In this week's "Ask a Physicist," we tackle a general relativistic paradox: If time slows down near the event horizon of a black hole, how does anything ever fall in?

I've been enjoying reading all of your questions to "Ask a Physicist." As an added twist in the coming weeks, I'd be interested in hearing any questions you have about physics and cosmology in the news, especially those along the lines of, "Is this real, or just bullshit?" As always, please send your queries to askaphysicist@io9.com

Today's question comes to us from David Sirola who asks:

If a black hole warps space-time to such a degree to slow and stop time, how can anything ever disappear past the event horizon (or whatever point t=0)? It would seem to me in my superficial understanding, that ultimately, after all the fun at the outer edges of the hole, that nothing ever really happens, since happens implies a time/cause/effect relationship.

What am I missing here?

Let's get one thing out of the way from the outset: Black holes are awesome. They are the only major disturbance of space-time which have the advantage of actually being known to exist. Almost every large galaxy, including our own, seems to have a supermassive black hole at the center.

And black holes are ridiculously simple objects — or at least the non-rotating ones are, which are the only ones I'm going to talk about here. They basically consist of an infinitely compact "singularity" at the center and an outer boundary known as an "event horizon" from which nothing can escape (and here's where I'm supposed to use an ominously spooky voice) not even light. These guys are tiny, astronomically speaking. Were our sun to become a black hole, it would be smaller in radius than the city of Philadelphia. Even the 3 million solar mass black hole at the center of the Milky Way could comfortably fit inside the orbit of Mercury.

Okay, you probably knew all of that. I still need to dispel a few myths before we get into the hardcore space-warping.

1. Black holes don't suck.

   Suppose the sun were to suddenly turn into a black hole. Would you notice? Sure you would. The sun would blink out of existence and you'd quickly freeze to death. But in your dying moments, you'd no doubt be struck by the fact that J.J. Abrams lied to you. Rather than get pulled into the black-hole sun, the earth would just keep orbiting that seemingly empty point in the sky, exactly as it always had. Only icier.

2. You can't actually see them.

   Black holes are called that because they don't give off any light. I don't want to get into a nerd-fight here, partly because my mom says I'm not allowed, but mostly because things will go more smoothly if I anticipate a few objections. Somebody is likely to point out that we do, indeed, "see" black holes in the form of quasars in other galaxies. But this isn't quite right. What you're really seeing is hot, glowing gas falling onto the black hole or even larger glowing gas clouds surrounding the whole shebang. And by the way, with the exception of giant radio jets, we can't even generally resolve these clouds. When you see detailed accretion disks in news stories about black holes, that's somebody using MS Paint or whatever they use these days to make artist's conceptions.

   Let me further anticipate a black-belt level nerd who might introduce an even better possibility: Hawking Radiation. This is one of the coolest ideas in astrophysics, and one that most physicists believe, even though we've never observed it. Near the event horizon of black holes, particles and antiparticles are constantly being created in pairs. Every now and again, one of the particles escapes and creates some radiation (and takes with it some of the mass-energy of the black hole). But here's the deal: Hawking radiation is far too dim, and far too long of wavelength to ever be seen directly.

Now that we've got the lay of the land, we can get into the question of what's so special about the event horizon.

One of the major predictions of general relativity is that time runs slower near massive bodies than far away. On earth, we don't notice this effect, since the effect is only about 1 part in a billion. However, if you were of a stout enough constitution (we're talking, like 18+2, or something like that) you could hang out on a neutron star where the effect is more like 20% or more. Hang out for a few years, and even more time will have passed far away. What you've done here is built a (pretty crappy) time machine into the future. Also, this would be a one-way trip.

Black holes do it one better, and at the event horizon the time distortion effect literally becomes infinite. There's the paradox. If time slows down infinitely near the surface, presumably it takes stuff longer and longer to get closer and closer to the event horizon. How does anything ever actually fall in?

Let's imagine you have a friend who you didn't mind sacrificing for science. Suppose he decided to jump feet first into a black hole. What do you see when he crosses the event horizon?

Well, first off, you're not going to see him cross the event horizon at all because he's going to be torn to shreds by tidal forces long before-hand. He's also going be squeezed by the strong gravitational forces until he's ripped apart atom by atom. To those of you who either whispered under your breath (or more likely squealed with delight), "Spaghettification," good for you!

It's unfortunate for your friend, however, as he will most certainly not survive the ordeal. There is a glimmer of good news, however. A friend and former professor of mine, Rich Gott did an interesting calculation in which he found that regardless of the size of the black hole, it would take approximately one tenth of a second between the moment when you first felt mildly uncomfortable to the time when you are ripped atom from atom. Incidentally, if you'd like to read more about what's in store when falling in, you should check out Neil Tyson's discussion of the subject or my own.

But let's forget about this unpleasantness. Even if your friend could somehow survive the process, you couldn't see him fall in because eventually his signal is going to disappear. If your clock is running slow, this means that everything you could possibly use to measure time — including the frequency of light, will also appear to run slow. Light emitted from your friend's ship, for example, becomes longer and longer in wavelength as he approaches the event horizon until you can't see him at all. Even if you were looking at him with a radio detector, eventually his signal would be too low a frequency for you to see him.

