Crazy science question.

[Traab]

Just left the death star thread in media when an odd notion hit. Lets say the death stars super weapon hit earth. Instead of shattering it into an asteroid field, it literally punched a clean hole through the middle of the planet and out the other side. What effect would that have on the planet? For fun try and describe the effects if say, it completely obliterates the inner core, it punctures the inner core, or it manages to miss the inner core on its straight line in one end and out the other.

[Eldan]

I'm not a physicist, but I imagine the end result would be that Earth would settle down into a smaller sphere. The hole would almost certainly collapse, though I don't know how quickly or violently. Probably massive volcanoes and earthquakes.

[Max™]

Be a heck of a gun to core a planet without moving the pieces to infinity. A starbreaker might do something like that, but the sides of the tunnel shouldn't hold up too long, though I want to say it would "zip" itself back up from the outside in, as gravity is pulling the very center sections outward as much as inward.

[shawnhcorey]

Assuming the hole was created very quickly, most of the material from the hole would blast back to the cannon. You had better have good shields on the Death Star.

As material fell into the hole, the crust would break into ever-widening circles around the hole until it is broke into many small pieces, say 100 km to 1,000 km in size. About this time, a large jet of material would be forced out of both holes. For the next several years, the Earth would shake like Jello until the vibrations finally damped down.

Life would be very difficult. Aside from the earthquakes and volcanoes, there would be debris falling back from space. And that doesn't account of all the various toxic gases released from underground.

[Traab]

Could the planet actually recover from something like that though? I mean, I would assume losing the inner core of our planet would kind of ruin our day. But even with the other options at the very least the new massive craters on both sides of the planet would dramatically effect the environment, ignoring the likely multiple year long shroud covering the sky from all the debris, but once the proverbial dust settles, would the planet still be capable of sustaining life? It might even depend on where it hits. For example, how much of our oceans would we lose if the death star hit dead center in one? Would any land mass around the impact site even survive the likely crumbling effect of the hole filling in? Of course, that depends on how big of a hole we are talking about. If the initial blast hit in say, kansas, I wonder if america would become a nation separated by a massive pit stretching across the entire landmass.

[Ravens_cry]

The Planet? Yes. Planets are tough nuts to crack. Life existing after would be a different story.

[Tebryn]

Something that seems to have been missed is...what would happen with the atmosphere? A super hot blast of energy, strong enough to core a planet, couldn't leave the Ozone Layer in that good a state right?

[Ravens_cry]

Something that seems to have been missed is...what would happen with the atmosphere? A super hot blast of energy, strong enough to core a planet, couldn't leave the Ozone Layer in that good a state right?

I think that's the least of your worries.

[Eldan]

What about the magnetic field? How much would a hole through the core impact that? Any ideas?

[factotum]

If this hole is big enough to completely obliterate the core, then the planet is pretty much destroyed--we'd be talking a hole around 3500 miles across, and with the planet's diameter a bit short of 8000 miles, that's a pretty darned big hole! If the hole is only a few miles across then it would collapse almost instantly. Probably wouldn't completely obliterate the planet, but the energy release would almost certainly kill everyone and everything on the surface. Either way, I don't think the effects on the magnetic field would be a big factor in anyone's lives after that point.

[Jimorian]

A lot depends on exactly how much material was "removed". Setting aside direct damage as the result of that material vaporizing and escaping, creating a sudden cylindrical hole through the earth would release tremendous amounts of gravitational potential energy as the planet tried to reestablish a solid spherical shape that represented the new total mass.

Make the hole large enough, and the resulting collapse will essentially melt and liquify the entire crust again. It's very unlikely that the hole would last very long. At planetary scales, everything is "liquid", as even the so-called solid crust is barely stiff enough to support variances from a perfect sphere of .2% (8 miles up or down from sea level over a radius of ~4000 miles.

Later, I may try to work out the energy release based on a variety of hole diameters.

[Traab]

If this hole is big enough to completely obliterate the core, then the planet is pretty much destroyed--we'd be talking a hole around 3500 miles across, and with the planet's diameter a bit short of 8000 miles, that's a pretty darned big hole! If the hole is only a few miles across then it would collapse almost instantly. Probably wouldn't completely obliterate the planet, but the energy release would almost certainly kill everyone and everything on the surface. Either way, I don't think the effects on the magnetic field would be a big factor in anyone's lives after that point.

Ah, see, I didnt realize the inner core was THAT huge, I knew it would make a very very large hole, but that pretty much turns earth into a donut.

[Frozen_Feet]

One way to look at it would be to count how much material you'd have to remove. Earth's diameter is 12756 kilometers, so punching even a fairly small hole (around a meter, f. ex.) all the way through would require obliterating a cylinderic iron object of immense size and weight. That in turn requires helluvalot of energy. The waste heat alone would schorch the surface and boil away the atmosphere.

