Do you think that before the big bang was possible to speak about thermodynamics? Or even the energy was defined? Notice that the existence of energy means that the homogeneity of the time was necessary. Could we guarantee it?

   The big bang is only a theory which assumes absolute ignorance before the first bang, at least nowadays, in all that I know.

Actually not quite absolute ignorance. See Penrose's cyclical universes scenarios, or Martin Bojowald's loop quantum cosmology, for instance. There are different possible BBs (Penrose, Tryon, etc.), all of which would manifest in the same way although they would be triggered very differently. Absolute rest is likely an impossibility, even in a possible  "pre BB" scenario.

Dear Chris,

   Your last sentence has left me a little puzzling: "Absolute rest is likely an impossibility". Absolute rest of what?

   In all that I know, the Big Bang theory it is not related with the motion of matter, but expanding space that is used to explain the redshift with distance. Thus it is argued that the wavelength of light is longer due to 'stretching' space and the Hubble expansion constant is obtained in agreement the microwave noise observed. That is a fantastic outcome obtained in the seventies. But even the distribution of the matter in the universe or the problem of the horizonts ( Guth theory of inflactionary universe) are needed.

   Please, could you explain a little bit what your last sentence and what Penrose says in his theory of what happened  before the big bang singularity?

  Dear Chris,  

  Let me summarize just three points which makes me see problems with the possibility to go before the Big Bang, from my humble point of view and trying to explain me better:

  1- The Big Bang theory is not founded on the Doppler effect but a theoretical concept of expanding space.

  2- It is then assumed that space exists and as we speak about the Universe, I cannot see how its motion can be observed from an external frame.

  3- Thermodynamics is not obviously followed, at least in a simple form, because a finite universe created by the Big Bang the second law of thermodynamics would cause it to encrease entropy and disorder. The fact is that this is not observed, the universe is highly ordered

Dear Daniel,

Good points - my reference to 'absolute rest' copies the phrase from the question itself, which is what I was quoting. A conundrum is that whereas vacuum is a hive of quantum activity post-BB, picturing a 'vacuum' without a froth of quantum activity pre-BB is rather hard to do (the Tryon scenario, and other views - Bojowald 'showing' that the pre existence of time is a necessary condition for a BB to be able to happen, or Jennifer Chen and Sean Carroll making calculations (fundamentally equivalent to Tryon's) calculating the frequency of virtual energy spikes capable of causing a BB, etc., all suppose a quantum type vacuum pre BB.)  Absolute rest, as phrased in the question, supposes a scenario whereby nothing exists prior - not space itself (of any dimensionality), nothing, which makes then in one fell swoop the Tryon, Bojowald, Penrose, and Chen/Carroll scenarios impossible. Then we don't have much to stand on, unless we blithely adopt John 23rd's views.

BBs are only one way universes can come into existence, as you are well aware - in a multiverse environment there is no reason why any one universe would have been begotten in any specific way, and different scenarios are possible. As you point out, this does not quite explain the inception of such things as space itself - there are a number of possibilities, including some very exotic ones, none of which however can work if a single universe scenario is adopted. There are also the issues of both space and time dimensionalities and a number of tricky issues such as arrows .... We don't have all the answers, but some putative scenarios are quite interesting. Your point 3, of course, is one of the enduring conundrums ....

About Penrose - you might want to read his 'Cycles of Time' book if you haven't yet?