Updated to ask readers more directly for their thoughts, if you have any...
A random thought. Suppose we ask whether the world has a Beginning or an End, or whether it is eternal is one or both directions. It seems like there are 5 possible views, which I will name by association to various cultural groups who supposedly have had these views:
- Norse view: the world began, and it will end.
- Greek view: time is infinite in both directions
- Hindu view: time goes in a circle
- Hebrew view: the world began, but it will never end.
- Nobody ever: time had no beginning, but it will still end!
I find it interesting that the first four views all have some intuitive appeal, to different people, but the fifth view just seems horribly wrong and perverse! Why do you suppose that is?
My best guess is that there's is a certain obvious symmetry to treating the past and future in the same way, which makes views (1-3) seem reasonable. And there is also an argument that the past is not like the future, but if so it had better be like (4) rather than like (5)! I guess we all know deep down (it's really the Second Law of Thermodynamics) that it makes sense for the universe to start from a simple initial condition and then develop complexities from there. But if we have to deal with infinite regresses AND we don't even get an eternal universe out of it, that seems a bridge too far... but if anyone has any further thoughts on this, I'd be interested.
My cultural names are a brutal oversimplification, and you shouldn't take my assigning these views to different cultures too literally. For one thing, there were lots of different Greeks and there are lots of different Hindus who believe all sorts of different things. For another, there is a conceptual difference between the world—in the sense of an ordered cosmology with a history—beginning, and time (a much more abstract notion) having a beginning. It takes a certain amount of intellectual sophistication to think about the latter question.
Norse mythology begins with fire and ice swirling around a bottomless pit for aeons; it is only later that a bit of fire strikes a bit of ice and spontaneously generates a giant and a cow, from whom later the jotun and gods emerge by various removes. (As you can see, the Norse were ultimately Materialists even about their so-called divinities.) At the end, the cruel jotun defeat the merry gods and the world is destroyed, plunging back into chaos. So it's not really clear that time has a beginning or end, just that the story has a beginning and an end.
The Hebrews had the notion of divine Creation in Genesis 1:1 and elsewhere, but it is controversial whether Genesis 1:1 actually teaches the creation ex nihilo of later theology. St. Augustine is usually credited with the idea that there was not even time before creation, but in fact Philo, a 1st century Hellenistic Jew, got there first.
Similarly, our current best "concordance cosmology" appears to begin with an initial singularity, but has no end in time. (Well, really we should talk about spacetime, which allows time to end in some places, e.g. inside black holes, but not others.) This appears at first sight to be like the Hebrew view. At late times the universe expands exponentially forever, thinning matter out to a very cold but finite temperature. This is in accordance with the Generalized Second Law of Thermodynamics, which tells us that the universe will reach a boring maximum entropy state at late times. Thus, the story ends at finite time, and we really have the heroic defiance against inevitable destruction, as in the Norse view.
Even in Hebrew cosmology, there is that little matter of the whole universe being destroyed and then recreated again:
“See, I will create
new heavens and a new earth.
The former things will not be remembered,
nor will they come to mind.
But be glad and rejoice forever
in what I will create,
for I will create Jerusalem to be a delight
and its people a joy.
I will rejoice over Jerusalem
and take delight in my people;
the sound of weeping and of crying
will be heard in it no more.
Never again will there be in it
an infant who lives but a few days,
or an old man who does not live out his years;
the one who dies at a hundred
will be thought a mere child;
the one who fails to reach a hundred
will be considered accursed.
They will build houses and dwell in them;
they will plant vineyards and eat their fruit.
No longer will they build houses and others live in them,
or plant and others eat.
For as the days of a tree,
so will be the days of my people;
my chosen ones will long enjoy
the work of their hands.
They will not labor in vain,
nor will they bear children doomed to misfortune;
for they will be a people blessed by the Lord,
they and their descendants with them.
Before they call I will answer;
while they are still speaking I will hear.
The wolf and the lamb will feed together,
and the lion will eat straw like the ox,
and dust will be the serpent’s food.
They will neither harm nor destroy
on all my holy mountain,”
says the Lord. (Isaiah 65:17-25)
It's really this "new heavens and new earth" that will last forever. Christianity is about Death and Resurrection, both for the universe and for each person. Science can get us as far as the doomed-to-die bit, but it can't get us any farther. That is Law, the rest is Grace, revealed in Jesus Christ.