CE420: Big Bang

Claim CE420:

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Response:

1. The big bang is supported by a great deal of evidence:
   
   
   • Einstein's general theory of relativity implies that the universe cannot be static; it must be either expanding or contracting.
     
     
   • The more distant a galaxy is, the faster it is receding from us (the Hubble law). This indicates that the universe is expanding. An expanding universe implies that the universe was small and compact in the distant past.
     
     
   • The big bang model predicts that cosmic microwave background (CMB) radiation should appear in all directions, with a blackbody spectrum and temperature about 3 degrees K. We observe an exact blackbody spectrum with a temperature of 2.73 degrees K.
     
     
   • The CMB is even to about one part in 100,000. There should be a slight unevenness to account for the uneven distribution of matter in the universe today. Such unevenness is observed, and at a predicted amount.
     
     
   • The big bang predicts the observed abundances of primordial hydrogen, deuterium, helium, and lithium. No other models have been able to do so.
     
     
   • The big bang predicts that the universe changes through time. Because the speed of light is finite, looking at large distances allows us to look into the past. We see, among other changes, that quasars were more common and stars were bluer when the universe was younger.
   
   Note that most of these points are not simply observations that fit with the theory; the big bang theory predicted them.
   
   
2. Inconsistencies are not necessarily unresolvable. The clumpiness of the universe, for example, was resolved by finding unevenness in the CMB. Dark matter has been observed in the effects it has on star and galaxy motions; we simply do not know what it is yet.
   
   There are still unresolved observations. For example, we do not understand why the expansion of the universe seems to be speeding up. However, the big bang has enough supporting evidence behind it that it is likely that new discoveries will add to it, not overthrow it. For example, inflationary universe theory proposes that the size of the universe increased exponentially when the universe was a fraction of a second old (Guth 1997). It was proposed to explain why the big bang did not create large numbers of magnetic monopoles. It also accounts for the observed flatness of space, and it predicted quantitatively the pattern of unevenness of the CMB. Inflationary theory is a significant addition to big bang theory, but it is an extension of big bang theory, not a replacement.

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