Category Archives: Technology and Society

The latest Crypto-Gram

Crypto-Gram is a monthly newsletter on security issues put out by Bruce Schneier of Counterpane Internet Security. I’ve mentioned it before, but it bears repeating. the link above is to the latest issue, which includes a well argued piece on handling terrorist suspects without skirting the Constitution. Schneier argues that it’s not necessary to work around established due process rules in order to deal effectively with terrorism. There are a couple of other really good items in this issue, notably the item on economic motivations for security theater (insurance companies will give you breaks on premiums if you install X-ray machines, even if you don’t use them effectively), and the item on ICS, a company selling an encryption scheme which they claim – get this – uses no math. Brilliant.

Anyway, if you’re at all interested in security issues and the tradeoffs between security and liberty, go on over and take a look.


John Derbyshire has been asking questions about why frozen sperm survives freezing, and gets a knowledgable email on the subject. The emailer does understand the issues, except for this:

A good post-thaw viability (survival of cells) is around 60% of the total of cells– some people advertise >80% or 90-%, but that is a bit of a ‘lie via statistics’ game– they don’t count all the dead population in computing the percentage. We are working here with different, more efficacious, and non-toxic CPAs, of which the most promising appears to be arabinogalactin extracted from larch trees.

As you can see, this is the reason that we will never get Ted Williams back among the living. His frozen body consisting of billions of cells simply would not work with only ~60% of the cells surviving the thaw process. As one can say, God instills the soul when He wishes, and outsmarts us all.

This, of course, presumes that the only method we will have, now and forever, is crude thawing. It ignores the future possibility of different techniques for restoring the tissue to room temperature and viability (e.g., nanomachinery that repairs as it warms). It’s fair to have an opinion that we may never have such capability, but it’s quite foolish, I think, to believe categorically that this is so.

More Supersonics

Kevin Murphy has some thoughts about supersonics, based on my previous post. He’s skeptical.

Given that he’s not stooped to calling me a scientific lightweight, and incapable of understanding mathematics, that’s fine, but he doesn’t really understand the whole picture, which is understandable since I haven’t really presented it. This is a matter of some frustration to me, but one that I can do little about until I can persuade the company involved to put up information on the web, so that it can be critiqued and reviewed.

Regardless, I’ll try to respond to his comments as best I can under the circumstances (which include limited time on my part).

…even if you have the same drag coefficient at supersonic as you do at subsonic — your drag, and thus fuel consumption, will increase substantially.

The key clause here is “if you have the same drag coefficient at supersonic.” At least for the wing, it’s actually possible to do better, at least in terms of induced drag (an effect of the end of the wing, which makes it greater than two-dimensional) which is actually improved at higher speeds. The notion, right or wrong, postulates that supersonic L/D for aircraft designed under this theory will be similar to that of subsonic aircraft, so it offers the potential (if not promise) of airfares comparable to subsonic fares for the same routes.

With regard to his comments on angle of attack, they’re not relevant, because any angle of attack that is non-zero will dramatically increase wave drag and induce shock waves. The aircraft’s nominal design condition is zero AOA. Takeoff and time to cruise aren’t an issue, either (as isn’t the engine) because we can get rid of the extreme sweep that has always been associated with supersonic aircraft (a design strategem that was always a kludge to come up with a way of minimizing wave drag without solving the fundamental problem).

Something like the SR-71 engines are a likely solution, in terms of the inlet, but that’s not a problem because they’ll be optimized for fuel economy at cruise speed (which will constitute most of their operating time), not takeoff/landing. Also, we’re not proposing anything as fast as the Blackbird–Mach 2.4 will probably be adequate.

But here is really the crux of the issue.

The claim is that with enough leading edge sharpness and the proper contouring behind, you can fly supersonically without shockwaves, except circulation (flow around the airfoil) which produces lift elimates the shockless effect. Why would this be? Well, without lift on a sharp symmetric airfoil the stagnation point would the the leading edge. If you add circulation, perhaps you move the stagnation point so that it is no longer on the leading edge. Could this be the problem? The flow splits at the stagnation point (that’s where it stops), and if it isn’t sharp where it splits, you get a shockwave? If that is the case, well, we’re screwed. No amount of adding in balancing circulation downstream will matter, and adding it to the flow over the wing to cancel it out will mean an end to the lift from the wing. Now you could make an unsymmetrical airfoil such that at the cruise condition the stagnation point is on the sharp point of the airfoil, but you’d have shockwave drag getting to that point (or if you had to fly off design point.)

