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Thijs Versloot

Time 'Emerges' from #Quantum Entanglement #arXiv - 1 views

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    Time is an emergent phenomenon that is a side effect of quantum entanglement, say physicists. And they have the first exprimental results to prove it
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    I always feel like people make too big a deal out of entanglement. In my opInion it is just a combInation of a conserved quantity and an Initial lack of knowledge. ImagIne that I had a machIne that always creates one blue and one red pIng-pong ball at the same time (|b > and |r > respectively). The machIne now puts both balls Into identical packages (so I cannot observe them) and one of the packages is sent to Tokio. I did not know which ball was sent to Tokio and which stayed with me - they are In a superposition (|br >+|rb >), meanIng that either the blue ball is with me and the red one In Tokio or vice versa - they are entangled. So far no magic has happened. Now I call my friend In Tokio who got the ball: "What color was the ball you received In that package?" He replies: "The ball that I got was blue. Why did you send me ball In the first place?" Now, the fact that he told me makes the superpositon wavefunction collapse (yes, that is what the Copenhagen Interpretation would tell us). As a result I know without openIng my box that it contaIns a red ball. But this is really because there is an underlyIng conservation law and because now I know the other state. I don't see how just lookIng at the conserved quantity I am In a timeless state outside of the 'universe' - this is just one way of InterpretIng it. By the way, the wave function for my box with the undetermIned ball does not collapse when the other ball is observed by my friend In Tokio. Only when he tells me does the wavefunction collapse - he did not even know that I had a complementary ball. On the other hand if he knew about the way the experiment was conducted then he would have known that I had to have a red ball - the wavefunction collapses as soon as he observed his ball. For him it is determIned that my ball must be red. For me however the superposition is Intact until he tells me. ;-)
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    Sorry, Johannes, you just develop a simple hidden-parameters theory and it's experimentally proven that these don't work. Entangeled states are neither the blue nor the red ball they are really bluered (or redblue) till the point the measurement is done.
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    Hm, to me this looks like a bad joke... The "emergent time" concept used is still the old proposal by Page and Whotters where time emerges from something fundamentally unobservable (the wave function of the Universe). That's as good as claiming that time emerges from God. If I understand correctly, the paper now deals with the situation where a finite system is taken as "Mini-Universe" and the experimentalist in the lab can play "God of the Mini-Universe". This works, of course, but it doesn't really tell us anything about emergent time, does it?
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    Actually, it has not been proven conclusively that hidden variable theories don' work - although this is the opinion of most physicists these days. But a non-local hidden variable would still be allowed - I don't see why that could not be equivalent to a conserved quantity within the system. As far as the two balls go it is fine to say they are undetermined instead of saying they are in bluered or redblue state - for all intents and purposes it does not affect us (because if it would the wavefunction would have collapsed) so we can't say anything about it in the first place.
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    Non-local hidden variables may work, but in my opinion they don't add anything to the picture. The (at least to non-physicists) contraintuitive fact that there cannot be a variable that determines ab initio the color of the ball going to Tokio will remain (in your example this may not even be true since the example is too simple...).
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    I guess I tentatively agree with you on both points. in the end there might anyway be surprisingly little overlap between the way that we describe what nature does and HOW it does it... :-D
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    Congratulations! 100% agree.
Luís F. Simões

NASA Goddard to Auction off Patents for Automated Software Code Generation - 0 views

  • The technology was originally developed to handle coding of control code for spacecraft swarms, but it is broadly applicable to any commercial application where rule-based systems development is used.
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    This is related to the "Verified Software" item in NewScientist's list of ideas that will change science. At the link below you'll find the text of the patents being auctioned: http://icapoceantomo.com/item-for-sale/exclusive-license-related-improved-methodology-formally-developing-control-systems :) Patent #7,627,538 ("Swarm autonomic agents with self-destruct capability") makes for quite an interesting read: "This invention relates generally to artificial intelligence and, more particularly, to architecture for collective interactions between autonomous entities." "in some embodiments, an evolvable synthetic neural system is operably coupled to one or more evolvable synthetic neural systems in a hierarchy." "in yet another aspect, an autonomous nanotechnology swarm may comprise a plurality of workers composed of self-similar autonomic components that are arranged to perform individual tasks in furtherance of a desired objective." "in still yet another aspect, a process to construct an environment to satisfy increasingly demanding external requirements may include instantiating an embryonic evolvable neural interface and evolving the embryonic evolvable neural interface towards complex complete connectivity." "in some embodiments, NBF 500 also includes genetic algorithms (GA) 504 at each interface between autonomic components. The GAs 504 may modify the intra-ENI 202 to satisfy requirements of the SALs 502 during learning, task execution or impairment of other subsystems."
Alexander Wittig

