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https://xkcd.com/2929

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.

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[-] Wild_Mastic@lemmy.world 96 points 6 months ago* (last edited 6 months 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

[-] Cethin@lemmy.zip 57 points 6 months 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.

[-] Wild_Mastic@lemmy.world 11 points 6 months 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.

[-] notabot@lemm.ee 20 points 6 months ago

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.

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[-] jol@discuss.tchncs.de 28 points 6 months ago

Ah the 50s, when everything atomic was rad.

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[-] SonnyVabitch@lemmy.world 19 points 6 months 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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[-] frezik@midwest.social 14 points 6 months 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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[-] ours@lemmy.world 13 points 6 months ago

Read "Footfall" for a hard scifi story featuring such a ship.

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[-] Drusenija@lemmy.world 59 points 6 months ago

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

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[-] Assman@sh.itjust.works 42 points 6 months ago

What is this transition lense slander

[-] Evotech@lemmy.world 33 points 6 months ago* (last edited 6 months ago)

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

[-] wizardbeard@lemmy.dbzer0.com 17 points 6 months ago

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.

[-] twice_twotimes@sh.itjust.works 14 points 6 months ago

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.

[-] WalrusDragonOnABike@lemmy.today 12 points 6 months ago

Why would wearing sunglasses outdoors make someone look like an asshole?

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[-] surewhynotlem@lemmy.world 11 points 6 months ago

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.

[-] rockerface@lemm.ee 12 points 6 months ago

To be fair, regular glasses mist up anyway when going inside from the cold, so you take them off anyway

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[-] FMT99@lemmy.world 33 points 6 months ago

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

[-] Mostly_Gristle@lemmy.world 34 points 6 months ago

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

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[-] FireTower@lemmy.world 15 points 6 months ago* (last edited 6 months 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. Heelys>transition lens.

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[-] MonkderDritte@feddit.de 26 points 6 months ago

Excuse me, what about pizza in squares?

[-] tacosplease@lemmy.world 28 points 6 months 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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[-] De_Narm@lemmy.world 23 points 6 months 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.

[-] tiredofsametab@kbin.run 20 points 6 months 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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[-] Hadriscus@lemm.ee 23 points 6 months ago

oh lord that alt text

[-] pineapplelover@lemm.ee 21 points 6 months ago

What's wrong with Transitions lenses. I like mine

[-] BearOfaTime@lemm.ee 14 points 6 months ago* (last edited 6 months 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~~ right corner. Sounds bad and is bad.

[-] AdrianTheFrog@lemmy.world 10 points 6 months 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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[-] yamanii@lemmy.world 20 points 6 months ago

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

[-] Death_Equity@lemmy.world 9 points 6 months ago

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

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[-] MonkderDritte@feddit.de 15 points 6 months ago* (last edited 6 months ago)

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

[-] witty_username@feddit.nl 13 points 6 months ago* (last edited 6 months ago)

I don't get the diverging diamond interchanges one

[-] Lux@lemmy.blahaj.zone 23 points 6 months 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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[-] UnderpantsWeevil@lemmy.world 13 points 6 months 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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[-] Gieselbrecht@feddit.de 13 points 6 months ago

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

[-] samus12345@lemmy.world 12 points 6 months ago
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[-] randomaccount43543@lemmy.world 12 points 6 months ago
[-] Wiz@midwest.social 9 points 6 months ago

I wonder why solar cars are bad?

[-] ours@lemmy.world 32 points 6 months 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

[-] Viking_Hippie@lemmy.world 9 points 6 months ago

unless your car is a drone on some remote planet

Which is about as ineffective as personal transport gets. And also not a car.

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[-] frezik@midwest.social 12 points 6 months ago* (last edited 6 months ago)

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.

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[-] rtxn@lemmy.world 11 points 6 months ago

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.

[-] Shurimal@kbin.social 10 points 6 months ago

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.

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this post was submitted on 07 May 2024
903 points (98.4% liked)

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