Load carrying during locomotion in the barnacle goose (Branta leucopsis): The effect of load placement and size.

“Load carrying has been used to study the energetics and mechanics of locomotion in a range of taxa. Here we investigated the energetic and kinematic effects of trunk and limb loading in walking barnacle geese (Branta leucopsis). A directly proportional relationship between increasing back load mass and metabolic rate was established, indicating that the barnacle goose can carry back loads (up to 20% of body mass) more economically than the majority of mammals… Sternal loads up to 15% of body mass were approximately twice as expensive to carry as back loads… Loading the distal limb with 5% extra mass incurred the greatest proportional rise in metabolism, and also caused increases in stride length, swing duration and stride frequency during locomotion. The increased work required to move the loaded limb may explain the high cost of walking.”

A cache of ostrich eggshell fragments discovered by archaeologists in South Africa could be instrumental in understanding how humans approached art and symbolism as early as the Stone Age. The eggshells, engraved with geometric designs, may indicate the existence of a symbolic communication system around 60,000 years ago among African hunter-gatherers [Discovery News].

At a site known as the Diepkloof Rock Shelter, a team led by archaeologist Pierre-Jean Texier discovered fragments of 25 ostrich eggs that date back 55,000 to 65,000 years. In an online paper published in the Proceedings of the National Academy of Sciences, the archeologists revealed that the eggshell fragments were etched with several kinds of motifs, including parallel lines with cross-hatches and repetitive non-parallel lines [ScienceNow]. The scientists are confident that the markings are almost certainly a form of messaging — of graphic communication [BBC].

Further study of the fragments revealed that a hole had been drilled at the top of some eggshells, suggesting that the hunter-gatherers could have used them as water containers during long hunts in arid regions, as the Kalahari hunter-gatherers were known to do in more recent history. Scientists estimate that each egg could have held one liter of water. The patterns on the shells, they propose, could have been a symbolic way of acknowledging the individual who used the canteen, or which community or family the user belonged to. For scientists studying human origins, the capacity for symbolic thought is considered a giant leap in human evolution, and [what] sets our species apart from the rest of the animal world [BBC].

These eggshells are not the first items that suggest symbolic thinking among stone age people. Archaeologists working in Blombos Cave in South Africa found engraved red ochre, incised bone and pierced shells that were strung and presumably worn on the body—all from layers dated to 75,000 years ago; three shell beads from Israel and Algeria are said to date to more than 100,000 years ago; dozens of pieces of red ochre–many of which were ground for use as pigment–turned up in layers dating to 165,000 years ago in a cave at Pinnacle Point in South Africa [Scientific American]. But some contrary researchers have argued that early engravings and body decorations may have been done for aesthetic purposes unrelated to symbolism.

Still, Texier says the Diepkloof eggshells are special, because so many fragments were found with similar designs, and because engraving the tough ostrich shells would have been a hard task–showing that the designs were not merely scratched-in doodles. The hunter-gatherers also colored their shells by baking them.

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80beats: “Pornographic” Statue Could Be World’s Oldest Piece of Figurative Art
DISCOVER: The Dawn of Abstract Art
DISCOVER: Learning to Love Neanderthals

Image: P.J. Texier

This is awesome.

Straight Outta Vulcan by ~tetsuoshima on deviantART

Also, logical.

It’s generally easy to write a damning book review. It’s much harder to write a positive and enthusiastic one. So how about a review that includes this paragraph?:

I put down Rebecca Skloot’s first book, “The Immortal Life of Henrietta Lacks,” more than once. Ten times, probably. Once to poke the fire. Once to silence a pinging BlackBerry. And eight times to chase my wife and assorted visitors around the house, to tell them I was holding one of the most graceful and moving nonfiction books I’ve read in a very long time.

