Michael Roberts wrote:
...........................................
> By 1800 astronomers calculated that light must have taken millions of years
> to come from some stars to the earth. Thus the physics was in place.
While there were speculations about the extent of the sidereal universe
before 1800, the first firm measurement of the distance to a star (11 light years
for 61 Cygni by Bessel) didn't come until 1838. Even in the early part of the
20th century the Milky Way could be thought to be only ~30,000 LY in extent &
many astronomers of the time thought that that was the entire universe. It
wasn't until Leavitt's discovery of the period-luminosity relation for Cepheids &
the establishment of the extragalactic character of many of the nebulae that it
became clear that we were receiving light from many millions of years in the
past.
Shalom,
George
George L. Murphy
http://web.raex.com/~gmurphy/
"The Science-Theology Interface"
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