# Is it possible to kill all life on Earth?

Edit: It has been suggested that my question is a duplicate of What could humans do to render the earth uninhabitable?. That question only asks what would be necessary to make human life impossible. That is much simpler than what I'm asking and every answer is geared only to that limited scope — and are, therefore, unsuitable to answer this question. No amount of time or editing of that other question (unless you change the OP's intent, which is forbidden by SE) will change this state.

I suspect someone read the title to that other question (but not the question itself) and jumped to a conclusion. Nevertheless, vox populii.

The year: 2025

The goal: Kill the Earth

• "Kill the Earth" means the Earth is no longer capable of supporting life of any kind. The only possible way for life to grace the planet again is through the reintroduction of life from an outside source or through the same serendipity that brought it about in the first place (if that's even possible on a planet this old).

• "Kill the Earth" does NOT mean the orb, sphere, lump-of-dirt-and-molten-metal of the planet is destroyed. That would be "overkill the Earth," and that's not what we're talking about.

• Only technology that can be justifiably developed by 2025 may be considered.

• The planet's death must be intentional. Unintentional side effects of living life are not allowed. For example, whether you prefer the phrase "climate change" or the phrase "global warming," neither is acceptable as a method of killing the planet. I believe neither apathy1 nor detachment2 meet the mandate of intention.3

• However, the reason for the death of the planet is NOT being considered here. In other words, I don't care if it's war or some evil genius. I'm hoping to understand if it's possible, given tech available on or before December 31, 2025, to kill the planet. However, if you just can't stand addressing the question without a premise, assume the nations of the Earth failed to pay Ernst Stavro Blofeld his ransom. Whether you think it can be done with enough nuclear weapons or bubble-gum, you need to justify just what it would take.

• The planet must be dead within a month of acting on the intent to destroy the Earth.

• I'm using the tag because I'm not interested in, "well, this might work" answers. Back it up or pack it out.

Question: Is it possible before the end of 2025 to destroy all life on Earth within a 30-day period per the above requirements?

1The tendency to consume resources and pollute in a thoughtless, even oblivious manner. It isn't that the individual wants to kill the Earth, it's that he/she doesn't care that they're part of the problem. Indeed, they don't even care to discover if they are part of the problem. The entire issue rolls off their back like water on a duck.

2On the other hand, this is the kind of person who honestly believes they're not killing the planet and would never in a million years agree that they are killing the planet — but see no reason why they shouldn't be allowed to dump chemical waste into a river. After all, it needs to go somewhere, and it costs too much to recycle it. More jobs are to be had if the cost is avoided! Like the job of scraping the barnacles off my new 60' yacht! So such a person deliberately dumps — but isn't actually trying to kill the Earth.

3The biggest reason for this condition is that almost anything could destroy all life on the planet, like a meteor, but I'm not interested in natural phenomenon, like meteors, or "consequence of living" phenomenon which may or may not kill everything (but likely won't, and hasn't in the last 50 years anyway). I want to know if there's a way to extinguish it. Frankly, I'm not convinced using all the nuclear weapons from the height of the Cold War would do it, which is why I'm asking. Honking cockroaches.

• Comments are not for extended discussion; this conversation has been moved to chat.
– L.Dutch
May 28 '19 at 16:23
• and furthermore, does it have to be 1 event? if so, yes, It's nearly entirely impossible. Jun 7 '19 at 14:04
• @tuskiomi It must be a human interaction from the perspective that it's a human choice to kill the planet. In other words, a meteor impact would only be a valid answer if within 30 days humans could move the meteor. No, it needn't be a single event, but whatever solution you have in mind must be completed within 30 days. Jun 7 '19 at 15:42
• @tuskiomi, You could say that. If you believe that could lead to a nuclear event in 2025 that would satisfy the question, please do! Jun 7 '19 at 18:57
• @DescheleSchilder (*sigh*) No question tagged hard-science can be opinion-based because of the requirement to prove an answer with mathematics, citations, and/or empirical evidence. You'd benefit a lot by reading our help center and the tag wikis. Worse, the condition of the question is that all life must be killed. You might want to redefine the question and then answer the modified question - but that's not your prerogative. Aug 4 at 4:57

# Not with the time constraint given.

Let's start with the most destructive thing we've got: nukes. There are about 15,000 nukes worldwide, of varying yields. Sources:

Assuming an average yield of 200 kilotons, which is what most US nukes have, we could assemble them all up into a framework to allow for a blast of approximately three gigatons.

Source for the average yield of an american bomb:

That is about 15 Krakatoa explosions. Source for the estimated output of the Krakatoa volcano:

If 15 Krakatoas went off at the same time around Earth, we might have more than enough dust in the atmosphere to block sunlight for some time. That would cause a huge and relatively quick extinction event. But lack of light did not end all life 65 million years ago. It would not end all life nowadays either.

# What if we dial it to eleven, then?

The amount of uranium in the Earth's crust that is accessible to mining approximates to 35 million tons. Source:

If we mined it all, and used it all for nukes and nothing else, we could have a set of bombs strong enough to achieve about the same yield as the impact of Chicxulub. Source:

So we got an extinction event on our hands, and on steroids since this one also makes the whole surface of the Earth radioactive. While this is enough to make Imagine Dragon's Radioactive the theme song for the planet, it will fail to wipe out all life on Earth just like Chicxulub did. The impact will be survivable for a lot of creatures, and the radiation will only immediately kill those at the surface of the Earth or closer to it (in the case of marine creatures).

Water is a great radiation shield. You can swim in a pool of spent nuclear fuel with impunity. Source:

The creatures at the depths of the ocean will be mostly unaffected until enough radioactive material actually makes it to them, which may take more than a month.

# Life always finds a way anyway

Last but not least: some lifeforms actually thrive on radiation. Consider the collapsed reactor of the Chernobyl Nuclear Power Plant. The amount of radiation in there is enough to kill most living beings in short time, yet a species of radiotrophic fungus thrives in there. Source:

You might kill a lot of things, but some lifeforms would remain. The goal you wish just cannot be achieved in such short time.

Edit: as Nicolai pointed out in comments, there are bacteria living several kilometers underground - and they use uranium in their metabolism, so even if the radioactivity makes it to the underground, the microbes may actually benefit from it. Source:

Edit: WhatRoughBeast and Denis de Bernardy have also reminded that this beast has been found way deep underground:

This is the Halicephalobus mephisto, a 0.5mm long nematode that has been found living 3.6km below the surface. It too would probably be largely unaffected by whatever disasters that wreck the surface of the planet.

