Physics posts
- February 9, 2010
- 02:40 PM
- 599 views
Mobile Phones' Impact on Health
by amiya in Physiology physics woven fine
Mobile phones have drastically transformed our lives. Also known as cellular phones or cell phones, these gadgets not only incorporate a phone, as the name suggests, but also a lot of other technologically advanced features. They include a camera, a sound recorder cum music system, a Bluetooth device and many more depending on the model and the maker of the phone. They are called mobile phones since they can be used while on the move.A mobile phone maintains a two way (transmit and receive) comm........ Read more »
Gary W. Arendash, Juan Sanchez-Ramos, Takashi Mori, Malgorzata Mamcar, Xiaoyang Lin, Melissa Runfeldt, Li Wang, Guixin Zhang, Vasyl Sava, Jun Tan.... (2010) Electromagnetic Field Treatment Protects Against and Reverses Cognitive Impairment in Alzheimer's Disease Mice . Journal of Alzheimer's Disease, 191-210. info:/
- February 4, 2010
- 03:36 AM
- 1,576 views
The end of gravity as we know it?
by sarah in One Small Step
When a physicist is on the front page of a newspaper, you know the story is either really bad, or really good. Just before Christmas, the Dutch paper De Volkskrant ran a big story on theoretical physicist Erik Verlinde, who has been making waves with his new theory for the origin of gravity. Since the [...]... Read more »
Erik P. Verlinde. (2010) On the Origin of Gravity and the Laws of Newton. arxiv. arXiv: 1001.0785v1
- February 3, 2010
- 10:55 AM
- 970 views
Accelerated Twins: The Answer
by Chad Orzel in Uncertain Principles
Yesterday's post on a variation of the "Twin Paradox" with both twins accelerating was very successful-- 337 people voted in the first poll question, as of a little before 9am, and the comments to the original post are full of lively discussion. That's awesome.
I wish I could take credit for it, but the problem posed is not original to me. It comes from a 1989 paper in the American Journal of Physics, which also includes the following illustration setting up the situation:
The article contai........ Read more »
Boughn, S. (1989) The case of the identically accelerated twins. American Journal of Physics, 57(9), 791. DOI: 10.1119/1.15894
Desloge, E. (1991) Comment on ‘‘The case of the identically accelerated twins,’’ by S. P. Boughn [Am. J. Phys. 57, 791–793 (1989)]. American Journal of Physics, 59(3), 280. DOI: 10.1119/1.16580
- February 3, 2010
- 07:45 AM
- 653 views
The Attraction of Curves
by Brian Koberlein in Upon Reflection
Figure 1: Newton's gravity predicts an elliptical orbit for Mercury (similar to the red path). Mercury's orbit actually shifts over time (similar to the path in blue). Mercury's motion agrees with Einstein's model of gravity. (Source: Wikipedia) Last time I...... Read more »
Dyson, F., Eddington, A., & Davidson, C. (1920) A Determination of the Deflection of Light by the Sun's Gravitational Field, from Observations Made at the Total Eclipse of May 29, 1919. Philosophical Transactions of the Royal Society of London. Series A, Containing Papers of a Mathematical or Physical Character (1896-1934), 220(1), 291-333. DOI: 10.1098/rsta.1920.0009
- February 2, 2010
- 03:00 AM
- 573 views
What Enables Termites to Fly in Rain?
by Michael Long in Phased
Gregory Watson (James Cook University, Australia) and coworkers have discovered small-scale architecture on termite wings that imparts remarkable water-repelling properties, while adding only minimal weight to the wings, enabling a species of weak fliers to readily fly in rain. This news feature was written on February 2, 2010.... Read more »
Watson, G. S., Cribb, B. W., & Watson, J. A. (2010) How Micro/Nanoarchitecture Facilitates Anti-Wetting: An Elegant Hierarchical Design on the Termite Wing. ACS Nano, 4(1), 129-136. DOI: 10.1021/nn900869b
- January 31, 2010
- 12:31 AM
- 965 views
Magnetic fields in gamma-ray burst jets
by Charles Daney in Science and Reason
Gamma-ray bursts (GRBs) are the most dramatic short-lived violent events observed in the universe. They are often described as releasing a quantity of energy, in less than a minute, that is at least as much as a star like the Sun releases in its entire 10 billion year lifetime. Since the first detection of a gamma-ray burst in 1967, the central question has been to determine the nature of the process or processes that can release so much energy so quickly.We've discussed gamma-ray burst several ........ Read more »
Steele, I., Mundell, C., Smith, R., Kobayashi, S., & Guidorzi, C. (2009) Ten per cent polarized optical emission from GRB 090102. Nature, 462(7274), 767-769. DOI: 10.1038/nature08590
- January 29, 2010
- 04:45 AM
- 1,967 views
The Entropy of the Universe
by Alexander in The Astronomist.
