For my September 2006 diary, go here.

Diary - October 2006

John Baez

• James Hansen, Makiko Sato, Reto Ruedy, Ken Lo, David W. Lea, and Martin Medina-Elizade, Global temperature change, Proc. Nat. Acad. Sci. 103 (2006), 14288-14293.

A study of 1,700 biological species found poleward migration of 6 kilometers per decade and vertical migration in alpine regions of 6 meters per decade in the second half of the 20th century, within a factor of two of the average poleward migration rates of surface isotherms during 1950-1995. More rapid warming in 1975-2005 yields an average isotherm migration rate of 40 kilometers per decade in the Northern Hemisphere, exceeding known paleoclimate rates of change. Some species are less mobile than others, and ecosystems involve interactions among species, so such rates of climate change, along with habitat loss and fragmentation, new invasive species, and other stresses are expected to have severe impact on species survival.

This lousy news makes me all the more eager to give my talk at the Long Now Seminar.

October 2, 2006

• Vernor Vinge, Rainbows End, Tom Doherty Associates, New York, 2006.

• Vernor Vinge, What is the singularity?
• Robin Hanson, ed., A critical discussion of Vinge's singularity concept.
• Wikipedia, Technological singularity.
• Ray Kurzweil, The singularity.
• Anders Sandberg, The singularity.

(See below for the resolution of this mystery.)

October 3, 2006

Oisin McGuinness wrote:

You wrote:

"There David Scharffenberg told me an incredible stories about a talking parakeet named Alex. I can't find any information about this on the web, so he may have been pulling my leg. If you know about this, let me know."

Not a parakeet, but an African Grey Parrot, Alex has been Irene Pepperberg's life work (well, 30 years so far)....

• Wikipedia, Alex (parrot).

And the official page:

• The Alex Foundation.

Enjoy!

Oisin McGuinness

Check out the above sites for more interesting stuff, like how well Alex does with math.

October 7, 2006

Ocean surface temperatures worldwide shot up by 5-8°C for a few thousand years - but in the Arctic it heated up even more, to a balmy 23°C (73°F). This caused a severe dieoff of little ocean critters called foraminifera, and a drastic change of the dominant mammal species. What caused this? Maybe a sudden release of greenhouse gases - carbon dioxide from volcanos, or a "methane burp" released from gas hydrates on the sea floor. People have indeed found drastically different carbon isotope ratios at this time.

This may be the closest analogue to the rapid global warming we're seeing now, so it's worth studying. Here's part of an article about it:

CLIMATE CHANGE:
A Smoking Gun for an Ancient Methane Discharge

Richard A. Kerr
Science 286 (19 November 1999), p. 1465

It's not often that researchers probing pivotal events in the ancient history of life can put their finger on causes. One striking exception is the meteor that hit Earth 65 million years ago, doing in the dinosaurs. Now paleoceanographers are closing in on a possible cause for another evolutionary watershed 55 million years ago. This watershed brought modern mammals--the ancestors of horses, cows, deer, apes, and us--into global dominance. And its trigger may have been a vast belch of climate-changing methane from under the sea floor.

Proposed less than 5 years ago, the "methane burp" hypothesis gets its most direct support yet on page 1531 of this issue of Science. Paleoceanographer Miriam Katz of Rutgers University in Piscataway, New Jersey, and her colleagues report the discovery of a sequence of sediment layers buried half a kilometer below the sea floor off Florida, which records the exact sequence of deep-sea changes--including vast submarine landslides--predicted by the scenario. "It's real good, consistent evidence" for the hypothesis, says paleoceanographer Timothy Bralower of the University of North Carolina, Chapel Hill. "It's not 100% proof, but it's compelling."

If not for the evolutionary turning point the methane burp might explain, we might be eating egg-laying mammals for Thanksgiving--if we had evolved at all. Ten million years after the demise of the dinosaurs, mammals in the fossil record were still "archaic," a mix of odd, unfamiliar animals that have no direct descendants today. But 55 million years ago, an array of modern forms burst on the scene in North America. In recent years, researchers have tied this transition to an extraordinary surge of global warming recorded in fossils and sediments. The warming would have allowed mammals that had already evolved into modern forms in a presumed Asian enclave to march across otherwise frigid polar lands and usurp North American archaics (Science, 18 September 1992, p. 1622).

