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.
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 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.
Current Earth-Destruction Status
Methods for destroying the Earth
Other, less scientifically probable ways that Earth could be destroyed
Methods from fiction
Things which will NOT destroy the Earth
General geocide strategy
For the purposes of what I hope to be a technically and scientifically accurate document, I will define our goal thus: by any means necessary, to change the Earth into something other than a planet or a dwarf planet.
The International Astronomical Union defines a planet as:
a celestial body that
is in orbit around the Sun
has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
has cleared the neighbourhood around its orbit
and a dwarf planet as:
a celestial body that
is in orbit around the Sun
has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape,
has not cleared the neighbourhood around its orbit, and
is not a satellite.
Since "celestial body" does not include the Earth, we shall assume for the sake of pedantry that the IAU meant to say "astronomical body".
These definitions instantly suggest some very simple ways of stripping the Earth of its planethood, such as hurling it into interstellar space, moving it into orbit around a gas giant, or moving it into a solar orbit whose neighbourhood is not cleared (the main asteroid belt being the most obvious choice). A slightly less obvious method would be redefining "planet" not to include the Earth. Naturally, these methods (the latter of which is by far the most feasible method listed in this document) will not be considered to count - redefining something doesn't make it go away.
We are left, therefore, with the challenge of significantly altering the Earth's physical structure, or else reducing its mass such that it can maintain a shape which is not round. For example: blowing it up, turning it into a dust cloud, merging it with a larger body, et cetera.
Current Earth-Destruction Status
Number of times the Earth has been destroyed: 1
Information courtesy of the International Earth-Destruction Advisory Board
Methods for destroying the Earth
To be listed here, a method must actually work. That is, according to current scientific understanding, it must be possible for the Earth to actually be destroyed by this method, however improbable or impractical it may be.
Methods are ranked in order of feasibility. Feasibility ratings are given out of ten - these are based primarily on my gut instinct and do not reflect actual mathematical probabilities in any way.
Several methods involve moving the Earth a considerable distance off its usual orbital track. This is an essay in itself, so a separate page has been created for it.
Annihilated by an equivalent quantity of antimatter
You will need: An entire planet Earth made from antimatter
Antimatter - the most explosive substance possible - can be manufactured in small quantities using any large particle accelerator, but this will take preposterous amounts of time to produce the required amounts. If you can create the appropriate machinery, it may be possible to find or scrape together an approximately Earth-sized chunk of rock and simply to "flip" it all through a fourth spacial dimension, turning it all to antimatter at once.
Method: Once you've generated your antimatter, probably in space, just launch it en masse towards Earth. The resulting release of energy (obeying Einstein's famous mass-energy equation, E=mc2) is equivalent to the amount the Sun outputs in some 89 million years. Alternatively, if your matter-flipping machinery is a little more flexible, turn half the Earth into antimatter (say, the Western Hemisphere) and watch the fireworks.
Earth's final resting place: When matter and antimatter collide, they completely annihilate each other, leaving nothing but energy. All that would be left of Earth is a scintillating flash of light expanding across space forever. This method is one of the most permanent and total on this list, as the very matter which makes up the Earth ceases to exist, making it virtually impossible to even reassemble the planet afterwards.
Feasibility rating: 2/10. It IS possible to create antimatter, so, technically, this method IS possible. But since the proposed matter-to-antimatter flipping machine is probably complete science fiction, we're looking at stupid, stupid amounts of time to pull this off.
Comments: With a significantly smaller amount of antimatter, you can simply blow the Earth up - see later.
Source: This method suggested by Thomas Wootten.
You will need: a universal fission machine (e.g. a particle accelerator), an unimaginable amount of energy
Method: Take every single atom on planet Earth and individually split each one down to become hydrogen and helium. Fissioning heavier elements to become hydrogen and helium is the opposite of the self-sustaining reaction that powers the Sun: it requires you to put energy in which is why the energy requirements here are so vast.
Earth's final resting place: While Jupiter, Saturn, Uranus and Neptune are gas giants composed primarily of hydrogen and helium, they are massive enough to actually hold on to their tenuous atmospheres. The Earth is not; the gases would dissipate away. You'd get a wispy mess of gas where there should have been a planet.
Feasibility rating: 2/10. Technically possible, but, again, hopelessly, mind-bogglingly inefficient and time-consuming. You're looking at billions of years minimum, folks.
Source: This method suggested by John Routledge.
Sucked into a microscopic black hole
You will need: a microscopic black hole.
Note that black holes are not eternal, they evaporate due to Hawking radiation. For your average black hole this takes an unimaginable amount of time, but for really small ones it could happen almost instantaneously, as evaporation time is dependent on mass. Therefore your microscopic black hole must have greater than a certain threshold mass, roughly equal to the mass of Mount Everest.
