[QUOTE=Musicat]
MMMmm…love Angel Wings. Just give me some dipping sauce and a beer…
I have a good friend who insists that you can’t see colors under moonlight, as the special moon-white light makes all things monochromatic. If I show him a red object and a green object in the moonlight, and we can certainly tell the difference, he says, “Oh, that’s because it’s BRIGHT moonlight – that only works under a full moon.”
[/QUOTE]
Is he particularly challenged as to the nature of “white”? :smack:
[QUOTE=Peter Morris]
I’m not certain whether he was really that stupid, or just jerking the board around.
[/QUOTE]
If he was just jerking us around he was really dedicated to that little hobby, because he asked what seem like dozens of other questions which were just as stupid.
If I recall correctly, he was eventually forbidden from opening new threads in GQ without getting moderator approval in advance.
[QUOTE=wolf_meister]
Rick Jay (Posting #31)
I think what you meant to say is that the Moon has one eightieth of the mass of the Earth. (precise value: Earth Mass = 81.347 Lunar Mass).
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Same difference; at the same distance from the centre of mass, the Moon will exert 1/81st, more or less, the gravitational force of the Earth. That the astronauts weighed as much as they did is because they were substantially closer to the Moon’s centre of mass than it would be possible to be to the Earth’s.
I say this because I, and I suspect a lot of people, always assumed the Moon had 1/6th the mass of Earth, but it doesn’t.
[QUOTE=Chronos]
One that bugs me is freshman physics students who think the images in a mirror are two-dimensional. Ask any five-year-old, he’ll trust his senses, and tell you (quite correctly) that the images in a mirror are three-dimensional. But apparently by the time most folks get to college, that’s been beaten out of them: The mirror itself is 2-d, so the images must be, also.
…
[/QUOTE]
Wait, this one seems to be rather subtle. I thought we could only see in 2-D. Yes, there is a percieved depth from shadows, but if we were to see in 3-D we would see all sides at once. No?
Let’s define axes. If it was 1-D there would be a point, if 2-d a line, and if 3-D a line/shape with depth. However, we can represent all we see with just a set of lines. A picture of what we see would be 2-D, and therefore we see in 2-D.
What am I missing?
[QUOTE=Honey]
My ex Sister-in-law had one of her ovaries removed. My ex Mother-in-law insisted that no matter how many kids she had, they would all be the same sex. Because you know, females come from one ovary and males come from the other. I was never able to convince her otherwise.
I’m grateful to be done with that family.
[/QUOTE]
Did the sister-in-law have kids after that? I hope she had a boy and a girl. The mother-in-law would likely tell her the doctors botched her surgery. You should have asked which side was the boys, and which side was the girls.
Oh, wow, I forgot one of the best. My coworker once spent a weekend with a couple that firmly believed that gigantic aliens populated the Earth. Er…Nephilim.
They believed - this couple, that is - that Lilith descended from these giants and her offspring populated the earth, and that one day: they’d be back.
[QUOTE=Harmonious Discord]
Did the sister-in-law have kids after that? I hope she had a boy and a girl. The mother-in-law would likely tell her the doctors botched her surgery. You should have asked which side was the boys, and which side was the girls.
[/QUOTE]
She had one child, a boy, with her husband before they divorced. With my luck had she had another child it would have been another boy. Thus proving my MIL right. :smack:
[QUOTE=ZebraShaSha]
Wait, this one seems to be rather subtle. I thought we could only see in 2-D. Yes, there is a percieved depth from shadows, but if we were to see in 3-D we would see all sides at once. No?
Let’s define axes. If it was 1-D there would be a point, if 2-d a line, and if 3-D a line/shape with depth. However, we can represent all we see with just a set of lines. A picture of what we see would be 2-D, and therefore we see in 2-D.
What am I missing?
[/QUOTE]
Stereoscopic vision.
[QUOTE=ZebraShaSha]
My sister once told me that the first high we ever experience, as kids, is spinning in chairs. That’s where we get our addiction/love for drugs later on. It may sound crazy, but it’s science - she learned it in college!
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Is this really so hard to believe? Maybe, “If you spin around in a chair when you’re little, you’re more likely to get addicted to drugs later” is going a little far, but I wouldn’t be surprised if that spinning triggers some of the same type of brain activity as drugs do.
[QUOTE=garygnu]
Stereoscopic vision.
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Right. Basically, your two eyes don’t see exactly the same thing, because they’re not in exactly the same location. If you’re looking at something far away, the difference between the two images is very subtle. If you’re looking at something only a few inches away from your face, your left eye sees the item from a quite different angle than your right. Your brain can tell the difference between these two situations, and figures out how far away something is. This still works when you’re looking at a mirror. Also, if you move sideways, near objects seem to move across your field of vision faster than far objects. For example, point a video camera out the side of a moving car. When you play it back, roadsigns will move across the screen very quickly, cows in the distance much slower, mountains miles away even slower, and the moon even slower than that. This also works in a mirror.
