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kottke.org posts about science

Do we live in a computer simulation?

In 2003, British philosopher Nick Bostrom suggested that we might live in a computer simulation. From the abstract of Bostrom’s paper:

This paper argues that at least one of the following propositions is true: (1) the human species is very likely to go extinct before reaching a “posthuman” stage; (2) any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history (or variations thereof); (3) we are almost certainly living in a computer simulation. It follows that the belief that there is a significant chance that we will one day become posthumans who run ancestor-simulations is false, unless we are currently living in a simulation. A number of other consequences of this result are also discussed.

The gist appears to be that if The Matrix is possible, someone has probably already invented it and we’re in it. Which, you know, whoa.

But researchers believe they have devised a test to check if we’re living in a computer simulation.

However, Savage said, there are signatures of resource constraints in present-day simulations that are likely to exist as well in simulations in the distant future, including the imprint of an underlying lattice if one is used to model the space-time continuum.

The supercomputers performing lattice quantum chromodynamics calculations essentially divide space-time into a four-dimensional grid. That allows researchers to examine what is called the strong force, one of the four fundamental forces of nature and the one that binds subatomic particles called quarks and gluons together into neutrons and protons at the core of atoms.

“If you make the simulations big enough, something like our universe should emerge,” Savage said. Then it would be a matter of looking for a “signature” in our universe that has an analog in the current small-scale simulations.

If it turns out we’re all really living in an episode of St. Elsewhere, I’m going to be really bummed. (via @CharlesCMann)


Immortality lessons from the humble jellyfish

Looking to live forever? You might want to take a close look at the immortal jellyfish. This death-defying creature ages, but researchers studying the jellyfish found that, instead of dying, it started “to age in reverse, growing younger and younger until it reached its earliest stage of development, at which point it began its life cycle anew.” (If beginning the life cycle anew means another trip through junior high, count me out.) From NYT Magazine: Can a Jellyfish Unlock the Secret of Immortality?


These birds teach their baby chicks a secret family password

Fairy wrens have a cuckoo problem. Specifically, cuckoos lay their eggs in the nest of the fairy wrens and, if undetected, they would end up raising the baby cuckoos to the potential detriment of their own children. But what the fairy wren mother does is after laying her eggs, she sings a unique song to the eggs until they hatch. Having learned the song while in-egg, the hatched baby wrens sing back part of the song to get fed.

She kept 15 nests under constant audio surveillance, and discovered that fairy-wrens call to their unhatched chicks, using a two-second trill with 19 separate elements to it. They call once every four minutes while sitting on their eggs, starting on the 9th day of incubation and carrying on for a week until the eggs hatch.

When Colombelli-Negrel recorded the chicks after they hatched, she heard that their begging call included a single unique note lifted from mum’s incubation call. This note varies a lot between different fairy-wren broods. It’s their version of a surname, a signature of identity that unites a family. The females even teach these calls to their partners, by using them in their own begging calls when the males return to the nest with food.

These signature calls aren’t innate. The chicks’ calls more precisely matched those of their mother if she sang more frequently while she was incubating. And when Colombelli-Negrel swapped some eggs between different clutches, she found that the chicks made signature calls that matches those of their foster parents rather than those of their biological ones. It’s something they learn while still in their eggs.

(via bruce schneier)


Why do kids cover their eyes when they’re hiding?

Children often close or cover their eyes to hide, and researchers at the University of Cambridge wanted to find out why. Click through for more interesting snippets.

Now things get a little complicated. In both studies so far, when the children thought they were invisible by virtue of their eyes being covered, they nonetheless agreed that their head and their body were visible. They seemed to be making a distinction between their “self” that was hidden, and their body, which was still visible. Taken together with the fact that it was the concealment of the eyes that seemed to be the crucial factor for feeling hidden, the researchers wondered if their invisibility beliefs were based around the idea that there must be eye contact between two people — a meeting of gazes — for them to see each other (or at least, to see their “selves”).

