I should say also that use of probability is a grey area even among scientists. I remember some decades back Stephen Hawking saying on the Radio that in his view there was a 90% probability that Black Holes exist. I think I know what he meant but, how actually do you define the probability of a 1-off event. Its not like he meant that 9 out of 10 Universes have black holes. Statisticians are generally OK to think of probability as a way of representing lack of knowledge in a given situation or of summarizing repeated experiments, but not as an absolute quantity. Many people, on the other hand, WANT to think of probability as an absolute (this is compounded by its apparently absolute role in quantum theory) which is much more dangerous (I tend to take a Bayesian view that all probability is conditional).

These matters come back fundamental physics in the context of the `anthropic principle’ which some scientists (including some string theorists) advocate. Basically, an `explanation’ for why some of the parameters in our physical theories have the values that they do is put forward as: “The fundamental laws of Nature allow all possible values; we happen to be in a Universe where just the right values were assigned by Nature by chance. It seems unlikely to us but if they weren’t right we wouldn’t be here to see it.” In recent years this has been elaborated a but more as a `multiverse’; that all different values are actually assigned by Nature in different Universes and we are in the right one because life did not develop in most of the others where the values were wrong. Opinion differs among my colleagues but to me this is all a non-explanation. Science should try to understand why things are the way they are.

Many thanks — I’m ready to argue those two points, which are very good ones. On the first point: I am saying that assuming the conventional picture well inside the box where we know what we are doing and extrapolating down exposes that we do not know what is happening in the lower region –even within the assumptions that we started off with. So I am pointing to an inconsistency of conventional science within itself and not speaking (in this post!) about what replaces it. Surely then, the argument is within the conventional set of assumptions for quantum theory and GR as a conservative line of argument. I do agree that this points to a `hole in science’, but not how to fill it. Put another way, distances below the Planck scale have no current place within science as it is known so far as there is no evidence for them within what we know so far. That there is some future theory that could be found in which such distances do exist is an article of faith which is possible, but for which scientific evidence does not yet exist.

In truth my actual position on this is that the continuum, like the `real numbers’ that we learn about in high school are useful abstractions because they gloss over a certain level of detail, but thats all. Has anyone actually seen a real number that is not a fraction or a mathematical abstraction? How about Pi? Well, has anyone ever seen an exactly flat circle on a completely flat plane? Before answering that, bear in mind that the Earth as well as spacetime are a little curved. But thats a different story from commenting within the normal assumptions in Science.

On the second point, I chose my words carefully in speaking in the post about `no continuum in the formulation of the theory’. Maybe times have changed but when I learned string theory for the first time it was in an era when every talk in a theoretical physics seminar HAD to begin with a lagrangian which specifies the model, in a continuum, and this included string theory. Now, using this continuum classical theory and `quantizing it’, for example by a weighted average over all possible classical fields (Feynman path integral), you get to some kind of quantum theory from where, within the algebra of that theory, you can recover the classical continuum in, as you say, the regimes where you expect it. Well and good, so you can `extract’ other limits out of it which might better approximate a `foam-like’ structure at the Planck scale or a discrete structure etc, in the effective theory in certain regimes. It is a step in the right direction. But the theory itself is still founded on a continuum in its formulation. I really do not want to single out string theory here, this comment applies to the standard accepted notion of quantisation itself: the mainstream route in theoretical physics is to build the quantum theory on the classical one which is a bit like pulling yourself up by your own bootstraps. The Feynman path integral is a process that is cooked up so that the classical theory you put in has to emerge from the quantum because the quantum one is built around the classical. It works pretty well in practice but is it right? I’m not saying it could not give insight into the true nature of space and time but its illogical to think that it as fundamental as it kind of starts with the answer it wants to get in some limit. Its a bit like putting the cart before the horse.

So IF string theorists want to start with the Nambu-Goto lagrangian etc then they are open to my criticism. Alternatively, they can start with something more algebraic. Perhaps an operator formalism? But the specification of the various operators usually ends up invoking a classical picture. I actually agree with this line of thinking but take it further. The development of an intrinsically algebraic formulation of the theory with only indirect `by analogy’ reference to continuum geometry is called `noncommutative geometry’. I’ll talk about it in a future post but noncommutative geometers indeed let go of the continuum in this way. Now, string theory as I see it is a beast that can absorb any new idea on its cutting edge. So yes, I can name string theorists also working with noncommutative geometry and other non-continuum ideas. But one has to wonder how much of the baggage of string theory is then necessary from this new starting point (I don’t know the answer). My criticism at any rate is addressed to mainstream theoretical physics as it is usually presented.

