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The scale here is absolutely nuts to me. 86 billion nuclei represent only 29 picograms. One gram is 10^12 picograms.

1,000 billion billion gold nuclei per gram of gold.



The analogy I heard was that if you take a golf ball and enlarge it to the size of the Earth, the atoms in the enlarged golf ball would be about the size of the original golf ball.


It took me a while to understand this comment, because I imagined that scaling up a golf ball would involve creating new atoms, but what you said only makes sense if you are scaling up the individual atoms.

What you're saying is that the ratio of the size of an atom to the size of a golf ball is approximately the same as the ratio of the size of a golf ball to the size of the earth.

I'm surprised atoms are so big, I would have guessed much smaller.


The analog is no good because it assumes people have an intuitive understanding of the volume of the Earth, which basically 0 people do because it's stupidly absurdly counter-intuitive (like volume in general). So let's go for something way smaller. Imagine we take just one little 'cube' of Earth that's just 1 mile on each side. And let's start placing boxes in it that are 1 cubic foot in size, so about the size of a micro microwave. How many of these boxes would it take to fill our little cube? The math is simple, but the answer is no less stupefying or counter-intuitive. It's more than 147 billion!!

Ok. Imagine we take those cubes that filled our 'little' cube of earth and taped them in one giant stack. That stack would not only reach to the Moon, but reach to the Moon 116 times over! In fact you'd be nearly able to reach Mars at its closest approach (34.8 million miles, vs 27.8 million miles for our box stack). And that's in 1 cubic mile of volume. The volume of Earth is about 260 billion cubic miles. To wrap up by getting back to golf balls - you can fit about 700 golf balls in 1 cubic ft.

------

Actually a somewhat macabre example came to mind. How many humans could we fit in our little cubic mile? And the answer is literally all of us, many times over in fact! And that's in just one cubic mile of the 260 billion total on Earth.


Hate me all you want for the last part of my comment, but I was trying to follow along. And then... non-metric :-[


Is this going to be on the test, Professor?


We’d fit, but it sounds uncomfortable.


> I'm surprised atoms are so big, I would have guessed much smaller.

Me too. Perhaps what we should realise is not how big atoms are, but how small we are. I wonder if life can be sustained at larger scales. Could we have galaxy-sized lifeforms that make us look like bacteria?


The relationship between time and distance is presumed to be a system constant, which we named c.

So, a galaxy-sized lifeform would take a very long time to experience stuff. It takes a tiny but measurable amount of time to go from your brain choosing "Press button" to your muscles all that distance away firing to cause the button press, and then for the button press to have effect - at galaxy scale these periods would be much larger than all of human recorded history.


It'd have to be much more distributed in its ability to react, like octopuses arms being semi autonomous. They'll continue to pass objects towards the body even after being severed.

Or consider the humongous fungus: https://en.m.wikipedia.org/wiki/Armillaria_ostoyae


Sure, but it's not clear in this case whether say the human species should also count as a single "organism". We don't understand very much about the octopus, which is a healthy reminder of why I shouldn't even speculate about alien life which would almost unavoidably be much stranger than an octopus - but we feel comfortable asserting that the "semi autonomous" limbs of the octopus are not distinct in the way that say, my friends Chris and Caroline are distinct people. So if this galaxy sized organism consisted of smaller units with similarly distinct properties, I think we'd say that's not a galaxy sized organism that's a culture of individuals.


Good point. Of course this presumes that we understand the physics at that scale, and that there's nothing akin to a quantum tunneled nervous system, etc.


think it's relative upward and downward in scale. an entity at universe scale might be moving similar speed to us in our 3d space


No, I assure you that the constant is not concerned with scale, we're easily able to check that. A bigger device does not make this constant larger or smaller, you may be able to get more accurate results but that scale is unaltered.


Not so early in the universe age, but who knows what happens in 10^10^10^10 years. Also organisms consume energy, but mechanism of consumption of some ultra massive central quasars is beyond my imagination (I know Marvel has Hunger character but thats not the level of detail and logic I mean).


There is a great classic sci-fi book that explores this: https://www.amazon.com/Black-Cloud-Fred-Hoyle/dp/0140014667


Maybe as an eventually consistent life form using extremely slow message passing. Though gravity becomes a major factor that would limit the size unless it’s incredibly sparse.

One of my favorite episodes of Love, Death, & Robots is “Swarm”. Worth a watch.


But that comment is about atoms, while ALICE is talking about nuclei, which are way smaller than atoms. Not sure what would be the analogy there.


Atoms are large enough to have noticeable Brownian motion visible with an optical microscope.

They're small but not impossibly so.


mmmm, not exactly. you cannot see atomic brownian motion with an optical microscope, what you can see is visible brownian motion of otherwise visible particles caused by their collisions with molecules/atoms. this says as much about the momentum/energy of the collisions as it does about the mass (which bears some relationship to the size which bears direct relation to optical visibility)


You are correct, but that is what I meant, even if the way I wrote it is either incorrect or somewhat unclear.


Now consider that most of that volume is empty space. Scaling up an atom such that a nucleus is the size of the Sun, you'd end up with an electron cloud about the size of the planetary solar system.


Atoms are relatively large and relatively dense in solids, atomic nuclei are small.


How do you draw a distinction? The nucleus is the part of the atom that occupies space.


The electrons are far better at occupying space. Or at least at keeping out other atoms, which is what counts.


This makes more sense to me shrinking down instead of sizing up: "Hold a golf ball. Imagine you're looking at the Earth with its own golf balls. Those smaller golf balls are the same size as atoms in the original golf ball you're holding."


Speaking of scale, this is a fun video at the other end of the spectrum:

https://www.youtube.com/watch?v=7J_Ugp8ZB4E


That's actually how they chose the size of a golf ball.


