Stargate Physics 101: A comedy about the importance of software testing

https://archiveofourown.org/works/3673335

by gwern • 10 years ago

334 67 10 years ago

archiveofourown.org

DiabloD3• 10 years ago

Ahh, Stargate.

Never gets old, and I wish we'd find out how Universe ends already.

hias• 10 years ago

I hope there will be a new series someday.

Looking forward for the reboot triology of the original movie though :)

Noughmad• 10 years ago

I just hope O'Neill will be spelled with two L's.

phire• 10 years ago

They went into hypersleep and never woke up, it's a somewhat fitting ending.

radnor• 10 years ago

Joseph Mallozzi (executive producer of SG:U) wrote about some potential plotlines they were thinking of for the 3rd season: https://josephmallozzi.wordpress.com/2011/05/12/may-12-2011-...

kchoudhu2• 10 years ago

Each item in the list of untested edge-cases at the end corresponds to an excellent episode.

Hilarious stuff.

Tuna-Fish• 10 years ago

What episode does the "2. Rotating gate" refer to? I don't remember seeing that one...

DRMacIver7• 10 years ago

About a third of them aren't from any episode, including that one.

Bluestrike2• 10 years ago

That's hilarious. And damn, exploding planets sure do emphasize the sheer random, uh, "creativity" of users. If there's a way, they'll find it. And if there isn't, they'll make it. I wonder if Temit was an ascended being, because surely near-omniscience is the only explanation for his ability to predict some of the crazy things gate users would try.

Anyhow, one minor issue: the gates were thought of by a guy named Amelius the night before they left the Alteran Home Galaxy, long before they ever reached Earth. :)

DRMacIver7• 10 years ago

Temit was an ascended being, because surely near-omniscience is the only explanation

Any sufficiently advanced QA department is indistinguishable from ascension.

for his ability

Stop misgendering my werewolves. >:(

Anyhow, one minor issue: the gates were thought of by a guy named Amelius the night before they left the Alteran Home Galaxy, long before they ever reached Earth. :)

Yeah, I had the timeline slightly wrong for how long it took them to get to earth. In my defence there's no evidence of them making Stargates pre Milky Way (he came up with the idea in the Ori home galaxy but they then spent a few thousand years looking for somewhere to settle), and we don't know how long the Alterrans lived, so it's just about plausible, but it's a bit of a reach.

mjevans3• 10 years ago

Who says they weren't in cryo or otherwise suspended for most of that trip?

Navarr• 10 years ago

The seed ships (SGU) had stargates though - I don't think those came out of the Milky Way, and I'm very sure they predate the Milky Way stargate system

poopchute• 10 years ago

The show Stargate Universe is set on a alterran Galaxy seeding ship. The stargates in that show are definitely an earlier design than the milky way ones, demonstrated by their ability to only dial other gates within a few dozen light years instead of across the galaxy

teh• 10 years ago

I think Temit is a fuzzer or Quickcheck / Hypothesis [1] :)

[1] https://hypothesis.readthedocs.org/en/latest/

DRMacIver7• 10 years ago

Yeah, this piece has been described as Stargate/Hypothesis crossover fic before.

kbenson4• 10 years ago

Or AI. That would explain the ability to exhaustively think of scenarios and problems, while possibly not having already come up with the technology themselves (depending on whether you believe creativity is semi-distinct from intelligence in some respects).

yincrash2• 10 years ago

Furlings are a race that's still alive during the time of the TV series. They kind of look like ewoks.

[1] http://stargate.wikia.com/wiki/Furling

Terr_• 10 years ago

They kind of look like ewoks.

No, that's just an idea from one of the characters. (Re-used in a "what-if thought bubble.")

Nobody really knows.

tnecniv2• 10 years ago

That was an idea pitched in the episode "200" for the movie they were going to make.

It was a riff on the idea that everyone assumed they were furry when nothing was known about them other than their existence.

TheLogothete• 10 years ago

Nobody knows what they look like as the other commenters pointed out.

However, to a question "When are we going to see the Furlings", one of the producers answers "Who says we haven't?"

david-given2• 10 years ago

It's funny because it's true. Every word.

...well, not the bits about planets exploding. I've never written code which did that. Yet. I did once write a program which summoned demons, but never made it work.

Mtinie• 10 years ago

...but never made it work.

