The Language of Bad Physics

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Dissecting sloppy language usage and logic in papers and theories currently gathering attention in theoretical physics.

S.C. Kavassalis
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  • April 11, 2011
  • 03:08 PM
  • 659 views

What’s been going on in the universe

by S.C. Kavassalis in The Language of Bad Physics

So my readers probably noticed the fact that this blog just stopped mid-February, without any explanation.  Life in our local part of the universe was substantially more chaotic than usual.  World wide protests, devastating natural disasters, nuclear fears, war, and us just trying to go about our day to day lives, buying a home, securing funding, getting sick, planning a wedding, all the while not looking at what was sitting just out of the corner of our eyes.
When the world is in crisis, physics doesn’t stop, science doesn’t stop.  Wars, famine, the need to rebuild – all of these are actually great motivators for researchers.  Unfortunately, most of us aren’t in fields that can actually offer anything close to intellectual assistance during these times.  There is a strange and sad fact about this planet and the animals that inhabit it though, and that is that there is always some part of the world that is in crisis.  If we took a pause every time something unimaginable to us happened, very little would ever get done.  Nevertheless, I paused.
To get back into things, here’s about a months worth of reading – there should be two other posts out later this week (back to some more serious blogging too). Astrophysics and Gravitation gives us some updates on the MOND versus dark matter debate (is MOND winning? or have we already seen dark matter?), a silly paper on stars with wormhole centres, another success for Einstein@Home, a possible explanation for the “Fermi Bubble”, a new value for the Hubble constant, a long overdue fix for the Pioneer Anomaly, and a huge explosion in space for NASA. Lots of news from CERN and Fermilab in High Energy & Particles, including the search for SUSY at the LHC, the hunt for the Higgs, a single top quark at the CMS, heavy antimatter for ALICE, the much hyped results of new physics at the Tevatron, and using a Fermi-Fermi gas to model the Big Bang. Finally in General Relativity & Quantum Gravity we get a lesson on quantum Riemann surfaces in Chern-Simons theory, a curious experiment using gravity waves to suss out dimensionality, an introduction to group field theories, BF models of gravity, and spin foams, an update on the status of Horava gravity, an absurd paper on life inside black holes, and an essay from the 1960s by George Gamow.
Astrophysics and Gravitation:

MOND vs Dark Matter, Again?

MOND is Winning?
Stacy S. McGaugh (2011). A Novel Test of the Modified Newtonian Dynamics with Gas Rich Galaxies Phys.Rev.Lett.106:121303,2011 arXiv: 1102.3913v1
No, it’s not (maybe in the Charlie Sheen sense though).  I’ve honestly never been enchanted with dark matter, the fact that it’s this giant unknown bothers me, and MOND holds a lot of appeal, logically for me, but the fact is, it doesn’t work, in the original form or any current one.  Yes, some observations do fit into MOND predictions – we wouldn’t be talking about it now if it was entirely unphysical – but MOND is also wrong about a lot of things (you know, like the CMB).  Yes, whatever this data was collected on gas rich galaxies probably does fit with what MOND predicts, and may very well disagree with Lambda-CDM (it’s certainly not a perfect model), but if MOND is wrong about other things, it’s still wrong.  If someone comes up with a Modified Modified Newtonian dynamics that explains the CMB and fits with the Bullet Cluster, then we’ll talk.
For more, see Gas Rich Galaxies Confirm Prediction of Modified Gravity Theory (PR), Is this the end of dark matter?, Alternate theory poses dark matter challenge, More Evidence Against Dark Matter?, Dark Matter: Just Fine, Thanks,

Has EDELWEISS Seen Dark Matter?
EDELWEISS Collaboration (2011). Final results of the EDELWEISS-II WIMP search using a 4-kg array of cryogenic germanium detectors with interleaved electrodes arXiv arXiv: 1103.4070v2
No, it hasn’t.  Well, probably not, anyway.  So, the EDELWEISS-II collaboration released some fairly unexciting results, that some people are jumping on as evidence for dark matter. Why? Because the results point to possible evidence for signals for a few WIMP candidates.  The CDMS collaboration last year published similarly tentative claims, though the energies of the EDELWEISS and CDMS candidates are different and thus both cannot be the same WIMP (if they are actually anything at all).  The noise here is very high, so high that it’s not even clear if any of these are signals at all.  People on the project don’t even really believe they’ve seen anything.  The spokesman for EDELWEISS, Gilles Gerbier, said, “We cannot say for sure that there is no signal. We are in the uncomfortable situation… We may have a signal but we cannot make any claim now.”  So, have we seen dark matter? No, it doesn’t sound like it.  It’s not 100% out of the question, however (but probably 99.9% out of it).
For more, see Have Physicists Already Glimpsed Particles of Dark Matter?, Dark matter signal sparks interest, but falls short of discovery.

“Stars Could Have Wormholes at Their Cores”
... Read more »

Stacy S. McGaugh. (2011) A Novel Test of the Modified Newtonian Dynamics with Gas Rich Galaxies. Phys.Rev.Lett.106:121303,2011. arXiv: 1102.3913v1

EDELWEISS Collaboration. (2011) Final results of the EDELWEISS-II WIMP search using a 4-kg array of cryogenic germanium detectors with interleaved electrodes. arXiv. arXiv: 1103.4070v2

V. Dzhunushaliev, V. Folomeev, B. Kleihaus, & J. Kunz. (2011) A Star Harbouring a Wormhole at its Center. arXiv. arXiv: 1102.4454v1

B. Knispel, P. Lazarus, B. Allen, D. Anderson, C. Aulbert, N. D. R. Bhat, O. Bock, S. Bogdanov, A. Brazier, F. Camilo.... (2011) Arecibo PALFA Survey and Einstein@Home: Binary Pulsar Discovery by Volunteer Computing. The Astrophysical Journal Letters, 732, L1 (2011). arXiv: 1102.5340v2

K. S. Cheng, D. O. Chernyshov, V. A. Dogiel, C. -M. Ko, & W. -H. Ip. (2011) Origin of the Fermi Bubble. arXiv. arXiv: 1103.1002v1

Riess, A., Macri, L., Casertano, S., Lampeitl, H., Ferguson, H., Filippenko, A., Jha, S., Li, W., & Chornock, R. (2011) A 3% SOLUTION: DETERMINATION OF THE HUBBLE CONSTANT WITH THE AND WIDE FIELD CAMERA 3 . The Astrophysical Journal, 730(2), 119. DOI: 10.1088/0004-637X/730/2/119  

F. Francisco, O. Bertolami, P. J. S. Gil, & J. Páramos. (2011) Modelling the reflective thermal contribution to the acceleration of the Pioneer spacecraft. arXiv. arXiv: 1103.5222v1

Philip Bechtle, Klaus Desch, Herbi K. Dreiner, Michael Krämer, Ben O'Leary, Carsten Robens, Björn Sarrazin, & Peter Wienemann. (2011) What if the LHC does not find supersymmetry in the sqrt(s). arXiv. arXiv: 1102.4693v1

O. Buchmueller, & et al. (2011) Implications of Initial LHC Searches for Supersymmetry. arXiv. arXiv: 1102.4585v1

ATLAS Collaboration. (2011) Search for Supersymmetry Using Final States with One Lepton, Jets, and Missing Transverse Momentum with the ATLAS Detector in sqrt[s]. Physical Review Letters, 106(13). DOI: 10.1103/PhysRevLett.106.131802  

Dine, M., & Mason, J. (2011) Supersymmetry and its dynamical breaking. Reports on Progress in Physics, 74(5), 56201. DOI: 10.1088/0034-4885/74/5/056201  

CMS Collaboration. (2011) Measurement of WW Production and Search for the Higgs Boson in pp Collisions at sqrt(s) . arXiv. arXiv: 1102.5429v2

CDF Collaboration, & T. Aaltonen. (2011) Invariant Mass Distribution of Jet Pairs Produced in Association with a W boson in ppbar Collisions at sqrt(s) . arXiv. arXiv: 1104.0699v1

Trenkwalder, A., & et al. (2011) Hydrodynamic Expansion of a Strongly Interacting Fermi-Fermi Mixture. Physical Review Letters, 106(11). DOI: 10.1103/PhysRevLett.106.115304  

Tudor Dimofte. (2011) Quantum Riemann Surfaces in Chern-Simons Theory. arXiv. arXiv: 1102.4847v1

Mureika, J., & Stojkovic, D. (2011) Detecting Vanishing Dimensions via Primordial Gravitational Wave Astronomy. Physical Review Letters, 106(10). DOI: 10.1103/PhysRevLett.106.101101  

Patrizia Vitale. (2011) A field-theoretic approach to Spin Foam models in Quantum Gravity. arXiv. arXiv: 1103.4172v1

Matt Visser. (2011) Status of Horava gravity: A personal perspective. arXiv. arXiv: 1103.5587v2

Vyacheslav I. Dokuchaev. (2011) Is there life inside black holes?. arXiv. arXiv: 1103.6140v1

  • February 22, 2011
  • 11:06 AM
  • 913 views

This “Week” in the Universe: February 1st – February 21st

by S.C. Kavassalis in The Language of Bad Physics

So I’ve been remiss in my reading lately, but here are my picks from the past few weeks.  We have Outstanding Problems in Galaxy Formation, Herschel on Dark Matter, Dark Matter Detection Discussed, “Symmetry Breaking” in Graphene?, Closed Timelike Curves and Postselection, Frame-Like Geometry of Double Field Theory, and Loop Lectures with Carlo Rovelli.
Astrophysics and Gravitation:

Outstanding Problems in Galaxy Formation
Joseph Silk (2011). Feedback in Galaxy Formation arXiv arXiv: 1102.0283v1
Abstract:
I review the outstanding problems in galaxy formation theory, and the role of feedback in resolving them. I address the efficiency of star formation, the galactic star formation rate, and the roles of supernovae and supermassive black holes.

Silk’s Figure 1. “The theoretical mass function of galaxies compared to the observed luminosity function.”

So, as most of us know, there are still quite a few puzzles when it comes to how galaxies form.  Joseph Silk has put together a little discussion on some of these problems, and, perhaps more interestingly, ways in which they can be rectified (or already have been). For example, cold dark matter simulations alone predicted more halo dwarf galaxies than were observed (called the “missing satellites” problem; see Kravtsov and pdf slides).  Through both a better understanding of observation (there were in fact more dwarfs out there than we though, they were just very faint) and more sophisticated models (taking into account baryonic physics too), this problem doesn’t seem so huge anymore (it’s not 100% resolved, mind you).  There are many other much less resolved issues when it comes to gravitation and galaxy formation that are also deserving of some serious study.

Herschel on Dark Matter
Alexandre Amblard, & et al. (2011). Sub-millimetre galaxies reside in dark matter halos with masses greater than 3×10^11 solar masses Nature arXiv: 1101.1080v1
From the press release:
ESA’s Herschel space observatory has discovered a population of dust-enshrouded galaxies that do not need as much dark matter as previously thought to collect gas and burst into star formation.
This is certainly good news for some galaxy formation theorists and another fun piece of the puzzle to think about.  The latest analysis of Herschel observations suggest the existence of galaxies that are roughly 300 billion solar masses but with as many stars as expected from a galaxy of 5000 billion solar masses (ie. that’s not got much dark matter in it).  This is quite fascinating, because most of the current theories dealing with galaxy formation require these huge amounts of dark matter to allow budding galaxies to stay together, but now there are observations that suggest otherwise.  It looks like we’ll have to adjust our ideas of dark matter’s role in the galaxy (not that this should surprise anyone).
For more, see Herschel finds less dark matter but more stars.

Dark Matter Detection Discussed
Earlier this month, there was a really excellent guest post at Cosmic Variance about the state of dark matter detection experiments by Neal Weiner (to complete the discussion of dark matter in the galaxy) so you should give that a read.
High Energy Physics and Particles:

“Symmetry Breaking” in Graphene?

