The crust and upper mantle are solid, 99% of the partially melted asthenospheric mantle is solid rock, the mantle beneath that is solid rock, and the inner core is solid. That really just leaves the outer core as liquid.
According to this nice summary, the mantle (asthenosphere part of it, anyway) is "semi-solid". Other sources describe it as akin to toothpase or silly putty.
It has been realized since the 1800s that for the Earth to retain its nearly spherical shape as it spins, the average strength of the Earth must be greater than that of a similar sized ball of glass or iron.
That's a pretty good trick, seeing as how iron is stronger than stone, which you're saying most of the planet is made of. Anyway, Jupiter spins over twice as fast, is immensely larger, and made almost entirely of fluids (i.e., non-solids), and even so is only just visibly squished! Earth, being so much cooler, smaller, slower, and more solid, would have no reason to be any other shape than "almost spherical", would it? Where are you getting this?
Wait a sec. I thought they only came up with usably accurate and precise equipment for doing interferometry with visible wavelength recently (say, in the last 10 years or so). We could do this since the 20s?? Where the heck are our pictures of the moons of the fifth planet of Regulus V?
I saw this a couple weeks ago, on Scientific American Frontiers (or Alan Alda in Scientific American Frontiers, or Alan Alda Acts As Everyman or whatever they're calling it now), on PBS.
Whyyyy, you whippersnappers got it too easy. When I was in high school, we had to take BASIC classes on an old IBM System/34 with eight terminals! And Pascal on PCs with mono green monitors and two floppies (what's a "hard drive"?), or the sooper-dooper CGA one (four colors that we don't get to choose? THANKS!), if you were lucky! Aaaaand we liked it!
We didn't have no fancy-dancy Cisco classes (for two years, no less!)! If we wanted to learn about hardware, we had to scrounge around behind the local ComputerLand for junked parts, and we'd cut our hands on the broken circuit boards and CRTs! We'd be networking-ignorant morons with bloody shredded hands and we'd say "Ohhhh noooo, maybe this wasn't such a good idea", but it was TOO LATE! Aaaaand we liked it!
Re:Who writes these articles? Or am I iggernint?
on
Non-Spherical Stars
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· Score: 1
A cohesive object doesn't have to be made of matter in a solid state. You can't move through three feet of ice (by yourself anyways), but you can jump into a lake or walk through a fog.
Fog is a cohesive object? Then what the heck is non-cohesive? A ghost?
Re:Who writes these articles? Or am I iggernint?
on
Non-Spherical Stars
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· Score: 1
Real black holes are likely to be spinning. And then they aren't spherical, as I recall.
The black hole itself (that is, the matter that constitutes it) can be whatever shape it wants to be. What we're talking about is the shape of the event horizon, which is purely defined by the escape velocity, which is purely defined by the gravitational attraction at a certain distance, which is purely defined by the mass and distance from center point. All points at a certain distance from a point a sphere; that's the mathematical definition of a sphere.
Now, imagine those two people pull at ninety degrees to each other. The load will experience a certain force. Now, imagine the two people pulling with the same force, but this time being only thirty degrees apart.
Key phrase: "with the same force." More in a sec.
Now, imagine two points equidistant from the black hole, one above the pole, and one in the equatorial plane. The black hole is going to subtend more of an "arc" from the polar point's point of view than the equatorial point of view. The polar point is going to be pulled from a wide angle. The equatorial point is going to be pulled from a narrower angle.
Right. BUT. The sum of the pulls from all the points in 3-space (an integral) is going to be the same either way. This is a basic result of physics and calculus. The points from the view of the polar point will be more spread out laterally, but will be closer together in distance, whereas the points from the view of the equatorial point will be closer together laterally, but more spread out in distance. Remember, the gravitational attraction falls off with the square of the distance, so closer points have a much higher attraction than far ones.
I wish I could remember the integral and show you, but I simply remember this result from physics class in college: the attraction is purely dependent on the distance to center and mass within the sphere defined by that center and radius. (Which means that the mass above your sphere cancels itself out -- if the star were oblate enough (almost a disk), and you sat on the surface at the center of that disk, you would hardly feel any gravity at all: only the mass contained in the sphere defined by the star's center and your radius from that center (only a small portion of the star) would count toward your gravitational acceleration.)