The proposal is not to build a symmetric airfoil. Stagnation points really aren’t relevant.

Imagine a Busemann biplane, which is really a DeLaval nozzle inside two wings. The top of the upper wing is flat, as is the bottom of the lower wing. That allows the airflow to move past without shock. The ramping occurs within the two wings. Now, Busemann showed that this will have a shock-free flow, but because of the symmetry, it has no lift. Now imagine that the lower wing is dynamic–it’s actually a supersonic airflow coming from a non-shocking duct, with a flat lower surface. The lower surface of the “biplane” (after a short ramp) is a stream of higher-energy air (to satisfy Crocco), that mixes the total flow to provide the anti-circulation to balance the wing circulation.

The idea is to provide that balance to eliminate the need for the highly entropic downstream vortices, that require far more energy than that required to simply provide that balance. It spreads the residual shocks over a much larger footprint, reducing almost to insignificance the PSF on the ground, and essentially eliminates the wave drag.

Bottom line: if this works (and I don’t claim that it will–only that it’s not obvious to me that it won’t), this means wide-body supersonic aircraft, at non-ozone-eating altitudes, at ticket prices comparable to subsonic ones. It means obsolescing the current subsonic fleet in the same way that prop-driven airplanes were put out of business by jets, other than niches.

I think that it’s worth spending a tiny fraction (how about a percent of one year’s budget?) of the billion-plus dollars that NASA wasted on the High-Speed Research program, but NASA didn’t agree in the late nineties, even when Congress specifically appropriated it.

Some patent thoughts

One of the things I did in my dissolute holiday was play Texas Hold’em with Dan Barry, among other people. The first thing in my inbox when I got back was an email from my advisor asking if I’d be willing to help someone with some patent advice. Among the first websites I visited when I got back was The Space Review, on which there is an article advising space entrepreneurs on patents, using Texas Hold’em as an example. Bizarre little chain of coincidences. Not being superstitious I’m not trying to figure out the deeper meaning, but it’s a little odd.

Anyway, on the topic of patents, the article by Sam Dinkin is pretty much exactly on target, but I thought I’d mention the advice I always give people thinking about patenting an idea. This is based on all of six month’s experience doing IP work, so it’s far from definitive, but my job would have been simpler had I known it, so here goes: The most important thing to understand about patents is that they aren’t about ideas or inventions, they are about lawsuits. The only utility of a patent is in a lawsuit or threat of a lawsuit. If your idea is unlikely to be picked up by someone else, a patent is unlikely to help. Given that the time when people are thinking about patenting an idea is right at the beginning of their business, the money and time invested will often pay off better elsewhere, such as in building a proof of concept demo. A patent can be useful in scaring away competition, but that cuts both ways – if you think you can build a genuinely better mousetrap but it infringes someone else’s IP, all may not be lost. After all, it’s about a lawsuit, and the patent holder doesn’t always win – there are some really lousy patents out there.

Anyway, I’m repeating a bit of what Sam Dinkin said, but hopefully the repetition isn’t wasted. If you have a good idea that might be patentable, go read his article, and then go read what Don Lancaster has to say on the subject. Also, check out the EFF’s Patent Busting Project for some examples of some of the egregious stuff that manages to get patented. EFF is trying to bring some sanity to the subject but they could certainly use some help.

Show Me The Numbers!

To paraphrase the Cuba Gooding character from “Jerry Maguire.”

I keep seeing these breathless articles in the popular media, and even the trade press, about reducing sonic boom, with its promise of practical commercial supersonic flight. The latest hype comes from Popular Science (via Clark Lindsey).

Why do I call them hype?

Two reasons.

First, I have never, ever seen a single number in these articles indicating to what degree the boom is attenuated. Maybe it’s just my suspicious nature, but I suspect that if we could see those numbers, we might be less impressed.

Second, there is never any mention in these articles about the other problem that is holding back practical supersonic flight, which is all of the drag associated with the shock. Even if by some legerdemain with vehicle contours they can reduce the boom sufficiently to allow overflight of land, the operating costs will remain horrific and unaffordable to most, because of the tremendous amount of wave drag from the shock system and skin drag from the huge swept delta wings that all of these concepts continue to employ.

That means that at best, it will remain another Concorde, though perhaps one that can fly coast to coast–an expensive ride only for the rich.

I find this topic particularly frustrating because I’ve been aware for a number of years of a technology with the potential to effectively eliminate shock, with both the sonic boom and the tremendous drag associated with it, but there has never been any interest in pursuing it, from either NASA or industry.

