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well if we sort of stick all the light together...
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I was thinking that if we could somehow get a photon to stop and attach itself to another substance (magnetic fields? electric charge? Some sort of exotic glue? I thought of gravity but then realised that I wouldn’t want the entire world sucked into a black hole - sorry to any fans of gravity) you would then be able to bounce another bit of light off it to find out what it looked like...

also if you could get lots of them to stick to something then it would probably look cool... it could start a new trend in decorating... or maybe you could use it as a replacement for florescent or glow in the dark substances..

RobertKidney, Aug 29 2001

Bringing light to a standstill http://www.bubbasof...0a%20Standstill.htm
[Trouvere, Aug 29 2001, last modified Oct 21 2004]


       Well, no matter how forcefully the photon is stuck, it's still going to move a little bit when it's hit. I'm not sure a sufficiently strong isometric force exists to keep the photon sufficiently still to be "seen," but I'll leave that to the HalfBakers who know what they're talking about.
nick_n_uit, Aug 29 2001

       I'll be in the cheap seats rooting for the home team.
thumbwax, Aug 29 2001

       I could be wrong, but . . . when we see something, isn't it (proximally) due to photons hitting receptors in the back of the eyeball? If so, how will we see your photons? While stuck to something else, it can't be travelling around and triggering receptors. "Oh, but it's light will shine into your eye" - yeah, but that light is photons. See what I mean? After all, black holes are black because they are photon collectors. "if you could get lots of them to stick to something then it would probably look . . " black. Things are light/bright because they emit or reflect photons. If your device holds them, but doesn't emit them, then it's gonna be black.   

       In other words, if a photon doesn't hit a receptor in some critter's eye, then it technically isn't light.
quarterbaker, Aug 29 2001

       quarterbaker - You mean if nobody sees something, it doesn't exist? Can't we infer the existence of things (the dark side of the moon, say) without having to literally see them?   

       Not that this helps RobertKidney...
snarfyguy, Aug 29 2001

       no - the idea is that the surface of the object is covered in photons but any more photons are free to bounce off the ones that are stuck...   

       and its light regardless of were it is... I can claim that the light entering your eye isnt light because I cant see it... no?
RobertKidney, Aug 30 2001

       great - but don't you think the tree would look better if it was decorated with stuck photons?   

       now as to how this would work... were is vernon when you need him?
RobertKidney, Aug 30 2001

       Then we better shoot him with a silver bullet!
beauxeault, Aug 30 2001

       snarfguy - I didn't say that if you can't see it it doesn't exist -- I just said that if you can't see it then it isn't light.

       "any more photons are free to bounce off the ones that are stuck" - just like they would off a surface that doesn't have stuck photons on it.

       You can't get light from a stuck photon because light, by definition, is non-stuck photons. Photons don't emit light, they are light.   

       I'm trying to think of a useful analogy . . . trying to get light from a "stuck" photon is like . .
1. taking a glass of water from an ocean wave to capture the wave
2. ???? suggestions ????
quarterbaker, Aug 30 2001

       to see an object I bounce a bit of light off it and into my eye - I dont have to get the object into my eye to see it. To see the stuck photon I bounce an unstuck photon off it into my eye...I don't see a problem here...
RobertKidney, Aug 30 2001

       [analogy] ...is like dialling your own number and expecting the phone to ring.
-alx, Aug 30 2001

       You can SMS yourself, though. [blatant stupidity of this annotation acknowledged]
sdm, Aug 30 2001

       I did that once...in the countryside, no watch, no clock on my phone. Sent myself a message to see the timestamp.
-alx, Aug 30 2001

       If Milli Vanilli fall down in a forest does someone else make a sound?
hippo, Aug 30 2001

       hippo: Yes! If Milli Vanilli are loose in the forest then our only hope is that UnaBubba will fall on them in the dark when nobody is listening.   

       I think that if you stop a photon it mopes and withers away, for its very essence is that it always travels at the speed of darkness. It is not Catholic (cannot gain weight no matter how much it eats) and has a permanent wave which does not detract from its particulate properties when examined in the proper way. It thumbs its probable nose at gluons, which are the stickiest things known to God, and it so cannot be stuck down. So small that it cannot carry a wristwatch, a photon has no notion of time and despite being redshifted it never hurries one bit, the cheeky thing. In a Bose-Einstein condensate, as per Trouvere's excellent link, it obeys local speed limits (a very law-abiding wavicle is the photon) but we should not hold that against it.
Dog Ed, Aug 30 2001

       Good analogy, -alx
RobertKidney - I see you've edited the first paragraph of your idea.
Let me try once more to explain. If you bounce a photon off a "stuck" photon, you'll see the bounced photon, not the stuck one.
Another analogy: a stuck photon has the same relation to visible light as a magnetic charge on an audio tape has to the sound it may produce if played.

       Please explain to me how bouncing photons off a surface that has photons stuck to it would produce a different visual experience from bouncing the same photons off the same surface, but without the stuck photons.
Your objective, it seems, is to make things glow ("replacement for fluorescent or glow-in-the-dark substances"), or, in other words, emit light. As I have patiently explained, photons do not emit light, they are light. You're now saying that you want to introduce more photons, besides the stuck ones. If you stick photons to a surface, then bounce more photons off those photons, the total quantity of light you get will be (at best) the light of the bouncing photons. The stuck ones can't contribute. To use one of my analogies, bouncing a sound wave off a magnetic tape recording won't allow the "sound" of the tape recording to contribute to or modify the bouncing sound wave.