Re:Who writes these articles? Or am I iggernint?
on
Non-Spherical Stars
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· Score: 1
Actually, I think they mean "solid-body" as "cohesive object" in this case.
Ermmmm...and how is that different from solid in the usual sense?
While I'm getting technical, Plasma can't be considered a fluid either, as it's not a liquid, it's a different state of matter altogether.
Unless I'm mistaken, a fluid is any state of matter in which the molecules flow freely and assume the shape of the container (i.e., liquid, gas, or plasma). How is a plasma not a fluid?
The fact that we can measure it is a breakthrough.
You got that right. Who would've thought we could start to resolve the diameters of other stars within our lifetimes?? Astromony never ceases to amaze.
The truth of observation that astronomy has advanced more in the last 30 years than the over entire previous history of man must surely give the power of Moore's Law a run for its money.
More to the point, the event horizon of a black hole (which is all you can ever sense about its shape) is a perfect sphere because your overall gravitational attraction to a thing is determined by your distance from its center, not from its surface. Therefore, the escape velocity will always be the same at any spherical shell around the gravitational center. And, of course, all the event horizon is is the spherical shell where the escape velocity equals the speed of light.
Who writes these articles? Or am I iggernint?
on
Non-Spherical Stars
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· Score: 3, Interesting
Due to its daily rotation, the solid Earth is slightly flattened...
Solid Earth? Only the surface (and part of the core) is solid, right? The rest is [Dr. Evil] liquid hot magma.
The observed flattening cannot be reproduced by the "Roche-model" that implies solid-body rotation and mass concentration at the center of the star.
I thought stars were pretty much all plasma, which is to say, a fluid. Why, therefore, should stars obey any "solid-body" rule at all?
...that everyone calls them "SCO" and not by their full, expanded name. That way, a fine town and school doesn't get dragged down into hell with them in people's minds.
Human attention, on the other hand, has hard limitations.
Spam takes a lot of your attention.
P2P does not.
Thus, spam is a bigger problem than P2P.
In other news...
In a shocking new study, it has been found that 95% of Internet bandwidth is used by things people want to do, but only 5% is taken by things they don't want to do. When contacted, a BOFH spokesman said only "I'll put a stop to that."
That would mean it operates by static electricity; a single spark when touched (the kind induced by your typical annoying office carpet). This thing continually sparks -- indicating continual current. Which you'd have to trigger for this to be of any use.
"Hold on, stop raping me for a second so I can unlock my electric coat so I can zap you..."
There's a short story Isaac Asimov wrote in 1957 called "The Feeling of Power", in which the ability to do arithmetic has been lost by humans, long since completely dependent on machines to do calculations for them. One guy rediscovers this lost art, christens it "Graphitics", and goes on to...well, I don't wanna spoil it for you. Here, read it yourself.
Finished? Good. Of course, the reliance on 1957-level projections of computer sizes, costs, speeds, and so on makes the story seem a little bewildering to modern readers (where modern = almost a whole 50 years later, ooo scary), but still...
Slashdot Mirror
Wait a sec. I thought they only came up with usably accurate and precise equipment for doing interferometry with visible wavelength recently (say, in the last 10 years or so). We could do this since the 20s?? Where the heck are our pictures of the moons of the fifth planet of Regulus V?
I saw this a couple weeks ago, on Scientific American Frontiers (or Alan Alda in Scientific American Frontiers, or Alan Alda Acts As Everyman or whatever they're calling it now), on PBS.
Not measure the diameters, resolve the diameters. As in, take a picture of, with sufficient resolution to see the dang thing.
Whyyyy, you whippersnappers got it too easy. When I was in high school, we had to take BASIC classes on an old IBM System/34 with eight terminals! And Pascal on PCs with mono green monitors and two floppies (what's a "hard drive"?), or the sooper-dooper CGA one (four colors that we don't get to choose? THANKS!), if you were lucky! Aaaaand we liked it!
