12 ms·
Ta. Been a while since I did my masters (astrophysics & cosmology), and ideas tend to drift into things which aren't quite right without steering and practice.
by madaxe 13y ago
Ta. Been a while since I did my masters (astrophysics & cosmology), and ideas tend to drift into things which aren't quite right without steering and practice.
That said - re: the measurement of a volume within a gravity well - how would you measure said volume? If you were to use light, surely it would take more time from an external reference frame to traverse (external chronometer) than it would within (internal chronometer), ergo meaning that the space is equivalently larger to the decrease in the time vector (as you can only convert space into time and vice versa).
Re: voids - I know that their hypothesis is that there's more space in the voids - but why could it not equally be the fact that there is less? More time (due to very low mas density/near-absence of gravity), ergo less space - and therefore redshift due to photons decelerating relative to our frame of reference (but constant v of c in theirs) as they move back into "normal" space.
Re: spacetime "keeping time" - true - but that also depends on your premises :) I like loop quantum gravity, and view time as an entropic thermodynamic process which can't exist without interactions... although the lack of quantisation jitter seen from pulsar light suggests that this might be wrong.
- pdonis 13y agohow would you measure said volume? Make a lot of local measurements of small volumes, and add them up. (Yes, I know we can't actually do that with voids a billion light years away; but when the Tardis paper talks about "volume", as I read their math, that kind of measurement is what they mean.) If you were to use light, surely it would take more time from an external reference frame to traverse (external chronometer) than it would within (internal chronometer) This is true, but I do not think it means what you think it means. See below. ergo meaning that the space is equivalently larger to the decrease in the time vector (as you can only convert space into time and vice versa) This doesn't make sense to me. Can you give a reference or show some actual math? I know that their hypothesis is that there's more space in the voids - but why could it not equally be the fact that there is less? I didn't say there couldn't be less; I said that assuming that there was less would be inconsistent with their hypothesis (which is that there is more), so it makes no sense to combine that assumption with their hypothesis and expect a sensible answer. that also depends on your premises The "Tardis" paper assumes the same premises, so it seems reasonable to keep them when discussing the paper.