Creating a microscopic black hole is tricky, since one needs a reasonable amount of neutronium, but may possibly be achievable by jamming large numbers of atomic nuclei together until they stick. This is left as an exercise to the reader.
Method: simply place your black hole on the surface of the Earth and wait. Black holes are of such high density that they pass through ordinary matter like a stone through the air. The black hole will plummet through the ground, eating its way to the centre of the Earth and all the way through to the other side: then, it'll oscillate back, over and over like a matter-absorbing pendulum. Eventually it will come to rest at the core, having absorbed enough matter to slow it down. Then you just need to wait, while it sits and consumes matter until the whole Earth is gone.
Earth's final resting place: a singularity with a radius of about nine millimetres, which will then proceed to happily orbit the Sun as normal.
Feasibility rating: 3/10. Highly, highly unlikely. But not impossible.
Comments: Hmm. The problem is, the microscopic black hole would still be in hydrostatic equilibrium, so it would still qualify as a planet according to the IAU!
Source: The Dark Side Of The Sun, by Terry Pratchett. It is true that the microscopic black hole idea is an age-old science fiction mainstay which predates Pratchett by a long time, he was my original source for the idea, so that's what I'm putting.
Cooked in a solar oven
You will need: Means for focusing a good few percent of the Sun's energy output directly on the Earth.
What I'm talking about here is: mirrors, and lots of them. Intercept several decent sized asteroids for raw materials and start cranking out kilometre-square sheets of lightweight reflective material (aluminised mylar, aluminium foil, nickel foil, iron foil or whatever you can scrape together). They need to be capable of changing focus direction at will because, while a few may be placed at the Earth-Sun system's Lagrangian points, the vast majority cannot be stationary in space and the relative positions of the Earth and Sun will be shifting as time passes, so attach a few manoeuvering thrusters and a communications and navigation system to each sheet.
Preliminary calculations suggest you would need roughly two trillion square kilometres of mirror.
Method: Command your focusing array to concentrate as much solar energy as you can directly on the Earth - perhaps on its core, perhaps at a point on its surface. So the theory goes, this will cause the Earth to generally increase in temperature until it completely boils away, becoming a gas cloud.
A variation on this method involves turning the Sun into a gigantic hydrogen gas laser.
Earth's final resting place: A gas cloud.
Feasibility rating: 3/10. The major problem here is: What's to stop the matter cooling and becoming a planet again? In fact, once the top layer of planet becomes gaseous, what would compel it to vent into space rather than remaining on the surface, absorbing more heat and preventing the lower layers from even being heated? Unless the amount of heat put in was really immense, all you'd get is a gas planet at best, and a temporary one at that. Moving the Earth towards the Sun (see later) is likely to be a far more viable method.
Source: This method suggested by Sean Timpa.
You will need: some means of accelerating the Earth's rotation.
Accelerating the Earth's rotation is a rather different matter from moving it. External interactions with asteroids might move the Earth but won't have a significant effect on how fast it spins. And certainly it won't spin the Earth fast enough. You need to build rockets or railguns at the Equator, all facing West. Or perhaps something more exotic...
Method: The theory is, if you spin the Earth fast enough, it'll fly apart as the bits at the Equator start moving fast enough to overcome gravity. In theory, one revolution every 84 minutes should do it - even slower would be fine, in fact, as the Earth would become flatter and thus more prone to breaking apart as you spun it faster.
Feasibility rating: 4/10. This could be done - there is a definite upper limit on how fast something like the Earth can spin before it breaks apart. However, spinning a planet is even more difficult than moving it. It's not as simple as attaching rockets pointing in each direction to each side...
Source: This method suggested by Matthew Wakeling.
You will need: 25,000,000,000,000 tonnes of antimatter.
Method: This method involves detonating a bomb so big that it blasts the Earth to pieces.
This, to say the least, requires a big bomb. All the explosives mankind has ever created, nuclear or non-, gathered together and detonated simultaneously, would make a significant crater and wreck the planet's ecosystem, but barely scratch the surface of the planet. There is evidence that in the past, asteroids have hit the Earth with the explosive yield of five billion Hiroshima bombs - and such evidence is difficult to find. It is, in short, insanely difficult to significantly alter the Earth's structure with explosives. This is not to mention the gravity problem. Just because you blasted the Earth apart doesn't mean you blasted it apart for good. If you don't blast it hard enough, the pieces will fall back together again under mutual gravitational attraction, and Earth, like the liquid metal Terminator, will reform from its shattered shards. You have to blow the Earth up hard enough to overcome that attraction.
How hard is that?