(via @noahwg)


Richard Feynman’s last interview

Aired as The Quest For Tannu Tuva in the UK and The Last Journey Of A Genius in the US, this hour-long program is the last extended interview that physicist Richard Feynman gave; he died a few days after the recording.

Richard Feynman was not only an iconoclastic and influential theoretical physicist and Nobel laureate but also an explorer at heart. Feynman through video recordings and comments from his friend and drumming partner Ralph Leighton tell the extraordinary story of their enchantment with Tuva, a strange and distant land in the centre of Asia.

While few Westerners knew about Tuva, Feynman discovered its existence from the unique postage stamps issued there in the early 20th century. He was intrigued by the unusual name of its capital, Kyzyl, and resolved to travel to the remote, mountainous land. However, the Soviets, who controlled access, were mistrustful, unconvinced that he was interested only in the scenery. They obstructed his plans throughout 13 years.

I could watch this guy talk all day long. Feynman is a national treasure; we should give Andrew Jackson the boot and put Feynman on the $20.


Earth-sized planet found only 4.3 light years away

A European team of exoplanet hunters has discovered a planet about the size of Earth orbiting Alpha Centauri B, which is in a group of stars closest to the solar system, a mere 4.3 light years away. Lee Billings explains the significance.

At a distance of just over 4.3 light years, the stars of Alpha Centauri are only a cosmic stone’s throw away. To reach Alpha Centauri B b, as this new world is called, would require a journey of some 25 trillion miles. For comparison, the next-nearest known exoplanet is a gas giant orbiting the orange star Epsilon Eridani, more than twice as far away. But don’t pack your bags quite yet. With a probable surface temperature well above a thousand degrees Fahrenheit, Alpha Centauri B b is no Goldilocks world. Still, its presence is promising: Planets tend to come in packs, and some theorists had believed no planets at all could form in multi-star systems like Alpha Centauri, which are more common than singleton suns throughout our galaxy. It seems increasingly likely that small planets exist around most if not all stars, near and far alike, and that Alpha Centauri B may possess additional worlds further out in clement, habitable orbits, tantalizingly within reach.


Women of science posters

I love these posters featuring six women who changed science and the world. Hard to pick a favorite but I’ll go with the Sally Ride one:

Sally Ride Poster

The Rosalind Franklin poster is a close second. The same artist also did this wonderfully minimalist poster for Louis Braille.

ps. Today is Ada Lovelace Day!


DNA has a 521-year half-life

Researchers in Copenhagan and Perth used DNA found in the leg bones of the extinct moa bird to determine the half-life of DNA: 521 years.

By comparing the specimens’ ages and degrees of DNA degradation, the researchers calculated that DNA has a half-life of 521 years. That means that after 521 years, half of the bonds between nucleotides in the backbone of a sample would have broken; after another 521 years half of the remaining bonds would have gone; and so on.

The team predicts that even in a bone at an ideal preservation temperature of -5 ºC, effectively every bond would be destroyed after a maximum of 6.8 million years. The DNA would cease to be readable much earlier — perhaps after roughly 1.5 million years, when the remaining strands would be too short to give meaningful information.

That means no real-life Jurassic Park, folks.


What percentage Neanderthal are you?

In the last few years, scientists have discovered that before Neanderthals went extinct around 30,000 years ago, they interbred with modern humans. As a result, many humans alive today contain Neanderthal DNA in their genomes, typically between 1-4%.

Yesterday, a few of the editors at The Atlantic had their genes analyzed for Neanderthal DNA: Alexis Madrigal had 3.6%, Steve Clemons had 4.3%, and James Fallows had 5%. Personal genetic information company 23andMe added the ability to determine your Neanderthal DNA percentage a few months ago and it turns out 2.7% of my DNA is from Neanderthals, compared to 2.5% for the average 23andMe user.

If you have a 23andMe acct, you can check your percentage by logging in and going to “Ancestry Labs” in the sidebar.


