Speed of Light; Age of Universe
When viewing Hubble deep field images on the Internet, we
are told we are looking at how the objects looked at that time i.e.
12 billion years ago. Assuming nothing can exceed the speed of
light, including the expanding universe, how can we see light from
12 billion years ago if we are moving away from the big bang slower
than the light we are looking at?
If we took a look at a galaxy, say in January, and then again in June,
we would be looking at that particular galaxy from two corners of a
triangle (with the galaxy forming the last point of the triangle), and
have the longest possible edge length between the measuring points (since
the Earth will have moved between the farthest points of its orbit around
the Sun). Using the angle of sighting, we can then triangulate the distance
of that particular galaxy. We can estimate the distance of that galaxy from
the Earth. If we then find that the galaxy is so far such that it would take
12 billion years for the light of that galaxy to reach us, then we have to
accept that whatever information the light that is currently reaching us
contains -must be 12 billion years old.
Greg (Roberto Gregorius)
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Update: June 2012