E2.0: Sean Carroll: The Origin of the Universe

This is the 15th in a new series of weekend posts taken from the presentations at the Salk Institute’s “Beyond Belief: Enlightenment 2.0.”. I have placed an index of essays in this series in an introductory post, Enlightenment 2.0: Introduction.

The next speaker in this conference was Sean Carroll, Senior Research Associate in Physics at the California Institute of Technology. Sean Carroll is interested in the origin of the universe – specifically, with the idea that the start of the universe is something that is difficult to explain and something for which people are tempted to claim there is a need for a God. Contemporary cosmology suggests that the universe started with a ‘big bang’ about 14 billion years ago which had to start somehow, and that somehow was God.

Carroll wants to suggest that this is not such a problem, for which there is not much of a reason to postulate the existence of a God. Carroll’s argument is that there is no “beginning of the universe” to explain. Because we need no explanation, we need not to postulate a God to explain it.

In general, Carroll seeks to explain his project by looking back to a similar project in physics that began with Aristotle’s physics.

Aristotle argued that the natural state of things in the universe is at rest. If you wanted something to move, you needed to push it. As soon as you quit pushing things, they stopped. This lead to the question, “Where does all of this pushing come from that keeps the universe in motion?” St. Thomas Aquinas provided an answer to that question (to be fair, he presented the accepted view of what that answer was), that this ‘prime mover’ that kept the universe going (without which the universe itself would come to a dead stop) was God.

Then Newton came along and said that this was not the case. On Newton’s model, objects moved in a straight line at a constant velocity unless acted upon by another force. The reason that things slowed down on Earth when we quit pushing them was because of the operation of a number of forces (friction, drag). If we eliminated these forces, then nothing would slow down.

Using this assumption, Newton was able to come up with a set of formulae that easily explained the motion of most objects in the universe, including the planets and the moon.

The moral of this story was that the idea that we needed to postulate a God to keep the universe in motion was a mistake. It was caused by a faulty assumption – an assumption that motionless was the natural state of items in the universe. That assumption made sense given our every-day observations, but it turned out not to be true.

Carroll sees the same problem arising with respect to the origin of the universe.

The idea that the universe actually had a beginning (a ‘big bang’) is not one that drew out of everyday observations, like the idea that everything stopped unless something kept them moving. It followed from observations that the universe was expanding – the galaxies are all getting further and further away from each other. If we “rewound” the universe – tracing these galaxies back to their starting point, we find that their starting point was about 14 billion years ago.

What, then, caused the big bang? Since the big bang could not cause itself, it must have been caused by something outside of the universe, and that thing is (was) God.

Carroll wants to argue that the universe did not have a beginning.

It was once thought that the universe would have an end. All of this material flying out from this big bang would eventually slow down, then stop, then fall back in on itself in a ‘big crunch’. However, that idea has now been rejected. Observations show us that the universe is not only expanding, but that it is expanding at a faster and faster rate. This means that the universe is eternal. It can go on indefinitely into the future.

Then why not suggest that it can also go back indefinitely in the past?

Well, we have this ‘big bang’ to contend with.

However, the ‘big bang’ is not a puzzle to be solved, it is a gap. It is one of those areas that we simply do not yet understand.

It is common among theologians, to find gaps in our knowledge, and to stuff God into those gaps. As soon as somebody comes up with a question that we do not know the answer to, the theologian pipes up, “I know what the answer is! The answer is God!”

Only, time after time the scientists have eventually come up with another suggestion – a suggestion that leads to a set of predictions, and predictions that then are confirmed by observation. When the ‘gap’ was how to explain the motion of things in a universe where everything appeared to slow down and stop without a ‘prime mover’, the theologian chimed in, “And that prime mover is God.” Only, Newton came along and said, “No, actually, the only ‘gap’ that existed was a gap in our understanding the universe. We do not need a God to keep the universe in motion.”

This story that we told you that convinced you there was a big bang is not internally consistent. We have theorems within Einstein’s general theory of relativity within our understanding of classical gravity, that given the conditions of the universe now there must have been a singular point, a point in which the universe was infinitely dense and had infinite space-time curvature, and we can even tell you when it was. It was about 14 billion years ago. And we even have data that tell you what it looked like one second after the big bang.

However, these theoretical demonstrations using classical general relativity can’t be right, because this infinite point of singularity means that general relativity is not correct at that point in the universe’s history, and nobody thinks that it is correct. What actually has to happen is that some better theory has to come into play before you hit this singular state. Normally we think that this is some quantum theory of gravity that we haven’t yet developed. But the point is that all of our firm declarations that there wasn’t anything before the big bang are based on a theory that doesn’t apply at the big bang.

Carroll presents his own idea of what happened at the big bang. He suggests that there was an empty parent universe going about its business and that we are an offspring of that universe. Events in that universe created a child universe, and that child universe is us.

The point being that we do not need to assume that Carroll is right in this. It is sufficient, for the purposes of this conversation, to simply note that we do not need to explain how the universe came from nothing (not even time). The fact that we do not yet know what ‘better theory’ accounts for the first second of the our universe’s existence or what that theory says about what came before implies that there is not yet any reason to believe ‘god did it’. There might not even be an ‘it’ in this case for God to do.

Ultimately, Carroll argues that we need to generalize this idea. There are a number of problems out there that are actually (according to Carroll) more difficult than the origin of the universe. He lists the development of the whole biosphere, morality, and romantic love. These problems are hard, but we are coming up with solutions to hard problems all the time. There is not yet any reason to believe that these hard problems cannot be answered. There is not yet any reason to point to a hard problem and say, “The answer is God.”

Because we are faced with these problems that are hard, but, nevertheless, we see specific examples of hard problems that get solutions, I would say that we should look at problems such as, ‘Where does love come from?’ ‘Where does morality come from?’ ‘How does the biosphere evolve?’ and say, ‘These are hard questions. Let’s get to work.

Of course, I must add that I do not think that the question of the origin of morality is that hard a question to answer. It consists in relationships between malleable desires and other desires – that we have ‘reasons for action’ that are desires to use social forces to promote some desires (desires that tend to fulfill other desires), and to inhibit other desires (desires that tend to thwart the desires of others). And that we encourage the development of good desires and discourage the development of bad desires by (moral) praise, condemnation, reward, and punishment.

But that’s just me.