Science-based what-if questions

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Re: Science-based what-if questions

Postby Sableagle » Fri Sep 30, 2016 7:20 pm UTC

lorb wrote:
Sableagle wrote:[...] nobody wants to ski on really hard surfaces. [...]


Elite/high level competitive alpine skiing is done on very very very hard snow. Basically ice.


I wonder, though: do they enjoy it? All the "oh yeah" stuff I hear is from people finding untouched powder.

Thanks to my knees, I can't really do all the jumping involved in deep off-piste powder any more, but a few inches over a "real dairy ice cream" textured slope are still awfully tempting. There's just something about doing an even series of turns through an open powder field, then going back up and doing it again and again and again to create an even pattern across the slope for people to admire from the chairlift or cable car ... until some idiot snowboarder wipes out through the middle of it. I've tried skiing on hard (black) ice and ... it's like skating on badly-designed skates with a pendulum on a bar on the front and back of each foot.

They race on very hard-packed and sun-crusted snow to get high speeds, because everyone wants to see them go really fast (see also tennis serve speeds), but given the choice of surface on which to spend a week skiing, whether touring or teaching, I think I'd choose the sorbet. It's probably easier to wash out, if nothing else.
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10 kg of antimatter

Postby andykhang » Thu Oct 13, 2016 5:20 pm UTC

What happen if you put 10 kg of antimatter into the core of the earth:

1. Through a straight, vacuumed hole into the center?

2. Instantly through a 1 way portal?

And what would you do, personally, to destroy the earth with the above?

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Re: Science-based what-if questions

Postby Zohar » Thu Oct 13, 2016 6:15 pm UTC

I'd rather not destroy Earth in the first place! Instead I might use it to create relatively clean energy. Though I wouldn't be surprised if any energy produced by matter-antimatter interaction would result in deadly radiation, too...
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Re: Science-based what-if questions

Postby Xanthir » Thu Oct 13, 2016 6:16 pm UTC

Basically nothing would happen. The earth is gigantic, 10kg of antimatter is comparitively miniscule. Check the Geocide Guide (#6 for exploding the Earth) for more details.
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Re: Science-based what-if questions

Postby commodorejohn » Thu Oct 13, 2016 6:25 pm UTC

Well, the vacuumed-hole approach might make for a nice Roman candle kind of display.
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Re: Science-based what-if questions

Postby p1t1o » Fri Oct 14, 2016 8:32 am UTC

commodorejohn wrote:Well, the vacuumed-hole approach might make for a nice Roman candle kind of display.


Ooh, some random knowledge in my head just tickled!

During underground testing of nuclear weapons, it was found that boreholes carrying sensors would be sealed by the shockwave, reducing fallout. So it looks like a roman candle would be unlikely :(

**

Just out of curiosity, lets do the math (because its easy math and makes me look clever, mainly):

Lets assume that the 10kg AM annihilates with 10kg regular matter.

E=20*c^2=1.8e18J
1megaton=4.18e15J
1.8e18=430megatons

Big, yeah, but not a planet-killer.

Want more random knowledge? The Star Trek (Next Gen) Technical Manual states that a photon torpedo contains 100kg af antimatter (and 100kg of matter, arranged in small particles to ensure as close as possible to a complete reaction.)

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Re: Science-based what-if questions

Postby Soupspoon » Fri Oct 14, 2016 10:41 am UTC

Or one Spock.

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Re: Science-based what-if questions

Postby p1t1o » Fri Oct 14, 2016 12:26 pm UTC

Soupspoon wrote:Or one Spock.


Potential for a nice new unit of energy, 1 Spock (Sk) = 4300megatons, or 1.8e19J

andykhang wrote:And what would you do, personally, to destroy the earth with the above?


I think the most destructive use of 10kg of antimatter, would be to use it to create a large collection of antimatter-catalysed fusion weapons.

With antimatter, you can compress a lithium deuteride secondary without requiring any fissile material whatsoever, making the weapons much, much simpler and very much smaller and lighter. And more dangerous.

