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pacome delva

Phantom menace to dark matter theory - space - 08 July 2009 - New Scientist - 0 views

www.newscientist.com/...ace-to-dark-matter-theory.html

phy mond gravitation

shared by pacome delva on 05 Aug 09 - Cached
  • If MOND exists, it will appear as if there is an anomalous, "phantom" mass in that region, exerting a gravitational force on the bodies in our solar system.
  • According to Milgrom, this force should cause the orbits of the planets to precess - that is, their elliptical orbits around the sun should slowly change their orientation, over time tracing out a pattern like the petals of a flower.
Ma Ru

Euroscience Open Forum 2010 - 2 views

www.esof2010.org

science conference Europe

shared by Ma Ru on 24 Apr 09 - Cached
LeopoldS liked it
  • ESA ACT on 24 Apr 09
     
    A conference ACT should consider going to.
  • ...4 more comments...
  • Ma Ru on 23 Apr 10
     
    Perhaps some of ACTers will find this conference interesting... One of the talks: "Would Einstein be on Twitter? Exploring the potential and limits of Web 2.0 in science & science communication" [Edit] Oh, I see someone has already posted this link... a year ago. Anyway, if anyone of you plans to go, let me know - I'll be around ;-)
  • Ma Ru on 08 Jul 10
     
    Just came back from ESOF 2010... I was on look for ACT agents undercover, but either they were not there or the cover was good enough... Anyway here's a few remarks from me (I could write a nice report... if you paid): 1) In general, to say that ESA was underrepresented on the conference as a whole is not enough (I guess ESA just failed to notice the event taking place). For instance, on the GMES presentation, ESA as such was not mentioned at all... at some point I started to wonder if ESA is actually involved in the project, but now I checked the website and apparently it is. On the other hand, GMES presentation was crap anyway, as after 1:15 of talking, I didn't gain any knowledge of what GMES is and what its contributions to the EU community will be. 2) There was a lot of talk about LHC and particle research (well, at least among those that I attended). Some of them were very good, some of them rather crap... 3) "Would Einstein be on Twitter? Exploring the potential and limits of Web 2.0 in science & science communication" talk - quite interesting, but focusing mainly on Science-to-Wide Public and Science-to-Journalists communication. Not really on Science-to-Science (as in Ariadnet). There was quite an extensive discussion with the public. You may be interested that Nature is trying to stimulate Web 2.0 communication, running blog service, but also I think a kind of social network - perhaps you'd like to have a look. In general the conclusion was that Web 2.0 is not so useful for scientific communication because practising it requires TIME (blogs, etc.) and often some professional skills (podcasts/videocasts, etc.), and scientists have neither of these. This can be run on corporation level (like ESA does actually), but then it looses the "intimate" character. 4) "How much can robots learn?" talk... very nicely presented: understandable by the wide public, but conveying the message... which is something like "we can already make the robots do stuff absolutely imp
  • Ma Ru on 08 Jul 10
     
    Well, my comment was cut in half, and I don't feel like typing it again... the most important highlight from the rest is that the only presenter from ESA (ESTEC) did not show up on his talk because his department was undergoing some sort of audit on the same day :)
  • LeopoldS on 08 Jul 10
     
    Fantastic comment - or better report!! thanks very much Marek! Who was the supposed no-show speaker from ESA?
  • Ma Ru on 08 Jul 10
     
    Bernard Foing (he is actually one of the 8 ESA employees who have their own page on Wikipedia)...
  • LeopoldS on 08 Jul 10
     
    written almost entirely by a guy called a "quest for knowledge" ... who will this be????? :-)
Luís F. Simões

Pioneer Anomaly Solved By 1970s Computer Graphics Technique - Technology Review - 4 views

www.technologyreview.com/...26589

pioneer anomaly PHY astrophysics

shared by Luís F. Simões on 31 Mar 11 - No Cached
Nicholas Lan liked it
  • Now Frederico Francisco at the Instituto de Plasmas e Fusao Nuclear in Lisbon Portugal, and a few pals, say they've worked out where the thermal calculations went wrong. These guys have redone the calculations using a computer model of not only how the heat is emitted but how it is reflected off the various parts of the spacecraft too. The reflections turn out to be crucial.
  • Ref: arxiv.org/abs/1103.5222: Modelling The Reflective Thermal Contribution To The Acceleration Of The Pioneer Spacecraft
  • santecarloni on 01 Apr 11
     
    This is really cool. I know one of the authors and he is a good guy... the only thing that leaves me unsatisfied is that if the whole issue is related to thermal effects one should have seen the Pioneer effect all the time and not only at about 10 AU... ...or is there some thermal process that kicked in only at this distance?
  • Luís F. Simões on 26 Jul 11
     