Several researchers proposed that the methane from the sea floor could have driven the warming (Science, 28 February 1997, p. 1267), and paleoceanographer Gerald Dickens of James Cook University in Townsville, Australia, used clues in sea-floor sediments to develop a detailed scenario for what happened. His hypothesis assumes that 55 million years ago, as today, something like 15 trillion tons of methane hydrate--a combination of ice and methane--had formed beneath the sea floor, where microbes digesting organic matter release methane. Then, for whatever reason, ocean bottom waters warmed enough to decompose a small fraction of the methane hydrate into water and methane gas--roughly a trillion tons of it. This methane disrupted the sediment, triggering landslides down the continental slope that let the methane burst into the ocean. Upon its release, theorized Dickens, the methane probably oxidized to form carbon dioxide, which eventually reached the atmosphere, driving greenhouse warming.

Katz and her colleagues found signs of most of what Dickens called for, 512 meters down a sediment core that the Ocean Drilling Program (ODP) retrieved 350 kilometers off the northeast Florida coast. The deep-ocean warming killed off bottom-dwelling microscopic animals called foraminifera, they saw. Then the isotopically distinctive carbon of the methane left its mark in carbonate sediments. Finally, carbonic acid from the dissolved carbon dioxide partially dissolved some of the sediment.

Other researchers had made similar findings in various cores. But Katz also turned up a never-before-seen 20-centimeter-thick layer of soft mud containing chunks, or clasts, of the same mud. That's just the sort of debris deposit you'd expect to see downslope of where methane burst from the bottom, she notes. Indeed, the mud-clast layer was laid down just where debris from a hydrate-triggered slide should be--in the layer that settled while the foraminifera were going extinct and just before the isotopic shift that recorded the surge of methane. In addition, seismic probing beneath the sea floor reveals a "chaotic zone" of disturbed sediment 15 kilometers upslope from the drill site. This zone, like the mud-clast layer, just predates the isotopic signal of methane in the sediment, says Katz, making it the likely source.

"You can't do much better than that" at getting the predicted events in the predicted order, says paleoceanographer James Zachos of the University of California, Santa Cruz. "This is all consistent with Dickens's original proposal." Paleoceanographer Ellen Thomas of Wesleyan University in Middletown, Connecticut, notes that "this is the first place we have evidence [that methane] came out anywhere; it's a really neat development. But it's not completely solved."

Charles Paull of the Monterey Bay Aquarium Research Institute in Moss Landing, California, agrees. A specialist in methane hydrates, he finds the sea-floor methane hypothesis "absolutely fascinating, but I wonder about whether or not it's correct." Among his doubts: whether the hydrate deposits 55 million years ago contained enough methane to drive the climate shift and whether a deepwater warming could have penetrated far enough into the sediments to decompose the deep hydrates that could cause landslides.

Tony Smith had some remarks about this graph:

and in particular the bump labelled "PETM", which I discussed on October 7 - the Paleocene-Eocene Thermal Maximum. He wrote:

Your diary for yesterday ( 6 Oct 2006 ) discussed
"... a sudden hot period about 55 million years ago,
which lasted a few thousand years! ...".

However, when looking at your 4600 Myr chart,
an excerpt of which is attached to this message:

I see a little bump in the Eocene that might
correspond to a "sudden hot period" lasting "a few thousand years",
but
it looks to me like a pimple on a mountain,
and
that the mountain is a very warm (compared to now) period
beginning around the end of the Jurassic and extending
through the Eocene.

Also, the very hottest part of that period seems to be
a big ridge (much bigger than the bump/pimple) in mostly the Cretaceous.

My guess would be that a methane burp might indeed have
caused the little warm bump/pimple,
but
the overall mountain and ridge of warmth would require a process
extending far longer than such a burp would be likely to last.

As to what might cause the mountain and ridge of warmth,
what about changes in solar luminosity?
Are solar evolution models understood well enough to shed any
light on the questions?

Also, could the end of the Cretaceous high ridge have been due
to change in ocean circulation (closing of the Tethys Sea, with
Africa/India closing in on Europe/Asia) ?

Tony

First, I should explain why I'm so interested in that insignificant "pimple". The current burst of global warming is happening very fast, and it's induced by greenhouse gases. To understand the possible consequences - e.g. extinctions of organisms unable to adapt in time to sudden changes - I want to look at similar events in the Earth's history. The PETM was a sudden warming, a spike of a few degrees Celsius lasting a mere thousand years, probably caused by a sudden release of greenhouse gases (methane rather than CO₂). So, it's a good analogue - and it indeed caused noticeable extinctions!

Another interesting rapid change is the cooling at the end of the Eocene, 34 million years ago. You can see the precipitous drop of temperature on the graphs above. India hit Asia at this time, the Antarctic first got glaciers then, and there was a serious extinction event -the worst since the extinction of the dinosaurs.

I believe organisms can adapt and survive much larger climate changes if they're sufficiently slow - they may change into completely different species, but that's just a kind of adaptation. So, the huge "mountain" of warming in the late Cretaceous and early Paleocene is not my main interest now, though it's still fascinating.

