5/19/04
"University of Nevada research geophysicist Geoff Blewitt will present his findings on why the Earth wobbles in a lecture, 'GPS as a global sensor of systems Earth,' ...Astronomers have known for more than a century that the earth wobbles in space. Thanks to global positioning system (GPS) technologies, this wobble has been tracked with a precision of a few millimeters over the last decade. Until now, there were good theories as to why this happens, but no one could really prove it. Now, however, Blewitt has an explanation for this mysterious geo-wobble. 'The theory, which my colleagues and I have proven using GPS observations of the Earth, is that it's likely to be caused by the surface matter being redistributed,'' Blewitt said. "
The article: Richard S. Gross, Geoffrey Blewitt, Peter J. Clarke, David Lavallée. "Degree-2 harmonics of the Earth's mass load estimated from GPS and Earth rotation data" GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L07601, doi:10.1029/2004GL019589, 2004 (full text for subscribers)
We tend to think of the earth as just a solid ball making an even, smooth trip around the sun while it rotates on its axis. It's actually a lot more complicated: the earth's center is liquid, the surface weight distribution shifts, the pole precesses and nutates, the earth is actually flattened, the orbit is eccentric... Satellites can observe some of this wierdness and are used to measure it. I learned a lot of this information in my required Celestial Navigation classes but I'm remembering it now because PSIgate just added a record for an MIT OpenCourseWare class on Modern Navigation. Looking at the lecture notes provides a nice review.
Thursday, May 20, 2004
New Scientist: Wi-Fi networks can be jammed from PDAs
5/17/04 by Jeff Hecht
"Wi-Fi networks can be jammed using nothing more sophisticated than a PDA and an off-the-shelf wireless networking card, the Australian Computer Emergency Response Team has warned.
Wi-Fi networks are becoming common in workplaces and elsewhere and it was known that they are vulnerable to jamming. It was thought that this would require the use of large, powerful and expensive equipment, but students at the Queensland University of Technology have now proved this wrong."
This shouldn't come as too much of a surprise, but it is good to be reminded. The article goes on to mention that this susceptibility to jamming is due to the protocol and that smart systems can detect and deny access to jammers.
"Wi-Fi networks can be jammed using nothing more sophisticated than a PDA and an off-the-shelf wireless networking card, the Australian Computer Emergency Response Team has warned.
Wi-Fi networks are becoming common in workplaces and elsewhere and it was known that they are vulnerable to jamming. It was thought that this would require the use of large, powerful and expensive equipment, but students at the Queensland University of Technology have now proved this wrong."
This shouldn't come as too much of a surprise, but it is good to be reminded. The article goes on to mention that this susceptibility to jamming is due to the protocol and that smart systems can detect and deny access to jammers.
Tuesday, May 18, 2004
New Scientist: Micro-sculptures give metal the Velcro touch
5/14/04
"Minuscule shapes sculpted on metal surfaces could have a profound impact in many fields of engineering.
By training intense electron beams on the surface of metals, Bruce Dance and his team have found a way to fashion delicate metal projections that will act like ultra-strong Velcro to form much tougher joints between metals and lightweight composite materials in aircraft and cars."
Anything that lessens the need for the [environmentally] nasty adhesives.
"Minuscule shapes sculpted on metal surfaces could have a profound impact in many fields of engineering.
By training intense electron beams on the surface of metals, Bruce Dance and his team have found a way to fashion delicate metal projections that will act like ultra-strong Velcro to form much tougher joints between metals and lightweight composite materials in aircraft and cars."
Anything that lessens the need for the [environmentally] nasty adhesives.
Monday, May 17, 2004
Chemical & Engineering News: NanoFocus
Yet another nanotech website. This one's from ACS (C&EN and Nano Letters). The big news is that there's an RSS feed.
(aside– a funny quote from their site: "WHAT'S SO GREAT ABOUT NANOTECHNOLOGY? We're not sure yet, but lots of people are very excited about it.")
(aside– a funny quote from their site: "WHAT'S SO GREAT ABOUT NANOTECHNOLOGY? We're not sure yet, but lots of people are very excited about it.")
Washington Post: Language of Science Lags Behind Nanotech
Burgeoning Field in Need of Universal Way to Describe Creations
5/17/04; Page A07; by Rick Weiss
Nanotech inventors assign somewhat arbitrary names to new materials because for the most part there is no established taxonomy. Regular chemistry naming conventions are sometimes inadequate because the materials act differently on a nano level. Regulators and insurers both need to refer to materials with standard names.
