Ok, first, you don't get shockwaves in nozzles- not unless you've got a rough nozzle surface, which is a bad idea, because the hot gas comes to a screaming halt ("stagnates") and the local temperature goes way up, and then the nozzle melts.
huh? There's a shockwave in the throat of the standard converging / diverging nozzel. It's where the gas is accelerated supersonic. The shockwave is at what's called the choke point.
You sir, are the one who's full of shit. There is always a shock where flow goes from subsonic to supersonic.
if the universe is infinite, and time is infinite, then,
Astronomers and physicists have very compelling evidence that both the universe and time are finite. Time had a beginning, and may have an end. The universe started as a point and has been expanding for a finite time, therefore it is finite... finite, but very, very big.
Now it is a big question how small the chance is that evolution could work... are we the only time it worked, or did life arise somewhere else in our solar system or other solar systems. Given that the universe is finite, if the probability is very small, then we will be alone in the universe (as the Bible tells us in Genesis).
These leads to the logical conclusion that if NASA ever finds irrefutable evidence of life on another planet, especially life more complex than bacteria... then NASA will be shut down immediately and all of its scientists will be blacklisted.
I'm not joking... I grew up in a place where public school teachers refused to teach evolution and taught a 6,000 year old Earth... in public school... in the 1980s. These people are dumb, angry, and well armed.
Amen! Until reporters can use anonymous sources responsibly, I say they have no right to a shield law. You have people like Rove saying bad things about opponents family anonymously not because he fears reprisals but because if such mud is attributed to an anonymous party insider it has more credibility than if it is attributed to Rove directly.
Let the DrunkenBatmans of the world have shield laws for their obsessive no-stone-unturned investigations , not the rumor mongering lazy reporters typical of most of the press.
"Yeah, I just carry it because I am supposed to, but I really haven't used it." ...or just buy everyone an iPod:) Then no funny excuses as to why you carry it around... and it's plausible to have one lost or stolen.
Dr. Brown had still hoped to hold back announcements of 2003 UB313 and another large Kuiper Belt object, 2005 FY9, until October, but his hand was tipped by Brian Marsden, director of the Minor Planet Center, who said that he was worried about hanky panky.
Dr. Marsden said that it was possible by looking on the Internet at the logs of one of the telescopes Dr. Brown's team had been using to find out where they had been pointed. He had evidence, he said, that someone had done that and computed crude orbits of the two unannounced planetoids, "presumably" in preparation for their own observations.
Since we've had leap seconds almost every year for over 20 years, I can safely assume that astronomers have methods to cope.
the last leap second was in 1999
In fact, as TFA says, they're the main scientific group opposing the obolition of leap seconds because it will fuck up their earth-based pointing systems, which tend to be huge, expensive and not easy to refit.
TFA is wrong. Some astronomers are for it, some are against it. And the telescopes can still be set to something like UTC (say UT1 for example) even if civil time stops using leap seconds. If their telescopes control software is hard coded to only use UTC, then they are idiots.
but you can't synchronize paper documentation. So you always run the risk that someone will grab a pre-leap second document of say geometry dependant events on a spacecraft and use it to say plan pointing for an observation... and then be one second off and miss the observation.
As for 'nobody uses a sextant' since we have good old GPS, tell that to the sailors not too many years ago who lost all nav equip and used hmm... a sextant. One NEVER abandons the ability to utilize alternate means of problem resolution.
Truth is a sextant doesn't really depend on time, it depends on an accurate prediction of the orientation of the Earth.
So instead of monkeying with clocks to make the incorrect assumption of a constant Earth rotation rate true... why not just use an accurate prediction of the Earth orientation as a function of time for celestial navigation and pointing telescopes and let the clock run at the constant rate needed for doing any calculations with physics.
If you use a system that cannot allow to have leap seconds, then should use your own relative time. Then you just need to keep a correspondance between your relative time and the more common time used by everyone else. No big deal.
and said correpsondance cannot be preidcted more that six months in advance when the elite timekeepers in France announce that they're resetting their clocks.
so if you print out any schedules in UTC (the time everyone else uses), those schedules are subject to arbitrary one second shifts no matter that you use a deterministic time system (like TDB) for your own calculations.