Had we one or two centuries to prepare, maybe we could throw some planetary mass at the Earth. That would melt the crust and make sure nothing survives. Short of something that starts another Hadean phase on Earth, nothing we do will end all life.

• Comments are not for extended discussion; this conversation has been moved to chat.
– L.Dutch
May 31 '19 at 4:52
• It's not just bacteria that were found that deep. There also are multicellular worms. Those nematodes are very tough critters, too. May 31 '19 at 6:08
• @tuskiomi feel free to suggest something that comes closer to the mark ;) Jun 7 '19 at 17:29
• @Renan targeted bio-weapons, atmospheric intervention, and using the sun as your power source to name a few. Jun 7 '19 at 17:59

No.

Most of the preceding responses have overlooked one relatively-recently identified home for life on the planet; within the crust itself. Researchers have found bacteria up to 4 kilometers down in continental crust and 2 km beneath oceanic crust. Recent estimates are that up to 70% of the microbial life on the planet is, in fact, in the deep biosphere.

That being the case, in order to sterilize the planet you'd need to heat the crust so that the heat penetrates down far enough to ensure there was no space between the hot rocks above and the hot rocks below for any life to survive. To do it quickly means dumping so much heat into the crust to allow it to work it's way down that you're almost certainly talking about creating a magma ocean on the surface.

There is no human technology capable of this, and will not be by 2025. While, theoretically, you might be able to slowly shift the orbit of, say, the Moon to do it through impact (and I'm not sure even that will be enough), it's not happening within 6 years.

• Simple and direct. May 29 '19 at 19:53
• There is 1 human technology on the near horizon that could make it possible. Asteroid mining. If you could vaporize ice on an asteroid in a targeted area you can create propulsion like a comet. A sufficiently large one that collided with the earth would be hard to find though since all the planets have long since cleared their orbits. You'd likely need an asteroid the size of the moon to accomplish the task but it would meet these criteria. 2025 is probably too tight and their likely isn't an asteroid of sufficient size in the solar system, but all the technology exists. May 29 '19 at 21:36
• @user2927848 - we do not have the tech to move an asteroid or comet large enough to cause that level of destruction anywhere near enough to hit the Earth.
– TLW
May 30 '19 at 1:30
• Could we take all those aforementioned nukes and pack them on the asteroid, and blow them all at once to get the asteroid moving...? Or... per Neil Stephenson's "Anathem", use the nukes successively as a propulsion system? May 30 '19 at 17:28
• @TLW - I'd disagree if the purpose is story writing. You just have to invent an extra-stellar mass like a larger Omuamua with favorable initial velocites & trajectories. 2025 like I said might be too tight but if you could relax that date to 2030 or so in theory it could be believable at least.There are mirrors like the ones I've mentioned planned for orbital telescopes. It's an engineering feat, but you could easily write that away by appealing to human greed. Then 'oops' something happens when moving it into orbit, kablam .... all life on earth is gone. May 30 '19 at 19:17

Well, the one thing that life needs on Earth (and pretty much anywhere else depending on how extreme your xenobiology is) is water.

Now, we're not trying to boil the ocean here but...

No wait. That's exactly what we need to do.

Let's start with how much water that is to boil. We're talking about 1.26 x 1021 litres of the stuff. That's a lot and is going to need a lot of energy to boil off. Exactly how much? Well, it takes approximately 4200 J to heat a litre of water by 1 °C, so it will take around 420 kJ to heat it by 100 °C.

Now, I know this is a simplification, and you're going to say things like 'Hey, the water on earth is warmer than zero degrees' and 'Hey, that doesn't account for the energy used in state change for ice at the poles' and 'Hey, what about pressure differential at the bottom of the ocean?' etc. and you're right; I'm over simplifying but for the purposes of an answer that doesn't blow the field limit of the answer box, let's just assume that on average we're going to need 420 kJ per litre of water on Earth to boil it off.

In practical terms, that means we're going to need 5.292 × 1026 joules to boil off the ocean. But that's just for starters; what we don't want is that water condensing again, so we want to keep up a supply of joules to basically keep it as steam in the atmosphere. But we'll get to that.

There is no such thing as an average nuclear reactor, but the largest one in the US is capable of generating just under 4 MW. Let's assume that we're building reactors half that size and we have a reactor that can reliably produce 2 MW of power 24/7. That is the equivalent of 48 GWh a day.

Now, 1 MWh = 3.6 × 109 J meaning that our nuclear power plant can generate 1.73 × 1014 J. Extending this further, we need around 3 × 1012 power plants to do this work in a day.

But, we have a month! So, dividing by 30, we now only need 1011 power plants to do it. The good news is that for that month, we're only going to need 4.5 tonnes of nuclear fuel per power plant to do this, although we may need more later to keep the water as steam for an unspecified period of time. But here's the thing; the world becomes unlivable because of the ambient temperatures well within the 30 days, so all 'complex' life is already dead. Most of the simpler life is either struggling or dead as well, so let's assume that we only need fuel for our 30 days.

According to some sources, there is only around 40 trillion tonnes, or 4 × 1010 tonnes on the planet today, which works out a little less than 10% of what we need to do this (1011 reactors times 4.5 tonnes of fuel). But, it's not 2025 yet! And there's another source of heat that we can potentially tap; the earth's mantle.

It is already estimated that the leakage of heat from the mantle is around 47 TW, and we can accelerate that through deep core drilling. Essentially, we want to drill a whole bunch of deep holes around the earth, right down to the mantle and let out the lava. This is already a thing, and geothermal energy producers are already getting output that rivals some nuclear power plants. In practice this means that we can generate 10% of the power through nuclear, and between now and 2025 invest a lot of money into geothermal research and drill deep holes that generate the other 90% of the heat we need through tapping into the earth itself.

This secondary (actually, primary given it needs to comprise 90%) method of heat generation has an added bonus; it's likely going to destabilise the tectonic plates as well given the number of holes we're going to drill.

In any event, the point is that life dies without liquid water. If we want to deliberately destroy life on this planet in 2025, the only thing we need by then in terms of tech is drilling technology; we have everything else we need, and we also get to do the one thing I keep getting told I'm not allowed to do on my regular projects;

Boil the ocean.

