xkcd #2929: Good and Bad Ideas
Alt text:
While it seemed like a fun prank at the time, I realize my prank fire extinguishers full of leaded gasoline were a mistake.
Alt text:
While it seemed like a fun prank at the time, I realize my prank fire extinguishers full of leaded gasoline were a mistake.
So, about Project Orion from Wikipedia
In August 1955, Ulam co-authored a classified paper proposing the use of nuclear fission bombs, "ejected and detonated at a considerable distance," for propelling a vehicle in outer space.
Excuse me what the fuck
All chemical propulsion is just controlled explosions that we use to push a thing forward. It's not that different, as long as you don't use it in the atmosphere or near humans.
Yeah I know, it's the same principle behind modern fuel engines. Still, using nukes for propelling something forward is a bit of a stretch.
Not just nukes, but nuclear shaped charges, at a rate of maybe one per second for a manned vehicle or even more for a faster cargo only mission.
If you can trust the human monkeys with the "shaping" of a rock that got us here, how you gonna distrust the widdle trivial matter of taking little bits of something and splitting them.
It's shaped charges, it's totally fine and sane. I'd happily get on the 1,000th Orion flight*.
*Only if that's a fresh hull
It's not uncommon in scifi. Netflix's Three Body Problem also explores such a solution in quite some depth.
I love The Three Body Problem, both the books and the show. But it bothered me to no end to read Netflix's Three Body Problem.
I'm not familiar with the books, and the plot summary of their Wikipedia article does not mention nuclear propulsion whereas the article for the series does, so I went with that.
Unless what bothers you is the x followed by the apostrophe and the s, which I never know when to omit the s, so it is what it is.
Ah gotcha. Yeah you should check out the books if you're liking the show! The books go into a ton more detail and the Staircase Project is pretty cool. Seeing it on the screen is cool too, but if you really wanna nerd out I highly recommend the books.
It would probably work just fine, but it needs a huge ship. It could get up to a few percent of the speed of light.
FWIW, nuclear test ban treaties are considered to outlaw it. I think we're more likely to solve the technical difficulties of antimatter propulsion than we are to get over the political difficulties of nuclear bomb propulsion.
It could get up to a few percent of the speed of light.
So could a person sticking their head out and blowing, but it's still a terrible idea.
Just as an observation, there was a time when everyone on the Internet was gaga over the idea of Project Orion, and you didn't dare speak out against it lest you get a hail of downvotes.
It'd work fine in deep space. It's not a good idea to launch from Earth this way. But again, we'll probably find something better once we're at the stage of needing it.
But then how would you launch nukes on orbit without the risk of accudental nuclear explosion?
Implosion-type nukes are all but impossible to make go off that way. They need a whole bunch of small explosives to go off very precisely to squeeze the core in just the right way. A short circuit or a crash won't have the necessary precision. This isn't entirely safe, either--it can still cause a small explosion with a flash of fallout and radiation--but it's a manageable problem.
Gun-types (Little Boy was one) are easier to go off on accident, but the US retired its last gun-type design decades ago. I don't think Russia used them much, either. They're only good for smaller bombs, and their safety issues make them questionable for any use. Smaller nuclear powers aren't bothering with them.
Co-written by the guy who tried to sell the US military the concept of "rods from god" (orbital kinetic weapon). I wouldn't expect anything less.
Not worse than a fusion torch. Or open-cycle nuclear propulsion. Or an antimatter drive.
You know, the Kzinti lesson😉
Never heard of those, but if they are on par with project Orion I have some nice readings to do today.
If you're into hard sci-fi and you're looking for a good read, they actually dropped a pretty good recommendation with that reference at the end - Larry Niven does a great job of blending real-world theories like Dyson spheres and advanced propulsion drives, with some of the more far-flung standards of the genre like an intra-planetary teleportation grid.
Aren't there plans again?
Considering that you need huge shields and dampening and you only have the mass of the bomb itself as propelant, is it still as effective as controlled propulsion?
I think you may be mixing up Project Orion (let's chuck bombs out of the back to make us go zoom) with NERVA (a nuclear thermal rocket engine where the heat from chemical reactions is replaced with heat from a nuclear reactor to generate gas expansion out of a nozzle). Something like NERVA is actually a great idea. Let me tell you why!