First, what is entropy? The entropy of a system can be defined as proportional to (the natural log of) the number of microstates corresponding to the observed system macrostate. In this post I discuss a paper for anyone was wondering what the entropy of the observable Universe is.... Read more »
Chas A. Egan, & Charles H. Lineweaver. (2010) A Larger Estimate of the Entropy of the Universe. ApJ. arXiv: 0909.3983v3
- January 26, 2010
- 08:59 AM
- 1,249 views
Migratory Monarch Butterflies See Earth's GeoMagnetic Field
by GrrlScientist in Living the Scientific Life (Scientist, Interrupted)
tags: evolutionary biology, behavioral ecology, biochemistry, biophysics, magnetoreception, photochemical mechanism, cryptochromes, geomagnetic fields, butterflies, Monarch Butterfly, Danaus plexippus, birds, migration, Cryptochrome, bpr3.org/?p=52,peer-reviewed research, peer-reviewed paper
Every autumn, millions of monarch butterflies, Danaus plexippus, each weighing less than one gram (one US penny weighs 2.5 grams), migrate nearly 4000 kilometers (3000 miles) between their summer bree........ Read more »
Gegear, R., Foley, L., Casselman, A., & Reppert, S. (2010) Animal cryptochromes mediate magnetoreception by an unconventional photochemical mechanism. . Nature. DOI: 10.1038/nature08719
- January 25, 2010
- 11:14 AM
- 1,777 views
Single-Photon Cooling: Making Maxwell's Demon
by Chad Orzel in Uncertain Principles
As mentioned previously, I've been reading Sean Carroll's Wheel arrow of time book, which necessarily includes a good bit of discussion of "Maxwell's Demon," a thought experiment famously proposed by James Clerk Maxwell as something that would allow you to cool a gas without obviously increasing entropy. The "demon" mans a trapdoor between a sample of gas and an initially empty space, and allows only slow-moving gas atoms to pass through. After some time, the empty volume is filled with a gas at........ Read more »
Travis Bannerman, S., Price, G., Viering, K., & Raizen, M. (2009) Single-photon cooling at the limit of trap dynamics: Maxwell's demon near maximum efficiency. New Journal of Physics, 11(6), 63044. DOI: 10.1088/1367-2630/11/6/063044
Raizen, M. (2009) Comprehensive Control of Atomic Motion. Science, 324(5933), 1403-1406. DOI: 10.1126/science.1171506
- January 23, 2010
- 12:44 PM
- 639 views
Can science be artistic?
by nuclear.kelly in Miss Atomic Bomb
In light of the lack of effective communication between scientists (and science generally) and the public, I posed a challenge to the graduate students in my department: write a story about your research. It seemed a simple task, but there was one catch - the story had to be a fictional tale about their actual work.Can science be artistic? Is it only a chosen few who can turn science into the kind of thing that people on the street (or in the pub) find interesting; people like Carl Sagan, Brian ........ Read more »
Chipps, K., Blackmon, J., Chae, K., Moazen, B., Pittman, S., Greife, U., Hatarik, R., Peters, W., Kozub, R., Shriner, J.... (2009) The ^{17}F(p,γ)^{18}Ne resonant cross section. Physical Review C, 80(6). DOI: 10.1103/PhysRevC.80.065810
- January 22, 2010
- 08:00 AM
- 1,846 views
the bizarre oceans of the outer solar system
by Greg Fish in weird things
The outer solar system is a strange place. It’s a realm of frozen gas giants surrounded by icy moons and yet, it’s actually home to one of the most promising destinations for alien hunters in the solar system, offering an even more convincing argument for an alien biosphere than Mars to some. We’re talking about [...]... Read more »
Tyler, R. (2008) Strong ocean tidal flow and heating on moons of the outer planets. Nature, 456(7223), 770-772. DOI: 10.1038/nature07571
Eggert, J., Hicks, D., Celliers, P., Bradley, D., McWilliams, R., Jeanloz, R., Miller, J., Boehly, T., & Collins, G. (2009) Melting temperature of diamond at ultrahigh pressure. Nature Physics, 6(1), 40-43. DOI: 10.1038/nphys1438
- January 18, 2010
- 12:40 PM
- 786 views
Mirror Neurons: Resonant Circuitry in Brain?