    Here's an update on this theory: NASA Releases New Pioneer Anomaly Analysis "The mysterious force acting on the Pioneer spacecraft seems to be falling exponentially. That's a strong clue that on-board heat is to blame, says NASA." Heat emission 'most likely cause' of pioneer anomaly "What's more interesting is that, contrary to the original analysis conducted all those years ago, the deceleration does seem to be decelerating at an exponential rate -- just as one might expect from the radioactive decay of plutonium-238, which powers the two spacecraft. Turyshev concludes, "The most likely cause of the Pioneer anomaly is the anisotropic emission of on-board heat.""
LeopoldS

SpaceX Targets 2013 for Launch of Falcon Heavy | SpaceNews.com - 1 views

spacenews.com/...pacex-launch-falcon-heavy.html

spacex launcher

shared by LeopoldS on 05 Apr 11 - No Cached
  • LeopoldS on 05 Apr 11
     
    big big booster coming ... !
  • ...1 more comment...
  • Joris _ on 06 Apr 11
     
    In similar story (http://www.orlandosentinel.com/news/os-spacex-rocket-elon-musk-20110405,0,3234336.story) the quote: " "This is a rocket of truly huge scale," said Musk, adding it would have the capability to one day enable moon or Mars missions." tells a lot about the ambition of it...
  • Luís F. Simões on 17 Apr 11
     
    even bigger booster also coming: China Aims To Build World's Largest Rocket "Back in March, China revealed it is studying the feasibility of designing the most powerful carrier rocket in history for making a manned moon landing and exploring deep space, according to Liang Xiaohong, vice head of the China Academy of Launch Vehicle Technology. The rocket is envisaged to have a payload of 130 tonnes, five times larger than that of China's current largest rocket. This rocket, if built, will eclipse the 53 tonne capacity of the planned Falcon 9 Heavy from SpaceX. It will even surpass the largest rocket ever built, the 119-tonne Saturn V."
  • LeopoldS on 18 Apr 11
     
    still only "is studying the feasibility of designing a powerful carrier rocket" - we could easily do the same at no cost almost ... but still ... they might be serious ...
johannessimon81

Astronomers Surprised to Find Asteroid With Rings - 2 views

www.wired.com/...asteroid-ring-system

space

shared by johannessimon81 on 27 Mar 14 - No Cached
  • johannessimon81 on 27 Mar 14
     
    For the first time ever, astronomers have discovered a ring system surrounding an asteroid. The finding is a complete surprise to planetary scientists, who are yet unsure exactly how such rings could have formed. The cosmic bling was found around an object named Chariklo, which orbits in a region between Saturn and Uranus.
Thijs Versloot

Twisted light waves sent across Vienna - 2 views

www.iop.org/...page_64430.html

laser communication OAM optics

shared by Thijs Versloot on 12 Nov 14 - No Cached
LeopoldS and jcunha liked it
  • Thijs Versloot on 12 Nov 14
     
    A group of researchers from Austria have sent twisted beams of light across the rooftops of Vienna. It is the first time that twisted light has been transmitted over a large distance outdoors, and could enable researchers to take advantage of the significant data-carrying capacity of light in both classical and quantum communications. Although the data rate is not very high, it could offer a way to provide unhackable data links via space. Would provide an edge over terrestrial fibre optics?
Thijs Versloot

A Groundbreaking Idea About Why Life Exists - 1 views

www.businessinsider.com/g-idea-of-lifes-origin-2014-12

life physics mathematics

shared by Thijs Versloot on 15 Dec 14 - No Cached
  • Thijs Versloot on 15 Dec 14
     
    Jeremy England, a 31-year-old assistant professor at the Massachusetts Institute of Technology, has derived a mathematical formula that he believes explains this capacity. The formula, based on established physics, indicates that when a group of atoms is driven by an external source of energy (like the sun or chemical fuel) and surrounded by a heat bath (like the ocean or atmosphere), it will often gradually restructure itself in order to dissipate increasingly more energy. This could mean that under certain conditions, matter inexorably acquires the key physical attribute associated with life. The simulation results made me think of Jojo's attempts to make a self-assembling space structure. Seems he may have been on the right track, just not thinking big enough
  • johannessimon81 on 15 Dec 14
     
