I’m not a huge fan of the current US Supreme Court, but they recently did something right: Bloomberg is reporting the Court denied the revival of a lawsuit against mobile phone companies from a group claiming cell phones cause brain damage, including cancer.

The Court denied the claim for legal reasons — basically, the suit was filed under state law claims, but a court had already ruled that those laws were superseded by federal (FCC) regulations. So the Court ruled the claimant doesn’t get to sue mobile phone companies.

And while you might consider this ruling decided on a technicality, it turned out the right way. Mobile phones don’t cause cancer. Or, if you want to be technically accurate, studies of this topic have shown that any link between cell phones and brain damage is so weak it’s statistically indistinguishable from no link at all.

The exception would be if you’re using your phone while you’re driving. Then the likelihood of brain damage — and spleen damage, and kidney damage, and bone damage, and life damage — jump by a factor of four.

So you can use your phone and not worry about brain damage… as long as you use it intelligently.

This is where we are now: at Duke University, a monkey controls a virtual arm using only its thoughts. Miguel Nicolelis had fitted the animal with a headset of electrodes that translates its brain activity into movements. It can grab virtual objects without using its arms. It can also feel the objects without its hands, because the headset stimulates its brain to create the sense of different textures. Monkey think, monkey do, monkey feel – all without moving a muscle.
And this is where  Nicolelis wants to be in three years: a young quadriplegic Brazilian man strolls confidently into a massive stadium. He controls his four prosthetic limbs with his thoughts, and they in turn send tactile information straight to his brain. The technology melds so fluidly with his mind that he confidently runs up and delivers the opening kick of the 2014 World Cup.

This sounds like a far-fetched dream, but Nicolelis – a big soccer fan – is talking to the Brazilian government to make it a reality. He has created an international consortium called the Walk Again Project, consisting of non-profit research institutions in the United States, Brazil, Germany and Switzerland. Their goal is to create a “high performance brain-controlled prosthetic device that enables patients to finally leave the wheelchair behind.”

But for the moment, it’s still all about monkeys. Nicolelis has spent the last few years developing ever better “brain-machine interfaces” – devices that allow individuals to directly control a machine using their brains. In 2003, he showed that monkeys could steer a virtual arm using electrodes in their brains. Since then, other groups have shown that monkeys can use similar devices to feed themselves with robotic arms.

These machines all lacked something important – a sense of touch. “In the absence of feedback from the arm, the most mundane activities of daily living are slow and clumsy, and require herculean concentration and effort,” says Sliman Bensmaia, who works in the same area. Without touch, the prosthetic is just a glorified hook. Some devices can provide crude sensations (think about the rumble packs on video game controllers), but they really have to hook up to the brain itself to provide realistic feedback.

Two members of Nicolelis’ team, Joseph O’Doherty and Mikhail Lebedev, have started to solve this problem. They have developed a “brain-machine-brain interface” or BMBI, which sends signals to the brain as well as receiving them. Electrodes connect to a monkey’s motor cortex, the part of its brain that controls movements. They read the activity of the local neurons to decipher the monkey’s commands. The electrodes also stimulate the neighbouring somatosensory cortex, which governs the sense of touch. The brain talks to the machine, but the machine also talks to the brain.

Developing the BMBI was not easy. The biggest problem is that the incoming sensory signals interfere with the outgoing motor ones, like two people shouting at one another. “Nobody had been able to record and stimulate at the same time,” says Nicolelis. His solution was to exploit lulls in the conversation, by timing the incoming signals so they arrived between the spikes of the outgoing ones. “There’s a small window of time when you only block a very small portion of the signals from the brain,” says Nicolelis. “It worked as if there was no interference.”

O’Doherty and Lebedev fitted the BMBIs to two monkeys, whose names – M and N – bear the ring of British intelligence services. Both animals soon learned to explore three objects with a virtual arm, just by thinking about it. At first, the monkeys learned to control the arm with a joystick. M managed it within four training sessions, N took nine to master the technique, and both became better over time. But both eventually learned to steer the arm without their hands.

Meanwhile, the electrodes fed their brains with signals that made the objects feel different. The monkeys used this textured information to pick the one that would earn them a tasty reward. This bit was easier than you might imagine. The somatosensory cortex doesn’t assign neurons to specific textures. Instead, it computes what we feel by analysing patterns of stimulation across large fields of neurons. “There are no specific nerves,” says Nicolelis. “You just give the signals to a general area of neurons and the brain figures it out.”

In this case, O’Doherty and Lebedev weren’t trying to create any specific textures; they just wanted to simulate different ones. For a working prosthetic, Bensmaia thinks that they will need “more sophisticated algorithms for sensory feedback”. He says, “The trick is to give the brain information that it can use in an intuitive way.” Ideally, that information would closely match the sensations evoked by an actual limb. “Otherwise, patients will receive a barrage of signals from the arm which may serve to confuse rather than assist them.”

Having successfully tested the BMBIs with a virtual arm, the next step is surely to test it with a physical one, before moving on to human trials. The potential applications are vast. Amputees and paralysed people could gain full and intuitive control of artificial limbs. Everyone could control technology with a thought. As O’Doherty and Lebedev write, “We propose that BMBIs can effectively liberate a brain from the physical constraints of the body.” But for the moment, the team have their World Cup target firmly in mind. “I think it is plausible,” says Bensmaia. “Of course, a lot of things would have to fall in place for that to happen.”

Reference: O’Doherty, Lebedev, Ifft, Zhuang, Shokur, Bleuler & Nicolelis. 2011. Active tactile exploration using a brain–machine–brain interface. Nature http://dx.doi.org/10.1038/nature10489

Image: It’s by Katie Zhuang from Nicolelis’s lab. Isn’t it great? TRON monkey!

More on prosthetics and related tech:

• Monkey see, monkey control prosthetic arm with thoughts
• Hair-thin ‘electronic skin’ monitors hearts and brains, controls video games
• Sniff-detector allows paralysed people to write messages, surf the net and drive a wheelchair
• Retinal implant partially restores sight in blind people
• The Beeblebrox Illusion: scientists convince people they have three arms

To celebrate my birthday today, I’m heading back into Second Life to do a chat with Alan Boyle of MSNBC.com fame. Alan has previewed some of the topics we’ll be discussing in a post at Cosmic Log. It’s possible the Nobel Prize will be mentioned. (The physics one. Don’t expect any insight from me on quasicrystals, except that they’re awesome.)

We’ll be chatting at 9pm Eastern/6pm Pacific, at the Stella Nova Theater. If you’re not already on Second Life, it’s super easy (and free) to join. (Here’s some very useful information for beginners.) And you get to design an avatar that looks like you would want to look, rather than your inevitably-disappointing real self.

The chat is part of the Virtually Speaking series hosted by FireDogLake, in this case co-produced with the Meta Institute for Computational Astrophysics. Alan does a regular series of interviews on science, so you may get hooked. Our chat will be a multi-media extravaganza, so you can choose to listen in various ways:

• Directly in Second Life.
• Audio on BlogTalk Radio. This is an archived podcast, available on iTunes, so you can listen later if you like.
• There is also live chat on IRC. Enter #vspeak into the channel field.

