Slashdot Mirror

From their FAQ:

"kwah-o-wahr"

Here is a link to the Quaoar FAQ, maintained by Chad Truijillo, one of the planet's co-discoverers. There's a lot of cool stuff there, including the discovery images (animated so you can see it moving across the star field), the Hubble images, information about the orbit, etc.

So the first reason for "plan first, then code" is that coding is expensive. That expense represents a risk if you're pursuing an approach that doesn't work out. Throwing away a plan is quicker and less expensive.

The second reason for "plan first, then code" is that a written plan is a clear expression of the ideas in the plan. Code is often not very readable or very obvious, and a large body of code may require weeks or months of study to get all the nuances at work.

There is a hidden disadvantage to "plan first, then code". Remember that we're trying to manage the risk of choosing a dead-end approach, so we want to minimize the investment before the discovery that the approach is bogus. A non-executable plan won't catch all the design bugs. It will only catch the design bugs that you can recognize on inspection of a written plan; the screening process is limited by your own human cognitive faculties.

What if we could write an executable plan, in a language that is clear and expressive, and in which writing the plan is inexpensive? This would be the best of all possible worlds! Luckily you're not the first person to face a daunting software design challenge, and people have been designing languages for exactly these constraints for many years (Python, Perl, Scheme, Ruby, Smalltalk, and others. These languages vary in the expressiveness of their syntax. If you're concerned about the mental expense of coding, you probably will want to avoid Perl (which looks a lot like C) and Scheme (which requires a mental paradigm shift). My off-the-cuff recommendation among these would be Python.

Why not write your final product in one of these easy, inexpensive, readable, expressive languages? Alas, many of them don't have the performance of C or C++. If you're doing something computation-intensive, that matters. But wait! There is another saving grace, called SWIG, a program that lets you glue small bits of C or C++ code into your larger program written in one of the easy languages.

In most computer programs, the performance is gated by a small number of small pieces of the code. Usually, the majority of the code does not have a big impact on performance. If you can identify those small performance-expensive bits, and translate them to C or C++ and glue them back into your program, you get the speed you want, and 95% of your code is still readable and expressive, and easy to change later. The trick to finding these performance-limiting bits is called profiling (see 1, 2, 3).

So here's the advice (assuming Python):
1. Spend a day learning Python, two days if you're busy. Python has lots of great libraries, skim the list of libraries as somebody may have contributed something you'll need.
2. Write your entire program readably in Python. Don't worry about speed yet. Rewrite as required until you're sure you've got a good design.
3. Use profiling to locate the few small pieces that slow down your program.
4. Use SWIG and C/C++ to rewrite those pieces and connect them back into your program.

Remember the Denver airport opening delays because of the baggage system bugs?

The Earth goes through periods where ice ages happen, and other periods where they don't. For the last 4 million years we have had regular ice ages. Before that the last previous period with ice ages was 350-250 million years ago. (The dinosaurs lived from 225-65 million years ago.) According to this there are 2 more such periods known in the last billion years. The first of which ended before the Cambrian explosion differentiated most of the major phyla that we still see today.

There is evidence of ice ages that are even older than those. For instance look at this one when the Earth was less than half its current age!

Terry Hancock has some ideas for doing just that, and recently started the spacelift/Narya project to try to get it going - not very active recently though...

Experiment #3, Millikan's oil drop, is widely regarded as the most famous example of cooking data in scientific history. This analysis by David Goodstein gives compelling evidence to the contrary. It in Goodstein claims that some of Millikan's unused data was the most supportive of his theory, and that even if he had used all the data he had gathered, it would not have made his results any less compelling.

(It seems Millikan had many other strikes against him. The question of fraud is brought up on page 3.)

This webpage from Cal Tech shows various relevant calculations of Van Allen radiation that suggest the dosage during the 1.5 hours of passage of the belts would be about 2 rem, about 100x less than an often-fatal dose.

--LP

Some Caltech CS courses
are already on-line including CS294,
by Professor DeHon, formerly of MIT & Berkeley.

