The Little Rovers That Did

July 7^th, 2003. A one hundred ton Delta II rocket streaks from Cape Canaveral into the night sky, carrying an advanced robotic explorer destined for Mars. The rover is named Opportunity, and together with its brother Spirit which launched the previous month, it will undertake the most extensive exploration of another world in human history.

Those watching the launch from the parks nearby might be forgiven for envying those skyward explorers. Planet Earth has had a rough ride, recently. The tragedy of the September 11 attacks has shattered the comfortable status quo of the post-Cold War world, leaving the War on Terror in its place. The invasion of Iraq is only 4 months old, and it's just becoming apparent that “mission accomplished” will require more than regime change. Anxieties are high and the battle lines that will define a decade of upheaval, at home and abroad, are being drawn. And hidden deep within the arcane world of global finance are the seeds of a crisis which will further define a generation.

Spirit and Opportunity are running about as far as its possible to go, but they've had to overcome obstacles of their own to even get this far. “That they were in Florida at all,” recalls Dr. Steve Squyres, principal investigator of the Mars Exploration Rover program and author of Exploring Mars, “was a small miracle.”

Just 4 years previously, in late 1999, two NASA spacecraft disappeared in the final stage of their journey to reach Mars. It was a humiliating blow for the Mars program, not least because of the reason for one of the losses: miscommunication between two teams using imperial and metric units. That elementary error, common in high school science classes around the country, caused an ignominious end to a 700 million dollar program, and left the Space program with something to prove. Mars missions, not easy to fund in the best of times, would face uphill battle to convince NASA and the American people that they were worth the risk.

Still, there was a lot of interest in exploring Mars, thanks to the discovery of what appeared to be fossilized bacteria on Martian meteorites. Mars had always been the nearest, most accessible candidate for planetary exploration, and it looked like it was also the best place to look for extraterrestrial life. The Mars Pathfinder mission, with its charismatic rover Sojourner, had been a great success, so in 2000 NASA approved another rover mission to Mars. The team who would build it now had three years to design and build a rover which could operate in frigid Martian weather, survive the trip through space, and a plunge through the atmosphere. To increase the odds of success, NASA asked them to build 2 rovers.

It was an ambitious plan. At the Jet Propulsion Laboratory in Pasadena, CA, the nation's top space engineers and scientists worked around the clock to solve the problems and invent the technologies that would make the vision a reality. For a nation flush with budget surpluses and still riding high as the world's only superpower, it seemed just this side of possible.

A modern spacecraft contains innumerable moving parts, computers, and instruments, and not all of them are made in the same place. Spirit and Opportunity had cameras manufactured at Arizona State University, a spectrometer from Johannes Gutenberg University, Germany, and a specialized drilling tool from a company called Honeybee robotics, located in New York city about a mile away from the World Trade Center towers.

On September 11^th, 2001, 2 planes crashed into the World Trade Center buildings, killing almost 3000 people in what instantly became the defining moment of a generation. In the fallout from the tragedy, people all over the world felt helpless. At JPL, the idea of using Spirit and Opportunity as memorials for the events of that day was suggested, and quickly picked up steam. A month and a half later, an aluminum plate was delivered to the Honeybee building and quickly reforged into cable shielding for the rovers, which would protect their delicate wires from impacts. To this day those two components solemnly sport American flags, memorials to the victims of that horrible day standing at the far edges of human endeavor.

In the following years the technologies grew and the rovers gradually took shape. In the wider world, the US invaded Afghanistan, then Iraq. The Euro became the official currency of 12 EU nations, gradually growing to include several more. On February 3, 2003, the space shuttle Columbia broke up during reentry, killing all 7 members of the flight crew.

Still the crew of the Mars Exploration Rover team soldiered on, working to meet the launch window. It was a nonnegotiable deadline, resulting from a rare conjunction of the planets. Any delay would push the mission back to 2005, with serious ramifications for the likelihood of success.

So while the spectacle of Spirit's departure from our planet on July 3, 2003 was incredible for anyone watching, it was especially poignant for the team who slaved over the two rovers in the first place. It was out of their hands, now, embarked on a journey that would take it unthinkably further than even the Apollo astronauts had ever gone, so far that light itself would take up to half an hour to make a round trip.

It took 6 months to make that trip, 6 months of patient (and, one can imagine, at times not so patient) waiting until that most nerve-wracking of moments, planetfall. Planetfall occurs when the spacecraft transitions from spaceflight to becoming a lander, impacting the atmosphere in as controlled a manner as possible so that it slows down enough to reach the surface without splattering into it. As if to emphasize the danger inherent in this complex maneuver, the European Space Agency's Beagle 2 lander suffered a catastrophe during landing on December 25, 2003, just 11 days before Spirit was scheduled to land. It was never heard from again, and presumed to have impacted the planet at too high a velocity.

Finally, the day came. Press from around the world surrounded the command center at JPL, waiting for images from the red planet or news of another disastrous failure. It is probably fair to say that the future of the Mars program in general, at least for the near future, rested on the successful landing of the rovers and completion of their 90 day mission. Failure would mean no more political will to extend humanity's reach on our nearest neighbor, especially in light of the Columbia tragedy. Success could mean proof of water on Mars and scientific strides that might pave the way for a manned mission.

On January 4^th, 2004, Mars Exploration Rover A, Spirit, touched down successfully at Columbia Memorial Station, a landing site named in honor of the fallen space shuttle. Spirit then broadcast the highest resolution image ever taken of another planet, a panoramic color view of the landing site. It was all that was needed to declare the landing a success. Now came the hard work of 90 grueling days of mission operation, with the scientists and engineers of the project living on the same 24.5 hour day that the rovers were experiencing. Spirit might have been alone on the surface of an alien world, but JPL staff were joining it every Martian morning by virtual commute from California to Mars.

The next few days proved to be tricky. Identifying potential sites of interest for the rover to examine had just begun when contact with the rover was lost. A few blips of data were received now and then, but what was originally thought to be a weather disturbance quickly became a threat with the potential to end the mission before any of its scientific objectives were realized. Worse, Opportunity was fast approaching the planet, and the engineers who needed to focus on its equally risky landing were distracted by the problems with Spirit.

On January 25^th, Opportunity experienced a picture-perfect landing, arriving in the middle of an unexpected crater of geological interest. It was named Eagle Crater, and the rover scientists called the landing an interplanetary “hole in one”. With the world caught up in concern about avian flu emerging in South Asia, Spirit was also back up and running by early February. It was a good month for the space program.

On March 11, 2004, Spirit transmitted the first image of Earth taken from another planet. The symbolism of that gesture, looking back at the fragile vessel which holds our collective histories, was undermined by the simultaneous bombings of numerous commuter trains in Madrid, killing 191 people and injuring almost 2,000 more, that very same day.

In April of 2004, with the US just getting down to the business of the oncoming Kerry versus Bush election, both rovers surpassed the guideline NASA had set out for a successful mission by operating for 90 days on the Martian surface. Because the rovers are solar powered, it had been anticipated that dust buildup would prevent the rovers from operating long past that point. NASA planners judged that 90 days of operation would justify the expense and risk of the mission.

Spirit lasted for 2210 Martian days (more than 5 years), and Opportunity remains operational as of the end of 2011, trekking across the Martian surface in pursuit of new regions to explore. During that time they greatly expanded our knowledge of the Martian surface, including close up views of conclusive evidence that water once existed on the Martian surface. Those years were filled with many other milestones, both for the intrepid rovers on Mars and for those of us still on Earth.

In January 2005, Opportunity identified the first ever meteorite found on another planet. Both it and other space probes had investigated craters before, but this was the first time that an actual meteorite was scene and examined on a world other than earth.

