Close your eyes. Inhale. Exhale. Ahh. Can you feel your autonomic nervous system modulating itself?

It probably sounds like a weird question. But according to researchers like Harvard Medical School professor Sat Bir S. Khalsa, yoga and meditation practices might actually produce measurable changes in the activity of the autonomic nervous system--the bodily system that regulates, among other things, respiration, pulse rate, and digestion--as well as in brain activity and even gene expression. Researchers like Khalsa believe that these physiological effects, collectively dubbed the "relaxation response," lie at the root of yoga's touted health benefits, and that understanding the relaxation response may prove invaluable in the quest to develop new and improved treatments for sleep disturbances, anxiety disorders, and even some learning difficulties.

A yoga class. Via the Wikimedia Commons, Creative Commons Attribution-ShareAlike 2.0.

Of course, if you're a self-described Type A personality like me, it's easy to view this type of on-demand relaxation as little more than a yogic pipe dream. But curious about how the other half lives, on March 2nd, 2011, I decided to attend a presentation by Khalsa at the Harvard Graduate School of Education entitled Yoga: Practice and Research. I had seen advertisements for the talk plastered around the school, where I am currently studying educational neuroscience, and I was intrigued. Khalsa's evidence-based approach seemed like the perfect way for this high-strung science nerd to enter into the elusive world of yoga and meditation. The promise of attending an actual yoga class following Khalsa's lecture was an added perk. Would I bear witness as my fellow students soared to higher planes of consciousness? Would I finally experience, firsthand, relaxation in its purest form? Only time would tell.

Khalsa began his talk by briefly discussing yoga's history. My fellow attendees and I learned that artifactual evidence suggests that yoga originated in India as many as 5000 years ago. In its traditional form, yoga encompasses rhythmic breathing patterns, physical exercise--including the characteristic, sometimes pretzel-like poses known as "asanas"--and a range of mental activities which, according to Khalsa, lead to a state of "relaxed, focused attention." Although historically yoga has been practiced as a kind of mysticism, with the ultimate goal of reaching a state of "enlightment," in recent years increasing attention has been paid by researchers and the media to yoga's therapeutic potential, both medical and psychological. This positive attention may help to explain yoga's meteoric rise to popularity far beyond the Indian subcontinent. As of 2008, nearly 16 million Americans actively participated in yoga, with a majority of novice practitioners citing wellness or "stress management" as their main motivation for taking up the practice.

As a dyed-in-the-wool data-lover, I found these statistics compelling, but not convincing. Popularity aside, I wondered about the scientific evidence supporting yoga's espoused health benefits. I thus listened with eager ears as Khalsa proceeded to discuss some research findings related to yoga's effects on the body. Surprisingly, I quickly discovered that yoga research is nothing new. A number of landmark studies dating back to the 1930s have looked at the effects of yoga and, relatedly, meditation, on everything from heart rates to brain waves.

While some of these studies yielded conflicting results--it appears that even expert yogis cannot, alas, temporarily stop their own hearts from beating--others provide strong evidence for the existence of the relaxation response. As early as the 1950s, scientists had discovered that yoga and meditation reliably produce a cascade of physiological effects, including decreased oxygen consumption, slowed breathing, increased blood flow to the limbs, and changes in patterns of brain activity associated with attention. Described in a 1971 article as reflecting a "wakeful hypometabolic physiologic state," these effects appear to account for the feelings of subjective calmness and well being reported by yoga and meditation practitioners.

Across the last three installments of the Preventing the Unpreventable series, we have explored the scientific challenges of working with the HIV virus, a brief history and status update of HIV vaccine research, and the perspectives of HIV vaccine trial participants. In the fourth and final installment of our series, we turn to the future, and to you.

Researchers believe that the scientific community may be within ten years of finding a safe and effective HIV vaccine. They remain optimistic that the recent modest success of the Thai Trial (see Part III) has reinvigorated hope that an HIV vaccine is indeed possible. Though each discovery takes years to develop from initial concept through multiple stages of testing, scientists believe they are at least moving in the right direction.

"[HIV/AIDS] is one of the most tremendous challenges of our generation," said Linsey Baden, M.D., of the Brigham and Women's Hospital in Boston.

In this way, as the scientific community collaborates in the search for the HIV vaccine, such a tremendous generational challenge also requires the support of communities of all types, around the world. We all must commit to fighting HIV/AIDS. The scientists and trial participants we spoke with all agreed on one thing: all of us have roles to play in the future of HIV vaccine research, even if those roles are not in the lab.

Joseph Caputo learned about HIV and AIDS while in high school, when HIV and homosexuality were inextricably linked in the public consciousness.

"Coming out in high school, the only place you could learn about being gay was the library and the Internet," he said. "All the books at the library were about gay men having AIDS. So from a very young age, I thought that if I was gay, it would mean I would get sick."

Over a decade later, while the public perception had changed, Caputo felt the desire to contribute to the fight against HIV. "I was watching Angels in America and I realized I wanted to do something to get involved," he said. "I don't have money, but I could give my time and my body to research."

Caputo is one of the tens of thousands of men and women who have participated or are currently participating in HIV vaccine field studies and clinical trials worldwide. These individuals are literally the "life of a trial."

