Slashdot Mirror


Physicists Turn Pull Into Push

sciencehabit writes "It's textbook physics: An electric charge near the surface of a material gets pulled toward the surface. However, if the charge is spread out into the right shape and moves fast enough, that attraction becomes a repulsion, one physicist calculates. The odd finding could help physicists avoid unexpected effects when guiding beams of particles such as electrons."

10 of 60 comments (clear)

  1. Great explanations by jez9999 · · Score: 4, Funny

    It's textbook physics: An electric charge near the surface of a material gets pulled toward the surface. However, if the charge is spread out into the right shape and moves fast enough, that attraction becomes a repulsion, one physicist calculates.

    This finally explains so much about women's behaviour towards me.

  2. Re:They could have just asked any geek by Anonymous Coward · · Score: 5, Funny

    So you are saying that if a geek guy stops and listens to a girl, that she'll find him attractive?

  3. Re:ION engines? by Anonymous Coward · · Score: 4, Informative

    It isn't like an ion engine at all. What they are saying is that electrostatic induction is not always attractive but it takes very specific conditions to make it repulsive. An ion engine doesn't use induction. Induction is the force between a neutrally charged object and a charged object.

  4. Re:They should work on the reverse by multiben · · Score: 4, Funny

    Sure we do. Rope!

  5. Re:They could have just asked any geek by somersault · · Score: 5, Insightful

    Yeah that is about when the average female starts to think a solid mate who will provide for her and care about her, is a tad more important than playing idiotic mindgames, teasing, and whoring for attention

    Counter-point: it's also when your average geek has settled into a well paying job/career.

    --
    which is totally what she said
  6. Re:Repulsion Engines Online by Tough+Love · · Score: 4, Insightful

    If it works, it's antigravity just as much as a table leg is. In that sense, we have already had antigravity for some time. What you really meant to say is: land speeder, finally.

    --
    When all you have is a hammer, every problem starts to look like a thumb.
  7. Re:They should work on the reverse by Tough+Love · · Score: 5, Funny

    Why didn't I think of that? A matter beam. Brilliant.

    --
    When all you have is a hammer, every problem starts to look like a thumb.
  8. Re:They should work on the reverse by Carewolf · · Score: 4, Funny

    All personal at battle stations: Fire the matter beam!!

    *poke*

  9. Re:theoretical bs by Chuckstar · · Score: 4, Informative

    Nothing in the article violates the laws of physics. It's merely a question of who did the math more accurately for the specific case of the given arrangement of electrons.

    Cherenkov radiation is a well understood phenomenon. What you are missing is that the cosmic speed limit is the speed of light in a vacuum. Where the speed of light is slower (i.e. glass), it does not violate the laws of physics for a particle to move faster than that speed. In the given example: the electrons move faster in glass than light moves in glass, but still slower than light moves in a vacuum.

  10. Re:theoretical bs by History's+Coming+To · · Score: 4, Informative

    Nope, they're referring to Cerenkov radiation, it's a known effect and produces a very pretty blue light in nuclear reactors. It occurs when the phase velocity travels faster than the speed of light in that medium which is all fine and dandy and breaks no rules at all.

    --
    Please consider this account deleted, I just can't be bothered with the spam anymore.