Possible dark matter detection

Dark matter detector prototype similar to the ones used in the recent experiment

University of Chicago physicists have discovered signals that are consistent with WIMPs — weakly-interacting massive particles — the leading candidates for dark matter. The signals were measured in a laboratory apparatus that is buried deep below the surface of the Earth in an abandoned mine in Minnesota, where layers of rock prevent cosmic rays and radiation from interfering with the experiment. Oddly enough, physicists discovered that the signal counts were higher in the summer than in the winter, but it sort of makes sense: in the summer months the Earth’s rotation is aligned with the motion of the Sun through the disk of the Milky Way, creating a net velocity through the dark matter cloud that is theorized to envelope our galaxy.

These results are not confirmation of the existence of dark matter, but they are encouraging nonetheless, especially as they are consistent with results from ten years ago that were deemed controversial at the time.

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New class of supernova intrigues astronomers

The Palomar Transient Factory (PTF) at Caltech has discovered a new class of bright supernovae that has astronomers baffled. The properties of these objects — extreme brightness, high ultraviolet luminosity, the presence of oxygen and lack of metals common to most supernovae — are not explained by current theoretical models. PTF astronomers speculate that these objects could be the result of exploding supermassive stars with 100 times the mass of the Sun or perhaps even magnetars (rapidly rotating neutron stars with super-strong magnetic fields).

The PTF uses an automated system that includes a telescope that scans large portions of the sky night after night using a wide-field imaging camera, and an algorithm that looks for transients — anything that has varied in brightness and/or position — by comparing these images with images from previous nights. When a transient is discovered, its coordinates are automatically sent to a larger telescope at Palomar for further observation. Finally, if the transient turns out to be interesting enough, an actual astronomer will follow-up with even more observations on an even bigger telescope.

This turns out to be an excellent way to pore over the sky looking for supernovae, which are exceedingly short-lived as cosmic events go — a typical supernova will begin to fade after just a few weeks. Prior to automated sky searches like PTF, this meant that catching a supernova in the act was to a large degree a matter of luck. Even though they’re extremely luminous events, most supernovae occur in galaxies that are so far away that they appear as faint dots in astronomical images. Yet there’s a universe potentially brimming over with them. Astronomers estimate that one in every 100 Milky Way-like galaxies will experience a supernova event each year. With about a hundred billion galaxies in the observable universe — about 20% of which are spirals like the Milky Way — that’s potentially hundreds of millions of events every year, and obviously astronomers want to catch as many of them as they can.

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Stunning southern vistas with the VLT Survey Telescope

Wired Science has posted a photo gallery of the new VLT Survey Telescope (VST) in Chile, including VST’s first breathtaking photos of the Southern sky.

The VST is a celestial scout of sorts — its purpose is to take vivid photos of celestial objects and identify suitable candidates for more detailed study by the VLT (Very Large Telescope). The VLT is an array of four large telescopes — each 8.2-m in diameter — with a combined resolution of 1 milli-arcsecond. In practical terms, this means the VLT would be able to distinguish two astronauts standing five feet apart on the surface of the Moon. Since time on the VLT is very precious, the VST — with its impressive 268-megapixel wide-field imaging camera — will be invaluable in selecting optimum targets for it.

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Antimatter successfully contained for several minutes

An illustration of anti-hydrogen containment

Physicists at the ALPHA facility at CERN report that they have managed to contain antimatter for several minutes, a huge improvement over their previous attempt at antimatter containment last year, which lasted only two tenths of a second.

Antimatter is comprised of particles that have the same mass as “normal” particles, like protons or electrons, but have opposite charge: for example, anti-protons have negative charge, while anti-electrons (aka positrons) have positive charge. The antimatter in the ALPHA experiment is in the form of neutral anti-hydrogen — an anti-proton and a positron — created in a high energy state. Anti-hydrogen is the antimatter counterpart to hydrogen, the simplest and by far the most abundant element in the universe.

