I’m going to jump back on one of my favourite high horses. I’ve previously blogged about Lawrence Krauss and his views on the question “why is there something rather than nothing?”. I’ve just finished his book, and he appeared last night on an Australian TV show called Q&A. It was a good panel discussion, but as usual the show invites too many people and tries to discuss too much so there is always too little time. Krauss’ discussions with John Dickson were quite interesting.

I’ll be discussing the book in more detail in future, but listening to Krauss crystallised in my mind why I believe that science in principle cannot explain why anything exists.

Let me clear about one thing before I start. I say all of this as a professional scientist, as a cosmologist. I am in the same field as Krauss. This is not an antiscience rant. I am commenting on my own field.

Firstly, the question “why is there something rather than nothing?” is equivalent to the question “why does anything at all exist?”. However, Krauss et al have decided to creatively redefine nothing (with no mandate from science – more on that in a later post) so that the question becomes more like “why is there a universe rather than a quantum space time foam?”. So I’ll focus on the second formulation, since it is immune to such equivocations.

Here is my argument.

A: The state of physics at any time can be (roughly) summarised by three things.

1. A statement about what the fundamental constituents of physical reality are and what their properties are.

2. A set of mathematical equations describing how these entities change, move, interact and rearrange.

3. A compilation of experimental and observational data.

In short, the stuff, the laws and the data.

B: None of these, and no combination of these, can answer the question “why does anything at all exist?”.

C: Thus physics cannot answer the question “why does anything at all exist?”.

Let’s have a closer look at the premises. I’m echoing here the argument of David Albert in his review of Krauss’ book, which I thoroughly recommend. Albert says,

[W]hat the fundamental laws of nature are about, and all the fundamental laws of nature are about, and all there is for the fundamental laws of nature to be about, insofar as physics has ever been able to imagine, is how that elementary stuff is arranged.

For example, in Newtonian physics the fundamental constituents are particles, absolute space and absolute time, the laws are Newton’s laws of motion and equations that describe the forces at work in the universe e.g. gravity, and the data are things like the motion of the planets, rolling down an inclined plane etc. After James Clerk Maxwell, we add to the basic stuff electromagnetic fields, and add his equations to the laws, and to the data add observations of electromagnetic phenomena. The standard model of particle physics has quantum fields and Einsteinian space time as the basic stuff, the laws are standard model Lagrangian and general relativity, and throw in all the data of particle accelerators and such. (I’m glossing over a lot here, obviously, but you get the idea.) Various theories beyond the standard model postulate different stuff and laws e.g. String theory, loop quantum gravity. In some of these theories, there is an attempt or at least the hope that the theory will be able to treat spacetime itself as a derived thing, that there will be something in the theory even more fundamental than space and time, out of which space and time can be made (so-called background independent theories).

Now, why think that neither the stuff, the laws or the data or a combination can answer the question of why anything exists?

1 can’t do it: A statement of the basic constituents of reality, in and of itself, obviously cannot explain why such things exist, any more than the statement “the sky is blue” can explain why the sky is blue. So 1 is out.

2 can’t do it: Mathematical equations describe properties, and existence is not a property. 5 dollars plus 5 dollars equals 10 dollars, but that fact will not tell you how much money is actually in my account. The same is true for all mathematical equations, even the more sophisticated ones used by modern physics. Write down any equation you like – you will not be able to deduce from that equation that the thing it describes really exists. Mathematical equations are abstract entities, they have no causal powers. They can’t do anything, least of all jump off the blackboard and pull entities into existence. So the answer cannot be found in 2.

1 and 2 can’t do it: 1 and 2 together give a theoretical description of reality as we know it, so succumb to the same problems as 2 alone.

3 can’t do it: for the same reason that 1 can’t. The statement “I observed an electron strike a screen” cannot explain why there are electrons at all, and thus (a fortiori) cannot explain why anything exists at all.

1, 2 and 3 can’t do it: Sitting and staring at 1+2 on one hand, and 3 on the other, will tell you why we think that 1+2 really describes our universe. They account for the data, which is what science does. But once again we see no resources to attack the question of why anything at all exists. We’ve successfully described our universe. But that is all.

Thus, physics cannot answer the question “why does anything at all exist?”.

It is important to realise that no amount of progress in physics will change this situation. Imagine the final equation, the law of nature, written on a blackboard to thunderous applause. After the adoration dies down, we will still be faced with the question “why does a universe described by that equation actually exist?”. The answer cannot be found in the equation. Stephen Hawking said it well:

Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe? (from A Brief History of Time)

Krauss’ new “scientific” “nothing” consists of yet more hypothesised fundamental entities and laws which govern their behaviour. In Q&A, Krauss appeared to deny that there were such laws, but his book makes it clear that by “no laws” what he really means is laws that are “stochastic and random”, admitting that “Although to be fair, to make any scientific progress in calculating possibilities, we generally assume that certain properties, like quantum mechanics, permeate all possibilities.” The novelty of Krauss’ particular stuff is that it is (hypothesised to be) more fundamental even than space and time. But it is still stuff. And the mathematical laws that describe its properties and behaviour still cannot explain why it exists at all.

If you are a philosophical materialist – if you believe that everything that exists is ultimately the stuff of physics – then this question is unanswerable. Not just unanswered – I have no problem with questions that science cannot currently answer. It’s because of such questions that I have a job. But materialism simply doesn’t have the resources to answer that question. To be a materialist, one must convince oneself that the question is somehow meaningless, that it is nonsense masquerading as one of the deepest and oldest philosophical questions mankind has ever asked.

Is theism’s answer any better? The attempt is as follows: if everything that exists does so contingently, that is, if it is possible that it could not exist, then the question of why anything at all exists is unanswerable. Given anything that exists, we would still be left with the question as to why it exists. To answer this question, we must postulate the existence of a necessary being, that is, one who can’t fail to exist, the reason for whom’s existence is found within itself, rather than externally. This is not creating an arbitrary exception for God. It is asking what kind of thing must exist in order to explain the existence of contingent things. It is the search for a sufficient explanation for existence that leads us to a metaphysically necessary being.

A plague of questions spring to mind. Does that even make sense? What kind of thing is a metaphysically necessary being? Why think that the necessary being is a person? Why couldn’t it be the universe? We get rather quickly into deep philosophical waters here. But that is my point. Physics simply cannot inform these questions, one way or the other. It cannot speak to ultimate existence, it cannot observe or model necessity. If the necessary being turns out to be the universe (a view that almost no modern philosophers defend), then this will not be a scientific conclusion – no observation could establish that fact. I agree with Martin Rees, who said

[P]hysics can never explain what ‘breathes fire’ into the equations, and actualised them into a real cosmos. The fundamental question of ‘Why is there something rather than nothing?’ remains the province of philosophers. And even they may be wiser to respond, with Ludwig Wittgenstein, what ‘whereof one cannot speak, one must be silent’.