Yes I know, very complicated. If simplicity is more your bag, here’s a guest video on dark energy that I did for the wonderful Minute Physics series.

There are many things you don’t want gathering in large numbers, including locusts, rioters, and brain proteins. Our nerve cells contain many proteins that typically live in solitude, but occasionally gather in their thousands to form large insoluble clumps. These clumps can be disastrous. They can wreck neurons, preventing them from firing normally and eventually killing them.

Such clumps are the hallmarks of many brain diseases. The neurons of Alzheimer’s patients are riddled with tangles of a protein called tau. Those of Parkinson’s patients contain bundles, or fibrils, of another protein called alpha-synuclein. The fibrils gather into even larger clumps called Lewy bodies.

Now, Laura Volpicelli-Daley from the University of Pennsylvania School of Medicine has confirmed that the alpha-synuclein fibrils can spread. Once they’ve entered a new neuron, they can corrupt the local proteins, changing their shape and gathering them into fresh Lewy bodies. They’re like gangs that travel from town to town, inciting the locals into forming their own angry mobs.

This makes alpha-synuclein a bit like prions, the proteins that cause mad cow disease, scrapie and Creutzfeld-Jacob disease (CJD). Prions are also misshapen proteins that can convert the shape of their normal peers. But there is a crucial distinction. Prions are infectious – they don’t just spread from cell to cell, but from individual to individual. Alpha-synuclein can’t do that. “There is no evidence that Parkinson’s disease or other [diseases related to synuclein] can spread from person to person or from animal to person,” says Virginia Lee, who led the study.

Parkinson’s may be confined to a single brain, but it can spread from one part to another. Thanks to studies like these, we know more about how this happens. “This is an outstanding study,” says Patrik Brundin, who works on Parkinson’s disease at Lund University. “It adds to the string of evidence that prion-like mechanisms play an important role in the development of Parkinson’s disease.”

Others studies have suggested that alpha-synuclein fibrils can seed new clumps of diseases proteins in healthy cells. In 2008, two teams showed that normal fetal neurons develop Lewy bodies if they’re transplanted into the brains of a Parkinson’s patient. A year later, other groups showed that if you can shunt alpha-synuclein fibrils into new cells, they create more fibrils.

But all of these studies either forced the fibrils in, used massive concentrations of them, or exposed neurons to the fibrils amid a cocktail of other chemicals. Volpicelli-Daley wanted to see if the fibrils can spread their corruption under natural conditions that better mimic the brains of Parkinson’s patients.

They could. Neurons will happily absorb alpha-synuclein fibrils at normal concentrations. Once inside, they start gathering the local synuclein proteins into fibrils along the stem of the neuron. After a few days, the fibrils move into the heart of the cell, where they create Lewy bodies (note the spread of the green dye in the image above). The cell fails, and eventually dies. “We never expect that it worked so well,” says Lee.

“I like the paper very much,” says Eliezer Masliah, who studies rogue proteins in Alzheimer’s disease. However, he points out that alpha-synuclein fibrils aren’t normally found in the space between cells, so it’s not clear if neurons would have any fibrils to absorb in real life. “There is a question of physiological relevance,” he says, “but it’s possible that very small fragments of fibrils might be released from dying neurons.”

It’s valuable to get clues about how synuclein fibrils spread, but Vopicelli-Daley has done something far more important – she has developed an easy system for studying that spread in the lab. Her experimental set-up is easy to run at a large scale. She’s now in a good position to look at why neurons absorb the fibrils (no one knows), how the Lewy bodies form, how they kill neurons, and how different Parkinson’s genes influence these events. She can also scan large libraries of chemicals to search for drugs that can stop the spread of synuclein.

More broadly, Vopicelli-Daley’s study supports the idea that the spread of rogue proteins is a unifying feature of many brain diseases. Clusters of misfolded Tau and amyloid beta – proteins involved in Alzheimer’s – can instigate fresh clusters in new cells. And as I’ve written about before, a twisted version of SOD1, which causes Lou Gehrig’s disease, can travel from cell to cell and nudge normal proteins into adopting its malformed shape. All these varied diseases could be caused by molecular evangelism gone wrong.

Reference: Volpcelli-Daley, Luk, Patel, Tanik, Riddle, Stieber, Meaney, Trojanowski & Lee. 2011.  Exogenous a-Synuclein Fibrils Induce Lewy Body Pathology Leading to Synaptic Dysfunction and Neuron Death. Neuron http://dx.doi.org/10.1016/j.neuron.2011.08.033

More on neural diseases:

• Fishing expedition reveals unexpected link between Alzheimer’s and prion diseases
• Neurons ravaged by infectious mutant sod
• Evolution without genes – prions can evolve and adapt too

Finally! After teasers released in March whetted our appetites, this maker’s dream is now airing: This week National Geographic’s DIY show “How Hard Can It Be?”, the team satisfies your hunger to see Carl Fredricksen’s balloon-propelled house in the flesh—using around 300 technicolor weather balloons and a lightweight cottage that the team was still stapling together just hours before it rose into the sky, to bob along at 10,000 feet. You can’t not root for this spunky bunch (even though this first video ends in a cliffhanger):

Luckily, with a bit of searching on the NatGeo site, you can find the clincher:

When they launched the balloon a few months ago, Wired did some back-of-the-envelope calculations on the physics involved here. Though Wired didn’t address this, we suspect that one reason they couldn’t use party balloons is that the pressure from balloons on the outside of the cluster pushing in on the ones in the center would cause them to burst. What do you think?

Booze inhibits more than just your judgement: it impairs your immune system’s ability to fight off pathogens, according to a study published last week in the journal BMC Immunology. Researchers exposed human monocytes, a type of white blood cell vital for a functioning immune system, to an amount of alcohol equivalent to a blood alcohol concentration of 0.1 (around the legal level in most states). Compared to booze-free cells, monocytes exposed to both short- and long-term levels of alcohol produced significantly less type 1 interferons, chemicals the help recruit immune cells to stage an antiviral response (and also have anti-tumor activity). Excessive drinking has long been thought to interfere with the body’s ability to fight disease, and boozing is an important risk factor for hepatitis C and barrier to treatment in HIV. But not much had been known about the mechanisms behind the effect.

But the findings of the study weren’t all so cut and dry. For instance, cells bathed in alcohol for only a few hours showed a notable decrease in the production of tumor necrosis factor-alpha, an chemical that’s helpful in fighting pathogens but is also associated with inflammatory-related chronic conditions like rheumatoid arthritis and inflammatory bowel syndrome. Monocytes exposed to near constant levels of alcohol for a week, however, showed the opposite: a significant increase in TNF-a. More research will be required to pin down the health-related effects of these chemical fluctuations.

Reference: Maoyin Pang, Shashi Bala, Karen Kodys, Donna Catalano and Gyongyi Szabo. Inhibition of TLR8- and TLR4-induced Type I IFN induction by alcohol is different from its effects on inflammatory cytokine production in monocytes. BMC Immunology, 2011. DOI: 10.1186/1471-2172-12-55

Image: Kirti Poddar / Flickr 

Does Zach Weiner know me or what?