That’s Dwight Garner reviewing the book for the New York Times. What’s more, this is a nonfiction book revolving around science! Henrietta Lacks died at age 31 of cervical cancer. She was relatively poor, and completely unknown. No tombstone marks her grave. Without any sort of consent or awareness, some of her cells were “stolen” during her treatment. It turned out that the cells could be cultured, and they rapidly became a key tool in biomedicine. Salk used her cells to develop a vaccine for polio. The cells are ubiquitous, living on and thriving half a century after Henrietta Lacks’ death. Although this was all news to me, apparently any self-respecting biologist has heard of HeLa. Her full story has plenty of moral and philosophical implications, as well as basic science. Henrietta Lacks has had a profound, and completely unwitting, impact on our lives. Wired magazine has a chart:

Garner ends his review with:

This is the place in a review where critics tend to wedge in the sentence that says, in so many words, “This isn’t a perfect book.” And “The Immortal Life of Henrietta Lacks” surely isn’t. But there isn’t much about it I’d want to change. It has brains and pacing and nerve and heart, and it is uncommonly endearing. You might put it down only to wipe off the sweat.

I think he liked the book. Other reviews have been similarly enthusiastic (see Skloot’s blog for links). “Immortal Life” is definitely heading to my bedside table. But apparently one of my co-bloggers has recently published a book, and I should probably read that one first. If only I could find time.

Male animals often use their horns to fight over females, but at least one species’ females use their horns to fight over excrement.

The species, no surprise, is the dung beetle. Unlike many of the animals we usually associate with elaborate horns, antlers, or other head weaponry—in which the male has the most impressive set—dung beetle females have horns that put the male version to shame. The reason, says a new study in the Proceedings of the Royal Society B, is that females must battle one another for that precious manure. Nicola Watson and Leigh Simmons of the University of Western Australia, Perth, pitted female dung beetles (Onthophagus sagittarius) against each other in a race for dung – a valuable resource that provides nutrients for their eggs. Matched for body size, females with bigger horns managed to collect more dung and so provide better for their offspring [New Scientist].

Dung beetles aren’t the only species whose females grow horns: Small antelopes called duikers, for instance, have them for self-defense or territorial struggles. But the beetle horns are special, Stankowich says. Female duiker horns generally look like the males’, but female dung beetles grow another type of horn altogether [Science News]. Thus, the researchers argue, the female beetle horns (on the right in the image) aren’t some kind of crossover from the kind of horns that the males grow (left), but rather an independently evolved feature. And, they say, finding out that a feature like this evolved for female reproductive competition rather than defense against predators is exceedingly rare.

You might think there’d be enough poop to go around, and that fighting over it wouldn’t be necessary. However, there’s a distinct advantage toward getting the very best dung to make the balls in which the beetles lay their eggs. “Dung loses its usability quickly, so they have to seize it fast,” says Watson. Female beetles have been found to steal dung, raid other brood balls, and replace existing eggs with their own [New Scientist].

Related Content:
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Image: Sean Stankowski

Three iPhone apps recently came out that pertain to some favorite topics on this blog, so here’s a quick roundup of them.

1) John Cook, like me, got tired of hearing the same old long-debunked claims from global warming deniers being used over and over again, so he created an app debunking these claims. Called Skeptical Science, it divides the claims into three categories: It’s not happening, It’s not us, and It’s not bad. Under each heading are quite a few claims I’ve seen made repeatedly by the deniers, and Cook includes detailed rebuttals.

Overall I like this app, and it’s bound to be handy if you find yourself in a situation where someone is using these same claims (it’s the Sun, the hockey stick graph is flawed, Al Gore is boring, and so on). I might quibble with some of the details — for example, it talks about 1934 being the warmest year on record, but doesn’t mention that 1998, the second warmest, trails behind by a statistically insignificant 0.02 degrees. There’s more like that, but this is such a small detail it really comes down to a matter of style; an "I woulda done it different" kind of thing. The content is good and links are provided for further info.

I recommend having this one handy, so here’s the direct download link.

2) Next up is a NASA app called 3D Sun. And not to trick you or anything, but it’s an app that displays the Sun in 3D. Put out by the folks behind the STEREO probes, it’s a pretty cool gizmo that reports new sunspots and aurorae, lets you look at movies of solar events like plumes, filaments, and coronal mass ejections, and gives you the latest solar news.

