On the Origin of Time: Stephen Hawking's Final Theory

by Thomas Hertog

The anthropic principle is a counsel of despair, he wrote, my bemusement mounting in sync with his clicking. It is a negation of our hopes of understanding the underlying order of the universe, on the basis of science.

Stephen proved in his thesis that if Einstein’s theory of gravity was right, then the mere existence of these echoes meant time must have had a beginning. Now how did that square with Andrei’s multiverse we were just talking about?

the American physicist Joe Weber claimed to hear frequent bursts of gravitational waves coming from the center of the Milky Way.

He did this because black holes and the big bang were like yin and yang in his thinking—many of Stephen’s key insights into the big bang can be traced to ideas he first developed in the context of black holes.

Both inside black holes and at the big bang, the macroworld of gravity truly merges with the microworld of atoms and particles. Under these extreme conditions, Einstein’s relativity theory of gravity and quantum theory had better work together. Except they don’t, and this is widely viewed as one of the biggest unsolved problems in physics.

I am dying…appeared on the screen. I froze. I glanced at his nurse who was reading quietly in a corner of the office. I looked back at Stephen, who seemed fine, as far as I could tell, and continued clicking away. …for…a…cup…of…tea. This was Britain and it was four p.m.

When we trace the universe back to its earliest moments, we encounter a deeper level of evolution, at which the physical laws themselves change and evolve in a sort of meta-evolution. The rules of physics transmute in the primeval universe, in a process of random variation and selection akin to Darwinian evolution, with particle species, forces, and, we will argue, even time fading away into the big bang.

Stephen and I came to see the big bang not only as the beginning of time but also as the origin of physical laws. At the heart of our cosmogony lies a new physical theory of the origin, which, we came to realize, at the same time encapsulates the origin of theory.

Communication slowed, from a few words per minute to minutes per word, before basically grinding to a halt, even as demand for his voice skyrocketed.[3] Here was the world’s most celebrated apostle of science, unable to talk. But Stephen wouldn’t give up. With our intellectual connection deepened through years of close collaboration we moved increasingly beyond verbal communication. Bypassing Equalizer, sensors, and clickers, I would position myself in front of him, clearly in his field of vision, and probe his mind by firing questions. Stephen’s eyes would light up brightly when my arguments resonated with his intuition. We would then build on this connection, navigating and exploiting the common language and mutual understanding we had forged over the years. It is out of these “conversations” that, slowly but steadily, Stephen’s final theory of the universe was born.

This primeval state is known as the hot big bang. Astronomical observations since the golden 1990s have pinned down the age of the universe—the time elapsed since the big bang—to 13.8 billion years, give or take 20 million. —

Had the hot big bang been perfectly uniform everywhere, there would be no galaxies today.

The ancient CMB snapshot marks our cosmological horizon: We cannot look back any farther. But we can glean something about processes operating in yet earlier epochs from cosmological theory. Just as paleontologists learn from stone fossils what life on Earth used to be like, cosmologists can, by deciphering the patterns encoded in these fossil flickers, stitch together what might have happened before the relic heat map was imprinted on the sky. This turns the CMB into a cosmological Rosetta Stone that enables us to trace the universe’s history even farther back, perhaps as far back as a fraction of a second after its birth.

As we will see in chapter 4, the temperature variations of the CMB radiation indicate that the universe initially expanded fast, then slowed down, and, more recently (about fi...

Slowing down appears to be the exception rather than the rule on the scales of deep time and deep space. This is one of those seemingly fortuitou...

only in a slowing universe does matter aggregate and cluster to form galaxies. If it hadn’t been for the extended near-pause in expansion in our past, there would, again,...

This moment occurred in the early 1930s, when Lemaître made a remarkable sketch in one of his purple notebooks of what he called a “hesitating” universe, one with an expansion history much like the bumpy ride that would emerge from observations seventy years later[*1] (see insert, plate 3). Lemaître embraced the idea of a long pause in the expansion by considering the universe’s habitability.

Make but a small change in almost any of its basic physical properties, from the behavior of atoms and molecules to the structure of the cosmos on the largest scales, and the universe’s habitability would hang in the balance.