If he's anything like this Q, he'd just stop time, arrest the criminals, put them on trial for the crimes of humanity, and be done with it.

I believe the issue is more complicated than you think. I refer you to a paper by David Goodstein that details the Millikan "controversy" and gives a little perspective.

Whoops, should be there now...

I wrote something to generate pictures based on iterative choices from mutations of a blank image. Thing is, I had my head up my ass when it came to java at the time, and have not gone back to fix it at all. Y'all can feel free to check out the source and improve the hell out of it...

I wrote something to generate pictures based on iterative choices from mutations of a blank image. Thing is, I had my head up my ass when it came to java at the time, and have not gone back to fix it at all. Y'all can feel free to check out the source and improve the hell out of it...

Milliken guessed or decided beforehand what he wanted the electrostatic constant to be and kept fudging his results until he got the one he wanted.

This is an unduly harsh analysis of Millikan's result and publication. There is no evidence to indicate that Millikan had guessed what he wanted, and then chose to the data to fit that. I suggest that you check out an article in The American Scientist (available freely in a posting by David Goodstein (Caltech)).

To briefly summarize that American Scientist article, Millikan had very exacting standards for the data that he would publish. If the oil drops were too small, too much effected by Brownian motion, or affected by innaccuracy in Stoke's Law (which he documented completely), the results were not published. If the drops fell to quickly for accurate measurement, the results were not published. So a marking like "error high, will not use" probably meant that he could not be certain of the numbers that he recorded. Likewise, even drops that were labeled "the best one I ever had" were not published. Even if the results of all his observations were taken into account, and not just the observations he published, his end result would have not changed significantly.

In short, to say that Millikan "guessed the answer" is at the very least unfair. He chose data that he was confidant had been recorded in a reliable fashion. You might fault him for other things, but not for choosing an answer before hand and then picking experimental results to support that.

The case has been rather overstated. David Goodstein, a current professor of physics at Caltech, wrote an article on this subject (warning: PDF). The relevant portion starts on page 3 - in summary, the data points that were discarded were being used to verify a separate formula for Stokes' law. A more recent analysis of all the points, published and not, doesn't show a bias regarding the charge value.

Unrelated but perhaps relevant, Goodstein also has an article titled Conduct and Misconduct in Science online.

The case has been rather overstated. David Goodstein, a current professor of physics at Caltech, wrote an article on this subject (warning: PDF). The relevant portion starts on page 3 - in summary, the data points that were discarded were being used to verify a separate formula for Stokes' law. A more recent analysis of all the points, published and not, doesn't show a bias regarding the charge value.

Unrelated but perhaps relevant, Goodstein also has an article titled Conduct and Misconduct in Science online.

Milliken guessed or decided beforehand what he wanted the electrostatic constant to be and kept fudging his results until he got the one he wanted.

Milliken guessed or decided beforehand what he wanted the electrostatic constant to be and kept fudging his results until he got the one he wanted.

It seems to me that open source would be the way to go, if only so any 'backdoors' or bugs can be found. 10 million stupid people or 5 million bored, smart people could really put our voting 'system' at risk.

This would also have the added benefit of removing the 'special interest' kickback that I'm sure the manufacturer/local politico is getting on some level.

Besides, what could be more patriotic (real patriotism, not bandwagon flags on your mailbox. ) than helping to create/debug a secure, fair, easy to use and accessible voting system? (Besides actually getting off your fat ass and voting. ;)

It seems to me that open source would be the way to go, if only so any 'backdoors' or bugs can be found. 10 million stupid people or 5 million bored, smart people could really put our voting 'system' at risk.

This would also have the added benefit of removing the 'special interest' kickback that I'm sure the manufacturer/local politico is getting on some level.

