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  • richardmitnick 10:51 am on May 13, 2011 Permalink | Reply
    Tags: , MIT Physics,   

    From MIT News: “Toward faster transistors” 

    MIT physicists discover a new physical phenomenon that could eventually lead to the first increases in computers’ clock speed since 2002.

    Larry Hardesty, MIT News Office

    “In the 1980s and ’90s, competition in the computer industry was all about “clock speed” — how many megahertz, and ultimately gigahertz, a chip could boast. But clock speeds stalled out almost 10 years ago: Chips that run faster also run hotter, and with existing technology, there seems to be no way to increase clock speed without causing chips to overheat.

    In this week’s issue of the journal Science, MIT researchers and their colleagues at the University of Augsburg in Germany report the discovery of a new physical phenomenon that could yield transistors with greatly enhanced capacitance — a measure of the voltage required to move a charge. And that, in turn, could lead to the revival of clock speed as the measure of a computer’s power.”

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    MIT researchers and colleagues at the University of Augsburg, in Germany, investigated the curious electrical properties of a material produced by stacking layers of lanthanum aluminate on layers of strontium titanate.

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    The researchers’ experimental setup consisted of a sample of the lanthanum aluminate-strontium titanate composite, which looks like a slab of thick glass, with thin electrodes deposited on top of it.

    See the full exciting article here.

     
  • richardmitnick 5:59 am on May 11, 2011 Permalink | Reply
    Tags: , , MIT Physics   

    From M.I.T. News: “Evolution, reversed” 

    Physicists’ study of evolution in bacteria shows that adaptations can be undone, but rarely.

    Anne Trafton, MIT News Office

    “Ever since Charles Darwin proposed his theory of evolution in 1859, scientists have wondered whether evolutionary adaptations can be reversed.

    Answering that question has proved difficult, partly due to conflicting evidence. In 2003, scientists showed that some species of insects have gained, lost and regained wings over millions of years. But a few years later, a different team found that a protein that helps control cells’ stress responses could not evolve back to its original form.

    Jeff Gore, assistant professor of physics at MIT, says the critical question to ask is not whether evolution is reversible, but under what circumstances it could be. ‘ It’s known that evolution can be irreversible. And we know that it’s possible to reverse evolution in some cases. So what you really want to know is: What fraction of the time is evolution reversible?’ he says.”

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    Graphic: Patrick Gillooly

    See the full article here.

     
  • richardmitnick 6:43 am on March 29, 2011 Permalink | Reply
    Tags: MIT Physics,   

    From M.I.T. news: “A new spin on superconductivity?” 

    Scientists produce a crystal that could help unlock the mystery of high-temperature superconductors.

    Anne Trafton, MIT News Office
    March 29, 2011

    “MIT scientists have synthesized, for the first time, a crystal they believe to be a two-dimensional quantum spin liquid: a solid material whose atomic spins continue to have motion, even at absolute zero temperature.

    The crystal, known as herbertsmithite, is part of a family of crystals called Zn-paratacamites, which were first discovered in 1906. Physicists started paying more attention to quantum spin liquids in 1987, when Nobel laureate Philip W. Anderson theorized that quantum spin liquid theory may relate to the phenomenon of high-temperature superconductivity, which allows materials to conduct electricity with no resistance at temperatures above 20 degrees Kelvin (-253 degrees Celsius).

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    MIT physicists grew this pure crystal of herbertsmithite in their laboratory. This sample is 7 mm long and weighs 0.2 grams.
    Image: Tianheng Han

    See the full article here.

     
  • richardmitnick 4:28 pm on March 1, 2011 Permalink | Reply
    Tags: , MIT Physics   

    From MIT News: “Explained: Quark gluon plasma” 

    This is old, but it is really good.

    Anne Trafton, MIT News Office
    June 9, 2010

    http://web.mit.edu/newsoffice/2010/exp-quark-gluon-0609.html

    “For a few millionths of a second after the Big Bang, the universe consisted of a hot soup of elementary particles called quarks and gluons. A few microseconds later, those particles began cooling to form protons and neutrons, the building blocks of matter.