Why did it happen? More generally, what explains the very long-term variations in climate, over periods like 100 million years? I've read some fascinating books on this, for example this:

• Barry Saltzman, Dynamical Paleoclimatology: Generalized Theory of Global Climate Change, Academic Press, New York, 2002.

but I think the really short answer is that nobody knows: there are lots of factors involved, and people argue quite a bit about their relative importance. Peek in the above book, and you'll see some beautiful dynamical systems theory applied to the Earth! Some important "feedback mechanisms" include:

• The Ice Albedo Effect. Having more ice around makes the Earth reflect more light, making it colder. When ice melts, the Earth gets darker, making it warmer. A positive feedback mechanism!
• Clouds and Water Vapor. When it gets hot more water evaporates, making more clouds, which reflect more light, making it colder - but water vapor traps heat, making it warmer. Which one wins?
• Metamorphosis versus Weathering. There's an important reaction
  metamorphosis
  CaSiO₃ + CO₂         CaCO₃ + SiO₂
  weathering

  When it's hot, warm water washes over rocks, so the rocks weather, and calcium silicate combines with carbon dioxide to form calcium carbonate and silica. This means less carbon dioxide, so less greenhouse effect, so things cool down.

  When it's cold, ice covers rocks, so rocks don't weather so much - but volcanos still pump out carbon dioxide, so there's more greenhouse effect, so things warm up. Note the carbon dioxide from volcanos is the same carbon dioxide that got absorbed when rocks were weathering! It's a cycle.

  A bunch of people regard this as the most important long-term stabilizing feedback mechanism in the climate - it operates at a timescale of about 500,000 years. Here I'm paraphrasing an article by David Archer in Science; see my April 18th entry for more details - and more disagreements. Also some great stuff about "Snowball Earth".

Two main "external driving forces" are plate tectonics and astronomy:

• Tectonics. You can get a nice taste of plate tectonics here, but this animation doesn't show how tectonics affects ocean currents and wind patterns. For example, there's a big argument over how much of the cooling since the Eocene is due to the separation of Antarctica from other land masses, allowing cold currents to circulate endlessly around this continent instead of being forced to curve back north, and how much is due to the huge icy Tibetan massif formed when India hit Asia.
• Astronomy. People believe three Milankovitch cycles are important at time scales around 20,000-100,000 years. These are slow cyclic changes in the direction of the Earth's axis (precession of the equinox), the shape of the Earth's orbit (eccentricity), and the tilt of the Earth's axis (obliquity). People have done lots of simulations to see how these could cause the glacial cycles we see lately:
  

  Here the solar forcing is the total result of the precession, eccentricity and obliquity, and glaciation responds to this in a delayed way, with feedback due to the ice albedo effect. The problem is, glacial cycles seem to occur every 100,000 years or so, which best fits the eccentricity cycles, which is the weakest of the three Milankovitch cycles! So, I'm not sure people understand what's going on. And of course we only have these glacial cycles under certain special conditions, not all the time.

  Also, there are changes in solar luminosity. People argue about how much the 7-year sunspot cycle matters - but that's a rapid oscillation compared to what we're discussing now. At large time scales, I believe the sun has been getting brighter more or less constantly for the last 4 billion years - with an overall increase in luminosity of about 30%. That's a lot! This will keep on going until the Sun becomes a red giant. 3.5 billion years from now the Earth will be getting as much sunlight as Venus is now, so our goose will be cooked. However, it's not worth worrying about this too much: the Andromeda Galaxy will hit the Milky Way in only 3 billion years, and many of the planets in our galaxy will be thrown out of orbit.

Hail, fellow rationalist. I've been tipped off that your August diary mentioned Friendly AI. Firstly - thanks! Second, "Creating Friendly AI" is showing a lot of age (I really need to get around to putting up a disclaimer to that effect). These days, the article I usually refer people to is:

• Artificial Intelligence as a positive and negative factor in global risk.

This is a book chapter in the forthcoming edited volume Global Catastrophic Risks by Nick Bostrom and Milan Cirkovic. I also did another book chapter for the same volume:

• Cognitive biases potentially affecting judgment of global risks.

The latter paper is an introduction to heuristics and biases, as particularly relevant to assessing large public risks. If you're planning to read both papers this one is better to read first.

I think you might like the cognitive biases paper, in particular.

But if the esteemed John Baez is going so far as to read my humble efforts, I also wish to offer to you:

• Twelve virtues of rationality - short but sweet.

and

• A technical explanation of technical explanation - meditation on Bayes, including what makes a scientific theory "technical", and how to calculate exactly how technical it is.

Sincerely,
Eliezer Yudkowsky.

