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Scientists Create New "Lightsaber-Like" Form of Matter

First time accepted submitter loftarasa writes "A group of scientists led by Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic have developed a form of matter by binding massless photons together in a special kind of medium to create 'photonic molecules', effectively bringing us a bit closer to a world with lightsabers. 'The discovery, Lukin said, runs contrary to decades of accepted wisdom about the nature of light. Photons have long been described as massless particles which don't interact with each other – shine two laser beams at each other, he said, and they simply pass through one another. "Photonic molecules," however, behave less like traditional lasers and more like something you might find in science fiction – the light saber.' The work is described in Nature (paywalled)."

175 comments

  1. Do we really want light sabres in untrained hands? by Anonymous Coward · · Score: 5, Funny

    Street justice can get pretty rough.

  2. Use the force, Lukin by ciaohound · · Score: 5, Funny

    Oh yeah.

    --
    Oh, yeah, it's not easy to pad these out to 120 characters.
    1. Re:Use the force, Lukin by sideslash · · Score: 1

      What about Dr.[th] Vladan?

    2. Re:Use the force, Lukin by girlintraining · · Score: 2

      It's paywalled. How about coming over to the dark side, Luke?

      --
      #fuckbeta #iamslashdot #dicemustdie
    3. Re:Use the force, Lukin by Anonymous Coward · · Score: 0

      Fuck you and fuck Star Wars. Anyone over the age of 8 who is still into Star Wars is nothing more than a fucking faggot.

      How appropriate, because most 8 year olds can come up with better insults than you evidently can, you swivel-eyed, knock-kneed tosspot.

    4. Re:Use the force, Lukin by Anonymous Coward · · Score: 0

      Darth Vladan, you mean?

    5. Re:Use the force, Lukin by Anonymous Coward · · Score: 0

      Use the laser cooled rubidium atom photonic push-pull force says Kool-Aid man!

    6. Re:Use the force, Lukin by SleazyRidr · · Score: 1

      Thank you for explaining the joke. I don't know how I would ever have made the connection without you.

  3. Re:STEVEN SPIELBERG HERE !! by geekoid · · Score: 1

    What a doof! everyone knows Steven Spielberg created Firefly, not Star Wars.

    --
    The Kruger Dunning explains most post on /. http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
  4. Unfortunately, you need real molecules to do this by TwineLogic · · Score: 4, Informative

    As the photons enter the cloud of cold atoms, Lukin said, its energy excites atoms along its path, causing the photon to slow dramatically. As the photon moves through the cloud, that energy is handed off from atom to atom, and eventually exits the cloud with the photon.

    These are not photons in free space being described. These are photons which have excited electron orbitals in some material.

  5. massless photons vs black hole by martyb · · Score: 5, Interesting
    Slightly OT question but TFA mentions that photons are massless particles. I've read that elsewhere, too.

    I've also heard that black holes are so massive that the force of gravity does not let anything escape including light.

    So, if photons have no mass, how do black holes keep the photons from escaping?

    1. Re:massless photons vs black hole by ChronoReverse · · Score: 5, Informative

      Because it turns out you don't need mass to be affected by gravity.


      A smart guy called Einstein did a lot of explaining about this.

    2. Re:massless photons vs black hole by gl4ss · · Score: 1

      it's not the spoon that bends but the space around the spoon. some shit like that.

      would have posted anon but damn time limits on slashdot..

      --
      world was created 5 seconds before this post as it is.
    3. Re:massless photons vs black hole by Anonymous Coward · · Score: 5, Interesting

      I'm no expert.

      But I think it has less to do with gravity directly effecting things, and more to do with the gravity of the singularity simply bending space to the degree that things move into it. Thus, anything traveling through that warped space would be effected.

    4. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      An interdimensional rift rather than a force of attraction.

    5. Re:massless photons vs black hole by l0ungeb0y · · Score: 2

      Yes, but there is no spoon, so how can you possibly bend the space around it?

    6. Re:massless photons vs black hole by HornWumpus · · Score: 4, Informative

      Photons have no _rest mass_ or they couldn't go the speed of light. Their mass is their energy which is a function of their frequency.

      --
      John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
    7. Re:massless photons vs black hole by joe_frisch · · Score: 5, Informative

      Physicists - please cover your ears, I'm trying to simplify.

      When particle move near the speed of light their mass increases. At the speed of light it becomes infinite. Imagine a very light particle, moving very fast. By making it move near C I can get any mass I want. So now imagine i make the original particle lighter, an keep moving it faster in such a way that its moving mass stays the same. In the limit a particle with zero mass moving at the speed of light can have some moving mass. That is how a photon works.

      Gravity will bend light, but the effect is very weak because light is moving very quickly. Gravity around a black hole is so strong that it will stop even light.

      Real relativity and general relativity changes this a little, but the basic idea is the same. Photons are very light -> massless. They move very fast -> speed of light, so they have mass from their motion. Gravity doesn't bend light much - but black holes have very strong gravity so they do bend light.

    8. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      The shape of spacetime.

    9. Re:massless photons vs black hole by XiaoMing · · Score: 4, Informative

      Slightly OT question but TFA mentions that photons are massless particles. I've read that elsewhere, too.

      I've also heard that black holes are so massive that the force of gravity does not let anything escape including light.

      So, if photons have no mass, how do black holes keep the photons from escaping?

      Gravity bends the fabric of space-time itself, which the photons are travelling through.

    10. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      There's no space there to band...

    11. Re:massless photons vs black hole by justthinkit · · Score: 4, Informative
      Gravity around a black hole is so strong that it will stop even light.

      .
      The BH does not stop light. It changes the path light takes so it never leaves the black hole's event horizon.

      --
      I come here for the love
    12. Re:massless photons vs black hole by dreamchaser · · Score: 1

      They are massless, but they are still affected by the curvature of space, which according to relativity is the actual 'cause' of gravity. The space at the event horizon is curved such that not even photons can escape.

    13. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Gravitation couples to energy, whether it be rest energy (mass) or kinetic energy (purely, in the case of photons).
      Gravitation is viewed as the deformation of space-time. Both massive and massless particles travel along the shortest paths in this deformed space-time.

    14. Re:massless photons vs black hole by joe_frisch · · Score: 1

      Yes, all timelike curves cross the event horizon and hit the singularity (I think, maybe not for rotating black holes) because of the curvature of space.

        I wanted physicists to cover their ears because I was trying for a vaguely correct explanation that didn't require too much background.

      Even without general relativity you could imagine a concentration of mass what would prevent (newtonian) light from escaping.

    15. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      And spacetime is deformed by energy, whether rest energy or kinetic energy. Two photons will gravitationally interact with each other. In this case, the paths they would chart if they were the only particles in an otherwise flat space-time would be about the size of the observable universe, since they interact so weakly with gravitation and deform spacetime so little.

    16. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Within the "event horizon," within the Schwarzchild radius of the singularity of a black hole, a particle with velocity less than or equal to the speed of light in vacuum will travel along shortest paths between two points in this deformed space-time such that none of the points of that path (called a geodesic) lie outside the event horizon (it is trapped). In fact, all paths will contain the singularity (where all understanding of space-time deformation runs into problems of infinity (all stuff ends up crunched at the singularity, but our current understanding and models become inconsistent and presently unworkable as it is approached.))

