Many texts and research papers seem to argue the case for the total energy of the universe being zero or constant. Indeed the Friedmann equation is often derived in books using KE+PE=constant, where the constant is zero for a flat universe. The sign of the constant also determines whether the universe recollapses again (or not). I know that in GR it is difficult to deal with the total energy of the universe but surely in a collapsing universe, the energy density would diverge as the universe collapsed so that even thogh there was finite energy in the form of matter and radiation the energy density would grow without bound. In Bianchi anisotropic models the shear also gives rise to a radiation temperature difference which provides an average shear term to be included in the energy density sum. (Lets forget the cosmological constant for the moment). This shear dominates the final collapse in these models and again seems to provide unlimited energy as the assymetrical collapse occurs. For the extreme kasner metric the energy from shear grows as one over the time from big crunch. I don't think I am mixing up energy with energy density here (energy density will go to infinity for even small amounts of matter as the volume decreases) - but I am a bit confused about Taub like collapse because it seems as though there is infinite available energy from the shearing weyl curvature collapse. Thus there must be an infinite energy content rather than zero in these anisotropic models. Is this the right way to interpret this? Especially since anisotropy(weyl curvature) could develop from normal symmetric(Ricci) curvature as a universe collapses - e.g. chaotic collapse.(adsbygoogle = window.adsbygoogle || []).push({});

I know that the current data fits an accelerating universe but that does not mean collapsing models are unphysical. If the CC is due to a scalar field which can decay then recollapse will occur any way so the jury is out on the final fate of the universe but the questions about energy still remain.

Can any one put my understanding on the right track with this?

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# Total energy of the universe

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