All physics runs on a clock without leap seconds. Relativity makes some clocks run at different rates, but that's a deterministic process that can be accounted for. UTC uses leap seconds because of an archaic desire to tie our clocks to the non-constant, non-deterministic rotation of the Earth.
UTC is not deterministic because we can't predict the rotation of the Earth (becuase it in part depends on things like the weather which we cannot predict to anywhere near the accuracy needed). So leap seconds are added willy-nilly whenever the Earth's rotation changes enough that UTC is 0.9 seconds fast or slow.
But physics needs a deterministic second that doesn't care about what time the Sun rises or sets! We should have a deterministic time system and track the Earth's rotation separately (with UT1) for those special applications that need a precise determination of the Earth's rotation.
Cival time should be the time physics uses... it should be God's time!
WHy would you need to guess when? surely the seconds are added at arbitrary points as required, but I can't imagine it is done with no warning.
6 months of warning... before that no one knows.
The industry I working does use highly complex systems where precise timing is critical. I can tell you from experience that you have to design for timing errors. They happen, not if but when.
That's a clock issue... I'm talking about a time system issue that makes schedules done in UTC subject to arbitrary 1 second shifts. This is nasty for things printed out on paper that cannot be autmatically updated via software.
Besides, assuming you've got a system that requires real-time function and accuracy to the second, why would you sync to outside time for anything but maintenance? Keep your timings relative to the system itself. Then you just need to worry about internal clocks...
There's lots of systems like that... but most of the world uses UTC. So you can do all of your internal scheduling in a system like ephemeris time that is deterministic, but eventually you have to schedule resources on the ground (like antenna time) and those schedules are UTC.
They are scheduled 6 months in advance... you cannot predict them before they are scheduled. They are based off of the Earth's rotation which won't be predictable until they can accurately predict the weather years in advance... i.e. not in my lifetime.
In addition to the weirdness of having second 60 in a minute, you get that added headache that leap seconds are non-deterministic... you can't predict ahead of time when they will happen. Imagine you make a very precise schedule in advance (e.g. scheduled events on a spacecraft) and then a leap second is announced and everything is then off by a second. Now you have all of these tables out there that are wrong that you have to find and then correct... a major headache when your working with something where precision in time is important (e.g. a spacecraft moving at 8 km/s).
Dr. Brown had still hoped to hold back announcements of 2003 UB313 and another large Kuiper Belt object, 2005 FY9, until October, but his hand was tipped by Brian Marsden, director of the Minor Planet Center, who said that he was worried about hanky panky.
Dr. Marsden said that it was possible by looking on the Internet at the logs of one of the telescopes Dr. Brown's team had been using to find out where they had been pointed. He had evidence, he said, that someone had done that and computed crude orbits of the two unannounced planetoids, "presumably" in preparation for their own observations.
Also, in the article it says the astronomers themselves have been calling it Xena.... don't think I like that name:(
I gotta say, since I bought my Mac with OS X, I'm much more comfortable in Linux/Shell enviroments. I'd be more likely to run Linux now than ever.
And with OS X on intel, people will have an Apples-to-Penguins way to compare Linux and OS X performance....And they'll probably find Linux is faster because of OS X's problems with 'funnels' and the BSD layer. It will be very interesting if this starts to drive more Linux adoption.
I'm also curious if someone will be able to hack a way to run the Aqua GUI atop the Linux kernel instead of Darwin.:)
In case of install, break Windows. In case of using IE, break Windows. In case of using Outlook Express, break windows. In case of buying a new graphics card, break windows. In case of using it for a couple months, break windows.
Heh.. the title of the article should have been: "Microsoft Continues Anti-OS Strategy"
Overall, this article is typical windows user complaining because they don't want to spend the time to learn a new platform. OS X has these features, it just takes time to learn them. Same thing if switching from Mac to Windows. Let's go down the list, shall we then...