Click to see the whole comic.

I would’ve gotten away with it too, if it weren’t for those meddling auditors!

The other day I posted a great picture of Saturn and its rings taken by Cassini. While digging around in my archives looking for other posts about the rings, I found one from earlier this year that had a picture of the icy moon Enceladus with the rings in the background. When I saw the picture, I got a jolt: there was a crater chain on the surface that looks just like the one on the asteroid Vesta!

Here’s a side-by-side comparison:

Enceladus is on the left, Vesta on the right (click those links for higher-res shots). Pretty cool, huh? You can see both have two big overlapping craters of roughly the same size, and a smaller third one roughly aligned on top. The set on Vesta is nicknamed — for obvious reasons — "Snowman".

Craters like this form when the impacting object is not a single body; for example, many asteroids are known to be binaries, with both objects about the same size. Getting hit by that would leave two craters either very close together or overlapping, depending on the sizes, distances, and velocities of the impacting bodies.

Sometimes, too, there are long chains of many craters, sometimes dozens. We see those on the Moon and Mercury, for example, and they may be from comets that have disintegrated into many pieces before they hit, like the comet Shoemaker-Levy 9 did before it whacked Jupiter over and over again in 1994.

The impacts on Vesta and Enceladus look remarkably similar. But I wonder. The two big craters on Vesta both have lots of shared characteristics: size, sharp rims, and so on. They’re the two biggest craters on Vesta, so it would be very unlikely to get them so close together unless they were from the same event. But the third crater has a softer rim (implying greater age due to erosive forces like the solar wind and smaller impacts over eons), is smaller, and doesn’t quite line up with the other two. There are also several craters that size on the surface. It’s possible it’s unrelated to the other two, and coincidentally nearby.

Enceladus, though, looks like all three are related. Even though one is smaller, it lines up pretty well with the other two and has similar features. Maybe this really was a triple-system that hit. The asteroid Kleopatra, for example, has two moons (though I must note Kleopatra is big, which helps it hold on to two moons; an impact from something like that would come close to shattering a moon like Enceldaus).

I have no real scientific conclusion to draw here, except that multiple-body asteroids and comets are certainly more common than we might have thought 20 years ago. It’s amazing that the evidence for their existence was literally carved into the surfaces of other big bodies out there. With all of this new and marvelous imagery we’re getting from our robots plying the solar system, I wonder what other things we’ll learn as we build up this huge database of pictures?

Every month or so I sit down (virtually) with my buddy Seth Shostak, and we record a short interview for Skeptic Check, part of the Big Picture Science podcast/radio show. Seth’s on the road right now, so they’ve put a "Beast of Skeptic Check" online, featuring some of Seth’s favorite segments. You can also just hear the part I’m in (talking Moon Hoax) on the Big Picture Science blog.

In honor of the Nobel Prize, here are some questions that are frequently asked about dark energy, or should be.

What is dark energy?

It’s what makes the universe accelerate, if indeed there is a “thing” that does that. (See below.)

So I guess I should be asking… what does it mean to say the universe is “accelerating”?

First, the universe is expanding: as shown by Hubble, distant galaxies are moving away from us with velocities that are roughly proportional to their distance. “Acceleration” means that if you measure the velocity of one such galaxy, and come back a billion years later and measure it again, the recession velocity will be larger. Galaxies are moving away from us at an accelerating rate.

But that’s so down-to-Earth and concrete. Isn’t there a more abstract and scientific-sounding way of putting it?

The relative distance between far-flung galaxies can be summed up in a single quantity called the “scale factor,” often written a(t) or R(t). The scale factor is basically the “size” of the universe, although it’s not really the size because the universe might be infinitely big — more accurately, it’s the relative size of space from moment to moment. The expansion of the universe is the fact that the scale factor is increasing with time. The acceleration of the universe is the fact that it’s increasing at an increasing rate — the second derivative is positive, in calculus-speak.

Does that mean the Hubble constant, which measures the expansion rate, is increasing?

No. The Hubble “constant” (or Hubble “parameter,” if you want to acknowledge that it changes with time) characterizes the expansion rate, but it’s not simply the derivative of the scale factor: it’s the derivative divided by the scale factor itself. Why? Because then it’s a physically measurable quantity, not something we can change by switching conventions. The Hubble constant is basically the answer to the question “how quickly does the scale factor of the universe expand by some multiplicative factor?”

If the universe is decelerating, the Hubble constant is decreasing. If the Hubble constant is increasing, the universe is accelerating. But there’s an intermediate regime in which the universe is accelerating but the Hubble constant is decreasing — and that’s exactly where we think we are. The velocity of individual galaxies is increasing, but it takes longer and longer for the universe to double in size.

Said yet another way: Hubble’s Law relates the velocity v of a galaxy to its distance d via v = H d. The velocity can increase even if the Hubble parameter is decreasing, as long as it’s decreasing more slowly than the distance is increasing.

Did the astronomers really wait a billion years and measure the velocity of galaxies again?

No. You measure the velocity of galaxies that are very far away. Because light travels at a fixed speed (one light year per year), you are looking into the past. Reconstructing the history of how the velocities were different in the past reveals that the universe is accelerating.

How do you measure the distance to galaxies so far away?

It’s not easy. The most robust method is to use a “standard candle” — some object that is bright enough to see from great distance, and whose intrinsic brightness is known ahead of time. Then you can figure out the distance simply by measuring how bright it actually looks: dimmer = further away.

Sadly, there are no standard candles.

Then what did they do?

Fortunately we have the next best thing: standardizable candles. A specific type of supernova, Type Ia, are very bright and approximately-but-not-quite the same brightness. Happily, in the 1990′s Mark Phillips discovered a remarkable relationship between intrinsic brightness and the length of time it takes for a supernova to decline after reaching peak brightness. Therefore, if we measure the brightness as it declines over time, we can correct for this difference, constructing a universal measure of brightness that can be used to determine distances.

Why are Type Ia supernovae standardizable candles?

We’re not completely sure — mostly it’s an empirical relationship. But we have a good idea: we think that SNIa are white dwarf stars that have been accreting matter from outside until they hit the Chandrasekhar Limit and explode. Since that limit is basically the same number everywhere in the universe, it’s not completely surprising that the supernovae have similar brightnesses. The deviations are presumably due to differences in composition.

But how do you know when a supernova is going to happen?

You don’t. They are rare, maybe once per century in a typical galaxy. So what you do is look at many, many galaxies with wide-field cameras. In particular you compare an image of the sky taken at one moment to another taken a few weeks later — “a few weeks” being roughly the time between new Moons (when the sky is darkest), and coincidentally about the time it takes a supernova to flare up in brightness. Then you use computers to compare the images and look for new bright spots. Then you go back and examine those bright spots closely to try to check whether they are indeed Type Ia supernovae. Obviously this is very hard and wouldn’t even be conceivable if it weren’t for a number of relatively recent technological advances — CCD cameras as well as giant telescopes. These days we can go out and be confident that we’ll harvest supernovae by the dozens — but when Perlmutter and his group started out, that was very far from obvious.

And what did they find when they did this?

