What would life be like on the remnants of a shattered planet?

Question

The year is 2089. The political shenanigans of the day have gotten more out of hand than usual and violent zealots have detonated the Earth's largest deposit of plotium devicide, an extremely versatile chemical compound that in this instance explodes with sufficient power to destroy the Earth. The planet shatters into millions of pieces, ranging in size from dust particles to moon-sized chunks, which mostly remain tumbling around the sun in their old orbit.

Billions of lives are lost and the Earth's biosphere is devastated beyond comprehension. However, plotium devicide can be also be used to construct indestructible bunkers, and several tens of thousands humans managed to survive this catastrophe along with a few decades worth of supplies (they were in the middle of a political crisis, after all). Also, several vaults (not unlike the real-world doomsday seed vault) were also reinforced with PD and were scattered, intact, across the shards of the Earth. These contained the genetic sequences of millions of species of plants, animals, fungi, protista, and bacteria, as well as huge reserves of food and useful technology, such as water purifiers, medicine, and equipment useful for agriculture and electrical infrastructure.

The question is, how screwed are the survivors? Please feel free to bring up any issues you feel are relevant, but I'm primarily curious about the following issues:

• Gravity
  • What would the gravity be like on the surface on some of the larger chunks?
  • What effect would the other chunks have on the gravity you felt?
  • What shape might the chunks form?
• Atmosphere
  • Would there be air, or would the atmosphere be lost into space?
  • Would there be oxygen?
• Surface Features
  • Would any of Old Earth's surface survive and remain recognizable, or would the event be catastrophic enough to leave no features intact? Remember, the explosion shattered the planet; it didn't vaporize or liquefy it (plotium devicide explodes in a highly unusual manner).
  • I'm wondering about mountains, surface water, and (ruined) cities.
• Civilization
  • Given the above points, do the humans have even a chance in hell of surviving, and if so, do they manage to organize? How?

Answers should be based in science but creativity is strongly encouraged. After all, the system was contaminated with huge amounts of plotium devicide, which could have extremely unpredictable effects. Have fun!

Answer 1

Don't Panic
--Hitchhiker's Guide to the Galaxy, Douglas Adams

Seriously though:

Everybody is certainly dead

Including everyone in the special bomb shelters.

Anything with enough energy to disrupt the Earth - will essentially melt or vaporize the entire Earth - including every biological entity living on, in, or over it.

To give you an idea of the energies we are talking about. The Theia Impact event (something about the size of Mars smacked into the Earth) melted or vaporized the entire Earth all the way down to the core. This impact did not have enough energy to disrupt the Earth's binding energy.

The Theia Impact provided about 2/3 of the energy required to disrupt the Earth.

2/3th of the Energy you described does this:

This is a video of an object about 1/1000th of Mars mass (and therefore 1/1000 the Theia impact energy) striking the Earth - realize that nothing survives this either.

The only way tens of thousands survive is if they manage to be far away from the planet when it happens.

No such thing as a shattered Earth

Depending upon the specifics of an impact/explosion you might get a shattered Earth for a tiny period of time, but this configuration is not stable. The shattered bits will all be in motion - some falling towards Earth, others flying off.

If the explosion is powerful enough to disrupt the Earth, then the pieces keep on going and the planet disappears. If the explosion does not disrupt the Earth, then it all falls back and we end up with a molten Earth.

Even if the super shelters are strong enough to withstand the explosion (they won't be), the people inside will subject to g forces ranging from 100 - 1000+ g upon impacting other objects. If the shelter doesn't leave the surface of the Earth, then it'll be floating in a sea of molten magma several thousand degrees which should cook the survivors to "well done".

This video of the formation of the Moon gives you an idea of how utterly screwed Humanity would be in such a situation:

Gravity

If the Earth is actually disrupted (e.g. down to the size of gravel), then it will dissipate. Some will fly off quickly but it will take a while for the rest to leave the vicinity of where the Earth originally was. From a distance, the mass left in the vicinity of Earth's starting position will still provide gravitational attraction, albeit at a significantly lessened level.

Close up, gravity will be squirrely. The mass that's flown past you will cancel out (as if it were a shell), so it really depends upon where you are in the debris field. Assuming your in the middle somewhere you'll notice gradually lessening gravity as you and bits of the Earth fly away from each other.

Atmosphere

After the Theia Impact, the Earth retained most of its atmosphere and hydrosphere. It took thousands or millions of years for it to all return (it had been blasted into orbit after all), but most of it was not lost to the planet.

You are talking about a more powerful explosion and the atmosphere and hydrosphere are the most volatile components of the Earth. So these will be among the first components lost.