The Boomerang Meteor

While driving a couple weeks ago, I happened to catch a meteor shooting across the sky:

Saw one of the coolest things ever tonight: a meteor burning up in the lower atmosphere. Super bright, exploded at the end like a firework.

It turned out that “one of the coolest things ever” wasn’t hyperbole. You see, earlier that day over the UK, a meteor streaked across the sky for about 50 seconds:

And then the one I saw happened about two-and-a-half hours later. Spurred by this unlikely coincidence, mathematician Esko Lyytinen of the colorfully named Finnish Fireball Working Group of the Ursa Astronomical Association did some calculations and determined that the two events were actually the same meteor.

He believes a large body grazed the upper atmosphere, dipping to an altitude of 33 miles (53 km) over Ireland before escaping back to space. Because it arrived moving at only about 8 miles (13 km) per second, barely above Earth’s escape velocity, it lingered for more than a minute as it crossed the sky. (This explains why some witnesses mistook it for reentering spacecraft debris.)

Lyytinen says the brief atmospheric passage took its toll. As the meteoroid broke apart, its velocity dropped to just 5.7 miles (9.2 km) per second, too slow to make an escape back to space. Instead, it became a temporary satellite of Earth, looping completely around the globe before reentering the atmosphere — this time for good. “It looks now that the fireball witnessed 155 minutes later in U.S. and Canada, may have been one fragment of the British fireball, most probably the biggest one,” Lyytinen explains.

Boomerang Meteor

These earth-grazers are not common but they do happen from time to time. But a visible Earth grazing meteor that enters the atmosphere twice? Unprecedented. So cool! (thx, alex)


Changing the color of the Moon with laser pointers

Hey, if Randall keeps writing them, I’m gonna keep posting links to them…today’s XKCD What If is “If every person on Earth aimed a laser pointer at the Moon at the same time, would it change color?

Unfortunately, the laser energy flow would turn the atmosphere to plasma, instantly igniting the Earth’s surface and killing us all.


In which Mars Curiosity finds a river bed

Earlier this month, the Curiosity rover photographed a dry stream bed on the surface of Mars.

Mars Curiosity River Bed

That’s the Mars river bed on the left and an Earth river bed on the right. Note the flat smooth rocks in the Mars pic. Pretty cool.


Fruit salad trees

Plant grafting is something I always sort of knew existed, but never really thought it worked well enough to create fruit salad trees. A plant with multiple different kinds of herbs would be amazing.

In Australia, James and Kerry West grow and sell four types of fruit salad trees, each of which bears several different kinds of fruit. Stone fruit salad trees grow peaches, plums, nectarines, apricots and peachcots. Citrus salad trees offer a winter and summer orange, mandarins, lemons, limes, grapefruits, tangelos and pomelos. Multi-apple trees boast between two and four different kinds of apples and multi-nashi trees produce between two and four different kinds of Asian pears.

(thanks, Jessie)


The story of how Gorilla Glass came to be

Gorilla Glass is the thin strong glass used for the screens of most smartphones. It was invented in the 1960s by Corning but was shelved in the early 1970s due to a lack of demand. The iPhone brought it out of retirement in a big way.

Chemical strengthening, the method of fortifying glass developed in the ’60s, creates a compressive layer too, through something called ion exchange. Aluminosilicate compositions like Gorilla Glass contain silicon dioxide, aluminum, magnesium, and sodium. When the glass is dipped in a hot bath of molten potassium salt, it heats up and expands. Both sodium and potassium are in the same column on the periodic table of elements, which means they behave similarly. The heat from the bath increases the migration of the sodium ions out of the glass, and the similar potassium ions easily float in and take their place. But because potassium ions are larger than sodium, they get packed into the space more tightly. (Imagine taking a garage full of Fiat 500s and replacing most of them with Chevy Suburbans.) As the glass cools, they get squeezed together in this now-cramped space, and a layer of compressive stress on the surface of the glass is formed. (Corning ensures an even ion exchange by regulating factors like heat and time.) Compared with thermally strengthened glass, the “stuffing” or “crowding” effect in chemically strengthened glass results in higher surface compression (making it up to four times as strong), and it can be done to glass of any thickness or shape.

