Image of the Day: Dasht-e Kavir

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Roughly 300 kilometers (200 miles) east-southeast of Tehran lies Iran’s Dasht-e Kavir, or Great Salt Desert. To the untrained eye, Dasht-e Kavir looks like a place that has been bone-dry since the dawn of time. But to the well-trained eyes of a geologist, this desert tells a tale of wetter times. Tens of millions of years ago, a salt-rich ocean likely occupied this region, surrounding a microcontinent in what is now central Iran.

Image credit: USGS/NASA Landsat 7

Startup with MIT roots wins R&D 100 Award

Leslie Bromberg, a research scientist at MIT’s Plasma Science and Fusion Center, and Alexander Sappok ’09 have been recognized by R&D Magazine for inventing one of the top 100 technologies of the year: the RF-DPF™ Diesel Particulate Filter Sensor. Sappok and Bromberg created the technology, which measures the amount, type, and distribution of contaminants on filters used to reduce engine and vehicle emissions, while Sappok was still a graduate student at MIT’s Sloan Automotive Laboratory.

The two first met when Bromberg attended Sappok’s Sloan Lab seminar about his research on diesel particulate filters (DPF).  “After the seminar, Leslie talked to me about an idea he had regarding the potential use of microwaves to try and measure the soot build-up inside the DPF,” Sappok notes. “The core idea was to use inexpensive circuit chips already mass produced for cell phones and other wireless devices in a new and unique application. Rather than transmitting data wirelessly, our approach was to monitor changes in the wireless signal itself, and use the signal to sense specific quantities of interest, such as soot, in the DPF.”

Bromberg had a number of DPFs in his lab, left over from plasma experiments focused on making auto engines burn fuel more cleanly and efficiently. In their spare time Bromberg and Sappok conducted preliminary tests, first using toothpicks to simulate soot loading in the tiny filter channels.  

From those early primitive measurements they were able to demonstrate the proof-of-concept, and over the next few years they worked on the idea, eventually building a business case around the technology. Entering the MIT $100K Entrepreneurship Competition in 2009, they made it to the semifinals for the MIT Clean Energy Prize. They also worked closely with MIT Venture Mentoring Service (VMS).

In 2009 Bromberg and Sappok formally incorporated their company as Filter Sensing Technologies, Inc. (FST). On the day of his graduation that year, Sappok received a letter from the National Science Foundation notifying him of a grant to further develop the technology.  This allowed FST to build a rough prototype and conduct an engine test at Oak Ridge National Laboratory to prove that the sensing method would work on an engine. The company has since grown, and in 2011 it received a $2 million grant from the U.S. Department of Energy to further develop and commercialize the technology.

Bromberg and Sappok expect their sensing technology to offer an economical alternative to the current pressure sensor-based controls, which measure the amount of contaminants indirectly and suffer from a large degree of error. The RF-DPF can measure the amount of soot and ash directly and more accurately, enabling improved engine control and reduced fuel consumption. Results from fleet testing with Volvo/Mack trucks operated by the New York City Department of Sanitation have shown the potential to reduce the DPF-related fuel consumption by up to a factor of two, and have helped attract interest from major engine and vehicle manufacturers and component suppliers.

By Paul Rivenberg | Plasma Science and Fusion Center

Image of the Day: Diatoms from Puget Sound, Washington

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A research team from the J. Craig Venter Institute (JCVI) and other institutions discovered that diatoms have an animal-like urea cycle, and that this cycle enables the diatoms to efficiently use carbon and nitrogen from their environment. The team believes the cycle could be a reason for the domination of diatoms in marine environments, especially after upwelling events–the upward movement of nutrient rich waters from the deep ocean to the surface. In response to ocean upwelling, diatoms are able to quickly recover from prolonged periods of nutrient deprivation and rapidly proliferate.

Image credit: Adrian Marchetti, University of Washington, and Andrew Allen, JCVI

Image of the Day: Cometary globule CG4

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The flower-like image of this star-forming region in Earth’s southern skies was imaged using a 64-megapixel Mosaic imaging camera on the National Science Foundation’s Victor M. Blanco telescope at Cerro Tololo Inter-American Observatory. Cometary globules are isolated, relatively small clouds of gas and dust within the Milky Way. This example, called CG4, is about 1,300 light years from Earth. Its head is some 1.5 light-years in diameter, and its tail is about eight light-years long. The dusty cloud contains enough material to make several sun-sized stars. CG4 is located in the constellation of Puppis.

