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A *healthy* human eye can resolve details approximately 1/3 of an arc minute across. At about 8" of distance, that works out to about 20 microns in size. The iPad3 has pixels that are about 80 microns in size.
[citation needed]
From all I've learned -- and I'm away from my primary sources at the moment, but here's a Wikipedia page that summarizes the issue -- a *perfect* human eye under *optimal* conditions can resolve details a maximum of 0.4 arcmin across. That corresponds to approximately 20/8 vision. The standard "normal vision" for a "healthy eye" is 20/20, corresponding to the traditional 1-arcmin resolution. And, again, that's under optimal conditions of distance and lighting -- if you're in normal indoor lighting, or in a twilight or night setting, you'll have trouble doing even that well.
Now, there are other issues, like vernier acuity, that mean resolution beyond these limits can matter. But in that realm, you can use antialiasing and other perception-informed techniques to get around the issue.
In practice, 80 microns at 12 inches is a perfect match for normal visual perception. If your vision is much sharper than this, congratulations; enjoy it while you can. (Presbyopia strikes even the sharpest-eyed of us in the end.)
Actually, it's about as different from driving as you can get. Stop for just one traffic light between here and Pluto, and see what it does to your mission profile.
You mean all I have to do is get my grandparents to spend more time punching digits on the phone?
Spelling snark aside, I'd love to see support for this claim (ketones improve Alzheimer's symptoms) from any source that isn't trying to sell us coconut oil.
And reading my question would've been faster than typing your reply.
At the risk of getting banned from Slashdot, I actually did follow the summary's link before I asked the question. I saw two alternatives, a "coming soon" link to Amazon and a link to Lulu. I saw nothing about which path would return more money to the project. So, my question: which way of buying is better (for the project)?
Kudos to them for walking the walk and making this freely available. So, if we want to get a printed copy and support the effort, which purchase avenue sends the most money in the most useful direction?
I see your point, but I think your argument is a little bit like saying (circa 1990) "why would anybody shell out hundreds of dollars for an ink-jet printer, when for the same price you could get a really nice set of drafting tools? And you could choose whatever paper and ink you like, instead of producing a fuzzy mess that runs when you get a drop of water on it."
It's some "control-traffic" issue that you, the customer, really shouldn't have to think about. It's nothing to do with an application that routes voice traffic over a data connection, thereby disrupting the carrier's finely-crafted billing practices.
I'm pretty sure that, in general, balloons aren't strong enough to exert significant pressure on their contents. So, close enough, the gas inside the balloon is always at the same pressure as the gas outside. And if the gas inside has a lower molecular weight, it's always going to be less dense than the gas outside.
You could include a compressor to move some of the gas into a pressure vessel, but that would add SERIOUS weight, not to mention power requirements.
Wonder if you could use hydrogen as the lift gas, and reversibly adsorb it to control buoyancy?
And by "failing" or "not working" I presume you mean "running for nearly two hours straight, including nearly half an hour at full design power".
NERVA worked. It could've put humans on Mars in the time that it took us to send the Shuttle program limping into LEO. The main "flawed concept" was the notion that the US had the political will to see it through.
My college roomate's father worked on the NERVA project back in the 60's. I don't know how he ever got over its ignominious cancellation. I'm not sure I ever would have managed it. I hope he's still alive to witness its rebirth.
Earth is moving at about 30 km/s relative to the Sun. That happens to be just the right velocity to keep it in an orbit at a distance of about 150 M km.
Apply thrust along that same vector, and you go into a higher orbit. Apply thrust against that same vector, and you go into a lower orbit. Apply enough thrust against your vector long enough -- long enough to change your velocity by about 30 km/s, which is a heck of a lot -- and you eventually intersect the Sun's surface.
"Let it fall slowly to the sun" is a bit like saying "just pick up both feet at the same time, and until you put them down, you're flying!"
Actually, the orangish color is there because the cheapest, most efficient lights are sodium-vapor, and that's what color they produce.