Anyways, I noticed with interest your "Zooming in" talk, and found that there's a slight mistake. It's one many people have made, and continue to make. It turns out that the Gulf Stream is not the reason that northern Europe is warmer than expected. This myth was laid to rest quite recently by Richard Seager and David Battisti:

• Richard Seager, The source of Europe's mild climate, American Scientist, July-August 2006.

It turns out that there is a combination of heat transport by the oceans, as well as the atmosphere. We are still learning a great deal about how the climate works and how heat is transported about the planet. For example, it is extremely difficult to account for all the observed latitudinal heat transport - which makes global climate modeling tricky to say the least.

I'm curious about how much this affects the theory that the Younger Dryas was caused by melting glacial ice disturbing the normal flow of currents in the North Atlantic - the "Atlantic thermohaline circulation". I reported on this theory in my November 12, 2004 diary entry. Later, I read in Mark Bowen's book Thin Ice that this theory had been discredited: ice cores from glaciers atop tropical mountains show more cooling in the Younger Dryas far from the North Atlantic!

According to this book, the importance of the North Atlantic thermohaline circulation had been greatly exaggerated this theory's main proponent, Wallace Broecker. In fact, this book goes after Broecker quite harshly, in part because book's main hero, the climate scientist Lonnie Thompson, had a lot of arguments with him. Broecker claimed the North Atlantic was the "Achilles Heel of Our Climate System", with world-wide effects, while Thompson believes that the tropics, and especially the Pacific, are much more important - because they contain a lot more heat energy.

So, the whole idea that an interruption in the the Atlantic thermohaline circulation could plunge Europe into a repeat of the Younger Dryas is looking more and more shaky to me now, but I don't know the latest word from the experts. I also don't know what other cause has been proposed for the Younger Dryas!

October 13, 2006

But, I couldn't let that stop me. So, I stayed in bed at the Hotel Drisco most of the day, mentally rehearsing my talk, listening to music by the Cocteau Twins and pondering some stuff I just read about a ball rolling on another ball without twisting or slipping. Here's an incredible fact: when one ball is exactly 1/3 the size of the other, the symmetry group of this problem is the same as the symmetry group of... the octonions!

(Actually the "split octonions" - but never mind. I'll explain this better soon in This Week's Finds.)

My talk was scheduled to start at 7:30 at the Cowell Theater in Fort Mason, an old fort at the north tip of San Francisco. A couple hundred people were supposed to attend. The sound check was to start at 6:30. Someone was supposed to drive me there. Around noon I got a call saying it would be Stewart Brand - the man himself, the guy running the show, creator of the Whole Earth Catalogue and CoEvolution Quarterly, founder of the WELL and founder of the Hackers Conference. It was a bit like getting a lift from the Dalai Lama.

Anyway, a while after 6:00 I went down to hotel entrance and waited there. At 6:15 I heard "Hey! Is that John Baez?" - and he picked me up in his GPS-equipped Land Rover.

Luckily he was unpretentious and friendly, so I was only marginally tongue-tied. As we rolled down the steep hills of Pacific Heights he told me he'd invited my cousin Joan, but she was too tired, 'cause she'd just been to Vaclav Havel's birthday, where she was supposed to jump out of a cake, and she was about to start another concert tour... or maybe it was the other way around, I can't remember. I told him I don't see much of her except at my uncle's birthday parties - that's her dad, Albert, who got me interested in physics when I was a kid. He's also the one who gave me an early edition of the Whole Earth Catalogue!

I asked him what he did these days and he told me. Half Long Now Foundation stuff, especially trying to preserve access to old data in outmoded formats, which is a big problem as computers keep changing. Half other stuff, like trying to convince intelligence people of the importance of history.

We rolled into Fort Mason, where the Long Now Foundation is headquartered, and got ready for the sound check. There were some people milling around looking at books for sale - I checked and saw they had some copies of the books I'd suggested: Thin Ice and When Life Nearly Died.

I also saw another interesting book:

• Neil Roberts, The Holocene: an Environmental History, Blackwell, Oxford, 1998

He was the other guy running this show: also a founder of the Whole Earth Catalogue, CoEvolution Quarterly and Hackers Conference... and the founding executive editor of Wired magazine, to boot. Another guy I've looked up to for years. So, another "meet the Dalai Lama" moment. What do you do in situations like this? You might as well just start tap-dancing and singing:

(You'll either get that joke, or you won't.)

Luckily, his bounciness and enthusiasm for cool ideas immediately made it impossible to be nervous. So, we talked a bit And before long, it was time for the sound check!