Image credit: T.A. Rector/University of Alaska Anchorage, T. Abbott and NOAO/AURA/NSF

Image of the Day: Tie dye fly

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It may look like a poster for the Grateful Dead, but these day-glo rainbow stripes belong to a fruit fly. Duke biologist Amy Bejsovec is studying the patterns that emerge during a fruit fly’s development from egg to adult — information that may help treat diseases that arise when normal development goes awry. The red stripes stain a protein called Wingless, which helps cells grow and multiply and develop into different cell types. Blue marks cell nuclei. The green areas contain a protein that keeps Wingless in check — a key factor in avoiding cancer.

Image credit:

Amy Bejsovec, Duke University

Fluid mechanics suggests alternative to quantum orthodoxy

The central mystery of quantum mechanics is that small chunks of matter sometimes seem to behave like particles, sometimes like waves. For most of the past century, the prevailing explanation of this conundrum has been what’s called the “Copenhagen interpretation” — which holds that, in some sense, a single particle really is a wave, smeared out across the universe, that collapses into a determinate location only when observed.

But some founders of quantum physics — notably Louis de Broglie — championed an alternative interpretation, known as “pilot-wave theory,” which posits that quantum particles are borne along on some type of wave.  According to pilot-wave theory, the particles have definite trajectories, but because of the pilot wave’s influence, they still exhibit wavelike statistics.

John Bush, a professor of applied mathematics at MIT, believes that pilot-wave theory deserves a second look. That’s because Yves Couder, Emmanuel Fort, and colleagues at the University of Paris Diderot have recently discovered a macroscopic pilot-wave system whose statistical behavior, in certain circumstances, recalls that of quantum systems.

Couder and Fort’s system consists of a bath of fluid vibrating at a rate just below the threshold at which waves would start to form on its surface. A droplet of the same fluid is released above the bath; where it strikes the surface, it causes waves to radiate outward. The droplet then begins moving across the bath, propelled by the very waves it creates.

“This system is undoubtedly quantitatively different from quantum mechanics,” Bush says. “It’s also qualitatively different: There are some features of quantum mechanics that we can’t capture, some features of this system that we know aren’t present in quantum mechanics. But are they philosophically distinct?”

Tracking trajectories

Bush believes that the Copenhagen interpretation sidesteps the technical challenge of calculating particles’ trajectories by denying that they exist. “The key question is whether a real quantum dynamics, of the general form suggested by de Broglie and the walking drops, might underlie quantum statistics,” he says. “While undoubtedly complex, it would replace the philosophical vagaries of quantum mechanics with a concrete dynamical theory.”

Last year, Bush and one of his students — Jan Molacek, now at the Max Planck Institute for Dynamics and Self-Organization — did for their system what the quantum pioneers couldn’t do for theirs: They derived an equation relating the dynamics of the pilot waves to the particles’ trajectories.

In their work, Bush and Molacek had two advantages over the quantum pioneers, Bush says. First, in the fluidic system, both the bouncing droplet and its guiding wave are plainly visible. If the droplet passes through a slit in a barrier — as it does in the re-creation of a canonical quantum experiment — the researchers can accurately determine its location. The only way to perform a measurement on an atomic-scale particle is to strike it with another particle, which changes its velocity.

The second advantage is the relatively recent development of chaos theory. Pioneered by MIT’s Edward Lorenz in the 1960s, chaos theory holds that many macroscopic physical systems are so sensitive to initial conditions that, even though they can be described by a deterministic theory, they evolve in unpredictable ways. A weather-system model, for instance, might yield entirely different results if the wind speed at a particular location at a particular time is 10.01 mph or 10.02 mph.

The fluidic pilot-wave system is also chaotic. It’s impossible to measure a bouncing droplet’s position accurately enough to predict its trajectory very far into the future. But in a recent series of papers, Bush, MIT professor of applied mathematics Ruben Rosales, and graduate students Anand Oza and Dan Harris applied their pilot-wave theory to show how chaotic pilot-wave dynamics leads to the quantumlike statistics observed in their experiments.

