格致

Today’s lesson teaches that a scientist can make great discoveries by being creative.

A new kind of scientific detective work has, reportedly, paid off bigtime in the field of environmental science.

Thousands of scientists labored for decades to identify the most dangerous sources of environmental pollution—but despite all their slow, careful measurement and experimentation, they failed to identify what we now learn is a major source of pollution. A January 5, 2009 Catholic News Service report explains:

The birth-control pill is causing “devastating” environmental damage and plays a role in rising male infertility rates, said the Vatican newspaper, L’Osservatore Romano…. Pedro Jose-Maria Simon-Castellvi, president of the Vatican-based World Federation of Catholic Medical Associations, wrote the article that appeared in the paper’s Jan. 4 edition.

The pill has created “devastating ecological effects from tons of hormones being released into the environment for years,” the article said.

Details have not yet been made public. Students (along with every environmental scientist in the world!) can now giddily await the day when Dr. Simon-Castelvi publishes a formal study, in a good science journal, giving details of how he achieved his breakthrough discovery.

(Thanks to investigator David Kessler for bringing this to our attention.)

Today's xkcd was insufficiently nerdy for me.

Yes, that's right.

In order to make the comic adequately reflect what I do on a daily basis, I have at least to modify the temperature conversion chart:

“Coco,” as the Colossal Colon is affectionately known, is a 40-foot long, 4-foot tall oversized model of the human colon that is designed to educate about colorectal cancer and other diseases of the colon. Visitors who crawl through the Colossal Colon will see Crohn’s disease, diverticulosis, ulcerative colitis, hemorrhoids, cancerous and non-cancerous polyps, and various stages of colon cancer.

So says the Colon Club.

Frank Tipler is a crackpot. At one point in his life, he did very good technical work in general relativity; he was the first to prove theorems that closed timelike curves could not be constructed in local regions of spacetime without either violating the weak energy condition or creating a singularity. But alas, since then he has pretty much gone off the deep end, and more recently has become known for arguments for Christianity based on fundamental physics. If you closely at those arguments (h/t wolfgang), you find things like this:

If life is to guide the entire universe, it must be co-extensive with the entire universe. We can say that life must have become OMNIPRESENT in the universe by the end of time. But the very act of guiding the universe to eliminate event horizons - an infinite number of nudges - causes the entropy and hence the complexity of the universe to increase without limit. Therefore, if life is to continue guiding the universe - which it must, if the laws of physics are to remain consistent - then the knowledge of the universe possessed by life must also increase without limit, becoming both perfect and infinite at the final singularity. Life must become OMNISCIENT at the final singularity. The collapse of the universe will have provided available energy, which goes to infinity as the final singularity is approached, and this available energy will have become entirely under life’s control. The rate of use of this available energy - power - will diverge to infinity as the final singularity is approached. In other words, life at the final singularity will have become OMNIPOTENT. The final singularity is not in time but outside of time. On the boundary of space and time, as described in detail by Hawking and Ellis [6]. So we can say that the final singularity - the Omega Point - is TRANSCENDANT to space, time and matter.

All of the signs of classic crackpottery are present; the vague and misplaced appeal to technical terminology, the spelling mistakes and capital letters, the random use of “must” and “therefore” when no actual argument has been given. Two paragraphs later, we get:

Science is not restricted merely to describing only what happens inside the material universe, any more than science is restricted to describing events below the orbit of the Moon, as claimed by the opponents of Galileo. Like Galileo, I am convinced that the only scientific approach is to assume that the laws of terrestrial physics hold everywhere and without exception - unless and until an experiment shows that these laws have a limited range of application.

Compares self with Galileo! 40 points! There is really no indication that the person who wrote this was once writing perfectly sensible scientific papers.

Perhaps you will not be surprised to find that Tipler has now jumped into global-warming denialism. In just a few short paragraphs, we are treated to the following gems of insight (helpfully paraphrased):

People say that anthropogenic global warming is now firmly established, but that’s what they said about Ptolemaic astronomy! Therefore, I am like Copernicus.

A scientific theory is only truly scientific if it makes predictions “that the average person can check for himself.” (Not making this up.)

You know what causes global warming? Sunspots!

Sure, you can see data published that makes it look like the globe actually is warming. But that data is probably just fabricated. It snowed here last week!

If the government stopped funding science entirely, we wouldn’t have these problems.

You know who I remind myself of? Galileo.