It's completely clean (unlike Orion and fission-fragment rockets)
it provides extremely high efficiency
it provides lots of thrust
No oxidizer is needed
For automated probes, the extreme efficiency and low thrust of ion thrusters makes perfect sense. If we ever want to send squishy humans further afield, we need something with more thrust so we can have shorter transit times (radiation is a bastard). Musk is supposedly going to Mars with Starship, and the Raptor engine is a marvel of engineering. I don't like the man and I'm not confident that he'll actually follow through with his plan, but the engineers at SpaceX are doing some crazy shit that might make it happen.
Just think though, if the engine was literally twice as efficient and they didn't need to lug around a tank of oxidizer, how much time could they shave off their transit? How much more could they send to Mars? Plus, they could potentially reduce the number of big-ass rockets they have to launch from Earth to refuel. If you can ISRU methane, then I imagine you could probably get hydrogen.
There are problems that still need to be resolved (the first that comes to mind is how to deal with cryogenic hydrogen boiling off), but like, the US had a nuclear thermal engine in the 70s. It was approved for use in space, but congress cut funding after the space race concluded so it never flew.
I'm happy to see that NASA is once again researching nuclear thermal rockets. Maybe we'll get somewhere this time.
I'm more with VASIMIR though, maybe with a nuclear reactor for power, since it's variable.
YMMV. For me soup sounds like a good idea but I find it annoying to eat so for me personally it is a bad idea.
I know right, I recently replaced my glasses with transition lenses and it's pretty nice.
Who doesn't want automated sunglasses? Not seeing any downsides yet. Only thing I know they don't work in cars, but I don't generally drive so it's ok
The technology has come a long way since the 90s
I find that they don't "un-tint" when going inside fast enough for my liking, personally.
Creates kind of the opposite effect of going from a dim room into a bright space. Instead of evrything seeming extra bright, it just dimmed everything and made it more difficult to see.
One problem my mom did not anticipate was that she would be stuck effectively wearing sunglasses for my brother’s outdoor wedding, where was sitting up with the bride and groom for the whole thing (Indian wedding). She just looked like an asshole, and continues to look like an asshole in the just about every photo of the ceremony. Oops.
Haha. Good point. You pretty much always have sunglasses on outside like it or not. Even when its shady
In the cold they take too long to transition to clear. So you end up taking them off for a few seconds when you go inside. It's only minorly annoying.
To be fair, regular glasses mist up anyway when going inside from the cold, so you take them off anyway
Can confirm, it’s all positives with the only downside being that it costs a little more.
No, they don't change inside (I've had them). They do have a slight tint all the time though, which isn't a big deal.
The human brain is very good at smoothing over brightness differences, even an oppressively well lit office is still typically an order of magnitude dimmer than the sun.
Yeah, for people with hemochromatosis (too much iron in the blood) the main treatment is still bloodletting.
Yeah, it's still practiced. But the whole four humors thing is a bit old hat.
I think there's a few of these misplaced. Heelys>transition lens.
Also leeches are used to help veins heal after reattaching fingers/ears/other dangly bits, which is a form of bloodletting
Yeah it can reduce PFAS levels in your system. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2790905
Though better to just donate that blood than let it go to waste.
Didn't Paul McCartney write a song about blood letting?
🎵if this ever-changing world in which we're living makes you give in to need... Live and let bleed!🎵
I guess because there is no crust to grab. Gotta get grease and maybe sauce on your hands to eat the inner squares.
Not necesarilly. I fear we have to face it: This is one of the rare cases where xkcd fucked it up.
Not at all, they are probably talking about horrible Dayton Style pizza. For when you want pizza but it needs to be thin, unsatisfying, greasy, and difficult to eat.
https://en.wikipedia.org/wiki/Dayton-style_pizza
Fucking heathens, if it weren't for them keeping keeping the alien technology from area 51 at Wright Patterson AFB I'd have them wiped off the map.
Do people actually eat this?
https://upload.wikimedia.org/wikipedia/commons/0/04/Marion%27s_Supreme.JPG
I only had New York style pizza in the US and thought the US pizza game isn't that bad.
People who eat Dayton-style pizza are like the city of Dayton itself—smelly inside and bereft of true purpose. Those of us in the US who haven't been so psychically damaged wouldn't eat that shit.
(I'm only just learning about the disgusting gutter pizza. I don't like Dayton because my last company was slowly destroyed over several years by a company that was headquartered in Dayton. I associate the city with the asshole who was CEO. Fuck you, Chris! I've heard Dayton is, at worst, not great, so take my comment as the joke it is.)
Hard to believe but they do. Note the blackened edges to make it even worse. It isn't a nice char like you get with Neapolitan, or even the seared cheese you get with a good Detroit or Pan, it's just burnt.