San-Jose, P., González, J., & Guinea, F. (2011). Electron-Induced Rippling in Graphene Physical Review Letters, 106 (4) DOI: 10.1103/PhysRevLett.106.045502
So this was a hot topic this month that I’m just getting around to: graphene as an analogy for the Higgs field.  Now, as always with these analogy papers, I get a little nervous.  When there isn’t an explicit (AdS/CFT-esque) correspondence, it’s really very difficult (and a somewhat philosophical matter) to say what we are actually able to learn from analogies. In this case, the analogy comes from the fact that the “energy landscape” of graphene moving in 2-dimensions is similar to that of the Higgs field in 3-dimensions, in that they are both described by a similar Mexican hat potential.  Okay. There are other situations where we see Mexican hat potentials, like when rotating a bead on a circle, but that doesn’t mean that they would be at all useful in thinking about spontaneous symmetry breaking. Since I don’t really know anything relevant about graphene, quantum criticality, or… well, materials in general, I am completely unqualified to to judge this analogy, but it is still an analogy, not a correspondence.  Similar and the same are, importantly, and fundamentally different.
... Read more »

Joseph Silk. (2011) Feedback in Galaxy Formation. arXiv. arXiv: 1102.0283v1

Alexandre Amblard, & et al. (2011) Sub-millimetre galaxies reside in dark matter halos with masses greater than 3x10^11 solar masses. Nature. arXiv: 1101.1080v1

San-Jose, P., González, J., & Guinea, F. (2011) Electron-Induced Rippling in Graphene. Physical Review Letters, 106(4). DOI: 10.1103/PhysRevLett.106.045502  

Lloyd, S., Maccone, L., Garcia-Patron, R., Giovannetti, V., Shikano, Y., Pirandola, S., Rozema, L., Darabi, A., Soudagar, Y., Shalm, L.... (2011) Closed Timelike Curves via Postselection: Theory and Experimental Test of Consistency. Physical Review Letters, 106(4). DOI: 10.1103/PhysRevLett.106.040403  

Hohm, O., & Kwak, S. (2011) Frame-like geometry of double field theory. Journal of Physics A: Mathematical and Theoretical, 44(8), 85404. DOI: 10.1088/1751-8113/44/8/085404  

Carlo Rovelli. (2011) Lectures on loop gravity. arXiv. arXiv: 1102.3660v2

  • January 25, 2011
  • 04:38 PM
  • 821 views

This Week in the Universe: January 18th – January 24th

by S.C. Kavassalis in The Language of Bad Physics

Phenomenally beautiful math was the main highlight of this week, I’d say, although none of it for the very faint of heart.
The CMS on SUSY, Bill Unruh on simulated Hawking radiation, Ed Witten on knots, and Schenkel and Van Oystaeyen on noncommutative space(times):

High Energy Physics and Particles:

The LHC Doesn’t Need Data-Collecting Mode To Have Fun
CMS Collaboration (2011). Search for Supersymmetry in pp Collisions at 7 TeV in Events with Jets and Missing Transverse Energy arXiv arXiv: 1101.1628v1
The CMS Collaboration released results this month ruling out supersymmetric particles with masses of less than ~ 0.5 TeV/c2.  This is just one of a series of ongoing SUSY related papers analyzing last years data and spitting out constraints on models (which is hugely important).  We’ll be seeing results papers for years to come, but it’s nice to see evidence of the LHC being exactly what we all hoped it would be already: the thing that tells us if we’re likely on the right track or not.
For more, see Reality check at the LHC.
General Relativity, Quantum Gravity, et al.:

Measurement of Stimulated Hawking Emission
Silke Weinfurtner, Edmund W. Tedford, Matthew C. J. Penrice, William G. Unruh, & Gregory A. Lawrence (2010). Measurement of stimulated Hawking emission in an analogue system Phys. Rev. Lett., 106 (2), 1302-1306 arXiv: 1008.1911v2
The abstract:
Hawking argued that black holes emit thermal radiation via a quantum spontaneous emission. To address this issue experimentally, we utilize the analogy between the propagation of fields around black holes and surface waves on moving water. By placing a streamlined obstacle into an open channel flow we create a region of high velocity over the obstacle that can include surface wave horizons. Long waves propagating upstream towards this region are blocked and converted into short (deep-water) waves. This is the analogue of the stimulated emission by a white hole (the time inverse of a black hole), and our measurements of the amplitudes of the converted waves demonstrate the thermal nature of the conversion process for this system. Given the close relationship between stimulated and spontaneous emission, our findings attest to the generality of the Hawking process.
Analogues often make me a little uncomfortable in physics, for what are probably obvious reasons, but Bill Unruh has had a lot of success and acceptance with his analogue black hole/white hole models in the past.  The line between similar and the same, and if it is actually telling us anything to observe properties in these analogue systems (which have some major fundamental differences) always gets to me in these matters, so I’m going to have to come back to this one to give further comments.
For more, see Wave-Generated ‘White Hole’ Boosts Hawking Radiation Theory: UBC Research.

Ed Witten on Khovanov Homology of Knots.
Edward Witten (2011). Fivebranes and Knots arXiv arXiv: 1101.3216v1
The abstract:
We develop an approach to Khovanov homology of knots via gauge theory (previous physics-based approches involved other descriptions of the relevant spaces of BPS states). The starting point is a system of D3-branes ending on an NS5-brane with a nonzero theta-angle. On the one hand, this system can be related to a Chern-Simons gauge theory on the boundary of the D3-brane worldvolume; on the other hand, it can be studied by standard techniques of S-duality and T-duality. Combining the two approaches leads to a new and manifestly invariant description of the Jones polynomial of knots, and its generalizations, and to a manifestly invariant description of Khovanov homology, in terms of certain elliptic partial differential equations in four and five dimensions.
So Ed Witten is one of those few authors whose work I can feel safe about getting excited over before I’ve read it, and at 146 pages, well, it’s unlikely I’ll ever make it through all of this (although its length is only due to the fact that it very thorough, and thus imaginably very useful).  I’m going to defer to the University of Toronto’s Daniel Moskovich from Low Dimensional Topology (which I can’t recommend enough) on this one, as he wrote:... Read more »

CMS Collaboration. (2011) Search for Supersymmetry in pp Collisions at 7 TeV in Events with Jets and Missing Transverse Energy. arXiv. arXiv: 1101.1628v1

Silke Weinfurtner, Edmund W. Tedford, Matthew C. J. Penrice, William G. Unruh, & Gregory A. Lawrence. (2010) Measurement of stimulated Hawking emission in an analogue system. Phys. Rev. Lett., 106(2), 1302-1306. arXiv: 1008.1911v2

Edward Witten. (2011) Fivebranes and Knots. arXiv. arXiv: 1101.3216v1

Alexander Schenkel. (2011) Quantum Field Theory on Curved Noncommutative Spacetimes. arXiv. arXiv: 1101.3492v2

  • January 20, 2011
  • 03:22 PM
  • 519 views

Finite formula found for partition numbers

by S.C. Kavassalis in The Language of Bad Physics

Credit: Emory and Ken Ono
So this isn’t physics*, but if you squint hard enough, you can probably make a connection.  The hot topic today is Ken Ono‘s latest work on the partition function:
Ken Ono, Amanda Folsom, & Zach Kent (2011). l-adic properties of the partition function American Institute of Mathematics.
Ken Ono & Jan Bruinier (2011). AN ALGEBRAIC FORMULA FOR THE PARTITION FUNCTION American Institute of Mathematics.
A EurekAlert press release appeared today, entitled: New math theories reveal the nature of numbers and people are already whispering “Fields Medal”. Now, I haven’t thoroughly read the paper yet, but, since I’m not a number theorist, my commentary probably won’t change very much anyway.  Obviously, like most press releases, this one is full of hyperbole and ridiculous sentences like, “the team was determined go beyond mere theories”, but the actual work being discussed is fascinating.
Now, when we talk about a partition function in the context of Ono’s work, we don’t mean the partition function that is familiar to most physicists, we mean what number theorists call a partition function.
In this setting, a partition is a way of representing a natural number as the sum of natural numbers (ie. for , we have three partitions, , , and , independent of order).  Thus, the partition function, , represents the number of possible partitions of .  So, , (for , we have: , , , ,  ) , etc..
To be slightly more technical, from Ken Ono and Kathrin Bringman [1],
A partition of a non-negative integer n is a non-increasing sequence of positive integers whose sum is .
The concept is straight forward, but how to obtain these partition numbers, in general, is actually no trivial matter.
The master of series, Leonhard Euler, worked on solving this problem, to less than fully satisfying results.  Using the reciprocal of what is now called Euler’s function, we get the generator for by this infinite product,
.
Here, counts the number of ways to write, , for , where each number appears times.
Obviously, for large , this can be unwieldy, and it doesn’t lead to an explicit formula, but as long as you didn’t need more than 200~ partition numbers, it was okay.
Mathematics had to wait until the early 1900s before anyone was to expand on Euler’s partition number generator, when Srinivasa Ramanujan made contact with G.H. Hardy.  Ken Ono actually has a beautiful historical, and mathematical, account of the Ramanujan and Hardy story, called “The Last Words of a Genius” [pdf].
Ramanujan famously proved an unusual and surprising result that [2],

,
,
.

He was also responsible for the first attempt at an explicit, although not exact, formula for with Hardy,
as .
... Read more »

Ken Ono, Amanda Folsom, & Zach Kent. (2011) l-adic properties of the partition function. American Institute of Mathematics. info:/

Folsom A, & Ono K. (2008) The spt-function of Andrews. Proceedings of the National Academy of Sciences of the United States of America, 105(51), 20152-6. PMID: 19091951  

  • January 18, 2011
  • 10:09 AM
  • 1,071 views

This Week in the Universe: January 11th – January 17th

by S.C. Kavassalis in The Language of Bad Physics

Astrophysics and Gravitation:
Planck’s Early Results
Planck Collaboration (2011). Planck Early Results: The Planck mission arXiv arXiv: 1101.2022v1
The Early Results Papers from the Planck Collaboration are based on the data acquired by the Planck satellite between August 13th, 2009 to June 6th, 2010.  This work is “an overview of the history of Planck in its first year of operations” and was released along side Planck’s Early Release Compact Source Catalogue, “the first data product based on Planck to be released publicly”.  Andrew Jaffe has a great summary of the results so far.
For more, see Planck: First results.

Dark Galaxies?
Sukanya Chakrabarti, Frank Bigiel, Philip Chang, & Leo Blitz (2011). Finding Dark Galaxies From Their Tidal Imprints arXiv arXiv: 1101.0815v1
From the abstract:
We describe ongoing work on a new method that allows one to determine the mass and relative position (in galactocentric radius and azimuth) of galactic companions purely from analysis of observed disturbances in gas disks….This approach has broad implications for many areas of astrophysics — for the indirect detection of dark matter (or dark-matter dominated dwarf galaxies), and for galaxy evolution in its use as a decipher for the dynamical impact of satellites on galactic disks. Here, we provide a proof of principle of the method by applying it to infer and quantitatively characterize optically visible galactic companions of local spirals, from the analysis of observed disturbances in outer gas disks.”
The tl;dr version is that they have a technique for detecting companion galaxies that need not be optically visible (which is great, because sometimes we can’t see things for reasons other than them being made out of dark matter) and this paper acts as a proof of concept by using it to correctly infer and characterize galaxies that we already can observe.  Does it say anything about having detected a dark matter galaxy? No.  If such things existed it could be used to detect them (if they were acting as companion to regular matter galaxies), but it doesn’t say anything about their existence.  I genuinely feel I read a different paper than the authors who wrote the below two articles.
For more, see Dark-Matter Galaxy Detected: Hidden Dwarf Lurks Nearby?, The Milky Way might be surrounded by invisible dark matter galaxies.
Not So Standard Standard Candle
This image layout illustrates how NASA's Spitzer Space Telescope was able to show that a "standard candle" used to measure cosmological distances is shrinking -- a finding that affects precise measurements of the age, size and expansion rate of our universe. Image credit: NASA/JPL-Caltech/Iowa State
From the NASA press release:
Astronomers have turned up the first direct proof that “standard candles” used to illuminate the size of the universe, termed Cepheids, shrink in mass, making them not quite as standard as once thought. The findings, made with NASA’s Spitzer Space Telescope, will help astronomers make even more precise measurements of the size, age and expansion rate of our universe.
Obviously, this is rather significant, but the immediate consequence of standard candles not being standard isn’t that it will allow for accurate future measurements of things, it’s that it calls into question the current measurements we have (for things like galactic distances).
From lead author of the study, Massimo Marengo*:
When using Cepheids as standard candles, we must be extra careful because, much like actual candles, they are consumed as they burn.
*He’s also an author on a wonderfully titled paper, Close Binaries with Infrared Excess: Destroyers of Worlds?.
For more, see Cosmology Standard Candle not so Standard After All.
Dynamical Coupled Dark Energy?

