16 ms·

How many radioactive bananas would you need to power a house?

387 points by notRobot 4y ago

dredmorbius 4y ago
Energy densities of various substances and/or reactions is pretty fascinating concept. Some of the most interesting energy analysis I've come across (Vaclav Smil and David MacKay especially) describe energy in terms of area: what are the comparable land areas which would have to be dedicated to specific sources or forms of energy or fuels, and how do those compare? One of Smil's descriptions of petroleum wells is "punctiform", which I love. A hole in the ground, only about 20 cm in diameter, can provide years to millennia of human energy output, per day. 1 litre of oil is equivalent to about 3 days of human energy output (at 3,000 kilocalories/day). 1 gallon of oil is eqivalent to about 11 days of human energy. One of the oldest oil wells in production (the First Oil Well of Bahrain) produced 80,000 barrels of oil per day initially. That's over 1,000 years of human energy equivalent. By comparison, the yeild of current biomass production is far, far less. The difference, of course, is that oil is biomass, accumulated, converted, and concentrated over hundreds of millions of years. We're consuming it at > 5 million times its rate of formation. (See Jeffrey S. Dukes, "Burning Buried Sunshine" (2003).) In terms of radioactivity, the net metabolic rate of the Sun's core is lower than that of a human, measured in energy/mass. Solar metabolism is closer to that of reptiles, about 1/5 of mamallian metabolic rates. Chemical energy is less productive than the most effective nuclear transitions, but its shear abundance and ease of utilisation tends to weigh in its favour.
- criticaltinker 4y ago
  > to produce one litre of petrol it takes 1.29 kg of oil, of which 85% (1.1 kg) is carbon. And as only 1/10,750 of the carbon remains from the plants that were buried millions of years ago, our one litre of petrol is the result of 1.1 x 10,750 = 11,825 kg of carbon from ancient plants. Finally, as plants are approximately half carbon, that means that 23.65 tonnes of plants were required to make just one litre of the petrol available at your local station Burning Buried Sunshine discussion and link: https://news.ycombinator.com/item?id=28214230 https://news.ycombinator.com/item?id=28214230
  - dredmorbius 4y ago
    Thanks. I strongly recommend reading that paper, it's one I return to every few years. And yes, you're quoting your comment on my previous submission ;-)
- gibolt 4y ago
  Land area hides the true scale though. The oil fills vast volume under the ground. Solar panels may take up more surface area, but the energy output per unit of material and volume should easily out-class oil. There is also no shortage of area on land or sea that is otherwise useless to us.
  - folli 4y ago
    > There is also no shortage of area on land or sea that is otherwise useless to us That's a bold statement considering ecological factors.
    - nine_k 4y ago
      I'd say that Sahara is an ecological disaster already, the result of ancient deforestation. Even if we might considering preservation of its ecosystem, we likely won't plan to preserve all of it.
      - rob74 4y ago
        While some ecological disasters are definitely man-made, the Sahara has been mostly the way it is today for the last 10,000 years (source: https://en.wikipedia.org/wiki/Sahara#Desertification_and_prehistoric_climate https://en.wikipedia.org/wiki/Sahara#Desertification_and_pre...). Of course the current climate change will influence whether it will expand in the future, but the "core" Sahara has been there before human influence...
      - jsjohnst 4y ago
        > I'd say that Sahara is an ecological disaster already, the result of ancient deforestation. There is literally zero scientific evidence I’ve seen to back up that claim, unless by “deforestation” you mean natural “deforestation” by glaciars.
    - kuhewa 4y ago
      They could be put on top of the massive surface area of oil sands deposits that are currently being treated as ecologically unimportant. A lot of oil extraction isn't as 'punctiform' as it used to be.
- zasdffaa 4y ago
  It's too early in the morning but something doesn't seem right here, not even close. > 1 litre of oil is equivalent to about 3 days of human energy output (at 3,000 kilocalories/day). Working 8 or 24 hrs/day? . <https://peakoil.com/generalideas/how-much-energy-is-there-in-a-barrel-of-oil https://peakoil.com/generalideas/how-much-energy-is-there-in...> " So, is oil really worth $100 a barrel? Another way of looking at it is to compare oil to a horse. A horse laboring a standard 40-hour work week (eight hours a day, five days a week, 50 weeks a year) would have to labor for more than one year to produce the energy in a barrel of oil. Do you think a horse could be fed and maintained for a year for $100? Not likely. Human labor is even worse. A fit human adult can sustain about one-tenth of a horsepower, so a human would have to labor more than 10 years to equal a barrel of oil. " . and an extract from a loong! thread <https://peakoil.com/generalideas/how-much-energy-is-there-in-a-barrel-of-oil https://peakoil.com/generalideas/how-much-energy-is-there-in...> " This has been argued and debated often on TOD, mainly in response to some of my own quotes in media about 1 barrel equating to 25,000 hours of human labour (12.5 years at 40 hours per week). Ultimately the answer to this question depends highly on assumptions - but we can arrive at a good approximation. 1 barrel equates to 6.1 Gigajoules (5.8 million BTUs). Depending on the 'job', humans use roughly 100-700 Kilocalories per hour (Computer work requires an estimated 119.3 Kcals/hr). 1 kilocalorie (Kcal) = 4,184 joules. So 1 barrel of oil has 6.1 billion/4,184 = 1,454,459 kcals. Using a range of 100-700 kcals per human hour of work then results in a range 2078 and 14544 hours per barrel of oil. At 2000 hours per year (40*50), this is would then be 1.0-7.25 years per barrel. " . One more <https://www.texasmonthly.com/articles/sneak-peak/ https://www.texasmonthly.com/articles/sneak-peak/> " One barrel of oil has the same amount of energy of up to 25,000 hours of hard human labor, which is 12.5 years of work. At $20 per hour, this is $500,000 of labor per barrel " . 1 barrel ~158 litres <https://en.wikipedia.org/wiki/Barrel_of_oil_equivalent https://en.wikipedia.org/wiki/Barrel_of_oil_equivalent>. Also hard labour is about 5,000 calories/hour. (edit: horizontally spaced a bit for readability)
  - wcoenen 4y ago
    Just to clarify where the original numbers came from... The claim you are responding to: 1 liter of oil ~ 3 days of human energy output. Energy in a liter of oil: about 30 megajoules. Human base metabolic rate: below 100 watt. Let's say 100 watt. 1 watt = 1 joule/second. 30 MJ / 100 joules/second = 300000 seconds = about 3.5 days. So the original claim is correct in that sense edit: Now, this doesn't mean you can get the same benefit from a human laboring for 3 days non-stop as you could get from 1 liter of oil. This is just the energy required by the human body to stay alive. Any additional useful energy output would be on top of that, and humans can only sustain a small amount of additional power for long. That's why your references seem to disagree. Though you will really get that 100 watt from a human in the form of heat, which is why that number needs to be used when designing airco systems.
