If all astronomical processes cease, how will the passage of time manifest itself? It is doubtful if vacuum fluctuations can provide a clock for the recording of time. Will time itself come to a stop? Is this a meaningful question? Such questions are difficult to answer.
Doubtless there is a desire in human beings to exist everywhere in space, but there seems to be a much stronger desire to exist everywhere in time, or at least in future time.
The human mind has a different attitude towards 'time' and 'space' as regards the survival of the human race.
Some people, including Hawking, think that we may be able to understand the big bang or the big crunch (in particular, whether time has a beginning or an end at these events) when we have a satisfactory quantum theory of gravitation.
One of the most intriguing problems is to understand the precise nature of time, especially with regard to the big bang, the big crunch and the long-term future of an open universe.
It is clear that there is a very great deal to be learnt about the universe and the endless subtleties of its various manifestations. What about the moral side of man, or what people with a religious bent of mind would prefer to call the spiritual nature of man? How will this develop in the endless aeons of the future? Perhaps in most of these questions like Newton we are still standing on the shore while the great ocean of knowledge lies ahead. It is significant that after more than two centuries of the acquisition of knowledge eminent men of science still have similar feelings.
The precise structure and description of the Galaxy is quite complicated with many unsolved problems. However, from the point of view of the large-scale structure of the universe, the detailed structure of the Galaxy is not very important.
Why should one bother about the ultimate fate of the universe? One answer to this question is similar to the answer to the question about climbing Mount Everest: because the problem exists. It is in the nature of the human mind to seek incessantly new frontiers of knowledge to explore.
It is irrelevant whether or not there are other forms of life in the Galaxy or in other galaxies. The fact that we are here provides an 'existence proof as it is called in mathematics. To say that we are an accident of nature is to miss the point. The laws of nature are presumably eternal and immutable. They do not change in mid-stream and suddenly acquire the ability to create a pretty toy if circumstances arise.
The study of the universe as a whole is a unique enterprise. At least in one sense one is seeking to understand the totality of things. We, as thinking beings, are as much a part of the universe as are neutron stars and white dwarfs and our destiny is inextricably bound up with that of the universe.
One of the most intriguing things about the universe, which probably cannot be explained by scientific investigations, is that it exists and we, who are a part of the universe, are able to contemplate and study it.
It is possible that those strange sentient beings of the far-future cold universe will find contemplating a warm universe such as ours not very pleasant, much as a nocturnal creature shuns daylight. But the more speculative amongst them may look back to our universe and to the Earth as an ideal world full of sunshine and a supply of adequate energy to last for billions of years, a dream world which will have passed away never to return. And what do we human beings do with this ideal dream world of ours? We oppress each other, build nuclear weapons for each other's destruction, and plunder the resources of the Earth!
If the standard model is correct, the universe started in a state of high density and temperature, with all matter and radiation forming one great continuous mass. It is very remarkable that this undifferentiated soup should have the intrinsic property that in due course of time it develops into galaxies of which at least one creates life with such staggering complexity, subtlety and diversity and often such stunning beauty. It also creates thinking and feeling beings which in turn can contemplate the universe and study its properties and which can love and hate.
One way in which a recurrence of life can occur is in the event that the cycle of the big bang and final collapse is repeated, and if galaxies are born again and again conditions for the existence of life may develop in some regions. Whether or not this can happen (assuming that the universe is closed) is, of course, not known.
Indeed, it is not clear whether it is meaningful to talk about 'after' the big crunch, just as it is not clear whether it is meaningful to talk about what happened 'before' the big bang. These questions are not necessarily meaningless, but the fact is we simply do not know.