Yousuf Khan wrote:
N:dlzc D:aol T:com (dlzc) wrote:
Are there parts of space so far
away from us that it's expanding away from us *faster* than
the speed of light?

We expect so, yes.

Okay great, then assuming by some discovery we find out how much of the
universe is outside of our viewing range, will that affect the
calculations for the age of the universe?

Not for our part of the universe. The portion of the universe outside
the region from which light has or could have travelled to us cannot
have had an effect on the part of the universe we can, in principle,
observe. To do so, some sort of information about the outside region
would have to have travelled faster than the speed of light to
influence us.

Bruce Scott TOK wrote:
Basically, although we see objects at distance we also see them in the
past and it is that which is relevant. We can see that the state of the
universe is different at high redshift than at zero redshift, and due to
the redshift distance relation this is interpreted as a difference
between past and present epoch. Note that this has a frame-independent
definition: proper time since the initial singularity. When we speak of
the age of the cosmos, we are really giving a number to this coordinate
in the Robertson-Walker metric. We can extrapolate from observations
enough to tell that there is a fundamental limit to this epoch of cosmic
time regardless of how much of the spatial extent of the universe we can
see.

I assume you're talking about things like quasars, which we see lot of
in the past and in the distance, but not so much nearby. Is it possible
that these locations are so far off, that we only see the brightest
objects from there?

Yousuf Khan

Yousuf Khan wrote:
Bruce Scott TOK wrote:

Basically, although we see objects at distance we also see them in the
past and it is that which is relevant. We can see that the state of the
universe is different at high redshift than at zero redshift, and due to
the redshift distance relation this is interpreted as a difference
between past and present epoch. Note that this has a frame-independent
definition: proper time since the initial singularity. When we speak of
the age of the cosmos, we are really giving a number to this coordinate
in the Robertson-Walker metric. We can extrapolate from observations
enough to tell that there is a fundamental limit to this epoch of cosmic
time regardless of how much of the spatial extent of the universe we can
see.


I assume you're talking about things like quasars, which we see lot of
in the past and in the distance, but not so much nearby. Is it possible
that these locations are so far off, that we only see the brightest
objects from there?

Yousuf Khan


Quasars where much more prevalent in the earlier universe and have
evolved into much weaker entities today.

18 billion .
Hubble constant ..do the math.
the wavelength hits 0 around 18 .
The edge of the universe hubble images 16 so far.
BGR is the zone going past c .
Dark energy is the photons at 0 wavelength passing us at c from outside
the universe.
Energy under presure is space full of photons with no wavelengh at c.

Ben Rudiak-Gould wrote:
The "speed" of the CMBR, in units of comoving distance over cosmological
time, is much larger than the speed of light. I think it's about 3.2c. This
means essentially nothing, since the speed of light has no special status
when talking about cosmological recession velocities.

Oh BTW, if the CMBR is "comoving" so fast away from us, how are we able
to detect its microwaves at all?

Yousuf Khan

Jim Black wrote:
Okay great, then assuming by some discovery we find out how much of the
universe is outside of our viewing range, will that affect the
calculations for the age of the universe?

Not for our part of the universe. The portion of the universe outside
the region from which light has or could have travelled to us cannot
have had an effect on the part of the universe we can, in principle,
observe. To do so, some sort of information about the outside region
would have to have travelled faster than the speed of light to
influence us.

So if the age of the universe is always based on only what we can see,
wouldn't that mean that the age of the universe will always be fixed at
the current age (of whatever estimate you want to use)? If the estimate
says the age of the universe is 13.7 billion years old now, then the
universe will forever be 13.7 billion years old, even if we do the
calculation a 100 billion years or a trillion years from now.

Yousuf Khan

Dear Yousuf Khan:

"Yousuf Khan" wrote in message
oups.com...
....
So if the age of the universe is always based on only what we
can see, wouldn't that mean that the age of the universe will
always be fixed at the current age (of whatever estimate you
want to use)? If the estimate says the age of the universe is
13.7 billion years old now, then the universe will forever be
13.7 billion years old, even if we do the calculation a 100
billion years or a trillion years from now.

No, because the information we base our conclusions on is
imbedded in this Universe with us. The determinations of the
temperature of the CMBR about 1 Gy ago, showed the CMBR was
warmer (about 9 K).

David A. Smith

Kemchan wrote:
yes there are parts of the univ. we can't see...yet...the light hasn't had
time to reach us yet.

And will that light ever reach us? Isn't it a bit like trying to walk
up a down-escalator, or walk down an up-escalator?

Yousuf Khan

Sam Wormley wrote:
Quasars where much more prevalent in the earlier universe and have
evolved into much weaker entities today.

In the earliest parts of the universe do we only see quasars, or do we
see normal galaxies too?

Yousuf Khan

Yousuf Khan wrote:
Jim Black wrote:

Okay great, then assuming by some discovery we find out how much of the
universe is outside of our viewing range, will that affect the
calculations for the age of the universe?

Not for our part of the universe. The portion of the universe outside
the region from which light has or could have travelled to us cannot
have had an effect on the part of the universe we can, in principle,
observe. To do so, some sort of information about the outside region
would have to have travelled faster than the speed of light to
influence us.


So if the age of the universe is always based on only what we can see,
wouldn't that mean that the age of the universe will always be fixed at
the current age (of whatever estimate you want to use)? If the estimate
says the age of the universe is 13.7 billion years old now, then the
universe will forever be 13.7 billion years old, even if we do the
calculation a 100 billion years or a trillion years from now.

Yousuf Khan


There is more than one way to estimate the age of the universe.

Ref: http://www.astro.ucla.edu/~wright/cosmolog.htm#News

New Age for the Universe

30 Jun 2005 - This week's Nature has a letter giving a new determination
of the age of the Universe based on the age of the isotopes. 238U and
232Th are both radioactive with half-lives of 4.468 and 14.05 Gyrs but
the uranium is underabundant in the Solar System compared to the expected
production ratio in supernovae. This is not surprising since the 238U has
a shorter half-life, and the magnitude of the difference gives an estimate
for the age of the Universe. But the production ratio is poorly known from
nuclear physics models, so Dauphas (2005, Nature, 435, 1203) combines the
Solar System 238U:232Th ratio with the ratio observed in very old, metal
poor stars to solve simultaneous equations for both the production ratio
and the age of the Universe, obtaining 14.5 +2.8/-2.2 Gyr.

See: http://www.astro.ucla.edu/~wright/cosmolog.htm#News