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Physicists at CERN's Large Hadron Collider (LHC) are analysing the results of their first attempt at colliding protons and lead ions. Further attempts at proton-lead collisions are expected over the next few weeks. If these trials are successful, a full-blown experimental programme could run in 2012.

In a surprise announcement earlier today (July 13), the European Southern Observatory said that monster black holes - those giants of millions or billions of solar masses, thought to lurk at the hearts of most galaxies - have a mechanism to become active other than galaxy collisions.

"A new study combining data from ESO's Very Large Telescope and ESA's XMM-Newton X-ray space observatory has turned up a surprise. Most of the huge black holes in the centers of galaxies in the past 11 billion years were not turned on by mergers between galaxies, as had been previously thought." and "The process that activates a sleeping black hole - turning its galaxy from quiet to active - has been a mystery in astronomy. What triggers the violent outbursts at a galaxy's center, which then becomes an active galactic nucleus? Up to now, many astronomers thought that most of these active nuclei were turned on when two galaxies merged, or when they passed close to each other and the disrupted material became fuel for the central black hole. Results of the new study indicate this idea may be wrong for many active galaxies." very interesting indeed

New technology (STARE-a constellation of nano-satellites) for tracking satellites and space debris could improve the accuracy from 1km (current by NORAD) to less than 100m. Increasing the reliability of collision detection, preventing 99% of false warnings.

U.S. scientists say they're working on mini-satellites that could function as "space cops" to help avoid collisions in space of satellites and space debris. Researchers at the Lawrence Livermore National Laboratory in California have tested a ground-based satellite to prove it is possible to refine the orbit of another satellite in low Earth orbit.

Theoretized 80 years ago was Breit-Wheeler pair production in which two photons result in an electron-positron pair (via a virtual electron). It is a relatively simple Feynmann diagram, but the problem is/was how to produce in practice a high energy photon-photon collider... The collider experiment that the scientists have proposed involves two key steps. First, the scientists would use an extremely powerful high-intensity laser to speed up electrons to just below the speed of light. They would then fire these electrons into a slab of gold to create a beam of photons a billion times more energetic than visible light. The next stage of the experiment involves a tiny gold can called a hohlraum (German for 'empty room'). Scientists would fire a high-energy laser at the inner surface of this gold can, to create a thermal radiation field, generating light similar to the light emitted by stars. They would then direct the photon beam from the first stage of the experiment through the centre of the can, causing the photons from the two sources to collide and form electrons and positrons. It would then be possible to detect the formation of the electrons and positrons when they exited the can. Now this is a good experiment... :)

True, but isnt it E2=(pc)^2 + (m0c^2)^2 such that for photons E\propto{pc} and for mass E\propto{mc^2}. I agree it will take a lot of energy, but this assumes that that wont be the problem at least. The question therefore is whether the mass flow of the photon rocket (fuel consumed to create photons, eg fission/fusion) is higher/lower than the mass flow for e-p creation. You are probably right that the low e-p cross-section will favour direct use of photons to create low thrust for long periods of time, but with significant power available the ISP might be higher for e-p pair creation.

In essence the equation tells you that for photons with zero rest mass m0 all the energy will be converted to momentum of the particles. If you want to accelerate e-p then you first spend part of the energy on creating them (~511 keV each) and you can only use the remaining energy to accelerate them. In this case the equation gives you a lower particle momentum which leads to lower thrust (even when assuming 100% acceleration efficiency). ISP is a tricky concept in this case because there are different definitions which clash in the relativistic context (due to the concept of mass flow). R. Tinder gets to a I_SP = c (speed of light) for a photon rocket (using the relativistic mass of the photons) which is the maximum possible relativistic I_SP: http://goo.gl/Zz5gyC .

first science results reported in Nature (as far as I know) from the Yutu-2 and Chang'e mission .... and they look very good!