HIV-negative volunteers such as Caputo receive treatments, often over the course of many years, that scientists design to prevent HIV infection. Researchers hope that participants who are given the vaccine will contract the virus at a lower rate than control subjects, who receive a placebo treatment instead. All trial subjects are routinely tested for HIV to gather data comparing the treatment group and placebo group, and track success over time. Caputo is currently involved in a study run from Boston.

In the third part of our video blog series Preventing the Unpreventable, we spoke with Caputo and another volunteer, Benjamin Perkins, who currently works in community HIV/AIDS outreach at Fenway Health. (To learn about the scientific challenges of the HIV virus, read Part I, and to find out about today's progress toward finding a safe and effective vaccine, check out Part II).

After serving on community advisory boards, promoting the cause as an HIV/AIDS activist, and working in the field, Perkins said, "I felt like it was a natural progression to roll up my sleeves-figuratively and literally-and do my part."

For both participants, their involvement in HIV vaccine trials has allowed them to feel they are members of the tremendous community of people around the globe contributing to the collective HIV/AIDS activism and advocacy effort.

"Hopefully, the kid today, wandering about the high school library, won't have to go through some of the things that I've gone through," said Caputo.

After 30 years of research, billions of dollars in spending, and millions of lives lost, are we any closer to finding a vaccine for HIV? In Part II of Preventing the Unpreventable, Inside NOVA's video blog series on the search for an HIV vaccine, we find out why some AIDS researchers are optimistic about the future. (For more on why HIV is such a formidable opponent, check out Part I of this series).

Almost every day, scientists from around the world release new findings about the biological structure of the HIV virus and its various subspecies, clinical test results that confirm or dispute the direction of vaccine development, or creative new vaccine concepts for eliciting immune response. Progress is happening in real time. So, where are we now?

Getting a potential vaccine to clinical trial is costly, logistically difficult, time-consuming, and ethically fraught. To drive progress toward that goal, large-scale organizations such as the HIV Vaccine Trials Network, the International AIDS Vaccine Initiative, and the U.S. Military HIV Research ProgramNational Institutes of Health and the Indian Council of Medical Research to private foundations, organizations including government agencies, non-profits, philanthropic foundations, and pharmaceutical companies, are joining forces to share research findings and build a collective database of HIV knowledge, all aimed at preventing HIV infection.

The journey to find the HIV vaccine has been a long one. Why?

We asked a few of today's leading HIV/AIDS specialists about the scientific challenges of working with the HIV virus and development of a safe and effective vaccine.

Not only does the human-specific HIV attack the very system (the immune system) that typically helps to ward off viruses, but it constantly changes, adapting to the body's antibodies. This is called adaptive immunity.

Some other unique challenges in working with HIV include:

• Most vaccines protect against disease, not infection. However, the HIV infection does not result in AIDS (the disease) for an extended period of time.
• A partial (or dead) HIV virus loses its potency, and thus cannot be used for a vaccine. Yet, using a live virus is too dangerous. Therefore, scientists must develop synthetic viruses that model the structure and ideally elicit similar immune responses as the actual virus. Synthetics, while more complex, are significantly safer, and are commonly used in other vaccines like the flu vaccine.
• While most vaccines guard against infection contracted primarily through gastrointestinal or respiratory tracts (the flu, for example), a great majority of HIV infection occurs through the genital tract, which responds only weakly to infection.
• HIV may be encountered by a single individual multiple times in various and diverse forms or strains; this is called biodiversity. Therefore, successful vaccine concepts must ward off many different viruses at once.
• Typical vaccines mimic natural immunity seen in patients who have recovered from infection, but there are no recovered HIV/AIDS patients.

Come back later this week as we take a look at what it takes to develop an HIV vaccine and the progress that has been made to date.

* * *

Lindsey R. Baden , M.D., is Director of Infectious Diseases, Dana-Farber Cancer Institute; Director of Clinical Research, Division Infectious Diseases, Brigham and Women's Hospital; and Assistant Professor of Medicine at Harvard Medical School.

Dan H. Barouch, M.D., Ph.D. is the Chief of the Division of Vaccine Research, Department of Medicine, Beth Israel Deaconess Medical Center; and an Associate Professor of Medicine at Harvard Medical School.

Ken Mayer M.D., is the Medical Research Director and co-chair of the Fenway Institute at Fenway Health.

This is Part One in the four-part blog series Preventing the Unpreventable: The Search for the HIV Vaccine written by Devon Dickau, who interned at NOVA in the spring of 2011 before graduating from the Harvard Graduate School of Education's program in Technology, Innovation and Education.

In 1984, only a few years after the first verifiable identification of AIDS, U.S. Secretary of

Health and Human Services Margaret Heckler declared that a vaccine for the deadly HIV virus, the virus that causes AIDS, would be widely available within 2 years.

What went wrong? This year, as we mark the 30th anniversary of the first AIDS diagnosis, more than 33 million people worldwide are infected. Since the 1980's, AIDS has become a global pandemic, revealing debilitating social stigmas, orphaning children, and destroying developing economies. And thus we spend almost $1 billion each year in pursuit of a vaccine that can prevent HIV-with little progress. But, why? How can we dedicate vast resources, time and brainpower with such a modest result?

This four-part blog series will try to answer those questions. We will delve into some of the scientific and social challenges to developing the vaccine, take a look at the milestones of the past decades, and come face-to-face with scientists and people who inspire the optimism driving the continuous search to prevent the seemingly unpreventable.

Part 1: Meeting the Challenge

Part 2: Where Are We Now?