Baldi, M., & Pettorino, V. (2011). High-z massive clusters as a test for dynamical coupled dark energy Monthly Notices of the Royal Astronomical Society: Letters DOI: 10.1111/j.1745-3933.2010.00975.x
Abstract:
The recent detection by Jee et al. of the massive cluster XMMU J2235.3−2557 at a redshift z≈ 1.4, with an estimated mass M324= (6.4 ± 1.2) × 1014 M⊙, has been claimed to be a possible challenge to the standard ΛCDM cosmological model. More specifically, the probability to detect such a cluster has been estimated to be ∼0.005 if a ΛCDM model with Gaussian initial conditions is assumed, resulting in a 3σ discrepancy from the standard cosmological model. In this Letter we propose to use high-redshift clusters as the one detected in Jee et al. to compare the cosmological constant scenario with interacting dark energy models. We show that coupled dark energy models, where an interaction is present between dark energy and cold dark matter, can significantly enhance the probability to observe very massive clusters at high redshift.
So I actually haven’t read this paper yet, but was told by a cosmologist frien... Read more »

Planck Collaboration. (2011) Planck Early Results: The Planck mission. arXiv. arXiv: 1101.2022v1

Sukanya Chakrabarti, Frank Bigiel, Philip Chang, & Leo Blitz. (2011) Finding Dark Galaxies From Their Tidal Imprints. arXiv. arXiv: 1101.0815v1

Baldi, M., & Pettorino, V. (2011) High-z massive clusters as a test for dynamical coupled dark energy. Monthly Notices of the Royal Astronomical Society: Letters. DOI: 10.1111/j.1745-3933.2010.00975.x  

Turok, N. (2011) Particle physics: Beyond Feynman's diagrams. Nature, 469(7329), 165-166. DOI: 10.1038/469165a  

  • January 10, 2011
  • 01:23 PM
  • 936 views

This Week in the Universe: January 4th – January 10th

by S.C. Kavassalis in The Language of Bad Physics

Astrophysics and Gravitation:
Supermassive Black Hole Surprise?
CREDIT: Reines, et al., David Nidever, NRAO/AUI/NSF, NASA
The dwarf galaxy Henize 2-10, seen in visible light by the Hubble Space Telescope. The central, light-pink region shows an area of radio emission, seen with the Very Large Array. This area indicates the presence of a supermassive black hole drawing in material from its surroundings. This also is indicated by strong X-ray emission from this region detected by the Chandra X-Ray Observatory.
Astronomers have identified a supermassive black hole candidate at the centre of the dwarf galaxy Henize 2-10.  Amy Reines, one of the members of the discovery team, on why this is important:
This galaxy gives us important clues about a very early phase of galaxy evolution that has not been observed before.
For more, see Surprise: Dwarf Galaxy Harbors Supermassive Black Hole.
High Energy Physics and Particles:
Good-Bye to the Tevatron?
Obviously the big news of today is the rumour that the Tevatron will cease operations at the end of 2011.  We’re still waiting on the official announcement though.
New in Nuclear Fission
Andreyev, A., et al., (2010). New Type of Asymmetric Fission in Proton-Rich Nuclei Physical Review Letters, 105 (25) DOI: 10.1103/PhysRevLett.105.252502
An exotic fission process is studied and an exciting and anomalous asymmetry in the daughter masses is discussed.
As Abhishek Agarwal writes:
The ISOLDE team’s puzzling result hints that a very subtle interplay between macroscopic and microscopic interactions plays a deeper role in the fission process than expected and is likely to inspire detailed theoretical studies and further experiment.
Neat.
For more, see Unequal Parts.

General Relativity, Quantum Gravity, et al.:
Projective flatness in the quantisation of bosons and fermions
Siye Wu (2010). Projective flatness in the quantisation of bosons and fermions arXiv arXiv: 1008.5333v2
The abstract:
We compare the quantisation of linear systems of bosons and fermions. We recall the appearance of projectively flat connection and results on parallel transport in the quantisation of bosons. We then discuss pre-quantisation and quantisation of fermions using the calculus of fermionic variables. We then define a natural connection on the bundle of Hilbert spaces and show that it is projectively flat. This identifies, up to a phase, equivalent spinor representations constructed by various polarisations. We introduce the concept of metaplectic correction for fermions and show that the bundle of corrected Hilbert spaces is naturally flat. We then show that the parallel transport in the bundle of Hilbert spaces along a geodesic is the rescaled projection or the Bogoliubov transformation provided that the geodesic lies within the complement of a cut locus. Finally, we study the bundle of Hilbert spaces when there is a symmetry.
So I’m a sucker for nice math, and this paper has got that in spades.  If you want some beautiful geometry, and some quantum mechanics (which together, I firmly believe are critical to good quantum gravity), then this is well worth the read.
... Read more »

Andreyev, A., Elseviers, J., Huyse, M., Van Duppen, P., Antalic, S., Barzakh, A., Bree, N., Cocolios, T., Comas, V., Diriken, J.... (2010) New Type of Asymmetric Fission in Proton-Rich Nuclei. Physical Review Letters, 105(25). DOI: 10.1103/PhysRevLett.105.252502  

Siye Wu. (2010) Projective flatness in the quantisation of bosons and fermions. arXiv. arXiv: 1008.5333v2

  • December 26, 2010
  • 09:25 PM
  • 778 views

This Week in the Universe: December 20th – December 27th

by S.C. Kavassalis in The Language of Bad Physics

Since I’m in the Rockies soaking up my last few days of vacation, I haven’t actually looked at much this week, but there were two papers I thought were worth noting.
Astrophysics and Gravitation:
Reconstructing Histories with Good Statistics
Tracy Holsclaw, Ujjaini Alam, Bruno Sanso, Herbert Lee, Katrin Heitmann, Salman Habib, & David Higdon (2010). Nonparametric Dark Energy Reconstruction from Supernova Data Phys. Rev. Lett. arXiv: 1011.3079v1
The abstract:
Understanding the origin of the accelerated expansion of the Universe poses one of the greatest challenges in physics today. Lacking a compelling fundamental theory to test, observational efforts are targeted at a better characterization of the underlying cause. If a new form of mass-energy, dark energy, is driving the acceleration, the redshift evolution of the equation of state parameter w(z) will hold essential clues as to its origin. To best exploit data from observations it is necessary to develop a robust and accurate reconstruction approach, with controlled errors, for w(z). We introduce a new, nonparametric method for solving the associated statistical inverse problem based on Gaussian process modeling and Markov chain Monte Carlo sampling. Applying this method to recent supernova measurements, we reconstruct the continuous history of w out to redshift z=1.5.
As the paper says, “In order to extract useful information from cosmological data, a reliable and robust reconstruction method for w(z) [the equation of state parameter] is crucial”, and that’s what this paper aims to provide.  It’s not the most exciting thing you’ll ever read (although it is short), but without work along these lines, much of cosmology and astrophysics is actually pretty meaningless, so it’s certainly worth remembering that.
For more, see Statistical modeling could help us understand cosmic acceleration.
General Relativity, Quantum Gravity, et al.:
Brane Holes
Valeri P. Frolov, & Shinji Mukohyama (2010). Brane Holes arXiv arXiv: 1012.4541v1
The abstract:
The aim of this paper is to demonstrate that in models with large extra dimensions under special conditions one can extract information from the interior of 4D black holes. For this purpose we study an induced geometry on a test brane in the background of a higher dimensional static black string or a black brane. We show that at the intersection surface of the test brane and the bulk black string/brane the induced metric has an event horizon, so that the test brane contains a black hole. We call it a brane hole. … We discuss thermodynamic properties of brane holes and interesting questions which arise when such an extra dimensional channel for the information mining exists.
Who doesn’t love higher dimensional solutions for black holes?  Honestly, I haven’t had time to give this a thorough read yet but it looks rather promising.
For more, see Cosmologists Discover How Black Holes Can Leak.
... Read more »

Tracy Holsclaw, Ujjaini Alam, Bruno Sanso, Herbert Lee, Katrin Heitmann, Salman Habib, & David Higdon. (2010) Nonparametric Dark Energy Reconstruction from Supernova Data. Phys. Rev. Lett. arXiv: 1011.3079v1

Valeri P. Frolov, & Shinji Mukohyama. (2010) Brane Holes. arXiv. arXiv: 1012.4541v1

  • December 20, 2010
  • 12:59 PM
  • 733 views

This Week in the Universe: December 14th – December 20th

by S.C. Kavassalis in The Language of Bad Physics

This will be an especially short one, as I’m sitting in a hotel room in Idaho right now and didn’t pre-write anything, but check out 10 Delicious Papers from 2010 for more fun!
Astrophysics and Gravitation:
Hints of a Multiverse?
Stephen M. Feeney, Matthew C. Johnson, Daniel J. Mortlock, & Hiranya V. Peiris (2010). First Observational Tests of Eternal Inflation arXiv DOI: 1012.1995


The abstract:
The eternal inflation scenario predicts that our observable universe resides inside a single bubble embedded in a vast multiverse, the majority of which is still undergoing super-accelerated expansion. Many of the theories giving rise to eternal inflation predict that we have causal access to collisions with other bubble universes, opening up the possibility that observational cosmology can probe the dynamics of eternal inflation. We present the first observational search for the effects of bubble collisions, using cosmic microwave background data from the WMAP satellite. Using a modular algorithm that is designed to avoid a posteriori selection effects, we find four features on the CMB sky that are consistent with being bubble collisions. If this evidence is corroborated by upcoming data from the Planck satellite, we will be able to gain insight into the possible existence of the multiverse.
Interesting, but far from conclusive, evidence has been found suggesting the possible existence of the multiverse.  Of course, these observations could also happen if there was no multiverse, but they allow for the possibility of its existence.  Further study will say more one way or the other (although it’s likely to never be conclusive).
For more, see Cosmic Radiation Features Could Suggest Our Universe Is Not Alone.
High Energy Physics and Particles:
No Mini Black Holes at the LHC, No One is Surprised
CMS Collaboration (2010). Search for Microscopic Black Hole Signatures at the Large Hadron Collider arXiv arXiv: 1012.3375v1
So no micoscopic black holes have been produced or detected at the LHC.  This is not surprising; it’s almost not even news.  Outside of the tabloids, I don’t think very many people thought there was any chance of it happening, as very few versions of quantum gravity would allow for black hole production at these, relatively low, energy levels.  However, ruling things out is always important (but it isn’t this grand failure of string theory as some people are claiming).
For more, see Search for microscopic black hole signatures at the Large Hadron Collider, LHC confirms a modest stringy prediction on black holes, Missing Black Holes Cause Trouble for String Theory, String Theory Fails Another Test, the “Supertest”.
General Relativity, Quantum Gravity, et al.:
Something Loopy This Way Comes?
Marcin Domagala, Kristina Giesel, & Wojciech Kaminski, Jerzy Lewandowski (2010). Gravity quantized arXiv DOI: 1009.2445
So I’m honestly not sure why this one is here, but io9 did a write up that seems to have a lot of people talking.  Okay, so I haven’t read more than the abstract (I’m supposed to be on vacation!), but the abstract was fairly lackluster.
Here is the abstract in its entirety:
…”but we do not have quantum gravity.” This phrase is often used when analysis of a physical problem enters the regime in which quantum gravity effects should be taken into account. In fact, there are several models of the gravitational field coupled to (scalar) fields for which the quantization procedure can be completed using loop quantum gravity techniques. The model we present in this paper consist of the gravitational field coupled to a scalar field. The result has similar structure to the loop quantum cosmology models, except for that it involves all the local degrees of freedom because no symmetry reduction has been performed at the classical level.
You guys can tell me if it’s worth reading when I’m back.
For more, see Loop quantum gravity could unite physics and take us back to the Big Bang.
Say Good-Bye to the Pioneer Anomaly
Slava G. Turyshev, & Viktor T. Toth (2010). The Pioneer Anomaly arXiv DOI: 1001.3686
This is actually great (although far too long to read unless you’re especially interested).  I’ll direct you to the wonderful summaries below, but basically, the Pioneer anomaly, an anomaly some people suggest indicates problems with general relativity, is probably not an anomaly at all.