Of course, from his perspective, it happens the other way around. Photons (and other particles) coming from the outside will appear to have a much higher frequency and much higher energies than they would otherwise. Even if he could somehow have survived the spaghettification, the high energy particles would rip him apart. This is a common theme, and one of the big puzzles of black holes. After all, if everything — keys and chairs and friends and particles lose their identity when they fall in — where does that information go?

And there would be a lot of particles, too. After all, just as you see your friend running slow, he sees you running fast. Indeed, someone dangling near the edge of a black hole would see the rest of the universe infinitely sped up. He could literally see the entire future of the universe.

Sort of. This only works if we can dangle someone just outside the black hole without them falling in. Supposing they were actually falling, they'd cross the event horizon and barely notice it (except for the dying part). From the perspective of people (and particles) inside the black hole there is no paradox. Everything falls in in a perfectly reasonable amount of time.

How reasonable? Well, I suppose I'd better answer the original question. Let's see you dropped your friend into a black hole the mass of the sun, and let him go at the same distance the earth currently is from the sun. It takes a surprisingly long time to fall in (from his perspective), a bit over 2 months. Of course, except for the last second or so, this is pretty uneventful. In fact, up until the last minute or so, your friend isn't even traveling an appreciable fraction of the speed of light and is so far outside the event horizon that you two could have a perfectly normal, nearly time-synchronized, conversation.

But after your friend falls in, and he tries to tell you how long it took, he's just SOL. Remember, nothing can escape, not even light. But of course, you knew that already.

Dave Goldberg is the author, with Jeff Blomquist, of "A User's Guide to the Universe: Surviving the Perils of Black Holes, Time Paradoxes, and Quantum Uncertainty." (follow us on facebook or twitter.) He is an Associate Professor of Physics at Drexel University. Feel free to send email to askaphysicist@io9.com with any questions about the universe.

Last month rumors swirled that scientists at Fermilab's Tevatron particle accelerator found the Higgs Boson particle. Those reports were untrue, but we have made significant progress towards finding the elusive particle. Why is this such an important discovery?

What is the Higgs Boson?

The Higgs is one of the five bosonic elementary particles, each of which acts as a carrier of a fundamental property of nature. The other four bosons, known as the gauge bosons, are the carriers of the fundamental forces - photons carry electromagnetism, the W and Z bosons both carry the weak nuclear force, and gluons carry the strong nuclear force. (There's also another hypothetical gauge boson, the graviton, which unsurprisingly carries the gravitational force, but that one remains undiscovered.)

Now, the Higgs Boson is the carrier of mass in the universe. It does this by helping to form a Higgs field, a quantum structure through which all the other elementary particles pass. According to the Standard Model of physics, certain particles - such as the photon - pass through the field unaffected and remain massless, while others - such as the W and Z bosons - bring part of the field with them, giving them mass. This subatomic interaction with the Higgs field is what accounts for the existence of all the mass in the universe - at least, if the theory is correct. And the only way to confirm it is to find the Higgs Boson.

Why is the Higgs Boson so difficult to find?

It's a relatively massive subatomic particle, thought to be over a hundred times the mass of a proton. The problem is that the Higgs Boson is thought to exist at extremely high energy levels - so high that only the newly built Large Hadron Collider is thought to be capable of achieving them. And then it only survives for a few seconds before decaying into other particles. Then there's the fact that, despite some rather ingenious deductions of its nature using indirect evidence, we still don't really know exactly where we should be looking for the Higgs Boson.

Today we're getting closer to knowing the Higgs Boson mass

Scientists at Fermilab, home of the world's most powerful particle accelerator that isn't the LHC, have been able to significantly narrow down the possible masses of the Higgs.

Physicists use the unit of measurement GeV/c^2, or Gigaelectronvolts divided by the speed of light squared, to measure the mass of subatomic particles. An electronvolt is the amount of energy of, you guessed it, a single electron. Because of Einstein's iconic equation E=mc^2, dividing the electronvolt by the speed of light squared makes it a unit of mass. And because most subatomic particles are much, much bigger than the tiny electron, we have to bump up the unit of measurement we use from electronvolts to gigaelectronvolts, or a billion electronvolts. Protons have a mass of about one GeV/c^2.

Here's what the Fermilab scientists found - their experiments with the Tevatron particle accelerator have conclusively ruled out a Higgs Boson with a mass between 158 and 175 GeV/c^2. Since the previously known range extends from 114 to 185 GeV/c^2, that means nearly a quarter of the possible masses have been eliminated.

Those remaining higher masses may be soon to fall as well, says physicist Dmitri Denisov:

We are close to completely ruling out a Higgs boson with a large mass. Three years ago, we would not have thought that this would be possible. With more data coming in, our experiments are beginning to be sensitive to a low-mass Higgs boson.

But where is the Higgs Boson?

