Recent content by John Helly

  1. J

    High School Expansion and raisin bread

    Sorry about the thread. I get confused by all the options and conventions yet to be discovered. Hoping a reply to this doesn't make it worse. What is it about gravity, presumably due to visible and dark matter, that exactly negates the expansion? Is there a thread you can suggest to the math...
  2. J

    High School Expansion and raisin bread

    Fascinated as I am of learning about cosmology, one metaphor seems particularly strained: the raisin bread metaphor for expansion. I get the notion of the dough expanding and how this accounts for the speed differential of the galaxies relative to each other; but what about the raisins...
  3. J

    Undergrad Where did the early photons go?

    Ok. The 1D example is helpful. Is there a place in the literature I can start to find the math that underlies this? I would like to get a feeling for what that is like and try to tie it to the bigger puzzle.
  4. J

    Undergrad Where did the early photons go?

    I interpret this as analogous to 'zooming' a view in an image. The coordinates are not changing but user's viewport is.
  5. J

    Undergrad Where did the early photons go?

    Mahalo. I will have to ponder this for a while.
  6. J

    Undergrad Where did the early photons go?

    Ah.
  7. J

    Undergrad Where did the early photons go?

    Ok. But what was expanding, then, and still is? Must be some kind of domain? Excuse me, I'm an earth scientist trying to wrap my head around cosmology.
  8. J

    Undergrad Where did the early photons go?

    Mahalo. I will read the link.
  9. J

    Undergrad Where did the early photons go?

    What scale factor? What is being scaled if the domain is infinite?
  10. J

    Undergrad Where did the early photons go?

    Mahalo for the reply. Yet, at the perimeter of the plasma they must do something different, no? Is it a black hole at the edge, for example? Is there an estimate of the velocity (field?) of expansion of the edge of the universe? What would/do photons do when the encounter(ed) the edge of the...
  11. J

    Undergrad Where did the early photons go?

    Since photons travel at c, where did they travel to, or was the universe expanding at the speed of light (or faster)?
  12. J

    Undergrad Reconciling smooth spacetime with variable, rotating, earth gravity

    Mahalo. That helps greatly. J.
  13. J

    Undergrad Reconciling smooth spacetime with variable, rotating, earth gravity

    Aloha. I'm studying Sean Carroll's Spacetime text and just beginning to understand the differential approximations to spacetime curvature. I'm trying to learn general relativity. However, as an oceanographer, I am familiar with the gravimetry satellite measurements and wonder how to reconcile...
  14. J

    Revisiting the Feynman Ball on an Inclined Plane Problem

    Well, this is what I came up with and it's obviously wrong but I don't know why.
  15. J

    Revisiting the Feynman Ball on an Inclined Plane Problem

    Mahalo.