Most (almost all) astronomers expected them to find that the universe was decelerating — galaxies pull on each other with their gravitational fields, which should slow the whole thing down. (Actually many astronomers just thought they would fail completely, but that’s another story.) But what they actually found was that the distant supernovae were dimmer than expected — a sign that they are farther away than we predicted, which means the universe has been accelerating.

Why did cosmologists accept this result so quickly?

Even before the 1998 announcements, it was clear that something funny was going on with the universe. There seemed to be evidence that the age of the universe was younger than the age of its oldest stars. There wasn’t as much total matter as theorists predicted. And there was less structure on large scales than people expected. The discovery of dark energy solved all of these problems at once. It made everything snap into place. So people were still rightfully cautious, but once this one startling observation was made, the universe suddenly made a lot more sense.

How do we know the supernovae not dimmer because something is obscuring them, or just because things were different in the far past?

That’s the right question to ask, and one reason the two supernova teams worked so hard on their analysis. You can never be 100% sure, but you can gain more and more confidence. For example, astronomers have long known that obscuring material tends to scatter blue light more easily than red, leading to “reddening” of stars that sit behind clouds of gas and dust. You can look for reddening, and in the case of these supernovae it doesn’t appear to be important. More crucially, by now we have a lot of independent lines of evidence that reach the same conclusion, so it looks like the original supernova results were solid.

There’s really independent evidence for dark energy?

Oh yes. One simple argument is “subtraction”: the cosmic microwave background measures the total amount of energy (including matter) in the universe. Local measures of galaxies and clusters measure the total amount of matter. The latter turns out to be about 27% of the former, leaving 73% or so in the form of some invisible stuff that is not matter: “dark energy.” That’s the right amount to explain the acceleration of the universe. Other lines of evidence come from baryon acoustic oscillations (ripples in large-scale structure whose size helps measure the expansion history of the universe) and the evolution of structure as the universe expands.

Okay, so: what is dark energy?

Glad you asked! Dark energy has three crucial properties. First, it’s dark: we don’t see it, and as far as we can observe it doesn’t interact with matter at all. (Maybe it does, but beneath our ability to currently detect.) Second, it’s smoothly distributed: it doesn’t fall into galaxies and clusters, or we would have found it by studying the dynamics of those objects. Third, it’s persistent: the density of dark energy (amount of energy per cubic light-year) remains approximately constant as the universe expands. It doesn’t dilute away like matter does.

These last two properties (smooth and persistent) are why we call it “energy” rather than “matter.” Dark energy doesn’t seem to act like particles, which have local dynamics and dilute away as the universe expands. Dark energy is something else.

That’s a nice general story. What might dark energy specifically be?

The leading candidate is the simplest one: “vacuum energy,” or the “cosmological constant.” Since we know that dark energy is pretty smooth and fairly persistent, the first guess is that it’s perfectly smooth and exactly persistent. That’s vacuum energy: a fixed amount of energy attached to every tiny region of space, unchanging from place to place or time to time. About one hundred-millionth of an erg per cubic centimeter, if you want to know the numbers.

Is vacuum energy really the same as the cosmological constant?

Yes. Don’t believe claims to the contrary. When Einstein first invented the idea, he didn’t think of it as “energy,” he thought of it as a modification of the way spacetime curvature interacted with energy. But it turns out to be precisely the same thing. (If someone doesn’t want to believe this, ask them how they would observationally distinguish the two.)

Doesn’t vacuum energy come from quantum fluctuations?

Not exactly. There are many different things that can contribute to the energy of empty space, and some of them are completely classical (nothing to do with quantum fluctuations). But in addition to whatever classical contribution the vacuum energy has, there are also quantum fluctuations on top of that. These fluctuation are very large, and that leads to the cosmological constant problem.

What is the cosmological constant problem?

If all we knew was classical mechanics, the cosmological constant would just be a number — there’s no reason for it to be big or small, positive or negative. We would just measure it and be done.

But the world isn’t classical, it’s quantum. In quantum field theory we expect that classical quantities receive “quantum corrections.” In the case of the vacuum energy, these corrections come in the form of the energy of virtual particles fluctuating in the vacuum of empty space.

We can add up the amount of energy we expect in these vacuum fluctuations, and the answer is: an infinite amount. That’s obviously wrong, but we suspect that we’re overcounting. In particular, that rough calculation includes fluctuations at all sizes, including wavelengths smaller than the Planck distance at which spacetime probably loses its conceptual validity. If instead we only include wavelengths that are at the Planck length or longer, we get a specific estimate for the value of the cosmological constant.

The answer is: 10¹²⁰ times what we actually observe. That discrepancy is the cosmological constant problem.

Why is the cosmological constant so small?

Nobody knows. Before the supernovae came along, many physicists assumed there was some secret symmetry or dynamical mechanism that set the cosmological constant to precisely zero, since we certainly knew it was much smaller than our estimates would indicate. Now we are faced with both explaining why it’s small, and why it’s not quite zero. And for good measure: the coincidence problem, which is why the dark energy density is the same order of magnitude as the matter density.

Here’s how bad things are: right now, the best theoretical explanation for the value of the cosmological constant is the anthropic principle. If we live in a multiverse, where different regions have very different values of the vacuum energy, one can plausibly argue that life can only exist (to make observations and win Nobel Prizes) in regions where the vacuum energy is much smaller than the estimate. If it were larger and positive, galaxies (and even atoms) would be ripped apart; if it were larger and negative, the universe would quickly recollapse. Indeed, we can roughly estimate what typical observers should measure in such a situation; the answer is pretty close to the observed value. Steven Weinberg actually made this prediction in 1988, long before the acceleration of the universe was discovered. He didn’t push it too hard, though; more like “if this is how things work out, this is what we should expect to see…” There are many problems with this calculation, especially when you start talking about “typical observers,” even if you’re willing to believe there might be a multiverse. (I’m very happy to contemplate the multiverse, but much more skeptical that we can currently make a reasonable prediction for observable quantities within that framework.)

What we would really like is a simple formula that predicts the cosmological constant once and for all as a function of other measured constants of nature. We don’t have that yet, but we’re trying. Proposed scenarios make use of quantum gravity, extra dimensions, wormholes, supersymmetry, nonlocality, and other interesting but speculative ideas. Nothing has really caught on as yet.

Has the course of progress in string theory ever been affected by an experimental result?

Yes: the acceleration of the universe. Previously, string theorists (like everyone else) assumed that the right thing to do was to explain a universe with zero vacuum energy. Once there was a real chance that the vacuum energy is not zero, they asked whether that was easy to accommodate within string theory. The answer is: it’s not that hard. The problem is that if you can find one solution, you can find an absurdly large number of solutions. That’s the string theory landscape, which seems to kill the hopes for one unique solution that would explain the real world. That would have been nice, but science has to take what nature has to offer.

What’s the coincidence problem?