If the Higgs does exist, it's running out of possible hiding spots, says University of Manchester physicist Stefan Söldner-Rembold:

"Our latest result is based on about twice as much data as a year and a half ago. As we continue to collect and analyze data, the Tevatron experiments will either exclude the Standard Model Higgs boson in the entire allowed mass range or see first hints of its existence."

It was thought until recently that the Large Hadron Collider held the only practical hope of discovering the Higgs Boson, but now it looks as though Fermilab's Tevatron accelerator is back in the hunt as well. As Fermilab spokespeople point out, creating high energy environments may actually be less important than simply creating as huge an amount of collisions as possible. We haven't found the Higgs Boson yet, but we're fast approaching the moment of truth: either we will discover it and confirm the Standard Model in the process, or we will have to reluctantly head back to the drawing board and start building a Higgs-less universe.

[Fermilab]

Segmentation, the replication of anatomical structures throughout the body, is found in many animal species. It's also a huge reason why all those species succeeded, and it comes from a single common ancestor 600 million years ago.

Specifically, segmentation refers to instances where identical anatomical units are repeated on the axis running from the top to a bottom of an animal. (So the fact that we have eyes, ears, arms, and legs that are all identical doesn't count as segmentation.) Obviously segmented species include centipedes and millipedes, in which a single structure is repeated dozens, even hundreds, of times over, but they're hardly the only examples. Anything from earthworms to humans can possess segmented features.

Three of the most basic groups of animals - arthropods (insects, arachnids, and crustaceans), vertebrates (most animals that we're familiar with), and annelid worms (sea and earthworms, basically) - all heavily make use of segmentation throughout their individual species, and yet they're very distantly related groups. Recent evidence indicates that the genes controlling segmentation are essentially the same in anthropod and worm species, indicating that there was indeed a single common ancestor, probably a worm-like creature, some 600 million years ago that proved phenomenally successful because of its ability to segment.

So why does segmentation provide such a huge evolutionary advantage, and why has it helped bring about such fantastic animal diversity? The answer might be quite simple: segmentation creates ready-made spare parts, producing duplicated anatomical units that can be repurposed as needed. If a species is under heavy pressure to fit into a changing environmental niche, it may need to develop new structures that can deal with the altered conditions. In that instance, it would be much easier to modify an existing organ than build a whole new one. Segmentation would give species a better shot at quickly adapting to new environments, which would create more pronounced changes in the species and, thus, greater diversity.

In that case, segmentation is the ultimate example of what Stephen Jay Gould dubbed an exaptation, in which a trait becomes extremely useful for reasons unrelated to its initial development. If nothing else, there's a certain evolutionary irony in that the exact duplication of body parts is responsible for why animal species all look so wildly different.

via Science

The kind of drowning you see on T.V.—think thrashy, screamy—doesn't have much in common with what real drowning looks like, according to writer and Navy/Coast Guard veteran Mario Vittone. That's because of something called the Instinctive Drowning Response, a pattern of behavior that appears to be hard-wired into humans and pops up whenever somebody feels like they're suffocating in water.

Frank Pia, Ph.D., the psychologist and lifeguard to first described the Instinctive Drowning Response explains it this way:

1. 1. Except in rare circumstances, drowning people are physiologically unable to call out for help. The respiratory system was designed for breathing. Speech is the secondary or overlaid function. Breathing must be fulfilled, before speech occurs.

2. 2. Drowning people's mouths alternately sink below and reappear above the surface of the water. The mouths of drowning people are not above the surface of the water long enough for them to exhale, inhale, and call out for help. When the drowning people's mouths are above the surface, they exhale and inhale quickly as their mouths start to sink below the surface of the water.

3. 3. Drowning people cannot wave for help. Nature instinctively forces them to extend their arms laterally and press down on the water's surface. Pressing down on the surface of the water, permits drowning people to leverage their bodies so they can lift their mouths out of the water to breathe.

4. 4. Throughout the Instinctive Drowning Response, drowning people cannot voluntarily control their arm movements. Physiologically, drowning people who are struggling on the surface of the water cannot stop drowning and perform voluntary movements such as waving for help, moving toward a rescuer, or reaching out for a piece of rescue equipment.

5. 5. From beginning to end of the Instinctive Drowning Response people's bodies remain upright in the water, with no evidence of a supporting kick. Unless rescued by a trained lifeguard, these drowning people can only struggle on the surface of the water from 20 to 60 seconds before submersion occurs.

In real life, a drowning person will be a lot more still and silent than you expect.

Time travel isn't just science fiction: Albert Einstein's general relativity suggests it could exist. And now we might have solved the tricky matter of time paradoxes. It's all just a question of adjusting probabilities.

A certain reading of Einstein's theories argue for the existence of closed timelike curves, which are strange paths of spacetime that take anything traveling on them into the past and then back to the future. First proposed by Kurt Gödel in 1949, CTCs could theoretically exist deep within black holes or other similarly chaotic corners of the universe. Since these CTCs, however difficult they might be to access, would apparently make time travel into the past a genuine possibility, the question then becomes how to deal with the potential time paradoxes.

