Sam Wormley wrote:
Yousuf Khan wrote:

Isn't it possible that given only what we can observe, we will always
come up with a finite age for the universe, and it will always be the
same age limit no matter when we do the calculation? For example if
we're calculating the age of the universe to be somewhere around 15-20
billion years old now, then a 100 billion years from now another set of
observers will look at what they can see in the universe at that time,
and they too will come up with 15-20 billion years rather than 115-120
billion?

We estimate the age of the universe to be about 13.7 billion years.
As the universe expands faster and faster, our observable horizon
will begin to shrink and we will no longer be able to "see" the early
universe.

The portion of the early universe (by which I mean the universe at the
time the CMBR was emitted) that we can see must always be expanding (by
which I mean we that in the future, we see things that were further
away). For this region to shrink, light which has already reached us
would have to reach us again. It is possible, however, for the part of
the early universe we can see to asymptotically approach some bound.