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Is there any place on earth

  1. Apr 3, 2009 #1

    LE0

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    Is there any place on earth free of all electromagnetic radiation (eg. microwaves, radio waves, or all possible combinations of the electric and magnetic field)? (manmade or existing by itself)
     
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  3. Apr 3, 2009 #2

    mgb_phys

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    There is nowhere free of the Earth's magnetic field. And you always have the thermal background of the Earth and the sky.

    There are a few radio-quiet areas where natural barriers and distance from civilisation mean there is less background RF and local rules restrict electrical equipment. They are usually home to radio telescopes.
     
  4. Apr 3, 2009 #3

    LE0

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    Quick question, what would be the simplest way to find out if there is any electromagnetic radiation around you?
     
  5. Apr 3, 2009 #4

    mgb_phys

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    Open you eyes - if you an see anything there is at least one source of EM?

    Depends what kind of EM you are intersted in.
    There is light (fairly easy to detect) and infrared (from the ground, sky and any hot objects) everywhere.
    Microwaves (cell phone, wifi) is shorter range so there is less of it if you aren't in sight of a transmitter.
    Radio (tv, radio stations) you can detect with a radio. It gets pretty much everywhere unless you are a 100s of km from any town.
     
  6. Apr 3, 2009 #5
    Well, if you want to get technical.. yes(up to a point, of course)

    The NSA, Pentagon, and likely numerous other government/non-government facilities have significant abilities within some "rooms' to preclude unwanted EM influence.
    A faraday shield on steroids.
     
  7. Apr 3, 2009 #6

    mgb_phys

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    although I doubt they are perfect blackbodies at absolute zero.
     
  8. Apr 3, 2009 #7
    No, quantum mechanics rules this out. In the vacuum inside a conducting box the electromagnetic field is in its ground state. But in this ground state the electromagnetic fields are only zero on average.
     
  9. Apr 3, 2009 #8
    I would think that the technology involved with a "closed room highest state-of-affairs" is extremely sophisticated and, as such, presumably classified.
    But it's interesting nonetheless!!
     
  10. Apr 4, 2009 #9

    Vanadium 50

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    Nonetheless, it's not a perfect black body at absolute zero.
     
  11. Apr 4, 2009 #10
    OK, well, my understanding is that trying to externally monitor a "closed-room" session is like trying to hear a cricket on Jupiter.
     
  12. Apr 9, 2009 #11
    Obviously if you put something in your room then you're going to have EM because anything that isn't at absolute zero emits blackbody radiation. So there's really two discussions going on, the people talking about 'how cool the rooms in the pentagon are' are missing the point that others are making that is, if you are IN said room then there is going to be EM inside it since YOU GIVE OFF INFRARED (anything that has a temperature gives off blackbody EM) so there's going to be EM in the room.

    Now, as long as there isn't a source of EM in the room (i.e. anything electronic or with a temperature above -273.15 degrees celsius) (which kinda like saying, inside this box is complete darkness but you can't open it to check, thus making the box kinda pointless if you want darkness), then I'd imagine the most effective EM shielding one could produce would be inside a conductor inside a superconducting box since superconductors push out external magnetic fields (perfectly in theory).
     
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