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

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.

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.

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.

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.

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?

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.