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A place for rational thoughts, randomly seeded on physics, astronomy, science, culture, design, technology, philosophy, art, and of course intergalactic space travel.
The Astronomist
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- April 12, 2012
- 09:49 PM
- 937 views
Disassociate Galaxy Clusters
by The Astronomist in The Astronomist.
A dissociative galaxy cluster is a cluster of galaxies that just can't keep it together any longer. This may sound like an unnecessary anthropomorphication of galaxies, but it is actually a description of galaxy clusters which have collided and experienced stratification of their constituent parts. In the standard and successful model of cosmology the largest scale structures in the universe, like super clusters of thousands of galaxies, form via the merger of filamentary structures compose........ Read more »
Dawson, W., Wittman, D., Jee, M., Gee, P., Hughes, J., Tyson, J., Schmidt, S., Thorman, P., Bradač, M., Miyazaki, S.... (2012) DISCOVERY OF A DISSOCIATIVE GALAXY CLUSTER MERGER WITH LARGE PHYSICAL SEPARATION. The Astrophysical Journal, 747(2). DOI: 10.1088/2041-8205/747/2/L42
Jee, M., Mahdavi, A., Hoekstra, H., Babul, A., Dalcanton, J., Carroll, P., & Capak, P. (2012) A STUDY OF THE DARK CORE IN A520 WITH THE : THE MYSTERY DEEPENS . The Astrophysical Journal, 747(2), 96. DOI: 10.1088/0004-637X/747/2/96
Markevitch, M., Gonzalez, A., Clowe, D., Vikhlinin, A., Forman, W., Jones, C., Murray, S., & Tucker, W. (2004) Direct Constraints on the Dark Matter Self‐Interaction Cross Section from the Merging Galaxy Cluster 1E 0657−56. The Astrophysical Journal, 606(2), 819-824. DOI: 10.1086/383178
- December 12, 2011
- 03:10 PM
- 3,369 views
The First Quantum Computer
by The Astronomist in The Astronomist.
In a nondescript office park outside Vancouver with views of snow capped mountains in the distance is a mirrored business park where very special work is being done. The company is D-Wave, the quantum computing company. D-Wave's mission is to build a computer which will solve humanity's grandest challenges.D-Wave aims to develop the first quantum computer in the world, perhaps they already have. The advent of quantum computers would be a sea change in the world that would allow for breaking of c........ Read more »
Harris, R., Johansson, J., Berkley, A., Johnson, M., Lanting, T., Han, S., Bunyk, P., Ladizinsky, E., Oh, T., Perminov, I.... (2010) Experimental demonstration of a robust and scalable flux qubit. Physical Review B, 81(13). DOI: 10.1103/PhysRevB.81.134510
Harris, R., Johnson, M., Han, S., Berkley, A., Johansson, J., Bunyk, P., Ladizinsky, E., Govorkov, S., Thom, M., Uchaikin, S.... (2008) Probing Noise in Flux Qubits via Macroscopic Resonant Tunneling. Physical Review Letters, 101(11). DOI: 10.1103/PhysRevLett.101.117003
- July 27, 2011
- 04:26 AM
- 1,234 views
A Cubic Millimeter of Your Brain
by The Astronomist in The Astronomist.
Are there more connections in a cubic millimeter of your brain than there are stars in the Milky Way? We are going to answer that question in a moment, but first take a look at this image of hippocampal neurons in a mouse's brain. It is an actual color image from a transgenic mouse in which fluorescent protein variations are expressed quasi-randomly in different neurons. This kind of image is known as a brainbow and is aesthetically awesome further it may we one way to empirically examine a volu........ Read more »
Marois, R., & Ivanoff, J. (2005) Capacity limits of information processing in the brain. Trends in Cognitive Sciences, 9(6), 296-305. DOI: 10.1016/j.tics.2005.04.010
Allen, J., Damasio, H., & Grabowski, T. (2002) Normal neuroanatomical variation in the human brain: An MRI-volumetric study. American Journal of Physical Anthropology, 118(4), 341-358. DOI: 10.1002/ajpa.10092
- March 25, 2011
- 11:01 PM
- 1,516 views
Naming the Unknown #1
by The Astronomist in The Astronomist.
Naming the Unknown is a new series where I highlight interesting papers in astrophysics. Research papers which I find compelling or of general interest will be spotlighted. The title 'Naming the Unknown' comes from accusation that cosmologists have simply begun to come up with names for those things which are not understood; yet, I do not think that anyone would claim that science is at times anything other than coming up with names for the unknown. Scientists define the unknown in terms of the ........ Read more »
Crocker, R., & Aharonian, F. (2011) Fermi Bubbles: Giant, Multibillion-Year-Old Reservoirs of Galactic Center Cosmic Rays. Physical Review Letters, 106(10). DOI: 10.1103/PhysRevLett.106.101102
- February 25, 2011
- 06:27 PM
- 1,372 views
Fusion for the Future: NIF
by The Astronomist in The Astronomist.
