The universe is more massive than it looks. Although it’s invisible to the eye, this extra mass, called dark matter, seems to interact with visible matter through gravity and the weak nuclear force. Some researchers hypothesize that dark matter consists of WIMPs, or weakly interacting massive particles, which form an invisible “sea” through which the Earth passes as our planet travels through space. While these WIMPs would ordinarily fly right through ordinary matter, we might be able to observe the rare occasions when one directly strikes a nucleus.
One big challenge to WIMP detection is proving that a collision was due to a WIMP, and not to another type of fly-by particle. Some projects are dealing with this problem by burying their detectors deep underground where no interfering radiation can reach; some are using the fact that the number of WIMP collisions is expected to change throughout each day and each year, as Earth’s position in the sea of WIMPS changes. (This approach is similar to the Michaelson-Morley experiment, which disproved the existence of luminiferous aether, another invisible “sea” we supposedly orbited through.) Now an interdisciplinary group of physicists and biologists has an idea to take the comparison of daily and annual measurements to the next level.
More than just a brilliant physicist, Richard Feynman was also a larger-than-life character whose enthusiasm, boundless curiosity, and mischievous sense of humor made him a dynamic lecturer and memoirist, as well as leading him to pick locks and crack safes for fun. But the very traits that continue to charm science fans today also brought him to the attention of the FBI—and now, with the help of a recent Freedom of Information Act request, we know all the dirt they gathered on the bongo-playing physicist.
MuckRock, a website that helps people file FOIA requests, asked the FBI for its records on Feynman and received and published 361 pages of background checks, interviews with Feynman’s acquaintances, newspaper articles that mention him, and notes on the official investigation. Most of the material is boringly uniform: colleague after colleague asserts that Feynman is trustworthy and dependable, an outstanding scientist and a loyal American. Some interviews add information known to any reader of Feynman’s books: that he was engaging and social, outspoken about his lack of religion, with a wide range of interests that did not include politics. But while readers of Feynman’s semi-autobiographical writing will see certain behavior, such as Feynman learning to crack safes, as a fun and ultimately harmless, the FBI report reveals an all-too-serious perspective: “[Feynman] has been known to show impatience and temper at security problems and investigators…For example, [a colleague] recalled that at one time [Feynman] demonstrated to some security people how worthless the locking procedure was on confidential items and he demonstrated this fact by ‘picking the locks’ of secured cabinets.” An incident that the physicist was fond of portraying as a prank was, to the FBI, a refusal to conform to rules and a sign of potential sedition.
The meter is fixed to the speed of light and a second to the radiation of cesium, but the mass of one kilogram is still not defined by a universal constant. Instead, it’s still pegged to an old-fashioned cylinder of platinum iridium alloy kept under lock and key in Sèvres, France.
The method isn’t just old-fashioned, it’s imprecise, which has literal ramifications across the world when the point is to set the kilogram standard. The cylinder is weighed every few decades against official copies that had the same mass when they were all cast in 1899. When they were last weighed in 1988, however, their masses had drifted 70 micrograms apart.
What’s the News: In high school physics classes, students are often taught that static electricity develops when electrons detach from the surface of one object and jump to another, causing a difference in charge. Since opposite charges attract, the two objects are drawn to one another (like your hair to a balloon). But new research published in the journal Science shows that static electricity is caused by more than just the exchange of individual electrons, and instead involves the transfer of bigger (yet still tiny) clumps of material.
No, you can’t see a black hole. What you might be able to see, though, is the way in which relativity predicts a spinning black hole will bend space, time, and light around it. Scientists say in a new study in Nature Physics that they are closer than ever to being able to see this effect in faraway black holes from our vantage point here on Earth.
Galaxies probably have spinning, supermassive black holes at their center, and spinning black holes possess two types of angular momentum, study coauthor Bo Thide explains. There’s spin angular momentum, which is analogous to what the Earth creates as it spins on its axis, and there’s orbital angular momentum, which is analogous to what the Earth creates as it orbits the sun. Thidé says that the second effect—orbital angular momentum—distorts light in a way that scientists who know what to look for might be able to see it from here.
“Around a spinning black hole, space and time behave in such an odd way; space becomes time, time becomes space, and the whole space-time is actually dragged around the black hole, becomes twisted around the black hole,” Professor Thidé explained. “If you have radiation source… it will then sense this twisting of spacetime itself. The light ray may think that ‘I’m propagating in a straight line’, but if you look at it from the outside, you see it’s propagating along a spiral line. That’s relativity for you.” [BBC News]
Brian Greene: Back to blow your mind.
Having explained string theory to the masses in his bestseller The Elegant Universe and untangled the fabric of the cosmos in The Fabric of the Cosmos, the superstar physicist returns this month with The Hidden Reality, an ode to multiverse theory.
