Human collective behavior can vary from calm to panicked depending on social context. Using videos publicly available online, we study the highly energized collective motion of attendees at heavy metal concerts. We find these extreme social gatherings generate similarly extreme behaviors: a disordered gas-like state called a mosh pit and an ordered vortex-like state called a circle pit. Both phenomena are reproduced in flocking simulations demonstrating that human collective behavior is consistent with the predictions of simplified models.
If you believe in gravity, then you know that if you remove air resistance, a bowling ball and a feather will fall at the same rate. But seeing it actually happen, in the world’s largest vacuum chamber (122 feet high, 100 feet in diameter), is still a bit shocking.
In the late 1500s, Galileo was the first to show that the acceleration due to the Earth’s gravity was independent of mass with his experiment at the Leaning Tower of Pisa, but that pesky air resistance caused some problems. At the end of the Apollo 15 mission, astronaut David Scott dropped a hammer and a feather in the vacuum on the surface of the Moon:
Dubbed the compact fusion reactor (CFR), the device is conceptually safer, cleaner and more powerful than much larger, current nuclear systems that rely on fission, the process of splitting atoms to release energy. Crucially, by being “compact,” Lockheed believes its scalable concept will also be small and practical enough for applications ranging from interplanetary spacecraft and commercial ships to city power stations. It may even revive the concept of large, nuclear-powered aircraft that virtually never require refueling-ideas of which were largely abandoned more than 50 years ago because of the dangers and complexities involved with nuclear fission reactors.
The key difference in Lockheed’s approach seems to be the configuration of the magnetic field containing the reaction:
The CFR will avoid these issues by tackling plasma confinement in a radically different way. Instead of constraining the plasma within tubular rings, a series of superconducting coils will generate a new magnetic-field geometry in which the plasma is held within the broader confines of the entire reaction chamber. Superconducting magnets within the coils will generate a magnetic field around the outer border of the chamber. “So for us, instead of a bike tire expanding into air, we have something more like a tube that expands into an ever-stronger wall,” McGuire says. The system is therefore regulated by a self-tuning feedback mechanism, whereby the farther out the plasma goes, the stronger the magnetic field pushes back to contain it. The CFR is expected to have a beta limit ratio of one. “We should be able to go to 100% or beyond,” he adds.
This week, Lockheed Martin supposedly managed to achieve a “breakthrough” in nuclear fusion that has gotten a lot of media attention. As Charles Seife points out, it did so “without having built a prototype device that, you know, fuses things on an appreciable scale. It’s a stunning assertion, even by fusion-research standards. But a quick look at the defense contractor’s ambitious plan-a working reactor in five years-already shows the dream fraying around the edges. A year and a half ago, the company promised that fusion was four years away, meaning that the schedule is already slipping. Negative one years of progress in 20 months is, sadly, business as usual for fusion. At this rate, it’ll take Lockheed Martin at least a decade before the natural endpoint: desperately spinning victory out of an underwhelming result generated by a machine whose performance comes nowhere near predictions-and which brings us no closer to actually generating energy from a fusion reaction.”
It’s a neat piece of science art, and it also tells us something interesting. The arrows show us that the force on the skateboard is constantly changing, both in magnitude as well as in direction. Now the force of gravity obviously isn’t changing, so the reason that these force arrows are shrinking and growing and tumbling around is that the skater is changing how their feet pushes and pulls against the board. By applying a variable force that changes both in strength and direction, they’re steering the board.
Today’s brain-melter: Every Insanely Mystifying Paradox in Physics. It’s all there, from the Greisen-Zatsepin-Kuzmin limit to quantum immortality to, of course, the tachyonic antitelephone.
A tachyonic antitelephone is a hypothetical device in theoretical physics that could be used to send signals into one’s own past. Albert Einstein in 1907 presented a thought experiment of how faster-than-light signals can lead to a paradox of causality, which was described by Einstein and Arnold Sommerfeld in 1910 as a means “to telegraph into the past”.
If you emerge with your brain intact, at the very least, you’ll have lost a couple of hours to the list.
