Chapter 30 — The Afterglow of Creation

In 1948 physicists George Gamow, Ralph Alpher, and Robert Herman predicted that the cooling of the initial hot dense state of the universe should have left behind a uniform glow of radiation—now greatly redshifted into the microwave spectrum—detectable from every direction in the sky.

In 1965 radio astronomers Arno Penzias and Robert Wilson of Bell Laboratories detected an unexplained microwave signal arriving uniformly from every direction at a temperature of 2.725 Kelvin—just under three degrees above absolute zero. When they contacted Robert Dicke at Princeton, who was independently searching for this signal, Dicke reportedly said: "We've been scooped." Penzias and Wilson received the 1978 Nobel Prize in Physics.

In 1992 the COBE satellite mapped the cosmic microwave background with high precision. George Smoot and John Mather led the team. They found temperature fluctuations of approximately one part in 100,000—corresponding to the density variations in the early universe that grew into today's galaxies. Smoot and Mather received the 2006 Nobel Prize in Physics. The magnitude and pattern of these fluctuations require precisely calibrated initial conditions. The afterglow of the Big Bang carries the fingerprint of fine-tuned parameters.

Penzias, A.A. and Wilson, R.W. "A Measurement of Excess Antenna Temperature at 4080 Mc/s." Astrophysical Journal Letters 142 (1965): 419–421. Smoot, G. et al. "Structure in the COBE Differential Microwave Radiometer First-Year Maps." Astrophysical Journal Letters 396 (1992): L1–L5. Nobel Prizes 1978 and 2006: nobelprize.org.

Chapter 31 — Why Is There Something Rather Than Nothing

The Second Law of Thermodynamics governs the direction of every physical process: entropy increases in a closed system over time. Ordered states evolve toward disordered states. Energy concentrations spread out. Structures decay. This gives time its direction. The past had lower entropy than the present; the present has lower entropy than the future.

The problem is that the universe began at extraordinarily low entropy. No physical law required this. A universe beginning at high entropy is vastly more probable than one beginning at low entropy—there are incomparably more high-entropy initial states available than low-entropy ones. The physical laws governing the universe are consistent with a high-entropy beginning. They simply describe what happens after whatever initial conditions are present. The initial conditions themselves are not explained by physics.

Stephen Hawking and Roger Penrose established in their 1970 singularity theorems that the laws of general relativity, extrapolated backward, require a singular beginning at which the usual framework of physics breaks down. Why the beginning had low entropy—why there was order rather than chaos, structure rather than featurelessness, something rather than nothing—is not a question physics answers. It is a question physics poses and cannot escape. Answering it honestly points past physics to the only kind of thing that could determine initial conditions: a choice made by a mind.

Hawking, S.W. and Penrose, R. "The Singularities of Gravitational Collapse and Cosmology." Proceedings of the Royal Society A 314 (1970): 529–548. Penrose, R. The Road to Reality. Jonathan Cape, 2004. Chapter 27.