If you do the lengthy calculations you find that to liberate that much energy is equivalent to the complete annihilation of around 1,246,400,000,000 tonnes of antimatter. That's assuming zero energy loss to heat, neutrinos and radiation, which is unlikely to be the case in reality: You'll probably need to up the dose by at least a factor of twenty. Once you've generated your antimatter, probably in space, just launch it en masse towards Earth. The resulting release of energy (obeying Einstein's famous mass-energy equation, E=mc2) should be sufficient to split the Earth into a thousand pieces.
Greg Bear's novel, "The Forge Of God", contains an interesting refinement of this technique. Here, the antagonist instead generates antimatter in the form of a "slug" of anti-neutronium - superdense material massing a billion kilograms per cubic centimetre. This is fired into the Earth's core. Neutronium passes through ordinary matter as easily as a ball flies through the air, so the anti-neutronium slug doesn't annihilate immediately; rather, it builds up a protective sheath of plasma around it as it plunges downwards towards the Earth's core. It's then followed up by a slug of regular neutronium, which also falls into the core, at a time calculated to meet the first slug head-on at the exact centre of the Earth, where they annihilate themselves, and soon afterwards, the Earth itself. Highly space-efficient, and with the added bonus of all the energy being released at the Earth's core, where it can do the most damage. In the book, the antagonists simultaneously detonate nuclear warheads in certain oceanic trenches, to weaken the crust and allow the planet to be blown apart more easily.
Rearranging Earth into two planets - which, provisionally, is sufficient according to my current criteria - would take slightly less energy, but considerably more finesse.
Earth's final resting place: A second asteroid belt around the Sun.
Comments: trembling writes, "I still think that antimatter is crazy s**t, i.e. wouldn't want it on my flapjacks". Charles MacGee presents a very well-realised alternate source of explosives in his blog; this method involves generating the explosive energy by fusing together the lighter elements of Earth's mantle (magnesium and oxygen). Of course, this would involve the invention of an efficient magnesium fusion bomb. And then turning all of the Earth's mantle into bombs. How implausible! Well. Implausibility is a relative thing.
Feasibility rating: 4/10. Just about slightly possible.
Sucked into a giant black hole
You will need: a black hole, extremely powerful rocket engines, and, optionally, a large rocky planetary body. The nearest black hole to our planet is 1600 light years from Earth in the direction of Sagittarius, orbiting V4641.
Method: after locating your black hole, you need get it and the Earth together. This is likely to be the most time-consuming part of this plan. There are two methods, moving Earth or moving the black hole, though for best results you'd most likely move both at once. See the Guide to moving Earth for details on how to move the Earth. Several of the methods listed can be applied to the black hole too, though obviously not all of them, since it is impossible to physically touch the black hole, let alone build rockets on it.
Earth's final resting place: part of the mass of the black hole.
Feasibility rating: 6/10. Very difficult, but definitely possible.
Sources: The Hitch Hiker's Guide To The Galaxy, by Douglas Adams; space.com.
Comments: It's clear that dropping the Earth into a singularity is massive overkill. A reasonably strong gravitational field, such as might be associated with any body between Jupiter and a neutron star, would be sufficient to rip the Earth apart via tidal forces. These possibilities are dealt with further down.
Meticulously and systematically deconstructed
You will need: a mass driver. A mass driver is a sort of oversized electromagnetic railgun, which was once proposed as a way of getting mined materials back from the Moon to Earth - basically, you just load it into the driver and fire it upwards in roughly the right direction. Your design should be powerful enough to hit escape velocity of 11 kilometres per second.
At a million tonnes of mass driven out of the Earth's gravity well per second, this would take 189,000,000 years. One mass driver would suffice, but ideally, lots (i.e. trillions) would be employed simultaneously. Alternatively you could use space elevators or conventional rockets.
Method: Basically, what we're going to do here is dig up the Earth, a big chunk at a time, and boost the whole lot of it into orbit. Yes. All six sextillion tonnes of it.
We will ignore atmospheric considerations. Compared with the extra energy needed to overcome air friction, it would be a relatively trivial step to completely burn away the Earth's atmosphere before beginning the process. Even with this done, however, this method would require a - let me emphasize this - titanic quantity of energy to carry out. Building a Dyson sphere ain't gonna cut it here. (Note: Actually, it would. But if you have the technology to build a Dyson sphere, why are you reading this?)
Earth's final resting place: Many tiny pieces, some dropped into the Sun, the remainder scattered across the rest of the Solar System.
Feasibility rating: 6/10. If we wanted to and were willing to devote resources to it, we could start this process RIGHT NOW. Indeed, what with all the gunk left in orbit, on the Moon and heading out into space, we already have done.
Source: this method arose when Joe Baldwin and I knocked our heads together by accident.
Comment: Could this also be achieved with a titanic, solar-powered electromagnet?
Pulverized by impact with blunt instrument
You will need: a big heavy rock, something with a bit of a swing to it... perhaps Mars.