Attack on the pentagon results in discovery of new mathematical tile - 2 views

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    In the world of mathematical tilIng, news doesn't come bigger than this. In the world of bathroom tilIng - I bet they're Interested too. If you can cover a flat surface usIng only identical copies of the same shape leavIng neither gaps nor overlaps, then that shape is said to tile the plane. Also only mathematicians can put the words "Pentagon", "attack", and "plane" In the same sentence...
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    I especially love this part of the story: "The hunt to find and classify the pentagons that can tile the plane has been a century-long mathematical quest, begun by the German mathematician Karl Reinhardt, who in 1918 discovered five types of pentagon that do tile the plane. (To clarify, he did not find five single pentagons. He discovered five classes of pentagon that can each be described by an equation. For the curious, the equations are here. And for further clarification, we are talking about convex pentagons, which are most people's understanding of a pentagon in that every corner sticks out.) Most people assumed Reinhardt had the complete list until half a century later in 1968 when R. B. Kershner found three more. Richard James brought the number of types of pentagonal tile up to nine in 1975. That same year an unlikely mathematical pioneer entered the fray: Marjorie Rice, a San Diego housewife in her 50s, who had read about James' discovery in Scientific American. An amateur mathematician, Rice developed her own notation and method and over the next few years discovered another four types of pentagon that tile the plane. in 1985 Rolf Stein found a fourteenth. Way to go!"
LeopoldS

Schumpeter: More than just a game | The Economist - 3 views

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    remember the discussion I tried to trigger in the team a few weeks ago ...
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    main quote I take from the article: "gamification is really a cover for cynically exploiting human psychology for profit"
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    I would say that it applies to management in general :-)
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    which is exactly why it will never work .... and surprisingly "managers" fail to understand this very simple fact.
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    ... "gamification is really a cover for cynically exploiting human psychology for profit" --> "Why Are Half a Million People Poking This Giant Cube?" http://www.wired.com/gamelife/2012/11/curiosity/
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    I think the "essence" of the game is its uselessness... workers need exactly the inverse, to find a meaning in what they do !
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    I love the linked article provided by Johannes! It expresses very elegantly why I still fail to understand even extremely smart and busy people in my view apparently waiting their time in playing computer games - but I recognise that there is something in games that we apparently need / gives us something we cherish .... "in fact, half a million players so far have registered to help destroy the 64 billion tiny blocks that compose that one gigantic cube, all working in tandem toward a singular goal: discovering the secret that Curiosity's creator says awaits one lucky player inside. That's right: After millions of man-hours of work, only one player will ever see the center of the cube. Curiosity is the first release from 22Cans, an independent game studio founded earlier this year by Peter Molyneux, a longtime game designer known for ambitious projects like Populous, Black & White and Fable. Players can carve important messages (or shameless self-promotion) onto the face of the cube as they whittle it to nothing. Image: Wired Molyneux is equally famous for his tendency to overpromise and under-deliver on his games. in 2008, he said that his upcoming game would be "such a significant scientific achievement that it will be on the cover of Wired." That game turned out to be Milo & Kate, a Kinect tech demo that went nowhere and was canceled. Following this, Molyneux left Microsoft to go indie and form 22Cans. Not held back by the past, the Molyneux hype train is going full speed ahead with Curiosity, which the studio grandiosely promises will be merely the first of 22 similar "experiments." Somehow, it is wildly popular. The biggest challenge facing players of Curiosity isn't how to blast through the 2,000 layers of the cube, but rather successfully connecting to 22Cans' servers. So many players are attempting to log in that the server cannot handle it. Some players go for utter efficiency, tapping rapidly to rack up combo multipliers and get more
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    why are video games so much different than collecting stamps or spotting birds or planes ? One could say they are all just hobbies
Dario Izzo

Critique of 'Debunking the climate hiatus', by Rajaratnam, Romano, Tsiang, and Diffenbaugh | Radford Neal's blog - 8 views