On March 10, 2005, Spirit photographed a dust devil moving across Mars in a rare and lucky break. A similar event was probably responsible for clearing much of the dust that had been accumulating on its solar panels, probably increasing the lifetime of the mission significantly. Here on Earth, CBS Evening News anchor Dan Rather signed off for good that same night.

During 2007, Opportunity explored a feature known as Victoria crater, which provided natural cross-sections of Mars rock strata. During this time, both it and Spirit weathered massive planet-wide dust storms which threatened to cut off their power supply completely. The scale of these dust storms are unprecedented here on Earth, as they affected both of the rovers for the entire month of July, despite the fact that they were on opposite sides of the planet. It was a stormy month here on Earth, as well, as fatal bombings rocked London's mass transportation, a mall in Israel, and a resort town in Egypt.

Nothing lasts forever, and despite the machines' incredible hardiness the years took their tole. On May 1, 2009, after five years of operation, the rover Spirit became stuck in abnormally soft sand hidden just below the soil surface. Over the course of the next year, engineers attempted to extricate the rover until it was declared a mobile research platform on January 26, 2010. A few months later, on March 22, the last communication from Spirit was received. Attempts to reestablish communication would continue until, 3 days after the supposed date of of the Christian rapture (famously predicted by Harold Camping), Spirit was officially given a farewell on May 25^th, 2011.

Opportunity is still chugging along, and participated in more milestones over the next year. In August it arrived at Endeavour crater, the culmination of a 3 year, 13 mile trek across the Martian landscape. In September it photographed the section of its assembly forged from debris from the World Trade Center towers, in commemoration of the tenth anniversary of that tragedy. Then in December, it broadcast an analysis of a vein of rock it identified as gypsum, in what has been called “slamdunk” proof that liquid water once flowed on or through Mars. Its mission of exploration continues into the new year, and beyond.

On November 26^th, 2011, the Curiosity rover was launched from Cape Canaveral and flung out towards Mars. Its mission is similar to the rovers that preceded it, though it is larger, more capable, and packed with more instruments than they were . It's mission is also more explicitly aimed at gathering data to help in ongoing planning for an eventual manned mission. Without the success of the Mars Exploration Rovers that preceded it, it would never have gotten off the ground.

With everything demanding our attention here on Earth, it is understandable that many people want to devote the resources we have to addressing problems close to home. In an earlier world, with our country flush with prosperity and facing down the Soviet Union, an extravagant space program was perhaps a luxury we could afford. But we no longer live in that world.

It's sometimes hard not to feel that ours is a nation, even a world in decline. The steady drumbeat of conflict, global warming, economic problems, and doomsaying takes its toll. The zeitgeist is full of anxiety that our ambitions for the future must be less than the triumphs of our history.

Spirit and Opportunity were born in that world, even if they were destined for another. The people who gave them life knew that their mission was do or die, either redemption for a program haunted by high profile failures, or proof that it was too risky and expensive to justify. They poured their lives into succeeding where many had failed before, on a scale that was unprecedented, with a time limit that seemed frankly impossible. Then they did it twice.

That they succeeded at all isn't just impressive, it is inspiring. That they succeeded so far beyond even their most optimistic dreams is incredible. The story of Spirit and Opportunity is a true epic, an untold story of triumph in a decade of upheaval and tragedy.

The world spins. Governments rise and fall, fortunes are swindled, and network news blares about a new study detailing the dangers of red meat. Two hundred million miles away, the most hard working astronaut in history patiently sifts through rock samples under an alien sky, waiting for a time when its human comrades can join it among the stars.

Faster than light

Albert Einstein once famously remarked of his theory of relativity, “No amount of experimentation can ever prove me right; a single experiment can prove me wrong.” Now, a particle apparently traveling faster than the speed of light may prove him prophetic even as the theory for which he is most remembered faces a new challenge.

The particle in question is called a neutrino, and its velocity was measured over a journey between CERN laboratories near Geneva all the way to a lab in Gran Sasso, Italy, about 730 km away. Investigators working on the project found the particles arriving sixty nanoseconds earlier than they should have been, an amount of time so tiny that it happens seven and a half million times in the time it takes to blink your eyes. That amount of time may seem miniscule, but tiny numbers tend to carry outsized importance in the world of modern physics.

It is not yet clear what the implications are if this measurement is correct; the speed of light is a foundation stone of modern physics, an inviolable speed limit that has withstood half a century of determined scrutiny by the best minds and most advanced instruments in the world. Yet it might be too soon to write an obituary for the theory of relativity. The equipment used for this experiment is among the most advanced ever constructed, but new technology means potentially untested sources of experimental error. And neutrinos themselves are an elusive quarry, having earned the nickname “ghost particles” for their spooky ability to pass through solid matter and, now perhaps, travel through time.

While physicists rush about confirming or falsifying the basis of the experiment, it is interesting to peek ahead at what bizarre new shapes reality might be taking if it all turns out to be true. To get to that point, it behooves us to understand how modern physics sees the world today.

Through Space and Time

Ever since Einstein, physicists have modeled the universe as consisting of four visible dimensions: the three of space and an additional dimension for time. An object has a set amount of “speed” available to move through the dimensions of space and time. One of Einstein's great insights was the realization that the two types of speed are interchangeable, that is by moving quickly through space you must consequently move more slowly through time.

In our everyday lives we have relatively little movement in the three spatial dimensions, and move through time steadily and inexorably. Only at so-called relativistic speeds (near the speed of light, not coincidentally) does the passage of time noticeably slow. At these velocities you actually age slower relative to someone at rest. Put another way, if you travel at a fast enough speed away from a friend who stays motionless, and then return to where you started, the two of you will disagree about how much time has passed.

There is of course a natural limit, a speed at which you are moving so quickly through space that you no longer experience the passage of time, having “borrowed” all movement through the time dimension. We call that upper limit the speed of light.

To illustrate this principle, let's imagine a universe where relativity reigns and the speed of light is 10. We won't worry about units in this example. Thanks to Einstein we know that you move through both space and time simultaneously, so the sum of your speed through space and through time must always equal 10. In this linear universe you can be moving quickly through one, but as a result your speed through the other will be lower such that they always add up to 10.

When standing still you move through time with a speed of 10 (0+10=10). If you are traveling at a modest speed of 2 through space, you experience slower time than when you were standing still, at 8 (2+8=10). If you reach the speed of light, 10, you do not travel through time at all (10+0=10) since all of your motion is devoted to travel through space. Time stops for you when you travel at the speed of light.

This surprising phenomenon is one of the most famous consequences of the theory of relativity, which Einstein derived from a series of thought experiments in 1905. Since then, its conclusions have been corroborated time and time again in physical experiments, including the observation that time slowed (minutely) for astronauts on the Apollo missions. The framework of modern physics has been built on relativity, and central to the theory is the speed of light (in a vacuum) as the universal, inviolable speed limit.

What were to happen if something could exceed the speed of light? Taking our example universe from above, lets look at an object traveling through space at speed 11. We already established that the object's combined speed through time and space must be equal to 10, so its movement through time must be a negative number, -1, to make the math work. In other words, the object must be traveling backwards in time!

There are further problems with accelerating a mass to the speed of light. For one it would require infinite energy. Infinities in physics are warning signs. When you see one of them pop up, then it's either impossible, the question you are asking is nonsense (what color is jazz music), or the theory you are using just can't deal with the answer, and you need a new one to fill in the gaps.

Photons (light) and other massless particles cheat because they never have to accelerate to the speed of light. Their lack of mass means that they constantly zip around at the universe's speed limit and can never slow down. Thus the speed of light isn't a speed limit because light is special, with nothing allowed allowed to move faster out of respect. Rather light happens to travel at the fastest speed that is possible, because it has no mass and therefore nothing to slow it down.