Part 3: Life of a Trial

Part 4: The Future and You

This post is part of the four-part blog series Preventing the Unpreventable: The Search for the HIV Vaccine written by Devon Dickau, who interned at NOVA in the spring of 2011 before graduating from the Harvard Graduate School of Education's program in Technology, Innovation and Education.

Your brain really doesn't remember the things it sees very well. While it might capture certain aspects of the world, it mostly discards the information it processes. University of Illinois psychologist Daniel Simons (along with collaborator Daniel Levin of Vanderbilt University) has devised many experiments to show just how poor our visual cognition can be, which the NOVA scienceNOW team replicated in this video blog.

Curious as to how the other parts of your brain work?  NOVA scienceNOW shows you how magic, free falls, and mind controls devices are shaping the way we think about the brain.

Alex Liu is a former NOVA scienceNOW intern and recent NYU SHERP graduate who now lives in the San Francisco Bay Area. Visit his personal website and follow him on Twitter.

Imagine yourself standing on the shore of a river in eastern Australia, arms outstretched to avoid being nipped by the flailing, angry platypus you have suspended upside down by its tail. The scene is strange enough without considering the oddities of the animal you have captured: It has the fur of a mammal, the bill of a duck, and the tail of a beaver, and it lays eggs like a reptile. And it's venomous. The platypus is one of a very select group of mammals that produces venom, and it is giving scientists clues into how and why venom evolved across species.

Catch me if you can! By Stefan Kraft (GFDL or CC-BY-SA-3.0) via Wikimedia Commons.

Right now, not much is known about the contents of platypus venom. Part of the reason for this is that platypuses are somewhat tough to come by. They don't breed well in captivity, and concerns about disturbing them during mating season make them difficult to track down in the wild. Fortunately for us, field scientists like Tom Grant of the University of New South Wales regularly put themselves in the aforementioned strange scenarios on eastern Australian rivers. Grant and his colleagues lay nets in the water in hopes of trapping an animal, and when they have one, they grab it by its long tail and hold it upside down. Platypus venom spurs are located on the hind legs, so while one scientist holds the angry, dangling platypus by the tail as far away from himself as possible to avoid being stung, another holds a small pipette up to the spurs in hopes of extracting a little venom that can be stored and studied. The venom is strong enough to kill a dog and cause debilitating pain to a human. Just another day at the office.

The venom-spitting dinosaur in Jurassic Park may have been fictional, but in a great case of life imitating art, scientists have discovered evidence of a real venomous dinosaur that walked the earth in China over 120 million years ago. Sinornithosaurus is the first confirmed venomous dinosaur, but there is evidence that venom is even older than this most recent discovery--that creatures from up to 500 million years ago could also have been venomous. These ancient venomous creatures are giving us reason to believe that, evolutionarily speaking, not being venomous may actually be more noteworthy than being venomous.

David Burnham, a paleontologist at the Kansas University Natural History Museum, was hunting for raptor fossils in rural China when he and his colleagues stumbled across a new fossil skeleton with grooved teeth and an inexplicable gap in its skull. They puzzled over what these two clues could mean. And then one day, while examining the skulls of venomous komodo dragons, it suddenly clicked. The cavities in the raptor skull very closely resembled areas in the komodo dragon skull reserved for their venom glands. Burnham began to wonder, was it possible that this ancient raptor was also venomous?

My, what big teeth you have! The Sinornithosaurus fossil specimen bares its teeth. Image courtesy David Burnham.

Further investigation revealed that everything Sinornithosaurus (the newly named raptor species) would need to be venomous was there. The spaces in the skull would have made room for prominent venom glands, along with a drainage canal leading into the mouth and muscles to help pump out the venom. But this dinosaur's venom-delivery mechanism was rather primitive. Unlike many modern snakes with long fangs in the front of their mouths that can forcefully eject venom at their prey (remember spitting cobras?), Sinornithosaurus had teeth with grooves for delivering venom that sat at the back of its mouth. Burnham suspects that over evolutionary time, tooth material closed in around the groove and migrated towards the front of the mouth, leading to something more closely resembling a cobra's fangs. The grooved teeth mean that unlike its fictional Jurassic Park counterpart, Sinornithosaurus had to chew the venom into its prey, probably using it more as a stunning tool than a killing one. A handful of modern snakes, unsurprisingly called "rear-fanged snakes," have retained the Sinornithosaurus-style grooved teeth.

Discoveries like Sinornithosaurus give scientists more decisive clues into the evolutionary history of venom. But we have reason to believe that venom is much older than even the dinosaurs. The conodont, an eel-like creature that lived almost 500 million years ago, had the same kinds of grooved teeth found in Sinornithosaurus and other primitive venomous creatures. And the evolutionary influence of the conodont is far from slight: it gave rise to all fish and most vertebrates.

There are more than 41,000 described species of spider, and over 99% of them are venomous. Mercifully, there are only four small groups of spiders whose venom is lethal to humans, but insects beware: Spider venom can inflict a cocktail of unpleasant symptoms, from full-body convulsions and paralysis to spontaneous cell death that dissolves your body while you're still conscious. With so many species and so much time to diversify, spiders have developed methods to capture and kill just about every kind of insect prey out there. And now, humans are developing ways to take advantage of diverse spider toxins to create pesticides that kill insects without harming humans or the environment.

