'Slicing up' planets

Balrog · Post by **Balrog** » 2007-11-03 02:27pm

Something I've been curious about: supposing one day a starship comes by Earth and, for shits 'n giggles, uses its big energy beam gun to cut completely through the planet and hacked off a chunk, i.e. less the cutting the world in half, but more then simply scrapping off the crust. Obviously it would be a Very Bad Thing for the planet, but what would be the exact effects be? How much would the size of the piece matter?

And on a similar note, suppose instead of slicing off a chunk it simply targeted one spot and shot a hole through Earth. Would there be any difference if it punched through the core or not?

Admiral Valdemar · Post by **Admiral Valdemar** » 2007-11-03 02:39pm

This depends on magnitude. How much is it slicing off? How big a hole does the beam punch into the planet's heart?

Seggybop · Post by **Seggybop** » 2007-11-03 02:45pm

If it simply sliced through, I don't think it would actually do much immediately. The chunk would be held in its original position by gravity. There would probably be some severe earthquakes from tectonic plates being subdivided though.

Admiral Valdemar · Post by **Admiral Valdemar** » 2007-11-03 02:52pm

I'm assuming the piece is removed, since you'd need a sizeable force to overcome gravity, much like the molecular bonds negating monofilament wires.

Balrog · Post by **Balrog** » 2007-11-03 02:52pm

Admiral Valdemar wrote:This depends on magnitude. How much is it slicing off? How big a hole does the beam punch into the planet's heart?

Alright, let's say the chunk is 1/4 the Earth's mass using a beam 100m in diameter. The hole is the same width and goes completely through.

Junghalli · Post by **Junghalli** » 2007-11-03 03:24pm

You wouldn't be able to "hack off" a piece of a planet because planets are basically held together by nothing but gravity anyway. Slicing a beam through a planet will do nothing but create a very long continuous crack in the ground. In the case of a planet like Earth the crack will probably fill with lava and you'll have a new tectonic rift where the beam went in. The beam is similar. You'll create two new circular volcanic rifts on either side of the planet.

Now assuming you somehow teleport away a slice of the planet... Planets are spheres because that's the only stable shape for an object with that much self-gravity. Take a chunk of it out and the planet quickly collapses back into a stable shape i.e. a smaller sphere. Needless to say we all die, as the surface probably gets flooded with lava in this process. Taking out a slice through the center is trickier as it alters the planet's center of mass, but my best guess is the same thing happens.

Darth Servo · Post by **Darth Servo** » 2007-11-03 03:27pm

If the chunk is "fundyland, USA" this might not be such a bad thing.

Zablorg · Post by **Zablorg** » 2007-11-03 05:35pm

I think, and this is from someone who has absolutley no education in gravity and such, that assuming it is actually torn apart;

The people on the far out bits of the semispheres will float off, while the people in the middle live as normal, albiet with severely reduced gravity...and air.

Zablorg · Post by **Zablorg** » 2007-11-03 05:37pm

Also, yeah, how much time would it take for the semisphere to start re-combobulating itself into a shape more stable?

Junghalli · Post by **Junghalli** » 2007-11-03 08:15pm

Zablorg wrote:Also, yeah, how much time would it take for the semisphere to start re-combobulating itself into a shape more stable?

About as long as a cliff 6,371 kilometers tall could hold up. The edges of the removed section will instantly begin to collapse in the mother of all landslides. The only real delay would be in how long it takes all the rock and lava to shift around until it makes a sphere again.

I really doubt anything could survive on the surface. Huge sections of the crust are going to literally collapse into the center of the planet, and even parts that don't are going to be turned into a lava-oozing mess as the magma literally drains away under them and they collapse and contort like the skin of a raisin. When it's all over Earth is going to look like it underwent a BDZ.

Zablorg · Post by **Zablorg** » 2007-11-03 08:32pm

The cockroaches *will* survive though.

They always survive.

Post by **Darth Wong** » 2007-11-05 01:07pm

Balrog wrote:How much would the size of the piece matter?

If we are not fixated on any particular size, then mankind has already developed weapons that can slice a chunk out of the Earth. They're called shovels.

OmegaGuy · Post by **OmegaGuy** » 2007-11-05 03:27pm

This sounds similar to the Doomsday Machine from TOS

Too bad we never got to see the actual effect it had upon the planets, or did they add that in the CGI updated version?

Balrog · Post by **Balrog** » 2007-11-05 05:25pm

Darth Wong wrote:
Balrog wrote:How much would the size of the piece matter?
If we are not fixated on any particular size, then mankind has already developed weapons that can slice a chunk out of the Earth. They're called shovels.

Balrog wrote:i.e. less the cutting the world in half, but more then simply scrapping off the crust.

Unless we have some mighty big shovels...

Steel · Post by **Steel** » 2007-11-06 03:13pm

Probably the most accurate model of this would be to take a cadburys creme egg and a handgun. You can guess the rest. for the other experiment perhaps a meat cleaver would be useful.

This would demonstrate what happens when you punch a hole through an object with a 'soft' inside and a solid outside. The problem is that unless you teleport away all the mass any beam that could accomplish the task of blowing a hole through the planet is going to have an effect similar to the death star...

Junghalli · Post by **Junghalli** » 2007-11-06 04:21pm

Steel wrote:This would demonstrate what happens when you punch a hole through an object with a 'soft' inside and a solid outside.

At the kind of stresses we're dealing with it really doesn't matter if the planet's inside is "soft" or "hard". A planet that was solid rock all the way to the center would react basically the same way, as would a gas giant.