I got hooked up to a little headset microphone, and my laptop got hooked up the video monitor - the usual drill. Everything worked fine, except my stupid laptop seemed to have lost its ability to display simultaneously on its own screen and the video monitor. Everyone there was too cool to know how PCs worked - they all had Macs. Oh well. Time dragged on a little, in a pleasant sort of way. At 7:00 they let in the crowd. At 7:30, Brand introduced me and I gave my talk.

I think it went okay. People seemed to enjoy my goofy sense of humor - a good thing, since one of my main messages was that the human race has started a mass extinction, and I didn't want people to leave the theater sobbing, though that's probably the most honest reaction to this news. In fact, after the talk Brand said he and Kelly were "cackling away" in the front row. Great!

Here's Stewart Brand's own summary:

The graphs we see these days, John Baez began, all look vertical --- carbon burning shooting up, CO₂ in the air shooting up, global temperature shooting up, and population still shooting up. How can we understand what really going on? "It's like trying to understand geology while you're hanging by your fingernails on a cliff, scared to death. You think all geology is vertical."

So, zoom out for some perspective. An Earth temperature graph for the last 18,000 years shows that we've built a false sense of security from 10,000 years of unusually stable climate. Even so, a "little dent" in the graph of a drop of only 1 degree Celsius put Europe in a what's called "the little ice age" from 1555 to 1850. It ended just when industrial activity took off, which raises the question whether it was us that ended it.

Nobel laureate atmospheric scientist Paul Crutzen suggests that the current geological era should be called the "Anthropocene," because it is increasingly dominated by human-caused effects. Baez noted that oil companies now can send their tankers through a Northwest Passage that they may have created, since it is fossil fuel burning that raised the CO₂ that raised the summer temperatures in the Arctic that melts the polar ice away from the land.

Zoom out further still to the last 65 million years. The temperature graph show several major features. One is the rapid (every 100,000 years) wide swings of major ice ages. When they began, 1.35 million years ago, is when humans mastered fire. But almost all of the period was much warmer than now, with ferns growing in Antarctica. "Now it's cold. What's wrong with a little warming?" Baez asked.

The problem is that the current warming is happening too fast. Studies of 1,500 species in Europe show that their ranges are moving north at 6 kilometers a decade, but the climate zones are moving north at 40 kilometers a decade, faster than they can keep up. The global temperature is now the hottest it's been in 120,000 years. One degree Celsius more and it will be the hottest since 1.35 million years ago, before the ice ages. Baez suggested that the Anthropocene may be characterized mainly by species such as cockroaches and raccoons who accommodate well to humans. Coyotes are now turning up in Manhattan and Los Angeles. There are expectations that we could lose one-third of all species by mid-century, from climate change and other human causes.

Okay, to think about major extinctions, zoom out again. Over the last 550 million years there have been over a dozen mass extinctions, the worst being the Permian-Triassic extinction 250 million years ago, when over half of all life disappeared. The cause is still uncertain, but one candidate is the methane clathrates ("methane ice") on the ocean floor. Since methane is a far worse greenhouse gas than carbon dioxide, massive "burps" of the gas could have led to sudden drastic global heating and thus the huge die-off of species. Naturally the methane clathrates are being studied as an industrial fuel for when the oil runs out in this century, "which could make our effect on global warming 10,000 times worse," Baez noted.

"Zooming out in time is how I calm myself down after reading the newspapers," Baez concluded. "A mass extinction is a sad thing, but life does bounce back, and it gets more interesting each time. We probably won't kill off all life on Earth. But even if we do, there are a hundred billion stars in our galaxy, and ten billion galaxies in the observable universe."

... the lesson I took from your talk was the under-appreciated title - Zooming. The ability and need to think in MULTIPLE time scales and zoom between them is what is so often missing. Now that I've seen climate in zoom mode, I want to see biology in zoom mode, architecture in zoom mode, technology in zoom mode, and so on.

After my talk there were a bunch of questions, many of which I couldn't answer - see below for more on those. Then some people came up to talk to me. But soon we had to zip off to Il Fornaio for dinner. I went with Stewart and some other Long Now honcho - someone into biodiesel - ah, I'm so lousy with names.

There were about 9 people at dinner. Interesting conversation. They even had me explaining n-categories after the second bottle of wine - but they didn't get me drunk enough to go into detail. Instead, I mainly listened: a lot about renewable energy sources, electric cars, stuff like that - but also the lambda calculus, and unconferences, and weird stuff, like how some anti-government radicals in the US think you don't need to pay income tax if you write your name in all lower-case letters... and how everyone named "Atta" gets hassled at airports since 9/11, including some joker who had changed his legal name to "Attaboy".