Matter dilutes away as the universe expands, while the dark energy density remains more or less constant. Therefore, the relative density of dark energy and matter changes considerably over time. In the past, there was a lot more matter (and radiation); in the future, dark energy will completely dominate. But today, they are approximately equal, by cosmological standards. (When two numbers could differ by a factor of 10¹⁰⁰ or much more, a factor of three or so counts as “equal.”) Why are we so lucky to be born at a time when dark energy is large enough to be discoverable, but small enough that it’s a Nobel-worthy effort to do so? Either this is just a coincidence (which might be true), or there is something special about the epoch in which we live. That’s one of the reasons people are willing to take anthropic arguments seriously. We’re talking about a preposterous universe here.

If the dark energy has a constant density, but space expands, doesn’t that mean energy isn’t conserved?

Yes. That’s fine.

What’s the difference between “dark energy” and “vacuum energy”?

“Dark energy” is the general phenomenon of smooth, persistent stuff that makes the universe accelerate; “vacuum energy” is a specific candidate for dark energy, namely one that is absolutely smooth and utterly constant.

So there are other candidates for dark energy?

Yes. All you need is something that is pretty darn smooth and persistent. It turns out that most things like to dilute away, so finding persistent energy sources isn’t that easy. The simplest and best idea is quintessence, which is just a scalar field that fills the universe and changes very slowly as time passes.

Is the quintessence idea very natural?

Not really. An original hope was that, by considering something dynamical and changing rather than a plain fixed constant energy, you could come up with some clever explanation for why the dark energy was so small, and maybe even explain the coincidence problem. Neither of those hopes has really panned out.

Instead, you’ve added new problems. According to quantum field theory, scalar fields like to be heavy; but to be quintessence, a scalar field would have to be enormously light, maybe 10^-30 times the mass of the lightest neutrino. (But not zero!) That’s one new problem you’ve introduced, and another is that a light scalar field should interact with ordinary matter. Even if that interaction is pretty feeble, it should still be large enough to detect — and it hasn’t been detected. Of course, that’s an opportunity as well as a problem — maybe better experiments will actually find a “quintessence force,” and we’ll understand dark energy once and for all.

How else can we test the quintessence idea?

The most direct way is to do the supernova thing again, but do it better. More generally: map the expansion of the universe so precisely that we can tell whether the density of dark energy is changing with time. This is generally cast as an attempt to measure the dark energy equation-of-state parameter w. If w is exactly minus one, the dark energy is exactly constant — vacuum energy. If w is slightly greater than -1, the energy density is gradually declining; if it’s slightly less (e.g. -1.1), the dark energy density is actually growing with time. That’s dangerous for all sorts of theoretical reasons, but we should keep our eyes peeled.

What is w?

It’s called the “equation-of-state parameter” because it relates the pressure p of dark energy to its energy density ρ, via w = p/ρ. Of course nobody measures the pressure of dark energy, so it’s a slightly silly definition, but it’s an accident of history. What really matters is how the dark energy evolves with time, but in general relativity that’s directly related to the equation-of-state parameter.

Does that mean that dark energy has negative pressure?

Yes indeed. Negative pressure is what happens when a substance pulls rather than pushes — like an over-extended spring that pulls on either end. It’s often called “tension.” This is why I advocated smooth tension as a better name than “dark energy,” but I came in too late.

Why does dark energy make the universe accelerate?

Because it’s persistent. Einstein says that energy causes spacetime to curve. In the case of the universe, that curvature comes in two forms: the curvature of space itself (as opposed to spacetime), and the expansion of the universe. We’ve measured the curvature of space, and it’s essentially zero. So the persistent energy leads to a persistent expansion rate. In particular, the Hubble parameter is close to constant, and if you remember Hubble’s Law from way up top (v = H d) you’ll realize that if H is approximately constant, v will be increasing because the distance is increasing. Thus: acceleration.

Is negative pressure is like tension, why doesn’t it pull things together rather than pushing them apart?

Sometimes you will hear something along the lines of “dark energy makes the universe accelerate because it has negative pressure.” This is strictly speaking true, but a bit ass-backwards; it gives the illusion of understanding rather than actual understanding. You are told “the force of gravity depends on the density plus three times the pressure, so if the pressure is equal and opposite to the density, gravity is repulsive.” Seems sensible, except that nobody will explain to you why gravity depends on the density plus three times the pressure. And it’s not really the “force of gravity” that depends on that; it’s the local expansion of space.

The “why doesn’t tension pull things together?” question is a perfectly valid one. The answer is: because dark energy doesn’t actually push or pull on anything. It doesn’t interact directly with ordinary matter, for one thing; for another, it’s equally distributed through space, so any pulling it did from one direction would be exactly balanced by an opposite pull from the other. It’s the indirect effect of dark energy, through gravity rather than through direct interaction, that makes the universe accelerate.

The real reason dark energy causes the universe to accelerate is because it’s persistent.

Is dark energy like antigravity?

No. Dark energy is not “antigravity,” it’s just gravity. Imagine a world with zero dark energy, except for two blobs full of dark energy. Those two blobs will not repel each other, they will attract. But inside those blobs, the dark energy will push space to expand. That’s just the miracle of non-Euclidean geometry.

Is it a new repulsive force?

No. It’s just a new (or at least different) kind of source for an old force — gravity. No new forces of nature are involved.

What’s the difference between dark energy and dark matter?

Completely different. Dark matter is some kind of particle, just one we haven’t discovered yet. We know it’s there because we’ve observed its gravitational influence in a variety of settings (galaxies, clusters, large-scale structure, microwave background radiation). It’s about 23% of the universe. But it’s basically good old-fashioned “matter,” just matter that we can’t directly detect (yet). It clusters under the influence of gravity, and dilutes away as the universe expands. Dark energy, meanwhile, doesn’t cluster, nor does it dilute away. It’s not made of particles, it’s some different kind of thing entirely.

Is it possible that there is no dark energy, just a modification of gravity on cosmological scales?

It’s possible, sure. There are at least two popular approaches to this idea: f(R) gravity , which Mark and I helped develop, and DGP gravity, by Dvali, Gabadadze, and Porati. The former is a directly phenomenological approach where you simply change the Einstein field equation by messing with the action in four dimensions, while the latter uses extra dimensions that only become visible at large distances. Both models face problems — not necessarily insurmountable, but serious — with new degrees of freedom and attendant instabilities.

Modified gravity is certainly worth taking seriously (but I would say that). Still, like quintessence, it raises more problems than it solves, at least at the moment. My personal likelihoods: cosmological constant = 0.9, dynamical dark energy = 0.09, modified gravity = 0.01. Feel free to disagree.

What does dark energy imply about the future of the universe?

That depends on what the dark energy is. If it’s a true cosmological constant that lasts forever, the universe will continue to expand, cool off, and empty out. Eventually there will be nothing left but essentially empty space.

The cosmological constant could be constant at the moment, but temporary; that is, there could be a future phase transition in which the vacuum energy decreases. Then the universe could conceivably recollapse.

If the dark energy is dynamical, any possibility is still open. If it’s dynamical and increasing (w less than -1 and staying that way), we could even get a Big Rip.

What’s next?

We would love to understand dark energy (or modified gravity) through better cosmological observations. That means measuring the equation-of-state parameter, as well as improving observations of gravity in galaxies and clusters to compare with different models. Fortunately, while the U.S. is gradually retreating from ambitious new science projects, the European Space Agency is moving forward with a satellite to measure dark energy. There are a number of ongoing ground-based efforts, of course, and the Large Synoptic Survey Telescope should do a great job once it goes online.