That's what they want you to believe.

david-given2• 10 years ago

Now I think about it, I did notice the CPU start to overheat and a strange sulphurous smell coming from the power supply when I ran the program...

jamstruth• 10 years ago

Do you work in the High Energy Magic building of the Unseen University? Giving Hex[1] the keys to summon demons sounds like a bad idea.

[1] https://en.wikipedia.org/wiki/Hex_(Discworld)

NoGravitas• 10 years ago

Or possibly at the Laundry[0]?

[0] https://en.wikipedia.org/wiki/The_Atrocity_Archives

jdaley• 10 years ago

We eventually tracked this down to some of the stabilisation algorithms – they work fine within the intended time frames, but there's an inefficiency in them that gets worse the longer the wormhole is open and eventually they can't keep up with the shifts.

An allusion to the accumulated rounding bug that caused the Patriot missile incident in 1991? That system was likewise intended to operate for only short periods.

From https://autarkaw.wordpress.com/2008/06/02/round-off-errors-a...

In the Patriot missile, time was saved in a fixed point register that had a length of 24 bits. Since the internal clock of the system is measured every one-tenth of a second, 1/10 expressed in a 24 bit fixed point register is 0.0001100110011001100110011 (the exact value is 209715/2097152).

On the day of the mishap, the battery on the Patriot missile was left on for 100 consecutive hours, hence causing an inaccuracy of 9.5E-8x10x60x60x100=0.34 seconds.

The shift calculated in the range gate due to the error of 0.342 seconds was calculated as 687m. The shift of larger than 137m resulted in the Scud not being targeted and hence killing 28 Americans in the barracks of Saudi Arabia.

seiji2• 10 years ago

Nice comparison!

But, more likely, it's just a play on a reason a Stargate (when unaided by some hostile energy source or time dilation field) just shuts off after 38 minutes with no explanation.

Someone1234• 10 years ago

I agree that it is a play on that...

However in Stargate the actual 38 minutes thing isn't a computer limitation it is a physical one. In the original show (i.e. SG1) Carter said it is "impossible" due to physics for it to stay open longer, and they also established that with enough raw power (e.g. blackhole, ancient device, etc) it could be kept open longer or near indefinitely, it just wasn't possible with the normal power the Stargate needs to operate.

Keep in mind they did exceed 38 minutes many times with different explanations each time[0] none of which were computer related. It is also worth noting that earth in the show built their own DHD which presumably would have different computer limitations than the ancient built DHD (and as they established when all DHDs in the universe died except theirs due to the malware).

[0] http://stargate.wikia.com/wiki/Stargate#Exceptions

guard-of-terra• 10 years ago

The kind of people who design things like this tend to think about such issues defensively, from the start.

Much of our fundamental problems with software seciruty stems from the fact that people don't think of software as of something particularily dangerous.

DRMacIver7• 10 years ago

One would certainly hope this to be the case, but it's hard to watch SG1 and get the impression that the ancients had much of a concept of defensive design.

mjevans3• 10 years ago

On the contrary, my view is that the Ancients knew defensive design is a /hard/ problem, for higher level languages. The lower level parts (like the actual Stargates) had smart companion interfaces where the safety features exist. The fact that you can over-ride a safety, presumably if you know what it exists for and have a use case for ignoring it, is a good engineering feature for a device that might be used in more extreme circumstances. (Such as evacuating from an Ori invasion.)

TheGuyWhoCodes2• 10 years ago

If you think about it the entire show was actually "Testing in Production"

noir_lord• 10 years ago

That was even mentioned in some of the episodes, I vaguely recall some scientist been horrified because they'd only decoded 97 of the over 200 error codes/status codes.

Probably McKay.

There was a strong technical slant in that show.

EDIT:

For instance, he knew that when Carter got the Stargate working with three supercomputers, they ignored 220 of the 400 feedback signals the Stargate can emit during any given dialing sequence.

http://stargate.wikia.com/wiki/Meredith_Rodney_McKay

I miss stargate so much.

