explain xkcd - User contributions [en]

Talk:2324: Old Days 2

2020-06-26T13:45:18Z

172.69.63.125:

I've gotta try that, see how the ice cream truck guy reacts. Wonder where I can find an ice cream truck though? [[Special:Contributions/172.69.71.16|172.69.71.16]] 23:42, 24 June 2020 (UTC)
: The above is me, wasn't logged in, would I get in trouble for fixing the signature? [[User:Mikemk|Mikemk]] ([[User talk:Mikemk|talk]]) 23:44, 24 June 2020 (UTC)
(@Mikemk, I recon you sorted it by adding what you did. If you'd have just changed things, probably no crime if you explained it in the edit Summary. But I'm just an IP Address, so no authority.) Anyway. The bit about a phone-call stopping all electronic business is obviously rooted in dial-up needing exclusive use of a POTS line, something that only went out with broadband piggy-backing alongside voice-calls, the respective carrier-signals now microfiltered at each end of the house-to-exchange copper cabling to let them coexist over the same circuit without blocking/overwhelming each other. Though, in this comic, it's hyperbole, overly fuzzy memory, leg-pulling and/or an alternate-history being described. [[Special:Contributions/141.101.98.130|141.101.98.130]] 02:06, 25 June 2020 (UTC)
::I would just have deleted the auto signature and put in the correct after login in. Great you signed it correctly. As there is already a discussion opn this I will not correct it. Had no one answered you I would have just put your signature where the special contribution signature is and deleted your second line... ;-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 17:24, 25 June 2020 (UTC)

In the early days (of the ARPAnet) there was actually something that today would be classed as a "cloud service" (before the term was invented) although limited. It was a computer (in Cambridge, MA) funded by ARPA with massive amounts of storage and anybody on the ARPAnet could use it for storage (primary access was through FTP). So, cloud storage but not cloud computing. If you wanted to do something with the data you had to copy the whole file to your local disk, edit it there, and then send it back. The actual bits were stored on magnetic tape and there was an elaborate X/Y mechanism to select a tape and mount it on a tape drive, and later return it to its cubby. [[User:MAP|MAP]] ([[User talk:MAP|talk]]) 02:38, 25 June 2020 (UTC)

"State landline" is reminiscent of the old sailing joke where you'd ask a n00b to bring you 100 feet of shoreline. -- brad

Hm, I'd think that "state landline" is a pun on "state line". [[User:Gvanrossum|Gvanrossum]] ([[User talk:Gvanrossum|talk]]) 04:19, 25 June 2020 (UTC)

Also, while mainframes didn't exactly knit sweaters when they ran your code, they *did* produce physical artifacts -- reams of line printer paper. [[User:Gvanrossum|Gvanrossum]] ([[User talk:Gvanrossum|talk]]) 04:21, 25 June 2020 (UTC)
:Kniting a sweater out of all teletyp tapes (5 holes width could work) that where common in releationship to mainframe landline interfaces 09:08, 26 June 2020 (UTC)Knitter

"It's not even likely that any punch patterns used in computer coding would be interpretable as valid sweater-creating instructions." Is anyone up to the challenge? [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 05:04, 25 June 2020 (UTC)

Wouldn't a loom produce woven textiles rather than knit garments like sweaters? Seems like an additional layer of tall tales. [[Special:Contributions/172.68.189.179|172.68.189.179]] 06:46, 25 June 2020 (UTC)

It seems to me that the comic is having fun with false etymologies. There is especially one article that 'explains' a lot of idiom (in the sense of making up a fanciful story), which has been debunked by Snopes
https://www.snopes.com/fact-check/life-in-the-1500s/ and the comics seems to allude to a similar situation in computer science, which is now old enough that early days are shrouded in a bit of mist out of which selective trivia is remembered (punch cards had something to do with looms) and then put together into a semi-coherent story that no longer reflects reality. (With part of the joke being that many people here will actually still know or even remember what it was really like in the 'early years', but the fewer those become, the more likely it will be that made-up 'origin stories' become accepted as true.

[[Special:Contributions/141.101.69.33|141.101.69.33]] 06:54, 25 June 2020 (UTC)

Is there a pun in the title text, regarding double meaning of driver? [[Special:Contributions/172.68.226.26|172.68.226.26]] 07:59, 25 June 2020 (UTC) Eddy

The explanation about landlines needs to be reviewed. Landlines are still a thing, people are still using them, they're not a "stone age" technology.[[Special:Contributions/141.101.98.130|141.101.98.130]] 14:35, 25 June 2020 (UTC)
:I disagree. The explanation does not claim landlines are a stone age technology. It instead says that Cueball, in this context, may associate them with an imagined stone age technology. In the same vein, it is the youngster Cueball who may believe that nobody today uses landlines for anything at all. [[User:JohnB|JohnB]] ([[User talk:JohnB|talk]]) 21:22, 25 June 2020 (UTC)

This comic is why we have children and encourage them to go into the same line of work as us: so we can tell them stories of the "good old days." My wife wants nothing to do with my stories of computers in the 70s and 80s, but my son - now also a developer like me - actually listens. [[User:Gbisaga|Gbisaga]] ([[User talk:Gbisaga|talk]]) 16:13, 25 June 2020 (UTC)

