Re: Evidence for "Big Bang Theory"
jsmill01@ulkyvx.louisville.edu
12 Apr 95 01:26:15 EDT
In article <3mfiko$jl6@lace.Colorado.EDU>, hgibbons@hoshi.Colorado.EDU (Hugh Gibbons) writes:
> Arun Gupta (gupta@mrspock.mt.att.com) wrote:
>> The three pieces of evidence that theories alternate to the Big
>> Bang have trouble coping with are :
>
>> 1. Redshifts of galaxies increases with their distance.
>
> This is commonly explained as evidence *for* there having
> been a big bang. If an explosion occurs, then each of the
> chunks sees all other chunks receding at a speed that's
> proportional to the distance.
>
> Astronomers rely on red-shift as their way of estimating the distances
> of distant (far outside our galaxy) objects, because they now assume
> that there was a big bang.
This is not quite correct. Astronomers rely on red-shift as their way
of estimating the distances of objects well beyond the local group
because it works for objects nearer to us which have had their
distances estimated by some other means (Cepheid variables, globular
clusters, brightest stars, HII regions, size of standard galaxies,
such as spirals).
The steady-state model also contains an expansion of the universe, but
gives no explanation of why, other than it has always existed. The
Big Bang models and their inflationary cousins attempt to give an
explanation of why the expansion is as observed, within the context of
our best theory of gravity today, the general theory of relativity.
So be careful when you make large, sweeping generalizations. The
usually prove incorrect and mark you as one not truely familiar with
the topic at hand.
>
> Question:
> What is the most distant object whose distance was measured *other*
> than by red-shift?
>
According to Kaufmann's "Universe", 2nd edition (not the most current
version I have, but the one here at my desk), supernova can be used as
distance indicators to a distance of about 8 billion lightyears.
There are lots of galaxies within that distance, the distance to which
can be checked/cross-checked with other "standard candles", some of
which I've mentioned above.
J. Scott Miller, Program Coordinator
Rauch Memorial Planetarium
University of Louisville
jsmill01@ulkyvx.louisville.edu
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