5/17/04; Page A07; by Rick Weiss
Nanotech inventors assign somewhat arbitrary names to new materials because for the most part there is no established taxonomy. Regular chemistry naming conventions are sometimes inadequate because the materials act differently on a nano level. Regulators and insurers both need to refer to materials with standard names.
EurekAlert: Yale scientist says clues to string theory may be visible in Big Bang aftermath
5/12/04 (from Yale Press Release)
"Critics have disdained string theory as a “philosophy” that cannot be tested. However, the results of Easther and his colleagues suggest that observational evidence supporting string theory may be found in careful measurements of the Cosmic Microwave Background (CMB), the first light to emerge after the Big Bang."
Historically math and physics has been developed to explain/model observations. String theory goes past what is observable, or measurable to link quantum mechanics with Newtonian physics. Read Brian Greene's Elegant Universe for more.
"Critics have disdained string theory as a “philosophy” that cannot be tested. However, the results of Easther and his colleagues suggest that observational evidence supporting string theory may be found in careful measurements of the Cosmic Microwave Background (CMB), the first light to emerge after the Big Bang."
Historically math and physics has been developed to explain/model observations. String theory goes past what is observable, or measurable to link quantum mechanics with Newtonian physics. Read Brian Greene's Elegant Universe for more.
Friday, May 14, 2004
EurekAlert: Impact at Bedout: 'Smoking gun' of giant collision that nearly ended life on earth is identified
5/13/2004
"Evidence is mounting that 251 million years ago, long before the dinosaurs dominated the Earth, a meteor the size of Mount Everest smashed into what is now northern Australia, heaving rock halfway around the globe, triggering mass volcanic eruptions, and wiping out all but about ten percent of the species on the planet. The 'Great Dying,' as it's called, was by far the most cataclysmic extinction event in Earth's history, yet scientists have been unable to finger a culprit as they have with the dinosaur extinction. A new paper published in Science, however, claims to identify the crater made by that meteor, and it builds upon an ongoing body of evidence by researchers at the University of Rochester and the University of California at Santa Barbara (UCSB), that points the finger for the Great Dying squarely at the heavens. "
This is becoming a recurring theme on this blog (see here, here, and here). Scientist have evidence that impacts of NEOs caused 2 of the 5 known mass extinctions on earth. Luckily for us it seems to happen every few million years. See the article from Science: "Bedout: A Possible End-Permian Impact Crater Offshore of Northwestern Australia" by
L. Becker, R. J. Poreda, A. R. Basu, K. O. Pope, T. M. Harrison, C. Nicholson, R. Iasky. 5/13/04. DOI: 10.1126/science.1093925 (PDF for subscribers right now is here)
"Evidence is mounting that 251 million years ago, long before the dinosaurs dominated the Earth, a meteor the size of Mount Everest smashed into what is now northern Australia, heaving rock halfway around the globe, triggering mass volcanic eruptions, and wiping out all but about ten percent of the species on the planet. The 'Great Dying,' as it's called, was by far the most cataclysmic extinction event in Earth's history, yet scientists have been unable to finger a culprit as they have with the dinosaur extinction. A new paper published in Science, however, claims to identify the crater made by that meteor, and it builds upon an ongoing body of evidence by researchers at the University of Rochester and the University of California at Santa Barbara (UCSB), that points the finger for the Great Dying squarely at the heavens. "
This is becoming a recurring theme on this blog (see here, here, and here). Scientist have evidence that impacts of NEOs caused 2 of the 5 known mass extinctions on earth. Luckily for us it seems to happen every few million years. See the article from Science: "Bedout: A Possible End-Permian Impact Crater Offshore of Northwestern Australia" by
L. Becker, R. J. Poreda, A. R. Basu, K. O. Pope, T. M. Harrison, C. Nicholson, R. Iasky. 5/13/04. DOI: 10.1126/science.1093925 (PDF for subscribers right now is here)
Scientists discover secret of dolphin speed
Pointed out by EurekAlerts
"Physicists in Japan have discovered how the surface of a dolphin's skin reduces drag and helps them glide smoothly and quickly through water. These findings could help scientists design faster, energy-efficient boats, ocean liners, and submarines. This research is published in the Institute of Physics journal, Journal of Turbulence."
Hiroshi Nagamine, Kenji Yamahata, Yoshimichi Hagiwara and Ryoichi Matsubara."Turbulence modification by compliant skin and strata-corneas desquamation of a swimming dolphin" J. Turbulence v5 n18 (May 2004). For subscribers here.
Basically, dolphins shed skin very rapidly and it seems that this helps get rid of vortexes that form around the body. Pretty neat, but to construct an equivalent material for a man-made object, it would have to have many layers (like a pad of paper) and the part that sloughs off would have to be environmentally friendly.