Stillman Drake, the world’s leading Galileo scholar, demonstrates in his book “Galileo: A Very Short Introduction” (Oxford University Press, 2001) that it was not theologians, but rather his fellow physicists (then called “natural philosophers”), who manipulated the Inquisition into trying and convicting Galileo. The “out-of-the-mainsteam” Galileo had the gall to prove the consensus view, the Aristotlean theory, wrong by devising simple experiments that anyone could do. Galileo’s fellow scientists first tried to refute him by argument from authority. They failed. Then these “scientists” tried calling Galileo names, but this made no impression on the average person, who could see with his own eyes that Galileo was right. Finally, Galileo’s fellow “scientists” called in the Inquisition to silence him.

One could go on, but what’s the point? Well, perhaps there are two points worth making.

First, Frank Tipler is probably very “intelligent” by any of the standard measures of IQ and so forth. In science, we tend to valorize (to the point of fetishizing) a certain kind of ability to abstractly manipulate symbols and concepts — related to, although not exactly the same as, the cult of genius. (It’s not just being smart that is valorized, but a certain kind of smart.) The truth is, such an ability is great, but tends to be completely uncorrelated with other useful qualities like intellectual honesty and good judgment. People don’t become crackpots because they’re stupid; they become crackpots because they turn their smarts to crazy purposes.

Second, the superficially disconnected forms of crackpottery that lead on the one hand to proving Christianity using general relativity, and on the other to denying global warming, clearly emerge from a common source. The technique is to first decide what one wants to be true, and then come up with arguments that support it. This is a technique that can be used by anybody, for any purpose, and it’s why appeals to authority aren’t to be trusted, no matter how “intelligent” that authority seems to be.

Tipler isn’t completely crazy to want “average people” to be able to check claims for themselves. He’s mostly crazy, as by that standard we wouldn’t have much reason to believe in either general relativity or the Standard Model of particle physics, since the experimental tests relevant to those theories are pretty much out of reach for the average person. But the average person should be acquainted with the broad outlines of the scientific method and empirical reasoning, at least enough so that they try to separate crackpots from respectable scientists. Because nobody ever chooses to describe themselves as a crackpot. If you ask them, they’ll always explain that they are on the side of Galileo; and if you don’t agree, you’re no better than the Inquisition.

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It's NFL playoff time, which means that sports fans will be treated to the sight of the most high-stakes farce in sports, namely the ritual of "bringing out the chains" to determine whether a team has gained enough yards for a first down. We've all seen this: the play is whistled dead, a referee un-stacks the pile of players, picks up the ball, and puts it down more or less where the player was stopped. Then he tosses the ball into the middle of the field, to a second referee, who tries to replicate the spot closer to the center of the field. Then a guy on the sideline carrying a big stick (connected by a ten-yard chain to another stick held by another guy) tries to put the end of the stick at the same position as the ball.

Three plays later, the spotting procedure is repeated, and then the sticks are bought out to the center of the field, the chain is stretched taut, and they measure the position of the ball to the nearest millimeter. Because, of course, there's absolutely no error in placing the sticks.

The whole ritual is preposterous, and anybody with the slightest scientific inclination has to wonder: "Isn't there a better way of doing this?" So, what would be required to do a better job of this?

I was out of town (again) this past weekend, hence the posting shortage. Why in the world is it so much harder to find time to post during a nominal between-semester-break? I dunno, but it seems to be true. Free time doesn't scale the way you'd like.

One of the fundamental skill sets a physicist or really just about any scientist needs is to understand how quantities change scale. This is especially true when things change scale at different rates. I first noticed this particular instance of scaling phenomena while sitting in traffic in the city of Houston, Texas whose map (via Google) is printed below:

Here at the same scale is the town where I spend most of my time: College Station, Texas.

Not counting the very dense central regions of Houston, it's not to much of a stretch to say that a randomly selected patch of Houston's sprawl will look a lot like the interior of College Station in terms of population density. In any case the density is usually of the same order of magnitude. But the developed area of College Station is tiny compared to the developed area of Houston. So as an approximation pretend that both are of equal and uniform population density, and we'll try to use that fact to explain why traffic is so much worse driving through Houston than it is driving through College Station.

Such a simplification makes clear what the problem is. Pretend for simplicity that both Houston and College Station are circular. They aren't, but this additional simplification is a very gentle one which will only cause an error which is O(1). Now let's find a picture of a circle (this one from Wikipedia, with British spelling):

Now imagine that the circle encloses each city. The Houston circle will clearly be much, much larger. The roads entering the city must cross through the perimeter of the circle. Only so many roads per unit perimeter can fit, just as only so many people per unit area can fit.

