
How to destroy the Earth (completely) - aycangulez
http://qntm.org/destroy
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DeusExMachina
Already discussed here: <http://news.ycombinator.com/item?id=998734>

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stcredzero
This is an amazing topic for getting scientific misconceptions out in the
open. Unfortunately, it does nothing for allaying them. People keep on
insisting on ridiculous things like dropping the Earth into the Sun, even
though there are far more efficient ways to reduce the whole planet to a
featureless, lifeless molten glob. Most of the people who have the capacity to
learn from such a thread have already learned and the people left haven't the
inclination.

This particular article can't hold a candle to rec.arts.sf.science discussions
of the same topic from the early 90's.

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joe_the_user
One point of note is that is that a small-enough black hole would be
essentially harmless.

See <http://www.aip.org/pnu/2008/split/871-1.html>

Obviously, there is a tipping point where a black hole becomes dangerous - but
it's worth remembering that gravity is the _weakest_ of the major forces. Any
physics geeks care to calculate how long it would take an Everest-sized black
hole to eat the earth?

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ars
The calculations are impossible without lots more details, but do you mean
Everest volume, or Everest mass?

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joe_the_user
Given this is entirely for entertainment purposes, any back-of-envelope
speculation will do.

The article does mention Everest mass.

Everest volume would, of course, not be a "small" black hole at all.

~~~
ars
Oh. I read this article years ago, so I didn't re-read it.

Everest mass would be a very tiny black hole.

As it oscillated back and forth it's picking up momentum from the earth, which
slows down the oscillation. It would end up right in the center, but not
moving.

After that it will wait for the pressure of the earth to feed it mass.

~~~
lisper
The inner core of the earth is solid. It's conceivable that the black hole,
after it has settled down, will simply carve out a little cave and sit there
in the center without accreting any more mass. In fact, I don't think you can
completely rule out the possibility that this has already happened.

~~~
jules
Wouldn't that be an unstable position? Even if the earth was a perfect ball
and the cave was a perfect ball exactly in the middle then the gravity
everywhere inside the cave is zero, so if you gave the black hole a little
push it would crash into the earth again.

~~~
ars
The center of the earth is the position that is "lowest" if you moved away
from it gravity would cause it to "fall down" back into the center.

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vecter
That is completely false. Modelling the inside of the earth as a hollow
spherical shell, the force inside at all points due to the gravity of the
surrounding shell is 0.

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ars
But it's not actually a shell.

In a solid sphere there is always force, and it always points to, and is
lowest, at the center.

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vecter
I assumed the black hole carved out a spherical hole in the center of the
Earth. If it was inside it, then it would be inside a spherical shell (a very
thick one at that).

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ars
But, you said it would be unstable, while actually if it crashed into the wall
the resultant forces would put it back somewhere in the middle.

Or more accurately oscillating back and forth in the middle, but not touching
the wall.

If there was any vapor in the middle (which seems likely to me, considering it
would be a perfect vacuum at pretty extreme temperatures), then the gas would
eventually slow down the oscillations and it would end up exactly in the
middle.

~~~
joe_the_user
Well, it would be sucking up the matter on the walls as well..

BTW, Sci fans of yesteryear were disappointed when it was discovered that
Dyson Spheres and Ring Worlds gravitationally unstable...

~~~
ars
> it would be sucking up the matter on the walls as well

It won't. The first time it touches (or comes near) the wall it will take what
it can get, but it will never go farther than that. There is nothing that will
"push" it closer to the walls.

~~~
jules
You are missing the crucial point. The force in a cave in the middle of the
earth is ZERO, there is NO force directed to the center of the cave. This is
not an intuitively correct statement, but if you carry out the calculation you
will see that it is true. If you take a solid sphere and carve out a spherical
cave in the center, then everywhere (not just in the center) inside this cave
all the little forces from all the atoms of the big solid sphere cancel out.

So this means that inside the cave the black hole will just move in one
direction, until it hits the wall. Then it will suck up some mass and be
pulled back to the center. Then it will suck up some mass on the other side,
etc.

The only way the black hole will remain in the cave is if you put it in the
cave with exactly zero velocity to begin with. As soon as one atom falls into
it it will start to eat up the earth.

~~~
ars
No, I am not missing that point.

You are missing a point.

Yes, inside the cave there is no force. But the black hole can hit the wall
just once. After that it can not go any farther.

If passes thought/inside the wall it will be pulled back to the center, and
the momentum exchange with the earth will slow it down (so next time it won't
go as far). If it was just touching the wall, then that is as far as it can
possibly go.

So once it's inside it's little cave, it's done. It can't eat anymore. (Unless
of course there is no cave and the earth feeds it, but we are assuming a
cave.)