As always, the Grandfather Paradox, in which a time traveler kills his or her grandfather before he fathered the traveler's parent, gets the most attention here. Various workarounds have been proposed over the years - Oxford physicist David Deutsch came up with an intriguing possibility in the early 90s when he suggested that it was impossible to kill your grandfather, but it was possible to remember killing your grandfather. In some weird way, the universe would forbid you from creating a paradox, even if your memories told you that you had.

This theory, like most others put forward, relies on liberal use of the word "somehow" and the phrase "for some reason" to explain how it works. As such, it's not an ideal explanation for paradox-free time travel, and that's where a new idea by MIT's Seth Lloyd comes into the picture. He says that paradoxes might be impossible, but extremely improbable things that prevent them from happening very definitely aren't.

Let's go back to the grandfather paradox to see what he means. Let's say you shoot your grandfather at point-blank range. This theory suggests that something will happen, such as the bullet being defective or the gun misfiring, to stop your temporal assassination. This can involve some very low-probability events - for instance, the manufacturer becomes incredibly more likely to make that specific bullet improperly than any other, for the sole reason that it will be later used to kill your grandfather. It might even come down to an ultra-low-probability quantum fluctuation, in which the bullet suddenly alters course for no apparent physical reason, in order to keep the paradox at bay.

Dubbed the post-selected model, Lloyd's theory is all about trading the impossible for the improbable, which admittedly can cause some very, very unlikely things to happen right around the specific moment where the paradox would otherwise occur. As Charles Bennett of IBM's Watson Research Center explains:

"If you make a slight change in the initial conditions, the paradoxical situation won't happen. That looks like a good thing, but what it means is that if you're very near the paradoxical condition, then slight differences will be extremely amplified."

Incredibly enough, Lloyd and his team say they actually have some experimental evidence of the theory. Though they obviously can't send anything, even a subatomic particle, back in time, they can at least create certain quantum conditions that would closely resemble those experienced by a time traveler. They placed photons in these temporal-like circumstances and then tried to push them towards what were essentially paradoxical situations. The closer they got, the more frequently the experiment failed, and they argue the universe as a whole could function in much the same way when it comes to stopping paradoxes. (This is probably one of those times when you're going to need to read the original paper to understand what they were up to here, because I'll readily admit this is a bit beyond my comprehension.)

In any event, other physicists have met the new theories with great enthusiasm. Todd Burn of the University of Southern California calls it "a nice, consistent loop" and "a really interesting body of work." However, he reminds us that, for now, these aren't much more than clever thought experiments:

"I don't expect these will be tested anytime soon. These are ideas. They're fun to play with."

Looks like we need to find a closed timelike curve. Who's up for a sightseeing trip to the nearest black hole?

[arXiv]

Even the most minuscule, atom-sized surface imperfections can pose colossal obstacles for the speedy flow of electrons. But certain substances create a remarkable condition where the electrons are able to completely ignore these pitfalls and move ultra-fast.

On most surfaces, tiny imperfections are like gigantic cliffs to electrons, which can become temporarily trapped and jam up the proper flow of the particles. For circuits that process information using electron flow, that's a major problem that needs to be carefully guarded against, which limits their maximum potential performance.

However, recent theories hold that certain compounds that contain the element antimony (or other elements with very similar chemical properties, but antimony works best) would provide electrons an essentially smooth surface. Although these nano-sized cliffs and crevasses would still exist, antimony helps create a special form of electron wave that allows the electrons to effortlessly flow around any possible imperfection.

Princeton physicist Ali Yazdani, who discovered this remarkable property, explains the potential applications of this discovery:

"Material imperfections just cannot trap these surface electrons. This demonstration suggests that surface conduction in these compounds may be useful for high-current transmission even in the presence of atomic scale irregularities — an electronic feature sought to efficiently interconnect nanoscale devices."

Antimony has a long history of practical use, but its strange properties with regards to surface conduction had been ignored until now. Admittedly, it's only recently become possible to even study how electrons flow at just the surface, requiring the development of incredibly precise techniques able to visualize surface electrons. Antimony is one of the so-called "topological" materials, which are able to give surface electrons these unique, free-flowing properties.

[Nature]

The deadly poison made famous in countless Agatha Christie mysteries isn't known for its health benefits. But an arsenic compound has helped treat leukemia sufferers for over a decade, and we've just discovered it can fight other cancers as well.

The specific compound is arsenic trioxide, and it's already been approved by the FDA for the treatment of humans. The arsenic is combined with other therapies to fight cancers brought on by an error in a cellular signaling pathway known as the Hedgehog pathway. This signaling cascade regulates embryonic development and remains crucial to properly functioning cells in adults. Malfunctions in the Hedgehog pathway have been shown to cause tumors in the skin, brain, blood, and muscle.

Arsenic trioxide works in relatively low quantities by blocking one of the final steps in the Hedgehog pathway, preventing a few of the cell's genes being expressed that would otherwise cause runaway, cancerous growth. Other treatments currently on the market also target the Hedgehog pathway, but they do so at much earlier points in the signaling cascade. That gives the malfunctioning pathway many more opportunities to mutate around the drug and relay its self-destructive messages to the cells. The arsenic treatment takes effect so late in the pathway that's there is nearly no chance for the cancer to mutate around it.