Image Courtesy Bruno Santos

Greta Binford spends most of her time doing research at Lewis and Clark College in Oregon, but when she's not in the lab, she can be found hunting down the deadly brown recluse spider everywhere from peculiar haunts like the basement of a Goodwill store in Los Angeles to the mountains in their native Peru. They are generalists that will eat pretty much anything that walks by, but other spiders are much more specialized. Tarantulas live in holes and only capture things that come near their dwellings; orb weavers catch insects in flight. A few species spit toxic glue at their prey; others dash underwater and bite fish. Most interesting of all to researchers like Binford is that all these spiders' venoms reflect the diversity in how and what they catch.

Jamie Seymour is hunting shadows. Box jellyfish--some of the most terrifying animals on the planet--are completely invisible in water, so the best Seymour can hope to find are the shadows they project onto the shallow ocean floor. He keeps a stealthy eye out for flashes of shadows on the sand beneath his boat just a few feet off the northern Australian coastline. When he thinks he's spotted something, he tosses a large plastic bin overboard in hopes of pinning his prey. Clad in thick rubber armor to protect himself from the box jelly, Seymour hops out of the boat to investigate his catch.

The box jellyfish inside the bin is roughly the size of a squared-off basketball. Though it is called a jellyfish and looks much like one, it is technically a member of a slightly different species. Chironex fleckeri has a startling 24 eyes, six facing each direction. On its base are 60 tentacles roughly eight feet long that bear a striking resemblance to fettuccine. Creeped out yet? If not, here's the final nail in the coffin: These animals can kill a human in about two minutes, and we don't entirely know how. Not to mention that a box jellyfish sting is probably among the most painful ways to die.

A signpost at a beach in Cape Tribulation, Queensland, Australia warning of the presence of the box jellyfish Chironex fleckeri and others. Image courtesy TydeNet, licensed under Creative Commons.

Seymour is a professor of biology at James Cook University in Australia, and has spent much of his professional life studying and tracking box jellies. He's devised a way to follow these animals by capturing them in his plastic bins and using surgical glue to attach small tracking devices to their skin. The glue only lasts a few days, but it's enough time to make some startling discoveries.

Among the first surprises: Box jellies are fast. They can swim at speeds up to four and a half knots--that's just under the speed of an Olympic swimmer. When they swim, their tentacles shrink from as long as ten feet to as short as two feet to help reduce resistance. In other words, unless you're Michael Phelps, don't count on being able to outrun one of these guys.

Even more shocking than their speed is when box jellies stop all together. Sleep is extremely unusual in invertebrates, especially ones that are composed of 96% water. Seymour's colleagues went so far as to call him nuts when he proposed the idea that box jellies sleep, but the data is clear: Box jellies sink to the bottom of the ocean and snooze whenever it's dark outside. Why is this significant? First and foremost, it gives the box jellies a chance to hide from their turtle predators, who are lucky enough to be one of the few creatures immune to box jellyfish venom. But it also gives them a chance to grow. Box jellies grow about two to three millimeters every single night, putting on layers like a tree. Their metabolisms have to run like V8 engines to fuel that kind of growth, so sleep gives them a chance to sit still while they expand in size.

When Bruce Young walks into a room filled with spitting cobras, he elicits a terrifying response. "They just love to spit at me," says the professor at the University of Massachusetts at Lowell. Spitting cobras have evolved the ability to hurl venom at the

A staring contest with a spitting cobra. Image Courtesy Biju Joshi

eyes of predators, debilitating and often blinding animals many times their size from up to ten feet away. So when it came time for Young to choose a target to use in order to study how cobras hit their targets' eyes with such accuracy, it seemed only natural to choose... his own face. Because, really, what else would you choose?

Young was studying the evolutionary history of cobras when he began to notice an interesting byproduct of the cobras' constant spitting in his direction. The venom trails that dried on the glass walls of the cobra tanks formed varied and beautiful geometric patterns. Cobras store venom in glands hidden just behind their eyes, and when they spit, they flex powerful muscles that force the venom out through long, thin fangs. But unlike the cobra's target, the fangs can't move. How could these complex patterns of venom form, and even more impressively, how could the cobras hit their targets with an accuracy rate over ninety percent? Young reasoned it must have something to do with head movements, but he wanted to know more.

Part 1: Cobra Face-Off
Part 2: Box Jellies
Part 3: Super Spiders
Part 4: Dinosaur Venom
Part 5: Platypus Tales

In anticipation of the NOVA/National Geographic special Venom: Nature's Killer, premiering February 23 at 9pm on most PBS stations, Inside NOVA is bringing you The Venom Chronicles, a five-part blog series exploring fascinating venomous animals and the researchers who study them. We are very much looking forward to giving you the heebie-jeebies, the creepy-crawlies, and a sense of awe at what these amazing animals can do. But before we get started, let's take a moment to talk about some venom basics.

Image Courtesy H Berends

What's the difference between venomous and poisonous animals?
Venom and poison are both substances that do harm, grouped under the umbrella term "toxin." The difference between them has to do with the delivery system. Poison must be eaten in order to be effective, as in the case of poisonous toads that injure or kill whatever tries to eat them. Venomous animals, on the other hand, usually have fangs or another related way of delivering the venom to their prey without needing to be eaten first. Of course, sometimes the two categories overlap. The yellow-bellied sea snake is a venomous animal with fangs that can cause serious damage if it bites you, but eating the venom can also be dangerous.