There are many American pizzas that are great, Chicago deep dish, NY, Detroit, on and on, Dayton style is not one of them.
This is the superior thin crust style of pizza. Cut in squares, which is a totally fine and legitimate thing to do.
Tomato soup in a bread bowl, with cheese. Not quiche, the filling isn't egg-based.
It's delicious. And since the Italians call just about any round bread with toppings pizza (e.g. Bartolomeo Scappi's pizza was cake with powdered sugar & saffron toppings) it's pizza. As is New England clam chowder in a bread bowl!
As a fork-and-knife pizza eater, I have come around to pizza squares.
That said, PIZZA BELONGS IN A TRIANGLE
If the pizza is a square or rectangle (like Detroit deep dish or a flatbread) it is on, but round pizza cut in squares is just bad
The only correct way to cut (not too gigantic) round pizza is into six parts so you get equilateral triangles (well, modulo a curved section) which is ideal for holding.
Home-made pizza rarely if ever is round, though, in which you probably don't want to go for squares but eyeball some appropriately-sized rectangles.
I think sliced bread is overrated as fuck. It used to be nice back when people couldn't just buy knives for cheap, but nowadays it just means getting stale bread faster.
For some types of bread, the machine can do it much more uniformly and without crushing. This can be difficult for humans.
You can buy your own bread slicer
i got a like 30 year old electric bread slicer, never sharpened the blade, still cuts like brand new, sometimes the crust gets stuck when its a super fresh super crispy crusted bread, but its amazing.
I recommend a very nice bread knife! I have a mediocre bread knife that was like 15USD like 15 years ago and it still saws solid slices of soft bread without schmushing the bread!
I'm mostly just commenting on why it was such a big deal in the time that it happened rather than today. Today, we do have more machines, easier access to knives, and generally less domestic work to do than was the case in this era. I do own a breadknife, though I rarely eat bread and it's mostly denser loaves when I do (a kind of sandwich bread the wife prefers or something like Baurenbrot for my tastes).
But sliced bread has become something else that doesn't exist with loaves. You can't buy an unsliced loaf of ultra-processed white bread.
You can get a wide variety of both sliced and unsliced loaves in pretty much every supermarket in my area. The ultra-processed american type bread is something else entirely and it's also a bad idea too, like pretty much all ultra-processed foods. Can that stuff even get stale? I remember it staying exactly the same up until it grows mold.
For pan loaves, people store it in a plastic bag to keep the crust soft.
Pan loaves should be presliced, stone baked loaves with thick crust should not.
Transitions are game changing. Sounds like someone who doesn't wear glasses all the time. I even had transition sunglasses before I needed glasses - got tired of taking them off going in/out all day.
Not sure who created this (I kkow, XKCD), but it's mediocre.
Double-ended extension cords belongs in the top left right corner. Sounds bad and is bad.
Double-ended extension cords belongs in the top left right corner. Sounds bad and is bad.
Remember, you’re probably more technical than the average person. Double ended extension chords sound fine if you haven’t heard of them before until you think about it for five seconds.
I’ve worn glasses my entire adult life and I had to get rid of them because being half blind every time I transition from outside to inside was interfering with my job.
This. I worked in a hardware store as a floater (I'm good at things, they ask me to do random) and often found myself irritated at how often I need to go outside for a minute to meet a customer or something, and then come back in and all the fucking lights are off.
It might just be a joke. I use transitions in my cycling glasses, where I might be in shade or when it starts to get dark (but I'll still have something protecting my eyes). I use regular sunglasses in the car, as transitions generally won't work there.
You can get them to work in the car. You just need to break all your windows.
Easy.
My only gripe with them is that if I spend any amount of time outdoors, even if it's not actually sunny, my glasses quickly turn to shades.
Coming inside and not being able to see a lot.
I specifically got rid of them having had them in my last pair. Too annoying!
I work from home in an office garden. The walk from the house to house to the office was enough to transition the lenses and then you're wearing sunglasses for 5 mins and they slowly change back. Definitely takes longer than 1 minute.
Interesting, yeah, I don't mind them as much I guess. Now I'm considering just getting prescription sunglasses to wear all the time
Every single glasses of mine have had transition lenses, I can't imagine my life without them anymore.
If you keep one eye closed and expose the other to sunlight, you can see the difference. The lenses tint a dark shade of purple. I have dark brown eyes, so you can't really notice the difference easily. There is a purple ring that is most noticeable outside of the limbal ring. They don't turn your eyes black like you had the tint of sunglasses or transitions glasses, which would be cool.
