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back to article New 'iPhoD' can 'adjust the speed of light by turning a knob'

Optical stuff is great, as everyone knows: optical links mean huge bandwidth right now, and computers running on photons rather than electrons might be truly amazing things - tremendously powerful, very economical of energy, and potentially able to exploit quantum effects to achieve all manner of mindbending feats. But …


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  1. Anonymous Coward

    Quantum computing..

    is not all it's cracked up to be. Where I work we already have quantum servers: as soon I as I stop watching them, they f*!k about and stop working properly.

    1. Trevor_Pott Gold badge


      Sounds to me like you have a bad case of "Schrödinger’s rack." Tough break; I hear the cure is quite expensive…

    2. hplasm

      Perhaps it's the cabling?

      Is it Schrodinger's Cat V ?

  2. Anonymous Coward
    Anonymous Coward

    But no!

    "But unfortunately, there is as yet no way to handle photons other than in a fibre"

    Well, my freeview box manages quite well, as does my moble broadband dongle (which even manages bi-directional).

    Photons aren't just visible light!

    1. Stuart Halliday


      "Photons aren't just visible light!"

      So what else are they?

      1. Pablo

        Radio in this case

        But also microwaves, IR, UV, x-rays, and gamma rays.

      2. Allan George Dyer

        IR, UV, microwaves, gama-rays, radio 4 broadcasts...

        in fact, all types of electromagnetic radiation.

      3. Cameron Colley

        @Stuart Halliday

        Gamma rays, X-Rays, ultra-violet, infra-red, microwaves, Long wave radio...

      4. Chemist

        Re : Ehh?

        So what else are they?

        Strictly quanta of any wavelength EM radiation AFAIA

      5. Jon 52

        anything on the elctromagnetic spectrum

        from beyond long range radiowaves to beyond gamma rays.

  3. Jelliphiish

    is that what mr beeblebrox listens to his tuns on?


  4. Chronos


    Cue Apple patent in 3... 2... 1...

    1. Mike Hunt 1

      Re: iPhod

      Surely you mean Cue Apple lawsuit.....!

      1. Chronos
        Jobs Horns

        Re: iPhod

        Nah, patent. Even Apple wouldn't dare go up against the Mad Military in a court of lore[1]. They'll not hesitate to try to patent and/or claim other people's ideas, though.

        "We invented the GUI! Windows copied us!"

        So X/PARC and Digital Research were just sitting there playing with themselves, were they? Yeah right, Steve. NURSE!

        [1] No, that wasn't a typo. Think about it.

    2. SkippyBing


      Apple vs DARPA, my money's on the Battle Boffinry Bureau!

  5. Anonymous Coward

    For a moment...

    I thought the article was going to say they can make light go faster than c. Phew! Who wants the Feds reading their email BEFORE they've sent it?

    1. K. Adams

      Might not be as big a problem...

      ... as you think.

      Heisenberg tells us that you can't measure something without changing it, or more (less?) precisely, you can't know everything about something in full detail.

      Therefore, if the Feds read your mail before you send it, then the copy you send won't be the copy they've read... :-)

      1. Allan George Dyer
        Paris Hilton

        Might be an even bigger problem...

        when the Feds read the plans for the terrorist attack you weren't planning, instead of the innocent message you really sent. And, if the Feds don't get you, the animal rights activists will want you to release the cat!

  6. TonyHoyle

    I'm somewhat surprised you can even slow it down

    In physics in school they drummed 2 things into you constantly:

    1. Energy can't be created or destroyed

    2. The speed of light is constant

    If (2) isn't true any more I'm glad I got out of physics at high school! God knows how I'd answer the homework if C isn't a constant any more :p

    1. ratfox

      You phail physics phorever

      Sorry, (2) was only ever true in space. Light is significantly slower in materials that are transparent but dense, such as water or glass. This is why light refracts when going from one medium to another.

      That's how lenses work.

    2. Cameron Colley

      "... in a vacuum...".

      "The speed of light in a vacuum is constant". The speed of light in other substances, however, is far from it -- otherwise eye glasses, telescopes and the like would be pretty useless.

    3. MaxRock


      c is still constant. But the speed of light in a medium other than vacuum can differ greatly from c.

    4. Anonymous Coward
      Anonymous Coward

      It's all trickery

      My understanding is that it's all relative time frames and photon absorption/emission. The light is still traveling at ~2.99E8 m/s but thanks to some math and physics trickery and what-not, we measure it as going slower. Though I may be entirely wrong.

    5. Zargof


      It would appear they didn't drum constantly enough.

      Your point 2 should be stated as "The speed of light *in a vacuum* is constant.

      This is a very important distinction as light travels at different speeds depending on the transmission medium. Just look up refraction for and everyday example of the effects of this.

    6. Ian K

      Why do replies _need_ titles? Surely they'll implicitly have the title of their parent post?

      The speed of light's only constant in a vacuum; when travelling through a transparent medium it can be (and is) different.

      That's not an obscure physics effect with no practical implications either; amongst other things it's the mechanism lens use to work, including the ones in eyes!

    7. Chris Miller

      Almost right

      The speed of light *in a vacuum* is constant.

      The speed of light through a material - air, water, glass - is slower. That's what refraction is. Didn't they teach that in high school physics?

    8. Matt 5

      Ok, I'll bite...

      The speed of light is constant - in a particular medium with fixed properties (remember the c most talked about is the speed of light in a vacuum, which is faster than the speed of light through the atmosphere and so on. Go re-read your high school physics books on refraction!). These guys are simply talking about changing the properties of the rubidium vapour, thus altering the speed of light in that substance. However, all light in that substance at that particular attunement will move at the same speed. So there you go. All sorted out for you.

