Before I embark on this blog post, a few words for regular readers. I have to apologise for the blog falling dormant for a month. This was because I have been working intensely on a book (a physics textbook), and also because I have been mulling over what to write. Also, I put up quite a lot of content just before the dormant period so I hope there was enough to be going on with (see under resources/talks). Finally, regarding comments: thanks for all constructive comments. They are all much appreciated and encouraging. However it is hard to keep up with moderating them because I have had over 7000 comments in total, almost all of them spam. I hope some day to get some help with the filtering process, but until I do that the situation will continue to be slow.
The post you are reading now was prompted in part by a recent talk at the physics department here in Oxford. The talk was the 2015 Wetton Lecture, delivered by Professor Carlo Frenk, Director, Institute for Computational Cosmology, University of Durham, and it had the title
“Everything from nothing, or how our universe was made”
It emerged early in the talk that, as most of the audience probably expected, Prof. Frenk was using the word “nothing” to refer to the lowest energy state of a highly sophisticated collection of quantum fields. In other words, he was using the word “nothing” to refer to something that is very, very different from what the word “nothing” means in its everyday sense. The talk was entertaining and informative, but nevertheless it left me uneasy because I think scientists have a duty to proceed more carefully when delivering science for a more general audience. If we allow ourselves to simply redefine words, we will end up first confusing other people, and finally confusing ourselves.
Referring to the quantum vacuum state as “nothing” is rather like referring to the Atlantic Ocean as “nothing”, and saying that only those drops of water that get splashed into the air count as “something”. You see, the quantum vacuum state—the lowest energy state of the quantum fields that the universe is built from—has a very large amount of mathematical structure. Roughly speaking, it is just as structured as the Atlantic Ocean. But if it is structured, then it is something. In the everyday sense of words—in the only sense that constitutes meaningful discourse—the quantum fields are something, whatever their state of energy.
To take another image, suppose an artist got together with an engineer in order to mount a public artwork in the town square, and the artwork consisted of a fifty-metre steel girder erected vertically and balanced on its end, with no other support. Now suppose a gust of wind blew it over and the girder came crashing down, crushing several cars and narrowly missing a passer-by. If the engineer now claimed that the falling of the girder was caused by a random fluctuation—the gust of wind—then he would be making a claim similar to the one made by people who say that the universe was caused by a random fluctuation. He would not get far in a court of law.
To summarise, then: the only reason that we can even begin to talk about scientific ideas such as cosmic inflation is that we have mathematical models which say that explosive growth into a hot Big Bang is the sort of behaviour that is characteristic of the stuff from which the universe is made. These mathematical models are models of something, not nothing. Secondly, if it is part of that behaviour that a wonderful universe such as the one we are in begins to evolve, starting with something like the release of an in-built tension, then the true cause of that wonderful universe is not the fluctuation, but whatever caused there to be something that could fluctuate. The true origin is whatever caused there to be the stuff (the quantum fields etc.) and whatever caused there to be law and pattern at all. This cause is not found in words like “fluctuation” or any other physical property or physical behaviour that is part of the universe. The origin is at another level, in another category. I am not about to claim to know the answers here, but let me say this at least:
It is reasonable to hold that that which stands as origin of the universe has something to do with sense and reason, and beauty too, because those are what we find in fundamental physics, and this is one of the most remarkable facts of all.
I will return to this theme in the next post.