What are the axioms (if any) behind the LCDM model of cosmology? NB: axioms, not postulates (e.g., inflation)

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    $\begingroup$ What do you mean by "axiom" and "postulate" -- normally they pretty much mean the same thing. What distinction are you trying to get at? $\endgroup$ – Mark Olson Jun 22 '18 at 13:21
  • $\begingroup$ I think if you edited to indicate prior research, you might get some more activity. Do you mean something like the Wrightman axioms? There is no satisfactory realisation for Wightman axioms in the case of Yang–Mills fields. (wikipedia) $\endgroup$ – James K Jun 23 '18 at 8:54
  • $\begingroup$ @MarkOlson I think it’s commonly understood that axioms are accepted as true (eg universal speed limit is c) whereas postulates are equivalent to hypotheses. $\endgroup$ – Chappo Hasn't Forgotten Monica Jun 23 '18 at 12:38
  • $\begingroup$ @Chappo That distinction was shown to be meaningless during the investigations into the foundations of mathematics in the 1800s, so I'm not assuming that that's what to OP meant. (Maybe he did. In that case, I'd like to hear it.) $\endgroup$ – Mark Olson Jun 23 '18 at 12:57
  • $\begingroup$ It's also worth noting the LCDM model isn't a mathematical theory, but a physical theory. It's certainly wrong to call inflation a postulate -- Inflation itself is a theory that explains certain observations better than any other theory we presently have. But it's still just a fairly poorly validated theory. $\endgroup$ – Mark Olson Jun 23 '18 at 13:00

The fundamental assumptions of LCDM cosmology are:

  1. General relativity is valid on cosmological scales.
  2. Universe is dominated by "cold" dark matter (origin, composition unknown).
  3. The metric of the universe is given by the Friedmann–Lemaître–Robertson–Walker metric.

Reference: https://en.wikipedia.org/wiki/Lambda-CDM_model A combination of 1 and 2 helped explain large scaled structure formation, which is smaller masses merging to become bigger systems while 3 helped explain the expansion of space depending on the matter density.

The lambda parameter comes from invoking general relativity. Although Einstein added it to support his own view of a static universe (disproved a decade later by Hubble's observations), it was later re-interpreted as a negative energy density of space (see Harvey, Alex 2012 https://arxiv.org/pdf/1211.6338.pdf and/or Carroll, Sean 2001 https://arxiv.org/abs/astro-ph/0004075).

Hope this helped.

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