E10 Quantum Cosmology and Inflation

Topic

Quantum cosmology attempts to describe the universe during its very first fractions of a second—a period when the Planck scale marks the precise limit of what known physics can describe.

Cosmic inflation is a fleeting period of accelerated exponential expansion that explains why the universe turned out so flat and homogeneous; furthermore, it sowed the seeds—derived from quantum fluctuations amplified by that very expansion—of the temperature variations observed today in the cosmic microwave background.

Primordial nucleosynthesis, which occurred during the first few minutes of the early universe, produced the observed proportions of hydrogen, helium, and trace amounts of lithium—proportions determined precisely by the baryon density and the temperature of the universe at that early stage.

The temperature of the cosmic microwave background drops as the universe expands, scaling in direct proportion to the redshift factor of the background light since the moment that radiation was released.

Temperature fluctuations in the cosmic microwave background are minuscule—on the order of just one part in a hundred thousand—yet these tiny seeds, subsequently amplified by gravity, gave rise to all later cosmic structure: galaxies, galaxy clusters, and the vast voids separating these structures. Both the cosmic microwave background and primordial nucleosynthesis independently confirm this same cosmological model. Thus, from the initial fractions of a second with which this document begins to the double confirmation that concludes it—spanning cosmic inflation and primordial nucleosynthesis—quantum cosmology traces the origins of everything we see in the sky today, from the simplest hydrogen to the largest galaxy cluster, back to tiny fluctuations that occurred at the very first instant of the universe itself.

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