But the perimeter is proportional to the radius, and the area is proportional to the radius squared. That is, for cities of larger and larger radius the number of people within the city increases much faster than the number of roads that can support them. Triple the radius of the city and you can triple the maximum number of roads entering. But the number of people in the city will have increased by a factor of 3*3=9, leaving you behind.

Of course there's mitigating factors. College Station doesn't have nearly the number of incoming roads that its perimeter can support, nor does it have any need for commuter lanes, toll roads, or mass transit. All those things can greatly increase the efficiency of the roads supporting a city. But in the final analysis, eventually you'll have fought a losing battle and there will be some limit to the practical size of a city before traffic simply becomes unmanageable.

I imagine the traffic engineers reading this are unhappy with my very simplified model of the perimeter as the variable of interest, for obviously traffic and urban design are vastly more complicated. And that's perfectly true. The mathematics is however entirely implacable and makes the accomplishments of traffic engineers that much more impressive.

Rebecca Goldstein's Incompleteness: The Proof and Paradox of Kurt Gödel is another book in the Great Discoveries series of short books by noted authors about important moments in the history of science, and the people behind them. Previous volumes include Everything and More and A Force of Nature, both of which were excellent in their own way, and Incompleteness fits right in there with them.

As the subtitle makes clear, this is a book about Kurt Gödel's famous Incompleteness Theorem, which shows that any formal logical system complex enough to describe arithmetic must allow the formation of statements that are true, but cannot be proved to be true within that system. If you've always wanted to know what all the fuss over Gödel, Escher, Bach was about, but can't make it through, this book would be an excellent alternative. Goldstein does an excellent job of explaining the meaning of the theorem, putting it in historical context, and sketching out the unique way Gödel did the proof.

Of course, like all the other books in the series, the book also reflects the author's tastes and professional inclination. Goldstein is a philosopher, and so she uses the book to make an argument about Gödel's philosophy: that contrary to the common impression of the theorem as the work of some sort of mathematical postmodernist, Gödel was in fact a passionate and committed Platonist, firmly believing in the independent reality of mathematical ideas. To him, the important part of the theorem was that the unprovable statements were true, suggesting a wider and deeper mathematical universe than the formalist program would admit. He wasn't out to destroy mathematical truth, but to confirm and in some sense ennoble it.

I'm not qualified to evaluate the accuracy of this claim, but Goldstein makes a convincing argument. She also does an excellent job of putting the theorem in historical context, sketching out both the philosophical circles of Vienna where Gödel cut his teeth, and the formalist program of David Hilbert (among others) that his famous result overthrew. And, of course, no biography of Gödel could hope to avoid his personal eccentricities, and the tragic descent into paranoia that led to his death.

This is a very well-done book, and if you have any interest in mathematics or the history and philosophy thereof, I recommend checking it out.

• Paul Buchheit: Overnight success takes a long time
  • Interesting discussion of what it takes to develop a successful technology, from one of the founders of FriendFeed, and the original creator of gmail.
• Trevor Strohman: Efficient Processing of Complex Features for Information Retrieval
  • Trevor Strohman’s thesis. Surveys search systems, and develops TupleFlow, a system extending MapReduce, intended for use in building certain indices for use in search
• Cloud N
  • Excellent blog on cloud and massively parallel computing from Bill McColl.
• The washing machine on Twitter
  • “A […] bright and entrepreneurial young man has hacked a washing machine so that it tweets every time it finishes a load of laundry. Presumably so he can get a direct reminder to hang the load out, or put it on to dry.”

Click here for all of my del.icio.us bookmarks.

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(That’s an excerpt from the article “Puzzling Solutions,” published in AIR 14:3.)

Previously in series:  Growing Up is Hard

So... I'm basically on board with that sort of thing as a fine and desirable future.  But I think that the difficulty and danger of fiddling with emotions is oft-underestimated.  Not necessarily underestimated by Greg Bear, per se; the above journal entry is from a character who was receiving superintelligent help.

But I still remember one time on the Extropians mailing list when someone talked about creating a female yet "otherwise identical" copy of himself.  Something about that just fell on my camel's back as the last straw.  I'm sorry, but there are some things that are much more complicated to actually do than to rattle off as short English sentences, and becoming a member of the opposite sex has to rank very high on that list.  Even if you're omnipotent so far as raw ability goes, it's not like people have a binary attribute reading "M" or "F" that can be flipped as a primitive action.

