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  • #1

    Physicists to the rescue

    I'm trying to wrap my mind about this but not sure if I get it right - anyone able to explain this in plain english ?

    http://arxiv.org/pdf/1302.3031.pdf
    With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion.

    Steven Weinberg
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  • #2
    "Blackbody radiation around hot objects induces ac Stark shifts of the energy levels of nearby atoms
    and molecules"

    Actually discovered by Iron Man, true story.
    Jon Miller: MikeH speaks the truth
    Jon Miller: MikeH is a shockingly revolting dolt and a masturbatory urine-reeking sideshow freak whose word is as valuable as an aging cow paddy.
    We've got both kinds

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    • #3
      Ok this is, very, very simplified apologies if it's too simplistic.

      If gravity is pulling all objects closer together, why do we have stars which are big balls of fire rather than everything always collapsing to a black hole?

      Because as the gasses collapse and get higher pressure they increase in temperature, and eventually get hot enough to start fusion, this creates a great deal of radiation. The star stays relatively stable as the radiation pressure balances the gravitational pressure. As the star burns one type of fuel it will shrink a bit until it gets hot enough to burn the next thing, and will reach a new equlilbrium, or explode, or form a black hole.

      Ok so that's a very, very simple overview of the basics.

      What this paper is saying is that there's another very minor force in play, which actually attracts molecules or atoms towards the black body (star in our scenario above). So our model where there is a balance between gravitational pressure and radiation pressure is overly simplistic. And not only that but in certain situations the new force is stronger than gravity.

      (which isn't hard Gravity is notoriously weak).
      Jon Miller: MikeH speaks the truth
      Jon Miller: MikeH is a shockingly revolting dolt and a masturbatory urine-reeking sideshow freak whose word is as valuable as an aging cow paddy.
      We've got both kinds

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      • #4
        Better summary.

        Blackbody radiation induces attractive force stronger than gravity
        http://phys.org/news/2013-07-blackbody-stronger-gravity.html
        Perfectly non-reflective objects, called blackbodies, produce blackbody radiation when at a uniform temperature. Although the properties of blackbody radiation depend on the blackbody's temperature, this radiation has always been thought to have a net repulsive effect. Now in a new study, scientists have theoretically shown that blackbody radiation induces a second force on nearby atoms and molecules that is usually attractive and, quite surprisingly, even stronger than the repulsive radiation pressure. Consequently, the atoms and molecules are pulled toward the blackbody surface by a net attractive force that can be even stronger than gravity. The new attractive force—which the scientists call the "blackbody force"—suggests that a variety of astrophysical scenarios should be revisited.
        Jon Miller: MikeH speaks the truth
        Jon Miller: MikeH is a shockingly revolting dolt and a masturbatory urine-reeking sideshow freak whose word is as valuable as an aging cow paddy.
        We've got both kinds

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        • #5
          I PUNCH gravity!
          “As a lifelong member of the Columbia Business School community, I adhere to the principles of truth, integrity, and respect. I will not lie, cheat, steal, or tolerate those who do.”
          "Capitalism ho!"

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          • #6
            Originally posted by DaShi View Post
            I PUNCH gravity!
            in the balls!
            To us, it is the BEAST.

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            • #7
              Originally posted by MikeH View Post
              Better summary.

              http://phys.org/news/2013-07-blackbo...r-gravity.html
              Thanks. I think that this solved my problem :

              As the scientists explain, this attraction occurs because atoms and molecules whose ground states are shifted to lower energy levels are drawn toward regions of higher radiation intensity—in this case, blackbodies.
              wich I missed/didn't get.
              With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion.

              Steven Weinberg

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              • #8
                Fississist.
                DISCLAIMER: the author of the above written texts does not warrant or assume any legal liability or responsibility for any offence and insult; disrespect, arrogance and related forms of demeaning behaviour; discrimination based on race, gender, age, income class, body mass, living area, political voting-record, football fan-ship and musical preference; insensitivity towards material, emotional or spiritual distress; and attempted emotional or financial black-mailing, skirt-chasing or death-threats perceived by the reader of the said written texts.

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