cosmodynamics

Tracing Dark Matter with Ripples in the Whirlpool Galaxy

2012-01-09T14:19:00.000-07:00

A new paper presented at this week’s American Astronomical Society conference promises to shine some light, so to speak, on the pursuit of dark matter in individual galaxies. The current model of cold dark matter in the Universe is extremely successful when it comes to mapping the mysterious substance on large scales, but not on galactic and sub-galactic scales. Earlier today, Dr. Sukanya Chakrabarti of Florida Atlantic University described a new way to map dark matter by observing ripples in the hydrogen disks of large galaxies. Her work may finally allow astronomers to use their observations of ordinary matter to probe the distribution of dark matter on smaller scales.
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Full story at Universe Today.

Unlocking Cosmology With Type 1a Supernovae

2012-01-05T18:00:00.000-07:00

Let's face it, cosmologists catch a lot of flack. It's easy to see why. These are people who routinely publish papers that claim to ever more finely constrain the size of the visible Universe, the rate of its breakneck expansion, and the distance to galaxies that lie closer and closer to the edges of both time and space. Many skeptics scoff at scientists who seem to draw such grand conclusions without being able to directly measure the unbelievable cosmic distances involved. Well, it turns out cosmologists are a creative bunch. Enter our star (ha, ha): the Type 1a Supernova. These stellar fireballs are one of the main tools astronomers use in order to make such fantastic discoveries about our Universe. But how exactly do they do it?
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Full story at Universe Today.

Testing the Multiverse... Observationally!

2011-08-05T08:46:00.001-06:00

The multiverse theory is famous for its striking imagery. Just imagine our own Universe, drifting among a veritable sea of spontaneously inflating “bubble universes”, each a self-contained and causally separate pocket of higher-dimensional spacetime. It’s quite an arresting picture. However, the theory is also famous for being one of the most criticized in all of cosmology. Why? For one, the idea is remarkably difficult, if not downright impossible, to test experimentally. But now, a team of British and Canadian scientists believe they may have found a way.
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Full story at Universe Today.

Ancient Galaxies Fed On Gas, Not Collisions

2011-07-01T09:00:00.001-06:00

The traditional picture of galaxy growth is not pretty. In fact, it’s a kind of cosmic cannibalism: two galaxies are caught in ominous tango, eventually melding together in a fiery collision, thus spurring on an intense but short-lived bout of star formation. Now, new research suggests that most galaxies in the early Universe increased their stellar populations in a considerably less violent way, simply by burning through their own gas over long periods of time.
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Full story at Universe Today.

Most Distant Quasar Opens Window Into Early Universe

2011-07-01T08:30:00.002-06:00

Astronomers have uncovered yet another clue in their quest to understand the Universe’s early life: the most distant quasar ever observed. At a redshift of 7.1, it is a relic from when the cosmos was just 770 million years old – just 5% of its age today.
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Full story at Universe Today.

Cosmology in the Year One Trillion

2011-06-23T23:59:00.001-06:00

Much of what is known today about the birth of the cosmos comes from astronomical observations at high redshifts. Due to the accelerated expansion of the Universe, however, astronomers of the future will be unable to use the same methods. In a trillion years or so, our own Milky Way galaxy will have merged with the Andromeda galaxy, creating a new galaxy that has been quaintly termed “Milkomeda.” All of our other galactic neighbors will have long disappeared beyond our cosmological horizon. Even the CMB will have been stretched into invisibility. So how will future Milkomedans study cosmology? How will they figure out where the Universe came from?
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Full story at Universe Today.

Neutrinos Probe Antimatter in Japan

2011-06-18T15:56:00.000-06:00

Neutrinos are nearly massless elementary particles that interact extremely weakly with matter. As you read this sentence, trillions of neutrinos are streaming through your body at nearly the speed of light, yet you don't feel a thing. It has been said that a neutrino could easily pass through light years of lead before disturbing even one atom - quite the feat for a particle that may hold the key to understanding the dearth of antimatter in our Universe! Not only are these subatomic speed ninjas extremely difficult to detect, but they actually possess a kind of quantum mechanical ADD as well. Neutrinos are known to spontaneously change between three distinct types, or flavors, during the course of their travels. Two of these so-called flavor oscillations have already been observed, leaving just one unaccounted for... until now.

Just a few days ago, scientists from the T2K experiment in Japan released data that suggests they may have witnessed the third flavor oscillation. At the T2K experiment, a beam of muon neutrinos is isolated from a proton stream at J-PARC in Tokai, and sent to the Super-Kamiokande detector in Kamioka, 295 kilometers away. The goal of the experiment is to see how many muon neutrinos change into electrons neutrinos along the way by detecting the number of electron events at the far detector. In an experiment of this nature, approximately 1.5 electron events that have nothing to do with neutrino flavor oscillations are to be expected. But when the background noise and other rogue neutrino events were filtered out of the data, 6 solid events remained: 6 events that suggest the appearance of electron neutrinos with 99.3% confidence, a 2.5 sigma result.

Due to the earthquake that struck Japan back in March, the T2K experiment has only been able to gather 2% of the total data it was designed to. So with 98% of the data still forthcoming, a 2.5 sigma is a pretty promising result. Physicists are hoping that understanding this last flavor oscillation will allow them to probe the differences between neutrinos and their anti-particles, anti-neutrinos. If the mechanism of flavor oscillation differs between the two sets, it may lead scientists to a better understanding of CP violation, the phenomenon believed to be responsible for the abundance of matter over anti-matter in our universe.

Antigravity Could Replace Dark Energy as Cause of Universe’s Expansion

2011-04-18T07:06:00.002-06:00

Since the late 20th century, astronomers have been aware of data that suggest the universe is not only expanding, but expanding at an accelerating rate. According to the currently accepted model, this accelerated expansion is due to dark energy, a mysterious repulsive force that makes up about 73% of the energy density of the universe. Now, a new study reveals an alternative theory: that the expansion of the universe is actually due to the relationship between matter and antimatter. According to this study, matter and antimatter gravitationally repel each other and create a kind of “antigravity” that could do away with the need for dark energy in the universe.
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Full story at Universe Today.

Cosmology 101: The End

2011-03-29T14:44:00.000-06:00

Welcome back to the third, and last, installment of Cosmology 101. So far, we’ve covered the history of the universe up to the present moment. But what happens next? How will our universe end? And how can we be so sure that this is how the story unfolded?
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Full story at Universe Today.

Damaged nuclear reactors intensify fears in disaster-ravaged Japan.

2011-03-14T14:00:00.004-06:00

Since Friday, the world's eyes have been on Japan. Hundreds of aftershocks and catastrophic tsunamis followed a record-shattering earthquake 80 miles east of the coastal city of Sendai, likely killing thousands and leaving hundreds of thousands more injured and/or homeless. Explosions sparked by the force of the quakes, combined with toppling buildings, flooding neighborhoods, and rippling, splitting pavement made for an almost post-apocalyptic scene in many Japanese cities. One eyewitness in Tokyo likened his experience to being "in a disaster movie." Economic losses are expected to be in the tens of billions of dollars. Millions of people are without heat, water or electricity. And to make matters worse, three nuclear reactors at the Fukushima Daiichi power station are now in danger of a full meltdown.

Map of the areas affected by Friday's earthquake, including the Fukushima Daiichi power station. (Image courtesy of USGS)
A nuclear reactor creates power through the process of fission, in which the nucleus of an unstable atom is broken apart. One of the most common isotopes used in fission reactions is uranium 235. The nucleus of a U₂₃₅ atom is massive, consisting of 92 protons and 143 neutrons. If it absorbs an additional neutron, it becomes too heavy and decays into other, more stable elements. Fission of the U₂₃₅ nucleus also yields a second neutron, which then causes a chain reaction of fission in other, nearby atoms of U₂₃₅. In a nuclear reactor, uranium pellets are housed in metal fuel rods that are submerged in highly pressurized water. Fission reactions inside the fuel rods create heat, which causes the surrounding water to boil. The boiling water is then transferred to a turbine, where its heat energy is converted to electricity.

Diagram of a nuclear reactor. (Image courtesy of 45 Nuclear Plants)
Immediately following the earthquake, workers at the Fukushima Daiichi station deployed a control system in the reactors and successfully halted the fission process; but with no electricity, the cooling mechanism failed. Residual heat in the fuel rods is now causing water to boil off, increasing the pressure inside the reactor to dangerous levels and raising concerns of a full meltdown. If the fuel rods are exposed to air for too long, the metal casing could crack, allowing radioactive material and hydrogen to escape and possibly triggering an explosion that would release radiation into the atmosphere. Explosions have already occurred in two out of three damaged reactors. Twenty-two people were diagnosed with radiation poisoning after the first explosion and the roof of one of the secondary containment vessels was blown off in the second.

As Japan continues racing against the clock to keep its nuclear energy contained, the debate over nuclear power rages in the rest of the world. Many are citing the Three Mile Island incident in 1979, the 1986 disaster at Chernobyl, and now the crisis at Fukushima as prohibitive warnings to the growth of nuclear power. Others, like risk assessment scholar David Ropeik, have questioned the relative danger of radiation poisoning when compared with the carcinogenicity of coal and oil burning byproducts.

Either way, the situation in Japan isn't getting any better. Even if operators prevent a full meltdown at the Fukushima plant, it will take years for the people of Japan to recover from this tragedy. According to the New York Times, one senior official is less than optimistic, remarking "under the best scenarios, this isn’t going to end anytime soon."

Cosmology 101: The Present

2011-03-09T23:59:00.000-07:00

Welcome back! Last time, we discussed the first few controversial and eventful moments following the birth of our cosmos. Looking around us today, we know that in the span of just a few billion years, the universe was transformed from that blistering amalgam of tiny elementary particles into a vast and organized expanse just teeming with large-scale structure. How does something like that happen?
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Full story at Universe Today

Cosmology 101: The Beginning

2011-02-17T08:14:00.000-07:00

How did the universe get its start? It’s one of the most pressing questions in cosmology, and likely one that will be around for a while. Here, I’ll begin by explaining what scientists think they know about the first formative seconds of the universe’s life. More than likely, the story isn’t quite what you might think.
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Full story at Universe Today.

Universe Could be 250 Times Bigger Than What is Observable

2011-02-08T10:11:00.000-07:00

Our Universe is an enormous place; that's no secret. What is up for discussion, however, is just how enormous it is. And new research suggests it's a whopper - over 250 times the size of our observable universe.

Currently, cosmologists believe the Universe takes one of three possible shapes:

1) It is flat, like a Euclidean plane, and spatially infinite.
2) It is open, or curved like a saddle, and spatially infinite.
3) It is closed, or curved like a sphere, and spatially finite.