With colleagues, Ulm began analyzing cities the way you’d analyze a material, looking at factors such as the arrangement of buildings, each building’s center of mass, and how they’re ordered around each other. They concluded that cities could be grouped into categories: Boston’s structure, for example, looks a lot like an “amorphous liquid.” Seattle is another liquid, and so is Los Angeles. Chicago, which was designed on a grid, looks like glass, he says; New York resembles a highly ordered crystal.
I love this. It’s like Jane Jacobs + the materials science research I did in college.
So far, Ulm says, the work has two potential applications. First, it could help predict and mitigate urban heat island effects, the fact that cities tend to be several degrees warmer than their surrounding areas-a phenomenon that has a major impact on energy use. (His research on how this relates to structure is currently undergoing peer review.) Second, he says that cities’ molecular order (or disorder) may also affect their vulnerability to the kinds of catastrophic weather events that are becoming more frequent thanks to climate change.
Scientists already know that magnetic north shifts. Once every few hundred thousand years the magnetic poles flip so that a compass would point south instead of north. While changes in magnetic field strength are part of this normal flipping cycle, data from Swarm have shown the field is starting to weaken faster than in the past. Previously, researchers estimated the field was weakening about 5 percent per century, but the new data revealed the field is actually weakening at 5 percent per decade, or 10 times faster than thought. As such, rather than the full flip occurring in about 2,000 years, as was predicted, the new data suggest it could happen sooner.
You can read up on geomagnetic reversals on Wikipedia. A short sampling:
These periods [of polarity] are called chrons. The time spans of chrons are randomly distributed with most being between 0.1 and 1 million years with an average of 450,000 years. Most reversals are estimated to take between 1,000 and 10,000 years. The latest one, the Brunhes-Matuyama reversal, occurred 780,000 years ago. A brief complete reversal, known as the Laschamp event, occurred only 41,000 years ago during the last glacial period. That reversal lasted only about 440 years with the actual change of polarity lasting around 250 years. During this change the strength of the magnetic field dropped to 5% of its present strength.
Great post on the Fermi Paradox, aka if there are so many potential intelligent civilizations out there in the universe (possibly 10 quadrillion of them), why haven’t we heard from anyone?
Possibility 5) There’s only one instance of higher-intelligent life — a “superpredator” civilization (like humans are here on Earth) — who is far more advanced than everyone else and keeps it that way by exterminating any intelligent civilization once they get past a certain level. This would suck. The way it might work is that it’s an inefficient use of resources to exterminate all emerging intelligences, maybe because most die out on their own. But past a certain point, the super beings make their move — because to them, an emerging intelligent species becomes like a virus as it starts to grow and spread. This theory suggests that whoever was the first in the galaxy to reach intelligence won, and now no one else has a chance. This would explain the lack of activity out there because it would keep the number of super-intelligent civilizations to just one.
Update: If you prefer to watch engaging videos instead of reading text, here’s six minutes on the Fermi Paradox:
We can fit the orbits of four gas giants in the habitable zone (in 3:2 resonances). Each of those can have up to five potentially habitable moons. Plus, the orbit of each gas giant can also fit an Earth-sized planet both 60 degrees in front and 60 degrees behind the giant planet’s orbit (on Trojan orbits). Or each could be a binary Earth! What is nice about this setup is that the worlds can have any size in our chosen range. It doesn’t matter for the stability.
Let’s add it up. One gas giant per orbit. Five large moons per gas giant. Plus, two binary Earths per orbit. That makes 9 habitable worlds per orbit. We have four orbits in the habitable zone. That makes 36 habitable worlds in this system!
Historic observations as far back as the late 1800s [2] gauged this turbulent spot to span about 41 000 kilometres at its widest point — wide enough to fit three Earths comfortably side by side. In 1979 and 1980 the NASA Voyager fly-bys measured the spot at a shrunken 23 335 kilometres across. Now, Hubble has spied this feature to be smaller than ever before.
