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Astronomer
01-15-2011, 07:30 AM
So how would you destroy a planet? And you must use scientifically plausible means.

If you were stationed on the moon, and you were tasked with destroying Earth, how would you do it? You can have as many chemical elements as you want in any quantity. What would you construct, launch, or ignite to destroy Earth from the moon?

If you destroy just the biosphere (every living thing), you get only partial credit.

Since you're stationed on the moon, you would ideally like to remain standing after you've accomplished your planetary destruction, so keeping the moon intact is desired. But, megalomania being what it is, you won't be penalized if you sacrifice the moon (and yourself) in your bid for global destruction.

So let's have it. What's your plan?

DaveKuzminski
01-15-2011, 07:41 AM
Develop a missile capable of burrowing down to the core of the planet where it would then detonate thus setting off seismic waves within the liquid core thus demolishing the planet from within. It's the same principle as filling a safe with water and then using a small explosive charge as demonstrated on Mythbusters because there's then more for the charge to push against.

Lhun
01-15-2011, 08:38 AM
So how would you destroy a planet? And you must use scientifically plausible means.What exactly do you mean by destroy? I.e. what should it look like afterwards?

Cheapest method: use a really, really big mirror to reflect sunlight on it, and completely vaporize it.


Develop a missile capable of burrowing down to the core of the planet where it would then detonate thus setting off seismic waves within the liquid core thus demolishing the planet from within. It's the same principle as filling a safe with water and then using a small explosive charge as demonstrated on Mythbusters because there's then more for the charge to push against.Unfortunately, doesn't work. A planet is nothing at all like a water filled safe on a planet.

movieman
01-15-2011, 08:47 AM
The traditional method is to build a huge mass-driver to fire relativistic rocks, using a significant fraction of the sun's output to power it. But you probably couldn't manage that on the moon.

The mirror is an interesting idea: ultimately you need to throw a huge amount of energy at the planet in order to break it apart against gravity and the sun is the only place you're likely to get that from. The question is really just how you convert solar power into planet-busting power.

Sharii
01-15-2011, 10:52 AM
Find a suitable meteoroid and change its course (using small impact to deflect it?) to hit the planet. The moon's survival? Not guaranteed.

Lhun
01-15-2011, 02:48 PM
The moon can only survive if the planet stays intact and only the biosphere gets wiped out.
Everything that will scatter the planetary mass across the orbit, or even solar system, will take the moon with it.
The very best that could happen is that the moon goes flying off, since the planet is was orbiting is kinda missing. Depending on the relevant sizes and speeds, anything could happen, from it crashing into the star, to it settling into its own, wider orbit around the star, at least until it gets swept up by an outer planet.

richcapo
01-15-2011, 07:33 PM
I originally saw this article on destroying the Earth on livescience.com, but it has apparently since been taken down from there. It's a great article, in my opinion, and I think you guys should enjoy it.

http://qntm.org/destroy

The website has asked readers not to paste any more than the article's prologue on other sites, so you'll need to go to that link to see what comes after the following text:

Preamble

Destroying the Earth is harder than you may have been led to believe.


You've seen the action movies where the bad guy threatens to destroy the Earth. You've heard people on the news claiming that the next nuclear war or cutting down rainforests or persisting in releasing hideous quantities of pollution into the atmosphere threatens to end the world.


Fools.


The Earth is built to last. It is a 4,550,000,000-year-old, 5,973,600,000,000,000,000,000-tonne ball of iron. It has taken more devastating asteroid hits in its lifetime than you've had hot dinners, and lo, it still orbits merrily. So my first piece of advice to you, dear would-be Earth-destroyer, is: do NOT think this will be easy.


This is not a guide for wusses whose aim is merely to wipe out humanity. I (Sam Hughes) can in no way guarantee the complete extinction of the human race via any of these methods, real or imaginary. Humanity is wily and resourceful, and many of the methods outlined below will take many years to even become available, let alone implement, by which time mankind may well have spread to other planets; indeed, other star systems. If total human genocide is your ultimate goal, you are reading the wrong document. There are far more efficient ways of doing this, many which are available and feasible RIGHT NOW. Nor is this a guide for those wanting to annihilate everything from single-celled life upwards, render Earth uninhabitable or simply conquer it. These are trivial goals in comparison.


This is a guide for those who do not want the Earth to be there anymore.

Astronomer
01-15-2011, 09:05 PM
What exactly do you mean by destroy? I.e. what should it look like afterwards?That's a fair question. I propose the following:

Grade A+: Explode Earth into tiny fragments, just like in the movies.

Grade A : Explode Earth into pie-shaped fragments, just like in the cartoons. (This, of course, comes with the realization that the pie-shaped fragments will fall back together to reform the planet, but at least it will be an uninhabitable shadow of its former self. And, personally, I don't think pie-shaped fragments are even possible. Pie -- and I'm talking the apple/pumpkin variety -- just doesn't scale like that.)

Grade B : Convert Earth into a boiling, molten mass. Just melt the crust, and you're there. Easy!

Grade C : Destroy all life. This includes all cockroaches and bacteria.

Grade D : Put someone's eye out.

Grade F : Anything less than putting someone's eye out, and you get a failing grade.


Lhun, what took you so long? It's always good to have you chime in. Your comments are, of course, 100% spot on, which makes me think we could get a two-fer by destroying Earth, and then sending the moon off to smack into Mars. The more I think about it, the more I like that idea.

So thanks to you, I now realize that, as with comedy, in planetary destruction, timing is everything.

Misa Buckley
01-15-2011, 10:16 PM
So how would you destroy a planet? And you must use scientifically plausible means.

Have the sun die and let nature take its course.

It takes a while, but the planet will eventually be destroyed. Right along with the rest of the solar system.

Misa, who thinks big.

Astronomer
01-16-2011, 01:40 AM
Misa, that's actually the method I used in my most recent novel. It's not a technique for the impatient, that's for sure. :)

LBlankenship
01-16-2011, 02:11 AM
And you must use scientifically plausible means.

I'd keep an eye on the news from CERN and see if they manage to make any baby black holes... if that becomes plausible, then I'd go with creating a temporary black hole in the center of the Earth.

Pistol Whipped Bee
01-16-2011, 02:23 AM
I'd construct a black hole. Isn't the earth covered in teeny tiny ones already?

Amadan
01-16-2011, 02:33 AM
The problem with "destroying" a planet is that even if you break it into a hundred billion itty bitty pieces, those pieces still have the same mass (and thus the same gravity) as the planet, which means they are going to stay right where they are and compress into a planet-sized mass again. When the Death Star blows up Alderaan, you wouldn't really get an asteroid field, you'd get a big rocky planetary sphere.