... Read more »

Stephen M. Feeney, Matthew C. Johnson, Daniel J. Mortlock, & Hiranya V. Peiris. (2010) First Observational Tests of Eternal Inflation. arXiv. DOI: 1012.1995  

CMS Collaboration. (2010) Search for Microscopic Black Hole Signatures at the Large Hadron Collider. arXiv. arXiv: 1012.3375v1

Marcin Domagala,, Kristina Giesel,, & Wojciech Kaminski, Jerzy Lewandowski. (2010) Gravity quantized. arXiv. DOI: 1009.2445  

Slava G. Turyshev, & Viktor T. Toth. (2010) The Pioneer Anomaly. arXiv. DOI: 1001.3686  

  • December 13, 2010
  • 11:14 AM
  • 901 views

This “Week” in the Universe: November 30th – December 13th

by S.C. Kavassalis in The Language of Bad Physics

Astrophysics and Gravitation:
The Milky Way Project
The Milky Way Project aims to sort and measure our galaxy, the Milky Way. Initially we’re asking you to help us find and draw bubbles in beautiful infrared data from the Spitzer Space Telescope.
Understanding the cold, dusty material that we see in these images, helps scientists to learn how stars form and how our galaxy changes and evolves with time.
The GalaxyZoo project expands! Help astronomers out when you’re feeling in the mood to procrastinate.

GREAT10 Image Analysis Competitions for Cosmological Lensing
GREAT10, a simulation challenge that aims to improve image analysis algorithms for cosmic gravitational lensing.
GREAT10 is a way for astronomers, astrophysicists, computer vision, and AI people to come together and find new ways of solving problems.  Contest details are online.
For more, see Computer Geeks: Compete to Help NASA Explain Dark Energy.
High Energy Physics and Particles:
2010 Ion Run Complete at CERN
From CERN Bulletin:
After a very fast switchover from protons to lead ions, the LHC has achieved performances that allowed the machine to exceed both peak and integrated luminosity by a factor of three. Thanks to this, experiments have been able to produce high-profile results on ion physics almost immediately, confirming that the LHC was able to keep its promises for ions as well as for protons.
Another milestone finished; it’s been a great year for the LHC.
For more, see CERN Bulletin.
General Relativity, Quantum Gravity, et al.:
GravityGeek for Christmas
GravityGeek is a cooperative project to help encourage interaction amongst physicists in gravitation/general relativity with journalists and the public.
GravityGeek, the beta collaboration/networking site for professionals in general relativity, quantum gravity, cosmology, etc., has recommendations for Christmas/other gift giving, in case you have a physicist to buy for (as well as non-technical recommendations for kids and those who just like good popular science literature).
For more, see The GravityGeek Mission.
Fun with 2D Blackholes
Abhay Ashtekar, Frans Pretorius, & Fethi M. Ramazanoğlu (2010). Surprises in the Evaporation of 2-Dimensional Black Holes arXiv arXiv: 1011.6442v1
The abstract:
Quantum evaporation of Callen-Giddings-Harvey-Strominger (CGHS) black holes is analyzed in the mean field approximation. The resulting semi-classical theory incorporates back reaction. Detailed analytical and numerical calculations show that, while some of the assumptions underlying the standard evaporation paradigm are borne out, several are not. Furthermore, if the black hole is initially macroscopic, the evaporation process exhibits remarkable universal properties. Although the literature on CGHS black holes is quite rich, these features had escaped previous analyses, in part because of lack of required numerical precision, and in part because certain properties and symmetries of the model were not recognized. Finally, our results provide support for the full quantum scenario recently developed by Ashtekar, Taveras and Varadarajan.
This is fairly nice for something so dense to read (it’s a lot crammed into four pages).  The key result: for 2D black holes, information in the matter profile on Ī⁻R will not all be recovered at Ī⁺R, in generality.  Slight twists on our understanding of 2D black holes might be suggestive of solutions in 4D.  Of course, the usual problems of discussing anything in 2D are still there, but still…
Cyclic Circles in the Sky? Probably Not
The big topic of the past few weeks has been Roger Penrose and V.G. Gurzadyan’s November paper, suggesting there was evidence, via circle matching in the CMB, of a cyclic cosmology.  There are so many papers being discussed right now, that this requires it’s own section.  Now, because Penrose being a co-author makes any paper big news, mainstream media was all over this “evidence for time before time” (and other completely offensive and nonsensical catchphrases).  What Gurzadyan and Penrose believed they had shown was that patterns in the CMB could not fit with standard inflationary cosmology and were strongly suggestive of a cyclic cosmology – ie. multiple “big bangs” (so our big bang wasn’t the first/didn’t start the cosmic clock, so to speak).  Now, many people who’ve looked for circles in the CMB (because it could be very suggestive of the topology/geometry/history of the universe) were sceptical of this, because, unfortunately, patterns in the CMB are a little like bible codes.  If you’re just looking for something, with a data set that big, you’re bound to find it and it doesn’t make it at all meaningful.  Doubters appeared quickly on the arXiv and in blogs, and Gurzadyan and Penrose quickly responded in kind (see NASA, this is how it’s supposed to work).  Below are the papers in the discussion as it stands, from November 16th to today:
The Original Paper
V. G. Gurzadyan, & R. Penrose (2010). Concentric circles in WMAP data may provide evidence of violent pre-Big-Bang activity arXiv arXiv: 1011.3706v1
Critique #1 by Wehus & Eriksen
I. K. Wehus, & H. K. Eriksen (2010). A search for concentric circles in the 7-year WMAP temperature sky maps arXiv arXiv: 1012.1268v1
Critique #2 by Moss, Scott & Ziblin
Adam Moss, Douglas Scott, & James P. Zibin (2010). No evidence for anomalously low variance circles on the sky ... Read more »

Abhay Ashtekar, Frans Pretorius, & Fethi M. Ramazanoğlu. (2010) Surprises in the Evaporation of 2-Dimensional Black Holes. arXiv. arXiv: 1011.6442v1

V. G. Gurzadyan, & R. Penrose. (2010) Concentric circles in WMAP data may provide evidence of violent pre-Big-Bang activity. arXiv. arXiv: 1011.3706v1

I. K. Wehus, & H. K. Eriksen. (2010) A search for concentric circles in the 7-year WMAP temperature sky maps. arXiv. arXiv: 1012.1268v1

Adam Moss, Douglas Scott, & James P. Zibin. (2010) No evidence for anomalously low variance circles on the sky. arXiv. arXiv: 1012.1305v1

V. G. Gurzadyan, & R. Penrose. (2010) More on the low variance circles in CMB sky. arXiv. arXiv: 1012.1486v1

  • November 29, 2010
  • 08:25 PM
  • 1,773 views

This Week in the Universe: November 23rd – November 29th

by S.C. Kavassalis in The Language of Bad Physics

Astrophysics and Gravitation:
Lensing of Black Holes Can Determine the Metric Around Them?
Bin-Nun, A. (2010). Gravitational lensing of stars orbiting Sgr A* as a probe of the black hole metric in the Galactic center Physical Review D, 82 (6) DOI: 10.1103/PhysRevD.82.064009
From the abstract:
We show that a possible astrophysical experiment, detection of lensed images of stars orbiting close to Sgr A*, can provide insight into the form of the metric around a black hole. We model Sgr A* as a black hole and add in a 1/r2 term to the Schwarzschild metric near the black hole. … This knowledge will be useful in constraining any modified gravity theory that adds a similar term into the strong field near a black hole.
Sounds too good to be true?  It’s hard to say, but a technique to observationally determine the spacetime metric would be awfully exciting (and huge – to classical/quantum relativists, that is).
For more, see Black Hole May Offer Clues to Extra Dimensions.
Dark Energy and the Geometry of the Universe
Marinoni, C., & Buzzi, A. (2010). A geometric measure of dark energy with pairs of galaxies Nature, 468 (7323), 539-541 DOI: 10.1038/nature09577
From the abstract:
There is a purely geometric test of the expansion of the Universe (the Alcock–Paczynski test), which would provide an independent way of investigating the abundance () and equation of state () of dark energy. … Here we report an analysis of the symmetry properties of distant pairs of galaxies from archival data. This allows us to determine that the Universe is flat…
Speaking of observing metrics… this is a lot less exciting, however, as it takes in many more assumptions about the basic nature of the universe, galaxy distances, and, of course, dark energy.
For more, see Distant Galaxies Confirm Dark Energy’s Existence and Universe’s Flatness, Dark Energy Theory Gets a Boost From New Galactic Measurements, Cosmology: Geometry of the Universe.
Unified Origin of Matter and Dark Matter?
Davoudiasl, H., Morrissey, D., Sigurdson, K., & Tulin, S. (2010). Unified Origin for Baryonic Visible Matter and Antibaryonic Dark Matter Physical Review Letters, 105 (21) DOI: 10.1103/PhysRevLett.105.211304
The abstract:
We present a novel mechanism for generating both the baryon and dark matter densities of the Universe. A new Dirac fermion X carrying a conserved baryon number charge couples to the standard model quarks as well as a GeV-scale hidden sector. CP-violating decays of X, produced nonthermally in low-temperature reheating, sequester antibaryon number in the hidden sector, thereby leaving a baryon excess in the visible sector. The antibaryonic hidden states are stable dark matter. A spectacular signature of this mechanism is the baryon-destroying inelastic scattering of dark matter that can annihilate baryons at appreciable rates relevant for nucleon decay searches.
This is a surprisingly practical one (and really should be classified as high energy): A UBC team has proposed a new fermion that could explain dark matter, while linking to regular matter and the Standard Model.  Signatures related to this fermion X should be detectable, in the right experiment, making it a target for future searches.
For more, see The X factor, UBC physicists make atoms and dark matter add up.
Accurate Measurement in the Field of the Earth of the General-Relativistic Precession
Lucchesi, D., & Peron, R. (2010). Accurate Measurement in the Field of the Earth of the General-Relativistic Precession of the LAGEOS II Pericenter and New Constraints on Non-Newtonian Gravity Physical Review Letters, 105 (23) DOI: 10.1103/PhysRevLett.105.231103
From the abstract:
The pericenter shift of a binary system represents a suitable observable to test for possible deviations from the Newtonian inverse-square law in favor of new weak interactions between macroscopic objects. We analyzed 13 years of tracking data of the LAGEOS satellites with GEODYN II software but with no models for general relativity. From the fit of LAGEOS II pericenter residuals we have been able to obtain a 99.8% agreement with the predictions of Einstein’s theory
It’s always nice to see confirmations of general relativity, especially when they help put limits on poss... Read more »

Bin-Nun, A. (2010) Gravitational lensing of stars orbiting Sgr A* as a probe of the black hole metric in the Galactic center. Physical Review D, 82(6). DOI: 10.1103/PhysRevD.82.064009  

Marinoni, C., & Buzzi, A. (2010) A geometric measure of dark energy with pairs of galaxies. Nature, 468(7323), 539-541. DOI: 10.1038/nature09577  

Davoudiasl, H., Morrissey, D., Sigurdson, K., & Tulin, S. (2010) Unified Origin for Baryonic Visible Matter and Antibaryonic Dark Matter. Physical Review Letters, 105(21). DOI: 10.1103/PhysRevLett.105.211304  

Lucchesi, D., & Peron, R. (2010) Accurate Measurement in the Field of the Earth of the General-Relativistic Precession of the LAGEOS II Pericenter and New Constraints on Non-Newtonian Gravity. Physical Review Letters, 105(23). DOI: 10.1103/PhysRevLett.105.231103  

Eugenio Bianchi. (2010) Black Hole Entropy, Loop Gravity, and Polymer Physics. arXiv. arXiv: 1011.5628v1

  • November 24, 2010
  • 10:56 AM
  • 1,190 views

This “Week” in the Universe: November 9th – November 22nd

by S.C. Kavassalis in The Language of Bad Physics

Astrophysics and Gravitation:
Fundamental constants: Big G revisited
Davis, R. (2010). Fundamental constants: Big G revisited Nature, 468 (7321), 181-183 DOI: 10.1038/468181b

Credit: Nature. a, A spherical 'source mass' (ms) is brought near a pendulum's spherical bob (the 'test mass', mt) and causes the bob to move a small distance z from its usual resting position (grey). The gravitational force between the two masses (left side of equation), which depends on Newton's constant (G), can be obtained from a measurement of z provided that k is known (see b). b, The value of k is found by measuring the period (P) of the freely swinging pendulum. To compute the value of G, we need measurements of L, z, ms and P (but not mt). Parks and Faller's experiment was based on four cylindrical source masses of 100 kilograms each, two pendulums and many other refinements.
From the abstract:
Measuring Newton’s constant of gravitation is a difficult task, because gravity is the weakest of all the fundamental forces. An experiment involving two simple pendulums provides a seemingly accurate but surprising value.