While most current data favors a flat universe, cosmologists have yet to come to a consensus. In a paper recently submitted to the Arxiv, UK scientists Mihran Vardanyan, Roberto Trotta and Joseph Silk present their fix: a mathematical version of Occam's Razor called Bayesian model averaging. The principle of Occam's Razor states that the simplest explanation is usually the correct one. In this case, a flat universe represents a simpler geometry than a curved universe. Bayesian averaging takes this consideration into account and averages the data accordingly. Unsurprisingly, the team's results show that the data best fits a flat, infinite universe.

But what if the Universe turns out to be closed, and thus has a finite size after all? Cosmologists often refer to the Hubble volume - a volume of space that is similar to our visible Universe. Light from any object outside of the Hubble volume will never reach us because the space between us and it is expanding too quickly. According to the team's analysis, a closed universe would encompass at least 251 Hubble volumes.

That's quite a bit larger than you might think. Primordial light from just after the birth of the Universe started traveling across the cosmos about 13.75 billion years ago. Since special relativity states that nothing can move faster than a photon, many people misinterpret this to mean that the observable Universe must be 13.75 billion light years across. In fact, it is much larger. Not only has space been expanding since the big bang, but the rate of expansion has been steadily increasing due to the influence of dark energy. Since special relativity doesn't factor in the expansion of space itself, cosmologists estimate that the oldest photons have travelled a distance of 45 billion light years since the big bang. That means that our visible Universe is on the order of 90 billion light years wide.

To top it all off, it turns out that the team's size limit of 251 Hubble volumes is a conservative estimate, based on a geometric model that includes inflation. If astronomers were to instead base the size of the Universe solely on the age and distribution of the objects they observe today, they would find that a closed universe encompasses at least 398 Hubble volumes. That's nearly 400 times the size of everything we can ever hope to see in the Universe!

Given the reality of our current capabilities for observation, to us even a finite universe appears to go on forever.

Article here. Originally posted on Universe Today.

Check it out!

2011-02-08T10:10:00.000-07:00

Hello fellow cosmodynamicists!

Great news - I'm now going to be covering news in cosmology on the fantastic astronomy blog Universe Today! Most of my articles will be cross-posted here, but make sure you check out the originals too. Subscribe via RSS, like us on Facebook, or follow us on Twitter!

Not quite Jurassic Park, but close.

2011-01-16T20:42:00.005-07:00

15,000 years ago, North America was close to unrecognizable. Most of modern-day Canada and parts of what is now the United States were covered by glaciers and temperatures elsewhere easily averaged below freezing. In the midwest, enormous mammals and birds reigned supreme. One of the most well-known of these massive species was the wooly mammoth. Their stature is believed to have been comparable to today's elephants; however, their hind legs were significantly shorter than their front legs, their colossal ivory tusks often measured over 13 feet in length, and, as you may have guessed, they were exceptionally hairy. Now, Japanese scientists have hatched a plan to bring this ancient beast back to life.

Back in 1996, researchers shocked the world when they unveiled Dolly, the very first test-tube ewe. Dolly lived to be six years old, and has long been hailed as the ultimate triumph of biotechnology. But can the same be done with an extinct species from the last ice age? Allegedly yes, through the process of somatic cell nuclear transfer (SCNT).

In SCNT, scientists extract an egg cell from a live animal and remove its nucleus, replacing it with the nucleus of a somatic cell (a somatic cell is any cell not from a sex organ). Somatic cells are diploid cells, meaning that they have two copies of genetic material from the parent animals. Germ cells, such as egg cells, are called haploid because they only have one copy. Replacing the nuclear material from an egg cell with that of a somatic cell is therefore an effective simulation of fertilization. Once the egg has been modified, it can then be implanted in a surrogate uterus, where it divides to form an embryo.

The research team hopes to isolate an intact somatic cell from frozen remains of a wooly mammoth. Within five or six years, they plan to successfully replace the nucleus of an elephant's egg cell with the nucleus of this preserved mammoth cell, implant it into the uterus of an elephant, and wait patiently for the birth of an animal that has not existed since humanity's first predecessors roamed the earth. No sweat. For some biologists, raising the dead is all in a day's work.

The greatest story ever told.

2011-01-15T18:25:00.002-07:00

13.7 billion years ago, an event occurred. Space itself swelled terrifically into being. Suddenly, there appeared a burgeoning cosmos where before there had been nothing. The explosion left behind a molten sea of charged particles that would eventually give life to everything in the universe. The churning plasma expanded along with space for 300,000 years until its constituent protons and electrons had finally cooled enough to combine. Consequently, the entire universe was soon clouded by neutral hydrogen gas. Such gas absorbs radiation exceptionally well, and so space was plunged into darkness for another billion or so years.

At this point, it was gravity that dispelled the haze. Clumps of gas soon condensed under its influence, slowly becoming dense furnaces for nuclear fusion. The high energy UV radiation emitted by these young stars leaked out across the universe, heating the surrounding gas to temperatures they had not faced since the big bang. Electrons that had been trapped within the nuclei of light atoms were suddenly released, reionizing hydrogen and rendering space transparent once more. As the universe expanded, overdense regions of structure contracted under gravity. Over the course of a few billion years, a familiar cosmos took shape. Stars came together into galaxies, galaxies came together into clusters, wacky objects like quasars came and went, supernovae went off, our Solar System formed, and the universe painstakingly plodded into its current configuration.

You may have noticed that some details are a little murky. As of yet, astronomers have no idea how the first stars formed out of the ambient fog. One pair of scientists is now hoping to change that. Alan Rogers of MIT and Judd Bowman of Arizona State University have developed a method using the 21cm spectral line of hydrogen. This line appears in the spectra of hydrogen atoms that have undergone an excitation. According to Rogers and Bowman, the specific way in which the radio spectrum of hydrogen evolves with time tells us that reionization itself lasted about 5 million years. Thus, the first stars and galaxies were most likely born during this time. Understanding the stellar mechanics that occurred during reionization is one of the most active quests in cosmology today. The team hopes to learn more with future observation and fine-tuning of their instrument, the EDGES antenna at the MIT Haystack Observatory.

New picture of the night sky, thanks to Fermi.

2010-11-10T16:48:00.000-07:00

Imagine a world shadowed each night by a giant cloud of mysterious, illuminated fog. From far outside our galaxy, one would observe the fog rising 25,000 light years above and below the plane of the Milky Way in two enormous plumes. In fact, this world is our own. Of course, you might be more inclined to believe me if you had the ability to see gamma rays.

The Milky Way, in visible light. Gamma rays are invisible to human eyes.
Image courtesy of erikaj121893.
The new discovery comes from a team of Harvard University scientists working with Fermi's Large Area Telescope (LAT). "This work presents a multiwavelength study of the inner Galaxy and identifies several large-scale gamma-ray features, most notably 2 large structures that we refer to as the 'Fermi bubbles'," wrote the team of astronomers in their recent paper. These Fermi bubbles could be millions of years old, but their origin is something of a mystery. Some have suggested that an ancient boom of star births may have later led to a clustered grouping of star deaths. A large number of supernovae occurring all at once could have injected enough energy into interstellar space to create the two plumes of gamma-ray emitting gas. Others, including Douglas Finkbeiner, a senior member of the team, believe that the massive black hole at the center of our galaxy gave rise to the bubbles. Many galaxies emit jets of high-energy radiation due to infalling material around a central black hole, and the Milky Way may be no exception.

The Fermi bubble structures. Image courtesy of Su et al..
It may seem odd that no one had detected these colossal structures before now. As it turns out, the Milky Way has a separate, amorphous halo of gamma-ray fog that prevented astronomers from observing the bubbles until recently. The bubbles, which are slightly more energetic than the ambient haze and have clearly-defined x-ray edges, were only apparent after subtracting this fog from LAT observations. Fermi continues to observe the universe at gamma-ray frequencies.

Talking weak sauce at the NASW luncheon.

2010-11-09T18:29:00.001-07:00

It was almost like kindergarden. One by one, decked out with our nametags and matching knapsacks, each of us chose a boxed lunch and filed into the classroom. There we sat, in a circle, waiting for the woman whose job it was that day to teach us something new. But when Dr. Bonnie Fleming of Yale University arrived, it wasn't a group of five year olds that she stood before; instead, it was a small group of science journalists from around the country, all gathered there to eat, relax, and listen to the latest news in neutrino physics.

"Neutrino physics is a field with many great stories," Fleming began. She then went on to explain that one of the most well-known of these stories is that of flavor oscillation. As it turns out, neutrinos have a sort of quantum mechanical ADD. Rather than sticking with one identity, neutrinos tend to change states spontaneously over the course of their travels. An electron neutrino may suddenly become a tau neutrino, and then a muon neutrino, and then a tau neutrino once more long before you or I have had the chance to ask, "what the- ?"

Regardless of flavor, however, all neutrinos have been said to interact via the same fundamental force: the weak force. As we sat dutifully munching on our sandwiches, Dr. Fleming invited each of us to lay one of our palms on the table and count to three. During that short time, she explained, over a trillion neutrinos had passed through every one of our outstretched hands. Indeed, a neutrino could pass straight through 200 Earths before having any appreciative chance of hitting anything. Physicists call it the "weak" force for a reason.

However, new research at Fermilab has suggested that there may be a fourth, even lazier type of neutrino - one that, unlike its electron, muon and tau counterparts, interacts via the gravitational force rather than the weak force. Perhaps surprisingly, gravity is actually the weakest of the four fundamental forces. If you're not convinced, just rub a balloon against your hair, stick it to the wall, and rest easily in the knowledge that you have just overcome the gravitational influence of the entire planet. Gravity's unbelievable frailty would make directly detecting the alleged new flavor of neutrino, dubbed the sterile neutrino, one of the most daunting tasks yet undertaken by the particle physics community. As it is, neutrinos are notoriously difficult to pin down. "We can only detect their flavor by whatever charged lepton they turn into," said Fleming.

As if neutrinos weren't hard enough to wrap your head around. Rather than exhaust myself by asking any more questions, I just sat there, ate my cookie, and let Dr. Fleming do rest of the talking.

Never-before-seen galaxy clusters make shadowy debut.

2010-11-03T15:33:00.000-06:00

You can run, but you can't hide from the Atacama Cosmology Telescope... especially if you're a massive galaxy cluster. Located high in the mountains of Chile, this telescope takes measurements of the CMB, the radiation that has filled the entire universe since the time of the big bang. Earlier this year, the Plank telescope mapped the CMB with unprecedented accuracy. Now, the ACT is providing astronomers with a way of using this radiation to discover galaxy clusters long before observing them visually.