I did glass research in college so I’m a sucker for this sort of thing. (via @joeljohnson)


A Skrillex storm with “a single giant drop”

XKCD’s What If? science feature continues to delight. This week’s question is “What if a rainstorm dropped all of its water in a single giant drop?”

The drop is now falling at 90 meters per second (200 mph). The roaring wind whips up the surface of the water into spray. The leading edge of the droplet turns to foam as air is forced into the liquid. If it kept falling for long enough, these forces would gradually disperse the entire droplet into rain.

Before that can happen, about 20 seconds after formation, the edge of the droplet hits the ground. The water is now moving at over 200 m/s (450 mph). Right under the point of impact, the air is unable to rush out of the way fast enough, and the compression heats it so quickly that the grass would catch fire if it had time.

Fortunately for the grass, this heat lasts only a few milliseconds because it’s doused by the arrival of a lot of cold water. Unfortunately for the grass, the cold water is moving at over half the speed of sound.


Zero gravity yo-yo tricks

It turns out that yo-yos work pretty well in space. Astronaut Don Pettit demontrates from the International Space Station.

(via explore)


Mr. Wizard, still a dick

Previously. (via to)


Tantalizing evidence of room temperature superconductivity

Researchers in Germany have found evidence of room temperature superconductivity in graphite powder that has been soaking in water and then dried. Not surprisingly, the results come with a few caveats:

First, this is not a conventional bulk material. The claim from Germany is that the superconductivity occurs at the interface between grains of graphite after they have dried out.

So that’s a surface effect which involves only a tiny fraction of the total mass of carbon in the powder—just 0.0001 per cent of the mass, according to Esquinazi and co.

What’s more the effect is clearly fragile. Esquinazi and co say the superconductivity disappears if the treated powder is pressed into pellets.

So whatever allows the superconductivity to occur at the grain interfaces is destroyed when the grains are pressed together.

I’m pretty sure this is the technology used by the aliens who designed The Machine in Contact.


The not-so-magic cooling glove

Writing for Slate, Daniel Engber takes a closer look at the magic cooling glove and finds some (but not a lot of) evidence that the thing actually works as advertised.

The study, which aggregates results from a decade’s worth of experiments, found that “palm cooling” helped people do 144 percent more pull-ups than they did before, on average. A closer look reveals that the effect might not be so beefy as it looks, however. That figure comes from testing just a handful of people in the lab-even after 10 years of research-and it has some honking error bars (+/-83 percent). To put it in perspective: Before the palm-cooled training, their scores ranged from 70 to 153 pull-ups in each session; after training, they ranged from 70 to 616.


Nanocrystalline cellulose is the new carbon nanotube

Nanocrystalline cellulose is made from wood pulp, is light, strong, and even conducts electricity.

So why all the fuss? Well, not only is NCC transparent but it is made from a tightly packed array of needle-like crystals which have a strength-to-weight ratio that is eight times better than stainless steel. Even better, it’s incredibly cheap.

“It is the natural, renewable version of a carbon nanotube at a fraction of the price,” says Jeff Youngblood of Purdue University’s NanoForestry Institute in West Lafayette, Indiana.


Obama and Romney talk science

In partnership with sciencedebate.org, Scientific American asked both major party candidates to answer questions about the important scientific questions of the day. Here are the results.

I am not a scientist myself, but my best assessment of the data is that the world is getting warmer, that human activity contributes to that warming, and that policymakers should therefore consider the risk of negative consequences. However, there remains a lack of scientific consensus on the issue — on the extent of the warming, the extent of the human contribution, and the severity of the risk — and I believe we must support continued debate and investigation within the scientific community.