Maybe a historical anecdote is in order here. When I was finishing my thesis in 1988, Ed Witten (The Ed Witten) gave a wonderful talk at Harvard on something like the `state of string theory today’. He even mentioned noncommutative geometry in his talk (but not as a starting point, rather as an algebra for sewing strings). In the reception at MIT that followed he asked me what I was doing. When I said that my thesis used algebra with different limits and did not begin with a continuum Lagrangian, Ed gave me a nice mini-lecture about how my approach must be wrong because you need a Lagrangian to conserve energy between a baseball bat and an atom. I remember it to this day though possibly in a garbled form (I was a bit too awe-struck to take it all in being a mere graduate student at the time). Some 10 years later I was visiting Harvard when Witten gave a similar lecture on the state of string theory. He began by saying that in his view there was no Lagrangian, that there was some unknown perhaps algebraic M-theory with different limits related by S-duality etc. So in so far as modern physics evolves one is speaking about a moving target. I rather think that the pendulum is gradually swinging to a more combinatorial or noncommutative or an even weirder direction for the deeper structure of space and time, but that the right starting point is still a (fascinating) mystery. Meanwhile, I hope its clear that I have nothing against string theory per se, this applies to much of conventional theoretical physics.

Greetings Jonathan,

This is an essay I blog posted 9/14/08 with a new, controversial and quite unusual viewpoint I hope will be widely discussed concerning the claims of the intelligent design movement.

It makes the case, primarily to religious moderates and others seeking a cooperative solution, that while faith and science are fully compatible, intelligent design is not only a bit crafty but, of all things, unscriptural. I do not believe this charge has ever been made before.

***

Practitioners of “intelligent design,” much like Molière’s Physician in Spite of Himself, not only belie the true nature of their avocation and motives but also play fast and loose with a commonly held precept. They tacitly negate the clear and completely traditional parameters that illuminate the position of chance occurrence in our universe.

How often do we see people settle an otherwise contentious decision by tossing a coin or by drawing straws near the climax of one of those tense action movies? It seems fair to all because it’s random and impartial; and most people seem to acknowledge this without any hesitation. Here’s the larger issue. What proponents of so-called intelligent design have cynically omitted in their polemic is that according to Biblical tradition, chance has always been considered God’s choice as well.

Read full article:

http://phoebekate.com/2008/09/14/randomness-creationism-and-intelligent-design

That’s how I look at it. Many physicists assume the unobservable wavelengths are governed by the same formulae of quantum theory, get themselves into infinities and the subtract out those infinities by hand, a process known as `renormalisation’. This sometimes works but its a bit of a trick to `undo” the ill effects of the wrong continuum assumption. In particular, such methods don’t work for the gravitational waves — which is why we have no conventional theory of quantum gravity.

Also notice that humans, life, lie in the middle of the physical wedge region. I’ll be arguing in a much later post that this is because we somehow built physics around ourselves (a kantian foundation for modern physics).

Faith means standing by your worldview and trying to interpret everything to fit it. Science is inventing a worldview and then doing your best to disprove it, and then choosing another, disproving it, and so on until you’re left with only the hypotheses that you’ve failed to disprove.

At that point, you’ll need to stop assuming a spherical horse so that you can disprove the rest of your hypotheses. If you’re lucky, you’ll be left with only one - not necessarily the coolest or most comforting one or the one that will please the most people, but if all the evidence supports it, you’re stuck with it. Unless you later manage to disprove that hypothesis too.

Religion doesn’t necessarily contradict the process of science, but it can interfere with it.

Also, thank you for the example. I’m no physicist, so I learned quite a lot from it. So the problem with the idea of a space-time continuum is not that the observable parts of it are wrong, but that it’s possible that the unobservable parts don’t continue along the same formula? What are the implications if this turns out to be the case?

I wanted to get beyond the usual level of debate on this issue because its only by conceding that science also makes key assumptions and showing how it deals with them (irreverently) that scientists can explain to non-scientists how science actually works and how it differs from religion. If its just `you faith, me not’ then the creationists have an easy fight back `just a theory’ and people can’t understand what the difference is and why its so dangerous for science education.

What I’m amazed about is how unworried the American people seem to be that the Republican VP candidate seems to support teaching of creationism in science lessons. I guess there are other things to worry about just now.