This is why the speed of light is not a speed limit like you see on the highway or a barrier like the speed of sound; those limits can be broken with effort or if you are comfortable risking a moving violation. The speed of light is a constant, arrived at through theory and confirmed experimentally, which can't be exceeded without implying spooky things like time travel and the loss of causality. Causality is what makes action lead to reaction, and without it consequences are free to precede the act that caused them. If that turns out to be the case then, in the words of Subir Sakar, head of particle theory at Oxford University, “We are buggered.”

Extraordinary claims, extraordinary evidence

Scientists haven't given up on an understandable universe, yet. The most likely explanation for the faster-than-light neutrinos is simply that there are problems with the experiment that have gone thus far undetected. The investigators were aware of the skepticism likely to meet their announcement, and of astronomer Carl Sagan's famous and relevant aphorism that “extraordinary claims require extraordinary evidence”.

A particle exceeding the speed of light is certainly an extraordinary claim, and the researchers were extremely careful to examine their data errors before presenting it. Their observations are the result of three years of observations and calculations by hundreds of scientists doing their best to prove the strange result wrong. Still, the possibility of error cannot be dismissed until the results are corroborated by another independent experiment. Other labs around the world are likely to begin efforts to replicate the experiment, but may take years to definitively uphold or dispel the results.

In the meantime, there remains the possibility that the results are real, and that neutrinos may travel faster than the speed of light. A number of theories exist that might explain how this is possible, though all are highly speculative. Some of them admit the possibility of time travel, some rely on exotic possibilities like hidden spatial dimensions and wormholes. Before we explore those, however, it might help to understand a bit more about the strange world of neutrinos.

Ghost Particles

The existence of the neutrino was inferred by physicist Wolfgang Pauli in 1930, long before one was ever observed. He noticed some energy going missing during the process of beta decay, a radioactive transformation of one element into another. Since energy can't be destroyed, Pauli theorized that this energy was carried away by a neutral particle which was invisible to the detection techniques of the time. This explanation was eventually accepted by the physics community, but a neutrino wasn't officially detected until 1956.

Twenty six years is a long time to look for something, but neutrinos are elusive quarry. They are very small and carry no electric charge, meaning that they barely interact at all with the type of matter that makes up ourselves and the world we inhabit.

Tap a table with your knuckle or hit your head on a rock and you get the definite impression that they are solid. That is because you are made of the same stuff they are. The atoms in your head, the rock, and all matter consist of two parts. The first is a dense and very small nucleus, which takes up about a millionth of a percent of the volume of an atom, but well over 99% of its mass. The rest of the mass is spread amongst a fuzzy cloud of electrons, which composes the vast majority of an atom's volume.

The illusion of solidity is the result of electron clouds' very strong dislike of each other. Electrons are negatively charged, which means they repel each other vigorously and refuse to share the same space. As the electron clouds which make up a rock meets the electron clouds of another object, say your head, the combined violent repulsion between the two groups rebound against the motion, leaving you with a headache and the very strong conviction that matter is hard.

Neutrinos are very different. Since neutrinos have no charge, electrons don't repulse them the way they do each other, and neutrinos pass right through the diffuse haze of electron cloud. The nucleus is solid and dense enough to stop an incoming neutrino, but the chance of one directly impacting the miniscule nucleus is so small that such events are rare. Thus neutrinos can pass through seemingly solid matter as easily as a bullet passes through fog. In fact about 65 billion neutrinos pass through every square centimeter of your body every second on their way from the sun to deep space, and you never notice a thing. Those neutrinos will continue through you, through the earth, and out the other side unimpeded, a property which has earned them the nickname “ghost particles”.

Fifty years after first observing neutrinos, there is a lot we still don't know about them. Originally it was thought that they had no mass and thus traveled at the speed of light, as photons do. Later theories suggested that the neutrino had a small amount of mass and traveled at near but slightly below the speed of light, since particles with mass cannot accelerate to the speed of light. Since we can barely detect neutrinos, it has been quite difficult to pin down their speed, but a fortunate event almost 25 years ago provided a large clue.

On February 23, 1987, at 7:35 a.m. UT, three separate neutrino detectors around the world recorded a 13 second burst of high energy neutrinos far in excess of normal background levels. Three hours later, light from the supernova SN 1987A reached earth after traveling through space for approximately 168,000 years. The supernova was visible to the naked eye and provided astronomers with a rare treat, but proved equally important for physicists looking to measure how fast neutrinos move.

At first glance, it seems like the fact that neutrinos beat the light from the supernova to Earth might support a faster-than-light speed for them. It turns out, however, that this delay was predicted and explained by existing theories. The earliest stage of a supernova includes a massive burst of neutrinos, which may carry away 90% or more of the total energy of the blast. This is shortly followed by a burst of electromagnetic radiation, including light, which is further slowed down (attenuated) as it passes through the gases and debris ejected by the star prior to the supernova. The end result is that neutrinos should form the blast front from a supernova, with light lagging slightly behind, just as predicted. If the measurement of neutrinos' speed made at Gran Sasso was correct for neutrinos in general, the neutrino shockwave would have arrived 18 months ahead of light from SN 1987A instead of 3 minutes. Explaining this discrepancy is one of the greatest challenges facing theorists if the CERN measurement turns out to be correct.

It turns out, though, that there are other glimmers suggesting that neutrinos might not follow posted universal speed limits.

In 2007, a neutrino detector in Michigan measured the speed of incoming neutrinos generated by Fermilab, a high energy physics laboratory in Chicago. The researchers running the experiment measured the neutrinos' speed as slightly above the speed of light, but determined that the inherent inaccuracy of the experiment (the error) was most likely to blame for this seemingly impossible number. In their report they said as much and the scientific community moved on, but the measurements made in Europe cast the possibility of faster than light travel in a more favorable light. Efforts are now under way at Fermilab to update their apparatus to independently verify or dispute the results of the CERN neutrino experiment.

Either way, it seems that neutrinos travel at least at the speed of light, but other experiments suggest that they also have a small but very real amount of mass. Given that an object with mass needs an infinite amount of energy to accelerate to the speed of light, how is this possible?

By never accelerating the neutrino in the first place. There is a loophole in the nature of relativity that can be exploited to allow an object with mass to simultaneously move at the speed of light, provided that object only ever travels that fast. It can never travel slower, never speed up, but like the photon is stuck at one speed from the moment it comes into being to the time it is absorbed or decays.

There are, then, suggestions that our understanding of relativity and the universal speed limit are incomplete, and that neutrinos may be a gateway to investigate further. What if further testing corroborates these faster-than-light neutrinos? If neutrinos can travel faster than the speed of light, is relativity wrong, time travel possible, and every facet of our grasp on reality blown to smithereens? Well . . . probably not.

The shoulders of giants

Scientific progress has not been a smooth road. At infrequent intervals, truly revolutionary discoveries are made which change the context of everything that came before them. Very rarely, however, do they wipe away previous theories entirely. Rather they serve to clarify and extend those theories, offering insight into their underlying reality or expansions of their scope without rendering them entirely invalid.

When Newton formulated his theory of gravitation, it was widely hailed as a breakthrough of historical proportions, for good reason. The movements of planets and stars, comets and fastballs, which had been puzzles since time immemorial, were made explicable by a single, elegant set of mathematical equations. As the theory spread into wide acceptance, many scientists confidently predicted that the universe would be understood in its entirety through mathematical expressions by the end of the nineteenth century.

There was one small hitch in this coup of rationality, namely the erratic orbit of the planet Mercury. The closest planet to the sun, it refused to behave like its brother and sister celestial objects and danced to its own beat, one which unfortunately seemed incompatible with Newton's formulation of gravitation. It wasn't a fatal problem, since Newton's theory held true for every other body in the observable night sky, but it bothered physicists and astronomers greatly.