- ZeroGravitas 4y ago
  Biomass production on the other hand, can be carbon negative and generate power from waste that would otherwise get dumped. So isn't it negative surface area by this metric? Similar to rooftop solar. Despite this being a ridiculous metric, I feel oil probably loses on it still, if you did a proper well to wheels analysis. Particularly the step when you turn it into electricity, oil/biomass is going to take a major hit in both energy and and surface area.
  - dredmorbius 4y ago
    I'm not quite sure what you mean by "can be carbon negative". Are you referring to sequestring some of the biomass in soil or other formations? That's possible, yes. The principle limitation though is net primary productivity, and the human use of that, HANPP (human appropriation of net primary productivity), a/k/a the photosynthetic ceiling. Humans already account for about 20% of all NPP, with considerable economic impacts. Our fossil fuel consumption equates to another large share (from memory, I believe another 40 percent). The likelihood of substituting for even a small share of that is small. Humans initially switched from biomass (wood and biowaste) to fossil fuels because rates of consumption of current biomass productivity exceeded replacement, as well as for degredation of ecosystems in which they were produced: "forests proceed us, deserts follow us". I've yet to see a biofuel proposal which even remotely pencils out in theory, let alone when considering the likely practical obstacles. This includes woodfuel, plant-oil plantations, peat harvesting, various grasses, pickleweed (a brackish-estuary fast-growing plant), or algae farming. There's some marginal contribution possible, but even that comes at extreme cost. Human populations, per-capita energy consumption, or both, would have to fall dramatically.
saagarjha 4y ago
Ooh, new design?
- sp332 4y ago
  They are less frequent, but the What-If section has 158 entries so far. https://what-if.xkcd.com/archive/ https://what-if.xkcd.com/archive/
  - Thiez 4y ago
    "Less frequent" is one way to describe almost 4 years without updates. I assumed that the What-If section was dead :)
    - gmuslera 4y ago
      He had a column in the New York Times (https://www.nytimes.com/column/good-question-randall-munroe-xkcd https://www.nytimes.com/column/good-question-randall-munroe-...) that worked as a continuation of it in that 4 year gap.
    - iso1631 4y ago
      There's a new what-if book out later this year, available at all good bookstores just in time for christmas shopping
teruakohatu 4y ago
This was a good read, but they didn't mention how much radiation is dangerous. The power output of the decay is not relevant to people who are worried about radiation. This XKCD chart is a much better representation: https://en.wikipedia.org/wiki/Banana_equivalent_dose#/media/File:Exposure_chart-XKCD.svg https://en.wikipedia.org/wiki/Banana_equivalent_dose#/media/... If someone is worried about banana's just tell them that eating a banana a day is as risky as sleeping next to another human. (Probably less appealing is the statistic that eating a banana smoothie each day for 7 months is the same as getting one chest X-Ray every 7 months.)
perihelions 4y ago
Potassium-40 decay is also one of the largest sources of geothermal heat [0]. The cumulative energy released is within two orders of magnitude of the Earth's gravitational binding energy. [0] https://en.wikipedia.org/wiki/Earth's_internal_heat_budget#Radiogenic_heat https://en.wikipedia.org/wiki/Earth's_internal_heat_budget#R...
- dredmorbius 4y ago
  TIL! Though I've got ... questions and concerns about how certain we are that there's no large-scale heavy-element fission occurring within the Earth's core. I'd think that within the nickel-iron core, one might find even heavier elements, that those would have sunk through the primordeal (and one presumes, not-yet solid) inner core, and would tend to have greater radioactivity. How to demonstrate this does seem something of a challenge. Decay products and/or neutrino flux, possibly?
  - perihelions 4y ago
    Neutrino observatories have ruled it out (for meaningfully large aggregate power levels). - "...hypothetical georeactor at the center of the Earth having power greater than 2.4 TW at 95% C.L. is excluded" https://arxiv.org/abs/1909.02257 https://arxiv.org/abs/1909.02257 (That physics paper counts more coauthors than neutrinos!)
    - dredmorbius 4y ago
      > That physics paper counts more coauthors than neutrinos. And that's even before enabling Javascript. (Javascript-enabled neutrinos will be a key feature of Web 6.0.) (Oh, and thanks!) Questions: - How'd you find this? I'm suspecting something like "earth's core reactor neutrinos". - I don't even know how to read/interpret the notation used to express neutrino counts. Though if we can divide 112 co-authors (including deceased) by annual detection rates we can come up with a neutrino-seconds equivalent of authors....
      - 4y ago
charcircuit 4y ago
So how many do you need? I'm disappointed that the question wasn't answered.
- CGamesPlay 4y ago
  The pile of bananas larger than Manhattan is how many you need to power a single house.
- geoffpado 4y ago
  “Even if you captured that decay energy with perfect efficiency, powering a house would require about 300 quadrillion bananas, which would form a heap large enough to bury most of the skyscrapers in the NYC metro area” 300 quadrillion
  - jart 4y ago
    That still won't stop united fruit from positioning itself as a green energy solution.
    - macksd 4y ago
      Which brings us to one of the best XKCD punchlines of all time: https://what-if.xkcd.com/3/ https://what-if.xkcd.com/3/
- josephcsible 4y ago
  It was answered. You need 300 quadrillion bananas if you only use the energy emitted from the radioactive decay, or 10 bunches per day if you're willing to just burn them and basically ignore their radioactivity.
  - charcircuit 4y ago
    I expected the article to actually calculate it and not just give the answer.
    - deleted 4y ago
xhrpost 4y ago
So if I let my bananas sit out longer, they will technically have more calcium.
- t_mann 4y ago
  And flammable gases.
heywoodlh 4y ago
Does our radioactivity play a factor in human life expectancy (I obviously don't mean in lethal or higher-than-average doses)? For example, does being around the normal amount of human radioactivity improve our health or is it a detriment? Or is it a nonfactor?
- brian_cloutier 4y ago
  My understanding is at a pop-science level, but it seems like once again the chemical energy overpowers the radioactive energy. The "free radical theory of aging" blames mitochondria for a lot of the damage our cells sustain. Mitochondria generate an incredible voltage gradient which generates and throws off a trickle of oxidative radicals which go on to damage the rest of the cell, occasionally even damaging your DNA, damage which slowly accumulates over the decades of your life.
