The Magic of Richard Feynman

Richard Feynman (1918-1988) was one of the more colourful and charismatic characters in US physics.
He's remembered as one of the greatest physics minds of the Twentieth Century, which sometimes leaves non-physicists wondering exactly what it was (apart from Feynman diagrams) that he actually did to get that reputation. How did he end up being regarded as some sort of god amongst physicists, he never actually discovered anything that most people will have heard of?

One of Feynman's hobbies was stage magic. He was a keen practical joker, and was fascinated by the way that people are led to believe certain things, or why they end up acting in certain predictable ways. He was fascinated by fallibility, and predictable fallibility, which is one of the reasons why he was such a a great choice when they were picking people for the Rogers Commission, to investigate the reasons for the 1986 "Challenger" space shuttle disaster. Feynman understood the concept of system failure, both at the organisational and personal level, and he liked to play with people, including other physicists.

Stage magic often works through a process of misdirection. The practitioner demands with every element of their voice, facial gestures and body language that the audience may like to look over //here//, to the extent that we find it almost impossible not to look at their selected spot – perhaps an inch or so away from their extended, waggling fingertips – while with their other hand over //there//, they perform the mechanics of the actual trick.

A magician might announce before performing their stunt: "Look at this table. It's a perfectly ordinary table. It really, really is." And they bang on the table with their fist, and walk around it, and hit it with a stick, and mark an X on it with white chalk ... and you're concentrating so hard on the table to try to find why it's NOT an ordinary table, that you fail to notice the large black velvety cloth hanging above it, or the trap door behind it. The table is, in fact, completely ordinary. It's a double-bluff.

That's misdirection. You don't necessarily tell the audience something that's untrue or misleading, you give them a series of false clues, and let them work out the wrong story for themselves.

Another factor that makes stage magic effective is the way that people apply Occam's Razor. Technical stage tricks often require ludicrous amounts of preparation, absurd amounts of technical expertise or physical dexterity, and improbable investments in custom hardware. The assistant just happens to be double-jointed, or has an identical twin sister, or a false leg. At some subconscious level, the watcher's mind runs through a set of absurdly complicated and tortuous conspiracy theories that might explain what they're seeing and gives up, deciding that it's simpler to assume that the magician really can fly or make tigers disappear. The audience reasons that this isn't true (it's "only a trick"), but at a gut level they've already suspended disbelief enough to enjoy the show.

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And so, to Feynman's magic trick.
One of the recurring stories about Richard Feynman goes something like this:
A physicist is working on a difficult problem. The physicist contacts Feynman. Feynman's secretary replies that Feynman is very busy, but could maybe schedule a meeting at some nebulous future date.
Several months pass. The physicist is contacted unexpectedly by the secretary to say that the secretary has just spotted that Mr Feynman now has a gap in his schedule, at quite short notice, and would the physicist still like to make use of it? The physicist eagerly agrees.

The physicist walks into Feynman's office.
"So,", says Feynman, "My secretary's just told me that you're working on some sort of interesting problem, but you'll have to forgive me, I've been really busy for the last couple of days, and haven't had the chance to look into it. Could you explain it to me? Oh, and could you start from scratch and make it simple, because, you know, this really isn't my field, and I'm not really up to speed with this subject. Start from the beginning."

The visitor is flattered and walks up to the board and starts explaining the nature of the problem. He pauses.

"So", says Feynman, "Let me see if I've got this right ..."

Feynman stares at the board and frantically marks symbols up while talking through what he's doing, until he has an equation.

"So your starting point would be something like that, yes? Okay, now tell me what you did next."

The visiting physicist is dumbfounded. What Feynman has just written on the board is the solution. And it's not just the solution, it's the solution to a more general version of the problem than the one that the visitor has been struggling with for months, or years. And Feynman's just done it in about three minutes flat.

The physicist leaves, ego totally destroyed, knowing that RF is in a totally different league to lesser mortals like himself.

Now, the "reveal".

If you were a suspicious stage-magician type, what you might suspect happened would be something like this: Physicist contacts RF's secretary, mentioning something about the problem. Secretary tells Feynman. RF researches the problem and all the relevant papers on the subject, and finds out how far the physicist has gotten. The secretary sends a stalling letter. Feynman adds the problem to his stack of other outstanding problems, playing them off each other, trying to cross-fertilise the different issues and bounce ideas between them, considering it a break from the problems he's actually trying to work on for himself. Finally, he works out the solution, and at this point, his secretary sends out the letter saying that RF now has an unexpected gap in his schedule.

Physicist arrives, RF plays dumb and asks them to outline the problem, RF "solves" it in three minutes flat, apparently using only the tools that the visitor has just provided.

Of course, this scenario still required RF to have been a damned good theoretical physicist. It also required RF to have had a wicked sense of humour, and to have done an awful lot of tough background work each time he pulled his stunt, just to create a few brief minutes of surprise for his "audience".

But that's exactly what stage magicians do.

The Principle of Relativity

The principle of relativity is pretty straightforward: it's essentially that "nothing is nailed down" The locations and properties of our universe's contents are defined by their relationships to other things in the same universe: there is no absolute sheet of "universal graph-paper" that's overlaid on the universe from outside that defines where everything "really" is, and which dictates the laws of physics in some occult manner.