Magic cooling glove “better than steroids” for athletic performance improvement

Leveraging the high number of specialized heat-transfer veins in the palm of the human hand, researchers at Stanford have developed a thermal exchange glove that is able to cool a person’s core temperature in a matter of minutes. Turns out this is helpful for athletes.

The glove’s effects on athletic performance didn’t become apparent until the researchers began using the glove to cool a member of the lab — the confessed “gym rat” and frequent coauthor Vinh Cao — between sets of pull-ups. The glove seemed to nearly erase his muscle fatigue; after multiple rounds, cooling allowed him to do just as many pull-ups as he did the first time around. So the researchers started cooling him after every other set of pull-ups.

“Then in the next six weeks he went from doing 180 pull-ups total to over 620,” said Heller. “That was a rate of physical performance improvement that was just unprecedented.”

The researchers applied the cooling method to other types of exercise — bench press, running, cycling. In every case, rates of gain in recovery were dramatic, without any evidence of the body being damaged by overwork - hence the “better than steroids” claim.

The cooling resets a temperature-sensitive enzyme that muscles need to generate energy, “essentially resetting the muscle’s state of fatigue”. I expect this will be either everywhere in pro sports in a couple of years or banned. (via @jsnell)


Squid’s membrane goes insane while listening to Cypress Hill

The crazy (and possibly high) folks at Backyard Brains hooked an iPod up to a squid in such a way that when the music played, it was converted into electrical impulses that triggered color changes on the squid’s skin, thereby creating the world’s first cephalo-iPod. Here’s a video of the squid’s skin pulsing along to Insane in the Membrane by Cypress Hill:

During experiments on the giant axons of the Longfin Inshore Squid (loligo pealei) at the Marine Biological Laboratory in Woods Hole, MA; we were fascinated by the fast color-changing nature of the squid’s skin. Squids (like many other cephalopods) can quickly control pigmented cells called chromatophores to reflect light. The Longfin Inshore has 3 different chromatophore colors: Brown, Red, and Yellow. Each chromatophore has tiny muscles along the circumference of the cell that can contract to reveal the pigment underneath.

(via colossal)


Feynman diagram sculptures by Edward Tufte

Opening on September 15 at Edward Tufte’s gallery in Chelsea is All Possible Photons, an exhibit of sculptures by Tufte of Richard Feynman’s subatomic particle diagrams.

Feynman Tufte

Made from stainless steel and air, the artworks grow out of Richard Feynman’s famous diagrams describing Nature’s subatomic behavior. Feynman diagrams depict the space-time patterns of particles and waves of quantum electrodynamics. These mathematically derived and empirically verified visualizations represent the space-time paths taken by all subatomic particles in the universe.

The resulting conceptual and cognitive art is both beautiful and true. Along with their art, the stainless steel elements of All Possible Photons actually represent something: the precise activities of Nature at her highest resolution.


Magical heart rate monitor iPhone app

Using just the camera on your iPhone, the Cardiio app can accurately measure your heart rate. Here’s how it works:

Every time your heart beats, more blood is pumped into your face. This slight increase in blood volume causes more light to be absorbed, and hence less light is reflected from your face. Using sophisticated software, your iPhone’s front camera can track these tiny changes in reflected light that are not visible to the human eye and calculate your heart beat!

This video shows this process in action (with a short explanatory intro of the mathematical technique):

That is flat-out amazing. (via @delfuego)


Photo of a massive Arctic cyclone

Where have I seen this before, a massive long-lasting Arctic storm that looks a lot like a hurricane? Oh right, The Day After Tomorrow.

Arctic Storm

The storm had an unusually low central pressure area. Paul A. Newman, chief scientist for Atmospheric Sciences at NASA’s Goddard Space Flight Center in Greenbelt, Md., estimates that there have only been about eight storms of similar strength during the month of August in the last 34 years of satellite records. “It’s an uncommon event, especially because it’s occurring in the summer. Polar lows are more usual in the winter,” Newman said.