The solution to this riddle came with Einstein's theory of relativity, which describes gravity as the result mass deforming spacetime in its vicinity, much like a heavy metal weight deforms a rubber sheet it is placed on. Under normal conditions the mathematics of the two theories agree. In regions of high gravity, such as near the sun, predictions made by relativity differ from classical mechanics in small ways, ways that neatly explain Mercury's aberrant orbit. It was an early coup for Einstein's theory and a tectonic shift in our view of the universe, but not one that displaced Newtonian mechanics. Rather it updated old theories, defining their limits without throwing them away.

Faster than light particles notwithstanding, it has been known for decades that relativity is, itself, an incomplete theory. At very small scales and very high energies it gives way, predicting nonsensical infinities and generally becoming an indecipherable mess. Much of late twentieth century physics to the present has been devoted to searching for an expanded theory which explains these discrepancies, updating and smoothing over relativity in the same way that it had modified theories that came before. But laboratory measurements have stubbornly refused to single out such a theory from the many possibilities that have been proposed.

Might the discovery of speeding neutrinos be the break physicists need to fill in our understanding of the universe? What mind-bending new ideas might we be forced to reckon with when that understanding comes? Most importantly, does it mean anything to the rest of the world, or is it only of interest to the ivory towered world of advanced physics?

A shortcut through dimensions

When, 168,000 years ago, the star SN1987A exploded, humans had only recently evolved on Earth. The shock wave from the supernova traveled for the next 168 millenia, spreading out the entire time, until finally reaching Earth. Even in this diminished state, the blast briefly outshone the entire rest of the universe combined (minus the sun, which is so close to the Earth that it's really cheating). The explosion was a titanic release of energy that truly beggars the imagination.

The CERN facility that produces the neutrinos for the Gran Sasso detector sends them off with a hundred times the energy as those launched from that dying star.

The supernova produced far more total energy, of course, by virtue of the massive number of particles involved. But the higher energy per particle produced at CERN may hold the key to explaining why neutrinos in the laboratory seem to behave differently than those observed in the universe, and that brings us to our first possibility for how the seemingly impossible neutrinos might be explained. To picture this we need to borrow a concept from theoretical physics known as M-theory.

Our universe, the only one we know about, has 3 spatial dimensions and a fourth we know as time. In other words, things not only have width, they have height and length and are located in different places at different times. But the fundamental theories of physics don't require 4 dimensions to work. Mathematically they work equally well in 5 or more dimensions, and it turns out that many of the problems facing modern physics can be at least partially explained by assuming the existence of more spatial dimensions beyond the 3 we know, that have somehow remained hidden from observation.

M-theory proposes the existence of no fewer than 11 total dimensions. Within that enormity our own universe may float like a plastic bag adrift at sea, or those dimensions might be rolled up in minute “strings” that stretch throughout the tiniest reaches of reality. The theory also predicts that these dimensions might become observable when sufficiently large energies are involved, such as those present in the particle colliders that produce neutrinos. It's a strange concept to be sure, but par for the course when touring the world of theoretical physics.

Leaping the Gap

Like a car traveling across a valley, a neutrino may travel along the surface of our universe or it may “jump” from one side to the other through the extra dimensions in between. It appears to move faster than the speed of light because it has a shorter path to follow than its low energy companion.

How does this help to explain the faster than light neutrinos? Remember that the neutrinos created at CERN are released with about one hundred times the energy of those from a supernova, a powerful burst not seen since the birth pangs of the universe. At those energies the neutrinos might vibrate with energy so intensely that they temporarily vibrate out of our 3-D universe entirely, cutting briefly through hidden extra dimensions of reality before dipping back into ours.

To an outside observer it might appear that the neutrino moved faster than light if the particle happened upon a shortcut during its brief hop out of our universe (see sidebar). In visualizing this , an analogy might help. Imagine our universe as a flat surface, like the surface of the Earth. Everything that happens in the universe takes place on this surface, while the air that surrounds it represents the extra dimensions proposed by M-theory. Those extra dimensions are normally inaccessible to the residents of our world, who have yet to invent air travel, and they must get from place to place by following the natural contours of the surface.

In some places, like a valley, the surface of this universe is naturally curved. Residents of the universe will travel from one side of the valley the long way, from top to bottom to top, without ever realizing that there is a shortcut through the air above them. If one of their vehicles could be imbued with enough extra power, say by a ramp and a turbocharged engine, they could temporarily leap out of their universe entirely and into the air, crashing down on the opposite site of the gorge. To an observer on the far side of the valley it would seem that the airborne pioneer was able to move much faster than his earthbound companion, even if he never actually reached a higher speed, because he took a shorter path to the other side.

In essence, by producing neutrinos imbued with such large amounts of energy, the researchers at CERN may have supercharged them enough to bounce in and out of our 3-D world. They appear to us to be moving faster than the speed of light, though from their perspective they have merely taken a shortcut.

Tiny wormholes

There is more than one way to take a shortcut through the world of the subatomic. Consider the wormhole, a staple of speculative fiction with a pedigree reaching back to Einstein himself. In its basic form a wormhole refers to two regions of spacetime which are pinched together, forming a bridge that offers a shorter path between two points than is normally available. Like with the previous scenario, an object passing across that bridge wouldn't technically exceed the speed of light, but it could traverse two distant points almost instantaneously.

Small Tunnel Ahead

Wormholes have been theoretically described since the 1930s, but never observed. It may be that small, energetic particles can traverse microscopic wormholes while larger, slower particles will not fit.

While the theoretical basis for the existence of wormholes is sound, one has never been observed. This could be because they form on scales too small or too brief for current instruments to detect. A neutrino, thanks to its small size, might be able to slip through one of these tiny, short-lived wormholes for just long enough to spurt ahead, again fooling an observer into believing that it has moved faster than the speed of light. Larger and less energetic particles, like those that make up matter, can't fit through these wormholes and are doomed to taking the slow path.

Unfortunately neutrinos aren't the only small particles, and there is no obvious reason why faster than light behavior of this kind shouldn't be possible for particles of similar size, like electrons. Given the vast amount of attention that has been devoted to such particles, it is suspicious that none of this behavior has been heretofore observed. If there is something special about neutrinos that predisposes them to skipping across the surface of dimensions, or tunneling through microscopic wormholes, theory has yet to describe it.

Both theories, involving hidden dimensions and tiny wormholes, exploit loopholes in the theory of relativity to move between two points more rapidly than light can, without locally exceeding the speed of light. Thus they avoid the thorny issues of time travel and how to accelerate a particle to faster than the speed of light by abusing a technicality. The third hypothesis tackles these problems head on, positing a particle that actually experiences time flow in the opposite direction as the rest of the universe.

Tachyons, born to speed

Objects moving faster than the speed of light have drawn fascinated speculation since Einstein first suggested it as a speed limit. It shouldn't be any surprise; scientists are as drawn by the prospect of surpassing limits and breaking rules as the rest of us. It was clear from the equations that such a particle would have some weird properties, for instance experiencing moving through time backwards and traveling slower the more energy it had. This seemingly impossible particle was christened the tachyon.

If a neutrino can really travel faster than the speed of light, instead of stepping through some kind of shortcut, it is behaving like a tachyon and must be experiencing time in the reverse order that we do. This seems like a straightforward admission of the possibility of time travel, and in a way it is. But you shouldn't be surprised to hear that there is a way to cheat that may strip time travel of its most vexing consequences.

