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pacome delva

A Phase Transition for Light | Physical Review Focus - 3 views

focus.aps.org/st19

phy liquid_light electromagnetism

shared by pacome delva on 22 Nov 10 - No Cached
  • A computer simulation shows the transition from "fermionic" to "liquid" light.
  • The possibility of sending this type of "self-focused" light pulse long distances could be important for remote sensing applications, such as LIDAR, which uses laser light the way radar uses radio waves.
  • LeopoldS on 23 Nov 10
     
    what the heck is this?? sounds really strange but highly interesting to me ....
  • LeopoldS on 23 Nov 10
     
    can we use this for energy transmission?
  • LeopoldS on 23 Nov 10
     
    read it now more carefully and the answer is probably no ...
Ma Ru

Yet another issue to take into account when you want to travel at c - 1 views

www.newscientist.com/...lls-especially-warp-speed.html

PHY interstellar travel human spaceflight speed of light

shared by Ma Ru on 19 Feb 10 - Cached
  • Ma Ru on 19 Feb 10
     
    While my attitude to articles about interstellar travel is generally sceptical, this one seems to raise quite an interesting point... Physicists?
  • ...1 more comment...
  • pacome delva on 19 Feb 10
     
    mmm, I think that if we manage to travel at 99.999998 per cent the speed of light, we'll have the technology to deviate these atoms ! one way could be a super strong magnetic field, or a super laser that would act as an ice breaker with the radiation pressure (the good thing is that light always travel at the speed of light, even if you are at 99.999998 per cent the speed of light)
  • Francesco Biscani on 19 Feb 10
     
    Also, remember never to dereference null pointers.
  • Ma Ru on 19 Feb 10
     
    True, it's almost like installing accelerometers upside down...
pacome delva

"Quantum trampoline" measures gravity - 2 views

physicsworld.com/...41208

phy atom_interferometry atom_gravimeter

shared by pacome delva on 15 Dec 09 - Cached
  • Physicists in France have come up with a new way of using bouncing ultracold atoms to measure the acceleration due to gravity. The technique involves firing vertical laser pulses at a collection of free-falling atoms, which bounces some atoms higher than others. When the atoms recombine at the centre of the experiment, they create an interference pattern that reveals that g is 9.809 m/s2 – just as expected for their Paris lab.
  • pacome delva on 15 Dec 09
     
    That's the lab I worked...
  • Dario Izzo on 16 Dec 09
     
    just being cinical ... but did not we know that g = 9.809 in Paris? I can also create a complex measurement procedure that will held pi = 3.1415, just as expected!!!
  • pacome delva on 17 Dec 09
     
    well, sure... the interest of such gravimeter is to be absolute, and for now slightly more accurate than the other type of absolute gravimeter which uses retroreflector and interferometry ( http://en.wikipedia.org/wiki/Gravimeter ). While the latter ones reached their limit in term of sensitivity, the atomic ones can be enhanced in many ways (using cooler atoms, better optics, etc...)
pacome delva

The Spiky Penis Gets the Girl - 1 views

sciencenow.sciencemag.org/...3

flies sexuality

shared by pacome delva on 07 Jan 10 - Cached
  • the genital spines give an advantage before insemination by fastening the genitalia together like Velcro fasteners.
  • pacome delva on 07 Jan 10
     
    Interesting...
  • Juxi Leitner on 07 Jan 10
     
    "But there was no direct way to test this. Enter laser beams." ... LOL
Joris _

SPACE.com -- NASA to Boost Speed of Deep Space Communications - 1 views

www.space.com/...tion-network-speed-100122.html

MAD technology communications DSN

shared by Joris _ on 25 Jan 10 - Cached
  • a few megabits per second might someday get as much as 600 megabits per second, if not more. That could enable far more scientific payoff per mission in the long run.
  • new communication innovations such as disruption tolerant networking
  • one of the biggest communication revolutions will come from laser-driven optical communication
    • Joris _
      Joris _ on 25 Jan 10
       