Before sodium-vapor lights became prevalent, the cheapest, most efficient lights were mercury-vapor, which emit bluish-white light.
It seems likely that white LED lights, which produce a blue spike and a broad red-through-yellow spectrum, will begin to replace both. Easier on the eyes, but worse for astronomers, as an earlier poster said.
Poor lighting, overgrown shrubs that impede the line of sight, tall buildings and allowing buildings to go into disrepair are all things which are linked to increased crime.
Please define "poor lighting". I would suggest that it includes:
Light wasted by being dumped up into the sky instead of directed toward the ground
Light that glares in the eyes, ruining night-vision adaptation
Light that casts deep shadows, where miscreants can hide
Yes, I'm sure the safest place to live would be one with no trees, no plants, nothing that would afford any privacy or break up the vistas of plain, flat-faced buildings and long, open streets. Me, I'd have no interest in living there.
First, let's skip the term "nutrients", which marketing and new-age blather have rendered meaningless for public discussion. This wouldn't consume vitamins and minerals. It would consume blood sugar or lipids, both of which average Americans have in great excess.
I've been calling for this (blood-sugar power for implanted devices) for decades. It's easy to point out how obvious this solution is, because I'm not in a field that gives me any insight into the actual technical problems.
If I had to power my computing and communication tools from my own body's stores of energy, I'd get to eat a lot more, and I'd probably still lose the spare tire.
...posting to remove a misapplied moderation. How about either (a) an undo option or (b) a moderation widget that's robust against bumped elbows, Slashdot?
As an OS X user, I'm painfully aware of this. But I've also run up against software that failed a default install on Windows because it couldn't cope with "Program Files". Really, people, how can you not test your own defaults?
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A *healthy* human eye can resolve details approximately 1/3 of an arc minute across. At about 8" of distance, that works out to about 20 microns in size. The iPad3 has pixels that are about 80 microns in size.
[citation needed]
From all I've learned -- and I'm away from my primary sources at the moment, but here's a Wikipedia page that summarizes the issue -- a *perfect* human eye under *optimal* conditions can resolve details a maximum of 0.4 arcmin across. That corresponds to approximately 20/8 vision. The standard "normal vision" for a "healthy eye" is 20/20, corresponding to the traditional 1-arcmin resolution. And, again, that's under optimal conditions of distance and lighting -- if you're in normal indoor lighting, or in a twilight or night setting, you'll have trouble doing even that well.
Now, there are other issues, like vernier acuity, that mean resolution beyond these limits can matter. But in that realm, you can use antialiasing and other perception-informed techniques to get around the issue.
In practice, 80 microns at 12 inches is a perfect match for normal visual perception. If your vision is much sharper than this, congratulations; enjoy it while you can. (Presbyopia strikes even the sharpest-eyed of us in the end.)
Actually, it's about as different from driving as you can get. Stop for just one traffic light between here and Pluto, and see what it does to your mission profile.
You mean all I have to do is get my grandparents to spend more time punching digits on the phone?
Spelling snark aside, I'd love to see support for this claim (ketones improve Alzheimer's symptoms) from any source that isn't trying to sell us coconut oil.
And reading my question would've been faster than typing your reply.
At the risk of getting banned from Slashdot, I actually did follow the summary's link before I asked the question. I saw two alternatives, a "coming soon" link to Amazon and a link to Lulu. I saw nothing about which path would return more money to the project. So, my question: which way of buying is better (for the project)?
Kudos to them for walking the walk and making this freely available. So, if we want to get a printed copy and support the effort, which purchase avenue sends the most money in the most useful direction?
Here's a good start:
Mindstorms Autofabrik
I see your point, but I think your argument is a little bit like saying (circa 1990) "why would anybody shell out hundreds of dollars for an ink-jet printer, when for the same price you could get a really nice set of drafting tools? And you could choose whatever paper and ink you like, instead of producing a fuzzy mess that runs when you get a drop of water on it."
