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Why cant light be stored?


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Thread,

 

Just thinking. "Stored" can be thought of in terms of put it in now, get it out later.

 

How about a fiber optic cable, with both ends in your hand? Shine a light in one end, and it comes out a fraction of a second later, from the other. A large enough coil of a ​strand of fiber optic cable, of a very large length would allow one to design a setup where the one end was fused back into the entry end, at a small angle like an entrance ramp onto a highway to where the light coming around the second time would take the course again, and again the third and successive times. This way the entry point would not be a likely exit point, and one could, by continually pumping light into the course, increase the amount of light traveling in the fiber. And if the entryway and an off ramp where designed to open and close in some manner, pulses of light going into the course, could be timed, so that the majority of the light was in one section of the course, at a time, analogous to the pack going around a speedway. Then the exit way could be switched open, like a train track switch, while the pack was in the middle of the course, and when it came around, out it would come. One could imagine this, as storing light.

 

Regards, TAR

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Thread,

 

Just thinking. "Stored" can be thought of in terms of put it in now, get it out later.

 

How about a fiber optic cable, with both ends in your hand? Shine a light in one end, and it comes out a fraction of a second later, from the other. A large enough coil of a ​strand of fiber optic cable, of a very large length would allow one to design a setup where the one end was fused back into the entry end, at a small angle like an entrance ramp onto a highway to where the light coming around the second time would take the course again, and again the third and successive times. This way the entry point would not be a likely exit point, and one could, by continually pumping light into the course, increase the amount of light traveling in the fiber. And if the entryway and an off ramp where designed to open and close in some manner, pulses of light going into the course, could be timed, so that the majority of the light was in one section of the course, at a time, analogous to the pack going around a speedway. Then the exit way could be switched open, like a train track switch, while the pack was in the middle of the course, and when it came around, out it would come. One could imagine this, as storing light.

 

Regards, TAR

 

I'd have to think that would be subject to the same inefficiencies that swansont mentioned with the mirrors. What I find myself wondering is "are these inefficiencies merely that (inefficiencies) or is there also some fundamental, "unbeatable" mechanism that would prevent it from persisting indefinitely?"

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Yes. Really transparent fiber still attenuates - maybe as little as 0.1 dB/km, but even then 100 km means it's dropped to 10%. So after a millisecond you've lost most of your power.

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KipIngram,

 

While considering thought experiments, containing photons, I often wonder how "long lived" a photon is, anyway. That is, any "loss" of photons going around the course would be associated with an increase in temperature of the second level medium that surrounded the fiber of glass. As I understand it, the light effectively reflects off the inside of the boundry between the glass and the surrounding material. But the photons themselves are not traveling through a vacuum, they are traveling through glass. So they must either be finding their way between the atoms of silicon, oxygen, sodium, carbon and calcium, or those said atoms are receiving a photon of energy and releasing a photon of energy of the same size, in, for some reason, in the same direction as the incoming photon was travelling. So, I am not sure what "happens to" a photon anyway. Whether it can be always considered as a discrete, unique unit, or thing, which has a born on date and a dead date, or whether it becomes merely the impulse, of that packet of energy, which can reside, for moments in forms other than photons, in the energy level of an electron of an atom that goes higher once hit by the "death" of a photon, and relaxes back to a lower level, when releasing a newborn photon.

 

Regards, TAR


For instance, if a photon is released from a Helium atom at the center of the Sun, does it ever "get out" of the Sun, or is it absorbed by a nearby other atom of helium, which then releases a "new" photon.


so when light bounces off a mirror, is it that same photon, actually somehow changing direction, or is the silver on the back of the glass, absorbing a photon and birthing a new one?

Edited by tar
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For instance, if a photon is released from a Helium atom at the center of the Sun, does it ever "get out" of the Sun, or is it absorbed by a nearby other atom of helium, which then releases a "new" photon.

so when light bounces off a mirror, is it that same photon, actually somehow changing direction, or is the silver on the back of the glass, absorbing a photon and birthing a new one?