Method: Essentially, anything can be destroyed if you hit it hard enough. ANYTHING. The concept is simple: find a really, really big asteroid or planet, accelerate it up to some dazzling speed, and smash it into Earth, preferably head-on but whatever you can manage. The result: an absolutely spectacular collision, resulting hopefully in Earth (and, most likely, our "cue ball" too) being pulverized out of existence - smashed into any number of large pieces which if the collision is hard enough should have enough energy to overcome their mutual gravity and drift away forever, never to coagulate back into a planet again.
A brief analysis of the size of the object required can be found here. Falling at the minimal impact velocity of 11 kilometres per second and assuming zero energy loss to heat and other energy forms, the cue ball would have to have roughly 60% of the mass of the Earth. Mars, the next planet out, "weighs" in at about 11% of Earth's mass, while Venus, the next planet in and also the nearest to Earth, has about 81%. Assuming that we would fire our cue ball into Earth at much greater than 11km/s (I'm thinking more like 50km/s), either of these would make great possibilities.
Obviously a smaller rock would do the job, you just need to fire it faster. Taking mass dilation into account, a 5,000,000,000,000-tonne asteroid at 90% of light speed would do just as well. See the Guide to moving Earth for useful information on manoeuvring big hunks of rock across interplanetary distances. For smaller chunks, there are more options - a Bussard Ramjet (scoop up interstellar hydrogen at the front and fire it out the back as propellant) is one of the most technically feasible as of right now. Of course, a run-up would be needed...
Earth's final resting place: a variety of roughly Moon-sized chunks of rock, scattered haphazardly across the greater Solar System.
Feasibility rating: 7/10. Pretty plausible.
Source: This method suggested by Andy Kirkpatrick
Comments: Earth is believed to have been hit by an object the size of Mars at some point in the distant past before its surface cooled. This titanic collision resulted in... the Moon. You can download a simulated video of the impact from this page. While the Mars-sized object in question obviously didn't hit Earth nearly as hard as we're proposing with this method, this does serve as a proof of concept.
Many useful planetary facts can be found here.
Hurled into the Sun
You will need: Earthmoving equipment.
Method: Hurl the Earth into the Sun, where it will be rapidly melted and then vaporized by the Sun's heat.
Sending Earth on a collision course with the Sun is not as easy as one might think. Contrary to popular opinion, Earth's orbit is not "unstable" and Earth will not begin to spiral into the Sun if we give it the slightest of nudges (otherwise, you can bet it would have happened already). It's surprisingly easy to end up with Earth in a loopy elliptical orbit which merely roasts it for four months in every eight. Careful planning will be needed to avoid this.
There is at least one way of moving the Sun itself. Although the Sun is much bigger, and the Earth would be carried along by its gravity, it might be possible accelerate the Sun hard enough that it eventually catches the orbiting Earth, with the same net result.
Earth's final resting place: a small globule of vaporized iron sinking slowly into the heart of the Sun.
Comments: As far as energy changes are concerned, this method is inferior to the next one.
This method is essentially a variation on the Solar Oven method listed above, wherein you bring the Sun to the Earth (in a manner of speaking).
Feasibility rating: 9/10. Impossible at our current technological level, but will be possible one day, I'm certain. In the meantime, may happen by freak accident if something comes out of nowhere and randomly knocks Earth in precisely the right direction.
Source: Infinity Welcomes Careful Drivers, by Grant Naylor
Ripped apart by tidal forces
You will need: Earthmoving equipment.
Method: When something (like a planet) orbits something else (like the Sun), the closer in it is, the faster it orbits. Mercury, the closest planet to the Sun, moves faster along its path than Earth, which in turn moves faster than Neptune, the furthest planet.
Now, if you move Earth close enough to the Sun, you'll find that it's close enough that the side of the Earth facing the Sun wants to orbit the Sun faster than the side pointing away from it. That causes a strain. Move Earth close enough, within an imaginary boundary called the Roche Limit, and the strain will be great enough to literally tear the planet Earth apart. It'll form one or more rings, much like the rings around Saturn (in fact this may be exactly where Saturn's rings came from). So our method? Move the Earth to within the Sun's Roche limit. Or, better, move it out, to Jupiter.
Moving the Earth out to Jupiter is much the same as moving the Earth in towards the Sun, the most obvious difference being your choice of vectors. However, there is another important consideration, and that is energy. It takes energy to raise or lower an object through a gravity field; it would take energy to propel the Earth into the Sun and it would take energy to propel it into Jupiter. When you do the calculations, Jupiter is actually rather preferable; it takes about 38% less energy.
