Atoms sometimes release alpha particles during radioactive decay.

What’s the News: An international team of researchers has completed the most precise measurement of the Earth’s radioactivity to date. By analyzing subatomic particles streaming out of the interior of the planet, the geologists and physicists discovered that the radioactive decay of several elements generates roughly half of the Earth’s total heat output. Their results were published recently in the journal Nature Geoscience.

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What’s the News: While the Kepler spacecraft is busy finding solar system-loads of new planets, other astronomers are expanding our idea where planets could potentially be found. One astronomer wants to look for habitable planets around white dwarfs, arguing that any water-bearing exoplanets orbiting these tiny, dim stars would be much easier to find than those around main-sequence stars like our Sun. Another team dispenses with stars altogether and speculates that dark matter explosions inside a planet could hypothetically make it warm enough to be habitable, even without a star. “This is a fascinating, and highly original idea,” MIT exoplanet expert Sara Seager told Wired, referring to the dark matter hypothesis. “Original ideas are becoming more and more rare in exoplanet theory.”

How the Heck:

• Because white dwarfs are much smaller than our Sun, an Earth-sized planet that crossed in front of it would block more of its light, which should make these planets easier to spot. So astronomer Eric Agol suggests survey the 20,000 white dwarfs closest to Earth with relatively meager 1-meter ground telescopes.
• And because white dwarfs are so cool, a planet in a white dwarfs habitable zone would be very close, meaning its transit would happen very fast. Agol says we’d only need to watch a star for 32 hours to pick up on any transiting, habitable planets.
• One leading theory about dark matter is that it’s made of theoretical particles called WIMPS (weakly interacting massive particles). It’s thought that when WIMPs collide (if, of course, they exist), they would explode. Astronomers think that these WIMP explosions could possibly heat a planet enough to make it habitable.
• There are no immediate plans to test the dark matter hypothesis, which is quite theoretical, and any plan to find dark matter-fueled planets would need to look far from here: our part of the universe doesn’t have nearly enough dark matter to bring a planet to habitability.

What’s the Context:

• In other white dwarf news, astronomers have discovered a red dwarf in an extremely tight orbit with a white dwarf.
• And others are still wrangling over what dark matter really is.
• As for exoplanets, astronomers have actually seen one—as in, with visible light—orbiting its star.

Not So Fast:

• It’s not at all clear if white dwarfs have any planets, and if so, whether any of them could possibly support water or life as we know it. For one thing, planets in the habitable zone would be tidally locked with the star—permanent scalding daylight on one side; permanent frozen nighttime on the other.
• Taking 32 hours to find a planet orbiting a white dwarf may seem like a short time, but when you’re looking at tens of thousands of stars, it adds up. Agol told UW Today, “This could take a huge amount of time, even with [a network of telescopes].”
• And just like star-orbiting planets have their Goldilocks zones (not to hot or too cold), dark matter-containing planets would need the right amount of dark matter to be habitable. “It’s not something that’s likely to produce a lot of habitable planets,” Fermilab researcher Dan Hooper told Wired. “But in very special places and in very special models, it could do the trick.” 

References: Eric Agol. “TRANSIT SURVEYS FOR EARTHS IN THE HABITABLE ZONES OF WHITE DWARFS.” doi: 10.1088/2041-8205/731/2/L31

Dan Hooper and Jason H. Steffen. “Dark Matter And The Habitability of Planets.” arXiv:1103.5086v1

Image: NASA/European Space Agency

Good news, solar sail enthusiasts: the NASA experimental spacecraft that was feared to be a dud sprang into life last week.

NanoSail-D was launched aboard a small satellite in December; once the satellite was in orbit the engineers back on Earth ordered the cargo door opened, and waited for NanoSail-D to pop out as planned. But the solar sail craft remained stubbornly inside the cargo bay. As weeks passed with no action, NASA’s hopes for the craft sunk.

But last Wednesday, NASA announced that NanoSail-D had spontaneously emerged.

“We knew that the door opened and it was possible that NanoSail-D could eject on its own,” Mark Boudreaux, FASTSAT project manager at the Marshall Center, said in a press release. “What a pleasant surprise this morning when our flight operations team confirmed that NanoSail-D is now a free flyer.” [CNN]

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In life, most people try to avoid entanglement, be it with unsavory characters or alarmingly large balls of twine. In the quantum world, entanglement is a necessary step for the super-fast quantum computers of the future.

