all physics stories

DARPA awards interdisciplinary research team $1.2 million grant to study surface enhanced Raman scattering

404132862 — Thu, 17 Jul 2008 10:19:05 -0400

The Defense Advanced Research Projects Agency (DARPA) has awarded a $1.2 million grant to an interdisciplinary team of Harvard researchers to study surface enhanced Raman scattering (SERS) for the first phase of a potential three-year effort. If all phases of the development program
are completed, researchers could receive up a total of up to $2.9 million in funding.

Pioneer in spintronics celebrates birthday

404132862 — Fri, 07 Mar 2008 12:09:26 -0500

What might be Harvard’s oddest birthday party unfolded last over Feb. 29 and March 1. In a lecture hall at Maxwell Dworkin, 50 physicists gathered to share the latest research in spintronics, an emerging branch of their science concerned with the quantum spin states of electrons, and to honor one-time Soviet scientist Emmanuel I. Rashba who turned 80 last October.

‘Hot’ ice could lead to medical device

50443248 — Mon, 01 Oct 2007 15:28:19 -0400

Harvard physicists have shown that specially treated diamond coatings can keep water frozen at body temperature, a finding that may have applications in future medical implants.

Doctoral student Alexander Wissner-Gross and Efthimios Kaxiras, physics professor and Gordon McKay Professor of Applied Physics, spent a year building and examining computer models that showed that a layer of diamond coated with sodium atoms will keep water frozen up to 108 degrees Fahrenheit.

In ice, water molecules are arranged in a rigid framework that gives the substance its hardness. The process of melting is somewhat like a building falling down: pieces that had been arranged into a rigid structure move and flow against one another, becoming liquid water.

Light and matter united

Wed, 11 Jul 2007 12:04:48 -0400

Lene Hau has already shaken scientists' beliefs about the nature of things. Albert Einstein and just about every other physicist insisted that light travels 186,000 miles a second in free space, and that it can't be speeded-up or slowed down. But in 1998, Hau, for the first time in history, slowed light to 38 miles an hour, about the speed of rush-hour traffic.

Two years later, she brought light to a complete halt in a cloud of ultracold atoms. Next, she restarted the stalled light without changing any of its characteristics, and sent it on its way. These highly successful experiments brought her a tenured professorship at Harvard University and a $500,000 MacArthur Foundation award to spend as she pleased.

Measuring one of the universe's building blocks

Thu, 12 Jul 2007 14:37:46 -0400

Electrons are everywhere. There are trillions of them around you as you read this. They help make your computer, TV, cell phone - even the universe - work.

Every atom boasts a thin cloud of them orbiting its core, or nucleus. When they jump from one orbit to another, they create the electric and magnetic forces that power the universe. Their behaviors in the most energetic orbits determine the chemical properties of everything you can think of.

Using physics to understand biology

70652986 — Mon, 26 Mar 2007 06:23:38 -0400

Anita Goel is using the tools of physics to examine one of the most basic processes of biology, the way genetic information is extracted from DNA molecules and how this process is influenced by the environment.

Goel, an associate of the Physics Department, is hoping her unique approach will lead to both a new understanding of this critical and complex process and to new ways to manipulate and control it.

Goel completed Harvard's M.D.-Ph.D. program last spring, earning her doctorate in physics, rather than in biology or chemistry - fields more conventionally related to medicine.

But Goel, who was named one of the world's 35 most promising researchers under the age of 35 this fall by the Massachusetts Institute of Technology's Technology Review Magazine, said that she's always been intrigued by the ability of physics to explain the most basic processes of the universe, including those underlying life.

"We understand so much about atoms and molecules, but do we really understand the basic physics of life?"

Today Goel wears several hats as she seeks to illuminate those basic processes. She is continuing her academic research, which attempts to understand how an enzyme called DNA polymerase replicates a single molecule of DNA, reading and writing genetic information.

She views the polymerase as a tiny, nanoscale motor because it moves along a strand of DNA by converting chemical energy into the mechanical energy needed for movement, much like an automobile converts the chemical energy in gasoline into the vehicle's motion.

"DNA polymerase is a motor intrinsically. It converts chemical energy into mechanical motion. We're trying to look at it, probe it, and understand how it works - and how the environment around it influences its behavior," Goel said. "[We're asking,] 'Can we develop knobs that control the motor?'"

Drops in drops hold practical promise

50443248 — Tue, 24 Jul 2007 14:11:41 -0400

A team of Harvard researchers has developed a technique that allows the precise formation of double emulsions - droplets within droplets - that offers new ways to deliver drugs, nutrients, and other consumer and industrial products.
The team, led by Gordon McKay Professor of Applied Physics and Professor of Physics David Weitz, devised a technique using two tiny tubes that produces precisely-sized fluid droplets wrapped inside a second fluid and suspended in a third.

The advance has a wide potential range of applications in the pharmaceutical, food, cosmetic, and chemical industries. The double emulsions are potentially useful in any application where a product needs to be shielded from its surroundings for a period of time before being delivered.

Lasers produce slow, cold antiatoms

50443248 — Wed, 25 Jul 2007 15:17:10 -0400

A new way to make colder atoms of antimatter has been found. It could help bring scientists closer to understanding why we, and everything else, are made out of matter instead of antimatter.
According to the best theories, ordinary matter and its shadowy twin were created in approximately equal amounts when the universe came into existence some 14 billion years ago. If that's true, then where has all the antimatter gone?