Let's revisit those two companions, one of whom travels while his friend remains behind. When they reconvene to compare clocks, they will find that the traveler has aged less than the person who stayed put. Now let's allow him to travel faster than light, and see where that takes us.

The traveler steps inside his craft and goes on his way. As he moves faster and faster he observes the universe around him slowing down. At the moment he reaches the speed of light time around his ship stops, and he goes even faster. Like a video on rewind the universe around him begins to retrace its steps, sending the traveler back in time. Finally he slows his ship to a halt and gets out to compare clocks with his friend, who is surprised to see him. The traveler went back to a moment before he ever left, and his friend here has no memory of him leaving in the first place! At this point the time traveler is free to kill his grandfather to prevent his own birth, bet on the winning team for the Superbowl, and generally do the kind of paradoxical things that make thinking about time travel such a headache. Because of these logical inconsistencies, many insist that time travel must be impossible.

Of course we've run into problems accelerating objects to the speed of light before. Neutrinos with mass vexed an earlier crop of physicists because they traveled at the speed of light, but needed an infinite amount of energy to accelerate to that speed. The solution was that they never accelerated at all; they came into existence at that speed, spent their entire existence that way, and were incapable of slowing down. What if our tachyon-like neutrinos did the same thing, moving faster than light at all times without ever slowing down?

That is exactly how tachyons are theorized to work, and that slight alteration to the example has profound consequences.

We again have two observers, but they don't know each other. They can't, because one was born charging along faster than the speed of light, and the other is living a sedate life in the slow lane along with the rest of us. The best they can hope for is a moment while they speed past, where they can look briefly into the others world.

For the longest time the stationary observer doesn't see anything. The fact that a particle is speeding faster than light towards his exact location is invisible to him, because the tachyon outruns its own light! By the time the light from the tachyon reaches our observer, the tachyon itself will have arrived and will be speeding past and away.

As it passes, our observer suddenly sees both the light from the particle's approach and the light lagging behind it as it speeds away. Effectively he now sees two images of the tachyon, one traveling along the particle's path and the other retracing the particle's steps in the opposite direction.

It's much easier to see this with pictures than with words, so take a look at the figure. The key point is that, because a tachyon outruns the very light that lets you see it, watching one pass by is really to watch two tachyons spring into existence, one moving in the direction the tachyon is actually traveling and the other appearing to retrace its steps in the opposite direction.

To make things even more surreal, since the tachyon is obeying the rules of relativity by never moving slower than the speed of light, it also experiences time subjectively moving in reverse when compared to the rest of the universe. While watching the tachyon move along its faster than light course, the observer sees anything traveling with it aging backwards! This isn't an optical illusion or a trick, anything moving faster than light actually experiences events moving in the opposite order that the rest of the universe experiences them.

Looking at it from the point of view of the tachyon makes that clear. When it begins life, it is already moving faster than light. It zips through the universe, outrunning its own light, and at some point passes our stationary observer. In that instant of interaction, the tachyon would see the observer's world passing in reverse. Anything he “dropped” would be seen to leap off the ground back into his hand. If he were writing something, the tachyon would see ink being soaked into his pen as he traced his letters backwards across a page, erasing them. A sneeze would be a bizarre act where the observer sucked up a cloud of spittle from the air in one mighty breath.

All right, so does this mean we can send signals back in time? If tachyons exist (or if neutrinos can act like tachyons), then in a sense time travel is possible. Put more precisely, a tachyon will travel through time by experiencing everything in our universe backwards. But the key point is that this is how it experiences time, but we still see it moving forward, through time, from A to B as any other particle does (albeit at faster than the speed of light). The fact that it disagrees, and sees itself as moving from B to A, is interesting but not paradox-causing because it can never slow down and join our frame of reference, thus it can never travel back from B to A to relay a message back in time.

Thus the universe remains neatly segregated into the slow lane, where time passes as we are accustomed, and the fast lane, populated by tachyons and their relatives, where time travels in reverse. And never the two shall meet. Paradoxes are avoided, time travel technically allowed but stripped of its logical inconsistencies, and faster than light neutrinos, maybe, explained.

So what is true?

The simple fact is that we don't really know what is happening in the experiment yet. We don't even know if the results are true, and it will take a long time and many experiments to bear that out. In the meantime we can look to the horizon to imagine what frontiers await exploration, and how seeing the world in a new light, supported by what we know about physics and what we might learn, could transform our universe forever.

Sunday Aug 28, A Week in Science

Double Amputee qualifies for semi-finals in 400 m dash in World Athletics Championships

Oscar Pistorius was eleven months old when doctors amputated both of his legs between the knee and ankle. He had been born without a fibula in each leg, and health complications from his condition required that they be removed.

Oscar never let that slow him down. By the age of 11 he had been fitted with prosthesis and participated in rugby, water polo, and tennis. At 17 he suffered a serious knee injury while playing rugby and began physical therapy, where he discovered running. In the following years he set multiple world records in parathlete sprinting events and competed against able-bodied athletes in international events.

In 2007 the International Association of Athletics Federations (IAAF) banned "any technical device that incorporates springs, wheels or any other element that provides a user with an advantage over another athlete not using such a device" in running events, a move that it said was unrelated to Oscar's recent successes. Oscar successfully appealed the decision and won the right to compete in world sprinting and Olympic events, despite claims that his lightweight prosthesis gave him an unfair advantage.

In 2008 he competed for the South African track team for the Beijing Olympics but missed qualifying by .70 seconds. Still determined to achieve his dream of competing in the Olympics, he continued to train and on Sunday, August 28 he qualified for the 400m semi-finals at the IAAF World Athletics Championship in Daegu, South Korea. If he is able to run another 'A' qualification time he will have won the right to run with the best in London in 2012, and to be the first amputee in history to compete in the Olympic games.

Experiments at the LHC continue to find no evidence of supersymmetry.

Modern physics is an uneasy blend of two revolutionary ideas from the twentieth century: general relativity and quantum mechanics. Like two competing nations, their laws work well within their own specific realms (relativity at large scales, quantum mechanics at very small ones) but those laws break down and become meaningless or even incomprehensible in the opposite domain. Between the two is a nebulous border region where strange, inexplicable things seem to occur.

Supersymmetry is a theory that attempts to bridge that gap. Experimental physics has confirmed the existence of a great many particles which make up the matter and energy we interact with every day. Many, such as photons and electrons, you may have heard of. Several, like muons and top quarks, are more obscure. By positing the existence of a set of massive, hard to observe partner for each of these particles, theoretical physicists had hoped that they untangled the thorny mess of conflict between relativity and quantum mechanics. As an added plus, it was hoped that experimental data would reveal these massive partner particles to be the source of the mysterious dark matter which pervades our universe.

Enter the Large Hadron Collider (LHC), the most powerful and expensive science experiment ever conceived. At 27 km in circumference, it is more of a man-made geographic feature than an edifice, and it contains detectors sensitive enough to detect the flickering of a candle from the moon. One of its main missions has been to evaluate the different models of supersymmetry. The data so far is not encouraging.

At the Lepton Photon Symposium in Mumbai, India, physicists from CERN, which operates the LHC, presented data which fails to find any evidence of supersymmetry. Although the findings do not rule out every version of the theory, there is a sense among physicists that a new theory may be needed to explain this data.

"It could be that this whole framework has some fundamental flaws and we have to start over again and figure out a new direction," said Dr Joseph Lykken of Fermilab, a competing detector in the United States with much less sensitivity and power. Dr. Lykken is a leading proponent of supersymmtry and organizer of a yearly conference for its advocates. "It's a beautiful idea. It explains dark matter, it explains the Higgs boson, it explains some aspects of cosmology; but that doesn't mean it's right.