Researchers Philip Beachy and Jynho Kim at the Stanford medical school first became interested in arsenic as a treatment for cancer when they noticed that birth defects brought on by arsenic exposure are very similar to the physical effects of not having an active Hedgehog pathway. They found that the same small amounts of arsenic trioxide that treated leukemia patients could also shut off the Hedgehog pathway, providing a potential treatment for sufferers of many other kinds of cancer.

Arsenic trioxide works by inhibiting a protein called Gli2 from causing gene transcription in the cell nucleus. Without Gli2, the Hedgehog pathway comes to a sudden, ineffectual end. Early tests of this treatment on mice found that most tumors either slowed down or stopped growing completely. Best of all, this works even in cells that have already proven resistant to other drugs that target the Hedgehog pathway.

[Proceedings of the National Academy of Sciences]

The current explanation of the universe's origins relies on clumsy assumptions and can't explain most subatomic particles. A small tweak to general relativity solves these problems - and seemingly proves the universe must have come from a black hole elsewhere.

As it stands right now, the explanation for the universe's beginnings is built around a combination of Einstein's general relativity and observation of the ancient universe. Mixing these two theories together creates some problems - for instance, the universe is impossibly large according to its current rate of expansion, so astrophysicists have to invoke the idea of inflation, in which the early universe expanded at a tremendous rate within the first second after the Big Bang.

General relativity, however, can't explain inflation, so another theory is required to account for it. There's nothing technically wrong with that, but it's an inelegant solution, and physicists tend to prefer an all-encompassing explanation to a bunch of piecemeal solutions. That's not the only issue with the current explanation - it can't deal with many properties of subatomic particles, consigning them entirely to the realm of quantum mechanics.

Nikodem Poplawski of Indiana University thinks solving the latter problem can also solve the former, and that's just the start of the craziness. In a new paper, he explains that the standard version of general relativity totally ignores the intrinsic momentum of subatomic particles like protons and neutrons, but a modified version known as the Einstein-Cartan-Kibble-Sciama theory of gravity solves that problem. The theory states these particles interact repulsively, creating tiny amounts of a force called torsion.

Under normal circumstances, this is just an interesting bit of math, and torsion doesn't really affect anything. However, if densities are increased tremendously, then torsion has some very significant effects. Most intriguingly, torsion makes it impossible for black holes to form singularities. And if singularities are impossible, then what's at the center of black holes?

Poplawski has an audacious proposal: there are whole universes where we thought the singularities were. The torsion process allows for a massive energy buildup inside the event horizon, and this would allow for the creation of new particles through pair production, in which matter and antimatter are created in equal quantities. All it takes then is a small imbalance between the particles and antiparticles to form, and you've got a Big Bang on your hands.

What makes this idea appealing (beyond the fact that it just sounds so awesome) is that torsion explains inflation without requiring a new theory. That repulsive force is sufficient to explain how the universe expanded to its present extent, which means a single theory can explain the entire universe as it is now.

This potentially means that many of the black holes in our own universe are the incubators of entirely new universes, each separated by the infinite time gap of the event horizon. That said, some properties of the mother universe could trickle through to its daughters, and detecting some of these properties could actually provide experimental proof of the theory. In fact Poplawski speculates this inheritance of properties could solve another great mystery of cosmology.

The so-called arrow of time, in which time flows in one direction but not another, is a fundamental aspect of our experience. This isn't accounted for at all by physics, as all of its laws are apparently time-symmetric in that they work just as well whether time flows forwards or backwards. However, the passage of matter through the event horizon would provide a time asymmetry in the new universe, giving it a forward arrow to time. In that way, time itself is a gift of our mother universe on the other side of the black hole.

[arXiv]

Researchers are getting closer to nailing down the actual mass of neutrinos by studying their interaction with the Universe as a whole. A paper published in Physics Review Letters this week describes how the history of galaxy formation indicates that the mass of neutrinos must be less than 0.28 electron volts. This lowers the mass ceiling by half, and researchers hope that technology will allow them to find the exact neutrino mass within the next decade. Knowing the exact mass would offer insight into particle physics and cosmology, among other things.

Scientists know that neutrinos are some of the lightest particles around. They come in three flavors: muon, tau, and electron, and it's possible to get some sense of their relative masses. However, details on their physical nature have been hard to come by, and their absolute mass has been difficult to determine.

The best researchers have been able to do is narrow the mass down to a window, with each new experiment shrinking the range a bit further. The upper limit has gone from 7.0 to 1.3 to 0.58 electron volts, and the lower limit from zero to about 0.05 electron volts. To push the limits closer, a research group turned its gaze to the Universe as a whole.

Even though neutrinos do have some mass, they tend to inhibit the clumping of matter, since they're so light and move so quickly that they don't tend to aggregate. On small scales (small being a relative term here), the bigger neutrinos were, the less galaxy formation there would be.

The researchers took pictures of deep space to observe the state of the Universe billions of years ago and compared them to pictures of areas nearer by to see how the formation rate has changed. Based on this measure, they determined that the rate of galaxy formation is only large enough for the sum of the masses of the three neutrinos to be no larger than 0.28 electron volts.