It takes thousands of years or more to get to the surface

https://image.gsfc.nasa.gov/poetry/ask/a11354.html

 

You can't tell if it's the same photon or not.

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?

What you said was "Imagine you had a 1 way mirror. One way, light could move right through without a problem.

On the other end, it would be reflected at 100% efficiency. (obviously an impossible component at current technology, but lets say it was real.)"

It's easy to make a very good mirror getting 99.99% reflection is "off the peg"

However the other thing you wanted " 1 way mirror." in the sense of a device where light only goes through in one direction, isn't so easy.

So, the disclaimer "(obviously an impossible component at current technology, but lets say it was real.)"

was tacked onto the wrong end.

 

Incidentally, photons are difficult to store because stores are stationary, but photons only exist at very high speed.

Edited by John Cuthber
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What is the battery in your car?

Do you think you get the same electrons out that you put in when charging?

 

So how to store photons as I outlined in post#4.

 

That is photons in and later photons out.

 

All afternoon my car has been sitting on the drive absorbing all those nice yellow photons.

 

Tonight, after dark, members of the local furry fraternity will sunbath by basking in the infra red photons radiated under my car.

 

There ya go, photons in photons stored, photons out.

 

I never said they were the same photons, any more than Mr Chloride said the electrons from the car battery are the same.

Gah. You're right. fine. nevermind.

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So for the sake of a thought experiment, related to what I think the OP is referring to.

 

Imagine you had a 1 way mirror. One way, light could move right through without a problem.

On the other end, it would be reflected at 100% efficiency. (obviously an impossible component at current technology, but lets say it was real.)

 

If you shined a laser into the box, where one end was the one way mirror, and every other side was 100% reflective.

They would bounce back and forth.

 

 

What would happen as more and more photons kept joining the box?

[/your quote]______________________________________________________

 

 

 

<<lets say a spherical shape box : It will go under fusion ; and explode,,,/ scatters in pieces.

Edited by Roger Dynamic Motion
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  • 4 weeks later...
  • 3 weeks later...

Here's one out-of-curiosity question, similar to Raider's but without the "one way mirror" to consider.

 

If someone made a closed container, coated on the inside with the most reflective material possible, and put a laser pointer inside it (set to go off at a given time) and used up all its light to completion, where would the light go?

 

Would it all be absorbed/transmitted, even by whatever degree of either it has? And would reflectance give way to absorptance and transmittance once the intensity of light increased?

Edited by ScienceNostalgia101
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Even our most reflective surfaces are not 100%. Someone energy will be absorbed at each reflection. That energy will radiate away from the outside as heat. As the energy increases inside the reflecting material will get hotter and then each reflection will be too much energy to easy dissipate, the mirror will start to burn, once that begins to happen the reflectivity over that area will drop dramatically and the burning will become faster. You'll end up with a destroyed box.

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Even our most reflective surfaces are not 100%. Someone energy will be absorbed at each reflection. That energy will radiate away from the outside as heat. As the energy increases inside the reflecting material will get hotter and then each reflection will be too much energy to easy dissipate, the mirror will start to burn, once that begins to happen the reflectivity over that area will drop dramatically and the burning will become faster. You'll end up with a destroyed box.

 

 

If the laser is powerful enough. Basically you need to reach steady-state: if the laser is outputting 20 mW, then you need to radiate 20 mW of energy, which would not require much of a temperature increase, given reasonable values for the area and emissivity.

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If the laser is powerful enough. Basically you need to reach steady-state: if the laser is outputting 20 mW, then you need to radiate 20 mW of energy, which would not require much of a temperature increase, given reasonable values for the area and emissivity.

Yes, I was anticipating a decent power. You would need to consider the full configuration as you may end up with a disproportionate amount of energy in one small area which could cause damage which would then multiply.

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Yes, I was anticipating a decent power. You would need to consider the full configuration as you may end up with a disproportionate amount of energy in one small area which could cause damage which would then multiply.

 

 

Right. I was assuming decent thermal conductance, which upon further consideration may not be a good assumption for a mirror

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