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Every time this toy shows up, I try to remind people that it doesn't have the grandest scale right. First, the observable universe. From WP: The comoving dist

Every time this toy shows up, I try to remind people that it doesn't have the grandest scale right. First, the observable universe. From WP: The comoving distance from Earth to the edge of the observable universe is about 14 billion parsecs (46.5 billion light-years) in any direction. The visible universe is thus a sphere with a diameter of about 28 billion parsecs (about 93 billion light-years). Assuming that space is roughly flat, this size corresponds to a comoving volume of about 3×10^80 cubic meters. This is equivalent to a volume of about 41 decillion cubic light-years short scale (4.1 × 10^34 cubic light years). Now for the whole universe: According to the theory of cosmic inflation and its founder, Alan Guth, if it is assumed that inflation began about 10^-37 seconds after the Big Bang, then with the plausible assumption that the size of the Universe at this time was approximately equal to the speed of light times its age, that would suggest that at present the entire Universe's size is at least 10^23 times larger than the size of the observable Universe.

9ec4c12949a4f3 16y ago
Ah, but in the earliest part of the big bang, time didn't exist. Now what?
- cryptoz 16y ago
  You are incorrect. There is no concept of time or space "before" the Big Bang; I say "before" in quotes because there is no "before" the Big Bang. In the earliest part of the Big Bang time did exist. The Big Bang created time.
  - 9ec4c12949a4f3 16y ago
    Simple question here, when did I ever say before? Edit: In the early universe, before the plank epoch when we had particles of plank length or less, you know, things with a schwarzschild radius? The entire universe made of things that are black holes, nothing but black holes? Those time-ending particles that disappeared in their own hawking radiation? The first early 10^−43 seconds, where time didn't actually exist? Those were the good old days.
    - cryptoz 16y ago
      You didn't. Sorry, my phrasing was poor. You said that time didn't exist at the earliest part of the Big Bang, and I was trying to clarify that time didn't exist "before" the Big Bang but did immediately after.
    - hugh3 16y ago
      The first early 10^−43 seconds, where time didn't actually exist? If time didn't exist, then how did the universe know when those 10^-43 seconds were up? Seriously, I think this discussion is proceeding at a level which probably shouldn't be attempted by non-cosmologists. We all probably have a bunch of misconceptions we've picked up from popularizations about the Big Bang, and would only embarrass ourselves if any cosmologists happen to show up.
  - jerf 16y ago
    This really ought to be phrased something more like "According to the best current model of the universe, there was no time until the big bang occurred. However, this model has known flaws; it is the best because we haven't got anything better, not because it is actually correct. Many competing models have been proposed, many of which include some form of time before the big bang." It really should not be stated as unassailable fact that time started with the big bang. It isn't even unassailable fact that the big bang must have erased all information about the previous universe.

9ec4c12949a4f3 16y ago

Ah, but in the earliest part of the big bang, time didn't exist. Now what?

cryptoz 16y ago
You are incorrect. There is no concept of time or space "before" the Big Bang; I say "before" in quotes because there is no "before" the Big Bang. In the earliest part of the Big Bang time did exist. The Big Bang created time.
- 9ec4c12949a4f3 16y ago
  Simple question here, when did I ever say before? Edit: In the early universe, before the plank epoch when we had particles of plank length or less, you know, things with a schwarzschild radius? The entire universe made of things that are black holes, nothing but black holes? Those time-ending particles that disappeared in their own hawking radiation? The first early 10^−43 seconds, where time didn't actually exist? Those were the good old days.
  - cryptoz 16y ago
    You didn't. Sorry, my phrasing was poor. You said that time didn't exist at the earliest part of the Big Bang, and I was trying to clarify that time didn't exist "before" the Big Bang but did immediately after.
  - hugh3 16y ago
    The first early 10^−43 seconds, where time didn't actually exist? If time didn't exist, then how did the universe know when those 10^-43 seconds were up? Seriously, I think this discussion is proceeding at a level which probably shouldn't be attempted by non-cosmologists. We all probably have a bunch of misconceptions we've picked up from popularizations about the Big Bang, and would only embarrass ourselves if any cosmologists happen to show up.
- jerf 16y ago
  This really ought to be phrased something more like "According to the best current model of the universe, there was no time until the big bang occurred. However, this model has known flaws; it is the best because we haven't got anything better, not because it is actually correct. Many competing models have been proposed, many of which include some form of time before the big bang." It really should not be stated as unassailable fact that time started with the big bang. It isn't even unassailable fact that the big bang must have erased all information about the previous universe.