    17. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      And interestingly, the Schwarschild radius comes out to the same value whether calculated with Newtonian gravitation or general relativity.

    18. Re:massless photons vs black hole by martyb · · Score: 1, Interesting
      Photons have no _rest mass_ or they couldn't go the speed of light. Their mass is their energy which is a function of their frequency.

      Aaaaah! rest mass == massless, but because of their energy, and e=mc^2, there is, effectively, a mass, which the black hole can act upon... got it! Thanks!

    19. Re:massless photons vs black hole by Princeofcups · · Score: 4, Informative

      Physicists - please cover your ears, I'm trying to simplify.

      Sorry, but I can't let that go, especially since it's been modded up. Just no. Light does not have mass. There is no such thing as "moving mass."

      General relativity: How does a large mass bend light? Because a large mass bends space around it. Light ends up bending around the object, kind of like a banked roadway. A black hole bends space so tightly that if light gets too close (the event horizon), it gets sucked in. That's why we refer to it as a hole.

      --
      The only thing worse than a Democrat is a Republican.
    20. Re:massless photons vs black hole by martyb · · Score: 1

      Physicists - please cover your ears, I'm trying to simplify.

      When particle move near the speed of light their mass increases. At the speed of light it becomes infinite. Imagine a very light particle, moving very fast. By making it move near C I can get any mass I want. So now imagine i make the original particle lighter, an keep moving it faster in such a way that its moving mass stays the same. In the limit a particle with zero mass moving at the speed of light can have some moving mass. That is how a photon works.

      Gravity will bend light, but the effect is very weak because light is moving very quickly. Gravity around a black hole is so strong that it will stop even light.

      Real relativity and general relativity changes this a little, but the basic idea is the same. Photons are very light -> massless. They move very fast -> speed of light, so they have mass from their motion. Gravity doesn't bend light much - but black holes have very strong gravity so they do bend light.

      *This* is what keeps me coming back to /.!

      When I was in college (many moons ago), we covered Newtonian physics, but they only mentioned general/special relativity in passing, and poorly at that. I was exposed to the concept of black holes, newtron stars, and white dwarfs, in my astronomy courses, but again in a superficial, hand-wavy manner. Thank you very much for your clear and lucid explanation!

      So, IIRC, gravity is a relatively weak force, compared to, say, electrostatic forces. And yet, near a black hole, gravity is so intense that even light cannot escape. Such a maelstrom of insanely massive currents and magnetic fields must be swirling around black holes, pulsars, etc.! That we can ponder about, and even quantify, such things... simply amazing!!

    21. Re:massless photons vs black hole by ebyrob · · Score: 2

      I think momentum is an important term to remember here. Photons may not have rest mass, but they do have momentum. (in classical physics: p = m * v)

    22. Re:massless photons vs black hole by Smonson78 · · Score: 1

      A black hole bends space so tightly that if light gets too close (the event horizon), it gets sucked in. That's why we refer to it as a hole.

      This still doesn't make sense to a non-physicist like me. You haven't explained why the photon can't just go into the curved area of space and straight out the other side.

    23. Re:massless photons vs black hole by Anonymous Coward · · Score: 3, Insightful

      becasue the curved area of space is bent so far that it never comes out the other side.

      Black holes are where the universe divided by zero.

    24. Re:massless photons vs black hole by Anonymous Coward · · Score: 0, Troll

      no, photons have 0 rest mass. Their energy is not mv^2 kinetic energy. You can tell because photons have 0 rest mass, all move at the same speed, and have different amounts of energy depending on how much energy they have.

      Gravity does not "bend light". Light always, always, always goes along lightlike paths. Gravity bends spacetime.

      A "black hole" is a region of space in which there is no lightlike geodesic that leaves the black hole (and continues to positive lightlike infinity).

      In conclusion, shut up if you don't know what you're talking about, you colossal faggot.

    25. Re:massless photons vs black hole by ultranova · · Score: 1

      So, if photons have no mass, how do black holes keep the photons from escaping?

      Because black holes are undead stars reaching from their graves with claws of gravity, and we all know that if you try to run from the monster you end up running right at it, which is what happens to photons. Then they get eaten and are never seen again.

      --

      Forget magic. Any technology distinguishable from divine power is insufficiently advanced.

    26. Re:massless photons vs black hole by jezwel · · Score: 1

      Light does that further out from the center of the black hole - it is bent by the gentle curvature, but still comes out the other side - just like a marble might on a trampoline with someone standing on it. Gravitational Lensing. The 'black' part of black hole is from where the 'slope' is so great that light gets stuck circling the singularity at the center, and therefore cannot escape. (That might be an elephant making your trampoline into basically a pit).

    27. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Gravity couples to energy. Photons are energy without mass. Mass also has an energy equivalent (E=Mc^2).

    28. Re:massless photons vs black hole by joe_frisch · · Score: 4, Informative

      A photon has mass energy. If I take an empty box made of perfect reflectors and add a photon, it will weigh more (by a tiny bit). It will have more inertia since inertial and gravitational mass are as far as we can tell exactly equivalent (as required if you use a curved space model of gravity).

      In any case, words are a bit fuzzy. A photon has 4-momentum and the mass like term (or time like term if you wish) is non-zero.

      btw- curved spacetime is a perfect model for all existing measurements involving gravity, but is incompatible with quantum mechanics at very (unreachable) high energies.

    29. Re:massless photons vs black hole by joe_frisch · · Score: 1

      I was taking a photon as the limit of a missive particle where you increase the velocity and decrease the mass in such a way that the mass-energy remains constant.

      And I am NOT colossal, and my sexuality is not a matter of public record.

      Otherwise though you are correct, but I was trying for an explanation that a non-scientist could understand.

    30. Re:massless photons vs black hole by Sabriel · · Score: 4, Informative

      Imagine a gigantic sheet and stretch it out flat and taut. This is space. Take a marble and set it rolling across the sheet. This is your light particle. It reaches the other side.

      Now attach a weight under the sheet so that it dips in the middle. This is the gravity of a star. Take the marble again and roll it across the sheet so it goes through the dip and keeps going. The curved path of the marble describes the influence of gravity upon the light particle.

      Now imagine the weight is so heavy that the dip is effectively vertical at its heart, a hole in the sheet. This is the gravity of a black hole. Take the marble again and roll it across the sheet. If it gets too close, it rolls into the hole and doesn't come out.

    31. Re:massless photons vs black hole by MickLinux · · Score: 1

      Photons have no rest mass. They do have mass, though. In line with that, I should also note that photons do not exist in their own system, when in transit through high vacuum. That is, within their own system, the time - dilated length of time that they experience (while travelling at the speed of light) approaches zero.

      Of course, photons seldom travel at the speed of light. And their own existence seems to use non-photons as their space.

      --
      Correct Horse Battery Staple: 72 bits of entropy. Enter "Correct H" into google. When it generates the phrase, that's
    32. Re:massless photons vs black hole by MouseTheLuckyDog · · Score: 0

      Why because the original question was hard ( it's not ) or because it was stupid ( very much so ).