The best thing is the 3D Sun itself. It displays the current solar disk, and you can look at it in different wavelengths (UV shows more violent activity) and from different solar observatories. You can zoom in, out, rotate the view, and pretend you’re on a spaceship roaring past our nearby star.

Now that the Sun is finally starting to show some life again, this app is pretty useful so you know what’s the latest. Here’s the direct download link.

3) The third app is called Lunar Electric Rover, and it’s also put out by NASA. Of the three, I think this is the weakest. It’s essentially a game where you command a lunar rover to traverse the Moon to get to different goals. Now, to be fair, I’m not really partial to these kinds of games, so if they’re your thing, you may love this. I found it to be a bit slow and tedious, and the narration was stilted and difficult to hear over the background sound effects. But again, I’m not a big fan of the "go over here and do this" kinds of games. I’ll note that after I took my own notes on the app, I went to the iTunes listings and the ratings are not all that great; out of 102 ratings, 130 scored it as average or below and 62 above average or great. Lots of folks thought the same things I did.

However, I do think some younger kids will enjoy this. The graphics are quite good, and there is real information displayed and used in the game that provide lots of teachable moments. Here’s the download link.

So, do you agree, disagree? All three apps are free, so I encourage readers to grab ‘em, play with ‘em, and leave your own comments below!

Now here is a great way to relax after a busy day; a music box made using the stars to determine what musical note is played.  The software was created by Jim Bumgardner, and he calls it The Wheel of Stars.

Jim Bumgardner, Wheel of Stars

What Mr. Bumbardner did was map the position of the brightest stars from the data provided by ESA’s satellite Hipparcos, and set them to slowly revolve around Polaris… just as we’d see them from the Earth.  It takes almost 24 hours to complete a full rotation.  As the stars cross 0′ and 180′ (marked by a straight line), a musical note or chime is sounded based on each individual star.  BV measurement determines pitch, magnitude determines volume, and the position on the screen is what the stereo panning is based on.

As each star passes the center line, it flashes – or sparkles, if you will.

The sound is very soothing, and it’s possible to pick out familiar stars, constellations, and asterisms.

Here is Jim’s Wheel of Stars website. It’s lovely, and well worth giving it a listen.

There are now over 60 comments at the Point of Inquiry forums on the latest show. So this one has clearly produced a lot of dialogue.

I want to continue to blog about some of the most memorable content–and in this respect, there was nothing like the show’s closing. I asked for Mann’s final words, and boy did I get them. He pointed out that the strength of climate science alone was clearly insufficient to stop the denial movement, and said that we probably should have expected a revival of that movement in the past three months–although even he didn’t expect how low it would go:

Despite all the talk a few years ago about ‘the debate being over’…the forces of anti-scientific disinformation were just lying dormant. But they would be back. And so this didn’t surprise me at all, and in fact, I fully expected that, in advance of the Copenhagen summit, that we would see an increased number of in attacks.

I guess what we all underestimated was the degree, the depth of dishonesty, dirtiness, and cynicism to which the climate change denial movement would be willing to stoop to advance their agenda. That’s the only thing that I think surprised many of us.

You can catch it all at around minute 39-40. Meanwhile, if you haven’t yet, I encourage you to listen to the Mike Mann interview here, and to subscribe to the Point of Inquiry podcast via iTunes.

“A man exhibited typical features of semantic dementia with onset at age 52. At age 55, he became infatuated with polka music. He would sit in his car in the garage and listen to polka on the radio or on cassettes, often for as long as 12 to 18 hours. Whereas some may argue that enjoying polka music is in itself pathologic, we view this patient’s new appreciation of polka similar to that recently described with pop music in two patients with frontotemporal dementia. Thus, heterogeneity in musical taste is yet one more dimension bridging semantic dementia and frontotemporal dementia.”

