xkcd #2929: Good and Bad Ideas

Comments

• Wild_Mastic@lemmy.world ⁨1⁩ ⁨week⁩ ago

  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

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  • Cethin@lemmy.zip ⁨1⁩ ⁨week⁩ ago

    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.

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    • Wild_Mastic@lemmy.world ⁨1⁩ ⁨week⁩ ago

      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.

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  • jol@discuss.tchncs.de ⁨1⁩ ⁨week⁩ ago

    Ah the 50s, when everything atomic was rad.

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    • GratefullyGodless@lemmy.world ⁨1⁩ ⁨week⁩ ago

      ::Fallout theme starts playing::

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  • SonnyVabitch@lemmy.world ⁨1⁩ ⁨week⁩ ago

    It’s not uncommon in scifi. Netflix’s Three Body Problem also explores such a solution in quite some depth.

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    • jballs@sh.itjust.works ⁨1⁩ ⁨week⁩ ago

      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.

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  • frezik@midwest.social ⁨1⁩ ⁨week⁩ ago

    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.

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    • Silentiea@lemmy.blahaj.zone ⁨1⁩ ⁨week⁩ ago

      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.

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  • ours@lemmy.world ⁨1⁩ ⁨week⁩ ago

    Read “Footfall” for a hard scifi story featuring such a ship.

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    • Crackhappy@lemmy.world ⁨1⁩ ⁨week⁩ ago

      I like Footfall, but it’s also a little over the top for me.

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    • Wild_Mastic@lemmy.world ⁨1⁩ ⁨week⁩ ago

      Will do! Thanks

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  • Shurimal@kbin.social ⁨1⁩ ⁨week⁩ ago

    Not worse than a fusion torch. Or open-cycle nuclear propulsion. Or an antimatter drive.

    You know, the Kzinti lesson😉

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    • Wild_Mastic@lemmy.world ⁨1⁩ ⁨week⁩ ago

      Never heard of those, but if they are on par with project Orion I have some nice readings to do today.

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  • MonkderDritte@feddit.de ⁨1⁩ ⁨week⁩ ago

    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?

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    • Badabinski@kbin.social ⁨1⁩ ⁨week⁩ ago

      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)
        • the reactor and fuel never touch, the fuel goes through a heat exchanger and is not radioactive
      • it provides extremely high efficiency
        • chemical rockets top out at ~400-500 isp in vacuum
        • NERVA tests in 1978 gave a vacuum isp of 841
        • ion thrusters like NEXT has an isp of 4170
      • it provides lots of thrust
        • NERVA had 246kN of thrust
        • NEXT (which was used on the DART mission) is 237 millinewtons
        • That's 6 orders of magnitude more thrust!
      • No oxidizer is needed
        • All you need is reaction mass, just like ion thrusters

      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, 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 built 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.

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    • Silentiea@lemmy.blahaj.zone ⁨1⁩ ⁨week⁩ ago

      Don’t forget the mass of whatever ablates from your shield!

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• Drusenija@lemmy.world ⁨1⁩ ⁨week⁩ ago

  So soup sounds like an idea and is actually an idea. Checks out.

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  • general_kitten@sopuli.xyz ⁨1⁩ ⁨week⁩ ago

    I dont know, soup has always been a better idea than it first seemed to me

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    • captain_aggravated@sh.itjust.works ⁨1⁩ ⁨week⁩ ago

      Depends on the soup I find.

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  • flerp@lemm.ee ⁨1⁩ ⁨week⁩ ago

    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.

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• Assman@sh.itjust.works ⁨1⁩ ⁨week⁩ ago

  What is this transition lense slander

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• FMT99@lemmy.world ⁨1⁩ ⁨week⁩ ago

  I was under the impression that bloodletting could in some cases actually be beneficial.

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  • Mostly_Gristle@lemmy.world ⁨1⁩ ⁨week⁩ ago

    Yeah, for people with hemochromatosis (too much iron in the blood) the main treatment is still bloodletting.

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    • deweydecibel@lemmy.world ⁨1⁩ ⁨week⁩ ago

      Or go piss off Magneto

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  • FireTower@lemmy.world ⁨1⁩ ⁨week⁩ ago

    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. Heeleys>transition lens.

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    • ZILtoid1991@lemmy.world ⁨1⁩ ⁨week⁩ ago

      And also often in such cases, blood donation is suggested instead.

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    • Viking_Hippie@lemmy.world ⁨1⁩ ⁨week⁩ ago

      Heelys>transition lens.

      I dunno, seems kinda unrelated…

      Image

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  • chumbalumber@lemmy.blahaj.zone ⁨1⁩ ⁨week⁩ ago

    Also leeches are used to help veins heal after reattaching fingers/ears/other dangly bits, which is a form of bloodletting

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  • IWantToFuckSpez@kbin.social ⁨1⁩ ⁨week⁩ ago

    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.