• I don't think any human activity will ever put even a dent on the stability of the crust... That said, boiling all water may be the way to go, but still would take more than a month. May 28 '19 at 3:28
• @Renan yes, I agree with that and I have to admit I've treated this as my own personal opportunity to write a 'what-if' style answer like Randall Monroe would. Very little in this answer is realistic except for the math. May 28 '19 at 3:35
• "the one thing that life needs on Earth ... is water." Citation definitely needed. May 28 '19 at 17:50
• Why bother to boil it? Just drill a hole in the bottom of the ocean and let it drain off. what-if.xkcd.com/53 May 28 '19 at 19:08
• wait, what? 420kj won't boil a litre of water, it'll just warm it to 100C - you still have the latent enthalpy of vaporization to invest. Also, typical nuclear reactors range from 400MW to 1.5GW electric, and 3 times that thermal e.g. 4.5GW thermal. May 29 '19 at 1:54

No

Within a month period is impossible. The only event realistically capable of wiping out all life that quickly is a meteor strike and you can't get to any asteroid big enough in that time frame let alone get it moving and back to Earth.

Scientists estimate it requires something of at least 100km diameter for an extinction level event. The Chicxulub impactor was 11 to 81 km and only wiped out the dinosaurs.

In the early history of the Earth (about four billion years ago), bolide impacts were almost certainly common since the Solar System contained far more discrete bodies than at present. Such impacts could have included strikes by asteroids hundreds of kilometers in diameter, with explosions so powerful that they vaporized all the Earth's oceans. It was not until this heavy bombardment slackened that life appears to have begun to evolve on Earth.

Wikipedia

Bacterial life is extremely hard to kill

You need a longer timeframe or perhaps settling for killing higher life forms? (Which in a month would still be virtually impossible)

• This is correct, but could benefit from references. This is a hard-science question. May 28 '19 at 4:56
• the impact that created the moon would do probably do it. Estimates vary, but it's thought a Mars sized body impacted the earth. May 28 '19 at 10:24
• This still wouldn't do it. There are deep microbes - similar to what we keep hoping to find on Mars - and such that this wouldn't even touch. May 28 '19 at 14:37
• You don't need anything like the moon to do it. Note that the Theia impact melted the whole planet, more than what's needed to kill the deepest bugs. May 29 '19 at 0:37
• @William All you need if enough released energy to reliquary the crust, there are no microbes that can survive in molten rock, which does not require anything near as big as the moon.
– John
Aug 4 at 2:51

TL;DR: We are unable to kill all life even in a tiny piece of medical equipment. Don't expect us to perform better at killing all life on the whole Earth.

We are already trying hard to kill all life in limited settings and with all the might of 2019 technology there is always something remaining. For example, in high-risk applications, we we don't try to remove the last millionth of microbes.

Of course, when killing all life on Earth we have the advantage that preserving it is not a requirement and we can go with more destructive methods than for medical equipment. However, even with lots of nukes, the size of the crust and the oceans makes any large scale sterilizing method less powerful than any industrial standard to sterilize smaller objects.

• XKCD. May 28 '19 at 18:19
• Bring down a large enough asteroid (and, yes, we can--Orion has the power) and everything's dead. It couldn't be launched by 2025, though, and it would be more than a year from when the button was pushed until the impactor got here. May 29 '19 at 0:40
• @LorenPechtel - Even if we could bring down a large asteroid, it wouldn't do the job. The one that killed dinosaurs fell very short from killing all life. To destroy the crust and the oceans we would need a Theia sized (e.g. Mars sized) body, and even then we would scatter millions of rocks laden with microbes, some of which would fall back when conditions get cool enough to settle again. And of course, throwing an small planet to sterilize Earth is out of reach for our technology.
– Pere
May 29 '19 at 10:04
• There's some evidence, tentative at the moment, that life predated the Late Heavy Bombardment and obviously survived. Throwing a rock at the planet isn't going to be enough unless you have a planet-sized rock. Jul 16 '19 at 15:58

# Grey Goo

One possible way that life on the planet could be extinguished is a Grey Goo scenario. Some kind of self-replicating nano-machine that indiscriminately consumes bio-matter could in theory wipe out all life on the planet, and assuming it propagates at 8 m/s (assuming I did the math right) it could entirely encompass the earth in a month. This assumes of course there's no built in failsafe, and it has expanded to a large enough area that it can't be stopped with conventional explosives, and or nukes. This also assumes it is only started in a single place. Even with a slower propagation rate, if it was released in multiple places around the globe simultaneously it could still suffice to end everything. It's worth noting that while a Grey Goo scenario could become unstoppable, in all likelihood it would propagate at a much more sedate pace.

# Math section

Circumference of Earth: 40,075,000 meters

Seconds in a month: 2592000

8 * 2592000 = 20736000 (half the circumference, since it would be expanding in all directions).

• This basically appears to be the only scenario that could maybe work? It would also have to eat it's way through the mantle of the earth feeding on all of the bacteria deep (kilometers deep) within the Earth. It does operate on the assumption that somehow we're able to create such a monstrosity, but that's the only practical problem here. May 28 '19 at 19:39
• The problem with "grey goo" is that it's got some pretty stiff competition from the "green goo" that took over the planet about four billion years ago.
– Mark
May 28 '19 at 20:30
• Question: Wouldn't nanites get crushed under there own weight once there depth reaches a maybe a couple hundred feet? Therefore its impossible to reach life at the core of the planet. May 28 '19 at 22:02
• @lvella Thermodynamically speaking, life is actually not particularly efficient. That said, depending on how you define life, a self-replicating machine might fit the definition. I'm not sure how bacteria would have time to evolve to eat the nano-machines, if they're spreading at several m/s ... Evolution is not fast. Also bacteria are generally .2-10 micrometers. One can assume a nano machine would be several orders of magnitude smaller. May 29 '19 at 13:18
• Gray Goo isn't even Hard Science. If a Goo particle is small enough to attack matter at the molecular level, it is small enough to be attacked by chemical effect (and by physical ones via Brownian motion), and will quickly deteriorate first into something that does something different than self-replication, and something inert afterwards. The whole Grey Goo idea is just a variation of Magic and Handwaving. May 30 '19 at 8:03

### < How to kill a Tardigrade >

Life is stronger than many people may have expected. For some, unless you nuke them on the head, they'll survive most world destruction events.

One example is Tardigrade. Known to have cyptobiosis, they can suspend their metabolism. They can survive under extreme environments that would kill almost any other animal.