Interbreeding with Neanderthals was important for Human Immune System Evolution

While popular depictions of human evolution show a straight progression from ape to hominid to modern Homo sapiens, it has long been known that human evolution was actually a branching tree. Rival species of hominids coexisted and competed until modern humans outlived or exterminated their rivals by about 30,000 years ago. New data suggests that some of those branches of the human family tree live on in our DNA, specifically in certain genes in the immune system which may have been key to our success as a species.

The study was published in this week's Science magazine by a group of researchers from Stanford and other universities. In it they report that an important set of genes in the human immune system preserves evidence of ancient interbreeding between humans and two other species of hominids, Neanderthals and Denisovans.

Using gene sequencing, the researchers were able to identify an allele known as HLA-B*73 which is far more distantly removed from other typed of HLA genes than those genes are from each other. In essence, using a form of statistical analysis paired with comparisons to living human relatives (chimpanzees and gorillas), they could determine that the allele evolved in isolation from other human genes before being reintroduced by interbreeding sometime in our ancient past. Similar analyses of other alleles in the same region of the human genome reveals another likely cross-breeding event, with Neanderthals, at a different geographical location.

West Asians are the most likely population to exhibit this gene, with a smaller prevalence in parts of Africa and token appearance in other populations around the world. This pattern suggests that the interbreeding event between humans and Denisovans took place in West Asia and spread to Africa and elsewhere over the following generations. Another interbreeding event between humans and Neanderthals happened somewhere in Eurasia, probably in Northern Europe where the Neanderthals were most established.

Previous work has suggested that Neanderthal genes make up between 1 and 6% of the human genome thanks to past interbreeding, but up to 50% of the genes examined by this study may have been inherited from those distant cousins. Such a high proportion suggests that these genes were important to the evolution of our immune systems and to our species' success in the face of constant threat from viral, bacterial, and parasitic infections.

UPenn Clinical Study Cures late stage Leukemia

A Hopeful Headline

In a new study published in the New England Journal of Medicine, researchers cured cancer using modified HIV viruses to turn the patient's own white blood cells into “cancer cell serial killers”. This gene therapy technique was tested in three patients afflicted with B-cell neoplasms, a form of leukemia. , (Perhaps start a new sentence and discuss one patient who one who had been continually diagnosed with the disease since 1996 and the other patients with advanced or chronic or …?. Over the course of six weeks, the disease disappeared from two of the patients entirely and was reduced by 70% in the third. The most serious side effects observed were similar to an intense fever, and one year later the disease remains in remission.

Researchers are hopeful that, based on these initial results, they have developed a powerful new treatment which may help those diagnosed with B-cell neoplasms and other forms of cancer.

The Science of Leukemia

Leukemia is a type of cancer which primarily afflicts the bone marrow and blood cells. Up to 250,000 people worldwide are diagnosed with it every year, and 210,000 die from it. It is the eleventh most common form of cancer, but the most common variety diagnosed in children. Depending on the type it causes tumors in the bone marrow and/or uncontrolled multiplication of certain blood cells.

Leukemia can treated by many avenues, but is notoriously difficult to eradicate completely. In later stages, cancerous cells may multiply so wildly that they crowd out healthy, functioning blood cells, or infiltrate internal organs and grow into tumors. Tumors can also develop in the bone marrow itself.

Treatments almost always include chemotherapy targeted at the type of leukemia the patient has, as well as radiation therapy if malignant tumors are present. Another common procedure is the bone marrow transplant, also called hematopoietic stem cell transplantation (HSCT). Hematopoietic stem cells exist in bone marrow and have the ability to divide and transform into any type of blood cell. In a healthy person the bone marrow continually replenishes blood cells that wear out with fresh-grown replacements. In advanced cases of leukemia, unhealthy cells can accumulate in the marrow, continually producing diseased cancer cells no matter how many times they are cleansed from the blood stream. An HSCT procedure removes healthy stem-cell containing bone marrow from a compatible donor and transfers it to the patient, replacing the cancerous marrow.

HSCT is a powerful tool, but is fraught with potential complications. Bone marrow produces blood cells of all types, including white blood cells whose job it is to attack anything they encounter that is foreign or unfamiliar. When white blood cells from a donor find themselves in a new body, they can sometimes confuse it with dangerous foreign material and attack. When this happens, it is called graft versus host disease, and it is extremely dangerous.

The graft versus host phenomenon and its underlying medical causes have been known since early immunology experiments with mice in the 1940's. In the 1980's, researchers began to observe a similar effect with positive ramifications for the patient, which was christened the graft versus tumor or graft versus leukemia effect. Like in graft versus host disease, donor white cells recognize parts of the host as foreign and attack. In this case, however, they specifically single out and attack leukemia cells, slowing the progress of the cancer. Unfortunately, the strength of the graft versus tumor effect is generally linked with the severity of the graft versus host disease, requiring a balancing act on the part of attending oncologists to keep the patient alive while combating the cancer as aggressively as possible.

There has been a lot of interest among researchers to develop treatments which take advantage of the graft versus tumor effect without the drawback of graft versus host disease. A number of projects have attempted to manufacture white blood cells, which would target only cancer cells while leaving healthy ones alone.

A new avenue

Reprogramming a cell requires the use of an advanced and controversial technique known as gene therapy. Gene therapy allows researchers to edit the DNA of target cells directly, rewriting the code of life in order to treat a disease. Since cancer is often the result of dangerous mutations in a cell's DNA, gene therapy is ale to rewrite the cancer cells' genes to turn of their malignancy, rendering them dormant or harmless.

Unfortunately it can be difficult to find all the malignant cells and edit their DNA, and a single surviving cancer cell may eventually multiply and reestablish the disease. In addition, the genetics of cancer are vastly complex and poorly understood, making it hard to know how exactly what changes to make to cure the patient. Even if a particular sequence could be singled out as the culprit, cancer is an individual disease that manifests in varying, often unique ways in different patients. A gene therapy regimen may have to be individualized in order to maximize its effectiveness, a slow and very expensive prospect.

Dr. June and his collaborators chose a different approach. Instead of finding and rewriting the cancer cells, they chose to use gene therapy principles to reprogram the host's own white blood cells, which are already specialized at hunting down contaminants and attacking them. These modified cells would be told how to recognize dangerous cancer cells, which normally hide from white blood cells because they look so similar to the rest of the body.

The result would hopefully be what the study's authors call “cancer cell serial killers”. If it worked, it would be the most advanced form of immunotherapy ever administered, skirting many of the dangers of chemotherapy and HSCT by using the patient's own reprogrammed immune cells to fight off the cancer.

How to build a cure for cancer

The researchers chose a kind of white blood cell called T-cells to be their tool. T-cells are the body's assassins, pillars in its defense against infection and contamination that specialize in binding and killing enemy cells. They are the rank and file, seeking out foreign bodies and going where they are directed by the rest of the immune system, but for this project the researchers taught them a few new tricks.

Before the reprogrammed cells can get to work, researchers need a way to deliver their instructions to the interior of the cell and edit the DNA. This is a complex task requiring precision at the molecular level, a technique far beyond the capability of researchers to accomplish directly. To do it they again co-opted machinery that evolved in nature for a very different purpose. In this case they took a virus, usually known for causing disease, and re-purposed it to deliver their package to target white blood cells.

Many scientists do not consider viruses to be living things, in part because they are unable to reproduce alone. Instead they invade a host and hijack its reproductive capabilities to produce copies of themselves. A particular group of viruses, called retroviruses, actually do this by editing the host cell's DNA. If a virus could be altered to edit DNA in a particular, useful way, it would allow researchers to reprogram a target cell indirectly.