So if by "destroy" you mean "remove the actual physical planet," I think the only way is by some sort of outlandish super-science that can actually destroy matter on a planetary scale. (Even "disintegration" wouldn't do it, if disintegration means reducing to dust, since you'd still have a planetary mass worth of dust reforming into a solid body.)

Lhun
01-16-2011, 04:04 AM
Grade A : Explode Earth into pie-shaped fragments, just like in the cartoons. (This, of course, comes with the realization that the pie-shaped fragments will fall back together to reform the planet, but at least it will be an uninhabitable shadow of its former self. And, personally, I don't think pie-shaped fragments are even possible. Pie -- and I'm talking the apple/pumpkin variety -- just doesn't scale like that.)You're right that it doesn't work. At the energy levels involved at this size, you can consider rock a liquid. The rigidity of even the hardest material is nothing, compared to the shear or even just inertia a mass the size of earth (or just a large fragment of earth) can can produce.

Grade B : Convert Earth into a boiling, molten mass. Just melt the crust, and you're there. Easy!

Grade C : Destroy all life. This includes all cockroaches and bacteria.This is kinda the same. There are bacteria that can damn near live in molten rock (and others some eat radiation!) so you'll really need to melt the whole surface to sterilize earth. And melt it white-hot, not red-hot, just to be on the safe side.

Lhun, what took you so long? It's always good to have you chime in.While i'm online at all hours, i'm not online permanently.

Your comments are, of course, 100% spot onThanks, i try. ;)

The site richcapo is really good for this topic. I couldn't spot any real mistakes (though i have a few things to nitpick about).
About the microscopic black hole, two more things need to be said (especially since it came up in this thread). For one, to avoid evaporation, one needs a size that's not only above the instant evaporation limit, but one given by the density of material around it. I.e. every black hole slowly evaporates at a rate determined by its surface area. And it absorbs matter depending on its surface area and mass as well as amount of surrounding matter. So the black hole needs to be big enough to allow it to swallow enough matter from the earth to outweigh the constant evaporation. Fortunately, the matter inside a planet is quite dense.
The second thing is that starting with a black hole that's as small as possible (since that's as easy to create as possible) will take a really, really long time. The thing is so tiny in the beginning that it will only swallow a couple of atoms every time it passes through earth. It could take hundreds of thousands of years for earth to be swallowed completely. Imagine it this way: once the black hole has swallowed all the mass of earth, it'll still only be a few millimetres large. Imagine how long it would take to absorb the earth one millimetre thick rod at a time, and then remember that it's only that "big" once it done, at the beginning it is much, much smaller. Heck, it would already take a long time for the black hole to grow big enough to swallow more matter each year than the earth gains from asteroid impacts. ;)
The growth is exponential, but exponential with a really really tiny base, so if one wants to destroy earth in a timely fashion one needs to start out with a bigger black hole.

The other thing to nitpick about is that earth, if vaporized, doesn't really turn into a gas cloud. Earth isn't massive enough to form as a gas planet, let alone one with the internal pressure of gaseous iron. If earth is turned into vapour, the internal pressure will cause it to dissipate.

Really useful are the section about blowing up the earth. The amounts of antimatter required kinda illustrate just how big the gravitational pull is.

Astronomer
01-16-2011, 04:31 AM
The thing is so tiny in the beginning that it will only swallow a couple of atoms every time it passes through earth.
I'll go even farther and say that a tiny black hole (assumed to be created by smashing two atomic nuclei together at mind-blowing energy levels) is even too tiny to absorb a single proton. The event horizon diameter will be nothing compared to a proton, and even if the tiny black hole were to pass directly through the center of the proton, there's not enough gravity (it's just two lead nuclei, remember?) to pull the entire proton's mass within its own Swarzschild radius so it can be absorbed. It would be rather like trying to suck a soccer ball through a straw with the strength of half a lung.

So black holes -- at least subatomic ones -- are definitely out.

FOTSGreg
01-17-2011, 02:17 AM
How about opening up a "white hole" at the planet's core?

Yeah, theoretically not very plausible, but still a possibility within certain plausible theories.

Al that energy assumed to be pulsing out of a white hole would bow the planet apart pretty quickly I would think.

Lhun
01-17-2011, 02:35 AM
The opening is less of a problem than white holes being completely fictional. ;)

LBlankenship
01-17-2011, 03:04 AM
I'll go even farther and say that a tiny black hole (assumed to be created by smashing two atomic nuclei together at mind-blowing energy levels) is even too tiny to absorb a single proton.

Aside from the amusing image of a black hole choking on a proton... does it have the strength to rip the proton apart and then eat it?

Skyler
01-17-2011, 04:26 AM
Hmm... crash the moon into the Earth? Even if it doesn't completely destroy the Earth, if you do it right you could probably destabilize its orbit and send it spiraling towards the Sun. In which case, it would probably explode into tiny fragments. Just like the movies.

The time scale you'd be looking at may not fit your bill. But then again, steering the moon into the Earth would probably kill just about anything alive in the first few hours. The remaining bacteria/cockroaches probably wouldn't have time to develop the technology needed to reverse the planet's doomed trajectory before being vaporized in a giant molten nuclear furnace that practically defines "overkill".

Daniel A. Roberts
01-18-2011, 03:47 AM
I would create the reverse fission catalyst that targets both hydrogen and oxygen and separates the atomic bonds so the elements divide independently from each other. Following that up with an ignition sequence would detonate the independent super concentrated gases.

Basically every ounce of water including the ice on Earth would destabilize into free form oxygen and hydrogen with the speed of nuclear fission, only it's nuclear fraction. The moment it's done, usually within seconds, the ignition would trigger the global now super condensed atmosphere into an explosion.

I'm not sure it would blow the planet into pieces, but considering the amount of ice and water on the Earth compared to the land mass, I'm sure you'd lose everything down to the mantle, at least.

Lhun
01-18-2011, 04:21 AM
I would create the reverse fission catalyst that targets both hydrogen and oxygen and separates the atomic bonds so the elements divide independently from each other. Following that up with an ignition sequence would detonate the independent super concentrated gases.Leaving aside that this is total magic ;), The energy required to split water is exactly the same as the energy produced when producing water, so you wouldn't get a big explosion, but a really really frozen planet.

Daniel A. Roberts
01-18-2011, 07:54 AM
Leaving aside that this is total magic ;), The energy required to split water is exactly the same as the energy produced when producing water, so you wouldn't get a big explosion, but a really really frozen planet.

Advanced science always appears as magic. Nuclear fraction works almost identical to nuclear fission.

Take fission with the U235 atom. When split by a neutrino, three more neutrinos are emitted, heat is released etc etc.

Fraction doesn't use a neutrino, but a radical proton. Meaning it's a proton that has broken free of it's atomic orbit and is related to the electrons that bind hydrogen and oxygen. Those electons get smashed by the radical proton when introduced by a molecular catalyst and they release anywhere from 3 to 5 more radical protons which react against more related electrons.