(mostly from wiki)

• Low temperature: few to days at 73K, few minutes at 1K.
• High temperature: few minutes at 151°C.
• Extreme pressure: vaccum of open space and solar radiation combined for at least 10 days, or more than 1200 Atm.
• Dehydration: survive 10 years of dry state.

While their average life span is only a few month, they can be dehydrated to skip a rather long time period, so they can just chill and wait until the "kill" is over.

And there are bacteria that live undersea (3,650 meters) and withstand extremely high temperature (121 Celsius). I highly doubt if you can damage them effectively, let alone eliminate them.

Given the time restriction you set (year 2025), no I don't think it is possible to kill ALL life on earth.

Supervolcanos

Supervolcanos are bad things. Very bad things. One supervolcano can qualify as a global catastrophic risk, creating a layer of ash in the sky across a continent, and a theory places a global winter 75,000 years ago as a result of one. Now, one supervolcano can't guarantee an extinction level event. Well, that's one.

There's more than one, though. A supervolcano, by definition, is anything that can qualify as a class 8 Volcanic Explosivity Index. And, from a few searches on the subject, there's around a dozen potential candidates scattered around the globe. Plus a few Class 7s, which aren't really extinction level events, but we might as well add them to the fire anyway.

Then we get to the main problem - triggering this event. This one's fun. Now, we've got two ways of doing it. The first is to just nuke it repeatedly until it explodes. (Like, maybe ten nukes to a supervolcano? Followed up by a few hundred round of conventional warheads, like MOABs. That seems like a reasonable number.) Now, I'm not sure if it'll work. In fact, I'm fairly certain that this won't trigger a conventional volcanic eruption. But you'll definitely get all that nice red-hotlava and ash, and hopefully the force of the explosion will scatter in to the winds.

The second way of doing things is hiring a geologist and using seismic charges to manipulate the crust. You'll probably need sizable charges, maybe even a few nukes, but this time strategically to trigger the volcano, rather than brute force. I am not a geologist, so my knowledge ends here, but there should be a way to set something like that up, given a few hundred nukes and five years to dig.

In either event, what you end up with is an ash-shell in the atmosphere, thick enough to block all sunlight and the heat that comes with it, choking life as we know it. Within days, the Earth becomes a horrific hellscape of either frozen barren wastes, or lava-choked scorched Earth. To clarify, there will be a few humans who survive past a month, presumably some important people with bunkers, or something of the like. But the Earth is done for. You'll have to wait for it to reset.

• Deep sea life and bacteria should also die I believe. It shouldn't be just humans. May 28 '19 at 10:05
• This is a hard science question so you need sources that indicate that nuking a super volcano can actually trigger the necessary catastrophic event. May 28 '19 at 13:50
• Agree with @MathijsSegers, blotting out the sun won't have much if any effect on ecosystems that are already isolated from sunlight, like those found in caves or at the bottom of the ocean. May 28 '19 at 15:37
• A super-volcano won't cut it. Even if you manage an ash atmospheric level unprecedented in geologic history, there are chemosynthetic bacteria that won't even notice what you're doing.
– Mark
May 28 '19 at 20:26
• The book "The hammer of Eden" of Ken Follett is based on a similar idea. May 29 '19 at 12:45

Since there are no practical "yes" answers I'll give a partial answer--meets everything but the 2025 requirement.

Send a mission to the asteroid belt, they're carrying a big load of nukes. The objective is to use them as an Orion drive to divert an asteroid towards Earth.

Blofeld does the "burn" while the asteroid is behind the sun so no pesky astronomer could notice what's going on. After the burn is done the asteroid is painted black so it's not going to be noticed as it comes down. It's aimed for a barely grazing trajectory.

As it approaches Blofeld makes his ransom demand--pay up if you want the crew to use the last of their nukes to nudge it into a near miss rather than a grazing hit. Orbital mechanics waits for no man so there can be no delaying tactics with the negotiations. One month from impact is the last point where they can nudge it away without simply shattering it instead.

The science:

Orion is going to take a lot of engineering but all the principles have been proven to work. A chemically powered version has actually flown a short distance and objects have been demonstrated to be able to survive in close proximity to a nuclear detonation.

Blofeld will deliberately choose an asteroid with no structural strength to ensure Earth can't simply use massive numbers of bombs. If you thump a rubble pile it's basically going to come apart. Some bits will be lost but so long as the thump isn't too hard the self gravity of the bits will bring them back together. This is a slow process, though, limiting the rate at which you can thump it. Thump it too hard and fast and it flies apart--now you have a great collection of rubble that you can't hope to divert. It will still deliver just as much energy when it hits, though, and the objective is that energy, not the destruction of the impact.

Note that the engineering is probably going to be done in the not too distant future. Delta-v doesn't care if it's used for good or bad, the exact same technology could be used to divert a rock that threatens Earth and the ability to move asteroids this way vastly exceeds any other proposal out there--when time is short there will be no other option. (Not to mention every other asteroid deflection technique requires rendezvous, Orion doesn't. So long as the guidance unit is good enough you merely need to get the bombs to the desired standoff range, it doesn't matter if they're doing a head-on approach.)

• Actually, it may be a full yes. Nuclear pulse propulsion may have been doable with 50 years old tech, and is almost certainly within the reach of 2025 tech - engineering and political problems would be much, much harder to solve, but the answers talks about tech so we may ignore those. Now, it would take much longer than a month to complete the operation - however if the asteroid is put in a near-Earth orbit and diverted at the last moment, it can be done less than one month before conjunction/impact. The problem is that to kill everything the asteroid will need to be immense...
– Eth
May 29 '19 at 15:58
• It may help if you use a retrograde asteroid and make it impact the Moon, to send bigger, slower debris falling. You may be able to do more damage that way.
– Eth
May 29 '19 at 15:59
• @Eth There's still engineering involved to scale it up to the required size. Your launch date has to be 2023 at the latest--that's only 4 years. That's not going to happen. As for debris, irrelevant. This isn't about smacking the planet, it's about delivering enough energy to bake the bacteria. Nothing else will kill the deep stuff. A retrograde would be good--but I don't think there's anything big enough up there. May 30 '19 at 1:39
• The problem with this is that none of the rocks that Blofeld can throw around is big enough to cause even an extinction-level event, much less wipe out all life on Earth. Even moving something the size of the Chicxulub impactor around, with extremely generous assumptions about the efficiency of an Orion drive, requires around 500 million metric tons of bombs. To wipe out life on Earth, you're looking at hitting it with something like Ceres, which requires a Kardashev Type II civilization for the timescales we're looking at.
– Mark
May 30 '19 at 20:38
• @Mark How are you getting that number for the energy to move it? Note that even a crude drive should give about 10% efficiency. May 30 '19 at 21:19

I don't think it can be done in any way imaginable save for complete physical destruction of the planet. Bacteria are essentially impossible to kill.

