If the sun were to suddenly vanish, how long would it take for the Earth to stop feeling the sun's graviational pull? Instanteneous? Speed of Light? Somewhere in between?
2006-06-19 20:20:06 · 14 answers · asked by sgissin 2 in Science & Mathematics ➔ Physics
I believe it would be instantaneous, but it's a fascinating question. Perhaps the speed of light, because there are those who argue that gravity is another form of energy generally, and the whole "unified field" thing that I confess I do not understand at all.
I suppose part of the question is how the sun could "suddenly vanish" in the first place. Would it in fact vanish instantaneously, or at the speed of light? Even if it fell into a black hole, that would be an event, and events have a place in space/time. That we would not know it had vanished until the light stopped coming to us some minute or two later (speed of light for 93 million miles), because of the light, then would gravity be following with that light? The light is, after all, energy and therefore -- says Einstein -- matter, and that's what responds to gravity . . .
Geeze, you make my head hurt with these puzzles. I hope some really heavy-duty physicist takes a shot at this question!
2006-06-19 20:32:33 · answer #1 · answered by auntb93again 7 · 0⤊ 3⤋
On earth the speed of gravity is 9.8 meters per second squared. I do not know if the force of gravity between the Sun and the Earth is the same though, probably not.
Newton described gravitational attraction in his Law of Universal Gravitation, which says that the force of gravity between two bodies is directly proportional to the product of the two masses and inversely proportional to the product of the square of the distance between them. Essentially, the pull between two objects directly relates to how massive each object is.
The velocity of a body changes direction when a force acting on the body is perpendicular to the velocity. As the trajectory or path bends, the applied force is pointing toward the center of each segment of the curved path. Such force is called centripetal force. The Earth stays in its orbit due to the centripetal force exerted on the Earth by the Sun.
To answer your question, I would say yes...if the sun were to suddenly vanish the effects of gravity would be almost instantaneous, at least at the speed of light. The centripetal force that the Sun exerts on the earth would be nonexistent and the Earth would just free-fall.
Ex: Compute the Earth's centripetal acceleration toward the Sun. The time it takes to go around the Sun once is 365 days. The radius on average is R = 1.5x10**8 km.
The average orbital speed of the Earth is V = 2pR/365x24x60x60 s = 30 km/s
ac = V**2/R = 900 (km**2/s**2) / 1.5x10**8 km = 600x10**-8 km/s**2 = 6x10**-3 m/s**2 pointing to the Sun. The centripetal force between the Sun and the Earth is
Fc = ma = 6x10**24 kg x6x10**-3 m/s**2 = 36x10**21 N
2006-06-19 20:55:37 · answer #2 · answered by Anonymous · 0⤊ 0⤋
The gravitational effect to curve or warp space time propagates at the speed of light (in a vacuum). Therefore, if the Sun were to disappear/vanish, it would take approx 8 minutes for the effects to reach the earth. With the Sun there, we are only seeing it as it was approx 8 minutes ago. Einstein refuted Newton's belief that gravity's effects were instantaneous.
2006-06-19 21:21:34 · answer #3 · answered by quntmphys238 6 · 0⤊ 0⤋
If the sun were to vanish its gravitational pull would, theoretically, be at the speed of light.
Theoretically the time it takes for one object to feel the pull of another is the distance between them times the speed of light.
2006-06-19 20:32:35 · answer #4 · answered by Anonymous · 0⤊ 0⤋
gravity is proportional to the mass of an object. More mass = higher gravitational pull. If the sun vanished, which is unlikely, then the earth would instantaneously lose orbit and follow a straight path until another force acted upon it.
2006-06-19 20:24:47 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Speed of light. The sun leaves an indent in spacetime, and when the sun disappears, this "gravitational wave" fills up the dent at exactly the speed of light. Well, that's what Einstein said. Once it has been filled up, we no longer are effected by the sun's pull.
2006-06-20 05:18:06 · answer #6 · answered by picsnap 3 · 0⤊ 0⤋
Presuming that gravity travelled at the speed of light was one of the axioms that led Einstein to formulate the General Theory of Relativity. Experimental confirmation of this theory indicate that gravity does indeed propagate at the speed of light.
2006-06-19 21:04:23 · answer #7 · answered by Epidavros 4 · 0⤊ 0⤋
Because gravity can be viewed as a 'deformation' of space-time, it doesn't need to travel, and therefor has no speed. Its effect is instantaneous.
***Edit***
I made that up. I love physics, but I'm self-taught, and many here know way more than I. I was just trying to get an answer in quick to try to win a trip to space camp for some kids in my neighborhood. (blush)
We must assume that no information travels faster than the speed of light.
2006-06-19 20:24:07 · answer #8 · answered by LazlaHollyfeld 6 · 0⤊ 1⤋
General relativity predicts that gravity propogates at the speed of light.
2006-06-19 20:23:02 · answer #9 · answered by Anonymous · 1⤊ 0⤋
evry vector field travels with the speed of light
2006-06-19 20:28:52 · answer #10 · answered by Anonymous · 0⤊ 0⤋