A related electron is keyed to the pion signature that is related to two or more elements that form a compound. Not all electrons are created equal on the subatomic level. It's why a magnet can attract steel and not your skin. The magnetic lines of force are related to the molecular structure on a subatomic level and they attract each other.

Finding the relationship that fuses hydrogen and oxygen and then shattering that relationship with a radical proton that is keyed to that relationship and you get nuclear fraction.

Using an electric current to break those bonds does exactly what you suggested. This is not using eletrical means. It's a chemical catalyst that is self sustaining, much like the fission inside a nuclear core. Without control rods in a core, you get the China Syndrome. There are no control rods that absorb radical protons. The Earth would be screwed in a heartbeart.

The only challenge in the research is finding the correct radical proton with the proper relationship to the chemical compound H2O and a magnetic jar to house enough of them to start a chain reaction when exposed to the substance. Only about a few million at the most, which is a tremendously low count compared to standard fission.

But I don't expect acceptance of that process. Many people who go down rarely explored avenues of science don't get support. Lots of naysayers. If they were listened to, Edison would have given up on trying to invent the lightbulb after his 10,000th failure. But then Edison refused to count those as failures and told folks that he learned 10,000 ways to 'not' make a lightbulb.

:D

Lhun
01-18-2011, 08:26 AM
Advanced science always appears as magic.No it doesn't. Clarke's third law is bullshit, just because a well-known SF writer said something doesn't make it correct.

Take fission with the U235 atom. When split by a neutrino, three more neutrinos are emitted, heat is released etc etc.You mean neutrons i gather.

Fraction doesn't use a neutrino, but a radical proton. Meaning it's a proton that has broken free of it's atomic orbit and is related to the electrons that bind hydrogen and oxygen. Those electons get smashed by the radical proton when introduced by a molecular catalyst and they release anywhere from 3 to 5 more radical protons which react against more related electrons.I'm not really sure if you're just misusing the names of subatomic particles here, or making stuff up. Protons have no atomic orbit, they're parts of the nucleus. Electrons can't get "smashed" by protons. Electrons also can't release protons if "smashed", by virtue of being about two thousand times smaller.

A related electron is keyed to the pion signature that is related to two or more elements that form a compound. Not all electrons are created equal on the subatomic level. It's why a magnet can attract steel and not your skin.I have no idea who told you that, but if it was any kind of physics teacher, fire him. And "keyed to pion signature" belongs on StarTrek.

The magnetic lines of force are related to the molecular structure on a subatomic level and they attract each other.No they're not.

Finding the relationship that fuses hydrogen and oxygen and then shattering that relationship with a radical proton that is keyed to that relationship and you get nuclear fraction.I'm sorry to sound rude, but that's total rubbish. Hydrogen and oxygen aren't fused in water. If you fuse hydrogen and oxygen, you end up with highly radioactive flourine, and shortly after, with oxygen again. And in water, there is no relationship to shatter, it's a quite simple covalent bond between two hydrogen and one oxygen atoms.

Using an electric current to break those bonds does exactly what you suggested. This is not using eletrical means. It's a chemical catalyst that is self sustaining, much like the fission inside a nuclear core. Without control rods in a core, you get the China Syndrome. There are no control rods that absorb radical protons. The Earth would be screwed in a heartbeart.No, sorry, farther from reality than recalibrating the main reflector dish again.
Whatever means you'd use to break up a molecule, the same amount of energy that was released when it was created, needs to be put in when it's broken apart. If that amount is bigger than 0 there's no catalyst. It's the first law of thermodynamics, kind of the most fundamental of all, aka: from nothing comes nothing.
Fission has nothing whatsoever to do with a chemical catalyst. It isn't even concerned with chemistry.
Protons, being charged particles, are much much easier to block than neutrons. The massive control rods inside nuclear reactors are only required to block neutrons because those, being neutral, will fly in a straight line, undisturbed by anything around them (except gravity). So you need a lot material to make sure the neutron hits something. For a proton, you just need a little electric charge, or even a magnet, and it will fly where you want it to.

The only challenge in the research is finding the correct radical proton with the proper relationship to the chemical compound H2O and a magnetic jar to house enough of them to start a chain reaction when exposed to the substance. Only about a few million at the most, which is a tremendously low count compared to standard fission. Fun fact: Proton beams are being used for cancer radiation therapy.

But I don't expect acceptance of that process. Many people who go down rarely explored avenues of science don't get support. Lots of naysayers.Oh please don't try that excuse. It's the last retreat of kooks and cranks since ancient times and will immediately associate you with them, even if you don't deserve it. Sure people laughed at Galileo. But people laughed at Boffo the clown as well, and if someone gets laughed at, odds are he's the next Boffo, not the next Galileo. Because there's millions of Boffos for every Galileo.

If they were listened to, Edison would have given up on trying to invent the lightbulb after his 10,000th failure. But then Edison refused to count those as failures and told folks that he learned 10,000 ways to 'not' make a lightbulb.Edison solved an engineering problem. Science works differently. There is no possibility of future science radically breaking known physical laws. The laws describing how the things work that we understand will never radically change, because if they did, we'd see all those things behave differently. Gravity causes things to fall to the center of the local mass, not downwards. That law will never be shown to be false because if it wasn't true, the aussies would fall off the earth. And they don't.
There might be some change in the understanding of why gravity works that way (that's how the discovery of DNA changed genetics) or some refinement that allows more accurate predictions (that's what Einstein did to mechanics) but there's never any radical turning-on-its-head.

Dommo
01-18-2011, 09:51 AM
To score an A is basically impossible.

To score a B, you'd just need a good sized relativistic kill vehicle, or a suitably large asteroid. Get something with like a million tons of mass up to around .5 C, and then let hit something earth sized. The crust would probably be liquefied, and a lot of the atmosphere stripped off.

Toimu
01-18-2011, 06:22 PM
Put humans on it and wait a few hundred-thousand years.

Without the Earth, the Moon will not last long until it runs into something.

Daniel A. Roberts
01-18-2011, 06:45 PM
To score an A is basically impossible.

To score a B, you'd just need a good sized relativistic kill vehicle, or a suitably large asteroid. Get something with like a million tons of mass up to around .5 C, and then let hit something earth sized. The crust would probably be liquefied, and a lot of the atmosphere stripped off.

Exactly! Using science facts as we know them today to try and solve a completely fictional goal is nearly impossible. Blowing the planet into bits with our current level of understanding isn't going to happen.

Even using such a kill vehicle would have to happen on its own too. We do not have the means to find a large enough rock out there and get it propelled up to half the speed of light.

And Lhun, my apologies. If I thought for a moment you were going to be so tripped over an obvious act of fiction, I would have put in a disclaimer. My point being that one has to go way out on a fictional limb to get graded an A on the scale provided. Nuclear fraction is only a theory I read about back in the 80's during college and not even aligned with any of the terminology I used.