Someone with an impressive grasp of all of the appropriate mathematics could probably figure out exactly how much hydrogen you can fuse with 10kg AM, but here's a back-of-the-napkin:

The B-61 is a modern "sub-strategic" thermonuclear weapon with a variable yield from 0.3kt to 340kt. 0.3kt is assumed to be the yield of the fission primary detonating on its own.

Since these things scale relatively linearly, we can roughly extrapolate that every kiloton of primary can compress enough secondary material to generate 1.1ish megatons, a conversion factor of around 1100.

So 430 megatons worth of antimatter, ought to be enough to build a collection of warheads (or a single warhead if you like, there is no upper limit theoretically) with yields totalling...

473 GIGAtons.

Planet Earth has approx 50million square miles of land area.

If you use your antimatter to build 473000 1-megaton devices, these could be spread evenly over the surface of the Earth at a rate of 1 per 105 square miles. Meaning each weapon is allocated to a square of land approx. 10 miles to a side.

I would wager that this would be more than enough to sterilise the entire surface of the Earth quite severely, and for quite a long time. Even ignoring the effects of fallout and radiation (which would obviously be very significant) the fireball itself from a 1Mt burst will be on the order of 5-10km across, so it is possibly that sterilisation may be possible from thermal effects alone!!

This does ignore all of the life within the oceans, so with a little bit of luck, new intelligent life may once again populate the Earth sometimes in the distant future...

In conclusion: 10kg of antimatter is nowhere near the amount needed to physically destroy the Earth, but if you are smart you can achieve a "soft-kill" if you like :) even if my calculations are off by a factor of 100, probably!

(Oh and if you have enough fissile material, you can double all of those yields by constructing the radiation cases from depleted uranium, you dont need anything more fissile than that)Scratch that, Im unsure if the B61 already has a fissile casing and thus already taken into account in the above conversion. If it does, then without using fissile material, the above total yield should be halved.

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Re: Science-based what-if questions

Postby gmalivuk » Fri Oct 14, 2016 12:32 pm UTC

Zohar wrote:I'd rather not destroy Earth in the first place! Instead I might use it to create relatively clean energy. Though I wouldn't be surprised if any energy produced by matter-antimatter interaction would result in deadly radiation, too...

Even if the energy was completely clean and 100% efficient, that much antimatter would cover the planet's energy needs for about a day.

Edit: I strongly doubt you would even kill all humans with the distributed 1mt bombs mentioned above, let alone all life. Yes, most buildings would collapse and people in the open would be badly burned, but people in basements and behind reinforced walls would probably survive.
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Re: Science-based what-if questions

Postby Soupspoon » Fri Oct 14, 2016 12:39 pm UTC

gmalivuk wrote:Even if the energy was completely clean and 100% efficient, that much antimatter would cover the planet's energy needs for about a day.
Then let's declare an International Holiday!

(Might then eke out to more, depending on how many office computers are shut off for the duration and industrial processes halted or at least brought down to idle-mode levels of activity, etc...)

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Re: Science-based what-if questions

Postby p1t1o » Fri Oct 14, 2016 1:45 pm UTC

gmalivuk wrote:Edit: I strongly doubt you would even kill all humans with the distributed 1mt bombs mentioned above, let alone all life. Yes, most buildings would collapse and people in the open would be badly burned, but people in basements and behind reinforced walls would probably survive.


A proportion will survive the initial effects yes, for a while. However a large percentage of casualties are expected from burial (not much use being alive in a basement if there is 100tons of rubble covering you) and fires caused not by the flash but by broken gas pipes, destroyed boilers, spilled fuel etc. Response from emergency services would be very, very limited in a single detonation, in this scenario it would be zero.
Destruction of food producing land and various related industry (read: ALL INDUSTRY) would finish the rest. And that is ignoring the extreme levels of global fallout.

Remember, at 1 device per 100sq. miles, the furthest you can be from a burst is approx. 7 miles. Except that there would be another one 7 miles away to your right, another to the left and a fourth behind you!

**
edit:
And another 12 bursts within 21miles on top of those! This really is a cataclysmic scenario, if any human survived, I'd eat my hat!
(Oh, and if you ignore mountain ranges and deserts, you can have 1 device per 50 square miles :) )
**

And shock-induced overpressures would be heavily magnified in these areas.