1) Compatible control keys. OS X already does this... just look in system preferences for the keyboard and mouse pref pane.
2) Save button on toolbars This is an app specific criticism and has nothing to do with the OS. Office has these save buttons in the toolbar. in iTunes, iPhoto, etc. such a feature is not needed (everything is saved by default.)
3) A multi button mouse. see parent: Exactly. That's a hardware issue, not an operating system (OS X) issue. It's not OS X's fault that Apple ships computers with single-button mice.
4) Only show relevant file types in open and save dialogs conceded... I guess. I don't mind the OS X behavior here because I am in the habit of opening files via drag and drop from spotlight or the finder.
5) Sort folders to top of directory listings Finder's list view does this if you sort by the 'kind' column.
6) More context sensitive help conceded. OS X help system in general needs work. But last time I ran Winders it wasn't much better.
From article: Switching between Mac and Windows this drives me nuts. I have to consciously think "command-C or control-C?" It shouldn't have to be that way. And if you're running RDC or VPC and copying and pasting between OS X and Windows!! Sheesh!
If you really must do this, you can do it in 'system preferences'. Just go to the 'Keyboard & Mouse' pref pane and click the modifier keys button. voila! switch control and option or whatever else you want.
Slashdot Mirror
Ok, first, you don't get shockwaves in nozzles- not unless you've got a rough nozzle surface, which is a bad idea, because the hot gas comes to a screaming halt ("stagnates") and the local temperature goes way up, and then the nozzle melts.
huh? There's a shockwave in the throat of the standard converging / diverging nozzel. It's where the gas is accelerated supersonic. The shockwave is at what's called the choke point.
You sir, are the one who's full of shit. There is always a shock where flow goes from subsonic to supersonic.
if the universe is infinite, and time is infinite, then,
Astronomers and physicists have very compelling evidence that both the universe and time are finite. Time had a beginning, and may have an end. The universe started as a point and has been expanding for a finite time, therefore it is finite... finite, but very, very big.
Now it is a big question how small the chance is that evolution could work... are we the only time it worked, or did life arise somewhere else in our solar system or other solar systems. Given that the universe is finite, if the probability is very small, then we will be alone in the universe (as the Bible tells us in Genesis).
These leads to the logical conclusion that if NASA ever finds irrefutable evidence of life on another planet, especially life more complex than bacteria... then NASA will be shut down immediately and all of its scientists will be blacklisted.
I'm not joking... I grew up in a place where public school teachers refused to teach evolution and taught a 6,000 year old Earth... in public school... in the 1980s. These people are dumb, angry, and well armed.
The best thing is to ditch anonymous sources.
Amen! Until reporters can use anonymous sources responsibly, I say they have no right to a shield law. You have people like Rove saying bad things about opponents family anonymously not because he fears reprisals but because if such mud is attributed to an anonymous party insider it has more credibility than if it is attributed to Rove directly.
Let the DrunkenBatmans of the world have shield laws for their obsessive no-stone-unturned investigations , not the rumor mongering lazy reporters typical of most of the press.
"Yeah, I just carry it because I am supposed to, but I really haven't used it." ...or just buy everyone an iPod :) Then no funny excuses as to why you carry it around... and it's plausible to have one lost or stolen.
teach me not to preview my comments :)
l anet.html
http://www.nytimes.com/2005/07/29/science/29cnd-p
more from here: http://www.nytimes.com/2005/07/29/science/29cnd-pl anet.html
:)
Dr. Brown had still hoped to hold back announcements of 2003 UB313 and another large Kuiper Belt object, 2005 FY9, until October, but his hand was tipped by Brian Marsden, director of the Minor Planet Center, who said that he was worried about hanky panky.