So, a possible extinction-level event that would kill anything big and possibly eventually a lot of bacteria too: "Sun shade" around the Earth. Just make eternal eclipse. No sun = no life. Eventually. I believe extinction-level event will happen within a month due to mass die-off of stuff requiring sunlight. Actual complete extinction will not be even close in that time frame and you might not wipe a single species if you turn the shade off after just a month - it will just look like extinction happened in a month due to massive die-off at that time.

(you can achieve sunblocking effect with volcanoes/meteors, possibly nukes to some extent, but this manmade shade looks more in spirit with the question demanding purposeful trigger of the extinction)

Now, what about bacteria? As another somewhat related SE question asked (https://biology.stackexchange.com/questions/23050/organisms-using-thermal-energy-as-their-sole-energy-source), there are bacteria that live ONLY on heat, so even if you turn off the sunlight "forever", these will survive until Earth cools down.

Now, how long will it take before Earth cools down completely because we cut off the sun - well, assuming Earth is rock-ish, we have 1 kJ/kg*K and its size gives about 10^27 J/K. Well, if I didn't screw up several orders of magnitude. We have about 10^17 W incoming from the sun that keeps Earth in heat balance and that is now gone, so we have 10^17 W of cooling. We are looking at 10^10s/K = about 30 years to drop a single degree. Note that the surface will cool much faster than the interior, but at the bottom of an ocean trench it will still take a while before those bacteria die off.

• There are bacteria close enough to the Earth's core that it would take billions of years for there to be sufficient solar-related cooling to matter to them; newscientist.com/article/… May 28 '19 at 11:49
• @Richard Well, we have no idea how close they are. If you merely want to freeze the surface (say top 10 km - the deepest we dug), I think it might be done a month. May 28 '19 at 13:48
• @ZizyArcher, um no. Geothermal gradient. Away from active margins, the temperature of the rock increases at 25-30 degrees centigrade per kilometer, and that's entirely due purely to geothermal heating. One calculation I've seen is that it would take hundreds of thousands of years for the oceans to freeze solid because the ice forming on the surface insulates the water below, dramatically decreasing its heat loss. May 28 '19 at 15:20
• Relevant: popsci.com/node/204957 May 28 '19 at 15:21
• Ironically, your sun shade will actually prolong life on Earth, if it’s stable for hundreds of millions of years, which it won't be. There is prolific life around deep-ocean geothermal vents, which won’t freeze while the Earth remains geologically active (several billion years), and won’t even notice the sun going out. But without a sun shade, the oceans will boil away in a mere one billion years or so. May 31 '19 at 7:04

A strangelet could do the job

Of course it is not hard science, because these things are (still) only theoretical and a doomsday scenario would require that some assumptions are right.

A strangelet is a hypothetical particle consisting of a bound state of roughly equal numbers of up, down, and strange quarks. An equivalent description is that a strangelet is a small fragment of strange matter, small enough to be considered a particle.

and

If the strange matter hypothesis is correct and a stable negatively-charged strangelet with a surface tension larger than the aforementioned critical value exists, then a larger strangelet would be more stable than a smaller one. One speculation that has resulted from the idea is that a strangelet coming into contact with a lump of ordinary matter could convert the ordinary matter to strange matter.[15][16] This "ice-nine"-like disaster scenario is as follows: one strangelet hits a nucleus, catalyzing its immediate conversion to strange matter. This liberates energy, producing a larger, more stable strangelet, which in turn hits another nucleus, catalyzing its conversion to strange matter. In the end, all the nuclei of all the atoms of Earth are converted, and Earth is reduced to a hot, large lump of strange matter, the size of an asteroid.

So, if someone has enough resources to build the most powerful particle accelerator in the world in 6 years (1), and some theories prove to be correct, he could trigger an end-of-the-world scenario with the total destruction of life on Earth.(2)

(1) Note that if the purpose is the destruction of the world, it would be relatively quick to build, since the biggest part of the work in projecting and building an accelerator is to be able to perform experiments, which would be useless in this case
(2) But of course, even given a powerful enough accelerator, the possibility that such thing could happen in real life are in the range of "win the national lottery 100 times in a row"

• Cosmic ray impacts have been observed at 40 million times the energy of the LHC, and they haven't produced destructive strangelets in the last 4 billion years, so you are going to need a collider at least 100 million times as powerful as the LHC. Good luck building one of those any time soon! Dec 12 '19 at 14:38

# ATMOSPHERIC INTERVENTION

## without protection, everything will face judgement

It's entirely possible, however, it's not a "Noah's flood". Things will die slowly, but completely.

Location
This is important, as you'll need a thick, forested area where there is plenty of foliage. I recommend the American/ Canadian Midwest, or the vast, low-population Russian forests.

Preparation The goal here is to strip the atmosphere of all protective qualities. This means that we have to reach a global supercritical temperature, where the earth becomes so hot it strips itself of an atmosphere. How hot is that? An average day temp of 100C will slowly ebb the oceans away, and once the oceans are gone, life will go. You'll also need to stockpile Flourine. The world puts out 5,000,000 Tons of Florine a year. Let's say that we put 1/2 of that (in the 10 year span) towards destruction, or 100,000,000 Tons. Let's put the entirety of that into carbon tetraflouride, where 1 molecule of said compound has the effect of 7350 molecules of CO2, and lasts many times longer.

We can do better, though. Sulfur hexaflouride, most notable for the deep voice it gives you upon breathing it in, is 400% more potent than Flouromethane, with only 50% more cost (sulfur quantity availability is much more than Florine). On top of that, it's atmospheric lifetime is 3,200 years, so it's rather static. With 100 megatons of Florine, that comes out to the equivalent of 1.986 Teratons of CO2 for the first 20 years. To compare, our CO2 output estimate for 2018, that's 50 years of CO2 output in a few moments.

That's not enough, maybe to kill all land animals, but not most creatures in the sea.