Yeah. I think most ppl (incl me) lack strong intuition about things at scales outside our human day-to-day. Reminds me of a conversation about wealth, someone said "The difference between a million and a billion is... about a billion."


A tenth of a percent is often a rounding error. So the difference between a million and a billion truly is about a billion.

When the above isn’t enough to light a bulb, I like introduce that as analogous to pennies.

1 penny is $0.01 10 pennies is $0.1 100 pennies is $1 1,000 pennies is $10 10,000 pennies is $100 100,000 pennies is $1,000 1,000,000 pennies is $10,000 10,000,000 pennies is $100,000 100,000,000 pennies is $1,000,000 1,000,000,000 pennies is $10,000,000

Most people understand that ten million dollars is not just a different amount but a distinct kind of amount from ten thousand dollars. The powers of ten seem to become clearer with a smaller starting amount. Once they grasp the above, point out that the relationship is the same if everything starts 100 times as large.

There’s also a great one out there comparing 1,000 to 1 million to 1 billion seconds, converted to years plus days.


Avogadro's number has a 10^23 in it to account for this atom-->physical matter sort of "scale up" conversion. Atoms are really small...


Sometimes I have a hard time wrapping my head around reconciling that with the estimated number of protons in the observable universe which is "only" ~10^80 (https://en.m.wikipedia.org/wiki/Eddington_number). Seems like it "should" be much higher, but orders of magnitude are sometimes deceptive to our intuition.


Unrelated, but I moved to a more rural area a while back and I’m surrounded by orchards and fields a fair amount of time, and my mind just can’t wrap itself around the scale of agriculture.

One avocado tree can produce around 200 avocados per year, and the orchards around here are probably around 150 trees/acre, so 30k avocados/acre/year.

Each avocado has about 250 calories (and that is just the parts that we eat, the tree has to put energy and mass into the pit and skin etc). These are food calories / kcal, so that’s 250k calories per avocado, or ~7.5 billion calories per year per acre.

7.5B calories/year is just about exactly 1kW, so that orchard is converting sunlight (and water, air, and trace minerals) to avocado calories at a continuous rate of 1kW. It’s incredible. The USDA says that as of 2022 there were about 880M acres of farmland in the United States alone.


1 acre is about 4,050 m^2, and incident sunlight has an average intensity of 1kW/m^2.

So your avocado orchard is converting incident sunlight to food calories with an efficiency of about 0.025%.

(This ... isn't wildly inefficient for photosynthesis, though typical values range from 1--3% AFAIU, though I've not computed this on a per-acre / per-hectare basis.)

Mind too that you're getting more than just avocado meat, there are also the skins and pits as you note, as well as leaves and wood, all of which could be used as fuel should we really want to.

Ecologists look at the net total energy conversion of ecosystems, often expressed not in terms of energy but as carbon fixation --- how much CO2 is captured from the atmosphere and converted to biomass.

And that amount is ... surprisingly limited. We'll often hear that humans use only a small fraction of the sunlight incident on the Earth's surface, but once you start accounting for various factors, that becomes far less comforting than it's usually intended. Three-quarters of Earth's surface is oceans (generally unsuitable for farming), plants and the biosphere require a certain amount of that activity, etc., etc. It turns out that humans already account for about 40% of net primary productivity (plant metabolism) of the biosphere. Increasing our utilisation of that is ... not likely, likely greatly disruptive, and/or both.

Another interesting statistic: In 1900, just as the Model T Ford was being introduced, and local transport (that is, exclusive of inter-city rail and aquatic transport) was principally dependent on human feet or horse's hooves, twenty percent of the US grain crop went to animal feed. (And much of that ended up on city streets.) We had a biofuel-based economy, and it consumed much of our food supply.

(Stats are for the US but would be typical of other countries of the time.)

This isn't an argument that fossil fuels are "good", or that renewables are "bad". It does point out, however, that changing our present system is hard, and any solution will cause pain and involve compromises.


It takes a bit to accept your (10^0 m) place in the universe on the length scale between the Planck length (10^-35 m), the width of a proton (10^-15 m) and the diameter of the observable universe (10^27 m).


I wonder if there's any reason we're roughly in the middle.


Well the ratio of the strong force, vs electromagnetism and the speed of light define the size of the atom. Life requires machinery to self replicate and the distance between a DNA base pair is a sugar molecule attached in a chain so that's about as small as possible. Intelligence requires a certain amount of complexity of something like a brain, and it has to be made of cells and doubtful it could be made more than an order of magnitude smaller.

Could intelligent life exist based on some other physical phenomena than a self-replicating string of atoms? Maybe some unknown quantum phenomena inside neutron stars or something big and slow on galactic scales or something new which fills the dark matter gap...

But otherwise it's physics driving where units of "stuff" can exist, and the correct scales for long term complexity/turbulence can happen, like the thin film of goo on the outside of the frozen crust of a molten rock we are.


"Roughly" still being off by a factor of 10^5 means an amoeba, or bacteria in general, would be acing the "middle" better than us though.


My brain says that's only 4 times as many.



Aren't we all a bit weird looking? I'm more entertained that URL was already in my browser history


Huh. It was grayed out for me as well, but I have no recollection of having had to look up moles, Avogadro, or even chemistry-related topics in Wikipedia for at least several months.


it's hn greying out the post


It looks like his MIND=BLOWN, then popped and re-inflated in Theme Hospital. It just goes to show how dangerous it is to think about such big numbers.

https://www.youtube.com/watch?v=Le_znuXcP2M


He was obviously an alien.


Ah, the source of "hey girls, take my number" meme.


> The scale here is absolutely nuts to me.

Being able to detect these tiny amounts is nuts to me.




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