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Seeing Earliest Galaxies, Speed of Light, Distance
Name: Russel
Status: student
Grade: 9-12
Location: IA
Country: USA
Date: May 2, 2011
Question:
If Earth is now seeing light from early galaxies born 13 billion years ago, and we all came from the same Big Bang, how did Earth beat the speed of light to get to present location so quickly?
Replies:
Russel,
Unfortunately, because we do not, as yet, have the technology to
replicate the energies and densities involved in a Big Bang, we can
only extrapolate to what conditions must have existed in the very
first tiny fraction of a second of the Big Bang. However, much of
our math and data suggest that the Big Bang indeed resulted in the
expansion of the universe - BUT what was expanding in that first
fraction of a second, was not galaxies and planets, but rather
subatomic particles and elementary particles. In effect, our theory
states, that in that first fraction of a second, the universe grew
exponentially and was filled with subatomic particles. Still within
a tiny fraction of a second, these subatomic particles combined to
form matter. A few minutes after the Big Bang lighter nuclei and
years later electrons and nuclei started forming atoms. After a
really long period of time, these atoms started forming larger
masses (due to gravitational effects). So by the time stars,
planets, galaxies formed, the universe is pretty much as large as it
is now - the sudden expansion had slowed down really dramatically.
So when we say that we are only now beginning to see light from
across the galaxy, it is because that light did indeed not start
until the universe was already very much expanded.
Greg (Roberto Gregorius)
Dear Russel,
Good question.
Earth did not beat the speed of light. Galaxies 13 billion
years old are easily visible from Earth using powerful telescopes,
especially the Hubble. We do not, however, see all the way back to
the moment of the Universe's birth, since that was too long ago.
Sincerely
David H. Levy
You have to be very careful when referring to time, distance, expansion of
the Universe, the speed of light and related subjects. Things are very
counter-intuitive. The "age" of the Universe is based upon Doppler shifts of
radiation (light). The larger the shift the older and further apart are the
source and "us". The "oldest" and "further apart" are the sources of the
radiation -- microwave background. Now here you have to "hang up" your
intuition. Unlike our classical intuition, it is not like there is some
outside observer "watching" all of this going on. After the "Big Bang" space
itself is being created. There is no outside observer looking at all this
going on. Space itself is being created -- not like watching a train going
by, but like the train itself is being created. Now that is pretty weird!!
But that is necessary to understand the experimental data. The Earth is/was
not in a race with some other object, because then you have to put down some
outside marker to measure the motion of the Earth (actually the whole Milky
Way galaxy) compared to some other object(s). But there are not any such
outside observers, because then you have to compare the motion of our galaxy
against this outside common reference. But there are not any such common
references. So the Earth is not/was not in some sort of race with another
galaxy/astronomical body.
We do not have any experience with the Earth comparable to actually creating
space and time on the scale of the Universe. This all sounds complicated,
because it is! The whole concept of actually "creating" space and time is a
concept where we have no parallel experience in our experience.
Vince Calder
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Update: June 2012
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