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Everything posted by swansont

  1. swansont

    Minus 273.15K

    I don't need to. I know and work with people who have done BEC, and I do laser cooling (to "only" a few microK) on a regular basis. I suspect the journalist involved was misunderstanding and/or sensationalizing the phenomena. Imagine that...
  2. swansont

    Burning Hydrogen

    I think you have that backwards. Hydrogen doesn't explode - it burns very fast. Burning hydrogen uses 3 moles of reactants to produce 1 mole of products, so the result is a 3:1 reduction in volume of gas. All expansion comes from the energy release, as opposed to products that go solid or liquid -> gas, that expand as a result.
  3. swansont

    Complex Wave functions?

    The probabilty is given by the square of the wave function (i.e. you multiply by the complex conjugate). There are things that you can represent easier by using a complex wave function - the wave function itself has no physical meaning, so it doesn't have to be real. As Aeschylus said, it's a matter of convenience.
  4. swansont

    Minus 273.15K

    No. Absolute zero theoretically has all center-of-mass motion of atoms and molecules stopping. But, as you note, it is unattainable.
  5. swansont

    Minus 273.15K

  6. swansont

    Low boiling point liquid, 25-03C

    pentane seems to be a good candidate
  7. swansont

    Observations with Mechanical Devices?

    That was "sweet," not "sweat." The scientist isn't a mechanical device, anyway. Anyway - sometimes things are red because the photons have a certain wavelength, but sometimes it's due to human perception. There are relatively few instances where light is monochromatic, or nearly so. And there are colors that aren't due to a particular wavelength - silver isn't a color of the spectrum; neither is brown. What one perceives as red depends on ambient lighting and surrounding color, and may vary from person to person. And, as a nit, electro-optics aren't technically mechanical means, so hooking up a spectrum analyzer doesn't work anyway.
  8. swansont

    subshells - quantium theroy thing

    That's within each sublevel, given by the magnetic quantum number. As Pulkit noted, there are magnetic 2l-1 sublevels. Within each sublevel there are the spin up and spin down orientations.
  9. I don't think anyone's going to do your lab for you, but if you have questions, ask 'em. I've done all those things.
  10. The KE is not caused by the state of the electron, and is not, in general, caused by photon emission. But some fraction of the atoms will be in excited states based on the temperature of the system.
  11. swansont

    Why is stuff squared?

    Well, there's more to it than that, of course. Just making the units match doesn't mean an equation is valid; it's a necessary but insufficient condition.
  12. swansont

    Direction - A fundamental property?

    Direction depends on your coordinate system. As far as one can tell the basic nature of space is isotropic - there is no preferred direction.
  13. swansont


    Bill Phillips, Eric Cornell, Carl Wieman or Steven Chu?
  14. swansont


    Of the ground state hyperfine levels, with no perturbations (i.e. no E or B field)
  15. swansont


    Cs melting point is about 28.5 C, so it's close to melting at room temp. IIRC Rb is about 37 C. I think it's lower as you move down the list of alkalis, and they become more reactive as well. (Only Fr is below Cs, and as has been noted, there are no stable Fr isotopes) The problem with an alkali melting is that it will then flow, and expose more surface to the air, which can then react.
  16. swansont

    New laptop advice

    I won't be turning my back on you then
  17. swansont


    Depends on what you mean by "visible." A group at Stony Brook trapped 210Fr and took pictures of the fluorescence.
  18. swansont


    It's not animated, but try this
  19. swansont

    Point of light travelling faster than light

    Yest, the point will move faster than c. No, it doesn't necessarily mean we see a discrete set of points - it depends on the photon flux. You could see this effect on a much smaller scale if the photons were emitted slowly (rate-wise) enough. [pre-emptive]Oh, and this doesn't violate relativity, either.[/pre-emptive]
  20. swansont


  21. Neutrinos maximally violate parity. All neutrinos are left-handed; the spin vector and linear momentum vector always have the same relationship.