While the number isn't definitive, the authors hope they can refine their measurement further with more detailed pictures of space that can encompass items like Lyman-alpha forests and weak lensing. He predicts that cosmological observation technology should be sufficiently advanced to pinpoint the exact neutrino mass within the next decade. Determining the individual mass of each individual neutrino, though, may take a bit longer.

Physics Review Letters, 2010. DOI: 10.1103/PhysRevLett.105.031301

APS Physics, 2010. DOI: 10.1103/Physics.3.57  (About DOIs).

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For several days, bloggers and journalists have been passing around a news story about how the BP oil disaster will unleash a "giant methane bubble" and initiate a mass extinction. Yes, it's a myth. And we've busted it.

In this article, called "Doomsday: How BP Gulf disaster may have triggered a 'world-killing' event," a guy named Terrence Aym takes some information he got from a "Mega Disasters" TV special on undersea methane bubbles and mixes it with comments about how there are "giant rifts" beneath the sea and an "information blackout." He proposes that a "twenty mile methane bubble" dislodged by the BP oil disaster will erupt from the ocean floor, causing tidal waves and giant explosions. The sad part about all this is that news organizations and blogs took the story seriously.

While it's true that there are methane bubbles (and methane ice) beneath the ocean floor, they are not about to erupt from Gulf and destroy all life on Earth. This morning I spoke with two Earth scientists, Dave Valentine of UC Santa Barbara and Chris Reddy of the Woods Hole Oceanographic Institute, who study methane and oil seeps from the sea floor. Valentine has just been out to the Gulf to study the methane levels there, and told io9:

During our recent cruise to the Gulf we observed significantly elevated levels of methane at water depth greater than 2500 feet, in the vicinity of the Deepwater Horizon spill site. While the total quantity of methane and other hydrocarbons is enough to cause problems with the regional ecosystem, there is no plausible scenario by which this event alone will cause global-scale extinctions.

So yes, there is a methane seep. No, it will not cause tidal waves or explode.

Another fishy fact in the methane bubble doomsday story is Aym's description of how methane bubbles are what caused the End Permian mass extinction event 250 million years ago - a mass extinction that I wrote about recently, here. Many scientists do believe that atmospheric changes and ocean anoxia (de-oxygenization) were to blame for that extinction - but even Gregory Ryskin, the scientist whose highly speculative work is cited in the article, doesn't try to claim this as the sole cause, nor does he believe that one bubble of methane could bring down the biosphere instantly. The End Permian extinction took millennia to happen.

So the BP oil spill isn't going to end the world - it's just going to kill a lot of ocean life. And already-existing methane seeps may be doing slow, deadly damage to our climate. All this makes it even more obvious that we need to invest in alternate forms of energy. But who wants to hear difficult, complicated pieces of information, when we could just be screaming about doomsday?

If you'd like to learn more about how methane bubbles really work, here are a few scientific articles:

Dissolved methane distributions and air-sea flux in the plume of a massive seep field, Coal Oil Point, California

Enhanced lifetime of methane bubble streams in the deep ocean [PDF]

Fate of rising methane bubbles in stratified waters: How much methane reaches the atmosphere [PDF]

Methane discharge from a deep-sea submarine mud volcano into the upper water column by gas hydrate-coated methane bubbles [PDF]

Or you can indulge in rank speculation:

Improving human mental health is having some serious unintended consequences for our friends in the ocean. Exposure to antidepressants makes shrimp five times more likely to place themselves in life-threatening situations, and the broader effects could damage the entire ecosystem.

Exposure to the antidepressant fluoxetine causes shrimp to radically alter their behavior. While normal shrimp are more likely to avoid swimming towards light because it's often associated with prey like birds or fishermen, those exposed to fluoxetine become five times more likely to swim towards light than away from it. That change in behavior places them in harm's way, and if enough shrimp are exposed to the antidepressant the entire population could be at risk.

Alex Ford, a marine biologist at the UK's University of Portsmouth, explains how that can reverberate throughout the oceanic ecosystem and why this is a serious concern:

Crustaceans are crucial to the food chain and if shrimps' natural behaviour is being changed because of antidepressant levels in the sea this could seriously upset the natural balance of the ecosystem. Much of what humans consume you can detect in the water in some concentration. We're a nation of coffee drinkers and there is a huge amount of caffeine found in waste water, for example. It's no surprise that what we get from the pharmacy will also be contaminating the country's waterways.

Ford exposed some shrimp to the same amount of fluoxetine that humans excrete into the waste water that gets carried out to sea. He found that even this seemingly small amount was enough to trigger this major behavioral change in the shrimp. He had been motivated to investigate this question by a parasite that is known to cause such changes by altering serotonin levels in shrimp. He wanted to find out whether the same deleterious result could be obtained using human antidepressants; the answer, sadly, is yes.

He explains how small individual amounts of antidepressants adds up to a big problem:

Effluent [outflowing waste water] is concentrated in river estuaries and coastal areas, which is where shrimps and other marine life live — this means that the shrimps are taking on the excreted drugs of whole towns.