The Atacama Cosmology Telescope, located in the Andes Mountains or northern Chile.
Image courtesy of Till Niermann.
About 300,000 years after the big bang, the universe had cooled and expanded to such an extent that photons could finally travel freely across long stretches of space without being absorbed by atoms. The background radiation that astronomers observe today is made up of those same primordial photons, whose wavelengths have been stretched by the expanding universe. The CMB now reveals itself as a faint 2.7K glow in the microwave range of the electromagnetic spectrum. Small anisotropies in the CMB sky denote regions of the universe that are either slightly more dense or slightly less dense than average.

WMAP provided one of the first maps of the CMB sky.
Image courtesy of NASA.
Thanks to the Atacama Cosmology Telescope, a team of astronomers from Rutgers University was able to predict the locations of several massive galaxy clusters from these anisotropies in the CMB. "The hot gases within the galaxy clusters cause a tiny fraction of the cosmic background radiation to shift to higher energies, which then makes them appear as shadows in one of ACT's observing bands," explained Jack Hughes, a senior member of the team. This phenomenon, called the Sunyaev-Zel'dovich (S-Z) effect, was predicted back in the 1970s, and has been experimentally verified a number of times since its conception. Astronomers hope that the unparalleled sensitivity of the ACT will provide them with more extensive results than ever before. In the game of galaxy detection, new technologies like the ACT are changing all the rules.

Hot and bothered, take two.

2010-10-20T22:58:00.001-06:00

Last week, I was fortunate enough to interview Professor Mike Shull at the University of Colorado about his recent publication. Although I've reviewed this research before, I thought some revisions were necessary. For more in-depth info about the project, you can check out the transcript of our chat here.

***

Imagine our universe - but smaller, hotter, brighter, and more dense. What you are picturing is the cosmos when it was a mere 2 billion years old. A team of astronomers from the University of Colorado at Boulder has devoted years to studying this epoch in an effort to understand a phenomenon that has recently been christened "universal warming." This period of reheating stalled the formation of dwarf galaxies in the early universe and tore tightly-bound electrons from the helium atoms that had been cooked up during the big bang. How does such dramatic warming happen? Professor J. Michael Shull and his team of observers believe they may have the answer.

As it turns out, the epoch of reheating coincides with a time in the past when extremely powerful, outrageously luminous balls of ultraviolet radiation called quasars ruled the universe. "A quasar, or a quasi-stellar object, is a generic active galactic nucleus,” explains Shull. "Something in the center of a galaxy goes haywire." Quasars emit a huge amount of energy, and his team believes this energy is responsible for the 500 million-year period of aggressive warming that halted the growth of small, low-mass galaxies nearly 12 billion years ago.

The team's work centers on a piece of equipment on the Hubble Space Telescope called the Cosmic Origins Spectrograph, or COS. Astronomers use COS to learn about very distant, very energetic objects by analyzing the way their light is absorbed by electrons in the intervening gas. Shull's team used COS to observe incoming light from a quasar as it passed through distant helium gas, and found that there was no absorption of light between 11.7 billion and 11.2 billion lightyears away. "When the absorption goes away, we’re assuming that it’s because now, helium is fully ionized," said Shull. "Once it’s a bare helium nucleus with no electrons, there’s no absorption." Thanks to the blistering energy of quasars, helium was reionized and star-forming gas heated to escape velocity, preventing the growth of dwarf galaxies.

This isn't a new project for the group at Boulder. Students and faculty in the Department of Astrophysical and Planetary Sciences have been working on this research since 1994, and they hope to continue their investigation for many years to come. In the coming months, Shull and his team plan to repeat their observations using a few different sightlines in order to determine whether reheating occurred at the same time in other regions of the universe. The team's research was published in the October 20 issue of The Astrophysical Journal.

Scientia Pro Publica 42: The Ultimate Answer to the Ultimate Question of Life, The Universe, and Everything.

2010-10-10T22:23:00.002-06:00

That's right! I am proud to present to you this particular edition of Scientia Pro Publica, your ULTIMATE guide to the best science, nature and medical writing on the web... the best, that is, until next week.

Let’s get started with the obvious: we all think science is pretty cool, or we wouldn’t be here. Self-proclaimed science lover Julie links us to some great resources to celebrate our collective appreciation of nature (and rockets!) in her posts World Space Week! and A New Website for Rocket Lovers over at Mama Joules. For some more fun, check out Sailing by Starlight: The Lost Art of Celestial Navigation at Southern Fried Science. There, Andrew teaches us all a lesson about living without navigational equipment. That's right. No Google maps, no GPS, no atlas or street names or landmarks; just you, the sea, and the sky.

Now, let’s talk gossip. Over at Not Ranting… Honestly, Austin Elliot has put together a great post about the scandal discussed in almost every molecular biology class: the publicity garnered by Crick, Watson and Wilkins for their discovery of the structure of DNA in the early 1950s. As the story goes, neither Rosalind Franklin nor Erwin Chargaff were given due credit for their contributions. Elliot documents firsthand evidence to the contrary in DNA – letters, stories, narratives 60 years on.

A more recent excerpt from the scientific tabloids is the “Climategate” scandal. Earlier this year, one of the three major sources of world climate change data came under attack, threatening the credibility of the global warming movement. Andy Extance at Simple Climate discusses the role of weathercasters in this scandal and the ramifications of their personal political affiliations in his post, I Don’t Care What the Weatherman Says, When the Weatherman Puts Politics Ahead of Science.

Objectivity isn't the only thing in our world that is experiencing a shortage. Certain types of fish are actually being overharvested due to ignorance regarding differences between species. Find out more about the taxonomy of skates in David Shiffman's What Species of Skate is for Dinner? at Southern Fried Science. Hannah at Sleeping With the Fishes also writes about overfishing (but with a twist) in Can Seabirds Overfish a Resource?. Meanwhile, at It’s a Micro World After All, Thomas Joseph discusses a different kind of endangerment: wasted energy. In Waste Not, Want Not, he details a recent paper that lays out exactly how much energy the world consumes every year to produce food that ends up spoiled or thrown out. Check out his post for some outrageous figures. And while we're on the topic of waste, Amy at Southern Fried Science might make you think twice the next time you're about to head to the beach. For some surprising facts about the kind of waste products that go into the ocean, read Chemistry of the Great Big Blue: Sewage.

Our understanding of modern science has increased exponentially over the last 100 years, leading some to believe that we are reaching the final frontier of scientific knowledge. Not so, according to Akshat from the Chemistry World Blog. In Have We Solved All the Questions in Chemistry?, he cites a few examples to prove that we are far from being Masters of the Universe.

That being said, even the best writers succumb to overblown language. Andrew at 360 Degree Skeptic begins his critique of groan-inducing rhetoric in The Sloppies: My Awards for Bad Science Writing (Part One). So there are bad science writers. But according to Mike at Traversing the Razor, there are many other categories of science writers as well. Check out his post and learn, What Kind of Science Communicator Are You?.

If you find yourself identifying with what Mike calls The Performer, you might appreciate Blowing Apart Streotypes, a post about the huge difference between the media's portrayal of science and science itself, written by Katherine Haxton at Endless Possibilities v3.0. Make sure you also check out a few posts from September's Ocean of Pseudoscience week: Flipper is a Fraud!, in which Chuck at Ya Like Dags? bursts the bubble of TV-dolphin enthusiasts, and Samurai Crabs, posted at Arthropoda. There, Michael Bok debunks the myth that these crabs are actually the souls of Japanese samurai killed in the 1185 Battle of Dan-no-ura.

It might be these types of legends that lead many in the West to doubt the validity of other Eastern sciences - namely, medicine. Chris at Martial Development endeavors to shift the Western understanding of the ancient concept of chi with an excerpt from Chi Gong: The Ancient Chinese Way to Health by Bruce Holbrook. Holbrook’s aim is not to prove the existence of chi; instead, he suggests that western science would do well to weaken its cultural bias. Read about the biochemical and physical legitimacy of what the Chinese call "chi" in Chris’ post, Science and the Problem With Chi.

Chinese medicine isn’t the only health field susceptible to misinterpretation and backlash. You may have heard some questionable conclusions here in the West about a supposed connection between sleep and weight loss. Akshat at The Allotrope sets the story straight in Sleep More to Lose Weight? Meanwhile, Andrew at 360 Degree Skeptic considers a new clinical trial: Placebo Treatments for Better Sex.

Speaking of sex, Eric Michael Johnson discusses the evolution of human sexuality in a guest post at The Primate Diaries in Exile. Read Sex, Evolution, and the Case of the Missing Polygamists for a twist on the Fred-Wilma Flintstone archetype of early human mating patterns.

And if you think Dino was the only king of the castle back in his day, think again. Revise your vision of the Mesozoic era by reading Giant Mesozoic Badger Turned Mammalian Dogma on its Head, written by Emily Willingham at the College Biology Blog. While you’re at it, let Julia Zichello at Evolverie teach you something about the evolution of skulls since the dawn of mammalkind in her post, What Change May Come. You can also check out Punctuated Equilibrium for more in the evolution vein. In Nuclear Receptors Show Evolution is the Greatest Tinkerer, Grrlscientist explains that the extreme variety in protein structure we see today might be traceable back to one single instance of complexity that underwent small changes over long periods of time.

Whether you study proteins or any other part of our physiology, it is obvious that the human body has evolved to become an incredible machine. Over time, humans have adapted to fight off a wide variety of threats to their well-being. Take microbes for example. Most of us know that our bodies are constantly fighting against external pathogens at the cellular level. So what’s the deal with probiotics found in yogurt and other supplements? Why are certain bacteria good for us, while other bacteria makes us sick? Learn how our bodies maintain the tenuous balance between the two in SE Gould’s post, Friend or Foe? How the Immune System Copes With the Gut Microbiotica over at Lab Rat.

It isn't hard to understand why the human gut has established a symbiotic relationship with certain strains of bacteria. After all, both parties benefit! As it turns out, organisms that can evolve to invoke positive feelings in other species have an advantage over those who cannot. For some reason, flowers actually elicit greater emotional wellbeing in humans than any other studied organism. Could it be that, over time, they have evolved the ability to exploit our happiness for their own gain? Find out in You Are Being Manipulated by Flowers, written by Warren at Positive Psychology Digest.

So flowers can make us happy, and they can certainly brighten up a room, but they can't fix patients suffering from heart disease. Corn, on the other hand, might be able to! In health news, scientists have designed a new type of plastic stent made of corn for patients with blocked or clogged arteries. Instead of remaining implanted in the patient’s blood vessel like a traditional metal stent, it dissolves after about a year and a half and vanishes without a trace. Sarah Rich of Fastco Design explains more in Plastics Made from Corn Could Save Your Life. Those crazy kids and their crazy technology. What will they think up next?