**
edit:
And if you still even slightly sceptical, instead of building 473000 1MT weapons, build 23,650,000 20kiloton "Hiroshima size" (Hiroshima was a little less) devices and spread them out for 1 warhead every 2 square miles...or, ignoring mountain ranges and deserts, 1 every square mile (that is ~16 bursts within 2.1 miles, max seperation between you and a burst is 0.7miles).

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Re: Science-based what-if questions

Postby gmalivuk » Fri Oct 14, 2016 4:47 pm UTC

Sure, smaller warheads every couple square miles would be worse, but I was talking about your original scenario as described. Also, looking at it more carefully your initial numbers started off wrong by a factor of 4.

There are about 200 million square miles of land area. If you cut that in half (for mountains and deserts, which means the people already living in those places are left completely fine by the initial blasts), that's still half the density you started with.

At 166 square miles, Barbados would get one nuke. NUKEMAP calculates that an airburst over the center of the island would kill 33,705 people, injure another 113k, and leave the remaining 140k residents unhurt. (These numbers could of course be altered significantly by taking population distribution into account when deciding where precisely to detonate, but adjusting for population density wasn't part of your original scenario.)

Civilization-ending? Sure.

Surface-sterilizing? Not by a long shot.
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Re: Science-based what-if questions

Postby andykhang » Sat Oct 15, 2016 1:18 pm UTC

So 10 kg of antimatter wouldn't be enough...Exurb1a have lie to me!!!

And if you want civilization ending though, just drop that 10kg into the atmosphere and it would relatively be enough to blast a hole in the ozone layer, cooking human alive.

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Re: Science-based what-if questions

Postby gmalivuk » Sat Oct 15, 2016 6:00 pm UTC

If you put it in one place, the damage will be extreme but localized. If you spread it everywhere, it's the amount of energy the Sun delivers in 10 seconds.
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Re: Science-based what-if questions

Postby Xanthir » Sat Oct 15, 2016 6:13 pm UTC

gmalivuk wrote:If you put it in one place, the damage will be extreme but localized.


And not even *that* extreme. Assuming p1t1o's math was correct, 10kg of antimatter, fully annihilating, will only deliver 430MT. Larger than any bomb ever detonated, but still just a city-flattener.
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Re: Science-based what-if questions

Postby gmalivuk » Sat Oct 15, 2016 9:28 pm UTC

As I calculate it, based on one website's figure of 364kJ/mol to break a bond in O3 and another site's statement that the ozone layer would be about 3mm thick if all the ozone were collapsed into a layer at STP, it would take 2.5e19 J to destroy the whole thing, if all of the energy went just to destroying ozone.

The energy of 10kg of antimatter is about 5.5% of that, and wouldn't all go to destroying ozone in any case.
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Re: Science-based what-if questions

Postby p1t1o » Mon Oct 17, 2016 9:16 am UTC

gmalivuk wrote:Sure, smaller warheads every couple square miles would be worse, but I was talking about your original scenario as described. Also, looking at it more carefully your initial numbers started off wrong by a factor of 4.

There are about 200 million square miles of land area. If you cut that in half (for mountains and deserts, which means the people already living in those places are left completely fine by the initial blasts), that's still half the density you started with.

At 166 square miles, Barbados would get one nuke. NUKEMAP calculates that an airburst over the center of the island would kill 33,705 people, injure another 113k, and leave the remaining 140k residents unhurt. (These numbers could of course be altered significantly by taking population distribution into account when deciding where precisely to detonate, but adjusting for population density wasn't part of your original scenario.)

Civilization-ending? Sure.

Surface-sterilizing? Not by a long shot.


A long shot, but not *such* a long shot.


According to several sources, 200,000,000sq miles appears to be *total surface area* (196,940,000sq miles).

I went straight to the wiki for Earth and rounded the figure for land area (57,510,000sq miles) to 50mil. The figure for inhabitable area I found somewhere else and similarly rounded it to 25mil.



Given the coverage and resilience of things like bacteria, and since I am ignoring the sea (so the land could be re-innoculated at any time with at least *something*) perhaps total sterility is not literally possible, no, but I think that the sheer amount of residual radiation would give it a good ol'British try!