But the answer might be boring — the dark energy is just a simple cosmological constant. That’s just one number; what are you going to do about it? In that case we need better theories, obviously, but also input from less direct empirical sources — particle accelerators, fifth-force searches, tests of gravity, anything that would give some insight into how spacetime and quantum field theory fit together at a basic level.

The great thing about science is that the answers aren’t in the back of the book; we have to solve the problems ourselves. This is a big one.

I’m fascinated by some geological events, including landslides. They happen so rapidly it’s rare to get them on video, but a lucky couple in Cornwall, UK^*, were at the right place at just the right time, and caught this amazing footage of several thousand tons of rocks letting go off a cliff face:

Wow! At 12 seconds in, though you can’t see any rock movement, there is a crack in the cliff where debris is getting forced out, falling in a plume. The crack widens, and then WHOOSH!

This was pretty small as slides go (some are longer and move far more slowly). Some are huge, and if they fall into water can cause very, very large tsunamis; for a fun sleep full of nightmares, read up on the Lituya Bay landslide and megatsunami of 1958. Happily, this one in England was far too small to do that sort of thing.

Did you know we see evidence of landslides on Mars and the Moon as well? See the Related posts below, including a couple of shots of avalanches on Mars caught in the act!

And as for the Cornwall slide, I would love to see something like that in person some day… from a nice safe distance. Yowza.

^* By coincidence, I just happened to write about Cornwall a few days ago, but that scene was somewhat more bucolic.

I use Google Trends a lot, but I don’t necessarily know if it’s telling me anything useful. So I decided to see if it might correlate well with browser share data. I know that W3Schools has been tracking their own stats for years, so I took their data from September of 2008 to September of 2011, and plotted the browser share. Below it are some trends from Google. Notice the pattern for Firefox and Chrome in particular.

Some of the people behind the openSNP website have been in touch with me for a while. As I put my own genotype into the public domain I’m obviously pretty well disposed toward this sort of thing. You should check them out if you haven’t before, they just moved to a beefier server. Here’s what they say they’re about:

openSNP allows customers of direct-to-customer genetic tests to publish their test results, find others with similar genetic variations, learn more about their results, find the latest primary literature on their variations and help scientists to find new associations.

In this space I tend to focus on ancestry because you don’t need any phenotypic information. You can just look at the relationships of the genotypes. But in the future traits are going to be where the real gold is. This sort of thing is a good first step.

Since 2006 I’ve been participating in DonorsChoose (thanks to timely reminders from Janet Stemwedel whenever life got too busy for me to keep track of anything). So I finally set up a page where you can donate to various life science related projects, with a bias toward genetics. Of course you don’t have to donate to just the projects that I selected. And if DonorsChoose is not to your taste, but you have funds you’d like to allocate to charity, please see the GiveWell recommendations.

Also check out the Leaderboard for science blogs.

The Better Angels of Our Nature: Why Violence Has Declined is finally out. I can’t read it in the near future because of time constraint, but I’m heartened that a public intellectual of Steven Pinker’s stature is finally making people more aware of the fact that in some ways the world is better than it has ever been! This being Pinker the media has responded in force. Peter Singer has given it a thumbs up in The New York Times, as you’d expect. But John Gray has one of the more disgusting responses I’ve seen in The Prospect, Delusions of peace: Stephen Pinker argues that we are becoming less violent. Nonsense, says John Gray. The comments notice what I did: Gray’s attack on Pinker is rhetorical sophistry, making no pretense at engaging the data which Pinker reports. This is particularly interesting coming from me because in terms of political philosophy I share many sympathies with Gray. I worry a great deal that the progressive liberal Whig moment in human history is a transient, and that the medium term future may be less than cheery. Nor do I have much faith in a utopian “End of History.” But whatever my concerns about the present and future are, they need to engage what we know about reality. That is one reason I revel in data and analysis which go against my intuition and falsify my own preconceptions.

The data that Pinker reports on the decline of violence are real, and responding to it by citing a handful of horrible genocides and sneering elegantly are low tactics which degrade intellectual discourse. Pessimism can’t be based on sentiment alone, one has to draw upon facts and robust theory. If those of us who who are wary of an arrow of history have only bluster and rhetoric, then the prophets of progress have won the day.

1) Post from the past, One Nation Under Gods, and Mitt Romney, over before it began.

2) Weird search query of the week: “false jewish genetic studies racist.”he

3) Comment of the week:

Frank Sweet’s “Legal History of the Color Line” is a good read on this topic. One of Sweet’s arguments is that black leaders, particularly Northeastern leaders, had a seminal role in the creation of an artificial, fiat-defined African American ethnos.

I think Sweet stresses the centrality of black leaders too much. They were more in a reactive, rather than proactive position vis-a-vis white racial codes and attitudes. But, still, a worthwhile read and this is not his central point.

The one drop rule wasn’t enforced effectively because the Jim Crow system was not totalitarian, the funds for an effectively intrusive bureucracy weren’t there. I think people are finally discussing the many ways it was ignored in practice. I had relatives who were remembered as “white colored men” in newspapers, and in one government document from the 1930s was described as “white” with some black ancestry. In other words, these are people who were legally and socially white, they voted, their kids went to white schools, and they married, but local memory knew that they had some African ancestry. My father told me that as a child it was the equivalent of having a crazy aunt in the family.

I read an old article from the Richmond Times Dispatch, by Walter Plecker, a colleague of Grant’s, and the VA state registrar of vital statistics. In the article Plecker was complaining about Greene County, and some other counties, I believe, midwives listing mixed ancestry children as Mexican. On the face of it, Plecker was correct, the kids obviously weren’t Mexican. But it shows how Plecker was relatively powerless in the face of local ad hoc decisions on who was non-black and who wasn’t. Unlike the Nazis, he was not operating in a totalitarian system. I’ve never seen these Mexican birth certificates, they are still closed per state laws. Plecker also made an infamous list of surnames, you can find it online, of mixed-race families.

4) Your weekly fluff fix:

UPDATE:  Solved by Rob at 12:01 CDT

How has your week been?  Are you up, alert, and bright-eyed?  If not, go grab a cup of caffeine real quick… we’ll wait for you.

Got your caffeine ready to go?  I think you’ll enjoy today’s riddle; I enjoyed constructing it, and usually if a riddle leaves me somewhat *blah*, you don’t get too worked up about it, either.

Today’s riddle answer is an event:

.
This event occurred in the 20th Century.

It was big, but not the biggest we’ve ever seen.

In fact, it could have gone completely unnoticed at the time.

Oh, come now. You know what this is.

There was little scientific curiosity about this event when it occurred.

In fact, it wasn’t even investigated until over a decade had passed.

That’s amazing because events of this nature have caused major problems in the past, and will cause major problems in the future.

And you know this image, also.

You’ll often see mention of this, in pseudo-science, popular media, and scientific inquiry.

This event destroys, but that’s only one half of the coin.

Life as we know it probably wouldn’t be possible without events just like this one.