Besides, what could be more patriotic (real patriotism, not bandwagon flags on your mailbox. ) than helping to create/debug a secure, fair, easy to use and accessible voting system? (Besides actually getting off your fat ass and voting. ;)

Here is a 700+ page book similar in content to a freshman college text MotionMountain

This is a Classical Electrodynamic book at a graduate level Classical Electrodynamics-Bo Thide

A site for Statistical and Thermal Physics with some good notes by Harvey Gould Statistical and Thermal Physics (STP) Curriculum Development Project

Quantum Mechanics--Niels Walet-- see the "Big .ps file

Lecture Notes on General Relativity-- Sean M. Carroll

A list of books to look into Cease's Book List

A few authors I like are A.P. French, Halliday Resnick for intro, Griffiths

A very respectable Oxford Physics booklist can be found in their handbook here

Mostly he was inspired by The Killer Savages, a book about the Battle of Gettysburg. [See his scifi.com interview.]

I doubt he took much from OLS. He's probably never seen it. He's said in interviews that he doesn't watch TV (because he's to busy making it) [See here for the quote. (Bottom of the page.)]

It has also been suggested that he took from Farscape and Andromeda--two other shows he's never seen.

Some of the things ScroP cites above are pretty common, in both sci-fi and westerns.

Space as the wild west was the basis for Star Trek, OLS, Cowboy Bebop, and any other space opera that treats space as a frontier.

Outlaws vs. the Law is everything from Reservoir Dogs to Ali Baba to Han Solo. Space is just a change of venue.

Character's running from a tragedy in their past? Thousands of people traveling west after the Civil War. It's a basic human motivation to escape our traumas.

Genius Kid on a space ship? Wesley Crusher.
Space pilots with shady jobs? Han Solo again.

We're mostly talking about common archtypes.

Even shipping someone in a box isn't that new an idea. Star Trek did it in "The Emissary" and Bram Stoker shipped Dracula in a box of dirt.

It will be the details that will really display the strengths and differences between the two shows, and we won't see those until later this month.

The filter seems to block my school's main site, but not the CS Department's site. Any Ideas?

The filter seems to block my school's main site, but not the CS Department's site. Any Ideas?

The other issue is the population.

As Verner Vinge said: "The work that is truly productive is the domain of a steadily smaller and more elite fraction of humanity. In the coming of the Singularity, we are seeing the predictions of _true_ technological unemployment finally come true."

What are people (who still have a strongly ingrained work ethic) to do with their time when they're not able to do anything truly productive? Become and U.S. Prison guard? Corporate middle-manager? Paper-pushing civil servant?

Braaaaaziiiil... :-)

(I hope 'busy-work' isn't the future. I'd rather have the unemployed 'working' on enjoying their lives and entertaining others (for "free") until the Singularity arrives.)

--

Caltech students were also responsible for the famous box-stuffing (spamming, really) of a nationwide fast food chain (McDonalds, but I can't be certain) contest in which they took home a vast majority of the winnings by computer-printing their entries.

In addition, there's a very good review of successful and legal professional gambling by the technically savvy by another Caltech alumnus that was published in "Engineering and Science," a Caltech alumni publication. Get the PDF here or here.

Caltech students were also responsible for the famous box-stuffing (spamming, really) of a nationwide fast food chain (McDonalds, but I can't be certain) contest in which they took home a vast majority of the winnings by computer-printing their entries.

In addition, there's a very good review of successful and legal professional gambling by the technically savvy by another Caltech alumnus that was published in "Engineering and Science," a Caltech alumni publication. Get the PDF here or here.

So do Butterflies

Big deal.

I'll second the notion that the half-qwerty concept is very useful. It has a much more shallow learning curve than nearly any other "nonstandard" (meaning different from whatever you're already used to) keyboard layout, because it exploits your innate ability to think of your hands as mirror images of one another.

In addition to the hardware implementation for Palm and commercial software implementations for Windows and Mac (all available from the site which the parent poster mentioned), there is also a free implementation for Linux in the form of a kernel patch.

The OS's one foundation
is Linus Torvald's code;
She is his new creation
by semaphores bestrode.
In Finland Linus wrote her,
his macro-kernel core;
With GPL he gave her,
that we might pay no more.

Input from every nation,
yet one o'er all the earth;
Her message: revolution,
open source proves its worth!
No profit-mad excesses,
she charges us no fee,
And to this hope she presses,
that software will be free.