Alternatively, it may be simpler to move Jupiter to Earth. The theory works like this: build a massive free-standing tower or "candle", with its lower end deep inside Jupiter's depths and its upper end pointing into space. Put machinery inside the tower to pull hydrogen and helium gases in as fuel, through ports in the middle section, and vent these elements out through fusion thrusters at the top and bottom. The tower is called a "candle" because it burns at both ends, see? Now: the flame directed downwards into Jupiter serves to keep the tower afloat (although some secondary thrusters would be needed to also keep it stable and upright). But this lower flame has no direct effect on the Jupiter/candle system as a whole, because all the thrust from the flame is absorbed by Jupiter itself. The two objects are locked together, as if the candle is balanced on a spring or something. The top flame, therefore, can be used to push both the candle and Jupiter along. The top flame pushes the candle which pushes the planet. This is a little unorthodox, and it only works on gas giants, but as means for moving planets it's at least as plausible as the mass-driver and gravity-assist methods described on the earthmoving page.
Earth's final resting place: lumps of heavy elements, torn apart, sinking into the massive cloud layers of Jupiter, never to be seen again.
Feasibility rating: 9/10. As before, impossible at our current technological level, but will be possible one day, and in the meantime, may happen by freak accident if something comes out of nowhere and randomly knocks Earth in precisely the right direction.
Source: Mitchell Porter suggested this method. Daniel T. Staal clued me in on the fusion candle technique, which he got from this Shlock Mercenary comic, which in turn was inspired by the novel "A World Out Of Time" by Larry Niven.
If your best efforts fail, you needn't fret. Nothing lasts forever; the Earth is, ultimately, doomed, whatever you do. The following are ways the Earth could naturally come to an end. (They're no longer in feasibility order since it reads better this way.) Bear in mind that none of these will require any activity on your part to be successful.
Total existence failure
You will need: nothing
Method: No method. Simply sit back and twiddle your thumbs as, completely by chance, all two hundred thousand million million million million billion trillion atoms making up the planet Earth suddenly, simultaneously and spontaneously cease to exist. Note: the odds against this actually ever occuring are considerably greater than a googolplex (1010100) to one. Failing this, some kind of arcane (read: scientifically laughable) probability-manipulation device may be employed.
Current feasibility rating: 0/10. Even if you look at the significantly greater probability of the Earth randomly rearranging itself into separate two planets, this is utter, utter rubbish.
Source: Life, The Universe And Everything, by Douglas Adams.
Written off in the backlash from a stellar collision
You will need: another star. White dwarf is good, but we're not fussy.
Method: Crash your star into the Sun.
The interactions between the two stars in this very violent stellar event will cause more fusion to occur inside the Sun than normally does in 100,000,000 years. The result is not unlike a supernova explosion, though slower - a staggering amount of matter and energy is released outwards, burning the Earth to a crisp and firing it into interstellar space at best, completely incinerating it at worst.
Earth's final resting place: burnt pieces.
Feasibility rating: 4/10. This is listed under natural methods because there is absolutely no way you can move a star. Well, there are ways and means, but if you can move a star, why not move the Earth into that star? And the chances of this happening - even considering that in two billion years' time the Milky Way is going to collide with Andromeda - are very, very slim. Calculations suggest that the number of actual stellar collisions that are likely to occur in that exchange will be SIX. Six chances in about a hundred billion.
Hmm. That's actually pretty high for this list. Make it 5/10.
Source: This method suggested by Eric Thompson.
Comments: See the supernova entry below for more about this Andromeda collision.
Swallowed up as the Sun enters red giant stage
You will need: patience
Method: Simply wait for roughly 5,000,000,000 years. During its natural progress along the Main Sequence, the Sun will exhaust its initial reserves of hydrogen fuel and expand into a red giant star - swallowing up Mercury, Venus, Earth and Mars in the process.
Earth's final resting place: Boiling red iron in the heart of the Sun.
Feasibility rating: 8/10. It is possible that the increasing solar wind combined with the Sun's decreasing mass will result in the Earth gradually moving out to a wider, cooler, safe orbit, but most recent work suggests that this method is sound.
You will need: considerably more patience
Method: Our universe is rapidly expanding in all directions. It will likely continue to do so for a very, very long time. After that time, if the density of matter in the universe is greater than a certain critical value, the universe will slow to a stop due to mutual gravitational attraction, and, roughly 42,000,000,000 years from now, collapse back together again, in a reversal of the Big Bang called the Big Crunch. Conditions during the Big Crunch will be similar to those during the Big Bang: mind-boggling heat, matter ripped to subatomic particles, fundamental forces such as gravitation and electromagnetism merging back together, that sort of thing. Yes, Earth would be destroyed. So would the rest of the universe. A tiny sphere of iron stands little chance against conditions like that.
Earth's final resting place: Quark-gluon plasma? Pure energy? Part of the next universe?
Feasibility rating: 8/10. Plausible. Assumes that the Big Crunch will actually occur at all, which is currently in question.
Source: Nick Snell suggested this method.