Arctic storms such as this one can have a large impact on the sea ice, causing it to melt rapidly through many mechanisms, such as tearing off large swaths of ice and pushing them to warmer sites, churning the ice and making it slushier, or lifting warmer waters from the depths of the Arctic Ocean.

I love The Day After Tomorrow. I know it’s a cheeseball disaster movie (which is pretty much why I love it) but it’s also looking more than a little prescient. Well, as prescient as a cheeseball disaster movie can be anyway. In the Washington Post the other day, prominent climatologist James Hansen wrote that human-driven climate change is responsible for an increase in extreme weather.

My projections about increasing global temperature have been proved true. But I failed to fully explore how quickly that average rise would drive an increase in extreme weather.

In a new analysis of the past six decades of global temperatures, which will be published Monday, my colleagues and I have revealed a stunning increase in the frequency of extremely hot summers, with deeply troubling ramifications for not only our future but also for our present.

This is not a climate model or a prediction but actual observations of weather events and temperatures that have happened. Our analysis shows that it is no longer enough to say that global warming will increase the likelihood of extreme weather and to repeat the caveat that no individual weather event can be directly linked to climate change. To the contrary, our analysis shows that, for the extreme hot weather of the recent past, there is virtually no explanation other than climate change.

In many ways, the phrase “global warming” is grossly misleading. “Oh,” we think, “it’s gonna be a couple degrees warmer in NYC in 20 years than it is now.” But the Earth’s climate is a chaotic non-linear system, which means that a sudden shift of a degree or two — and when you’re talking about something as big as the Earth, a degree over several decades is sudden — pushes things out of balance here and there in unpredictable ways. So it’s not just that it’s getting hotter, it’s that you’ve got droughts in places where you didn’t have them before, severe floods in other places, unusually hot summers, and even places that are cooler than normal, all of which disrupts the animal and plant life that won’t be able to acclimate to the new reality fast enough.

But pretty Arctic cyclone though, right?


Why does Mars Curiosity have such a small camera?

The main imaging cameras on the Mars Curiosity rover have only 2-megapixel sensors with 8 GB of flash memory — compare that to a maxed-out iPhone 4S with an 8-megapixel sensor and 64 GB of flash memory (not to mention 30-fps 1080p video). Planning timeframes and communications bandwidth contributed to the chosen camera size.

‘There’s a popular belief that projects like this are going to be very advanced but there are things that mitigate against that. These designs were proposed in 2004, and you don’t get to propose one specification and then go off and develop something else. 2MP with 8GB of flash [memory] didn’t sound too bad in 2004. But it doesn’t compare well to what you get in an iPhone today.’

The cameras were also supposed to be outfitted with zoom lenses but that part of the project was scrapped.


The physics of cats always landing on their feet

In this slow-motion video, you can see how cats rotate themselves in the air while conserving angular momentum.

This is an interesting companion to yesterday’s owl rotation video. (via @stevenstrogatz)


The Mars Olympics

On Twitter right now, Neil deGrasse Tyson is imagining how various Olympic events would work on Mars.

Women’s Beach Volleyball on Mars: No protective ozone layer there. Solar UV would irradiate all exposed legs, buns, & tummies

Gymnastics: On Mars, with only 38% of Earth’s gravity, the Vault & other spring-assisted leaps would resemble circus cannons.

(via @jaycer17)


Landing on Mars next week: the Curiosity rover

The rest of you can have your Olympics, but the early August event I’m most looking forward to is the arrival on Mars of the Curiosity rover. But NASA has had some problems in the past delivering payloads to Mars, so this is going to be somewhat of a nail-biter. If you haven’t seen it, Curiosity’s Seven Minutes of Terror is well worth watching to see the logistical challenge of getting the rover down to the surface.

Curiosity will hopefully land on the surface on Aug 6 at about 1:30 am ET.