For more, see Fundamental constants: Big G revisted.
Galaxy Zoo Supernovae
Galaxy Zoo (2010). Galaxy Zoo Supernovae arXiv arXiv: 1011.2199v2
This paper presents the first results from a new citizen science project: Galaxy Zoo Supernovae which, with 2500 volunteers, has categorized almost 14,000 supernovae candidates.
For more, see Galaxy Zoo paper goes supernova.
“Youngest” Nearby Black Hole
Credits: X-ray: NASA/CXC/SAO/D.Patnaude et al, Optical: ESO/VLT, Infrared: NASA/JPL/Caltech
From the Press Release:
This composite image shows a supernova within the galaxy M100 that may contain the youngest known black hole in our cosmic neighborhood. In this image, Chandra’s X-rays are colored gold, while optical data from ESO’s Very Large Telescope are shown in red, green, and blue, and infrared data from Spitzer are red. The location of the supernova, known as SN 1979C, is labeled… This approximately 30-year age, plus its relatively close distance, makes SN 1979C the nearest example where the birth of a black hole has been observed, if the interpretation by the scientists is correct.
Sure, black holes can have finite age, that seems perfectly reasonable… well no, not really.  The “age” of a black hole is an exceptionally complicated, verging on philosophical, matter that I’ll have to write about.
For more, see Black Hole Baby Spotted Being Born, Youngest nearby black hole found, Youngest Nearby Black Hole.
High Energy Physics and Particles:
Trapped Antihydrogen
Andresen, G., & et al. (2010). Trapped antihydrogen Nature DOI: 10.1038/nature09610
From the abstract:
Antihydrogen, the bound state of an antiproton and a positron, has been produced2, 3 at low energies at CERN (the European Organization for Nuclear Research) since 2002. Antihydrogen is of interest for use in a precision test of nature’s fundamental symmetries. … Here we demonstrate trapping of antihydrogen atoms. …This result opens the door to precision measurements on anti-atoms, which can soon be subjected to the same techniques as developed for hydrogen.
For more, see Antiatoms Bottled for First Time, Antimatter atoms held captive by physicists.
General Relativity, Quantum Gravity, et al.:
Pre-Big-Bang Penrose
V. G. Gurzadyan, & R. Penrose (2010). Concentric circles in WMAP data may provide evidence of violent pre-Big-Bang activity arXiv arXiv: ... Read more »

Davis, R. (2010) Fundamental constants: Big G revisited. Nature, 468(7321), 181-183. DOI: 10.1038/468181b  

Galaxy Zoo. (2010) Galaxy Zoo Supernovae. arXiv. arXiv: 1011.2199v2

Andresen, G., & et al. (2010) Trapped antihydrogen. Nature. DOI: 10.1038/nature09610  

V. G. Gurzadyan, & R. Penrose. (2010) Concentric circles in WMAP data may provide evidence of violent pre-Big-Bang activity. arXiv. arXiv: 1011.3706v1

Belgiorno, F., Cacciatori, S., Clerici, M., Gorini, V., Ortenzi, G., Rizzi, L., Rubino, E., Sala, V., & Faccio, D. (2010) Hawking Radiation from Ultrashort Laser Pulse Filaments. Physical Review Letters, 105(20). DOI: 10.1103/PhysRevLett.105.203901  

Alberto S. Cattaneo, & Florian Schaetz. (2010) Introduction to supergeometry. arXiv. arXiv: 1011.3401v1

Benjamin Bahr, Bianca Dittrich, & Song He. (2010) Coarse graining theories with gauge symmetries. arXiv. arXiv: 1011.3667v1

Veronika E. Hubeny. (2010) The Fluid/Gravity Correspondence: a new perspective on the Membrane Paradigm. arXiv. arXiv: 1011.4948v1

  • November 10, 2010
  • 10:30 AM
  • 1,105 views

This Week in the Universe: November 2nd – November 8th

by S.C. Kavassalis in The Language of Bad Physics

Hot topics in astrophysics, gravitation, high energy, and quantum gravity for the week.... Read more »

Negrello, M., & et al. (2010) The Detection of a Population of Submillimeter-Bright, Strongly Lensed Galaxies. Science, 330(6005), 800-804. DOI: 10.1126/science.1193420  

Aguilar-Arevalo, A., & et al. (2010) Event Excess in the MiniBooNE Search for ν[over ¯]_{μ}→ν[over ¯]_{e} Oscillations. Physical Review Letters, 105(18). DOI: 10.1103/PhysRevLett.105.181801  

David J. Toms. (2010) Quantum gravitational contributions to quantum electrodynamics. Nature 468:56-59,2010. arXiv: 1010.0793v1

  • November 2, 2010
  • 11:38 AM
  • 1,168 views

This Week in the Universe: October 26th – November 1st

by S.C. Kavassalis in The Language of Bad Physics

Astrophysics and Gravitation:
Hubble Tries to See into the Future
Illustration Credit: NASA, ESA, and G. Bacon (STScI), Science Credit: NASA, ESA, and J. Anderson and R. van der Marel (STScI)
From NASA, ESA, and J. Anderson and R. van der Marel (STScI):
The multicolor snapshot, at top, taken with Wide Field Camera 3 aboard NASA’s Hubble Space Telescope, captures the central region of the giant globular cluster Omega Centauri. All the stars in the image are moving in random directions, like a swarm of bees. Astronomers used Hubble’s exquisite resolving power to measure positions for stars in 2002 and 2006.
From these measurements, they can predict the stars’ future movement. The bottom illustration charts the future positions of the stars highlighted by the white box in the top image. Each streak represents the motion of the star over the next 600 years. The motion between dots corresponds to 30 years.
By precisely observing the stars in Omega Centauri, a 10 million star globular cluster within our galaxy, the NASA/ESA team has been able to predict the stars’ movements over the next 10,000 years.  Considering how many variables are in this system, this is an awfully impressive achievement.
For more, see Hubble Data Used to Look 10,000 Years into the Future.
High Energy Physics and Particles:
ANITA Balloon sees Cosmic Rays by Accident
Hoover, S., & et al. (2010). Observation of Ultrahigh-Energy Cosmic Rays with the ANITA Balloon-Borne Radio Interferometer Physical Review Letters, 105 (15) DOI: 10.1103/PhysRevLett.105.151101
Credit: Physical Review Letters » Covers » Vol. 105, Iss. 15- Locations of direct (black) and reflected (red) detection of ultrahigh energy cosmic ray events by the ANITA balloon experiment over Antarctica. The field of view is delineated by the dashed blue line.
From the abstract:
We report the observation of 16 cosmic ray events with a mean energy of 1.5×1019 eV via radio pulses originating from the interaction of the cosmic ray air shower with the Antarctic geomagnetic field, a process known as geosynchrotron emission. We present measurements in the 300–900 MHz range, which are the first self-triggered, first ultrawide band, first far-field, and the highest energy sample of cosmic ray events collected with the radio technique. Their properties are inconsistent with current ground-based geosynchrotron models.
The ANITA Experiment, while on the hunt for cosmic neutrinos, ended up seeing 16 exceptionally high energy cosmic ray events (particles with energy several orders of magnitude greater than those made in the LHC).  Accidental observations are always fun, especially when they suggest a new technique for observing known phenomena.  Perhaps radio interferometer equipped balloons will now be used to detect these rare cosmic ray events.
For more, see Antarctic balloon sees particles with a million times more energy than the Large Hadron Collider.
Confirmed Top Quark Observation in the LHC
CMS Collaboration (2010). First Measurement of the Cross Section for Top-Quark Pair Production in Proton-Proton Collisions at sqrt(s)=7 TeV arXiv arXiv: 1010.5994v1
Exciting news! The CMS Collaboration has published their first confirmed observations of top quark production at the LHC this week.  This is especially exciting because it means that we’ll be able to study top quarks in multi-TeV proton-proton collisions for the first time.  At the Tevatron, top quark pairs are mainly produced via quark-antiquark annihilation, while at the LHC top quark pair production is expected to be dominated by a gluon fusion process.  Thus, observing top quark production is crucial to our understanding of this new mechanism. This is an important step in the early physics program at the LHC, since, “many signatures of new physics models accessible at the LHC either suffer from top-quark production as a significant background or contain top quarks themselves.”
The US at the Large Hadron Collider Photo of the Week

Credit: US/LHC - Candidate W-boson decay to tau and neutrino in ATLAS
The US/LHC has started an Event of the Week flickr account, showcasing an exciting and beautiful particle event from the current LHC runs every week.  This weeks was a candidate W-boson decaying into a tau and a neutrino within the ATLAS detector!
General Relativity, Quantum Gravity, et al.:
Want to Learn More about Gauge Gravity?
Andrew Randono (2010). Gauge Gravity: a forward-looking introduction arXiv arXiv: 1010.5822v1
... Read more »

Hoover, S., & et al. (2010) Observation of Ultrahigh-Energy Cosmic Rays with the ANITA Balloon-Borne Radio Interferometer. Physical Review Letters, 105(15). DOI: 10.1103/PhysRevLett.105.151101  

CMS Collaboration. (2010) First Measurement of the Cross Section for Top-Quark Pair Production in Proton-Proton Collisions at sqrt(s). arXiv. arXiv: 1010.5994v1

Andrew Randono. (2010) Gauge Gravity: a forward-looking introduction. arXiv. arXiv: 1010.5822v1

  • October 26, 2010
  • 11:24 AM
  • 971 views

This “Week” in the Universe: October 12th – October 25th

by S.C. Kavassalis in The Language of Bad Physics

Two weeks of news in one!
Astrophysics and Gravitation:
Did We Already Have the Data to Show Dark Matter Annihilation?
Dan Hooper, & Lisa Goodenough (2010). Dark Matter Annihilation in The Galactic Center As Seen by the Fermi Gamma Ray Space Telescope arXiv arXiv: 1010.2752v1
Analyzing old data from the Fermi Gamma Ray Space Telescope, the authors have noticed gamma ray emissions consistent with predictions for a certain type of dark matter.  Unfortunately, these things are never nice, clear problems where they’ve definitely seen dark matter or have definitely not seen it, but it’s an exciting collection of data points for astrophysicists who are on the dark matter hunt.  It could turn out to be the evidence that people have been looking for, but it’s too early to say anything definitively.
For more, see Signs of Destroyed Dark Matter Found in Milky Way’s Core, Fermilab theorist sees dark matter evidence in public data.
Weighing Planets with Pulsars
Champion, D., et al. (2010). MEASURING THE MASS OF SOLAR SYSTEM PLANETS USING PULSAR TIMING The Astrophysical Journal, 720 (2) DOI: 10.1088/2041-8205/720/2/L201
What can’t pulsars do? The team, using an array of pulsars (PSRs J0437–4715, J1744–1134, J1857+0943, J1909–3744), have identified the masses of the planetary system from Mercury to Saturn, in agreement with the best-known masses determined by spacecraft and other observations.  This new method relies on the incredibly predictable nature of pulsars and solar system ephemeris (the past and future positions of the Sun, Moon, and nine planets in three-dimensional space).
From the authors:
While spacecraft are likely to produce the most accurate measurements for individual solar system bodies, the pulsar technique is sensitive to planetary system masses and has the potential to provide the most accurate values of these masses for some planets.
Practical!
For more, see A New Way to Weigh Planets.
A New Standard Candle?
Poznanski, D., Nugent, P., & Filippenko, A. (2010). TYPE II-P SUPERNOVAE AS STANDARD CANDLES: THE SDSS-II SAMPLE REVISITED The Astrophysical Journal, 721 (2), 956-959 DOI: 10.1088/0004-637X/721/2/956
For years, Type Ia supernovae have been used as standard candles to measure cosmic distances; they were especially important for the measurements that determined that the expansion of the universe ws accelerating.  Now, some astrophysicists are suggesting that for even higher accuracy, we use Type II supernovae as well.  Initially, Type II supernovae weren’t used as standard candles because we weren’t as sure about their properties and actual brightness as we were for Type Ia supernovae.  Using additional markers to gauge cosmic distances could help confirm and strengthen current observations, as well as discover inconsistencies.
Adam Burrows, astrophysicist at Princeton University:
It is unlikely that this technique will be able to compete with Ia, but it can contribute complementary cosmic information. It is coming into its own.
For more, see Alternative yardstick to measure the universe.
Dark Matter in the Sun, Revisited
Lopes, I., & Silk, J. (2010). Neutrino Spectroscopy Can Probe the Dark Matter Content in the Sun Science, 330 (6003), 462-462 DOI: 10.1126/science.1196564
The abstract:
After being gravitationally captured, low-mass cold dark-matter particles (mass range from 5 to ~50 x 109 electron volts) are thought to drift to the center of the Sun and affect its internal structure. Solar neutrinos provide a way to probe the physical processes occurring in the Sun’s core. Solar neutrino spectroscopy, in particular, is expected to measure the neutrino fluxes produced in nuclear reactions in the Sun. Here, we show how the presence of dark-matter particles inside the Sun will produce unique neutrino flux distributions in 7Be- and 8B-, as well as 13N-, 15O-, and 17F-.
Finally, a credible sounding experiment to test this dark-matter-in-the-sun-hypothesis, discover that there is no cold dark matter in the sun, and convince people to stop taking things seriously just because they technically “could” be possible.  We’re not 100% sure of the consistency of the moon either, therefore I propose it’s full of anaerobic unicorns.
For more, see Neutrino Spectroscopy Can Probe the Dark Matter Content in the Sun.
New Oldest/Farthest Object in the Universe*
... Read more »