I'm a writer challenged to do the realistically impossible for an A score. Of course I'm going to use fiction to do it as it's the only way to make the impossible remotely possible.

Lhun
01-18-2011, 09:38 PM
And Lhun, my apologies. If I thought for a moment you were going to be so tripped over an obvious act of fiction, I would have put in a disclaimer. My point being that one has to go way out on a fictional limb to get graded an A on the scale provided.This is the science fact subforum. Just making stuff up and saying the earth explodes because of it is what the main fantasy forum is for, and i wouldn't want anyone mistaking pure fiction for real because it's located in here instead. It is perfectly possible, as has been demonstrated up-thread, to figure out how one could make the earth explode realistically. Whether it's feasible, let alone whether we're currently capable of it is a completely different question than whether it's realistically possible.

Nuclear fraction is only a theory I read about back in the 80's during college and not even aligned with any of the terminology I used.It's not a theory, it's at best some wild hypothesis. And it would have been the same during the 80s, nuclear physics isn't that new.

Astronomer
01-21-2011, 07:42 AM
All it takes is energy to blow a planet to smithereens. We can't master enough of it, though.

How about this: build a rail gun on the surface of the moon pointing in the direction of its orbit around Earth. Fire moon rock after moon rock off the moon's surface, diminishing the moon's angular momentum. Over a long enough period of time, the moon will spiral in and crash into Earth.

How much of the moon is left when it smashes into Earth depends on the amount of power you can feed your rail gun.

Skyler
01-24-2011, 07:08 AM
I like how that's pretty much the same as my idea but with a mass driver. =)

lpetrich
02-01-2011, 02:54 PM
Seems like we have several different possibilities. Let's evaluate each of them.

Make the Earth disintegrate

One must supply enough energy to balance out the Earth's gravitational binding energy:
E(bind) = (1/2) * integral over volume of (density)*(gravitational potential)
= - (1/2) integral over radius r from 0 to infinity of (mass inside r)2

Using the Earth's interior structure, I find it to be 1.08 * the constant-density case, or 2.43*1032 joules or 2.71*1012 metric tons (remember E = mc2). That's still 4.5*10-10 the mass of the Earth, or less than 1 part in 2 billion.

That's a lot of energy, so let's see how it compares to more accessible forms of energy.

Checking on Solar luminosity - Wikipedia (http://en.wikipedia.org/wiki/Solar_luminosity), it is 3.839*1026 watts, or over 4 million tons of light per second.

It would take a week for total sunlight to equal the Earth's binding energy.

So we must dismiss Death Star vs. Alderaan as fantasy.

Melting the Earth

It's much more difficult to quantify that, since the Earth's interior temperature is not very well-known. But the Earth's mantle is a few hundred to over 1000 degrees cooler than its melting temperature in most places, and to be definite, I'll use 1000d. For its heat capacity, I'll use 0.8 J/g/K, which seems like a reasonable typical value. That yields about 5*1030 joules, which is not much better.

If one settles for melting the Earth's crust, one's life becomes easier. The Earth's oceanic crust is about 5 - 10 km thick, while its continental crust is about 30 - 50 km thick. So melting down to 50 km should obliterate all details of the Earth's crust. Checking on Melting Points of Rocks and Minerals (http://hyperphysics.phy-astr.gsu.edu/hbase/geophys/meltrock.html), it should take only 1000 C temperature rise to do it. I estimate about 6*1028 joules, which is only a few minutes of the Sun's output.

Making its Atmosphere Dissipate Into Outer Space

That can be done by heating it enough so that some non-negligible fraction of air molecules have more than the Earth's escape velocity. The ones at the top will escape, and will be quickly replenished by collisions redistributing the energy of the remaining ones. The velocities have a 3D Gaussian distribution, meaning that one will need an average velocity only 1/5 - 1/3 the Earth's escape velocity. That's about 2 to 3 km/s, and it requires a temperature around 30,000 K. That requires about 1.5*1026 joules.

Boiling its Oceans

That would make the Earth's atmosphere mostly water vapor for a while, though it would likely cool enough to rain back down. I find about 3*1027 joules.

The Earth's surface would get a pressure around that of its ocean floors, nearly 400 atmospheres, and a side effect would likely be heating it to several hundred degrees C.

Heating its Atmosphere by 100 C

Much easier, about 5*1023 joules, which is about a millisecond of total sunlight, or nearly 6000 tons of energy. However, the Earth receives sunlight at a rate of 1.74*1017 watts, thus requiring a month of the Earth's total sunlight.

Camilla Delvalle
02-13-2011, 02:17 AM
Hit the Earth with an asteroid, a moon or a planet the right way so that the Earth's orbital speed around the Sun is reduced. The Earth will be pulled in by the Sun, fall down on the Sun and be destroyed.

Alexandermerow
04-08-2011, 03:41 AM
With a very big rocket. How else? ;)

Smileycat
04-19-2011, 02:44 PM
You could use a super powerful laser-like weapon, designed for splitting earth into tectonic plates. Doing this would cause horrible tsunamis if it was a waterfilled world. The tsumanis would, of course destroy buildings and everything with 500 miles of said water. Therefore, multiple strikes would be necessary.

Another way would be to hurl a very large object, like a hydocarbon planetoid at the world. This would convey its oceans of oil onto the world, rendering their drinking water bitter (think Wormwood).

glutton
04-19-2011, 04:29 PM
Hit somebody through it with a hammer? At least, it worked in a Marvel comic...

JimmyB27
04-19-2011, 04:50 PM
I have no input on the OP, but:

Advanced science always appears as magic.


No it doesn't. Clarke's third law is bullshit, just because a well-known SF writer said something doesn't make it correct.
I think if you get the wording correct, it does make more sense.

Any sufficiently advanced technology is indistinguishable from magic.
The 'sufficiently advanced' part is important, and it is variable, based on the scientific understanding of the beholder. For example, a TV would appear magical to someone from just a few hundred years ago. To you and me, not so much.

Sarpedon
04-19-2011, 05:08 PM
Aside from the amusing image of a black hole choking on a proton... does it have the strength to rip the proton apart and then eat it?

No. gravity<strong nuclear force.

much <.

Amadan
04-19-2011, 06:54 PM
The 'sufficiently advanced' part is important, and it is variable, based on the scientific understanding of the beholder. For example, a TV would appear magical to someone from just a few hundred years ago. To you and me, not so much.

But a well-educated person from a few hundred years ago who encountered a TV would be amazed, but would probably correctly conclude that it was a product of advanced science, and not magic.

/derail

Skyler
04-20-2011, 02:00 AM
But a well-educated person from a few hundred years ago who encountered a TV would be amazed, but would probably correctly conclude that it was a product of advanced science, and not magic.