How does venom work?
Venom is made up of a combination of many different protein molecules that change the way your cells behave. The huge variety of toxins lead to many different effects on your body, depending on what kind of cells they target. An animal's venom may have one, some, or all of the following categories of toxins:
 

Neurotoxins affect the cells in your brain and nervous system. The most common effect is paralysis, but these molecules can also affect the way your brain cells communicate with each other.

Hemotoxins mostly target cells in your bloodstream, though they have impacts on other tissues as well. They can kill red blood cells, which deliver oxygen to the rest of your body, as well as disrupt normal blood clotting and cause organ failure.

Cytotoxins are responsible for spontaneous cell death in which a cell explodes and releases its fluid into the body. The tissue swells up and causes extraordinary pain.

In "Jurassic Park," we saw what might happen if some of the world's largest and smartest predators are brought back to life. The movie put the awe in audiences with its strikingly realistic dinosaurs. But how close are we to really being able to bring creatures back from the dead?

Not very. In the movie, geneticists extract dinosaur blood from mosquitoes preserved in fossilized amber, but it is extremely unlikely that DNA would be able to survive for 65 million years, even in the best conditions. If the scientists somehow found a large enough workable sample, they still wouldn't have a complete genome, as it deteriorates over time. They would also need a surrogate mom from a closely related species to provide an egg and carry the embryo. These are just a few of the major advancements which would be necessary to make dinosaur cloning a reality.

This video, from the Howard Hughes Medical Institute, shows the first step in the reproductive cloning process, known as somatic cell nuclear transfer. Cloning existing animals, especially mammals, is challenging enough for scientists. Clones often die soon after birth if they survive at all. And there are always concerns over maintaining a diverse gene pool.

Yet some scientists have already attempted to replicate animals in danger of extinction or which recently went extinct, all of them far less daunting than dinosaurs. Advanced Cell Technology cloned a gaur, a threatened species of Asian ox, in January of 2001. This was the first attempt to clone an endangered species. The gaur was carried to term in a cow, but died of a common infection two days after its birth. In late 2001, scientists in Italy reported the successful cloning of a baby mouflon, an endangered wild sheep, which lived out its adult life at a wildlife center in Sardinia. In 2003, scientists cloned a banteg, an endangered species of wild cattle.

In "Back to the Future II," director Robert Zemeckis envisioned a future--now a mere five years away--in which every home comes equipped with a Mr. Fusion Home Energy Reactor. Mr. Fusion can power just about anything, even the flux capacitor of our favorite time-traveling DeLorean, using everything from banana peels to beer cans. Zemeckis may have overestimated the ubiquity of mini fusion reactors--not to mention flying cars--but we have made some progress in transforming waste into power since 1985. Manure and some forms of garbage have been used to produce methane gas, hydrogen gas, and to directly generate electricity. But one of the most surprising of these renewable biomass energy sources is urine.

Urine may not be a particularly powerful energy source, but its abundance and inherent renewability could make up for what it lacks in energy density. Using a technique called urea electrolysis, says Dr. Geraldine Botte of the Center for Electrochemical Engineering Research (CEER) at Ohio University, farms and office buildings could become self-sustaining pee powerhouses.

Urea is one of the main components of urine. If left untreated, urea will react with water and turn into ammonia and other pollutants. To turn this would-be pollutant into power, Botte and her colleagues extract urea from the wastewater and pass an electrical current through it, releasing hydrogen gas. The hydrogen can then be used to power generators or create fuels, and the urea-free wastewater can safely be used for irrigation.

Traditionally, hydrogen has been produced using water electrolysis, but that process is far more expensive and inefficient. Dr. Botte says one cow could provide enough hydrogen to heat water for 19 homes and an electrolyzer could easily fulfill all the electricity needs of a small farm. Some researchers speculate that an office building could be fully powered by the liquid waste of its office workers. And Botte's lab has even used hydrogen made from pee to create a pee-powered car.

In this video Purusha Bonnin, a graduate student working with Dr. Botte, demonstrates how CEER's hydrogen-powered car would work using a small model. But what about the DeLorean? Dr. Botte, like most researchers, thinks that this technology is better suited to stationary purposes for electricity production or perhaps for powering the electrical systems of the car. It is not powerful enough to keep a car engine running efficiently. We are decades away from surmounting the technical and economic hurdles to widespread use of hydrogen cars--and they may never become widely available.

In the movies, they go by many names: death ray, ray gun, laser beam, phaser, blaster and, of course, lightsaber. These weapons are science fiction icons. Remember Han Solo blasting Greedo the bounty hunter in "Star Wars"? The alien invaders annihilating the White House in "Independence Day"? Classic science fiction films like "War of the Worlds" feature equally fearsome aliens with death-ray-equipped UFOs. "Ghost Busters" taught us never to cross the streams of our super-cool, though equally fanciful, "proton packs."

In reality, they're collectively known as directed-energy weapons, and they channel lasers, heat, or particles into targeted beams. The military has made several attempts in recent years to create viable, field-ready directed-energy weapons, primarily for missile defense, but most of these projects have been abandoned. Starting in 2000, a joint U.S.-Israeli prototype called the Tactical High-Energy Laser (THEL) took down 25 Katyusha rockets during a demonstration program and a mobile version destroyed multiple mortar rounds. The project was discontinued in 2005.

