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If you drop a bunch of neodymium magnets down through a thick-walled copper pipe, an effect called eddy current braking will slow the magnets’ fall even though there’s no direct magnetic attraction between the copper and the magnets.
Science! (via make)
At the beginning of this video, Ramesh Raskar, associate professor at the MIT Media Lab, announces calmly:
We have built a virtual slow-motion camera where we can see photons, or light particles, moving through space.
Yeah, no biggie.
Rumor has it that the LHC at CERN has found the Higgs boson. The news runs contrary to some earlier speculation.
The teams are sworn to secrecy, but various physics blogs, and the canteens at Cern, are alive with talk of a possible sighting of the Higgs, and with a mass inline with what many physicists would expect.
Since the Higgs’ nickname is the God particle, does this count as the Second Coming? (@gavinpurcell)
From Sean Carroll at Cosmic Variance, a list of facts and very strong opinions about the nature of time.
4. You live in the past. About 80 milliseconds in the past, to be precise. Use one hand to touch your nose, and the other to touch one of your feet, at exactly the same time. You will experience them as simultaneous acts. But that’s mysterious - clearly it takes more time for the signal to travel up your nerves from your feet to your brain than from your nose. The reconciliation is simple: our conscious experience takes time to assemble, and your brain waits for all the relevant input before it experiences the “now.” Experiments have shown that the lag between things happening and us experiencing them is about 80 milliseconds.
5. Your memory isn’t as good as you think. When you remember an event in the past, your brain uses a very similar technique to imagining the future. The process is less like “replaying a video” than “putting on a play from a script.” If the script is wrong for whatever reason, you can have a false memory that is just as vivid as a true one. Eyewitness testimony, it turns out, is one of the least reliable forms of evidence allowed into courtrooms.
One of the many reasons to love the wooden water towers found on the tops of NYC buildings is that the structures themselves reveal the math behind how they work.
The distance between the metal bands holding the cylindrical structure together decreases from top to bottom because the pressure the water exerts increases with depth. The top band only needs to fight against the water at the very top of the tower but the bottom bands have to hold the entire volume from bursting out.
What the what? This video gives a little more explanation into the effect at work here (superconductivity + quantum trapping of the magnetic field in quantum flux tubes) and an awesome demonstration of a crude rail system. You can almost hear your tiny mind explode when the “train” goes upside-down.
Wingardium Leviosa! (via stellar)
Why do riderless bicycles not fall over? Science Friday looks at the science behind bike self-steering.
(via robottke!)
Physicists at CERN believe they have observed neutrinos moving at speeds faster than the speed of light, a feat previously assumed to be impossible.
Thousands of experiments have been undertaken to measure it ever more precisely, and no result has ever spotted a particle breaking the limit.
But Dr Ereditato and his colleagues have been carrying out an experiment for the last three years that seems to suggest neutrinos have done just that.
Neutrinos come in a number of types, and have recently been seen to switch spontaneously from one type to another.
The team prepares a beam of just one type, muon neutrinos, sending them from Cern to an underground laboratory at Gran Sasso in Italy to see how many show up as a different type, tau neutrinos.
In the course of doing the experiments, the researchers noticed that the particles showed up 60 billionths of a second sooner than light would over the same distance.
This is a tiny fractional change, but one that occurs consistently.
The team measured the travel times of neutrino bunches some 15,000 times, and have reached a level of statistical significance that in scientific circles would count as a formal discovery.
If true, saying this is a significant discovery is a doubly significant understatement.
Most of the possible masses for the Higgs boson (aka the God particle) have been eliminated with at a 95% confidence level by physicists at CERN. They’re checking the other masses and will likely have an answer one way or the other in December.
“We are now entering a very exciting phase in the hunt for the Higgs boson,” Sharma said. “If the Higgs boson exists between 114-145 GeV, we should start seeing statistically significant excesses over estimated backgrounds, and if it does not then we hope to rule it out over the entire mass range. One way or the other we are poised for a major discovery, likely by the end of this year.”
(via @daveg)
The giants of physics (and Morgan Freeman, who can be a giant of anything he wants) explain quantum mechanics using relatively simple terms and autotune.
(via devour)
Mesmerizing video of a series of pendulums moving in an out of sync with each other until at the end…well, I won’t spoil it.
(thx, john)
NASA’s just finished an impressive experiment designed to test Einstein’s general theory of relativity — specifically the “mass distorts spacetime” part:
Put a spinning gyroscope into orbit around the Earth, with the spin axis pointed toward some distant star as a fixed reference point. Free from external forces, the gyroscope’s axis should continue pointing at the star—forever. But if space is twisted, the direction of the gyroscope’s axis should drift over time. By noting this change in direction relative to the star, the twists of space-time could be measured.
