New sea creatures, humongous stars, and cockroach antibiotics: Those are just a few reader favorites from this year in science. As 2010 comes to a close, we bring you a dozen of the most popular 80beats posts of the year.
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For more great stories from the year in science, check out DISCOVER’s Top 100 Stories of the Year.
That’s the minuscule factor by which time speeds up if you’re elevated just one foot higher from the surface of the Earth, according to new study in Science that cleverly demonstrates Einstein‘s general relativity on a human scale. Don’t rush to move into the basement to extend your life, though: That tiny speck of a difference would account for just about a billionth of a second over the span of the year.
Gravity is the key player in this time variance:
One of the top three priorities for the next decade of astrophysics and astronomy, we noted this week, is unraveling dark energy, the weird force that pushes the universe apart. Given that scientists know next-to-nothing about dark energy—besides the fact that it makes up most of the universe—any step could be an important one. Thanks to a study out this week in Science, astrophysicists at least can have more confidence in this phenomenon that can’t be directly seen or measured: Their estimates for dark matter’s extent appear to be on target.
The technique scientists used in this study is called gravitational lensing, and the lens in this case is a huge galactic cluster called Abell 1689.
Because of its huge mass, the cluster acts as a cosmic magnifying glass, causing light to bend around it. The way in which light is distorted by this cosmic lens depends on three factors: how far away the distant object is; the mass of Abell 1689; and the distribution of dark energy [BBC News].
In a study published yesterday in Science, physicists describe their attempts to study the overlap between these two theories–by dropping really cold rubidium (only billionths of a degree warmer than absolute zero) from a great height (480 feet). The cold rubidium behaves as an observable, quantum mechanical system and since gravity is a main driver in general relativity, watching gravity’s pull on that system might give researchers glimpses into how to tie the two theories together.
“Both theories cannot be combined,” said researcher [and coauthor of the paper] Ernst Rasel of the University of Hannover in Germany. “In that sense we are looking for a new theory to bring both together.” [Live Science]
Here’s what they did:
Step 1 — Cool it
Physicists first made super-cold Bose-Einstein condensates of rubidium. Since heat is really the random jostling of molecules, to cool things down, experimenters had to make those molecules sit still. They used an elaborate system of lasers to hold the molecules steady.
When rubidium atoms get that cold, they exhibit quantum mechanical behaviors that researchers can observe, acting like one giant particle-wave.
The idea is to chill a cluster of atoms to a temperature that is within a fraction of absolute zero. At that extreme, the atoms all assume the same quantum-mechanical state and begin to behave collectively as a sort of super-atom, known as a Bose-Einstein condensate (BEC). [Nature News]
In this study, researchers contained that complicated system in a two-foot diameter and seven-foot tall cylinder.
How far can you beam information instantaneously? Try 10 miles, according to a study in Nature Photonics that pushes the limits of quantum teleportation to its greatest distance yet. At that distance, the scientists say, one can begin to consider the possibility of someday using quantum teleportation to communicate between the ground and a satellite in orbit.
As stories about quantum teleportation usually note, this isn’t the Starship Enterprise’s transporter: The weird quantum phenomenon makes it possible to send information, not matter, across a distance.
It works by entangling two objects, like photons or ions. The first teleportation experiments involved beams of light. Once the objects are entangled, they’re connected by an invisible wave, like a thread or umbilical cord. That means when something is done to one object, it immediately happens to the other object, too. Einstein called this “spooky action at a distance.” [Popular Science]
A team of scientists led by Mark Raizen at the University of Texas at Austin had the gumption to take on Einstein. And according to their new paper in Science, they won. The point of contention? The lovechild of statistical mechanics and thermodynamics: Brownian motion.
Here’s how they did it.
Step 1. Learning the Moves
In the 1820s, Scottish botanist Robert Brown looked through a microscope at plant bits floating in water, and wrote [PDF]:
“I observed many of them very evidently in motion . . . [these motions] arose neither from currents in the fluid, nor from its gradual evaporation, but belonged to the particle itself.”
To make sure that the pollen wasn’t alive–actually swimming around–Brown tried it with coal dust. Dust had the same moves.
Today, we understand that Brownian motion, the random break dance of these tiny particles, comes from the water molecules bumping against them. In 1905, Einstein determined the properties of the liquid and the particles that would help describe their wanderings and the motion of molecules. But he also said that it was “impossible” to determine at any moment the speed and direction of a single particle during this dance.
Step 2. Water Into Air
The reason for Einstein’s doubt? The particles bumped around too quickly to ever measure their speed and direction:
He believed that it would be impossible in practice to track this motion, given the incredibly short timescales over which the Brownian fluctuations take place. [PhysicsWorld]
How quick is too quick? A very tiny glass sphere (think micrometers) in water would change direction almost every 100 nanoseconds (about the time it takes light to travel 30 meters). Raizen wanted to make the time between moves longer, so they didn’t use water. They put the glass beads on a dance floor with fewer partners, using a medium whose molecules are farther apart: air.
