version of this book
The known universe is immense beyond imagination but not beyond calculation. We can give it a size and a lifetime, not with any great confidence in the accuracy, but with good reasons for believing the estimates are correct within an order of magnitude. Of course there is no guarantee and other possibilities such as steady state models cannot be completely ruled out. However the evidence is strong that our universe started as an immense explosion called the big bang and will end in either the thermal death of unending expansion and continuously increasing entropy or will collapse to an immensely dense state know as the big crunch.
Does this mean we live in a huge but finite universe? We will never know with certainty but I prefer to think our universe is potentially infinite and will evolve throughout a future without limits . Historically every previous attempt to bound our universe has been woefully inadequate and I hope the current attempt will suffer the same fate. There is no reason to assume that our local big bang is the only big bang in the universe. General relativity requires that universes beyond a certain critical mass and density (black hole s) are closed to each other. Things can enter the universe but nothing, not a single bit of information, can leave. If that is absolutely true then it may make little difference if the universe is infinite. However black holes do radiate and do emit information with that radiation. We do not know if that radiation has any correlation with the internal state of the black whole just as we have no idea what happens inside a black holes once the density exceeds certain limits. At that point known physics ends and there are many possibilities.
My favorite fantasy is a potentially infinite universe with an unbounded expanse of big bangs collapsing into big crunches and then exploding again as big bangs. Over time the size of these universes increase. Perhaps the process started with some nearly uniform initial conditions. Just as cells, individuals and cultures are born and die so do entire universes. The big bang/big crunch cycle may be a necessary process to `recycle' entropy. There is no known process that could decrease entropy but we have no idea what happens in the collapse of a black hole past a certain density. The enormous densities are a good candidate for creating order our of chaos by some laws completely outside of our current understanding. Some process of this sort is necessary if a potentially infinite universe is to evolve for an unbounded future .
Evolution requires information transfer from those from the big crunch to those in the ensuing big bang who are each other. There are many possibilities. Perhaps there is a way for some small mass to escape the big crunch through interaction with other universes at the points of greatest expansion. Perhaps by altering the shape of the big crunch we can alter evolution in the next big bang. Perhaps there is information from the previous big crunch in some encoded form in our universe that we will someday with yet undreamed of technology be able to decode.
Perhaps the next frontier beyond space is the universes beyond the next big crunch. Perhaps one of the stages of evolution is an entire universe as an individual living, dyeing, reproducing and evolving.
version of this book