AS an astronomy-obsessed kid in the 1970s, I subsisted on a steady diet of science fiction. It promised a future filled with technological wonders: talking computers, bionic limbs, flying cars. Forty years later, though much of that future has arrived, it’s still missing what I consider its most important ingredient. Sure, we’ve got the iPhone’s Siri, and the Food and Drug Administration just approved a prosthetic arm controlled by signals from the brain — but where are our smooth-gliding flying machines, our Landspeeders (“Star Wars”) and airborne DeLoreans (“Back to the Future”)?
You may think that the absence of such cars speaks to a failure of engineering or distorted incentives in the marketplace. But the humbling truth is that we don’t have these vehicles because we still don’t know, even in principle, how to directly manipulate gravity. Indeed, the cars missing from our skies should serve to remind us that, to a degree rarely appreciated, we have surprisingly poor control over most of nature’s fundamental forces.
full article at I Was Promised Flying Cars – NYTimes.com.
This article points out something I’ve never thought about. That we really only have command of one of the four fundamental forces of nature, electromagnetism. We have a crude limited ability to manipulate the strong and weak nuclear forces, but no ability whatsoever to manipulate gravity. (Although we do understand it well enough for our spacecraft to navigate the interacting gravity of solar system bodies.)
I see this as a reminder of how beneficial a usable theory of quantum gravity might be, whether or not it rises to actually being a theory of everything. Physicists have, of course, been pursuing this for the last several decades. That’s what all the speculative stuff about strings, branes, and the like are about. But I think it’s fair to say that, aside from some mathematical techniques, little reliable knowledge has come of it.
Modern physics appears to be spinning its wheels on this issue. It’s not even clear what empirical investigations might help, although the LHC appears poised to dispense with a lot of theories when it fires up again, principally by burying supersymmetry. (Although the advocates of that theory will likely continue to claim its viability in modified forms for years to come.)
It feels like some new fundamental insight about how the universe works will be necessary to move forward. (Of course, any such insight will have to account for what we already know, something many claiming to have that insight fail to appreciate.)