Does anyone know...

[Bob Schroeck]

...if some enterprising fan has already run the numbers of the physics of the Second Impact cover story?  As in, "X amount of energy is needed to melt all the ice in Antarctica; delivering that energy requires a meteor of mass Y and velocity Z", with an extrapolation of real-world physical effects beyond icecap vaporization?  It occurs to me that Doug, on hearing the meteor story, might just work up his own calculations on how likely the story is, and I'd like to save myself the effort if someone else has already done it.

Thanks.
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.

[Dartz]

Not that I know of. Here's a quick shot at it:

30 million cubic kilometres of ice. 30 million million cubic meters of ice. Each of those cubic meters of ice contains about 900kg of ice/water. The energy required to melt 1kg of ice already at zero degrees is 334kJ (If I remembering my physics right.). Then heat that up to a hundred degrees celsius (4181.3 J*100).... then boil it all to vapour (1371 kJ).

So, if I 'm doing this right it takes 419835 Joules of energy to go from 1kg of ice a 0 Celsius, to 1kg of water vapour at 100 degrees.

Multiply by 900 to get the energy required to convert a cubic meter of ice into steam. 377851500J That's a big enough number.

Multiply that by a million. Then by a million. Then by thirty. 1.2595*10^19 Joules. (If my text-box wikipedian maths are right. I can dig up my college thermo notes to make certain).

And that's just to heat the antarctic ice sheet from 0 degrees, up to 100 and boil it. You don't even have to boil... just melt it. (Giving 1.2554*10^19)

Compare with the Dinosaur Killer which, wikipedia-fu suggests was about 4×10^23 Joules of energy. The result's actually less insane than I expected. But not all that energy goes into vapourising the ice, there's gigatons of rock that have to be excavated to to form our crater, debris has to be blasted into orbit. And not included is the massive kinetic energy required to shift the Earth's axis by a couple of degrees.

That takes something the size of the moon.

Come to think of it. The coverstory was that it was a 5cm pebble screaming in at about 95% the speed of light. The kinetic energy of that is only ever going to be in the vicinity of x*10^16 Joules.... even taking into account relativity. Since a 5cm pebble is going to weigh less than a kilogram..... it doesn't come close.

Edit: Unless it was made of something hyperdense like a chunk of a neutron star or something. If it's a neutron star shard this actually makes a lot more sense considering how massively dense they are.... Meanwhile scientists who don't know any better trying to explain how something so small dense could possibly exist.
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--m(^0^)m-- Wot, no sig?

[Bob Schroeck]

Okay, I think that's enough for me to have Doug do a back-of-envelope calculation and then call bullshit on 2I... Thanks!

(BTW, Dartz, I was thinking along these lines because I just finished rereading the extant chapters of New Perspective Evangelion -- apparently I got distracted away from it at some point because it seemed like the last 20% or so was completely new to me. Anyway, that nudged me a bit off of Harry Potter and back to NGE; maybe I can break out of the stall I went into after Doug's arrival, now...)
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.

[Dartz]

Grand so. I've always been a little bit curious about this step.

I went back a while back and cleaned up the earlier parts because they were so 'old' compared to what I was doing, so 20% of it or so probably is completely new. And I've been steadily chipping away at the next part for what seems like an age.
________________________________
--m(^0^)m-- Wot, no sig?

[Sweno]

well I found a neat tool you can play with:
http://www.purdue.edu/impactearth

The sad fact is that anything big enough to shift the axis of the earth would make the dinosaur killer look like a wet firecracker.
So we are left running with 'no more seasons' due to massive environmental fallout (I'm willing to swallow that dumping that much energy into the atmosphere will change things for decades unless a climatologist and a astrophysicist want to explain why it won't work).

But if you are looking for ways to dump massive amounts of heat (to melt the ice cap) into the atmosphere, then doing a bit of reading on the Tunguska event. It blew up mid air and dumped almost all it's energy into heating the surrounding area.

Regarding the possibility of the 5cm impactor being made of something significantly denser than iron. Neutron star stuff won't survive on small scales, the electromagnetic forces would make it expand to normal matter sizes without gravity to hold it together.

[I hope this sounds cognizant, I can never tell how coherent I sound at late at night]
-Terry
-----
"so listen up boy, or pornography starring your mother will be the second worst thing to happen to you today"
TF2: Spy

[Dartz]

That tool was so much help for the tenth angel.

Chances are such a massive rise in sea level so quickly would lead to a massive shift in climate. Without such a concentration of cold at the bottom of the world it's entirely believable that temperatures would warm up. And get wetter with much more water to evaporate and much more heat to evaporate it.

So, hot, muggy, rainy.... A Jurassic climate. And sea levels 60 meters deeper and still rising as remaining ice caps worldwide start to let go.

World population has died back to around 1960's levels.