"Physicists in Japan have discovered how the surface of a dolphin's skin reduces drag and helps them glide smoothly and quickly through water. These findings could help scientists design faster, energy-efficient boats, ocean liners, and submarines. This research is published in the Institute of Physics journal, Journal of Turbulence."
Hiroshi Nagamine, Kenji Yamahata, Yoshimichi Hagiwara and Ryoichi Matsubara."Turbulence modification by compliant skin and strata-corneas desquamation of a swimming dolphin" J. Turbulence v5 n18 (May 2004). For subscribers here.
Basically, dolphins shed skin very rapidly and it seems that this helps get rid of vortexes that form around the body. Pretty neat, but to construct an equivalent material for a man-made object, it would have to have many layers (like a pad of paper) and the part that sloughs off would have to be environmentally friendly.
NY Times: In a Road That's All Eyes, the Driver Finds an Ally
5/13/04 by Ian Austen
"Now, after perfecting illuminated markers that are embedded in the road surface to guide motorists through bad weather or warn of dangerous conditions, Mr. Dicks's company, Astucia Traffic Management Systems, is going a step further. Its latest creation is an embedded stud equipped with a camera that catches speeders, monitors traffic for criminals or stolen cars and even checks for bald tires on the fly."
Neat miniturization of technology. Generally, though, the Brits are much more accepting of government-run spy cameras in public places than Americans are. The illuminated markers would be very helpful in northern Florida where there are thunderstorms every afternoon.
"Now, after perfecting illuminated markers that are embedded in the road surface to guide motorists through bad weather or warn of dangerous conditions, Mr. Dicks's company, Astucia Traffic Management Systems, is going a step further. Its latest creation is an embedded stud equipped with a camera that catches speeders, monitors traffic for criminals or stolen cars and even checks for bald tires on the fly."
Neat miniturization of technology. Generally, though, the Brits are much more accepting of government-run spy cameras in public places than Americans are. The illuminated markers would be very helpful in northern Florida where there are thunderstorms every afternoon.
Wednesday, May 12, 2004
New Scientist: Computer chip noise may betray code
5/11/04
"The noise emitted by computer chips could help code breakers decipher encrypted messages, according to preliminary research carried out at the Weizmann Institute in Israel.
Adi Shamir and Eran Tromer sampled the high-frequency audio produced by computer central processing units (CPU) ... They discovered that they could distinguish between different cryptographic keys being processed by the chip, according to the frequency of the sound emitted. They also found they could determine the length of a string of characters by measuring the duration of certain sounds."
Very interesting. As fancy as computers are, it all still comes down to the physics of heat, sound, etc.
"The noise emitted by computer chips could help code breakers decipher encrypted messages, according to preliminary research carried out at the Weizmann Institute in Israel.
Adi Shamir and Eran Tromer sampled the high-frequency audio produced by computer central processing units (CPU) ... They discovered that they could distinguish between different cryptographic keys being processed by the chip, according to the frequency of the sound emitted. They also found they could determine the length of a string of characters by measuring the duration of certain sounds."
Very interesting. As fancy as computers are, it all still comes down to the physics of heat, sound, etc.
Monday, May 10, 2004
RedNova News: Is It Possible That Galileo Was Wrong?
5/8/04
"Some modern theories actually suggest that the acceleration of gravity does depend on the material composition of the object in a very subtle way,' says Jim Williams, a physicist at NASA's Jet Propulsion Laboratory (JPL). If so, the theory of relativity would need re-writing; there would be a revolution in physics."
Uh-oh. Now all those kids in basic mechanics classes can use this on their homework. Is this going to tell them enough to allow them to connect quantum mechanics with Newtonian physics, I doubt it, but it is very interesting.
"Some modern theories actually suggest that the acceleration of gravity does depend on the material composition of the object in a very subtle way,' says Jim Williams, a physicist at NASA's Jet Propulsion Laboratory (JPL). If so, the theory of relativity would need re-writing; there would be a revolution in physics."
Uh-oh. Now all those kids in basic mechanics classes can use this on their homework. Is this going to tell them enough to allow them to connect quantum mechanics with Newtonian physics, I doubt it, but it is very interesting.
Washington Post: NASA Weighs Robotic Mission To Aid Hubble
May 10, 2004, Guy Gugliotta, Page A01
"Early this year NASA had all but written off the Hubble Space Telescope, but today a robotic mission to replace worn-out batteries and gyros, and even to install new instruments, suddenly seems so doable that the agency is likely to ask for proposals to do the job in early June. "
It's a very complicated mission, but do-able. All of the public outrage about letting Hubble go sooner than scheduled probably had something to do with this.
