Melting Antarctic ice is causing gravitational shifts
23 replies, posted
Source: [url]http://io9.com/weve-lost-so-much-antarctic-ice-its-causing-a-dip-in-ea-1639502535[/url]
[quote]
The GOCE satellite was launched in 2009 to undertake a detailed mapping of Earth's gravity, along with any fluctuations in strength. As researchers recently began analyzing the data they'd received, they noticed something curious: the variations in gravity they were seeing in the Antarctic were mirrored by the changes in ice as the collapse of the ice sheet there accelerated.
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That makes sense. Ice is less dense than water, so the shift is gonna fuck with the Earth's total density, and therefore the gravity.
[QUOTE=Sgt-NiallR;46121958]That makes sense. Ice is less dense than water, so the shift is gonna fuck with the Earth's total density, and therefore the gravity.[/QUOTE]
Gravity is due to mass not density
[QUOTE=Sgt-NiallR;46121958]That makes sense. Ice is less dense than water, so the shift is gonna fuck with the Earth's total density, and therefore the gravity.[/QUOTE]
It won't really fuck with the "total" density, just the local density.
[QUOTE=Yuskolov123;46122033]Gravity is due to mass not density[/QUOTE]
Yes, but local changes in density will make gravity stronger in some areas than others.
It's more of a thing that the mass can spread around the globe more evenly, rather than being concentrated in one spot due to being frozen in one denser block.
[QUOTE=JohnnyMo1;46122056]
Yes, but local changes in density will make gravity stronger in some areas than others.[/QUOTE]
Yeh I was just talking about the 'total' density
Better start working out those leg muscles then
This is similar to some dam built in china. The mass of water accumulated in the dam increased how long our days are. [sp]by 0.06 microseconds[/sp]
[QUOTE=mdeceiver79;46122142]This is similar to some dam built in china. The mass of water accumulated in the dam increased how long our days are. [sp]by 0.06 microseconds[/sp][/QUOTE]
How does that work?
[editline]1st October 2014[/editline]
In layman's terms, I'm no scientist.
Repercussions on this might be? Might the changes be so minimal that there are none?
[QUOTE=Emperor Scorpious II;46122148]How does that work?
[editline]1st October 2014[/editline]
In layman's terms, I'm no scientist.[/QUOTE]
The stronger the gravity, the slower time goes. (At least that's how I understand it)
The accumulation of water made gravity stronger in that area, so time was slower in that area.
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That's why GPS satellites need special clocks because time is ever so slightly faster out in space (we're talking 0.0000038 seconds faster per day for a GPS satellite). As an exaggerated example, imagine if you sent a signal at 9:00, it took exactly one minute to reach the satellite, but the satellite's clock is 9:02. That's the kind of fuckery that gravity does with spacetime.
[QUOTE=ScottyWired;46122160]The stronger the gravity, the slower time goes. (At least that's how I understand it)
The accumulation of water made gravity stronger in that area, so time was slower in that area.
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That's why GPS satellites need special clocks because time is ever so slightly faster out in space. Imagine if you sent a signal at 9:00, it took exactly one minute to reach the satellite, but the satellite receives it at 9:02. That's the kind of fuckery that gravity does with spacetime.[/QUOTE]
I think even 0.06 microseconds sounds a like a bit too big of a correction for just some water. Relativistic effects are tiny without big masses/speeds. I think the change of moment of inertia of the earth might dominate the relativistic effects.
[QUOTE=DrDevil;46122076]It's more of a thing that the mass can spread around the globe more evenly, rather than being concentrated in one spot due to being frozen in one denser block.[/QUOTE]
Ice is less dense than water
[QUOTE=JohnnyMo1;46122187]I think even 0.06 microseconds sounds a like a bit too big of a correction for just some water. Relativistic effects are tiny without big masses/speeds. I think the change of moment of inertia of the earth might dominate the relativistic effects.[/QUOTE]
Its 0.00000006 of a second how is that large.
Very sensationalist title on this one
[QUOTE=Emperor Scorpious II;46122148]How does that work?
[editline]1st October 2014[/editline]
In layman's terms, I'm no scientist.[/QUOTE]
Basically, if your spinning around on an object (eg: [URL="http://smilekiddo.files.wordpress.com/2013/08/zipline_merry-go-round.jpg"]a merry go round[/URL]) whillst its spinning and you pull yourself closer to the center, it spins faster. The further away you are, the slower it goes. Same principle for the earth, the water is further away so the earths rotation slows ever so slightly.
[QUOTE=Emperor Scorpious II;46122148]How does that work?
[editline]1st October 2014[/editline]
In layman's terms, I'm no scientist.[/QUOTE]
to do with the centre of mass of the earth. Like when you are on 1 of those spinny poles in kids playgrounds (this is how u get higher on a swing by moving ur centre of gravity). Move further out it rotates slightly slower, longer period of rotation = longer day
Ahh beaten to it
[QUOTE=FLIPPY;46122522]Its 0.00000006 of a second how is that large.[/QUOTE]
My electrodynamics professor was talking about a decay one time in class that has a mean lifetime of a picosecond (i.e. 0.000000000000001 seconds). "That's a pretty long time!" he said. And it is, compared to other decays. Helium-8 decays in 200 attoseconds, for example.
Point being "large" is relative (heh). I just did a calculation and it looks like the time change per day would be on the order of 1 picosecond from relativistic effects. Like I mentioned, the corrections from relativity are [I]tiny[/I] unless you're moving really fast or dealing with very high mass.
[QUOTE=JohnnyMo1;46122780]My electrodynamics professor was talking about a decay one time in class that has a mean lifetime of a picosecond (i.e. 0.000000000000001 seconds). "That's a pretty long time!" he said. And it is, compared to other decays. Helium-8 decays in 200 attoseconds, for example.
Point being "large" is relative (heh). I just did a calculation and it looks like the time change per day would be on the order of 1 picosecond from relativistic effects. Like I mentioned, the corrections from relativity are [I]tiny[/I] unless you're moving really fast or dealing with very high mass.[/QUOTE]
How would relativity play a role exactly? Reduced time dilation due to smaller angular velocity?
[QUOTE=Falubii;46123196]How would relativity play a role exactly? Reduced time dilation due to smaller angular velocity?[/QUOTE]
Gravitational time dilation caused by being near such a large body of water. Of course, this is assuming that all that mass simply [I]wasn't there[/I] in any way before so the actual correction is going to be much smaller. My approximation was basically two people far away from each other at the same gravitational potential and one of them is right at the surface of a sphere of water of the mass and volume of all the water behind the Three Gorges Dam. Already with that model the correction is minuscule. The real life situation is even worse.
I wonder how big the fluctuations were during the ice age.
dont skip leg day anymore
[QUOTE=slashsnemesis;46122239]Ice is less dense than water[/QUOTE]
Yeah, but ice can go above the water surface and on land, so if you look at a 2d-map from above, the density in areas with ice will be higher.
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