@ Andrew
Looks like there is a difference in world view here. I'll state my position.
I believe that science is generally a step-wise attempt to refine how things work, with the occasional big breakthrough/upheaval. If there is a wonderful new breakthrough that can give us centuries more resource, then great! However, to actually bet the world's future energy resources/requirements on scientists developing some major breakthrough just when we need it seems a little irresponsible to me.
This may be a little bit "out there" in terms of thought, but maybe - just maybe! - the world should start looking at finding a way to live within the means of *known* resources for a change, without depending purely on human inventiveness to get out of the mess we could very easily find ourselves in. If we find a wonderful new resource we can exploit, then obviously the standards of living and what we can achieve can also be increased. If, though, we do not look at living within our means, the potential crash is frightening.
Yes, it would be nice to live in a world of pure optimism assuming that scientists and engineers will come through and continue providing breakthrough after breakthrough (because, let's face it, politicians and economists are a totally busted flush), eventually even defeating the presently known laws of physics. But then, I'm not that much of an optimist.
In other news: the Earth isn't infinte.