For us, the universe goes only as far as light has traveled in the billions of years since the universe was formed. This visible universe-the universe we know and can talk about-is a million million million million (that’s 1,000,000,000,000,000,000,000,000) miles across. But according to most theories the universe at large-the meta-universe, as it is sometimes called-is vastly roomier still. According to Rees, the number of light-years to the edge of this larger, unseen universe would be written not “with ten zeroes, not even with a hundred, but with millions.” In short, there’s more space than you can imagine already without going to the trouble of trying to envision some additional beyond.
For a long time the Big Bang theory had one gaping hole that troubled a lot of people-namely that it couldn’t begin to explain how we got here. Although 98 percent of all the matter that exists was created with the Big Bang, that matter consisted exclusively of light gases: the helium, hydrogen, and lithium that we mentioned earlier. Not one particle of the heavy stuff so vital to our own being-carbon, nitrogen, oxygen, and all the rest-emerged from the gaseous brew of creation. But-and here’s the troubling point-to forge these heavy elements, you need the kind of heat and energy of a Big Bang. Yet there has been only one Big Bang and it didn’t produce them. So where did they come from?
Interestingly, the man who found the answer to that question was a cosmologist who heartily despised the Big Bang as a theory and coined the term “Big Bang” sarcastically, as a way of mocking it. We’ll get to him shortly, but before we turn to the question of how we got here, it might be worth taking a few minutes to consider just where exactly “here” is.