Copy pasta without source. Book! https://xkcd.com/1162/
this post was submitted on 09 Apr 2025
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*Boo
(But having a book instead is always nice.)
I choose to believe it was meant as a warning, because GP is going to yeet a book at your head. But with a fair warning.
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I always use “book” as an insult. Especially since my phone autocorrect was updated…
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If we could consume uranium, you could have a teaspoon's worth and be done with eating for the rest of your life.
I think that's technically true regardless.
I wonder if that's actually factual or not. Uranium by itself isn't too terribly dangerous. It's the whole fission byproducts thing that's the buzz kill.
You would get heavy metal poisoning, same as if you ate a chunk of lead
Interestingly, no. It's not the same as if you ate a chunk of lead.
Lead binds to calcium channels, and then blocks them. This makes it a bit of a neurotoxin. It also accumulates in the bones.
Uranium on the other hand is one of the heavy metals that the body is good a filtering out of the blood. The body is not as good at expelling the uranium. It accumulates in the kidney. This can lead to kidney disease, and other related issues. And that's just the chemical toxicity of Uranium. Add in the radioactive side of things, and you have a truly distinct form of metal poisoning.
Also it depends on the isotope of uranium. Something you could find naturally isn't too dangerous, but something enriched too be used as fuel or for wepons is significantly more radioactive.
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Uranium generates that energy by fission. The hydrogen in sugar could generate huge amounts of energy if fused.
And this boulder could generate huge amounts of energy if I pushed it up to the top of Mt. Kilimanjaro and let it roll down.
44 upvotes and 0 downvotes for a comment that doesn't understand that energy density measurements like this tend to measure the useful energy of a system.
It's disappointing that natural selection didn't figure out fusion.
It figured out photosynthesis instead. Why do your own fusion when you can just take advantage of the fusion that's already happening?
There is still time
I mean, technically it already has.
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How much more energy would you get if you fused uranium?
Using the rule of thumb, anything heavier than iron requires energy input to fuse. So you lose energy fusing uranium.
Serious answer: A huge negative amount. Anything above iron requires energy to fuse (which is why it produces energy from fission.) and I'm pretty sure nothing with 184 protons could be stable enough to count as being produced - the nuclei would be more smashed apart than merging at that point.
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and all would generate the same if thrown to something capable of lossless e=mc^2 conversion (maybe a black hole)
sadly black holes go to something like 42% conversion (source: some minute physics video i think)
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Whilst I get your point, their point is still valid in the sense that you just can't extract that energy from gasoline in a more efficient manner than just burning it. For practical purposes, gasoline truly is that much less energy dense.
For comparison:
- Chemical combustion of uranium: ~4.7 MJ/kg
- Nuclear fission of uranium-235: ~83.14 TJ/kg (or $ 83.14 \times 10^6 , \text{MJ/kg} $)
In theory, yes. In practice, of those two only fission is currently viable.
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Bah, that graph needs antimatter.
Is there enough paper on earth?
Antimatter doesn't really do anything by it's own, but if we let 1 kg react with 1 kg of matter (non-anti-matter), we get E = mc^2^ with m = 2 kg. So 1.8 * 10^17^ J, or 1.8 * 10^11^ MJ. If we assume that 10 MJ/kg is represented by about 1 cm, the bar would have to be 1.8 * 10^10^ cm or about 1.8 * 10^8^ m. A standard A4 piece of paper is about 30 cm tall, so 6.0 * 10^8^ A4 papers are needed. I.e. 600 million papers.
So we definitely have enough paper, but it would be a very tall stack.
That's only about 180,000km (~112,000 miles) or just under half way to the moon.
Also some quick googling says an average desktop printer can print about 30,000 pages per month, so it would take 20,000 months (~1670 years) to print that out. And a typical toner cartridge can print 3,000 pages and costs $80, so it would take 200,000 toner cartridges and cost $16 million.
Now, those aren't based on any specific model, just the first result in Google haha
Wrong. You can't scale logs much. logs are 16 MJ/kg
Weird thing I’ve noticed:
Logs are taught in high school. Absolutely no one seems to remember what they are after the unit test, much less high school. I’ve even reminded other math instructors about how to use them.
Why do people have such a hard time learning to use and understand logs?
I love this comic, and it’s going to replace my weird “let’s talk about how this makes the distance between us and Alpha Centauri, and us and Earendil easier to understand” bit.
I mean I think a lot of it is that at least in America when it comes to Math a lot of the teaching is more about how to use specific formulas and apply them to certain kinds of problems. They don't really teach you what it is you're actually doing or why you're doing it. It just turns into recognizing a type of problem and applying a certain tool to it rather than understanding what that tool is and what it does.
Yes boss, I did work out the dynamic range of that log amplifier we wanted to use in our next product's sensor PCB, it's 80dB.
The results are over here. (points to a roll of A-4 paper)
It has 40 data points and only took me 1 week, 10 pencils, and 20 erasers to plot the chart. Yeah I can present it, it'll take me 10 minutes to roll it out, pin it down, and fetch the A-frame ladder.
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Jerry Hathaway still wants 5 megawatts by mid-May.
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