by Amiya in Physiology physics woven fine
Back in the time of the “black and white” motion picture days, when “talkies” weren’t even born, we still could make out the essence of what Charlie Chaplin had to “say”. We understood his unspoken words, courtesy a system of neuronal networking, called the mirror neuron system. Another example: you observe a man kissing ‘his’ girlfriend, ‘your’ neuronal network that would otherwise activate when you ‘actually’ kissed her, would fire! Mirror neurons are at work. Seems t........ Read more »
Iacoboni M, Molnar-Szakacs I, Gallese V, Buccino G, Mazziotta JC, & Rizzolatti G. (2005) Grasping the intentions of others with one's own mirror neuron system. PLoS biology, 3(3). PMID: 15736981
- January 16, 2010
- 06:23 PM
- 1,295 views
The Moon, where the Helium-3 from the Sun is
by The Astronomist in The Astronomist.
Moon is a 2009 science fiction film about astronaut Sam Bell who is the solitary worker on the moon. Sam is at the end of a three-year stint on the Moon so the film begins as if it was the denouement of another quieter story. When an accident occurs Sam suddenly meets himself for the first time.I am adapt at finding flaws in science fiction films, but Moon nails a lot of science as well as could be expected. The most incredulous point about the film for me was the lack of a radio array on the fa........ Read more »
FA, W., & JIN, Y. (2007) Quantitative estimation of helium-3 spatial distribution in the lunar regolith layer. Icarus, 190(1), 15-23. DOI: 10.1016/j.icarus.2007.03.014
Heber, V., Baur, H., & Wieler, R. (2003) Helium in Lunar Samples Analyzed by High‐Resolution Stepwise Etching: Implications for the Temporal Constancy of Solar Wind Isotopic Composition. The Astrophysical Journal, 597(1), 602-614. DOI: 10.1086/378402
- January 16, 2010
- 03:15 AM
- 1,430 views
The Moon, Where helium-3 from the sun is
by Alexander in The Astronomist.
Moon is a 2009 science fiction film about astronaut Sam Bell who is a solitary miner on the moon. When Helium and fusion was mentioned at the beginning of the film I was delighted that they had based the story on a kernel of science. The energy source they are gathering from the moon is Helium-3. Helium-3 is a light isotope of helium with two protons and one neutron which is suitable as a fusion fuel. I have done some research into the literature to determine just how feasible this 3He min........ Read more »
FA, W., & JIN, Y. (2007) Quantitative estimation of helium-3 spatial distribution in the lunar regolith layer. Icarus, 190(1), 15-23. DOI: 10.1016/j.icarus.2007.03.014
Heber, V., Baur, H., & Wieler, R. (2003) Helium in Lunar Samples Analyzed by High‐Resolution Stepwise Etching: Implications for the Temporal Constancy of Solar Wind Isotopic Composition. The Astrophysical Journal, 597(1), 602-614. DOI: 10.1086/378402
- January 13, 2010
- 07:40 AM
- 523 views
And Yet It Moves
by Brian Koberlein in Upon Reflection
Figure 1: A painting of the trial of Galileo, by Cristiano Banti. (Source: UMKC) A famous story in the history of science is that of the trial of Galileo Galilei. Galileo believed that the Earth moved around the Sun, but...... Read more »
Foucault, M. (1851) Physical demonstration of the rotation of the earth by means of the pendulum. Journal of the Franklin Institute, 51(5), 350-353. DOI: 10.1016/0016-0032(51)90993-3
- January 8, 2010
- 09:10 PM
- 754 views
Mechanistic Insights into Supported Lipid Bilayer Formation
by Michael Long in Phased
Kuchnir Fygenson (University of California, Santa Barbara) and coworkers have gained physical insights relevant towards rendering planar lipid bilayers more useful for practical biological and engineering applications. This news feature was written on January 8, 2010.... Read more »
