Group items tagged

"Row over 'torture' on French TV "

Suggestion for new format of ACT meetings. What would make this experiment scientifically relevant and not just a show?

Free software or a marketing move?

They have all the weight they need to pull this through. I'm dreaming of a day in which they will switch all Youtube videos to WebM, with all the Apple devices becoming useless to watch Internet video :) And Steve Jobs struggling to explain why, after wearing the mantle of open standards in the whole Flash vs HTML5 thing, he's now pushing H.264 against WebM... Anyway, in my view the less encumbered formats around the best for everyone's freedom.

You guys could like this....

how the spider silk gets so strong ...

C'mon Leopold! It is obvious from the title.

:-)

an additional investment of €50 billion in energy technology research will be needed over the next 10 years. This means almost tripling the annual investment in the European Union, from €3 to €8 billion

this is the type of really important research !!

May be interesting for the Tallha proposal of grabbing solar cells with thin wires to avoid the common illumination reduction by the contacts.

An ACT classical subject

additional info: http://en.wikipedia.org/wiki/Himba_people#Exceptional_color_perception

Yeah that's interesting stuff... We have one prof in the lab who used to do some research related exactly to this (http://www.tech.plym.ac.uk/socce/staff/tonybelpaeme/research.html). Similar question (i.e. if/how language is involved in the formation of a concept) is also valid for numbers, see for instance this recent story: http://www.newscientist.com/article/dn20095-without-language-numbers-make-no-sense.html

The scientific rationale behind it is that at km-depth there could be a) water resources (which could support a biosphere) and b) understand the formation of Mars. I would argue that an efficient drilling (robot) is also valuable for possible developing underground habitation (caves) at some point. This paper mentions two drilling concepts, but we could come up with many more (bio-inspired) probably. Daniel already came up with a nice one.. microwave drilling Also, the NASA InSight probe to Mars in 2016 is using a DLR-designed 'Mole' drill that is designed to reach a depth of... 5 meters

In this case I was thinking more about a smaller and controlled digging effort.. not ablating a football field sized hole

Nice one! plenty of examples in nature for this

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 .

Scientists at MIT have traced 13 billion years of galaxy evolution, from shortly after the Big Bang to the present day. Their simulation, named Illustris, captures both the massive scale of the Universe and the intriguing variety of galaxies - something previous modelers have struggled to do. It produces a Universe that looks remarkably similar to what we see through our telescopes, giving us greater confidence in our understanding of the Universe, from the laws of physics to our theories about galaxy formation. "Simulation is the future of innovation"

Astronomers have observed up to three newborn planets evolving from a disk of gas and dust particles circling a distant Sun-like star. While 1,900 planets have been discovered outside our solar system, these are the first to be seen that are still forming.

"Over the past couple of decades, the research literature has filled up with endless new nature-based metaphors for algorithms. You can find algorithms based on the behaviour of cuckoos, bees, bats, cats, wolves, galaxy formation and black holes. (...) All researchers have been doing is wasting time on developing new approaches that are probably little better than existing ones. And the language of each metaphor then invades the literature, distracting people from using the already sufficiently expressive terminology of mathematics and, above all, working together to find the best way forward." The golden era of fireworks-like algorithm is about to end

Lies, lies, all lies. They will never go away. Papers need to be published.