NB: Of course, the closer you look (eg: Barbados) the more likely the gross assumptions would break down. Plus if one was really serious, of course you wouldn't evenly spread the weapons, you'd be more picky. The model, like most, is illustrative only. On the other hand, smaller warheads are not only worse but allow a greater resolution. Barbados may only receive 1 (or 2, if you round up) weapon in the 1MT model, but in the 20kt model it would receive 83!

Anyhoo, thats with only 10kg AM. Gimme a ton and we'll talk again about your precious "bacteria".

*edit*

"Civilisation ending" - If this is all you want to achieve I think it could be done with *significantly* less destruction, since people will finish the job themselves if you remove enough infrastructure. All you need is a decent WWIII-scale scenario. Put a few large dirty bursts in the most fertile areas to seal the deal.

**2nd edit**

I wonder if another approach might be worth a look-
Use your 10kg AM as before to create 470-odd gigatons of AM-catalysed H-bombs, and use these to vaporise as much seawater as possible, with the aim of causing a runaway greenhouse effect. I have no idea if this is a workable quantity of water vapour for this purpose, but it seems like quite a lot of bang-for-the-buck in terms of atmospheric engineering with 10kg AM.

Rough calcs -
1ton TNT = 4.184GJ
Energy to boil 1L water, starting somewhere between 0-10degC, 1atm. = ~2600kJ/L
1ton TNT boils ~ 1600L water
473Gigatons TNT boils ~ 7.57e14kg water

Current atmosphere approx 0.4% water vapour
Mass of atmosphere ~5.15e18kg
Of which water vapour = 2e16kg

473Gigatons of boiled water will only net you a few percent increase in water vapour globally. Probably less. Is this enough to spark major changes?

Or would the dust raised from land-based detonations be a larger concern?

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Re: Science-based what-if questions

Postby gmalivuk » Mon Oct 17, 2016 12:22 pm UTC

So much for Googling "land area of Earth", I guess.

Water can absorb a huge amount of heat before boiling, and then has the audacity to rain back down very quickly after reaching the atmosphere. Plus this scenario only increases humidity by a few percent to begin with. I imagine that bu itself would result in a short period of heavy rain followed by getting mostly back to normal.

I think all the live steam in the air would be a bigger problem, at least while it was concentrated near the surface, but even then it's only 0.01% the mass of the whole atmosphere, so the long-term impact on air temperature would be minuscule.

tl;dr - We'd probably have lots of rain and fucked-up weather for a few days before things returned mostly to normal.
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Re: Science-based what-if questions

Postby p1t1o » Mon Oct 17, 2016 12:28 pm UTC

gmalivuk wrote:snip


Land strikes it is then!

All this just goes to show...dang, planets are BIG hey?

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Re: Science-based what-if questions

Postby gmalivuk » Mon Oct 17, 2016 3:36 pm UTC

Even when an entire population is within the 8psi overpressure radius, NUKEMAP suggests many will survive and some won't even be injured badly.

(Obviously the exact geography of an area will have an effect, I'm just using islands to focus on the casualty rate within small distances of one explosion, because the site doesn't map multiple blasts simultaneously. At only 8.1 square miles, Nauru alone could be pretty nearly wiped out by a slightly lower airburst that includes the entire island within the 10+psi overpressure radius.)
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Re: Science-based what-if questions

Postby p1t1o » Mon Oct 17, 2016 4:22 pm UTC

gmalivuk wrote:Even when an entire population is within the 8psi overpressure radius, NUKEMAP suggests many will survive and some won't even be injured badly.

(Obviously the exact geography of an area will have an effect, I'm just using islands to focus on the casualty rate within small distances of one explosion, because the site doesn't map multiple blasts simultaneously. At only 8.1 square miles, Nauru alone could be pretty nearly wiped out by a slightly lower airburst that includes the entire island within the 10+psi overpressure radius.)


I dont doubt the accuracy of that, which probably includes huge error bars, but there are a lot of things that that does not take into account. Many of these things are related to the rather exaggerated scenario we have going (for example, where exactly is that 8psi line going to be when you are firing off an infinite square grid of these things?), but it also ignores fallout, a significant factor. A VERY significant factor in our model. The next biggest thing would be infrastructure destruction. In fact Im not sure which way around those two would go, but hey-ho.