It's some "control-traffic" issue that you, the customer, really shouldn't have to think about. It's nothing to do with an application that routes voice traffic over a data connection, thereby disrupting the carrier's finely-crafted billing practices.
You mispelled "porpoises".
Also "new".
I'm pretty sure that, in general, balloons aren't strong enough to exert significant pressure on their contents. So, close enough, the gas inside the balloon is always at the same pressure as the gas outside. And if the gas inside has a lower molecular weight, it's always going to be less dense than the gas outside.
You could include a compressor to move some of the gas into a pressure vessel, but that would add SERIOUS weight, not to mention power requirements.
Wonder if you could use hydrogen as the lift gas, and reversibly adsorb it to control buoyancy?
My bad, I dropped a stack frame somewhere.
You're talking about Orion, not NERVA. This fission-rocket proposal is the same approach as NERVA.
Oh, sure. "Nukes are too scary, so let's just goatse a big hole in space itself right next to an effectively unlimited reservoir of condensed matter."
And by "failing" or "not working" I presume you mean "running for nearly two hours straight, including nearly half an hour at full design power".
NERVA worked. It could've put humans on Mars in the time that it took us to send the Shuttle program limping into LEO. The main "flawed concept" was the notion that the US had the political will to see it through.
My college roomate's father worked on the NERVA project back in the 60's. I don't know how he ever got over its ignominious cancellation. I'm not sure I ever would have managed it. I hope he's still alive to witness its rebirth.
I don't think you understand how "falling" works.
Earth is moving at about 30 km/s relative to the Sun. That happens to be just the right velocity to keep it in an orbit at a distance of about 150 M km.
Apply thrust along that same vector, and you go into a higher orbit. Apply thrust against that same vector, and you go into a lower orbit. Apply enough thrust against your vector long enough -- long enough to change your velocity by about 30 km/s, which is a heck of a lot -- and you eventually intersect the Sun's surface.
"Let it fall slowly to the sun" is a bit like saying "just pick up both feet at the same time, and until you put them down, you're flying!"
Actually, the orangish color is there because the cheapest, most efficient lights are sodium-vapor, and that's what color they produce.
Before sodium-vapor lights became prevalent, the cheapest, most efficient lights were mercury-vapor, which emit bluish-white light.
It seems likely that white LED lights, which produce a blue spike and a broad red-through-yellow spectrum, will begin to replace both. Easier on the eyes, but worse for astronomers, as an earlier poster said.
Poor lighting, overgrown shrubs that impede the line of sight, tall buildings and allowing buildings to go into disrepair are all things which are linked to increased crime.
Please define "poor lighting". I would suggest that it includes:
Yes, I'm sure the safest place to live would be one with no trees, no plants, nothing that would afford any privacy or break up the vistas of plain, flat-faced buildings and long, open streets. Me, I'd have no interest in living there.
So, how is this going to detect anything other than Brownian noise?
In some ways he was a bitter old prick whose lasting legacy in my eyes is that I STILL don't have Macromedia Flash on my i-device.
Okay, that's deserving of +5 Funny.
Except that powdered metal can be used to produce incendiaries and explosives, and so Homeland Security will step right in to save us.
First, let's skip the term "nutrients", which marketing and new-age blather have rendered meaningless for public discussion. This wouldn't consume vitamins and minerals. It would consume blood sugar or lipids, both of which average Americans have in great excess.
I've been calling for this (blood-sugar power for implanted devices) for decades. It's easy to point out how obvious this solution is, because I'm not in a field that gives me any insight into the actual technical problems.
If I had to power my computing and communication tools from my own body's stores of energy, I'd get to eat a lot more, and I'd probably still lose the spare tire.
...where you can't see a thing because of all the light pollution.
...posting to remove a misapplied moderation. How about either (a) an undo option or (b) a moderation widget that's robust against bumped elbows, Slashdot?
As an OS X user, I'm painfully aware of this. But I've also run up against software that failed a default install on Windows because it couldn't cope with "Program Files". Really, people, how can you not test your own defaults?