    33. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      I don't believe gravity pulls photons into a black hole. The space around a black hole becomes increasing warped such that a photon traveling in a straight line curves into the hole by following space. This isn't gravity, per se, but severe warpage of space itself. Much like the "big bang" created space in an outward fashion, as if it were growing like cells, making matter appear to move faster than light. Black hole has the reverse effect with space gone (or nearly so) at the center.

    34. Re:massless photons vs black hole by michelcolman · · Score: 1

      have different amounts of energy depending on how much energy they have

      Makes sense to me.

    35. Re:massless photons vs black hole by Jesrad · · Score: 1

      Even better, black holes are time-stasis bubbles. Studying them from a spacetime metric POV and adding entropy considerations make for a fascinating journey.

      --
      Maybe we deserve this world ?
    36. Re:massless photons vs black hole by Pranadevil2k · · Score: 1

      Instead, try to realize the truth. You will see it is not the space around the spoon that bends, it is only yourself.

    37. Re:massless photons vs black hole by drkim · · Score: 1

      So, if photons have no mass, how do black holes keep the photons from escaping?

      They don't. The gravitational field created by the black hole bends space-time.

      Think of a marble rolling around a flat sheet. The marble always moves in a straight line.

      Now imagine the sheet has a big depression in it. The marble still rolls 'straight' but as it follows the dip in the sheet, it 'curves' into the dip.

      Now, to the marble, it feels like it's still going straight.
      To an outside observer it looks like the marble is tracking into the dip.

    38. Re:massless photons vs black hole by idji · · Score: 1

      photons travel in "straight lines" at the speed of light. inside a blackhole the "straight lines" are loops or relativistically twisted that a photon would take an eternity to reach the event horizon. From the photon's own perspective all is normal, but not from the observer outside

    39. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      That is the simplified model.
      It is unwise to use that model close to or inside the event horizon.
      People doing that have already cooked up enough crackpot theories.

      The singularity model works best when reasonably far away from the black hole.

    40. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      More interestingly, you're wrong about that. It's off by a factor of two.

      If you're interested that it's just a factor of two, I suggest you review dimensional analysis again.

    41. Re:massless photons vs black hole by AGMW · · Score: 1
      >Photons have no _rest mass_ or they couldn't go the speed of light.

      So, we keep measuring the speed of light more and more precision, and what if our precision with that measurement simply isn't up to the job, and light actually travels at ever so slightly less than the (theoretical) speed of light.
      Photons at rest could then have a Really (really really ...) small mass ...

      ebyrob> I think momentum is an important term to remember here. Photons may not have rest mass, but they do have momentum. (in classical physics: p = m * v)

      Hang on ... isn't momentum mass times velocity?
      Momentum? why you keep using that word?

      --
      Eclectic beats from Leeds, UK
      handmadehands.co.uk
    42. Re:massless photons vs black hole by angel'o'sphere · · Score: 1

      Photons have no "rest mass".
      But as every photon is moving it has 'kinetic' mass, h*v / (c^2).

      --
      Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
    43. Re:massless photons vs black hole by angel'o'sphere · · Score: 1

      You are wrong, read wikipedia or google for "photon mass".

      --
      Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
    44. Re:massless photons vs black hole by AGMW · · Score: 1

      Gravity bends the fabric of space-time itself, which the photons are travelling through.

      Yeah, I get that, but I thought that the gravitational attraction was between the relative masses of the two objects. Presumably, therefore, any massless doodah wandering by would be unaffected by the masses of thingamejigs it might pass.
      That being so ...

      A mass-less photon (at speed) whizzing past a superhumongous 'body' would be unaffected by it, gravitationally, regardless of how massive the body was, if it had no mass. Ergo - a photon at speed has mass.

      Where does that mass come from. If it comes from momentum, then it must have mass at rest (mass * velocity).

      --
      Eclectic beats from Leeds, UK
      handmadehands.co.uk
    45. Re:massless photons vs black hole by idkk · · Score: 0

      Bear with me for a moment:

      If inertial and gravitaional mass are exactly equivalent, and a photon has momentum (granted, it is 4-momentum - so we are dependent here upon the frame of reference) and (crudely - and, you are going to say, incorrectly) momentum is mass times velocity, then from the fact a photon has momentum we can deduce that it has mass (p=mv). From Einstein's equations, however, we can deduce that it cannot have any rest-mass, as at speed-of-light (c) movement it would have infinite moving-mass.

      BUT suppose - just for a moment - two heretical things: firstly that a photon DOES have rest mass (very tiny, but non-zero), and secondly that light does NOT travel at c - the upper speed limit for the universe - but very, very slightly less than that. We speak of c as being "the speed of light in vacuum" but we also speak of there being no true vacuum anywhere in the universe. Even intergalactic space contains some matter - per cubic metre not much, but some. So we have never - and I really do mean never - measured the actual speed of light in vacuum. We have measured the speed of light in "close to vacuum" (and in glass and in water and in air and lots of other media too), but never actually "in vacuum".

      Still bear with me: so what if the rest-mass of a photon is, say ten to the fortieth power smaller than the mass of a neutrino (... when I was a child I was told neutrinos have no mass - but that's changed!), and that the maximum speed of light actually occuring in the universe is one ten to the fortieth part smaller than c (the ultimate speed limit)? Then we could still have Einstein (scientifically good) and we could think of photons as having mass (ordinary common sense good) and we can get rid of Black Holes (I've never liked them - but that, I know, is not a good argument) and instead have very, very deep (but NOT infinitely deep) gravity wells.

      Photons are very light - but NOT massless. Photons always move at LESS than the (unmeasured) upper speed of light..

      OK - you can stop bearing with me now.

      --
      Ian D. K. Kelly

      idkk Consultancy Ltd.

      "Quality through Thought"

    46. Re:massless photons vs black hole by Anonymous Coward · · Score: 5, Informative

      No, photons do NOT have mass. You can only go at the speed of light (photon is light) if you do not have mass.
      Photons have only energy associated with their speed. But NO energy associated with any mass.

      And you do not need mass to be affected by gravity. Gravity is a distortion of space, and therefore everything in space (with mass and without) is affected by gravity.

      This blog post explains everything in detail in a simple way:
      http://profmattstrassler.com/articles-and-posts/particle-physics-basics/mass-energy-matter-etc/more-on-mass/the-two-definitions-of-mass-and-why-i-use-only-one/]

    47. Re:massless photons vs black hole by Anonymous Coward · · Score: 1

      The thing is, if E=mc^2 is correct, then mass is energy. It's just that people get hung up on semantics because the packetized form of energy appears to behave different than freely flowing form.

      If you look at gravity as a function of energy density and it's effects similar to those of electric charge and capacitance, it just might make a little more sense. (Like a capacitive plate, the intensity of gravity also has a relationship with surface area.) Apparently space itself can hold only so much energy before it deforms under a sort of pressure, and it's that deformation that causes a space-time distortion to occur. (Yes time too. For light to bend on its path with no acting medium such as glass, time has to slow down with a gradient that is stongest at the center of the mass. The speed of light in a vacuum does not change (at least in a way that is observable while under influence of a gravitational field), and since speed is d/t, then time has to do the bending work. Another odd thing is that gravity and time are also linked, so a second passing in a black hole isn't the same as a second passing here.)