Fusion is only 50 years away and it will solve all of the worlds energy problems. That is the good news. The bad news is that it has been 50 years away for the last 50 years. If that situation is maddening to you then you are not alone. Leonardo Mascheroni, a retired Los Alamos National Laboratory physicist, wanted funding to build a colossal laser for producing energy from fusion and was willing to trade the United States' nuclear weapons secrets to realize his dream. Mascheroni was recently in........ Read more »
Glenzer, S., MacGowan, B., Michel, P., Meezan, N., Suter, L., Dixit, S., Kline, J., Kyrala, G., Bradley, D., Callahan, D.... (2010) Symmetric Inertial Confinement Fusion Implosions at Ultra-High Laser Energies. Science, 327(5970), 1228-1231. DOI: 10.1126/science.1185634
- January 21, 2011
- 08:41 PM
- 1,686 views
The Universe and Life is asymmetric: Chirality
by The Astronomist in The Astronomist.
The shadow of symmetry haunts physics. Symmetry is invoked to understand nature concisely, but broken symmetry is invoked to understand nature completely. Physics is filled with examples of shattered symmetries: there is more matter than antimatter, neutrinos only come in the left handed spin flavor, and quantum processes break symmetries constantly, but nature also violates symmetry in chemistry and biology in a very clever manner. Chemistry and biology are subjects I do no normally touch ........ Read more »
Robert N. Compton, Richard M. Pagni, & Volume 48, 2002, Pages 219-261. (2002) The chirality of biomolecules. Advances In Atomic, Molecular, and Optical Physics, 219-261. info:/
- December 16, 2010
- 08:56 PM
- 1,615 views
Supermassive Black Holes
by The Astronomist in The Astronomist.
A black hole is a massive object with such powerful gravity that not even light may escape from it. Black holes only have three unique properties which are mass, charge, and spin. At one time black holes were a speculative phenomena, but astronomers now understand that black holes are a relatively common and important occurrence in our Universe, unfortunately the public and science fiction still seems to be in dark. There are a lot of misconceptions about black holes:If the Sun was replaced........ Read more »
Gebhardt, K., Bender, R., Bower, G., Dressler, A., Faber, S., Filippenko, A., Green, R., Grillmair, C., Ho, L., Kormendy, J.... (2000) A Relationship between Nuclear Black Hole Mass and Galaxy Velocity Dispersion. The Astrophysical Journal, 539(1). DOI: 10.1086/312840
Genzel, R., Schödel, R., Ott, T., Eckart, A., Alexander, T., Lacombe, F., Rouan, D., & Aschenbach, B. (2003) Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre. Nature, 425(6961), 934-937. DOI: 10.1038/nature02065
Ghez, A., Salim, S., Weinberg, N., Lu, J., Do, T., Dunn, J., Matthews, K., Morris, M., Yelda, S., Becklin, E.... (2008) Measuring Distance and Properties of the Milky Way’s Central Supermassive Black Hole with Stellar Orbits. The Astrophysical Journal, 689(2), 1044-1062. DOI: 10.1086/592738
- October 30, 2010
- 10:05 PM
- 1,843 views
Very precise pulsar measurements
by The Astronomist in The Astronomist.
A neutron star is made of neutrons, right? Astrophysicists ponder this question and forge theory after theory, but the only thing they conclude with certainty is that a neutron star by any other name would still be made of the densest form of matter know to exist in our Universe. Under certain conditions a star which has exhausted all of its fuel and is sufficiently massive will not be able to support its own weight with pressure support (as in a regular star) or with electron degeneracy support........ Read more »
Demorest PB, Pennucci T, Ransom SM, Roberts MS, & Hessels JW. (2010) A two-solar-mass neutron star measured using Shapiro delay. Nature, 467(7319), 1081-3. PMID: 20981094
D. J. Champion, G. B. Hobbs, R. N. Manchester, R. T. Edwards, D. C. Backer, M. Bailes, N. D. R. Bhat, S. Burke-Spolaor, W. Coles, P. B. Demorest.... (2010) Measuring the mass of solar system planets using pulsar timing. ApJ. arXiv: 1008.3607v1
- October 16, 2010
- 09:37 PM
- 1,700 views
The Goldilocks Planet
by The Astronomist in The Astronomist.