Changing sex makes a good, vivid example of the sort of difficulties you might run into when messing with emotional architecture, so I'll use it as my archetype:

Let's suppose that we're talking about an M2F transformation.  (F2M should be a straightforward transform of this discussion; I do want to be specific rather than talking in vague generalities, but I don't want to parallelize every sentence.)  (Oddly enough, every time I can recall hearing someone say "I want to know what it's like to be the opposite sex", the speaker has been male.  I don't know if that's a genuine gender difference in wishes, or just a selection effect in which spoken wishes reach my ears.)

Want to spend a week wearing a female body?  Even at this very shallow level, we're dealing with drastic remappings of at least some segments of the sensorimotor cortex and cerebellum - the somatic map, the motor map, the motor reflexes, and the motor skills.  As a male, you know how to operate a male body, but not a female one.  If you're a master martial artist as a male, you won't be a master martial artist as a female (or vice versa, of course) unless you either spend another year practicing, or some AI subtly tweaks your skills to be what they would have been in a female body - think of how odd that experience would be.

Already we're talking about some pretty significant neurological changes.  Strong enough to disrupt personal identity, if taken in one shot?  That's a difficult question to answer, especially since I don't know what experiment to perform to test any hypotheses.  On one hand, billions of neurons in my visual cortex undergo massive changes of activation every time my eyes squeeze shut when I sneeze - the raw number of flipped bits is not the key thing in personal identity.  But we are already talking about serious changes of information, on the order of going to sleep, dreaming, forgetting your dreams, and waking up the next morning as though it were the next moment.  Not informationally trivial transforms like uploading.

What about sex?  (Somehow it's always about sex, at least when it's men asking the question.)  Remapping the connections from the remapped somatic areas to the pleasure center will... give you a vagina-shaped penis, more or less.  That doesn't make you a woman.  You'd still be attracted to girls, and no, that would not make you a lesbian; it would make you a normal, masculine man wearing a female body like a suit of clothing.

What would it take for a man to actually become the female version of themselves?

Well... what does that sentence even mean?  I am reminded of someone who replied to the statement "Obama would not have become President if he hadn't been black" by saying "If Obama hadn't been black, he wouldn't have been Obama" i.e. "There is no non-black Obama who could fail to become President".  (You know you're in trouble when non-actual possible worlds start having political implications.)

The person you would have been if you'd been born with an X chromosome in place of your Y chromosome (or vice versa) isn't you.  If you had a twin female sister, the two of you would not be the same person.  There are genes on your Y chromosome that tweaked your brain to some extent, helping to construct your personal identity - alleles with no analogue on the X chromosome.  There is no version of you, even genetically, who is the opposite sex.

And if we halt your body, swap out your Y chromosome for your father's X chromosome, and restart your body... well.  That doesn't sound too safe, does it?  Your neurons are already wired in a male pattern, just as your body already developed in a male pattern.  I don't know what happens to your testicles, and I don't know what happens to your brain, either.  Maybe your circuits would slowly start to rewire themselves under the influence of the new genetic instructions.  At best you'd end up as a half-baked cross between male brain and female brain.  At worst you'd go into a permanent epileptic fit and die - we're dealing with circumstances way outside the evolutionary context under which the brain was optimized for robustness.  Either way, your brain would not look like your twin sister's brain that had developed as female from the beginning.

So to actually become female...

We're talking about a massive transformation here, billions of neurons and trillions of synapses rearranged.  Not just form, but content - just like a male judo expert would need skills repatterned to become a female judo expert, so too, you know how to operate a male brain but not a female brain.  You are the equivalent of a judo expert at one, but not the other.  You have cognitive reflexes, and consciously learned cognitive skills as well.

If I fell asleep and woke up as a true woman - not in body, but in brain - I don't think I'd call her "me".  The change is too sharp, if it happens all at once.

Transform the brain gradually?  Hm... now we have to design the intermediate stages, and make sure the intermediate stages make self-consistent sense.  Evolution built and optimized a self-consistent male brain and a self-consistent female brain; it didn't design the parts to be stable during an intermediate transition between the two.  Maybe you've got to redesign other parts of the brain just to keep working through the transition.

What happens when, as a woman, you think back to your memory of looking at Angelina Jolie photos as a man?  How do you empathize with your past self of the opposite sex?  Do you flee in horror from the person you were?  Are all your life's memories distant and alien things?  How can you remember, when your memory is a recorded activation pattern for neural circuits that no longer exist in their old forms?  Do we rewrite all your memories, too?

