Modern Cosmology: Science or Folktale?

In the 1980s, cosmologists predicted that very distant galaxies would be too faint for the cameras of the Hubble Space Telescope to capture. Yet "deep field" images of the HST revealed a rich array of such galaxies. Image courtesy of Robert Williams and the Hubble Deep Field Team and NASA.

By Michael J. Disney
American Scientist
September-October 2007

Edited by Andy Ross

The current Big Bang paradigm has it that the cosmos is expanding out of an initially dense state and that by looking outward into space, one can, thanks to the finite speed of light, look back to much earlier epochs. This understanding owes much to two accidents: astronomers' discovery of redshifts in the spectra of distant nebulae and the fortuitous detection of an omnipresent background of microwave noise, which is believed to be the remnant of radiation from a hot and distant past. Set in the theoretical framework of Einstein's general theory of relativity, such observations lead to a model that makes predictions and can thus be tested.

Big Bang cosmology is five separate theories constructed on top of one another:

1. Expansion, historically but not fundamentally rooted in general relativity, explains the redshifts and happily also accounts for the cosmic background radiation.
2. Inflation is needed to solve the horizon and "flatness" problems of the Big Bang.
3. The Dark Matter hypothesis is required to explain the existence of contemporary visible structures, such as galaxies and clusters, which otherwise would never condense within the expanding fireball.
4. Some kind of description is needed for the "seeds" from which such structure is to grow.
5. Dark Energy is needed to allow for the recent acceleration of cosmic expansion indicated by the supernova observations.

In its original form, an expanding Einstein model had an attractive, economic elegance. Alas, it has since run into serious difficulties, which have been cured only by sticking on some ugly bandages: inflation to cover horizon and flatness problems; overwhelming amounts of dark matter to provide internal structure; and dark energy, whatever that might be.

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