    48. Re:massless photons vs black hole by sjames · · Score: 1

      When a particle is said to have no mass, they really mean it has no mass at rest. It still has the mass associated with it's energy and photons have energy.

    49. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      So, we keep measuring the speed of light more and more precision, and what if our precision with that measurement simply isn't up to the job, and light actually travels at ever so slightly less than the (theoretical) speed of light. Photons at rest could then have a Really (really really ...) small mass ...

      Then different energies of light would have different speeds. We can measure the difference in speed between two different wavelengths a lot more precisely than we can measure the absolute speed of any given single photon (although absolute measurements ultimately come down to comparing to the sodium line used for the definition of meter and second...). Light from distance sources has been found to travel at the same speed to incredibly small lower bounds. This hasn't stopped attempts at extensions to particle theories being proposed that include a massive photon, but the implications of such theories all would amount to an incredibly small photon mass, below the lower bounds even seen with the astronomical observations.

      isn't momentum mass times velocity?

      Only in Newtonian mechanics. The definition is updated in special relativity: E^2=p^2c^2+m0^2c^2, which in the low velocity limit gets you back that momentum is mv. You don't even need to evoke relativity to see that momentum is more general than p=mv though, as Maxwell's equations show that electromagnetic fields carry momentum (although the Lorentz invariance of those equations closely connects them to relativity).

    50. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      So we have never - and I really do mean never - measured the actual speed of light in vacuum. We have measured the speed of light in "close to vacuum" (and in glass and in water and in air and lots of other media too), but never actually "in vacuum".

      Quantum field theory, and quantum electrodynamics in particular for things like the photon, already take that into account: that we can't measure the properties of particles moving without interacting with the false vacuum. Those theories already take such interactions into account, and currently represent some of the most precise predictions confirmed by experiments to date.

    51. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Your logic may look sound, but the premises are not correct in the sense you are trying to conflate together old definitions with newer (still 100 years old...) theories which generalized some of those definitions. This is on par with arguing about the annihilation energy of a positron-electron pair assuming energy is only of the form 0.5mv^2, or trying to examine laser cooling of atoms using caloric theory.

    52. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Except what the previous AC said applies to large areas outside of the event horizon too. There are regions where large parts of the light approaching the black hole will not escape, and instead take a trajectory that takes the light closer to the event horizon and not just some hyperbolic classic orbit. This is coming pretty close to testable due to the impact it has on accretion disk modeling and not so distant direct observation of large black holes via radio telescope interferometers.

    53. Re:massless photons vs black hole by Bucc5062 · · Score: 1

      This is why I love /. That was a great article. Thank you for posting it. Back (way back) in high school I wanted to by a physicist. Going into my freshman year of physics I quickly discovered two things. One, physics is damn hard and what the hell is calculus. Two, I was introduced to computers by my calculus professor and it was love at first sight. I dumped physics (clearly she moved on to better things) and have been with computers ever since. Still I love keeping in touch with the general world of physics and articles like this is a sweet morsel to enjoy.

      Photons have mass...go figure.

      --
      Life is a great ride, the vehicle doesn't matter
    54. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Wow! Linking to a slashdot comment to prove a point? What? Is Wikipedia too good for you?

      Photons have no "rest mass".
      But as every photon is moving it has 'kinetic' mass, h*v / (c^2).

      Also, the slashdot comment indicates 'kinetic mass', but doesn't survive a unit check... Wherever this equation came from, its wrong.

      Here are some resources for you:
      http://www.askamathematician.com/2010/09/q-how-can-photons-have-energy-and-momentum-but-no-mass/
      http://pveducation.org/pvcdrom/properties-of-sunlight/energy-of-photon
      http://web.utk.edu/~cnattras/Phys250Fall2012/modules/module%201/photons.htm
      http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html

    55. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Posts like this being modded up is another reason I just troll Slashdot anymore. There's is nothing insightful or informative here. The entire post is a trainwreck of how a 5th grade student would try to explain the answer to the question for his science class at 9:45 the night before the homework is due. The fact that this is modded up is somewhere between a sick sad joke and outright misinformation. Even a politician couldn't make up such nonsense.
       
      For the love of God, Joe, STFU and let people who passed high school physics talk. I seriously don't know how you ever got this much bullshit in your head but I really hope your friends, if you have any, aren't hanging on your every word about science because you're dead wrong. I have a nephew who tries to pull the same crap and his friends all adore his "intelligence" even tho 99% of what he says is wrong. Anytime I call him out on it he just stomps away and pouts.
       
      Turn off the video games and open a book. Not even the "Science" Channel. A frigging book! You moron.

    56. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Photons propagate with a finite velocity in vacuum, the speed of light. Energy density (provided by the mass of the black hole) curves space making the distance the photon has to travel longer than if there was not an energy density present. A black hole increases this distance more rapidly than the photon can travel through it. Therefore the photon never escapes.

    57. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      They clearly meant nu for the frequency, not v, which looks the same on something like Slashdot. Energy of a photon is E=h*nu, and the mass equivalent is then derived from E=mc^2 to get m=h*nu/c^2

    58. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Ever been at the mall and see one of those large convex coin things. You put a coin in the slot and it circles about the convex surface until it dumps into the hole in the center?

      Black holes are kind of like that. If you envision space as a flat plane the coin would roll in a straight line. Gravity however distorts that plane into a different shape and when light enters into that distorted plane it will curve around that surface. If it enters at an angle that is acute enough it never escapes.

      Google for a "coin vortex" or "coin gravity well". Anyhow that is all I remember from high school science some decades ago.

    59. Re:massless photons vs black hole by ceoyoyo · · Score: 1

      E=mc^2. Rearranged, m = E / c^2.

      A photon has no rest mass (or energy). It does have energy associated with it's motion, and energy is equivalent to mass. You can use that mass/energy as the term in the classical momentum equation, or calculate the non-classical momentum directly based on it's frequency.

    60. Re:massless photons vs black hole by joe_frisch · · Score: 1

      The standard image in popular science of a bowling ball distorting a rubber sheet isn't very good at conveying what is going on. It is not space, but rather space-time that is curved - you need to imagine the curvature of 4-dimensional space time - which normal humans like me can't do.

      Kip Thorne had an example that was easier to think about. Imagine an orange with 2 ants at the equator. In this model space is 1 dimension, east / west. Time is latitude. So if the ants are not "moving" in space, they will walk northward as they go forward in time. After a while as they near the north pole the will find themselves closer together than when the started. Some "force" has drawn them together.

      If we extend this: when an ant moves it walks east or west, but since it can't move faster than "light" in this model, it is still mostly moving north. If at all points it can only go a small angle away from north, no matter what it does it will end up at the "singularity" at the north pole of the orange.

    61. Re:massless photons vs black hole by joe_frisch · · Score: 1

      Yes gravity is very weak, but it is unique among the forces in that there are no "negative" gravity charges and that like-charges attract. The electrical forces between 2 electrons are enormously stronger than the gravitational forces. If I try to collect a lot of electrons in one place though, those forces will push them apart.