    :-P Thanks Thijs... I do not agree with the premise of the article that a possible correlation of energy dissipation in living systems and their fitness means that one is the cause for the other - it may just be that both go hand-in-hand because of the nature of the world that we live in. Maybe there is such a drive for pre-biotic systems (like crystals and amino acids), but once life as we know it exists (i.e., heredity + mutation) it is hard to see the need for an amendment of Darwin's principles. The following just misses the essence of Darwin: "If England's approach stands up to more testing, it could further liberate biologists from seeking a Darwinian explanation for every adaptation and allow them to think more generally in terms of dissipation-driven organization. They might find, for example, that "the reason that an organism shows characteristic X rather than Y may not be because X is more fit than Y, but because physical constraints make it easier for X to evolve than for Y to evolve." Darwin's principle in its simplest expression just says that if a genome is more effective at reproducing it is more likely to dominate the next generation. The beauty of it is that there is NO need for a steering mechanism (like maximize energy dissipation) any random set of mutations will still lead to an increase of reproductive effectiveness. BTW: what does "better at dissipating energy" even mean? If I run around all the time I will have more babies? Most species that prove to be very successful end up being very good at conserving energy: trees, turtles, worms. Even complexity of an organism is not a recipe for evolutionary success: jellyfish have been successful for hundreds of millions of years while polar bears are seem to be on the way out.
Thijs Versloot

Webinar: Solving system level design riddle - 1 views

www.designworldonline.com/ing-system-level-design-riddle

concurrent design

shared by Thijs Versloot on 09 Dec 14 - No Cached
LeopoldS liked it
  • Thijs Versloot on 09 Dec 14
     
    In the space industry, concurrent design is frequently implemented as requirements are frequently not set but developed along the design process. In many cases this is due to the interconnection between (sub)systems. In the industry however, this is hardly done, but it is becoming more relevant as lead times and innovation speed needs to increase. There is a webinar tomorrow 10 december from Agile on this topic regarding the semiconductor industry
  • LeopoldS on 13 Dec 14
     
    missed it ... did anybody attend?
Thijs Versloot

NASA's 'Swarmies' are a squad of smaller, less intelligent rovers - 0 views

www.engadget.com/...nasa-swarmies

robot swarm AI

shared by Thijs Versloot on 27 Aug 14 - No Cached
  • Thijs Versloot on 27 Aug 14
     
    Typically, we send rovers to our planetary neighbors one at a time -- but what if we sent a small team of smaller, less impressive robots instead? That's the idea NASA is exploring at Kennedy Space Center with Swarmies: a quartet of four autonomous robots designed to work together to complete a single mission.
Athanasia Nikolaou

More science crowdsourcing games! - "EyeWire" - 4 views

news.sciencemag.org/...reveals-space-time-neurons-eye

BIO Neuroscience crowdsourcing INF

shared by Athanasia Nikolaou on 08 May 14 - No Cached
  • Athanasia Nikolaou on 08 May 14
     
    There is this optical neuron that gets stimulated from motion. Mapping it is difficult in the lab: "The stumbling block is a lack of fine-grained anatomical detail about how the neurons in the retina are wired up to each other." So, use people deciphering from 2D images --> the 3D neuron structure using the human spatial reasoning to figure out what is part of a branching cell and what is just background noise in the images (yet incomparable to their best algorithms' performance) 120.000 users so far mapped 2% of the retina
Thijs Versloot

Laser link offers high-speed delivery - 0 views

www.esa.int/...ink_offers_high-speed_delivery

laser communication

shared by Thijs Versloot on 02 Dec 14 - No Cached
  • Thijs Versloot on 02 Dec 14
     
    New technology demonstration of laser communication link to offer high-speed near real time delivery of data from space... Oh, that's us... :)
jaihobah

The Nanodevice Aiming to Replace the Field Effect Transistor - 2 views

www.technologyreview.com/...ce-the-field-effect-transistor

transistor PHY technology

shared by jaihobah on 03 Feb 16 - No Cached
LeopoldS liked it
  • LeopoldS on 08 Feb 16
     
    very nice! "For a start, the wires operate well as switches that by some measures compare well to field effect transistors. For example they allow a million times more current to flow when they are on compared with off when operating at a voltage of about 1.5 V. "[A light effect transistor] can replicate the basic switching function of the modern field effect transistor with competitive (and potentially improved) characteristics," say Marmon and co. But they wires also have entirely new capabilities. The device works as an optical amplifier and can also perform basic logic operations by using two or more laser beams rather than one. That's something a single field effect transistor cannot do."
  • ...1 more comment...
  • jcunha on 09 Feb 16
     