Dan Hooper, & Lisa Goodenough. (2010) Dark Matter Annihilation in The Galactic Center As Seen by the Fermi Gamma Ray Space Telescope. arXiv. arXiv: 1010.2752v1

Champion, D., Hobbs, G., Manchester, R., Edwards, R., Backer, D., Bailes, M., Bhat, N., Burke-Spolaor, S., Coles, W., Demorest, P.... (2010) MEASURING THE MASS OF SOLAR SYSTEM PLANETS USING PULSAR TIMING. The Astrophysical Journal, 720(2). DOI: 10.1088/2041-8205/720/2/L201  

Poznanski, D., Nugent, P., & Filippenko, A. (2010) TYPE II-P SUPERNOVAE AS STANDARD CANDLES: THE SDSS-II SAMPLE REVISITED. The Astrophysical Journal, 721(2), 956-959. DOI: 10.1088/0004-637X/721/2/956  

Lopes, I., & Silk, J. (2010) Neutrino Spectroscopy Can Probe the Dark Matter Content in the Sun. Science, 330(6003), 462-462. DOI: 10.1126/science.1196564  

Lehnert, M., Nesvadba, N., Cuby, J., Swinbank, A., Morris, S., Clément, B., Evans, C., Bremer, M., & Basa, S. (2010) Spectroscopic confirmation of a galaxy at redshift z . Nature, 467(7318), 940-942. DOI: 10.1038/nature09462  

Raphael Bousso, Ben Freivogel, Stefan Leichenauer, & Vladimir Rosenhaus. (2010) Eternal inflation predicts that time will end. arXiv. arXiv: 1009.4698v1

Sabine Hossenfelder. (2010) Experimental Search for Quantum Gravity. arXiv. arXiv: 1010.3420v1

Major, S. (2010) Shape in an atom of space: exploring quantum geometry phenomenology. Classical and Quantum Gravity, 27(22), 225012. DOI: 10.1088/0264-9381/27/22/225012  

Sachdev, S. (2010) Holographic Metals and the Fractionalized Fermi Liquid. Physical Review Letters, 105(15). DOI: 10.1103/PhysRevLett.105.151602  

Henrique Gomes, Sean Gryb, & Tim Koslowski. (2010) Einstein gravity as a 3D conformally invariant theory. arXiv. arXiv: 1010.2481v1

  • October 18, 2010
  • 12:00 PM
  • 939 views

Guest Post: The fine-structure constant is probably constant by Sean Carroll

by S.C. Kavassalis in The Language of Bad Physics

This is the first guest post on The Language of Bad Physics by Cosmic Variance‘s Sean Carroll.  This post is cross-posted on Cosmic Variance.
A few weeks ago there was a bit of media excitement about a somewhat surprising experimental result. Observations of quasar spectra indicated that the fine structure constant, the parameter in physics that describes the strength of electromagnetism, seems to be slightly different on one side of the universe than on the other. The preprint is here.
Remarkable, if true. The fine structure constant, usually denoted α, is one of the most basic parameters in all of physics, and it’s a big deal if it’s not really constant. But how likely is it to be true? This is the right place to trot out the old “extraordinary claims require extraordinary evidence” chestnut. It’s certainly an extraordinary claim, but the evidence doesn’t really live up to that standard. Maybe further observations will reveal truly extraordinary evidence, but there’s no reason to get excited quite yet.
Chad Orzel does a great job of explaining why an experimentalist should be skeptical of this result. It comes down to the figure below: a map of the observed quasars on the sky, where red indicates that the inferred value of α is slightly lower than expected, and blue indicates that it’s slightly higher. As Chad points out, the big red points are mostly circles, while the big blue points are mostly squares. That’s rather significant, because the two shapes represent different telescopes: circles are Keck data, while squares are from the VLT (“Very Large Telescope”). Slightly suspicious that most of the difference comes from data collected by different instruments.

But from a completely separate angle, there is also good reason for theorists to be skeptical, which is what I wanted to talk about. Theoretical considerations will always be trumped by rock-solid data, but when the data are less firm, it makes sense to take account of what we already think we know about how physics works.
The crucial idea here is the notion of a scalar field. That’s just fancy physics-speak for a quantity which takes on a unique numerical value at every point in spacetime. In quantum field theory, scalar fields lead to spinless particles; the Higgs field is a standard example. (Other particles, such as electrons and photons, arise from more complicated geometric objects — spinors and vectors, respectively.)
The fine structure constant is a scalar field. We don’t usually think of it that way, since we usually reserve the term “field” for something that actually varies from place to place rather than remaining constant, but strictly speaking it’s absolutely true. So, while it would be an amazing and Nobel-worthy result to show that the fine structure constant were varying, it wouldn’t be hard to fit it into the known structure of quantum field theory; you just take a scalar field that is traditionally thought of as constant and allow it to vary from place to place and time to time.
That’s not the whole story, of course, When a field varies from point to point, those variations carry energy. Think of pulling a spring, or twisting a piece of metal. For a scalar field, there are three important contributions to the energy: kinetic energy from the field varying in time, gradient energy from the field varying in space, and potential energy associated with the value of the field at every point, unrelated to how it is changing.
For the fine structure constant, the observations imply that it changes by only a very tiny bit from one end of the universe to the other. So we really wouldn’t expect the gradient energy to be very large, and there’s correspondingly no reason to expect the kinetic energy to matter much.
The potential energy is a different matter. The potential is similar to the familiar example of a ball rolling in a hill; how steep the potential is near its minimum is related to the mass of the field. For most scalar fields, like the Higgs field, the potential is extremely steep; this means that if you displace the field from the minimum of its potential by just a bit, it will tend to immediately roll back down.

A priori, we don’t know ahead of time what the potential should look like; specifying it is part of defining the theory. But quantum field theory gives us clues. At heart, the world is quantum, not classical; the “value” of the scalar field is actually the expectation value of a quantum operator. And such an operator gets contributions from the intrinsic vibrations of all the other fields that it couples to — in this case, every kind of charged particle in the universe. What we actually observe is not the “bare” form of the potential, but the renormalized value, which takes into account the accumulated effects of various forms of virtual particles popping in and out of the quantum vacuum.
The basic effect of renormalization on a scalar field potential is easy to summarize: it makes the mass large. So, if you didn’t know any better, you would expect the potential to be as steep as it could possibly be — probably up near the Planck scale. The Higgs boson probably has a mass of order a hundred times the mass of a proton, which sounds large — but it’s actually a big mystery why it isn’t enormously larger. That’s the hierarchy problem of particle physics.
So what about our friend the fine structure constant? Well, if these observations are correct, the field would have to have an extremely tiny mass — otherwise it wouldn’t vary smoothly over the universe, it would just slosh harmlessly around the bottom of its potential. Plugging in numbers, we find that the mass has to be something like 10-42 GeV or less, where 1 GeV is the mass of the proton. In other words: extremely, mind-bogglingly small.
But there’s no known reason for the mass of the scalar field underlying the fine structure constant to be anywhere near that small. This was established in some detail by Banks, Dine, and Douglas. They affirmed our intuition, that a tiny change in the fine structure constant should be associated with a huge change in potential energy.
Now, there are loopholes — there are always loopholes. In this case, you could possibly prevent those quantum fluctuations from renormalizing your scalar-field potential simply by shielding the field from interactions with other fields. That is, you can impose a symmetry that forbids the field from coupling to other forms of matter, or only lets it couple in certain very precise ways; then you could at least imagine keeping the mass small. That’s essentially the strategy behind the supersymmetric solution to the hierarchy problem.
Problem is, that route is a complete failure when we turn to the fine structure constant, for a very basic reason: we can’t prevent it from coupling to other fields, it’s the parameter that governs the strength of electromagnetism! So like it or not, it will couple to the electromagnetic field and all charged particles in nature. I talked about this in one of my own papers from a few years ago. I was thinking about time-dependent scalars, not spatially-varying ones, but the principles are precisely the same.
That’s why theorists are skeptical of this claimed result. Not that it’s impossible; if the data stand up, it will present a serious challenge to our theoretical prejudices, but that will doubtless goad theorists into being more clever than usual in trying to explain it. Rather, the point is that we have good reasons to suspect that the fine structure constant really is constant; it’s not just a fifty-fifty kind of choice. And given those good reasons, we need really good data to change our minds. That’s not what we have yet — but what we have is certainly more than enough motivation to keep searching.

... Read more »

J. K. Webb, J. A. King, M. T. Murphy, V. V. Flambaum, R. F. Carswell, & M. B. Bainbridge. (2010) Evidence for spatial varia. arXiv. arXiv: 1008.3907v1