The real surprise for me was meeting John Moussouris. You may know him because he just won a $300 million lawsuit against Intel, but I knew of him because I read his thesis on Poincaré group spin networks - he was a student of Roger Penrose at Oxford, so he was working on that sort of thing long before it became fashionable in the loop quantum gravity crowd. Turns out he also worked with Dana Scott on domain theory - which is why he wound up briefly explaining the lambda calculus at this dinner. (It's a unconfortable sensation seeing smart nonmathematicians trying to absorb the fact that if we restrict attention to continuous maps we can get an isomorphism U ≅ U^U, but luckily it was over really quick.)

And - he told me as he drove to my hotel - he'd worked with Ed Fredkin at MIT before quitting academia and going to Silicon Valley. As an MIT grad student, I had a grumpy argument with Fredkin about whether the world is fundamentally digital, while eating at a Chinese restaurant in Kendall Square with Norm Margolus, Tommaso Toffoli and my pal Mark Smith. So, this was one of those "small world" things. Great fun!

It turns out Moussouris is now working on setting up some sort of nonprofit that will help academics with patents involving renewable energy. He's really worried about the effects of a carbon-burning economy - more than me, even. He explained how the massive $200 trillion valuation of all the world's petroleum reserves warps reality in such a way that a board of directors of any oil company has a fiduciary duty to buy up companies that come up with cool ideas that might lessen our dependence on oil, and make sure these ideas never get implemented. He thinks that after we've burned all the clean carbon we'll burn the dirty stuff - to the point where we may need to wear gas masks to breathe outside. A really sad thought. But, he wants to do something about it. And I think that's great.

All in all, an exciting night.

October 18, 2006

One was "How did all those methyl hydrates get formed?" Another was Another, from Stewart Brand, was "How about preventing global warming by sticking a satellite in the Lagrange point between the Sun and the Earth?" - somebody has suggested doing this. And another, from Saheli Datta, was "When did flowering plants show up - before or after the asteroid impact at Chicxulub? How was this related to climate change? Isn't the change in flora more important in some ways than when mammals showed up?"

Indeed, plants are a big deal! I stalled for time by talking about the rise of grasslands, basically quoting myself:

The beginning of the Miocene, 24 million years ago, is when the first grasses arose. It's sort of amazing that something we take so much for granted - grass - can be so new! But grasslands, as opposed to thicker forests and jungles, are characteristic of cooler climates. And as Nigel Calder has suggested, grasslands were crucial to the development of humans! We grew up on the border between forests and grasslands. That has a lot to do with why we stand on our hind legs and have hands rather than paws. Later, the agricultural revolution relied heavily on grasses like wheat, rice, corn, sorghum, rye, and millet. As we ate more of these plants, we bred them in a way that completely changed their characteristics. So, you could say we coevolved with grasses!

Indeed, the sequence of developments leading to humans came shortly after the first grasses. Apes split off from monkeys 21 million years ago, in the Miocene. The genus Homo split off from other apes like gorillas and chimpanzees 5 million years ago, near the beginning of the Pliocene. The fully bipedal Homo erectus dates back to 1.9 million years ago, near the end of the Pliocene.

But anyway, what about flowering plants in general? Now that I'm at a computer I can appear smarter. Turns out a big distinction in plants is between gymnosperms (seed-bearing plants without flowers, like conifers, cycads and ginkgos) and angiosperms (flowering plants). This stuff is interesting:

• Sebastian Molnar, Angiosperm origins and evolution, 2001.

This item suggests that angiosperms started spreading when it got colder:

• Texas A&M University Bioinformatics Working Group, Botany 201, Evolution.

• Neil Roberts, The Holocene: an Environmental History, Blackwell, Oxford, 1998

• As a glacial ends, first comes the protocratic phase, when birches and pines immigrate from southern refuges into what had been tundra.
• In the mesocratic phase, mixed deciduous forest takes over, with oak and elm becoming dominant. During this period the unleached calcareous soils turned into brown forest soils.
• Gradually, leaching from rocks in glacial tills led to a shift from neutral to acid soils, leading to the oligocratic phase favoring trees like spruce.
• As spruce take over, fallen needles make the soil even more acid. Together with cooling temperatures as the next glacial approaches, this leads to the replacement of deciduous forest by heathland and pine forests - the telocratic phase.
• When glaciers move in and scrape away the soil, we reach the cryocratic phase.

It's even cooler when you read this:

It was believed by clasical authors such as Varro and Seneca that there had once been a "Golden Age", "when man lived on those things which the virgin earth produced spontaneously" and when "the very soil was more fertile and productive." If ever there was such a "Golden Age" then surely it was in the early Holocene, when soils were still unweathered and uneroded, and when Mesolithic people lived off the fruits of the land without the physical toil of grinding labour.

For more on the last Ice Age, see my December 1 entry.

