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Re: Old Stars



David, your original question was as follows:

When we look at the oldest stars we can see, we are looking back to
a time just after the big bang. How is it that we (planet earth) have
arrived 'here' before the light that left those stars?


Let me try to clarify the question a bit -- maybe we can get a better response.

Your problem begins, I think, with "oldest stars". The very oldest "stars"
are well over 10\9yrs old. They are less than 1 solar mass and are red
dwarfs. And they will be shining for at least another 10\9yrs. So we don't
know when the light we see from them began.

The very brightest stars are several solar masses and are very young -- All
having formed since Sol formed and all will go super nova within the next
few *million* years.

But let's talk about quasars, light sources older than stars. These formed
15\9yrs ago -- give or take a year or two. These objects no longer exist
presumably having decayed to galaxies or such. So the light we see left them
some 15\9yrs ago and so it has traveled a distance of 15\9ltyrs. But the
interstellar matter Sol was made from can't travel at anything like c, so if
Sol formed 5\9yrs ago and we some time after that, it must have formed well
less than 5\9ltyrs distant from the bang.

Hence, the relative flash of the quasars of 15\9yrs ago must have passed
this spot in the Universe long ago. By some watches at least 10\9yrs ago --
when even the interstellar matter hadn't arrived here. Even the large star
which went super nova to nucleate Sol hadn't even formed yet! So how can we
see the quasars now?

Is that your question?


At this point we might be regaled with stories of curved space-time and how
the quasar flash has made several orbits around the circumference of the
Universe as the Universe AND space have been expanding. But don't believe a
word of it.

Best wishes


Jim.Green@Snow.edu