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    Hilarious critique to a quite important paper from Stanford trying to push the agenda of global warming .... "You might therefore be surprised that, as I will discuss below, this paper is completely wrong. Nothing in it is correct. It fails in every imaginable respect."
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    To quote Francisco "If at first you don't succeed, use another statistical test" A wiser man shall never walk the earth
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    why is this just put on a blog and not published properly?
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    If you read the comments it's because the guy doesn't want to put in the effort. Also because I suspect the politics behind climate science favor only a particular kind of result.
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    just a footnote here, that climate warming aspect is not derived by an agenda of presenting the world with evil. If one looks at big journals with high outreach, it is not uncommon to find articles promoting climate warming as something not bringing the doom that extremists are promoting with marketing strategies. Here is a recent article in Science: http://www.ncbi.nlm.nih.gov/pubmed/26612836 Science's role is to look at the phenomenon and notice what is observed. And here is one saying that the acidification of the ocean due to increase of CO2 (observed phenomenon) is not advancing destructively for coccolithophores (a key type of plankton that builds its shell out of carbonates), as we were expecting, but rather fertilises them! Good news in principle! It could be as well argued from the more sceptics with high "doubting-inertia" that 'It could be because CO2 is not rising in the first place'', but one must not forget that one can doubt the global increase in T with statistical analyses, because it is a complex variable, but at least not the CO2 increase compared to preindustrial levels. in either case : case 1: agenda for 'the world is warming' => - Put random big energy company here- sells renewable energies case 2: agenda for 'the world is fine' => - Put random big energy company here - sells oil as usual The fact that in both cases someone is going to win profits, does not correllate (still not an adequate statistical test found for it?) with the fact that the science needs to be more and more scrutinised. The blog of the Statistics Professor in Univ.Toronto looks interesting approach (I have not understood all the details) and the paper above is from JPL authors, among others.
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 !!
Nicholas Lan

Betting on Green - 5 views

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    breakthroughs vs. accelerated deployment in climate change mitigation technologies.
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    interesting guy indeed ... "Forget today's green technologies like electric cars, wind turbines, solar cells and smart grids, in other words. None meets what Mr Khosla calls the "Chindia price"-the price at which people in China and india will buy them without a subsidy. "Everything's a toy until it reaches that point," he says. I also like this one since its a bit like ACT topic selection: ""I am only interested in technologies that have a 90% chance of failure but, if they do succeed, would change the infrastructure of society in some radical way," he says." should we propose SPS to him ? :-)
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    one more: ""I never compute returns. If you start forecasting cash flows, you lose innovation, you lose instinct. You average yourself down to mediocrity." "I've had many more failures than successes in my life," admits Mr Khosla. "My willingness to fail gives me the ability to succeed."
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    indeed. puts me in mind of the often reinvented private ACT idea. actually there's a bunch of interesting looking articles on his website. http://www.khoslaventures.com/khosla/papers.html . No sps in the solar one as far as i can tell :) found this bit intriguing too in that, albeit presumably out of context, it doesn't make sense ""The solution to our energy problems is almost the exact opposite of what Khosla says," declares Joseph Romm, who is the editor of Climate Progress, an influential climate blog, and a senior fellow at the Centre for American Progress Action Fund, a think-tank. "Technology breakthroughs are unlikely to be the answer. Accelerated deployment of existing technologies will get you down the cost curve much more rapidly than a breakthrough."" found this seemingly not very well considered piece (to be fair a blog post) by the guy http://climateprogress.org/2010/07/02/is-anyone-more-incoherent-than-vinod-khosla/ . maybe he's written some more convincing stuff in this vein somewhere.
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    "Mr Khosla (...) is investing over $1 billion of his clients' money in black swans" Well, with his own money his approach might be a little different :-)
santecarloni

[1106.1470] Evidence for Time-Varying Nuclear Decay Rates: Experimental Results and Their Implications for New Physics - 2 views

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    Unexplained annual variations in nuclear decay rates have been reported in recent years by a number of groups. We show that data from these experiments exhibit not only variations in time related to Earth-Sun distance, but also periodicities attributable to solar rotation. Additionally, anomalous decay rates coincident in time with a series of solar flares in December 2006 also point to a solar influence on nuclear decay rates....
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    can we use space to make a smart experiment to solve this riddle? e.g. sending a decay detecter on a close solar orbit and one to Pluto and then compare decay rates? or a highly elliptical trajectory and compare during peri and apoapsis?
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    I think it could be possible. I need to look into the details. in fact it could probably be done already with the nuclear generators on the Voyager and Pioneer and other nuclear powered probes. That is if the data are precise enough...
LeopoldS