"Early this year NASA had all but written off the Hubble Space Telescope, but today a robotic mission to replace worn-out batteries and gyros, and even to install new instruments, suddenly seems so doable that the agency is likely to ask for proposals to do the job in early June. "
It's a very complicated mission, but do-able. All of the public outrage about letting Hubble go sooner than scheduled probably had something to do with this.
Thursday, May 06, 2004
The New York Times :The Bionic Running Shoe
5/6/04 By Michel Marriott
"SHOES have long been sensible. Now some are getting smart. Smart enough, that is, to sense their environment electronically, calculate how best to perform in it, and then instantly alter their physical properties to adapt to that environment." The sensors in this shoe aren't so new, but the way it controls the cushioning is pretty neat. Overall this is a very interesting use of the sensors.
"SHOES have long been sensible. Now some are getting smart. Smart enough, that is, to sense their environment electronically, calculate how best to perform in it, and then instantly alter their physical properties to adapt to that environment." The sensors in this shoe aren't so new, but the way it controls the cushioning is pretty neat. Overall this is a very interesting use of the sensors.
Tuesday, May 04, 2004
Optics Express; Quantum key distribution with 1.25 Gbps clock synchronization
by J. C. Bienfang, A. J. Gross, A. Mink, B. J. Hershman, A. Nakassis, X. Tang, R. Lu, D. H. Su, Charles W Clark, and Carl J. Williams, National Institute of Standards and Technology; E. W. Hagley and Jesse Wen, Acadia Optronics LLC 4/27/04 (pointed out by Science Daily).
According to the ScienceDaily this is 100x faster than previously reported systems.
According to the ScienceDaily this is 100x faster than previously reported systems.
e4engineering.com: Protecting ships and rigs with polymer armour
By Stuart Nathan
"Microscopic polymer armour could allow researchers to develop effective and environmentally friendly anti-fouling coatings for ships and oil rigs, and prevent rejection of surgical implants."
The traditional coatings for ship hulls have been toxic chemicals (organotin and copper compounds) that kill off anything that tries to live on the hull. (Copper sheathing was used in the Napoleonic era, but that wasn't as effective). There are environmental and safety issues with the painting, resurfacing, and wear. I believe the US has outlawed these coatings in accordance with an IMO Convention. The rush is on to replace these with enzymatic coatings that affect the adhesion of the critters to the hull surfaces, but the enzymes break down fairly quickly. This article discusses a way to protect the enzymes so that the coating is effective for longer.
"Microscopic polymer armour could allow researchers to develop effective and environmentally friendly anti-fouling coatings for ships and oil rigs, and prevent rejection of surgical implants."
The traditional coatings for ship hulls have been toxic chemicals (organotin and copper compounds) that kill off anything that tries to live on the hull. (Copper sheathing was used in the Napoleonic era, but that wasn't as effective). There are environmental and safety issues with the painting, resurfacing, and wear. I believe the US has outlawed these coatings in accordance with an IMO Convention. The rush is on to replace these with enzymatic coatings that affect the adhesion of the critters to the hull surfaces, but the enzymes break down fairly quickly. This article discusses a way to protect the enzymes so that the coating is effective for longer.
PhysicsWeb: Beating the diffraction limit
By David R. Smith, May 2004
This overview article discusses the progress made in creating and using materials with negative indexes of refraction. So remember your basic optics, a wave traveling from a vacuum will bend toward the surface when it hits a material with a positive index. A negative index means that it will bend past the normal (>=180 deg). This means that you can have flat lenses and all kinds of neat things. The idea of a material with a negative index was developed in 1968, but it's now do-able because of materials research.
Update: 6/17/04, Contemporary Physics has a nice article by JB Pendry explaining this and reviewing the 200 recent articles (v.45 n.3 (Jun/Jul 04): 191-202.) Subscribers can resolve this doi to get it: 10.1080/00107510410001667434. (If you have it through Ingenta just work your normal magic to have that happen).
This overview article discusses the progress made in creating and using materials with negative indexes of refraction. So remember your basic optics, a wave traveling from a vacuum will bend toward the surface when it hits a material with a positive index. A negative index means that it will bend past the normal (>=180 deg). This means that you can have flat lenses and all kinds of neat things. The idea of a material with a negative index was developed in 1968, but it's now do-able because of materials research.
Update: 6/17/04, Contemporary Physics has a nice article by JB Pendry explaining this and reviewing the 200 recent articles (v.45 n.3 (Jun/Jul 04): 191-202.) Subscribers can resolve this doi to get it: 10.1080/00107510410001667434. (If you have it through Ingenta just work your normal magic to have that happen).
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