Well... maybe we could retain your old male brainware through the transformation, and set up a dual system of male and female circuits... such that you are currently female, but retain the ability to recall and empathize with your past memories as if they were running on the same male brainware that originally laid them down...

Sounds complicated, doesn't it?  It seems that to transform a male brain into someone who can be a real female, we can't just rewrite you as a female brain.  That just kills you and replaces you with someone re-imagined as a different person.  Instead we have to rewrite you as a more complex brain with a novel, non-ancestral architecture that can cross-operate in realtime between male and female modes, so that a female can process male memories with a remembered context that includes the male brainware that laid them down.

To make you female, and yet still you, we have to step outside the human design space in order to preserve continuity with your male self.

And when your little adventure is over and you go back to being a man - if you still want to, because even if your past self wanted to go back afterward, why should that desire be binding on your present self? - then we've got to keep the dual architecture so you don't throw up every time you remember what you did on your vacation.

Assuming you did have sex as a woman, rather than fending off all comers because because they didn't look like they were interested in a long-term relationship.

But then, you probably would experiment.  You'll never have been a little girl, and you won't remember going through high school where any girl who slept with a boy was called a slut by the other girls.  You'll remember a very atypical past for a woman - but there's no way to fix that while keeping you the same person.

And all that was just what it takes to ranma around within human-space, from the male pole to the female pole and back again.

What if you wanted to move outside the human space entirely?

In one sense, a sex change is admittedly close to a worst-case scenario: a fixed target not optimized for an easy transition from your present location; involving, not just new brain areas, but massive coordinated changes to brain areas already in place.

It might be a lot easier to just add one more emotion to those already there.  Maybe.

In another sense, though, a sex change is close to a best-case scenario: the prototype of your destination is already extensively tested as a coherent mind, and known to function well within a human society that already has a place for it (including companions to talk to).

It might be a lot harder to enter uncharted territory.  Maybe.

I'm not saying - of course - that it could never, ever be done.  But it's another instance of the great chicken-and-egg dilemma that is the whole story of present-day humanity, the great challenge that intelligent life faces in its flowering: growing up is a grownup-level problem.  You could try to build a cleanly-designed artificial grownup (self-improving Friendly AI) to foresee the pathway ahead and chart out a nonfatal course.  Or you could plunge ahead yourself, and hope that you grew faster than your problems did.

It's the same core challenge either way: growing up is an adult problem.  There are difficult ways out of this trap, but no easy ones; extra-ordinary solutions, but no ordinary ones.  People ask me why I take all these difficulties upon myself.  It's because all the easier ways, once you examine them in enough fine detail, turn out to be illusions, or contain just as much difficulty themselves - the same sort of hidden difficulty as "I'd like to try being the opposite sex for a week".

It seems to me that there is just an irreducible residue of very hard problems associated with an adult version of humankind ever coming into being.

And emotions would be among the most dangerous targets of meddling.  Make the wrong shift, and you won't want to change back.

We can't keep these exact human emotions forever.  Anyone want to still be eating chocolate-chip cookies when the last sun grows cold?  I didn't think so.

But if we replace our emotions with random die-rolls, then we'll end up wanting to do what is prime, instead of what's right.

Some emotional changes can be desirable, but random replacement seems likely to be undesirable on average.  So there must be criteria that distinguish good emotional changes from bad emotional changes.  What are they?

At the moment from our perspective we do understand that the action is part of the defensive action of Israel (...) we do understand that it is more defensive than offensive.

The Great Synagogue in Pilsen...

Clearly, the holocaust experience has strengthened the plans to recreate a Jewish state in Palestine in the late 1940s. It was a difficult and controversial engineering project meant to restore the status that existed 2,500 years ago or so - driven by the desire to transform the Jews into a generic nation with its own homeland, like everyone else - but I would claim that it has worked beautifully. 

Good luck to Israel and all of its Jewish, Arab, and other citizens who want the situation to converge into a stable, capitalist, democratic, not-religiously controlled state on the territory, naturally dominated by the Jewish nation. But the Czech Republic is going to help you by following the good soldier Švejk's example only. 



Click the picture of the French, EU, Czech foreign ministers to see a similar optimistic scenario by an Israeli professor.

I am personally convinced that the relative contribution of the Jewish nation to the modern civilization, including theoretical physics, vastly exceeds the ratio of the Israel's territory and the total land mass on Earth which is why I find it natural for Israel to be restored and stabilized within the borders of the Greater Israel we knew for a few decades.

As the year breaks, the internets are abuzz with deep thoughts!