/derail

Albeit only because they reject the possibility of magic out of hand.

Astronomer
04-20-2011, 03:51 AM
I think the notion that such things scale indefinitely is too easily accepted as fact. I don't buy it, and I've never thought Clarke's quote to be too insightful, except to the extent that it lends itself to the creation of remarkable SF stories.

I don't believe it is infinitely scalable. I believe that, when it comes to understanding of nature (and, thus, technology), there are plateaus that can be reached -- one of them being the automatic rejection of magic out of hand. I believe that to a sufficiently advanced civilization, no amount of advanced technology would be perceived as magic, simply because they've reached the point at which new phenomena are seen as just that: perfectly natural phenomena -- however unexplained -- and not something that must be explained by thundering gods or supernatural powers.

Aside: I hope the OP doesn't mind our derailing the topic and discussing this. Think he'd be mad if we continued down this path?

KellyAssauer
04-20-2011, 03:58 AM
So how would you destroy a planet? And you must use scientifically plausible means.

So let's have it. What's your plan?

Vote Republican?

:D

*ducks*

glutton
04-20-2011, 04:16 PM
I don't believe it is infinitely scalable. I believe that, when it comes to understanding of nature (and, thus, technology), there are plateaus that can be reached -- one of them being the automatic rejection of magic out of hand. I believe that to a sufficiently advanced civilization, no amount of advanced technology would be perceived as magic, simply because they've reached the point at which new phenomena are seen as just that: perfectly natural phenomena -- however unexplained -- and not something that must be explained by thundering gods or supernatural powers.

But what if the tech they encounter works on a level completely beyond their understanding of their universe... ie. if it can outright ignore and even rewrite what they perceive to be the laws of physics?

Astronomer
04-20-2011, 05:34 PM
But what if the tech they encounter works on a level completely beyond their understanding of their universe... ie. if it can outright ignore and even rewrite what they perceive to be the laws of physics?
As astounding as that would be, a sufficiently advanced civilization would not jump to the conclusion that, since something completely defies currently understood laws of physics, it must be supernatural.

All science is tentative and subject to revision as new phenomena are observed. That's just the way the Scientific Method works. So seeing something that completely contradicts what we think we know doesn't throw scientists for a loop. On the contrary, it thrills them to no end because it gives them something new to explore. We observe new phenomena every day and constantly add to our body of scientific knowledge as we come to terms with it -- or we take away from our body of knowledge (which is really adding to it, since it's based on something we learned) if something we thought we knew is confirmed to be false.

If god-like aliens were to arrive and wield powers beyond our comprehension, it would be the same thing we do in science every day, only in far more concentrated form.

Of course, if they're shooting at us, applying the Scientific Method to the phenomena they display would be difficult. But who ever said science is easy?

Obiwanbeeohbee
04-29-2011, 05:11 AM
How would I destroy the Earth?

If you need a technological means that is based on science that we can demonstrate now and possibly only needs to be scaled up, I would think the most believable method would be to use sympathetic vibration (some folks would want insert the words 'scalar weaponry' here) to shake it apart. The molten core is much warmer than the solid surface, so it is under a great amount of pressure. If you need an explosion that will scatter the pieces, rapid expansion of the core once the crust and mantle have been shaken apart should provide a believable one.

If I only needed to decimate the surface by technological means, I'd figure out a way to detonate all of the nuclear weapons that we have stockpiled at once.

If you are looking for an act of God, there are always asteroid/comet impacts, solar events (coronal mass ejections) and stray planetary-sized objects from outside the solar system. Of course, those have been covered here, already.

readlorey
04-29-2011, 07:52 PM
I would use my space ship, go to the Empire, and borrow the Death Star, leaving my space ship parked in the rental space ship lot. Using its formidable formidable array of turbolasers and tractor beam projectors I would then destroy the planet.

When I was finished I would the fill up the fuel tanks and return the Death Star to the Empire and then go home via my space ship.

Easy, smeasy. Of course the fees are outlandish, but you gotta do what you gotta do.

Pthom
04-29-2011, 08:02 PM
Space ships, Death Stars, turbolasers and tractor beam projectors are fun, but far from factual. Please don't forget this particular sub-forum is for discussions of science facts, not speculations.

Thanks. :)

Soccer Mom
04-29-2011, 08:04 PM
.

agent.grey
04-29-2011, 11:41 PM
How would I destroy the Earth?

If you need a technological means that is based on science that we can demonstrate now and possibly only needs to be scaled up, I would think the most believable method would be to use sympathetic vibration (some folks would want insert the words 'scalar weaponry' here) to shake it apart. The molten core is much warmer than the solid surface, so it is under a great amount of pressure. If you need an explosion that will scatter the pieces, rapid expansion of the core once the crust and mantle have been shaken apart should provide a believable one.

Do you mean sympathetic resonance? That comes with two problems. The energy input will need to be enormous, much greater than exploding all nuclear weapons on earth. It is also much more likely to work in a solid, not a fluid/semi-solid with large variations in temperature, viscosity etc. between regions.

Even if you do 'shake apart' the crust it is already cracked into tectonic plates) there is no reason to think that the mantle and/or core will expand/explode. During the formation of the Earth there was no solid outer layer.

readlorey
04-29-2011, 11:44 PM
Okay then a cut holes with drills such as they use in oil rigs in strategic positions around the planet, such as fault lines, to the core as close as you can get, and place bombs that are 10 times stronger than Little Boy in them. Explode the bombs at the same time and that should cause a tectonic plate reaction that would possibly destroy the planet.

Obiwanbeeohbee
04-30-2011, 12:43 AM
Do you mean sympathetic resonance? That comes with two problems. The energy input will need to be enormous, much greater than exploding all nuclear weapons on earth. It is also much more likely to work in a solid, not a fluid/semi-solid with large variations in temperature, viscosity etc. between regions.

Even if you do 'shake apart' the crust it is already cracked into tectonic plates) there is no reason to think that the mantle and/or core will expand/explode. During the formation of the Earth there was no solid outer layer.

Like I said, you would have to scale this up a bit, but the science is basically sound. All solids (I believe for our purposes, you can consider the crust to be solid) have a natural structural resonance frequency. If you find out what the Earth's NSRF is, you could theoretically build a device that causes a sympathetic vibration.

As for the explosion, the early Earth condensed out of a much larger and less dense cloud of dust and debris. The crust and mantle are fragmented and cracked in many places. That is why we have volcanism. But, the solid crust and semi-solid mantle are much more dense now than the pre-solidification dust cloud and I would guess that they are compressing the molten core at many thousands of atmospheres. One of the dangers of being in a submarine is the possibility of implosion due to the weight of the water above you, and you would only be a small fraction of the depth needed to reach the Earth's core.