The proportion of people killed in a single strike is always going to be less than that killed in a coordinated one, and FAR FAR less than the scenario we are discussing. Have you not seen "Threads"?

The people who "survive" the detonation are the *unlucky* ones.

You are not going to be able to convince me that there will be any worthwhile survival after the astute deployment of 473 gigatons!

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Re: Science-based what-if questions

Postby gmalivuk » Mon Oct 17, 2016 4:43 pm UTC

I think I have been pretty clear all along that I'm taking issue with words like "sterilizing". I have no doubt the consequences would be horrific, and that our species would quite possibly go completely extinct as a result, but there is a fairly large gap between "uninhabitable by humans" and "sterile".
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Re: Science-based what-if questions

Postby p1t1o » Mon Oct 17, 2016 4:53 pm UTC

gmalivuk wrote:I think I have been pretty clear all along that I'm taking issue with words like "sterilizing". I have no doubt the consequences would be horrific, and that our species would quite possibly go completely extinct as a result, but there is a fairly large gap between "uninhabitable by humans" and "sterile".


Oh is that all it is, I conceded that that was quite unlikely already, keep up! :)

PS: it is the fallout that I had initially assumed would be doing the final sterilizing, not the initial heat.

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Re: Science-based what-if questions

Postby gmalivuk » Mon Oct 17, 2016 6:28 pm UTC

(Mostly I just like using Nukemap.)
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Re: Science-based what-if questions

Postby Sableagle » Sun Oct 23, 2016 5:34 pm UTC

Oh, Willie McBride, it was all done in vain.

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Re: Science-based what-if questions

Postby Zohar » Mon Oct 24, 2016 12:57 pm UTC

If you want to cause as much destruction as possible, maybe a list of thetop economically-influential cities is more relevant?
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Re: Science-based what-if questions

Postby Sableagle » Tue Oct 25, 2016 4:25 pm UTC

Also a good list to use for selection, although I'm not so sure I agree with their intro.
London should be congratulated for its remarkable run over the past couple of decades, even as the U.K.’s economy has sputtered.
That "even as" raised an eyebrow (just a half-millimetre) here. London has done well because HMG made sure it did, even at the expense of the rest of the country.

Most populous, most polluted, most violent and most economically powerful cities, then. Would the rest of us be better off, long-term, as a result of 250m-diameter iron balls doing 15km/s vertically into each city on any of those lists? If that happened to Beijing, would asthma incidence in Los Angeles be lower the next summer? What would it do to trade, to international debts, to the disputes over certain islands et cetera?

Actually, asteroids de-orbiting into cities are officially Acts Of God, which would be a very important distinction if Jerusalem and/or Mecca made the list, wouldn't it?
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Re: Science-based what-if questions

Postby gmalivuk » Tue Oct 25, 2016 4:38 pm UTC

Given that LA is *on* one of those lists, I doubt anything happening in Beijing would be their primary concern.
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Re: Science-based what-if questions

Postby p1t1o » Wed Oct 26, 2016 7:52 am UTC

Honestly, I'd just stick with the most populous. A great deal of the worlds problems boil down to population pressure.

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Re: Science-based what-if questions

Postby Sableagle » Thu Oct 27, 2016 3:40 pm UTC

gmalivuk wrote:Given that LA is *on* one of those lists, I doubt anything happening in Beijing would be their primary concern.


Well, yes, 14th, and Beijing is way down at 23rd, which brings up a similar question the other way round.

If those most populous cities started getting hit by city-killing "acts of god" at 24hr intervals, starting with Tokyo and counting down the list, what would happen in LA? Tokyo goes and everyone stares and says things like: "Wow." New York goes and people start wondering what the odds of two random impacts both hitting cities are. By the time it got to Manila I reckon the stores would have been stripped of bottled water and canned food and there would be heavy traffic with a lot of incidents. When Cairo got hit, there'd be such a stampede the rock might be kind of unnecessary. The possible body-count may already have been exceeded by the RTA body-count. How soon would an attempt be made to evacuate Beijing, and how well would that work? Where would they go? After all, if 400,000 of them go to Shenzhen it'll swap places in the list with Beijing.
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Re: Science-based what-if questions

Postby commodorejohn » Thu Oct 27, 2016 4:15 pm UTC

Sableagle wrote:If those most populous cities started getting hit by city-killing "acts of god" at 24hr intervals, starting with Tokyo and counting down the list, what would happen in LA?

