If something like a giant sword were to slice cleanly through the Earth, what would happen? Aside from the obvious damage it would cause anything in the path of the blade, would anyone outside of its immediate zone even know something happened? Say it created a 5 ft cut through the Earth (which is really small relative to the Earth). Would the Earth immediately slam back together is almost the same exact shape it was before? Would you be able to feel anything anywhere else in the world or would you only notice it around where it happened?
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I don’t know but someone needs to get Randall Munroe to write a What If? about this.
It would be like cutting a pile of sand with a cheese wire
>Would the Earth immediately slam back together is almost the same exact shape it was before?
Yes. It would start as a sphere and reform as a sphere.
> Would you be able to feel anything anywhere else in the world or would you only notice it around where it happened?
There would be a massive global earthquake. It is hard for me to predict exactly how large it would be, but it seems like it would easily be the biggest disaster in human history.
Okay, I did some math. I’m not gonna post it all here because I’m lazy and writing on my phone, but if the assumption is that a 5ft gap is opened between two halves of the planet, and that the process imparts no energy on the earth itself, then the two halves slamming back together would release an amount of energy equivalent to 8 billion megatons of TNT, one thermonuclear warhead per person alive right now. So the surface of the planet gets vaporized, we all die, oopsie.
I ran it again on the assumption that something really tiny separates the two halves of the planet by 1 nanometer, and that one produces about 100 Tsar-Bombas worth of energy, or about a 1/5th of one second of the energy we get from the sun. So you’d maybe feel a rattle.
Ok, so what if the dividing force is like a cheese wire but so thin and “sharp” that it passes clean through with almost no resistance, 1m wide at the rotational poles, and it rotates with the earth, so its in geosynchronous rotation, its not consuming or destroying anything its so fine, just cleaving apart, would the effect be noticeable.
Knowing my luck, I’d be the guy in exactly the place it got cut.
It would slice me in two, right through my face and testicles and anus my friends.
I think the gravitational pull of each half would attract the other half with enough pull to join them back together again.
Great question 👍🏼
“Slice cleanly” is the key point here. If there’s no drag on the rest of the planet, the two halves would simply be drawn back together. The impact energy is then dependent on how wide of a gap you cut. (There would also probably be some damage at the edges of the cut, as the halves would be drawn inward rather than directly together, but if there’s gap is wide enough for that to have a significant effect then life on Earth is probably over anyway.)
Even if it did somehow reform and not breakapart….the sheer impact of such a weapon would cause so many other globe spanning issues. One being the earth would likely stop spinning for at least a few minutes if not longer…you can watch videos on YT that goes into that What If scenario.
Basically, the Earth would be rendered uninhabitable and otherwise destroyed before it could ever theoretically heal…and it’s highly unlikely it would heal.
The energy required to do this is would be enormous giant earthquakes and tidal waves at the least, maybe some new faults, might even make some brand new continents.
Earth has a molten core. I imagine it would start exploding once the immense pressure is released
i think the earth wouldnt immediately come back together. At depths of hundreds and thousands of kilometers the material is so compressed, it would rapidly expand from immense pressure to fill this 5 ft gap
Tectonic plates
Youd have new fault lines and probably enough earthquakes to end all life
We would finally know what’s at the center. I bet it’s chewy
Follow-up question. Assuming that a 5 foot wide section of earth is removed, would the resulting loss of mass have any noticeable effect on the earths and moons respective orbits? Just how much mass would the planet lose?
Based on a little back of the envelope math, assuming uniform hemispheres, this would release around 10^25 joules of energy, aka around 200,000,000 times the yield of the most powerful nuclear weapon ever detonated
Wouldn’t a substantial amount of the atmosphere be immediately sucked into the void caused by the five-foot gap and then violently expelled as the two hemispheres came crashing back together? Seems dangerous.
No one would be able to feel it, we’d all be dead before notice anything happened.
Is there air in the gap created or not?
The five foot gap is huge in that you now have two different masses with two different centers of rotation with lots of rotational inertia. The earth is not slapping back together in any kind of equal flat on flat surface. The two halves would still spin from their new centers of rotation and and crash into each other over smaller surface areas.
The planet would be seriously wrecked with it braking up into pieces and drawn out as a ring around the sun.
Doubtful about “immediately,” there’s a lot of pressure under (and throughout) the surface. I imagine you’d have quite a bit of magma leaking out of the crack. Although it would probably cool before very long and you’d end up with s volcanic scar around the planet. Probably a burst of humidity too. And heat. You’d have new fault lines, probably even some plate shifting just after the cut happens
People are answering as if the entire half of the Earth would move at once, which it wouldn’t. Aside from the (negligible) sudden difference in gravity, the effects would propagate at the speed of sound in the material.
At the cut on the surface, you’d have the sides collapse inwards, like a really long sink-hole. In ocean areas, you’d get a wall of water shooting up. In both cases, followed shortly by a wall of magma shooting up.
Most of the damage will probably be close to the cut, but it would seal itself fairly quickly. The other place you’d get surface damage would be at the axis perpendicular to the cut (eg the poles if it was cut along the equator). The shockwave from the two halves of the core slamming together would reach the crust in about 10 minutes. At that point, any concept of “solid ground” would disappear as the crust is ejected into the sky.
So there’s not enough info to answer the question as-is but I can gladly tell you if you supply some information:
So for example, a scenario I thought up was a very long, thin filament made of neutronium (neutron star stuff, basically unbreakable). It’s 25,000km long but only 10,000nm wide (basically a human hair), as slick as teflon and it’s floating in space right in the Earth’s orbital path but stationary to the Earth.