“Recent Hubble Space Telescope observations confirm that the spot is now just under 16 500 kilometres across, the smallest diameter we’ve ever measured,” said Amy Simon of NASA’s Goddard Space Flight Center in Maryland, USA.
Amateur observations starting in 2012 revealed a noticeable increase in the spot’s shrinkage rate. The spot’s “waistline” is getting smaller by just under 1000 kilometres per year. The cause of this shrinkage is not yet known.
Clive Thompson recently saw the moons of Jupiter with his own eyes and has a moment.
I saw one huge, bright dot, with three other tiny pinpoints of light nearby, all lined up in a row (just like the image at the top of this story). Holy moses, I realized; that’s no star. That’s Jupiter! And those are the moons of Jupiter!
I’m a science journalist and a space buff, and I grew up oohing and aahing over the pictures of Jupiter sent back by various NASA space probes. But I’d never owned a telescope, and never done much stargazing other than looking up in the night unaided. In my 45 years I’d never directly observed Jupiter and its moons myself.
So I freaked out. In a good way! It was a curiously intense existential moment.
For my birthday when I was seven or eight, my dad bought me a telescope. (It was a Jason telescope; didn’t everyone have a telescope named after them?) We lived in the country in the middle of nowhere where it was nice and dark, so over the next few years, we looked at all sorts of celestial objects through that telescope. Craters on the Moon, the moons of Jupiter, Mars, and even sunspots on the Sun with the aid of some filters. But the thing that really got me, that provided me with my own version of Thompson’s “curiously intense existential moment”, was seeing the rings of Saturn through a telescope.
We had heard from PBS’s Jack Horkheimer, the Star Hustler, that Saturn and its rings would be visible and he showed pictures of what it would look like, something like this:
But seeing that with your own eyes through a telescope was a different thing entirely. Those tiny blurry rings, visible from millions of miles away. What a thrill! It’s one of my favorite memories.
The elements located in the upper reaches of the periodic table are notable for their short half-lives, the amount of time during which half the mass of an element will decay into lighter elements (and other stuff). For instance, the longest lived isotope of fermium (#100) has a half-life of just over 100 days. More typical is bohrium (#107)…its half-life is only 61 seconds. The elements with the highest numbers have half-lives measured in milliseconds…the half-life of ununoctium (#118) is only 0.89 milliseconds.
So why do chemists and physicists keep looking for heavier and heavier elements if they are increasingly short-lived (and therefore not that useful)? Because they suspect some heavier elements will be relatively stable. Let’s take a journey to the picturesque island of stability.
In nuclear physics, the island of stability is a set of as-yet undiscovered heavier isotopes of transuranium elements which are theorized to be much more stable than some of those closer in atomic number to uranium. Specifically, they are expected to have radioactive decay half-lives of minutes or days, with “some optimists” expecting half-lives of millions of years.
Ruh-roh. Remember the news last month about the detection of gravitational waves would have allowed scientists to see all the way back to the Big Bang? Well, that result may be in jeopardy. The problem? Dust on the lens. Well, not on the lens exactly:
An imprint left on ancient cosmic light that was attributed to ripples in spacetime — and hailed by some as the discovery of the century — may have been caused by ashes from an exploding star.
In the most extreme scenario, the finding could suggest that what looked like a groundbreaking result was only a false alarm. Another possibility is that the stellar ashes could help bring the result in line with other cosmic observations. We should know which it is later this year, when researchers report new results from the European Space Agency’s Planck satellite.
You may also remember the video of physicist Andrei Linde being told about the result, which seemed to confirm a theory that had been his life’s work. I don’t think I want to see the video of Linde being told of this stellar ashes business. Although Linde is more than aware that this is how science works…you have to go where observation takes you. (via @daveg)
The US Navy is working on technology to convert seawater into fuel to power unmodified combustion engines. They recently tested the fuel (successfully!) in a replica P-51 and hope to make it commerically viable.
Navy researchers at the U.S. Naval Research Laboratory (NRL), Materials Science and Technology Division, demonstrated proof-of-concept of novel NRL technologies developed for the recovery of carbon dioxide (CO2) and hydrogen (H2) from seawater and conversion to a liquid hydrocarbon fuel.