Sure they are very useful! It will be even better if they manage to fit the data to modeled circulation of the lunar magma ocean that was formed posterior to the "Theia" body collision with Earth. The collision was the cause of the magma ocean in the first place. The question now is how this circulation pattern of the lava-moon "froze" in time upon phase transition to solid. Because, what crystallizes last in sequence, is more rich in "incompatible" with the crystal structure, elements, we might combine data+models to predict their location. Those incompatible tracers are mainly radioactively decaying elements that produce heat (google publications about lunar KREEP elements (potassium (K), rare earth elements(REE), and phosphorus(P)). By knowing where the KREEP is: - we know where to dig for them mining (if they are useful for something, eg. Phosphorus for plants to be grown on the Moon) - we avoid planning to build the future human colony on top of radioactives, of course. The hope is that the Moon, due to lack of plate tectonics, has preserved this "signature of the freezing sequence". Let's see.

thanks Nasia! very interesting comment

A sonification experiment taking data from ATLAS and translating it into music. The outcome was played at Montreux jazz fest, listen to the results in soundcloud https://soundcloud.com/sonification-quantizer. The way it works is "A tiny subset of collision data from the ATLAS Detector (in CERN, Switzerland) is being generated and streamed in real-time into a sonification engine built atop Python, Pure Data, Ableton, and IceCast." Code's in github https://github.com/cherston/Quantizer_public

"The latest idea comes from engineers at Glasgow's University of Strathclyde who suggest that a swarm of laser-wielding satellites could nudge Earth-bound asteroids off their collision course.... One proposed deflection technique involves using lasers to pulverize the surface of the asteroid, ejecting tiny bits of rock that would act as a propellant and push it onto a different course."

Physicists have simulated two universes colliding inside a metamaterial--  Now, this is cool (if it is true...)

Hm, they use more or less everything I don't especially like. They are nonmagnetic, so the relation materialGR is already rather weak. Usually, experimentalists prefer nonmagnetic media, since they are cheaper and broadband. At least the broadband is no argument here, since the frequency defines the "mass", which I find a rather strange point of view. And finally, they use strong anisotropy as a model of "time", which is rather problematic. Of course, the spatial direction with eps<0 appears in the wave equation with the same sign as time. But this does not mean that it behaves like time. But to teach material physicists that time is more than just a different sign in the wave equation seems to be as hopeless as to teach them that a black hole is more than something that absorbs all light... SIGHHH

Luzi I miss you ...

Theorists expect that positronium, a sort of 'atom' consisting of an electron and an anti-electron, can be used to make a powerful gamma-ray laser. Scientists now report detailed calculations of the dynamics of a positronium BEC. This work is the first to account for effects of collisions between different positronium species.

Can we have one?

They say they create 2 GeV electrons in a very small setup. However the laser they use is more than 10 meters in length. Still a really nice result.

Compared to a 27km circumference this is major achievement and it is indeed already foreseen that future colliders will include this technology as beam fillers and pre-accelerators at some point. The technique is quite elegant and a lot more energy efficient. Nevertheless, there are also thoughts that future particle colliders might actually go towards space and study collisions orginating from extremely energetic cosmic particles

no Higgs boson before 2013... and a replacement of 10,000 superconducting magnet connections ! Reminds me of the the gravitational detectors... no detection before an upgrade in 2013...! There are the big announcements to make the cash flow... and reality !

Higgs is almost 81, so he should better invest in his health if he wants the Nobel prize... But who cares, it's another 5 years window where high-energy theorists can produce nonsense with no experimental evidence. They should be happy!

Laskar does it again.... any comment, Pacome? :-)

Instead of classifying galaxies (image analysis), this new project asks the public to try to recreate collisions

From the section Science & Environment Scientists are claiming a stunning discovery in their quest to fully understand gravity. They have observed the warping of space-time generated by the collision of two black holes more than a billion light-years from Earth.

Collisionless electrostatic shocks (CES) are the dominant process in heating a plasma when using high power lasers. It turns out that ion-ion collisions actually only play a small role. The ability to create small regions of very high ion energy density on time scales shorter than that of hydrodynamic expansion will be of interest in attempts to understand the processes involved in inertial confinement fusion.