      If I take neutral particles (say atoms), the gravitational force of each one is incredibly tiny - but it is attractive. If I get a LOT (like the mass of a planet together), they will attract each other and their gravity will add and become stronger than any of the other forces.

      You are right that a real black hole is likely anything but black - it is probably surrounded by clouds of relativistic hot gas - and "black holes" are likely the engines at the center of the brightest objects in the universe .

    62. Re:massless photons vs black hole by joe_frisch · · Score: 1

      Photons could have a tiny rest-mass. You can't distinguish experimentally between a particle with a tiny mass moving very near the speed of light and a massless particle moving at the speed of light (this was part of my point in talking about the limit as the rest-mass gets small). People have put limits on this though and if the photon has rest mass it is TINY. Really really tiny.(I see a paper showing 1e-54 kg).

      Your neutrino comment is a good example - it was thought to be mass-less, and to move at the speed of light, but later experiments showed that it had a small rest mass (still huge compared to the limit for the photon) and that it therefore must move slightly slower than the speed of light.

      You can still have black holes even if photons have rest mass. Gravity would work essentially the same way. Enough matter in a small enough space would bend space so that all time like curves could not escape. Or put classically the gravity would be so strong that no object could escape -incluing the almost-speed-of-light massive photons.

    63. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      If you try to think of it classically, as in the gravitational force being proportional to the masses of the two bodies, then yes, you arrive at zero force on a massless photon. However, the actual "acceleration" of the photon is what matters. Classically, acceleration is force / mass. If mass is zero, then acceleration is undefined - it could be zero, it could be infinite. This just shows that classical mechanics can't describe massless particles, not that photons must have mass. A gravitational field accelerates all objects at the same rate, in the limit as mass approaches zero.

    64. Re:massless photons vs black hole by joe_frisch · · Score: 1

      What is the part you think is wrong? This sort of thing is difficult to explain. The "correct' description in fairly recent physics is that gravity is due to the exchange of spin-2 gravitons. Maybe by now there are even more exotic explanations. They are way beyond me - and anyone else not in the field.

      General relativity is a pretty good description - it matches all observations and experiments, the only (big) problem is that it is not compatible with quantum mechanics at very large energy scales. Quantum compatible descriptions of gravity lead to gravitons, and then the more exotic stuff that I don't understand at all.

      General relativity describes the curvature of 4-dimensional space time. This is really difficult to visualize. Most visualizations (like the bowling ball on a rubber sheet) are showing just the curvature of a 2 dimensional spatial object into 3 spatial dimensions. Clever people who see this are confused because it doesn't seem to make sense - and they are right. Its a bad model. Other than the Kip Thorne ants on an orange model I gave above, (which isn't great either), I haven't seen a good intuitive model of curved space time.

      Meanwhile many of the posters are not physicists. So I try to come up with an explanation that doesn't involved curved space time but which at least gives a vague idea of what is going on. Of course it is wrong. General relativity is wrong . Gravitons are wrong - we don't have a working theory of quantum gravity yet. All we have are models that fit experiments under some conditions.

      Remember that all this thread was started by someone asking how gravity could affect "massless" photons. Its a good question. Since then it has evolved into a discussion of black holes and as the discussion gets more detailed, a better description is needed.

      Are you so sure what your nephew says is wrong?

      If you didn't post as AC I could at least see which of the objections were from you and which were from other people. I can't tell if you are just complaining or are contributing since there could easily be more than one AC on this thread. Why not use your real name like I do?

    65. Re:massless photons vs black hole by ZombieBraintrust · · Score: 1

      Your thinking of F = G*m1*m2/r^2
      if m1 is 0 then F would be 0 in newtonian physics. Einstein General Relativity replaces this equation. The theory was proved when Einstein showed that light bent around the sun. (measured during an eclipse)

    66. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Stop thinking it as a the speed of light, and as the maximum speed limit of the Universe.

    67. Re:massless photons vs black hole by TemporalBeing · · Score: 1

      Photons at rest could then have a Really (really really ...) small mass ...

      Well, theoretically (and only theoretically) photons could have a gigantive rest mass that is 100% converted to energy when in motion. The problem we normally face is that we cannot convert (or think of how to convert) 100% to 100% energy in a manner required to do that - t0 at rest, t1 in motion, a=c over t0 to t1 and (t1-t0) is nearly zero (e.g. 0.000.....0001 or 1*10^-infinity).

      --
      Truth is like the sun. You can shut it out for a time, but it ain't goin' away. - Elvis Presley (source: imdb.com)
    68. Re:massless photons vs black hole by HornWumpus · · Score: 1

      In addition to the point about different energies having different speeds.

      If they had _any_ rest mass at all their mass would be approaching infinity as they approached the speed of light.

      --
      John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
    69. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Some of the Standard Model extensions the presuppose a massive photon give upper bounds around the 10^-45 g range, which would allow for a photon to stay less than 0.1% of the mass of a neutrino while still speed separated from the speed of light over a billionth of precision of the best tests related to c. But outside of a test for such esoteric theories, the implications are mostly nil, and such a small mass would be inconsequential to 99% of science and engineering.

    70. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      Because the energy/mass of the black hole is warping space around it. Everything falls into this metrical singularity. The photons travel within this space. There is an energy mass equivalence you're missing. Photons have energy

    71. Re:massless photons vs black hole by Anonymous Coward · · Score: 0

      No, photons do NOT have rest mass. You can only go at the speed of light (photon is light) if you do not have rest mass.

      FTFY

      Photons have only energy associated with their speed.

      This is so misguided, I'm not sure how to fix it. A photon's energy is more correctly said to be associated with its frequency than its speed.

      This blog post explains everything in detail in a simple way:
      http://profmattstrassler.com/articles-and-posts/particle-physics-basics/mass-energy-matter-etc/more-on-mass/the-two-definitions-of-mass-and-why-i-use-only-one/]

      I see now why you're so confused. This blog is using the term mass to mean rest mass, so you think photons therefore have no mass. Photons have energy. Energy is mass. (Remember e = mc^2?) Therefore photons have mass and are affected by gravity. It's as simple as that. I'm unaware of any massless objects so I couldn't say whether they would be affected by gravity or not.

    72. Re:massless photons vs black hole by ChronoReverse · · Score: 1

      Congratulations, you've taken an extremely shallow knowledge of relativistic mass and assumed it's actually relevant.

    73. Re: massless photons vs black hole by nbritton · · Score: 1

      So, if photons have no mass, how do black holes keep the photons from escaping?

      Good question, photons are energy, E(eV) = 1.24 / Î(μm).... the answer is m = E / c^2. Photons are like atoms, individually they are insignificant, because c^2 in is so large.

    74. Re:massless photons vs black hole by angel'o'sphere · · Score: 1

      Pfft ...

      If photons had no mass, something like a photovoltaic cel would not work.

      The one with "shallow" ... or more precisely "no knowledge" about photons is you.