- jbboehr 4y ago
  Well there's also this concept [0]: > Radiation hormesis is the hypothesis that low doses of ionizing radiation (within the region of and just above natural background levels) are beneficial, stimulating the activation of repair mechanisms that protect against disease, that are not activated in absence of ionizing radiation. [0]: https://en.wikipedia.org/wiki/Radiation_hormesis https://en.wikipedia.org/wiki/Radiation_hormesis
- rasz 4y ago
  Normal Ramsar background radiation is ~260 mSv while 100mSv should be dangerous according to common knowledge. https://pubmed.ncbi.nlm.nih.gov/11769138/ https://pubmed.ncbi.nlm.nih.gov/11769138/ http://large.stanford.edu/courses/2018/ph241/lance2/ http://large.stanford.edu/courses/2018/ph241/lance2/ "Those who lived in higher radiation areas also were found to live the same life expectancy as those in lower radiation areas, while all residents of Ramsar had the same life expectancy as those in neighboring areas with less background radiation."
boxfire 4y ago
That second Mars Rover with plutonium is Perseverance, not Opportunity. Oppy was solar and lost to the great dust storm of 2018.
Stratoscope 4y ago
I would leave the bananas out on the counter, let them get very very ripe, and then harvest the energy of all the fruit flies flying around the house. --- This leads me to a serious question. We all know you will have a house full of fruit flies if you leave ripe bananas out. But where do they come from? Are they already in the house in some latent form, just waiting for ripe fruit that they can lay eggs in? Or are they swarming outside looking for that whiff of ripe banana gas, and they sneak in when you open the door? Where do fruit flies come from anyway?
- brenns10 4y ago
  They come in on your produce as eggs!
  - Hallucinaut 4y ago
    And, with this small comment, I have become a banana-washer
    - Stratoscope 4y ago
      Ah, but are the fruit fly eggs on the banana peel or in it? I do have a friend who insists on washing a banana before peeling it, and washing an avocado before cutting into it. At first I thought it was silly, but it actually makes sense. You're probably going to touch the banana with the same hands you got dirty from the peel, and the knife could push anything icky on the outside of the avocado peel into the delicious fruit.
      - jve 4y ago
        Moreover you never know how many different hands handled those fruits and how much chemicals did it endure until it landed on your table. And you are touching that banana too.
      - aqme28 4y ago
        I don't know how you eat a banana, but I'll basically never touch the banana itself.
chasil 4y ago
Not only are we radioactive (with 3,500 potassium-40 decays per second as the original article states), we are also sources of antimatter. "Very rarely (0.001% of events), it decays to Argon-40 by emitting a positron (β+) and a neutrino." https://en.m.wikipedia.org/wiki/Potassium-40 https://en.m.wikipedia.org/wiki/Potassium-40
orangepanda 4y ago
> In theory, you could use this heat energy to do work—that's how the Mars rovers Curiosity and Opportunity are powered. They're powered by bananas. Got it.
- bell-cot 4y ago
  Hence their limited service lives. Mars is too cold and dry to grow more bananas for the rovers.
  - ghostbrainalpha 4y ago
    Could the rovers be constructed to utilize power generated from the infinite supply of fruit flies that the rotting bananas would produce rather than the bananas themselves?
belorn 4y ago
Since the factoid comes from nuclear engineers using the banana for scale, I do wonder a bit how it actually scales up. Is a banana more radioactive than low-level nuclear waste?
- dmurray 4y ago
  No, quite a few orders of magnitude less. A banana is about 0.1 Becquerels/gram [0]. Low-level nuclear waste starts around 100 Bq/g [1]. Below that is another category called very-low-level nuclear waste. Disposing of the latter "does not pose any major problems" - you can put it in landfills, or grind it up and build roads with it - but it is still not recommended that you eat it in large quantities. [0] https://en.wikipedia.org/wiki/Banana_equivalent_dose https://en.wikipedia.org/wiki/Banana_equivalent_dose [1] https://www.radioactivity.eu.com/site/pages/VLLW_Waste.htm https://www.radioactivity.eu.com/site/pages/VLLW_Waste.htm
  - belorn 4y ago
    I suspect that the nuclear waste at Fukushima that they intend to release into the ocean is of that category very-low-level nuclear waste. 2.1gram of tritium diluted in 860,000 tons of water. Not sure how many Becquerels/gram that is, but I would be interested to know if its actually higher than the 0.1 of the banana. Is there a minimum level for what can be called very-low-level nuclear waste? (As a minor side note, someone should update wikipedia since VLLW does not seem to exist there as a category and waste with less than 100 kBq/kg is explicitly defined as LLW).
    - dmurray 4y ago
      Surprisingly, it's a lot more radioactive than the bananas. Pure tritium is 3.57×10^14 Bq/g [0] It's being diluted at a ratio of 4x10^11 : 1 so the diluted mixture still has 1000 Bq/g, or four orders of magnitude stronger than the equivalent mass in bananas. Of course, it gets diluted more after you release it into the ocean, but it would take a lot of mixing to get the water down only to banana levels. [0] https://en.wikipedia.org/wiki/Tritium https://en.wikipedia.org/wiki/Tritium
GrantZvolsky 4y ago
The banana equivalent dose is misleading because potassium doesn't accumulate in the body.
- stefantalpalaru 4y ago
qalmakka 4y ago
Yay, What If is back! Munroe hasn't posted one in ages, it's one of my favourite science pages out there. Really looking forward the new book.
- macintux 4y ago
  I concur; as I read this I was trying to figure out whether I remembered it from the before days. Munroe is a treasure.
- globular-toast 4y ago
  It looks like he didn't post this one either, assuming Kang Ji is the author?
  - jon-wood 4y ago
    Kang Ji is the person who asked the question.
Terry_Roll 4y ago
> A large cheese pizza might be three times more radioactive than a banana So thats why the food industry stopped using potassium chloride (known as the good salt) and continued using even more sodium chloride in their food. We have the Sodium Potassium pump in virtually every cell of the body and Sodium keeps the Potassium out of the body so you dont have to wait for nuclear decay! https://en.wikipedia.org/wiki/Sodium%E2%80%93potassium_pump https://en.wikipedia.org/wiki/Sodium%E2%80%93potassium_pump Cool, high salt food stops you becoming even more radioactive. Seriously though, I do like the way the message has been got across, things like "every second you roll 21 dice. If they all come up 6s, you decay.", I think more people can relate to the timescales so they know just how radioactive they become. Personally I dont know why we arent all sucking Potassium Iodide lozenges considering the amount of Potassium-40 there is in the environment. Maybe thats why Whales are the longest living mammals on the planet, the sodium chloride keeps potassium out of their bodies?