Fueled by a liquid hydrocarbon — a component of NRL’s novel gas-to-liquid (GTL) process that uses CO2 and H2 as feedstock — the research team demonstrated sustained flight of a radio-controlled (RC) P-51 replica of the legendary Red Tail Squadron, powered by an off-the-shelf (OTS) and unmodified two-stroke internal combustion engine.
Using an innovative and proprietary NRL electrolytic cation exchange module (E-CEM), both dissolved and bound CO2 are removed from seawater at 92 percent efficiency by re-equilibrating carbonate and bicarbonate to CO2 and simultaneously producing H2. The gases are then converted to liquid hydrocarbons by a metal catalyst in a reactor system.
“In close collaboration with the Office of Naval Research P38 Naval Reserve program, NRL has developed a game-changing technology for extracting, simultaneously, CO2 and H2 from seawater,” said Dr. Heather Willauer, NRL research chemist. “This is the first time technology of this nature has been demonstrated with the potential for transition, from the laboratory, to full-scale commercial implementation.”
I love this video. Love love love. Chao-Lin Kuo surprises Andrei Linde and his wife with the news that gravitational waves were detected, proving Linde’s theory of an inflationary universe.
Update: Many people have asked what Kuo is saying to Linde on the doorstep. Let’s start with “5 sigma”. The statistical measure of standard deviation (represented by the Greek letter sigma) is an indication of how sure scientists are of their results. (It has a more technical meaning than that, but we’re not taking a statistics course here.) A “5 sigma” level of standard deviation indicates 99.99994% certainty of the result…or a 0.00006% chance of a statistical fluctuation. That’s a 1 in 3.5 million chance. This is the standard particle physicists use for declaring the discovery of a new particle.
The “point-2” is a bit more difficult to explain. Sean Carroll definesr as “the ratio of gravitational waves to density perturbations” as measured by the BICEP2 experiment, the telescope used to make these measurements. What BICEP2 found was an r value of 0.2:
According to the theory of Inflation, the Universe underwent a violent and rapid expansion at only 10^-35 seconds after the Big Bang, making the horizon size much larger, and allowing the space to become flat. Confirmation of Inflation would be an amazing feat in observational Cosmology. Inflation during the first moments of time produced a Cosmic Gravitational-Wave Background (CGB), which in turn imprinted a faint but unique signature in the polarization of the CMB. Since gravitational waves are by nature tensor fluctuations, the polarization signature that the CGB stamps onto the CMB has a curl component (called “B-mode” polarization). In contrast, scalar density fluctuations at the surface of last scattering only contribute a curl-free (or “E-mode”) polarization component to the CMB which was first detected by the DASI experiment at the South Pole.
The big deal with BICEP2 is the ability to accurately detect the B-mode polarization for the first time. r is the ratio between these two different types of polarization, E-mode & B-mode. Any result for r > 0 indicates the presence of B-mode polarization, which, according to the theory, was caused by gravitational waves at the time of inflation. So, that’s basically what Kuo is on about.
We didn’t do any re-takes. The goal was for it to be a really natural thing. We did ask him to tell us what he was feeling and what the research means. But what you see in the video is just very off-the-cuff and raw. Part of it was, we went there not even knowing if we’d be able to use or keep anything that we did. It was just as likely that he would have been emotional in a way that he didn’t want us to share, or that his wife didn’t. So we went into it with no guarantee-we knew we’d be able to shoot, but didn’t know if we’d be able use it. So we’re thankful that they agreed to let us do that.
Finally a viral video that’s genuine and not staged or reality TV’d.
This is huge: physicists have detected gravitational waves that harken back to the beginning of the universe, when it was “a trillionth of a trillionth of a trillionth of a second old”. The discovery goes a long way toward proving the inflation theory of how the universe formed.