Earth would slam into it at 30km/s. The filament would cut clean through the Earth in 423 seconds. I’m not going to show the math, you’ll just have to trust me. This produces 1.52×10^(12) N of friction, mostly as heat but also as sound. Once it’s traversed the entire Earth that friction has released 1.93×10^(19) J of energy over 423 seconds, or ≈4.56×10^(16) Watts per second. That’s about 100 Hurricane Katrinas worth of energy, per second. It would be like a 10.8 megaton nuclear bomb going off every second for 7 minutes but in a line passing over the Earth.
That being said, the damage isn’t that bad, the Earth seals up the ~22mm cut within seconds and goes on being a planet.
This scenario gets really nutty if you increase the friction, speed, make it spin etc
I think a substantial majority of the Earth’s volume would indeed just reconnect and fuse itself together. A lot of the inside is super hot, under a lot of pressure and thus flows like taffy or thick cream depending on the depth. Cleaving the globe doesn’t negate gravity after all.
In fact, almost all of it would reconnect before you even finished the cut.
The real problem is the Earth’s crust. Most of that won’t rejoin. Instead it will become like a fault line, only one that goes deep enough to create a super-volcano.
What you’d end up with is a world girdling chain of super volcanoes that erupt until enough magma accumulates and cools enough to seal the crack like window caulk.
Which would likely be a super extinction level event for all chordate life.
Somebody get xkcd on this.
While not quite the same, your question is in the same ballpark as the plot of Seveneves by Neal Stephenson. But it’s the moon splitting into seven pieces. Spoiler alert, things don’t go back together smoothly.
5mm separation got me energy release when the two halves “slam back” simmilar to energy release of asteroid that killed dinosaurs.
Please don’t play with your planet cutting sword.
No. I’m not clever in planetary geology though, but I’m sure I’m right.
Is the sword a samurai or English medieval one they cut differently so would have an impact on the size of the earthquake and tsunami that follows
I’m no scientist. But I would think if it was sliced cleanly in half, like razor thin. I think gravity would just press it right back together without much issue.
Most of the earth is liquid/molten, so it would probably never really be sliced.
The moment the earth is split, you would have two halves which are not rotating about their centre of mass in a stable manner. It would be a violent affair, similar to a phone or joystick vibrator. The centripetal force suddenly ceases to exist at one point and originates at another, so these two horribly vibrating halves would collide like a low five and try to scoop into each other. It would try to be stewie head shaped but fall way short as a molten deformed ball.
I think we need to define the speed at which the cut occurs as well as what happens with the material at the cut. This is also assuming that the pressure of the separated earth does not cause the blade to bind halfway through. And that it stays sharp enough.
If its instantaneous and that material just disappears, then there is a 5 ft gap that smarter people have calculated the energy that would be created by the 2 halves closing that gap.
If we have a more gradual cut speed, say 8 hours to cut through the whole thing (Blades still moving ~1000mph!), and the material is simply seperated, I think it would be more like cutting sushi. The earth is mostly malleable on a planetary scale, so the moved material could just backfill in on itself and mitigate the energy created by closing the gap. Massive earthquakes still, but I think maybe initially survivable? You’re also probably looking at a planet wide new volcano forming that feels…less survivable.
If we are moving gradually and the material is being removed, ala a circular saw blade’s kerf, we’d have a 5ft hole encircling the earth, collapsing in on itself in places and opening up that volcano in others.
And then you’re going to get eaten by the earth and all you can think is “Great, now I dont have to go to work tomorrow.”
This is a question for kurzgesagt, they just did a video on silly questions but answered scientifically: https://youtu.be/tRXy-b6_lBc?si=Q3y2dGLoWomE3LbJ
All life would be destroyed and they are now two separate objects that will probably float apart from the impact.
Anything in the path would be obliterated but if you’re not in the sword’s path, you’re probably okay until the Earth gets mad and throws a natural disaster party, it would be a total chaos. Eventually, stuff would settle down, but the scars would be insane. You’d definitely see a gnarly line around the planet, maybe even a permanent crack or canyon if the sword left a gap before Earth clapped shut.
First of all, DON’T PANIC.
Yes. All objects with mass attract each other. If you put two baseballs next to eachother in outter space, they would attract to each other unless a more powerful force kept them seperated.
Two giant halves of earth would move back together.
I would think that if the sheer force of the impact to actually slice the Earth into two pieces did not cause the entire thing to explode from the inertia then i would image it would mostly reform but due to the force of the impact would go spiraling out of the solar system.
If you mean slicing at the level of atoms, it would be immaterial to us if it fused back, because what remains would be irradiated dust.
If you mean cutting in the non-atomic sense, the speed necessary to cut through the mantle and core would result in a non-nuclear explosion that still completely obliterates life as we know it. Ejecta orbiting the planet for millennia, perhaps, suffocated under gray skies while the planet burns awhile.
l don’t know what the hell you ScyFi addics are talking about? Where is Rod Serling? He could use your material.
The amount of energy required to slice through the earth’s core is probably greater than 100 trillion nukes, no matter how thin the giant sword is. The core of the earth might stay intact due to it’s unbelievable density—but I believe everything outside the core (99.3% of the planet’s volume) would be more or less atomized.
It would reform into a sphere and pretty much everybody would die.
I think everything would be in terrible conditions lmao