***

An issue of Scientia Pro Publica every single week, that's what! But in order to accomplish this amazing feat, we need more hosts - including one for the next issue! If you're interested in hosting the carnival, check here for the schedule, and sign up for an open slot. If compiling mass quantities of awesome blogposts isn't your thing, but you would still like to participate, you can submit high-quality posts that you have read or written using this handy submission form.

Thanks to all the readers and writers who made this 42nd issue possible! I hope you have all enjoyed it. Remember, the next edition is scheduled to be published on October 25th. See you all then!

Scientia Pro Publica is coming to cosmodynamics!

2010-10-07T23:04:00.004-06:00

Hello faithful cosmodynamicists! I am proud to announce that I will be hosting the upcoming edition of Scientia Pro Publica, the biweekly carnival of the best science, nature and medical writing the blogosphere has to offer.

That being said, I'm looking for your submissions! The issue will be published on Monday, October 11th, so you only have a few days left to submit. If you have an interest in science and writing and would like to share your original work with a larger audience, now is your chance! You can either use this handy submission form, or you can send your articles to ScientiaBlogCarnival@gmail.com. The best quality pieces will appear in the 42nd edition of Scientia, here, on Monday.

Happy writing, and make sure to check back after the weekend!

Early universe hot and bothered, says new research.

2010-10-07T20:16:00.012-06:00

Imagine a place so hot and so high in energy that there is no such thing as a neutral atom. Instead, electrons are blasted away from their nuclei by radiation so intense that the most abundant elements can exist only as positively-charged ions. In many low-mass systems, thermal pressure outweighs the influence of gravity and galaxies can neither grow nor hold onto their stores of gas. The small "stuff" in the universe becomes inert, and stays that way for hundreds of millions of years.

According to new research released by a team working with data from the Hubble Space Telescope's Cosmic Origins Spectrograph, this is exactly what happened to our universe over 11 billion years ago. The astronomers, working out of the University of Colorado at Boulder, claim that two billion years after the big bang, conditions suddenly changed and the entire universe overheated. That seems... drastic. How does something like that just happen, and on such an enormous scale?

Image courtesy of NASA, ESA, and STScI.
Click to enlarge.
You may recall from a previous post or two that quasars are extremely distant, outrageously luminous balls of radiation that were born of cataclysmic galaxy collisions in the early universe. They can emit all sorts of radiation, from radio waves to visible light to x-rays. When photons given off by a quasar interact with intensely hot material falling into a central supermassive black hole, they become energized and propagate as x-rays across the expanding universe. Of course, objects this powerful didn't form right after the big bang. It took a good couple of hundred million years for the first stars to form, and then a few hundred million for those stars to condense into galaxies, and then a few hundred million more for those galaxies to become abundant enough to encroach on each others' space, collide, and create the supermassive black holes responsible for the x-ray output of quasars. Once all of this happened, however, it wasn't long before the universe was filled with x-rays and all of its intergalactic gas heated accordingly.

Gas in the interstellar medium is excited by photons at all energies.
Image courtesy of NASA/JPL-Caltech.
You might be wondering how in the world astronomers can know all of this, given that it all occurred over 7 billion years before our solar system even existed. As it so happens, astronomers can use the blazing brilliance of quasar light to study the gas and dust between us and them. When an energetic photon interacts with an atom, it can transfer some of its energy to one of the atom's electrons, causing the electron to temporarily "jump" to a higher energy state. The energy transferred to the electron will always be a discrete amount, and corresponds to a particular wavelength of light (e.g., radio, visible, x-ray). When astronomers study the spectrum of a sample of gas that lies between a photon source (such as a quasar) and a detector (such as a telescope), any absorbed photons will show up as specific lines in the spectrum. Each line, or transition, corresponds to a particular energy and a particular atom, so scientists can automatically tell what type of atom was energized, how much it was energized, and whether enough energy was present to ionize the atom.

The electromagnetic spectrum. Image courtesy of OSHA.
In this case, the CU-Boulder team spotted a hallmark transition of helium in the gas present between 11.3 and 11.7 billion lightyears away. Knowing how much energy is needed to ionize helium, the researchers were able to extrapolate the harsh and stagnant circumstances our early universe may have faced at that time.

Mapping the conditions of the toddler universe: just one more way Hubble gotchu!

Milky J, Hubble aficionado, seen here with an image of the Eagle nebula, M16, courtesy of the Hubble Space Telescope.

Earth-like planet discovered, may support life.

2010-10-01T08:00:00.008-06:00

Big news: Astronomers have discovered another planet that could support life as we know it. Over the last few years, the number of planets found to orbit nearby stars has increased exponentially. Finding planets is no great shakes anymore. But coming across one that falls within the so-called "Goldilocks zone" of a star (not too hot, not too cold, etc.. get it?) is something entirely different.

Artist rendering of an Earth-like planet in the Gliese system.
Image courtesy of ESO.

The new planet goes by the romantic name Gliese 581g and is part of a system of six known planets orbiting the same red dwarf star about 20 lightyears away from Earth. Two of these planets, 581c and 581d, orbit on either side of 581g - on the warmer and cooler edges, respectively, of the habitable zone (HZ). Meanwhile, planet g lies smack dab in the middle of the HZ, with a presumed equilibrium surface temperature of around 228 K (-45 C). That's pretty cold. Keep in mind, however, that the equilibrium temperature of the Earth is actually about 255 K (-18 C). We can thank Earth's atmosphere and the resulting greenhouse effect for keeping our planet nice and toasty. The same goes for Gliese 581g. A greenhouse effect would support liquid water, one of the cosmic benchmarks for potential development of life. There is an important difference, however: planet g is tidally locked to its star, much like the way our moon is tidally locked to the Earth. This means that one side of the planet always faces its star, while the opposite side always faces away. According to Steven Vogt, an astronomer from the UC - Santa Cruz team, a temperate and liveable climate would probably only exist at the boundary between the blazing hot sunny side and the frigid, perpetually dark side. This might be a card in life's favor, however. To quote Vogt, "Any emerging life forms would have a wide range of stable climates to choose from and to evolve around, depending on their longitude."

Habitable zone of the Gliese system as compared with that of our solar system. Gliese 581g has been discovered in the HZ between planets c and d.
Image courtesy of ESO.

Altogether, there are many factors that distinguish Earth from planetary newcomer Gliese 581g. For instance, the planet is at least three times as massive as Earth, and thus orbits its parent star far closer than we do the sun. Its surface gravity is likely stronger than ours, and it may not necessarily have the same rocky composition or protective atmosphere as we do. But it's a start, and it is certainly conceivable that life could have developed there. Unfortunately, since planet g never transits its star relative to our line of sight on Earth, researchers currently do not have the technology necessary to analyze its composition or exact mass. That being said, the discovery of planet g is the first of its kind, and it gives astronomers and astrobiologists hope of finding many more planets like it. As Vogt put it, "If these are rare, we shouldn't have found one so quickly and so nearby. The number of systems with potentially habitable planets is probably on the order of 10 or 20 percent, and when you multiply that by the hundreds of billions of stars in the Milky Way, that's a large number. There could be tens of billions of these systems in our galaxy." His brazen comments are currently catching a lot of flack on the airwaves, but in theory, he's right. We'd be silly not to acknowledge the likelihood of life elsewhere in the universe, and this discovery is as good a start as any.

Spectacular show to grace the Northern skies tonight.

2010-09-22T09:33:00.019-06:00

Here in America, summer is coming to an end. The fall equinox will occur tonight, September 22nd, at 11:09pm EDT (9:09pm here in Boulder). The full moon that occurs closest to the first day of autumn is called a Harvest Moon, and this year we are getting a rare treat: a "Super Harvest" Moon on the same night as the equinox! Not only that, but both Jupiter and Uranus are near opposition this week, which means that they are positioned exactly opposite the sun in our sky. Jupiter appears to the naked eye as an extremely bright object next to the moon, and one can just as easily see Uranus with simple binoculars or a small telescope. Tonight, the two will appear just one degree apart, a phenomenon known as conjunction. Altogether, it's quite the exciting week for astronomers and stargazers alike.

Harvest Moon, Sept. 25th, 2007. Image courtesy of joiseyshowaa.
An equinox occurs twice each year, at the moment the sun passes directly over Earth's equator. It is commonly believed that on this date, the day and night are of equal length; however, this is not strictly true. In fact, for those observers away from the equator, there is always a slight excess of daytime on the equinox. The moment at which light hours are equal to dark hours is actually called the equilux. For most people on Earth, the equilux occurs just before the vernal equinox and just after the autumnal equinox.

Traditionally, the vernal equinox occurs around March 20th or 21st, while the autumnal equinox occurs around September 22nd or 23rd. In between the equinoxes, the Earth's axial tilt causes one hemisphere to receive more of the sun's energy than the other. In the Northern Hemisphere, we experience summer when our half of the globe is tilted toward the sun and winter when it is tilted away. At the equinoxes, however, the Earth is tilted in the direction of its orbit, rather than in the direction of the sun. This means observers at equal latitudes above and below the equator receive equal amounts of sunlight.

The Earth's tilt accounts for a seasonal climate in the mid-latitudes. Counterclockwise from top left: summer solstice, fall equinox, winter solstice, spring equinox.
Image courtesy of Tau'olunga.
So tonight, as the Earth shows its full-frontal glory to the sun, make sure to watch the evening unfold. The Harvest Moon will appear enormous on the eastern horizon, and the light from both sunset and moonrise will create a unique and rare kind of twilight. This eerie glow, together with Jupiter shining brightly just below the full moon, should create quite a memorable sight for stargazers on the northern half of the globe. Happy fall!

Hawking debunks "myth" of God.

2010-09-03T22:26:00.007-06:00

Stephen Hawking is causing a stir. In a book excerpt published in tomorrow's Wall Street Journal, Hawking addresses the ever-controversial topic of science and religion. His take? The presence of a Creator is rendered completely unnecessary by modern science.

Hawking cites the so-called anthropic principle as the reason many people believe God must exist. The anthropic principle comes in two forms: the "weak" anthropic principle, which states that we developed on Earth because specific factors in our environment allowed us to do so, and the "strong" anthropic principle, which states that our existence as intelligent life-forms mandates the parameters inherent in the laws of nature themselves. For most, the weak anthropic principle is easily debunked. There are plenty of environments in the universe where intelligent life did not develop; we naturally find ourselves in one in which it did. This planet wasn't fine-tuned for the conditions of human life, human life was fine-tuned for this planet. Essentially, we are a statistic. Most people would agree with that in the context of the universe at large.

