A New View of the Universe that made my head hurt.
Cycles of Time – An Estraordinary view of the Universe (2010) by Roger Penrose
2.1 Our Expanding Universe
p60-1 “One should not think of the Big Bang as being localized at some particular region of space. The view that cosmologists take in accordance with Einstein’s perspective of general relativity, is that at the time that it occurred, the Big Bang encompassed the entire spacial spread of the universe, so it included the totality of all the physical space, not merely the material content of the universe. Accordingly space itself is taken to have been, in an appropriate sense, very tiny at the time.”
2.2 The Ubiquitous Microwave Background
p75 “…at the present epoch of the universe’s evolution, the greatest entropy contributions, by far, lies in black holes, like the one at the centre of our own Milky Way galaxy, with a mass around 4,000,000 times the mass of our Sun. The total entropy in such objects completely swamps that in the CMB [cosmic microwave background], which had previously been thought to represent the dominant contribution too the entropy present in the universe. Thus, the entropy has greatly increased via gravitational condensation from what it was at the creation of the CMB.”
p77 “…the energy that the Earth receives from the Sun by day is essentially equal to that which the Earth returns to the darkness of space! If this were not so, then the Earth would simply heat up until it reaches such an equilibrium. What life depends upon is the fact that the Sun is much hotter than the darkness of space, and consequently, the photons from the Sun have a considerably higher frequency (namely that of yellow light) than the infra-red photons that Earth returns to space.”
p78-9 “So what the Sun does for us is not simply to supply us with energy, but to provide this energy in a low-entropy form, so that we (via the green plants) can keep our energy down, this coming about because the Sun is a hot spot in an otherwise dark sky… This applies, also, to the Sun’s ability to raise water from the oceans high up into the clouds, which again depends crucially on this temperature difference.”
2.3 Space-time, null cones, metrics, conformal geometry
p93 “If m is a particle’s mass (assumed to be constant), then we find that it has a rest energy E given by Einstein’s famous formula
E=mc2
which is fundamental to relativity theory. the other, almost equally famous formula – fundamental to quantum theory – is Max Planck’s
E=hv
(h being Planck’s constant), telling us that this particle’s rest energy defines for it a particular frequency v of quantum oscillation. In other words, any stable massive particle behaves as a very precise quantum clock, which ‘ticks away’ with a specific frequency
v=m (c2/h)
in exact proportion to its mass,via the constant (fundamental) quantity c2/h.”
2.4 Black Holes and Space-Time Singularities
p98 “Whereas the Big Bang is seen as the beginning of time, the singularities in black holes present themselves as representing the end of time – at least as far as the fate of that material that has, at some stage, fallen into the hole is concerned. In this sense, we may regard the problem presented by black-hole singularities to be the time-reverse of that presented by the Big Bang.”
p117 “Yet, if we take the very very long view, and bear in mind that the exponential expansion of our universe will, if it continues indefinitely, lead to a vast cooling in the CMB, we would expect it to get down to the temperature of even the largest black holes that are likely ever to arise. After that, the black hole will start to radiate away its energy into the surrounding space, and in losing energy it must also lose mass (by Einstein’s E=mc2). As it loses mass, it will get hotter, and gradually, after an incredible length of time (perhaps up to around 10100 years for the largest black holes around today) it shrinks away completely, finally disappearing with a ‘pop’…”
3.3 Earlier pre-Big-Bang proposals
p171″[Lee] Smolin makes the tantalizing suggestion that when black holes form, their internal collapsing regions – through unknown quantum-gravity effects – become converted to expanding ones by some kind of ‘bounce’, each one providing the seed of a new expanding universe phase. Each new ‘baby universe’ then expands to a ‘full-grown’ one with its own black holes, etc., etc.”
302 Days to Dec 21st 2012