Reaching back across 13.8 billion years to the first sliver of cosmic time with telescopes at the South Pole, a team of astronomers led by John M. Kovac of the Harvard-Smithsonian Center for Astrophysics detected ripples in the fabric of space-time — so-called gravitational waves — the signature of a universe being wrenched violently apart when it was roughly a trillionth of a trillionth of a trillionth of a second old. They are the long-sought smoking-gun evidence of inflation, proof, Dr. Kovac and his colleagues say, that Dr. Guth was correct.
Inflation has been the workhorse of cosmology for 35 years, though many, including Dr. Guth, wondered whether it could ever be proved.
If corroborated, Dr. Kovac’s work will stand as a landmark in science comparable to the recent discovery of dark energy pushing the universe apart, or of the Big Bang itself. It would open vast realms of time and space and energy to science and speculation.
Confirming inflation would mean that the universe we see, extending 14 billion light-years in space with its hundreds of billions of galaxies, is only an infinitesimal patch in a larger cosmos whose extent, architecture and fate are unknowable. Moreover, beyond our own universe there might be an endless number of other universes bubbling into frothy eternity, like a pot of pasta water boiling over.
If the results are confirmed, Guth will undoubtably win the Nobel in Physics for this soon. Phil Plait at Bad Astronomy has more on the discovery.
Update:This video of Chao-Lin Kuo (one of the principle investigators on this experiment) telling physicist Andrei Linde (a leading inflation theorist) about the result is just outstanding.
The problem comes in when the astronomers looked at things that might mimic the signal they were looking for. For example, dust (long, complex carbon-molecules that are much like fireplace soot) floating in space can look very much like the signal BICEP2 was seeking. The astronomers knew this, and used data from the ESA mission Planck to investigate it. Planck measured the amount of dust lying along the direction BICEP2 was looking, and the astronomers concluded the amount of dust in their line-of-sight was low. The signal they saw, therefore, must be from inflation.
And here’s the bummer part: They were using preliminary Planck data. When better data from Planck were released, the astronomers used that, and found that the amount of galactic dust in their view was much higher than they previously thought. That weakens their case considerably.
I don’t want to see the video of someone telling Linde “whoops!”
Last year (spoilers!), CERN confirmed the discovery of the Higgs boson. Physicist-turned-filmmaker Mark Levinson has made a film about the search for the so-called God Particle. Particle Fever follows a group of scientists through the process of discovery and the construction of the mega-machine that discovered the Higgs, the Large Hadron Collider. Here’s a trailer:
Two additional data points: the movie is holding a 95% rating on Rotten Tomatoes and legendary sound designer and editor Walter Murch edited the film. Particle Fever is showing at Film Forum in New York until March 20. (thx, james)
Ok quiet down, we’re going to science right now. (That’s right, I verbed “science”.) If you take a long chain of beads, put them in a jar, and then throw one end of the bead chain out, the rest of the beads will follow *and* this bead fountain will magically rise up into the air over the lip of the glass.
As the guy’s face in the video shows, this is deeply perplexing. For an explanation, slow motion video, and a demonstration of a preposterously high chain fountain, check this video from the NY Times out:
The fountain, said Dr. Biggins, which he had never seen before the video, was “surprisingly complicated.” The chain was moving faster than gravity would account for, and they realized that something had to be pushing the chain up from the container in which it was held.
A key to understanding the phenomenon, Dr. Biggins said, is that mathematically, a chain can be thought of as a series of connected rods.
When you pick up one end of a rod, he said, two things happen. One end goes up, and the other end goes down, or tries to. But if the downward force is stopped by the pile of chain beneath it, there is a kind of kickback, and the rod, or link, is pushed upward. That is what makes the chain rise.