Gravity Probe B’s experiment was 47 years in the making, helped spawn 100 PhD theses, and required the invention of 13 brand-new technologies, including a “drag-free satellite.” The four gyroscopes in GP-B are “the most perfect spheres ever made by humans… If the gyroscopes weren’t so spherical, their spin axes would wobble even without the effects of relativity.”
NASA finished collecting the data in 2005; now they’ve crunched the numbers. And yes, Einstein was right. The gyroscopes wobble in just the way general relativity predicts.
The first and most famous empirical experiment testing Einstein’s theory was performed in 1919 by Arthur Eddington during a full solar eclipse. Photographs showed that the sun’s mass caused starlight to bend around it.
(Image by James Overduin, Pancho Eekels, and Bob Kahn via NASA.)
Scientists at Fermilab have found a “suspicious bump” in their data from the Tevatron that may indicate the discovery of a new particle (not the Higgs boson) or a new force of nature or a mistake.
“Nobody knows what this is,” said Christopher Hill, a theorist at Fermilab who was not part of the team. “If it is real, it would be the most significant discovery in physics in half a century.”
We won’t have to wait too long to see if the bump is real…the LHC will reveal all soon.
I haven’t been keeping up with the Japan nuclear power plant situation as much as I want, but I wanted to pass along a few interesting articles. Over at Boing Boing, Maggie Koerth-Baker wrote a widely linked piece about how nuclear power plants work:
For the vast majority of people, nuclear power is a black box technology. Radioactive stuff goes in. Electricity (and nuclear waste) comes out. Somewhere in there, we’re aware that explosions and meltdowns can happen. Ninety-nine percent of the time, that set of information is enough to get by on. But, then, an emergency like this happens and, suddenly, keeping up-to-date on the news feels like you’ve walked in on the middle of a movie. Nobody pauses to catch you up on all the stuff you missed.
As I write this, it’s still not clear how bad, or how big, the problems at the Fukushima Daiichi power plant will be. I don’t know enough to speculate on that. I’m not sure anyone does. But I can give you a clearer picture of what’s inside the black box. That way, whatever happens at Fukushima, you’ll understand why it’s happening, and what it means.
MrReid, a physics teacher, writes about the situation at Fukushima:
Even with the release of steam, the pressure and temperature inside Unit 1 continued to increase. The high temperatures inside the reactor caused the protective zirconium cladding on the uranium fuel rods to react with steam inside the reactor to form zirconium oxide and hydrogen. This hydrogen leaked into the building that surrounded the reactor and ignited, damaging the surrounding building but without damaging the reactor vessel itself. Because the reactor vessel has not been compromised, the release of radiation should be minimal. It appears that a very similar situation has occurred at Unit 3 and that hydrogen is again responsible for the explosion seen there.
And this piece is a more meta take on the situation, What the Media Doesn’t Get About Meltdowns.
Of immediate concern is the prospect of a so-called “meltdown” at one or more of the Japanese reactors. But part of the problem in understanding the potential dangers is continued indiscriminate use, by experts and the media, of this inherently frightening term without explanation or perspective. There are varying degrees of melting or meltdown of the nuclear fuel rods in a given reactor; but there are also multiple safety systems, or containment barriers, in a given plant’s design that are intended to keep radioactive materials from escaping into the general environment in the event of a partial or complete meltdown of the reactor core. Finally, there are the steps taken by a plant’s operators to try to bring the nuclear emergency under control before these containment barriers are breached.
From physicist John Baez, a history of the major disasters that happened to the Earth: the Big Splat, the Late Heavy Bombardment, the Oxygen Catastrophe, and the Snowball Earth. The Big Splat is believed to have formed the Moon:
In 2004, the astrophysicist Robin Canup, at the Southwest Research Institute in Texas, published some remarkable computer simulations of the Big Splat. To get a moon like ours to form — instead of one too rich in iron, or too small, or wrong in other respects — she had to choose the right initial conditions. She found it best to assume Theia is slightly more massive than Mars: between 10% and 15% of the Earth’s mass. It should also start out moving slowly towards the Earth, and strike the Earth at a glancing angle.
The result is a very bad day. Theia hits the Earth and shears off a large chunk, forming a trail of shattered, molten or vaporized rock that arcs off into space. Within an hour, half the Earth’s surface is red-hot, and the trail of debris stretches almost 4 Earth radii into space. After 3 to 5 hours, the iron core of Theia and most of the the debris comes crashing back down. The Earth’s entire crust and outer mantle melts. At this point, a quarter of Theia has actually vaporized!
After a day, the material that has not fallen back down has formed a ring of debris orbiting the Earth. But such a ring would not be stable: within a century, it would collect to form the Moon we know and love. Meanwhile, Theia’s iron core would sink down to the center of the Earth.