[shawnhcorey]

One way to look at it would be to count how much material you'd have to remove. Earth's diameter is 12756 kilometers, so punching even a fairly small hole (around a meter, f. ex.) all the way through would require obliterating a cylinderic iron object of immense size and weight. That in turn requires helluvalot of energy. The waste heat alone would schorch the surface and boil away the atmosphere.

Don't forget the blowback. All that material would come out of the hole at high speed, straight back to the laser.

[Kato]

Don't forget the blowback. All that material would come out of the hole at high speed, straight back to the laser.

Sorry, but.. why? I guess it depends on what evacuation mechanism we imagine... If we talk abut "we cook us some magma and get massive amounts of gaseous rock" I guess there'd be quite a bit of backfiring, yeah, but otherwise... would that even happen or would the pressure of the laser direct the flow out the other side? I honestly don't know.


Factotum's right, I wasn't aware the (outer) core was so huge. But I guess even a hole the size of the inner core would have pretty drastic effects on earth... If we talk about any clean shot through earth I'd wager it depends a lot on how large it is. As Frozen noted, a hole of 1m diameter (or radius, whatever in this case) would likely just collapse within a given time.

Magnetic field I think is pretty simple: It is widely accepted our magnetic field is created by our core, so no core, no magnetic field. Well, haven't used a compass in forever anyway. ([tangent] Before someone chops in on it: I think there are quite a few scientists of the opinion loss of the magnetic field wouldn't result in instantly burning us all with cosmic radiation, as is often proclaimed... it's happened often in the past and life survived. One theory from what I recall is our atmosphere interacting with the radiation creating its own shielding equilibrium... something. I forgot what exactly the mechanism was sorry [/tangent])

[shawnhcorey]

Sorry, but.. why?

All that material has to go somewhere, even if it's a gas. If you punch the hole thru quickly, there's going to be a very large, very dense blowback. If you don't do it quickly, the magma will continuously refill the hole.

[ChristianSt]

The first thing I thought while reading the question was: "Mh, I'm pretty sure I haven't seen that scenario on xkcd: what if?".

I don't know how Randall Munroe selects his topics, but I think it would be a fun enough question, so you could try to submit that question and get some nice pictures along the way

[Jay R]

Just left the death star thread in media when an odd notion hit. Lets say the death stars super weapon hit earth. Instead of shattering it into an asteroid field, it literally punched a clean hole through the middle of the planet and out the other side. What effect would that have on the planet? For fun try and describe the effects if say, it completely obliterates the inner core, it punctures the inner core, or it manages to miss the inner core on its straight line in one end and out the other.

An actual physical or energy attack would shatter the planet, not core it. Your question assumes a change in physical laws, and therefore cannot be answered by application of those laws.

[shawnhcorey]

An actual physical or energy attack would shatter the planet, not core it. Your question assumes a change in physical laws, and therefore cannot be answered by application of those laws.

In order to shatter the planet, it would have to turn the insides into very hot gas, which would push the surface outward. That would take a lot more energy than simply drilling a hole thru it.

[Max™]

From what I've read due to links in a recent What If? the amount of material removed from some of the largest open pit mines would be enough to drill at least a narrow tunnel through the planet.

The question of where the material goes is why I mentioned starbreakers, for those who never read any of the Xeelee stories, it's a focused beam of gravity waves, one of the first depictions was a delicate handgun with multiple settings, the low ones produce synchrotron radiation, the race which found it had been afraid to try the higher ones. Later in a panic they fired it on the highest setting at and through a stolen Xeelee Nightfighter which had arrived back in their system a little too close to their star for comfort (that's what my Avatar is, btw) and accidentally triggered a massive stellar eruption which took out their planet.

One of the stories describes a cylindrical crater with vertical walls on what was a colony moon around Jupiter or Saturn, forget which one.

Stands to reason that if you could make the material "fall" in the direction of the beam you could punch a core out and send it out the far side... though keeping the rest of the material around the impact point from following it is another matter.

Nice representation of the crust/mantle/outer/inner core scales:

Spoiler

Show

[Tebryn]

I think that's the least of your worries.

Well, part of the question was how would life handle it I thought. That matters I'd say.

[Knaight]

An actual physical or energy attack would shatter the planet, not core it. Your question assumes a change in physical laws, and therefore cannot be answered by application of those laws.

The question is about the aftermath. The getting there is nonsense, but if it is already in that state it can be handled with physical laws just fine.

[Jay R]

In order to shatter the planet, it would have to turn the insides into very hot gas, which would push the surface outward. That would take a lot more energy than simply drilling a hole thru it.

Simply untrue.

Take a rock and a hammer. Is it easier to shatter the rock, or to drill a hole through it?

