Quantum Physics Question

[mike.mckenzie]

If the sun was turned off instantaneously, would the earth fly off into space immediately or would it take some time for the effect to kick in, a la the sun's light reaching us about 8 minutes after it leaves the sun????

What is it??? I can't sleep.

[Rheghead]

What do you mean by turned off? If it just stopped shining then things would just stay the same but would be a lot darker. As for if the Sun just disappeared then the Earth would carry on in its trajectory until the light reached it then it will go off at a tangent some ~8 minutes later. I think gravity waves travel at light speed as well. The good Doctor would be a better person to ask though.

[scotsboy]

I dont think things would stay the same Rheghead as we need the Suns energy for heating, photosynthesis etc........it would be the end......may take a week or two.........but as you say it would depend how the lights went out.

[Joefitz]

http://earthguide.ucsd.edu/sun/intro4.html

1) It cannot "Go out"

2) Worst case scenario, self destruction due to gravitational flux

3) Don't know if anyone has tried to calculate what would happen if it suddenly "went out", but it would fuel a lot of argument

4) Exploding stars have been noted, but what happened to the capture planets is not known.

[XP]

According to Einstein's General Relativity gravity is due to curvature of space-time. It is a geometrical effect rather than a force that propagates at a finite speed. Therefore, if the Sun's gravity was "turned off" then, ignoring gravitational attraction of other objects, the Earth would immediately begin to travel in a straight line tangential to its current orbit.

[DrSzin]

According to Einstein's General Relativity gravity is due to curvature of space-time. It is a geometrical effect rather than a force that propagates at a finite speed. Therefore, if the Sun's gravity was "turned off" then, ignoring gravitational attraction of other objects, the Earth would immediately begin to travel in a straight line tangential to its current orbit.

Nope. The effect of the sudden disappearance of the sun (assuming this could happen lol) would propagate outwards at the speed of light, so Rheghead's simple argument is correct.

Another way of saying this is that the local curvature of space is indeed determined by the solution of Einstein's equations, but the change in curvature would propagate outwards at the speed of light.

Anyway, this has nothing to do with Quantum Physics, it's classical field theory.

[Saveman]

Does light travel in waves or particles?

Do gravity waves exist?

[fred]

Does light travel in waves or particles?

Do gravity waves exist?

The answer to your first question is yes.

As for gravity waves personally I think gravity is just like centrifugal force, the nature of a moving object to try and travel in a straight line.

If you reduce the four dimensional universe to three dimensions and think of it as a balloon which is rotating and then think of a spherical planet as a disk which is inside the balloon then centrifugal force would cause the disk to press outwards and stretch the rubber of the balloon. Obviously another disk shaped object which entered the area of stretching would be forced towards the first disk shaped object. If the second object were travelling fast enough and not aimed directly at the first object then instead it would travel round and round the depression caused by the first object like a motorcycle on a wall of death, it would be in orbit.

I may have over simplified what actually happens somewhat for the sake of clarity but it is my belief that this is the general principle.

[clash67]

According to Einstein's General Relativity gravity is due to curvature of space-time. It is a geometrical effect rather than a force that propagates at a finite speed. Therefore, if the Sun's gravity was "turned off" then, ignoring gravitational attraction of other objects, the Earth would immediately begin to travel in a straight line tangential to its current orbit.

XP...you just blew my mind (expressed in a kramer type fashion)! LOL

[theone]

If the sun just stopped burning and emmitting heat and light then after the 8 minutes or so we'd be pretty cold but surely wouldn't have moved anywhere because the earth is held in orbit by the suns gravity, which wouldn't disapper unless you removed the suns mass?