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Francesco Biscani

The End Of Gravity As a Fundamental Force - 6 views

science.slashdot.org/...Gravity-As-a-Fundamental-Force

phy

shared by Francesco Biscani on 11 Jan 10 - Cached
LeopoldS liked it
  • Francesco Biscani on 11 Jan 10
     
    "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."
  • ...8 more comments...
  • Dario Izzo on 12 Jan 10
     
    Diffcult for me to fully understand / believe in the holographic principle at macroscopical scales ... potentially it looks though as a revolutionary idea.....
  • pacome delva on 13 Jan 10
     
    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 ?
  • Luzi Bergamin on 13 Jan 10
     
    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.
  • Luzi Bergamin on 13 Jan 10
     
    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...
  • LeopoldS on 13 Jan 10
     
    is there any experimental or observational evidence that points to this "solution"?
  • Luzi Bergamin on 13 Jan 10
     
    Are you joking??? :D
  • pacome delva on 14 Jan 10
     
    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...
  • LeopoldS on 14 Jan 10
     
    Luzi, I miss you!!!
  • Luzi Bergamin on 14 Jan 10
     
    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.
  • pacome delva on 14 Jan 10
     
    haha, today would have been great to show your mood... we had a talk on the connection between mind and matter !!
pacome delva

Landmarks: Teleportation is not Science Fiction - 0 views

focus.aps.org/st1

phy quantum_computation quantum_physics quantum_cryptography

shared by pacome delva on 11 Jan 10 - Cached
  • If a practical quantum computer is ever built, he says, it will have to make use of different kinds of quantum bits, perhaps atoms for storage and photons for transmission. So teleportation would be a natural way to connect these components, he says.
Francesco Biscani

Can Curiosity Be Programmed? - 4 views

developers.slashdot.org/...Can-Curiosity-Be-Programmed

ai

shared by Francesco Biscani on 28 Jan 10 - Cached
  • Francesco Biscani on 28 Jan 10
     
    Deja-vu?
  • Luzi Bergamin on 28 Jan 10
     
    He talks on "Singularity Summits" of good ol' Kurtzweil? Surprised?
Francesco Biscani

Open Source Software Meets Do-It-Yourself Biology - 1 views

science.slashdot.org/...e-Meets-Do-It-Yourself-Biology

bio inf

shared by Francesco Biscani on 26 Jan 10 - Cached
  • Francesco Biscani on 26 Jan 10
     
    "As the shift to open source software continues, computational biology will become even more accessible, and even more powerful, while intellectual property and other bureaucracies continue to hobble traditional forms of research." Spot on, I'm very glad to see this happening :)
Eduardo Martin Moraud

On whether to re-brand space junk as "historical heritage"... - 3 views

www.latimes.com/...nk29-2010jan29,0,5698181.story

shared by Eduardo Martin Moraud on 29 Jan 10 - Cached
LeopoldS liked it
  • Eduardo Martin Moraud on 29 Jan 10
     
    For those working on space debris removal... Watch out for moon-protection activists that will accuse you of distroying a historical heritage: "There are countless places on Earth that have been awarded protection to preserve their historic or cultural importance. The moon has none. But that may be about to change...."
Juxi Leitner

"Verschränkte" Gehirnzellen - science.ORF.at - 2 views

science.orf.at/1636355

bio neuroscience quantum

shared by Juxi Leitner on 18 Jan 10 - Cached
  • Juxi Leitner on 18 Jan 10
     
    Sorry for the German, but there is a link to the english paper as well: http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1000278 Following up on Martin's talk, I found that on the Austrian National Broadcaster website, well not really the top source for sound science news but anyway :)
Nicholas Lan

A counter-distributed computing story - 4 views

www.economist.com/...displaystory.cfm

computing technology

shared by Nicholas Lan on 25 Jan 10 - Cached
  • Nicholas Lan on 25 Jan 10
     
    article itself isn't terribly interesting but first piece i've seen on such a trend
nikolas smyrlakis

Google Maps Finally Adds Bike Routes | Autopia | Wired.com - 1 views

www.wired.com/...google-maps-for-bikes

maps google bike routes

shared by nikolas smyrlakis on 10 Mar 10 - Cached
  • nikolas smyrlakis on 10 Mar 10
     
    not for leiden - estec yet as I checked but hopefully soon for the netherlands
Ma Ru

Riding the strangest rocket in the world - 0 views

www.bbc.co.uk/...-the-strangest-rocket-in.shtml

space science technology operations launchers

shared by Ma Ru on 19 Mar 10 - Cached
  • Ma Ru on 19 Mar 10
     
    Interesting article about your Cryosat. Don't miss the Dniepr launch videos and the story about Kazakh surgeon fixing the satellite :)
pacome delva

Fruit Fly Aerial Maneuver Explained - 1 views

focus.aps.org/st13

bio biomimicry fruit_fly

shared by pacome delva on 12 Apr 10 - Cached
LeopoldS liked it
  • Insects can execute flying feats more impressive than fighter jets, and a team of researchers has now learned the trick behind one of them. They used high speed video cameras and a new 3D reconstruction technique to show how fruit flies execute their acrobatic turns. As they report in the 9 April Physical Review Letters, despite the complex wing motions, a fly can execute quick pirouettes by adjusting just a single parameter that controls the difference between the way its left and right wings oscillate. The results may be relevant for engineers designing flight control strategies for tiny robotic insects for search-and-rescue and surveillance.
pacome delva