What will change everything? is this year’s Edge Annual Question. Many interesting answers, as you might expect. Choose from Massive Technological Failure (David Bodanis), Breaking the Species Barrier (Richard Dawkins), Coordinated and Expanded Computational Power (Lisa Randall), Faster Evolution (Jonathan Haidt), Happiness (Betsy Devine), Synthetic Biology (Dimitar Sasselov), and more. The book of last year’s question is out soon.

The blog posts to be reprinted in the Open Lab 2008 anthology have been announced — only 50 selections from over 500 nominations, I’m glad I wasn’t responsible for making the tough choices. Also glad that they chose one of my posts, The First Quantum Cosmologist. You can also read about The Igneous Petrology of Ice Cream (Green Gabbro), Expect the Unexpected (A canna’ change the laws of physics), How do cave bats know when it is dark outside? (Pondering Pikaia), and perhaps the most courageous blog post of all time: Liveblogging the Vasectomy (Terra Sigillata). Some sort of new journalism” going on there.

Finally, if all those ideas are weighing you down, play with the David Lee Roth ‘Runnin’ With the Devil’ Soundboard (via Cynical-C). Deconstructed from this classic track.

The complete version is here, but it only detracts.

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I’m hoping that, for many of our readers, New Year’s Resolutions include getting off their duffs and starting a blog of their own. It’s certainly not hard; at the minimal level of effort, hop over to Blogger and set up your own free blog in a couple of easy steps. Only after you’ve established yourself can you hope to sell out to the Man and thereby cause the Death of the Blogosphere, like us.

But there are obstacles, for example: what to call the blog? We’re here to help. I was leafing through some old emails, and stumbled across the conversations we were having in the days before Cosmic Variance even existed. The heady days of youth, when we were trying to come up with good names for our new venture. Of course there are many types of blogs, from individual rants about the state of one’s personal life and recent dining experiences to focused discussions of the prospects for health care reform at the national level. We (including Clifford) wanted something that reflected our identity as scientists, but would attract and intrigue non-scientists as well, as we have always hoped to cast our discoursive net more widely than our particular disciplines. So we were looking for titles that played off scientific concepts, but didn’t come off as complete gobbeldy-gook to non-experts. Shores of the Dirac Sea is an excellent recent example of the genre — very much a physics in-joke, but one that isn’t completely off-putting to outsiders. If you call your blog “Laplace-Beltrami Operator” or “Gravitino Propagator,” you might amuse yourself, but your audience will be limited. (Apologies if there are any blogs out there with those names.)

Of course we came up with more than one, before settling on our perfect choice. But what was imperfect for us might fit you just fine. So, offered up free of charge, here are some of the names we were bandying around, plus some extras I came up with since.

• Tycho’s Nose
• Higher Dimensional Operators
• Extremize The Action
• Critical Phenomena
• The Residue Theorem
• But No Simpler
• De Revolutionibus
• Smooth Tension
• Ultra Deep Field
• Outside the Light Cone
• Primeval Atom
• Left As An Exercise
• The Error Bar

Personally I’m partial to Tycho’s Nose, but The Error Bar is an awesome name. That blog practically writes itself. So what are you waiting for?

Those who are too lazy and/or timid to start their own blogs are encouraged to suggest additional names in comments.

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Dear Reader, remember the remote-controlled Mars rovers, Spirit and Opportunity? How long is it since the last time you thought of them? Spirit landed on Mars five Earth years ago today, Opportunity on 25 January -- and both are still going strong! These machines were originally meant to work for three months, yet they continue to trundle around that cold, distant planet, taking pictures and analysing rocks. Check out the project's web site for news!

[More blog entries about astronomy, space, mars, nasa; astronomi, rymden, mars, nasa.]

I will be leaving town tomorrow to spend most of this coming week in Washington D.C., participating in the annual extravaganza known as the Joint Mathematics Meetings. This is quite simply the place to be if you have any interest in mathematics.

Of course, this means I will only have limited internet access for the next few days. So I will not be blogging, and I will not be making detailed replies to comments. Try to soldier on in my absence!

Can humans live completely according to a theory? Apparently so, if one uses the logic in Peter Huber’s book Hard Green: Saving The Environment From The Environmentalists A Conservative Manifesto. Huber writes:

Cut down the last redwood for chopsticks, harpoon the last blue whale for sushi, and the additional mouths fed will nourish additional human brains, which will soon invent ways to replace blubber with Olestra and pine with plastic. Humanity can survive just fine in a planet- covering crypt of concrete and computers.