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  • Viking_Hippie@lemmy.world ⁨1⁩ ⁨week⁩ ago

    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 neeed… Live and let bleed!🎵

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• MonkderDritte@feddit.de ⁨1⁩ ⁨week⁩ ago

  Excuse me, what about pizza in squares?

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  • tacosplease@lemmy.world ⁨1⁩ ⁨week⁩ ago

    I guess because there is no crust to grab. Gotta get grease and maybe sauce on your hands to eat the inner squares.

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    • MonkderDritte@feddit.de ⁨1⁩ ⁨week⁩ ago

      But square pizza is the sort you eat with fork and knive tho?

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    • Rai@lemmy.dbzer0.com ⁨1⁩ ⁨week⁩ ago

      As a fork-and-knife pizza eater, I have come around to pizza squares.

      That said, PIZZA BELONGS IN A TRIANGLE

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    • ItzzMe@midwest.social ⁨1⁩ ⁨week⁩ ago

      This can be solved by using a napkin

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  • criticon@lemmy.ca ⁨1⁩ ⁨week⁩ ago

    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

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  • barsoap@lemm.ee ⁨1⁩ ⁨week⁩ ago

    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 holing.

    Home-made pizza rarely if ever is round, though, yes also and especially in Italy. You probably don’t want to go for squares though but eyeball some appropriately-sized rectangles.

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• De_Narm@lemmy.world ⁨1⁩ ⁨week⁩ ago

  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.

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  • tiredofsametab@kbin.run ⁨1⁩ ⁨week⁩ ago

    For some types of bread, the machine can do it much more uniformly and without crushing. This can be difficult for humans.

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    • onion@feddit.de ⁨1⁩ ⁨week⁩ ago

      You can buy your own bread slicer

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    • leftzero@lemmynsfw.com ⁨1⁩ ⁨week⁩ ago

      Those aren’t good types of bread, though.

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    • Rai@lemmy.dbzer0.com ⁨1⁩ ⁨week⁩ ago

      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!

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  • biddy@feddit.nl ⁨1⁩ ⁨week⁩ ago

    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.

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    • De_Narm@lemmy.world ⁨1⁩ ⁨week⁩ ago

      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 pretty 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.

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  • deegeese@sopuli.xyz ⁨1⁩ ⁨week⁩ ago

    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.

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• Hadriscus@lemm.ee ⁨1⁩ ⁨week⁩ ago

  oh lord that alt text

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• pineapplelover@lemm.ee ⁨1⁩ ⁨week⁩ ago

  What’s wrong with Transitions lenses. I like mine

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  • BearOfaTime@lemm.ee ⁨1⁩ ⁨week⁩ ago

    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 corner. Sounds bad and is bad.

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    • AdrianTheFrog@lemmy.world ⁨1⁩ ⁨week⁩ ago

      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.

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    • EncryptKeeper@lemmy.world ⁨1⁩ ⁨week⁩ ago

      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.

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    • limelight79@lemm.ee ⁨1⁩ ⁨week⁩ ago

      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.

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    • Clbull@lemmy.world ⁨1⁩ ⁨week⁩ ago

      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.

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  • RenBiv@lemmy.ml ⁨1⁩ ⁨week⁩ ago

    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!

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    • pineapplelover@lemm.ee ⁨1⁩ ⁨week⁩ ago

      They transition very quickly though. Takes like a minute

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• yamanii@lemmy.world ⁨1⁩ ⁨week⁩ ago

  Every single glasses of mine have had transition lenses, I can’t imagine my life without them anymore.

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  • Death_Equity@lemmy.world ⁨1⁩ ⁨week⁩ ago

    I love transitions lenses. I have transitions contacts and they are fantastic.

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    • Grandwolf319@sh.itjust.works ⁨1⁩ ⁨week⁩ ago

      Omg, does that mean your “eye color” changes in the sun?

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    • BearOfaTime@lemm.ee ⁨1⁩ ⁨week⁩ ago

      Holy cow-had no idea they made those.

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  • DragonOracleIX@lemmy.ml ⁨1⁩ ⁨week⁩ ago

    Same. Although mine became a lot less useful after becoming a night owl.

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• MonkderDritte@feddit.de ⁨1⁩ ⁨week⁩ ago

  Replying to spammers sound like a good idea first, should be top left.

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• UnderpantsWeevil@lemmy.world ⁨1⁩ ⁨week⁩ ago

  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.

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  • Donjuanme@lemmy.world ⁨1⁩ ⁨week⁩ ago

    Project Orion is a bad idea??