Prescriptions for antidepressants have skyrocketed in recent years, but this is one of the very first attempts to figure out what ecological impact all that pharmaceutical sewage could have. The most worrying part of it all is that this might just be the tip of an ecosystem-altering iceberg - there are lots of other drugs other than fluoxetine that affect serotonin levels, and Ford hasn't even tested any of those yet to see what they do to shrimp and other marine organisms.

[Aquatic Toxicology]

What do you get when you combine some xenon, some fluoride, and pressures similar to those found at the center of the Earth? You get an ultra-battery, capable of storing more condensed energy than any other battery ever built.

The material used to make the "battery" is xenon difluoride (XeF₂), a white crystal primarily used to etch silicon conductors. The crystal was placed in a diamond anvil cell, a tiny device that measures only two inches by three inches. The cell uses two tiny diamond anvils (as you might expect, considering its name) to produce incredibly high pressures in tiny, contained spaces.

Normally, the molecules in xenon difluoride stay relatively far apart. The squeezing process the crystals underwent in the diamond anvil cell forced the molecules closer and closer together. At first, the squeezing caused the crystal to become a two-dimensional semiconductor, but then something even more remarkable happened. When the pressure reached a million atmospheres, similar to the pressure found halfway to the center of the Earth, the molecules formed 3D metallic "network structures", which forced all the mechanical energy of the compression process to be stored as chemical energy within the molecular bonds. At a million atmospheres, that's a whole lot of stored energy.

Heading up this research is Washington State chemistry professor Choong-Shik Yoo, who says this "is the most condensed form of energy storage outside of nuclear energy." The possible applications of the material pretty much all include the word "super": superconductors, super-oxidizing materials that can destroy chemical and biological agents, not to mention new fuels and, most obviously, an energy storage device.

[Nature Chemistry]

There's no simple trick to reaching 100 years old, although most experts say it's a mix of luck and taking good care of yourself. Plus, it really helps to have one of the nineteen "longevity" gene groups scientists just discovered.

The experiment considered the genomes of 1,055 centenarians and 1,267 younger controls.The team, led by Paola Sebastiani and Thomas T. Perls of Boston University, zeroed in on particular areas of the genome that varied between the experimental and control groups. They were able to build a genetic model that could predict with 77% accuracy which genomes belonged to the centenarians and which belonged to their younger counterparts. They built the model by locating about 150 cases where a difference in a particular nucleotide in the genetic sequence - known as a single-nucleotide polymorphism - correlated with exceptional longevity.

Sebastiani puts their success in context:

"Seventy-seven percent is very high accuracy for a genetic model. But 23 percent error rate also shows there us a lot that remains to be discovered."

Additionally, the team was able to put ninety percent of the centenarians into one of nineteen different genetic clusters of various combinations of genotypes. Some of the clusters promoted longer survival (naturally enough), while others delayed the onset of disease. Indeed, a surprise for Sebastiani and Perls was the discovery that the centenarians had all the same genes that lead to age-related illnesses as their younger counterparts; they just happened to also possess genes that canceled these diseases out.

Perls explains the significance of this find:

"We have noted in previous work that 90 percent of centenarians are disability-free at the average age of 93. We had long hypothesized that to get to 100 you have to have a relative lack of disease-associated variants. But in this case, we're finding that not to be the case."

As for the super-centenarians, those 110 years old or more, they found that forty percent of this group had three particular gene clusters in common. Even though that's less than half the group, such a correlation provides another useful hint as to which areas of the genome play the biggest role in increased longevity.

Ultimately, Perls advises caution in reading too much into these findings, at least at the moment:

"We're quite a ways away, still, in understanding what pathways are governed by these genes. I look at the complexity of this puzzle and feel very strongly that this will not lead to treatments that will get people to be centenarians.

That said, the 77 percent success rate of their genetic model is way ahead of anything that's been accomplished before, and the team hopes to push forward with further research. This particular study has been going on since 1995 and focused on Caucasians. Perls and Sebastiani say they want to next run similar tests on Japanese centenarians, as Japan is well-known for its unusually large elderly population.

[Science; also check out Gawker's post on this story]

DNA sculpture by Bathsheba Grossman.

We don't know how to cure it, but now we've got a better idea what causes cancer. The disease starts when cells mess up their attempts to repair damage to their DNA.

There's a certain tragic irony to this, as these terrible diseases seem to begin with cells trying to fix the far more minor problem of damage to DNA strands. According to James Haber, Wade Hicks, and Minlee Kim of Brandeis University, cells that are showing the very earliest signs of cancer start to have errors in the DNA replication process. To fix this, the cells use a number or methods to repair the damage, one of which is known as gene conversion.

Gene conversion repairs the break in the DNA strand by using an almost identical sequence from elsewhere in the cell's DNA, providing a template from which the original strand can be reconstructed. Although this was once thought to be a mostly error-free process, the new study actually suggests it leads to a far greater number - about 1,400 times the usual amount - of DNA mutations than would otherwise be expected. Once these mutations affect the various genes that provide the cell's ability to control its own growth, the cell quickly becomes cancerous.