leto_ii 4y ago
> A banana contains about 100 calories of food energy, and if you incinerate whole bananas as fuel, it would only take about 10 bunches per day to keep your house running. Just at an intuitive level that sounds like very little to me. 10 bunches is what, 10 kg of bananas? That's roughly 15 euros where I live. Considering my normal wintertime heating + electricity costs that would mean using bananas for energy would only be ~1.5x more expensive than the natural gas I currently use. Does that make sense?
- deepsun 4y ago
  Kinda yes. The problem is utilizing the food energy efficiently. But if we could utilize it at only, say, 20%, that sounds reasonable to me, comparing to heating the house with wood, then 50kg of bananas should be enough. Natural gas is just more convenient, as it doesn't require you to feed the stove/dispose the ashes.
- Tade0 4y ago
  I suppose so. After all, many people use wood to heat their homes, and dry wood has around 400-500kcal of energy per 100g while dried bananas go up to 360kcal/100g.
  - leto_ii 4y ago
    Ok, but 10kg of dried bananas is something different. I imagine that can get close to 100 kg of raw bananas.
noduerme 4y ago
Natural tobacco, like I smoke, has a lot more radiation than bananas[1]. In the form of Polonium-210, mostly absorbed from phosphate fertilizers. Turns out the content is actually higher in "organic" tobacco[2]. So as I light this cigarette, I'm going to reflect for the millionth time on why I should've gotten addicted to bananas instead. But all else being equal, either cancer is cured in the next 20 years or we're all dying in a nuclear war, so, smoke up. And eat your bananas. [1] http://large.stanford.edu/courses/2019/ph241/lord1/ http://large.stanford.edu/courses/2019/ph241/lord1/ [2] https://www.straightdope.com/21343841/does-smoking-organically-grown-tobacco-lower-the-chance-of-lung-cancer https://www.straightdope.com/21343841/does-smoking-organical...
- h2odragon 4y ago
  Grow yer own, do not put apatite on it. Its an entrenched tradition in the USA, "tobacco culture" says it doesn't taste right without added radio actives. I've not looked in a decade but it may still be illegal to produce tobacco without it here.
- ghostbrainalpha 4y ago
  I think about smoking almost daily, although I haven't smoked in 20 years. We just haven't created anything remotely comparable to smoking that looks as cool, and fills that fidget hobby space in the same way. I used to love rolling my own cigarettes, and just the act of smoking. Was hoping some sort of vitamin nicotine free vape would fill the same void, but so far nothing has.
_def 4y ago
> So don't worry about the radioactivity in bananas. It's the rest of the banana that's the real threat.
jasonhansel 4y ago
It's worth noting that the idea that bananas are uniquely or unusually high in potassium is itself a myth. Many other fruits and vegetables are much higher: a cup of spinach, for instance, has about twice as much potassium as a banana, and a baked potato has even more.
- deelly 4y ago
  Quote from article: > lists lots of other foods with more potassium-40 than bananas, including coconuts, peanuts, and sweet potatoes
mkl 4y ago
> 15 decays per second from one banana work out to a couple of picowatts of power, roughly the power consumption of a single human cell. Even if you captured that decay energy with perfect efficiency, powering a house would require about 300 quadrillion[6] bananas > [6] Fine, I looked it up this time. I think that's out by a factor of 1000. Potassium-40 decays 89.28% of the time to calcium-40, releasing 1.31 MeV, and 10.72% of the time to argon-40 releasing 1.46 MeV [1]. That's .8928*1.31+.1072*1.46 = 1.32608 MeV per decay on average, which is about 2.1246e-13 Joules [2] per decay on average. 15 decays per second is 15*2.1246e-13 ≈ 3.1869e-12 Watts = 3.1869 picowatts per banana. I think Randall is using 1000 Watts as the average power usage of a house. 1000/3.1869e-12 ≈ 3.1378e14 ≈ 300,000,000,000,000 = 300 trillion bananas. Maybe he looked it up wrong? Can anyone confirm this? I can't find the packing density of bananas, but if it was 1000 kg/m^3, a medium banana is ~118 g [3], so 1000/.118 ≈ 8475 bananas / cubic metre, so 300e14/8475 ≈ 3.54e12 cubic metres of bananas. The New York metro area is about 12000 km^2 = 12e9 m^2 [4], so the depth of the banana pile is on average 3.54e12/12e9 ≈ 295 metres, which is indeed taller than most of the buildings, so that bit seems right. It's half past midnight here, so I'm well into "Someone is wrong on the internet" [5] territory.... [1] https://en.wikipedia.org/wiki/Potassium-40 https://en.wikipedia.org/wiki/Potassium-40 [2] https://www.unitjuggler.com/convert-energy-from-MeV-to-J.html?val=1.32608 https://www.unitjuggler.com/convert-energy-from-MeV-to-J.htm... [3] https://www.healthline.com/nutrition/bananas-calories-carbs https://www.healthline.com/nutrition/bananas-calories-carbs [4] https://en.wikipedia.org/wiki/New_York_metropolitan_area https://en.wikipedia.org/wiki/New_York_metropolitan_area [5] https://xkcd.com/386/ https://xkcd.com/386/
- Semaphor 4y ago
  I have no idea. But I bet he'd love an email from you :D
  - mkl 4y ago
    I couldn't find a general email address, just one for the store and a press one.
    - notRobot 4y ago
glitchc 4y ago
Goes to show once again that burning hydrocarbons produce a great deal of energy.
glenstein 4y ago
What I find so beautiful about these XKCD responses is that they acknowledge conceptual problems presented but then nevertheless carry on in the spirit of the question. One problem I think I find in comment sections, besides the epidemic of uncharitable interpretation, is this unwillingness to entertain thought experiments intended to illustrate a point in an abstract way. Resistance to the exercise comes out in various ways, like denying the practical plausibility of actually carrying out the hypothetical, to confidently dismissing them for unpredictable reasons. What's really going on is that people are expressing resistance to participating in a hypothetical, which shuts conversation down. The ability to maintain and participate in hypotheticals without unconscious mechanisms that protest against the exercise is kind of a personal marker I use for measuring the health of an online community that is interested in ideas.
tbalsam 4y ago
At least 17, probably.
focusedone 4y ago
Why is there no hovertext on two of the images? Has this ever happened before?
ck2 4y ago
Potassium becomes calcium?! is that observable over a long time (year?) with a time lapse microscope camera? > There are gazillions[3] of atoms of potassium-40 in a banana. In any given second, 10 or 15 of them make that all-sixes roll, spit out a high-energy particle, and become stable calcium or argon.
the8472 4y ago
Bananas also contain hydrogen. That's plenty of energy if you have a Mr Fusion