    Just don’t start the nuclear propulsion until you’re outside of earths gravity well…

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    • UnderpantsWeevil@lemmy.world ⁨1⁩ ⁨week⁩ ago

      Project Orion is a bad idea??

      A tricky bit of math to achieve, certainly.

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• witty_username@feddit.nl ⁨1⁩ ⁨week⁩ ago

  I don’t get the diver go diamond interchanges one

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  • Lux@lemmy.blahaj.zone ⁨1⁩ ⁨week⁩ ago

    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

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    • eksb@programming.dev ⁨1⁩ ⁨week⁩ ago

      Diverging diamonds are great if your only consideration is car throughput.

      If you are considering people walking or riding bicycles, they are shit.

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    • Silentiea@lemmy.blahaj.zone ⁨1⁩ ⁨week⁩ ago

      Significantly safer to navigate in practice than traditional intersections, and very straightforward to navigate in practice.

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    • stebo02@lemmy.dbzer0.com ⁨1⁩ ⁨week⁩ ago

      Image

      Having to stop for a stoplight twice just to go straight? No thx.

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• Gieselbrecht@feddit.de ⁨1⁩ ⁨week⁩ ago

  Pizza is way too right and too high on this graph.

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• samus12345@lemmy.world ⁨1⁩ ⁨week⁩ ago

  Image

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  • Rhynoplaz@lemmy.world ⁨1⁩ ⁨week⁩ ago

    I always upvote Mr. Skullhead!

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• randomaccount43543@lemmy.world ⁨1⁩ ⁨week⁩ ago

  explainxkcd.com/2929

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• Omgboom@lemmy.zip ⁨1⁩ ⁨week⁩ ago

  How dare you put heelies in the bad section

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  • Bread_And_Buried@lemmy.sdf.org ⁨1⁩ ⁨week⁩ ago

    For real, all credibility lost.

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• PiratePanPan@lemmy.dbzer0.com ⁨1⁩ ⁨week⁩ ago

  I’m sorry, what transplants?

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  • Woovie@lemmy.world ⁨1⁩ ⁨week⁩ ago

    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.

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  • barsoap@lemm.ee ⁨1⁩ ⁨week⁩ ago

    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.

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• Wiz@midwest.social ⁨1⁩ ⁨week⁩ ago

  I wonder why solar cars are bad?

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  • ours@lemmy.world ⁨1⁩ ⁨week⁩ ago

    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

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• rekabis@lemmy.ca ⁨1⁩ ⁨week⁩ ago

  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.

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• EnderMB@lemmy.world ⁨1⁩ ⁨week⁩ ago

  Hmm, I had never thought of it…but soup is absolutely a neutral experience. Even a good soup on a cold, winter day is still slightly above neutral, and is improved by non-soup add-ins.

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• mightyfoolish@lemmy.world ⁨1⁩ ⁨week⁩ ago

  If anyone else is also curious on why “putting mold on infections” is more good than crumple zones:

  They [molds] also play important roles in biotechnology and food science in the production of various pigments, foods, beverages, antibiotics, pharmaceuticals and enzymes. - Wikipedia

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• refalo@programming.dev ⁨1⁩ ⁨week⁩ ago

  Yesterday I heard a conspiracy theory that the reason lead was added to gasoline was to keep the Pouge carburetor from becoming viable because it allegedly used pre-heated gas vapor to achieve 100-200mpg efficiency, but the lead clogged it up instead.

  Here’s my own counter-conspiracy on that… if everything we read says that it didn’t actually work, why did Breen Motor Company claim it worked when THEY tried it? And why did Pouge suddenly disappear?

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• Kolanaki@yiffit.net ⁨1⁩ ⁨week⁩ ago

  Heelies should be at least below the middle line.

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• southernbrewer@lemmy.world ⁨1⁩ ⁨week⁩ ago

  Putting mold on infections? Wait what?

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• sagrotan@lemmy.world ⁨1⁩ ⁨week⁩ ago

  Combo washer dryer are never as good as two decent machines. Empiric fact.

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• angrystego@lemmy.world ⁨1⁩ ⁨week⁩ ago

  This graph is rather discutable.

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• grrgyle@slrpnk.net ⁨1⁩ ⁨week⁩ ago

  I want transitions lenses so bad, but the women in my life won’t let me 😔

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• hactar42@lemmy.ml ⁨1⁩ ⁨week⁩ ago

  Wouldn’t a fake prank fire extinguisher just be a normal fire extinguisher?

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• Lizardking27@lemmy.world ⁨1⁩ ⁨week⁩ ago

  An extension cord with 2 male ends is useful for powering your home with a generator.

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• Sorgan71@lemmy.world ⁨1⁩ ⁨week⁩ ago

  project orion was awsome and the nuclear panic ended it.

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