I’ve been asked numerous times about a scientific paper published earlier this year purporting to show the universe has always existed:
The universe may have existed forever, according to a new model that applies quantum correction terms to complement Einstein’s theory of general relativity.
Apparently, some atheists are latching onto this to show that Genesis 1:1 is wrong, and some of you are unsure how to respond to such an argument.
The first thing I would like to point out is that atheists have been trying to get around the finite age of the universe since the 1960s, when the most compelling evidence for the big bang — the cosmic microwave background — was discovered. As many atheist scientists observed at the time, big bang cosmology is uncomfortably close to Genesis 1.
If you’re a Young Earth creationist who believes the big bang theory is an atheist conspiracy, this should be a compelling reason for you to reconsider that belief. Most atheist scientists are desperate to do away with the conventional big bang theory. They were quite happy prior to the 1960s when it seemed the universe was infinitely old — an infinitely old universe requires no explanation, and therefore requires no God. But we’re stuck with a universe with a beginning, and that’s a problem for atheists. This is why we hear so much about overblown stories about the big bang not happening or all these stories about the multiverse.
Anyway, here’s what you should keep in mind about this paper.
1. It’s just a model, not evidence.
The physicists who wrote the paper are proposing an explanation for the big bang by using a mathematical model. Models that speculate about how things might work are important in science, but you should always remember that a plausible model is not evidence. Think about it this way. I could come up with some very interesting and plausible explanations for who assassinated JFK and how they did it. While these explanations would suggest possible lines of investigation, they would not constitute evidence in a court of law.
2. The study’s conclusion follows from its assumptions.
This requires a bit of background to explain. The big bang was a sudden expansion of the universe from a hot, dense state. We can see by looking at the motions of galaxies all rushing away from each other that the universe is still expanding, and it’s cooling as it does this. If you think about running the movie of the universe in reverse, all these galaxies would appear to be rushing towards each other as we go back in time. Everything would be getting more smushed, and the universe would be getting denser and hotter, until we reached some initial very dense, very hot state; possibly even infinitely dense and hot, but nobody knows for sure what that initial state was.
In Einstein’s general relativity, the shortest distance between two points in spacetime is called a geodesic. As you go further and further back in the history of the universe, as things get smushed together and hot, all geodesics eventually converge and you get a singularity. The problem is, general relativity is unreliable on extremely small — that is to say, quantum — scales. For that reason, you can’t legitimately extrapolate all the way back to a singularity using general relativity, and that’s why physicists are working on a quantum version of gravity. To get around this problem, the physicists in this study used a quantum replacement for geodesics, called Bohmian trajectories. By their very nature, these quantum trajectories cannot converge to a singularity. So, big surprise, when you assume that you can’t get a singularity in your model, you don’t get a singularity in your model. This is why the headline of the phys.org article is so annoying: “No Big Bang? Quantum equation predicts universe has no beginning.” No, it does not predict the universe has no beginning; the assumptions in the equation require it! And, it’s wrong about this “prediction” anyway (see below).
3. Do we really care about a singularity?
So, what is a singularity, anyway? If you ask a random person, he’ll probably say it’s an infinitely small point. For physicists, it’s more complicated. It can be a hypothetical infinitely small point, but it can also represent a state of infinite density, even if space isn’t infinitely small. But this is problematic, as people like to say. It’s fine to talk about infinities in terms of mathematics, but physicists don’t like infinities in reality, because they play havoc with reason. That’s why we tend to think they don’t actually exist.
Anyway, the notion that the universe might not have begun with a singularity (of whatever kind) is not new. Physicists know general relativity becomes unreliable at the very earliest moments of the universe, because it just isn’t equipped to describe what’s going on at those scales. A common way of expressing this is to say physics breaks down at the smallest scales. So, if you ever hear a physicist talking about the big bang singularity, what he really means is the place at which physics doesn’t explain what’s going on. The best we’ve been able to say for a while now is that we don’t know exactly how the universe began. This is nothing new.
4. They’re playing fast and loose with the notions of potential and beginnings.
According to the model, the universe does not start off as a singularity, but existed eternally as a quantum potential. In an article at livescience.com, one of the authors of the paper is quoted as saying this could mean the universe is infinitely old, i.e. the universe had no beginning. Popular media writers are inferring this also means there was no big bang. However, both are wrong.
Let’s get this out of the way first: the scientific paper does not claim there was no big bang. ‘No singularity’ is not the same thing as ‘no big bang.’ It just means the big bang occurred from some state other than a singularity.
As for the universe not having a beginning, let’s use an analogy to explore potentials and beginnings, and we’ll see why this is wrong. We’ll start with an obvious statement: every person begins to exist. People argue about when the beginning of human life actually occurs, but there is little doubt that the very earliest we could possibly date it is the moment when a sperm fertilizes an egg. Let’s take you, for example. You exist. We could legitimately say that you began to exist as far back as when you were conceived in your mother’s womb. We could also legitimately say that the potential for your existence predated your conception. That potential existed in your mother and father, and, before them, in their mothers and fathers, and so on, all the way back to the earliest moments of the universe. But does that mean you’ve existed for 13.8 billion years? No reasonable person would make such a claim, for the simple reason that we intuitively understand that the potential to exist is not the same thing as existing. That’s why it’s silly and misleading to claim that a hypothetical eternal quantum potential for the universe implies the universe has always existed.
Here’s what you should take away from all of this. The big bang is still the moment in cosmic history when something significant happened — space began to rapidly expand from a mysterious and extreme initial state. It doesn’t matter that we can’t exactly specify what that state was; it still marks the beginning of the universe as we know it, and Genesis 1:1 is still true.