Thanks to Ace for today’s ROFL!
Photo: flickr/grenade

Related content:
Discoblog: NCBI ROFL: Pink Floyd hallucinations: not just for druggies.
Discoblog: NCBI ROFL: I still think listening to country music is degrading.
Discoblog: NCBI ROFL: Opera makes me want to kill myself.

You’ve probably seen a Rube Goldberg machine in a science museum sometime, and watched with amusement while balls rolled down tracks or balloons inflated, triggering other mechanical events in a complicated chain reaction. But we guarantee you’ve never seen a Rube Goldberg machine quite like this.

When the rock band OK Go, justly famous for its treadmill dancing video, decided to make a new music video for its song “This Too Shall Pass,” the rockers tapped the artsy engineers at Syyn Labs to do something really special. The result was this 4-minute Rube Goldberg machine that plays part of the song, synchronizes with the beat, and involves the band members getting very messy. It runs the length of a two-story warehouse, and the action was filmed in a single shot. With no further ado, we give you: The mother of all Rube Goldberg machines.

Related Content:
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Discoblog: NCBI ROFL: I Still Think Listening to Country Music Is Degrading
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Discoblog: Quirky Musicians + Clever iPhone Apps = the MoPho Orchestra

Video: OK Go / Synn Labs

If you’ve been paying attention here the past few months, you already know that the British Chiropractic Association is suing Simon Singh because he dared tell the truth about them in a newspaper article.

After the BCA aimed, cocked, and shot themselves in the foot, a lot of collateral damage has taken place as well. You may remember what I called Chiropocalypse, where a lot of other UK chiropractors suddenly found themselves in hot water, making claims on their websites they couldn’t back up… and instead of backing up their claims with evidence, chose instead to take their sites down.

Well, it looks like those chickens have come home to roost. According to an article in the Guardian, one out of every four chiropractors in Britain is under investigation for false claims.

Let’s see, what are the words I’m looking for? Ah yes: this.

Even better, it looks like this happened because skeptics stepped up the pressure in direct response to the BCA suing Simon. This is basically a case of The Streisand Effect, and a happier outcome is hard to imagine. Unless, of course, that ratio rises to 100% of all chiropractors making false claims.

Tip o’ the herniated disk to Nigel Gomm.

Water, water, everywhere! Radar results from a lunar probe have revealed that the moon’s north pole could be holding millions of tons of water in the form of thick ice, raising the possibility that human life could be sustained on Earth’s silvery satellite, NASA scientists said.

A NASA radar aboard India’s Chandrayaan-I lunar orbiter found 40 craters, ranging in size from 1 to 9 miles across, with pockets of ice. Scientists estimate at least 600 million tons of ice could be entombed in these craters [Wired].

Scientists estimate that this amount of water could easily sustain a moon base, or, if the oxygen in the ice was converted to fuel, could fire one space shuttle per day for 2,200 years. Last year, scientists found almost 26 gallons of water ice on the moon’s south pole, by crashing a rocket hull into a cold, dark crater. The crash produced a plume of material that provided evidence of water ice on the moon’s surface.

The craters which house the water deposits at both the north and south poles of the moon are extremely dark, cold, and most never catch any sunlight. Temperatures in some of these permanently darkened craters can drop as low as 25 Kelvin (-248C; -415F) — colder than the surface of Pluto — allowing water-ice to remain stable [BBC]. Presenting the findings at a major planetary science conference in Texas, Paul Spudis of Houston’s Lunar and Planetary Institute said the ice at the north pole could be buried under a layer of lunar soil, which may have prevented it from being vaporized even in crater regions that are exposed to sunlight.

The findings, which will be published in the journal Geophysical Research Letters, are the strongest indication yet that the moon could sustain a human outpost. Says Spurdis: “Now we can say with a fair degree of confidence that a sustainable human presence on the Moon is possible. It’s possible using the resources we find there” [BBC]. But what a case of bad timing. The findings come just one month after the Obama administration proposed that NASA give up on its mission of returning to the moon by 2020.