The controversial part of Hawking's statement, however, is his belief that the strong anthropic principle can be logically unravelled in the same way. The problem with the strong anthropic principle is that we have nothing to compare it to. As far as we are concerned, our universe is the only one. There are a variety of finely-tuned physical constraints inherent in the laws of physics, without which we would not exist. For instance, if gravity were any weaker, stars would never have formed in the early universe. Meanwhile, if gravity were stronger, our sun would have burned through all of its hydrogen already. Take your pick: the strength of the fundamental forces, the precise ratio of matter to antimatter, the stability of heavy elements like carbon, even the number of spatial dimensions in the universe; any of these is at the least, peculiar, and for some, explicit proof of God's existence.

But with the dawn of new cosmology - specifically evidence that points to the existence of multiple universes - Hawking believes that this principle too can be explained away. Just as there are many stars in our universe that are not orbited by planets, and many planets in our universe that are not hospitable to life, there are also many universes within our multiverse in which these physical parameters do have different values, and in which intelligent life was never able to form. Once again, we are a statistic. A Creator did not concoct a universe for our benefit; we evolved as a consequence of the specific universe we are in. Human life was inevitable, not essential. Or so Hawking believes.

First, let me say that I have no problem discussing science and religion in the same sentence. In fact, I think it can be extremely valuable. For my part, I know that science has profoundly affected and enriched my own spirituality. However, I don't think that Hawking's bold statement is going to do much to heal the schism between fundamentalist religion and modern science. There are altogether too many people who actually believe the Earth was created 6000 years ago, and who blatantly ignore scientific fact because they see it a contradiction of their own religious beliefs. Don't get me wrong - I'm a big believer in grey areas, but that is just absurd and ignorant. To be sure, a dialogue needs to be initiated, and a mutual one at that. Evolution absolutely needs to be taught in schools, but not at the expense of prayer or spiritual pride. Unfortunately, while I admire the conviction, I just don't think Hawkingism is going to win any new converts.

Of strings and things.

2010-09-03T08:27:00.003-06:00

Imagine a tiny thread of material, so infinitesimal that it is more than a quadrillion times smaller than a proton (no matter who you ask). Now imagine that same tiny thread being present at the heart of every single particle that makes up every atom that makes up every bit of matter we can observe in the universe. Got that? Good. Now imagine that the identity of every subatomic particle is determined by the precise vibration pattern of the tiny strand of material within; that is, its precise vibration pattern... in ten dimensions. Welcome to the world of superstring theory, one of the most potent contenders for the long sought-after "Theory of Everything" that will combine general relativity and quantum mechanics into one, all-inclusive framework.

As always, xkcd cuts right to the heart of things.

Simply put, string theory elegantly exploits the physical principles of music; that is, plucking a string will generate a different sound, depending on the properties of the string and how hard it is plucked. Some variations of string theory predict that strings are open, with two endpoints, while others predict that strings are closed, like a loop. Either way, it is the specific modes of vibration, or excitations, of the string that give rise to different kinds of particles.

String theorists conceive of elementary particles as having a very small dimension of length, rather than being point particles with no length, width or height. It may seem like a simple change, but this assumption neatly does away with the problems scientists have always faced when trying to formulate a quantum theory of gravity. There is only one problem: scientists have had no way to test the predictions of string theory. Because strings are thought to be so incredibly small, particle accelerators would have to operate at astronomically high energies to probe deeply enough into the subatomic realm. We simply don't have the technology.

Not even CERN has the power to probe the mysteries of string theory.
Image courtesy of Image Editor.

But a new discovery by a researcher at Imperial College London might be about to change things. According to Professor Mike Duff, the math scientists use to apply string theory to black holes is exactly the same as the math that is used to describe quantum entanglement between three particles. In a paper published in this week's Physical Review Letters, Duff and his team of colleagues detail an experiment involving four entangled particles and predict the result based on the mathematics of string theory. If researchers can manage to carry out this experiment, and if the results agree with the team's predictions, string theory will finally have the experimental backing scientists have been seeking for decades.

Currently, there seems to be no practical connection between quantum entanglement and the string physics of black holes. Even Duff acknowledges that they are "unexpected and unrelated" areas of physics. Perhaps researchers are about to discover more than they bargained for. Or perhaps all of this is simply an odd, yet serendipitous, coincidence.

Peer pressure: radioactive decay succumbs to sun's infuence.

2010-08-31T15:13:00.009-06:00

The sun is getting full of itself. Apparently, transitioning into the active phase of its 11-year cycle, throwing off solar flares, and giving rise to sensational aurorae are not enough. Now, new research suggests that our star might also be messing around with radioactivity here on Earth. According to a team composed of scientists from Stanford and Purdue Universities, radioactive isotopes like silicon-32 and chlorine-36 decay at slightly different rates, depending on where the sun's core is in its rotation.

Image courtesy of NASA/Goddard.

The researchers found that decay rates changed by about 0.1% over the course of a recurring 33-day cycle. These measurements fit current theoretical models of the sun's inner rotation quite well. Interestingly enough, they also coincide with the occurrence of solar flares and correlate with the earth's yearly orbit around the sun. "Finding that the decay rates fluctuate in a pattern that matches known and theoretical solar frequencies is compelling evidence for a solar influence on decay rates," said Jere Jenkins of Purdue University, a lead engineer on the team.

The main suspect in this emerging investigation is the solar neutrino. Neutrinos are (nearly) massless, electrically neutral elementary particles that are only subject to the weak force; they can therefore travel extremely long distances without interacting with anything at all. Every second, the earth is pummeled with an innumerable amount of solar neutrinos. In fact, 65 billion neutrinos will pass though every square centimeter of your body in the time it takes you to read the word "radioactivity."

The first recorded evidence of a neutrino. A proton, muon, and pi-meson (right) leave diverging tracks that result from a single neutrino striking the chamber.
Image courtesy of Argonne National Laboratory.

So, if neutrinos don't interact with anything, how could they cause such changes in the decay of radioactive isotopes? Researchers don't really have an answer to that question. Jenkins' words say it best: "What we're suggesting is that something that can't interact with anything is changing something that can't be changed." However, if the team's data does turn out to be accurate, it could have broad implications. Scientists could use changing decay rates to predict and prevent the power outages and technological malfunctions that often accompany solar flares. Variable decay rates could also affect both archeological carbon dating and medical radiation treatments. Thanks to allegedly inert neutrinos, the sun's 11-year cycle might do more than just put on pretty light shows.

When galaxies collide.

2010-08-26T16:20:00.011-06:00

Thanks to science fiction, most people know that our universe is a dangerous place. If you happen to cross the event horizon of a black hole (which is invisible, by the way), your body will immediately be ripped to shreds by tidal forces, and every bit of matter that ever made you "you" will be crushed to an infinite density. In case that doesn't scare you, try this on for size: black holes exist at the center of many galaxies, including our own. That's right. 20,000 light years away, there is an enormously energetic, spectacularly dense, churning pit of doom just waiting for its next victim to wander one step too close. Supermassive black holes (SMBHs) fuel objects called quasars, which are some of the most powerful and luminous sources of radiation in the universe. Quasars can be detected from billions of light years away due to the extraordinary amounts of energy that SMBHs provide them with. But how did these black holes form in the first place?

Artist rendering of dust in the quasar wind. Image courtesy of NASA/JPL.

The SMBHs that power quasars were born when the universe was still very young, mere millions of years after the Big Bang. This means that they must have formed very quickly, and in an environment that contained very few metals. A metal-rich atmosphere would have given rise to normal stars, not black holes; however, even a metal-poor atmosphere would not have been able to yield such massive black holes in such a short time. Now, researchers from Ohio State University believe they have solved the problem. In a paper published in this week's Nature, they suggest that SMBHs formed during the collisions of protogalaxies in the early universe. According to their theory, SMBHs are created when two massive, orbiting galaxies collide and merge into one large, spinning disk of gas. As the gas swirls, it collects in the center of the disk and condenses under the influence of gravity. In only 10,000 years, this process creates a gas clump that weighs hundreds of millions of times the mass of our sun! Eventually, the clump becomes dense enough to create the precursor to a SMBH, or a "seed." This seed gathers more material over time, until it becomes one of the powerful and ancient black holes we observe today.

Artist's rendering of a supermassive black hole. Image courtesy of Phil Plait.

Of course, this mechanism can only explain the formation of SMBHs by colliding galaxies above a certain mass. The OSU team plans to further their research by surveying the masses of SMBHs at different distances, and thus different times in the past. (Since light from faraway stars always travels to us at a fixed rate, looking into the distant universe actually allows scientists to see the universe as it was billions and billions of years ago.) If they can back their model with observational evidence, the OSU team will be that much closer to understanding the complexities of stellar evolution.

Quantum weirdness reaches new heights, now implies parallel universes.

2010-08-18T12:50:00.011-06:00

Einstein's theory of general relativity states that nothing in the universe can travel faster than light. As usual, quantum mechanics disagrees. In special cases, a pair of particles can be connected in such a way that by measuring the state of one, the state of the other can be instantaneously known, even if the two particles are separated by a large distance. Einstein famously poked fun at the idea, sarcastically nicknaming it "spooky action at a distance." Many physicists today still have trouble accepting this so-called quantum entanglement, despite experimental evidence that implores them to think otherwise. In a recent paper, Dr. Frank J. Tipler, a mathematician and physicist at Tulane University, has developed a model that links alleged quantum nonlocality with the Many Worlds interpretation of quantum mechanics. He claims that his theory solves the paradox of faster-than-light travel, but only if we are prepared to accept the fact that we live in a multiverse, a wacky version of the cosmos in which parallel universes are born every time a decision is made.

Einstein's famous gibe, paired with the mathematical notation for "spin-up."
Image courtesy of Matt Mechtley.

The most oft-cited example of quantum entanglement is a system in which two electrons exist in a singlet state; that is, they must have opposite spins. Spin is a property that measures the angular momentum of a particle. When measured in the vertical direction, the spin of a particle can either be "up" or "down." In a singlet state, if one electron is spin up, the other must be spin down; this holds true even if the electrons are separated by hundreds of thousands of lightyears. The problem with such systems is that electrons should not be able to communicate with each other any faster than light can travel. For instance, if they are positioned 100,000 lightyears away from each other, it should take no less than 100,000 years for the news of one electron's chosen spin to reach the other so that it can choose the opposite spin; however, experiments indicate that such information seems to travel instantly.