Torn a new one
You will need: about half as much patience
Method: Recent experimental results seem to show that the expansion of the universe is not slowing as one might imagine it would. In fact, the expansion is accelerating. It's a bit early to say with confidence why this is happening, though phrases like "dark matter" and "phantom energy" pop up pretty frequently, but anyway, it's conjectured that if the ratio w of dark energy pressure to dark energy density in the universe is around -3/2 (buh?), then something of the order of 20,000,000,000 years from now, the universe would expand, accelerating in its expansion until it was ripped apart at the seams. To quote Wikipedia's entry: "First the galaxies would be separated from each other, then gravity would be too weak to hold individual galaxies together. Approximately three months before the end, solar systems will be gravitationally unbound. In the last minutes, stars and planets will come apart, and atoms will be destroyed a fraction of a second before the end of time." Cool, eh?
Earth's final resting place: HAH! If I knew that, I wouldn't need aftershave.
Feasibility rating: 8/10. Likely. Assumes the Big Rip theory is correct, which it probably is, but might not be.
Source: a theory proposed by Robert R. Caldwell, Marc Kamionkowski, and Nevin N. Weinberg in February 2003. Read it here (PDF warning! Also, dense, difficult physics!). Brought to my attention by Jonah Safar and nanite.
You will need: all-surpassing patience
Method: If the Big Crunch doesn't happen, and the Big Rip doesn't happen either, then we come back to the third option: the Big Chill. For this, the universe will just expand, forever. The laws of thermodynamics take over. Every galaxy becomes isolated from its neighbours. All the stars burn out. Everything gets colder until it's all the same temperature. And after that, nothing ever changes in the universe. For eternity.
A lot can happen in an eternity. Protons, for example, while incredibly stable, are believed to eventually decay like any other particle. So simply wait for a period of time of the order of 1,000,000,000,000,000,000,000,000,000,000,000,000 years, and roughly half of the constituent particles of Earth will have decayed into positrons and pions. If that's still too much like a planet for you, you could wait for another 1036 years, leaving only a quarter of the original Earth. Or wait even longer. Eventually there will be as little of Earth left as you wish.
Earth's final resting place: Miscellaneous positrons and gamma radiation (pions decay almost instantly into gamma ray photons) scattered thinly across the entire universe.
Comments: It's interesting to compare this method with the one right at the top (total existence failure). What we are essentially doing here is almost exactly the same thing, only instead of expecting every particle to disappear at once, we are waiting patiently for a significant proportion of them to disappear, one at a time, over the course of an unimaginable period of time. Essentially we've come full circle. The scientific theories involved are the same, it's just the time scale being considered which changes the feasibility rating from "astoundingly improbable" to:
Feasibility rating: 9/10. If all else fails, this one would be essentially unstoppable...
Source: This method suggested by Joseph Verock.
Bobby Florea suggested to me the intriguing idea that "Evolve an Earth-destructive form of life" might count as an additional natural method for destroying the Earth. Given that we are here, and you are reading this article, it seems like this is the plan which is furthest along at the moment. Of course, this could simply be taken to be "step zero" in all the artificial methods listed above, and not an original method at all...
Other, less scientifically probable ways that Earth could be destroyed
Here are kept the methods which sound good on paper, but might not necessarily actually work, because the science they are based on isn't necessarily valid. Read on.
Whipped by a cosmic string
You will need: a cosmic string and a whole lotta luck
Method: Cosmic strings are hypothetical 1-dimensional defects in spacetime, left over from earlier phases of the universe, somewhat like cracks in ice. They are potentially universe-spanning objects, thinner than a proton but with unimaginable density - one Earth mass per 1600m of length! All you need to do is get a cosmic string near Earth, and it'll be torn apart, shredded, and sucked in. Probably the entire rest of the solar system would be too.
Earth's final resting place: String.
Feasibility rating: 1/10. Mind-bogglingly unlikely. Even if cosmic strings do exist, which they may not, there are probably only about ten of them left in the ENTIRE UNIVERSE. And they can't be steered, unless you have godlike powers, in which case you might as well chuck the Earth into the Sun and have done with it, so you're relying entirely on luck. This. Will. Never. Happen.
Source: this method suggested by Dan Winston.
Gobbled up by strangelets
You will need: Some strange matter.
Strange matter is a phase of matter which is even more dense than neutronium. It's theorized to form in particularly massive neutron stars when the pressure inside them becomes just too great for even neutronium to exist: the individual neutrons comprising the neutronium are instead broken down into strange quarks. The neutron star then becomes a "strange star" which is essentially a single gigantic nucleon.
Some theories suggest that a lump of strange matter ("strangelet") could remain stable outside of the intense pressure which created it. This would make it theoretically possible for strangelets of sizes all the way down to the atomic scale to exist. It's further theorized that the gravitational field of a microscopic strangelet would be enough to gobble up anything it comes in contact with, turning it into more strange matter.