I would assume that the molten core is under enough pressure that if the crust and mantle were somehow partially liquefied, by sympathetic vibration or other means, there would be quite an energetic expansion. Granted, gravity would dampen it some, and might possibly cause things to re-condense after a short time, astronomically speaking, but you still wouldn't want to be here when it happened.

I will also admit this isn't the most exciting way to do it...:)

agent.grey
04-30-2011, 03:23 AM
I would assume that the molten core is under enough pressure that if the crust and mantle were somehow partially liquefied, by sympathetic vibration or other means, there would be quite an energetic expansion. Granted, gravity would dampen it some, and might possibly cause things to re-condense after a short time, astronomically speaking, but you still wouldn't want to be here when it happened.

I will also admit this isn't the most exciting way to do it...:)

The 'pressure' is not being held back by a solid or semi-solid layer. Gas giants like Jupiter have no such layer and do not explode in the way suggested. Gravity is supplying the force that creates the pressure, so except in a very localised way it cannot overcome itself.

The explosive (rather than extrusive) volcanic events are almost always due to dissolved gas in the magma/lava escaping at or near the surface, particularly in Rhyolitic magmas.

benbradley
04-30-2011, 04:21 AM
Space ships, Death Stars, turbolasers and tractor beam projectors are fun, but far from factual. Please don't forget this particular sub-forum is for discussions of science facts, not speculations.

Thanks. :)
That's JUST what I was thinking of, and this only uses fifty year old (gasp!) technology.

Thinking of "natural amplification" of current technologies, blowing a nuclear bomb at the Yellowstone supervolcano should be enough to "get it started."

If you don't have access to nuclear bombs, perhaps a large enough mass moving fast enough hitting the right place on Yellowstone might do it. A Saturn 5 Moonshot would do it, just replace the Command and Lunar Module areas with as much mass as you can boost up there. Not sure if it really needs to to a Moon shot turnaround, but that might make it easier to aim it with midcourse corrections and have it coming straight down through the atmosphere at 25,000+ mph. It would be an interesting heat shield design to keep it from burning up on the way down.

Getting back to the original question, this could be done on the Moon with a mass driver, enough payloads (one payliad hitting may not be enough, but MANY payloads sent one after another at slightly different speeds and precise midcourse corrections could add up to a substantial mass hitting all at once) and appropriate steering technology, which a long-term Lunar installation would surely already have to be able to ship things back to Earth. The payload control devices may need modifying so they can't be controlled from Earth on the way down, as that would surely be a safety feature if the Lunar launcher "accidentally" lost control and they were going to hit in the wrong place

Maybe an oil drilling rig going deep enough might start it off, but I imagine you'd get the attention of Mr. "Ranger" before you can drill too far.

Oh, wait, he's from Jellystone.

But if you're on the Moon and have the money and connections (and secure communications to reduce the chance of others finding out what you're doing), you could pay to have a drilling company somehow sneak in and start drilling at a remote location within Yellowstone.

Have the sun die and let nature take its course.

It takes a while, but the planet will eventually be destroyed. Right along with the rest of the solar system.

Misa, who thinks big.
The sun can shine on, but with space technology, it would only take a 1-mil or less reflective or absorptive film to stop all sunlight shining on the Earth, out at the L1 orbit between the Earth and Sun. This would be at least 8,000 (or larger due to paralax and the sizes of the Earth and Sun) miles in diameter, which could add up in mass, but this is just a little technology, not any new science. We've already got the James Webb Telescope being developed to capture a large amount of (very low-level) radiation in a precision way. All we want to do is block more of it.

There's also some visceral fear about a solar eclipse, especially when it doesn't stop and the Moon is nowhere near the Sun in the sky...

I'd keep an eye on the news from CERN and see if they manage to make any baby black holes... if that becomes plausible, then I'd go with creating a temporary black hole in the center of the Earth.

I'd construct a black hole. Isn't the earth covered in teeny tiny ones already?


I'll go even farther and say that a tiny black hole (assumed to be created by smashing two atomic nuclei together at mind-blowing energy levels) is even too tiny to absorb a single proton.
...
So black holes -- at least subatomic ones -- are definitely out.
Also, those generated in accelerators have such low mass that they don't last long enough to absorb any other particles. They radiate away virtually instantly from Hawking radiation (as I understand, that radiation and its timing after the initial events is actually how they claim to have made a black hole). It's just not big enough to stick around, and particle accelerators don't have enough power to make them much bigger.



Hmm... crash the moon into the Earth? Even if it doesn't completely destroy the Earth, if you do it right you could probably destabilize its orbit and send it spiraling towards the Sun. In which case, it would probably explode into tiny fragments. Just like the movies.

The time scale you'd be looking at may not fit your bill. But then again, steering the moon into the Earth would probably kill just about anything alive in the first few hours. The remaining bacteria/cockroaches probably wouldn't have time to develop the technology needed to reverse the planet's doomed trajectory before being vaporized in a giant molten nuclear furnace that practically defines "overkill".
Depending on the energy you have to do it, driving the Moon into the Earth would take years, decades, or centuries or longer. Perhaps long enough for lots of people on Earth to escape, even with a few "Noah's Arks" of other life on Earth.

The Moon wouldn't even have to hit, just get the orbit below the Roche Limit of either body. Either one breaking up would cause the destruction of at least the surface of the other.

Okay then a cut holes with drills such as they use in oil rigs in strategic positions around the planet, such as fault lines, to the core as close as you can get, and place bombs that are 10 times stronger than Little Boy in them. Explode the bombs at the same time and that should cause a tectonic plate reaction that would possibly destroy the planet.
They probably got 'em 100 to 1,000 times Little Boy, but getting them into a borehole might be a problem, though that's an interesting possibility.

Like I said, you would have to scale this up a bit, but the science is basically sound. All solids (I believe for our purposes, you can consider the crust to be solid) have a natural structural resonance frequency. If you find out what the Earth's NSRF is, you could theoretically build a device that causes a sympathetic vibration.
At first thought that sounds interesting and almost plausible Resonant frequencies of the Earth are already well known due to thousands of seismometers around the Earth, measuring every earthquake large enough to be detected. Here's a graph of the big earthquake in Japan A February 2010 Earthquake in Chile. The vertical scale is degrees from the earthquake (180 degrees is the opposite site of the Earth), and the horizontal is time in minutes. There's a minor echo at 90 minutes, and larger one at 180 minutes (this is a large file and takes a while to load):
http://www.unavco.org/community_science/science_highlights/2010/M8.8-Chile_RC_2010_8.8.pdf

The big earthquakes like the recent in Japan are already in the power range of the largest nuclear weapons, if not moreso. You should certainly be able to trigger some faults and/or supervolcanos with nuclear weapons causing great havoc on the surface virtually worldwide, but as far as making the whole Earth come apart, I don't believe it.

