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Beniamino Abis

Wanted: Volunteers for Yearlong Mock Mars Mission in Canadian Arctic - 2 views

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    Mars Society, which advocates for manned exploration of the Red Planet, has released its requirements for the six volunteers who will be expected to spend 12 months at the society's Flashline Mars Arctic Research Station on Canada's Devon Island, which is about 1,450 kilometers from the North Pole, beginning in July 2014. Crewmembers will spend most of their time doing science, studying things such as carbon release from the permafrost and human performance in extreme conditions. If they want to go outside their base, they'll have to wear a spacesuit. If something breaks, they're the ones who are going to have to fix it.
Thijs Versloot

Concordia calling #ESA - 4 views

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    Are you a team player who is unafraid of long isolation? Do you have a medical degree and a healthy love of extremes? ESA is offering the chance of a lifetime to run space experiments in one of the world's most isolated places: Concordia research station in Antarctica.
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    One engineer YGT has already reserved his position to go there for maintaining infrastructure, the coming austral winter. Apparent science contribution: low, experience of a lifetime : affirmative!
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    "team player who is unafraid of long isolation" LOL
jcunha

Silicon Valley celebrates Moore's Law 50 years anniversary - 2 views

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    A bit late, but it is very interesting and instructive to listen to Gordon Moore's words "It almost doubled every year (...) so I said in the next 10 years it's going to continue to double every year, we are going to go from 16 components on a chip to 16 000. Pretty wild extrapolation!". This extrapolation (exponential with only 5 initial points) is now well-known and is one of the things that changed the World, it is pretty amazing how this "wild" futuristic vision came true.
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    A great source is also the blog from Chris Mack (http://life.lithoguru.com/?p=451) who is a semicon pioneer and publisher of many books on the subject. He wrote an article for IEEE Spectrum on Moore's law and its future. Find it here, http://spectrum.ieee.org/semiconductors/processors/the-multiple-lives-of-moores-law
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    Whenever I think about moore's law and extrapolating like that I end up back at this xkcd comic https://xkcd.com/605/
Thijs Versloot

Solar singlet fission bends the laws of physics to boost solar power efficiency by 30% ... - 2 views

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    Chemists at UCR have found a way of turning a single photon into two excitons, by a process known as singlet fission. By doubling the yield of excitons in a solar cell, you theoretically double the number of electrons produced and could lead to having a max theoretical efficiency of 60% or more in an (organic) solar cell See also DOI: 10.1021/jz500676c - "Singlet Fission: From Coherences to Kinetics"
Thijs Versloot

Extremely durable hydrophobic ceramics - 4 views

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    this is very interesting - we should speak to some colleagues here about it, e.g. in the melissa project ....
Beniamino Abis

Laser-Plasma Particle Accelerator - 1 views

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    Can we have one?
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    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.
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    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
jcunha

Nature: Spawning rings of exceptional points out of Dirac cones - 3 views

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    Dirac cones, a band-structure of two cones touching each other, are the key to understand graphene exceptional properties. They also appear in the theory of photon waveguides and atoms in optical lattices. In here, the study of a Dirac cone deformation in an open system (a system that is perturbed by external agents) lead to the deformation of the Dirac cone, meaning a change in the fundamental properties of the system. This change is such that strange phenomena such as unidirectional transmission or reflection or lasers with single mode (really single) operation can be achieved. Proved experimentally in photonic crystals. New way for extremely pure lasers?
jcunha

Chemical analysis in Earth and Space via Raman Spectroscopy - 2 views

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    "A new lightweight, energy-efficient tool for analyzing a material's chemical makeup could improve the detection abilities of various technologies, ranging from bomb-detecting drones to space rovers searching for signs of life". Raman Spectroscopy is about measuring vibrational modes in molecules. This vibrational modes are in the meV typically, turning Raman Spectroscopy into a high precision technique. This impressive work shows a new technique based on the use of optical fibers coupled to photomultipliers allowing its use, author's word, in extreme conditions such as unmanned aircraft vehicles (UAVs) and Mars/Moon rovers.
Dario Izzo

Extreme strength observed in limpet teeth | Journal of The Royal Society Interface - 3 views