      --
      Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
    75. Re:massless photons vs black hole by Smonson78 · · Score: 1

      Thanks for attempting to explain this concept in layman's terms. I appreciate it very much. So from what I understand, the ants never actually reach the north pole of the orange because time at the singularity gets slower and slower from the reference point of the universe outside the event horizon, and that's why they can't cross the centre of the gravity-hole and come back out the other side?

  6. Well by abroadwin · · Score: 2

    Good thing that lightsaber quote isn't getting out of hand.

  7. Dear University PR Heads: by Anonymous Coward · · Score: 5, Insightful

    Science is cool enough without ridiculous hyperbole.
    That is all.

  8. You know that if they actually ever do make one... by mark-t · · Score: 3, Funny

    ....... the number of accidental amputees is going to skyrocket.

  9. Re:STEVEN SPIELBERG HERE !! by JustOK · · Score: 1

    Oh, come on! It was created by Gene Roddenberry!

    --
    rewriting history since 2109
  10. Re:You know that if they actually ever do make one by chromas · · Score: 5, Funny

    That's right...'accidental'.

  11. Starwards the wrong cultural reference. by BLACKMIST · · Score: 1, Interesting

    So I'm reading this, and they do the whole lightsaber thing- they explain this opens the possibility of -crystals made of light-

    They have completely missed the cultural reference. Clearly this needs a Tolkien reference. This is Feanor's Silmaril. Why can't they see the obvious?

    Oh, and new form of matter made of energy- there's that too. That didn't even make the title.

    Seriously though, howto simerils.
    _B

    1. Re:Starwards the wrong cultural reference. by Anonymous Coward · · Score: 0

      So I'm reading this, and they do the whole lightsaber thing- they explain this opens the possibility of -crystals made of light-

      They have completely missed the cultural reference. Clearly this needs a Tolkien reference. This is Feanor's Silmaril. Why can't they see the obvious?

      Oh, and new form of matter made of energy- there's that too. That didn't even make the title.

      Seriously though, howto simerils.
      _B

      It works in star wars too. Lightsabers get their color and power from crystals http://starwars.wikia.com/wiki/Lightsaber_crystal

    2. Re:Starwards the wrong cultural reference. by Anonymous Coward · · Score: 0

      Energon dude! energon!

  12. This is highly illogical. by atari2600a · · Score: 3, Informative

    Everyone knows photons were meant to be shot out of phasers, not for dueling with lasers.

    1. Re:This is highly illogical. by msobkow · · Score: 1

      Phasers are not lasers.

      --
      I do not fail; I succeed at finding out what does not work.
    2. Re:This is highly illogical. by msobkow · · Score: 1

      By that I mean that directed energy weapons are highly unlikely to use photons as the means of deploying their energy bursts. Magnetic bubbles of plasma or streams of electrons or even subatomic particles would be far more likely to be used.

      Lasers, on the other hand, shoot photons.

      --
      I do not fail; I succeed at finding out what does not work.
    3. Re:This is highly illogical. by TheCarp · · Score: 2

      Really? Because of all those things, the only one that is currently actually being used as a directed energy weapon is...in fact, the laser.

      At least so far as "directed energy" doesn't count the acceleration of metal projectiles or explosive shells, which still take the cake for directed energy burst delivery.

      --
      "I opened my eyes, and everything went dark again"
    4. Re:This is highly illogical. by Crimey+McBiggles · · Score: 1

      Whoever modded this guy informative must not understand what "informative" means. Please mod funny or troll.

      --
      Crimey
    5. Re:This is highly illogical. by avandesande · · Score: 1

      Better to put them in a torpedo....

      --
      love is just extroverted narcissism
    6. Re:This is highly illogical. by cellocgw · · Score: 1

      Lasers, on the other hand, shoot photons.

      Yer a frickin' libral. Everyone knows that lasers don't shoot photons! People with a laser shoot photons.

      --
      https://app.box.com/WitthoftResume Code: https://github.com/cellocgw
    7. Re:This is highly illogical. by martinQblank · · Score: 1

      Repeat after me: "Photons go in torpedoes". Thank you.

  13. Light Saber? by OhSoLaMeow · · Score: 5, Insightful

    Hokey religions and ancient weapons are no match for a good blaster at your side, kid.

    --
    They can take my LifeAlert pendant when they pry it from my cold dead fingers.
    1. Re:Light Saber? by Slagothor · · Score: 1

      Damn you. Damn you to hell. I was logged out and needed to log in to post that. You beat me to it you steely eyed missile man. :)

    2. Re:Light Saber? by SternisheFan · · Score: 1

      Hokey religions and ancient weapons are no match for a good blaster at your side, kid.

      Of course these light-sabers will be made for a more civilized time...

      (ducks!)

    3. Re:Light Saber? by ranjix · · Score: 1

      In the best Greedo voice: "I find your lack of faith disturbing..."

      Too much?

      --
      I had another sig before, but this one is better
  14. Re:Unfortunately, you need real molecules to do th by ColdWetDog · · Score: 4, Funny

    These are not the photons you are looking for.....

    --
    Faster! Faster! Faster would be better!
  15. Cue the comedy by nurb432 · · Score: 1

    While everyone misses the science. Sad state of affairs of the so called 'geek'.

    --
    ---- Booth was a patriot ----
    1. Re:Cue the comedy by ThatAblaze · · Score: 3, Insightful

      Science?? Not everyone has a paid subscription to Nature. Without that there is hardly anything to miss!

    2. Re:Cue the comedy by nurb432 · · Score: 1

      And you call yourself a nerd.

      --
      ---- Booth was a patriot ----
  16. Re:STEVEN SPIELBERG HERE !! by Anonymous Coward · · Score: 5, Funny

    Use the force Harry!

    -Gandalf

  17. Re:You know that if they actually ever do make one by mark-t · · Score: 2

    Most people, I would expect, would not intentionall dismember themselves.

  18. the summary is garbage... by slew · · Score: 5, Interesting

    From what I can tell, they are simply creating a system of quantum-mechanically entangled photons, not a "molecule" of photons...

    Apparently trick is that they created a medium (a laser cooled "gas" of rubidium atoms), and excited it with photons from a laser at a frequency that created a condition for the formation of a Rydberg state in the gas. This state is basically kind-of a pseudo-atom (i.e., a group of atoms that behave somewhat like a "scaled-up" atom). The gas made up of the pseudo-atom has a different apparent index of refraction than the unexcited medium looks to the first photon but it can effectively keep a second photon nearby the first photon in a type of quantum entanglement

    This is what is described as a photon "molecule". Of course the energy levels required to create a similar Rydberg state in air (at room-temperature) would be slightly different orders of magnitude because you are pumping in enough energy into the air so that hyper-energized pseudo-molecules of air are resisting your opponent's light sabre... Not so sure you want to be actually holding a device that does that ;^)

    1. Re:the summary is garbage... by Princeofcups · · Score: 5, Informative

      From what I can tell, they are simply creating a system of quantum-mechanically entangled photons, not a "molecule" of photons...

      You can stop reading the summary after "A group of scientists led by Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic..." Everything after that is complete fabrication.

      --
      The only thing worse than a Democrat is a Republican.
    2. Re:the summary is garbage... by quax · · Score: 1

      Second that.

