I had a wild, intense dream last night that I was outside with some friends and we were looking at constellations. The Big Dipper started to dip toward the horizon in a big way and I realized that we had just bombed Pakistan with enough force to throw off the rotation of the earth. Soon the sun came back up from where it had gone down, and we resumed normal rotation. I was thrilled, though because I had been up too late and was worried about getting enough sleep, but after the bombing, time had been set back to the evening again, so I had plenty of time before work.
My question is: how much force would be required to upset Earth’s rotation (not in a drastic way, but enough to be noticable) and would it be too much force for the world’s population to survive?
The force is beyond thinking about, except in an abstract way.
However, some obvious problems if it was ever achieved.
Normal rotation would not resume unless the force was applied again to bring us back up to speed.
At the equator you and the earth’s surface are moving at about 1700 kph, less as you move towards the poles.
ANY significant slowing or speeding up of the rotation speed of the earth would cause HUGE problems.
Slowing the earth by even 1 kph would probably cause all the oceans to roll up the western coasts for MILES. Eastern coast lines would be dry for miles… Then it all sloshes back and forth a few times.
It wouldn’t take much though, (I’ll let someone else figure out just how much speed difference it would take) to have the oceans slosh up and pretty well wipe the continents clean.
I think you’re talking about an asteroid hit, at least.
On the scale of Nature, nothing man does even jiggles the scales. A single volcanic eruption is many times all the bombs dropped so far.
Do you mean “so far against Afghanistan” or “so far in all of human history”? Do you have a cite for the energy released in a volcano versus energy released in bombing?
If you’re comparing it to Afghanistan, I can probably believe that. But if you’re talking all of history here, I have a hard time believing that one volcano has more energy than 2 atomic weapons, all the bombs dropped (futilely) in WW II, Korea, Vietnam (Rolling Thunder, Linebacker I and II come to mind), etc. And that’s just considering U.S. campaigns. I guess we could also include atomic weapons tests.
The article is not available online on the Science News website, but there was a report in this publication in 1996 that the damming of rivers (primarily in the Northern hemisphere) over the last century has caused a redistribution of mass, resulting in a change in the Earth’s rotational inertia–enough to produce a measureable change in the rotation of the Earth. The effect is to make the day slightly shorter than if the damming had not taken place.
Here’s a citation:
“Reservoirs speed up Earth’s spin” (SN: 2/17/96, p. 108) says the impoundment of 10 trillion tons of water in the Northern Hemisphere over 40 years has affected Earth’s rotation and spin axis.
Another thing: For a gigantic bomb to effect the rotation of the earth, it has to expend its force as kinetic energy in the appropriate direction. Much of the energy of something like an atomic bomb is released as heat, which won’t change the rotation of the earth at all. And what material is ejected is usually pretty much omnidirectional, so again, there is no net force on the rotation of the earth.
It’s relatively easy to figure out how much energy you’d need to slow down the earth by a fixed amount - just calculate the angular momentum of the earth before and after, and the energy required pops right out.
We don’t have any weapons that can come close to making a difference. As someone else said, even small volcanos release more energy than hundreds of atomic weapons.
What we do is even less than insignificant. The only way to change the angular momentum of the Earth at all is to launch something into space, or to get something from space. It’s the rotational version of Newton’s Third Law: If I put angular momentum into the Earth, I have to put equal and opposite angular momentum into something else. The only way to change the angular momentum of the whole system is to either change what’s in the system, or interact with something outside of it. If we blew the entire country of Afganistan sky-high, we might briefly change the angular momentum of the rest of the Earth (by a miniscule amount), but it would be changed right back when all the pieces land.
Granted the nuclear bombs dropped in WW II were in the low kiloton range, so we probably have not released, in total, the same amount of energy as that in the Mount St. Helens eruption. But was MSH a big or small volcanic eruption on the scale of all volcanoes?
However, the effect of man had he dropped these high-yield bombs, would certainly have been significant on the scale of nature, not the miniscule effect alluded to previously.
Hurricanes release millions of times the energy of the Hiroshima bombs every second. Forget where I heard that, but I’ll look into it.
But anyway, explosions exert forces in all directions, so they balance out. Te real question is, what would happen if you lined up every single jet engine on one line of longitude and fired them simultaneously? There’s ALOT of engines…but the earth DOES weigh alot too. Iunno… that’s the stuff I think about.
Ski: Mount St. Helens was a fairly minor volcanic eruption, as volcanic eruptions go. According to this page MSH was a “large volcanic eruption” rather than a “small volcanic eruption”–but it wasn’t a “major volcanic eruption”. Major eruptions are “tens to hundreds of times larger” than MSH. Krakatoa in 1883 is probably the most famous major volcanic eruption. This page estimates Kratatoa had an energy equivalent of 5,000 megatons, which is equivalent to a full-scale nuclear war right there*. Krakatoa is far from the largest volcanic eruption we know of, either. According to this page, in terms of the volume of material ejected, the Yellowstone volcano of about 600,000 years ago was tens or hundreds of times larger than Krakatoa.
*That is, in terms of total energy released. Since all of that energy was released in one relatively small area, what you got was a major amount of overkill as far as what used to be the island of Krakatoa, heavy damage to surrounding areas in the Indonesian archipelago due to tsumanis, and really pretty sunsets all over the planet. The earlier Tambora explosion caused global climatic effects–“the year without a summer”. But these really big eruptions still aren’t as destructive as a full-scale nuclear war would be to human civilization, because most of the energy is expended pulverizing some particular mountain to dust, rather than being spread across the landscape of the Northern Hemisphere’s major cities or military installations. (There’s also no radioactive fallout from volcanoes, of course.) For this reason–that above a certain size, you’re just converting the target into smaller dust particles, with little practical effect–most modern strategic nuclear warheads have yields of a few hundred kilotons, not the behemoth 15 or 50 megaton bombs which the USA and USSR test-fired during the early days of Cold War weapons testing.
It would not have even the slightest effect. None, zippo, not even in theory.
A jet engine running on the ground would have precisely the same affect as a group of people playing tug of war. No net gain at all as far as the planet is concerned.
You think, you get all that thrust the jet transferred to the ground… the problem is, exactly the same amount is require slowing all those air particles back down. It just happens over a more dispersed area.
It doesn’t look like tug of war, because you don’t SEE the opponent on the other end of the rope. But it is there just the same, it is the whole atmosphere, and Earth’s surface.