Girls Get Math: It's Culture That's Skewed - 2 views

www.livescience.com/...090601-gender-math.html

sociology math

shared by pacome delva on 19 Apr 10 - Cached
  • "There's a gender stereotype that boys are better at math than girls are, and stereotypes die very hard," Hyde told LiveScience. "Teachers and parents still believe that boys are better at math than girls are." The researchers provide several possible cultural factors keeping females from excelling in math, including classroom dynamics in which teachers pay more attention to boys, while even mathematically gifted girls are not nurtured. In addition, stereotypes may drive guidance counselors and others to discourage girls from taking engineering courses.
  • Nina Nadine Ridder on 26 Apr 10
     
    The guidance counselor at my high school discouraged me to study physics but was very excited when I was contemplating to become a teacher. Maybe I should send her this article...
  • Luzi Bergamin on 26 Apr 10
     
    Oh yeah, real new!! And in the 90s it was obvious that girls are smarter but discriminated, today its obvious that the poor boys are neglected; some years ago female teachers were proven to discriminate even stronger against girls than male teachers and today politicians demand more male teachers... because they would pay more attention to the neglected boys! Great, that's what I like about sociological research, every couple of years one can sell the same old story again and again and again... sorry, I'm in a real bullshitter mood today!
  • Nicholas Lan on 27 Apr 10
     
    gotta agree with luzi here. girls at secondary school in the UK have been outperforming boys for years now after numerous government programmes. As to guidance counsellors - if they were any good at guidance wouldn't they have better jobs?
pacome delva

New Material: Network of 'Streets' for Light - 1 views

focus.aps.org/st14

phy metamaterials waveguides

shared by pacome delva on 19 Apr 10 - Cached
  • In recent years, researchers have created early versions of "invisibility cloaks" and advanced optical fibers by manipulating light using structures composed of tiny, repeating units. In the 9 April Physical Review Letters, a team proposes a different way to make an artificial optical material--from a network of light-guiding filaments. If such structures are practical, they could open new ways to control light in technologies ranging from high-speed telecommunication to high-resolution imaging.
pacome delva

Mapping Turbulence in the Solar Wind - 0 views

focus.aps.org/st16

phy astrophysics solar_wind formation_flying turbulence

shared by pacome delva on 03 May 10 - Cached
  • a team reports studying the turbulent flow of solar wind particles by monitoring the accompanying waves of magnetic field. The team used a cluster of satellites to measure the field in unprecedented spatial detail. They found that the waves aren't equally strong in all directions but are larger in certain preferred directions, as theorists had predicted. The observation will help astrophysicists better understand the consequences of the solar wind, including its effect on the transmission of cosmic rays, particles that arrive at Earth from elsewhere in our galaxy.
Ma Ru

Space shuttle for sale - 1 views

edition.cnn.com/...index.html

Space shuttle sale technology space NASA

shared by Ma Ru on 26 May 10 - Cached
  • Ma Ru on 26 May 10
     
    Sort of a follow-up to the story Joris posted a while ago...
Luís F. Simões

Crowdfund a Moon Monolith Mission? - Slashdot - 1 views

idle.slashdot.org/...wdfund-a-Moon-Monolith-Mission

2001 monolith moon crowdsourcing private-spaceflight sci-fi fun

shared by Luís F. Simões on 07 Jan 11 - No Cached
  • Jamie found a somewhat amusing little essay on putting together a crowd-sourced mission to put a monolith on the moon. The author estimates it would cost half a billion dollars, which is a sum he thinks could be raised.
  • Let's raise the stakes. I propose raising half a trillion dollars to develop a time machine and put a monolith in Olduvai Gorge three million years in the past to influence Astralopithecus Afarensis evolution. Our very existence might depend on it.
Isabelle DB

Global Warning - a project of the National Security Journalism Initiative - 0 views

global-warning.org/main

Arctic Climate Change Global Warming and Security Environment Energy Youth Students Water Military

shared by Isabelle DB on 12 Jan 11 - No Cached
  • Isabelle DB on 12 Jan 11
     
    "WASHINGTON, D.C. - In a three-month investigation, a team of Northwestern University student reporters has found that the US nation's security establishment is not adequately prepared for many of the environmental changes that are coming faster than predicted and that threaten to reshape demands made on the military and intelligence community. This is despite the fact that the Defense Department has called climate change a potential "accelerant of instability." The Medill School of Journalism graduate student team began publication on January 10 of its findings on the national security implications of climate change with a series of print, video and interactive stories."
Luís F. Simões

Open Source Hardware Hits 1.0 - Slashdot - 1 views

hardware.slashdot.org/...Open-Source-Hardware-Hits-10

open-source hardware

shared by Luís F. Simões on 11 Feb 11 - No Cached
  • Open Source Hardware is a term for tangible artifacts — machines, devices, or other physical things — whose design has been released to the public in such a way that anyone can make, modify, distribute, and use those things.
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