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    stronger than steel - small teeth of snail like creature ...
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    According to a BBC news article it's actually stronger than Kevlar...
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    The spider silk is no longer the toughest natural material around.
LeopoldS

PLoS Biology: Extreme Endurance Migration: What Is the Limit to Non-Stop Flight? - 1 views

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    the Alaskan bar-tailed godwit (Limosa lapponica baueri) (Figure 1), makes its eight-day, 11,000-km autumn migration from Alaska to New Zealand in one step, with no stopovers to rest or refuel. This roughly doubles the previous maximum direct flight distance in birds, challenging experts to square this remarkable marathon migration with our understanding of aerodynamic theory and endurance physiology.
jmlloren

Exotic matter : Insight : Nature - 5 views

shared by jmlloren on 03 Aug 10 - Cached
LeopoldS liked it
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    Trends in materials and condensed matter. Check out the topological insulators. amazing field.
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    Aparently very interesting, will it survive the short hype? Relevant work describing mirror charges of topological insulators and the classical boundary conditions were done by Ismo and Ari. But the two communities don't know each other and so they are never cited. Also a way to produce new things...
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    Thanks for noticing! Indeed, I had no idea that Ari (don't know Ismo) was involved in the field. Was it before Kane's proposal or more recently? What I mostly like is that semiconductors are good candidates for 3D TI, however I got lost in the quantum field jargon. Yesterday, I got a headache trying to follow the Majorana fermions, the merons, skyrnions, axions, and so on. Luzi, are all these things familiar to you?
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    Ismo Lindell described in the early 90's the mirror charge of what is now called topological insulator. He says that similar results were obtained already at the beginning of the 20th century... Ismo Lindell and Ari Sihvola in the recent years discussed engineering aspects of PEMCs (perfect electro-megnetic conductors,) which are more or less classical analogues of topological insulators. Fundamental aspects of PEMCs are well knwon in high-energy physics for a long time, recent works are mainly due to Friedrich Hehl and Yuri Obukhov. All these works are purely classical, so there is no charge quantisation, no considerations of electron spin etc. About Majorana fermions: yes, I spent several years of research on that topic. Axions: a topological state, of course, trivial :-) Also merons and skyrnions are topological states, but I'm less familiar with them.
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    "Non-Abelian systems1, 2 contain composite particles that are neither fermions nor bosons and have a quantum statistics that is far richer than that offered by the fermion-boson dichotomy. The presence of such quasiparticles manifests itself in two remarkable ways. First, it leads to a degeneracy of the ground state that is not based on simple symmetry considerations and is robust against perturbations and interactions with the environment. Second, an interchange of two quasiparticles does not merely multiply the wavefunction by a sign, as is the case for fermions and bosons. Rather, it takes the system from one ground state to another. If a series of interchanges is made, the final state of the system will depend on the order in which these interchanges are being carried out, in sharp contrast to what happens when similar operations are performed on identical fermions or bosons." wow, this paper by Stern reads really weired ... any of you ever looked into this?
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    C'mon Leopold, it's as trivial as the topological states, AKA axions! Regarding the question, not me!
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    just looked up the wikipedia entry on axions .... at least they have some creativity in names giving: "In supersymmetric theories the axion has both a scalar and a fermionic superpartner. The fermionic superpartner of the axion is called the axino, the scalar superpartner is called the saxion. In some models, the saxion is the dilaton. They are all bundled up in a chiral superfield. The axino has been predicted to be the lightest supersymmetric particle in such a model.[24] In part due to this property, it is considered a candidate for the composition of dark matter.[25]"
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    Thank's Leopold. Sorry Luzi for being ironic concerning the triviality of the axions. Now, Leo confirmed me that indeed is a trivial matter. I have problems with models where EVERYTHING is involved.
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    Well, that's the theory of everything, isn't it?? Seriously: I don't think that theoretically there is a lot of new stuff here. Topological aspects of (non-Abelian) theories became extremely popular in the context of string theory. The reason is very simple: topological theories are much simpler than "normal" and since string theory anyway is far too complicated to be solved, people just consider purely topological theories, then claiming that this has something to do with the real world, which of course is plainly wrong. So what I think is new about these topological insulators are the claims that one can actually fabricate a material which more or less accurately mimics a topological theory and that these materials are of practical use. Still, they are a little bit the poor man's version of the topological theories fundamental physicists like to look at since electrdynamics is an Abelian theory.
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    I have the feeling, not the knowledge, that you are right. However, I think that the implications of this light quantum field effects are great. The fact of being able to sustain two currents polarized in spin is a technological breakthrough.
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    not sure how much I can contribute to your apparently educated debate here but if I remember well from my work for the master, these non-Abelian theories were all but "simple" as Luzi puts it ... and from a different perspective: to me the whole thing of being able to describe such non-Abelian systems nicely indicates that they should in one way or another also have some appearance in Nature (would be very surprised if not) - though this is of course no argument that makes string theory any better or closer to what Luzi called reality ....
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    Well, electrodynamics remains an Abelian theory. From the theoretical point of view this is less interesting than non-Abelian ones, since in 4D the fibre bundle of a U(1) theory is trivial (great buzz words, eh!) But in topological insulators the point of view is slightly different since one always has the insulator (topological theory), its surrounding (propagating theory) and most importantly the interface between the two. This is a new situation that people from field and string theory were not really interested in.
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    guys... how would you explain this to your gran mothers?
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    *you* tried *your* best .... ??
Luís F. Simões