    The good thing about using CdSe NW (used here) is that they show a photon-to-current efficiency window around the visible wavelengths, therefore any visible light can in principle be used in this application to switch the transistor on/off. I don't agree with the moto "Nanowires are also simpler than field effect transistors and so they're potentially cheaper and easier to make." Yes, they are simple, yet for applications, fabricating devices with them consistently is very challenging (being the research effort not cheap at all..) and asks for improvements and breakthroughs in the fabrication process.
  • LeopoldS on 09 Feb 16
     
    any idea how the shine the light selectively to such small surfaces?
  • jcunha on 10 Feb 16
     
    "Illumination sources consisted of halogen light, 532.016, 441.6, and 325 nm lasers ported through a Horiba LabRAM HR800 confocal Raman system with an internal 632.8 nm laser. Due to limited probe spacing for electrical measurements, all illumination sources were focused through a 50x long working distance (LWD) objective lens (N.A. = 0.50), except 325 nm, which went through a 10x MPLAN objective lens (N.A. = 0.25)." Laser spot size calculated from optical diffraction formula 1.22*lambda/NA
Alexander Wittig

Scientists discover hidden galaxies behind the Milky Way - 1 views

www.icrar.org/...hidden-galaxies

astronomy

shared by Alexander Wittig on 11 Feb 16 - No Cached
  • Alexander Wittig on 11 Feb 16
     
    Hundreds of hidden nearby galaxies have been studied for the first time, shedding light on a mysterious gravitational anomaly dubbed the Great Attractor. Despite being just 250 million light years from Earth-very close in astronomical terms-the new galaxies had been hidden from view until now by our own galaxy, the Milky Way. Using CSIRO's Parkes radio telescope equipped with an innovative receiver, an international team of scientists were able to see through the stars and dust of the Milky Way, into a previously unexplored region of space. The discovery may help to explain the Great Attractor region, which appears to be drawing the Milky Way and hundreds of thousands of other galaxies towards it with a gravitational force equivalent to a million billion Suns. Lead author Professor Lister Staveley-Smith, from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said the team found 883 galaxies, a third of which had never been seen before. "The Milky Way is very beautiful of course and it's very interesting to study our own galaxy but it completely blocks out the view of the more distant galaxies behind it," he said. Professor Staveley-Smith said scientists have been trying to get to the bottom of the mysterious Great Attractor since major deviations from universal expansion were first discovered in the 1970s and 1980s. "We don't actually understand what's causing this gravitational acceleration on the Milky Way or where it's coming from," he said. "We know that in this region there are a few very large collections of galaxies we call clusters or superclusters, and our whole Milky Way is moving towards them at more than two million kilometres per hour." The research identified several new structures that could help to explain the movement of the Milky Way, including three galaxy concentrations (named NW1, NW2 and NW3) and two new clusters (named CW1 and CW2).
jaihobah

Tajmar tests the EM drive with DLR funding and the result is... - 4 views

tu-dresden.de/...-and-Mach-Effect-Thrusters.pdf

space PHY science?

shared by jaihobah on 21 May 18 - No Cached
jcunha liked it
  • jaihobah on 21 May 18
     
    it works! No, of course it doesn't. I've wasted your time just posting this.
jaihobah

A precise extragalactic test of General Relativity - 0 views

science.sciencemag.org/...1342

PHY

shared by jaihobah on 22 Jun 18 - No Cached
  • jaihobah on 22 Jun 18
     
    Einstein's theory of gravity, General Relativity (GR), has been tested precisely within the Solar System. However, it has been difficult to test GR on the scale of an individual galaxy. Collett et al. exploited a nearby gravitational lens system, in which light from a distant galaxy (the source) is bent by a foreground galaxy (the lens). Mass distribution in the lens was compared with the curvature of space-time around the lens, independently determined from the distorted image of the source. The result supports GR and eliminates some alternative theories of gravity.
koskons

A Political History of Apollo | The Planetary Society - 2 views

www.planetary.org/...litical-history-of-apollo.html

technology science space

shared by koskons on 14 Aug 19 - No Cached
  • koskons on 14 Aug 19
     
    Another entry by the Planetary Society for the Apollo 11 50th anniversary, this time a podcast series on its political background.
gpetit

Intrinsic functional connectivity reduces after first-time exposure to short-term gravi... - 1 views

www.nature.com/...s41598-017-03170-5

BIO space

shared by gpetit on 03 Jul 17 - No Cached
  • gpetit on 03 Jul 17
     
    Loss of connectivity in the multisensory integration cortical areas after short term microgravity experience, which could explain astronauts decrease of performance in sensorimotor tasks and spatial working memory. However, the effect should wear off after a few days in microgravity and after adaptation to incongruent vestibular information. ISS experiment needed...
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