Explain xkcd: It's 'cause you're dumb.
In the early 20th century, visions of the future usually stipulated that everyone would travel around with rockets strapped to their backs. However, this has not come to pass.
In this comic, Randall is pointing out that the problem with personal rocket packs - more commonly called jetpacks - is not how to attach a rocket to someone's back, but other practical considerations. One might be how to keep the hot exhaust from burning the user's calves. Many jet pack designs actually do have ways to deal with this, such as moving the rockets farther from the user, but there are many other practical issues which have made this an impractical form of travel given current technology.
The title text starts with the trope "I want my jetpack". It continues with pointing out that if people did start using rocket packs, there would also be more injuries, raising health care costs. That's something that people usually don't consider when imagining a future where these devices are commonplace.
So this year when the comics was published the demand was:
- 'It's 2014--I want my jetpack [and also my free medical care covering all my jetpack-related injuries]!'
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- [Text above the frame.]
- Rocket packs are easy.
- [In the frame: Cueball is lying face down on the ground with his Rocket Packs on his back and his calves severely burned.]
- Cueball: Ow.
- [Text below the frame.]
- The hard part is inventing the calf shields.
I think long fall boots (from Portal) would probably help with this.
18.104.22.168 04:34, 16 June 2014 (UTC)
- -Not so much, they're designed for a completely different purpose. That's like expecting a kevlar vest to protect you against a sword. (They would, however, help if you ran out of fuel in midair.) 22.214.171.124 12:53, 16 June 2014 (UTC)
- A kevlar vest would protect you from a sword, if you're stabbed or hit in the chest.126.96.36.199 19:37, 16 June 2014 (UTC)
- Kevlar vests do not protect against even relatively small knives. If wearers of Kevlar body armor expect to come in close contact with hostile people, they add metal or ceramic strike plates to their armor specifically designed to upgrade it to be able protect against being stabbed with a knife or sword. 188.8.131.52 (talk) (please sign your comments with ~~~~)
I was thinking a chair design with the legs pulled out in front might help out. 184.108.40.206 (talk) (please sign your comments with ~~~~)
Wear the jet pack on your chest, avoid calf-burn. But don't mention the genitals. 220.127.116.11 05:13, 16 June 2014 (UTC)
Is it really so hard to invent calf shields? 18.104.22.168 07:53, 16 June 2014 (UTC)
Where is the problem? just reverse front and rear :=)
22.214.171.124 10:10, 16 June 2014 (UTC)
The logic and humor of this comic could be extended to the notion of "free" medical care, in a world where people are inclined to try things like rocket packs. 126.96.36.199 (talk) (please sign your comments with ~~~~)
Most practical rockets have the thrust in line with the center of gravity. A jetpack like the one depicted will tend to nose over unless the user sticks his lower legs up into the exhaust to deflect it. Not a great way to travel. Real jetpacks have the nozzles either side to get around this problem. They still have the difficulty of being unable to glide if the engine cuts. If this happens too low to use a parachute, that will spoil the user's day. Jim E (talk) 16:03, 16 June 2014 (UTC)
Why do people keep talking about running out of fuel in midair? When was the last time you ran out of fuel in your car, in between gas stations? Sure, the consequences aren't quite as catastrophic, but my point is that usually people refill their tanks before they run out...Diszy (talk) 21:30, 16 June 2014 (UTC)
- Running out of fuel isn't the only reason your car might stall or stop in the middle of nowhere. Sometimes the engine overheats and stops or the accelerator just stops working for no (apparent) reason. If something similar happens to your jetpack when you are 30m in the air, you can expect a few medical bills, if not a visit to your neighborhood mortician. Any good jetpack should come equipped with emergency boosters, but how effective they may be at low heights is still an issue. 188.8.131.52 (talk) (please sign your comments with ~~~~)
- I've run out of fuel in a car twice, due to faults. The first was a loan car - it smelt of petrol, but the owner said it was OK. Turned out it had a hole in the fuel tank, which meant that the petrol leaked out and left me stranded. The other time was my car - fuel tank had rusted (I was unaware of this), and when I went over a rough bit of road, it disintegrated, shedding fuel. Not all "out of fuel" errors are caused by driving until you run out. Farnz (talk) 13:55, 18 June 2014 (UTC)
Real life rocket packs have flight times as short as 30 seconds in some cases, so running out if fuel and falling to the ground is a very real concern. Jim E (talk) 22:54, 16 June 2014 (UTC)
I think the title text may also refer to how free health care sometimes sounds just as far-fetched in the US as practical jetpacks becoming commonplace. It was something that always almost came up when people were comparing countries on the Internet these last few years. Especially when Canadians compared their country to the States... 184.108.40.206 12:58, 17 June 2014 (UTC)
- There's no such thing as "free health care". TANSTAAFL, and TANSTAFH. Wherever you are, you and your country's economy pay for it one way or another (barring some novel method of enslaving providers of healthcare and medical supplies). Canadians pay about as much per capita for healthcare as most other industrialized nations, and incur intangible costs such as increased wait times, rationed care, and so on. I wish people would start using a less misleading term than "free healthcare", which falsely implies that magic fairies are making the costs and trade-offs disappear. If "free health care" seems "far-fetched" in the US, it's because most of us haven't lost sight of the fact that it isn't free, and (thanks to government intrusion, restrictions, and mandates) in a lot of ways it's much less free in the other sense of the word 220.127.116.11 07:43, 24 June 2014 (UTC)
- The point was not that Canada pays very little for healthcare, it is that the US pays so much. You are 100% right that Canada pays about as much as most other industrialized nations, but the US pays FAR more than most other industrialized nations. You completely ignore that the US pays per capita 90% MORE than Canada. Exact numbers are US: $8,508 Canada: $4,522.--18.104.22.168 22:29, 25 June 2014 (UTC)