Physicists at particle accelerates have been able to produce positrons and anti-protons for a long time. Getting them to stick together to form a neutral anti-hydrogen atom and keep it contained has been the real trick. The ALPHA physicists used electric fields to clear out stray charged particles, and used superconducting magnets to hold the remaining anti-hydrogen particles in place. The purpose for containing antimatter for a long periods of time is to allow study of its properties and see how it differs from normal matter. Why is this important? Out of laziness, I’ll just quote myself from a previous article:

… big bang theory requires that equal amounts of matter and antimatter existed in the very early history of the universe. The matter and antimatter would collide and annihilate, producing a burst of energy. The great mystery is why our galaxy and everything we observe appears to be made of matter. Actually, the great mystery is why there is any matter at all, for if there was an equal amount of antimatter, all of it should have been annihilated. Some theories propose a tiny asymmetry, with slightly more matter than antimatter, but these theories raise problems of their own.

What physicists hope to understand is why matter came to dominate the universe instead of antimatter (or no matter at all). Some sort of asymmetry has to exist, and studying anti-hydrogen may reveal what that is.

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Saturday science smorgasbord

Danish inventors successfully launch homemade rocket.

Using money from private donations, space enthusiasts and at least one former NASA employee constructed and successfully launched their own rocket from a floating platform in the sea. The prototype cost $73,000 — extremely cheap as far as rockets go, and no wonder: the components included a hair dryer that was intended to keep a valve from freezing. The rocket was dubbed ‘Heat-1X Tycho Brahe’ after the famous 16th century Danish astronomer.

‘Gang of four’ awarded a $500,000 cosmology prize for their work in dark matter.

Dark matter was first posited to exist in 1934 by astronomer Fritz Zwicky to explain the strange behavior of visible matter spinning around in galaxies. Since that time, detailed observations and complex computer simulations, like those of the prize-winning cosmologists, have helped pin down exactly how much dark matter is in the universe and how it’s distributed.

Thirty years ago, nobody really knew how matter was distributed in the universe on a large scale. Today we know from observations that matter is distributed in cosmic clumps, chains, and filaments surrounding enormous voids. Results from computer models reproduced these features using slow-moving massive dark matter particles, giving cosmologists confidence that dark matter was indeed a major constituent of the universe.

Infrared mapping “masterpiece” shows the universe in 3D.

The map shows two dimensions in terms of celestial longitude and latitude, with a third dimension added by redshift, an indicator of cosmic distance. The map is a culmination of decades of survey work that includes 45,000 galaxies in the local universe.

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An emotional ending

One final space shuttle launch to go, and the mood around NASA is decidedly melancholy. With nothing concrete on the horizon to replace the shuttle, this is an understandable state of mind. A lot of people in the “space shuttle family” are nevertheless trying to be optimistic about the future of the space program, because people need hope in order to function well. Personally, I believe that hope lies with the private sector.

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SpaceX’s Dragon capsule ready for Mars

Artist's conception of the SpaceX Dragon capsule in space

As NASA’s Space Shuttle program winds down, the next generation of space ships is shaping up, most notably with SpaceX’s “Dragon” capsule. The Dragon capsule, intended in the near-term for unmanned supply missions to the International Space Station, has already been tested with a successful launch into space with SpaceX’s Falcon 9 rocket.

SpaceX also plans to make the capsule rated for manned missions. According to Elon Musk, the “nerdwealth” millionaire who is financing SpaceX, the Dragon capsule is capable of landing on other planets. In fact, Musk’s ultimate plans are to have colonies on Mars as soon as possible, and presumably the Dragon will play a role in getting people there.

Remarkably, only nine years after its inception, SpaceX is already reported to be operating at a level comparable to the European Space Agency, a collaboration between 19 European nations established 36 years ago. This is why I believe the future of space is with free enterprise. Motivated by competition and profit, private companies tend to operate far more efficiently and with more innovation than government agencies.

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Endeavour’s last mission and strange physics

Shuttle flight #134 out of 135 is set to launch this Friday, April 29, when Space Shuttle Endeavour will blast into space for the last time. During its last mission, the Endeavour crew will deliver a special physics instrument to the International Space Station.

The instrument, called the Alpha Magnetic Spectrometer (AMS), is designed to make detections of exotic phenomena that are not observable from the surface of the Earth, including antimatter, dark matter, strangelets, and cosmic ray counts. These are all important for testing various theories and for practical reasons.


