Expert: Tom Whiting - 6/2/2005

Question
I read that the current thinking is that the universe is around 18 billion years old (give or take several billion).  We now have pictures of gallaxies that are around 12 billion light years from Earth.  So how did all this matter (other gallaxies) get so far away?  The speed of light I understand.  But how did all this matter travel at near the speed of light?  I thought that was impossible.

Answer
Hi Dan,
Well, I think the current age is stated as 13.7 Billion, plus
or  minus 0.3 billion years...but no matter...

Yes, we see the light of galaxies out there 12 billion ly
and they are probably receding from us at a high fraction of
light speed...they can never equal or exceed light speed...
But it's only "matter"  that is restricted, and it isn't the
galaxies that are expanding, it's the SPACE itself, or more
accurately, the space-time continuum that is expanding.
So since only matter that is restricted, there is no such
restriction on space itself...space can expand (or contract)
as fast or as slow as it wants to....the speed of light
speed limit....only applies to mass, not to space, shadows,
etc...massless items.
{It's kind of like an empty canoe- a distant galaxy-  traveling down a fast moving creek or stream, going faster and faster.}

We know that those early galaxies are receding very
rapidly because we already observe, with red shift,  what is called ultraviolet galaxy "drop-out" and even visual light galaxy drop-out...as some galaxies are moving so fast away from us that their light is red-shifted (doppler effect) down into the infrared and even radio portion of the electromagnetic spectrum....so we are relying more and more on infrared telescopes and radio telescopes due to that reason, for the most distant galaxies.  The ultraviolet and visible light wavelengths are stretched down to the lower part of the band.

Another food for thought tid-bit...the estimated lifespan
of our known visible Universe is in the hundreds of
trillions of years....little red dwarf stars have an estimated
lifespan of several trillion years...so looking at it that way,
this Universe just began last month!  The Solar System
formed up about 4.6 billion years ago, like last week!
We humans have just arrived yesterday (~3 million years).!

So this Universe has just begun.    97% of the Universe is
still hydrogen/helium from the Big Bang....Supernovae have only processed up to only 3% of the heavier elements (Lithium to Uranium) ....so we are very lucky to be here this early....how many other places had, or have, an excess of the 3% heavies?  Not too many, in my opinion....so we hit the Big Lottery, and probably are alone in the Milky Way Galaxy.  
True, there are a lot of stars and galaxies, but they also
sell billions of Powerball lottery tickets too...but there is only
one winner every 4 or 5 months...so sheer numbers are
meaningless...you've still have to have the carbon, oxygen,
iron, aluminum, etc., heavy elements, to have intelligent life, or any life for that matter.  (as life is defined as a chemical processes, and if you don't have the "elements"...you can't have life, because there are no chemical processes with
only hydrogen and helium (an inert gas).

Hope all this helps,
Clear Skies,
Tom Whiting
Erie PA


FOLLOW UP....
Oh, I missed part of your question....how did things get so
far away so fast?  Well, they didn't really move that distance...realize that everything we see, including us, are "inside" the Big Bang 'bubble'...we were part of it, along with those distant, early,  galaxies.
So we are really looking back in time, (not necessarily
distance) in all directions---back at galaxies that formed up perhaps just only several million years after the Big Bang.  So the light we see left when the Universe was much smaller, and younger...say only 6 billion ly radius...and while the light was
traversing that vast distance, space has expanded and carried
those distant galaxies to a point we estimate is 12
billion ly distant now.....or then....whatever.  Today, this
second, they could actually now have moved even
farther away, there is no way to tell the present, on distant
galaxies....we only can see backwards in time with a telescope, not the 'present' or not forward in time.
(A telescope is simply a time viewer machine...we are always looking back in time...even the moon we see 1.5 seconds ago....the sun 8.3 minutes ago.)   The main recessional
culprit is the space itself expanding, not the galaxies
themselves...there are no "little rockets" attached to the
individual galaxies...they are just moving along like
the canoe analogy above, along with the general expansion
of space itself.  Which, BTW, is accelerating, not decelerating
as we once believed.  So someday in the distant future,
perhaps a few billion years from now, all we'll see is the
Local Group of Galaxies, and perhaps some of the Virgo
Supercluster, of which we are a member.  All other distant
galaxies will have receded so far away, that they will not
be visible to us....a lonely ending in a few billion more years.
Clear Skies,
Tom Whiting
Erie, PA