What would be the effect on humanity (our health, structures, aircraft, etc) if Earths gravity increased by 1 percent?
If the effects of a one percent increase would be negligible, what percentage of increase would start to cause problems for us?
One percent wouldn’t be much (you may weigh a pound or two more). I doubt there’d be much of a health effect. I’d have to run some calculations to figure out the effect on structures, etc. (I wonder what long-term affects there would be for the Earth-moon or Earth-sun system.)
Certainly, when you start gaining significant weight (50 pounds for say a 30% increase in gravity or 100 pounds for a 60% increase), that may start causing problems.
(note: just back-of-the-envelope calculations here)
Don’t test pilots start passing out at something like 4G’s? I’m not sure.
I agree. I think the only visible effect would be that the orbit of the moon would be slightly altered. Eventually you’d notice that the moon is going through the phases a bit faster than it used to.
As for structures, the more the gravity increases, the more susceptible it becomes to wind, earthquake, and other natural forces. But I think bridges won’t start falling down by themselves until you increase the gravity by around 100%.
IIRC you pass out at negative 3 or 4 G’s and 9-10 positive G’s. Negative G’s happen when flying straight and level and a plane pushes its nose down giveing you that tickling feeling ‘down there’. The effect of passing out in ths case is called a red-out as blood gets pushed into your head and (apparently) the world goes red before you passout.
Positive G’s give you your typical blackout condition (things fade to black as you pass out) and a human is much more resistant to this. If you ever watch fighter pilots that need to descend quickly you’ll notice them flipping their plane upside down and then pointing the nose to the ground. When they do it this way they experience positive G’s and as a result can manage much tighter flying.
Also, just a vague memory here, I believe a redout is harder to recover from than a blackout (takes longer to wake up again).
There is already nearly 1% variation in the strength of gravity at the surface of the earth. You have to take three things into consideration:
- the earth is not a sphere, so the poles are closer to the center of the earth than the equator is
- the earth is rotating, so centrifugal force (so-called) makes gravity seem less strong at the equator
- mountain peaks are farther from the center of the earth than areas at sea level.
By my estimate, gravity at the top of Mt Chimborazo in Equador should be about 0.75% less than at the north pole.
Because of altitude: -0.2%
Because of rotation: -0.35%
Because of oblateness: -0.2%
There are also local variations because the density of the earth’s crust is not uniform. What little information I have on the subject suggests these are pretty insignifigant compared to the three considerations discussed above.
Wouldn’t the earth’s gravity be increasing incrementally each year due to the weight of meteorites and other space debris? Or is this offset by the amount of terrestrial stuff we shoot into space? Just wondering…
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None of this is first-hand, but it depends on the individual’s resistance (heart to head distance, size of blood vessels) and what he’s doing. I’ve read the “G-suit” can give an added G of tolerance, and the “G-straining maneuver” (likened to straining on the toilet) can add 2-3 G’s of tolerance. Under those conditions, some people can tolerate 9-10 positive G’s, others can’t. A continuous 5-6 G’s is likely to make many people pass out if they aren’t fighting it.
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I don’t have exact numbers on-hand (I’ll see what I can find), but the mass of stuff we shoot off into space is insignificant compared to the daily accumulation of meteoroids. (IIRC, it’s a surprisingly huge in-flux of space dust, but even that is next-to-nothing compared to the mass of the Earth.)