CHAOS THEORY... It does apply to everything, but the little bit that is applies to really big things like planets and their effect on a space craft is negligile.
There are places where the gravity from the Earth and the Sun pull on your spacecraft at almost the same amount (near Lagrange points) in these places small maneuvers can put you on vastly different trajectories... small actions have big effects... and this is where you can use chaos theory for trajectory design.
Pioneer and Voyager used much higher energy versions of the same thing. However, the theory behind the slingshot trajectories (patched conics) breaks down in low energy regimes. These guys worked out a theory to design trajectories in these low energy regimes and found some pretty cool stuff.
This is an extension to ideas that pre-date the "fuzzy boundary" techniques by about 100 years. The "fuzzy boundary" people just made up a new name for work that had been done before in hopes that they could patent it. Compare their stuff to Tisserand for example.
See this: http://www.space.com/news/space_routes_000726.html for more info about what these guys are trying.
And the "chaos theory" probably means that they just considered the stability of their trajectories. This is hardly very exciting. The problems of unstable trajectories should be known to any maths undergrad.
Yeah, but they found a way to make unstable trajectories go exactly where they want them to without using hardly any fuel. Before we just avoided unstable areas because we thought that being unstable was bad, now we can use instability to our advantage. That's the breakthrough.
It's kinda like figuring out how to get from LA to New York without using any gas by planning one big chain reaction car wreck.
The Slingshot effect (i.e. the Gravity-Assist) is for trajectories at much higher energies. The Interplanetary Superhighway method is useful at lower energies.
What will be cool is when we can tie the two methods together and use gravity-assists to get someplace quickly and then use lagrange points to move around after we get there... say to design a mission to orbit each of jupiter's moons one by one.
And near these lagrange points, a very small maneuver has a great big effect on a spacecraft trajectory. If you know what these small perturbations do you can design a trajectory that gets all the way to Jupiter using very small amounts of fuel.
There's a faster converging series given by Steffensen (in german): Steffensen, J.F.: 1957, 'On the Problem of Three Bodies in the Plane', Mat. Fys. Medd. Dansk. vid. Selskap. 31, No. 3.
Roger Brouke also gives a solution to the n-body problem using Steffensen's method (in english): Brouke, R.,: 1971, 'Solution of the N-Body Problem With Recurrent Power Series', Celestial Mechanics, No. 4, pp. 110-115.
Painleve proved that there were no more integrals of the motion in the 3+ body problem when the mass of bodies were free to change (e.g., with collisions). This means, in this case, that the method used to solve the two-body problem won't work for 3 or more bodies. These series methods don't require integrals of the motion and work just fine for the 3+ body problem.
Numerical integration usually uses methods similar to these series solutions, but numerical integration only provides a single solution for a specific initial condition. These series solutions are general and provide the solution for any initial condition.
put a checkbox in the installation process to install a system with maximum security options... stuff like no list of users on the login screen and no web server installed at all, etc.
I should clarify here... I mean give the guy administering a group of machines a simple little checkbox that doesn't even install Apache rather than just disabling it. This is so that a user with administrator password doesn't turn on the web server by clicking the "enable web sharing" box but has to do a little bit of extra work so as to ensure that the user really knows what they are doing.
And I'd like to be able to set a checkbox at instillation time that locks down all of the little things that you have to remember to lock down after the install, like disabling the list of the users on a system.
Perhaps, the best way to do this stuff is just have the sysadmins burn their own CD with their own custom OS X install.
Also, i'm not talking about security options for the average home user. I think Apple has great security for home users. I'm talking about stuff that you want for macs running at atomicsecrets.gov.
I should clarify... I don't mean that installers should access these directories and file without asking for the administrator password, I mean that installers shouldn't access these directories at all. 90% of OS X installers that ask for an admin password shouldn't be doing whatever they are doing that needs the admin password.
If there's a danger of regular user mucking up some critical config file or library why should so many installers be messing with these config files and libraries??
But why does IE need to change system-wide libraries?? It's just a web browser! There's no good reason for a web browser to mess with my system libraries. Just look at Omniweb, it plays nice.
Good OS X apps put everything in their own ".app" directory so you can install and uninstall the app easily.
You don't even need to be in the admin group to install software on OS X... You can create an "~/Applications" directory in your user directory and install software there. Well written apps function just as well from ~/Applications as/Applications.
yeah, but an organization might want to remove the web servers on their machines so that some user doesn't set up a web server or some other service and create a possible security hole.