Astronomer
04-30-2011, 05:19 AM
My understanding is that an eruption at Yellowstone would destroy at most just the civilized world on the North American continent. The lingering ash cloud, however, would certainly make life tough worldwide, but probably not unrecoverably so.

On the scale we're talking about, I think Earth's crust may as well be a liquid. Maybe more like a thin slice of processed cheese, but not really a solid. In fact, if you were to shrink Earth down to the size of an apple, Earth's crust would be thinner than the apple's skin. I'm afraid I must side with Ben in that targeting the crust with pinprick nuclear explosions in order to let Earth's raging interior do its dirty work is probably not an effective use of resources. Poke a hole in the crust, and it'll be a bit runny for a while. But it will crust over again soon enough.

What if I were to launch enough pure sodium toward Earth (from the moon) to eliminate its oceans? I'd have to use a rail gun and do it a little at a time. But using Ben's time-on-target approach (nice idea!) at multiple targets, I bet I could have a pretty serious impact on humanity.

Layla Nahar
04-30-2011, 06:24 AM
How about using anti-matter? I guess that is in the same realm as the black hole solution, right?

Pthom
04-30-2011, 09:26 AM
My gut reaction is that it would be much easier to destroy the ability of life to survive on a planet, than to destroy the planet itself.

The gravitational forces involved in holding such a thing as a planet together are incredibly immense. Could we break the Earth? Possibly. Could we make it disappear (without magic)? Probably not.

Obiwanbeeohbee
04-30-2011, 08:33 PM
This is how Michio Kaku would do it:

http://science.discovery.com/videos/sci-fi-science-designing-a-planet-buster.html

Seems a bit futuristic for our purposes, but the last 20 seconds or so are interesting.

Wayne K
04-30-2011, 08:40 PM
Deregulation

Bartholomew
05-02-2011, 01:19 PM
So how would you destroy a planet? And you must use scientifically plausible means.

If you were stationed on the moon, and you were tasked with destroying Earth, how would you do it? You can have as many chemical elements as you want in any quantity. What would you construct, launch, or ignite to destroy Earth from the moon?

If you destroy just the biosphere (every living thing), you get only partial credit.

Since you're stationed on the moon, you would ideally like to remain standing after you've accomplished your planetary destruction, so keeping the moon intact is desired. But, megalomania being what it is, you won't be penalized if you sacrifice the moon (and yourself) in your bid for global destruction.

So let's have it. What's your plan?

I would construct massive thrusters on the backside of the moon, pointed in such a direction as to force Luna to collide with Earth.

Earth pinwheels off course and sails into the sun. The remains of Luna resume orbit.

Because if the cueball goes into the hole, I lose my turn.

Astronomer
05-02-2011, 08:18 PM
I would construct massive thrusters on the backside of the moon, pointed in such a direction as to force Luna to collide with Earth.Actually, if you want to push the moon into the sun, you need to mount your mass driver so that it shoots in the direction of the moon's orbit so that the moon's angular momentum is reduced. Mounting the mass drivers on the backside would just cause the moon to oscillate around the point where its center of gravity now orbits Earth, without reducing its overall angular momentum.

Orbits are peculiar things. A planet in orbit around a star (or moon around a sufficiently large planet) is as stable as a marble in a round-bottomed bowl. Push it in any direction, and it will tend to return to its center. You can even make it "orbit" around its point of stability, which is what putting the mass driver on the backside of the moon would accomplish.

A solid ring in orbit around a star (sound familiar?) is like a marble on top of a hill, stability-wise. Give it a slight push in any direction, and it will roll down, never to have the energy required to put it back in orbit (on top of the hill). Sorry, but Ringworlds are too unstable to work. Without constant and very energy-intensive adjustments to their orbits, they will always end up crashing into their suns.

And what about a Dyson Sphere? That's like a marble on a flat surface. It's not inherently stable, but it's not inherently unstable, either. The sphere isn't gravitationally pulled in any particular direction by the star within, regardless of where inside the sphere the star is. (This is assuming, of course, that the sphere is impossibly rigid.) Orbital (if you can call it that) adjustments would still need to be made, but there isn't a gravitational/centripital slope that's either hindering or helping you, so a sphere can be maintained a safe distance from its star far more easily than a ring.


Sorry, it's been a slow day. :)

Wojciehowicz
05-14-2011, 06:46 AM
If time and space were not an issue, nor were supply and energy, relativistic motion should suffice. E=mc^2. Use some other star system's moon or moon-sized asteroid. Use fusion to kick it in the pants, then move to a plasma accelerator, and finally an ion accelerator. When something of a considerable size strikes at .95c, BANG. If the moon were more of a cometary body with significant hydrogen available and you could do efficient fusion, with a body that size you could have immense power plants that would be part of the kinetic kill body itself.

It would take a lot of time, an a lot of accuracy. A little bit off at those speeds, and you miss entirely. But if you do it right, your impactor and whatever it hits are completely destroyed. The force of the event should scatter dust and gas all over the target solar system.

agent.grey
05-14-2011, 11:56 PM
Even allowing for the accuracy problem, where will the energy for the ion accelerator (or any other propulsion method) come from?

A moon-equivalent body at 0.95c has approx 6e42 joules of kinetic energy.

To get that much energy you need to annihilate approx 6.5e22kg of matter.

If you are fusing hydrogen for power you achieve annihilation of 0.7% of the hydrogen's mass. You therefore need to start with more than a hundred times more hydrogen than the body itself weighs.

Or have I made a miscalculation somewhere here? Haven't studiedphysics for quite a few years. :)

benbradley
05-15-2011, 01:13 AM
Sounds about right. I think such a moon hitting the Earth at a relative speed of 0.0005c would have plenty enough energy to destroy everything on the Earth's surface as we know it.

But that would be too fast. I like the idea of moving the Moon into a closer and closer orbit around the Earth, until the Roche limit (http://en.wikipedia.org/wiki/Roche_limit) of one or both is reached. That should be plenty enough to plow under everything on the Earth's surface. It would be so kewl, and there'd be some awfully big earthquakes well before the Roche limit is reached.

Wojciehowicz
05-15-2011, 01:39 AM
Sounds about right. I think such a moon hitting the Earth at a relative speed of 0.0005c would have plenty enough energy to destroy everything on the Earth's surface as we know it.

But that would be too fast. I like the idea of moving the Moon into a closer and closer orbit around the Earth, until the Roche limit (http://en.wikipedia.org/wiki/Roche_limit) of one or both is reached. That should be plenty enough to plow under everything on the Earth's surface. It would be so kewl, and there'd be some awfully big earthquakes well before the Roche limit is reached.

