Concepts, Conceits, And Physical Laws

     “It’s better not to know so much than to know so much that isn’t so.” – Originator unknown, but frequently attributed to humorist Kin Hubbard

     Mankind is a limited species. We are capable within those limits, but incapable outside them. People forget this rather frequently – usually when it would satisfy their most cherished fantasies if it were not so. Some of the folks most frequently guilty of imagining themselves unlimited, at least within a particular demesne, work in science or technology.

     Consider, if you will, a phrase often bandied about, sometimes in a sarcastic or humorous fashion: “Does it violate the laws of physics?” Smith might reply in this fashion to Jones, when Jones objects to a proposal of Smith’s. The implication, of course, is that if what Smith has suggested doesn’t violate the laws of physics, then it’s possible at the very least.

     (Yes, many things are possible in theory but aren’t doable in practice. But that’s not what I’m driving at here. Bear with me.)

     What is the subtext of Smith’s riposte to Jones? Only this: “You and I both know the laws of physics well enough to be aware that what I’ve proposed lies within them.” Among scientists and technologists, that subtext usually goes unchallenged. That’s a pity.

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     The suggestion that the spatiotemporal universe we inhabit is “governed” by “laws” is an assumption, a premise required for the orderly investigation of natural phenomena. It’s been a generally trustworthy assumption since Francis Bacon. However, it underpins a form of conceit that’s had as much of a retarding influence on the accumulation of human knowledge as any set of taboos.

     Breakthroughs in the hard sciences are achieved mostly by young researchers. Such persons are more willing to challenge what “everyone knows” than their elders. The elders serve the cause of scientific advancement by forcing the young upstarts to prove their contentions. I use the word prove not in the mathematical sense of establishing a truth impervious to contradiction, but in the observational sense: the demonstration that some phenomenon does not conform to the “laws of physics” as the elders imagine them.

     The universe does indeed seem to obey a set of “laws of physics.” However, the further we probe into the realms of the very large, the very small, and the very fast, the more likely it seems that we don’t really know those laws in absolute, all-encompassing, perfect-precision exactitude. As we’re too limited a species to go beyond certain magnitudes, my contention is that we never will.

     The true scientist is aware of the nature of true science: a realm of observation, inference, hypothecation, and experimental design in which a theory can be disproved but never proved beyond all possibility of subsequent contradiction. He hopes not for absolute knowledge but for confidence: an ever-increasing set of confirmations of the theories he propounds about the laws of Nature. That confidence arises from success in predicting the outcomes of relevant, well designed experiments.

     Such a scientist must remain faithful to Socrates’ Dictum: “Only one thing do I know, and that is that I know nothing.” To abandon that post is to leave off being a scientist and become a dogmatist.

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     This comes to mind today because of this article about the EmDrive:

     SINCE THE BIRTH of the space age, the dream of catching a ride to another solar system has been hobbled by the “tyranny of the rocket equation,” which sets hard limits on the speed and size of the spacecraft we sling into the cosmos. Even with today’s most powerful rocket engines, scientists estimate it would take 50,000 years to reach our closest interstellar neighbor, Alpha Centauri. If humans ever hope to see an alien sunrise, transit times will have to drop significantly.

     Of the advanced propulsion concepts that could theoretically pull that off, few have generated as much excitement—and controversy—as the EmDrive. First described nearly two decades ago, the EmDrive works by converting electricity into microwaves and channeling this electromagnetic radiation through a conical chamber. In theory, the microwaves can exert force against the walls of the chamber to produce enough thrust to propel a spacecraft once it’s in space. At this point, however, the EmDrive exists only as a laboratory prototype, and it’s still unclear whether it’s able to produce thrust at all. If it does, the forces it generates aren’t strong enough to be registered by the naked eye, much less propel a spacecraft.

     I’m eager for the results of the tests proposed for the EmDrive. I hope it demonstrates thrust without reaction for two reasons. First, it’s every science-fiction writer’s dream that reactionless propulsion be possible and achievable. Without it, we’re probably stuck in this solar system. But second and more important, it would reveal that one of the “laws of physics” – the conservation of momentum – comes with a codicil that begins “except for…” and goes on to state circumstances where it doesn’t apply as we’ve understood it lo! these many moons. That would be a true advance in the science of physics.

     What are the odds? I have no idea; I’m not conversant with the mechanisms underlying the EmDrive. If I had to place a bet, it would be on the conservation of momentum. In other words, I’d say the observed thrust is probably an illusory effect. But science requires that I be open to the possibility that the EmDrive will really work as proposed.

     It really comes down to a concept – and a word – that scientists cordially detest and strive to avoid with all their might:

     Not that the count was a drone. At last reports, he had been involved in some highly esoteric tampering with the Haertel equations—that description of the space-time continuum which, by swallowing up the Lorentz-Fitzgerald contraction exactly as Einstein had swallowed Newton (that is, alive), had made interstellar flight possible. Ruiz-Sanchez did not understand a word of it, but, he reflected with amusement, it was doubtless perfectly simple once you understood it.
     Almost all knowledge, after all, fell into that category. It was either perfectly simple once you understood it, or else it fell apart into fiction. As a Jesuit—even here, fifty light-years from Rome—Ruiz-Sanchez knew something about knowledge that Lucien le Comte des Bois-d’Averoigne had forgotten, and that Cleaver would never learn: that all knowledge goes through both stages, the annunciation out of noise into fact, and the disintegration back into noise again. The process involved was the making of increasingly finer distinctions. The outcome was an endless series of theoretical catastrophes.
     The residuum was faith.

     [James Blish, A Case of Conscience]

     Food for thought…and for humility.