I would imagine someone with lighter color eyes, like really light blue, would have a very noticeable difference.
Something I did notice as the wearer is when the lenses are tinted there is like a contrast filter on your vision so colors look better.
They kind of released under the radar because a comedy skit about them came out and gaslighted people into believing they were not a real thing.
I only found them because I went to order contacts and saw the product category.
They aren't as good as sunglasses(but are really awesome) and they don't work much in the car so you will still want sunglasses.
Diverging diamond interchanges are a type of road intersection that appears very chaotic from the outside, but are actually pretty simple and safe to navigate
Diverging diamonds are great if your only consideration is car throughput.
If you are considering people walking or riding bicycles, they are shit.
I hadn't considered that. I was still pretty car-brained when i watched the cgp grey video on them, but now that you mention it, i definitely agree
This is expensive to address because you have to separate cyclists out to the right before the right car lane splits for right turns before the crossover. And then you have to build a bridge or tunnel for cyclists and pedestrians. On each side.
Really, any road busy enough to justify a diverging diamond probably already needed separated bike lanes. But in America (motto: "If you aren't in a car, you don't matter"), there almost certainly was not any cycling infrastructure there before.
There is one of these near me. Their solution for pedestrians is to make them cross the high speed outer lanes four times (where drivers are encouraged to not slow down). Their solution for cyclists is take the lane and pray or get off and do what the pedestrians have to do.
Edited for clarity: pedestrians cross four times, not drivers are encouraged to not slow down four times.
To be clear, it is four times that pedestrians have to cross, not four times that drivers are encouraged to not slow down. Drivers are not explicitly encouraged to not slow down, but the point of the diverging diamond is to make drivers not have to slow down.
It doesn't help that US diverging diamonds seem to insist on having pedestrians walk through the median.
But honestly all interchanges are varying degrees of horrible and if you want your city to be bearable to navigate as a pedestrian/cyclist you just really don't want to do urban highways, or roads above a certain size in general.
Significantly safer to navigate in practice than traditional intersections, and very straightforward to navigate, if not quite as easy as a normal intersection you've seen all your life.
There are many of these where I live. The lights are usually timed so that you just go straight through without having to stop. They're much better than the traditional intersections that came before.
I will absolutely concede that they're shitty for pedestrians or cyclists, however.
The ones I've used time the pedestrian lights with the traffic, so it's safer for them. Still tricky for peds going across turn lanes.
They're usually built over a motorway where there was already two stoplights just to go straight, so ...
One of the cooler parts of Three Body Problem was when they attempted the Orion Project to accelerate a probe to 1% of light speed.
Project Orion is a bad idea??
Just don't start the nuclear propulsion until you're outside of earths gravity well...
It's way more effective to collect the solar energy from a station to charge batteries than to cary the whole thing around unless your car is a drone on some remote planet
unless your car is a drone on some remote planet
Which is about as ineffective as personal transport gets. And also not a car.
Should have strapped him into the Tesla he stuck on one of his penis compensators rockets when we had the chance..
The sun gives you around 1500W per m2. If sun shines at maximum brightness for 24 hours, you get 36kwh per day. That's enough to fully charge a small EV every day. That's a spherical chicken estimate.
Bringing this to numbers that exist in the real world, the sun will only give you about 20% of that over the course of the day, and the panels are around 20% efficient. You'll get more like 1.4kwh per day per m2. You can double or triple that, depending on how much surface area you can cover. An EV can get around 3 miles per kwh, so tripling that number will get you 12 miles. Considering the extra costs involved (both in buying the panels and adding weight), it's not even worth it as a supplementary source.
There's some possibilities for RVs, which have a lot of roof space for panels, tend to sit in one spot for days or weeks, and have other power usages that are a lot less than driving. Otherwise, put the solar panels over the parking places and roadways, not on the cars.
The benefits increase as the efficiency of the car increases though, check out Aptera. They say they get 10 miles per kwh, and they have a lot of surface area for panels. Enough that in ideal conditions they say they get 40 miles per day from solar. It is a bit different looking though.
It's also a three-wheeler, which gets around US safety regulations. It gets registered as a motorcycle or autocycle (depending on how your state handles it). However, it's still an enclosed metal box. There's not a lot of good data, but it's arguably better to be sitting loose on a motorcycle with a helmet and safety gear as opposed to being crushed inside a sardine can.
There's a certain point of shrinking cars where you have to ask "why not use an e-bike?", and this is that point.