Method: Hijack control of a particle accelerator. I suggest the Relativistic Heavy Ion Collider in Brookhaven National Laboratory, Long Island, New York. Use the RHIC to create a strangelet large enough to remain stable. Once created, your job is done: relax and wait as the strangelet plummets through to the Earth's core, where it will eventually swallow up the entire Earth.
Earth's final resting place: a tiny glob of strange matter, perhaps a centimetre across.
Feasibility rating: 3/10. Evidence for the existence of strange matter is sketchy at best; there are a few neutron stars which look too small to be made of neutronium, there are a few earthquakes which might have been caused by a microscopic strangelet passing through the Earth at high speed, but that's about it. And even if it were possible that small stable strangelets could exist and swallow matter up in the manner described, the odds of forming one in a particle accelerator are pretty much zero.
The Supernova Method
See: The Supernova Method
Shaken to pieces
See: Tesla's Earthquake Machine Method
Reduced to true vacuum
You will need: An expanding bubble of true vacuum decay.
Some scientific theories tell us that what we may see as vacuum is only vacuum on average, and actually thriving with vast amounts of particles and antiparticles constantly appearing and then annihilating each other. However, it's postulated that at any time a small bubble of this "false vacuum" could spontaneously decay into genuinely empty "true vacuum". Usually such a bubble would contract to nothingness instantly, but under the right conditions it could expand forever, eventually destroying the entire universe.
Method: There's no method here because such bubbles are quantum effects which can only really come into existence spontaneously, not by human machinations. You just have to wait for it to happen.
Earth's final resting place: Unknown.
Feasibility rating: 1/10. Firstly, this might be total bunk. Secondly, if it isn't total bunk, the odds against this ever happening are clearly astronomical. It's never happened at any time in the last 13.7 billion years; it seems unlikely to happen anytime soon.
Source: This method suggested by Adam Mansbridge.
You will need: A stable Einstein-Podolsky-Rosen bridge, a.k.a. a wormhole.
Method: Depending on how powerful your technology is, there are a variety of possible methods. Bridging the centre of the Earth with the centre of the Sun would do the trick very efficiently, with the Sun's million-degree heat instantly boiling the Earth from the inside.
Alternatively, open a large wormhole at the Sun's core and the other end in deep space, rapidly venting all the Sun's fuel and hastening its transition to the Red Giant stage. Drain all this fuel rapidly enough and you might even be able to cause a supernova.
You could even bridge the Earth's core with deep space, causing it to implode - although the toothpaste-shaped remnant appearing at the other end may well collapse back to form a planet again.
Earth's final resting place: Variable.
Feasibility rating: 2/10. Wormholes probably aren't actually scientifically possible, and even if they are: opening one at the centre of the Sun? Come on.
Source: This method suggested by Daniel Swartzendruber.
Existence negated via time travel
You will need: a time machine, heavy rock-moving equipment/explosives.
Method: Using your time machine, travel back in time just over 4,500,000,000 years to shortly (i.e. a few billenia) before the formation of the Earth. What you should find in its place is a young Sun and an accretion disc formed of the dusty/rocky material that will later become our Solar System. Find the patch of material that is likely to condense into the Earth. Now blow up, split apart and otherwise stir up the material so that it never gets a chance to come together and form the Earth. Return forwards in time in several hundred-million-year jumps, repeating the process each time so that no planet of any kind ever forms at roughly 1 AU from the Sun. If you make an error, simply go back in time and try again.
If your time machine is more resilient, or you don't mind dying, you could consider going further back in time. The further you go, the less you need to change the universe to prevent the Earth ever forming. Go back to a few billionths of a second after the universe began and just by being there you'll completely alter the face of the universe to come... although it was pretty hot back then...
Earth's final resting place: When you finally return to the present day, you will be left with a largish asteroid belt where Earth should be. Alternatively, you may find that the matter has been assimilated into the bodies of other planets or the Sun.
Feasibility rating: 1/10. This method relies on fictional technology and has no basis in real events or scientific theory. Time travel in this way is almost certainly impossible.
Comments: My good friend Rob rightly informs me that this course of action does not strictly speaking "destroy" the Earth - there is no actual destruction event in which the Earth goes from existing to not existing. What one ends up with instead is a universe in which the Earth does not and never did exist.
Destroying Rob proved remarkably easy.
Destroyed by God
You will need: God
Method: Far be it from me to dictate whether God does or does not exist, but if he did, and was omnipotent, then no doubt he could destroy the Earth at a mere thought if he should decide to. Of course, the question arises of how we persuade him to do this.
The first idea which springs to mind is to simply bring about the Apocalypse described in the Christian Bible. Assuming the book of Revelation is an accurate, literal depiction of future events, verse 1 of chapter 21 reads "Then I saw a new heaven and a new earth, for the first heaven and the first earth had passed away, and there was no longer any sea".