Dr. Marsden said that it was possible by looking on the Internet at the logs of one of the telescopes Dr. Brown's team had been using to find out where they had been pointed. He had evidence, he said, that someone had done that and computed crude orbits of the two unannounced planetoids, "presumably" in preparation for their own observations.
perhaps we should call the planet P4w-N3d
Since we've had leap seconds almost every year for over 20 years, I can safely assume that astronomers have methods to cope.
the last leap second was in 1999
In fact, as TFA says, they're the main scientific group opposing the obolition of leap seconds because it will fuck up their earth-based pointing systems, which tend to be huge, expensive and not easy to refit.
TFA is wrong. Some astronomers are for it, some are against it. And the telescopes can still be set to something like UTC (say UT1 for example) even if civil time stops using leap seconds. If their telescopes control software is hard coded to only use UTC, then they are idiots.
but you can't synchronize paper documentation. So you always run the risk that someone will grab a pre-leap second document of say geometry dependant events on a spacecraft and use it to say plan pointing for an observation... and then be one second off and miss the observation.
As for 'nobody uses a sextant' since we have good old GPS, tell that to the sailors not too many years ago who lost all nav equip and used hmm... a sextant. One NEVER abandons the ability to utilize alternate means of problem resolution.
Truth is a sextant doesn't really depend on time, it depends on an accurate prediction of the orientation of the Earth.
So instead of monkeying with clocks to make the incorrect assumption of a constant Earth rotation rate true... why not just use an accurate prediction of the Earth orientation as a function of time for celestial navigation and pointing telescopes and let the clock run at the constant rate needed for doing any calculations with physics.
If you use a system that cannot allow to have leap seconds, then should use your own relative time. Then you just need to keep a correspondance between your relative time and the more common time used by everyone else.
No big deal.
and said correpsondance cannot be preidcted more that six months in advance when the elite timekeepers in France announce that they're resetting their clocks.
so if you print out any schedules in UTC (the time everyone else uses), those schedules are subject to arbitrary one second shifts no matter that you use a deterministic time system (like TDB) for your own calculations.
All physics runs on a clock without leap seconds. Relativity makes some clocks run at different rates, but that's a deterministic process that can be accounted for. UTC uses leap seconds because of an archaic desire to tie our clocks to the non-constant, non-deterministic rotation of the Earth.
UTC is not deterministic because we can't predict the rotation of the Earth (becuase it in part depends on things like the weather which we cannot predict to anywhere near the accuracy needed). So leap seconds are added willy-nilly whenever the Earth's rotation changes enough that UTC is 0.9 seconds fast or slow.
But physics needs a deterministic second that doesn't care about what time the Sun rises or sets! We should have a deterministic time system and track the Earth's rotation separately (with UT1) for those special applications that need a precise determination of the Earth's rotation.
Cival time should be the time physics uses... it should be God's time!
WHy would you need to guess when? surely the seconds are added at arbitrary points as required, but I can't imagine it is done with no warning.
6 months of warning... before that no one knows.
The industry I working does use highly complex systems where precise timing is critical. I can tell you from experience that you have to design for timing errors. They happen, not if but when.
That's a clock issue... I'm talking about a time system issue that makes schedules done in UTC subject to arbitrary 1 second shifts. This is nasty for things printed out on paper that cannot be autmatically updated via software.
Besides, assuming you've got a system that requires real-time function and accuracy to the second, why would you sync to outside time for anything but maintenance? Keep your timings relative to the system itself. Then you just need to worry about internal clocks...
There's lots of systems like that... but most of the world uses UTC. So you can do all of your internal scheduling in a system like ephemeris time that is deterministic, but eventually you have to schedule resources on the ground (like antenna time) and those schedules are UTC.
JPL uses ephemeris time for mission critical spacecraft operations.
JPL uses UTC. The DSN uses UTC. Only the navigators use ephemeris time because they need a deterministic system.
They're scheduled; they're deterministic.
They are scheduled 6 months in advance... you cannot predict them before they are scheduled. They are based off of the Earth's rotation which won't be predictable until they can accurately predict the weather years in advance... i.e. not in my lifetime.
