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this post was submitted on 27 Jun 2025
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Science Memes
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Fun fact: a gram of plutonium contains about 20 billion calories. Yum.
And it goes straight to my hips. By which I mean the bone marrow in my pelvis.
These hips don't lie : you got cancer
Hey, sexy bone-marrow pelvis, shake them atomic gains!
(OK, but like, if I produced synthetic plutonium I would make the box look like a chocolate box. Those workers & engineers deserve to have a fun work environment, engage in some shenanigans, make an oopsie from time to time.)
Why the pelvis specifically? How did it get there? What were you doing with it?
If you eat just one bite you'll never have to eat again for the rest of your life!
Not dietal calories.
The calorie numbers we assign to food, measure how much energy our body extracts from them when eaten.
In this context, plutonium is closer to 0
If we instead want to measure the actual total physical energy content of materia, we would turn to E=mc^2, telling us that a gram of anything has about 20 million kcal, no matter if its plutonium or diet coke. which is a slightly less useful value on food labels :D
Technically it measures how much you can heat up a known volume of water if you burn the food. We have no way of measuring how much of that energy released by combustion actually gets absorbed and translated to ATP in the body, but it’s the best estimation we have of the relative energy content of foods.
There’s some carbohydrates, proteins, and fats that our bodies don’t seem to convert to energy (or only partially convert) but still technically contain “calories” because they’re combustible. Sugar alcohols, fiber, etc.
Plutonium doesn’t combust, but it would heat up water in a calorimeter. Really the test method’s applicability kind of falls apart when you start testing undigestible materials.
Plutonium actually does combust^1^. Even worse, it's pyrophoric^2^. I couldn't easily find kcal/g though.
I did a little digging. The heat of decay (so plutonium 238 just sitting around, not burning) is about .48 kcal/hr per gram. So if we were able to convert that energy to ATP like we do carbohydrates, eating about 300g of plutonium would be like eating a twinkie (150kcal) every hour. In about 88 years the energy output of that plutonium would have reduced to about a half-twinkie per hour.
Assuming you need 2000 kcal per day to maintain weight, that’s only 83 kcal per hour needed. So, if you could survive eating it and actually utilize the energy generated, you’d be set for life on food after eating less than 300g. We’d have to come up with a dosing schedule or you’d have to work out pretty hard as a young person to keep from getting fat.
The heat of combustion for plutonium based on a very cursory search (take it with a grain of salt) is about 1 kcal/g. So assuming your body could oxidize it, you’d get a one-time burst of about 2 twinkies worth of energy immediately upon eating that 300g.
Oh no!
This is actually an issue with food calories as well. Wood shavings give a high reading in a bomb calorimeter but you can't process them into energy. Same with lots of fiber. And ethanol, in some cases.
Equivalent-level of fun fact: 1 gram of hay contains that much calories too!
No wonder cows are so fat