Fundamental Constants

Once upon a time, when I was but a humble undergraduate, I had a professor who interrupted his lecture to point out one of the fundamental constants of the universe:

"Unlike such things as the fine structure constant, which is occasionally up for discussion (and why 1/137?), there is one number that remains fixed and unchanging throughout time. When I was an undergraduate, commercial fusion energy was twenty years in the future. When I was a graduate student, commercial fusion energy was twenty years in the future. And now, as I look upon your bright and eager faces, I tell you that commercial fusion energy is twenty years in the future."*

* I may be gifting my old instructor with more eloquence than he actually possessed, but we'll give the old boy the benefit of the doubt.

I sat in my chair as he said this and harbored a secret chuckle, for I knew what he did not. I had spent several years as a technician working for the Fusion Research Center at the University of Texas on the Texas EXperimental Tokamak (TEXT), and I knew that with the remarkable breakthroughs that we were making daily, that it would only be a decade or so before someone, somewhere, had a working fusion reactor. After all, at that time there were hints from Princeton and other places of near-break-even operation, if only for a fraction of a second.

Well, today (and I am sorry to say that it has been much more than twenty years since I had sat in that classroom) there was an Op-Ed in the New York Times on the topic of fusion energy. Stewart Prager who is identified as the director of the Princeton Plasma Physics Laboratory has a wonderful piece that talks of all the benefits of fusion energy: it's not a greenhouse gas producer, it doesn't pollute, there is no chance for a catastrophic meltdown, it's available to every country on Earth, and the fuel is damn near free.

And then, in the last paragraph, just when he's closing the deal, he mentions the fundamental constant:

Fusion used to be an energy source for my generation’s grandchildren; now, plans across the world call for a demonstration power plant in about 20 years.

Hmmm, I wonder how the gravitational constant is holding up these days?

Penultimate Failure

Airbus recently tested the wing of their new A380 to destruction. Unfortunately, it failed a little earlier than anticipated. The test that failed is known as the Ultimate Load test. It involves mounting a wing in a jig and bending the tip up to simulate the strain that the wing might face in service. The first series of tests are to the "Limit Load" — the maximum amount that the aircraft is to carry in service. The European aviation authorities then require the wing to withstand a strain of 1.5 times the Limit Load for three seconds before failing.

The A380 wing failed between 1.45 and 1.5 times the Limit Load. Airbus will attempt to convince the authorities to approve the wing based upon models of any changes, rather than testing another actual wing. This is in accordance with standard Airbus practice. The A330 wing also failed just short of the standard. Airbus actually points to the failure with pride, pointing out how it means that there is no wasted weight spent on excessive strength, as compared with the Boeing 777 which didn't fail until 1.54 times the Limit Load.

While there is something to be said for avoiding excessive conservatism and the fact that the wing did fail at precisely the point predicted by the models, I'd prefer to fly on a plane that had been designed with the extra little bit of strength built in.