We didn't have no fancy-dancy Cisco classes (for two years, no less!)! If we wanted to learn about hardware, we had to scrounge around behind the local ComputerLand for junked parts, and we'd cut our hands on the broken circuit boards and CRTs! We'd be networking-ignorant morons with bloody shredded hands and we'd say "Ohhhh noooo, maybe this wasn't such a good idea", but it was TOO LATE! Aaaaand we liked it!
Thank you!
Right. BUT. The sum of the pulls from all the points in 3-space (an integral) is going to be the same either way. This is a basic result of physics and calculus. The points from the view of the polar point will be more spread out laterally, but will be closer together in distance, whereas the points from the view of the equatorial point will be closer together laterally, but more spread out in distance. Remember, the gravitational attraction falls off with the square of the distance, so closer points have a much higher attraction than far ones.
I wish I could remember the integral and show you, but I simply remember this result from physics class in college: the attraction is purely dependent on the distance to center and mass within the sphere defined by that center and radius. (Which means that the mass above your sphere cancels itself out -- if the star were oblate enough (almost a disk), and you sat on the surface at the center of that disk, you would hardly feel any gravity at all: only the mass contained in the sphere defined by the star's center and your radius from that center (only a small portion of the star) would count toward your gravitational acceleration.)
"'Age of onset of prostate cancer, 53 years.' When's your birthday?"
"Two weeks ago."
"Uh...hup...yeah, there it goes. Sorry, pal."
The fact that we can measure it is a breakthrough.
You got that right. Who would've thought we could start to resolve the diameters of other stars within our lifetimes?? Astromony never ceases to amaze.
The truth of observation that astronomy has advanced more in the last 30 years than the over entire previous history of man must surely give the power of Moore's Law a run for its money.
More to the point, the event horizon of a black hole (which is all you can ever sense about its shape) is a perfect sphere because your overall gravitational attraction to a thing is determined by your distance from its center, not from its surface. Therefore, the escape velocity will always be the same at any spherical shell around the gravitational center. And, of course, all the event horizon is is the spherical shell where the escape velocity equals the speed of light.
Due to its daily rotation, the solid Earth is slightly flattened...
Solid Earth? Only the surface (and part of the core) is solid, right? The rest is [Dr. Evil] liquid hot magma.
The observed flattening cannot be reproduced by the "Roche-model" that implies solid-body rotation and mass concentration at the center of the star.
I thought stars were pretty much all plasma, which is to say, a fluid. Why, therefore, should stars obey any "solid-body" rule at all?
Leave the CD stationary, but spin the laser beam. As in, the way a laser printer does, with a high-speed rotating mirror. 172x, here we come!
...that everyone calls them "SCO" and not by their full, expanded name. That way, a fine town and school doesn't get dragged down into hell with them in people's minds.
(Go Slugs!)
*Sigh*
Has the day finally arrived when people can't tell you're kidding despite the introduction of two instances of "d00d"?
(Anyway, I send my encouragement to all underground developers.)
Dance Dance Revolution is totally a Simon ripoff. Which is itself totally a "Simon Says" ripoff. Totally, d00d.
Truisms of the information age:
Bandwidth gets cheaper according to Moore's Law.
Human attention, on the other hand, has hard limitations.
Spam takes a lot of your attention.
P2P does not.
Thus, spam is a bigger problem than P2P.
In other news...
In a shocking new study, it has been found that 95% of Internet bandwidth is used by things people want to do, but only 5% is taken by things they don't want to do. When contacted, a BOFH spokesman said only "I'll put a stop to that."
That would mean it operates by static electricity; a single spark when touched (the kind induced by your typical annoying office carpet). This thing continually sparks -- indicating continual current. Which you'd have to trigger for this to be of any use.
"Hold on, stop raping me for a second so I can unlock my electric coat so I can zap you..."
There's a short story Isaac Asimov wrote in 1957 called "The Feeling of Power", in which the ability to do arithmetic has been lost by humans, long since completely dependent on machines to do calculations for them. One guy rediscovers this lost art, christens it "Graphitics", and goes on to...well, I don't wanna spoil it for you. Here, read it yourself.
Finished? Good. Of course, the reliance on 1957-level projections of computer sizes, costs, speeds, and so on makes the story seem a little bewildering to modern readers (where modern = almost a whole 50 years later, ooo scary), but still...