It’s just a theory

Last week I was a watching a repeat of an edition of Horizon which was looking at the idea of what was around before the Big Bang. For UK readers, it may still be available on iPlayer and would highly recommend watching it. It features a few of my favourite scientists: the physicists Neil Turok and Lee Smolin and the mathematician Roger Penrose. Those who know me well may recall that for my master’s degree I studied Roger’s twistor theory under the supervision of one of Roger’s former students.

The programme featured a variety of views from these and other scientists about a controversial notion. I’m familiar with Roger’s view, conformal cyclic cosmology, from reading his work, Cycles of Time. The other views I had heard before (not least from when the programme was first aired) but was less acquainted with.

One post I saw on Facebook read as follows: “So watching Horizon about the Big Bang, and loving the fact that scientists clearly have not got a clue about the universe started. Mmm…

One of the comments below stated: “Most of science is all theory and guess work!

These two combined rather got my hackles up. I chose not to enter into a debate then and there but rather think about it for a few days and write something up the following weekend (which, at 9:31pm on a Saturday night, I am now doing).

The first comment

The phrase that I object to here “have not got a clue”. Cosmology may be a relatively young science with much of the universe still to explore, but the notion that there isn’t a clue simply flies in the face of the evidence.

After the discovery of galaxies and the measures of their redshifts allowed for us to realise that we live in an expanding universe. This has been backed up by numerous astronomical observations and, to the best of knowledge, no observations have been made that falsify the idea of the expanding universe.

The idea of the Big Bang (a term originally used as a derisory attempt to discredit it by the steady state advocate, Fred Hoyle) was then developed by ‘turning back the clock’ and asking: if the universe is expanding, then in the past it was smaller, but how far back does that go.

The serendipitous discovery of the cosmic microwave background radiation by Penzias and Wilson was the nail in the coffin for Hoyle’s steady state hypothesis. It also tied in neatly with the developing theory of the Big Bang.

To date, it is the best theory of how the universe came into being. It accords with the best available evidence and has been studied in great detail in papers published in peer-reviewed journals – the gold standard of scientific epistemology. (Though it should be added that it’s not foolproof, as recently attested)

That doesn’t mean our knowledge and understanding is perfect and complete. If it were, there would be no need for further analysis. A lack of understanding is not a cause for abandonment or of making presumptions, it is a cause for further study. The Big Bang theory has its limits and the Horizon programme probed at some of these limits, asking important questions. If it turns out that another theory will be needed in order to give more details into the universe’s origins then it must take into account the evidence to date.

To take an historical example, Einstein’s general relativity recast Newton’s earlier work. The formalisms look quite different, but if one starts from Einstein and make some simplifications, one can rederive Newton. But Einstein had to start with Newton. Newton’s work was necessary to begin with. It seems unlikely that the more ‘obvious’ formalism would be overlooked and that someone could have come up with the more sophisticated theory. Yet Einstein didn’t overthrow Newton. The former built upon and refined the latter.

The case may be the same with the Big Bang. If a new theory is needed it will need to incorporate the evidence gathered to date. It would likely have an element which, if simplified, would result in something that looks like the formalism of the Big Bang. It’s doubtful many  people would understand it at first. But the lack of understanding is not a good reason for rejection. It should be quite exciting.

This is why I reject the idea that “scientists clearly have not got a clue about the universe started”. We have many clues. We have a coherent and consistent model of how it came about. It’s not complete, with some aspects as yet not understood. The work of the cosmologist is to try to bridge that gap in understanding.

The second comment 

So then, with that in mind, what about the second point?

“Most of science is all theory and guess work!”

First, we have the appalling grammar to deal with. Is it all or is it most? It can be difficult to judge tone in a written text (goodness knows what you make of my tone on this blog sometimes!), especially in one so short, but I read this is a statement not made by someone well-versed in science but rather as a condemnatory statement.

One of the key words here is “theory”. It is an example of where words which have fairly precise, technical meanings are also used in colloquial English. For another example in a different context, see my take here on the use of ‘complex’.

The Oxford English Dictionary defines theory as “1. an idea or set of ideas that is intended to explain something. 2. a set of principles on which an activity is based.” A footnote adds that it is derived from the Greek theoria which is translated as ‘speculation’.

This is the more common use of the term, and represents an unscientific viewpoint. That is not to say it is an inferior viewpoint in any way. It’s just a use of the term that is not context-specific. Contrast it with this, from Encyclopaedia Britannica: “a systematic ideational structure of broad scope, conceived by the imagination of man, that encompasses a family of empirical (experiential) laws regarding regularities existing in objects and events, both observed and posited – a structure suggested by these laws and devised to explain them in a scientifically rational manner.”

I would paraphrase this as: a framework of understanding, based on observation, by which reality is modelled.

However you prefer it, the scientific theory is a lot more than speculation. For that we would generally use the term hypothesis or conjecture.

But this brings us back to the comment. We test what we want to find out, in other words, what we do not know. Science tends to come in two parts: theoretical and experimental. I’m much more of a theorist. The work of the theorist is to develop the models, usually mathematical, and develop them into a coherent system which first of all agrees with all known observed data and secondly makes new, testable predictions. Depending on what area of science one works in, one will have different standards of evidence. Mathematics is the most precise of the sciences, where the only evidence accepted is that of proof. It’s a watertight logic. In physics, such proof is hard to come by. But physics is extremely rigorous, with 5-sigma being the level of certainty required before announcing a discovery . The use of this was well documented at the Large Hadron Collider in two recent instances: 1) the discovery of the Higgs boson and 2) the possibility (later explained) that a particle had travelled faster than the speed of light.

The latter point makes for an interesting case study in the scientific method. The apparent result would, if true, have contradicted a century’s worth of physics. That was not a reason to either throw Einstein out of the window or to reject the experiment as a hoax. It demanded to be taken seriously. It was the fact that Einstein’s relativity has been tested numerous times and that the framework which is established by that theory is one that we use everyday (e.g. for satellite navigation) that made a possible falsification a prospect that was at once thrilling and threatening. Had it been wrong, how would the body of evidence that supports it be accounted for?

I could go on even more. But I hope I’ve made my point.

Yes, science is theory, but that’s how it works. In the development of our theories there are hypotheses made. These are not random guesses flung out, but are the result of disciplined work. Once those hypotheses are tested they might be rejected or incorporated into the current theory. We have a lot of clues as to how the universe began and what goes on within it. We don’t know everything, and that is why research continues.