Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: kyscreth on 02/10/2009 08:25:35

Title: What could cause the earth to lose its gravity?
Post by: kyscreth on 02/10/2009 08:25:35: Does anyone have any ideas how the earth or any other planet could lose its gravity?? either over a long or short amount of time..
any ideas would be appreciated, cheers.
Title: What could cause the earth to lose its gravity?
Post by: Mr. Scientist on 02/10/2009 08:29:02: Only one solution. A loss of gravity would mean a loss of mass.
Title: What could cause the earth to lose its gravity?
Post by: syhprum on 02/10/2009 15:39:28: When LHC gets going and drops a dreaded blackhole into the centre of the Earth causing it to collapse almost instantly into a 50 millmeter radius ball we who are living 6400 Km from the the centre at present will notice an immediate loss of gravity.
This will not last long as we drop towards the centre very gently at first it will rapidly increase and reach a quite uncomfortable level!.
Title: What could cause the earth to lose its gravity?
Post by: neilep on 02/10/2009 18:14:55: Will it help if I am upon an airomobile when this happens ?
Title: What could cause the earth to lose its gravity?
Post by: LeeE on 02/10/2009 19:31:40: Quote from: syhprum on 02/10/2009 15:39:28
When LHC gets going and drops a dreaded blackhole into the centre of the Earth causing it to collapse almost instantly into a 50 millmeter radius ball we who are living 6400 Km from the the centre at present will notice an immediate loss of gravity.
This will not last long as we drop towards the centre very gently at first it will rapidly increase and reach a quite uncomfortable level!.

The Schwarzchild radius for the Earth is a little under 9mm, iirc. Were the Earth to be instantly transformed into such a black hole there would be no change in the 'strength' of gravity at the original radius of the Earth i.e. where it's surface was. There would be no loss of gravity and anything left there would just start accelerating towards the center at 1G.

If a micro black hole were to fall into the Earth from its surface, the Earth would not collapse almost instantly; the fastest that the surface could collapse would still be 1G and in fact it's likely that the Earth would take quite some time to collapse, probably over a period of days to months. The micro-BH would oscillate back and forth through the Earth, initially with relatively little slowing, but getting slower with each pass and eventually settling at the center. As matter fell into the micro-BH energy would be released by the in-falling matter, effectively producing a back-pressure that would slow the rate of further in-fall. Although the collapse would start slowly, it would speed up over time and total effective collapse would be inevitable in the end.
Title: What could cause the earth to lose its gravity?
Post by: syhprum on 02/10/2009 20:59:00: I did not expect my post to be taken too seriously but I am pleased to see any serious analyses of the scenario.
Title: What could cause the earth to lose its gravity?
Post by: RD on 02/10/2009 21:08:45: What about the Lagrange point L1 ? where gravity is cancelled out.
http://en.wikipedia.org/wiki/Lagrangian_point
Title: What could cause the earth to lose its gravity?
Post by: syhprum on 30/11/2009 14:46:25: If mathematicians found serious errors in Einstein and Newtons calculations
Title: What could cause the earth to lose its gravity?
Post by: yor_on on 13/12/2009 00:04:26: Gravity is related to mass and acceleration. As soon as you stop accelerating you become 'weightless' if in space. So to get to a state without gravity I think you would need to be as far away from any mass and acceleration as possible.
Title: What could cause the earth to lose its gravity?
Post by: Mr. Scientist on 13/12/2009 00:38:40: Quote from: kyscreth on 02/10/2009 08:25:35
Does anyone have any ideas how the earth or any other planet could lose its gravity?? either over a long or short amount of time..
any ideas would be appreciated, cheers.

Not without the absence of the matter earth is comprised of. :)
Title: What could cause the earth to lose its gravity?
Post by: Mr. Scientist on 13/12/2009 00:39:25: Or a gradual but long gravitational radiation.
Title: What could cause the earth to lose its gravity?
Post by: Mr. Scientist on 13/12/2009 00:40:20: Quote from: yor_on on 13/12/2009 00:04:26
Gravity is related to mass and acceleration. As soon as you stop accelerating you become 'weightless' if in space. So to get to a state without gravity I think you would need to be as far away from any mass and acceleration as possible.

Listen to this one - he is also true.
Title: What could cause the earth to lose its gravity?
Post by: yor_on on 25/12/2009 07:13:51: Nah not really, but thanks all the same Mr S. Thinking of it you need to get outside SpaceTime to get out of gravitational influences. The universe binds together by gravity so?
Title: What could cause the earth to lose its gravity?
Post by: Pmb on 27/12/2009 03:14:42: Quote from: syhprum on 02/10/2009 15:39:28
When LHC gets going and drops a dreaded blackhole into the centre of the Earth causing it to collapse almost instantly into a 50 millmeter radius ball we who are living 6400 Km from the the centre at present will notice an immediate loss of gravity.
This will not last long as we drop towards the centre very gently at first it will rapidly increase and reach a quite uncomfortable level!.
That is not true. We'd never know the difference if our distance from the center of the Earth remained the same.
Title: What could cause the earth to lose its gravity?
Post by: syhprum on 27/12/2009 10:08:54: LeeE has published a more detailed account of what will happen.
Title: What could cause the earth to lose its gravity?
Post by: questioner on 31/12/2009 00:52:15: Gravity gets weaker as we travel away from the earth so it must be stronger as we get closer to the centre. The density in the centre of the earth must be immense. If you could remove the core of the planet wouldn't it collapse into dust.
Title: What could cause the earth to lose its gravity?
Post by: Geezer on 31/12/2009 06:44:15: Quote from: questioner on 31/12/2009 00:52:15
Gravity gets weaker as we travel away from the earth so it must be stronger as we get closer to the centre. The density in the centre of the earth must be immense. If you could remove the core of the planet wouldn't it collapse into dust.

Er well, no. If you were able to survive at the centre of the Earth, the Earth would exert no gravitational force on you at all. The mass of the Earth would be equally distributed around you in three dimensions, so the gravitational forces from the Earth's mass would sum to zero.