07-18-2010, 04:44 PM
Thanks for this. I read part of the paper, but lost interest quickly for several reasons:
The author throws infinities around with metaphysical abandon. He wants an "infinitely cyclic" model, not because the data suggests it but because he finds the idea attractive. He postulates an astronomical number of causal patches leading to an "infinite multiverse". His model universe cycles an "infinite" number of times to give "infinite parallel universes".
Physics is an observational science. There are no observed infinities. Infinity is a purely mathematical convenience, just like zero. Math isn't science, and neither is logic, in the sense that neither has any necessary connection with the real world. So a physicist who insists on invoking infinities has abandoned his craft, I think. That said, if he confined his inquiry to the last hypothetical cycle and the next one I'd be more inclined to listen.
And seeking a mathematical justification for a cyclic universe seems a fanciful indulgence, where the available data doesn't suggest a cycle and where no one knows how new data might verify the consequences of it.
BTW, I thought the "big crunch" hypothesis was recently discarded:
But even evidence supporting a future "big crunch" wouldn't necessarily support a rebound. It just seems like a fairy tale buttressed with some serious mathematics because by golly he wants things to be cyclical, don't you think?![[Image: smile.gif]](http://i485.photobucket.com/albums/rr217/darkside_999/smile.gif)
String theory isn't testable either, but at least it conceivably could be. And it has the virtue of trying to explain phenomena we can access.
The author throws infinities around with metaphysical abandon. He wants an "infinitely cyclic" model, not because the data suggests it but because he finds the idea attractive. He postulates an astronomical number of causal patches leading to an "infinite multiverse". His model universe cycles an "infinite" number of times to give "infinite parallel universes".
Physics is an observational science. There are no observed infinities. Infinity is a purely mathematical convenience, just like zero. Math isn't science, and neither is logic, in the sense that neither has any necessary connection with the real world. So a physicist who insists on invoking infinities has abandoned his craft, I think. That said, if he confined his inquiry to the last hypothetical cycle and the next one I'd be more inclined to listen.
And seeking a mathematical justification for a cyclic universe seems a fanciful indulgence, where the available data doesn't suggest a cycle and where no one knows how new data might verify the consequences of it.
BTW, I thought the "big crunch" hypothesis was recently discarded:
Quote:Recent experimental evidence (namely the observation of distant supernova as standard candles, and the well-resolved mapping of the cosmic microwave background) have led to speculation that the expansion of the universe is not being slowed down by gravity but rather accelerating. However, since the nature of the dark energy that drives the acceleration is unknown, it is still possible that it might eventually reverse sign and cause a collapse.http://en.wikipedia.org/wiki/Big_Crunch
But even evidence supporting a future "big crunch" wouldn't necessarily support a rebound. It just seems like a fairy tale buttressed with some serious mathematics because by golly he wants things to be cyclical, don't you think?
String theory isn't testable either, but at least it conceivably could be. And it has the virtue of trying to explain phenomena we can access.