It is quite natural to look at the night sky, especially away from city lights, and be in awe. When we learn that the U
It is also natural to ask where it all came from. Has the universe always existed? What caused it?
There are several well known arguments that try to answer these questions. One of the simplest is the Kalam Cosmological Argument, named after an Arabic phrase meaning (roughly) “science of discourse”, reflecting the work done by Islamic scholars on this argument. The Kalam has only two premises leading to its conclusion:
1. Whatever begins to exist has a cause.
2. The universe began to exist.
3. Therefore the universe has a cause.
But did the universe have a beginning?
There are several intuitive arguments that suggest that the universe had a beginning:
- Mathematical: It is impossible to count to infinity. Therefore it is impossible to count backwards to negative infinity. Therefore it is impossible for an infinitely old universe to ever reach the present time.
- Scientific: One of the fundamental laws of physics is the Second Law of Thermodynamics, which states that entropy (a measure of the part of the internal energy of a system that is not available to do work and make things happen) can never decrease. This means that the universe is “running down”, moving from a state of highly uneven temperature and distribution of matter, to a state of being homogeneous. If the universe was infinitely old, the universe would have already reached this stat. The fact that it hasn’t shows that it cannot be infinitely old.
But it turns out it may not be that simple.
When all else fails, listen to the experts
There is a tendency for all of us to trust our own logic and judgment, even when we don’t really know all we need to know. In fact, the Dunning-Kruger Effect says that when we have low ability, we are more prone to think we know more than we do.
I have found the Dunning-Kruger Effect is especially prevalent on the internet, so I want to try to avoid it myself. The only remedy is to check out what the experts say, and try to get an understanding of the range of expert opinion, and the consensus.
Models of the universe
When we use the word “model”, we tend to picture a small scale copy of something real. But models of the universe are mathematical and conceptual. In trying to explain the processes going on in the universe that led to the situation we now see, physicists have proposed many different models and theorems. There is the Standard Model of the big bang, and many other models such as the Friedman-Lemaitre-Robertson-Walker model, the Ekpyrotic model, there are theories of gravity (notably General Relativity), the Penrose singularity theorem, the Borde-Guth-Vilenkin (BGV) theorem – and much more!
These models and theorems are tested for consistency with known data and known laws, and gradually, it is hoped, the truest ones become clearer. But the point is that even experts in some areas of cosmology are not fully familiar with some of these ideas, so it is folly for a total layperson like me, or many others on the internet, to think we can venture into these matters with any confidence.
So in what follows, I am being guided by the experts – hopefully my reading has been fair and balanced!
The Borde-Guth-Vilenkin theorem
This theorem, used by philosopher William Lane Craig to support the Kalam argument, starts with reasonable assumptions and proves mathematically that the universe had a beginning. However other cosmologists counter that using different models for understanding the physics of the universe allows an infinitely old universe.
Alexander Vilenkin, Director of the Institute of Cosmology at Tufts University, continues to argue that the evidence points to a beginning. In a recent paper, The Beginning of the Universe, he argues in support of the BGV theorem and concludes:
The answer to the question, “Did the universe have a beginning?” is, “It probably did.” We have no viable models of an eternal universe.
However Sean Carroll and Aron Wall argue that the BGV theorem isn’t strong evidence for a beginning.
Two experts review the evidence
Luke Barnes reviews 16 different models, theorems and ideas, showing there is plenty of evidence both ways. But in the end, he concludes:
It’s a bit of a mess. There are enough surprising hints for the beginning of the universe to be taken very seriously, but enough unknowns to keep us busy. If offered even money, I’d bet on the proposition that there has only been a finite amount of classical time in the history of the universe.
Aron Wall is equally circumspect. He concludes: “So, even if we can say there appears to have been a beginning based on an extrapolation of the Big Bang Model to early times, there are also reasons why we can’t be completely sure”.
In another post he reviewed the relevant physics, and said there are 7 different aspects of physics that are relevant to this question, and 5 of these point to the universe having a beginning, 1 suggests it did not, and one could be interpreted either way. So here he concludes: “We don’t know for sure whether the Universe began, but to the extent that our present-day knowledge is an indicator, it probably did.”
But he also says: “In our current state of knowledge, any statements about the beginning of the universe are necessarily speculative, and if we rest our theological beliefs (for or against Theism) on that shaky foundation, we are setting ourselves up for trouble.”
So the probability is ….
It seems, according to science, it is still more likely that the universe had a beginning than that it didn’t. This means the Kalam cannot be considered a “proof”, but could be considered an indication or even a probability.
But could the universe have appeared out of nothing?
So what about the first premise? Does everything that begins to exist have a cause?
Again, superficially, premise 1 seems reasonable. It accords to logic and it is confirmed by our experience. Things don’t just happen without any reason or cause. As the Greek philosopher Parmenides said about 2,500 years ago: “Nothing comes from nothing.”