Once upon a time there was a planet named Earth. It orbited exactly one astronomical unity away from a G2V type star. Billions of years went by and Earth found that it lived right in the habitable zone where liquid water was maintained on it surface and life spontaneously arose. Pretty soon life on Earth became restless, questioned its own existence, and looked for life on Gliese 581. Earthlings found many planets and exclaimed, 'Gliese 581 b is too hot, Gilese 581 c is slightly too hot, Glies........ Read more »
Steven S. Vogt, R. Paul Butler, Eugenio J. Rivera, Nader Haghighipour, Gregory W. Henry, . (2010) The Lick-Carnegie Exoplanet Survey: A 3.1 M_Earth Planet in the Habitable Zone of the Nearby M3V Star Gliese 581. ApJ accepted. info:/arXiv: 1009.5733v1
- September 13, 2010
- 06:38 PM
- 1,717 views
Magnetic Fields in Cosmology
by The Astronomist in The Astronomist.
The existence of magnetic fields on cosmologically large scales is an unsolved problem in astrophysics. Theory favors a universe that did not begin with any magnetic fields present and classical magnetohydrodynamics restricts the spontaneous emergence of a magnetic state under the influence of ideal forces. In a paper entitled Twisting Space-Time: Relativistic Origin of Seed Magnetic Field and Vorticity appearing Physical Review letters Swadesh Mahajan and Zensho Yoshida propose a universal magn........ Read more »
Beck, R., Brandenburg, A., Moss, D., Shukurov, A., & Sokoloff, D. (1996) GALACTIC MAGNETISM: Recent Developments and Perspectives. Annual Review of Astronomy and Astrophysics, 34(1), 155-206. DOI: 10.1146/annurev.astro.34.1.155
Davis, A., Lilley, M., & Törnkvist, O. (1999) Relaxing the bounds on primordial magnetic seed fields. Physical Review D, 60(2). DOI: 10.1103/PhysRevD.60.021301
Mahajan, S., & Yoshida, Z. (2010) Twisting Space-Time: Relativistic Origin of Seed Magnetic Field and Vorticity. Physical Review Letters, 105(9). DOI: 10.1103/PhysRevLett.105.095005
- August 20, 2010
- 01:40 PM
- 1,984 views
Cylons and Smelloscopes: False Positives and False Negatives in the Search for Extraterrestrial Life
by The Astronomist in The Astronomist.
Are there planets outside of our solar system? Is there life on other planets? Is life on other planets like life on Earth? These are questions that astronomers, astrobiologists, chemists, and geologists are trying to answer with current experiments. In order to answer these questions we must observe distant planets and we must determine what life on those planets may be like. Detecting extrasolar planets is tricky enough, but imaging what alien life is like may well be stranger than science fic........ Read more »
Beichman, C. A., Woolf, N. J., & Lindensmith, C. A. (1999) The Terrestrial Planet Finder (TPF) : a NASA Origins Program to search for habitable planets. JPL publication. info:/
- July 29, 2010
- 03:51 PM
- 1,697 views
Hubble Bubble
by The Astronomist in The Astronomist.
The Copernican principle holds that humans are not privileged observers of the Universe. Copernicus stated that the Earth is not at the center of the solar system or at any particularly special position in the heavens. Modern cosmology has extended this idea to reason that the earth does not occupy any unique position in the Universe. Modern philosophy of science pushes the principle even further to conclude that every observer (even if they be they little green men) should reason as if they wer........ Read more »
Adam Moss, James P. Zibin, & Douglas Scott. (2010) Precision Cosmology Defeats Void Models for Acceleration. arXiv preprint. arXiv: 1007.3725v1
Conley, A., Carlberg, R., Guy, J., Howell, D., Jha, S., Riess, A., & Sullivan, M. (2007) Is There Evidence for a Hubble Bubble? The Nature of Type Ia Supernova Colors and Dust in External Galaxies. The Astrophysical Journal, 664(1). DOI: 10.1086/520625
- July 11, 2010
- 07:00 PM
- 1,705 views
The Size of the Proton Measured with Lasers
by Alexander in The Astronomist.
A little over a week ago in Lindau, Germany Theordor Hanch hinted at new measurements of the size of the proton which may impact the fundamental theory of quantum electrodynamics. Hansch's lecture was an overview of the history of lasers progressing from our realization of the wave/particle duality nature of light to new research published in Nature on the size of the proton.... Read more »
Pohl R, Antognini A, Nez F, Amaro FD, Biraben F, Cardoso JM, Covita DS, Dax A, Dhawan S, Fernandes LM.... (2010) The size of the proton. Nature, 466(7303), 213-6. PMID: 20613837
- May 5, 2010
- 12:51 AM
- 1,861 views
Dark Matter Confronts Observations
by The Astronomist in The Astronomist.
