Cosmology
LISA technology and instrumentation
Oliver Jennrich (European Space Agency) has prepared a large review on technical aspects of LISA (space laser interferometer) mission – the project is extremely complicated for realization, many technologies are not even yet fully developed, and various prototypes will have to be launched. Yet, possible payout is so huge – even including possible detection of gravitational waves from the very early Universe – from inflationary and reheating stages (just think about it – detecting EM radiation did not really allow us to go beyond redshift 
so far, not including here CMB of course). Who is a sucker for space research as I am – please check out the paper. It does not discuss science related to the mission but contains tons of technical information about LISA you won’t find anywhere else.
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Susskind’s lectures on cosmology
Another amazing set of 8 lectures by Lenny Susskind – cosmology this time. Thanks for sharing this, Stanford!
P.S. If you were unable to see embedded video, here is the link to the playlist I’ve created for you.
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Other interesting things in ArXiv (12 Jun 2009)
Wayne Hu. Acceleration from modified gravity: lessons from worked examples. The main question Wayne Hu discusses in this minireview is “How can we distinguish dark energy from modified gravity theories if the former and the latter provide the same predictions for cosmological dynamics?” He is particularly focused on DGP and 
models. His answer is the presence of anisotropic stress for modified gravity models which is coupled directly to lensing potential – if we are able to measure this effect, we will be able to discriminate between IR modified gravity and dark energy. Another idea is to study behavior of theories in non-linear regimes, for example, by means of N-body simulation, and compare it to LSS.
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Lithium problem
Apart from being a very nice review of Big Bang Nucleosynthesis (BBN), recent paper by Karsten Jedamzik and Maxim Pospelov discusses an important open problem in the physics of BBN.
In short, the lithium problem in physics of Big Bang Nucleosynthesis is seeming underproduction of 
. What do we mean by that?
Rocky Kolb’s lecture on Dark Universe
… namely, about dark matter and dark energy as you may imagine. The lecture itself (2009 Buhl lecture at Carnegie Mellon U) is actually very clear and suitable for newcomers/non-scientists. So, if you want to know in some details (more or less technical) what the modern cosmology is all about, please check out this lecture.
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Other interesting things in ArXiv (11 Jun 2009)
Basically, there were so many interesting and useful papers (or at least they were useful for me) – lecture notes, reviews – that it will give me hard time posting reviews of all of them here – since I am lazy, I’ll just try to list some of them.
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Into dark ages or again about GRB090423
Back in April, I already wrote about GRB090423 – currently the most distant detected object in the Universe. Yesterday, two papers with details of mesurement have appeared in astro-ph (unfortunately, Icannot give you the links – see my comment below).
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How to spot a black hole on the Sky
Here is a video from NewScientist featuring simulations by Loeb and his collaborators (we have discussed Loeb’s results several times on NEQNET). The idea is that BH acts as a strong gravitational lense, so if we have a close system “star-BH”, we will see a very specific pattern of light when the companion star crosses the “disk” of BH. Of course, in order for us to spot this pattern, it is better if the line of our sight lights in the orbit plane of the star.
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This and that in ArXiv on Monday
Due to unbelievable overload of the last days let me simply list the recent papers in ArXiv that I found the most interesting:
1. Quantum information
T. Tilma el al., “Is entanglement a critical resource for quantum metrology?”
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Three last Susskind’s lectures on general relativity
… that is, lectures 10, 11 and 12: gravity in 4+1 dimensions, dynamics of scalars in curved spacetimes (and behavior of gravitational potential – which is scalar), a bit of topology (Euler characteristics), Lagrangian of a relativistic massive point particle, geodesics in curved spacetime and, finally, Schwarzschild solution.
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Workshop on tests of gravity in Case Western – day 2: aether and modified gravity
Let me finally briefly review the reminder of the second day of the workshop.
Justin Khoury (whom I knew from Perimeter years and who is in Penn now) gave the first talk afternoon – titled “observational hints of IR modified gravity”. His talk followed Nima’s, and the latter almost completely blew me away, so I was somewhat unfocused during Justin’s presentation. Yet, I was able to capture that as such observational hints he wanted to present local bulk flow of matter within 50 
MPc scale, excess power in Lyman 
(about 30%) and small scale CMB anomalies (which I would hardly call anomalies due to lack of statistics there). According to him, all this shows that gravity should be stronger at larger scales – and that’s exactly what many models of modified gravity predict.
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Susskind’s general relativity – lecture 9
… where Leonard Susskind discusses spacetime – spacelike, timelike and lightlike directions, explains how one gets special relativity from general relativity (post-Newtonian approximation), non-relativistic limit of GR and finally … Einstein equations (hurray!)
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Workshop on tests of gravity in Case Western – day 2 and Arkani-Hamed’s talk
The second day of the Workshop on Tests of Gravity (and here is my blog post about the first day) was mostly devoted to analog models (Bill Unruh, Michael Uhlmann, George Pickett) and models of modified gravity (Nima Arkani-Hamed, Justin Khoury, Stacy McGaugh, Ted Jacobson, Levon Pogosyan and Mark Wyman).
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Susskind’s 8th lecture on general relativity
Leonard Susskind continues reading his lecture course on general relativity in U. of Stanford. Previous lectures can be found here: Lectures 1-5, Lecture 6 and Lecture 7.
Susskind continues to discuss covariant derivatives, parallel transport of vectors, Ricci and Riemann tensors. In the second part of the lecture he turns to geodesics. He is terrific lecturer but after the lecture N7 I start wondering whether it’s worth spending so much time discussing technicalities 
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Workshop on tests of gravity at Case Western – day 1
Dear friends,
I am sorry for being rather quiet for a while. As many of you may already know, my laptop has decided to enter coma during the trip, as a result, I was left without appropriate internet access (sporadic use of Pascal Vaudrevange’s computer is not counted, thanks, Pascal!). Although the laptop tried to revive after we came back home, demonstrating some kind of “brain” activity, in a couple of days I understood that the growth of entropy is as inevitable as a finally victory of string theory over loop quantum gravity.
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