Another similar technique is dithering. I guess computer graphics nerds are familiar with this, but it's handy to do to any signal that's about to get digitized -- add about half a bit of noise and you can pick up signals of less than one bit amplitude. Of course with poor signal to noise, but that's better than the no signal to noise you would have had without dithering.
What in the world does "molten core" have to do with "split off from Earth"?! The thermal time constant of the Earth is only a few million years -- the core isn't molten because the Earth is still cooling, it's molten because of the decay of radioactive nuclei, primarily uranium. The moon's thermal time constant would be even shorter, so if the core is still molten, it would have nothing to do with a violent creation.
Guess I can see why SETI gives out prizes for processing a buttload of data -- they sure as hell won't be giving any prizes for actually finding an ET civilization.
After claiming that it'll be the biggest balloon ever, they never give a size. Unless you count "400 times the size of a typical hot-air balloon and as tall as the Empire State Building; or seven times the height of Nelson's Column."
40 million cubic foot balloons are the biggest common size used at the National Scientific Balloon Facility in the US, and I believe they're about 130 meters tall when they reach altitude. I don't know how that compares to Nelson's "Column," as they so delicately put it, but that's probably smaller than the Empire State Building.
However, 40 km altitude is no record, the 40 millions can (and do) take a pretty hefty package to 43 km. I guess they're talking about a balloon carrying people. Why anybody would want to do that is beyond me.
I guess this article would give the impression that ballooning is the realm of crazies and crackpots, but high altitude ballooning is a very handy technology. Much science that is done from satellites can be done from balloons for a tiny fraction of the cost.
Much of what you say is true, but the reaction is wrong. "Reforming" means CH4 + 2 H2O in the presence of much heat and your favorite catalyst yields CO2 + 4 H2. You get out 4 H2's for each CH4, not 2. So, as you see, this is twice as efficient as you were thinking. Hence it's not much worse than burning methane, it's only just as bad as burning methane.
Resolution is not the biggest issue, making a good enough coronograph is. If a relatively nearby star had a Jupiter, Hubble has the resolution to see it. But the Jupiter would be about a billion times dimmer than the star, so you need to get the point spread function to drop by more than a billion in that little interval.
I confess I don't know much about SIM, but I do know that generally speaking, interferometers have great resolution and terrible tails on the point spread function.
Does the new camera really allow astronomers to take pretty pictures that they couldn't take before, or are they just using pretty pictures as a public relations gimmick?
Both. By far most of the science done with Hubble uses the spectroscopic capabilities of the instruments. But spectra don't make pretty pictures, and the newspapers only want pretty pictures. So what you see in the PR blowouts are all images.
As for false coloring, it's more than a cheap trick. Hubble images are usually taken in several filter bands -- again, to get spectral information. Since Hubble specializes in the non-visible wavelengths that don't make it through the atmosphere, there's a lot of info that can't really go in a true color image. Hence false color. The false color images are a handy visualization tool to help figure out what's going on. And of course, if you play around you can make them very pretty, and the newspapers will print them.
Steinhardt makes much of the "singularity" in the big bang theory, but in fact nobody understands the equations of state of matter past a certain extreme of pressure and temperature. So as you try to extrapolate towards earlier and earlier times, your understanding gets vaguer. See Weinberg's "The First Three Minutes" for a discussion of this. So this part doesn't disagree with the big band theory, Steinhardt just thinks he can fill in some new parts.
He also seems to think he has an alternate solution to the flatness problem. This is the puzzle that according to gravitational theory, the curvature of space could be anything, but observationally, the curvature is zero. Seems like an odd coincidence. Guth came up with the inflation theory to explain this -- Steinhardt has another theory.
So you're right, it's not contradictory to big bang theory. But it's not really part of it either.
HUNDREDS OF THOUSANDS!!! There are hundreds of thousands of suspected terrorists...
I'm surprised the number is that small. Looks to me like the govt thinks we have about 250 million possible terrorists in this country, who all need to be watched very closely.
Protect us?! We don't want our government to protect us! We want our government to go drop lots of bombs on some small, distant foreign country we never heard of before, and show it all on TV.
The problem is that the government has to waste several hours tracking down the judge to get the warrant signed.
The point is, that is not a waste of time -- it is an investment of time that pays off in freedom and justice for all of us. As the guy you're replying to already explained more eloquently than I can; so let me suggest you read his message a couple more times and see if you get it.