The U.S. Air Force's Airborne Laser Test Bed successfully took out a ballistic test missile in February of 2010, but funding for the device was later suspended, as the test revealed that it was difficult to maintain the laser's precise alignment. The device also had a tendency to overheat and malfunction during adverse weather conditions.

While they may come up short in missile defense, directed-energy weapons like the ZEUS-HLONS system, commonly known as ZEUS, have been successfully deployed on Humvees on the battlefield to burn out land mines and unexploded munitions, preventing a larger explosion. The ZEUS heats up and defuses explosives up to 300 meters away using a laser beam.

As for targeting individual soldiers, it looks like we'll be setting our phasers to stun--at least for now--with devices that incapacitate people rather than eliminate them, like the military's Active Denial System (ADS). The ADS is essentially a ray gun, but it doesn't cause instant death or, like the "District 9" version, turn its targets into Jell-O. Instead, it uses a very precise frequency of microwaves to agitate fat molecules in the top layer of the skin. The skin heats up, causing a sensation which CBS News correspondent David Martin likened to scalding water.

It's also been described as similar to the blast of heat you feel upon opening a very hot oven. Most people find this unpleasant enough to send them running out of the beam's path within a few seconds--and once they do, the pain instantly subsides. These devices won't actually fit in your pocket, and you can't see or hear the beam. The beam projects from a large reflector plate usually mounted on top of a vehicle and controlled by an operator with a joystick. ADS could be used to repel a large group of people at a range of over 700 meters. The United States Marines and police are working on portable versions.

"Wait a minute, Doc. Ah... Are you telling me that you built a time machine... out of a DeLorean?" says an awestruck Marty McFly in the iconic film, "Back to the Future." While we probably won't be visiting our hormone-charged teenage parents in souped-up DeLoreans, there are a few natural phenomena which could transport us into the future and, maybe, even into the past.

Hollywood has long fantasized about time travel and its seemingly endless possibilities, from thrillers like "The Time Machine" and "12 Monkeys" to over-the-top comedies like "Bill and Ted's Excellent Adventure" and "Hot Tub Time Machine."

But how can time travel reach beyond the realm of science fiction? Technically, it already has, as astronauts travel a few nanoseconds into the future every time they travel into space. In fact, just by driving in your car, riding an airplane, or climbing a ladder, you change the rate at which time flows. Einstein's Theory of Relativity established that both motion and gravity could slow down the progression of time. The closer an object--let's say, a space shuttle--travels to the speed of light, the slower it travels through time and the slower the pilot ages.

There have been many fictional ideas for time travel devices--phone booths and hot tubs come to mind--but in reality time travel does not require a machine at all, except perhaps a space ship. According to Dr. Max Tegmark, professor of physics at MIT, the most plausible way to travel into the future is by orbiting a black hole. Flying just outside of the black hole's event horizon--the point at which nothing can escape its gravitational pull--would allow you to travel close to the speed of light. But Tegmark points out that we would need to find a suitable black hole close by, which is no easy feat. Theoretically, black holes from other galaxies consumed by our own could be orbiting nearby and these would be our best bet for traveling into the distant future.

So far, we've only been talking about going forward in time. Could a black hole also give us access to the past? In the newest "Star Trek" movie, Spock's vessel and the Romulan ship get caught in the event horizon of an artificial black hole and are transported 129 years into the past. In reality, Spock would be torn apart by the intense gravitational pull before he could reach the center of the black hole. However, some theorists postulate that a rotating black hole called a Kerr black hole could be traversable. So, Spock could theoretically travel to the past by exiting through a "reverse black hole" called a white hole on the other side, where he'd find himself at a different point in space and, perhaps, in time.

A hypothetical spacecraft warps space-time. Image courtesy of NASA/Les Bossinas.

Another possibility: Just build a wormhole. Wormholes are shortcuts in space-time that connect two distant points, like a train tunnel cutting through a mountain. But scientists aren't sure how to create a wormhole--or how to keep one open.

In the blockbuster action flicks "Iron Man" and "Iron Man II," Tony Stark doesn't need a vat of toxic waste or the bite of a mutated spider to obtain his superpowers. He uses the powers of science and engineering to create a robotic exoskeleton, which gives him superhuman strength, increased endurance, and the ability to fly. Many other science fiction films have featured similar devices--who could forget Ripley's machine-clad fight-to-the-death with the vicious queen in "Aliens"? In "Avatar" and "The Matrix Revolutions" powered exoskeletons are used in combat and for moving cargo.

Surprisingly, these on-screen machines are more science than fiction with one key exception: the power source. Tony Stark uses the fictional "arc reactor"--a fusion reactor--to generate the vast amount of energy needed to power his suit's jet boots, plasma weapons, and on-board computer. But if you could condense a nuclear power plant into a softball-sized reactor, would you really want to put that in your chest? Tony Stark did and managed to not be cooked alive, but in the real world, the heat output of such a device would be problematic to say the least.

In reality, generating that much power for exoskeletons would be overkill. Companies like Raytheon and Lockheed Martin, which are developing real-life exoskeletons for the military, are wrestling with the power-supply problem, but they seem more concerned with reducing power consumption than with finding new energy sources. Running these machines for sustained periods of time in the field is one of the last major hurdles Raytheon's XOS 2, Lockheed Martin's HULC and similar models face before they can be distributed for military and industrial use.