See, Sulfur hexafloride just heats the planet, there is still protection provided by the atmosphere. For that, we're going to use a different compound: Halon 1301. This chemical is used in fire extinguishers to fight chemical fires, and we could reasonably produce 1.81 million tons, given the limited capacity of Bromine production of 250,000 tons per year. This is capable of eliminating 1,310 megatons of ozone. Compare the 1.81 million tons figure with the 790 tons of 1301 released in 1997. Releasing this quantity of 1301 would be the equivalent of 2291 years of pollution (we used CFC aerosols for 50 years).

The event

Here's a prediction from NASA of of the ozone concentration if we continued using CFCs for another 60 years:

The damage above would be only 5.24% of the total possible damage such an event would cause.

With ozone being out of the equation, Ionizing radiation is much more common on earth now, along global warming being 50 years more advanced. by no accurate calculation, I'd estimate a global temp increase of about 15C because of the Sulfur release alone.

The atmosphere is now toxic
Normal life cannot exist using the atmosphere for air, as ionizing radiation can now liberate atoms from the surface to create spontaneous gasses.

The Oceans are now toxic
As the atmosphere befalls to this, so does the ocean, and oxygenation from algae is no longer possible.

The Oceans are now super-salinated
As water evaporates off in extreme heat, the concentration of salts and minerals in the water skyrockets, killing off most creatures.

The surface is now dust
eventually, all non-human land creatures succumb to drought or kidney failure. what's left of the surface is inorganic structures, and dust.

The ocean is nearly uninhabitable
With the exception of extremophiles, all life in the ocean is gone.

Humanity's final Hurrah: The nuclear anthem
with all food being gone except twinkies, humanity decides it's time to set off the nukes (though the nukes were on a timer since you released the gas). They launch and race into the plasma that's shortly above everyone's heads. With all nuclear bombs at hand, the major targets are: The Chile super volcano, The Wyoming super volcano, and a few more in the Philippines, along with any remaining human settlements.

With a little luck, over 15,000 cubic kilometers of mass, or 0.00000178% of it's total mass, but that figure isn't important, what is important is that the mantle now has open ejection channels, and that the crust, is more or less, sinking, and weakening the magnetic field of the earth.

eventually, the earth turns into a clone of Venus, with acid rains, slowed days, extreme heat, and most importantly, no life. Even the extremophiles have no means of reproduction, as their environment has changed so much. a sterile planet.

edit: This is not a 30-day extinction event, but rather an event in 30 days that tips the dominoes towards impending doom. It's unlikely that anything would go extinct as a result of the events in the first 30 days.

• You could explode all the nukes in the world again and again and again and you would not cause the the crust to sink, nor even scratch the magnetic field of the planet. Jun 7 '19 at 22:20
• @Renan Sink is relative. didn't mean sink like the titanic, more sink like when it rains in a canoe Jun 10 '19 at 21:52

Mass Extinction

Life on Earth has recovered from five mass extinction events. Definition: more than 75% of species become extinct. The closest life came to being ended completely was "the great dying" of the late Permian mass extinction which eliminated 96% of extant species and nearly ended life completely.

In this 20,000 year period a huge volcanic eruption in Siberia released large amounts of CO2 into the atmosphere. Methanogenic bacteria thrived from this CO2 plume and began contributing large amounts of methane [another greenhouse gas] into the atmosphere as well. Global temperaturs rose and oceans acidified, losing oxygen and killing fish life. This in turn released hydrogen sulfide or H2S. H2S displaces oxygen and is highly toxic to aerobic life. It was in short a radical transformation of our atmosphere and oceans to a point where they no longer supported the vast majority of extant species.

As to how you could do that on purpose using existing man-made technology? I don't think you can. Technically we are in the anthropocene 6th mass extinction, where the cause is human activity but even at our worst we aren't recreating the conditions of the Permian event. Volcanism releases far more CO2 naturally than we can on purpose and to get a bloom of methanogenic bacteria and possibly oceanic algae blooms all synchronised at once.. you'd need to know when an eruption as bad if not worse than Mount St Helen was going to occur and have stocks of the bateria ready to disperse. If you knew a way hands down to cause a volcanic eruption that bad you'd be close but it would certainly take longer than a month.

• Packing a couple dozen/hundred/thousand nukes in any single spot on the crust ought to do it. Krakatoa was only 200 MT, easily accomplished with a couple of thermonuclear bombs. Take half the US stockpile (4k?) at last count and make something an order of magnitude larger - viola, your own nukano. May 28 '19 at 14:43
• The largest bomb tested was the Soviet Tsar Bomba: a 3 stage thermonuclear device with a theoretical upper yield of 100 mt. It would make a spectacular mess but I don't see how that would actually induce volcanic activity in say a dormant volcano. Those dynamics take place well below the Earth's crust. May 29 '19 at 1:11
• It looks like the numbers have changed significantly from when I last looked at them (admittedly, that was probably 20 years ago...), but the US and Russia have easily thousands of warheads between them capable of ~half-megaton yields at a minimum. Tsar Bomba was tested as an airburst because its raison d' etre was basically a glorified firework, but planting a gigaton worth of "oops" in any relatively small area is going to have significant ramifications on a geological scale. May 29 '19 at 17:12

You could make a snowball earth using environmental chemistry, make the sky dark and kill 99% of the planets land and sea animals, but it would be difficult. Humans can make nuclear bombs 10,000 to 20,000 times Hiroshima for every bomb. Each bomb could take the worlds temperature down 1'C, if you buried it somewhere where it generates atmospheric ash, so you can potentially cool the planet by 100'C. Krakatoa took the temperature down 1.2 degrees, and it was only worth one human megabomb, i.e. 3 Tsar bombs.

If you can lift 1000 cubic kilometers of ash into the air, that's already at least 20'C or 30'C degrees drop in temperature. Humans should be able to lift about 10km3 with every bomb, so you'd need at least 100 bombs.

There is a lot of ash in Indonesia, Hawaii, and other archipelagos.

If you made as many atomic bombs as man can make, say a thousand of them, in the time given, and bury them all in places with dark ash, coal, volcanoes, you can probably trigger a darkness and nuclear winter which would destroy most of the plants, land animals and fish. After that, the small mammals, insects and mushrooms will always survive for at least a few hundred years. You could also try to manufacture botulin and sarin gas and other toxic hyper-variants in billions of tons, and combine both a snowball earth and the chemical warfare, but it would only give the planet a brief sleepy period, and then it would bounce back as good as new.

## Push the earth closer to the Sun!

I came up with this idea that may achieve that evil goal, with current technology and billions of rocket engines, in 117 years; although that doesn't suffice the requirement, I'd like to discuss with people to see if there is a better approach.