[QUOTE=ZebraShaSha]
Wait, this one seems to be rather subtle. I thought we could only see in 2-D. Yes, there is a percieved depth from shadows, but if we were to see in 3-D we would see all sides at once. No?
[/quote]
No. Being able to see in 3-D is a funtion of having two close-set, forward facing eyes. Each eye sees the same image from a slightly different perspective. The brain integrates these two images, and the slight differences between the two of them is what allows us to perceive depth. There are a number of other tricks that people use subconsciously to differentiate between objects that are near and objects that are far, but they don’t allow the person to perceive objects in three dimensions.
Seeing in three dimensions is not the same as seeing in all directions at once. It’s the ability to perceive that an object has both height, width, and depth.
No. A picture can use some of the other tricks we use to gauge depth to present the illusion of three dimensions, but a person with normally functioning vision will have no problem telling the difference between a picture of a room, and the room itself, because the picture will not have the same depth as the room itself.
Imagine the difference between watching a normal movie, and one shown in 3-D. The normal movie is a flat image: we can tell that things are further away because they’re behind other objects, or smaller than objects in the foreground, but the movie clearly exsists in two dimensions: there’s no sense that what you’re looking at extends out past the screen or recedes deeper into it. Watching a movie in 3-D, however, you can “see” that things are clearly sitting at a distinct distance from where you know the surface of the screen to be. (This is done by creating a stereoscopic image: the film has two images at the same time, slightly offset. The glasses you wear filter the image so that each eye only sees one image, and the brain integrates the two different images the same way it does viewing true 3-D objects.)
Possibly, the ability to perceive real depth. It’s not an unheard of affliction, even among people who have otherwise good vision in each eye. Oliver Sachs wrote an article about this for a recent issue of the New Yorker. I can get the issue number when I get home, if anyone is interested.
[QUOTE=Exgineer]
If he was just jerking us around he was really dedicated to that little hobby, because he asked what seem like dozens of other questions which were just as stupid.
If I recall correctly, he was eventually forbidden from opening new threads in GQ without getting moderator approval in advance.
[/QUOTE]
Shit I remember that guy! What fun that was!
[QUOTE=Anaamika]
Oh, wow, I forgot one of the best. My coworker once spent a weekend with a couple that firmly believed that gigantic aliens populated the Earth. Er…Nephilim.
They believed - this couple, that is - that Lilith descended from these giants and her offspring populated the earth, and that one day: they’d be back.
[/QUOTE]
Well, then what about Hagrid? 
My sister keeps telling me that when my computer is slow, or something doesn’t work, it’s because “you have too much stuff on it.” (I have a little over half of the hard drive used up, because I have to back some stuff onto discs). It’s not about hardware or software capabilities, or RAM. It’s because I have so much stuff on my hard drive. Mmmmkay.
[QUOTE=Mindfield]
Pssh. Didn’t you ever see the original Superman movie? Where at the end Superman is so upset that a landslide killed Lois Lane that he flew up above the Earth’s atmoshpere and began orbiting it so fast that time reversed? I’m sure this is the concept that guy was trying to convey.
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It wasn’t so much the concept he was trying to convey; he’d seen the movie and fully believed you could reverse time by rotating the Earth in the other direction. When we tried to point out that it’s just a fuckin’ movie, he said you could tell it was real because you could hear Superman flying. Wuh Duh Fuh?
[QUOTE=Guinastasia]
My sister keeps telling me that when my computer is slow, or something doesn’t work, it’s because “you have too much stuff on it.” (I have a little over half of the hard drive used up, because I have to back some stuff onto discs). It’s not about hardware or software capabilities, or RAM. It’s because I have so much stuff on my hard drive. Mmmmkay.
[/QUOTE]
There’s sort of a grain of truth in there; if the ‘stuff’ consists of programs you’ve installed, then the system will slow down even when they’re not running because the registry will be bloated; if the ‘stuff’ includes lots of truetype fonts, then this can seriously affect performance; if the ‘stuff’ includes online games or browser extensions, then they could well have brought spyware with them, which will eat system resources and slow things down - so there are plenty of senses in which ‘too much stuff on it’ really can slow your machine down.
Even if the ‘stuff’ is just documents, images, music, etc, it can still affect performance if you have disk indexing switched on and the machine spends a lot of time maintaining the indexes, or even if the sheer number of files makes your scheduled virus scan run forever in the background.