Weirich, K. L., Israelachvili, J. N., & Fygenson, D. K. (2010) Bilayer Edges Catalyze Supported Lipid Bilayer Formation. Biophysical Journal, 98(1), 85-92. DOI: 10.1016/j.bpj.2009.09.050
- January 6, 2010
- 06:53 PM
- 1,910 views
getting information from a black hole’s maw
by Greg Fish in weird things
Physicists are loath to break the laws by which the universe works when putting together their equations. They don’t fear a trip to physics jail or anything like that, but if their work requires a massive rearrangement of what we seem to understand, they tend to take it as a sign that somewhere along the [...]... Read more »
Gerard 't Hooft. (2009) Quantum gravity without space-time singularities or horizons. Erice Summerschool of Subnuclear Physics. arXiv: 0909.3426v1
- January 4, 2010
- 03:07 AM
- 902 views
Space is very fine-grained
by Charles Daney in Science and Reason
It would take you a lot longer to hike a significant distance over very hilly terrain than it would over a completely flat plain. For much the same reason, it would take light longer to cover the same distance depending whether the space through which it moves does or doesn't have large "hills".But what does it mean for space to contain "hills"? And how large do "hills" need to be to make a difference?Consider the second question first. There's no natural place on Earth that is perfectly flat, o........ Read more »
Abdo, A., Ackermann, M., Ajello, M., Asano, K., Atwood, W., Axelsson, M., Baldini, L., Ballet, J., Barbiellini, G., Baring, M.... (2009) A limit on the variation of the speed of light arising from quantum gravity effects. Nature, 462(7271), 331-334. DOI: 10.1038/nature08574
- December 31, 2009
- 09:00 AM
- 1,747 views
Radiation from CT scans: Balancing risks and benefits
by Orac in Respectful Insolence
NOTE: Orac is on semi-vacation this week, trying very hard to recharge his Tarial cells. Actually, although he is at home, he is spending much of his time in his Sanctum Sanctorum (i.e., his home office) working on an R01 for the February submission cycle. Given that the week between Christmas and New Years Day tends to be pretty boring, both from a blogging and blog traffic standpoint, he's scaling back the new, original stuff and mixing in some "best of" reruns, as well as some more recent stu........ Read more »
Berrington de Gonzalez, A., Mahesh, M., Kim, K., Bhargavan, M., Lewis, R., Mettler, F., & Land, C. (2009) Projected Cancer Risks From Computed Tomographic Scans Performed in the United States in 2007. Archives of Internal Medicine_id, 169(22), 2071-2077. http://archinte.ama-assn.org/cgi/doi/10.1001/archinternmed.2009.440
Smith-Bindman, R., Lipson, J., Marcus, R., Kim, K., Mahesh, M., Gould, R., Berrington de Gonzalez, A., & Miglioretti, D. (2009) Radiation Dose Associated With Common Computed Tomography Examinations and the Associated Lifetime Attributable Risk of Cancer. Archives of Internal Medicine, 169(22), 2078-2086. DOI: 10.1001/archinternmed.2009.427
Redberg RF. (2009) Cancer risks and radiation exposure from computed tomographic scans: how can we be sure that the benefits outweigh the risks?. Archives of internal medicine, 169(22), 2049-50. PMID: 20008685
Brenner DJ, & Hall EJ. (2007) Computed tomography--an increasing source of radiation exposure. The New England journal of medicine, 357(22), 2277-84. PMID: 18046031
- December 30, 2009
- 06:45 AM
- 1,120 views
2010, the year when 20/10 vision was promised
by Pablo Artal in Optics confidential
The promise of perfect "20/10" vision for everybody appeared to be a real possibility in the early 2000's. 2010 is already here and your doctor cannot offer you yet supervision...... Read more »
Santamaria, Artal, Bescos. (1987) Determination of the point spread function of human eyes using a hybrid optical-digital method. J.Opt.Soc.Am.A., 1109. info:/
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