I considered that, but I wanted to go for bang, splat, kapow sort of destruction. Absolutely, your scenario would totally waste the surface. Tidal waves sweeping across entire continents would result long before the Roche limit was reached. Volcanic activity would be insane and the atmospheric damage would wipe out most life we know or care about (as in, everything above microbes). The weather would go crazy and there would be winds sufficient to scour whole cities off the map. When the end came, the rain of debris would be spectacular, if you were watching it from space.

Still, we might want to slow the Moon a little bit someday, to keep it where it is before it recedes to much more. Where it is right now works just perfectly for life as we are and are used to.

Wojciehowicz
05-15-2011, 01:51 AM
Even allowing for the accuracy problem, where will the energy for the ion accelerator (or any other propulsion method) come from?

A moon-equivalent body at 0.95c has approx 6e42 joules of kinetic energy.

To get that much energy you need to annihilate approx 6.5e22kg of matter.

If you are fusing hydrogen for power you achieve annihilation of 0.7% of the hydrogen's mass. You therefore need to start with more than a hundred times more hydrogen than the body itself weighs.

Or have I made a miscalculation somewhere here? Haven't studiedphysics for quite a few years. :)

It doesn't have to be the size of the moon. A moon, which means smaller or larger. At relativistic speeds, even a small body will cause a gigantic kinetic energy release that will disrupt the planet enough for mass to be scattered beyond gravitational recollection. A body the size of our Moon would not need to be going anywhere near that to do it, but would need to be moving way faster than the original impact between Proto Earth and whatever hit it, that gave us Current Earth and the Moon. The goal is to scatter the remaining mass too far for it to clump back together.

agent.grey
05-15-2011, 11:20 PM
It doesn't have to be the size of the moon. A moon, which means smaller or larger. At relativistic speeds, even a small body will cause a gigantic kinetic energy release that will disrupt the planet enough for mass to be scattered beyond gravitational recollection.

Apologies on misreading that, but the basic point about using a fusion power source remains - you still need a hundred times the mass of your chosen moon, and that just covers the hydrogen requirement and assumes total efficiency.

I certainly don't dispute that a massive relativistic mass is a good planet killer, I just don't see any means of propulsion suggested for accelerating such a projectile.

Nivarion
06-09-2011, 09:13 PM
Why would I destory the earth when I've got limitless supplies on the moon? I would rule over the earth from my space throne of evuls, safe in the knowledge that it is incredibly hard for farmboys got get to the moon.

Meanwhile, it would be relatively simple for me to hit their population centers with a massive rock whenever they refuse to show me the respect I deserve. Especially since it would be difficult for them to return fire.

Bwhahahahaha.


I think the notion that such things scale indefinitely is too easily accepted as fact. I don't buy it, and I've never thought Clarke's quote to be too insightful, except to the extent that it lends itself to the creation of remarkable SF stories.

I don't believe it is infinitely scalable. I believe that, when it comes to understanding of nature (and, thus, technology), there are plateaus that can be reached -- one of them being the automatic rejection of magic out of hand. I believe that to a sufficiently advanced civilization, no amount of advanced technology would be perceived as magic, simply because they've reached the point at which new phenomena are seen as just that: perfectly natural phenomena -- however unexplained -- and not something that must be explained by thundering gods or supernatural powers.

Aside: I hope the OP doesn't mind our derailing the topic and discussing this. Think he'd be mad if we continued down this path?

One of the stories in the que (I'm getting better, might start pitching a few soon) involves the captain of a war cruiser meeting up with an alien race who can use magic.

He pitches off clarkes law at one of their gods, who creates a new planet from nothing just to show him up. Full of primal life and everything.

Sufficiently powerful magic will be known as such.

Pthom
06-10-2011, 04:13 AM
Again, folks, this particular sub forum is NOT for discussing works of fiction, but for facts of science. This thread, as a whole, is very close to crossing that line. Certain posts in this thread have already done it. Please follow the rules of this forum and reserve speculative discussions for the main SF/F forum. Because of that, I am very close to moving this thread.

However, a point brought up by benbradley interests me, and that is the Roche Limit. I am curious: with a satellite such as our Moon, which is a little over half as dense as its primary, wouldn't there be significant damage to either body due to tidal stress long before the satellite reaches the Roche limit?

Especially with the Earth/Moon system, where there is tectonic activity and lots of water to factor in. The Roche limit for fluid bodies is not about half as great as for solid ones--I think the earthquakes and tsunamis we've witnessed during this decade would be minor comparatively.

Saturn
07-21-2011, 07:11 AM
Well if we are assuming the hypothetical person on the moon is not an Earthling then he, or she of course, may use a much larger scale version of the propulsion used to get there and turn the moon into a large kamikaze craft and drive the Moon into Earth too fast for Roche's Law to turn it into a ring.

If the person on the moon is from Earth they will have a harder job of it. They probably do not have the resources to capture enough of the sun's energy to melt a planet and may not have available transport to the Asteroid belt. With such transport and sufficient resources and manpower they could rig engines on the largest asteroids (for instance those above 10 km in size) and send them all at Earth in a giant conga line of destruction. This would certainly wipe out life and might be enough to rate a B.

benbradley
07-21-2011, 08:11 AM
...
If the person on the moon is from Earth they will have a harder job of it. They probably do not have the resources to capture enough of the sun's energy to melt a planet and may not have available transport to the Asteroid belt.
I am again reminded of creating a very thin reflective foil (in space around the Earth-Moon system, from some small factory designed, assembled on and launched from the Moon), maybe just a few atoms thick, it only needs to be strong enough to hold together when random atoms hit it in space, made of aluminum, or something like mylar with a thin coat of aluminum. Much like what I wrote before:

...
The sun can shine on, but with space technology, it would only take a 1-mil or less reflective or absorptive film to stop all sunlight shining on the Earth, out at the L1 orbit between the Earth and Sun. This would be at least 8,000 (or larger due to paralax and the sizes of the Earth and Sun) miles in diameter, which could add up in mass, but this is just a little technology, not any new science. We've already got the James Webb Telescope being developed to capture a large amount of (very low-level) radiation in a precision way. All we want to do is block more of it.
... but this time to REFLECT extra sunlight onto the Earth. With an 8000 mile diameter mirror you could double the sunlight that hits Earth and we'd all be cookin' in no time at all (astronomically speaking), but even an increase of 20, 10 or 5 percent of sunlight on Earth would cause Global Warming worse than in Al Gore's worst nightmares. I'm thinking this would have the biggest bang for the cost of materials. You could have controllable mirror sections of a square mile each, and have them all reflect the Sun to a single point on Earth, giving a few city blocks the radiation of thousands of midday suns. All life would be gone in minutes. This would also be a really effective way of starting forest fires.

There's a point where extra sunlight (maybe a 50 percent increase?) would cause the Earth to heat up so much it could only support life at the poles, if at all. That's it, have two mirrors that reflect extra sunlight directly onto the poles, and the whole globe will become a supertropical not-paradise. Eat your heart out, Venus!