387 points by notRobot 4y ago

Energy densities of various substances and/or reactions is pretty fascinating concept. Some of the most interesting energy analysis I've come across (Vaclav Smil and David MacKay especially) describe energy in terms of area: what are the comparable land areas which would have to be dedicated to specific sources or forms of energy or fuels, and how do those compare? One of Smil's descriptions of petroleum wells is "punctiform", which I love. A hole in the ground, only about 20 cm in diameter, can provide years to millennia of human energy output, per day. 1 litre of oil is equivalent to about 3 days of human energy output (at 3,000 kilocalories/day). 1 gallon of oil is eqivalent to about 11 days of human energy. One of the oldest oil wells in production (the First Oil Well of Bahrain) produced 80,000 barrels of oil per day initially. That's over 1,000 years of human energy equivalent. By comparison, the yeild of current biomass production is far, far less. The difference, of course, is that oil is biomass, accumulated, converted, and concentrated over hundreds of millions of years. We're consuming it at > 5 million times its rate of formation. (See Jeffrey S. Dukes, "Burning Buried Sunshine" (2003).) In terms of radioactivity, the net metabolic rate of the Sun's core is lower than that of a human, measured in energy/mass. Solar metabolism is closer to that of reptiles, about 1/5 of mamallian metabolic rates. Chemical energy is less productive than the most effective nuclear transitions, but its shear abundance and ease of utilisation tends to weigh in its favour.

criticaltinker 4y ago
> to produce one litre of petrol it takes 1.29 kg of oil, of which 85% (1.1 kg) is carbon. And as only 1/10,750 of the carbon remains from the plants that were buried millions of years ago, our one litre of petrol is the result of 1.1 x 10,750 = 11,825 kg of carbon from ancient plants. Finally, as plants are approximately half carbon, that means that 23.65 tonnes of plants were required to make just one litre of the petrol available at your local station Burning Buried Sunshine discussion and link: https://news.ycombinator.com/item?id=28214230 https://news.ycombinator.com/item?id=28214230
- dredmorbius 4y ago
  Thanks. I strongly recommend reading that paper, it's one I return to every few years. And yes, you're quoting your comment on my previous submission ;-)
gibolt 4y ago
Land area hides the true scale though. The oil fills vast volume under the ground. Solar panels may take up more surface area, but the energy output per unit of material and volume should easily out-class oil. There is also no shortage of area on land or sea that is otherwise useless to us.
- folli 4y ago
  > There is also no shortage of area on land or sea that is otherwise useless to us That's a bold statement considering ecological factors.
  - nine_k 4y ago
    I'd say that Sahara is an ecological disaster already, the result of ancient deforestation. Even if we might considering preservation of its ecosystem, we likely won't plan to preserve all of it.
    - rob74 4y ago
      While some ecological disasters are definitely man-made, the Sahara has been mostly the way it is today for the last 10,000 years (source: https://en.wikipedia.org/wiki/Sahara#Desertification_and_prehistoric_climate https://en.wikipedia.org/wiki/Sahara#Desertification_and_pre...). Of course the current climate change will influence whether it will expand in the future, but the "core" Sahara has been there before human influence...
    - jsjohnst 4y ago
      > I'd say that Sahara is an ecological disaster already, the result of ancient deforestation. There is literally zero scientific evidence I’ve seen to back up that claim, unless by “deforestation” you mean natural “deforestation” by glaciars.
  - kuhewa 4y ago
    They could be put on top of the massive surface area of oil sands deposits that are currently being treated as ecologically unimportant. A lot of oil extraction isn't as 'punctiform' as it used to be.
zasdffaa 4y ago
It's too early in the morning but something doesn't seem right here, not even close. > 1 litre of oil is equivalent to about 3 days of human energy output (at 3,000 kilocalories/day). Working 8 or 24 hrs/day? . <https://peakoil.com/generalideas/how-much-energy-is-there-in-a-barrel-of-oil https://peakoil.com/generalideas/how-much-energy-is-there-in...> " So, is oil really worth $100 a barrel? Another way of looking at it is to compare oil to a horse. A horse laboring a standard 40-hour work week (eight hours a day, five days a week, 50 weeks a year) would have to labor for more than one year to produce the energy in a barrel of oil. Do you think a horse could be fed and maintained for a year for $100? Not likely. Human labor is even worse. A fit human adult can sustain about one-tenth of a horsepower, so a human would have to labor more than 10 years to equal a barrel of oil. " . and an extract from a loong! thread <https://peakoil.com/generalideas/how-much-energy-is-there-in-a-barrel-of-oil https://peakoil.com/generalideas/how-much-energy-is-there-in...> " This has been argued and debated often on TOD, mainly in response to some of my own quotes in media about 1 barrel equating to 25,000 hours of human labour (12.5 years at 40 hours per week). Ultimately the answer to this question depends highly on assumptions - but we can arrive at a good approximation. 1 barrel equates to 6.1 Gigajoules (5.8 million BTUs). Depending on the 'job', humans use roughly 100-700 Kilocalories per hour (Computer work requires an estimated 119.3 Kcals/hr). 1 kilocalorie (Kcal) = 4,184 joules. So 1 barrel of oil has 6.1 billion/4,184 = 1,454,459 kcals. Using a range of 100-700 kcals per human hour of work then results in a range 2078 and 14544 hours per barrel of oil. At 2000 hours per year (40*50), this is would then be 1.0-7.25 years per barrel. " . One more <https://www.texasmonthly.com/articles/sneak-peak/ https://www.texasmonthly.com/articles/sneak-peak/> " One barrel of oil has the same amount of energy of up to 25,000 hours of hard human labor, which is 12.5 years of work. At $20 per hour, this is $500,000 of labor per barrel " . 1 barrel ~158 litres <https://en.wikipedia.org/wiki/Barrel_of_oil_equivalent https://en.wikipedia.org/wiki/Barrel_of_oil_equivalent>. Also hard labour is about 5,000 calories/hour. (edit: horizontally spaced a bit for readability)
- wcoenen 4y ago
  Just to clarify where the original numbers came from... The claim you are responding to: 1 liter of oil ~ 3 days of human energy output. Energy in a liter of oil: about 30 megajoules. Human base metabolic rate: below 100 watt. Let's say 100 watt. 1 watt = 1 joule/second. 30 MJ / 100 joules/second = 300000 seconds = about 3.5 days. So the original claim is correct in that sense edit: Now, this doesn't mean you can get the same benefit from a human laboring for 3 days non-stop as you could get from 1 liter of oil. This is just the energy required by the human body to stay alive. Any additional useful energy output would be on top of that, and humans can only sustain a small amount of additional power for long. That's why your references seem to disagree. Though you will really get that 100 watt from a human in the form of heat, which is why that number needs to be used when designing airco systems.
ZeroGravitas 4y ago
Biomass production on the other hand, can be carbon negative and generate power from waste that would otherwise get dumped. So isn't it negative surface area by this metric? Similar to rooftop solar. Despite this being a ridiculous metric, I feel oil probably loses on it still, if you did a proper well to wheels analysis. Particularly the step when you turn it into electricity, oil/biomass is going to take a major hit in both energy and and surface area.
- dredmorbius 4y ago
  I'm not quite sure what you mean by "can be carbon negative". Are you referring to sequestring some of the biomass in soil or other formations? That's possible, yes. The principle limitation though is net primary productivity, and the human use of that, HANPP (human appropriation of net primary productivity), a/k/a the photosynthetic ceiling. Humans already account for about 20% of all NPP, with considerable economic impacts. Our fossil fuel consumption equates to another large share (from memory, I believe another 40 percent). The likelihood of substituting for even a small share of that is small. Humans initially switched from biomass (wood and biowaste) to fossil fuels because rates of consumption of current biomass productivity exceeded replacement, as well as for degredation of ecosystems in which they were produced: "forests proceed us, deserts follow us". I've yet to see a biofuel proposal which even remotely pencils out in theory, let alone when considering the likely practical obstacles. This includes woodfuel, plant-oil plantations, peat harvesting, various grasses, pickleweed (a brackish-estuary fast-growing plant), or algae farming. There's some marginal contribution possible, but even that comes at extreme cost. Human populations, per-capita energy consumption, or both, would have to fall dramatically.

