I'm watching my local PBS station late at night, and they're running a 9/11 "truther" video presentation. (Partially on the taxpayer's dime, of course.) Ah, the reality-based community in action! If you have any understanding of fairly elementary physics, it's rather painful to watch.

For example: We're shown a film of the collapse of one of the WTC towers. The narrator notes the tower begins to collapse at the point of jet impact (bombs are planted there, he assures us), and yet he points to a small (very small) puff of smoke coming out above those floors, as the top of the building begins to drop into the burned-out area. Well, yes, of course: there's a huge hollow elevator shaft (and several vertical ventilation shafts) running between those floors, and some air will escape in all directions, including even up, as the space collapses.

(And even if there were bombs, why would you plant them near the top of the building and blow them up at the same time? It never seems to occur to him to ask this question.)

Then, as the building begins to fall, more damning evidence! As each floor collapses (in a "pancake collapse") puffs of smoke come out the windows! Where else was the air on each floor supposed to go, instead of outward? We're never told. Bombs must be going on off on each floor because, um, apparently, if they didn't, the entire top of the tower would have just stopped after the first collapse, and balanced there, in place, for weeks on end!

Of course, they show clips of people on the street saying it sounded like an "explosion". Well, it certainly ought to have! The top third of the building just crushed several floors and forced a huge amount of air and debris outward in less than a second — hence the word "ex-" (out) "plode" (burst). Again, where was the air and debris supposed to have gone? Was it supposed to have teleported itself into outer space???

And some people felt a shock beneath their feet! Well, again, yes, that's what we'd expect: when the top section first collides with the mostly-still-intact structure beneath the burned-out area, a shock would have been transmitted all the way down the building, into the ground. (In contrast, a controlled demolition uses many, small, perfectly-placed explosions which cut through support beams, rather than shaking the ground. Even in that case, it's the collapse of the structure itself which eventually does the shaking.)

Much is made of the fact that some people seemed to know WTC 7 was going to fall before it did. Let's see: it had several floors burning, buildings nearby had just collapsed from the same sort of damage, further weakening it, and undoubtedly you had some of the best structural engineers in the city advising you on what was going to happen next.

And of course, opposite views prove the same thing: Not many expected the main WTC tower to collapse as soon as it did, therefore proving it must have been blown up! Afterwards, observers guessed WTC 7 would probably collapse too, therefore proving — it must have been blown up! If the outcome is expected, it's a plot! If the outcome was unexpected — that also proves a plot! Verily, there's no way to disprove such criteria.

Now they're making much of the fact a few small bursts come out of the building below the area of collapse as the collapse proceeds. The host tells the audience that some claim it's "air" which is blowing out the windows — but it's really debris! (Of course the air contains debris! Why would we expect otherwise?) And it must have been caused by bombs!

(Which makes no sense whatsoever: If it was a "controlled explosion", why blow out a few random windows ahead of time, well below the collapse? Again, it never seems to occur to him to wonder about this.) He states if it were a natural event, all the windows would blow out at once. Really? Why? Is there a difference between a change in air pressure caused by a bomb, as opposed to a change in air pressure from a collapse above? Actually: I'd expect the opposite, a-la Die Hard: Bombs would cause a huge, almost instantaneous local change in pressure, blowing out all the windows, where as the increase caused by a collapse above would be quite a bit slower, being relieved when the weakest window on a floor (or series of adjacent floors) blew.

Next: The building collapsed at the approximate the speed of falling debris! Of course when they show the collapse you can see, with your own eyes, this isn't so: ejected debris, even with air resistance, is falling faster than the collapse. But he has a neat timer and calculation to "prove" the opposite of what you're plainly seeing.

To further "prove" how improbable this is, he has (you're not going to believe this!) several cardboard boxes shaped like parts of a WTC tower. He drops one small box, shaped like the top section, an inch or so onto another box (shaped like the main tower remaining below) and notes it stops! Meanwhile another, dropped over open air, falls to the ground! Oh my!!!

This is so stupid that I literally am clutching my head and shaking it in mental anguish and disbelief. I feel embarrassed even to be seeing be this. This actually made it on TV, and yet the studio audience — I can see them — are cheering and clapping (a standing ovation!) — so impressed are they by this demonstration. (As, undoubtedly, are the people at my local PBS station who decided to air this. My head hurts just contemplating it.)

Look: smaller objects, even when constructed identically to larger ones, have much stronger structural support. That's why an tiny ant can lift twenty times its weight, but a scaled-up human- or elephant-sized ant (like you see in 1950s movies) wouldn't even be able to hold up its own weight.

Further, even ignoring that (which you really shouldn't) an empty cardboard box is constructed nothing like a skyscraper. It's made of relatively light paper, not steel. It's a continuous solid piece (well, solid on the outer edges, corrugated inside), not an open lattice of tiny metal sticks fused together with weaker glass bits between them. It's completely hollow and empty within, where a building is not. If skyscrapers had the same structural characteristics as cardboard boxes, anyone could build them: just fold 'em up and put masking tape on the corners. Geez.

They want me to donate. Is there any way I could donate a negative amount? I can't bear to watch any longer. But I do, with the mute on, as I finish typing this: turns out it was produced at my local PBS station, by some of their camera people and directors! I suddenly feel very, very good about my decision to stop supporting my local PBS station.

But this is still so, so sad.