Over at Boing Boing, Lee Billings has an interview with Greg Laughlin, an astrophysicist who recently came up with an equation for estimating the value of planets, a sort of Drake equation for cosmic economics.
This equation’s initial purpose, he wrote, was to put meaningful prices on the terrestrial exoplanets that Kepler was bound to discover. But he soon found it could be used equally well to place any planet-even our own-in a context that was simultaneously cosmic and commercial. In essence, you feed Laughlin’s equation some key parameters — a planet’s mass, its estimated temperature, and the age, type, and apparent brightness of its star — and out pops a number that should, Laughlin says, equate to cold, hard cash.
At the time, the exoplanet Gliese 581 c was thought to be the most Earth-like world known beyond our solar system. The equation said it was worth a measly $160. Mars fared better, priced at $14,000. And Earth? Our planet’s value emerged as nearly 5 quadrillion dollars. That’s about 100 times Earth’s yearly GDP, and perhaps, Laughlin thought, not a bad ballpark estimate for the total economic value of our world and the technological civilization it supports.
Science magazine has named their top scientific breakthroughs of 2010 and the insights of the decade. The quantum paddle deservedly took the top spot:
“This year’s Breakthrough of the Year represents the first time that scientists have demonstrated quantum effects in the motion of a human-made object,” said Adrian Cho, a news writer for Science. “On a conceptual level that’s cool because it extends quantum mechanics into a whole new realm. On a practical level, it opens up a variety of possibilities ranging from new experiments that meld quantum control over light, electrical currents and motion to, perhaps someday, tests of the bounds of quantum mechanics and our sense of reality.”
Cosmologists have discovered evidence that our universe has been “bruised” by collisions with other universes.
Today, another group says they’ve found something else in the echo of the Big Bang. These guys start with a different model of the universe called eternal inflation. In this way of thinking, the universe we see is merely a bubble in a much larger cosmos. This cosmos is filled with other bubbles, all of which are other universes where the laws of physics may be dramatically different to ours.
The findings are currently difficult to reproduce, but with better data on the way, scientists are hoping to get to the bottom of the matter in the next few years.
Under certain circumstances, you can mix liquids of different colors, then unmix them, and not violate the second law of thermodynamics.
(via fine structure)
By smashing together lead ions instead of protons, researchers at the Large Hadron Collider have produced a “mini-Big Bang”.
The collisions obtained were able to generate the highest temperatures and densities ever produced in an experiment. “This process took place in a safe, controlled environment, generating incredibly hot and dense sub-atomic fireballs with temperatures of over ten trillion degrees, a million times hotter than the centre of the Sun.
“At these temperatures even protons and neutrons, which make up the nuclei of atoms, melt resulting in a hot dense soup of quarks and gluons known as a quark-gluon plasma.” Quarks and gluons are sub-atomic particles — some of the building blocks of matter. In the state known as quark-gluon plasma, they are freed of their attraction to one another. This plasma is believed to have existed just after the Big Bang.
The US Navy is looking for a way to replace bulky antennas on warships with antennas made from seawater.
What they came up with is little more than an electromagnetic ring and a water pump. The ring, called a current probe, creates a magnetic field through which the pump shoots a steam of seawater (the salt is a key ingredient, as the tech relies on the magnetic induction properties of sodium chloride). By controlling the height and width of the, the operator can manipulate the frequency at which the antenna transmits and receives. An 80-foot-high stream can transmit and receive anywhere from 2 to 400 mHz, though much smaller streams can be used for varying other frequencies, ranging from HF through VHF to UHF.
Wow. (via bldgblog)
Christoph Niemann hits another one out of the park with an illustrated look at the how physics governs everything we do in life.
I loved his idea for calorie-neutral foods:
All you need is to freeze a pint of ice cream to -3706 F. The energy it will take your system to bring the ice cream up to a digestible temperature is roughly 1,000 calories, neatly burning away all those carbohydrates from the fat and sugar. The only snag is the Third Law of Thermodynamics, which says it’s impossible to go below -459 F. Bummer.
Researchers at Fermilab are building a holometer, the most precise clock ever, which will attempt to determine if the 3-D aspect of the universe is a hologram.
Black hole physics, in which space and time become compressed, provides a basis for math showing that the third dimension may not exist at all. In this two-dimensional cartoon of a universe, what we perceive as a third dimension would actually be a projection of time intertwined with depth. If this is true, the illusion can only be maintained until equipment becomes sensitive enough to find its limits. “You can’t perceive it because nothing ever travels faster than light,” says Hogan. “This holographic view is how the universe would look if you sat on a photon.”