The goddess of beauty. Standing on the surface of another planet.

Events like this were more common in the past.

It happens everywhere.

You see something like it in miniature all the time.

Castle Bravo

And there you have it.  This riddle requires a specific answer, not one in general.  For instance, if the answer was the Sun, I wouldn’t accept “a star” for an answer.  Good luck!

Tremble in fear, Human! I have you in my clutches. RAWR!

Top picks

The Nobel Prize in Medicine was awarded to three scientists for understanding immunology. Because, let’s face it, no one else does. Meanwhile, it transpired that one of the laureates had died three days before. Cue hijinks.

“The US is experiencing ant invasions that are like those “endless [movie] franchises that never dies” Great post on invasive ants by Alex Wild.

A scan reveals a lemon-size mass in boy’s chest. Fearing cancer, surgeons operate & see something odd

Can you use brain scanners to detect paedophiles, by measuring their response to images of children? Would you even want to? Top Neuroskeptic post.

A great explainer on dark energy, by Sean Carroll. Where one I was completely lost, now I am merely very confused.

Awesome artist turns the dingy tunnels near Waterloo Station into musical instruments… with SCIENCE

How the Tate Britain used eye-tracking tech to restore a flood-damaged masterpiece.

AWESOME! ‘Invisibility Cloak’ Uses Mirages To Make Objects Vanish

It’s 1940. Niels Bohr needs to melt his two Nobel Prize medals before the Nazis find him. What does he do?

Carl Zimmer on the amazing slime moulds

The New York Times published a truly awful op/ed piece on iPhone addiction. There’s no shortage of takedowns of this neuro-fluff, but my favourite one was by Vaughan Bell: “The New York Times has just pissed its neuroscientific pants in public.”  Here’s another good one and one more from the Neurocritic. Meanwhile this old list of “Brain Scans Show That…” media stories from Dorothy Bishop is still relevant.

An awesome tribute to the science teachers who change our lives, collected by Steve SIlberman and featuring me, Rebecca Skloot, David Dobbs and more.

Astonishing down-the-microscope photos. This is one of the best of such series. My favourite are the spider eyes at the very end. Like domes on Mars.

Breast cancer’s false narrative, by Christie Aschwenden. What the media rarely tells you.

Top 5 volcanic lairs for the aspiring evil genius from the Geological Society of London

“[The Nobel in Medicine] was given to a scientist that many feel is undeserving of the honour,” says Kevin Bonham. But Carl Zimmer argues that Nobel Prize disputes are tedious and inevitable. “The people behind the Nobel Prize have done a lot of good. But the vehicle that delivers this good is absurd”

Awesome: watching an episode of Lie to Me makes people worse at detecting lies. Lie to Me lied to me!

Large Hadron Collider putting family-run particle colliders out of business

How the evolution of armadillos made them good carriers for leprosy, and surprisingly well-endowed.

“A bonfire is basically a tree running in reverse.” A lovely list of 20 things you didn’t know about fire, from Discover.

Oh bloody hell. A computer virus has hit the U.S. drone fleet. “We keep wiping it off, and it keeps coming back… We think it’s benign. But we just don’t know.” Great.

Science/news/writing

Science is Vital continues: Vital signs of an unhealthy future for UK science

What 300 sea otters can tell us about the ocean. Other than that it is insanely cute

The first clinical uses of whole-genome sequencing show just how challenging it can be. A great feature by Brendan Maher. And not all whole genome sequencing ends happily: an important story by Erika Check Hayden.

Russian tigers threatened by dog disease. These cats do not LOL.

Steve Jobs died. Here’s a well designed tribute. Meanwhile, Dr Len from the American Cancer Society calls Jobs a cancer survivor and SFGate describes the rare pancreatic cancer that Jobs had. But the last laugh goes to the Onion: Last American Who Knew What The F**k He Was Doing Dies

Judy Stone explains how clinical trials work and why they’re expensive.

“Science, besides having crackerjack storylines… and superb metaphors, is a cure for neurotic uncertainty.” Ann Finkbeiner on her conversion to science writing.

The Galapagos Islands are largely inhabited by creationists. From -5:01 onwards.

Eric Kandel on that unpopular and obscure branch of biology known as neuroscience. What a dude.

Cloned human embryo makes working stem cells. Er, yes, but they’re triploid! That’s not actually very good! All the fuss over abnormaliites in iPSCs seems trivial when the best the alternative technique can do is make triploid cells.

A gene that affects moral choices?

Screw you mind. Eight counter-productive effects of thought-suppression

How epigenetics works – a video by Neil deGrasse Tyson

How papers are withdrawn from scientific literature

“Shechtman said to himself in Hebrew, “Eyn chaya kazo,” which means “There can be no such creature.” 29 years later, he wins the Nobel Prize for Chemistry.

Fossils Help Revitalise Hard-Hit Newfoundland Fishing Area

How do you build a prosthetic foot that can support the weight of an elephant?

NESTA are developing a UK Alliance for Evidence, to look at the evidence base for social policy decisions. Interesting.

Prehistoric Dog Found with Mammoth Bone in Mouth

Solyndra and our solar future: the real story is $30 billion dollars being invested in renewables

100 year old time capsule could tell us more about the evolution of bacteria.

The United States Preventive Services Task Force says that PSA testing has no benefit for healthy men. About time. It really is a truly rubbish screening test.

Memory errors are all in the groove. Mo Costandi covers a new paper on a fold in our brains that affects our ability to discern what actually happened from what we imagined. Meanwhile, Time gets it completely wrong.

Empty space is empty except for all the “frothing, turbulent gas”

Judy Mikovits, the controversial researcher behind the XMRV-chronic fatigue syndrome link, has been fired. And there are some mighty dodgy dealings with some of her images.

The Guaraní believe that people with recurrent seizures are a gateway between the worlds of life & death.

“The surgeon fumbled and panicked, cursing the patient loudly for having “a very deep perineum” – more horror stories from the pre-anaesthetic era.

The origins of the midlife crisis

Drawing the line between science and pseudo-science.

Alzheimer’s might be contagious like prions. Er, only if its transmitted by a scientist injecting you in the brain with a needle. And if you’re a mouse.

What does success look like in big science?

“It went from ‘Oh, this is a terrible mistake’ to ‘Oh my God, this might be the right answer!” – Adam Reiss on his Nobel win.

Would-be geoengineers must listen to the public

A creationist’s claims that atoms are “irreducibly complex” have been thoroughly dismantled.

Whales – one of evolution’s greatest punchlines

There are little mites in your eyelash and they can pop out and crawl over your face. Thye’re largely harmless, until they’re not.

The hairs in your nose continue to beat after death

Paleolithic finger painting? Finger flutings in Rouffignac cave suggest young kids contributed to cave art

World’s largest river restoration project is now underway on Washington’s Elwha River, with the tallest dam ever to come down.

A fascinating account of a woman with multiple personality disorder

18% of statistical results reported in psychology papers are incorrectly reported.