Raffi Khatchadourian’s long piece on the construction of the International Thermonuclear Experimental Reactor (ITER) is at once fascinating (for science reasons) and depressing (for political/bureaucratic reasons). Fusion reactors hold incredible promise:
But if it is truly possible to bottle up a star, and to do so economically, the technology could solve the world’s energy problems for the next thirty million years, and help save the planet from environmental catastrophe. Hydrogen, a primordial element, is the most abundant atom in the universe, a potential fuel that poses little risk of scarcity. Eventually, physicists hope, commercial reactors modelled on iter will be built, too-generating terawatts of power with no carbon, virtually no pollution, and scant radioactive waste. The reactor would run on no more than seawater and lithium. It would never melt down. It would realize a yearning, as old as the story of Prometheus, to bring the light of the heavens to Earth, and bend it to humanity’s will. iter, in Latin, means “the way.”
But ITER is a collaborative effort between 35 different countries, which means the project is political, slow, and expensive.
For the machine’s creators, this process-sparking and controlling a self-sustaining synthetic star-will be the culmination of decades of preparation, billions of dollars’ worth of investment, and immeasurable ingenuity, misdirection, recalibration, infighting, heartache, and ridicule. Few engineering feats can compare, in scale, in technical complexity, in ambition or hubris. Even the iter organization, a makeshift scientific United Nations, assembled eight years ago to construct the machine, is unprecedented. Thirty-five countries, representing more than half the world’s population, are invested in the project, which is so complex to finance that it requires its own currency: the iter Unit of Account.
No one knows iter’s true cost, which may be incalculable, but estimates have been rising steadily, and a conservative figure rests at twenty billion dollars — a sum that makes iter the most expensive scientific instrument on Earth.
I wonder what the project would look like if, say, Google or Apple were to take the reins instead. In that context, it’s only $20 billion to build a tiny Sun on the Earth. Facebook just paid $19 billion for WhatsApp, Apple has a whopping $158.8 billion in cash, and Google & Microsoft both have more than $50 billion in cash. Google in particular, which is making a self-driving car and has been buying up robots by the company-full recently, might want their own tiny star.
But back to reality, the circumstances of ITER’s international construction consortium reminded me of the building of The Machine in Carl Sagan’s Contact. In the book, the countries of the world work together to make a machine of unknown function from plans beamed to them from an alien intelligence, which results in the development of several new lucrative life-enhancing technologies and generally unites humanity. In Sagan’s view, that’s the power of science. Hopefully the ITER can work through its difficulties to achieve something similar.
First of all, not all of the Earth would simply be sucked into the black hole. When the matter near the black hole begins to fall into the black hole, it will be compressed to a very high density that will cause it to be heated to very high temperatures. These high temperatures will cause gamma rays, X-rays, and other radiation to heat up the other matter falling in to the black hole. The net effect will be that there will be a strong outward pressure on the outer layers of the Earth that will first slow down their fall and will eventually ionize and push the outer layers away from the black hole. So some inner portion of the core will fall into the black hole, but the outer layers, including the crust and all of us, would be vaporized to a high temperature plasma and blown into space.
This would be a gigantic explosion — a significant fraction of the rest of the mass of the Earth matter that actually fell into the black hole will be converted into energy.
FYI, that marble-sized black hole would have about the same mass as the Earth. Not that they exist, mind you. Maybe, maybe not. Blackish holes? Dark grey holes? Anyway, really heavy.
In 1976, legendary cosmologist and astronomer Carl Sagan tried to recruit a 17-year-old Neil deGrasse Tyson to Cornell University. In April of that year, Tyson wrote Sagan a letter informing him of his intention to enroll at Harvard instead:
The Viking Missions referred to in the letter were the two probes sent to Mars in the mid-1970s.
Tyson occupies a role in today’s society similar to Sagan’s in the 1980s as an unofficial public spokesman of the wonderous world of science. Tyson is even hosting an updated version of Sagan’s seminal Cosmos series for Fox, which debuts on March 9th. Here’s a trailer:
In a short video from The Atlantic, science writer Philip Ball explains why Isaac Newton picked ROYGBIV (red, orange, yellow, green, blue, indigo, and violet) for the colors of the spectrum and not 3 or 6 or even 16 other possible colors.
Newton was the first to demonstrate through his famous prism experiments that color is intrinsic to light. As part of those experiments, he also divvied up the spectrum in his own idiosyncratic way, giving us ROYGBIV. Why indigo? Why violet? We don’t really know why Newton decided there were two distinct types of purple, but we do know he thought there should be seven fundamental colors.