In September, Raytheon revealed its XOS 2 to the public in a demonstration cross-promoting the "Iron Man 2" DVD and Blu-ray release.

In this video, Rex Jameson, Raytheon's test engineer, demonstrates the maneuverability of the suit by lifting weights, running, and punching a speed bag. He also kicked a soccer ball, climbed stairs, and walked on his heels while wearing the suit.

It's been referred to as the real Iron Man, as it's the first full-body exoskeleton. The XOS 2 makes lifting 200 lbs feel like 12 lbs and it allows its wearer to punch through three inches of wood with ease. An internal combustion engine powers the exoskeleton, but the suit must also be plugged into an electrical power source to function. Raytheon is currently developing a battery option, which would be worn in a backpack. Raytheon expects to have a tethered (plugged in) version employed in major military operations in about five years and an untethered version available three to five years after that.

When will science catch up with Hollywood? In our new Cinema Science series, running all this week, NOVA intern Samantha Johnson examines the real science of classic sci-fi tropes like time travel, super-suits, ray guns, and more. First up: Saving Earth from killer asteroids.

"It happened before. It will happen again. It's just a question of when," says an ominous voice in the opening sequence of the film "Armageddon," as we watch a deadly asteroid strike the earth, decimating the dinosaurs. But before you build an underground bunker and stock up on a lifetime supply of SpaghettiOs, let's take a minute to find out what films like "Armageddon" and "Deep Impact" get right-and wrong-about how to save the world from killer asteroids and comets.

Image courtesy of NASA/Don Davis. Artist's concept of a catastrophic asteroid impact with the early Earth.

Though they seem to slam into movie and TV screens every year, asteroids capable of exterminating entire species are exceedingly rare. There are many smaller Near-Earth Objects (NEOs), which, on average, hit the earth every 200 years and could potentially level a city. Earth's most recent brush with destruction came in 1908, when a 30- to 50-meter-wide object exploded over Siberia, destroying more than 800 square kilometers of forest, but, apparently, killing no one.

So, what can we do to save humanity from the Big One? Hollywood often opts for big explosions with the latest Aerosmith power ballad blaring in the background. The heroes blow up the killer rock at the last possible second and the camera pans across cheering crowds from New York to Mumbai watching the mass detonation. In "Deep Impact," astronauts destroy an incoming comet with nuclear weapons minutes before impact.

In "Armageddon," a crew of rugged oil drillers lands on the asteroid, digs 800 feet into the surface, and deploys nuclear weapons four hours before impact. This would supposedly break the asteroid into two pieces, which would somehow clear the Earth. While this method does give the filmmaker an excuse to put Bruce Willis in space, it doesn't bode well for humanity.

But in reality, most scientists agree that, even in the most desperate circumstances, blowing up a threatening asteroid would be a bad idea. If we try to blast the big scary rock, we'll most likely end up with many little scary rocks. They would rock our world with the same amount of kinetic energy, resulting in an equally devastating event.

Whether you slap on whatever's handy or put together a well-coordinated ensemble, your outfit makes some sort of fashion statement. But imagine wearing clothes that could, literally, speak for themselves.

A lab at MIT has designed special fibers that can detect and emit sound. The team described exactly how they accomplished this in a paper in Nature Materials.

MIT scientists have designed smart fibers thin enough to be woven together.
Image Credit: Courtesy of Yoel Fink, MIT.

We know scientists can manipulate the most basic units of life in the lab. Now they've made plastic copies of our body's natural defenders, antibodies.

Courtesy of Hoang Xuan Pham, University of California, Irvine

UC Irvine chemistry professor Dr. Kenneth Shea recently reported in the Journal of the American Chemical Society that this plastic antibody rescued mice that had been exposed to lethal doses of melittin, the toxic component in bee venom.

How did scientists manage to make more of these biological bodyguards without using any living organisms?

Why don't trees ever get sunburned? And could we harness their secret to protect our own skin? Researchers are studying how proteins called photolyases, which have been lost to humans through evolutionary time, provide most other organisms with extraordinary protection from damage caused by the sun's ultraviolet (UV) rays. The proteins do it by channeling the power of visible light.

A dimer in DNA forms in response to ultraviolet rays. Image Courtesy NASA/David Herring

Normally, the molecules that make up DNA look like a twisted ladder and form the classic double helix structure. But UV light, which has a shorter wavelength than visible light and cannot be seen, sometimes causes two of the rungs of nucleotides to fuse to each other instead of reaching across the ladder. This bulging formation, called a dimer, can be passed on when DNA is replicated and lead to mutations--some of which can turn into deadly forms of skin cancer. 

Fortunately, our cells do have repair mechanisms that find dimers, snip them out, and replace them with new DNA that fits properly into the ladder before the dimer can be replicated. But our proofreading process is not perfect, and sometimes it lets a dimer or two slip through.

I get lost. A lot.

For this reason, I was very excited when I picked up last month's Science, in which researchers from University College London reported that sense of direction is innate in newborn rats. Their work is an important starting point in understanding how humans develop a concept of space.

This was big news for me. Maybe, I thought to myself, I was one of the unlucky few who had been cursed with bad biology. Could it be that my constant disorientation wasn't actually my fault?

A new brain mapping technique uses viruses to illuminate neurons in beautiful colors, and can give us detailed visuals of how information travels through the brain.

Imagine the brain like an old house, full of complex electrical circuits and wires that branch off to every room. 