But again, it is more complicated than that. For a start, quantum physics suggests that some events do happen without a direct cause, although there are still necessary pre-conditions (the existence of a quantum field).
So perhaps the first question should be, could the universe come from nothing? Cosmologists have addressed this question also.
Lawrence Krauss and a universe from nothing
Physicist Lawrence Krauss has written and spoken widely in support of the idea that the universe could appear from nothing. In fact, he argues, it seems inevitable that it would. Krauss bases his idea on the fact that in a quantum field, particles can appear apparently out of nothing. So, he apparently says (I can’t claim to understand this too well), the universe could appear out of no space and no particles because that “nothing” is unstable.
Krauss received some support for his ideas, but has been widely criticised for sloppy and misleading thinking. There have been two main criticisms:
A quantum vacuum is far from nothing
- Long before Krauss’s book, Martin Rees cautioned: “Cosmologists sometimes claim that the universe can arise ‘from nothing’. But they should watch their language, especially when addressing philosophers. We’ve realised ever since Einstein that empty space can have a structure such that it can be warped and distorted. Even if shrunk down to a ‘point’, it is latent with particles and forces – still a far richer construct than the philosopher’s ‘nothing’.”
- New York Times review, physicist and philosopher David Albert pointed out that a quantum field, even if devoid of particles, is very much more than nothing.
- Aron Wall analyses three different aways that Krauss uses the word “nothing”, and argues that none of them are actually nothing. In quantum field theory, a vacuum state has virtual particles (and if it didn’t it would have infinite energy) and space & time geometry. The other two uses of the word are quite speculative and don’t mean “nothing” either.
- Luke Barnes is even more critical, saying that if Krauss’s “nothing” has properties, such as being unstable, then it can’t be nothing = not anything – it has to be something to have properties. He says: “The quantum vacuum is a type of something. It has properties. It has energy, it fluctuates, it can cause the expansion of the universe to accelerate, it obeys the (highly non-trivial) equations of quantum field theory. We can describe it. We can calculate, predict and falsify its properties. The quantum vacuum is not nothing.”
The laws of physics are not “nothing”
Even if we could regard the quantum vacuum that supposedly began the universe as “nothing”, Krauss’s proposal still requires the laws of physics to exist and to control the spontaneous appearance of the universe out of nothing, and Krauss’s ideas don’t explain where these laws came from, and why they can be considered “nothing”. Almost all commentators criticise Krauss’s ideas on these grounds:
- Cosmologist George Ellis says this.
- So does Michael Brooks reviewing the book in New Scientist.
- Even cosmologist Sean Carroll, who is quite sympathetic to Krauss overall, makes the same point. Because he believes there is nothing outside the physical universe and science is the best (only?) way to understand the universe, he argues that some questions are outside the realm of science and can be considered meaningless questions.
- David Albert, Aron Wall and Luke Barnes also say this – science can only explain how something becomes something else, it cannot explain how the whole thing, matter, energy, quantum vacuums and laws came to exist out of nothing.
Alexander Vilenkin again
Alex Vilenkin, in the article I quoted earlier, also addresses the question of a universe from nothing. He discusses a quantum creation, a “speculative hypothesis” that may not be able to be tested observationally, but which might allow a universe to arise from nothing: “there is nothing to prevent such a universe from being spontaneously created out of nothing”.
But this view still has its critics. Luke Barnes comments briefly: “‘nothing’ does not equal ‘physical system with zero energy’.”
But Vilenkin sides with those who point out that even if the universe could be spontaneously created out of nothing, we still have to explain where the laws came from to make that occur, and concludes: “We have no way to begin to address this mystery.”
The multiverse – the elephant in the room?
Very little of the discussion I have seen on the beginning of the universe and its appearance out of nothing, has discussed how the multiverse hypothesis changes things. If there is a multiverse, then before the big bang there was certainly something. But of course we can then ask how did the multiverse arise out of nothing, and we are left with the same philosophical question, but with virtually no established science to guide us.
So where have we ended up?
It seems that the first premise of the Kalam (Whatever begins to exist has a cause) is made a little more doubtful by modern cosmology, though the Kalam can probably be rescued if we expand the premise to something like; “Whatever begins to exist has a cause external to itself or arises out of something external to itself”, or perhaps “Nothing can come into existence out of nothing.”
The second premise (The universe began to exist) is also made a little more doubtful. According to modern cosmology, it is probably true, but not certainly true.
The Kalam only needs one of the premises to be unsupported to fail. Neither has been shown to be false by the latest science, but both are merely probable rather than certain. This seems to make the conclusion definitely more likely than not to be true (especially if premise 1 is amended), but far from certain.
Doubtless we’ll all differ on how probable we think it is overall.
Aron Wall seems to think that cosmological and fine-tuning arguments offer some support to the existence of God, but believes these arguments are not strong because they depend on the science, which is always changing, often speculative and may end up with surprising conclusions. He thinks there are other better reasons to believe in God.