I guess this wouldn't be a problem if users could get by without administrator access, but Mac vendors don't seem to understand that software installs should rarely require admin password. Why does internet explorer require an administrator password to install?
OS X has good security, but it has lots of room for improvement. It needs:
longer than 8 character passwords
checking for good passwords, password expiration, etc.
let the user turn off the option where you can login with "John Doe" instead of your username
let the user turn off the 'helpful' feature that puts the last user's name on the login screen
put a checkbox in the installation process to install a system with maximum security options... stuff like no list of users on the login screen and no web server installed at all, etc.
Alright, let's analyse this. Congress can't prohibit the free exercise thereof. Hmmm... Where does the first amendment prohibit people from saying the word, "God?" I don't see it in there, anywhere. In fact, it says they CAN'T stop you from saying "Under God." (In "abridging the freedom of speech," eh.)
Nothing in the court ruling restricts the right to say "under god".
UNDER GOD - UNDER GOD
See... no one is stoning me. The ruling says that the government cannot force little children to say "under god"
If MS makes sure every pre-Palladium windows is buggy and full of security holes, then users will have to upgrade to get a usable system. The shear entropy of all of the viruses out there will make any old version of windows unusable after MS drops support.
Is there any local where everything from 13 to 52 is full?
In metro LA there's: 13, 17, 18, 22, 24, 28, 30, 34, 38, 40, 50, 52, 56, 57, 58, and 62. And yes, I can pick up all of them. (Most of them aren't in English though).
So I guess 56, 57, 58, and 62 could find open slots between 13 and 52, but then there might be a conflict with some UHF stations in San Diego, San Bernadino, Orange County, Ventura, Lancaster, Santa Barbara, or Bakersfield where reception areas overlap on the edge of the city, or when weird weather makes a station broadcast further than normal. Plus, when stations are close together on the dial they can interfere (as I've noticed with 17 and 18).
Quoting from Barker's The Elements of Logic: "One well known type of tautology has the form 'P v -P'. This is sometimes called the 'law of the excluded middle', because it reflects the fact that any given sentence must be either true or false, there being no third alternative."(Barker, p. 91, 5th ed.)
Silly logician, the third alternative is "Mu", being the unknownable, or no-thing. The Classic example of this is the first Koan of the "Gateless Gate": Q:"Does a Dog have a Buddha nature?" A:"Mu".
Binary logic (i.e. where all statements are either true or false) is useful in some situations. However, ternary logic which adds "Mu" is very useful in experimental science where very often quantities cannot be measured. And when I say something can be measured I don't just mean quantum physics, all experiments have a set of both observable and unobservable quantities.
Warning: The Open Firmware Password can be reset and changed by any one of the following:
1. By any Admin user, as designated in the users pane of System Preferences (or in Server Admin). 2. Via physical access to the inside of the computer. 3. When the computer is started up in Mac OS 9.
No computer is secure if you have physical access to the computer.
yup, in general relativity zero G really is zero gravity... on very small scales.
Unfortunately part of the spacestation is closer to the Earth and another part is further away. This means that there will be small accelerations due to gravity pretty much everywhere in the station. Only the center of mass of the station is really at zero gravity.
What a typical Mac zealot responce: "there's no problem with the gilded Mac OS, rather a problem with the user."
Hey I like OS X a bunch, but I don't think it is the end-all be-all of operating systems -- how absurd!
IMHO, even if you did explain it, most Mac users wouldn't like it. I'm sending my son this web page; here's the web page window and here's the email window. They're both sitting right there on the screen, why on Earth would you want to go through all that rigamarole to hide the windows you're working on? Or to hide the entire *desktop*, yet? Why try to hide what you're working on? That makes no sense
You don't hide windows that you're working on... you hide the ones that you're not working on to get them out of the way. Mulitple desktops are a way to organize the windows of several related programs together so that you can hide or unhide them as a group. When you're using many different apps together to do a task this is very useful.
OS X is a professional grade OS and can be used to do real work (be it programming, video editing, document creation, or whatever). Multiple desktops or something that provides similar functionality would be a nice addition to OS X... and if you don't need this feature, you don't have to us it.
Slashdot Mirror
CHAOS THEORY... It does apply to everything, but the little bit that is applies to really big things like planets and their effect on a space craft is negligile.
There are places where the gravity from the Earth and the Sun pull on your spacecraft at almost the same amount (near Lagrange points) in these places small maneuvers can put you on vastly different trajectories... small actions have big effects... and this is where you can use chaos theory for trajectory design.