Anyway, I’ll take this stuff seriously when I see some quantification of just how much they’re reducing the overpressure, and some indication of understanding of the drag problem, instead of focusing entirely on the boom.

[Update in the afternoon]

Clark points out in comments that they do show some numbers in a slideshow.

Color me unimpressed. There’s never been any doubt that one can reduce boom through body shaping–the issue is whether you can get enough reduction to solve the problem. This graph shows a softer peak, from a little over 1.2 PSF to about 9 PSF. So they’re reducing it by about thirty percent.

Big whoop. Still gonna break windows.

Is there any reason to think that they can do significantly better than this graph would indicate, particularly for a large transport? There’s none provided in the article. In fact, they even admit in the caption here, “Designers of the modified F-5E weren’t trying to eliminate the sonic boom, but prove that aircraft shaping can lessen this signature of supersonic flight.”

Big deal–we knew that.

And as Clark notes, there remains no mention of the drag issue.

Still looks like hype to me, similar to that over hypersonics. It may be beneficial for some military apps, but there’s no reason to think that it will usher in a new era of commercial air transport, or even make supersonic bizjets practical, despite the pretty pictures.

A couple of computer security issues

The latest Crypto-gram is out, and it’s got the usual good stuff in it. Two things that stand out are the Witty Worm, and a letter on computer security (the last one).

The Witty worm is particularly scary because it was so well written (700 bytes!) and so destructive (infected 100% of targeted systems in 45 minutes). The only reason it wasn’t a major story is that the worm targeted only systems running a particular company’s security software, and there were only a limited number of installations.

Who Am I?

Steven den Beste has a long essay on the nature of consciousness and identity (which I hadn’t noticed earlier because it starts out about anime, a subject in which my disinterest is astronomical). In it, among other things, he concurs with my comment a week ago about the late president (not to imply that he read it).

President Reagan’s heart stopped beating a few days ago, and low-level brain activity inside his skull also ceased. But he actually died long before that, from my point of view.

The problem is that we can’t really say when. It is usually a very long and gradual process. How much must you lose before you no longer exist at all? At what point is an Alzheimer’s patient really dead, if not when his heart stops beating?

Of course, that’s not a good criterion either, since hearts can be resuscitated. I’ve written before that, like identity, death itself is a legal state, not an objective scientific one.

He asks an ethical question as well:

Organ transplantation is one of the reasons why medical ethics now is forced to confront the question of when someone has actually died, even though their heart continues to beat. If we conclude they are nonetheless dead, it may be possible to save other lives.

In a case like that of Jon-Erik Hexum, or someone else who has suffered severe trauma to the brain in a car accident or via gunshot, that transition is sufficiently abrupt that it’s more straightforward. But should we consider the possibility of using Alzheimer’s patients as organ donors? And if so, how do we know that the disease has progressed far enough so that they, too, are effectively brain dead? I doubt that anyone will ever seriously consider using Alzheimer’s patients as organ donors precisely because it is such a sticky problem.

There’s a corollary to this question. Suppose we had a way of preserving brains, in some kind of suspension. We don’t know yet how to transplant them, or how to reverse the progress (if that’s the right word) of Alzheimers, but we could remove the brain and put it in stasis in the hopes that the future will both find a cure and the technology to replace it.

If the brain is the seat of the identity and the person, why wouldn’t it make sense to do such a preservation before the brain deteriorated, and the individual was lost forever to information death? Why would, or should, such a procedure be illegal (as it currently is)?

There was in fact a court case like this a few years ago. It wasn’t about Alzheimers–a man with a brain tumor petitioned a court to be allowed to be cryonically suspended if his condition took a turn for the worse, before it destroyed his brain. His assumption was that as poor as the prospects might have been for a cryonic suspension, it beat the odds of having a cancer destroy his mind, a condition that no future technology was likely to be able to repair. And in some sense, he was proposing an organ donation of his brain to his future self.

The court ruled against him, on the basis that he was asking permission to euthanize himself. The irony, of course, was that he was attempting to save himself, while the court was essentially sentencing him to a horrible death. Fortunately, his cancer went into remission, so the issue became moot for him, but the general principle remains. Unless and until we resolve the issues of identity, and where it resides, and what truly constitutes death (as opposed to the current and ever-changing function-based criteria) and differentiate the concept of information death from bodily functions, such issues will continue to be troubling, and in many cases, perverse.