Also cool is this article I found from reading Mahelli Datta's website:

• Janet Raloff, Light impacts: Hue and timing determine whether rays are beneficial or detrimental, Science News, 169 (May 27, 2006), p. 330.

Results, published 5 years ago, showed that the biological clock is most responsive to a narrow band of wavelengths from 466 to 477 nanometers (nm), which are close to the blue of a clear sky.

"It's not something we would have predicted," Brainard notes, since these wavelengths aren't ones to which the eye's vision receptors - rods and cones - are most sensitive. The receptors called blue cones have a maximum sensitivity of about 430 nm.

Brainard says that an explanation for the biological clock's blue sensitivity soon emerged in "a landmark paper that stunned the world."

Four years ago, retinal neuroscientist David M. Berson and his colleagues at Brown University in Providence, R.I., described a new class of light receptors in the human eye. These receptors' sensitivity peaked at 480 nm. They are located in a minute share of ganglion cells, the information-processing units that send signals to various parts of the brain. Moreover, these cells appeared to be the most important source of information for brain area, the superchiasmatic nucleus, which is "the biological equivalent to the clock chip on your computer," Berson says.

Still, it's peaceful.

Today I mainly worked on my course on classical versus quantum computation, trying to figure out the best string diagram notation for monoidal compact categories. Not feeling particularly sharp... no deep insights, just sort of chewing away on it. I read and answered email whenever I felt like break, or sometimes did some yardwork, gradually cleaning up my dried-out, part-dead garden.

On August 7th I mentioned Ray Kurzweil's thoughts on the Fermi paradox. The Wikipedia article on the Fermi paradox does a pretty good job of explaining it:

The paradox is a conflict between an argument of scale and probability, and a lack of evidence. A more complete definition could be stated thus:

The size and age of the universe suggest that many technologically advanced extraterrestrial civilizations ought to exist. However, this belief seems logically inconsistent with the lack of observational evidence to support it. Either the initial assumption is incorrect and technologically advanced intelligent life is much rarer than believed, current observations are incomplete and human beings have not detected other civilizations yet, or search methodologies are flawed and incorrect indicators are being sought.

The first aspect of the paradox, "the argument by scale", is a function of the raw numbers involved: there are an estimated 250 billion (2.5 × 10¹¹) stars in the Milky Way and 70 sextillion (7 × 10²²) in the visible universe. Even if intelligent life occurs on only a minuscule percentage of planets around these stars, there should still be a great number of civilizations extant in the Milky Way galaxy alone. This argument also assumes the mediocrity principle, which states that Earth is not special, but merely a typical planet, subject to the same laws, effects, and likely outcomes as any other world. Some estimates using the Drake equation support this argument, although the assumptions behind those calculations have themselves been challenged.

The second cornerstone of the Fermi paradox is a followup to the argument by scale: given intelligent life's ability to overcome scarcity, and its tendency to colonize new habitats, it seems likely that any advanced civilization would seek out new resources and colonize first their star system, and then surrounding star systems. As there is no evidence on Earth or anywhere else of attempted alien colonization after 13 billion years of the universe's history, either intelligent life is rare or assumptions about the general behavior of intelligent species are flawed.

Several writers have tried to estimate how fast an alien civilization might spread through the galaxy. There have been estimates of anywhere from 5 million to 50 million years to colonize the entire galaxy; a relatively small amount of time on a geological scale, let alone a cosmological one.

• S. Webb, If the Universe is Teeming with Aliens... Where is Everybody: Fifty Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life, Praxis Publishing, New York, 2002.

• Civilizations always self-destruct before they colonize the galaxy.
• Civilizations don't bother to colonize the galaxy: they find something much cooler to do.
• We're living in the equivalent of a wild animal park, which the aliens carefully watch from a distance.
• The aliens actually have visited us.

The key point is this:

So we need an explanation that circumvents this.

Kurweil gave two. The first is well-known: maybe we just happen to be the first - or at least, the first within a sphere large enough that none of the others would have reached us yet.

The second seemed more novel to me: even if there are other intelligent civilizations nearby, we can't see them because they're expanding outwards at nearly the speed of light! We won't see them until they're almost here.

A long time ago on this diary, I mentioned my friend Bruce Smith's nightmare scenario. In the quest for ever faster growth, corporations evolve toward ever faster exploitation of natural resources. The Earth is not enough. So, ultimately, they send out self-replicating von Neumann probes that eat up solar systems as they go, turning the planets into more probes. Different brands of probes will compete among each other, evolving toward ever faster expansion. Eventually, the winners will form a wave expanding outwards at nearly the speed of light - demolishing everything behind them, leaving only wreckage.

The scary part is that even if we don't let this happen, some other civilization might.