Coauthor James Haber says this theory explains why cells turn cancerous so quickly:

"It has been hard to imagine how cells could accumulate so many mutations in the few generations that they undergo cell division on the way to becoming cancerous. We think that the elevated rate of mutation at sites where DNA has been broken may be an important source of these gene changes."

Wade Hicks builds on this by noting that the mutations are themselves unique, and this could help test the validity of their ideas:

"During repair, mutation rates increase, and the types of mutation during repair are different from normal mutagenesis. It would be interesting to do an in depth analysis of the types of mutations in cancer cells and compare to those we observed in a repair event to see if they match up."

Their examination of gene conversion revealed that the copying of DNA during repair was often interrupted, which presented major complications. Most strikingly, the copying mechanisms would often choose the wrong template when they restarted, choosing an unhelpful sequence that provided little useful information for the strand in need of repair, which naturally created errors and mutations in the repair process. Gene conversion also fails to use another cellular repair system known as "mismatch repair", which is the only way the cell can notice and fix mutations that crop up. As such, gene conversion leaves all mutations in place, hastening their takeover of the cell's DNA.

The researchers say they will next focus on how often these template switches occur and what proteins are involved in the process. The hope is that this will better explain the runaway mutagenesis that leads to cancer and perhaps offer some clue as to how to prevent it from happening in the first place.

The blog Star-Gazy Pie (it's namesake being this whimsically disturbing fish dish from Wales Cornwall) offers up some fun insight into the biology of the tuna—specifically, why that biology makes the tuna so much fun to eat. The piece also explains why certain species of tuna are endangered and how to make sure the tasty tuna you eat was raised in such a way as to ensure that our great-grandchildren will be able to enjoy it, too.

But yeah, have you ever wondered why tuna steaks look like this (top) and say, catfish fillets (bottom) look like this?

DING DING DING: Tuna have more red muscle than other fish in order to fuel their eternal swim (like sharks, tuna literally do not stop swimming). To burn the oxygen required by these hefty piscine muscles, tuna have myoglobin, a type of protein, in their muscles. Myoglobin actually forms the pigments that gives raw "red" meat its color, and is also responsible for making red meat that has been frozen turn brown.

Awesome! Along with that, I also learned that tuna are neither, strictly speaking, cold-blooded OR warm-blooded. Instead, tuna use a network of veins and arteries to trap body heat. They can't regulate their temperature as well as warm-blooded species, but they can stay significantly warmer than the ice cold waters they swim through. Cool stuff.

Learn a trick that makes fabrics temporarily waterproof. Short answer: start wearing them really tight. Eighties leggings tight.

Pour water on a loose handkerchief and it will soak right in. That's not the hanky's fault. It was designed to soak things up, and must be honestly grateful that this time around the liquid it is soaking up is just water.

Stretch the handkerchief, good and tight, over the top of a glass of water, invert the glass, and no water will get through. This handy demonstration proves it. It's obviously the same piece of cloth, so there doesn't seem to be a reason why water can push through it in one position and be corralled by it in another.

But what a difference a flat surface makes. In water, it allows surface tension to come into play. Surface tension is the result of cohesion; the fact that water molecules are attracted to each other. They pull together everywhere, but especially along the surface of the water. This cohesion allows the water to form a kind of skin.

Examples of cohesion and surface tension are everywhere. Everyone has seen droplets of water splattered on floors or tables. The droplets form little balls, usually squished out of shape on the side that's resting on the surface. It's enough of an everyday experience that no one thinks about why, without surface tension, it shouldn't happen. Gravity is pulling down on the water. It should be flattened across the surface of the table like road kill from a steamroller. Instead, part of the drop of water is pushing up, defying gravity. This is because the surface tension forms a membrane that keeps the water together. So instead of looking like a squashed opossum, it forms something like a little water balloon.

Water balloons can burst, and that's where the other part of the hanky's feat of strength comes in. One water droplet will stand up. Add more and more water to it and it deflates and turns into a film. The surface tension can stand up to a certain amount of internal pressure from the water, and after that the cohesive forces can't contain anymore. The skin breaks and the water splooshes out. (That's a technical term. Feynman used it.)

The sploosh is easy to come by if half a glass of water is applied to the surface membrane. The cotton chops up that surface into tiny parts. The tiny threads that make up the fabric make a lot of tiny little surfaces. In order for the water to fall, the water pushing down, and the air pushing up, has to apply enough force to break the membrane. It's easy to apply that force across the entire surface of the glass, the way it would be easy to break a water balloon stretched across an entire cauldron. It gets a lot harder to apply that force to each tiny surface that peeks through the cotton threads.

And so the fabric that absorbs all that lovely blue liquid in personal undergarment commercials stays leak free if it's pulled tight enough. This is a trick that will work with other fabrics, such as ordinary clothes, as well. The problem is, they do have to be pulled tight and flat enough so that none of the water can break rank and flow. Ladies, you will have to tuck all your pointy bits away. Gentlemen, you too.

Via Physics.org and Kitchen Science Experiments.