saagarjha 4y ago

Ooh, new design?

sp332 4y ago
They are less frequent, but the What-If section has 158 entries so far. https://what-if.xkcd.com/archive/ https://what-if.xkcd.com/archive/
- Thiez 4y ago
  "Less frequent" is one way to describe almost 4 years without updates. I assumed that the What-If section was dead :)
  - gmuslera 4y ago
    He had a column in the New York Times (https://www.nytimes.com/column/good-question-randall-munroe-xkcd https://www.nytimes.com/column/good-question-randall-munroe-...) that worked as a continuation of it in that 4 year gap.
  - iso1631 4y ago
    There's a new what-if book out later this year, available at all good bookstores just in time for christmas shopping

teruakohatu 4y ago

This was a good read, but they didn't mention how much radiation is dangerous. The power output of the decay is not relevant to people who are worried about radiation. This XKCD chart is a much better representation: https://en.wikipedia.org/wiki/Banana_equivalent_dose#/media/File:Exposure_chart-XKCD.svg https://en.wikipedia.org/wiki/Banana_equivalent_dose#/media/... If someone is worried about banana's just tell them that eating a banana a day is as risky as sleeping next to another human. (Probably less appealing is the statistic that eating a banana smoothie each day for 7 months is the same as getting one chest X-Ray every 7 months.)

perihelions 4y ago

Potassium-40 decay is also one of the largest sources of geothermal heat [0]. The cumulative energy released is within two orders of magnitude of the Earth's gravitational binding energy. [0] https://en.wikipedia.org/wiki/Earth's_internal_heat_budget#Radiogenic_heat https://en.wikipedia.org/wiki/Earth's_internal_heat_budget#R...

dredmorbius 4y ago
TIL! Though I've got ... questions and concerns about how certain we are that there's no large-scale heavy-element fission occurring within the Earth's core. I'd think that within the nickel-iron core, one might find even heavier elements, that those would have sunk through the primordeal (and one presumes, not-yet solid) inner core, and would tend to have greater radioactivity. How to demonstrate this does seem something of a challenge. Decay products and/or neutrino flux, possibly?
- perihelions 4y ago
  Neutrino observatories have ruled it out (for meaningfully large aggregate power levels). - "...hypothetical georeactor at the center of the Earth having power greater than 2.4 TW at 95% C.L. is excluded" https://arxiv.org/abs/1909.02257 https://arxiv.org/abs/1909.02257 (That physics paper counts more coauthors than neutrinos!)
  - dredmorbius 4y ago
    > That physics paper counts more coauthors than neutrinos. And that's even before enabling Javascript. (Javascript-enabled neutrinos will be a key feature of Web 6.0.) (Oh, and thanks!) Questions: - How'd you find this? I'm suspecting something like "earth's core reactor neutrinos". - I don't even know how to read/interpret the notation used to express neutrino counts. Though if we can divide 112 co-authors (including deceased) by annual detection rates we can come up with a neutrino-seconds equivalent of authors....
    - 4y ago

charcircuit 4y ago

So how many do you need? I'm disappointed that the question wasn't answered.

CGamesPlay 4y ago
The pile of bananas larger than Manhattan is how many you need to power a single house.
geoffpado 4y ago
“Even if you captured that decay energy with perfect efficiency, powering a house would require about 300 quadrillion bananas, which would form a heap large enough to bury most of the skyscrapers in the NYC metro area” 300 quadrillion
- jart 4y ago
  That still won't stop united fruit from positioning itself as a green energy solution.
  - macksd 4y ago
    Which brings us to one of the best XKCD punchlines of all time: https://what-if.xkcd.com/3/ https://what-if.xkcd.com/3/
josephcsible 4y ago
It was answered. You need 300 quadrillion bananas if you only use the energy emitted from the radioactive decay, or 10 bunches per day if you're willing to just burn them and basically ignore their radioactivity.
- charcircuit 4y ago
  I expected the article to actually calculate it and not just give the answer.
  - deleted 4y ago

xhrpost 4y ago

So if I let my bananas sit out longer, they will technically have more calcium.

t_mann 4y ago
And flammable gases.

heywoodlh 4y ago

Does our radioactivity play a factor in human life expectancy (I obviously don't mean in lethal or higher-than-average doses)? For example, does being around the normal amount of human radioactivity improve our health or is it a detriment? Or is it a nonfactor?