  • October 11, 2010
  • 06:59 PM
  • 1,019 views

This Week in the Universe: October 5th – October 11th

by S.C. Kavassalis in The Language of Bad Physics

Astrophysics and Gravitation:
Early Universe was Overheated, says NASA
Michael Shull, Kevin France, Charles Danforth, Britton Smith, & Jason Tumlinson (2010). Hubble/COS Observations of the Quasar HE 2347-4342: Probing the Epoch of He II Patchy Reionization at Redshifts z = 2.4-2.9 arXiv arXiv: 1008.2957v1
Credit: NASA/Michael Shull, University of Colorado
From the Press Release:
During a period of universal warming 11 billion years ago, quasars — the brilliant core of active galaxies — produced fierce radiation blasts that stunted the growth of some dwarf galaxies for approximately 500 million years.  This important conclusion comes from a team of astronomers that used the new capabilities of NASA’s Hubble Space Telescope to probe the invisible, remote universe. The team’s results will be published in… The Astrophysical Journal.
For more, see Hubble Astronomers Uncover an Overheated Early Universe.
Dark Matter, Neutron Stars, and Strange Quark Matter, Oh My!
Perez-Garcia, M., Silk, J., & Stone, J. (2010). Dark Matter, Neutron Stars, and Strange Quark Matter Physical Review Letters, 105 (14) DOI: 10.1103/PhysRevLett.105.141101
The abstract:
We show that self-annihilating weakly interacting massive particle (WIMP) dark matter accreted onto neutron stars may provide a mechanism to seed compact objects with long-lived lumps of strange quark matter, or strangelets, for WIMP masses above a few GeV. This effect may trigger a conversion of most of the star into a strange star. We use an energy estimate for the long-lived strangelet based on the Fermi-gas model combined with the MIT bag model to set a new limit on the possible values of the WIMP mass that can be especially relevant for subdominant species of massive neutralinos.
For more, see Does dark matter trigger strange stars?.
High Energy Physics and Particles:
Hey, this isn’t research news!
Yeah, it’s not… But, for anyone who will be in Manchester from October 23rd – 27th, 2010 should make sure they check out Super K Sonic Booooum!
This large installation consists of a 22 meter long ‘river’ of water running through a tunnel lined with thousands of silver balloons (photomultiplier tubes). Members of the public embark on a boat, pulled through the tunnel on a submerged track using a pulley system, with sound and lighting effects, and with an expert particle physicist navigator as a guide. On the journey they learn of neutrinos, their role in the Universe and how scientists detect them. All crew members must first don white Tyvek suits, wellies and hard hats or else face the wrath of Nelly the security chief, at the entrance of the tunnel. This installation is designed to deliver physically thrilling experiences; emerging the audience on a journey through the physics of the Universe.
Workshop on Sunday 24 October – 2pm – 4pm
Capture the Invisible: Craft and Science in particle physics.
In this workshop you will get the chance to make your own photomultiplier tube to capture the invisible in your own bedroom! Designed by Nelly Ben Hayoun in collaboration with Dr Jonathan Perkin, physicist and glassblower Jochen Holz
For more, see Super K Sonic Booooum.
SuperB Project Preparing for Construction!
SuperB Collaboration, E. Grauges et al., Francesco Forti, Blair N. Ratcliff, & David Aston (2010). SuperB Progress Reports — Detector arXiv arXiv: 1007.4241v1
It looks like funding for the SuperB Collaboration will come through and see the new experiment built in Frascati.  I hope the Italians take this great opportunity to make many “flavour country” jokes.
From the press release:
The most elementary components of matter, quarks and leptons, have been found, as the result of 100 years of research, to be organized into three replicating “families”. The reason for this specific number or organization remains a full mystery. Flavor physics, the detailed understanding of the relationship between these families and the comparison between properties of matter and antimatter, is one of the most promising ways to explore new physics, quite complementary to the energy frontier research most notably pursued at the CERN LHC collider. Different kinds of new physics have different effects on rare decays of bottom and charmed quarks and of heavy tau leptons. These particles are all produced at SuperB in unparalleled abundance, making possible for the first time measurements of the precision required to be sensitive to the details of new physics uncovered at CERN.
For more, see SuperB project moves forward, preparing for construction.
Bonner Nuclear Lab to Study Quark-Gluon Plasma
Credit: Frank Geurts/Rice University
It was a good week to get funding for high-energy experiments.
From the Press Release:
Rice University’s Bonner Nuclear Lab has won a $1.175 million grant that will support its research on high-density and hot nuclear matter.  Rice physicist Frank Geurts, who has spent his career looking for clues to the basic elements of the universe by smashing the nuclear contents of gold, lead and other heavy atoms, said the Department of Energy grant will facilitate his group’s transition from constructing and commissioning a highly complex detector system to using that machinery to do basic research.
Video: Quark gluon plasma (QGP)
For more, see Grant advances quark-gluon ... Read more »

Michael Shull, Kevin France, Charles Danforth, Britton Smith, & Jason Tumlinson. (2010) Hubble/COS Observations of the Quasar HE 2347-4342: Probing the Epoch of He II Patchy Reionization at Redshifts z . arXiv. arXiv: 1008.2957v1

Perez-Garcia, M., Silk, J., & Stone, J. (2010) Dark Matter, Neutron Stars, and Strange Quark Matter. Physical Review Letters, 105(14). DOI: 10.1103/PhysRevLett.105.141101  

SuperB Collaboration, E. Grauges et al., Francesco Forti, Blair N. Ratcliff, & David Aston. (2010) SuperB Progress Reports -- Detector. arXiv. arXiv: 1007.4241v1

Gary Felder, & Stephanie Erickson. (2010) CurvedLand: An Applet for Illustrating Curved Geometry without Embedding. arXiv. arXiv: 1010.1426v1

Poltis, R., & Stojkovic, D. (2010) Can Primordial Magnetic Fields Seeded by Electroweak Strings Cause an Alignment of Quasar Axes on Cosmological Scales?. Physical Review Letters, 105(16). DOI: 10.1103/PhysRevLett.105.161301  

  • October 4, 2010
  • 09:41 PM
  • 503 views

This Week in the Universe: September 28th – October 4th

by S.C. Kavassalis in The Language of Bad Physics

Astrophysics and Gravitation:
Vacuum-Driven Evolution in Astrophysics
William C. C. Lima, George E. A. Matsas, & Daniel A. T. Vanzella (2010). Awaking the vacuum in relativistic stars Physical Review Letters arXiv: 1009.1771v1
In a very cool paper that will be appearing in the Physical Review Letters at the end of the week, Lima et al. have shown an interesting (and surprising) relationship between neutron star formation and the vacuum energy density of our universe. Using some semi-classical concepts of gravity [PRL 104, 161102 (2010)], the authors come the conclusion that the formation of relativistic, compact, objects (like neutron stars) could disturb the vacuum of a quantum field (of a certain type) which could cause the energy density of the vacuum to undergo exponential growth.  This growth could eventually lead to the collapse or explosion of the relativistic object in question.  Of course, the observation of stable neutron stars should be suggestive that such fields (that could have triggered this exponential growth in energy density) can not exist.  Thus, if we see stable neutron stars (which we think we do), we learn something about the vacuum state of the universe, ie. the observation of a stable and (reasonably) spinless cold neutron star would rule out the existence of massless scalar fields with a range of coupling constants.  Seeing as we only know what a marginal fraction of the universe’s energy content is, this could prove incredibly useful for the field theoretically inclined cosmologists out there.  The nitty-gritty details on what should specifically happen to these relativistic objects hasn’t been worked out just yet (I’m sure someone will be donating some cluster time soon), but when it has, we may end up learning something new and exciting about one of the most basic aspects of our universe.
For more, see Neutron Star Formation Could Awaken the Vacuum.
High Energy Physics and Particles:
Randomness Brings Order to Quarks
P. H. Damgaard, K. Splittorff, & J. J. M. Verbaarschot (2010). Microscopic Spectrum of the Wilson Dirac Operator arXiv arXiv: 1001.2937v3
An interesting paper out of the Niels Bohr Institute shows how large quantities of random numbers can help explain the oscillations of quarks within protons.
Kim Splittorff:
Over several years it became increasingly clear that the way in which the left-handed and right-handed quarks come together can be described using a massive quantities of random numbers. These random numbers are elements in a matrix, which one may think of as a Soduko filled in at random. In technical jargon these are called Random Matrices.
Random numbers have been used for quite some time to make sense of spontaneous symmetry breaking, but what is unique about this team’s work is that they are doing it exactly.
Splittorff:
What is new about our work is that not only the exact equation for quarks, but also the approximation, which researchers who work numerically have to use, can be described using random matrices. It is already extremely surprising that the exact equation shows that the quarks swing by random numbers. It is even more exciting that the approximation used for the equation has a completely analogous description. Having an accurate analytical description available for the numerical simulations is a powerful tool that provides an entirely new understanding of the numerical data. In particular, we can now measure very precisely how closely the right-handed and left-handed quarks are dancing
How “exact” this really can be, is more of a philosophical question at this point, but this technique will find use in helping make predictions at CERN and even in condensed matter systems.
For more, see Quarks ‘swing’ to the tones of random numbers.
General Relativity, Quantum Gravity, et al.:
Hawking Radiation, Observed?
F. Belgiorno, S. L. Cacciatori, M. Clerici, V. Gorini, G. Ortenzi, L. Rizzi, E. Rubino, V. G. Sala, & D. Faccio (2010). Hawking radiation from ultrashort laser pulse filaments arXiv arXiv: 1009.4634v1
I have lengthy comments to make on this paper that will appear later this week, but it is a fascinating (and short) read.
The abstract:
Event horizons of astrophysical black holes and gravitational analogues have been predicted to excite the quantum vacuum and give rise to the emission of quanta, known as Hawking radiation. We experimentally create such a gravitational analogue using ultrashort laser pulse filaments and our measurements demonstrate a spontaneous emission of photons that confirms theoretical predictions.
Did they really observe Hawking radiation? That’s a question that will be open for debate for quite some time.
For more, see Physicists may have observed Hawking radiation for the first time, Imitation black hole seen on earth.
... Read more »

William C. C. Lima, George E. A. Matsas, & Daniel A. T. Vanzella. (2010) Awaking the vacuum in relativistic stars. Physical Review Letters. arXiv: 1009.1771v1

P. H. Damgaard, K. Splittorff, & J. J. M. Verbaarschot. (2010) Microscopic Spectrum of the Wilson Dirac Operator. arXiv. arXiv: 1001.2937v3

F. Belgiorno, S. L. Cacciatori, M. Clerici, V. Gorini, G. Ortenzi, L. Rizzi, E. Rubino, V. G. Sala, & D. Faccio. (2010) Hawking radiation from ultrashort laser pulse filaments. arXiv. arXiv: 1009.4634v1

  • September 27, 2010
  • 11:27 AM
  • 728 views

This (Long) Week in the Universe: September 16th – September 27th

by S.C. Kavassalis in The Language of Bad Physics

I know, I know, I switched back to writing these on Mondays again without telling anyone.  It turns out, Wednesdays were a terrible choice of day for me. I swear I asked someone to fill in for me last week…
...but I guess she wasn't all that interested in the job.
Astrophysics and Gravitation:
Taking a Swim in the Lagoon Nebula
Credit: NASA/ESA Hubble Space Telescope
NASA and the ESA Hubble Space Telescope, via the Advanced Camera for Surveys, have provided us with a gorgeous picture of the Lagoon Nebula.  This nebula is of particular interest to amateur astronomers because it is one of only a few of its kind actually visible with the naked eye from Earth.  While it may be a blurry oval to the unassisted human viewer, to Hubble, this gas cloud is a giant, dynamic, home to new stars.  Okay, so there isn’t any new physics here, but they did get a great image.
For more, see Breaking Waves in the Stellar Lagoon.
AGILE on Gamma Rays
Marisaldi, M., et al. (2010). Gamma-Ray Localization of Terrestrial Gamma-Ray Flashes Physical Review Letters, 105 (12) DOI: 10.1103/PhysRevLett.105.128501
A team using satellite data to watch thunderstorms has figured out to to locate gamma rays (sometimes produced in said thunderstorms) with exceptional accuracy.  These models are helping physicists understand gamma rays and how they relate to electrical storms (which most theories wouldn’t actually anticipate).
For more, see Pinpointing Earthly Gamma Rays.
ANITA on Cosmic Rays
S. Hoover, & et al. (2010). Observation of Ultra-high-energy Cosmic Rays with the ANITA Balloon-borne Radio Interferometer Physical Review Letters arXiv: 1005.0035v2
A team using airborne radio detectors has noticed a characteristic radio wave signal produced by ultrahigh energy cosmic rays as they hit the ice in the Antarctic.  Since we still don’t know where these ultrahigh energy particles come from, being able to track them once they hit the earth will be a useful tool in figuring out where they originated from.
For more, see Tuning In to Highest Energy Cosmic Rays.
So Long S-Process
A. J. Gallagher, S. G. Ryan, A. E. García Pérez, & W. Aoki (2010). The barium isotopic mixture for the metal-poor subgiant star HD140283 Astronomy and Astrophysics arXiv: 1008.3541v1
Snipet from the abstract:
Current theory regarding heavy element nucleosynthesis in metal-poor environments states that the r-process would be dominant. The star HD140283 has been the subject of debate after it appeared in some studies to be dominated by the s-process. We provide an independent measure… that observations and analysis do not validate currently accepted theory.
It’s another one of these fun astrophysics mysteries.  We have a reasonable idea how stars work, but every now and then an observation comes along and tells us that our theoretical mechanisms can not be the end all be all of star dynamics and formation.  Star HD140283 is another fun piece to contradictory puzzle.  Because of the suspected age of HD140283 (ie. that it’s very, very old), it should have formed in its galaxy before the first red giants/barium producing stars formed, meaning that it shouldn’t (and according to current theory, couldn’t) have inherited any barium from its neighbours (and thus undergo r-process nucleosynthesis).  However, Gallagher et al.’s team’s observations say otherwise (that instead, we see s-process nucleosynthesis).  Is the current model of star formation incorrect, ie. do we need to rethink this late production of s-process isotope issue? Could there have been barium somehow to kick off this stars life? Could it be something else? Could that star have somehow been pulled in from an older galaxy? At this point, it seems pretty open.
For more, see Ancient star poses galactic puzzle.
High Energy Physics and Particles:
Good news, everyone! We might have been way off about quarks and gluons!
... Read more »