Inferring individual rules from collective behavior - 2 views

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    "We fit data to zonal interaction models and characterize which individual interaction forces suffice to explain observed spatial patterns." You can get the paper from the first author's website: http://people.stfx.ca/rlukeman/research.htm
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    PNAS? Didnt strike me as sth very new though... We should refer to it in the roots study though: "Social organisms form striking aggregation patterns, displaying cohesion, polarization, and collective intelligence. Determining how they do so in nature is challenging; a plethora of simulation studies displaying life-like swarm behavior lack rigorous comparison with actual data because collecting field data of sufficient quality has been a bottleneck." For roots it is NO bottleneck :) Tobias was right :)
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    Here they assume all relevant variables influencing behaviour are being observed. Namely, the relative positions and orientations of all ducks in the swarm. So, they make movies of the swarm's movements, process them, and them fit the models to that data. In the roots, though we can observe the complete final structure, or even obtain time-lapse movies showing how that structure came out to be, getting the measurements of all relevant soil variables (nitrogen, phosphorus, ...) throughout the soil, and over time, would be extremely difficult. So I guess a replication of the kind of work they did, but for the roots, would be hard. Nice reference though.
Francesco Biscani

The End Of Gravity As a Fundamental Force - 6 views

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    "At a symposium at the Dutch Spinoza-instituut on 8 December, 2009, string theorist Erik Verlinde introduced a theory that derives Newton's classical mechanics. In his theory, gravity exists because of a difference in concentration of information in the empty space between two masses and its surroundings. He does not consider gravity as fundamental, but as an emergent phenomenon that arises from a deeper microscropic reality. A relativistic extension of his argument leads directly to Einstein's equations."
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    Diffcult for me to fully understand / believe in the holographic principle at macroscopical scales ... potentially it looks though as a revolutionary idea.....
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    never heard about it... seems interesting. At first sight it seems that it is based on fundamental principle that could lead to a new phenomenology, so that could be tested. Perhaps Luzi knows more about this ? Did we ever work on this concept ?
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    The paper is quite long and I don't have the time right now to read it in detail. Just a few comments: * We (ACT) definitely never did anything in this direction? But: is there a new phenomenology? I'm not sure, if the aim is just to get Einstein's theory as emergent theory, then GR should not change (or only change in extreme conditions.) * Emergent gravity is not new, also Erik admits that. The claim to have found a solution appears quite frequently, but most proposals actually are not emergent at all. At least, I have the impression that Erik is aware of the relevant steps to be performed. * It's very difficult to judge from a short glance at the paper, up to which point the claims are serious and where it just starts to be advertisments. Section 6 is pretty much a collection of self-praise. * Most importantly: I don't understand how exactly space and time should be emergent. I think it's not new to observe that space is related to special canonical variables in thermodynamics. If anybody can see anything "emergent" in the first paragraphs of section 3, then please explain me. For me, this is not emergent space, but space introduced with a "sledge hammer." Time anyway seems to be a precondition, else there is nothing like energy and nothing like dynamics. * Finally, holography appears to be a precondition, to my knowledge no proof exists that normal (non-supersymmetric, non-stringy, non-whatever) GR has a holographic dual.
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    Update: meanwhile I understood roughly what this should be about. It's well known that BH physics follow the laws of theormodynamics, suggesting the existence of underlying microstates. But if this is true, shouldn't the gravitational force then be emergent from these microstates in the same way as any theromdynamical effect is emergent from the behavior of its constituents (e.g. a gas)? If this can be prooven, then indeed gravity is emergent. Problem: one has to proof that *any* configuration in GR may be interpreted as thermodynamical, not just BHs. That's probably where holography comes into the play. To me this smells pretty much like N=4 SYM vs. QCD. The former is not QCD, but can be solved, so all stringy people study just that one and claim to learn something about QCD. Here, we look at holographic models, GR is not holographic, but who cares... Engineering problems...
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    is there any experimental or observational evidence that points to this "solution"?
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    Are you joking??? :D
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    I was a bit fast to say it could be tested... apparently we don't even know a theory that is holographic, perhaps a string theory (see http://arxiv.org/abs/hep-th/9409089v2). So very far from any test...
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    Luzi, I miss you!!!
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    Leo, do you mean you liked my comment on your question more than Pacome's? Well, the ACT has to evolve and fledge, so no bullshitting anymore, but serious and calculating answers... :-) Sorry Pacome, nothing against you!! I just LOVE this Diigo because it gives me the opportunity for a happy revival of my ACT mood.
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    haha, today would have been great to show your mood... we had a talk on the connection between mind and matter !!
pacome delva

New pulsars could net gravitational waves - 0 views

  • One of the physicists working on interferometers, Jim Hough of the University of Glasgow, agrees that pulsar timing is a good way to search for gravity waves at extremely low frequencies. He believes that if astronomers observe 20 pulsars with a timing precision of better than 100 nanoseconds for five years then they would "have a very good possibility of observing gravitational-wave signals."
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    Again an article about the gravitational waves detected with pulsars. However its a bit fast conclusion, cause i don't know any serious article that draw this conclusion for sure...
Luís F. Simões

