, “I want to know God’s thoughts; the rest are details.” I’ve been saving up a couple of links, so pay attention.
Here’s how it goes. Forget that we are “typical” or any such thing. Take for granted that we are exactly who we are — in other words, that the macrostate of the universe is exactly what it appears to be, with all the stars and galaxies etc. By the “macrostate of the universe,” we mean everything we can observe about it, but not the precise position and momentum of every atom and photon. Now, you might be tempted to think that you reliably know something about the past history of our local universe — your first kiss, the French Revolution, the formation of the cosmic microwave background, etc. But you don’t really know those things — you reconstruct them from your records and memories right here and now, using some basic rules of thumb and your belief in certain laws of physics.
The point is that, within this hypothetical thermal equilibrium universe from which we are purportedly a fluctuation, there are many fluctuations that reach exactly this macrostate — one with a hundred billion galaxies, a Solar System just like ours, and a person just like you with exactly the memories you have. And in the hugely overwhelming majority of them, all of your memories and reconstructions of the past are false. In almost every fluctuation that creates universes like the ones we see, both the past and the future have a higher entropy than the present — downward fluctuations in entropy are unlikely, and the larger the fluctuation the more unlikely it is, so the vast majority of fluctuations to any particular low-entropy configuration never go lower than that.
Therefore, this hypothesis — that our universe, complete with all of our records and memories, is a thermal fluctuation around a thermal equilibrium state — makes a very strong prediction: that our past is nothing like what we reconstruct it to be, but rather that all of our memories and records are simply statistical flukes created by an unlikely conspiracy of random motions. In this view, the photograph you see before you used to be yellow and wrinkled, and before that was just a dispersed collection of dust, before miraculously forming itself out of the chaos.
Note that this scenario makes no assumptions about our typicality — it assumes, to the contrary, that we are exactly who we (presently) perceive ourselves to be, no more and no less. But in this scenario, we have absolutely no right to trust any of our memories or reconstructions of the past; they are all just a mirage. And the assumptions that we make to derive that conclusion are exactly the assumptions we really do make to do conventional statistical mechanics! Boltzmann taught us long ago that it’s possible for heat to flow from cold objects to hot ones, or for cream to spontaneously segregate itself away from a surrounding cup of coffee — it’s just very unlikely. But when we say “unlikely” we have in mind some measure on the space of possibilities. And it’s exactly that assumed measure that would lead us to conclude, in this crazy fluctuation-world, that all of our notions of the past are chimeric.
Our spoilsport author goes on, “Now, just like Boltzmann’s Brain, nobody believes this is true,” but, just for Pi Day, let’s suspend our disbelief until tomorrow.
Speaking of Sean Carroll, we also have Michael Bérubé’s review of his forthcoming From Eternity to Here: The Origin of the Universe and the Arrow of Time.
Time just isn’t what it used to be. And space has gotten to be a bit of a problem, as well. When I was a lad, physicists told me that they had these things pretty well figured out: they had discovered material evidence of the Big Bang, they had adjusted their conception of the age and evolution of the universe accordingly, and, having recalculated the universe’s rate of expansion (after Hubble’s disastrous miscalculations threw the field into disarray), they were working on the problem of trying to figure out whether the whole thing would keep expanding forever or would eventually slow down and snap back in a Big Crunch. The key, they said, lay in finding all the “missing mass” that would enable a Big Crunch to occur, because at the time it looked as if we only had two or three percent of the stuff it would take to bring it all back home. When I asked them why a Big Crunch, and a cyclical universe, should be preferable to a universe that just keeps going and going, they told me that the idea of a cyclical eternity was more pleasing and comfortable than the idea of a one-off event; and when I asked them what came before the Big Bang, they patted my head and told me that because the Big Bang initiated all space and time, there was no such thing as “before the Big Bang.”
But now they tell me that most of that account of the world is wrong. For one thing, the expansion of the universe seems to be accelerating, which puts a crimp in the plans of everyone who’d been counting on its eventual collapse; worse still, no one can explain why it is that the universe is different now than it was, say, 14 billion years ago, or why it will be different 14 billion years from now. For the simple and stupefying fact remains that the laws of physics are reversible; nothing in those laws prevents time from running backwards, and it’s entirely possible to have universes in which conscious entities remember the future and remark offhandedly to each other that you can’t get some eggs without breaking an omelet. And yet, our universe obeys those reversible laws of physics even though effects follow causes, old age follows youth, and systems move from states of low entropy to states of high entropy. How can this be? How might it be otherwise?
It’s above my pay grade, this much I know. But thanks in part to local fluctuations in my corner of the universe that allow me to read books before they are written (these are known technically as Borges-Boltzmann Waveforms, or more colloquially, “wrinkles in time”), I can reveal that Caltech physicist Sean Carroll will have addressed—if not quite “answered”—these questions in his new book, From Eternity to Here: The Origin of the Universe and the Arrow of Time. (Not to be confused with this superficially similar book, which has been published in parallel universe XGH0046, where Frank Viola gave up a promising baseball career in order to become a Christian writer.)
Good stuff. Go get your pie (you’ll need two slices), follow the link (not neglecting the comments thread), settle back, and enjoy the day.