    9. stucs201

      you missed a bit

      the speed of light *in a vacuum* is constant.

      (though it probably goes round in circles too if that vacuum is a Dyson, not a Hoover)

    10. frank ly

      Re. The speed of light

      "2. The speed of light is constant"

      The speed of 'light' depends on the properties of the medium that it's traveling in. For a bulk medium, like the vacuum of space, a block of glass, etc; this is easy enough to work out and the behaviour of the waves/photons, whatever, is easily predicted. Hence school level physics.

      When the photons start interacting with exotic substances that absorb and re-emit, then it all gets very complicated and scientific articles are born.

    11. SkippyBing

      The speed of light is constant in a vacuum

      this doesn't mean it's the same velocity in another medium.

    12. K. Adams

      c_Rb != c_vacuum

      The constant "c" (as in "just 'c' ") is the speed of light **in a vacuum**.

      The speed of light can and does vary, depending on the material (or lack thereof) through which the light moves.

      Thus: c_Rb != c_vacuum

      It is even possible for physical charged particles (electrons and/or protons) to **exceed** the speed of light **of a given moderating material**, if the particles have enough momentum. For a more detailed explanation, look up Cherenkov radiation:


    13. Anonymous Coward
      Anonymous Coward

      But the speed of light...

      ...changes depending on the medium it's travelling through, which is pretty critical to how this works.

    14. Adam 10

      Speed of light in a vacuum

      Ah yes, we've all heard "The speed of light is constant and is approximately 3x10^8 ms^-1", but the important bit that sometimes gets missed out is "in a vacuum".

      If you want to see a very cool effect caused by the difference in the speed of light between material A and material B, look up Cherenkov radiation on the net, especially for pictures!

      1. Ross 7

        Cherenkov radiation

        I always thought that was a cool step up from cold cathode lighting for a games rig, but the health and safety implications (not to mention getting raided by SO13 at 4am for being a terrorist implications) make it a little less attractive.

        You;ve gotta admit tho - the cooling and visual benefits of dropping your rig in heavy water with some beta emmitters are definitely there...

  7. Dazed and Confused

    Who wants to slow it down

    We need to speed it up. That damn value of "c" is just too slow, it causes too many performance problems. Can't these guys get on with tackling the real problem, latency!

    1. Jon 52

      like the 500 mile email

  8. Rupert Stubbs

    Bob Shaw will be happy...

    ... can't be long before we get slow glass...

    1. James Hughes 1


      I remember that one - good story. Can you remember the name of the it?

      1. Sam Therapy
        Thumb Up

        Slow glass story

        Was called "The Light of Other Days". Damn good - and quite sad - story.

        Such stuff already exists, though I believe the time differential is only small, at present.

  9. Stuart Halliday
    Thumb Up


    Have they invented 'Slowglass'?

    People who don't read books (ROM devices made of cellulose) wouldn't get that Bob Shaw reference.

  10. Alex maximus
    Dead Vulture

    A science article and no single reference ...

    ... to boffins, applied boffinry, or any other name calling? Tsktsktsk... You disappoint, el Reg, you disappoint!

    What next - dropping the term JesusPhone from future iFruit reports? It's a slippery slide from here!

  11. Anonymous Coward

    slow light

    So light can slow down. maybe light is slowing down the farther it travels, and all astrophysics is wrong!

  12. King Jack


    Slow light is what comes out of Capt Kirk's phaser.

  13. Graham Marsden

    Then you turn on the control laser and...

    ... "Boom"!

    Erm, perhaps he could have phrased that better?!

  14. Xris M


    I assume Prisms weren't included in your GCSE/O-Level syllabus then.

  15. Damian Turner-Steele

    Best name ever

    beaten-track-averse battleboffinry bureau

    Laughed harder at this then at the more recent BOFH

  16. Paul_Murphy

    Gravity also affects the speed of light (in a vacuum)

    Gravitic lenses caused by galaxies should be the most familiar, but even planets can cause the light path to curve.

    Space-time is affected by mass - so another way of creating a light pulse would, I postulate, consist of a black-hole which can have its' mass altered.

    Feed some light into the black hole at the right angle whilst adding sufficient mass to trap the light, and then simply remove some mass to release the light.

    Wouldn't change the speed of the light, of course.


    Now is it worth patenting that idea I wonder?? hmm


    *Ok - there may be an element of sarcasm in there.

    1. Anonymous Coward


      From what I remember from Uni, that's not strictly true.

      Gravity causes light to curve, because space/time is curved and not flat.

      Light doesn't slow down, but it can loose energy, which will show as a red shift, but it'll still travel at c...

  17. Yesnomaybe

    I thought...

    ...there was an article a while ago, about some boffins having invented slow glass? OK, SLOWER glass... Wasn't there?

  18. Mr Jolly

    So let me just get this straight...

    From reading the comments here, can I surmise that the speed of light is only constant "in a vacuum?"

    I'd have thought it would get trapped in all the fluff and spinning brushes.

    1. Anonymous Coward
      Anonymous Coward


      Depends if its a bag-less vacuum (and generally clear sides, which allows the light to escape, and you to realise it's full after 5 seconds hovering) or not.

  19. Ian Yates

    Have I missed something?

    We've been here before... (albeit, slightly different implementation),1674.html

  20. Craig 12

    Easier way to 'faster' computing

    Can't we just set a computer running, shoot off for a quick trip round the solar block at 90% light speed, then check back to see the results?

  21. MarkieMark1

    so, wait

    Is the speed constant in every medium? Please answer in no less than 53 comments

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