Hot Science in a Cold Universe
The cosmic background radiation (CBR) was discovered in 1964, and was crucial evidence for the "big bang." The temperature of the CBR is about 2.73 K, as expected in a universe that has undergone Hubble expansion for about 15 billion years. Within the last couple of years, studies of temperature fluctuations at the microKelvin scale exhibit a power spectrum that opens the door to precision cosmology. These peaks in the CBR contain information about the composition and structure of the early universe.

The universe is expanding; but beyond the Hubble expansion, recent observations show that the expansion is accelerating with a positive sign. Evidently, about 65% of the energy denisty in the universe is so-called "dark energy," which gives effectively a negative pressure that drives the acceleration. But nobody reall knows what dark energy is. The best understanding of it we have so far is a "vacuum energy."

To learn more about recent observations and interpretations in cosmology, read the following "Elegant Connection" articles, first published in the SPS Observer and Radations magazine on big bang cosmology.

1. Big Bang Cosmology, Part 1: The Expansion of the Universe (Coming soon)
2. Big Bang Cosmology, Part 2: Nucleosynthesis and the Background Radiation
3. Light and Two Curves, One Century Apart

 

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