"Also it is unknown how it should know in which repo to create a pull request and whom to contact about it." I assumed it was akin to those USB dead drops. You give the disk to an ice cream man and hope that there is something interesting in the repo. Also the thrill is more in being one of the few insiders who know how to access it, not necessarily the value of the contents themselves.[[Special:Contributions/173.245.54.131|173.245.54.131]] 19:25, 25 June 2020 (UTC)
:Removed - presumably the contents of the floppy disk would tell the truck driver which repo and whom to contact. Just as the requests you send over a network do now. [[Special:Contributions/108.162.245.28|108.162.245.28]] 00:41, 26 June 2020 (UTC)

: Git is a version control system, which employs and manages a centralized copy of a coding project to prevent and resolve conflicts from multiple people editing the project at once.
No. Git itself has no concept of "centralized copy". It is 100% distributed. Human developers often choose one of the copy and call it "main", "master", or whatever. But that’s only a convention humans can agree on when using this tool. [[Special:Contributions/141.101.69.91|141.101.69.91]] 21:30, 25 June 2020 (UTC)
:It might be notable that Git is while not first definitely version control system which popularized decentralized distributed version control systems. In old days, version control systems were centralized, with master copy on single server and developers fetching the code from it and then committing their changes back. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 00:21, 26 June 2020 (UTC)

The circulating mag tape is very reminiscent of quotations such as this.

"Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway."
— Andrew S. Tanenbaum

Related: {{w|Sneakernet}} and {{w|Delay-tolerant networking}}. In areas that are not served by communication lines/wireless communication, vehicles running on a regular route have been used as basis for network communications. [[Special:Contributions/108.162.245.28|108.162.245.28]] 00:41, 26 June 2020 (UTC)

"And it's not likely that any punch patterns used in computer coding would be interpretable as a suitable pattern for a sweater." - Is that a CHALLENGE? [[Special:Contributions/172.68.50.50|172.68.50.50]] 08:46, 26 June 2020 (UTC)
: Sounds like it would make an interesting esolang. [[Special:Contributions/172.69.63.125|172.69.63.125]] 13:45, 26 June 2020 (UTC)

2321: Low-Background Metal

2020-06-18T00:55:54Z

172.69.63.125: /* Explanation */

{{comic
| number = 2321
| date = June 17, 2020
| title = Low-Background Metal
| image = low_background_metal.png
| titletext = The only effect on the history books were a few confusing accounts of something called 'Greek fire.'
}}

==Explanation==
{{incomplete|Created by a TIME TRAVELER. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
In this comic, a team including [[Megan]] and [[Black Hat]] have invented {{w|time travel}}. Time travel is a common trope in science fiction, and such a discovery would be likely to change the world as we know it. However, Megan and Black Hat's machine requires the use of "low-background" metal, which is in short supply.

Megan explains that, while delicate equipment is often shielded from radiation by lead, metal produced in modern times is contaminated by {{w|nuclear fallout}} in the atmosphere, which means that the shielding itself has enough radioactivity to interfere with highly delicate equipment. In order to shield this equipment, "low-background metal" is salvaged from sunken Roman ships. This metal, primarily lead, was used as ballast in the ships. The Roman lead was produced before atmospheric nuclear tests occurred and therefore did not have {{w|radionuclides}} in the air used in its manufacture. Because it has spent many centuries continually underwater, it is both shielded from radioactive particles, and has had time for natural radioactivity to fade.

The number of shipwrecks of that age that can be found and successfully salvaged for metal is quite small, which puts this material in short supply. Megan mentions that they have only enough for a single trip. The team realizes (apparently at [[Black Hat]]'s suggestion), that a solution is to use their single trip to take modern military hardware back to the era of the {{w|Roman Empire}} and use it to sink multiple ships. This would both provide for many more shipwrecks to salvage, and give the team a good idea of where those wrecks were, when they returned to modern times. They could also specifically target ships that were in waters that are well-suited for salvage operations.

The title text refers to {{w|Greek fire}}, which was an incendiary weapon invented and employed by the Byzantine empire. It was a flammable liquid used in naval combat to set fire to enemy ships, famously said to burn on water. As it was a closely-guarded military secret, many of the details have been lost to time, and modern chemists have only been able to develop educated guesses of what it ''probably'' was. Randall proposes a rather outlandish alternative hypothesis: that all records of Greek fire were actually in reference to the modern weapons used by the time travelers.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Megan, Black Hat and Cueball stand around a time machine on a table.]
:Megan: Our time machine works.
:Megan: But we're almost out of low-background metal.
:Cueball: What's that?

:[Close-up on Megan.]
:Megan: Modern metal is contaminated by fallout from nuclear testing, and lead also has natural radioactivity that fades over time.
:Megan: To shield sensitive equipment, physicists use lead from sunken Roman ships.
:Megan: But shipwreck lead is hard to find.

:[Zoomed back out to the group. Megan is facing Black Hat, who has his hand on his chin.]

:Black Hat: How much do we have?
:Megan: Enough for one trip through time.
:Black Hat: ''Hmmm...''

:[The scene changes to the group having traveled through time. They are in a helicopter, with Megan piloting, Cueball as a passenger, and Black Hat firing a flamethrower at a Roman ship. The sailors on the ship are alarmed and attempting to escape. Two already-burning ships can also be seen, with one almost completely sunk.]
:Flamethrower: FWOOOSH

{{comic discussion}}

[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Time travel]]

2321: Low-Background Metal

2020-06-17T16:13:39Z

172.69.63.125: /* Explanation */

2321: Low-Background Metal

2020-06-17T16:13:03Z

172.69.63.125: /* Explanation */