Cycles of Time: An Extraordinary New View of the Universe
Roger Penrose
Language: English
Pages: 304
ISBN: 0307278468
Format: PDF / Kindle (mobi) / ePub
This groundbreaking book presents a new perspective on three of cosmology’s essential questions: What came before the Big Bang? What is the source of order in our universe? And what cosmic future awaits us?
Penrose shows how the expected fate of our ever-accelerating and expanding universe—heat death or ultimate entropy—can actually be reinterpreted as the conditions that will begin a new “Big Bang.” He details the basic principles beneath our universe, explaining various standard and non-standard cosmological models, the fundamental role of the cosmic microwave background, the paramount significance of black holes, and other basic building blocks of contemporary physics. Intellectually thrilling and widely accessible, Cycles of Time is a welcome new contribution to our understanding of the universe from one of our greatest mathematicians and thinkers.
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weeks. According to relativity, the notion of ‘simultaneous’, for distant events, is not an absolute thing, but depends upon some observer’s velocity to be specified, so the slicing of space-time into a family of simultaneous 3-spaces is subjective in the sense that for a different observer velocity we get a different slicing. What Minkowski’s space-time achieves is to provide an objective geometry, that is not dependent on some arbitrary observer’s view of the world, and which does not have to
hypersurface . To before the Big Bang? Surely not: the Big Bang is supposed to represent the beginning of all things, so there can be no ‘before’. Never fear—this is just a mathematical trick. The extension is not supposed to have any physical meaning! Or might it …? Part 3 Conformal cyclic cosmology 3.1 Connecting with infinity 3.2 The structure of CCC 3.3 Earlier pre-Big-Bang proposals 3.4 Squaring the Second Law 3.5 CCC and quantum gravity 3.6 Observational implications 3.1
the charge-current vector J, so that exactly the same Maxwell equations hold as before,[3.3] but now with all operations defined in terms of ĝ rather than g. Accordingly, any solution of the Maxwell equations, with one particular choice of conformal scale, goes over to an exactly corresponding solution when any other choice of conformal scale is made. (This will be explained in slightly more detail in §3.2, and more fully in Appendix A6.) Moreover, at a primitive level, this is basically
the condition that the conformal curvature merely be finite (which was what Tod’s proposal gave directly), namely that this conformal curvature really does vanish at the of each aeon, in accordance with the original idea of WCH. Fig. 3.5 The conformal scale factor goes cleanly from positive to negative at crossover, the curve having a slope that is neither horizontal nor vertical. Here ‘conformal time’ just refers to ‘height’ in a suitable conformal diagram. Fig. 3.6 The gravitational field
energies that we are concerned with here, though it could perhaps be playing a role in the way that conformal invariance ‘dies off’ as rest-mass begins to be introduced. 3.5 D.J. Gross (1992), ‘Gauge theory – Past, present, and future?’, Chinese J Phys. 30 no. 7. 3.6 The Large Hadron Collider is intended to collide opposing particle beams at an energy of 7×1012 electronvolts (1.12 μJ) per particle, or lead nuclei at an energy of 574 TeV (92.0 μJ) per nucleus. 3.7 The issue of inflation is