  19. Lightsaber! by manu0601 · · Score: 3, Insightful

    The journalist could not say their finding will cure cancer or obesity in several decades, therefore they sold it as a potential path to lightsabers!

    We would probably not accept such bold tactics from politicians, why do we accept it from scientific journalists?

    1. Re:Lightsaber! by Anonymous Coward · · Score: 0

      You want to cure obesity and cancer? Eat more, like lots more, vegetables, and cut out processed food.

    2. Re:Lightsaber! by mdielmann · · Score: 1

      The journalist could not say their finding will cure cancer or obesity in several decades, therefore they sold it as a potential path to lightsabers!

      We would probably not accept such bold tactics from politicians, why do we accept it from scientific journalists?

      From what I've seen, we do accept such outrageous tactics from politicians. Journalists seem to have realized that they can do the same.

      --
      Sure I'm paranoid, but am I paranoid enough?
    3. Re:Lightsaber! by manu0601 · · Score: 1

      I would add fish to vegetables. A bad omega 3/omega 6 ratio is the root of many diseases: Eicosanoids produced from omega 6 arachidonic fatty acid induces inflamation (which promotes cancer) and adipocytes proliferation. Eicosanoids produced from omega 3 eicosapentaenoic fatty acid (EPA) found in fishes counteract that, by competing with arachidonic acid for the same enzymes.

  20. Hard Light! by d'baba · · Score: 1

    Lucky Rimmer!

    1. Re:Hard Light! by Molochi · · Score: 1

      Great, now I want curry and all the delivery places are closed.

      --
      "The Adobe Updater must update itself before it can check for updates. Would you like to update the Adobe Updater now?"
  21. Re:You know that if they actually ever do make one by Anonymous Coward · · Score: 1

    OH, I'm willing to stipulate that *most* people wouldn't *intentionally* dismember themselves but consider the following:

    1) a surprising number of people actually commit suicide by decapitating themselves with a chainsaw.

    2) think of how many martial art wannabes buy or make their own nunchaku, proceed to flail themselves in the ribs, face and/or groin and then post video proof of their stupidity on youtube. That same demographic would do the same with lightsabers. (assuming they survived to post anyway)

    3) Think of Jackass and the like where youths dare each other to do incredibly stupid shit like VOLUNTEER TO HAVE THEIR BALLS WHACKED WITH A GOLF CLUB! That same group would be trying to light a cigarette in their buddies mouth with a lightsaber, you can count on it.

    4) If lightsabers were real, a fair number of people would carry one for self defense, you just know it. Some amateur waving one around to fend off a mugging, rape or gang related curb stomping is gonna lop parts off of *somebody* and it won't always be the intended target.

    All in all, there would be a shitload of "I swear! I didn't mean to do that, it was a total accident bro!" dismemberments and deaths....

  22. Lukin Skywalker by frootcakeuk · · Score: 2

    If it wasn't his nickname before.....

    --
    Remember kids: What's right isn't as important as what's profitable.
  23. Re:STEVEN SPIELBERG HERE !! by viperidaenz · · Score: 1

    Mickey Mouse has more to do with Star Wars than George Lucas.

  24. Re:STEVEN SPIELBERG HERE !! by Anonymous Coward · · Score: 0

    Please stop it.

    Everyone knows that Star Wars started off as a cooperative writing project between Robert Heinlein and Issac Asimov, that it was then taken over by David Eddings and Neil Gaimen halfway through Emprire Strikes Back, and then all four cooperated on the Return of the Jedi!

    The prequel trilogy were all written by J.K. Rowling and Judy Bloom.

  25. Re:Unfortunately, you need real molecules to do th by Anonymous Coward · · Score: 0

    The Force has a strong influence on weakly bound electrons.

  26. SERIOUS! his name is LUKIN!!!??? by Anonymous Coward · · Score: 0

    sow awesome!

  27. Holodeck by Tekoneiric · · Score: 4, Interesting

    This is more like holodeck matter from Star Trek or hard light holograms from Red Dwarf rather than a lightsaber.

    --
    *It's not what you can do for the Dark Side but what the Dark Side can do for you!*
  28. I say... by GrahamJ · · Score: 1

    Use the force, Lukin!

  29. Re:STEVEN SPIELBERG HERE !! by JustOK · · Score: 1

    No, that was Star Search with Ed McMahon

    --
    rewriting history since 2109
  30. Re:So light has no mass, but space does? by Anonymous Coward · · Score: 0, Troll

    You're a very classical kind of idiot. If you regularly encountered black holes, or were the size of a quark, or traveled at relativistic speeds, you would not think anything unusual about the physics of these things. If this stuff were simple we wouldn't need the smartest guys on the planet working it out, we could just call you up.

    Sorry Captain Hubris but the pencil necks win this one.

  31. So little we know by lapm · · Score: 1

    Just goes to show how little we really know about physics and laws of nature in reality... Now they make light behave unexpectedly.. Personally i welcome weapon of more civilized times into our reality. All we need now is to learn to understand the force...

  32. Re:Unfortunately, you need real molecules to do th by bill_mcgonigle · · Score: 1

    <handwave>You don't need a coherent article summary.</handwave>

    --
    My God, it's Full of Source!
    OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
  33. Re:STEVEN SPIELBERG HERE !! by Kleen13 · · Score: 1

    Ugh... Judy is SUCH a bitch. This one time, at Band Camp... Nevermind.

    --
    That sinking feeling deep in your gut when you KNOW you screwed up bad summed up with: {head desk} {head desk}
  34. Re:So light has no mass, but space does? by Anonymous Coward · · Score: 0

    I'm sure the math works, but what it describes is not explainable in human language. All of us outside of physics can see that the descriptive theory has no clothes.

    Is math not a human language and form of description? If it works, as in it has predictive power and can't be simplified any further, how is an emperor with no clothes situation?

  35. Finally! by exxaminer · · Score: 1

    But LightSabre only Jedi handle can..and of course..the Siths..

  36. Obligatory xkcd by michelcolman · · Score: 3, Informative
  37. Useless, unfortunately by gweihir · · Score: 1

    Without Jedi skills, carrying a light-saber is just a good way to get shot.

    --
    Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
  38. Re:Do we really want light sabres in untrained han by Anonymous Coward · · Score: 0

    amateurs .. in central europe we are way ahead of you!

    http://www.youtube.com/watch?v=iiTE3tfe7qM

  39. Hello holodeck? by Anonymous Coward · · Score: 0

    Sounds like future holodeck technology or at least 'print' lightstructures in a 3d-printer? :)

  40. Re:You know that if they actually ever do make one by drkim · · Score: 1

    If lightsabers were real, a fair number of people would carry one for self defense...

    ...I'm just picturing George Zimmerman with a light saber.

    "Hey You! Kid!! What the hell are you doing around here!!!!" [bwazzzzzzzzzZZZZZZZZZZZZ - bzzzzWAAAaaaa - bzZZZZWAAAaaa]

  41. Re:Unfortunately, you need real molecules to do th by Sockatume · · Score: 1

    Correct, although I should point out that they're photons propagating through a medium, not photons being absorbed and re-emitted as one might assume. It's interesting that they're so strongly coupled to the rubidium.