Pioneer and Voyager used much higher energy versions of the same thing. However, the theory behind the slingshot trajectories (patched conics) breaks down in low energy regimes. These guys worked out a theory to design trajectories in these low energy regimes and found some pretty cool stuff.
"Artist's concept of interplanetary superhighway", apparently not reviewed by any knowlegeable person.
Actually the picture is a pretty accurate representation of six-dimensional phase space, as far as representations of six-dimensional phase space go.
This is an extension to ideas that pre-date the "fuzzy boundary" techniques by about 100 years. The "fuzzy boundary" people just made up a new name for work that had been done before in hopes that they could patent it. Compare their stuff to Tisserand for example.
l
See this: http://www.space.com/news/space_routes_000726.htm
for more info about what these guys are trying.
And the "chaos theory" probably means that they just considered the stability of their trajectories. This is hardly very exciting. The problems of unstable trajectories should be known to any maths undergrad.
Yeah, but they found a way to make unstable trajectories go exactly where they want them to without using hardly any fuel. Before we just avoided unstable areas because we thought that being unstable was bad, now we can use instability to our advantage. That's the breakthrough.
It's kinda like figuring out how to get from LA to New York without using any gas by planning one big chain reaction car wreck.
The Slingshot effect (i.e. the Gravity-Assist) is for trajectories at much higher energies. The Interplanetary Superhighway method is useful at lower energies.
What will be cool is when we can tie the two methods together and use gravity-assists to get someplace quickly and then use lagrange points to move around after we get there... say to design a mission to orbit each of jupiter's moons one by one.
And near these lagrange points, a very small maneuver has a great big effect on a spacecraft trajectory. If you know what these small perturbations do you can design a trajectory that gets all the way to Jupiter using very small amounts of fuel.
There's a faster converging series given by Steffensen (in german):
Steffensen, J.F.: 1957, 'On the Problem of Three Bodies in the Plane', Mat. Fys. Medd. Dansk. vid. Selskap. 31, No. 3.
Roger Brouke also gives a solution to the n-body problem using Steffensen's method (in english):
Brouke, R.,: 1971, 'Solution of the N-Body Problem With Recurrent Power Series', Celestial Mechanics, No. 4, pp. 110-115.
Painleve proved that there were no more integrals of the motion in the 3+ body problem when the mass of bodies were free to change (e.g., with collisions). This means, in this case, that the method used to solve the two-body problem won't work for 3 or more bodies. These series methods don't require integrals of the motion and work just fine for the 3+ body problem.
Numerical integration usually uses methods similar to these series solutions, but numerical integration only provides a single solution for a specific initial condition. These series solutions are general and provide the solution for any initial condition.
And you can mount encrypted and unencrypted disk images remotely via a url... cool dat
put a checkbox in the installation process to install a system with maximum security options... stuff like no list of users on the login screen and no web server installed at all, etc.
I should clarify here... I mean give the guy administering a group of machines a simple little checkbox that doesn't even install Apache rather than just disabling it. This is so that a user with administrator password doesn't turn on the web server by clicking the "enable web sharing" box but has to do a little bit of extra work so as to ensure that the user really knows what they are doing.
And I'd like to be able to set a checkbox at instillation time that locks down all of the little things that you have to remember to lock down after the install, like disabling the list of the users on a system.
Perhaps, the best way to do this stuff is just have the sysadmins burn their own CD with their own custom OS X install.
Also, i'm not talking about security options for the average home user. I think Apple has great security for home users. I'm talking about stuff that you want for macs running at atomicsecrets.gov.
I should clarify... I don't mean that installers should access these directories and file without asking for the administrator password, I mean that installers shouldn't access these directories at all. 90% of OS X installers that ask for an admin password shouldn't be doing whatever they are doing that needs the admin password.
If there's a danger of regular user mucking up some critical config file or library why should so many installers be messing with these config files and libraries??
But why does IE need to change system-wide libraries?? It's just a web browser! There's no good reason for a web browser to mess with my system libraries. Just look at Omniweb, it plays nice.
/Applications.
Good OS X apps put everything in their own ".app" directory so you can install and uninstall the app easily.
You don't even need to be in the admin group to install software on OS X... You can create an "~/Applications" directory in your user directory and install software there. Well written apps function just as well from ~/Applications as
yeah, but an organization might want to remove the web servers on their machines so that some user doesn't set up a web server or some other service and create a possible security hole.