HIV, the virus responsible for AIDS, is perhaps the most famous and feared of the retroviruses. It specializes in infecting immune cells, particularly T-cells, killing them off as its first wave of attack while tricking them into producing millions of copies of the virus. In an ironic twist, the same qualities that make it so devastating to an infected immune system also make it the perfect tool to deliver the package of genetic material which turns a normal T-cell into a cancer killer.

Researchers of course removed the parts of the genome that lead to AIDS, leaving only the instructions needed for slipping into the cell and changing the host DNA. With AIDS this process tricks the host cell into producing copies of HIV, but the researchers edited those instructions as well. By piggybacking HIV's normally deadly lifecycle, the researchers now had a way to tell a white blood cell to do whatever they wanted.

Anti-cancer vigilantes

Being able to order someone around, of course, tends to be the easy part. Researchers still had to tell the T-cell what to do. They could tell it to ignore its usual restraints and attack the leukemia, but an indiscriminate killer could prove as dangerous to the patient as to the cancer. Researchers had to teach these T-cells to tell the difference between healthy cells and dangerous ones.

B-cell neoplasms involve the aggressive and out-of-control multiplication of B-cells, a type of white blood cell. B-cells produce antibodies, tiny pieces of protein which find and identify foreign contaminants. Antibodies and the B-cells that produce them are scouts for the rest of the immune system's army.

In another example of adapting natural tools for medicinal purposes, researchers used the ability of antibodies to recognize very specific targets as part of the treatment. Every type of cell in nature has different surface markers, they “look” different on a chemical level. Because those differences are microscopic it's hard to recognize them, though many white blood cells have evolved for that very purpose. Antibodies in particular are extremely good at noticing the subtle differences between a liver cell, a bacterial cell, and a B-cell because of their function as the immune system's scout.

Normally the body does not produce antibodies which could attack its own cells. When it does, the patient experiences what is known as an autoimmune disorder. Arthritis and Lupus are common autoimmune disorders, as is graft versus host disease. In the latter case donated white blood cells don't recognize the host's unfamiliar cell markers as “friendly”, and attack. This is why most cases of graft versus tumor treatment involve an associated graft versus host disease; antibodies that target canerous tumors also tend to target other, healthy parts of the patient's body.

Antibodies can be specific enough to attack the cancer and not the rest of the patient, if you know how to get them to tell the difference. In B-cell neoplasms, the researcher's approach was simply to teach antibodies to recognize B-cells. In yet another ironic twist, the very weapons employed by B-cells to defend the body are adapted as weapons used to attack them when they go rogue. Thanks to the modified HIV virus, they can then implant those antibodies in a T-cell's DNA, creating a dedicated killing machine whose sole target is cancerous B-cells.

Persistence is key

While the science that creates these cancer hunting T-cells is exciting, other groups have attempted to make them before. The problem so far has been that the T-cells work for a little while, but soon die off, allowing the cancer to quickly reassert itself. In healthy individuals those cells would be soon replaced by the bone marrow, but the diseased marrow of leukemia patients is unable to do this, and the modified T-cells are introduced from the outside in the first place. A method was needed to ensure that modified T-cells are around for the many months needed to clear the cancer completely.

The researchers working in this study tried out a particular gene known as CD137, which had been observed in other studies to enhance the lifespan and replication of T-cells. By including it with the DNA package delivered by the HIV derived viral vector, they hoped to increase the longevity of the treatment.

The clinical results were striking. In previous trials, modified T-cells without the enhanced longevity were administered to patients, but steadily declined in number and effectiveness over the following days. When the patients were examined three weeks after the initial infusion of T-cells in this study, the cells had multiplied a thousand fold.

Soon patients experienced a condition known as tumor lysis syndrome. Symptoms include muscle weakness, seizures, blood toxicity, and others. While the condition is serious and can be fatal, there was a bright side: tumor lysis syndrome occurs when the body is overloaded by debris from dying cancer cells. Patients lost as much as five pounds of cancerous tissue in those weeks as the T-cells purged them from their bodies.

“It was like the worse flu of their life,” said Dr. June. “But after that, it's over. They're well.”

Three months later, the cancer was in remission and levels of the synthetic T-cell remained high. Tumors could no longer be detected in two of the patients at all, and had shrunk by 70% in the third. No symptoms of the cancer or tumor lysis syndrome were apparent, though a few side effects of the treatment necessitated further medication. In hunting down the cancer cells, the T-cells indiscriminately wiped out all B-cells present in the body. While this side effect was expected, it does severely compromise the immune systems of the patients, exposing them to infections. In cases of terminal cancer, a patient surviving to worry about this complication is a step in the right direction.

As the patients were monitored following their dramatic recoveries, another benefit of the treatment became apparent. Some of the synthetic T-cells had made the transition to “memory” T-cells. Once a disease has been fought off, some T-cells become dormant as an insurance policy for future attacks. If the disease were to reappear, these memory T-cells would reactivate and multiply in order to fight it off. Researchers are hopeful that their presence will grant a lasting ability to fight off any reemergence of the patients' leukemia.

One year after treatment, the patients' physicians haven't detected any resurgence of the disease. Following the publication of their findings in the New England Journal of Medicine, the study's authors are sure to expand the trial to include more patients, and other groups are looking to adapt the technique to other types of cancer. The reaction by experts in the field has been very optimistic and positive, with certain reservations with regards to the treatment's long term effects.

What's next

Physicians and researchers are not the only people likely to show great interest in the treatment. Patients suffering from B-cell neoplasms, as well as any form of cancer that might benefit from this experimental treatment, will be asking their doctors about it in the months to come. Since it is still in phase I clinical trial, the total number of patients that can benefit from it is limited and patients will be carefully screened to see if they meet the criteria for the trial. The treatment is also very complex and expensive, and it will take a great deal of time for clinics around the country to gain the expertise and equipment required to administer it.

There is also the question of long-term effectiveness and side effects, which won't be answered until the patients can be observed over a longer time period. The lack of B-cells in treated patients is sure to expose them to further health complications, and the T-cells themselves may exhibit unpredictable behaviors over longer time frames.

All of these observations, as well as an expansion of the number of test patients benefiting from the treatment, will form the rest of its phase I clinical trials. It is impossible to know how long this phase will last, though several years of continued testing and observation is a certainty. Upon entering phase II, the scope and availability of the treatment will expand, but its a long and expensive road to get there.

Whatever the results of this long process, at least three patients have received the treatment and are thankful for the extra time it affords them. Before Bill Ludwig was inducted into the study one year ago, he was told that the leukemia would kill him within weeks. "I'm more closer to the people I love and I appreciate them more... I'm getting emotional... the grass is greener and flowers smell wonderful," he said of his recovery.

Another patient , himself a former scientist, released an anonymous statement. “I am still trying to grasp the enormity of what I am a part of – and of what the results will mean to countless others with CLL or other forms of cancer. When I was a young scientist, like many I’m sure, I dreamed that I might make a discovery that would make a difference to mankind – I never imagined I would be part of the experiment.”

The Bottom Line

The study done by Dr. Carl June and his collaborators at the University of Pennsylvania took patients' own immune systems and programmed it with a modified HIV virus to recognize and destroy cancer cells. It avoids the destructive side effects of marrow transplantation while harnessing their strengths. The side effects of the treatment are manageable but potentially serious over the long term, though not nearly so serious as the cancer if left untreated. By programming the cells to multiply and persist in the patients' bodies, the study has advanced the fledgling science of immunotherapy, raising hopes that it may someday replace the toxic chemotherapy that currently dominates cancer treatment.

Much progress been made over the decades in combating cancer, yet many seeming miracle treatments have turned out to have serious negative ramifications, or limitations not anticipated during their development. With that in mind, this study will still give great hope to patients fighting cancer, their families who suffer with them, and to the doctors who deal with the tragedy of cancer every day.