The basic idea is: using rockets to decelerate the earth so that it will get closer to the sun. As it gets close enough, I expect the "pale blue dot" becomes a "bright red dot". If the whole planet becomes (almost) a lava orb, I don't think any life-form can survive that - and no, it's not destroying the earth, so definitely not overkill. Earth just returned to a form 4.5 billion years ago.

A slightly detailed version:

• I plan to use Saturn-V, the most powerful rocket in human history.
• I will use Hohmann transfer orbit to move earth between two orbits. That's when I realized we can't achieve this plan in a timely manner.
• I want the new radius to be 0.1 AU. Apparently, Mercury at 0.3 AU is not hot enough for project lava orb (700 Kelvin).

### Math time:

some constants

# AU distance, m
au=1.496e11
# Gravitational constant, m^3*kg^-1*s^-2
G=6.67408e-11
# weight of the earth, kg
M=5.972e24

r1 = au
r2 = 0.1 * au
mu = G * M

pi=3.14

F = 3.3e7


How long does it take?

According to Hohmann transfer orbit wiki page (yup, just learned this 5 minutes ago), this process will take 117 years to make the orbital transfer

t_h = pi * ( (r1+r2)**3 / (8*mu) )**0.5 # 117 years


What is the change of speed in each process?

Hohmann transfer requires a two-step speed change. Delta_v of each process is surprisingly small - 29m/s and 56m/s decrease in speed.

delta_v1 = ((mu/r1)**0.5) * (((2*r2)/(r1+r2))**0.5 - 1) # -29.6 m/s
delta_v2 = ((mu/r2)**0.5) * (1 - ((2*r1)/(r1+r2))**0.5) # -56.9 m/s


How can we achieve that!

I plan to use Saturn_V (with Rocketdyne F-1 engine), THE rocket that sent Apollo XI to the moon. I disregarded the time needed to construct and assemble these rockets.

Assume we have precisely one year for the first deceleration and the second deceleration, how many Saturn_Vs do we need to ignite at the same time to achieve the Hohmann transfer?

burn_1 = (M * -delta_v1) / (F * 86400 * 365) # 1.7e11
burn_2 = (M * -delta_v2) / (F * 86400 * 365) # 3.3e11


Whoa! 170 Billion and 330 billion rockets, not including the amount of kerosene fuel wasted in this process. This will most likely tear the atmosphere into pieces, destroy the ionosphere (hello solar wind), and heat generated in this process should be able to eliminate most life forms already.

## conclusion

Project lava orb will literally take hundreds of billions of rocket engines, and 117 years to push the earth close enough to kill all life on earth. This project is based on an unreliable calculation, an unrealistic waste of resources, and 20-century technology.

But hey, we did it!

• You're using the wrong mu for the orbit time and delta-V calculations. Since you're orbiting the Sun, you use the Sun's mass for calculating the transfer orbit time, and if you do the math, you get a transfer time of around 74 days, an initial burn of 17000 m/s, and an insertion burn of 32700 m/s. The faster transfer means you need to perform your initial burn in less than a day, and your insertion burn in a matter of minutes.
– Mark
May 30 '19 at 20:21
• And now, the reason for the downvote: if you feed the corrected numbers into the Tsiolkovsky rocket equation, you'll find that you need to fuel your rockets with about 17 million times the mass of the Earth. Even your original, incorrect numbers require 3% of the mass of Earth as fuel.
– Mark
May 30 '19 at 20:23
• As it is significantly lighter and closer, wouldn't it be more feasible to crash the moon into the Earth? May 30 '19 at 21:11
• @Myles, "more" is relative. Yes, you only need 40% the mass of the Moon in fuel rather than 17 million times the mass of the Earth, but it's still on the impractical side of things.
– Mark
May 30 '19 at 21:48
• @ChenxiGE, even the most efficient engine possible, a photon drive, will still require about 0.016% the mass of the Earth as reaction mass. It also requires so much energy that you'd be better off just melting the Earth directly.
– Mark
May 30 '19 at 22:01

The best way to answer the question, assuming the means of extermination is by nuclear bombs or other similar weapons of mass destruction is to compare what is being sought for with what has actually happened in the past. Since life is still on the Earth, then this gives you a lower bound on what is required.

Yellowstone's volcano was about 875,000 megatons when it last went up.

The dinosaur comet was about 100,000,000 megatons.

TNT Equivalent (with list of examples): https://en.wikipedia.org/wiki/TNT_equivalent

Here are the most recent snapshot of bomb counts https://www.armscontrol.org/factsheets/Nuclearweaponswhohaswhat Russia and the US have a 6000-7000 each, everyone else has a few here and there. It adds up to about 15000. The biggest Cold War nuke was around 100 megatons, so that gets you up to a max of 15,000,000 megatons; but more likely around something like 1,000,000 megatons.

That's not even scratching the surface. It barely even matches Yellowstone. You have a long way to go.

In contrast, take a look at what happens (according to Universe Sandbox 2) when our resident Evil Wannabe God-Demiurge gets into another one of his moods and puts a 1 millimeter-sized black hole next to the Earth. https://www.youtube.com/watch?v=h3KOmt9onvc

• Welcome to the site, Rock. Please note that the OP is looking for definitive proof that either A) the stated objective and can be achieved and how to achieve it, or B) why it cannot be achieved given the stated criteria. The answer you have provided here is a partial answer, explaining why nuclear weapons are unlikely to be successful. Further, you cite YouTube and Wikipedia as sources, neither of which meets the expectations of the hard-science tag. As is, this answer is likely to be flagged/deleted for being low-quality, but may survive if an edit is made. May 28 '19 at 19:40
• Welcome to the site, could you tell us how you propose to go about placing a black hole where you seem to suggest, enlisting the help of a God would not seem to fit the hard-science tag. May 29 '19 at 8:50

Well... this is highly theoretical and very speculative, but I think it still qualifies as hard science. It could be possible that our universe is in a "false vacuum" state and given the right conditions could collapse to a state of a lower energy. If this was happen to one small place, the theory is that it would spread like a "bubble" at the speed of light. You literally wouldn't see it coming. And after it has happened, the universe (in that place) would have changed with all new laws of physics and fundamental constants. Pretty sure that life as we know it wouldn't exist anymore. Heck, chemistry wouldn't exist anymore.

But, as I said, it's highly theoretical at this point and we have no idea if this is actually the case or not. But it does work for a story.