So how does lunar water form? Scientists suggest that chemical reactions triggered by the solar wind, the fast-moving stream of particles that blows away from the sun, could be the source. In this method, the radiation would cause oxygen molecules already in the soil to acquire hydrogen. This means that there might not be obvious skating rinks of ice in the lunar craters, but instead so-called “adsorbed” water may be present as a fine film that coats soil particles. Other researchers have suggested that ice was delivered to the moon in comet and asteroid impacts.

But the findings are literally the tip of the iceberg, and lead to a host of further questions: How does the water move around? What percentage of the water is adsorbed molecules? What percentage is ice filling pore space? And what portion of it is the solid chunks that could nourish human exploration? [Nature blog] Researchers will have to keep investigating to find out.

Related Content:
80beats: NASA: Bombing The Moon Provided Definite Evidence of Lunar Water
Bad Astronomy: NASA Finds Reservoir of Water Ice on the Moon!
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80beats: So What Exactly Happened with that Crashing Moon Probe?
80beats: Lunar Impact! NASA Probe Slams into Moon to Search for Water

Image: NASA

A physics student here at UC Davis, Austin Sendek, has launched a campaign to add another designator to the list of numeric SI prefixes such as kilo-, mega-, etc. to cover 10²⁷: hella. For example, 1 hellagram would be 10²⁷ grams, or 1000 yottagrams.

The term “hella” is one I first heard my sister-in-law utter in the context “that ski run was hella fun!”, which I immediately took as a shorthand for “a hell of a lot of”. I’ve since learned that it originated, reportedly, in San Francisco to mean just that, or “very” in general, as in “that tee shirt is hella awesome” – it’s not an uncommon utterance to hear here in northern California.

And, 10²⁷ is hella big, to be sure. A hellasecond is ten billion times the age of the universe, and the mass of the earth is about 6 hellagrams.

It seems that hella is poised to go viral…there are nearly 24,000 fans of the facebook petition, and it even made the local news last night in Sacramento.

Who decides such things? The International Bureau of Weights and Measures, that’s who. They added yotta in 1991. Sign the petition to them at the facebook site!

Over the next few weeks, the European probe Mars Express will be making a series of close passes to the Martian moon Phobos, a wrecked potato that has had an extensively battered history. In January, ME got this shot (among others):

You can see that this little moon has been kicked around quite a bit. Those parallel grooves are still a bit of a mystery; they are most likely cracks that formed when Phobos got whacked, creating the 10-km-wide crater Stickney on one end, but that matter is not 100% settled. Maybe these new observations will help end the debate.

And as nice as this image is, we’ll be getting lots better ones soon! So this is a heads-up: closest approach is on March 3, so stayed tuned for more pictures. I’ll post ‘em as I see ‘em.

Take a good look: according to a new study in PLoS Biology, what you see in this image is a snake about to prey on dinosaur eggs, a 67-million-year-old scene frozen in time and finally discovered. It’s the first time that a snake has been seen eating a dinosaur. The snake is that bit of bones on the left, lead researcher Jeff Wilson says. The egg in the top right contains a tiny titanosaur, one of largest dinosaur groups to ever walk the Earth.

“The snake (Sanajeh indicus) probably lived around the nesting ground and preyed upon hatchlings. They all died instantly when they were covered by a big pulse of sediment from a nearby hill loosened by a storm,” says Wilson [New Scientist]. Wilson guesses that a storm or some other malady might have led the enormous adult dinos to leave the nest, opening the door for the snake to slither in, wait for the baby dinos to hatch, and snack on them. But it never got the chance.

Unlike modern snakes, S. indicus lacked jaw joints that allowed it to open its mouth incredibly wide, so it relied on its large overall body size to prey on the fledgling dinosaurs [Wired.com]. However, researchers say it’s rare to find a snake specimen from the period, especially one as complete as the one here. Fully developed, the snake would’ve been nearly 12 feet long. And while the titanosaur would’ve reached immense size if it had grown to adulthood, the baby seen here is only 20 inches long—easy prey.