I'm given to understand that it would probably look like the aftermath of a Lakers game.
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Re: Science-based what-if questions

Postby Soupspoon » Thu Oct 27, 2016 4:19 pm UTC

(If Shenzen swaps with Beijing) There'd be emperical evidence of whether the Rods From God people are using a fixed list, or going back to Wikipedia after every attack and choosing their next target according to the latest update. (Then someone can perhaps arrange for Power Cable, Nebraska, to head the list and the page protected from well-meaning reversion/malicious alternate revandalising. It'd be an interesting experiment to have to carry out.)

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Re: Science-based what-if questions

Postby gmalivuk » Thu Oct 27, 2016 4:49 pm UTC

Sableagle wrote:
gmalivuk wrote:Given that LA is *on* one of those lists, I doubt anything happening in Beijing would be their primary concern.


Well, yes, 14th, and Beijing is way down at 23rd
LA is 3rd on the first list of economically powerful cities, and it was one of the ones you mentioned yourself in your post that linked to the population list.
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Re: Science-based what-if questions

Postby Sableagle » Fri Oct 28, 2016 11:08 am UTC

I do not deny that. It was just an example of a long-range effect that may not be immediately obvious.

If Sin-majority cities were hit, would China have to be renamed Hannah? If the East End of London got hit, would What's On TV go out of business? If Fred Phelps got hit, would there be a www.godhatesgodhatesfagsdotcom.com website? What if the Three Gorges Dam took the impact? A 0.175 * 660 * 1.1 km wedge of mucky water held back by a concrete wall on two faultlines has to look like a tempting target for a spiteful god. V≈4.24×1010 m3. 42.4 gigatonnes of dirty water waiting for an excuse ...
Anybody know how to calculate how deep it'd be in Wuhan and how long it'd take to get there?
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Re: Science-based what-if questions

Postby Copper Bezel » Sat Oct 29, 2016 6:42 pm UTC

Well, I have some good news for you, at the very least - Fred Phelps is already dead.

Edit: No such luck for soap opera, it seems.
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Re: Science-based what-if questions

Postby Sableagle » Sat Oct 29, 2016 7:29 pm UTC

On a cheerier subject, today there was a ladybird on my car window, tucked up against the upper seal, out of the wind. This made me wonder whether spiders and ladybirds can mix otherwise isolated populations by hitch-hiking on commuters and thereby avoid genetic bottleneck effects.
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Death ray from above.

Postby andykhang » Sun Dec 25, 2016 4:28 pm UTC

Suppose I have an absurd amount of nanomachine in my hand with perfect control to each and every one of them (through dubious mean). I was having an intention to create a death ray from above, using the sun ray, concentrated by water droplet in the sky to converge them into a beam capable of heating an object (let said human) to 1000 degree Celcius and above. Let said I just need the diameter of each beam to be 70 cm, and I would need to have 1000 of them beam. How much would I need: From the area to collect the sun ray (for ease of calculating, let said from the cloud-less level), to how much water is needed,etc...?

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Re: Death ray from above.

Postby Tub » Tue Jan 03, 2017 11:32 pm UTC

Have you read https://what-if.xkcd.com/145/ ? It'll tell you why the idea you're having doesn't work that way. You can't have a death beam, you need a focal point. Considering that the sun's surface is only about 5500°C, you cannot de-focus your beam too much if you want to reach 1000° on the target. It's also going to be a huge lens if it's supposed to be in the upper atmosphere; you can go smaller if you get closer.

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Re: Science-based what-if questions

Postby andykhang » Sun Jan 08, 2017 12:00 pm UTC

The situation applied only to one lensed though, multiple of those concentrate into a point would still work fine. I'm not saying to build 1 gigantic one in the first place

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Re: Science-based what-if questions

Postby gmalivuk » Sun Jan 08, 2017 3:20 pm UTC

No, it doesn't make any difference. No amount of simple lenses can do what you want.
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