this post was submitted on 03 Apr 2024
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Science Memes

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submitted 7 months ago by [email protected] to c/[email protected]
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[–] [email protected] 36 points 7 months ago (3 children)

Meme is referring to nuclear reactors, not complete antimatter annihilation.

Nuclear reactors don't "burn" everything

most of the matter stays (this is what nuclear waste is). So you can only apply E=mc^2 to the difference in mass, not the mass of the fuel.

[–] [email protected] 15 points 7 months ago* (last edited 7 months ago) (1 children)

You know it's funny, technically a calorie is just a measure of how much energy it takes to heat up 1 gram of water 1° C I never really thought about it but it could totally be applied to other things and nuclear reactor plants that literally just heat up water to spin a turbine would be the perfect thing to measure in calories. So would regular electric plants for that matter. It might just be literally calories.

Oh shoot that would be some wild math to figure out how hungry they all are.

[–] [email protected] 6 points 7 months ago

Except that 1 gram of water is at 1 bar. Heating up 1 gram of water from 300°C to 301°C takes 1.38 calories.

[–] [email protected] 5 points 7 months ago (2 children)

Can they really get out THAT many calories from a gram of Uranium?! That's insane!

I wish I cared more and would verify it

[–] [email protected] 9 points 7 months ago

Calories are just a measure of the energy released by a material.

Normally they're measured by burning the material, so it's not really accurate to say that you can get that many calories from uranium. On the other hand the whole concept is fucking stupid anyway, because it's measured by burning the material. Technically, a kilo of dry sawdust has 4800 calories (more than double the daily calorie requirement of the average person).

[–] [email protected] 3 points 7 months ago

I just googled around and I think the meme inflated the numbers. Fast neutron reactor gets 28GJ/g, which is "only" about 7 million food (kilo) calories.

[–] [email protected] 4 points 7 months ago* (last edited 7 months ago) (1 children)

The numbers don't add up. If you can get 21 billion US food calories from total annihilation (which I checked is right), you'd get nowhere near 18 billion food calories from a fusion reaction. Maybe it works if you assume "calories" for the fission reaction means metric calories, since US food calories are metric kilocalories.

I hate the way the word "calorie" ended up with two wildly different definitions.

[–] [email protected] 5 points 7 months ago (1 children)

Yeah, I looked up energy density assuming fast neutron reactor, and it's "only" 7 million US food calories.

[–] [email protected] 3 points 7 months ago

US calories are equal to the real metric unit of kilocalories. Maybe the meme above used real calories