      they kind-of stole my idea ;)
Luís F. Simões

SETI, Citrus Division - 1 views

www.newscientist.com/...cted-at-kinetica-art-fair.html

SETI fun

shared by Luís F. Simões on 07 Feb 11 - No Cached
  • A nice contrast to these high-tech installations, Adrian Lee's Search for Extra-Terrestrial Intelligence (SETI) Citrus Division (below), sees 65 lemons trying to communicate with aliens. Using their own juices, these lemon batteries power a small motor - which turns a disc into which is punched the Morse code for "We are here". As the disc rotates, a class 2 laser - also powered by the lemons - shines through the holes and the encoded message is then directed by a small mirror up into space...or in this case, onto the ceiling of the Ambica P3 venue. Amusing, simple and sophisticated all at once, the Citrus Division mixes old and new science and technology in just the right measure.
Isabelle DB

Laser light and the nematode C. elegans - 2 views

colbert.physics.harvard.edu/videos.php

bio phy

shared by Isabelle DB on 10 Mar 11 - No Cached
  • Isabelle DB on 10 Mar 11
     
    Controlling Locomotion and Behavior in Real-Time
ESA ACT

Technology Review: Laser Lunar Landing System - 0 views

www.technologyreview.com/...21660

lander optics sensors

shared by ESA ACT on 24 Apr 09 - Cached
  • ESA ACT on 24 Apr 09
     
    NASA still on active sensors...
Ma Ru

Dark Matter or Black Hole Propulsion? - 1 views

www.newscientist.com/...s-for-interstellar-travel.html

NRG propulsion star travel space PHY

shared by Ma Ru on 25 Nov 09 - Cached
  • Ma Ru on 25 Nov 09
     
    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
  • ...5 more comments...
  • Luzi Bergamin on 26 Nov 09
     
    What an awful bunch of complete nonsense!!! But I don't think anybody wants to hear MY opinion on this...
  • pacome delva on 26 Nov 09
     
    wow, is this serious at all...!?
  • Luzi Bergamin on 26 Nov 09
     
    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??
  • LeopoldS on 26 Nov 09
     
    WRONG!!! we are all just WAITING for your opinion on this ....!!!
  • pacome delva on 27 Nov 09
     
    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...
  • Luzi Bergamin on 27 Nov 09
     
    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.
  • pacome delva on 27 Nov 09
     
    well then I agree, how the fu.. they want to collect them !!!
Joris _

A Fusion Thruster for Space Travel - IEEE Spectrum - 4 views

spectrum.ieee.org/...0

Thruster PHY NRG NASA

shared by Joris _ on 29 Jun 11 - No Cached
LeopoldS liked it
  • Now a NASA engineer has come up with a new way to fling satellites through space on mere grams of fuel, tens of times as efficiently as today’s best space probe thrusters.
  • Instead of using deuterium and tritium as the fuel stocks, the new motor extracts energy from boron fuel.
  • Joris _ on 29 Jun 11
     
    "And according to his calculations, improvements in short-pulse laser systems could make this form of thruster more than 40 times as efficient as even the best of today's ionic propulsion systems that push spacecraft around. "
  • LeopoldS on 02 Jul 11
     
    Dejan please have a look at this also ...
  • LeopoldS on 02 Jul 11
     
    while the nuclear reaction seems to be sound at first view, I am not so sure how this would work: "Electromagnetic forces push the target and the alpha particles in the opposite directions, and the particles exit the spacecraft through a nozzle, providing the vehicle's thrust. "
annaheffernan

Particle accelerator barely bigger than a grain of sand - 3 views

gizmodo.com/bigger-than-a-grain-1426829083

technology PHY science

shared by annaheffernan on 07 Oct 13 - No Cached
  • annaheffernan on 07 Oct 13
     
    Just getting a particle up to near the speed of light isn't good enough for today's physics. To properly unravel the fundamentals of the universe, particles have to be smashed together with enormous force. And two Stanford researchers have just devised a laser-based method that imparts ten times the power of traditional methods at a fraction of the cost.
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?
Paul N

Room temperature superconductors - 4 views

phys.org/...superconductivity-cooling.html

technology PHY

shared by Paul N on 06 Dec 14 - No Cached
Thijs Versloot and jcunha liked it
  • Paul N on 06 Dec 14
     