So if the FBI finds out you have met somebody they're investigating for a crime, you want them to have the right to search your house, without asking a judge for permission, just because you might possibly conceivably possess some evidence they could use against that person?
Too often people cast this debate in terms of whether we are for or against the police. The fact is, the police aren't doing their job if they don't do everything allowed by law that might help their investigations. I don't fault the FBI for taking advantage of this law -- I fault Congress for passing it, and the White House idiot for signing it. It's the job of these people to set the limits on the police in way that's consistent with American values, not Fascist police state values.
This article repeats what's often heard in the popular press, that the most common sources of hydrogen fuel are water and natural gas. You sure can get hydrogen from water, but if you do, it's not a source of energy -- at perfect efficiency it would take as much energy to get the hydrogen out of the water as you'll get back when you burn it. So hydrogen from water isn't an energy source, it's an energy storage mechanism. You still need to figure out where the energy is coming from.
As for natural gas, you can strip the hydrogen off, but you get one CO2 for every 4 H2's. You're ahead on energy, but you're still pulling carbon out of the ground and sticking it in the atmosphere, where you don't want it.
What we need is a closed-cycle fuel system. Something like grow tree, cut down tree, process tree into hydrogen and carbon dioxide, use hydrogen as fuel. This way, all the carbon and water you're releasing into the atmosphere is stuff the tree pulled out of it -- so the system is stable.
Christa McAuliffe was an English teacher, but now, she's history.
NASA was shooting for an educational experience, and I think everyone learned a valuable lesson: that when Reagan called the shuttle the "Space Truck" he was full of shit. It's a flying bomb. It's a safer flying bomb now than it was then, but it doesn't pay to trivialize the danger of flying in the thing.
On a more crass note, has anyone noted that there are 7 seats on the shuttle, and a flight runs about $500M, so this next teacher in space will cost the taxpayers about $70M. I hope we get something good for it.
Somebody at slashdot really really has a hardon for asteroids hitting the Earth. We've been averaging a story a month on this topic over the last year.
Titanium really is amazing stuff. We needed a part made, a cylinder about two feet long, 1.5 foot diameter, of 0.030 inch titanium. The shop cut a piece of sheet titanium and ran it through their rollers to bend it into a cylinder -- and it came out flat. So they set the rollers to a much tigher radius and ran it through again -- they said it was all they could do to turn the crank -- and it came out flat again. So they built a jig to hold it while they welded it. They had to attach a cheater bar 6 feet long so they could bend the sheet to get it into the jig.
Not to mention that stupid train in space thing we've had two articles on, and a seemingly endless supply of articles on asteroids that are that close to hitting the Earth.
You have *way* too much freaking time on your hands dude.
I'll second that. Bringing facts, reason, and for god's sake calculations to Slashdot is really in questionable taste.
Please stick to nerdy pseudoscientific bullshit from now on.
BTW, has anybody counted what fraction of the slashdot "science" section is stories about our imminent doom from asteroids hitting the Earth? Seems we never tire of this subject.
OK. When you make a centrifuge you have to put a counterweight on the opposite side, so you don't rip the bearing apart, so when they say 58 ft they mean diameter. Hence r = 29 ft = 8.8 m. Put this together with 15 rpm and you get 22 m/s^2 or about 2 g.
Glad I could help.
Of course you have to add this in quadrature with the Earth's grav, so you get more like 2.4 g.
Slashdot Mirror
Another similar technique is dithering. I guess computer graphics nerds are familiar with this, but it's handy to do to any signal that's about to get digitized -- add about half a bit of noise and you can pick up signals of less than one bit amplitude. Of course with poor signal to noise, but that's better than the no signal to noise you would have had without dithering.
What in the world does "molten core" have to do with "split off from Earth"?! The thermal time constant of the Earth is only a few million years -- the core isn't molten because the Earth is still cooling, it's molten because of the decay of radioactive nuclei, primarily uranium. The moon's thermal time constant would be even shorter, so if the core is still molten, it would have nothing to do with a violent creation.
I don't think I'll be filling in your holes -- I'm a married man -- but the unit you refer to is the "Smoot."
Guess I can see why SETI gives out prizes for processing a buttload of data -- they sure as hell won't be giving any prizes for actually finding an ET civilization.
40 million cubic foot balloons are the biggest common size used at the National Scientific Balloon Facility in the US, and I believe they're about 130 meters tall when they reach altitude. I don't know how that compares to Nelson's "Column," as they so delicately put it, but that's probably smaller than the Empire State Building.