brian_cloutier 4y ago
My understanding is at a pop-science level, but it seems like once again the chemical energy overpowers the radioactive energy. The "free radical theory of aging" blames mitochondria for a lot of the damage our cells sustain. Mitochondria generate an incredible voltage gradient which generates and throws off a trickle of oxidative radicals which go on to damage the rest of the cell, occasionally even damaging your DNA, damage which slowly accumulates over the decades of your life.
jbboehr 4y ago
Well there's also this concept [0]: > Radiation hormesis is the hypothesis that low doses of ionizing radiation (within the region of and just above natural background levels) are beneficial, stimulating the activation of repair mechanisms that protect against disease, that are not activated in absence of ionizing radiation. [0]: https://en.wikipedia.org/wiki/Radiation_hormesis https://en.wikipedia.org/wiki/Radiation_hormesis
rasz 4y ago
Normal Ramsar background radiation is ~260 mSv while 100mSv should be dangerous according to common knowledge. https://pubmed.ncbi.nlm.nih.gov/11769138/ https://pubmed.ncbi.nlm.nih.gov/11769138/ http://large.stanford.edu/courses/2018/ph241/lance2/ http://large.stanford.edu/courses/2018/ph241/lance2/ "Those who lived in higher radiation areas also were found to live the same life expectancy as those in lower radiation areas, while all residents of Ramsar had the same life expectancy as those in neighboring areas with less background radiation."

boxfire 4y ago

That second Mars Rover with plutonium is Perseverance, not Opportunity. Oppy was solar and lost to the great dust storm of 2018.

Stratoscope 4y ago

I would leave the bananas out on the counter, let them get very very ripe, and then harvest the energy of all the fruit flies flying around the house. --- This leads me to a serious question. We all know you will have a house full of fruit flies if you leave ripe bananas out. But where do they come from? Are they already in the house in some latent form, just waiting for ripe fruit that they can lay eggs in? Or are they swarming outside looking for that whiff of ripe banana gas, and they sneak in when you open the door? Where do fruit flies come from anyway?

brenns10 4y ago
They come in on your produce as eggs!
- Hallucinaut 4y ago
  And, with this small comment, I have become a banana-washer
  - Stratoscope 4y ago
    Ah, but are the fruit fly eggs on the banana peel or in it? I do have a friend who insists on washing a banana before peeling it, and washing an avocado before cutting into it. At first I thought it was silly, but it actually makes sense. You're probably going to touch the banana with the same hands you got dirty from the peel, and the knife could push anything icky on the outside of the avocado peel into the delicious fruit.
    - jve 4y ago
      Moreover you never know how many different hands handled those fruits and how much chemicals did it endure until it landed on your table. And you are touching that banana too.
    - aqme28 4y ago
      I don't know how you eat a banana, but I'll basically never touch the banana itself.

chasil 4y ago

Not only are we radioactive (with 3,500 potassium-40 decays per second as the original article states), we are also sources of antimatter. "Very rarely (0.001% of events), it decays to Argon-40 by emitting a positron (β+) and a neutrino." https://en.m.wikipedia.org/wiki/Potassium-40 https://en.m.wikipedia.org/wiki/Potassium-40

orangepanda 4y ago

> In theory, you could use this heat energy to do work—that's how the Mars rovers Curiosity and Opportunity are powered. They're powered by bananas. Got it.

bell-cot 4y ago
Hence their limited service lives. Mars is too cold and dry to grow more bananas for the rovers.
- ghostbrainalpha 4y ago
  Could the rovers be constructed to utilize power generated from the infinite supply of fruit flies that the rotting bananas would produce rather than the bananas themselves?

belorn 4y ago

Since the factoid comes from nuclear engineers using the banana for scale, I do wonder a bit how it actually scales up. Is a banana more radioactive than low-level nuclear waste?

dmurray 4y ago
No, quite a few orders of magnitude less. A banana is about 0.1 Becquerels/gram [0]. Low-level nuclear waste starts around 100 Bq/g [1]. Below that is another category called very-low-level nuclear waste. Disposing of the latter "does not pose any major problems" - you can put it in landfills, or grind it up and build roads with it - but it is still not recommended that you eat it in large quantities. [0] https://en.wikipedia.org/wiki/Banana_equivalent_dose https://en.wikipedia.org/wiki/Banana_equivalent_dose [1] https://www.radioactivity.eu.com/site/pages/VLLW_Waste.htm https://www.radioactivity.eu.com/site/pages/VLLW_Waste.htm
- belorn 4y ago
  I suspect that the nuclear waste at Fukushima that they intend to release into the ocean is of that category very-low-level nuclear waste. 2.1gram of tritium diluted in 860,000 tons of water. Not sure how many Becquerels/gram that is, but I would be interested to know if its actually higher than the 0.1 of the banana. Is there a minimum level for what can be called very-low-level nuclear waste? (As a minor side note, someone should update wikipedia since VLLW does not seem to exist there as a category and waste with less than 100 kBq/kg is explicitly defined as LLW).
  - dmurray 4y ago
    Surprisingly, it's a lot more radioactive than the bananas. Pure tritium is 3.57×10^14 Bq/g [0] It's being diluted at a ratio of 4x10^11 : 1 so the diluted mixture still has 1000 Bq/g, or four orders of magnitude stronger than the equivalent mass in bananas. Of course, it gets diluted more after you release it into the ocean, but it would take a lot of mixing to get the water down only to banana levels. [0] https://en.wikipedia.org/wiki/Tritium https://en.wikipedia.org/wiki/Tritium

GrantZvolsky 4y ago

The banana equivalent dose is misleading because potassium doesn't accumulate in the body.

stefantalpalaru 4y ago

qalmakka 4y ago

Yay, What If is back! Munroe hasn't posted one in ages, it's one of my favourite science pages out there. Really looking forward the new book.

macintux 4y ago
I concur; as I read this I was trying to figure out whether I remembered it from the before days. Munroe is a treasure.
globular-toast 4y ago
It looks like he didn't post this one either, assuming Kang Ji is the author?
- jon-wood 4y ago
  Kang Ji is the person who asked the question.

Terry_Roll 4y ago

> A large cheese pizza might be three times more radioactive than a banana So thats why the food industry stopped using potassium chloride (known as the good salt) and continued using even more sodium chloride in their food. We have the Sodium Potassium pump in virtually every cell of the body and Sodium keeps the Potassium out of the body so you dont have to wait for nuclear decay! https://en.wikipedia.org/wiki/Sodium%E2%80%93potassium_pump https://en.wikipedia.org/wiki/Sodium%E2%80%93potassium_pump Cool, high salt food stops you becoming even more radioactive. Seriously though, I do like the way the message has been got across, things like "every second you roll 21 dice. If they all come up 6s, you decay.", I think more people can relate to the timescales so they know just how radioactive they become. Personally I dont know why we arent all sucking Potassium Iodide lozenges considering the amount of Potassium-40 there is in the environment. Maybe thats why Whales are the longest living mammals on the planet, the sodium chloride keeps potassium out of their bodies?