NASA orbiter discovers evidence of liquid water on Mars

The Headline

NASA scientists have released photographs from the Mars Reconnaissance Orbiter (MRO) which they claim show evidence of liquid water on the surface of Mars. This is the first clear evidence that water can exist in its liquid state on Mars, though ice has been observed near the planet's poles and under the soil. Reservoirs of water might prove to be an invaluable resource to any future missions to Mars, and raise hopes among many scientists that life might have been able to develop and evolve in the extreme Martian environment.

The Science

The MRO is a probe that entered orbit around Mars in 2006. Since then it has observed the planet and sent thousands of photos back to Earth over the course of three Martian years (one Martian year is 1.88 Earth years).

During this time scientists have made many interesting discoveries, but one set of photos stood out (pictured below). It shows a region of bluffs and valleys which slowly develop dark finger-like features which extend down the slope during the spring and summer, fade in the winter, and return as the atmosphere heats up again. Puzzlingly the soil does not appear to darken because it is wet, but rather because grains of dust are disturbed and rearranged due to something flowing or moving downhill.

image credit: NASA/JPL-Caltech/Univ. of Arizona

“The best explanation for these observations so far is the flow of briny water,” said Alfred McEwen of the University of Arizona, Tucson. McEwen is the principal investigator for the orbiter’s High Resolution Imaging Science Experiment (HiRISE) and lead author of the paper about the flows, published in the journal Science.

Briny water is water that contains very high concentrations of dissolved salts, which are known to be prevalent on Mars' surface thanks to geological studies by the Spirit and Opportunity rovers. Briny water has a much lower freezing point than pure water, and is more viscous as well. This helps to explain how liquid water could exist on Mars, which features temperatures far below the freezing point of pure water.

Other qualities of the flows remain unexplained, for instance why no water or other volatile substances have been detected by the MRO's spectroscopy sensors. Scientists hypothesize that the water may evaporate into the atmosphere too quickly for the orbiter to detect, or that the flows may occur just under the surface of the soil. Another question is why the features disappear as the weather chills during the Martian winter.

“It’s a mystery now, but I think it’s a solvable mystery with further observations and laboratory experiments,” McEwen said.

The possibility of water on any interstellar body is an exciting one for scientists, but especially on Mars, our most accessible planetary neighbor. Life as we know it cannot exist without water, meaning both that it will be an important resource for any possible manned mission, but also that its presence vastly increases the hopes that indigenous life might be discovered on a planet other than our own.

The Bottom Line

The announcement by NASA expresses confidence that liquid water is responsible for the features observed on the Martian surface, but doesn't rule out the possibility of other geological mechanisms. In terms of its impact on a future manned mission, ice has already been discovered on Mars, so the existence of liquid water wouldn't make or break such an expedition. It does increase the interest in organizing such a venture for many scientists, as life is presumed to be much more likely in the presence of liquid water. At the very least the announcement highlights the vast amount that remains to be discovered in even the most familiar regions (relatively speaking) of our interstellar neighborhood.

http://www.nasa.gov/mission_pages/MRO/news/mro20110804.html - NASA mission news

New Study Challenges Global Warming Theories

The Headline

A new analysis of data collected by NASA's Terra satellite suggests that current models of global climate change are flawed. The study, released in the July 25 issue of the journal Remote Sensing, claims that temperature variations in Earth's climate may be attributable to cyclical oceanic phenomen such as el nino and la nina, and provides evidence that the atmosphere is more efficient at radiating excess heat than current warming models predict. If the study withstands further peer review and testing, it may fundamentally shift the predictions made by climate scientists with regard to the hypothesized anthropogenic warming of the planet.

The Science

The article's author's, Roy W. Spencer and William D. Braswell, analyzed 10 years worth of data collected by CERES (Clouds and Earth's Radiant Energy System), a sensor system in earth orbit on the Terra satellite, to address the simple but vital question of how much energy is absorbed by the atmosphere.

The major source of energy entering the atmosphere is sunlight (also called solar radiation). In fact the Earth receives about 2x10¹⁷ joules of sunlight every second, equivalent in energy to a 48 megaton explosion (two thousand times the power of the bomb dropped on Hiroshima). All of this energy has to go somewhere, and in simple terms it does one of three things. It could simply be reflected back into space, a process carried out quite efficiently by clouds and polar ice. Some incoming solar radiation will be absorbed and then re-emitted at a lower wavelength, typically infrared (IR), which can likewise travel back into space. The third and final possibility is that energy from incoming sunlight is retained by the atmosphere as heat, increasing global temperatures.

The main argument made by proponents of anthropogenic climate change (or the global warming hypothesis) is that the release of greenhouse gases by humanity will block the Earth's ability to radiate heat back into space, forcing it to be retained in the atmosphere. This then kicks off what is called a positive feedback loop whereby higher temperatures increase the amount of water vapor and methane in the air (both greenhouse gases), which traps more heat and raise the temperature and so on.

The typical approach to building climate models has been to take temperature measurements around the globe, then use this data to make determinations of how much solar radiation is being retained by the atmosphere as heat. Drs. Spencer and Braswell chose to use the inverse approach by measuring the amount of energy the earth received as sunlight and the amount reflected or radiated back into space with the delicate sensors of the Terra satellite. Armed with these two numbers they could make an accurate determination of how much heat is being retained in the atmosphere, as well as searching for correlations between decreased radiation of IR wavelengths and spikes in atmospheric temperature.The study examined data gathered between 2000 and 2010.

The results of this analysis will likely be contentious among climate scientists. According to the paper's analysis, the atmosphere is far better at radiating heat than most models predicted, and it begins doing so earlier in a warming event than scientists anticipated. In a graph from the paper (shown to the right) the authors plot predictions from IPCC (Intergovernmental Panel on Climate Change) models which represent the general consensus on how the atmosphere radiates energy in comparison to the observations of the Terra climate satellite.

Experimental observations are shown in green, while blue and red represent the IPCC conventional theories. A large mismatch between the two is clearly visible. In area 1, the graph shows a large increase in the amount of energy absorbed by the atmosphere (as measured by the total energy received from the sun minus energy reflected or re-emitted back into space) before a warming event, which is intuitive and agrees with existing models. In area 2, however, we see a rapid increase in the observed heat radiated from the atmosphere into space, even before the temperature maximum is achieved, while traditional models predict heat to be retained in the atmosphere for much longer.

The paper speculates briefly on what mechanisms might be responsible for this discrepancy, but admits that more work needs to be done. Still, if their analysis of the CERES data holds up, the atmosphere is somehow much better at radiating heat into space than is currently assumed, especially given elevated levels of carbon dioxide in the atmosphere due to human activity. Specifically the data suggests a negative feedback mechanism whereby increased temperatures are counteracted by developments which deflect and disperse the extra heat into space, preventing the kind of runaway warming which the most alarming models predict. Should this theory turn out to be correct, then the worst predictions of climate change will almost certainly turn out to be untrue. But there remains a great deal of work to be done before any such claims can be credibly made.

The Bottom Line

Even if all this paper's findings withstand the intense scrutiny that is certainly about to fall upon it, all the study does is reveal unexplained trends in the data which disagree with wide held assumptions about the way the atmosphere interacts with solar energy. It does not provide an explanation for this data beyond suggesting a few possibilities, as the authors themselves state. It certainly does not disprove or invalidate concerns about humanity's impact on the climate.

Instead it provides information that climate scientists will have to explain and incorporate into their models. Whether these enhanced models will turn out be more or less sanguine about the future of our planet remains to be determined.

http://www.uah.edu/news/newspages/campusnews.php?id=564– press release

http://www.mdpi.com/2072-4292/3/8/1603/pdf - article