Blueberry Earth
January 15, 2019 8:07 AM   Subscribe

On Physics Stackexchange billybodega asked the question: Supposing that the entire Earth was instantaneously replaced with an equal volume of closely packed, but uncompressed blueberries, what would happen from the perspective of a person on the surface? Unfortunately the site tends to frown on fun questions like this, so it was in my opinion prematurely closed while I was working out the answer. So here it is, with some extra extensions.
posted by Wolfdog (30 comments total) 27 users marked this as a favorite
 
This is good.

And boo on the Physics Stackexchange for their stuffy lack of humor. Thought experiments like this are, aside from immediately useful real-world predictive models, probably the best part of physics.

May the ghost of Richard Feynman forever haunt whoever closed that question, and insert embarrassingly simple errors into all their calculations, which they won't find until a junior colleague points it out.
posted by Kadin2048 at 8:24 AM on January 15 [14 favorites]


what would happen from the perspective of a person on the surface?

they'd find themselves in a jam
posted by flabdablet at 8:24 AM on January 15 [55 favorites]


Futures in inter galactic canning and sorbet mining.
posted by Oyéah at 8:36 AM on January 15 [1 favorite]


The result is that blueberry earth will turn into a roaring ocean of boiling jam, with the geysers of released air and steam likely ejecting at least a few berries into orbit

Somewhere in the universe there must exist a blueberry-ejecting jam world...right? Or must such wonders only live in my dreams (or a Space Engine Very Berry mod package?)
posted by Khazk at 8:39 AM on January 15 [1 favorite]


Does this take into account that every 17th berry is desiccated?
posted by josephtate at 8:43 AM on January 15 [4 favorites]


Who said anything about air?
posted by Reverend John at 9:00 AM on January 15 [1 favorite]


If this starts with air between the berries, at whatever pressure, that's going to make the atmosphere of blueberry earth a whole lot larger.
posted by sfenders at 9:08 AM on January 15 [1 favorite]


This only works if you assume a peanut butter moon.
posted by phooky at 9:10 AM on January 15 [4 favorites]


Assume a spherical blueberry in a vacuum - who the hell left blueberries on the carpet?!?
posted by Greg_Ace at 9:23 AM on January 15 [4 favorites]


Surround with a planetary Dyson sphere of dough, let the sun toast it, and you have a Galactus-sized pop-tart.
posted by zaixfeep at 9:27 AM on January 15 [1 favorite]


See also: XKCD What if you had a mole of moles?
posted by straight at 9:47 AM on January 15 [4 favorites]


Metafilter: The end result is a world that has a steam atmosphere covering an ocean of jam on top of warm blueberry granita.
posted by lazaruslong at 10:08 AM on January 15


stacking a sugar cube (1 g) on a berry will not break it, while a milk carton (1 kg) will; 100 g has a decent but not certain chance.

I approve of this log(Goldilocks) approach to life.

But it seems to me that the gravitational attraction of blueberries to each other is not high enough to keep the blueberries in a Earth-shaped spheroid. What's to keep the blueberries from rolling off into outer space long before they start to pulp and jam? Will you even get jam without pectin or lemons? Why was this question posed when blueberries are out of season so I can't eat a bazillion of them as an "experiment."
posted by basalganglia at 10:15 AM on January 15


The other day we saw a commercial showing pumpkins and blueberries of the same size so my daughter and I were wondering about what it would be like to have a blueberry the size of a pumpkin. Our imaginations were not big enough to think about blueberries the size of planets (or a planet's worth of blueberries).
posted by any portmanteau in a storm at 10:21 AM on January 15 [1 favorite]


Why was this question posed when blueberries are out of season so I can't eat a bazillion of them as an "experiment."

My grocery store has blueberries right now. On sale, even! I don't know where they come from, but they are there.

Probably from strip-mining an orebody left from an ancient impact with a blueberry meteorite.
posted by Kadin2048 at 10:27 AM on January 15 [3 favorites]


Four hours and 15 comments and nobody has mentioned the historic geological discovery of Blueberry Hill by Antoine Dominique "Fats" Domino Jr.??
posted by oneswellfoop at 12:18 PM on January 15 [1 favorite]


I think that site was rezoned in the 70's, and a block of high-rise office suites got built on it.
posted by Greg_Ace at 12:49 PM on January 15


> And boo on the Physics Stackexchange for their stuffy lack of humor. Thought experiments like this are, aside from immediately useful real-world predictive models, probably the best part of physics.