Surface Features

None

If disrupted, the Earth will have no surface features. If the blast was insufficient to disrupt the Earth, then the Earth's surface will be completely molten.

After the initial impact, shock, & splash die down; the Earth's surface will be a nearly perfect oblate spheroid. Meanwhile, debris will continually rain down from orbit - possibly for thousands to hundreds of thousands of years.

Civilization

Kiss everything up to geosynchronous orbit goodbye.

Humanity had better hope it has created colonies throughout the solar system. A Lunar colony is probably doomed - too much debris from the Earth will end up hitting the Moon.

Even a colony on Mars might have issues with the amount of material that will be flying around the inner solar system.

It might pay to have people put on a generation ship that just flies around trying to dodge this stuff.

Messing with your premise

We frown on arguing with the questioner about their premise but...

There's only so much energy that you can store in chemical bonds. There is no conceivable way to make a chemical that has unlimited bond strength such that breaking them and reforming it disrupts the Earth (or conversely that this chemical can be used to shield against the equivalent of a 10 x million x million powerful nuclear explosions).

Atomic Rockets: Boom Table shows that the explosion required to do this would require about $1.5 \cdot 10^{13}$ megaton explosions (basically that many large nuclear explosions). If you didn't have the nuclear weapons, then you would need $1.5 \cdot 10^{19} tons$ of high explosives. This is something like 20x of the mass of all of the oceans in the world.

If you write a story with your plotium devicide and it has these properties, bear in mind no one who knows physics is going to suspend their disbelief (FWIW, I have read good stories that throw physics out the window so I don't want to totally discourage you on this).

Answer 2

The short term effects of shattering the planet would be that much of the atmosphere and liquid water is lost. The amount of energy to shatter the Earth would be between 1.5 X 10^30J (blow off Terra's crust into space) and 2.9 X 10^31J (reduce the Earth to gravel). This is far beyond the amounts of energy needed to blow the Earth's atmosphere and oceans into space, so initially we are surrounded with a rapidly expanding cloud of vapour. (All figures courtesy of the Atomic Rocket's "Boom Table": http://www.projectrho.com/public_html/rocket/usefultables.php)

Although I'm not clear how to quantify this, you would also have a very nasty problem as the pressure was released from the Earth's core. Massive amounts of white hot iron would suddenly be expanding into the vacuum of space, potentially coating every solid surface it came into contact with, and providing energy to drive at least some of it out of the Earth's old orbit. From some safe distance in space, you would see a glowing, rapidly expanding cloud of "stuff" assuming a rather weird oval shape. People who sought safety on the Moon are bombarded with splinters of hot, iron coated rock, and a temporary atmosphere of hot nitrogen, oxygen and water vapour also covers the moon (rapidly corroding much of the infrastructure that is in place, designed for the vacuum environment).

The release of energy should also produce a great deal of heat, so the remaining chunks of Earth are going to be heated to such an extent that some of them will be molten, and most will have melted through the surface layers. This heat pulse will also affect the surface of the Moon, although not so dramatically.

As the excitement dies down, gravity patiently takes over. Pieces of the Earth are going to be close together and the larger pieces will have sufficient gravitational attraction to draw smaller pieces towards them. The cascade effect will continue as more and more pieces are drawn towards each other and the Earth begins to reform. Since we have pieces ranging in size from sand to chunks the size of the Moon, the process will be messy and inconsistent, but the pieces will be crashing together at an accelerating rate. Once again, the sheer mass will exert a massive amount of pressure on the pieces caught in the middle, and with the squeeze will come more heat (see a pattern here?), starting the process of melting and the eventual redistribution of the Earth's mass, with iron and heavy elements gradually settling into the new core, and lighter silicates rising to the surface.

It is thought that a great deal of water (up to 3X the amount currently in the Earth's oceans) is trapped in the rocks in the mantle, so we can assume that at least some of that will remain, and the heat of reformation will cause it to be outgassed onto the newly molten surface. An atmosphere of steam will surround the Earth for thousands of years until the surface cools enough to allow condensation and rain.

As for the bunkers trapped in the Earth's crust, unless they have also defied the laws of physics in other ways, they will be quickly roasted by being surrounded by molten rock and unable to shed their heat loads. given the chaotic reformation org the Earth, there is a good chance that some of the bunkers will be reformed far below the nominal crust and will be crushed by the massively increasing pressures in the new core and mantle. Real survivalists will have fled with Elon Musk to Mars back in the 2020's, so after spending a thousand or so years practicing terraforming Mars, they will be ready to return to the somewhat smaller and much drier Earth in the year 3000 to reseed the planet.