In 1927, a Belgian priest named Georges Lemaître used Einstein's General Relativity equations to propose a radical idea: the universe is expanding! Two years later, Edwin Hubble confirmed Lemaître's hypothesis; it later became known as the "Big Bang" theory. The idea of an expanding universe did not sit well with a number of physicists, however, including Einstein. Why? Because it meant the universe had a beginning, and they knew that has enormous theological implications.
Fast forward to the present. Due to a number of dramatic empirical confirmations in the last century, scientists now can't deny that a Big Bang occurred and the universe is expanding. However, many physicists have been trying to come up with models that explain the evidence and include a Big Bang, yet somehow avoid an absolute beginning to the universe. Like the physicists of Lemaître's day, they fear that a beginning requires a theological explanation. They're right. Unfortunately for them, it now appears the universe almost certainly had an absolute beginning.
Famed physicist Alexander Vilenkin has proved mathematically that all the models physicists have conceived of to avoid a beginning, must themselves have a beginning. His proof has been reported by numerous science journals and blogs. He also explained it in person at Stephen Hawking's 70th birthday "party." One science writer called it "the worst birthday present ever" (Hawking is one of the physicists who has been hoping that the universe doesn't have a beginning). Here's why all of this matters:
Religious philosophers and theologians have been offering cosmological arguments for God's existence for thousands of years. The one I find the most persuasive is called the Kalām cosmological argument. It was formulated by Islamic philosophers during the Middle Ages, and has been made popular again by Christian philosopher William Lane Craig (who was a professor of mine in grad school). The argument can be summarized as follows:
Whatever begins to exist has a cause.
The universe began to exist.
Therefore, the universe has a cause.
The argument is simple enough. Premise 1 seems fairly intuitive and appears to be confirmed by all our experiences (we don't tend to observe things popping into existence without a cause). Premise 2 has been dramatically confirmed by science. And the conclusion follows inescapably from the premises. So, what does this have to do with God?
If the universe began to exist, that means it had a cause that brought it into existence. In other words, something had to make the Big Bang happen. What could that cause be like? It can't be a physical cause -- matter came into existence at the Big Bang. Nor can the cause be something that exists in time or space -- they are products of the Big Bang as well. So, the cause of the universe has to be something that is non-physical, spaceless, and timeless (i.e. eternal), yet unfathomably powerful. These are all qualities traditionally attributed to God. Thus, the origin of the universe provides a powerful reason for belief in God's existence.
1. If everything requires a cause, then who made God? The argument doesn't say everything requires a cause -- only things that begin to exist. If God is eternal, then he doesn't have a beginning. He therefore doesn't require a cause. In that case, it doesn't make sense to ask, "Who made God?" It's like asking, "Who made the thing that wasn't made?"
2. In our experience, causes are always physical. Thus, there can be no non-physical causes. The cause of the universe cannot be physical because matter did not exist prior to the Big Bang. So, either the universe just popped into existence from nothing without any cause (something contrary to both intuition and experience), or it has a non-physical cause. Which one seems more likely? (Stay tuned. In #8 of this series, I show there are good reasons to think there are non-physical causes).
3. Quantum particles come into existence without a cause. Do they? Quantum particles are said to emerge from a quantum vacuum that is constantly fluctuating with energy, and is governed by physical laws and forces, such as gravity. Sounds like there are plenty of possible causes there. It would be more accurate to say that some quantum events/particles appear to occur without any detectable cause. That's very different.
4. The universe created itself from nothing. That's nonsense (and I'm not the only one who thinks that). Physicists who claim such things are making horrible equivocations -- they're equating "nothing" with something. By "nothing" they mean the quantum vacuum mentioned earlier, which is definitely something, and which requires an explanation of its own.
5. Our universe may have had a beginning, but the multiverse it's a part of is eternal. Not likely. Vilenkin (himself, a strong proponent of the multiverse) admits that his theorem applies to the multiverse as well. In other words, if there is a multiverse, then it too had a beginning. Other scientists and philosophers have independently argued that the past can't be eternal (see the Kalām argument in more detail), and that multiverse theories may not even be scientific. But even if it were eternal (and actually existed), the multiverse may not be able to escape the argument offered in my next post.
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*To better understand the goals and limits of this blog series, please read the Introduction, if you haven't already. Thanks!
1. There is one new model I haven't had a chance to investigate yet. Roger Penrose released a book in 2012 in which he proposes an eternal cyclical model of the universe. I haven't read it, but reviews seem to suggest it is speculative and untestable. At this point, I don't have any reason to think Penrose's model is any less susceptible to Vilenkin's theorem than the other models. But even if it were, it would have to contend with the argument in my next post, as well as philosophical arguments against the existence of an infinite number of universe cycles (see below).
2. In the paper linked to above, in section 3.4, titled "Problems With Infinity," the authors write, "Can there really be an infinite set of really existing universes? We suggest that, on the basis of well-known philosophical arguments, the answer is No." They go on to cite several mathematical and philosophical problems with the idea of there being an actual infinite number of things in existence. That is essentially what the Kalām argument does as well. These arguments would equally apply to Penrose's new model mentioned in the note above. If an actual infinite number of things can't really exist, then there could not be an infinite number of past cycles in the universe, as Penrose is suggesting.