Zardoz84• 10 years ago

McKay becomes a really nerd genius on Atlantis... I hope that at least write some books about what happens on Destiny before they got to sleep.

nbevans• 10 years ago

Haven't read the article in full but as a Stargate SG-1 fanatic, I can tell you there were numerous episodes where the plot played upon the number of bugs and design flaws in the reverse-engineered software that powered the gate on Earth. Almost every season Dr Carter would speak of the improvements she had made to the "dialling computer" and other such things. There was an episode called "Time", my favourite, where they inadvertently dialled a planet next to a black hole and the worm hole could not shut down. It was subsequently learnt that this would never have been possible had it not been for design flaws in the dialling computer program.

kefka• 10 years ago

Ah. "Error code 23, extreme gravity present"

It's OK, we don't know what this error means. We'll override it.

SolarNet2• 10 years ago

Well they are ignoring about 180 possible signals the gate could send during any dialing sequence. I assume one of them would warn about that.

jerf• 10 years ago

Half-expected the ending to be "So, anyway, we've been reassigned to this Ascension project, because the brass want that working yesterday and they've decided to add every available engineer to speed it up."

yincrash2• 10 years ago

I enjoyed the part where the author implied that the asteroid belt was the result of a stargate crashing into Tellus.

jperras• 10 years ago

The coordinate calculations were pretty hairy, so we just hard-coded each location into the Stargates for now. It shouldn't be hard to extend properly later.

Ha! Gold.

TeMPOraL2• 10 years ago

Yeah, this is the most plausible explanation I've ever heard of the utter insanity of DHD design.

heavenlyhash• 10 years ago

Some friends and I were chatting about this last night while watching the heinous MacGuffins and Deus ex Machina moments in the final episode of Atlantis, oddly enough, backpedalling furiously trying to come up with alternative excuses for the coordinate system.

Our best stab was handwaving frantically and uttering something about a Hilbert curve [1][2].

But that still doesn't really explain anything about why the ancients would pull the equivalent of going from IPv6 to v4 by dropping the number of coordinates in the Milky Way gates.... or, anything else, really.

[1] https://en.wikipedia.org/wiki/Space-filling_curve [2] a la https://xkcd.com/195/

cowpewter• 10 years ago

Wow, never thought I'd ever see an AoO link on HN. I usually mentally associate that domain with slash fic.

adiabatty2• 10 years ago

It used to be on someone's blog. It got moved to AoOO for posterity, I guess.

tnecniv2• 10 years ago

He forgot the part about how you get cold when you go through the stargate...

I need to watch this show again.

obsurveyor• 10 years ago

I'm not sure if it was explicitly addressed in the show but I believe it was a tweak to the gate control. Another bug squashed!

ajford2• 10 years ago

They resolve this in the show. Carter mentions the rough ride and cold was due to their home-grown dialing program and instabilities in the wormhole. Further tweaks result in the improved travel comfort.

TeMPOraL2• 10 years ago

That kind of explains the attitude of ascendent beings towards our universe: they treat it all as one big pile of legacy code - not to touch under any circumstances!

CharlesMerriam2• 10 years ago

Kudos for the language section. We use strange words like "bug" and "error" when we really mean more complex ideas. Where are the words for "flawed by virtue of being untested", "acceptable flaw because the chain of causality is too long in the physical world", "failure to map possible external states (as opposed to internal states)". Language design for spoken technical language should be a 'thing'.

outworlder• 10 years ago

We shipped one of them off to the nearest inhabited planet in another star system – horrible hellhole of a place called Abydos.

That is only going to be correct if you disregard the whole "Universe" series. Otherwise, the chronology is wrong. And can't be just about the movie, otherwise there are no "ancients".

All in all, an excellent read. This was almost certainly written by a software engineer, or two.

onetimePete• 10 years ago

Oh, Stargate- man i remember that- i got that idea for that city-traint wriggling itself through the gate from one wormhole to another from this. Great Inspiration.

https://springrts.com/phpbb/download/file.php?id=9695

Brilliant show. Strong science attitude of anything goes, if you put your mind to it. Also actual c++ code when "Hacking" was done.

saurik• 10 years ago

I read this and do not consider it to be about "the importance of software testing"... it reads more like a demonstration of the hubris that one can fix a fundamentally flawed system by trying to dream up test cases and then fixing them one by one as if they were in isolation of each other. One can imagine someone writing something like this about a sorting algorithm, slowly discovering corner cases of large numbers, negative numbers, 2s compliment wraparound situations, custom comparators that violate invariants, values that are being mutated while sorting... the more of these issues you find the more you should question that you really have defined the problem correctly, not patting yourself on the back for having good testing.

Stargate Physics 101: A comedy about the importance of software testing

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