If we think about the problem logically, we find that there's another aspect to the idea: if there were such a sheet of universal graphpaper, and that sheet did force physics to operate in such a way that we could identify an objects absolute motion relative to it, then that hypothetical sheet of graphpaper would (in a sense) have to exist within our universe, and the motion of bodies could once again be described using the principle of relativity, by treating our absolute frame as another (rather special) physical "thing". But it's perhaps slightly perverse to decide that the universe exactly one of these special things, with nothing else like it, so Occam's Razor pretty much demands that we reject the idea of a single absolute reference frame, unless there's compelling supporting evidence for it.

A more serious problem with the idea of an absolute, inviolable aetheric medium is that such a thing would appear to break some basic principles concerning cause and effect. Normally we assume that when a thing acts, it knows that it's acted ... that is, that there is a back-reaction for every reaction. We assume that if Object A exerts power over Object B, that A's ability to influence is somehow reduced, or at least altered in some way. There is no “something from nothing”, no expenditure of influence without a corresponding lessening of the bank account, and no free lunch. If A's ability to affect B was absolute and without consequence for A, then we could say that A's stock of influence appeared to be infinitely large. And if we are talking about an identifiable physical and quantifiable influence, it leads to some nasty mathematical results if we say that anything has an infinite quantity of a real physical thing. A further problem with these infinities is that they break accounting rules and the chain of causality. When asked where this influence comes from, we can't reverse the sequence of events and extrapolate any further back than the dictatorial rulings of our infinitely-strong metric, which then acts as a limit for any further logical analysis. It becomes a prior cause, a thing that can't be politely incorporated into a larger, fluid, mutually self-contained logical structure, but has its own separate anchor-point that doesnt relate to anthing else inside the structure, and allows it to dictate terms to everything else without retribution.

This sort of “absolute aether” is a way of saying that things simply happen in a certain way because they do, with no further analysis possible, and from a theoretical-analytical point of view, it's a dead end.

It was partly Einstein's appreciation of this problem that led him to the conviction that spacetime itself had to be a stressable, flexible, malleable thing. The “medium” of Einstein's general theory was the background gravitational field (which also defined distances and times), but the assumed properties of this field were no longer absolute, but were affected by the properties of the physics that played out within it. Spacetime was an interactive, integrated part of physics. The “fabric of spacetime” deformed gravitomagnetically as objects passed through it, and spacetime itself was the medium by which masses communicated with and connected causally to other masses. There was an interplay between the properties of spacetime and the properties of matter and energy – as John Wheeler put it, “Matter tells space how to bend, space tells matter how to move”.

The more static, "fixed" spacetime of special relativity, Einstein later decided, was a somewhat distasteful creature. Certainly special relativity had done away with the idea of there being any absolute reference for location, and even for absolute independent values of distance and time, but the overall spacetime structure still had an “absolute” quality to it, in that the geometry of Minkowski spacetime was meant to control and define inertial physics, without its own properties being in any way affected (a slightly abstract version of "action without reaction"). Minkowski spacetime was still "absolute" in the geometrical sense.

To quote Einstein ("The Meaning of Relativity", Princeton University Press):

... from the standpoint of the special theory of relativity we must say, continuum spatii et temporis est absolutum. In this latter statement absolutum means not only "physically real", but also "independent in its physical properties, having a physical effect, but not itself influenced by physical conditions".
...

It is contrary to the mode of thinking in science to conceive of a thing (the space-time continuum) which acts itself, but which cannot be acted upon. This is the reason why E. Mach was led to make the attempt to eliminate space as an active cause in the system of mechanics. According to him, a material particle does not move in unaccelerated motion relatively to space, but relatively to the centre of all the other masses in the universe; in this way the series of causes of mechanical phenomena was closed, in contrast to the mechanics of Newton and Galileo. In order to develop this idea within the limits of the modern theory of action through a medium, the properties of the space-time continuum which determine inertia must be regarded as field properties of space, analogous to the electromagnetic field.
...
... the gravitational field influences and even determines the metrical laws of the space-time continuum."

Because the word "relativity" is often equated with the predictions of specific theoretical implementations of the principle, it comes with a certain amount of historical baggage that isn't always useful when one wants to discuss a problem more generally. Sometimes it's more convenient to start from scratch and use a different form of words when trying to explain a relativistic principle without getting bogged down in historical implementational specifics. John Wheeler used the term "democratic principle" to refer to the idea that there's no single overriding cause that determines the forces on a particle, and another way of describing it might be to refer to the principle of mutuality, in that everything in the universe might be expected to not only have a vote in influencing anything that happens (subject to signal-propagation times), but also to be influenced itself in return.

So really, the principle of relativity in its broadest sense is just about going back to classical first principles: there's no action without origin and/or consequences, causality is A Good Idea, and nothing happens for no reason. These are somewhat pragmatic assumptions if we want to analyse the pattern of rules that the universe obeys – the first step is to assume that there IS a pattern.

There are, of course, more specific definitions of what the principle of relativity "says", which are tailored to the contexts of specific theories (usually Einstein's special and general theories). But we aren't obliged to use those existing definitions, and if we want a chance of discovering broader and deeper theories, we probably shouldn't.