You are missing three points: one is that if there is no cave, and it's
oscillating through the earth, it will be pulled to the center. Two is that it
looses momentum each time through the earth. And three is that once it's
inside it's hollow cave it can no longer reach the wall.

~~~
jules
I don't know what to say. On one hand you seem to agree that there is no force
to slow the black hole down inside the cave, but on the other hand you claim
that the black hole will remain inside the cave.

> You are missing three points: one is that if there is no cave, and it's
> oscillating through the earth, it will be pulled to the center.

Agreed.

> Two is that it looses momentum each time through the earth.

I'm not so sure about that. Mass is added to the black hole, and perhaps this
causes the total momentum to increase.

> And three is that once it's inside it's hollow cave it can no longer reach
> the wall.

If it is stopped inside the cave. But there is no force to stop it.

~~~
ars
Well we agree on the basics, that's good.

Imagine a tiny black hole arriving on earth. It grabs some mass. The black
hole is moving, but the mass it ate is not. So rather than free falling, it
looses momentum. As it falls through the earth it keeps doing that.

So it will not rebound back up to the top at the same height it fell. It will
be lower. The second time through the same thing will happen.

Each time it oscillates it will get lower and lower.

Next. Say the black hole is a bit bigger. And it eats some mass on one side of
the earth - now there is an imbalance. There is more mass on the other side.
So the forces will cause it to slow down more than it otherwise would.

When it finally settles down enough to make a cave, it will "swing" as much as
it can. But each swing can not be any higher than the one before. Over time,
with random atoms falling into the cave it, it will come to rest at the exact
center.

~~~
jules
Assuming the cave is spherical, each swing will reach the other side, because
inside the cave the black hole will not be slowed down, do you agree? So in
this perfect situation, it is impossible that the black hole will come to stop
exactly in the center. Even _if_ it was stopped exactly in the center, if one
atom hits it from one side, the black hole will crash into the other side (but
slowly of course).

~~~
ars
I see your point (I didn't before).

There is no force on the black hole, so if it moved at all it would crash into
the wall. Only when it actually ate some of the wall would it turn around. So
each swing would eat more and more.

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dennisgorelik
That article is a good demonstration of scientific entertainment. I liked that
method: \--- "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...'" \---

~~~
stcredzero
Many think that all we have to do is show:

1) we are here

2) that we're savages who have nuclear weapons and who are perfectly willing
to use them on _each other_.

3) we're going to develop interstellar spacecraft

I think many civilizations worthy of the name would want to bomb us before we
get out of Earth's gravity well en masse.

~~~
sliverstorm
In the grand scheme of things, I have come to realize nuclear warheads are not
that fearsome. Thus far they have caused less damage to the surface of the
earth than a pimple causes to your face. And the earth is insignificantly
small.

They are definitely scalable, but they are certainly no Dr. Device

~~~
stcredzero
Interstellar drives are the dangerous bit. The point is that we have a history
of being willing to use weapons of mass destruction on our own species. This
should make other species a bit nervous.

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Avshalom
There are a couple of comments here about the phrase "destroy the world"
normally referring to life on earth.

In that vein I'd like to say that killing all life currently within 6500
kilometers of the Earth's center of mass is, in some ways, harder than simply
destroying the Earth.

Take for instance the humble Water Bear they range from microscopic to a
millimeter in size and can survive being frozen to within a degree of 0k and
have survived 10 days in hard vacuum, during which time eggs were laid and
hatched. It seems likely that any of the various "disassemble Earth" methods
would fail to kill them. Similarly any chunk of Earth with a sealed ecosystem,
like some caves, might continue to keep going indefinitely.

Killing everything might _require_ vaporizing the planet in the sun or eating
it with a black hole.

~~~
stcredzero
Heating the biosphere and the crust to a depth of 5 miles to 500 degrees and
keeping it there for at least a couple of hours would likely do it, even for
the Water Bears and _radiolarens_. That could be accomplished with
asteroid/comet bombardment. The energy budget for that is many orders of
magnitude smaller than most of the proposals in the article.

~~~
Avshalom
Well you'd probably want to go deeper than 5 miles to be sure. But a massive
comet strike doesn't guarantee the sterilization of ejected material which is
really the difficult part. Because there is life that can handle vacuum you
have to not only heat the world to 200C (we think) but you have do it in a way
that nothing larger than individuals molecules escape due to heating. which is
also tricky because at some altitude in the atmosphere evaporative cooling
might allow for something to survive indefinite periods of superheated crust.

EDIT: really what it comes down to is how many 9s of biocide do you want.
Ramming Luna into the Earth might accomplish 7 or 8 9s, but if you want to
kill _everything, 100% of life from LEO down_ not just _practically
everything_ it's going to take more finesse than that.

~~~
stcredzero
Heating the biosphere by using a large cloud of orbital mirrors and inducing
runaway greenhouse might accomplish your goal of 100% containment and
sterilization, but if a few mites and microorganisms escape, that's close
enough for me.

~~~
Avshalom
slacker

~~~
stcredzero
It's called GTD. Getting Things Destroyed!

