My point is this, it takes time to become an expert in a field but you don't always have to go to school to suceed.

Right. School gives you a leg up, but it doesn't guarantee your success. One of my friends who lives in Italy is a millionaire CEO of an oil company, which he runs out of an office that looks like an explosion at an office supply store. He has a basic high school education, yet he is one of the smartest and most insightful people I've ever met.

My philosophy is that you are never too old to learn, and never too smart to make a mistake. And those are primarily maxims I apply to myself. I've learned many things without getting a degree in that field or without sitting in a classroom.

I said earlier that common sense does not substitute for specific detailed knowledge of a particular field. That's still true. But it doesn't mean you have to get a degree in the subject in order to acquire that specific, detailed knowledge.

More that a library full of books, more than a wallet full of money, more than the most erudite professors on the planet -- the single most effective resource for gaining wisdom is the willingness to be taught. The actual information is almost always readily available.

Scientists, engineers, and other highly trained people can sometimes come off as arrogant. In fact, science begins with the observation, "Hey, that can't be right." A scientist can't be successful scientist until the point at which he is willing to admit he may be wrong about something.

Of course that doesn't mean we have to go back and question first principles every time. As I said, the very basic laws of thermodynamics are not likely to be wrong.

But what I'm trying to get at here is the notion of "teachability". That's really a synonym for humility. Scientists have to have a certain amount of it, otherwise they'll fail. And in fact anyone who wants to learn something has to first realize that he doesn't know it, but would like to.

At age 35 I decided I wanted to learn about theatrical lighting design. So I volunteered at a local theater where I studied it under their chief lighting designer. Now this guy didn't have a college degree whereas I did, and as part of that had studied the physics of light. On top of that I had taught illumination modeling to graduate students at a university that produced such household names as Gouraud and Phong. One could, in a certain sense, call me an expert in illumination.

But I didn't know a scoop from an ellipsoidal, or how to wire a resistance dimmer, or any of the specific skills that were necessary to the job. Nor did I understand the vast amount of art that has to go into such an endeavor. And so while I could comfortably stand in a college classroom and discuss topics such as irridescence, diffusion, and specularity, I was completely at the mercy of this relatively uneducated master of his art, who had a wealth of information, skill, insight, and who with careful experimentation had observed empirically many of the phenomena that I had learned theoretically.

I could have approached this experience with the notion that I knew it all already and that there was little this old fellow could have taught me. But instead I chose to be teachable.

As you can see, when I made the comment that the authors of "Dark Moon" or their sources had no background in heat transfer, fluid mechanics, thermodynamics or EVA glove or tool design, it was made with 20 years of experience.

And when I said they knew nothing of aerospace design, that's from my ten or so years consulting for design engineers from TRW, Morton Thiokol, Boeing, Lockheed, Hughes, and others.

And when I said they know nothing of perspective, that's partly from having grown up in a family of architects and having learned to draw accurately as soon as I could hold a pencil, and partly from having taught principles of numerical projective transformation to college graduate students. After learning it myself, of course.

It's also simply from observing perspective in the real world. See, I can slam out the linear algebra that defines a conical projection through a lens from affine space into projective space. But Bennett and Percy wouldn't understand the proof. If they did, they wouldn't be making the arguments they're making. So my training in this type of geometry is really only good for discussing the subject with other people who have had similar training.

Proof in this case is probably best accomplished by means of empirical evidence. That is, myriads of photographs that show that parallel lines -- be they features of objects, lines painted on the ground, or shadows cast in sunlight by parallel objects -- only rarely appear parallel in photographs.

I would agree with you that traveling around the world to verify every claim would be extremely expensive

As would I. But thanks to the miracle of the Internet the people who live in Australia or England or Indiana or Houston can do the research. Thanks, guys!

Like I also said earlier, if I ever find the themal analysis report of the Hassalbald camera, I will send you a copy.

I have several hundred megabytes and several shelf-feet of printed material having to do with many aspects of Apollo. Just tell me what you wish you had available, and I'll either be able to supply it or find it.

The host measures a replica of the LEM at The Space Centre in Houston

Are you talking about LM-9?

The LEM in Space Center in Houston hangs from the ceiling about 20 feet up and there is no access to it.

Yeah, you can look right up its skirt.

The upshot is that there's no actual LM anywhere in the world that you can just walk up to with a tape measure and start taking measurements.

Collier measured the hatch on a LM cockpit simulator, which he just assumed was cut to the same dimensions as the flight hardware.

My NASA experience has been that training versions are close but not the same.

The sine qua non of any cockpit simulator is the positioning of the controls. Everything else is negotiable. The main goal of the cockpit simulator is to give the pilot the "blindfold touch" experience. That is, pilots generally have to be able to sit (or stand, in this case) in a cockpit blindfolded and reach out and touch a specific control without fumbling for it.

Now on to Donna Tietze.

It's a staple fantasy of the conspiracy theory crowd that the government can make all traces of someone disappear just by the push of a button. It makes for great Hollywood movies, but it's impossible as a practical measure to accomplish that.

And ironically, the more notable someone is, the less possible it is to "erase" them. Ms. Tietze apparently had a long and distinguished career at NASA. People who have long and distinguished careers have to interact with other people in their field. They write papers, they go to conferences, they send letters to people, they win awards.

Someone somewhere will have a copy of the paper she wrote, her name in a conference proceedings, letters, articles, books. Someone will remember attending her awards ceremony.

Now in terms of inductive proof, it's impossible to prove she didn't work for NASA in the claimed capacity. The absence of evidence is generally not evidence of absence. But it can be, depending on the thoroughness of the search and the objective probability of any such search turning up the information.

If Ms. Tietze did do all she said, there would definitely be a pretty hefty paper trail of it, much of that in private hands where the government doesn't even know it exists. To find no traces anywhere of Ms. Tietze to substantiate her claim is indeed very highly suspicious.

But we've got the cart before the horse. Since a search for her identity would be conclusive only if exhaustive -- and that would be impossible -- it falls to Ms. Tietze to offer substantiation. In short, it can't be proven that she didn't work for NASA, but it can be proven that she did, if she did. Let her produce a pay stub, or the names of employees who would have known her, or an offer letter, or some other reasonably uncontestable bit of evidence that shows she did what she said she did.

Sadly, often investigation must proceed along the lines of what can be proven, not what ought to be proven.