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"A Dyson sphere, much less a partial Dyson sphere with sporadic orbit makes no sense."
A whole Dyson sphere or Niven ring don't make sense, that much is for sure since they wouldn't be able to maintain a stable orbit around the star.

Wasn't there a game called Omega? I recall that from the late 80's

Omega 0.80 was probably the last version, and it's still available. Damn, I killed a lot of hours in that world. I should go back there, I probably still have some old save files floating around somewhere...

But they would still be stable even if they were solid.

No they wouldn't. The geometry in 2d doesn't cancel out the way it does in 3d.

I mean each narrow individual ring, not the whole disk of rings (that would not be stable since the inner rings would rotate faster than the outer rings).

This is not a problem. Ever seen a record player?

I get a tarball for some old project and get it to compile without warnings with g++. The task can take hours as I have to deal with old C programmers' hatred for const correctness, uberclever macros, use of variables called "class" and "new", reinvented containers, and general disregard for maintainer sanity. Approached with the right mindset this can become as entertaining as a video game, with frequent exclamations of "what kind of a moron would do this?!?"

I highly recommend Omega roguelike game for this purpose. In addition to all of the above mentioned qualities, it's got tons of entertaining content, being probably the best roguelike out there. It is relatively challenging to convert to an event-driven model suitable for a modern UI approach. And heck, it is just plain darn fun and easy to debug.

I was going to reply that Larry Niven's rings are unstable (pointed out by MIT students) and that therefore shells should be as well, but ... came across this instead: http://www.alcyone.com/max/writing/essays/why-niven-rings-are-unstable.html (Dyson spheres aren't dynamically unstable, rings are.)

ABRIDGE, v.t.
        To shorten.

                        When in the course of human events it becomes necessary for
                people to abridge their king, a decent respect for the opinions of
                mankind requires that they should declare the causes which impel
                them to the separation.
                                                                                                                      Oliver Cromwell

AUCTIONEER, n.
        The man who proclaims with a hammer that he has picked a pocket with his tongue.

PATRIOTISM, n.
        Combustible rubbish read to the torch of any one ambitious to illuminate his name.

        In Dr. Johnson's famous dictionary patriotism is defined as the last resort of a scoundrel. With all due respect to an enlightened but inferior lexicographer I beg to submit that it is the first.

Why science fiction, why not science fact? How about a book like "One, Two, Three... Infinity" by George Gamow? Or anything written by Martin Gardner? How about Innumeracy by John Allen Paulos? Or Max Born wrote a book, "Einstein's Theory of Relativity", which explains relativity in great detail with nothing more than pre-algebra. Or for the computer nerds, the obligatory recommendation is "Godel Escher Bach, an Eternal Golden Braid" by Douglas Hofstadter.

I have never understood the point of fiction, except as pure entertainment. Non-fiction is where the good stuff is. If it really has to be fiction, try Flatland by Edwin Abbott.

In case you haven't read it, Flatland (The first non-wiki link in google) is the tale of a square named (conveniently) A. Square living in his comfortable home in a two dimensional world, who is eventually visited by a sphere from a *third* dimension and is both vexed and eventually exhilarated (and then vexed again) by what he learns in terms of geometric and social implications.

It's a wonderful bit of British satire and more written by Edwin A. Abbott around 1884. Check it out - it's a wonderful short story, and a very nice example of the treasures that lie within the public domain.

Ryan Fenton

Indeed. As Ambrose Bierce said:
CORPORATION, n.
An ingenious device for obtaining individual profit without individual responsibility.

E. Abbot's Flatland

Don't forget about Sexy Losers (DNSFW)

Sorry, I'll always think of it as "The Thin H Line". But I agree, one of the best out there. Oddly, I consider the total NSFW-ness of it almost irrelevant to the humor, but not gratuitous fan-service (Hmm, that sounds like a contradiction, but I stand by it).

But since this seems to have devolved into a "my favorite webcomics" listing, I might as well plug my personal favorite...

Unicorn Jelly, by Jennifer Diane Reitz (You might recognize the name from the credits (design) of a number of EA, Epyx, Interplay, and other old-school games). The story has sadly finished, and you should only read this one from the beginning, but well worth a few hours of your life.