       Does anyone else here want to have a go at explaining this, please?
quarterbaker, Aug 30 2001

       so when I look at my computer I dont see it I see the photons bouncing off it... true but I still get to find out what it looks like... I plan to look at my stopped photons in the same way...
RobertKidney, Aug 30 2001

       so what does it look like?   

       and he's probabley working on his next idea...
RobertKidney, Aug 31 2001

       does any one want to see my photon album?
po, Aug 31 2001

       Another analogy...   

       A light bulb emitts photons (speaker: sound waves) When the bulb is off, or the speaker silent, there is nothing but a light bulb (or speaker). Or stationary photons (no visible light), (sound waves (no sound)).
TimothyD, Sep 21 2002

       stationary photons do not, can not exist (in this house, we obey..) - they already have no rest mass energy, all they have - all they are - is a particular form of kinetic energy, if you will. Remove that, and you have nothing.   

       Conundrum that just popped into my head: If you have two photons travelling in parallel, what is their relative speed? Answers on a postcard to...
yamahito, Sep 21 2002

[ sctld ], Sep 21 2002

       OK, sctld: now imagine that there's a certain boundary a certain distance from their starting point - which one arrives first?
yamahito, Sep 21 2002

       They both arrive at the same time.
[ sctld ], Sep 21 2002

       but then their relative speed would have to be zero..   

       If I were answering a physics paper, I'd have to start talking about uncertainty and similar to answer this one, I think - the trick is in the question: you could never be sure that two photons were travelling in parallel. That would imply the existence of simultaneity, which is not really sensible in a relativistic universe.   

       (i'd like to point out that these are guesses on my part - I probably slept in when we covered them in class..)
yamahito, Sep 21 2002

       No they don't have to have a realtivistic speed of 0. You asked who would win the race. That implies that i would be judging from the outset. And since light always has a relativistic speed of C to any object, both photons move away at the same speed to me, and arrive at the same time as far as i am concerned. If you had asked me which one wins, relative to each other, then photon A will 'think' that photon B has won, and photon B will 'think' that photon A has won, since they can't view from the outset.
[ sctld ], Sep 22 2002

       //as far as i am concerned//   

       No, now you're thinking in a stationary starting point frame. i wanted to think about the frame of light of one of these light particles. Also relativistic is not the same as relative.   

       //photon A will 'think' that photon B has won, and photon B will 'think' that photon A has won//   

       you also need to take into account the time taken for the information to pass between these two: in which case, I don't think the above can be correct. In fact, if the maximum speed of information transfer is the speed of light, and all particles of light are travelling that fast away from each other, then information can never flow between the two frames of reference associated with the photons. I think that this is equivalent to saying that there is no such thing as simultaneous events. - shall we move this discussion to IBD?
yamahito, Sep 22 2002

       Indded we should.
[ sctld ], Sep 22 2002

       There's no reason to stick it to a surface. All you have to do it knock two particles together. You record where each of them lands. You do this thousands of times and you have a picture of a photon, because all the photons look exactly alike. A mathematician doesn't need to hold something still to bounce something off it. He just knocks them together and then adjusts the vector space until one is, if he wants.   

       They haven't made much progress with photons yet because photon entanglement (two photons interactng) is difficult to pull off. Photons are hard to create exactly where you want, and very hard to steer, so they've been later on the list of particles to bounce off each other.   

       As for what they "look like" what a particle looks like means many things. It means how it interacts. They're not going to get a "picture" of the particle on a photographic plate because they're not bouncing thousands of tiny particles off a larger particle in a classical way. What they get is points which, when analyzed, provide the information to formulate expressions for the various implicit surfaces of the particle in multi-dimensional spaces you don't have the math to imagine. After they have the math, they can graph a three-dimensional "slice" of this appearance based on specific circumstances and voila, they give you your layman's picture in Scientific American, which really will be the picture you wanted, something you can put on your wall and say "this is the shape of the thing," and be as right as you are when you point to flat grainy collection of faded dots and say "that's Grandma."   

       To make this clear, consider that you think you know what DNA is shaped like, and in a sense you do, but there's an infinite number of ways to look at it. It folds up, the pieces of the helices bristle with atoms, which bristle with electron shells, which are vague cloudy probability functions. It's all about how detailed your graph is. If you were a little electron in there, you wouldn't see all these things around you. You'd just careen back and forth over the sum total of the surfaces at your potential level, perhaps being traded from time to time, perhaps not. At the same time, in this environment which bristles with implicit surfaces, the reality of what it "look like" might be closer to total emptiness. The matter involved is just the tiniest specks, never getting anywhere near touching directly. An electron is tens of millions times smaller than it is far from the center of an atom, something very vaguely like being a single human in a space suit forty thousand kilometers from an asteroid, attached by an elastic band.   

       "Looks like" is either what you experience, or how you understand something to be shaped. If you want "looks like" for a photon in terms of human vision only, a photon is a spot as black as possible without being black.
AllenChristopher, May 12 2003

       Folks, you all seem to be missing the fact that every substance ABSORBS a certain amount of light -- there are no perfectly reflecting substances. Thus, from a certain point of view, those absorbed photons qualify as "stuck", as far as RobertKidney's Idea here is concerned. (True, they don't usually stay stuck, a substance tends to re-emit the photons it absorbs, although usually at invisible infrared wavelengths.)   

       Do recall that seeing color in objects is a result of selective absorption of photons by those objects (a ripe apple absorbs green and blue photons, and reflects red, for example). Perhaps, from that point of view, this Idea should be considered totally baked.
Vernon, Dec 10 2003


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