Global Innovation Commons - 4 views

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    nice initiative!
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    Any viral licence is a bad license...
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    I'm pretty confident I'm about to open a can of worms, but mind explaining why? :)
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    I am less worried about the can of worms ... actually eager to open it ... so why????
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    Well, the topic GPL vs other open-source licenses (e.g., BSD, MIT, etc.) is old as the internet and it has provided material for long and glorious flame wars. The executive summary is that the GPL license (the one used by Linux) is a license which imposes some restrictions on the way you are allowed to (re)use the code. Specifically, if you re-use or modify GPL code and re-distribute it, you are required to make it available again under the GPL license. It is called "viral" because once you use a bit of GPL code, you are required to make the whole application GPL - so in this sense GPL code replicates like a virus. On the other side of the spectrum, there are the so-called BSD-like licenses which have more relaxed requirements. Usually, the only obligation they impose is to acknowledge somewhere (e.g., in a README file) that you have used some BSD code and who wrote it (this is called "attribution clause"), but they do not require to re-distribute the whole application under the same license. GPL critics usually claim that the license is not really "free" because it does not allow you to do whatever you want with the code without restrictions. GPL proponents claim that the requirements imposed by the GPL are necessary to safeguard the freedom of the code, in order to avoid being able to re-use GPL code without giving anything back to the community (which the BSD license allow: early versions of Microsoft Windows, for instance, had the networking code basically copy-pasted from BSD-licensed versions of Unix). in my opinion (and this point is often brought up in the debates) the division pro/against GPL mirrors somehow the division between anti/pro anarchism. Anarchists claim that the only way to be really free is the absence of laws, while non-anarchist maintain that the only practical way to be free is to have laws (which by definition limit certain freedoms). So you can see how the topic can quickly become inflammatory :) GPL at the current time is used by aro
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    whoa, the comment got cut off. Anyway, I was just saying that at the present time the GPL license is used by around 65% of open source projects, including the Linux kernel, KDE, Samba, GCC, all the GNU utils, etc. The topic is much deeper than this brief summary, so if you are interested in it, Leopold, we can discuss it at length in another place.
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    Thanks for the record long comment - am sure that this is longest ever made to an ACT diigo post! On the topic, I would rather lean for the GPL license (which I also advocated for the Marek viewer programme we put on source forge btw), mainly because I don't trust that open source is by nature delivering a better product and thus will prevail but I still would like to succeed, which I am not sure it would if there were mainly BSD like licenses around. ... but clearly, this is an outsider talking :-)
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    btw: did not know the anarchist penchant of Marek :-)
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    Well, not going into the discussion about GPL/BSD, the viral license in this particular case in my view simply undermines the "clean and clear" motivations of the initiative authors - why should *they* be credited for using something they have no rights for? And I don't like viral licences because they prevent using things released under this licence to all those people who want to release their stuff under a different licence, thus limiting the usefulness of the stuff released on that licence :) BSD is not a perfect license too, it also had major flaws And I'm not an anarchist, lol
Ma Ru

Dark Matter or Black Hole Propulsion? - 1 views

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    Anyone out there still doing propulsion stuff? Two more papers just waiting to get busted... http://arxiv.org/abs/0908.1429v1 http://arxiv.org/abs/0908.1803
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    What an awful bunch of complete nonsense!!! But I don't think anybody wants to hear MY opinion on this...
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    wow, is this serious at all...!?
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    Are you joking?? The BH drive propses a BH with a lifetime of about an year, just 10^7 tons, peanuts!! Then you have to produce it, better not on Earth, so you do this in space, with a laser that produces an equivalent of 10^9 tons highly foucussed, even more peanuts!! Reasonable losses in the production process (probably 99,999%) are not yet taken into account. Engineering problems... :-) The DM drive is even better, they want to collect DM and compress it in a propulsion chamber. Very easy to collect and compress a gas of particles that traverse the Earth without any interaction. Perhaps if the walls of the chamber are made of artificial BHs?? Who knows??
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    WRONG!!! we are all just WAITING for your opINion on this ....!!!
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    well, yes my remark was ironic... I'm surprised they did a magazine on these concepts...! But the press is always waiting for sensational. They do not even wait for the work to be peer-reviewed now to make an article on it ! This is one of the bad sides of arxiv in my opinion. It's like a journalist that make an article with a copy-paste in wikipedia ! Anyway, this is of course complete bullsh..., and I would have laughed if I had read this in a sci-fi book... but in a "serious" article i'm crying... For the DM i do not agree with your remark Luzi. It's not dark energy they want to use. The DM is baryonic, it's dark just because it's cold so we don't see it by usual means. If you believe the in the standard model of cosmology, then the DM should be somewhere around the galaxies. But it's of course not uniformly distributed, so a DM engine would work (if at all...) only in the periphery of galaxies. It's already impossible to get there...
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    One reply to Pacome, though the discussion exceeds by far the relevance of the topic already. Baryonic DM is strictly limited by cosomology, if one believes in these models, of course. Anyway, even though most DM is cold, we are constantly bombarded by some DM particles that come together with cosmic radiation, solar wind etc. etc. If DM easily interacted with normal matter, we would have found it long ago. in the paper they consider DM as neutralinos, which are neither baryonic nor strongly or electromagnetically interacting.
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    well then I agree, how the fu.. they want to collect them !!!
Thijs Versloot

Quantum entanglement at ambient conditions in a macroscopic solid-state spin ensemble - 1 views