A region of the hippocampus where new memories are often formed.          Photo Courtesy T. Weissman, J. Livet, and J. W. Lichtman

Now imagine that you wanted to trace the path electricity takes from the main circuit breaker to the microwave, but you're not allowed to destroy the house in the process. Hopefully you would have a circuit map, and if you're really lucky, the circuits might even be drawn out in different colors. Now, scientists have found a way to make the same kinds of maps in the brain of a mouse by literally illuminating the pathways between neurons.

Attention astronomy enthusiasts! Remember learning about the seemingly insurmountable odds astronauts faced when upgrading the Hubble Space Telescope? (If not, check out these programs from NOVA scienceNOW and NOVA.) Thankfully, after a successful mission, the world's most powerful space telescope can now see the universe as it was a billion years after the Big Bang. But are you a little anxious (like we are) to know more about the even earlier universe?  Well, if you can wait until 2014, scientists might be able to peer into this past-- only 300 million years after the dawn of the cosmos.

Meet the James Webb Space Telescope. Engineers have started constructing this new space telescope, and astrophysicists hope that it will change the way we understand the universe. NASA showcased a full sized model of the telescope at the World Science Festival in Manhattan in June, so the team at NOVA scienceNOW went to see what it could do. Take a look.



Alex Liu, an intern at NOVA scienceNOW, is currently a master's candidate at New York University's Science, Health, and Environmental Reporting Program.

If your social life is anything like mine, you have probably spent a few Saturday nights rubbing saliva between your thumb and forefinger and watching a beaded liquid string form as you slowly pulled your fingers apart.

Some polymer-containing fluids, like saliva, form           beads-on-a-chain structures when stretched.

Well if you haven't, try it now. Trust me, it's cool.

"At first it may look like a wire as you are separating your two fingers. But then, all of a sudden, little beads start forming on it," Dr. Osman Basaran, a professor at Purdue University's School of Chemical Engineering, said during a phone interview with me last week. "That's how I started thinking about this problem." 

Basaran and his colleagues provided a detailed explanation of how these structures form in this month's Nature Physics.

Their work has some very useful medical applications, particularly in managing drug dosage.

Several examples of these liquid beads-on-a-chain structures exist in nature, from fish slimes to silk threads. Until now, scientists did not have a detailed understanding of how these necklaces took shape.

Have you ever felt guilty and not understood why? Or felt that you're easily distracted? Most have. A study by the U. S. Geological Survey shows that a parasite that invades human brains and cat intestines could be to blame.

Here's how the bug works: Humans ingest Toxoplasma gondii, a common relative of malaria, which, at first, only makes itself known through mild flu symptoms. These symptoms have been known to linger in individuals with compromised immune systems, such as those affected by AIDS, but, in the majority of cases, the symptoms pass, the host feels better, and the bug is forgotten.

But Toxoplasma gondii stays on...

As someone who has always been embarrassingly weak, it's nice to know that sometimes all that's required to win is the right attitude. At least this is the case for the female jumping spider, Phidippus clarus.

Various species of female spiders are notorious for their viciousness against males. And female jumping spiders also fight aggressively with each other, sometimes to the death.   

Interestingly, in fights between female jumping spiders, winning isn't dependent on size or strength, but on how badly the female wants to win, according to scientists at the University of California at Berkeley and Dr. Maydianne Andrade, who we profiled on NOVA scienceNOW last year. Their work appears in this week's Behavioral Ecology.

Who sells seashells by the seashore? And, more importantly, why should you care?

Journalist Shelley Emling's got the answer to both of these questions in her recent book, The Fossil Hunter: Dinosaurs, Evolution, and the Woman Whose Discoveries Changed the World. She is Mary Anning and this pithy tongue-twister does no justice to her fascinating life as the world's first female paleontologist.

As for me, I had never heard of Mary Anning until just a few months ago when I caught an interview of Emling on the radio. She was discussing her biography of Anning along with another writer, Tracy Chevalier who had also recently published a novel inspired by Anning's life called Remarkable Creatures.

Here's a special guest post by Pamela King, a Northeastern University journalism student interning with NOVA's web team this semester. To read more of Pamela's work, visit her portfolio blog!

What can dogs do for us? Apart from companionship and the tasks of the occasional watchdog or service dog, canines seem to be the sole evolutionary beneficiaries of their relationship with their best friend, man. Stephen Budiansky even goes so far as to describe dogs as social parasites in his book, The Truth About Dogs, an excerpt of which appears on the companion web site for NOVA's Dogs and More Dogs.

But a recent study published in Molecular Psychiatry indicates canines might serve a purpose beyond being our cute, cuddly friends - dogs could provide insight into human mental health.

There has been a burst of research on restoring the blind's sight lately, including the development of an artificial retina and a gene therapy treatment that has brought fast and meaningful improvements in patients' vision. It sounds like in the not-too-distant future, blindness could be curable. But while we pour all our attention on the eye treatment, we neglect the fact that other organs could help "see" too - like the tongue.

Meet NOVA intern Bo Zhang, a graduate student in Boston University's science journalism story. In her first Inside NOVA post, Bo describes an electronic contact lens that can read your cholesterol level, blood sugar, and more--all from your eyeball. You can read more from Bo at Free Radicals, a brand new web magazine from the BU science journalism program. I'll hand the microphone over to Bo:

If your brain was a musical instrument, what kind of songs would it play?