5 ms·

The title (and the first comment on the link) makes it sound like it's a perpetual motion machine, but as far as I can tell it's more like a tiny heat-pump: ene

by eck 14y ago

The title (and the first comment on the link) makes it sound like it's a perpetual motion machine, but as far as I can tell it's more like a tiny heat-pump: energy is conserved, entropy increases. Still kind of neat though.

Cushman 14y ago
Of course they didn't beat thermodynamics, but still, assuming they can scale the tech up to a useful power, it's a light that's also a cooling element. That'd be more than kind of neat, wouldn't it?
- Ygg2 14y ago
  But where would you use light that cools? Fridge lights? House lighting in warm regions? Hmmm. On second thought it could have interesting applications depending how much it cools.
  - nagash 14y ago
    Data centers.
  - mbreese 14y ago
    Lighting is hot. I'd love to have lights that weren't also little heaters. Or, if the cooling effect is big enough - imagine solid state cooling on devices. Who needs a fan when you can have a little cooling light? I doubt that they'll be able to scale this up too much though, since it probably relies on an effect that only occurs below a certain threshold.
    - swombat 14y ago
      Most LEDs don't heat up that much... they're usually cool to the touch. I'd love a computer that glows brighter to release heat when it gets too hot, though :-)
  - aw3c2 14y ago
    you apparently never were on a stage, bring illuminated by giant lights. it often is uncomfortably hot. this is also a problem in video recording.
    - ars 14y ago
      And this would make it worse. It cools the lamp by sending the heat outward in the form of light. It does not cool the recipient in any way, in fact it requires that the recipient already be cooler than where the lamp is.
      - aw3c2 14y ago
        oops, my bad. I thought I understood it from the comments here and did not read the article.
  - gsivil 14y ago
    I am sorry that I cannot elaborate more on that for now(4am) but the cooling effects of light are known for quite some time already. Please check laser cooling as a keyphrase.
- ars 14y ago
  Keep in mind it only works if the light is being sent to an area that is cooler than where the lamp is. It's basically converting the heat difference into light. So you can't use it just to cool, it doesn't work that way.
  - davorak 14y ago
    I think where the light is being sent is open space so what ever temperature the local background radiation is at; a common local minimum being the cosmic background radiation.
    - ars 14y ago
      > a common local minimum being the cosmic background radiation No, that's only if you are in outer space. On earth it's the temperature of the air, or the walls. It doesn't matter if the light eventually gets to outer space - what matters is that there is something hotter near you (namely the air). i.e. it's not where the photons end up that matters, it's the total of all the photons that are being sent in your (the lamp's) direction that counts.
      - davorak 14y ago
        Sorry if what I said was unclear. > it's not where the photons end up that matters, it's the total of all the photons that are being sent in your (the lamp's) direction that counts. This is what I was referencing when I siad "the local background radiation." The common minimum was supposed convey high frequency when choosing a random spot in the known universe. > On earth it's the temperature of the air, or the walls. The temperature of the air only comes into play if it is emiting radiation at the frequency of light produced by the led and at greater intensity. I do not see why this would be required.
        ars 14y ago
        > The temperature of the air only comes into play if it is emiting radiation at the frequency of light produced by the led and at greater intensity. Blackbody radiation. Air (everything) always emits light. > I do not see why this would be required. It's a fundamental law of thermodynamics that requires a heat source and a cold source in order to convert heat into some other form of energy. The air around you is the cold source, and the LED lamp is the hot source. If the LED is colder than the air it will not work - the LED must be hotter (in this particular case they put it in an oven).

by eck 14y ago

Cushman 14y ago

Of course they didn't beat thermodynamics, but still, assuming they can scale the tech up to a useful power, it's a light that's also a cooling element. That'd be more than kind of neat, wouldn't it?

Ygg2 14y ago
But where would you use light that cools? Fridge lights? House lighting in warm regions? Hmmm. On second thought it could have interesting applications depending how much it cools.
- nagash 14y ago
  Data centers.
- mbreese 14y ago
  Lighting is hot. I'd love to have lights that weren't also little heaters. Or, if the cooling effect is big enough - imagine solid state cooling on devices. Who needs a fan when you can have a little cooling light? I doubt that they'll be able to scale this up too much though, since it probably relies on an effect that only occurs below a certain threshold.
  - swombat 14y ago
    Most LEDs don't heat up that much... they're usually cool to the touch. I'd love a computer that glows brighter to release heat when it gets too hot, though :-)
- aw3c2 14y ago
  you apparently never were on a stage, bring illuminated by giant lights. it often is uncomfortably hot. this is also a problem in video recording.
  - ars 14y ago
    And this would make it worse. It cools the lamp by sending the heat outward in the form of light. It does not cool the recipient in any way, in fact it requires that the recipient already be cooler than where the lamp is.
    - aw3c2 14y ago
      oops, my bad. I thought I understood it from the comments here and did not read the article.
- gsivil 14y ago
  I am sorry that I cannot elaborate more on that for now(4am) but the cooling effects of light are known for quite some time already. Please check laser cooling as a keyphrase.
ars 14y ago
Keep in mind it only works if the light is being sent to an area that is cooler than where the lamp is. It's basically converting the heat difference into light. So you can't use it just to cool, it doesn't work that way.
- davorak 14y ago
  I think where the light is being sent is open space so what ever temperature the local background radiation is at; a common local minimum being the cosmic background radiation.
  - ars 14y ago
    > a common local minimum being the cosmic background radiation No, that's only if you are in outer space. On earth it's the temperature of the air, or the walls. It doesn't matter if the light eventually gets to outer space - what matters is that there is something hotter near you (namely the air). i.e. it's not where the photons end up that matters, it's the total of all the photons that are being sent in your (the lamp's) direction that counts.
    - davorak 14y ago
      Sorry if what I said was unclear. > it's not where the photons end up that matters, it's the total of all the photons that are being sent in your (the lamp's) direction that counts. This is what I was referencing when I siad "the local background radiation." The common minimum was supposed convey high frequency when choosing a random spot in the known universe. > On earth it's the temperature of the air, or the walls. The temperature of the air only comes into play if it is emiting radiation at the frequency of light produced by the led and at greater intensity. I do not see why this would be required.
      - ars 14y ago
        > The temperature of the air only comes into play if it is emiting radiation at the frequency of light produced by the led and at greater intensity. Blackbody radiation. Air (everything) always emits light. > I do not see why this would be required. It's a fundamental law of thermodynamics that requires a heat source and a cold source in order to convert heat into some other form of energy. The air around you is the cold source, and the LED lamp is the hot source. If the LED is colder than the air it will not work - the LED must be hotter (in this particular case they put it in an oven).