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    Quoted from one of the authors in a separate interview: "We know that the spin states of atomic nuclei associated with semiconductor defects have excellent quantum properties at room temperature," said Awschalom, Liew Family Professor in Molecular Engineering and a senior scientist at Argonne National Laboratory. "They are coherent, long-lived and controllable with photonics and electronics. Given these quantum 'pieces,' creating entangled quantum states seemed like an attainable goal." Bringing the quantum world to the macroscopic scale could see some interesting applications in sensors, or generally entanglement-enhanced applications.
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    They were previously working on the same concept in N-V centers in diamond (as a semiconductor). Here the advantage is that SiC could in principle be integrated with Si or Ge. Anyway its all about controlling coherence. in the next 10 years some breakthroughs are expected in the field of semiconductor spintronics, but quantum computing in this way lies still in the horizon
Dario Izzo

Check your country impact on science!!! - 8 views

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    Did you know that papers in space science are among the most quoted? Check how your country is doing .... you will be surprised :)
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    In terms of country based quotations ("Most scited countries") I cannot access space science, only Geosciences, Immunology, Material Science, and Psychiatry & Psychology. But when I first saw the list of countries at the left under "Impact In Science" I saw ArgentInia was on top, and USA was on last position. Yes, I was surprised, until I realised that is was just an alphabetical order. Did you see the same list?
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    scotland's a separate country. must be preparing for independence already. and it's highest percentage is for space science. crazy
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    Dajan, you need to click on the country you are interested in ....
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    Nooo, can't be THAT simple.
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    data a bit old .... newer data (but less well presented) at http://sciencewatch.com/ there you can also read: "The 20th century was largely dominated by the US as a major powerhouse of scientific research and innovation, with 40% of the papers indexed in the Web of Science fielded by US scientists in the 1990s. By 2009, that figure was down to 29%. The US now struggles to keep pace with increased output from Europe and Asia."
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    hottest space science paper in January 2012: Field: Space Science Article Title: Herschel Space Observatory An ESA facility for far-infrared and submillimetre astronomy Authors: Pilbratt, GL;Riedinger, JR;Passvogel, T;Crone, G;Doyle, D;Gageur, U;Heras, AM;Jewell, C;Metcalfe, L;Ott, S;Schmidt, M Journal: ASTRON ASTROPHYS, 518: art. no.-L1 JUL-AUG 2010 * ESTEC SRE SA, ESA Res & Sci Support Dept, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands. * ESTEC SRE SA, ESA Res & Sci Support Dept, NL-2201 AZ Noordwijk, Netherlands. * ESTEC SRE OA, ESA Sci Operat Dept, NL-2201 AZ Noordwijk, Netherlands. * ESTEC SRE P, ESA Sci Operat Dept, NL-2201 AZ Noordwijk, Netherlands. * ESOC OPS OAH, ESA Mission Operat Dept, D-64293 Darmstadt, Germany. * ESAC SRE OA, ESA Sci Operat Dept, Madrid 28691, Spain.
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    InterestIngly, Space Science is the only field In which my country has positive "Impact vs. world" value (even more InterestIngly as we don't even have a proper national space agency)...
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    this might also be an indication / point to an issue with their data concerning space science publications ... quite surprising indeed that all Europeans are doing so well in this field
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    Something should be wrong, for Spain I can read: Economics & Business 4.54 -28 Only minus 28!
LeopoldS

An optical lattice clock with accuracy and stability at the 10-18 level : Nature : Nature Publishing Group - 0 views

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    Progress in atomic, optical and quantum science1, 2 has led to rapid improvements in atomic clocks. At the same time, atomic clock research has helped to advance the frontiers of science, affecting both fundamental and applied research. The ability to control quantum states of individual atoms and photons is central to quantum information science and precision measurement, and optical clocks based on single ions have achieved the lowest systematic uncertainty of any frequency standard3, 4, 5. Although many-atom lattice clocks have shown advantages in measurement precision over trapped-ion clocks6, 7, their accuracy has remained 16 times worse8, 9, 10. Here we demonstrate a many-atom system that achieves an accuracy of 6.4 × 10−18, which is not only better than a single-ion-based clock, but also reduces the required measurement time by two orders of magnitude. By systematically evaluating all known sources of uncertainty, including in situ monitoring of the blackbody radiation environment, we improve the accuracy of optical lattice clocks by a factor of 22. This single clock has simultaneously achieved the best known performance in the key characteristics necessary for consideration as a primary standard-stability and accuracy. More stable and accurate atomic clocks will benefit a wide range of fields, such as the realization and distribution of SI units11, the search for time variation of fundamental constants12, clock-based geodesy13 and other precision tests of the fundamental laws of nature. This work also connects to the development of quantum sensors and many-body quantum state engineering14 (such as spin squeezing) to advance measurement precision beyond the standard quantum limit.
Dario Izzo