They added that after I posted my comment :)
In addition to the weirdness of having second 60 in a minute, you get that added headache that leap seconds are non-deterministic... you can't predict ahead of time when they will happen. Imagine you make a very precise schedule in advance (e.g. scheduled events on a spacecraft) and then a leap second is announced and everything is then off by a second. Now you have all of these tables out there that are wrong that you have to find and then correct... a major headache when your working with something where precision in time is important (e.g. a spacecraft moving at 8 km/s).
This web page gives away their name:e x.html
http://www.gps.caltech.edu/~mbrown/planetlila/ind
Lila is the name of Dr. Brown's newborn daughter by the way...
from here: http://www.nytimes.com/2005/07/29/science/29cnd-pl anet.html
:(
I vote for 'p4wn3d' because....
Dr. Brown had still hoped to hold back announcements of 2003 UB313 and another large Kuiper Belt object, 2005 FY9, until October, but his hand was tipped by Brian Marsden, director of the Minor Planet Center, who said that he was worried about hanky panky.
Dr. Marsden said that it was possible by looking on the Internet at the logs of one of the telescopes Dr. Brown's team had been using to find out where they had been pointed. He had evidence, he said, that someone had done that and computed crude orbits of the two unannounced planetoids, "presumably" in preparation for their own observations.
Also, in the article it says the astronomers themselves have been calling it Xena.... don't think I like that name
how is this offtopic???
I gotta say, since I bought my Mac with OS X, I'm much more comfortable in Linux/Shell enviroments. I'd be more likely to run Linux now than ever.
...And they'll probably find Linux is faster because of OS X's problems with 'funnels' and the BSD layer. It will be very interesting if this starts to drive more Linux adoption.
:)
And with OS X on intel, people will have an Apples-to-Penguins way to compare Linux and OS X performance.
I'm also curious if someone will be able to hack a way to run the Aqua GUI atop the Linux kernel instead of Darwin.
The Yuri's Night people have made some nice PSA ads to pique children's interest in space:
S TIONS.mov
http://www.yurisnight.net/_multimedia/Reach.mpg
http://www.yurisnight.net/_multimedia/MARSPSA_QUE
In case of install, break Windows.
In case of using IE, break Windows.
In case of using Outlook Express, break windows.
In case of buying a new graphics card, break windows.
In case of using it for a couple months, break windows.
Heh.. the title of the article should have been: "Microsoft Continues Anti-OS Strategy"
Now if I could only map "caps lock" to delete, where God and the MIT Lisp Machines knew it should be.
you can swap control and caps lock: http://ella.slis.indiana.edu/~jfieber/osx/
Overall, this article is typical windows user complaining because they don't want to spend the time to learn a new platform. OS X has these features, it just takes time to learn them. Same thing if switching from Mac to Windows. Let's go down the list, shall we then...
1) Compatible control keys.
OS X already does this... just look in system preferences for the keyboard and mouse pref pane.
2) Save button on toolbars
This is an app specific criticism and has nothing to do with the OS. Office has these save buttons in the toolbar. in iTunes, iPhoto, etc. such a feature is not needed (everything is saved by default.)
3) A multi button mouse.
see parent: Exactly. That's a hardware issue, not an operating system (OS X) issue. It's not OS X's fault that Apple ships computers with single-button mice.
4) Only show relevant file types in open and save dialogs
conceded... I guess. I don't mind the OS X behavior here because I am in the habit of opening files via drag and drop from spotlight or the finder.
5) Sort folders to top of directory listings
Finder's list view does this if you sort by the 'kind' column.
6) More context sensitive help
conceded. OS X help system in general needs work. But last time I ran Winders it wasn't much better.
From article: Switching between Mac and Windows this drives me nuts. I have to consciously think "command-C or control-C?" It shouldn't have to be that way. And if you're running RDC or VPC and copying and pasting between OS X and Windows!! Sheesh!
If you really must do this, you can do it in 'system preferences'. Just go to the 'Keyboard & Mouse' pref pane and click the modifier keys button. voila! switch control and option or whatever else you want.