“Each religion makes scores of purportedly factual assertions about everything from the creation of the universe to the afterlife. But on what grounds can believers presume to know that these assertions are true? The reasons they give are various, but the ultimate justification for most religious people’s beliefs is a simple one: we believe what we believe because our holy scriptures say so. But how, then, do we know that our holy scriptures are factually accurate? Because the scriptures themselves say so. Theologians specialize in weaving elaborate webs of verbiage to avoid saying anything quite so bluntly, but this gem of circular reasoning really is the epistemological bottom line on which all ‘faith’ is grounded. In the words of Pope John Paul II: ‘By the authority of his absolute transcendence, God who makes himself known is also the source of the credibility of what he reveals.’ It goes without saying that this begs the question of whether the texts at issue really were authored or inspired by God, and on what grounds one knows this. ‘Faith’ is not in fact a rejection of reason, but simply a lazy acceptance of bad reasons. ‘Faith’ is the pseudo-justification that some people trot out when they want to make claims without the necessary evidence.But of course we never apply these lax standards of evidence to the claims made in the other fellow’s holy scriptures: when it comes to religions other than one’s own, religious people are as rational as everyone else. Only our own religion, whatever it may be, seems to merit some special dispensation from the general standards of evidence.And here, it seems to me, is the crux of the conflict between religion and science. Not the religious rejection of specific scientific theories (be it heliocentrism in the 17th century or evolutionary biology today); over time most religions do find some way to make peace with well-established science. Rather, the scientific worldview and the religious worldview come into conflict over a far more fundamental question: namely, what constitutes evidence.Science relies on publicly reproducible sense experience (that is, experiments and observations) combined with rational reflection on those empirical observations. Religious people acknowledge the validity of that method, but then claim to be in the possession of additional methods for obtaining reliable knowledge of factual matters — methods that go beyond the mere assessment of empirical evidence — such as intuition, revelation, or the reliance on sacred texts. But the trouble is this: What good reason do we have to believe that such methods work, in the sense of steering us systematically (even if not invariably) towards true beliefs rather than towards false ones? At least in the domains where we have been able to test these methods — astronomy, geology and history, for instance — they have not proven terribly reliable. Why should we expect them to work any better when we apply them to problems that are even more difficult, such as the fundamental nature of the universe?Last but not least, these non-empirical methods suffer from an insuperable logical problem: What should we do when different people’s intuitions or revelations conflict? How can we know which of the many purportedly sacred texts — whose assertions frequently contradict one another — are in fact sacred?”

“When it came time for me to give my talk on the subject, I started off by drawing an outline of the cat and began to name the various muscles.The other students in the class interrupt me: “We *know* all that!””Oh,” I say, “you *do*? Then no *wonder* I can catch up with you so fast after you’ve had four years of biology.” They had wasted all their time memorizing stuff like that, when it could be looked up in fifteen minutes.”

“What I have done is to show that it is possible for the way the universe began to be determined by the laws of science. In that case, it would not be necessary to appeal to God to decide how the universe began. This doesn’t prove that there is no God, only that God is not necessary.”

“The role played by time at the beginning of the universe is, I believe, the final key to removing the need for a Grand Designer, and revealing how the universe created itself. … Time itself must come to a stop. You can’t get to a time before the big bang, because there was no time before the big bang. We have finally found something that does not have a cause because there was no time for a cause to exist in. For me this means there is no possibility of a creator because there is no time for a creator to have existed. Since time itself began at the moment of the Big Bang, it was an event that could not have been caused or created by anyone or anything. … So when people ask me if a god created the universe, I tell them the question itself makes no sense. Time didn’t exist before the Big Bang, so there is no time for God to make the universe in. It’s like asking for directions to the edge of the Earth. The Earth is a sphere. It does not have an edge, so looking for it is a futile exercise.”

“Photons have mass? I didn’t even know they were Catholic.”

“In the beginning there was nothing, which exploded.”

“I once read in my physics book that the universe begs to be observed, that energy travels and transfers when people pay attention. Maybe that’s what love really boils down to–having someone who cares enough to pay attention so that you’re encouraged to travel and transfer, to make your potential energy spark into kinetic energy.”

“No, this trick won’t work… How on earth are you ever going to explain in terms of chemistry and physics so important a biological phenomenon as first love? ”

“Sometimes I wonder if my heart is like a black hole–it’s so dense that there’s no room for light, but that doesn’t mean it can’t still suck me in.”

“Physics isn’t the most important thing. Love is.”

“I’ll be looking for you, Will, every moment, every single moment. And when we do find each other again, we’ll cling together so tight that nothing and no one’ll ever tear us apart. Every atom of me and every atom of you… We’ll live in birds and flowers and dragonflies and pine trees and in clouds and in those little specks of light you see floating in sunbeams… And when they use our atoms to make new lives, they wont’ just be able to take one, they’ll have to take two, one of you and one of me, we’ll be joined so tight…”