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| Nicolaas Vroom... |
 Posted: Fri Sep 04, 2009 6:16 am |
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In Nature Vol 460 20 Augustus 2009 at page 990 we read:
"Once produced, gravitational waves travel through space-time
at the speed of light, and are essentially unaffected by the matter
they encounter. As a result, gravitational waves emitted shortly
after the Big Bang (and observed to day) would carry
unaltered information about the physical processes that generated
them"
My question is how do we know that if we receive for example
a positive signal of around 100Hz that that signal is originated
from for example year 100000 after the Big Bang and not
from year 100000 before present ?
[[Mod. note -- All you know directly from the observations is that
the source was at a place-time such that the signals reach the Earth
"now" with the observed frequency/amplitude spectrum. You need
astrophysical/cosmological context to determine whether it's more
plausible that the source was (for example) 1 light-year away 1 year
ago, 1e5 light-years away 1e5 years away, or from the Big Bang 13e9
or so years ago.
That is, like most other astronomical observations, you have to
combine multiple lines of evidence & inference.
-- jt]]
My first guess is that it is extremely difficult to establish its
physical origin in distance (and time) if you cannot establish
the source vissible.
I also doubt if you can clearly establish gravity waves
from the Big Bang.
My picture of the Big Bang is (for what ever it is worth)
is a boiling pot of matter.
This boiling matter will influence each other by gravitational
interaction.
This boiling process will slowly diminish and so will the strength
of the gravitational interaction, which is a function of the current
process.
This boiling process will slowly come (on average) to a halt
and so the (average long range) gravitational interaction.
Implying all influences from its hectic origin will be damped out.
What we can measure (in principle) are current events
in our neighbourhood.
Nicolaas Vroom |
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