Bitcoin P2P Currency: The Most Dangerous Project We've Ever Seen - 10 views

  • After month of research and discovery, we’ve learned the following:1. Bitcoin is a technologically sound project.2. Bitcoin is unstoppable without end-user prosecution.3. Bitcoin is the most dangerous open-source project ever created.4. Bitcoin may be the most dangerous technological project since the internet itself.5. Bitcoin is a political statement by technotarians (technological libertarians).*6. Bitcoins will change the world unless governments ban them with harsh penalties.
  • The benefits of a currency like this:a) Your coins can’t be frozen (like a Paypal account can be)b) Your coins can’t be trackedc) Your coins can’t be taxedd) Transaction costs are extremely low (sorry credit card companies)
  • An individual with the name -- or perhaps handle -- of Satoshi Nakamoto first wrote about bitcoins in a paper called Bitcoin: A Peer-to-Peer Electronic Cash System.
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  • * We made this term up to describe the “good people” of the internet who believe in the fundamental rights of individuals to be free, have free speech, fight hypocrisy and stand behind logic, technology and science over religion, political structure and tradition. These are the people who build and support things like Wikileaks, Anonymous, Linux and Wikipedia. They think that people can, and should, govern themselves. They are against external forms of control such as DRM, laws that are bought and sold by lobbyists, and religions like Scientology. They include splinter groups that enforce these ideals in the form of hacktivism, such as the takedown of the Sony Playstation Network after Sony tried to prosecute a hacker for unlocking its console.
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    Sounds good!
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    wow it's frigthening! it's the dream of every anarchist, every drug, arm, human dealer! the world made as a global fiscal paradise... the idea is clever however it will not replace real money because 1 - no one will build a fortune on bitcoin if a technological breakthrough can ruin them 2 - government never allowed parallel money to flourish on their territory, so it will be almost impossible to change bitcoin against euros or dollars
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    interesting stuff anyone read cryptonomicon by neal stephenson? similar theme.
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    :) yes. One of the comments on reddit was precisely drawing the parallels with Neal Stephenson's Snowcrash / Diamond Age / Cryptonomicon. Interesting stuff indeed. It has a lot of potential for misuse, but also opens up new possibilities. We've discussed recently how emerging technologies will drive social change. Whether it's the likes of NSA / CIA who will benefit the most from the Twitters, Facebooks and so on, by gaining greater power for control, or whether individuals are being empowered to at least an identical degree. We saw last year VISA / PayPal censoring WikiLeaks... Well, here's a way for any individual to support such an organization, in a fully anonymous and uncontrollable way...
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    One of my colleagues has made a nice, short write-up about BitCoin: http://www.pds.ewi.tudelft.nl/~victor/bitcoin.html
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    very nice analysis indeed - thanks Tamas for sharing it!
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    mmm I'm not an expert but it seemed to me that, even if these criticisms are true, there is one fundamental difference between the money you exchange on internet via your bank, and bitcoins. The first one is virtual money and the second one aims at being real, physical, money, even if digital, in the same way as banknotes, coins, or gold.