Then look at the Moon. Did the asteroid that created the Tycho crater start a hole through the moon, or leave long stress rays way beyond the crater?

Then look at every astronomical body we've ever seen. Do we have any evidence at all for a possible hole drilled through one?

[Astral Avenger]

Simply untrue.

Take a rock and a hammer. Is it easier to shatter the rock, or to drill a hole through it?

Then look at the Moon. Did the asteroid that created the Tycho crater start a hole through the moon, or leave long stress rays way beyond the crater?

Then look at every astronomical body we've ever seen. Do we have any evidence at all for a possible hole drilled through one?

OTOH, people have pointed out that a hole through a planet/celestial body would collapse in on itself very quickly or make the entire thing go boom into a nebula or rocky, dusty cloud. Either way, we see a lot of nebulas and dusty clouds out there, and we also see a lot of very beat up planets out there.

[Tebryn]

Simply untrue.

Take a rock and a hammer. Is it easier to shatter the rock, or to drill a hole through it?

Then look at the Moon. Did the asteroid that created the Tycho crater start a hole through the moon, or leave long stress rays way beyond the crater?

Then look at every astronomical body we've ever seen. Do we have any evidence at all for a possible hole drilled through one?

I've never seen the after-effects of a DEW on a planetary body. I can't think that it would behave the same way as a giant asteroid however. Could be wrong though.

[factotum]

Ah, see, I didnt realize the inner core was THAT huge, I knew it would make a very very large hole, but that pretty much turns earth into a donut.

To clarify: that's the inner core *and* outer core. The Earth's magnetic field is generated by liquid movements in the outer core (the inner core is completely solid), so to seriously disrupt it you'd have to take both out.

Mind you, the inner core is still a good 900 miles across, which is still a significant enough fraction of the planet's diameter that the collapse of the remnants would certainly kill us all and destroy everything we've built.

[Kato]

To clarify: that's the inner core *and* outer core. The Earth's magnetic field is generated by liquid movements in the outer core (the inner core is completely solid), so to seriously disrupt it you'd have to take both out.

That's still at best a very likely theory.. I'm always intrigued with what certainty people claim to know about the make-up of the inside of our planet when we really mostly have to infer stuff from the little we know about it's surface. (Obviously not saying it's false, but taking it as die-hard facts...)

Mind you, the inner core is still a good 900 miles across, which is still a significant enough fraction of the planet's diameter that the collapse of the remnants would certainly kill us all and destroy everything we've built.

Oh, factotum, you old pessimist, there_s a decent chance a few of us might survive for a while and a few buildings could remain intact long enough for us to hide from the amounts of falling debris and live out their lives until the atmosphere collapses... which I guess it would do rather fast, I'll admit.

[factotum]

That's still at best a very likely theory.. I'm always intrigued with what certainty people claim to know about the make-up of the inside of our planet when we really mostly have to infer stuff from the little we know about it's surface. (Obviously not saying it's false, but taking it as die-hard facts...)

We know a lot more about it than that. They monitor the reflections of seismic waves travelling through the body of the planet and can see the discontinuities between different zones--that's how they know how big the inner and outer cores are, and their approximate densities.

[Comissar]

Not sure how relevant this What-if xkcd is, specifically the bit where the meteor is given the speed of the oh-my-god particle. The OP made me think of it, though.

[shawnhcorey]

Simply untrue.

Take a rock and a hammer. Is it easier to shatter the rock, or to drill a hole through it?

Then look at the Moon. Did the asteroid that created the Tycho crater start a hole through the moon, or leave long stress rays way beyond the crater?

Then look at every astronomical body we've ever seen. Do we have any evidence at all for a possible hole drilled through one?

You are forget the crust (that's the solid part) is only about 50 km thick. Most of the drilling would be thru the mantle, which is liquid, and the outer core, which is also liquid, before you get to the solid inner core. Everything under the crust is very hot and under extreme pressure. As soon as you punch a hole into one layer, it would instantly turn to vapour and be expelled out of the hole. And this would interfere with the laser beam and possibly damage the laser itself. Unless your laser is powerful enough to punch thru quickly, you would have to vaporize almost all of the mantle and outer core before you can start on the inner core.

And the inner core is solid only because of the pressure. Drill a hole down to it, and it too would instantly become a vapour.

To clarify: that's the inner core *and* outer core. The Earth's magnetic field is generated by liquid movements in the outer core (the inner core is completely solid), so to seriously disrupt it you'd have to take both out.

Mind you, the inner core is still a good 900 miles across, which is still a significant enough fraction of the planet's diameter that the collapse of the remnants would certainly kill us all and destroy everything we've built.

The crust is about 50 km thick, the mantle about 2900 km, the outer core 2250 km, and the inner core 1300 km.