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blitzo
They left out one possible solution: create a time machine to traveled back to
a minute before 4.54 billion years ago. Equipment needed: high-pressured
suction vacuum machine preferably solar-powered with a dustbag hard enough to
store around 1.08321 × 1012 km3 mass volume of solar's dust and gas left over.
Contrary to popular believe, it is actually easy to shop for a decent time-
traveled machine: imdb.com Feasibility: 1/10

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pvdm
"Give me the place to stand, and I shall move the earth." Archimedes. Said to
be his assertion in demonstrating the principle of the lever.

~~~
ErrantX
Moving the Earth is dealt with in some (err, much) depth here:
<http://qntm.org/moving>

In terms of Archimedes:

 _"Give me a place to stand, and I will move the Earth", proclaimed Archimedes
upon discovering the principles of leverage. Unfortunately, that place needs
to be immovable, which is impossible. Also, what he didn't specify is that he
also needs an equally immovable fulcrum - equally impossible - and a lever of
stunning length which is unbreakable. Hah! Nice try, Archimedes._

~~~
astine
"Unfortunately, that place needs to be immovable"

No, it merely needs to be of sufficient mass. As a practical strategy for
moving the earth, this would clearly be infeasible, but, strictly speaking, I
don't think that it is impossible.

~~~
dhimes
When Newton came along we realized that all we needed to do was jump. Granted,
we don't move the earth very much, and it comes right back, but still...

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dmoney
Destroying the Earth is kind of overkill. Unless you're making way for a
hyperspace bypass, most supervillains' needs could be served by destroying
what makes it different from any other planet. Burn off the atmosphere, melt
the crust, release a metagenic virus that kills the biosphere, dump 130
million gallons of oil into the Gulf of Mexico...

~~~
ars
And?

Did you read the article?

~~~
dmoney
And what?

I read it the last couple times it was posted here.

~~~
ars
And so what if destroying the earth is overkill.

That isn't what the article is about.

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bkudria
This is fun and all, but my question is: what happens when all the honeybees
die out?

~~~
eru
Let them eat cake.

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pesco
This is completely old, but so funny every time, I have to up it. :)

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bitwize
An Illudium Q-36 Explosive Space Modulator will not suffice?

~~~
stcredzero
Wabbits. (Admittedly, not the best reference, since there was no FUD in that
episode.)

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greenlblue
Hilarious.

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mkramlich
Talk about exactly the kind of article title I wouldn't want to be easy to
find by bad guys.

~~~
sliverstorm
If they have the kind of time, money and resources to pull these things off, I
think their discovery of this article is the least of our problems.

I mean, if you've got 25,000,000,000,000 tonnes of antimatter just laying
around in a warehouse somewhere, I don't care if you want to kill me and
destroy the earth- I want to shake your hand.

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mseebach
This is somewhat entertaining, but it's a giant strawman. When someone talks
about destroying earth, they don't mean literally making the planet cease to
be a such, they don't even mean annihilating humanity. They mean permanently
making earth a significantly less pleasant place to live for a significant
portion of its population. Such as, cutting down the rain forest, disrupting
the CO2 pump (or whatever) and lowering the air quality with more disease to
follow (or some variation - either way, it's still a planet, and it's still
very much populated by humans).

~~~
jerf
When a writer chooses a definition, as long as the definition is not insane
("When I say 'brutal murder', I actually mean the color purple"), you really
have to go along with it. English is not a sufficiently precise language to be
immediately suitable to the expression of all ideas.

I don't know what the original title was, but I do know the contents of the
article, in which the author makes it abundantly (and if you read everything
in that section, repeatedly) clear that he is aware of the usual use of the
phrase "destroy the Earth". It is not a "strawman", it is the _topic of the
essay_. If anyone is erecting a strawman, it is those who refuse to deal with
the text on its own terms and insist on forcing their personal definitions of
various terms onto the text, despite clear, repeated disclaimers, and the
obvious fact that the entire idea of the essay is predicated on the author's
definition.

Maybe you were just reacting to this title, but this has been linked in a few
places and every time it seems this reminder needs to be given, so even if you
are now satisfied by the new title, this still needs saying. An author is free
to choose their topic and the precise meaning of some of the terms they are
using; nothing else makes any sense.

~~~
stcredzero
Insane? How about nonsensical? The "blow up the earth real good" goal is of
the mentality of someone who watches Star Wars and decides the movie portrays
real physics. Vaporizing the oceans and turning the crust into molten lava is
plenty of destruction. It's also many orders of magnitude less energy than a
lot of the patently unphysical proposals in the article. Equivalent mass of
antimatter? You'd need a lot less than that to exceed the gravitational
binding energy of planet Earth, and even that is ridiculously inefficient.

That's like the proposal to achieve AI by simulating a whole human body down
to the molecules. It sounds clever to college freshmen, but it really just
shows people are ignorant of the orders of magnitude of what they're
discussing.