How can this be? According to Tipler, we should embrace the Many Worlds interpretation of quantum mechanics in order to make sense of this seeming paradox. In the Many Worlds interpretation, every possible set of circumstances exists in a separate universe. Every time one choice is made over another, the universe splits. In my current universe, I am writing this article at a coffee shop in downtown Boulder. In a separate but equally real parallel universe, I am writing from home, successfully resisting the lure of overpriced tea. In yet another universe, I have horrible command of the English language and am instead spending my afternoon pondering the financial merits of becoming a stripper. Regardless of circumstance, each of these alternate universes is just as real as the one in which I sit, fully clothed, diligently pounding out a wordy and rambling piece of science writing.

Image courtesy of anomalous4.

Back to Tipler. In his model, there are four distinct universes that are born of such an experiment: one in which electron #1 is spin up, one in which electron #1 is spin down, one in which electron #2 is spin up, and one in which electron #2 is spin down. But because the two electrons exist in a singlet state, there are only two possible combinations of these worlds. Either electron #1 is spin up and electron #2 is spin down, or electron #1 is spin down and electron #2 is spin up. When an observer measures the state of electron #1 here on Earth, two universes result, each one containing an observer that detects an opposite spin. Thus, the resulting spin of electron #2 has nothing to do with any kind of faster-than-light communication by its counterpart. It is simply a consequence of the particular universe the observer happens to find himself in. Measurement of one electron does not determine the spin of the other; instead, it selects for one universe over another, one in which the two electron spins have been predetermined.

Confused yet? Don't worry, in another universe you know exactly what's going on. I promise.

Particle physics theory plays God, creates the universe.

2010-08-16T15:38:00.006-06:00

For eons, human beings have wondered how we came to be. Physics provides a simple answer: in the early universe, there was more matter than antimatter. You see, when equal parts matter and antimatter meet, they annihilate each other. The slight overabundance of the former 13.7 billion years ago explains why there is a universe at all, and why all the "stuff" we see in it is made out of matter instead of antimatter. Although this is a fairly agreed-upon theory, it begs yet another question: why was there an excess of matter? For years, scientists have cited a phenomenon called CP violation that predicts such an excess; however, CP violation does not predict enough of an excess to match present-day observations. Now, a group at Fermilab's Tevatron claims that they have found yet another instance of CP violation that could help to fill the observational gap.

Fermilab, home of the Tevatron. Image courtesy of Renzo Borgatti.

CP violation postulates that certain particles can transform into both their associated antiparticles and particles that exhibit a mirror-image symmetry, or an opposite "handedness". The former type of inversion is called charge conjugation violation, while the latter is called parity violation. CP violation is one of the Sakharov conditions, three rules that detail what must have occurred during the first short moments following the Big Bang in order for the universe to appear as it does today. The new instance of CP violation was found during an experiment involving a type of neutral B meson. These B mesons each consist of two quarks: an anti-bottom quark and a strange quark. During the experiment, B mesons transformed into anti-B mesons, which consist of a bottom quark and either an anti-strange quark or an anti-down quark. Each of these different "flavors" of quark is unstable in isolation, and decays into a different kind of particle.

The Tevatron experiment yielded an excess of positively charged muons, which only result from the decay of anti-bottom quarks. Since anti-bottom quarks are only found in B mesons and not anti-B mesons, this particular instance of CP violation seems to indicate an excess of matter over antimatter: the exact result the team was seeking. The results of this experiment will soon be retested at multiple detectors around the world, including CDF at Fermilab and the ATLAS and LHC-b detectors at CERN. Until then, the jury is out on whether CP violation can account for the very small matter of our human existence.

Waking sun throws a tantrum, produces dazzling light shows.

2010-08-07T21:04:00.007-06:00

On August 1st, NASA scientists watched as ten billion tons of blazing plasma and electromagnetic radiation were thrown off from our sun without warning, sent hurtling through space toward Earth at over a million miles per hour. You might be wondering why we aren't dead yet.

A coronal mass ejection screams toward Earth's magnetosphere.
Image courtesy of NASA.

Actually, events like this are fairly normal in our stellar neighborhood. Every eleven years or so, the sun completes a cycle of waxing and waning electromagnetic activity. During its more active phases, such furious discharges of material (coronal mass ejections, or CMEs) are common. The last peak of solar activity was in 2001. Now, nine years later, it seems that our star is once again getting ready to pull out the big guns. Between now and 2013, scientists predict that CMEs like the one that occurred last week will become more frequent. But far from signaling our imminent doom, these violent outbursts will actually treat us to a demonstration of one of nature's most amazing spectacles: the aurora.

The Aurora Borealis in Alaska. Image courtesy of Joshua Strang.

Aurorae occur when solar material is spontaneously thrown toward Earth, as in a CME. Upon reaching the magnetosphere, highly energetic solar particles are carried groundward, where they collide with and excite nitrogen and oxygen atoms in the ionosphere. The atoms cannot remain excited, so they release excess energy in the form of a photon. The amount of energy needed to excite an atom determines what color photon is emitted when it makes the transition back to its ground state - in this case, ionized oxygen emits green light while ionized nitrogen emits blue or red light. The flickering lights that spread across the sky during an aurora are simply large-scale representations of the transitions that occur when atmospheric particles are excited by the solar wind.

Atoms in the ionosphere interacting with the solar wind.
Image courtesy of NASA.

Sure enough, the CME on August 1st provided audiences across North America and Europe with spectacular visions of the lights a few days later. Although visibility is usually limited to areas surrounding the poles, some American observers this time around reported light shows as far south as Massachusetts! As solar maximum draws nigh, the after-effects of the sun's raging temper should become more and more apparent. Keep your eyes peeled. Depending on where you live, you might be glad you did.

Could the Big Bang be a bust?

2010-08-01T22:14:00.005-06:00

Once upon a time, our universe was a hot, dense place. Then, out of nowhere (and no-when), it suddenly underwent a monstrous expansion. 13.7 billion years later, we look back upon this moment of extraordinary inflation and call it the "big bang." Over the years, cosmologists have collected a hefty stock of evidence that strongly supports this story. But what if there were another explanation for how we came to be? What if nothing "banged?" What if the universe has always existed? A group of Taiwanese researchers is now suggesting a new cosmological model - one that doesn't require a big bang at all.

In his recent paper, professor Wun-Yi Shu from the Institute of Statistics at the National Tsing Hua University suggests that many of the current problems plaguing cosmology can be solved by his new model. For instance, it renders the horizon and flatness problems obsolete based on new geometry. It also does away with the seemingly improvised explanation that physicists currently give when asked about the accelerated expansion of the universe: an exotic form of anti-gravity called "dark energy." Based on cosmological evidence, dark energy is believed to be responsible for about 75% of the universe's energy density (for comparison, the kind of matter we see all around us only accounts for about 5%). There is only one problem with this theory: researchers have never seen or detected this mysterious form of energy. In general relativity, dark energy is represented by the cosmological constant, a fudge factor inserted by Einstein in order to prevent the universe from collapsing on itself. But according to Shu, dark energy is unnecessary.

The current cosmological model. Image courtesy of NASA/WMAP.

His model makes four major claims. First of all, the speed of light and gravity are not constant; instead, they vary with time as the universe evolves. Secondly, time is infinite. Shu also states that the spatial portion of the universe (that is, the part of spacetime that is not temporal) takes the form of a 3-sphere, the four-dimensional counterpart to a sphere. Lastly, Shu states that although we know that the universe is accelerating now, that doesn't mean it always has been. In his reality, the universe spends time decelerating as well.

Shu's spacetime illustrates a type of eternal, cyclic universe with dynamic physical laws. And perhaps surprisingly, all of this is more than a simple thought experiment. Shu actually compared his model with existing data from the analysis of type 1a supernovae and found that his "theoretical predictions... fit the observations quite well." Einstein once called the cosmological constant the "biggest blunder" of his life. A model such as Shu's could pave the way to vanquishing it and dark energy for once and for all.

Quantum mechanics challenged, but to no avail.

2010-07-27T13:19:00.007-06:00

I've written about light multiple times in this blog, using terms like photons, light rays, and electromagnetic radiation. You might be wondering what the deal is with all the fancy nomenclature, especially since some of these ideas seem to contradict each other. For instance, light comes in quantized packets called photons. But light is also often referred to as a ray or a wave. What gives? Well, as it turns out, light is very, very weird.

Over 100 years ago, the famous Double-Slit Experiment taught physicists that, at its core, light is both a particle and a wave. In quantum mechanical terms, the wavelike property of light means that every photon has a specific probability of being found in a given spot. When two light waves interfere (as in the double-slit experiment), these probabilities can be seen to occur in pairs: one set of positions where a photon is more likely to be found, and one set of positions where a photon is less likely to be found. Physicists at the University of Waterloo in Canada recently conducted a triple-slit experiment and were able to rule out higher-order probabilities, thus confirming a key principle of quantum mechanics.

The double-slit experiment produces a characteristic interference pattern.
Image courtesy of Timm Weitkamp.

Both the double-slit and triple-slit experiments are very simple in design. In the former, a light source is aimed at a metal sheet with two microscopic slits cut into it. The incident light then passes through the slits and lands on a blank screen. Scientists found that when they covered one slit, the light formed a pattern on the screen that was bright in the middle and faded to black at the edges. One would expect that the same pattern would result when both slits were open. If light behaved solely as a particle, half the photons would pass through one slit and half would pass through the other. The result would be a pattern that was doubly bright, but otherwise the same. Oddly enough, this is not what happened. Instead, a pattern of alternating bright and dark bands developed on the screen (see above). This was a clear indication that it was actually two light waves that passed through the slits, interfering with each other before they hit the screen and thus creating this distinctive pattern.

And the story gets weirder still. Experimentalists decided to try firing one photon at a time at the metal sheet. Surely this would force the photons to "pick" one slit over the other and prevent any wave interference from occurring. No such luck. An interference pattern still emerged, albeit more slowly as each photon took its place on the screen. Clearly this phenomenon could not be explained away by saying that light was really just a wave composed of particles. Scientists were forced to conclude that light is simultaneously a particle and a wave. The photons actually behaved as though they were waves, each photon somehow interfering with itself to form the characteristic light and dark bands shown on the screen.

Individually-fired photons produce an interference pattern over time.
Image courtesy of Ethan Hein.

In the triple-slit experiment, the Innsbruck group attempted to find evidence of third-order probabilities. According to our current understanding of the quantum world, this is impossible. The resulting light and dark bands in the double-slit experiment illustrate that such probabilities only occur in pairs. Success at Waterloo would have had drastic consequences for physics, disproving a long-held belief and necessitating a revision of quantum mechanics as we know it. Fortunately, no such result was found. Indeed, the oddities of the subatomic world live to see another day.