Marisaldi, M., Argan, A., Trois, A., Giuliani, A., Tavani, M., Labanti, C., Fuschino, F., Bulgarelli, A., Longo, F., Barbiellini, G.... (2010) Gamma-Ray Localization of Terrestrial Gamma-Ray Flashes. Physical Review Letters, 105(12). DOI: 10.1103/PhysRevLett.105.128501  

S. Hoover, & et al. (2010) Observation of Ultra-high-energy Cosmic Rays with the ANITA Balloon-borne Radio Interferometer. Physical Review Letters. arXiv: 1005.0035v2

A. J. Gallagher, S. G. Ryan, A. E. García Pérez, & W. Aoki. (2010) The barium isotopic mixture for the metal-poor subgiant star HD140283. Astronomy and Astrophysics. arXiv: 1008.3541v1

CMS Collaboration. (2010) Observation of Long-Range Near-Side Angular Correlations in Proton-Proton Collisions at the LHC. JHEP. arXiv: 1009.4122v1

Lehner, L., & Pretorius, F. (2010) Black Strings, Low Viscosity Fluids, and Violation of Cosmic Censorship. Physical Review Letters, 105(10). DOI: 10.1103/PhysRevLett.105.101102  

Chou, C., Hume, D., Rosenband, T., & Wineland, D. (2010) Optical Clocks and Relativity. Science, 329(5999), 1630-1633. DOI: 10.1126/science.1192720  

  • September 15, 2010
  • 10:16 AM
  • 900 views

This Week in the Universe: September 9th – September 15th

by S.C. Kavassalis in The Language of Bad Physics

Astrophysics and Gravitation:
Astrophysics, by General Mills
Vella, D., & Mahadevan, L. (2005). The “Cheerios effect” American Journal of Physics, 73 (9) DOI: 10.1119/1.1898523
FOX News and a few other news agencies have discovered the Cheerios Effect this week (unfortunately, MSNBC beat them to this scope by about five years).  Back in 2005, Vella and Mehadevan described the “Cheerios Effect”, the tendency for small, wet, objects to attract each other.
From the abstract:
Objects that float at the interface between a liquid and a gas interact because of interfacial deformation and the effect of gravity.
Makes sense, but what does this have to do with astrophysics? Well, just like how the few remaining Cheerios left in the bowl have a tendency to group together in the milk, galaxies have a tendency to group together in space.  While the forces involved are quite different, the outcome is visually rather similar, and, astrophysics has a long history of using fluid models for approximations.  Is this big news? No, but it makes a very good classroom demonstration (as the authors originally wanted).
For more, see Cereal And Saturday Morning Physics.
PAMELA Results on the Cosmic-Ray Antiproton Flux
O. Adriani, & et al. (2010). PAMELA Results on the Cosmic-Ray Antiproton Flux from 60 MeV to 180 GeV in Kinetic Energy Phys. Rev. Lett., 105 (12), 1101-1106 : 10.1103/PhysRevLett.105.121101
The abstract:
The satellite-borne experiment PAMELA has been used to make a new measurement of the cosmic-ray antiproton flux and the antiproton-to-proton flux ratio which extends previously published measurements down to 60 MeV and up to 180 GeV in kinetic energy. During 850 days of data acquisition approximately 1500 antiprotons were observed. The measurements are consistent with purely secondary production of antiprotons in the Galaxy. More precise secondary production models are required for a complete interpretation of the results.
Earlier this year, PAMELA observed an usually large flux of positrons within the cosmic rays they were seeing from some unknown, beyond the atmosphere, source.  Naturally, like all unusual cosmic ray results, people thought “dark matter”.  Now, with more data, the PAMELA team has confirmed these observations, but still can’t suggest a cause.  Observation supports some “secondary production” mechanism for their creation, ie. the positrons being produced by some annihilation interaction with some unknown particles, but it’s still quite open what that might be.
For more, see Uncertain Sources.
Hungry Hungry Stars
Credit: X-ray (NASA/CXC/RIT/J.Kastner et al), Optical (UCO/Lick/STScI/M.Perrin et al); Illustration: NASA/CXC/M.Weiss
NASA’s Chandra X-ray Observatory has recently seen evidence of star cannibalism.  It appears that star BP Piscium (BP Psc – a red giant phase star once probably the size of our Sun) may have absorbed a companion star in the past (or perhaps a large planet).
David Rodriguez from UCLA:
BP Psc shows us that stars like our Sun may live quietly for billions of years, but when they go, they just might take a star or planet or two with them.
For more, see Chandra Finds Evidence for Stellar Cannibalism.
Dark Matter in the Sun (again?)
Lopes, I., & Silk, J. (2010). Neutrino Spectroscopy Can Probe the Dark Matter Content in the Sun Science DOI: 10.1126/science.1196564
From the abstract:
After being gravitationally captured, low mass cold dark matter particles (mass range 5 to ~50 x 109 electron volts) are thought to drift to the center of the Sun and affect its internal structure. Solar neutrinos provide a way to probe the physical processes occurring in the Sun’s core. Solar neutrino spectroscopy, in particular, is expected to measure the neutrino fluxes produced in nuclear reactions in the Sun. Here, we show how the presence of dark matter particles inside the Sun will produce unique neutrino flux distributions…
Ah, more speculation that dark matter could be found inside the sun.  Is this based on observation? Well no, but we still can’t quite explain the expected composition of the sun with its mass and spectrum, so there is room for dark matter.  Is it science? Not yet.
For more, see Searching the Sun for dark matter.
General Relativity, Quantum Gravity, et al.:
Fun with Five-Dimensional Black Strings
Lehner, L., & Pretorius, F. (2010). Black Strings, Low Viscosity Fluids, and Violation of Cosmic Censorship Physical Review Letters, 105 (10) DOI: 10.1103/PhysRevLett.105.101102
The Abstract:
We describe the behavior of 5-dimensional black strings, subject to the Gregory-Laflamme instability. Beyond the linear level, the evolving strings exhibit a rich dynamics, where at intermediate stages the horizon can be described as a sequence of 3-dimensional spherical black holes joined by black string segments. These segments are themselves subject to a Gregory-Laflamme instability, resulting in a ... Read more »

Vella, D., & Mahadevan, L. (2005) The “Cheerios effect”. American Journal of Physics, 73(9), 817. DOI: 10.1119/1.1898523  

O. Adriani, & et al. (2010) PAMELA Results on the Cosmic-Ray Antiproton Flux from 60 MeV to 180 GeV in Kinetic Energy. Phys. Rev. Lett., 105(12), 1101-1106. info:/10.1103/PhysRevLett.105.121101

Lopes, I., & Silk, J. (2010) Neutrino Spectroscopy Can Probe the Dark Matter Content in the Sun. Science. DOI: 10.1126/science.1196564  

Lehner, L., & Pretorius, F. (2010) Black Strings, Low Viscosity Fluids, and Violation of Cosmic Censorship. Physical Review Letters, 105(10). DOI: 10.1103/PhysRevLett.105.101102  

  • September 9, 2010
  • 11:11 AM
  • 557 views

This Week in the Universe: September 2nd – September 8th

by S.C. Kavassalis in The Language of Bad Physics

Astrophysics and Gravitation:
What Supernova 1987A Left Behind
France, K., McCray, R., Heng, K., Kirshner, R., Challis, P., Bouchet, P., Crotts, A., Dwek, E., Fransson, C., Garnavich, P., Larsson, J., Lawrence, S., Lundqvist, P., Panagia, N., Pun, C., Smith, N., Sollerman, J., Sonneborn, G., Stocke, J., Wang, L., & Wheeler, J. (2010). Observing Supernova 1987A with the Refurbished Hubble Space Telescope Science DOI: 10.1126/science.1192134
Hubble Video: Supernova 1987A Observed by Hubble from 1994 – 2006
Old data from the Hubble Telescope is shedding new light on the remnants of Supernova 1987A.  It appears that shock waves of gas that were/are being sent out by the supernova core are brightening the ring shaped cloud of dust surrounding it.  It may not add anything critical to our understanding of gravitational collapse, but it makes for pretty visuals.
For more, see ‘Lost years’ end for backyard supernova.
Seeding Magnetic Fields in Spacetime?
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
The Abstract:
We demonstrate that a purely ideal mechanism, originating in the space-time distortion caused by the demands of special relativity, can break the topological constraint (leading to helicity conservation) that would forbid the emergence of a magnetic field (a generalized vorticity) in an ideal nonrelativistic dynamics. The new mechanism, arising from the interaction between the inhomogeneous flow fields and inhomogeneous entropy, is universal and can provide a finite seed even for mildly relativistic flows.
I have to say, this abstract doesn’t make a lot of sense to me, as written.  There is no “spacetime distortion” caused by special relativity, so I’m not entirely sure I understand their meaning here, but let’s address the subject at hand.  In 1979, E.N. Parker wrote a book called “Cosmical Magnetic Fields: Their Origin and Their Activity” in which addressed the issue of, as the title would suggest, cosmic magnetic fields, specifically the generation of said magnetic fields within astronomical bodies.  Then, in 2002, Lawrence Widrow wrote a brief follow up, of sorts, called “Origin of galactic and extragalactic magnetic fields“, where he talks about:
A variety of observations suggest that magnetic fields are present in all galaxies and galaxy clusters… However, fundamental questions concerning the nature of the dynamo as well as the origin of the seed fields necessary to prime it remain unclear.
Finally, in 2008, a fairly comprehensive review paper was written by Kulsrud and Zweibel called, “On the origin of cosmic magnetic fields“, which ends with,
Our conclusion as to the most likely origin of cosmic magnetic fields is that they are first produced at moderate field strengths by primordial mechanisms and then changed and their strength increased to their present value and structure by a galactic disc dynamo. The primordial mechanisms have not yet been seriously developed, and this preliminary amplification of the magnetic fields is still very open.
So this basically brings us to 2010.  In all of the early work on cosmic magnetic field origins, “nonideal mechanisms”, like the baroclinic effect (apparently…), were used to suggest plausible creation or “seed” scenarios for these magnetic fields.  However, the authors of this current paper take a different approach:
[Generalized vorticity] can be generated in strictly ideal dynamics, as long as the dynamics is explicitly embedded in the space-time dictated by the demands of special relativity. The generalized vorticity is, then, generated through a source term born out of the special relativistic ‘‘modifications’’ to the interaction of an inhomogeneous flow with inhomogeneous entropy.
The authors are talking about vorticity instead of magnetism directly because of the “mathematical and dynamical similarity between magnetic fields and fluid vorticity” (it might be a good strategy).  So what are these modifications? Basically, they’re just adding in special relativity to fluid dynamics and drawing an analogy with magnetism.  This has nothing to do with any spacetime distortion (because “spacetime” as a concept only exists in special and general relativity, anyway… so adding special relativity doesn’t “distort” it) or “topology” (the word does appear once in the body of the paper though).
For more, see Origin of magnetic fields may lie in special relativity’s spacetime distortions.
Static Universes Never Die
Well they don’t.
David F. Crawford (2010). Observational evidence favours a static universe arXiv : 1009.0953
... Read more »

France, K., McCray, R., Heng, K., Kirshner, R., Challis, P., Bouchet, P., Crotts, A., Dwek, E., Fransson, C., Garnavich, P.... (2010) Observing Supernova 1987A with the Refurbished Hubble Space Telescope. Science. DOI: 10.1126/science.1192134  

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  

David F. Crawford. (2010) Observational evidence favours a static universe. arXiv. info:/1009.0953

Katrin Gelfert, & Adilson E. Motter. (2010) (Non)Invariance of Dynamical Quantities for Orbit Equivalent Flows . Communications in Mathematical Physics. info:/10.1007/s00220-010-1120-x

Steven Carlip. (2010) The Small Scale Structure of Spacetime. arXiv. arXiv: 1009.1136v1

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