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B Light could destroy anything

  1. Feb 26, 2017 #1
    Every material absorbes some light, right? -even a mirror! So I ask myself: is there anything bigger than the wavelength of that light that cannot be destroyed with a powerful lightsource? (for example laser)
     
  2. jcsd
  3. Feb 26, 2017 #2

    phinds

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    Well, black holes come to mind.
     
  4. Feb 26, 2017 #3

    ZapperZ

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    I'm going to tell you why your question here is rather puzzling, because this is a physics forum (full of professionals) and often times, the nature of the question is as important as the answer itself:

    1. If the object is bigger than the wavelength of the light (and you didn't put any upper bound on the size), then what exactly do you mean by "destroyed"? If I just punch a 1-mm diameter hole in a slab of steel 1 square meter, have I "destroyed" the slab? If I ablate the top 10 nm of the material from a clump of iron, have I "destroyed" it?

    2. Why does it have to be a "laser"? Why would the coherence of the light source make any difference? And do we have a time scale for how long this light impinges on the material to destroy it? Or should it only be done by a single photon?

    There are many words and terminologies that we use everyday that appear to be clear and well-defined. But when it is put in the context of science, these words are often vague and ambiguous. This is what is happening here.

    Zz.
     
    Last edited: Feb 26, 2017
  5. Feb 26, 2017 #4
    Sufficiently powerful and focused light, (or other EM), could completely vaporize a small material object.
    Obviously the more massive the object is, the more powerful the light has to be to do that.
    I'd guess that producing/focusing light powerful enough to instantly vaporize anything much more than about 1 gram of say iron is probably beyond current technology
    Even though an object could be vaporized, the individuals atom which made up the object will still exist,
    though they probably will exist as plasma; atomic nuclei with some or even all electrons stripped.
    (The stripped electrons will return when the plasma cools)
     
    Last edited: Feb 26, 2017
  6. Feb 26, 2017 #5

    davenn

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    maybe you haven't seen the current technology for laser metal cutters ?
    they go through a few mm of steel like a hot knife through butter :smile:

    an example .......

    laser-cut-metal.jpg

    there are some really serious laser etching processes out there too .....

    http://www.bing.com/videos/search?q...717C19228A0C08A63793717C19228A0C0&FORM=VRDGAR


    Dave
     
  7. Feb 26, 2017 #6
    Impressive definitely, but not in the 'destroy anything' category.
     
  8. Feb 26, 2017 #7

    phinds

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    I think his point was just that your estimate of 1 gram was WAY off, not that it could destroy anything. Laser cutting of steel plates for shipbuilding has been done for almost 50 years. In the 70's I wrote an assembly language program for a minicomputer to control such a process.
     
  9. Feb 26, 2017 #8
    OK, but back to the original question, which I interpreted to be about if focused light could be effectively used as a range weapon.
    I doubt it.
     
  10. Feb 26, 2017 #9

    phinds

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    I agree, at least for even coming close to total destruction.
     
  11. Feb 26, 2017 #10

    berkeman

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    Wow, what a beautiful piece. What is it used in? If for a chain drive, why the even/odd offset spacing? It sure looks on-purpose...
     
  12. Feb 27, 2017 #11
    Yeah, light does not destroy things like for example antimatter does (by annihilation). However, that is not needed to "destroy" the structure of something (for example a drone with a long range laser weapon).
     
  13. Mar 2, 2017 #12

    Baluncore

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    There is nothing that cannot be destroyed by a powerful light source, given enough time and energy.

    “Too much light will destroy anything”. Is true because the quantity “too much” is defined as enough light to destroy anything.

    Next consider the question: What happens when an irresistible force acts on an immovable object ?
     
  14. Mar 2, 2017 #13

    DrClaude

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    On these words of wisdom, thread closed.
     
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