Spaceballs: The (Academic) Sequel.

2010-07-26T14:19:00.005-06:00

It's almost like NASA's version of the World Cup. Astronomers using the Spitzer Space Telescope announced last week that they have observed soccer-ball shaped molecules called "buckyballs" in the planetary nebula Tc 1. First isolated in a lab at Rice University in 1985, scientists have long predicted that these molecules would one day be found in space. While previous evidence of naturally-occurring buckyballs was tenuous at best, astronomers can now claim their existence with unprecedented certainty.

Buckyballs are named for their resemblance to architect Richard Buckminster Fuller's famed geodesic domes. Image courtesy of Paul Lowry.

Buckminsterfullerenes, or buckyballs, are hollow, spherical molecules composed of pentagonal and hexagonal linkages of carbon atoms. Since their creation 25 years ago, these and other fullerenes have become increasingly popular in the world of nanotechnology due to their extreme durability and uniquely resilient chemical structure. Buckyballs are also highly aromatic, meaning that their electrons are free to move between adjacent carbon bonds rather than reacting with other, external molecules. Chemically speaking, they are more like an inert gas (such as helium or argon) than a single carbon atom. For these reasons, buckyballs and their cylindrical cousins, carbon nanotubes, continue to be the focus of much research in medicine, engineering and materials science.

The most common type of buckyball is C₆₀. This molecule consists of 60 carbon atoms arranged as shown. Image courtesy of ltamblyn.

Researchers would also like to learn more about the characteristics of naturally created buckyballs. Enter Jan Cami, an astronomer with the University of Western Ontario and the SETI Institute in California, and leader of the group that made the recent discovery. Her team was able to detect these elusive fullerenes in a carbon-rich region of nebula Tc 1. Such regions are common, as planetary nebulae result when a dying star begins to throw off its outer layers of hydrogen, helium, carbon, and other heavier elements. The astronomers actually discovered the buckyballs by accident, catching sight of their unique spectral signature while observing the nebula in infrared light. "When we saw these whopping spectral signatures, we knew immediately that we were looking at one of the most sought-after molecules," said Cami. "We are particularly excited because they have unique properties that make them important players for all sorts of physical and chemical processes going on in space." Buckyballs have already staked their claim in many exciting fields on Earth. We will have to wait and see what they have to tell us about the rest of the universe.

Rogue physicist stokes the Higgs rumor mill.

2010-07-14T13:35:00.009-06:00

For the past week, the physics community has been buzzing about a recent blog post written by Tommaso Dorigo, a member of Fermilab's CDF team. In it, he claimed to have heard "from two different, possibly independent sources" that the infamous Higgs boson may have been detected at the Tevatron within the three-sigma statistical level of confidence (99.73%). The Tevatron is the second most powerful particle accelerator in the world (behind the LHC at CERN) and is located at Fermilab in Illinois. This discovery would be huge news, as the Higgs is one of the most elusive and sought-after entities in modern particle physics.

The Standard Model hangs on discovery of the mysterious Higgs boson.
Image courtesy of Fermilab.

Particle accelerators such as the Tevatron and the LHC were built to probe the Standard Model of particle physics. The Standard Model (see above) describes three of the four forces of nature: Electromagnetism, and the Strong and Weak forces. Gravity is left out, as is the mechanism by which objects in the universe acquire mass. This latter mystery is where the Higgs boson comes in. Although physicists know how most particles interact in order to give rise to such properties as radioactivity and light emission, no one knows where the property of mass comes from. In 1960, Peter Higgs came up with the idea of a field that permeates all of space, much like the electromagnetic field; but instead of gathering electromagnetic energy from photons in this field, particles traveling through the Higgs field would be granted mass by Higgs bosons.

At the moment, Fermilab is denying that any such discovery has been made. On July 12, scientists posted the following via the FermilabToday Twitter account: "Let's settle this: the rumors spread by one fame-seeking blogger are just rumors. That's it." Ouch. Keep in mind, however, that this is the same group who announced they had a 50% chance of detecting the Higgs particle this year. We'll just have to wait and see.

A tiny mistake.

2010-07-07T16:58:00.009-06:00

The proton is one of nature's most famous elementary particles. Solid, stable and always positive, this subatomic celebrity is, quite literally, at the center of everything in the universe. But new research suggests that the proton may actually be smaller than previously thought. If this turns out to be true, the laws of physics will definitely need some rehabilitation.

Excepting dark matter and dark energy, the entire universe is made up of atoms. In the center of each is a small positively-charged core called a nucleus, which is made up of protons and neutrons held together by the strong force. Like a swarm of bees, electrons buzz around the nucleus in different "shells", or energy states. Hydrogen, the lightest and most abundant element, has been exploited by scientists for centuries due to its extraordinarily simple structure: one proton orbited by one electron.

Ionized clouds of hydrogen. Image courtesy of UC Astronomy Dept.

Most recently, researchers at the Max Planck Institute used our atomic minimalist to probe some choice principles of Quantum Electrodynamics (QED), a theory that merges Einstein's theory of special relativity with quantum mechanics. According to QED, an electron orbiting the hydrogen nucleus in the 2S shell will have a different energy than it would if it were orbiting in the 2P shell. This difference is called the Lamb shift, and it contradicts Paul Dirac's original prediction that the 2S and 2P shells should have the same energy. In order to learn more about the Lamb shift, the team at Max Planck replaced the electron in hydrogen with its cousin the muon, a particle that is 200 times as massive and far less stable. When researchers observed the newly created muonic hydrogen, they found that the massive muon orbited the central proton far more closely than the electron did, and was therefore far more sensitive to its size. The team's calculations assign the proton a radius of 0.84184 femtometers (0.00000000000000084184 meters), a number that is 4% smaller than its previously accepted value of 0.8768 femtometers.

4% may not seem like a whole lot, but this tiny miscalculation could have enormous implications for particle physics. If this new result turns out to be accurate, QED and the Standard Model will have to be completely rewritten. No easy task for the most relied-upon theory in modern physics. Quite frankly, scientists may have a revolution on their hands.

The universe, as seen through new eyes.

2010-07-05T11:39:00.006-06:00

The European Space Agency has just released the most sophisticated picture of our universe taken to date. Assembled using strips of data from the Planck satellite, launched in May 2009, this image depicts both the large-scale structure of our own Milky Way galaxy and the Cosmic Background Radiation (CMB) that fills the entire universe. Here, have a look:

Image courtesy of ESA.

The center line that runs through the image is the galactic plane, sprawling across our field of view the same way it does in the sky on a clear night. The wispy, silvery-blue projections extending out of the galactic plane detail the large-scale structure of the Milky Way. But it is the top and bottom of the image, above and below these majestic plumes of gas, that show the real prize: the cosmic microwave background.

Immediately after the big bang, our fledgling universe was nothing but a hot, dense soup of charged particles. At an age of about 300,000 years, the universe had cooled enough for atoms to form, allowing light to travel freely for the very first time. Today, astronomers detect this primordial light as a nearly homogeneous 2.7K radiation that fills the entire sky. (2.7K is incredibly cold, by the way. At less than three degrees above absolute zero, detecting it in the first place is one of the modern miracles of science.) Small temperature fluctuations in the CMB are visible in this image as tiny yellow and green spots. Slightly overdense regions are hotter than the surrounding 2.7K radiation, while slightly underdense regions are cooler. It is these anisotropies that gave rise to all the structure we see in the universe today. Stars, galaxies, galaxy clusters... all of these objects were born of slightly overdense areas of radiation in the very early universe.

You may have seen similar images before. Two previous missions, COBE in 1996 and WMAP in 2003, have already measured the CMB; however, Planck will map this radiation with unprecedented accuracy. Astronomers are hoping that the current mission will allow them to glimpse evidence of inflation, the accelerated expansion the universe is believed to have undergone very early in its development. The stunning image above is only the first of many to come, and is probably the most crude. Researchers will have to eliminate the "noise" caused by the Milky Way if they are to properly map the CMB across the entire sky. Luckily, Planck's refined observations between now and 2012 should allow them to do just that.

For more on the CMB, check out this paper written by an incredibly beautiful, witty and smart young cosmologist.

Nature's symphony heard for the first time, thanks to the LHC.

2010-07-02T22:24:00.004-06:00

Today, I stumbled upon the Coolest Website in the Universe. Don't get me wrong, I have come across some great sites in my time (exhibits A, B, and C). But this one takes the cake.

Since January, a group of physicists, engineers, and musicians have been getting paid to convert data collected at the Large Hadron Collider into music. This isn't just some artist's rendering of the cosmic symphony of particle physics. This is actual science. Using a process called data sonification, the group is creating nonspeech audio that correlates with both real and simulated results from CERN's Atlas detector. Atlas is one of the six projects at the LHC that smashes particles together in order to probe the mysteries of the subatomic world.

A simulated collision of the elusive Higgs boson. Photo courtesy of CERN.

The LHCsounds group has been using information collected by Atlas' calorimeter, a device that measures the energies of particles that collide with the detector. Each collision is assigned a note depending on what kind of particle was involved, where the particle struck the calorimeter, and its energy. Different particles (e.g., protons, electrons, photons) sound like different musical instruments that play more loudly at higher energies. Particles that strike the calorimeter closer to an observer are assigned a higher pitch than those that do so further away. Using this formula, LHCsounds has created quite the arrangement. See for yourself here. Make sure to check out the simulated HiggsJetSimple, as well as CalorimeterEndcapLayers (proton collision) and Top Quark Jet, which were both created from real data at 7 TeV!

Processes like data sonification have the potential to revolutionize the way scientific data is analyzed. But the LHCsounds group claims that this isn't their main goal. Instead, their aim is to share the intrinsic beauty of physics with those outside of the scientific community. I'd say they are doing a pretty good job.

In argument over cosmic fallout, supernovae come out on top.

2010-07-01T10:38:00.012-06:00

4th of July fireworks ain't got nothin on type Ia supernovae. These exploding stars exhibit their catastrophic brilliance in a systematic fashion, allowing scientists to use them as "standard candles" to measure properties of the universe at large. But for such a uniform piece of cosmic machinery, researchers have long wondered why the ejecta of some type Ia supernovae appear to expand at a different rate from that of others. Now, astronomers from the Dark Cosmology group at the Neils Bohr Institute believe they have found the answer.

