Chaotic inflation was confirmed by observation recently. Inflation is a conjecture within the framework of big bang cosmology that posits that spacetime expanded faster than the speed of light early in the universe’s history. Sounds simple enough, but it has implications far beyond obscure debates among theoretical physicists. From Livescience:
The new research also lends credence to the idea of a multiverse. This theory posits that, when the universe grew exponentially in the first tiny fraction of a second after the Big Bang, some parts of space-time expanded more quickly than others. This could have created “bubbles” of space-time that then developed into other universes. The known universe has its own laws of physics, while other universes could have different laws, according to the multiverse concept. [Cosmic Inflation and Gravitational Waves: Complete Coverage]
“It’s hard to build models of inflation that don’t lead to a multiverse,” Alan Guth, an MIT theoretical physicist unaffiliated with the new study, said during a news conference Monday. “It’s not impossible, so I think there’s still certainly research that needs to be done. But most models of inflation do lead to a multiverse, and evidence for inflation will be pushing us in the direction of taking [the idea of a] multiverse seriously.”
In other words, inflation makes it very probable that numerous other universes exist now, have existed in the past, and will exist in the future. Parallel universes. We have woken up in a reality that resembles science fiction.
Theists have argued that the laws of physics are so precisely set for life to exist that it would be almost impossible for our universe to support life if God hadn’t created it. We atheists have pointed out that the same argument has been made before: people once thought planet Earth was so well-adjusted to support life that we could only explain it with a miracle. Astronomy, on the other hand, has given us evidence that billions and billions of other planets exist. If a life-friendly planet is one out of ten million, we don’t need God to explain it. We can explain it with the law of large numbers: if a life friendly planet is one out of ten million, but we’ve got billions and billions of planets, at least one or two will wind up being able to support life. We atheists have pointed out that there’s an easy way to explain why our universe is life-friendly: there are lots and lots of universes, and because there are so many, at least one had to wind up friendly to life by chance. The multiverse was at first just a speculation. It was a better speculation than God: after all, God was the wrong explanation for planet earth; the right answer was the law of large numbers. Moreover, we pointed out that multiverse theories, like chaotic inflation, were able to explain things that the God theory didn’t. Stephen Hawking goes over the case for inflation in The Grand Design as does Lawrence Krauss in A Universe From Nothing. But predicting evidence before the fact is always more impressive than explaining evidence after the fact. Inflation has now done that, and that is impressive.
Theists will no doubt protest the new support for inflation. Robin Collins argues that chaotic inflation requires a bit of ‘fine-tuning,’ that very specific conditions have to hold before inflation will happen. I see no merit in this objection. First what exactly is Collins saying? If he is saying that chaotic inflation is an ad-hoc theory, he needs to meet his burden of proof and argue that the assumptions made by chaotic inflation can’t be justified by the evidential support it has. If he is arguing that chaotic inflation would still require God’s handiwork, it’s hard for me to take that seriously. If “God did it” could do any explanatory work here, you’d have to show that positing the existence of God made inflation more probable than atheism does. But what theologian can argue with a straight-face that “God really wanted a universe with chaotic inflation of spacetime”? Moreover, you’d think inflation was much better explained under atheism, since atheism and the multiverse fit together like a hand in a glove.