Dark matter is like the Rome of astronomy, all observations lead to dark matter. The problem is that physicists and astronomers, don't know what it actually is. The observations which support dark matter come from many different independent observations, so it is not just some observational error. The observations which corroborate the dark matter paradigm make for a fantastic discussion, but for right now I would like to focus on explanations for what dark matter may be. Specifically, what kin........ Read more »
Abdo, A., Ackermann, M., Ajello, M., Atwood, W., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Baughman, B., Bechtol, K.... (2010) Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived from First-Year Fermi Large Area Telescope Data. Physical Review Letters, 104(10). DOI: 10.1103/PhysRevLett.104.101101
Nima Arkani-Hamed, Douglas P. Finkbeiner, Tracy R. Slatyer, & Neal Weiner. (2008) A Theory of Dark Matter. Phys.Rev.D79:015014,2009. arXiv: 0810.0713v3
Feng, J., Kaplinghat, M., & Yu, H. (2010) Halo-Shape and Relic-Density Exclusions of Sommerfeld-Enhanced Dark Matter Explanations of Cosmic Ray Excesses. Physical Review Letters, 104(15). DOI: 10.1103/PhysRevLett.104.151301
- March 26, 2010
- 02:50 PM
- 2,346 views
On the Phenomena of Lightning
by Alexander in The Astronomist.
Thunderstorms are epic demonstrations of nature that can be quite fascinating when they aren't terrifying. The study of thunderstorms, in particular lightning, is of obvious practical interest, but also there is also a purely aesthetic and amusing aspect to them.... Read more »
Siingh, D., Singh, A., Patel, R., Singh, R., Singh, R., Veenadhari, B., & Mukherjee, M. (2009) Thunderstorms, Lightning, Sprites and Magnetospheric Whistler-Mode Radio Waves. Surveys in Geophysics, 29(6), 499-551. DOI: 10.1007/s10712-008-9053-z
- February 19, 2010
- 03:47 AM
- 713 views
An Upper Limit On Not Knowing What the F*** They're Doing
by The Astronomist in The Astronomist.
First, I should say that the Supernova Cosmology Group and others using Type Ia supernova as standard candles are very precise in their work and I don't seriously doubt their results as they have been very consistent with other observations. There is though the one dark shadow looming over all their results and that is systematic error. Cosmologists use Type Ia supernova as a lighthouse in the dark because we can assume that all lighthouses have the same intrinsic luminosity and therefore any di........ Read more »
Marat Gilfanov, & Akos Bogdan. (2010) An upper limit on the contribution of accreting white dwarfs to the type Ia supernova rate. Nature, 18 February 2010, Vol.463, p.924. arXiv: 1002.3359v1
- February 19, 2010
- 12:05 AM
- 744 views
An Upper Limit On Not Knowing What the F*** They're Doing
by The Astronomist in The Astronomist.
First, I should say that the Supernova Cosmology Group and others using Type Ia supernova as standard candles are very precise in their work and I don't seriously doubt their results as they have been very consistent with other observations. There is though the one dark shadow looming over all their results and that is systematic error.... Read more »
Marat Gilfanov, & Akos Bogdan. (2010) An upper limit on the contribution of accreting white dwarfs to the type Ia supernova rate. Nature, 18 February 2010, Vol.463, p.924. arXiv: 1002.3359v1
- February 10, 2010
- 11:22 PM
- 1,963 views
The Cosmos isn't strange, people are strange
by The Astronomist in The Astronomist.
The cosmos isn't strange, people are strange. The universe on the largest of scales is actually simple compared to the complexities of the human mind or even the weather. In a statistical sense all current observations indicate that universe is homogeneous and isotropic everywhere. The best evidence for this statement is the cosmic microwave background (CMB) radiation which is light from the big bang that has traveled unimpeded through the universe since recombination. A simp........ Read more »
C. L. Bennett, R. S. Hill, G. Hinshaw, D. Larson, K. M. Smith, J. Dunkley, B. Gold, M. Halpern, N. Jarosik, A. Kogut.... (2010) Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Are There Cosmic Microwave Background Anomalies?. ApJ. arXiv: 1001.4758v1
- February 8, 2010
- 02:42 AM
- 1,690 views
The Cosmological Constant and the Dark Sector
by The Astronomist in The Astronomist.
What is the phenomenology of the dark sector? That is my question. The dark sector refers to dark energy and dark matter, which are two distinct phenomena which seem to have no direct connection other than in name. In this post I am going to talk about the cosmological constant, dark energy, and look at some landmark literature on the subject. I am going to show the origin of the 10120 order of magnitude error that results from the quantum field theory prediction and cosmological observation. I ........ Read more »
Carroll, Sean M., Press, William H., & Turner, Edwin L. (1992) The cosmological constant. ARA, 499-542. info:/
Will J. Percival, Beth A. Reid, Daniel J. Eisenstein, Neta A. Bahcall, Tamas Budavari, Joshua A. Frieman, Masataka Fukugita, James E. Gunn, Zeljko Ivezic, Gillian R. Knapp.... (2009) Baryon Acoustic Oscillations in the Sloan Digital Sky Survey Data Release 7 Galaxy Sample. MNRAS. arXiv: 0907.1660v3
- January 29, 2010
- 04:45 AM
- 1,963 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
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