Initially about a rebellious young witch (think " LeGuin's Disposessed applied to Wicca" rather than Wendy or Sabrina), it evolves into a tale of rationality applied to a superstitious world facing an unavoidable cataclysm... With a hint of Abbott's "Flatland" thrown in for spice. One of its most fascinating points (to me, anyway) - Although you need suspension of disbelief to allow the strip's universe to exist in the first place, once you accept that, you won't find many points to nitpick about. The strip's world has distinctly different physical rules than our world, yet remains internally consistent to the point that the author has worked out actual laws of physics and entire ecosystems suited to those laws.

You damned Spacelanders--always trying to tell us there's more than 2 dimensions!

http://www.alcyone.com/max/lit/flatland/

There are only so many ways that an enemy can attack you in 2 dimensions. This effectively -limits- gameplay and -limits- creativity. It also breaks the metaphor for games trying to provide an immersive experience- why the hell didnt Shinobi, being the elite ninja that he is, ever take two steps to his left and avoid dying?

BOTEC is a simple astrophysical and orbital mechanics calculator, including a database of all named Solar System objects. BOTEC is intended as a simple but useful calculator to assist with making astrophysical, orbital mechanics, and space navigation calculations. As the origin of the acronym applies, BOTEC is more of a "back-of-the-envelope calculator" rather than an industrial-strength calculator, although this may change in the future.

BOTEC is primarily intended for people familiar with physics and Python, and as such is unlikely to be useful to the average enduser. BOTEC really consists of two parts: The BOTEC software, which knows what to do with the data, and the Solar System data itself, which is represented in a large data file (a Python pickle, actually). This is deliberately modularized so that the Solar System data BOTEC uses can be updated independently of software, and also that alternative data files (e.g., hypothetical stellar systems for fictional purposes) can be supported. All values are strictly in SI units.

Flatland (complete text) by Edwin A. Abbott
It's a work of fiction written in 1884 about a 3-dimensional being's visit to a 2-dimensional world. It blew my mind when I first read it in high school.

A couple of things. The reason that energy is not released when a virtual pair recombine is because that energy was already "borrowed" from the universe in order to create the pair. This is why they are called "virtual" -- they don't exist in a form that allows us to extract energy from them. The length of time a virtual pair can exist is controlled by the uncertainly principle and is thus inversely proportional to the energy of the pair:

Energy x Time = h /(2 pi)

Theoretically, if you can break the laws of physics as your device does then an infinite amount of energy would become available. The limit should be set by some physical limitation of your device. If you want to know more about background fluctuations google around for "casimir effect".

The idea of your device only allowing one sort of matter to be created might be very unappealing to physicists because you are breaking all sorts of conservation laws that are dear to their hearts. A more appealing device might be some sort of a trap for anti-matter. Remember that current atomic bombs don't destroy atoms, they just convert neutrons and protons from one grouping to another. The energy released is the difference in binding energy of the groupings. You would get much more bang for you buck if you were able to achieve total annihilation using anti-matter. But alas, this idea seems worn and hackneyed. Although there might be some interesting ideas to explore in the trap itself that holds the anti-matter.

If you really want to harness the vacuum fluctuations then I suggest using some sort of sub-sub-atomic mirrors that harness the casimir effect. The mirrors exist for a VERY short period of time, but they are so flat and so perfectly reflecting that they slam together at high speed due to the casimir effect. The mirrors should probably be made up out of strings in some configuration that is not found in nature. If fact, you would probably want to use 'branes instead of strings. This idea is probably just as ridiculous as the first but the details can be swept under a larger and perhaps more appealing rug.

The rules for creating black holes is most simply expressed in terms of escape velocity. A black hole is achieved when the escape velocity is greater than the speed of light.

1/2 mv^2 = GMm/r

v^2 = 2GM/r

On earth the escape velocity is about 11 km/s. The speed of light is roughly 300,000 km/s. So something with the mass of the earth would need to be roughly (300,000/11)^2 times smaller than the earth to form a black hole, roughly 1 cm across.

For evaporation, the follow page contains the simple formulas it sounds like you are looking for:
http://www.alcyone.com/max/writing/essays/black-ho le-evaporation.html

That reminded me of Flatland :)

That would be Edwin Abbot's Flatland.

For enlightenment, please read Flatland by Edwin A. Abbott. A very interesting way to conceptualize life in one, two and four-dimensional worlds.

Nothing - provided you live in Flatland...