If at first you have a hard time seeing a snake in the jumble of fossils, don’t worry—the team did, too. Researchers found the fossil in India in 1984, but thought the area contained only dino bones. It wasn’t until 2001 that Wilson took a second look at it, and the team finally figured out they were looking at snake remains and began to piece the puzzle together. “It was such a thrill to discover such a portentous moment frozen in time,” said Dr Dhananjay Mohabey from the Geological Survey of India, who unearthed the fossil [BBC News].

Related Content:
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80beats: New Analysis Reveals Color of Dinosaur Feathers for the First Time
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80beats: Super-Sized Snake Ate Crocodiles For Breakfast

Images: Jeff Wilson / PLoS, Tyler Keillor / Ximena Erickson / Bonnie Miljour

In a study done a year ago — before Andrew Wakefield was found to be unethical, dishonest, and irresponsible, and his paper which started this whole thing withdrawn from the Lancet — it was found that one in four parents thought autism was related to vaccines. However, the study also found that of these, many felt that vaccines were still important in protecting children from disease.

While that number is high, that added part about protection is very heartening. If we can show those parents the reality that vaccines have nothing to do with autism, then maybe we’ll see the number of children suffering, and even dying, from preventable diseases drop.

After all, we can prevent measles, mumps, rubella, pertussis, HiB, and many other illnesses. But the thing is, we can also prevent ignorance. We just have to shine a light on it.

There are many who will try to extinguish that light. But we have to make sure we hold that light steady and true. It can be tiring, since the antivaxxers are loud and seemingly relentless in their zealous crusade. But we have a huge advantage on our side: we’re right. Reality will always win out, and we just have to make sure that it does so quickly, before more children lose their lives.

Tip o’ the syringe to BABloggee Randyt.

Atrazine, one of the world’s most widely used herbicides, is wreaking havoc on the sex lives of male frogs. In a new experiment, exposure to the chemical emasculated more than half of the male African claw frogs in the study, and made one in ten turn into females. The results, which were published in the Proceedings of the National Academy of Sciences, have raised concerns that the herbicide found in waterways is altering amphibians’ hormones, and could potentially have similar effects on other animals, including humans.

Biologist Tyrone Hayes studied 40 male control tadpoles along with 40 male tadpoles reared in water tainted with atrazine. The levels of the chemical matched the levels the frogs would encounter in their natural settings, and was also within the drinking water standards set by the Environmental Protection Agency. The results showed that 75 percent of male tadpoles reared in atrazine-contaminated water developed into frogs that had low testosterone levels, decreased breeding gland size, feminized laryngeal development, suppressed mating behavior, reduced sperm production and decreased fertility, while the control group showed features typically found in male frogs [AFP]. Most of these “chemically castrated” frogs were unable to reproduce.

The rest of the results were even more dramatic. Ten percent of tadpoles raised in the chemically tainted water developed into frogs with male genetics but female anatomy, and some of these were actually able to breed and produce eggs. The offspring, researchers found, were all male because both parents contributed male genes. Scientists worry that the sex-reversed males and the subsequent production of all-male offspring is skewing the sex ratio of wild frog populations, and may be contributing to the decline of frog populations worldwide.

This is not the first time that Hayes has found atrazine to be wreaking havoc on male frogs. In 2002, working on the African clawed frog, the researchers found that tadpoles raised in atrazine-contaminated water become hermaphrodites – they develop both female (ovaries) and male (testes) gonads. This occurred at atrazine levels as low as 0.1 parts per billion (ppb), 30 times lower than levels allowed in drinking water by the EPA (3 ppb) [University of California, Berkeley]. Subsequent studies in the Midwest showed that male leopard frogs living in atrazine-contaminated streams often had eggs in their testes. They also had lower testosterone levels and smaller voice boxes, which scientists presumed hampered their ability to call mates.

Other studies have found that atazine can interfere with the hormones and sexual development of fish, birds, and rats. Hayes says his new findings should raise alarms about human health. “It’s a chemical . . . that causes hormone havoc,” Hayes said. “You need to look at things that are affecting wildlife, and realize that, biologically, we’re not that different” [Washington Post].