What’s real?

In a review article appearing in the Annual Review of Fluid Mechanics, Bush explores the connection between Couder’s fluidic system and the quantum pilot-wave theories proposed by de Broglie and others.

The Copenhagen interpretation is essentially the assertion that in the quantum realm, there is no description deeper than the statistical one. When a measurement is made on a quantum particle, and the wave form collapses, the determinate state that the particle assumes is totally random. According to the Copenhagen interpretation, the statistics don’t just describe the reality; they are the reality.

But despite the ascendancy of the Copenhagen interpretation, the intuition that physical objects, no matter how small, can be in only one location at a time has been difficult for physicists to shake. Albert Einstein, who famously doubted that God plays dice with the universe, worked for a time on what he called a “ghost wave” theory of quantum mechanics, thought to be an elaboration of de Broglie’s theory. In his 1976 Nobel Prize lecture, Murray Gell-Mann declared that Niels Bohr, the chief exponent of the Copenhagen interpretation, “brainwashed an entire generation of physicists into believing that the problem had been solved.” John Bell, the Irish physicist whose famous theorem is often mistakenly taken to repudiate all “hidden-variable” accounts of quantum mechanics, was, in fact, himself a proponent of pilot-wave theory. “It is a great mystery to me that it was so soundly ignored,” he said.

Then there’s David Griffiths, a physicist whose “Introduction to Quantum Mechanics” is standard in the field. In that book’s afterword, Griffiths says that the Copenhagen interpretation “has stood the test of time and emerged unscathed from every experimental challenge.” Nonetheless, he concludes, “It is entirely possible that future generations will look back, from the vantage point of a more sophisticated theory, and wonder how we could have been so gullible.”

“The work of Yves Couder and the related work of John Bush … provides the possibility of understanding previously incomprehensible quantum phenomena, involving ‘wave-particle duality,’ in purely classical terms,” says Keith Moffatt, a professor emeritus of mathematical physics at Cambridge University. “I think the work is brilliant, one of the most exciting developments in fluid mechanics of the current century.”

By Larry Hardesty | MIT News Office

Alan Guth shares $1 million Kavli Prize in Astrophysics

Alan Guth, the Victor F. Weisskopf Professor of Physics at MIT, was awarded the Kavli Prize in Astrophysics, announced yesterday by the Kavli Foundation in Oslo, linked by satellite to a session at the World Science Festival in New York.

Guth will share the $1 million prize with Andrei Linde of Stanford University and Alexei Starobinsky of the Landau Institute for Theoretical Physics in Russia. Together, they are cited by the Kavli Foundation “for pioneering the theory of cosmic inflation.” 

Guth proposed the theory of cosmic inflation in 1980, the same year he joined the MIT faculty. The theory describes a period of extremely rapid exponential expansion within the first infinitesimal fraction of a second of the universe’s existence. At the end of inflation, approximately 14 billion years ago, the universe was in an extremely hot, dense, and small state, at the beginning of the more leisurely phase of expansion described by the conventional “Big Bang” theory. The conventional theory most successfully explains what happened after the bang, describing how the universe has cooled with expansion and how its expansion has been slowed by the attractive forces of gravity.

However, the conventional theory does not describe the mechanism that propelled the expansion of the universe in the first place, but the theory of cosmological inflation does: Guth hypothesized that the expansion of the universe was driven by repulsive gravitational forces generated by an exotic form of matter. Supported by three decades of development, including contributions from Linde, Andreas Albrecht, and Paul Steinhardt, Guth’s theory is now widely accepted by physicists.

The theory was further supported by an announcement in March by astronomers working on the Background Imaging of Cosmic Extragalactic Polarization telescope, which discovered evidence of gravitational waves produced by inflation. This experiment, however, has not yet been confirmed.

Cosmological inflation builds on general relativity’s description of gravity as a distortion of space-time, which allows for the possibility of repulsive gravity. At very high energies, like those that existed at the beginning of the universe, modern particle theory suggests that forms of matter that generate repulsive gravity should exist.

Inflation posits that this material inhabited at least a very small part of the universe, perhaps no more than 10-24 centimeters across, 100 billion times smaller than a proton. As the material began to expand, doubling every 10-37 seconds, any normal matter would thin out to a density of nearly zero.