--to the tune of The Church's One Foundation
also here

Wasn't it Vernor Vinge who coined the term Singularity in relation to exponential technologic growth which overwhelms our ability to predict and comprehend?

His writings are suffused with it. It is a key theme in A Fire Upon the Deep and Marooned in Realtime. It also weighs heavily in the background of A Deepness in the Sky. All IMO are brilliant pieces of SF.

Here is what Vernor Vinge has to say about the singularity. Watch out, its a bit fatalistic.

http://www.ugcs.caltech.edu/~phoenix/vinge/vinge-s ing.html

It was in trying to imagine a world where this wouldn't happen that he created his "Zones of Thought" novels.

While the CNN article is truely hyped and mostly fluff there is an informative paper here.

In summary: If you find yourself in orbit around a Lagrange point you only need to change your velocity a little to change your orbit radically (thats the chaos part). The orbits you can enter in the Sun-Earth system is forming two horseshoes with the Earth placed in the gap (or perhaps more precisely: Like the figure 8 with the smallest of the loops folded within the larger one and the Earth placed in the cross between the loops). One of the orbits lies within earths orbit. The other lies outside of Earths orbit.

What makes this particular interesting is that the horseshoes of the Sun-Earth system overlaps the horseshoes of the Earth-Moon system. So, if you're travelling along one of the horseshoes in the Sun-Earth system, you can pull the trick again when you cross the horseshoe of the Earth-Moon system and enter an orbit around earth with virtually no fuel consumption. It works the other way around too: If you place a spaceship in one of the Lagrange points of the Earth-Moon system you can reach far into the solar system for almost free by entering the horseshoe of the Sun-Earth system at the right time. The only catch is that you're travelling pretty slow.

Now the CNN article talks a lot about interplanetian travel, but the reality is that the mechanics have only been worked out for the earth-moon-sun system and the Jovian system. Interplanetarian travel requires heavy computatios and is still in the works.

And to dispell some of the confusion in this thread about the nature of the Langrange points this page gives a good explanation.

Which makes sense for interstellar travel.

in interplanetary travel, these areas are probably constantly shifting, and so I wonder if the speed of shift is faster or slower than current space craft.

• Each planet and moon has five locations in space called Lagrange points, where one body's gravity balances another's. Spacecraft can orbit there while burning very little fuel. To find the Interplanetary Superhighway, Lo mapped all the possible flight paths among the Lagrange points, varying the distance the spacecraft would go and how fast or slow it would travel. Like threads twisted together to form a rope, the possible flight paths formed tubes in space. Lo plans to map out these tubes for the whole solar system.

In 1993 I was a graduate student in the Caltech asynchronous circuit design group. That year we had a prototype asynchronous microprocessor that implemented a subset of the MIPS instruction set.

The guys in the lab used to demo this by hooking up an oscilloscope to show the instruction rate. They would then get out a can of liquid nitrogen, and pour it on the CPU. The instruction rate would climb right up... This lead to many jokes about temporary cooling during heavy loads. "Hey, get the ice cubes... He's starting gcc!" :-)

I believe our group used a different basic latch design than Sutherland describes. We handled all bits asynchronously using three wires, one that went high for 0, one that went high for 1, and a feedback wire for "got it". His design looks like it could latch a bus of wires simultaneously. Forgive me if I'm wrong... it's been almost a decade.

One of the nice features of these chips is that they are tolerant of manufacturing errors. Often impurities in the silicon will change the resistance or capacitance of a long wire. In asynchronous designs, this just means operations that need that wire will be a little slower. In the synchronous world, either the whole chip fails or you have to underclock it.

A group of ex-Caltech graduate students started a company to sell these asynchronous processors. Details at Fulcrum Microsystems.

(For those at Caltech: Yes, that's me on the asynch VLSI people page. And yes, I wrote prlint. What an awful piece of software that was.)