And physicists are going mad trying to figure out where all the energy in Second Impact came from. And the only theory they can come up with is a chunk of Neutron Star or micro-black hole or Strangelet or some utterly ridiculous physics that must be true because it just happened. Funding is of course, being diverted to this big thing in Japan.
________________________________
--m(^0^)m-- Wot, no sig?

[Dartz]

Just thinking of this, I grabbed this sea-level rise link from slashdot:

http://flood.firetree.net

To see what Second Impact will do to the world, set it to 60m.
________________________________
--m(^0^)m-- Wot, no sig?

[Black Aeronaut]

Interesting. Always wondered what the US would look like in a case like this.

Notable items:

Eastern Seaboard is pretty much gone, going as far inland as Washing, DC and Richmond, VA.

On the western side, the Puget Sound got a bit bigger, Portland and the valleys further south get turned into inland lakes, and the Bay Area flooded over into the Sacremento Valley.

South, Florida is gone. Full stop. The Mississippi River Valley becomes the Mississippi River Inlet. And the Texas coast moves about fifty miles inland, taking Houston and Corpus Christi with it.

[Jorlem]

I think the map is glitching for me. There's an unnatural looking diamond shape in Florida, which seems odd.
Edit: Also, the areas that are north or south of  60 degrees latitude will apparently be unaffected.  Good to know. 
-----
Stand between the Silver Crystal and the Golden Sea.
"Youngsters these days just have no appreciation for the magnificence of the legendary cucumber."  --Krityan Elder, Tales of Vesperia.

[ECSNorway]

There are a couple more of those 'diamond' flaws elsewhere -- Myrtle Beach, New Bedford, etc.

And it doesn't predict any effect on the Great Lakes, either, which I'd expect from a change that massive....
--
Sucrose Octanitrate.
Proof positive that with sufficient motivation, you can make anything explode.

[Foxboy]

Well, Lake Champlain becomes part of the St. Lawrence Seaway... and it was one of the Great Lakes... for all of 30 days.
''We don't just borrow words; on occasion, English has pursued other languages down alleyways to beat
them unconscious and rifle their pockets for new vocabulary.''

-- James Nicoll

[Norgarth]

There are a couple more of those 'diamond' flaws elsewhere -- Myrtle Beach, New Bedford, etc.

And it doesn't predict any effect on the Great Lakes, either, which I'd expect from a change that massive....

Well, Lake Ontario (the 'lowest' of the lakes, drainage-wise) is 74m above sealevel according to wikipedia, so a 60m increase wouldn't (quite) reach it, let alone the other lakes. 
___________________________
"I've always wanted to be somebody, but I should have been more specific." - George Carlin

[robkelk]

However, the Great Lakes should be slightly larger than they are now. Some of the water that flows out of them and 60m down to sea level now would remain staying in the lakes (much like the water doesn't flow out of a sink with a backed-up drainpipe)...
--
Rob Kelk
"Governments have no right to question the loyalty of those who oppose
them. Adversaries remain citizens of the same state, common subjects of
the same sovereign, servants of the same law."

- Michael Ignatieff, addressing Stanford University in 2012

[Bob Schroeck]

Hm, I'll have to take a look at this after work.
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.

[Norgarth]

But (to continue the anology) the drainpipe isn't backed up, it's just shorter.  The outflow channel from the great lakes hasn't changed it's cross-section/capacity, just the distance before it reaches sealevel.  Instead of the pipe carrying the water down to the basement, it's spilling onto the bathroom floor, but the sink is still draining at the same rate.
___________________________
"I've always wanted to be somebody, but I should have been more specific." - George Carlin

[Disruptor]

There is a very small problem with Antarctica. The same problem that the arctic circle is currently facing. The methane gas underneath the ice.

Antarctica is a very big bomb and should it catch on fire and explode, it will remain constantly burning and probably trigger the volcano underneath Old Faithful in Yosemite National Park when it explodes.

[InsaneTD]

That might help explain the crater actually. Meteor air bursts, pressure wave cracks the ice and heat boils off the water. Methane rich soil also gets super heated and methane quickly escapes the soil. Heat might dissipate quickly enough to not ignite the methane so no secondary explosion?

[Disruptor]

Well according to Enoch 1(one of the Dead Sea scrolls), Antarctica is supposed to catch on fire and remain lit for a very long time(1000 years)

Evangelion is the one who messed with the Dead Sea scrolls and says that they are canon for their universe and one of the Dead Sea scrolls flat out says Antarctica catches on fire.

There is actually supposed to be a war with the grey aliens/fallen angels down there according to Enoch 1. There are also the 200 Watchers down there as well. They were bound with chains of darkness, having rocks shoved into their mouth and having lava being poured over them after they were forced to watch their children slaughter each other before their eyes. God was a tad upset with them for mating with human women and having 450 foot giants for children and teaching men all the different ways to sin. As to those angel/human hybrids that killed each other off? Their spirits are stuck on the Earth as evil spirits or demons.