Future of Chernobyl health studies in doubt

800,000 Manmade Plant Fossils (and counting)

Yeah when I’m 85, I probably won’t be jetting off to Antarctica. All hail David Attenborough

Heh/wow/huh

The Bloggess declines a pointless pitch & the Vice-President of a PR company calls her “a f**king bitch”

Forget Siri, get GLaDOS on your iPhone

When there is writing on the blackboards in porn, is it correct? NSFW-ish.

Sea snake versus moray eel.

A giant herd of thousands of walruses hauled out on the Alaskan coast

“Deliveries anywhere? ALRIGHT! Bring me llamas now!

Phil Plait with the week’s best/worst headline.

A surprisingly funny abstract if you happen to know someone called Tim, or six.

Passive Aggressive Birds

The Star Wars/Seven crossover ended badly

An intelligent design children’s book with a fire-breathing Parasaurolophus.

“First and last authorship determined by coin flip”

Six ways to never get lost in a city again

Dan Macarthur asked for a consensus phylogeny of mammal species. I drew one

Abandoned Lego Victorian houses.

I really want a satirical 21st-century reimagining of Captain Planet

Beautiful pic of a meteor’s lingering glowing streak, with and equally beautiful explanation by Phil Plait.

Heh. Cat learns harsh reality of internet viral videos

Gnarly. Surfers make bioluminescent waves off San Diego coast by disturbing bloom of phytoplankton

Solving all your problems…with tanks

Internet/journalism/society

Italian Wikipedia replaces every page with free speech protest

For Ada Lovelace Day, Alice Bell compiled a list of 50 lovely women tweeters in sci, tech, environment and/or health

“Blood must be spilled but the cat will be anesthetized.” On vampires, magic duels and headless bodies in Highgate Cemetery.

Before Hitler, who was the rhetorical Hitler? The Pharaoh.

The Daily Mail produces little good content of its own, so it lifts what other people do.

John Rennie complains about Andy Revkin’s false equivalence on climate message machines.

“It’s not that journalists are biased, lazy or stupid… the problem is that they’re slaves to formula.”

On Naïveté Among Scientists Who Wish to Communicate – Kevin Zelnio takes issue with Christie Wilcox’s post on scientists and social media. And Christie comes back: “I wasn’t saying build it & they will come. I was saying don’t build it & they can’t come.”

Remember that game where you stopped your digital wristwatch on every second? There’s an app for that.

Please welcome Robert Stewart-Rogers & his new science blog Handsome Science. Photos, insects, lovely writing

The biggest mall in the world is in China, and it’s empty. 2% occupancy

Alice Bell is collecting memories of kids’ environmental media.

“Sendak is still enraged by almost everything that crosses his landscape.”

Why are so few popular science books written by women?

Facebook is okay with pro-rape pages, and likens them to rude jokes in a pub.

And ambitious project: Hypothes.is: The Internet, Peer Reviewed.

Dan Harmon of Community treats every story arc as an eight-part circle

Tuvalu, a small island nation, is down to its last few days of water.

After 25 years, The Scientist, a magazine that made the careers of many science journalists, has folded.

A few nights ago, my wife went outside for a moment, only to come running back in a minute later, grabbing me. "Phil, come out here, you have to see this!"

So I went out, and she pointed out this lovely lady to me:

I recognized it right away: a katydid, though that’s a fairly generic name. I think that’s actually an example of Microcentrum retinerve, or the Lesser Angle-winged Katydid (though it’s possibly Microcentrum rhombifolium; it’s hard to tell in these pictures^*). They’re pretty common in North America, though usually not this far west from what I can tell. It was roughly 5 – 7 cm long, and quite pretty. I suspect this one is female because there are no brown spots near the tops of the wings, which males have (I wondered briefly if it may have been a nymph, but this late in the season that seems unlikely). I would’ve checked for an ovipositor, but c’mon, have some respect.

Check out those wings: they look amazingly like plant leaves, which is of course why my wife was so excited. The obvious conclusion is that long ago, the insects like this that had greenish wings with vein-like structures were harder to spot by predatory birds, and were able to pass this characteristic down to their kids (ones that were easier to see got eaten, and didn’t get a chance to reproduce as much). Little by little, bit by bit, every time one insect’s wings looked a bit more leafy than its siblings it would tend to live longer, and reproduce more. Over thousands, millions, of generations of katydids we get this: an insect that would be incredibly difficult to see from the air. Natural selection at work, my friends. Some people would even call this evolution. I know I would.

A very cool thing to see, and a fun example of how wonderful and subtle nature can be.

But sometimes subtlety is overrated. Wouldn’t it have been cooler to see one like this?

[If you like pix of insects, my Hive Overmind co-blogger Ed Yong just coincidentally mentioned the blog Myrmecos by Alex Wild, which has stunning photography.]

^* And duh, of course I had to look those names up online. I’m an astronomer, not a bugologist.

Galaxy Arp 220 (main image, taken with the Hubble Space Telescope) with some of its newly discovered supernovae (inset, taken with Global VLBI). The inset image is 250 light years across. Click for larger. Credit: NASA, ESA, Hubble Heritage Team, Chalmers via Spaceref

Arp 220 is what happens when two galaxies merge and it is known to be a prodigious star maker. The name Arp 220 comes from the fact it is listed in Halton Arp’s Atlas of Peculiar Galaxies and that seems to be quite fitting. Aside from the star formation, the presence of organic molecules and now finding that it is quite a “supernova factory”, there is also at least two masers sources in the galaxy: a OH megamaser and a water maser.

Here’s the Onsala press release:

A team led by astronomers at Chalmers and Onsala Space Observatory has detected seven previously unknown supernovae in a galaxy 250 million light years away. Never before have so many supernovae been discovered at the same time in the same galaxy. The results are accepted for publication in the Astrophysical Journal.

The discovery proves what astronomers have long believed: that the galaxies which are the universe’s most efficient star-factories are also supernova factories.

The astronomers used a worldwide network of radio telescopes in five countries, including Sweden, to be able to create extremely sharp images of the galaxy Arp 220. The scientists observed around 40 radio sources in the center of the galaxy Arp 220. These radio sources are hidden behind thick layers of dust and gas and invisible in ordinary telescopes. To discover the nature of these radio sources, they made measurements at different radio wavelengths and watched how they changed over several years.

“With all the data in place, we can now be certain that all seven of these sources are supernovae: stars that exploded in the last 60 years,” says Fabien Batejat, main author of the article about the discovery.

So many supernovae have never before been detected in the same galaxy. The number is nevertheless consistent with how fast stars are forming in Arp 220.

“In Arp 220, we see far more supernovae than in our galaxy. We estimate that a star explodes in Arp 220 once every quarter. In the Milky Way, there is only one supernova per century,” says Rodrigo Parra, astronomer at the European Southern Observatory in Chile and member of the team.

John Conway is professor of observational radio astronomy at Chalmers and deputy director of Onsala Space Observatory.

“Arp 220 is well-known as a place where star formation is very efficient. Now we have been able to show that star factories like this are also supernova factories,” he says.

The radio measurements have also given researchers insight into how radio waves are generated in supernovae and their remnants.

“Our measurements show that a supernova’s own magnetic field is what gives rise to its radio emission, not the magnetic fields in the galaxy around it,” says Fabien Batejat.