However, Syngenta, the leading manufacturer atrazine, has disputed Hayes’ studies. Hayes responded by saying that people will have to make a final call on whether the costs of atrazine exposure outweigh its benefits: “Not every frog or every human will be affected by atrazine, but do you want to take a chance, what with all the other things that we know atrazine does, not just to humans but to rodents and frogs and fish?”[AFP].

An estimated 80 million pounds of atrazine is used annually in the United States, and it’s commonly found in ground and surface water. About 75% of stream water samples and 40% of groundwater samples contain atrazine, according to the U.S. Geological Survey. The Natural Resources Defense Council, an environmental advocacy group, detected atrazine in 90% of tap water samples from 139 water systems [USA Today]. The EPA is currently reviewing the herbicide, while several states are considering banning it all together. Atrazine is already banned in the European Union.

Join Discover Magazine on Facebook.

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Image: Tyrone Hayes

Registration for The Amaz!ng Meeting 8 is now open!

Wow, what a lineup. Richard Dawkins, folks, as well as a whole passel of skeptical stars. I couldn’t help but notice I’m on that list as well. I’d better come up with a talk.

But I have a little while; TAM 8 is July 8 – 11. Maybe by then I’ll be able to open up on My Sooper Sekrit Project™. And show my tattoo!

So go and sign up. TAM 8 is the Woodstock of skepticism, and has earned that moniker. Man, it’s 5 months away and I already can’t wait!

Welcome to this week’s installment of the From Eternity to Here book club. Finally we dig into the guts of the matter, as we embark on Chapter Eight, “Entropy and Disorder.”

Excerpt:

Why is mixing easy and unmixing hard? When we mix two liquids, we see them swirl together and gradually blend into a uniform texture. By itself, that process doesn’t offer much clue into what is really going on. So instead let’s visualize what happens when we mix together two different kinds of colored sand. The important thing about sand is that it’s clearly made of discrete units, the individual grains. When we mix together, for example, blue sand and red sand, the mixture as a whole begins to look purple. But it’s not that the individual grains turn purple; they maintain their identities, while the blue grains and the red grains become jumbled together. It’s only when we look from afar (“macroscopically”) that it makes sense to think of the mixture as being purple; when we peer closely at the sand (“microscopically”) we see individual blue and red grains.

Okay cats and kittens, now we’re really cooking. We haven’t exactly been reluctant throughout the book to talk about entropy and the arrow of time, but now we get to be precise. Not only do we explain Boltzmann’s definition of entropy, but we give an example with numbers, and even use an equation. Scary, I know. (In fact I’d love to hear opinions about how worthwhile it was to get just a bit quantitative in this chapter. Does the book gain more by being more precise, or lose by intimidating people away just when it was getting good?)

In case you’re interested, here is a great simulation of the box-of-gas example discussed in the book. See entropy increase before your very eyes!

Explaining Boltzmann’s definition of entropy is actually pretty quick work; the substantial majority of the chapter is devoting to digging into some of the conceptual issues raised by this definition. Who chooses the coarse graining? (It’s up to us, but Nature does provide a guide.) Is entropy objective, or does it depend on our subjective knowledge? (Depends, but it’s as objective as we want it to be.) Could entropy ever systematically decrease? (Not in a subsystem that interacts haphazardly with its environment.)

We also get into the philosophical issues that are absolutely inevitable in sensible discussions of this subject. No matter what anyone tells you, we cannot prove the Second Law of Thermodynamics using only Boltzmann’s definition of entropy and the underlying dynamics of atoms. We need additional hypotheses from outside the formalism. In particular, the Principle of Indifference, which states that we assign equal probability to every microstate within any given macrostate; and the Past Hypothesis, which states that the universe began in a state of very low entropy. There’s just no getting around the need for these extra ingredients. While the Principle of Indifference seems fairly natural, the Past Hypothesis cries out for some sort of explanation.