If your machine is not running Windows, just ignore everything I said.
[QUOTE=Morgyn]
To paraphrase James Michener:
Holy Saint Leibowitz, protect them down there.
[/QUOTE]
I thought that was Walter M. Miller? :dubious:
Here’s the Superman/Reverse time thread:
http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=140878
Enjoy!
[QUOTE=McNew]
My high school health teacher taught us that the only way a woman could get pregnant is if she and the man both orgasmed simultaneously.
Given that she was a phys ed teacher corralled into “teaching” health, we gave her a pass on that one.
[/QUOTE]
If McNew’s high school health teacher = right, let GLOBALPOPULATION = 179.
[QUOTE=McNew]
My high school health teacher taught us that the only way a woman could get pregnant is if she and the man both orgasmed simultaneously.
Given that she was a phys ed teacher corralled into “teaching” health, we gave her a pass on that one.
[/QUOTE]
Jesus wept! I thought this notion had died out in the 1700s with the discovery of the microscope. Before that, her theory was the prevailing one: it was commonly believed that a woman had to oragsm in order to release her “female seed” and concieve. I have little doubt that this fallacy was encouraged by women ;). This belief had its harmful side in that it was used to “disprove” accusations of rape.
But, og almighty, I had no idea anyone still believed that. She didn’t also give a discourse on humours, did she?
[QUOTE=UncleRojelio]
So, if I showed you an image in a mirror and the same image printed out on paper and stuck to the back of a piece glass, or would be able to tell me which was which by virtue of these “layers”?
(Just asking because I’ve never really considered the question before)
[/QUOTE]
All I would have to do is move my head sideways, or maybe even cover one eye, then another. The virtual image “in” the actual mirror will have the objects in the foreground and background “move” different degrees due to parallax shift, while in the surface image of a print-behind-glass or HD screen they will not. Or if it shows a distinct foreground and background, just attempt to refocus from foreground to background. The mirror will let me, the print/HD screen won’t
Concrete example: I’m looking at my own face in a mirror. Behind me is a bookshelf. I hold the mirror and my head still, close my right eye. Above my left ear I can see the end of the shelf, and on it a box of PainShopPro and the corners of a book I can’t really discern as it disappears behind my head. Remain still and swtich eyes. Now my face shifted slightly, but the shelf is seen to extend farther away and I can see the PDP box, a hardbound copy of A.C. Clarke’s “Greetings, Carbon Based Bipeds”, and a box for PaperPort Deluxe. By changing slighly the angle at which I look at a stationary mirror, I now can see a virtual image something that was “behind” the original virtual foreground.
Also with both eyes open, I try to focus on reading the words “Paint Shop Pro”, and I can’t clearly see the image of my face. Focus on the image of my face, the images in the background go out of focus. The image in the mirror is subject to my eyesight’s natural depth-of-field limits.
Therefore there is virtual distance to that virtual image, in addition to height and width: The mirror provides a virtual image of 3-D space.
ZebraShaSha, those phenomena I describe, when happening in normal line-of-sight, is what is meant by that “we see in 3D”. Depth perception by our brains computing parallax and depth-of-field, plus perspective effects. In 2D, you’d depend on perspective, and that can work quite well – however, anyone who’s seen M.C. Escher’s work can tell you, perspective alone can trick you into “seeing” the impossible. (BTW, what we have is stereoscopic vision; “seeing all directions at once” would be holoscopic vision, I think.)
[QUOTE=JRDelirious]
Concrete example: I’m looking at my own face in a mirror. Behind me is a bookshelf. I hold the mirror and my head still, close my right eye. Above my left ear I can see the end of the shelf, and on it a box of PainShopPro and the corners of a book I can’t really discern as it disappears behind my head. Remain still and swtich eyes. Now my face shifted slightly, but the shelf is seen to extend farther away and I can see the PDP box, a hardbound copy of A.C. Clarke’s “Greetings, Carbon Based Bipeds”, and a box for PaperPort Deluxe. By changing slighly the angle at which I look at a stationary mirror, I now can see a virtual image something that was “behind” the original virtual foreground.
[/QUOTE]
Of all the things I have never thought to think of. Thanks for the push.
[QUOTE=Miller]
Possibly, the ability to perceive real depth. It’s not an unheard of affliction, even among people who have otherwise good vision in each eye. Oliver Sachs wrote an article about this for a recent issue of the New Yorker. I can get the issue number when I get home, if anyone is interested.
[/QUOTE]
I find it very difficult to see depth (you take the jokes from there) because of a confluence of factors - strabismus, amblyopia (lazy eye), and anisometropia (eyes of different prescriptions) - that cause my eyes not to work in tandem.