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    An algorithm wanna-be central bank issuing untraceable tax free money between internet users? not more likely than the end of the world supposed to take place tomorrow, in my opinion. Algorithms don't usually assault women though !:P
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    well, most money is anyway just virtual and only based on expectations and trust ... (see e.g. http://en.wikipedia.org/wiki/Money_supply) and thus if people trust that this "money" has some value in the sense that they can get something of value to them in exchange, then not much more is needed it seems to me ...
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    @Leopold: ok let's use the rigth words then. Bitcoin aim at being a currency ("physical objects generally accepted as a medium of exchange" from wikipedia), different than the "demand deposit". In the article proposed by Tamas he compares what cannot be compared (currencies, demand deposits and their mean of exchange). The interesting question is wether one can create a digital currency which is too difficult to counterfeit. As far as I know, there is no existing digital currency except this bitcoins (and maybe the currencies from games as second life and others, but which are of limited use in real world).
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    well of course money is trust, and even more loans and credit and even more stock and bond markets. It all represents trust and expectations. However since the first banks 500 years ago and the first loans etc. etc., and as well the fact that bonds and currencies bring down whole countries (Greece lately), and are mainly controlled by large financial centres and (central) banks, banks have always been on the winning side no matter what and that isn't going to change easily. So if you are talking about these new currencies it would be a new era, not just a new currency. So should Greece convert its debt to bitcoins ;P ?
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    well, from 1936 to 1993 the central bank of france was owned by the state and was supposed to serve the general interest...
LeopoldS

SVS Animation 3832 - Extreme Solar Eruption Caught on Camera - 1 views

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    Nice!!
LeopoldS

TEDxNASA Silicon Valley - Extreme Green 2011 - 1 views

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    to be followed ....
LeopoldS

BBC News - Speed-of-light experiments give baffling result at Cern - 5 views

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    Sante, Luzi have a look at this???!!!
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    and here's the xkcd on it: http://xkcd.com/955/
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    And here's the arXiv paper http://arxiv.org/abs/1109.4897 Serious? Difficult to say. I'm theorist and can't really rate their measurement techniques. Certainly be cautious, mostly such things disappear faster than they appeared.
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    it took them 3 years to "appear"!
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    Leo, you mean that they measured 3 years? That's not a point to criticize: since the only interaction of neutrinos with matter is the Weak Interaction (which is indeed very, very weak), it is extremely hard to get a reasonable statistic. By the same reason, it's essentially impossible to shield the experiment from the background. And this background (solar neutrinos, cosmic radiation neutrinos) is huge.
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    for sure a result to be taken seriously. It makes a buzz in my lab... but always be cautious with this kind of declaration, that hugely violates all physics we know and even most of the reasonable alternative theories... Remember the Pionneer anomaly for which it took almost ten years to set up that finally its a thermal effect.
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