Note: IANAP(hysicist)

From a thought experiment point of view, a teeny-tiny black hole would have an event horizon (the point of no return so to speak) with a vanishingly small radius, as subatomic particles come into contact with it, it eats those, then it eats more and more of them until it's eating atoms, then...and so on.
It is worth noting that black holes, being 0-dimensional points, have infinite density and would (absent an electromagnetic field of some kind) fall straight into the earth's core, and in our little thought experiment, eventually eat the earth from the inside out. However:

A bit of googling turns up the following link:

http://www.alcyone.com/max/writing/essays/black- ho le-evaporation.html

which shows that a black hole evaporates over an amount of time proportional to it's mass cubed. Let's assume they make a black hole that weighs 1kg, then

tau=c^2/(3*(3.563*10^32)) * (1kg)^3
tau=8.4198*10^(-17) seconds

which is not long enough to worry about by any means =)

Considering pretty much everybody's head is 3D (4D, too, if you think about it), I would be way more impressed if the company were run by a 2D head. :)

Let's suspend our disbelief for a second and forget that the limitation at the speed of light is due to energetic constraints and not simply to the appearance of shockwaves, as occurs at the speed of sound.

They say that Mach Number is analogous to Warp Factor. Mach 5 being like Warp 5 and therefore half of the Enterprise's rated limit of Warp 10.

Presumably they're studying the standing shockwave pattern around the vessel, looking at where the crests and valleys attach to the hull, nacelles, etc., to see if that causes improper loads (supersonic aircraft designers have to "tune" the positions of edges and control surfaces so that the standing shockwaves don't amplify drag, eliminate lift, induce vibrational feedback, etc). Which is a reasonable thing to do; they're checking whether the fictional vessel could be said to have been properly designed to handle the shockwaves encountered if light produces shockwaves (which it does when particles enter media with lower speed of light than the medium they came from; see http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe =UTF-8&safe=off&q=cerenkov+radiation&btnG=Google+S earch).

The only problem is, the Mach number is a simple multiple of the local speed of sound, while the Warp Factor is the square root of a multiple of the speed of light. So to find out what happens at Warp 5 they would have to study the analogous Mach 25 to get the correct results.

(removes pointy latex ears)

>No! They are not even close to being in the same galaxy as "more >correct". Within the context of the computer world,
>1K = 1024 or 2^10
>1M = 1048576 or 2^20
>1G = 1073741824 or 2^30
>1T = 1099511627776 or 2^40

Where have you been?

1KB = 1000 bytes
1MB = 1000000 bytes
1GB = 1000000000 bytes
1TB = 1000000000000 bytes

1KiB = 1024 bytes
1MiB = 1048576 bytes
1GiB = 1073741824 bytes
1TiB = 1099511627776 bytes

This "new" standard is from December 1998 (when it was adopted by the IEC).

Check here or here for reference.

Google for "SI binary prefix" for many more references if you care to.

Got the wife and kids in a truck, and we're gonna head to the hills for a while. Got meself a shotgun... just in case those Martians come for ME!

The problem is that the radiation pressure from a black hole decreases (and decreases rapidly) with mass. So, as more mass accretes, less radiation pressure exists and the rate of accretion accelerates. In principle, it might be possible to create a highly unstable equilibrium with a very low-mass black hole--but I suspect that such a system would tip over into either complete evaporation or rapid growth very, very quickly.

Here's a neat derivation relating evaporation time to mass. Radiation pressure varies as roughly 1/m^4. It's not gonna be stable--and you need a very small black hole (ie much less than a solar mass) to see any appreciable radiation at all.

Games with full-screen character graphics are called "roguelike", after the 1980's game "rogue". IMHO, they're much deeper than most modern so-called RPGs.

Some of my favorites are angband, mangband, slashem and omega.

For general information, try this or that.

There are many other translations of Beowulf available on the Web; see for instance here.

Larry Niven, author of the Ringworld books, among others is hardly obscure. He also coined the term flash crowd. Google, as always, turns up a wealth of information.

On a related note, due to the inherent instabilities of a ringworld, I would suggest looking for signs of jets (or other methods of in-space propulsion) around the peripherary of the disk. That should provide significant evidence as to whether it's really a ringworld, or "just" a belt of dust, as the article indicates.

Wrong. If you were a 2D being and a sphere assed through your plane you'd see a dot grow into a long "wall" or "line", disappearing into a dot again.

The book Flatland (available online in its entirity) covers all the nuances of the 2D lifestyle.

... too bad I don't really have a clue what it means. *sigh* I guess this is why I'm not majoring in Math ;-)


You should read Flatland. It's a fun beginners guide to other deminsions. It's a great story too.

