The Bad Astronomer
Muse
- Joined
- Feb 19, 2002
- Messages
- 828
I was going to post this as a blog entry on my site, but now that we're a few days from TAM4, I think it's appropriate to post it here. Maybe I'll edit it a bit and blog it anyway. Still... if you're going to TAM 4, please read it.
***
So I carry this little card in my wallet. It's the same size as a business card. It's plastic, blank on one side. The other side, the business end, so to speak, has little pictures of spirals all over it, in red and green and blue. The surface is ridged with about a hundred very small, well, ridges, made of translucent plastic, so you can see the spirals through them.
If you hold the card upright (portrait mode for you printer-savvy readers) and rotate it around the long axis, the spirals appear to spin! It's quite a cool illusion. Even better, some spin clockwise and others counterclockwise! Everyone who sees it is fascinated by it. It's almost hypnotizing.
I picked it up in 1985 at a college bookstore. I wish I'd bought a hundred of them. They'd make great gifts. Hey, they'd make great business cards. Damn! Too late, I only bought one.
I really wish I had bought at least two. I couldn't figure out how the thing works! It's amazing. If I'd had another one, I could carefully peel off the ridges and see how it works. I knew it involved a Fresnel lens of some kind, but I couldn't see how that was done.
Over the years I showed it to a lot of people. Astronomers, physicists, even opticians. I showed it to the guy who was the inventor of the Hubble Space Telescope camera I worked on. This guy's no slouch, duh, he built a frigging camera on board Hubble, but even he was stumped by it.
So it's sitting in my wallet for years. Then, back in 2003, I got invited to TAM. I was thrilled! During the meeting, I went outside for the buffet breakfast and plopped myself down next to one James "The Amazing" Randi, and he's talking about a trick he did once. It jogged my memory, and I said to him, "Hey, what do you make of this?" and I hand him my spiral Fresnel business card thingy.
He looks at it, and without even hesitating, he says, "Ah yes, a visaview," and then he hands it back to me.
I suspect you could probably hear those words echoing around in my mouth, hanging open like a cave as it was. I'd had that card for nearly 20 years, and no one knew what the hell it was. I'd done web searches, even! And Randi knew what it was right away.
"I don't suppose you know how it's done, do you?" I asked.
And then (he is Amazing, after all) Randi launched into a history of the technique, about how it was discovered by accident when Wrigley was filming a chewing gum commercial decades ago. The ridges act like lenses, yes, but they also let light through only from a certain direction. There are several pictures underneath the lens part, split into rows and interlaced. When you look at one angle, one of the pictures gets lensed toward your eye. Change that angle by rotating the card, and you suddenly see a different picture. That's how the spirals rotated; there were several images of them, sort of like an animated cartoon is just a bunch of drawings seen in a sequence.
I was probably slack-jawed during the whole speech he gave. 20 years I'd had that thing. I should have eaten breakfast with Randi a long time back.
In another thread on this board, it was mentioned that Randi and other "big names" at TAM II weren't very accessible (though it was also said things were better at TAMIII). I think a lot of people are too star-struck, or just frightened, to go up to Randi.
Folks, do yourselves a HUGE favor. Talk to the guy. I have never walked away from a discussion with him without having laughed myself silly at some story he's told, and he has a lot of stories. He's all gruff and curmudgeonly on the outside, but on the inside he's just like the rest of us: gloppy, red, and full of disgusting organs and things. But he also is a pretty nifty fella, and you should get to know him better.
***
So I carry this little card in my wallet. It's the same size as a business card. It's plastic, blank on one side. The other side, the business end, so to speak, has little pictures of spirals all over it, in red and green and blue. The surface is ridged with about a hundred very small, well, ridges, made of translucent plastic, so you can see the spirals through them.
If you hold the card upright (portrait mode for you printer-savvy readers) and rotate it around the long axis, the spirals appear to spin! It's quite a cool illusion. Even better, some spin clockwise and others counterclockwise! Everyone who sees it is fascinated by it. It's almost hypnotizing.
I picked it up in 1985 at a college bookstore. I wish I'd bought a hundred of them. They'd make great gifts. Hey, they'd make great business cards. Damn! Too late, I only bought one.
I really wish I had bought at least two. I couldn't figure out how the thing works! It's amazing. If I'd had another one, I could carefully peel off the ridges and see how it works. I knew it involved a Fresnel lens of some kind, but I couldn't see how that was done.
Over the years I showed it to a lot of people. Astronomers, physicists, even opticians. I showed it to the guy who was the inventor of the Hubble Space Telescope camera I worked on. This guy's no slouch, duh, he built a frigging camera on board Hubble, but even he was stumped by it.
So it's sitting in my wallet for years. Then, back in 2003, I got invited to TAM. I was thrilled! During the meeting, I went outside for the buffet breakfast and plopped myself down next to one James "The Amazing" Randi, and he's talking about a trick he did once. It jogged my memory, and I said to him, "Hey, what do you make of this?" and I hand him my spiral Fresnel business card thingy.
He looks at it, and without even hesitating, he says, "Ah yes, a visaview," and then he hands it back to me.
I suspect you could probably hear those words echoing around in my mouth, hanging open like a cave as it was. I'd had that card for nearly 20 years, and no one knew what the hell it was. I'd done web searches, even! And Randi knew what it was right away.
"I don't suppose you know how it's done, do you?" I asked.
And then (he is Amazing, after all) Randi launched into a history of the technique, about how it was discovered by accident when Wrigley was filming a chewing gum commercial decades ago. The ridges act like lenses, yes, but they also let light through only from a certain direction. There are several pictures underneath the lens part, split into rows and interlaced. When you look at one angle, one of the pictures gets lensed toward your eye. Change that angle by rotating the card, and you suddenly see a different picture. That's how the spirals rotated; there were several images of them, sort of like an animated cartoon is just a bunch of drawings seen in a sequence.
I was probably slack-jawed during the whole speech he gave. 20 years I'd had that thing. I should have eaten breakfast with Randi a long time back.
In another thread on this board, it was mentioned that Randi and other "big names" at TAM II weren't very accessible (though it was also said things were better at TAMIII). I think a lot of people are too star-struck, or just frightened, to go up to Randi.
Folks, do yourselves a HUGE favor. Talk to the guy. I have never walked away from a discussion with him without having laughed myself silly at some story he's told, and he has a lot of stories. He's all gruff and curmudgeonly on the outside, but on the inside he's just like the rest of us: gloppy, red, and full of disgusting organs and things. But he also is a pretty nifty fella, and you should get to know him better.