Not everyone agrees. Craig Callender, a philosopher who has thought a lot about these issues, reviewed my book for New Scientist and expresses skepticism that there is anything to be explained. (A minority view in the philosophy community, for what it’s worth.) He certainly understands the need to assume that the early universe had a low entropy — as he says in a longer article, “By positing the Past State the puzzle of the time asymmetry of thermodynamics is solved, for all intents and purposes,” with which I agree. Callender is simply drawing a distinction between positing the past state, which he’s for, and trying to explain the past state, which he thinks is a waste of time. We should just take it as a brute fact, rather than seeking some underlying explanation — “Sometimes it is best not to scratch explanatory itches,” as he puts it.

While it is absolutely possible that the low entropy of the early universe is simply a brute fact, never to be explained by any dynamics or underlying principles, it seems crazy to me not to try. If we picked a state of the universe randomly out of a hat, the chances we would end up with something like our early universe are unimaginably small. To most of us, that’s a crucial clue to something deep about the universe: it’s early state was not picked randomly out of a hat! Something should explain it. We can’t be completely certain that such an explanation exists, but cosmology is hard enough without choosing to ignore the most blatant clues that nature is sticking under our noses.

This chapter and the next two are the heart and soul of the book. I hope that the first part of the book is interesting enough that people are drawn in this far, because this is really the payoff. It’s all interesting and fun, but these three chapters are crucial. Putting it into the context of cosmology, as we’ll do later in the book, is indispensable to the program we’re outlining, but the truth is that we don’t yet know the final answers. We do know the questions, however, and here is where they are being asked.

According to a new study in the Proceedings of the National Academy of Sciences, chivalry just depends on how much time you’ve got.

That was the conclusion Benno Torgler and colleagues arrived at by studying two of history’s most famous shipwrecks: The Titanic, where social norms seem to have prevailed and women and children had a better chance of surviving, and the Lusitania, where they did not. The rapid sinking of the Lusitania appears to have triggered the selfish instinct for survival in its passengers, while the slow sinking of the Titanic may have allowed altruism to reemerge.

More than 1,500 people died when the Titanic struck an iceberg in 1912 and sank over the course of three hours in the freezing waters of the North Atlantic. In their analysis, the researchers studied passenger and survivor lists from both ships, and considered gender, age, ticket class, nationality and familial relationships with other passengers. The differences emerged after a closer look at the survival rates [The New York Times]. Children aboard the Titanic, researchers say, were about 15 percent more likely to survive than adults, and women had more than a 50 percent better chance than men to make it out alive.

But while the Lusitania disaster occurred only three years after the Titanic, researchers say that the passenger reaction was quite different. The Lusitania took just 18 minutes to sink on 7 May 1915, torpedoed by a German U-boat just off Kinsale in Ireland, on a voyage between New York and Liverpool: 1,198 died, and it was literally survival of the fittest among the 639 who escaped [The Guardian]. People between the ages of 16 and 35 had the best chance of surviving the Lusitania, the scientists say, not only because there was so little time, but also because the escape was hazardous and the lifeboats rocked violently.

There are many confounding factors in a disaster, but Torgler argues that time was the key. With the Titanic sinking so slowly, he argues, social norms reemerged: Not only did women and children fare better, but upper class people were more likely to survive the Titanic wreck than the Lusitania, which devolved into a mad dash to the lifeboats. However, psychologist Daniel Kruger says that leadership could play a large role, too. The Titanic crew was more successful in maintaining order than the crew of the Lusitania. “People might be in a state of panic, but if they are reassured there is a system in place, they might be more likely to go along with contingency plans,” Kruger said [Los Angeles Times].

The life-and-death drama of events like the Titanic and Lusitania provide researchers a window to further figure out how people behave under pressure. Torgler and his colleagues are studying the reactions to more recent disasters — namely in the use of text messages, including those sent by people trapped during the World Trade Center attacks on Sept. 11 [The New York Times].

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Image: National Archive