Powers of Ten
Powersof10.com and Eames Office - Powers of Ten
Quarks to Quasars
`Powers of Ten' scales (additional links)
The book at Amazon, Barnes & Nobel.

Cosmic View: The Universe in 40 Jumps, by Kees Boeke (1957)
Cosmic View
Cosmic View (another version)

A Powers of Ten variant (my own)
How Big Are Things? (comments encouraged)
Scaling the universe to your desktop

Other PoT presentations of length
Length
Orders of magnitude - Distance
Scales of Measurement (ASCII version) from Niel Brandt's Timelines and Scales of Measurement Page

- Mitchell Charity

There are at least 2 games called Omega.

Here Omega is also the first roguelike game that
has a wilderness and several dungeons and not
a single dungeon.

Omega official distribution page

Does anyone remember a game called Omega as well?

Omega, the roguelike, is still floating around. Old versions can be had from the official distribution page. The game is still under on-again, off-again development by William Tanksley (the third person to helm its development). More recent builds of his work can be found over at Sourceforge.

Imagine reading Beowulf while listening to the hum from a cluster of these....

does this even have a word?

weel try this one:
http://www.alcyone.com/max/reference/physics/prefi xes.html

wouldn't that be exallion values?

But i think a better look at encryption will prove that more bytes is not better securty above a vertain point. (For DES i know this)

The print edition of this is one of my most treasured stymying weapons in drunken debate.

Hi,

I'm going to unabashedly karma whore for a second because Nethack is my favourite game ever. I can't tell you the number of hours I wasted playing this (or other rogue-like games, such as rogue, larn, adom, or omega).

Here are some links to get you all started:

Nethack.org

One of the first and best Nethack pages, from the legenday Boudewijn Waijers

another Nethack homepage

A newer Nethack page

QT Nethack

An impressive graphical Nethack

The google Roguelike directory entry

the classic rec.games.roguelike.nethack

Happy hacking!

Yeah, tell me this in a few billion years, when the sun dies, then I'll believe it's a renewable resource. ;)

No, not 3d; 2 and a half, perhaps. If i saw in 3d, i'd be able to see the back of something at the same time as the front.

Ehh? WTF? I think that'd be more akin to x-ray vision...or disconnected eyeballs.

3D translates to 3 Dimensional. The dimension in question are:

1. Length
2. Width
3. Depth
If you see 1D, you'd only see lines. 2D would be able to give you shapes, but no idea how deep the shape was. 3D gives you all of it. Check out Flatland for help...which you obviously need.

Actually, that's only 8.0 zebibytes, which is the SI binary prefix for 2**70.

9.4 Zettabytes is correct. Zetta is the decimal prefix.

*Beeep* Wrong.
There's something called "Planck units", which are not arbitrary at all.
For further reference, Take a look here, or try Google.

Such pictoral messages are unlikely to be very effective, if ever encountered by an alien intelligence; they are too human-centric and require way too many assumptions about visual acuity and pattern recognition and the ability to understand letters. Even people used to some languages on Earth would have great difficulty understand it. What's more, the actual transmission that was actually sent had typos in it! Nice job.

Raw transmissions such as Lincos like languages are largely mathematical, have no required geometrical interpretation to be understood, and are much more straightforward to decipher.

For an example of a Lincos-like language that was easily deciphered by amateurs, see The Contact Project. For an example of what Lincos "looks like" (it is actually a radio transmission, see Excerpts from Lincos. For more information on extraterrestrial intelligence and contact, see my Extraterrestrial intelligence links.

Dan Quayle probably couldn't spell Beowulf either...

I've been meaning, for a long time, to sit down, disembowel Omega, and write a bug-free clone. Care to help?

Actually, Omega is now under the maintainership of William Tanksley. Unfortunately, William hasn't released a stable version yet, and he doesn't have a permanent Omega web site yet.

You can visit the official Omega site, though. Or check the rec.games.roguelike.misc newsgroup.

I know that William sometimes reads /., so maybe he can give us some updates....

PEACE, n. In international affairs, a period of cheating between two periods of fighting.

One point consistently missed by the people who keep banging on the ABM treaty is that this isn't a two-superpower world any more. The USSR is gone, the Russians have no stomach for imperialism in Europe (they have their hands full with their own former SSR's), and our threats now include ideological (China, N. Korea), religious (Iran, maybe someday Pakistan) and personality-cult (Libya, Iraq) nation-states. It's never been easier to go nuclear, and we can't go on pretending that the only credible threat is HQed in Moscow.
--