However, 40 km altitude is no record, the 40 millions can (and do) take a pretty hefty package to 43 km. I guess they're talking about a balloon carrying people. Why anybody would want to do that is beyond me.
I guess this article would give the impression that ballooning is the realm of crazies and crackpots, but high altitude ballooning is a very handy technology. Much science that is done from satellites can be done from balloons for a tiny fraction of the cost.
But I haven't tried this, and I sure as hell ain't gonna.
Much of what you say is true, but the reaction is wrong. "Reforming" means CH4 + 2 H2O in the presence of much heat and your favorite catalyst yields CO2 + 4 H2. You get out 4 H2's for each CH4, not 2. So, as you see, this is twice as efficient as you were thinking. Hence it's not much worse than burning methane, it's only just as bad as burning methane.
I confess I don't know much about SIM, but I do know that generally speaking, interferometers have great resolution and terrible tails on the point spread function.
As for false coloring, it's more than a cheap trick. Hubble images are usually taken in several filter bands -- again, to get spectral information. Since Hubble specializes in the non-visible wavelengths that don't make it through the atmosphere, there's a lot of info that can't really go in a true color image. Hence false color. The false color images are a handy visualization tool to help figure out what's going on. And of course, if you play around you can make them very pretty, and the newspapers will print them.
He also seems to think he has an alternate solution to the flatness problem. This is the puzzle that according to gravitational theory, the curvature of space could be anything, but observationally, the curvature is zero. Seems like an odd coincidence. Guth came up with the inflation theory to explain this -- Steinhardt has another theory.
So you're right, it's not contradictory to big bang theory. But it's not really part of it either.
Protect us?! We don't want our government to protect us! We want our government to go drop lots of bombs on some small, distant foreign country we never heard of before, and show it all on TV.
So if the FBI finds out you have met somebody they're investigating for a crime, you want them to have the right to search your house, without asking a judge for permission, just because you might possibly conceivably possess some evidence they could use against that person?
Too often people cast this debate in terms of whether we are for or against the police. The fact is, the police aren't doing their job if they don't do everything allowed by law that might help their investigations. I don't fault the FBI for taking advantage of this law -- I fault Congress for passing it, and the White House idiot for signing it. It's the job of these people to set the limits on the police in way that's consistent with American values, not Fascist police state values.
As for natural gas, you can strip the hydrogen off, but you get one CO2 for every 4 H2's. You're ahead on energy, but you're still pulling carbon out of the ground and sticking it in the atmosphere, where you don't want it.
What we need is a closed-cycle fuel system. Something like grow tree, cut down tree, process tree into hydrogen and carbon dioxide, use hydrogen as fuel. This way, all the carbon and water you're releasing into the atmosphere is stuff the tree pulled out of it -- so the system is stable.
NASA was shooting for an educational experience, and I think everyone learned a valuable lesson: that when Reagan called the shuttle the "Space Truck" he was full of shit. It's a flying bomb. It's a safer flying bomb now than it was then, but it doesn't pay to trivialize the danger of flying in the thing.
On a more crass note, has anyone noted that there are 7 seats on the shuttle, and a flight runs about $500M, so this next teacher in space will cost the taxpayers about $70M. I hope we get something good for it.
Somebody at slashdot really really has a hardon for asteroids hitting the Earth. We've been averaging a story a month on this topic over the last year.
Titanium really is amazing stuff. We needed a part made, a cylinder about two feet long, 1.5 foot diameter, of 0.030 inch titanium. The shop cut a piece of sheet titanium and ran it through their rollers to bend it into a cylinder -- and it came out flat. So they set the rollers to a much tigher radius and ran it through again -- they said it was all they could do to turn the crank -- and it came out flat again. So they built a jig to hold it while they welded it. They had to attach a cheater bar 6 feet long so they could bend the sheet to get it into the jig.
(If you just count the ones that, you know, like, make it.)
Not to mention that stupid train in space thing we've had two articles on, and a seemingly endless supply of articles on asteroids that are that close to hitting the Earth.
Interesting web page about the genetic contribution to myopia here.
If he can even figure out which end of a soldering iron to pick up, he's way ahead of any theorist I ever met.
BTW, has anybody counted what fraction of the slashdot "science" section is stories about our imminent doom from asteroids hitting the Earth? Seems we never tire of this subject.
Glad I could help.
Of course you have to add this in quadrature with the Earth's grav, so you get more like 2.4 g.