    Over the past decade, physicists around the world have been trying to re-create that soup, known as quark-gluon plasma (QGP), by slamming together nuclei of atoms with enough energy to produce trillion-degree temperatures.

    ‘If you’re interested in the properties of the microseconds-old universe, the best way to study it is not by building a telescope, it’s by building an accelerator,’ says Krishna Rajagopal, an MIT theoretical physicist who studies QGP.

    Quarks and gluons, though they make up protons and neutrons, behave very differently from those heavier particles. Their interactions are governed by a theory known as quantum chromodynamics, developed in part by MIT professors Jerome Friedman and Frank Wilczek, who both won Nobel prizes for their work. However, the actual behavior of quarks and gluons is difficult to study because they are confined within heavier particles. The only place in the universe where QGP exists is inside high-speed accelerators, for the briefest flashes of time.

    In 2005, scientists at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory reported creating QGP by smashing gold atoms together at nearly the speed of light. These collisions can produce temperatures up to 4 trillion degrees — 250,000 times warmer than the sun’s interior and hot enough to melt protons and neutrons into quarks and gluons.

    The resulting super-hot, super-dense blob of matter, about a trillionth of a centimeter across, could give scientists new insights into the properties of the very early universe. So far, they have already made the surprising discovery that QGP is a nearly frictionless liquid, not the gas that physicists had expected.

    By doing higher-energy collisions, scientists now hope to find out more about the properties of quark gluon plasma and whether it becomes gas-like at higher temperatures. They also want to delve further into the very surprising similarities that have been seen between QGP and ultracold gases (near absolute zero) that MIT’s Martin Zwierlein and others have created in the laboratory. Both substances are nearly frictionless, and theoretical physicists suspect that string theory may explain both phenomena, says Rajagopal.

    At the Large Hadron Collider in Geneva, MIT faculty Gunther Roland, Wit Busza and Boleslaw Wyslouch are among the physicists planning to double the temperature achieved at Brookhaven, offering a glimpse of an even-earlier stage of the universe’s formation.”

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    A visualization of one of the first full-energy collisions between gold ions at Brookhaven Lab’s Relativistic Heavy Ion Collider, as captured by the Solenoidal Tracker At RHIC (STAR) detector. Image: Brookhaven National Laboratory


    MIT News Office

     
  • richardmitnick 3:47 pm on January 13, 2011 Permalink | Reply
    Tags: , MIT Physics   

    From MIT News:”And then there was light” 

    Morgan Bettex, MIT News Office
    January 13, 2011

    “In the beginning, there was no light.

    After the Big Bang created the universe 13 billion years ago, the universe remained enshrouded in darkness. Based on observations of the radiation left over from the Big Bang, astronomers have theorized that several hundred million years after this event, gravity caused hydrogen and helium particles to condense into clouds. The energy from this activity eventually ignited those clouds, setting in motion a chain of events that led to the birth of the first stars. Although the transition between the so-called cosmic dark ages and the birth of stars and galaxies may explain the origin and evolution of many celestial objects, astronomers know very little about this period.

    Recently, two astronomers conducted an experiment to try to learn more about this transitional period, which is known as the Epoch of Reionization, or EOR. Because identifying any light from the earliest galaxies is nearly impossible, Alan Rogers, a research affiliate at MIT’s Haystack Observatory, and Judd Bowman, an assistant professor at Arizona State University, instead focused their efforts on detecting radio waves emitted by hydrogen that existed between the first galaxies. Some of these radio waves are just reaching us today, and astronomers have theorized that certain characteristics of the waves could hold clues about the EOR”

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    Close up of the EDGES antenna. The four panels are made from aluminum sheet metal and supported by PVC legs. The white bag under the antenna encloses analog amplifiers and calibration circuits.
    Photo: Judd Bowman/Arizona State University

    Read the full article here.

     
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