According to a study published by Nature today, physicists have successfully entangled 10 billion quantum bits, otherwise known qubits. But the most significant part of the research is where the entanglement happened–in silicon–because, given that most of modern-day computing is forged in the smithy of silicon technology, this means that researchers may have an easier time incorporating quantum computers into our current gadgets.

Quantum entanglement occurs when the quantum state of one particle is linked to the quantum state of another particle, so that you can’t measure one particle without also influencing the other. With this particular study, led by John Morton at the University of Oxford, UK, the researchers aligned the spins of electrons and phosphorus nuclei–that is, the particles were entangled.

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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.

From John Conway at DISCOVER blog Cosmic Variance:

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.

Related Content:
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

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]

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When neutrinos change from one phase to another, they tell us something about their mysterious nature. These ghostly subatomic particles come in three flavors, physicists say: muon, tau, and electron. Just this summer, a team caught a neutrino in the act of changing from muon to tau, a finding that backed up the argument that these particles do, in fact, have mass. This week, a new study of neutrino oscillation—the changing of flavors—suggests an deeper mystery, and implies that these three flavors of neutrino may not be enough to account for these particles’ behavior.

In Physical Review Letters, a large group of physicists published their study from the MiniBooNE experiment at Fermilab in Illinois. When the physicists looked at oscillations of muon antineutrinos into electron antineutrinos, they found the process happening faster than known physics predicts. Neutrinos followed the rules, but antineutrinos didn’t behave the same way did.

So what does it mean? We asked physicist Silvia Pascoli at the U.K.’s Durham University to explain:

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It’s one of Stephen Hawking‘s most famous hypotheses (though one often co-credited to other researchers): According to the rules of quantum mechanics, a black hole—from which nothing should be able to escape—actually can emit material in the form of Hawking radiation. In the thirty-plus years since the reknowned physicist made his prediction Hawking radiation has remained theoretical, but a research team now claims to have seen it right in the lab.

First, a quick refresher on Hawking radiation:

Physicists have long realised that on the smallest scale, space is filled with a bubbling melee of particles leaping in and out of existence. These particles form as particle-antiparticle pairs and rapidly annihilate, returning their energy to the vacuum. Hawking’s prediction came from thinking about what might happen to particle pairs that form at the edge of a black hole. He realised that if one of the pair were to cross the event horizon, it could never return. But its partner on the other side would be free to go. [Technology Review]

The lonesome, unpaired particles streaming away would make it appear that the black hole was emitting radiation, Hawking argued.
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The sun is breaking the known rules of physics—so said headlines that made the rounds of the Web this week.

That claim from a release out about a new study by researchers Jere Jenkins and Ephraim Fischbach of Purdue, and Peter Sturrock of Stanford. The work suggests that the rates of radioactive decay in isotopes—thought to be a constant, and used to date archaeological objects—could vary oh-so-slightly, and interaction with neutrinos from the sun could be the cause. Neutrinos are those neutral particles that pass through matter and rarely interact with it; trillions of neutrinos are thought to pass through your body every second.

In the release itself, the researchers say that it’s a wild idea: “‘It doesn’t make sense according to conventional ideas,’ Fischbach said. Jenkins whimsically added, ‘What we’re suggesting is that something that doesn’t really interact with anything is changing something that can’t be changed.’”

Could it possibly be true? I consulted with Gregory Sullivan, professor and associate chair of physics at the University of Maryland who formerly did some of his neutrino research at the Super-Kamiokande detector in Japan, and with physicist Eric Adelberger of the University of Washington.

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Detectors buried thousands of feet under the Antarctic ice recently confirmed a mysterious cosmic lopsidedness. Though it might seem reasonable for our planet to receive energetic particles, called cosmic rays, on average from all directions equally, more cosmic rays’ seem to approach Earth from certain preferred directions.

The IceCube Neutrino Observatory, which is still under construction, confirmed these odd cosmic ray preferences, previously detected in the northern hemisphere.

Cosmic rays–energetic particles flung from as nearby as the sun and light years away–are the extra “noise” in the observatory’s experiments; to filter out this noise, researchers needed to map where the cosmic rays are coming from. In a paper published earlier this month in The Astrophysical Journal they confirmed that more cosmic rays seem to come from certain directions–an observation known as anisotropy–in the Earth’s southern hemisphere too.

[T]hey used IceCube to study a longstanding puzzle: whether the distribution of cosmic ray arrivals is uneven across the southern sky, as scientists have previously observed in the northern hemisphere. Indeed, the team found, IceCube detected a disproportionate number of cosmic rays arriving from some parts of the sky. But the reason for this uneven distribution remains unclear. [ScienceNOW]

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Particle physicists hunting for the Higgs boson reported their latest findings yesterday at the International Conference on High Energy Physics in Paris. The big two–Europe’s Large Hadron Collider and Fermilab’s Tevatron Collider (in Illinois)–gave updates, and other conference buzz included talk of a new facility, the International Linear Collider, which may one day give physicists a cleaner look at the other colliders’ results.

