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Being the Least Wrong

You would never design a television transmitter using quantum electrodynamics.

Robin Ince – How do you deal with this?  A journalist wrote to me the other week and he said, he actually said, ‘If science is so good why do they keep having to change it?’

Brian Cox – (Laughs)

RI  Yeah, I know, and I thought this is one of the hardest things –

BC – They…?

RI – The idea of being the least wrong.  The idea that science is not 100%, you know, of all the things we’ve recorded for this etcetera, many of them in fifty years time will have changed, will have moved on, they will have been stepping stones towards a less wrong understanding of the Universe.

BC – I don’t understand why the, it’s very, very very, this very simple idea that nature exists, obviously, outside of our experience, outside of our existence, it is there.  There’s a very big universe out there, possibly infinite, we’ve measured its age, we know its large, we are in many ways, in many ways an insignificant speck in it.  I don’t say in every way because we don’t know how many intelligent civilisations there are out there, but anyway, there we are, nature exists outside of us.  How is it a difficult concept that the aim of science is to understand how that external reality works and therefore, if you have an idea, which may be, Newton’s law of gravitation, and the idea is there’s a force between massive objects which is proportional to the product of their masses and the square of the distance between them, inversely proportional to that, so you move them, double the distance between them the force drops by a factor four, right?  There’s an idea, it’s a description of nature.  It works very well.  It allows us to send spacecraft to the outer Solar System, but it turns out that if look at the planet Mercury, its orbit deviates slightly from what you would expect and the reason for that is that the theory’s not quite right.  There’s a better theory, a better description, which is Einstein’s theory of general relativity and that describes it better.  Most likely, almost certainly, certainly I would say, there is a better theory.  For example, we don’t understand what happens inside black_holes.  Einstein’s theory produces infinities when you ask it to describe what happens inside a black hole.  That is a signal that the theory doesn’t apply there, we need a more accurate theory, don’t know what it is yet.  I don’t understand why that’s a difficult idea to get into your head, one’s head.  The fact that we are trying to describe nature.  If a better description comes along, you jettison, or replace, the previous description with the new description.  You probably hang on to the previous description as well as it might be the simplest way to describe things in a particular domain.  So if you want to send a spacecraft to Jupiter, better to use Newton’s laws.  Ridiculous to use Einstein’s theory of general relativity because it won’t make any difference to getting your spacecraft to Jupiter, but if you want to describe the orbit of Mercury, we’ll use the more accurate theory.  And there will be another more accurate theory.  I don’t understand why that is a complex and difficult idea to get your head around.  I don’t understand!  The reason we keep replacing theories of nature with new ones is because we find a more accurate description of nature.  It doesn’t mean the person who wrote down the previous theory was somehow deficient.  It doesn’t mean they were somehow wrong, it doesn’t mean they were somehow a lesser person.

RI – Well people do do that don’t they?  They go, ‘Newton was wrong,’ and you go, ‘No, no, Newton was right up to a point, surely?

BC – Newton was right.

RI  He was still, his calculations and his system was used to get to the moon.  So you have to go, well, that’s what got me when someone come up to me, because of cultural relativism, ‘How much do we know now?  We’ll all be proved wrong.’  And I went, ‘Yeah, but there are certain things we know are right.  There is no way people will look back in a hundred years time and go, ‘No-one actually realised at the beginning of the 21st century that they’d all died at the age of two from cholera.’  They hadn’t realised because in fact the water was still dirty, they kept on living their life because, you go, ‘No!  We definitely know things like the system we have now, that can purify water, means that when we look out at London, there are not the same number of cholera deaths.  That’s not going to change, that’s still, I mean, we might find new ways and we might understand new ways of purifying water or whatever it might be –

BC – It’s a good example.  I’ll give you another example.  Radio and television right?  That proceeds by, the way we understand it and the way it’s all written down and the designs are done is in terms of electromagnetic waves which are, so the way that radio waves are generated and transmitted and received, they use something called Maxwell’s equations, written down in the 1860s by James Clerk Maxwell.  There is a better theory now, called Quantum electrodynamics written down by Richard Feynman and others, actually in the beginning of the 1920s I suppose, certainly in the 1940s, 1950s, it’s a more accurate description of electromagnetic radiation but you would NEVER design a television transmitter using quantum electrodynamics.  You couldn’t.  It would be ridiculous overkill and you couldn’t do the sums, so you use Maxwell’s equations, which allow you to do something real which is to build a television, which is exactly what you said –

RI – Are you sure?  Will people in a hundred year’s time go, ‘There was a mass delusion.  People believe they were watching Brian Cox’s Wonders of the Solar System but in fact all the screens were blank.’

BC – Yeah, but that’s the kind of, almost the implication of that kind of complete misunderstanding of science.  You say, ‘Well it’s been replaced so therefore it’s wrong.’  Example after example, um, aerodynamics.  Every time you sit on a plane you’re sitting on something that’s been designed, the shape of the wings etcetera, have been designed using fluid mechanics and all these wonderful equations that describe how the fluid of air moves across the surfaces.  Now, actually the most precise description we have of the way the molecules interact with each other, and atoms interact, is Quantum theory.  But you wouldn’t try and use Quantum theory to design a plane because it’s not necessary.  it’s outside its domain, well it’s not outside its domain of applicability but it’s outside of the domain of reasonable computational time.  You don’t need to use Quantum theory to do aerodynamics.  You can use a more approximate, effective_theory it’s called, so effective theories are fine –

RI – So Thomsons Holidays could use a many-worlds interpretation to make the journey quicker to Australia or Barcelona?

BC – No.  You do not –

RI – You wouldn’t be able to use the Many-Worlds, oh –

BC – You will never need Quantum Theory to design an aircraft.  Because fluid mechanics is sufficient, right, fluid mechanics, which is an effective theory which works beautifully at those kinds of distant scales, those desensitise, etcetera, etcetera, so it’s a misunderstanding.

RI – See, I think it’s a really lovely thing.  I think it’s beautiful that the idea of 100% knowledge is, but that may not be a possibility but going, this is this wrong, this is this wrong and this is this wrong, so we’re gonna go with this because this one definitely has the least worst outcomes.  I think that, rather than going, see, a lot of people want an utter certainly and I think it’s far more beautiful to go, ‘Look, we’re managing to survive for longer and this is happening but who knows what next.’

BC – Certainty is a human construct isn’t it?  It’s about how you feel about something.  ‘I am certain,’ about something.  The point is, if we’re talking about wing design, it’s about how much lift you get given this particular shape of wing, this particular velocity etcetera etcetera.  That’s a thing you can calculate.  You can design the wing, you can then build the plane, you can get on the plane and it flies.  So I don’t understand the idea of degrees of certainty about those things in a sense, it kind of, or the idea that you want to be certain about nature is, that’s a human impulse.  What we’re doing is describing nature as best we can.  Certainty doesn’t really come into it in my view.  If your wing design works and the force, the lift, is as you thought it would be, then you understand nature well enough to build a wing.

RI – That’s how I work it.  The least likely scenario of me crashing into a mountain and being forced to cannibalise other people.  It’s not certain that that’s not going to happen, but I have been looking for an alibi for my cannibalism.