The last point is the key one. Even if something is unlikely, in a sufficiently large universe it will happen, as long as it's possible. And then it will perpetuate itself, as long as it's evolutionarily fit. Our universe seems pretty darn big. So, even if a given strategy is hard to find, if it's a winning strategy it will get played somewhere.

So, even in this nightmare scenario of "spheres of von Neumann probes expanding at near lightspeed", we don't need to worry about a bleak future for the universe as a whole - any more than we need to worry that viruses will completely kill off all higher life forms. Some fraction of civilizations will probably develop defenses in time to repel the onslaught of these expanding spheres.

Anyway, my friend Jim Dolan recently offered another resolution of the Fermi paradox, which goes something like this. Suppose intelligent civilizations tend to create baby universes for their own use, instead of wasting time on space travel. Then the density of intelligent life in a given universe may never get very high! In this scenario, we're likely to be in a baby universe created for some unfathomable purpose by some civilization that we'll never meet, because they won't bother to travel around this one.

This is just far-out enough to be believable. Outguessing civilizations that have been around millions of years more than ours seems like a loser's bet: sort of like a chimpanzee trying to imagine space travel. But, if we're going to play this game, it probably pays to think big.

This business of our universe being created by another civilization reminds me of this paper:

• S. Hsu and A. Zee, Message in the sky, Mod. Phys. Lett. A21 (2006) 1495-1500.

Abstract: We argue that the cosmic microwave background (CMB) provides a stupendous opportunity for the Creator of our universe (assuming one exists) to have sent a message to its occupants, using known physics. The medium for the message is unique. We elaborate on this observation, noting that it requires only careful adjustment of the fundamental Lagrangian, but no direct intervention in the subsequent evolution of the universe.

Being early-21st-century physicists, Hsu and Zee naturally guess that the creator would use this opportunity to pass on some information that early-21st-century physicists would find interesting: the Cartan matrix of the symmetry group for the gauge theory describing our universe. This seems pretty self-centered. Jews would expect the Ten Commandments, Christians would expect the Lord's Prayer, and mathematicians would like to see the solutions to their favorite chestnuts. For all I know, we'll just see a serial number.

Right now I'm listening to Beck's latest album, The Information. From the song of that title:

Strange era we live in, that such dark lyrics could be so popular. The "single", Nausea, is even darker:

• Richard Dawkins, The God Delusion, Houghton Mifflin, New York, 2006.

I think the implicit American contract where politicians don't talk too much about religion is broken. So, we can expect more atheists to start talking about their views, too. That's probably why these books are selling so well:

• Sam Harris, The End of Faith: Religion, Terror, and the Future of Reason, W. W. Norton, New York, 2005.
• Sam Harris, Letter to a Christian Nation, Random House, New York, 2006.

What took me aback is the position that Harris is advocating - that it is okay to subject religion to careful scrutiny, in fact, it is desirable as religion is having such a negative impact on us all. He's talking about a change in social norms, attitudes, what is considered mannerly... he's saying that we can no longer afford to be respectful and tolerant of others' religious beliefs when those beliefs could do us all in. He suggests that we ask: What is the evidence for your God?

I learnt that a person's religious beliefs are his own private business - every person has to work out his own salvation - and it was not for me to question these beliefs. I learned that it is behavior that counts - how we treat others and the world we live in. But in America this has flipped. Now many people talk about their beliefs, the one-on-one they have with Christ, while they indulge in the most hateful and unchristian behavior. Worse, they think their beliefs call for such behavior. Harris suggests that it is time for us to grab this nettle and challenge religion's hold on so many people.

Where do I stand on this? Well, I try not to talk much about my views on deep philosophical issues, mainly because the only way to be clear is by talking very carefully for a very long time, preferably to one person at time. Ethics and religion - these are among the deepest issues of all.

Politics, however, demands that everything be compressed into sound bites, to move crowds.

October 30, 2006

I think it's time to admit it, and start letting people know: Bush has lost the war in in Iraq.

He had no realistic plans for what to do after the initial invasion. He thought we would be greeted as liberators, and he apparently had no clue about the long enmity between Shiites, Sunnis and Kurds. He never put enough troops in to win the war. He dismantled the Iraqi army, let unemployment soar, and let militias take hold throughout the country.

At the end of April 2003, Bush stood under a banner announcing "Mission Accomplished" and hailed a "job well done".

Over 3 years later, US casualties are rising. A 2-month operation to restore security in Baghdad has failed. Britain's most senior general, Richard Dannatt, has declared the whole invasion a failure. Worst of all, a growing number of Iraqis support attacks on US troops - now a majority:

I think it's only a matter of time before we all realize: Bush started this war, and he lost it.

For my November 2006 diary, go here.

© 2006 John Baez
baez@math.removethis.ucr.andthis.edu

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