Ralf raises some interesting points about the nature of privacy while we all live under the satellites, but I’m actually not sure if I agree with his conclusions. I’ll propose a few hypotheticals to explore the premise, and I’ll preface by saying that I’m not talking about legality or morality — both of which have things to say about public nudity — but about our personal sense of privacy.

Ralf links to a woman who was caught sunbathing by the Google Earth Orbiting Gnomes, and points out that although the picture is fuzzy enough to avoid being salacious, you can still determine the woman’s address — and hence a name and identity. So while we don’t quite know what it’s like to see her naked (or rather, we know what it’s like for an extremely nearsighted person to see her naked), we know the fact that she likes airing herself out in flagrante, which in and of itself invades her privacy.

I can agree with this, simply because she’s doing this on her roof, and not her backyard. Unfortunately, her sense of privacy is limited to two dimensions; she was considering whether she’d be visible from the ground, and forgot to think about Low Earth Orbit. I think it’s safe to say that if she lived next door to a high-rise apartment with balconies, the roof would have had the same connotations as her backyard for her sunbathing plans.

So where, then, should we have an expectation of privacy? Inside our houses? Unfortunately, most of us are forced to live amongst technologies that allow strangers to gather information about our private domiciles; generally, these are called “windows”. The other day, I accidentally knocked down the blinds off my window and haven’t yet bothered to stand on a chair to put them back up; therefore, since then, I’ve been turning off my lights before walking around naked at night, thanks to a rudimentary understanding of light refraction.

Presumably, I have the right to walk around naked in my own home, the line being drawn at a certain gray area of what might be considered exhibitionism since I don’t have the blinds up. Doing the can-can naked in front of the window, even in the privacy of my own home, might cross a few lines since the window itself creates a non-private zone.

Which leads me to a story I heard at Penn this year, about two undergraduates who decided to have intimate relations standing up against a large window, with the lights on, at night. Said students were clearly visible to other students living in the high rise next door, many of whom owned digital cameras, and some of these pictures made their way onto the Internet. Lawsuits and much academic debate commenced, which to me largely obscured the obvious point, namely: if you’re gonna get yourself laid in full view of a thousand horny undergraduates, you’re a damn fool if you don’t expect them to watch. The sole difference between a high rise dorm room (with those lighting characteristics) and the middle of College Green is that you’re allowed to have sex there, whereas getting busy in the center of campus would probably inspire one of that thousand to throw a bucket of water on you.

This is one of the areas where I actually do see an inevitable end of certain forms of privacy, as personal video cameras become ubiquitous enough that they’ll be impossible to avoid. I’m predicting an outgrowth of pre-sexual revolution chastity for today’s prepubescents, since they’ll be coming of sexual age at a time when the taboo against starring in an amateur porn video will still be in force, but the risk that any sexual partner might decide to make and publish one will be extremely high. (This is also a risk for us grown-ups, but once sexual habits are established, they’re very difficult to change.) Ultimately, though, it seems inevitable that the taboo will fall away as it becomes so common; when the teenagers of 2040 commonly find out that their mother was a hit on YouTube in 2010, their reaction is likely to be, “What’s the big deal?”

Likewise, I can certainly see why that sunbather would feel that her privacy was invaded, and it’s a shame that she’ll have to curtail her hobbies accordingly. But we should expect to see a resumption of rooftop nudity, as soon as we collectively realize that there’s no particular reason to consider that private.

Writing from Amtrak on the way to Philly. We left after the usual 15-minute departure delay, during which time the board listed us as on-time, and I overheard one woman complained that she’d have to wait another hour because they told her this train had left. I went to the cafe and asked if I could sit there, since the last time I tried this I proceeded to debate with the Amtrak employees for 20 minutes over whether I was allowed to. (The answer, in hierarchical order of people I spoke to, was no, yes, no, yes, no.) This time, like every other time, the answer was, “Sure. Why’d you ask?”

As I took my seat at the table, I noticed two drops of water on the cushion and a premonition told me to take the other side. Around 10 minutes later during acceleration, a long stream of water poured out of the ceiling onto the spot where I’d have been sitting. I noticed that the opposite corner of the same ceiling panel was directly over me, deduced what might happen when we were braking, and moved to another table.

Mentioned this to the conductor. “Oh, yeah,” he says. “Happens every time it rains, all over the train. No way of knowing where it’s going to come down.”

Does the A in Amtrak stand for Aeroflot?

Perry Metzger wrote a fascinating post on Interesting-People about the difficulty of using liquid explosives — and pointing out that you’d also have to forbid many other substances to get that job done.

So, lets say you have your oxidizer mixture and now you are going to mix it with acetone. In a proper lab environment, that’s not going to be *too* awful — your risk of dying horribly is significant but you could probably keep the whole thing reasonably under control — you can use dry ice to cool a bath to -78C, say, and do the reaction really slowly by adding the last reactant dropwise with an addition funnel. If you’re mixing the stuff up in someone’s bathtub, like the guys who bombed the London subways a year ago did, you can take some reasonable precautions to make sure that your reaction doesn’t go wildly out of control, like using a lot of normal ice and being very, very, very careful and slow.

On an airplane? On an airplane, the whole thing is ridiculous. You have nothing to cool the mixture with. You have nothing to control your mixing with. You can’t take a day doing the work, either. You are probably locked in the tiny, shaking bathroom with very limited ventilation, and that isn’t going to bode well for you living long enough to get your explosives manufactured.

We’re stopping people from bringing on board wet things. What about dry things? Is baby powder safe? Well, perhaps it is if you check carefully that it is, in fact, baby powder. What if, though, it is mostly a container of potassium cyanide and a molar equivalent of a dry carboxylic acid? Just add water in the first class bathroom, and LOTS of hydrogen cyanide gas will evolve. If you’re particularly crazy, you could do things like impregnating material in your luggage with the needed components. Clearly, we can’t let anyone carry on containers of talc, and we have to keep them away from all aqueous liquids.

Brian and I have been debating the fate of the world, mainly AIDS research and the environment, in a series of posts over on his blog. Feel free to join in, especially if you agree with me.