The vast wildfires of this summer and last represent a new normal for the western United States. They may signal a radical landscape transformation, one that will make the 21st century West an ecological frontier.
Unlike fires that have occurred regularly for thousands of years, these fires are so big and so intense as to create discontinuities in natural cycles. In the aftermath, existing forests may not return. New ecosystems will take their place.
“These transitions could be massive. They represent the convergence of several different forces,” said Donald Falk, a fire ecologist at the University of Arizona. “There is a tremendous amount of energy on the landscape that historically would not have been there. These are nuclear amounts of energy.”
Hunting for meteorites may sound like a cool way to spend an afternoon, but imagine doing it from an airship.
A couple weeks after a meteorite blazed to Earth April 22 over California’s Sierra Nevada mountains, a team of researchers flew aboard the commercial airship Eureka to try to search for pieces of the space rock.
The 10-foot hunk of rock, about the size of a car, burned to pieces in the air above Sutter’s Mill, the site where gold was first found in California. A thunderous boom announced its arrival, and scientists raced up to the site to look for pieces of the meteorite. They only found disappointingly small pieces, but it was enough to determine the meteorite was a rare, carbon-containing type. Studying it could help scientists learn how the building blocks for life — like carbon, nitrogen and oxygen — ended up on Earth.
The meteorite’s fall ranged over about 20 miles, so the best bet for finding more pieces was to look for scars in the landscape from the air.
“An airship is perfect, because it flies at 1,000 feet and it moves very gradually, very relaxed,” said astronomer Peter Jenniskens at SETI Institute and NASA Ames Research Center, who led the airship search party.
This week NASA released an ultra-high-resolution view of the frigid Martian landscape captured by the only rover currently operating on the red planet.
“The view provides … a spectacularly detailed view of the largest impact crater that we’ve driven to yet,” said planetary scientist Jim Bell of Arizona State University in a press release July 5.
The solar-powered, golf-cart-sized rover, called Opportunity, wrapped up exploration of the half-mile-wide Victoria Crater in August 2008. It then rolled for the next three years to reach the 14-mile-wide Endeavour Crater.
But the plucky robot must hunker down during Martian winters that last six Earth months, as Opportunity needs to have enough power to warm its fragile electronics. So from Dec. 21, 2011 through May 8, 2012, NASA instructed the robot to stay put and take 817 images.
If you’re a Wallace and Gromit fan, you’ll want a look at this pair of robotic legs, which a group of researchers claim are the first to model walking in a biologically accurate manner.
No, you can’t wear them like Wallace did — these pants walk alone. But they do have features that imitate biological muscles, sensors and nervous-system control. The research, published today in the Journal of Neuroengineering by researchers from the University of Arizona, could help us understand how human babies learn to walk.
The robot’s legs are made from plastic using a 3D printer, and the ”muscles” consist of motors that pull on kevlar straps to bend and straighten the legs. Force sensors in the straps endow the robot with proprioception, the human body’s sense of its limb positions and movements.
To better mimic walking in humans, the computer that controls the legs acts like a central pattern generator, or CPG, the neural network in our spinal cords responsible for the rhythmic, mindless quality of walking. The researchers used a simple “half-center CPG” consisting of two signals firing alternately to flex and then extend each leg. The movement allows slight adjustments for sensory feedback, in a reflex-like manner.
The mechanical legs represent a simplified model of how real legs function. The legs can amble successfully at a range of walking frequencies, and the CPG signals greatly stabilize the walking movement, showing the importance of top-down control in the nervous system, as opposed to merely reflex-based control.
The robo-legs totter like a toddler in a baby walker, and the researchers suggest that babies might use a simple CPG like the robot’s, and develop more complex control patterns as they age.
Stephen Wolfram’s diverse areas of research include mathematics, physics, and computing. Though his early career was focused on particle physics, he went on to create the widely used computer algebra system Mathematica and, later, the search engine Wolfram Alpha. He is author of A New Kind of Science — a study of simple computational systems such as cellular automata — and current CEO of Wolfram Research.
The announcement early yesterday morning of experimental evidence for what’s presumably the Higgs particle brings a certain closure to a story I’ve watched (and sometimes been a part of) for nearly 40 years. In some ways I felt like a teenager again. Hearing about a new particle being discovered. And asking the same questions I would have asked at age 15. “What’s its mass?” “What decay channel?” “What total width?” “How many sigma?” “How many events?”
Stephen Wolfram
When I was a teenager in the 1970s, particle physics was my great interest. It felt like I had a personal connection to all those kinds of particles that were listed in the little book of particle properties I used to carry around with me. The pions and kaons and lambda particles and f mesons and so on. At some level, though, the whole picture was a mess. A hundred kinds of particles, with all sorts of detailed properties and relations. But there were theories. The quark model. Regge theory. Gauge theories. S-matrix theory. It wasn’t clear what theory was correct. Some theories seemed shallow and utilitarian; others seemed deep and philosophical. Some were clean but boring. Some seemed contrived. Some were mathematically sophisticated and elegant; others were not.
By the mid-1970s, though, those in the know had pretty much settled on what became the Standard Model. In a sense it was the most vanilla of the choices. It seemed a little contrived, but not very. It involved some somewhat sophisticated mathematics, but not the most elegant or deep mathematics. But it did have at least one notable feature: of all the candidate theories, it was the one that most extensively allowed explicit calculations to be made. They weren’t easy calculations—and in fact it was doing those calculations that got me started having computers to do calculations, and set me on the path that eventually led to Mathematica. But at the time I think the very difficulty of the calculations seemed to me and everyone else to make the theory more satisfying to work with, and more likely to be meaningful.
At the least in the early years there were still surprises, though. In November 1974 there was the announcement of the J/psi particle. And one asked the same questions as today, starting with “What’s the mass?” (That particle’s was 3.1 GeV; today’s is 126 GeV.) But unlike with the Higgs particle, to almost everyone the J/psi was completely unexpected. At first it wasn’t at all clear what it could be. Was it evidence of something truly fundamental and exciting? Or was it in a sense just a repeat of things that had been seen before?