I guess this wouldn't be a problem if users could get by without administrator access, but Mac vendors don't seem to understand that software installs should rarely require admin password. Why does internet explorer require an administrator password to install?
- longer than 8 character passwords
- checking for good passwords, password expiration, etc.
- let the user turn off the option where you can login with "John Doe" instead of your username
- let the user turn off the 'helpful' feature that puts the last user's name on the login screen
- put a checkbox in the installation process to install a system with maximum security options... stuff like no list of users on the login screen and no web server installed at all, etc.
Just a few ideas..."The next thing you know it will be illegial or unlawful to utter the word 'God' in public"
"Jehovah!, Jehovah!, Jehovah!"
Alright, let's analyse this. Congress can't prohibit the free exercise thereof. Hmmm... Where does the first amendment prohibit people from saying the word, "God?" I don't see it in there, anywhere. In fact, it says they CAN'T stop you from saying "Under God." (In "abridging the freedom of speech," eh.)
Nothing in the court ruling restricts the right to say "under god".
UNDER GOD - UNDER GOD
See... no one is stoning me. The ruling says that the government cannot force little children to say "under god"
Read the many articles.
If MS makes sure every pre-Palladium windows is buggy and full of security holes, then users will have to upgrade to get a usable system. The shear entropy of all of the viruses out there will make any old version of windows unusable after MS drops support.
It sounds like Microsoft is spending a lot of money just to incorporate something like Sherlock into the operating system.
In LA we have 16... I'm teaching myself Spanish, Korean, Japanese, Chinese, Armenian, and what I think might be Thai.
Is there any local where everything from 13 to 52 is full?
In metro LA there's: 13, 17, 18, 22, 24, 28, 30, 34, 38, 40, 50, 52, 56, 57, 58, and 62. And yes, I can pick up all of them. (Most of them aren't in English though).
So I guess 56, 57, 58, and 62 could find open slots between 13 and 52, but then there might be a conflict with some UHF stations in San Diego, San Bernadino, Orange County, Ventura, Lancaster, Santa Barbara, or Bakersfield where reception areas overlap on the edge of the city, or when weird weather makes a station broadcast further than normal. Plus, when stations are close together on the dial they can interfere (as I've noticed with 17 and 18).
Quoting from Barker's The Elements of Logic: "One well known type of tautology has the form 'P v -P'. This is sometimes called the 'law of the excluded middle', because it reflects the fact that any given sentence must be either true or false, there being no third alternative."(Barker, p. 91, 5th ed.)
Silly logician, the third alternative is "Mu", being the unknownable, or no-thing. The Classic example of this is the first Koan of the "Gateless Gate": Q:"Does a Dog have a Buddha nature?" A:"Mu".
Binary logic (i.e. where all statements are either true or false) is useful in some situations. However, ternary logic which adds "Mu" is very useful in experimental science where very often quantities cannot be measured. And when I say something can be measured I don't just mean quantum physics, all experiments have a set of both observable and unobservable quantities.
In the article:
Warning: The Open Firmware Password can be reset and changed by any one of the following:
1. By any Admin user, as designated in the users pane of System Preferences (or in Server Admin).
2. Via physical access to the inside of the computer.
3. When the computer is started up in Mac OS 9.
No computer is secure if you have physical access to the computer.
yup, in general relativity zero G really is zero gravity... on very small scales.
Unfortunately part of the spacestation is closer to the Earth and another part is further away. This means that there will be small accelerations due to gravity pretty much everywhere in the station. Only the center of mass of the station is really at zero gravity.
yup, check out macslash.org
What a typical Mac zealot responce: "there's no problem with the gilded Mac OS, rather a problem with the user."
Hey I like OS X a bunch, but I don't think it is the end-all be-all of operating systems -- how absurd!
IMHO, even if you did explain it, most Mac users wouldn't like it. I'm sending my son this web page; here's the web page window and here's the email window. They're both sitting right there on the screen, why on Earth would you want to go through all that rigamarole to hide the windows you're working on? Or to hide the entire *desktop*, yet? Why try to hide what you're working on? That makes no sense
You don't hide windows that you're working on... you hide the ones that you're not working on to get them out of the way.
Mulitple desktops are a way to organize the windows of several related programs together so that you can hide or unhide them as a group. When you're using many different apps together to do a task this is very useful.
OS X is a professional grade OS and can be used to do real work (be it programming, video editing, document creation, or whatever). Multiple desktops or something that provides similar functionality would be a nice addition to OS X... and if you don't need this feature, you don't have to us it.