Type Ia supernovae are born when a small, dense star called a white dwarf accretes material from a companion star. When the tiny dwarf reaches a mass of 1.4 times that of our sun, it can no longer support itself. High density and pressure in the star's core allow carbon to be fused into oxygen in a runaway process and the star explodes into a supernova. Since the white dwarf's mass limit is always 1.4 solar masses, peak luminosity is the same for all type Ia supernovae. By comparing the supernova's known luminosity with its apparent brightness from our position in space, astronomers can easily and accurately calculate its distance from us. Researchers (myself included!) have used the brightness and distance of type Ia supernovae to determine how quickly the universe is expanding, and what proportion of dark energy is causing it to do so.

Double supernova remnants DEM L316. The smaller remnant on the left is believed to be that of a Type Ia supernova. Image courtesy of NASA.

Since stellar explosions of this kind are all presumed to ignite in the same way, researchers had difficulty understanding why the ejected material from some type Ia supernovae appeared to decelerate at different rates. This discrepancy in so-called velocity gradients led some scientists to believe that these objects were not truly "standard candles." But according to new research from Dark Cosmology, white dwarf enthusiasts can rest easily. As it turns out, the team claims, the observed discrepancies between supernovae can be chalked up to our earthly perspective.

It has long been assumed that type Ia supernovae are triggered in the center of a white dwarf, leading to a symmetrical explosion and a homogeneous ejection of material in all directions. But if a supernova ignites at, say, the outer edge of a star, opposite sides of the explosion will progress at different rates. According to Giorgos Leloudas, a member of the team, "What we could see was that the varying natures of the supernovae could be explained by an asymmetric explosion, where the ignition takes place away from the centre." Whether astronomers observe a high-velocity or low-velocity gradient in the star's ejecta depends on which side of the supernova faces Earth. This conclusion reaffirms the role of type Ia supernovae as the universe's standard candles and, in turn, bolsters the case for dark energy. The team's research is published in the July 1 issue of Nature.

One of these things is never like the other.

2010-06-30T19:45:00.002-06:00

Orville Wright once said, “If we worked on the assumption that what is accepted as true really is true, then there would be little hope for advance.” Presumably, this was the rationale behind a recent experiment conducted by a team of particle physicists at the University of California, Berkeley. Scientists operate on the assumption that all of the known subatomic particles fall into two distinct categories, bosons and fermions, whose respective properties are unique. If even one boson was to be observed to be acting under the laws that govern fermions, the whole of the Standard Model of particle physics would collapse. Fortunately, the UC Berkeley physicists have concluded that bosons - specifically, photons - never act like fermions. Ever.

Two photons of different wavelengths.
Image courtesy of NASA/Sonoma State University/Aurore Simonnet.

From the forces of nature to the basic constituents of matter, the Standard Model explains everything we think we know about our world. For instance, matter arises from different configurations of two groups of fermions: quarks and leptons. Quarks are the particles that make up protons and neutrons, while leptons are stand-alone particles such as the electron. The Standard Model also tells us that there are four basic forces: the strong and weak nuclear forces, electromagnetism, and gravity. These forces operate by exchanging bosons such as the gluon, the W and Z particles, and the photon.

Bosons and fermions behave according to the laws of quantum field theory, the physics behind the Standard Model. Each has a property called "spin," which defines its intrinsic angular momentum in terms of a number. Bosons are only allowed to have spins that are integers, e.g., 0, 1, 2, 3. Fermions can only have half-integer spins, e.g., 1/2, 3/2, 5/2. In quantum field theory, this is called the Spin-Statistics Theorem. Another difference between the two lies in their configuration; namely, that no two fermions can occupy the same quantum state. This is why the electrons in an atom arrange themselves in separate shells around the nucleus. Bosons, however, can share a single quantum state. This is the phenomenon behind laser beams and Bose-Einstein condensation.

The idea behind the experiment at UC Berkeley was to try and violate the Spin-Statistics Theorem and thus disprove the distinctness of bosons and fermions. The scientists fired two lasers at a group of barium atoms in order to see whether any electrons in the barium would be excited to a higher energy level. The transition they were looking for occurs when two photons are absorbed at once, and is forbidden to bosons (like photons) by the Spin-Statistics Theorem. According to Damon English, a post-doc with the Berkeley group, if photons acted like fermions, the transition would "go like gang-busters." But it didn't. Not one two-photon absorption was observed. The researchers thus concluded that our understanding of the Spin-Statistics Theorem is sound. "Photons are bosons," claimed English, "at least within our experimental sensitivity."

Was there once life on Venus?

2010-06-26T21:47:00.008-06:00

Of our two planetary neighbors, Mars was always the favored child, making headlines year after year as scientists alternately bolstered and debunked claims of its habitability. Meanwhile, Venus sat idly by - gaseous and fuming, nothing but a bright "star" in the early morning and evening skies. But all that might be about to change. For the last four and a half years, the Venus Express satellite has been gathering data that suggests that, at one time, the gassy planet may have supported liquid water.

Image courtesy of NASA.

Today, Venus is an oppressive and stormy place. With an ambient temperature hot enough to melt lead, surface pressure comparable to the depths of Earth's oceans, and an atmosphere composed mainly of carbon dioxide and sulfuric acid, Venus is an inconceivably inhospitable place for life to thrive. However, this was not always the case. The Venus Express satellite has detected large amounts of hydrogen and oxygen escaping into space from the Venusian atmosphere; more specifically, two molecules of hydrogen for every one molecule of oxygen. Sound familiar? It should. Liquid water, or H2O, shares this exact ratio and evaporates into its constituent gases when struck by UV light from the sun. Current research implies that most of this water was probably atmospheric, but it does not rule out the possibility of ancient oceans on the Venus' surface. Water is thought to be a crucial ingredient for the evolution of carbon-based life forms, making the existence of standing water on Venus at some point in history appealing to astrobiologists studying the origin of life in the solar system.

Physiology of a Suntan, or Why I Am So Red.

2010-06-25T23:04:00.011-06:00

Image courtesy of Vox Efx.

As I lay out in the blazing 100-degree sun today, I started wondering exactly what was happening to my skin on the microscopic level. Welcome to my nerdy daydreams. As it turns out, my mental image of thousands of tiny cellular defenders banding together in formation to fire missiles at hoards of incoming free radicals isn't quite right.

As we all know, sunburns and suntans are caused by the sun's ultraviolet radiation (UVR). There are two types of UVR that can penetrate the earth's atmosphere: UVA and UVB. UVA rays are the most prevalent, no matter the season or time of day, and are responsible for wrinkles, sunspots, mottled, droopy skin, and other signs of aging.

Skin cells under a microscope. Image courtesy of euthman.

UVB rays, on the other hand, are responsible for sunburns and suntans. Upon contact with UVB light, skin cells called melanocytes begin producing melanin, a pigment that darkens the skin and absorbs harmful radiation before DNA damage can occur. UVB rays prompt the secretion of MSH, or Melanocyte Stimulating Hormone, from the pituitary gland. MSH binds to a receptor on the surface of melanocytes, triggering melanogenesis through the release of a chemical called cAMP. The more cAMP that is present, the greater the amount of melanin that is synthesized. Once melanin is released from the melanocytes, it is transferred to surface skin cells called keratinocytes that darken and give skin its tanned appearance. In fair-skinned individuals, MSH cannot bind to its receptor as effectively, so less melanin can be produced. With less melanin, UVB rays can easily strike melanocytes and keratinocytes, causing nuclear damage and inciting an inflammatory response, which we call a sunburn. Generally speaking, Caucasians have less melanin than other, darker-skinned populations and so tend to have higher incidences of sunburn and skin cancer.

Take it from me, the fair-skinned hypocrite who forgot to reapply her sunscreen today: sun damage takes its toll over time and can even be fatal. Take action to protect your skin, and keep those nasty photons away from your melanocytes.

A star is born: Infant star causes a stir in the astonomical community.

2010-06-20T18:12:00.002-06:00

Call it slapping hydrogen gas on its proverbial butt. A team of American and German astronomers has announced its observation of the youngest known stellar object ever, according to a paper published in the most recent issue of The Astrophysical Journal. The fledgling star bears the poetic name L1448-IRS2E and was observed developing in the Perseus star-forming region, 800 million light years away. Stellar objects of this age are notoriously difficult to observe because they are not yet true stars and do not give off much light. The team of astronomers discovered L1448-IRS2E by detecting radiation emitted by dust surrounding the object.

A group of young stars in the Perseus constellation. Image courtesy of NASA.

Stars form out of molecular clouds when an overdense area of hydrogen begins to collapse under the influence of gravity. As the clump of gas becomes more massive, it begins to draw in gas and dust from the surrounding area. This "prestellar" phase lasts until the object forms a core that is dense and hot enough to fuse hydrogen into helium. It can then be called a protostar. Due to high-velocity streams of gas being ejected from its center, L1448-IRS2E is believed to have passed the prestellar phase; however, it is not emitting enough light to truly be called a protostar.

The object was originally discovered using Nasa's Spitzer Space Telescope and the Submillimeter Array in Hawaii. The team plans to continue observing with the newly launched Herschel telescope and hopes that its research will shed some light on the mechanics of early stellar evolution.

Exotic form of matter falls 33 stories and lives to tell the tale.

2010-06-19T17:02:00.013-06:00

General relativity is to quantum mechanics as oil is to water. Since the 1930s, physicists have been trying, unsuccessfully, to unite the two disciplines in an effort to explain the physics of both the very large and the very small. Now, almost a century later, scientists are beginning to take drastic measures. For instance, a team at the University of Hanover in Germany recently hauled a very expensive piece of technology down a 110-meter long shaft just to see what would happen.

The idea behind their experiment was to create a strange state of matter called a Bose-Einstein condensate (BEC) and to test its behavior during free fall. First created in 1995 at the University of Colorado at Boulder, a BEC is an extremely cold collection of atoms that magnifies the strange world of subatomic physics. How? When certain gases are cooled to near absolute zero, some of the atoms in the gas are able to occupy the same quantum state. They coalesce to form a visible super-atom, allowing scientists to observe quantum fluctuations on a macroscopic scale - in this case, during 4.7 seconds of free fall. According to Einstein's Equivalence Principle, the conditions experienced during free fall are identical to those felt in an environment without gravity. Experiments such as the one conducted by the Hanover team may shed light on whether quantum mechanical systems obey the same rule. If they do not, it could indicate new hope for the marriage of quantum mechanics and gravity.

A Bose-Einstein condensate created from rubidium atoms. The three diagrams show material gradually condensing in the blue and white regions. Image courtesy of NIST.

180 drops later, the experiment concluded without a hitch. The team next plans to split the BEC and repeat the experiment, sending each half along a different trajectory. Any differences in the motion of the two halves during free-fall would indicate an exception to the Equivalence Principle at the subatomic level and might help to spawn a new theory of quantum gravity.