Large Hadron Collider — More Detailed Models Help the Search

Currently operating at 7  Tera electron Volts (TeV), the Large Hadron Collider is the world’s most powerful particle accelerator. Though electrical malfunctions hindered the collider in 2008, now LHC scientists report that they have made up for lost time: finding in months, what took the Tevatron, with its 2 TeV collisions, decades.

“The scientific community thought it would take one, maybe two years to get to this level, but it happened in three months,” said Guy Wormser, a top French physicist and chairman of the conference.[AFP]

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To test the basics of quantum theory, physicists recently pulled out an antique. In a paper published today in Science, they confirmed a staple of quantum mechanics, using a test derived from a classic nineteenth century light experiment.

In particular, the researchers questioned how particles move through three slits, something previously too difficult to measure. They found that the particles behaved just like quantum theory–or more specifically the Born Rule–would have predicted.

As physicist Chad Orzel describes in his blog, that’s bad news for theorists hoping to tweak this rule to solve Nobel Prize-worthy problems related to quantum gravity or Grand Unifying Theories.

[The study is good news if] you’re the ghost of Max Born, or the author of an introductory quantum book…. This was disappointing news for some theorists, though, as there are a number of ways to approach problems … that would require some modification of the Born rule. [Uncertain Principles]

But how did they do it?

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It wasn’t supposed to be like this. The Higgs boson, dark matter, neutrinos—weird or poorly understood phenomena like these seemed the likely candidates to provide a surprise that changes particle physics. Not an old standby like the proton.

But the big story this week in Nature is that we might have been wrong all along in estimating something very basic about the humble proton: its size. A team from the Paul-Scherrer Institute in Switzerland that’s been tackling this for a decade says its arduous measurements of the proton show it is 4 percent smaller than the previous best estimate. For something as simple as the size of a proton, one of the basic measurements upon with the standard model of particle physics is built, 4 percent is a vast expanse that could shake up quantum electrodynamics if it’s true.

If the [standard model] turns out to be wrong, “it would be quite revolutionary. It would mean that we know a lot less than we thought we knew,” said physicist Peter J. Mohr of the National Institute of Standards and Technology in Gaithersburg, Md., who was not involved in the research. “If it is a fundamental problem, we don’t know what the consequences are yet” [Los Angeles Times].

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As a younger stronger particle smasher, the Large Hadron Collider can turn even baby steps into new records. Over this past weekend, the LHC beat another personal best–colliding its most protons yet at 10,000 particle collisions per second (about double its earlier rate). Physicists believe this is a crucial step on the collider’s hunt for new physics.

In November of 2009, the LHC collided its first protons as it started its quest to find the suspected mass-giving particle known as the Higgs Boson. The collider is still running at half of its designed maximum energy, but after this weekend, the number of particles per bunch traveling in the ring is just what physicists had planned. This is essential, says CERN physicist John Ellis:

“Protons are complicated particles, they’ve got quarks, [and other small particles], and colliding them is like colliding two garbage cans and watching carrots come out…. The more collisions we get, the closer we get to supersymmetry, dark matter, the Higgs boson and other types of new physics.” [BBC]

Here are some basics:

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If the Higgs boson is the “God Particle,” then some particle physicists just turned polytheistic. To explain a recent experiment, they wonder if five Higgs bosons give our universe mass instead of one.

Last month, we discussed a curious experiment at the Tevatron particle accelerator at Fermilab near Chicago. Colliding protons and antiprotons, the Tevratron’s DZero group found more matter than antimatter.

This agrees well with common sense–if the Big Bang had really churned out equal amounts of matter and antimatter, the particles would have annihilated each other, and we wouldn’t be here. Unfortunately, the physics for this matter favoritism doesn’t make sense.

For one, it requires some fudging to fit the Standard Model, the organizing theory for particle physics. This might seem sad since we were so close to finishing the Standard Model up, with the Higgs filling the last cage in physicists’ particle zoo:

For those who believe the Standard Model is nearly complete, the discovery of the Higgs boson–a theoretical particle that imparts mass to all the other particles–would close out the final chapter. But for others who think that undiscovered physics properties exist–so-called new physics–a sequel to the Standard Model is needed. [Symmetry]

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