Recent content by earnric

  1. earnric

    Is the universe truly expanding?

    space-time is not "nothing" ... space-time is a stage on which matter, energy and time play out... Why it has negative pressure and 'expands' is still unknown: but we can say we observe that this is a characteristic of space-time. I think that's about as far as physics will take you.
  2. earnric

    Is the universe truly expanding?

    If you consider the "line" to be space-time itself, you have the idea. You can easily extend this idea to 2D by considering the surface of a balloon. Blow it up a little, use a marker to create dots on the surface... Blow it up more: you will notice that every dot moves away from every other...
  3. earnric

    Is the universe truly expanding?

    Space(-time) is a "thing" ... it has dimensions and (from our measurements of the expansion) a negative pressure. The more space-time you have, the more negative pressure. Hence the 'expansion' of space accelerates. This is what we are measuring. We don't yet have a good handle on the source...
  4. earnric

    Solid angle (and integral of a sine function)

    Oops! My bad: symmetric is the wrong word. As you realized, Sin reflects THRU the origin -- about both x and y... not just the y-axis as I implied. Sorry!
  5. earnric

    Solid angle (and integral of a sine function)

    Since Cos[t] = Cos[-t], the integral should be identically 0. If you think about it, Sin is symmetric about the origin: hence any definite integral centered on 0 (i.e. - {-t -> t}) MUST 'sum' to 0.
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