IPCC models getting mushy | Financial Post - 2 views

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    why am I not surprised .....
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    http://www.academia.edu/4210419/Can_climate_models_explain_the_recent_stagnation_in_global_warming A view of well-respected scientists on how to proceed from here, that was rejected from Nature. in any case, a long way to go...
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    unfortunately it's too early to cheer and burn more coal ... there is also a nice podcast associated to this paper from nature Recent global-warming hiatus tied to equatorial Pacific surface cooling Yu Kosaka & Shang-Ping Xie Nature 501, 403-407 (19 September 2013) doi:10.1038/nature12534 Received 18 June 2013 Accepted 08 August 2013 Published online 28 August 2013 Despite the continued increase in atmospheric greenhouse gas concentrations, the annual-mean global temperature has not risen in the twenty-first century1, 2, challenging the prevailing view that anthropogenic forcing causes climate warming. Various mechanisms have been proposed for this hiatus in global warming3, 4, 5, 6, but their relative importance has not been quantified, hampering observational estimates of climate sensitivity. Here we show that accounting for recent cooling in the eastern equatorial Pacific reconciles climate simulations and observations. We present a novel method of uncovering mechanisms for global temperature change by prescribing, in addition to radiative forcing, the observed history of sea surface temperature over the central to eastern tropical Pacific in a climate model. Although the surface temperature prescription is limited to only 8.2% of the global surface, our model reproduces the annual-mean global temperature remarkably well with correlation coefficient r = 0.97 for 1970-2012 (which includes the current hiatus and a period of accelerated global warming). Moreover, our simulation captures major seasonal and regional characteristics of the hiatus, including the intensified Walker circulation, the winter cooling in northwestern North America and the prolonged drought in the southern USA. Our results show that the current hiatus is part of natural climate variability, tied specifically to a La-Niña-like decadal cooling. Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas
Dario Izzo

Probabilistic Logic Allows Computer Chip to Run Faster - 3 views

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    Francesco pointed out this research one year ago, we dropped it as noone was really considering it ... but in space a low CPU power consumption is crucial!! Maybe we should look back into this?
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    Q1: For the time being, for what purposes computers are mainly used on-board?
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    for navigation, control, data handling and so on .... why?
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    Well, because the point is to identify an application in which such computers would do the job... That could be either an existing application which can be done sufficiently well by such computers or a completely new application which is not already there for instance because of some power consumption constraints... Q2 would be then: for which of these purposes strict determinism of the results is not crucial? As the answer to this may not be obvious, a potential study could address this very issue. For instance one can consider on-board navigation systems with limited accuracy... I may be talking bullshit now, but perhaps in some applications it doesn't matter whether a satellite flies on the exact route but +/-10km to the left/right? ...and so on for the other systems. Another thing is understanding what exactly this probabilistic computing is, and what can be achieved using it (like the result is probabilistic but falls within a defined range of precision), etc. Did they build a complete chip or at least a sub-circiut, or still only logic gates...
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    Satellites use old CPUs also because with the trend of going for higher power modern CPUs are not very convenient from a system design point of view (TBC)... as a consequence the constraints put on on-board algorithms can be demanding. I agree with you that double precision might just not be necessary for a number of applications (navigation also), but I guess we are not talking about 10km as an absolute value, rather to a relative error that can be tolerated at level of (say) 10^-6. All in all you are right a first study should assess what application this would be useful at all.. and at what precision / power levels
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    The interest of this can be a high fault tolerance for some math operations, ... which would have for effect to simplify the job of coders! I don't think this is a good idea regarding power consumption for CPU (strictly speaking). The reason we use old chip is just a matter of qualification for space, not power. For instance a LEON Sparc (e.g. use on some platform for ESA) consumes something like 5mW/MHz so it is definitely not were an engineer will look for some power saving considering a usual 10-15kW spacecraft
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    What about speed then? Seven time faster could allow some real time navigation at higher speed (e.g. velocity of a terminal guidance for an asteroid impactor is limited to 10 km/s ... would a higher velocity be possible with faster processors?) Another issue is the radiation tolerance of the technology ... if the PCMOS are more tolerant to radiation they could get more easily space qualified.....
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    I don't remember what is the speed factor, but I guess this might do it! Although, I remember when using an IMU that you cannot have the data above a given rate (e.g. 20Hz even though the ADC samples the sensor at a little faster rate), so somehow it is not just the CPU that must be re-thought. When I say qualification I also imply the "hardened" phase.
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    I don't know if the (promised) one-order-of-magnitude improvements in power efficiency and performance are enough to justify looking into this. For once, it is not clear to me what embracing this technology would mean from an engineering point of view: does this technology need an entirely new software/hardware stack? If that were the case, in my opinion any potential benefit would be nullified. Also, is it realistic to build an entire self-sufficient chip on this technology? While the precision of floating point computations may be degraded and still be useful, how does all this play with integer arithmetic? Keep in mind that, e.g., in the Linux kernel code floating-point calculations are not even allowed/available... It is probably possible to integrate an "accelerated" low-accuracy floating-point unit together with a traditional CPU, but then again you have more implementation overhead creeping in. Finally, recent processors by intel (e.g., the Atom) and especially ARM boast really low power-consumption levels, at the same time offering performance-boosting features such as multi-core and vectorization capabilities. Don't such efforts have more potential, if anything because of economical/industrial inertia?
Joris _