Repulsive-gravity material behaves very differently, however, maintaining a constant density as it expands. While appearing to violate the principle of the conservation of energy, the constant density is enabled by an unusual feature of gravity: The energy of a gravitational field is negative.

As repulsive-gravity material exponentially expanded in the early universe, it created more and more energy in the form of matter. In turn, the gravitational field generated by matter created more and more negative energy.  The total energy remained constant. When inflation ended, the repulsive-gravity material decayed into a hot soup of the ordinary particles that would be the starting point for the conventional Big Bang.

Awarded in alternating years since 2008, the Kavli Prize recognizes outstanding scientific achievements in the categories of astrophysics, nanoscience, and neuroscience. Guth, along with this year’s eight other recipients, will be presented with the award by King Harald of Norway at a ceremony in Oslo on Sept. 9.

The Kavli Prize was established in 2005 by the founder of the Kavli Foundation, Fred Kavli, as well as Kristin Clemet, Norway’s minister of education and research, and Jan Fridthjof Bernt, president of the Norwegian Academy of Science and Letters. Before the prize was established, Guth met Kavli several times, including at a dinner Kavli organized to discuss his philanthropic goals with a contingent of physicists. While opinions at the table differed, the group advised him against establishing the Kavli Prize.

“I don’t think I voiced an opinion on that subject,” Guth says, “but now I’m glad that we didn’t talk him out of it. I now think that prizes of this sort actually do help to put scientists in the spotlight, and that helps to elevate the status of scientists in the eyes of young people choosing careers. Nobody should go into science for the money, but it is important that science is viewed as something valued by society. Through the prizes and also through his funding of Kavli Institutes around the world, including at MIT, Fred Kavli has been crucially important in furthering the cause of science.”

Guth’s previous honors include election to the National Academy of Sciences and the American Academy of Arts and Sciences; the Franklin Medal for Physics from the Franklin Institute; the Dirac Prize from the International Center for Theoretical Physics; the Cosmology Prize from the Peter Gruber Foundation; the Newton Prize of the Institute of Physics (U.K.); and the Fundamental Physics Prize of the Milner Foundation. 

By Bendta Schroeder | School of Science

Image of the Day: A star turns on

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Artist’s conception of the “boiling disk” surrounding the massive young stellar object known as Orion Source I. A disk of hot, ionized gas surrounds the central star, blocking our view. A cool wind of gas is driven from the upper and lower surfaces of the disk (as indicated by the colored arrows) and is sculpted into an hourglass shape by tangled magnetic field lines (shown as thin blue lines). This outflow is lit up by emission from silicon monoxide molecules – emission that has been imaged and tracked by radio astronomers month-to-month. The entire disk and wind are rotating, leading to observable Doppler shifts of the material entrained in the wind; redder colors represent material with a component of motion away from the observer (into the plane of the sky), while bluer colors represent material moving toward the observer (out of the plane of the sky).

Image credit: B. Saxton, NRAO/AUI/NSF

Image of the Day: Magnetic-optic materials

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Shown above are four-fold planar magnetic domains in a bismuth, rare-earth iron garnet thick film. Developed by Vincent Fratello and his research team at Integrated Photonics Inc., the film is an innovative solution to device problems that require high-speed, continuously varying polarization rotation with applied field. Potential applications include inexpensive magnetic and electromagnetic sensors and photonic devices for telecommunications and military applications, including variable optical attenuators, polarization controllers and increased speed magneto-optic switches.

Image credit: Integrated Photonics Inc.

Image of the Day: The Kepler field of view

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This photo is of the Kepler field of view, located between two bright stars in the summer triangle, rising over the WIYN telescope on Kitt Peak in southern Arizona. The NASA Kepler Space Telescope has confirmed about 1000 exoplanets, as well as thousands more stars considered “Kepler objects of interest,” stars that could possibly host planets. Until now, there has been an unanswered question about exoplanet host stars; how many host stars are binaries? A team of astronomers, led by Dr. Elliott Horch, Southern Connecticut State University, have shown that stars with exoplanets are just as likely to have a binary companion: that is, 40% to 50% of the host stars are actually binary stars.

Image credit: National Optical Astronomy Observatory

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