"The imbalance is an embarrassing thing in physics, something we don't talk about," admits Gerald Gabrielse, Leverett Professor of Physics at Harvard University. To solve this universal mystery, researchers want to get a good look at antimatter atoms. To get such a view, they need a good way to slow them down.

Light propagates via wires more slender than its own wavelength

70652986 — Mon, 26 Mar 2007 05:33:37 -0400

A research team led by Harvard's Eric Mazur and Limin Tong, a visiting professor from Zhejiang University in China, reported on their work with nanowires in the Dec. 18, 2003 issue of the journal Nature. "You wouldn't normally imagine that a baseball could pass through a garden hose, but these nanowires appear able to handle exactly that kind of wide load," says Mazur, Harvard College professor, Gordon McKay Professor of Applied Physics, and professor of physics. "In some cases light is propagating along wires just one-third the width of its own wavelength. It's almost as if the wire serves as a rail to guide the light rather than funneling it in the traditional sense." The wires could aid in the development of optical chips that operate more rapidly and efficiently than today's electronic chips. The tiny structures could also be used to manipulate cells and other microscopic objects. The wires are so fine that they could poke into a cell or a droplet of liquid without disrupting them, yet are extremely sturdy - several times stronger than spider silk, one of the gold standards in the world of materials.

Scientists look inside antimatter

70652986 — Mon, 26 Mar 2007 05:25:53 -0400

"We have obtained the first glimpse inside an antihydrogen atom, and this is a significant step on the way to precision measurements that will allow matter/antimatter comparisons to be made," says Gerald Gabrielse, professor of physics at Harvard and leader of the research team. Such comparisons could show why antimatter and matter have not destroyed each other; in other words, why there's a universe at all. They also might cause physicists to scrap all their theories of how the universe operates. Although no one is making any claims at this point, practical applications might come from the research.

Harvard undergraduate discovers novel atomic cluster

70652986 — Mon, 26 Mar 2007 05:15:10 -0400

Eighteen-year-old Kevin Chan, a member of the Harvard College Class of 2004, used a supercomputer to discover a novel arrangement of atoms that had been missed by other scientists studying such clusters. Chan made the unexpected discovery in late June 2001 while working on a summer project at the San Diego Supercomputer Center (SDSC). Chan, a student majoring in mathematics, used a variation of a well-known mathematical technique to discover that 78 neutral atoms can theoretically settle into the shape of a particular "double icosahedron." Icosahedrons are 20-sided objects. Chan used a variant of a so-called "basin-hopping" algorithm developed by Robert Leary, an applied mathematician at SDSC under whom Chan worked during the summer.

Young star may be belching spheres of gas, astronomers say

70652986 — Mon, 26 Mar 2007 05:13:39 -0400

Observations by astronomers of a young star in the constellation Cepheus, more than 2000 lights-years away, suggest that it is repeatedly belching spheres of gas. Current theories about how young stars shed matter would not have predicted such eruptions. In order to remain stable while accumulating matter, young stars have to throw off some of the infalling material to avoid "spinning up" so fast they would break apart, according to those theories. But that infalling matter forms a thin spinning disk around the core of the new star, and material is ejected in twin "jets" perpendicular to the plane of the disk. Therefore, jets are expected, while spheres of gas are not.

Harvard researchers stop, restart, light

70652986 — Mon, 26 Mar 2007 05:04:31 -0400

Albert Einstein theorized that light cannot travel faster than 186,282 miles per second. But he never said it couldn't go slower. Lene Hau, a physics professor in the Faculty of Arts and Sciences at Harvard University, says Einstein would "probably be stunned" at the results of her recent experiments. Working in her laboratory at the Rowland Institute for Science, she and her colleagues slowed light 20 million-fold in 1999, to an incredible 38 miles an hour. They did it by passing a beam of light through a small cloud of atoms cooled to temperatures a billion times colder than those in the spaces between stars. Just recently, they were able to stop light completely. "In this odd state, light takes on a more human dimension; you can almost touch it," Hau says.

Thinnest wires probe superconductivity

70652986 — Mon, 26 Mar 2007 05:03:53 -0400

Wires made by a team of Harvard University researchers are almost too small to imagine – thousands of times thinner than a human hair and just millionths of an inch long. The long-term result may be computers much smaller and faster than the speediest supercomputers available today. Such supercomputers would be super cool, operating at about minus 458 degrees Fahrenheit. How small can such machines be? That depends on how small their wires can be made and still function as superconductors. No one knew the lower limits until Harvard physicists provided the first answer: roughly 5 millionths of a millimeter across (5 nanometers), or about 200 thousandths of an inch.

Closing in on the 'theory of everything'

70652986 — Mon, 26 Mar 2007 05:08:51 -0400

A single theory describing nature's four forces, called the "Theory of Everything," has been the Holy Grail for physicists and other scientists seeking the universe's deepest mysteries. Physicist Juan Maldacena has devised a way to explain gravity using a theory that also explains the other three basic forces of nature. And in this day of high-tech gadgets growing ever smarter and more powerful, Maldacena's breakthrough came not with the help of giant particle accelerators, complex computer programs, or powerful telescopes. Instead, Maldacena relied on two ancient tools: pen and paper. "I use computers sometimes, for e-mail or for exchanging information with colleagues," Maldacena said.