What the strange persistence of rockets can teach us about innovation. - 5 views

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    If I could write, this is exactly what I would write about rocket, GO, and so on... :) "we are decadent and tired. But none of the bright young up-and-coming economies seem to be interested in anything besides aping what the United States and the USSR did years ago. We may, in other words, need to look beyond strictly U.S.-centric explanations for such failures of imagination and initiative. ... Those are places we need to go if we are not to end up as the Ottoman Empire of the 21st century, and yet in spite of all of the lip service that is paid to innovation in such areas, it frequently seems as though we are trapped in a collective stasis." "But those who do concern themselves with the formal regulation of "technology" might wish to worry less about possible negative effects of innovation and more about the damage being done to our environment and our prosperity by the mid-20th-century technologies that no sane and responsible person would propose today, but in which we remain trapped by mysterious and ineffable forces."
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    Very interesting, though I'm amused how the author tends to (subconsciously?) shift the blame to non-US dictators :-) Suggestion that in absence of cold war US might have abandoned HB and ICBM programmes is ridiculous.
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    InterestIng, this was written by Neal Stephenson ( http://en.wikipedia.org/wiki/Neal_Stephenson#Works ). Great article Indeed. The videos of the event from which this arose might be equally InterestIng: Here Be Dragons: GovernIng a Technologically UncertaIn Future http://newamerica.net/events/2011/here_be_dragons "To employ a commonly used metaphor, our current proficiency In rocket-buildIng is the result of a hill-climbIng approach; we started at one place on the technological landscape-which must be considered a random pick, given that it was chosen for dubious reasons by a maniac-and climbed the hill from there, lookIng for small steps that could be taken to Increase the size and efficiency of the device."
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    You know Luis, when I read this quote, I could help thinking about GO, which would be kind of ironic considering the context but not far from what happens in the field :p
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    Fantastic!!!
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    Would have been nice if it were historically more accurate and less polemic / superficial
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    mmmh... the wheel is also an old invention... there is an idea behind but this article is not very deepfull, and I really don't think the problem is with innovation and lack of creative young people !!! look at what is done in the financial sector...
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

Human Brain Project - Goals - 3 views

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    can we contribute in any way to this - or alternatively benefit from this research already now?
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    Watch out!! I read quite a lot about the contribution by EPFL (apparently coordinator) and their boss, Henry Markram. From what I read, this is not really science, but mainly a PR campaign. The main motor in this project is attracting a lot of money and the main aim to do so is promising a lot of stuff that nobody will be able to deliver. Accordingly, Markram is a very controversial person in the business...
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    Oups, sorry! Of course I meant, "the main MEAN to do so...", but the aim justifies the means. Well, that's exactly Markram's motto, I guess.
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    interesting info indeed ... I though still think that the overall goal of this project, even if too ambitious for the time being is interesting, no?
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    It's not about interesting or not, it's about serious science or not. Also the goal of a fortune-teller is interesting, isn't it? Any description of a good science project is too ambitious, that's normal and not necessarily PR. But personally I think there is a certain limit where a science project becomes a bad SciFi thriller. This one here is a dime novel, I think. But the too ambitious is not the only point I became very doubtful. I have seen quite a number of scientists and engineers from different fields; what I read about the character and attitude of this guy just hints towards the worst case scenario. It's presumptive evidence, I know...
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    that bad! wow ....
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    You know me, I'm the bullshitter... You remember Kurzweil and his Singularity-nonsense. in a way this was very similar. Though I think Kurzweil and Markram are very different characters (The Singularity essentially is a religion, I can't see anything like that in Markram's claims) they seem to share an important point: they are both complete nerds that apparently never spent a single thought on the limits of science (in its English meaning) in general nor of their particular research field in specific. One may find this excusable, I don't. But even then, they make claims that the nerdest nerd must know that they are completely unrealistic and thus I just have to assume that they claim their nonsense on purpose. The reason in Markram's case clearly seems to be money. But all this does not mean that these nerds cannot produce valuable results.
johannessimon81