The Great Egg Race was a late-70s/early-80s BBC TV show that was a kind of Junkyard Wars on a smaller and more nerdy scale. The first episode shows a number of people attempting to build small egg carrying cars powered by rubber band.
I love this stuff. I had a physics teacher in high school who presented us with a number of these challenges throughout the school year. There was the strong toothpick bridge (someone basically cheated and made a glue bridge with embedded toothpicks) and the rolling object (it had to go down a short ramp and stop on a mark about 10 feet away), but my favorites were the mouse trap-powered car and the egg drop.
The winning mouse trap car was made with a lot of assistance from the student’s father, who owned a machine shop. It was light but solid with precisely machined plastic wheels and a precisely machined axle and travelled probably twice as far as any of the other cars, which were generally built with whatever crappy off-the-shelf components could be scrounged from the local five-and-dime. I spent three satisfying late nights building my car and came in pretty close to last.
The egg drop challenge involved constructing a landing pad no taller than 12 inches for an unboiled egg. Competitors dropped their eggs from successively greater heights until the egg broke. The two winning landing pads were successful at the greatest height that our small school could muster…out a window at the top of the football field stands, probably about 35 or 40 feet tall. One was a huge box full of wool and other soft materials that could have successfully cushioned an egg dropped from the top of the Sears Tower. The other winner was a tupperware bowl full of stale popcorn that your humble blogger grabbed off the counter the morning of the challenge after completely forgetting about it over the weekend. No one was more surprised than I to discover that popcorn is an ideal egg cushioning material…not that I let on. :)
The Big Picture has a selection of photos of the National Ignition Facility which I’ve written about previously.
“Creating a miniature star on Earth” is the goal of the National Ignition Facility (NIF), home to the world’s largest and highest-energy laser in Livermore, California. On September 29th, 2010, the NIF completed its first integrated ignition experiment, where it focused its 192 lasers on a small cylinder housing a tiny frozen capsule containing hydrogen fuel, briefly bombarding it with 1 megajoule of laser energy. The experiment was the latest in a series of tests leading to a hoped-for “ignition”, where the nuclei of the atoms of the fuel inside the target capsule are made to fuse together releasing tremendous energy — potentially more energy than was put in to start the initial reaction, becoming a valuable power source.
The NIF and the LHC are this generation’s Apollo program.
That habitable exoplanet discovery? Maybe not.
Astronomer Francesco Pepe of the Geneva Observatory in Switzerland, who spoke Oct. 11 at an International Astronomical Union symposium on planetary systems, reported a new analysis using only HARPS data, but adding an extra 60 data points to the observations published in 2008. He and his colleagues could find no trace of the planet.
Using motion tracking software, Rhett Allain finds out if the flight of the slingshotted Angry Birds adheres to the laws of physics.
The only force acting on the bird (if the bird is not moving too fast) would be the gravitational force from the Earth. This is where I see lots of intro-student mistakes. They tend to want to put some force in the horizontal direction because the bird is moving that way. DON’T do that. That is what Aristotle would have you believe, but you don’t want to be in his club. There is no horizontal force in this case — no air resistance.
He also determines the height of the red bird: about 2.3 feet tall. The big red bird must be at least double that.
A team of scientists has discovered a potentially habitable planet located about 20 light years from Earth.
The paper reports the discovery of two new planets around the nearby red dwarf star Gliese 581. This brings the total number of known planets around this star to six, the most yet discovered in a planetary system other than our own solar system. Like our solar system, the planets around Gliese 581 have nearly circular orbits.
The most interesting of the two new planets is Gliese 581g, with a mass three to four times that of the Earth and an orbital period of just under 37 days. Its mass indicates that it is probably a rocky planet with a definite surface and that it has enough gravity to hold on to an atmosphere, according to Vogt.
Gliese 581, located 20 light years away from Earth in the constellation Libra, has a somewhat checkered history of habitable-planet claims. Two previously detected planets in the system lie at the edges of the habitable zone, one on the hot side (planet c) and one on the cold side (planet d). While some astronomers still think planet d may be habitable if it has a thick atmosphere with a strong greenhouse effect to warm it up, others are skeptical. The newly discovered planet g, however, lies right in the middle of the habitable zone.
Sam Arbesman’s prediction of May 2011 might have been too conservative. And 20 light years…that means we could send a signal there, and if someone of sufficient technological capability is there and listening, we could hear something back within our lifetime. Contact! (thx, jimray)
Several physicists weigh in on what would happen if you were to place your hand in the proton stream of the Large Hadron Collider at CERN.
There’s not a definite answer…the responses range from “nothing” to “you’d die for sure, instantly”.
This little guy is a newborn uncontrolled nuclear fisson reaction. You know, an atomic bomb.
This is from a NY Times photo slideshow of atomic bomb explosions. Check out the school bus sequence starting at slide #14.
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