    --
    No kidding!!! What do you say at this point?
  42. Youuuu by Anonymous Coward · · Score: 0

    want this don't you Lukin. Take your jedi weapon - strike me down with all your hatred - and your passage to the darkside will be completed.

  43. Re:STEVEN SPIELBERG HERE !! by K.+S.+Kyosuke · · Score: 3, Interesting

    Everyone knows that Star Wars started off as a cooperative writing project between Robert Heinlein and Issac Asimov

    Do you also love the part of the movie where Hari Seldon uses psychohistory to predict where the engineers would have put the most vulnerable spot, and then personally blows up the Death Star with a proton torpedo?

    --
    Ezekiel 23:20
  44. Re:Unfortunately, you need real molecules to do th by Richard+Kirk · · Score: 3, Informative

    This is happening in a non-linear medium where photons interact: it can't happen in free air. Photons hardly interact on most transparent media, but there are materials with non-linear electric properties that can be used to generate harmonics ( see for example http://en.wikipedia.org/wiki/Second-harmonic_generation ). This is used to convert red light into green in some green laser light pointers. At high power levels, the refractive index increases in more normal materials, which is a nuisance in high-power lasers as light in NdYg glass laser elements can self-focus and damaage the apparatus if the power gets too great.

    Hardly "contrary to decades of accepted wisdom about the nature of light" if you can find it in a green laser pointer. Meh.

  45. Re:Unfortunately, you need real molecules to do th by sjames · · Score: 2

    In a sense. They excite the individual rubidium atoms and then get re-emitted in a form identical to the original at the quantum level.

  46. Re:Unfortunately, you need real molecules to do th by sjames · · Score: 3, Insightful

    Calling it a form of matter is a bit of a stretch as is imagining that an advanced form of it could ever be lightsaber like. Unless all saber fights will take place in a rarefied environment consisting of super cold rubidium.

  47. Re:STEVEN SPIELBERG HERE !! by K.+S.+Kyosuke · · Score: 2

    It would have actually made perfect sense if Obi-Wan had said "fly, you fools!" to our heroes on the ramp of the Millenium Falcon. It flies, see?

    --
    Ezekiel 23:20
  48. What a terrible article summary. by Anonymous Coward · · Score: 2, Informative

    What a terrible article summary.

    Light is not self interacting at the tree level. This means there is no scattering of light in the classical sense, only through virtual particles (quantum loop corrections). Did this group of experimenters prove otherwise? No.

    This is the most clear statement from TFA

    "It's a photonic interaction that's mediated by the atomic interaction," Lukin said. "That makes these two photons behave like a molecule, and when they exit the medium they're much more likely to do so together than as single photons."

    http://phys.org/news/2013-09-scientists-never-before-seen.html

    What the experiment did do was place another particle in the theory, the electron, with which the light may interact. So the light continuously scattering off of electrons keeps the two light beams spatially near each other. This is not new physics. The sun does the same thing. How long does it take a photon to escape from the sun? Typically a few million years.

    What is significant about this experiment is the level of control the experimenters have over the scattering proximity of the light. Unlike the sun, whereby a very large volume is effectively trapping the light, this is a tabletop experiment.

    A proper summary would be that a breakthrough in experimental techniques allowed for controlling photon scattering to a higher degree than before achieved.

    1. Re:What a terrible article summary. by ceoyoyo · · Score: 1

      That's not actually really new either - people have been shooting lasers into super cold rubidium gas for years. What's new here is that these guys shot two photons in and watched them come out again.

  49. Use the force, Lukin by Anonymous Coward · · Score: 0

    This is actually a very exciting discovery.

  50. Re:Do we really want light sabres in untrained han by ceoyoyo · · Score: 1

    Pretty ineffective. They kept hitting that guy and he still wouldn't stay down.

  51. Coincidence? by Anonymous Coward · · Score: 0

    Let's see.... Luke is a Jedi who can make a light saber. The scientist's name is 'Lukin'... Hmmmm Coincidence?

  52. Re: Unfortunately, you need real molecules to do t by _0xd0ad · · Score: 1

    Did you read the whole article? One photon will be re-emitted in identical form to the original, but two photons will likely be re-emitted as a single, molecule-like unit.

  53. Re: Unfortunately, you need real molecules to do t by sjames · · Score: 1

    No, it said two photons will be released together. Two photons flying in formation is hardly the same as a bound molecule.

  54. Re:STEVEN SPIELBERG HERE !! by Specter · · Score: 1

    Well that explains why Ep. V went downhill after the Battle of Hoth. Come to think of it, it completely explains the land side of the Battle of Endor.

  55. Re:You know that if they actually ever do make one by Tyler+Durden · · Score: 2

    1) a surprising number of people actually commit suicide by decapitating themselves with a chainsaw.

    I was going to reply with a "citation needed" to this one but, on second thought, if this is true then I really don't need to know.

    --
    Happy people make bad consumers.
  56. Re:STEVEN SPIELBERG HERE !! by ClickOnThis · · Score: 1

    He can't! My tricorder says Neo is in the way!

    - Tyrion

    --
    If it weren't for deadlines, nothing would be late.
  57. Re: Unfortunately, you need real molecules to do by Anonymous Coward · · Score: 0

    No, it said

    they were surprised to see them exit together, as a single molecule. ... these two photons behave like a molecule

    Perhaps you could e-mail the scientists and tell them that they're wrong, that what they've observed is simply "two photons flying in formation".

  58. Matter Creation by autojack2 · · Score: 1

    I keep seeing this headline about scientists creating matter. Matter/energy is not created or destroyed.

    1. Re: Matter Creation by Anonymous Coward · · Score: 0

      New form of matter != new matter

  59. Re: Unfortunately, you need real molecules to do by sjames · · Score: 1

    With no binding force, it is not a molecule once it leaves the cloud (which mediated the binding). Since I seriously doubt they would bury a lead like 'new force of nature discovered' or 'photons interact through nuclear force', I can only conclude that you are taking the analogy far more literally than they intended.

    WITHIN the rubidium cloud, they act as a molecule whose binding is mediated by rubidium atoms. That is not uninteresting, but is not the same thing at all.

  60. Re:You know that if they actually ever do make one by Anonymous Coward · · Score: 0

    "an elegant weapon for a more civilized age" (vs. a chainsaw)

    Because: It cauterizes the amputations. (And we never dwell on how much energy would be required for instant cauterization of such wounds and how much damage that thermal energy would inflict.... above and beyond the systemic shock)

  61. Re:STEVEN SPIELBERG HERE !! by samwichse · · Score: 1

    I think Dumbledore says that.

  62. Re: Unfortunately, you need real molecules to do by Anonymous Coward · · Score: 0

    The news was that once they exited the cloud they still acted like they were bound together.

  63. Re: Unfortunately, you need real molecules to do by sjames · · Score: 1

    by what?

  64. There's a fucking typo in the phys.org article.. by Anonymous Coward · · Score: 0

    "Researchers began by pumped rubidium atoms into a vacuum chamber,"

    PUMPING... wtf is wrong with the world when the best of the best don't proofread their shit? Are we really doomed to be a half-assed society?