Big bang theory requires that equal amounts of matter and antimatter existed in the very early history of the universe. The matter and antimatter would collide and annihilate, producing a burst of energy. The great mystery is why our galaxy and everything we observe appears to be made of matter. Actually, the great mystery is why there is any matter at all, for if there was an equal amount of antimatter, all of it should have been annihilated. Some theories propose a tiny asymmetry, with slightly more matter than antimatter, but these theories raise problems of their own. It is important to determine whether any antimatter still exists in the universe, and this is where AMS comes in. AMS is designed to be highly sensitive to antimatter detections all the way to the “edge” of the observable universe.

Dark Matter

Anyone who has been fortunate enough to view the night sky free from the glow of city lights knows that the sky appears to be awash in stars. It’s tempting to think the entire universe looks this way, but this view is misleading. Our night sky provides a local view of a particularly dense area of the universe, the inside of a galactic disk of stars. Even the lovely visage of seemingly endless galaxies in the Hubble Ultra Deep Field may tempt the viewer into thinking the universe is overflowing with galactic material. The (theoretical) reality is that the vast majority of the “stuff” of the universe can’t be seen at all. In fact, according to the latest results from WMAP, stars and gas make up less than 5% of the total stuff out there. Dark matter is theorized to make up 23% of the total stuff (with dark energy making up the biggest chunk at 72% of the total). Even though it’s supposed to be a major constituent of the universe, dark matter has never been directly detected. AMS will look for neutralinos, the leading candidate for the dark matter particle. Theory predicts that when neutralinos collide, they produce other charged particles and energy, which can be detected by AMS.


One of the great discoveries of particle physics was the quark, the basic building block of matter. “Normal” matter (also called baryonic matter) comprises the familiar things of existence, from people to planets to stars. Normal matter is made of two kinds of quarks, called “up” and “down” quarks, bound together in groups of three. Four other types of quarks — called charm, strange, top, and bottom — were predicted to exist and subsequently discovered in particle accelerators. Some of these quarks are known to combine into other types of hadrons, or heavy particles. One theory predicts that strange quarks may group with up and down quarks to make extremely heavy “strange matter” particles called strangelets. Theory predicts that if strange matter comes into contact with normal matter, it could convert the normal matter into strange matter. AMS is designed to make detections of these strangelets if they do in fact exist.

Cosmic Ray Counts

If we have any hope of sending a manned mission to Mars we will need an accurate measurement for the rate of cosmic rays in our solar system. Cosmic rays are charged particles accelerated to near-light speeds, and they represent a major hazard to astronauts who would be exposed to them in space long term without the protection of the Earth’s atmosphere. AMS will make accurate counts of cosmic rays in the solar system so that scientists and engineers can devise appropriate protection for Mars-bound astronauts.

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NASA goes commercial

The SpaceX Falcon 9 rocket

NASA is trying to go commercial for its space delivery vehicles by awarding $269M toward private development

The awards, part of what NASA calls its commercial crew development program, are a bet, pushed by the Obama administration, that commercial companies will be able to get people to and from orbit more quickly and less expensively.

If all goes as planned, NASA anticipates commercial spacecraft will be able to deliver astronauts to the International Space Station mid-decade.

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The free frontier

Yesterday, on the 50th anniversary of the first man in space, The Atlantic featured an article by Jim Hodges lamenting the decline of American exceptionalism in space:

[In the 1960s] Americans didn’t talk of their exceptionalism. They did exceptional things, and the world talked about it. In many places around the world, in science labs and classrooms, the NASA “meatball” was as recognizable as the Stars and Stripes.

People remember that President Kennedy said, “I believe that this nation should commit itself to achieving the goal, before this decade [of the 1960s] is out, of landing a man on the moon and returning him safely to the Earth.”

Forgotten is that just before that challenge, he said this as a preamble to it: “I believe we possess all of the resources and talents necessary [to lead the world into space]. But the facts of the matter are that we have never made the national decisions or marshaled the national resources required for such leadership. We have never specified long-range goals on an urgent time schedule, or managed our resources and our time as to insure their fulfillment.”

The government is certainly not doing that now, and we can’t count on it to do these things ever again.

However, I do not see this as occasion to despair. As well-intentioned as NASA has been, government almost always does things slower, costlier, and with less innovation than private enterprise. In fact, while government has been slashing NASA’s budget and scaling back its goals, private companies out in Mojave have been quietly innovating like crazy:

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