It will take it just 6 months to burn up its oxygen. Again, when there’s not enough oxygen being fused to generate energy to balance the pressure of gravitational contraction, the star begins to shrink, almost doubling the temperature, tripling the density, and causing the silicon (which was produced by the oxygen fusion) to begin fusing, in its own complicated sequence involving the alpha process, with the end result of nickel-56 (which radioactively decays into cobalt-56 and iron-56). This, as before, balances against the gravitational pressure and returns the star to equilibrium.
And now it will take merely 1 day to burn up its silicon. Finally, when there’s not enough silicon being fused to generate energy to balance the pressure of gravitational contraction, the star begins to shrink.
This time, however, the core of the star is mostly nickel and iron, and they cannot ordinarily be fused into heavier elements, so as the star shrinks and the temperature and density increase, there is no nuclear fusion ignition of the nickel and iron to counteract the contraction. Here the limit of pressure and density is the electron degeneracy pressure, which is the resistance of electrons being forced to occupy the same energy states, which they can’t.
Most physicists foolhardy enough to write a paper claiming that “there are no black holes” — at least not in the sense we usually imagine — would probably be dismissed as cranks. But when the call to redefine these cosmic crunchers comes from Stephen Hawking, it’s worth taking notice. In a paper posted online, the physicist, based at the University of Cambridge, UK, and one of the creators of modern black-hole theory, does away with the notion of an event horizon, the invisible boundary thought to shroud every black hole, beyond which nothing, not even light, can escape.
In its stead, Hawking’s radical proposal is a much more benign “apparent horizon”, which only temporarily holds matter and energy prisoner before eventually releasing them, albeit in a more garbled form.
A supernova erupted recently1 in galaxy M82, a mere 11.4 million light years away from Earth, which means that it was close enough to be discovered by someone using an ordinary telescope in London and may be visible with binoculars sometime in the next two weeks.
M82’s proximity means that there are many existing images of it, pre-explosion, including some from the Hubble Space Telescope. Cao and others will comb through those images, looking for what lay in the region before. It will not be easy: M82 is filled with dust. But the light the supernova shines on the dust could teach astronomers something about the host galaxy, too. One team is already looking for radioactive elements, such as nickel, that theories predict form in such supernova, says Shri Kulkarni, an astronomer at California Institute of Technology. “Dust has its own charms.”
Ok, it didn’t erupt recently. M82 is 11.4 million light years away, so the supernova happened 11.4 million years ago and the light is just now reaching us here on Earth.↩
Think about this … an ordinary fox can stalk a mole, mouse, vole or shrew from a distance of 25 feet, which means its food is making a barely audible rustling sound, hiding almost two car lengths away. And yet our fox hurls itself into the air — in an arc determined by the fox, the speed and trajectory of the scurrying mouse, any breezes, the thickness of the ground cover, the depth of the snow — and somehow (how? how?), it can land straight on top of the mouse, pinning it with its forepaws or grabbing the mouse’s head with its teeth.
Look at those ears and how the fox moves his head around to zero in on the mouse’s location…reminds me of the pre-radar acoustic location devices (sometimes called war tubas) used in the early 20th century to detect approaching aircraft:
Let slip the tubas of war! Aaaaanyway, as the acoustic location device gave way to the more effective radar, so too is the fox more successful at hunting when he is pointed northeast — a kind of magnetic radar, if you will. Fascinating.
Here, three implementations of Internet searches for time travelers are described, all seeking a prescient mention of information not previously available. The first search covered prescient content placed on the Internet, highlighted by a comprehensive search for specific terms in tweets on Twitter. The second search examined prescient inquiries submitted to a search engine, highlighted by a comprehensive search for specific search terms submitted to a popular astronomy web site. The third search involved a request for a direct Internet communication, either by email or tweet, pre-dating to the time of the inquiry. Given practical verifiability concerns, only time travelers from the future were investigated.
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