    With the aid of short infrared laser pulses, researchers have succeeded for the first time in making a ceramic superconducting at room temperature - albeit for only a few millionths of a microsecond.
Isabelle Dicaire

Experimental space telescopes to be 3D-printed at NASA - Laser Focus World - 0 views

www.laserfocusworld.com/...-to-be-3d-printed-at-nasa.html

shared by Isabelle Dicaire on 08 Aug 14 - No Cached
  • Isabelle Dicaire on 08 Aug 14
     
    From the article: By the end of September 2014, Jason Budinoff, an aerospace engineer at NASA's Goddard Space Flight Center (Greenbelt, MD), is expected to complete the first imaging telescopes ever assembled almost exclusively from 3D-manufactured components. The devices' optics and electronics will be fabricated using conventional methods. "As far as I know, we are the first to attempt to build an entire instrument with 3D printing," says Budinoff. He is building a fully functional 50 mm camera whose outer tube, baffles, and optical mounts are all printed as a single structure. The instrument is appropriately sized for a CubeSat (a small satellite made of individual units each about 100 mm on a side). 
Paul N

Microsoft Hololens, Occulus rift killer? - 1 views

www.youtube.com/watch

FUN

shared by Paul N on 27 Jan 15 - No Cached
  • Paul N on 27 Jan 15
     
    Probably old news by now, but this thing sounds so awesome it warrants an entry
  • Thijs Versloot on 28 Jan 15
     
    Looks like fun! Note though, I'm always slightly annoyed when people use holography only because it sounds cool. because clearly this is not a hologram! Definition: a three-dimensional image formed by the interference of light beams from a laser or other coherent light source. I am sure this is not what is happening in these goggles.
  • Paul N on 28 Jan 15
     
    I think they suspect that "hologram" would sell better than "yet-another-augmented-reality-goggle"
jcunha

Nature Optics: Super vision - 6 views

www.nature.com/...optics-super-vision-1.16877

BIO technology science PHY FUN

shared by jcunha on 13 Feb 15 - No Cached
  • jcunha on 13 Feb 15
     
    Taking images through opaque, light-scattering layers is a vital capability and essential diagnostic tool in many applications. The research group of Prof. Mosk of U. Twente have started doing experiments shooting optical lasers into opaque materials in 2007, and for surprise of everyone, it turn out the light intensity after the opaque material in their experiments was orders of magnitude bigger than expected. Following these results they succeeded in taking non-invasive sharp pictures of objects hidden behind a screen of opaqueness, the so referred Super Vision in this Nature overview article.
  • LeopoldS on 14 Feb 15
     
    very nice!!!
Thijs Versloot

Engineering three-dimensional hybrid supercapacitors for high-performance integrated en... - 3 views

www.pnas.org/...1420398112

technology energy batteries

shared by Thijs Versloot on 02 Apr 15 - No Cached
jcunha liked it
  • Thijs Versloot on 02 Apr 15
     
    Stacking laser printed supercapacitors (no clean room required btw) has lead to about 1100F/g and thus about 20-40Wh/L. For supercapacitors thats pretty damn good. For reference, Li-ion recently reached 650Wh/L. The gap is closing, although for supercaps of this type the theoretical maximum is 1400F/g.
Thijs Versloot

Ultrafast collisional ion heating by electrostatic shocks - 0 views

www.nature.com/...ncomms9905.html

shared by Thijs Versloot on 23 Nov 15 - No Cached
jcunha liked it
  • Thijs Versloot on 23 Nov 15
     
    Collisionless electrostatic shocks (CES) are the dominant process in heating a plasma when using high power lasers. It turns out that ion-ion collisions actually only play a small role. The ability to create small regions of very high ion energy density on time scales shorter than that of hydrodynamic expansion will be of interest in attempts to understand the processes involved in inertial confinement fusion.
albertosantos

A Cloaking Device for Transiting Planets - 5 views

mnras.oxfordjournals.org/...mnras.stw672.full.pdf+html

technology science space fun

shared by albertosantos on 02 Apr 16 - No Cached
  • albertosantos on 02 Apr 16
     
    Cloaking Laser could hide us from "evil aliens "
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