Randall Munroe's What If? blog is an excellent demonstration of good scientific practices. Questions like this are a hell of a lot better than endless "do my homework!" questions, and might help with the relatively desert state of the Physics subsite.

And basically, what better way is there to show how complex and interesting and consequential your discipline is than by applying it to silly questions whose answers end up being far more complicated than they seem?
posted by ardgedee at 1:04 PM on January 15 [5 favorites]


Questions like this are a hell of a lot better than endless "do my homework!" questions

They also strike me as possibly a good way for non-scientists to become more engaged with science, since even though the questions may be a bit silly at least they involve concepts that are more "relatable" than, say, dark matter or string theory.
posted by Greg_Ace at 1:22 PM on January 15 [1 favorite]


If this starts with air between the berries, at whatever pressure, that's going to make the atmosphere of blueberry earth a whole lot larger.

To be only slightly more precise, we can estimate that at least half of the atmosphere is within 10km of the earth's surface. Wikipedia says three quarters of it is within about 11 km, so that seems safe. Let us propose to fill the blueberry orb with air at the average density of air within that volume, as if we're copy/pasting from the interior of a pile of berries way up in the sky somewhere; maybe it's being carried in a low-flying plane in the hopes that the experimenter can somehow keep flying as things proceed.

According to the first online calculator that comes up, the volume in which we've found more than half earth's present air is about 5 thousand million cubic kilometres. The volume of air to be found in the blueberry sphere, by comparison, using the blueberry packing density from tfa and the air pressure setting from the arbitrary choice above, is about 330 thousand million cubic kilometres.

So unless my calculations are somehow wrong, which seems highly impossible, that's more than 33 times more air being added to the planet than it currently has. The surface air pressure is going to be... I dunno, probably higher than the low-pressure blueberry world paradise you may have been imagining.
posted by sfenders at 2:47 PM on January 15


On second thought, I may have been off by a factor of at least ten, but less than a billion.
posted by sfenders at 2:53 PM on January 15 [3 favorites]


What's to keep the blueberries from rolling off into outer space long before they start to pulp and jam?

The sheer amount of gravity. When you've got an Earth-sized volume of blueberries, any one blueberry is pulled on by all of the rest. As the blueberries collectively have a mass equivalent to the moon, they won't roll off one another into space any more than they'd roll off the moon into space.
posted by explosion at 8:27 PM on January 15 [1 favorite]


That's a whole lot of warm blueberry granita. Can humankind eat it all before it goes bad?
posted by Conrad Cornelius o'Donald o'Dell at 9:37 PM on January 15


But if we did eat it all, then what would we live on? Like, literally?

I'm imagining the last living person gasping on mere dregs of air but still scrabbling to consume a final few berries before the remnant individual fruits and humans float off to drift, separately and forever, in the stark infinite void...
posted by Greg_Ace at 10:28 PM on January 15


> But if we did eat it all, then what would we live on? Like, literally?

Uhhhhh, let's just stick to the earth made of blueberries.
posted by lucidium at 3:11 AM on January 16


> That's a whole lot of warm blueberry granita. Can humankind eat it all before it goes bad?

All the bacteria and mould that would spoil or ferment blueberries has also been replaced by blueberries, so "goes bad" would have a different dynamic.

Upside: You and I would also have been replaced by blueberries, ergo not our problem any more.
posted by ardgedee at 4:13 AM on January 16 [2 favorites]


All hail our new Queen: Violet Beauregard
posted by Daily Alice at 4:53 AM on January 16


Even if the gravity of blueberry-earth is enough to retain such an atmosphere, the planet no longer has an iron core to provide a magnetic field. My understanding is that Earth's magnetic field helps prevent the atmosphere from being stripped away by the solar wind?
posted by NMcCoy at 5:13 AM on January 16


That would take millions of years, though.
posted by tavella at 8:34 AM on January 16


The solar wind is a liberal myth, like global warming and weak nuclear force.
posted by Kadin2048 at 11:47 AM on January 16 [2 favorites]


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