Asteroid mining could lead to self-sustaining space stations - VIDEO!!! - 5 views

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    Let's all start up some crazy space companies together: harvest hydrogen on Jupiter, trap black holes as unlimited energy supplies, use high temperatures close to the sun to bake bread! Apparently it is really easy to do just about anything and Deep Space industries is really good at it. Plus: in their video they show Mars One concepts while referring to ESA and NASA.
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    I really wonder what they wanna mine out there? Is there such a high demand on... rocks?! And do they really think they can collect fuel somewhere?
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    Well they want to avoid having to send resources into space and rather make it all in space. The first mission is just to find possible asteroids worth mining and bring some asteroid rocks to Earth for analysis. in 2020 they want to start mining for precious metals (e.g. nickel), water and such.They also want to put up a 3D printer in space so that it would extract, separate and/or fuse asteroidal resources together and then print the needed structures already in space. And even though on earth it's just rocks, in space a tonne of them has an estimated value of 1 million dollars (as opposed to 4000 USD on Earth). Although I like the idea, I would put DSI in the same basket as those Mars One nutters 'cause it's not gonna happen.
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    I will get excited once they demonstrate they can put a random rock into their machine and out comes a bicycle (then the obvious next step is a space station).
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    hmm aside from the technological feasibility, their approach still should be taken as an example, and deserve a little support. By tackling such difficult problems, they will devise innovative stuffs. Plus, even if this doom-to-fail endeavour may still seem you useless, it creates jobs and make people think... it is already a positive! Final word: how is that different from what Planetary Resources plan to do? It is founded by a bunch of so-called "nuts" ... (http://www.planetaryresources.com/team/) ! a little thought: "We must never be afraid to go too far, for success lies just beyond" - Proust
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    I don't think that this proposal is very different from the one by Planetary Resources. My scepticism is rooted in the fact that - at least to my knowledge - fully autonomous mining technology has not even been demonstrated on Earth. I am sure that their proposition is in principle (technically) feasible but at the same time I do not believe that a privately funded company will find enough people to finance a multi-billion dollar R&D project that may or may not lead to an economically sensible outcome, i.e. generate profit (not income - you have to pay back the R&D cost first) within the next 25 years. And on that timescale anything can happen - for all we know we will all be slaves to the singularity by the time they start mining. I do think that people who tackle difficult problems deserve support - and lots of it. It seems however that up till now they have only tackled making a promotional video... About job creation (sorry for the sarcasm): if usefulness is not so important my proposal would be to give shovels to two people - person A digs a hole and person B fills up the same hole at the same time. The good thing about this is that you can increase the number of jobs created simply by handing out more shovels.
johannessimon81

Bacteria grow electric wire in their natural environment - 1 views

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    Bacterial wires explain enigmatic electric currents in the seabed: Each one of these 'cable bacteria' contains a bundle of insulated wires that conduct an electric current from one end to the other. Cable bacteria explain electric currents in the seabed Electricity and seawater are usually a bad mix.
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    WOW!!!! don't want to even imagine what we do to these with the trailing fishing boats that sweep through sea beds with large masses .... "Our experiments showed that the electric connections in the seabed must be solid structures built by bacteria," says PhD student Christian Pfeffer, Aarhus University. He could interrupt the electric currents by pulling a thin wire horizontally through the seafloor. Just as when an excavator cuts our electric cables. in microscopes, scientists found a hitherto unknown type of long, multi-cellular bacteria that was always present when scientists measured the electric currents. "The incredible idea that these bacteria should be electric cables really fell into place when, inside the bacteria, we saw wire-like strings enclosed by a membrane," says Nils Risgaard-Petersen, Aarhus University. Kilometers of living cables The bacterium is one hundred times thinner than a hair and the whole bacterium functions as an electric cable with a number of insulated wires within it. Quite similar to the electric cables we know from our daily lives. "Such unique insulated biological wires seem simple but with incredible complexity at nanoscale," says PhD student Jie Song, Aarhus University, who used nanotools to map the electrical properties of the cable bacteria. in an undisturbed seabed more than tens of thousands kilometers cable bacteria live under a single square meter seabed. The ability to conduct an electric current gives cable bacteria such large benefits that it conquers much of the energy from decomposition processes in the seabed. Unlike all other known forms of life, cable bacteria maintain an efficient combustion down in the oxygen-free part of the seabed. It only requires that one end of the individual reaches the oxygen which the seawater provides to the top millimeters of the seabed. The combustion is a transfer of the electrons of the food to oxygen which the bacterial inner wires manage over centimeter-long distances. However, s
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