You've hit the nail right on the head. Async circuits aren't harder to design; they're harder to verify and debug. Historically the tools just haven't been up to it and, despite some recent breakthroughs, I'm not sure they are now. Check out the work at CalTech, Manchester, and Theseus Logic for the current state of the art.

fry a diode, for example

How much more would it cost to build a 100m filled aperture in space? Lots more because launching to low earth orbit is very expensive, much more expensive than doing multi-conjugate adaptive optics from the ground.

Space does bring unique capabilities even in the adaptive optics era, since the atmosphere is opaque at many wavelengths. Hence the need for space-based X-ray, ultraviolet, and mid- and far-infrared telescopes. In this sense Hubble is an aberration (pun intended), in that its doing from orbit what can be done from the ground. But adaptive optics was nowhere near as developed when it was launched. The other benefit Hubble gets is low background, which makes it more sensitive, but when compared to a 100m telescope, that doesn't make a lot of difference.

Likely to be online before OWL is CELT - the CalTech Extremely Large Telescope.

And Hi from the ESO Guesthouse in Chile!

Just another manic monday

It's going to be pretty expensive to fix this upper case T.

I tried to post the script earlier, but /.'s filter didn't like it. Alas, a google link has solved my problem.

Try Google search or for Linux, this site

Here, please note, I just found this and I haven't tried it out yet.

GLUI, though. Yech. That's a crappy toolkit. You have to modify the guts of the thing to add new widgets, the architecture is a mess, and it has problems synchronizing the front and back buffers. GLOW is much better. I've used both. Both are menu and widget toolkits built entirely on top of OpenGL. This gives cross-platform portability. Doing 2D widgets through the 3D OpenGL engine seems inefficient, but it works well. If you have 3D hardware, you may as well use it. It's an relatively clean way to program.

No. It will penetrate a sheet of paper but probably be stopped by something such as your hand. I would be impressed if this setup will go 15 miles through a thunderstorm.

Will it be fixed-point (ie. you must be aimed directly at the antenna, making use of this with laptops/pdas/phones impossible.)

Not necessarily however the line-of-sight requirements would make roaming with omnidirectional antennas very disappointing.

75-90GHz means wavelengths between 4mm and 3.33mm. A quarter-wave antenna would be only 1mm long. You'd probably manufacture antennas for this by using phased dipole arrays on a printed circuit board [Warning: powerpoint link] (probably the same circuit board as the transceiver) aimed at a parabolic dish reflector.

It's also explored in the Star Trek TNG episode Second Chances.

Telescopes like the James Clerk Maxwell Telescope (JCMT) and the Caltech Submillimeter Observatory (CSO) have been using these THz waves to do astronomical research for about 15 years.

THz waves are in the millimeter/submillimeter regime of the electromagnetic spectrum, placing them between the far-infrared and the radio.

Just like we use infrared light to look at things which are at roughly room temperature, we use submillimeter light - with wavelengths about 10 times longer - to look at things which are about ten times cooler, down to a few tens of Kelvin above absolute zero.

This includes solar system bodies, comets, and clouds of interstellar gas and dust - the birthplaces of new stars. Just like in the articles, we can use submillimeter waves to see through things that entirely block visible (optical) light.

How about if you add an extra layer of indirection?

Instead of releasing a module proper, you release say, a single xml-document, which can be run by end-users through a translator which just happens (gasp!) to output IWD-compatible modules if properly fed.

Maybe there's an implicit 'anything that could possibly be made into a working module belongs to us'? :-\

Hmm.. maybe we'll get some reverse-engineering fun out of this after all :-)

Hehe, yeah, maybe that was going overboard. Didn't even notice. Guide for the uninitiated:

IWD = Icewind Dale
IWD2 = Icewind Dale 2
IE = Infinity Engine -- powers BG/BG:TotSC/PS:T/IWD/IWD:HoW/BG2/BG2:ToB and IWD2
NPC = Non-Player Character
NWN = Neverwinter Nights
DS = Dungeon Siege
TA = Total Annihilation
OP = Original Poster
TotSC = Tales of the Sword Coast. BG1 add-in adventures
PS:T = Planescape: Torment
ToB = Throne of Bhaal. BG2 expansion.
HoW = Heart of Winter. IWD add-in.