leto_ii 4y ago

> A banana contains about 100 calories of food energy, and if you incinerate whole bananas as fuel, it would only take about 10 bunches per day to keep your house running. Just at an intuitive level that sounds like very little to me. 10 bunches is what, 10 kg of bananas? That's roughly 15 euros where I live. Considering my normal wintertime heating + electricity costs that would mean using bananas for energy would only be ~1.5x more expensive than the natural gas I currently use. Does that make sense?

deepsun 4y ago
Kinda yes. The problem is utilizing the food energy efficiently. But if we could utilize it at only, say, 20%, that sounds reasonable to me, comparing to heating the house with wood, then 50kg of bananas should be enough. Natural gas is just more convenient, as it doesn't require you to feed the stove/dispose the ashes.
Tade0 4y ago
I suppose so. After all, many people use wood to heat their homes, and dry wood has around 400-500kcal of energy per 100g while dried bananas go up to 360kcal/100g.
- leto_ii 4y ago
  Ok, but 10kg of dried bananas is something different. I imagine that can get close to 100 kg of raw bananas.

noduerme 4y ago

Natural tobacco, like I smoke, has a lot more radiation than bananas[1]. In the form of Polonium-210, mostly absorbed from phosphate fertilizers. Turns out the content is actually higher in "organic" tobacco[2]. So as I light this cigarette, I'm going to reflect for the millionth time on why I should've gotten addicted to bananas instead. But all else being equal, either cancer is cured in the next 20 years or we're all dying in a nuclear war, so, smoke up. And eat your bananas. [1] http://large.stanford.edu/courses/2019/ph241/lord1/ http://large.stanford.edu/courses/2019/ph241/lord1/ [2] https://www.straightdope.com/21343841/does-smoking-organically-grown-tobacco-lower-the-chance-of-lung-cancer https://www.straightdope.com/21343841/does-smoking-organical...

h2odragon 4y ago
Grow yer own, do not put apatite on it. Its an entrenched tradition in the USA, "tobacco culture" says it doesn't taste right without added radio actives. I've not looked in a decade but it may still be illegal to produce tobacco without it here.
ghostbrainalpha 4y ago
I think about smoking almost daily, although I haven't smoked in 20 years. We just haven't created anything remotely comparable to smoking that looks as cool, and fills that fidget hobby space in the same way. I used to love rolling my own cigarettes, and just the act of smoking. Was hoping some sort of vitamin nicotine free vape would fill the same void, but so far nothing has.

_def 4y ago

> So don't worry about the radioactivity in bananas. It's the rest of the banana that's the real threat.

jasonhansel 4y ago

It's worth noting that the idea that bananas are uniquely or unusually high in potassium is itself a myth. Many other fruits and vegetables are much higher: a cup of spinach, for instance, has about twice as much potassium as a banana, and a baked potato has even more.

deelly 4y ago
Quote from article: > lists lots of other foods with more potassium-40 than bananas, including coconuts, peanuts, and sweet potatoes

mkl 4y ago

> 15 decays per second from one banana work out to a couple of picowatts of power, roughly the power consumption of a single human cell. Even if you captured that decay energy with perfect efficiency, powering a house would require about 300 quadrillion[6] bananas > [6] Fine, I looked it up this time. I think that's out by a factor of 1000. Potassium-40 decays 89.28% of the time to calcium-40, releasing 1.31 MeV, and 10.72% of the time to argon-40 releasing 1.46 MeV [1]. That's .8928*1.31+.1072*1.46 = 1.32608 MeV per decay on average, which is about 2.1246e-13 Joules [2] per decay on average. 15 decays per second is 15*2.1246e-13 ≈ 3.1869e-12 Watts = 3.1869 picowatts per banana. I think Randall is using 1000 Watts as the average power usage of a house. 1000/3.1869e-12 ≈ 3.1378e14 ≈ 300,000,000,000,000 = 300 trillion bananas. Maybe he looked it up wrong? Can anyone confirm this? I can't find the packing density of bananas, but if it was 1000 kg/m^3, a medium banana is ~118 g [3], so 1000/.118 ≈ 8475 bananas / cubic metre, so 300e14/8475 ≈ 3.54e12 cubic metres of bananas. The New York metro area is about 12000 km^2 = 12e9 m^2 [4], so the depth of the banana pile is on average 3.54e12/12e9 ≈ 295 metres, which is indeed taller than most of the buildings, so that bit seems right. It's half past midnight here, so I'm well into "Someone is wrong on the internet" [5] territory.... [1] https://en.wikipedia.org/wiki/Potassium-40 https://en.wikipedia.org/wiki/Potassium-40 [2] https://www.unitjuggler.com/convert-energy-from-MeV-to-J.html?val=1.32608 https://www.unitjuggler.com/convert-energy-from-MeV-to-J.htm... [3] https://www.healthline.com/nutrition/bananas-calories-carbs https://www.healthline.com/nutrition/bananas-calories-carbs [4] https://en.wikipedia.org/wiki/New_York_metropolitan_area https://en.wikipedia.org/wiki/New_York_metropolitan_area [5] https://xkcd.com/386/ https://xkcd.com/386/

Semaphor 4y ago
I have no idea. But I bet he'd love an email from you :D
- mkl 4y ago
  I couldn't find a general email address, just one for the store and a press one.
  - notRobot 4y ago

glitchc 4y ago

Goes to show once again that burning hydrocarbons produce a great deal of energy.

glenstein 4y ago

What I find so beautiful about these XKCD responses is that they acknowledge conceptual problems presented but then nevertheless carry on in the spirit of the question. One problem I think I find in comment sections, besides the epidemic of uncharitable interpretation, is this unwillingness to entertain thought experiments intended to illustrate a point in an abstract way. Resistance to the exercise comes out in various ways, like denying the practical plausibility of actually carrying out the hypothetical, to confidently dismissing them for unpredictable reasons. What's really going on is that people are expressing resistance to participating in a hypothetical, which shuts conversation down. The ability to maintain and participate in hypotheticals without unconscious mechanisms that protest against the exercise is kind of a personal marker I use for measuring the health of an online community that is interested in ideas.

tbalsam 4y ago

At least 17, probably.

focusedone 4y ago

Why is there no hovertext on two of the images? Has this ever happened before?

ck2 4y ago

Potassium becomes calcium?! is that observable over a long time (year?) with a time lapse microscope camera? > There are gazillions[3] of atoms of potassium-40 in a banana. In any given second, 10 or 15 of them make that all-sixes roll, spit out a high-energy particle, and become stable calcium or argon.

the8472 4y ago

Bananas also contain hydrogen. That's plenty of energy if you have a Mr Fusion