It seems astounding that the complete destruction of an entire planet (and heaven too) would only be worth a single sentence in this lengthy account of the End Times. But on the other hand, verse 5 of the 104th Psalm reads "He [God] set the Earth on its foundations; it can never be moved", and there are other verses like this, so maybe:
the New International Version of the Bible has "earth" written with a lower-case "e", which suggests that this verse could merely refer to, you know, the ground
this verse could be merely metaphorical - after all, so is the creation story described in Genesis
it could be that the new Earth is the same as the old Earth, and "new" just means it was "wiped clean" in some sense, like an Etch-A-Sketch
In all three cases, the new Earth would still need destroying for real.
Another suggestion, should Judaic mythology turn out to be correct, is finding and killing one or more of the Lamed Vav Tzadikim, 36 righteous men whose role in life is to justify the purpose of mankind in the eyes of God. If even one of these is missing, it is said the world would come to an end. Practically speaking, it would probably be easier to wipe out humanity than to find one of these individuals, who do not themselves know who they are.
Comments: It is of course entirely possible that the means God would choose to use to destroy the Earth would be a natural, non-miraculous event such as one of those listed above.
Earth's final resting place: potentially any form, anywhere.
Feasibility rating: this, naturally, is entirely subjective.
Mike Trainor writes, "Just because we don't have the technology to destroy the planet doesn't mean no one else in the universe does. What you need to do is to point our most powerful radio-telescope transmitters at likely solar systems and taunt them. 'The girly-beings in your miserable solar system could never destroy a planet as cool as this one...'" Thanks, Mike. We'll get SETI on it.
Methods from fiction
This section got too big for its shell so I moved it to a separate page.
Things which will NOT destroy the Earth
Nanotechnology. Let's be clear here: nanotechnology is nothing more than a means to an end. Programming some sort of self-replicating von Neumann machine to eat the entire Earth up has its own massive problems (like, won't the ones at the bottom be crushed into their constituent atoms?), but even if it worked - you haven't destroyed the Earth. You've just got a planet made of nanobots that still needs destroying somehow. Program them to hurl themselves into space? Well, that's Meticulous Deconstruction, above.
You will need: The capability to reduce the entire planet Earth to the microscopic temperatures necessary to cause it to revert to a Bose-Einstein condensate.
Method: It's well known and reasonably well-understood that substances at extremely low temperatures can get to the point where quantum phenomena start to have macroscopic, i.e. visible, effects. For example, it can just climb right out of a container, defying gravity. As to why, you would need some quantum physics under your belt.
Could the same work for a whole planet? Could a sufficiently cold body (if it were shielded from the heat of the Sun and ambient background microwave radiation) just spontaneously begin to dissipate into space?
Another idea is to use strong magnetic fields on the condensate to cause it to display what is currently referred as an unusual characteristic, undergoing something approximating a stellar supernova on a tiny scale: imploding on itself and then exploding, with a substantial fraction of the atoms involved disappearing entirely!
Feasibility rating: 4/10. The first idea may work, but the second one probably won't. This is because the experiment specifically used rubidium-85 atoms having a "negative atom-atom scattering length". I don't know what that is, but it sounds unusual for an atom, and we know for a fact that most of Earth is not made up of rubidium-85. Plus, the "disappeared" atoms didn't actually vanish, they just escaped the experiment system under high enough energy that they weren't detected escaping. And of course, generalising quantum phenomena to gigantic scales is never a great idea.
Gamma Ray Burst'd
You will need: a star in Earth's stellar neighbourhood with >40 solar masses. Such massive stars are hard to come by; even Betelgeuse has only 20 solar masses. The best candidate I know of is Eta Carinae, which has over 120 solar masses but is ~7500 light years away.
Method: Gamma ray bursts are powerful, short-lived floods of gamma ray photons. GRBs come in two flavours, short (less than 2 seconds) and long (2 seconds to about 3 minutes); the latter are believed to be caused by stellar explosions called hypernovae, hundreds of times more violent than ordinary supernovae. Such stars are usually billions of light years away when they explode - the fact that we can detect them at this range should tell you enough about how powerful a hypernova is. So how about triggering one locally? Any such explosion within about 20 light years would probably be violent enough to destroy the Earth itself.
Feasibility rating: 0/10. This method was originally listed above, but astronomer Stephen Thorsett set me straight. It wouldn't work. Even in the titanic quantities described above, gamma rays wouldn't make a dent in Earth's actual, physical structure.
Sources: Lycurgus suggested this method. Further information from nasa.gov.
Burned away by muon-catalyzed fusion of the oceans
You will need: a supply of muons.
Method: The theory runs like this. A muon is a negatively-charged particle somewha