Considering the origins of the universe with Year 8 students after lunch on a Friday is a challenge. Schroedinger somehow crept into the conversation, (well, his cat did anyway). Among the questions considered was whether time travel was possible, the students agreed that it was not, otherwise someone would have arrived to tell us about it.
The class’s conception of time was as something linear, past, present and future in a straight line, to have questioned that idea would have been a step too far on a Friday. Perhaps an opportunity will come to introduce Einstein to the conversation.
Einstein conceived of space and time as one, it was not a question of space existing in time, but space-time being a single continuum; the whole of time exists in a single moment that embraces the whole of space. (So, ghosts, deja vu, premonitions, all those so called paranormal experiences, are explicable as simply glimpses of all those things hat have happened, and will happen, simultaneously to the present moment).
Conventional scientific thought believes the universe began 13.5 billion years ago with a massive explosion of matter and space to fill the nothingness that previously existed, or didn’t exist as the case may be, nothingness having no existence. Since that moment, space has been getting bigger, and time, being part of a single continuum, has expanded with space. Human lives have been led in a single, linear direction, beginning at the cradle and ending at the grave.
But, some thought suggests, there will come a point when the outward momentum of the universe comes to an end, when inertia will slow down, and eventually halt, the progress of the galaxies. Eventually, the gravity that holds the universe together will exert a pull that is stronger than the last remnant of momentum left from the Big Bang and the universe will begin to contract.
As the process of the creation of space is reversed, time, being one with space, will also be reversed. At some point, perhaps billions of years hence, space-time will be at the point where it is at this moment, except the journey will be a return one rather than an outward one, and time, as part of reversing space, time will presumably be also reversed: life will begin at the grave and end with our birth.
There are theories that the universe goes through a series of expansions and contractions, but if there are tens of billions of years between each of our appearances, there will be plenty of time to work out the best way to live. All of which is too much for a Friday.