The theory of general relativity: It works. OK, it’s not exactly Earth-shattering news that Albert Einstein’s century-old idea works in real life. That’s been shown over and over. But what had been difficult for researchers to do until now was verify the theory on truly massive scales beyond the solar system, that of whole galaxies and clusters of galaxies. This week in Nature, Reinabelle Reyes and colleagues report that they did it, and that Einstein was proven correct once more.
While the find is a nice coup for Reyes’ team, its importance goes beyond just reaffirming the great scientists of yesteryear with yet another “Einstein was right” story. The existence of dark matter and dark energy is based on the assumption that Einstein’s gravity is affecting galaxies billions of light-years from Earth in the same way that it affects objects in our solar system [National Geographic]. However, if the study had shown that general relativity needed a slight adjustment at vast distances (like the nudge Einstein himself provided to Newton’s physics), that could have altered prevailing ideas about dark matter and energy. This research indicates those pesky ideas may be here to stay [Space.com].
New results are in from the Fermi Space Telescope, which settled into orbit in the summer of 2008, and the findings seem to prove Albert Einstein right once again. Man, that guy was good.
The telescope detected and studied a gamma ray burst, one of the massively bright and powerful explosions that occurs when stars go supernova in distant galaxies. Astronomers were interested in the gamma rays of differing energies and wavelengths that were generated by the explosion, and that raced each other across the universe. After a journey of 7.3 billion light-years, they all arrived within nine-tenths of a second of one another in a detector on NASA’s Fermi Gamma-Ray Space Telescope, at 8:22 p.m., Eastern time, on May 9 [The New York Times].
The researchers were wondering if certain gamma rays with both high energies and short wavelengths would arrive last, at the back of the pack. That would suggest that they had violated one of the principles set out in Einstein‘s theory of relativity: that the speed of light is always constant. If researchers could detect a significant lag in some gamma rays, it would also give fresh hope to those ambitious researchers searching for a theory of everything.
Physicists in Washington State and Louisiana recently spent two years hunting for the mysterious gravitational waves first predicted by Einstein, but detected nothing: zilch, zero, nada, nary a ripple. But that “null result” is itself of great value, researchers say, because it tells them where to look for the waves next. The findings are a nice reminder that scientific progress isn’t always about the dramatic discovery; it’s often a long, careful process of testing hypotheses, analyzing results, and heading back to the drawing board.
Einstein’s theory of general relativity states that every time mass accelerates — even when you rise up out of your chair — the curvature of space-time changes, and ripples are produced. However, the gravitational waves produced by one person are so small as to be negligible. The waves produced by large masses, though, such as the collision of two black holes or a large supernova explosion, could be large enough to be detected [SPACE.com].
Beyond those large disturbances, the universe is thought to be filled with small disturbances left over from the rapid period of expansion that followed the Big Bang, in a phenomenon known as the stochastic (meaning randomly distributed) gravitational wave background. If the expansion of the newborn universe had produced strong gravity waves, the physicists working at the two Laser Interferometer Gravitational-wave Observatory (LIGO) centers would have detected them. Since they found nothing, researchers have determined that smaller waves were produced, which they’ll need more sensitive instruments to detect. Says study coauthor Vuk Mandic: “We now know a bit more about parameters that describe the evolution of the universe when it was less than one minute old” [Sky & Telescope].
In several labs around the world, sound waves are doing things they’ve never done before. Teams working in England and the Ukraine have made a sonic laser, or “saser,” which operates in the terahertz range, with sound waves oscillating more than a trillion times per second. Meanwhile, in an Israeli lab, researchers say they’ve created the first ever sonic black hole that traps sound waves and won’t let them escape.
The saser uses packets of sonic vibrations called “phonons” much like a regular laser uses photons. Specifically, the acoustic laser device consists of a sonic beam traveling through a “superlattice” constructed of 50 sheets of material each only atoms thick that are alternately made of gallium arsenide and aluminium arsenide, two materials found in semiconductor [CNET]. The phonons bounce back and forth inside the lattice, which causes more phonons to be released and amplifies the overall signal. The result is the formation of an intense series of synchronised phonons inside the stack, which leaves the device as a narrow saser beam of high-frequency ultrasound [New Scientist].
At the moment the terahertz saser, described in a paper published in the journal Physical Review B, is mainly a neat trick, but it may find practical applications down the line, says lead researcher Tony Kent. “Fifty years ago many eminent scientists said that light amplification by the stimulated emission of radiation [lasers] was no more than a scientific curiosity,” says Kent, but lasers are now used for everything from digital storage and cancer treatment to weaponry [New Scientist]. Kent says the new saser technology could lead to breakthroughs in imaging for tiny, nanoscale objects.