By now, the 11-dimension string theory models of his earlier books … are looking downright commonsensical. “The Hidden Reality” moves on to increasingly speculative and exotic discussions of a bubble multiverse (“Think of the universe as a gigantic block of Swiss cheese. …”) a holographic one, a brane-world scenario (courtesy of string theory), computer-driven simulations, questions of how probability relates to infinity, and the Many Worlds view of quantum mechanics. “A frequent criticism of the Many Worlds approach is that it’s just too baroque to be true,” Mr. Greene writes. [The New York Times]
Multiverse theory—the idea that our universe and its Big Bang were just one of many—is a favorite theme of science fiction (and “Family Guy”), as it allows us to have parallel selves in parallel universes. Greene explains the real science behind the idea with one of his litany of analogies: a simple deck of cards.
If you shuffle the deck infinitely many times, the card orderings must necessarily repeat. Similarly, in an infinite expanse of space, particle arrangements must repeat too—there just aren’t enough different particle configurations to go around. And if the particles in a given region of space the size of ours are arranged identically to how they are arranged here, then reality in that region will be identical to reality here. Except that maybe we’d be seeing the Jets and the Bears in the Super Bowl. [Wall Street Journal]
Since 1983, the Tevatron particle accelerator at Fermilab outside Chicago has been faithfully smashing particles and probing deeper into the mysteries of physics. But its time is nearly at an end.
The Large Hadron Collider—that big European underground ring you might have heard of—surpassed Tevatron in size and energy. The American collider’s operators had hoped to extend its life a few more years, especially with LHC still getting up to speed. But the money just wasn’t there, and so the announcement came yesterday that Tevatron would shut down in September.
In the fall, the Department of Energy’s High Energy Physics Advisory Panel recommended that the Tevatron be funded to run for three years beyond the planned end in September of 2011, largely in order to provide additional information in the search for the Higgs boson. … But in a letter to day to the chair of HEPAP, the head of the Office of Science at the Department of Energy, William Brinkman, wrote that “Unfortunately, the current budgetary climate is very challenging, and additional funding has not been identified. Therefore…operation of the Tevatron will end in FY2011, as originally scheduled.”
Conway’s lengthy eulogy for a particle accelerator is a great read, including plenty of the history of the rivalry between American physicists and the CERN physicists in Europe building their own huge smashers, leading up to the LHC.
80beats: New Revelations From Particle Colliders Past, Present & Future
80beats: Fermilab Particle Physicists Wonder: Are There 5 Higgs Bosons?
80beats: Ghost in the Machine? Physicists May Have Detected a New Particle at Fermilab
Image: Wikimedia Commons
Earlier this month CERN’s smashing machine switched from sending protons zinging around its ring to sending heavy lead ions at relativistic speeds. Those energetic collisions, the physicists now say, have allowed them to use the LHC’s ALICE experiment to glimpse quark-gluon plasma, the “primordial soup” present just after the Big Bang.
During this time, the Universe would have been so hot and energetic that the particles making up the elements we know today were unable to form, leaving the constituents to float “free” as a primordial soup. Quarks and gluons were only able to condense into larger particles when universal energy conditions were low enough. Hadrons (i.e. particles made from quarks; including baryons like neutrons and protons) were only allowed to form 10-6 seconds after the Big Bang. [Discovery News]
It’s a trap! (For antimatter.)
Researchers report this week in Nature that they’ve managed to corral atoms of antimatter in the lab and keep them around for about one-sixth of one second—an eternity in particle physics. The ability to trap these atoms means scientists could soon have the ability to study them directly, and perhaps answer one of the fundamental questions of the universe: Why the matter and antimatter present after the Big Bang didn’t annihilate each other completely and leave a matter-less universe behind.
Jeffery Hangst led the research team at CERN’s ALPHA collaboration.
It’s not easy, because of that mutual-annihilation issue. Hangst said the first trick was to combine the particles in a super-cold vacuum setting — less than 0.5 Kelvin, or -458.8 degrees Fahrenheit. That way, the particles don’t instantly jump away and fizzle out. The second trick is to build a magnetic trap to help contain the particles so that they don’t instantly decay. And there’s a third trick: designing a system capable of verifying that the atoms actually exist. “You must have a trap, and you must be cold, and you must be able to detect that you’ve done this,” Hangst said. [MSNBC]
Cats have been our companions for almost 10,000 years. They have been worshipped by Egyptians, killed (or not) by physicists, and captioned by geeks. And in all that time, no one has quite appreciated how impressively they drink. Using high-speed videos, Pedro Reis and Roman Stocker from the Massachusetts Institute of Technology has shown that lapping cats are masters of physics. Every flick of their tongues finely balances a pair of forces, at high speed, to draw a column of water into their thirsty jaws.
Read the rest of the post at Not Exactly Rocket Science, where Yong explains that each sip is a tug-of-war between inertia and gravity. Here’s a little of that high-speed video:
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