Well, it has a carbon fiber frame with a crumple zone in the front. They are going to put it through 3rd party safety testing. It won't be as safe as a big SUV, sure, but I think it will be safer than an ebike. It also protects you from weather and has 35 cubic feet of storage in the back. I think ebikes are great too, but this does have more of the advantages of a car.
You know how the Internet made fun of Stockton Rush for using carbon fiber in a sub, which is a compression structure? Similar thing going on here. Carbon fiber is a great material for tensile strength and lightweight. It can be used in compression structures, but it needs more careful engineering to pull it off. The benefits do not always outweigh the costs.
As a more general issue, if a car the size of a Geo Metro or smaller can't be safe on roads, then motorcycles and bikes can't be, either.
Well, I just said carbon fiber, but to be more exact it is forged carbon SMC, so yeah, careful engineering involved. Same stuff Lamborghini is using for some structural components, so probably fairly fit to purpose.
Cuz you can haul more, camp inside of it with the tent mod, travel further and faster.
They’re planning 250, 400 and 1000 mile versions. I’m also not taking an e-bike on the highway.
Ya I saw that cybertruck to cargo bike comparison. I automatically went to the mountain bikes. We don’t have the same cargo bikes the Dutch have but there is a guy around here with a cargo e-trike. I bet it’d be close. But the car can also take a second passenger not in the cargo space.
Solar cells of comparable scale don't provide nearly enough power to propel any kind of useful mass, and their output is only a trickle compared to even the slow-charging current of a classical EV. A solar-powered car would have to save mass everywhere, including safety devices (goodbye, crumple zones), backup propulsion, and batteries. No batteries means that the car would be limited by weather, time of day, and day of the year (winter -> sun at lower angle -> reduced solar cell power). Solar cells would have to be flush with the car's body lest they turn into sails/wings/airbrakes, which makes tracking the sun for better efficiency impossible. Driving through a city, a wooded area, or inside a tunnel would cast shadows on the car, especially at dawn/dusk.
I could go on.
They're not—as long as the PV cells are a supplementary charging solution, in addition to wall charging, to the batteries. You'll get a bit more range out while driving, especially when the car is a lightweight low drag design and PV cells may be the only thing needed to keep the constant 90 km/h speed in a sunny day. And when not driving the cells might be enough to get the 10...20 km or so commuting range back over your 8-hour workday.
But putting PV cells on a 3 ton electric SUV or pickup truck is stupid, it won't do jack all due to the inherent inefficiency of such vehicles.
Let's worry about the inefficiency of SUVs and pickup trucks for transporting one person to work. Compared to that solar panels are a drop in the bucket.
Wasn't really a car, though, rather
a small one-person battery electric recumbent tricycle, technically an "electrically assisted pedal cycle".
The energy one can get from a panel the size of a car roof is tiny and not worth the added weight.
They're not. If you make your car light enough, and potentially aerodynamic enough (things which should already be done to electric cars/cars in general), it makes sense, especially for the real life practical application of people who don't have outlets they can run to their car. Aerodynamics is mostly just an efficiency increase, but decreasing weight gives a myriad of benefits, potentially including increased power to weight ratio, decreased road wear, decreased road noise at speed, increased efficiency, improved crash safety as a result of decreasing the total amount of weight you have to stop, which can actually improve the efficiency of the interior space as you can now make things like roof pillars less thick. Could also lead to increased parking space, better maneuverability, and better visibility, if you make the car itself smaller as a result of decreased weight.
Cars should be like1/3rd of their current size. Clown cars ftw.
people with certain medical issues in their bowels can be cured of them by a fecal transplant from someone who is a good donor. It usually means a family member. The purpose is to treat bowel infections. Pretty neat shit.
It's about the microbiome, lots of critters living in your bowels breaking down stuff for you. Some conditions or treatments (e.g. chemo) can fuck with that severely up to completely obliterate everything so you need a donor to get it started up again.
Most of your body’s mass does not have a human genome, it represents other living things existing in symbiosis with your body. And your digestive tract is nearly 100% reliant on these microbiota to break down food and provide it to the small intestine. If you don’t have the right mix/balance or you have too many of the wrong species, you can suffer extremely deleterious health effects. If you have none at all, you starve pretty quickly regardless of how much food you eat.
Fun facts:
I… am strangely ambivalent and conflicted about soup.
I recognize logically and rationally that it should be lower or to the left, but would personally place it higher or to the right.
Maybe smack dab in the centre gives us the worst of both options.