• HArd science questions require references and the like. You are providing none of them
– L.Dutch
May 29 '19 at 8:17
• @L.Dutch - I'm not an expert, so I do not know any original sources or such. I have however heard of the phenomenon and am quite certain that it's not just fiction, but rather is, indeed, hard science. If the author is interested in pursuing this avenue, I have left a link which has further information and other links, leading to other links etc. There is all that is needed for the author to start his research. Does the hard science tag also require that I do the research for him? May 29 '19 at 9:14
• @L.Dutch - In other words, I do not know the destination, but I have heard of it and am quite sure it holds what the author wants. So I do the most that I can - show him a path that he can take. May 29 '19 at 9:15
• That would do for a science based answer, but I am afraid it is not enough for a hard science one.
– L.Dutch
May 29 '19 at 9:28
• @L.Dutch - Well... OK. Still, as this is the only answer that even hints at a possible solution, I'll leave the decision of whether or not to delete it to someone else. If you feel like this should be deleted, go ahead. Or perhaps someone better knowledgeable than me will come along and improve it with proper references. May 29 '19 at 10:15

It might be.

It has been considered, as very hard science, here.

Synopsis: you would need to drop a hydrogen bomb into the sun. Deep into the sun. The problem, therefore, is to avoid the bomb being vaporised before it reaches sufficient depth to start a nuclear chain reaction within the hydrogen of the sun itself. Whether a sufficient thickness of sufficiently heat-resistant ablative material might be created and delivered into the sun, seems unlikely, but I'd prefer to have seen a proof of total impossibility.

(On the political/human front, it probably is impossible. How to hide your intent? It would just take one person out of many tens of thousands involved in such a project to sabotage it, and it's not as if you can test it properly in advance!)

• The journal you are linking to is SCIRP. Quoting another researcher: "The Chinese Publisher SCIRP (Scientific Research Publishing): A Publishing Empire Built on Junk Science." May 30 '19 at 8:19
• @toolforger I didn't know that and only rapidly skimmed the paper. It didn't trigger my usual crackpot detectors, but if you say it's better-than-average cargo-cultism I'll take your word for it! Anyway, this is Worldbuilding, not Physics. So it might be useful anyway. May 30 '19 at 8:22
• Plus, it's a pretty absurd idea that you can get a warhead into the sun and have it all work. The radiation levels are high enough to roast the detonation mechanism, the bomb would have to get into seriously high-pressure region which means it would be slowed down before it could reach the region. May 30 '19 at 8:25

We can try to adopt the method proposed here to prevent a large impact with the Earth, to let large proto-planets like Vesta or Ceres crash into the Earth, but it is unlikely to work on a time scale of just a few years. A relatively fast way could be by sending a mission to a a few comets to alter their courses to make them crash into large asteroids the size of Eros. Those collisions are engineered such that these large asteroids are sent to collide with minor planets like Vesta and Ceres in such a way that these minor planets will collide with the Earth.

• Moving Ceres around on the timescale requested basically requires a Kardashev Type II civilization.
– Mark
May 30 '19 at 20:00
• @Mark It depends on whether the "cascade" method proposed here (see also the other answer I linked to) is feasible. E.g. one may be able to engineer a collision between Vesta and Ceres by engineering a large impact on Vesta by a large asteroid. That asteroid's course was altered due to an impact by a smaller one, which in turn had its course altered by a yet smaller one, etc. etc. etc. and at the beginning of that entire chain there may only have been a change of course of a small asteroid that's feasible with current technology. May 31 '19 at 5:25
• The problem with the "cascade" method is that once you've used up Vesta, Pallas, and Hygiea, where are you going to get the dozen or so other large asteroids you'll need to put Ceres on an Earth-impact trajectory?
– Mark
May 31 '19 at 5:41
• @Mark I agree that it's not clear if it is indeed feasible (unlike the case of preventing a large impact). But then Worldbuilding StackExchange is more of a half-baked idea q&A site than e.g. Math, or Physics stackExchange. May 31 '19 at 5:57

This is a yes or no, open-ended question, where you specifically ask for hard science. I believe that, even though the majority have answered no, there is no way you could truly claim that it is impossible. You cannot prove a negative, as they say. That being said, I'd like to explore one particular path of action that might result in the earth being uninhabitable.

Colliding the moon with the earth.

I think it's safe to say that this would end all life, likely within hours. https://www.iflscience.com/space/what-would-happen-if-moon-hit-earth/

So the big question then, is can you do it in a 30 day period?

Google tells me that the energy required to stop the moons orbit around the earth is about 3.7e28 joules. That is quite a lot more than the entire nuclear arsenal of the earth. (according to google)

Now, it depends a bit on what exactly you mean by your 30 day period. If you were to produce this thrust with a rocket engine (with sufficient propellant somehow) spread out over the entire 30 days, you would have to produce roughly 1e26 watts of thrust. I believe that means you would be looking at the equivalent of roughly 5e20 f1 rocket engines on the moons surface, as well as their fuel for continuous burning for 30 days, which doesn't seem particularly feasible.

If you also had to take from the 30 days to manufacture, transport and install these rocket engines (and their fuel) it would be even more difficult. You would probably have to find a way to do most of this on the moon itself. Especially using the moon as propellant would help the equation a lot. I don't really know of any way to do that.

So my answer is: This particular method seems infeasible. (aka no)

As other answers have pointed out, humans do not and will not have the technology to do so. That leaves non-human technology. Although you've stated that you don't want to physically destroy the Earth, considering life in the cust, the only way to kill all life on Earth is to essentially make the Earth stop being.

Those aliens must be already en-route in order to get here by 2025. They are powerful. Very powerful. Any sufficiently advanced technology is indistinguishable from magic. Their spaceship is planet sized, and although 25 trillion tons of antimatter is costly, spaceship policy requires the destruction of any planet harboring intelligent life. It takes the aliens about 3 gigaseconds (~100 years) to produce such a bomb, but they've known for 15 gigaseconds that they are going to pass near enough the Earth to target it with one, and it's been many teraseconds since they last had to neutralise an entire planet (for safety and regulatory reasons, they don't stock more than a few billion tons of antimatter). They send off their 25 trillion tons of antimatter on a course to hit the Earth at 0.9c. After it hits, the Earth physically blows into pieces. Any life that isn't killed yet, will be soon by boiling, by vacuum, or by lack of water. And if any microbes survive even that, they wouldn't be life on Earth anymore. They would be life on a second asteroid belt in solar orbit.