speed of gravity and light?

Question

so... it's commonly accepted that NOTHING is faster than the speed of light (aside from theoretical stuff such as tachyons and spaceships). well what about the force of gravity?

if the sun all of a sudden just disappears, would earth be orbiting nothing until the force of gravity ends and it'd just fly tangent?

oh and also... just wondering. if luke skywalker fires a laser from his blaster on his MOVING speeder, would the laser (obviously flying at the speed of light) go any faster?? because from the added speed of the speeder?

Answer 1

Gravity is widely accepted to move at the speed of light. If the sun disappeared (kidnapped by the Emperor..) it would take about 8 minutes before earth would swing away into space in a straight line.

If Luke fired his blaster towards Darth Vader while he´s riding his speeder at a quarter at the speed of light, Darth would still be able the measure the speed of the laser blast to be traveling at light speed. Not light speed + a quarter. Even if Darth was in his Tie Fighter flying toward Luke at a quarter of the speed of light, fired HIS blasters, Luke would be able to measure the speed of the blast to be traveling at light speed. Not light speed + a quarter + a quarter. The speed of light is a constant. The same for ALL observers. Weird huh? This is because of time dilation. When someone is moving really fast time slows down. So to the observer time will appear to be ticking as normal but since time is really slowed the blast can move the same distance at the same time as if did when the observer was standing still (and time was ticking at its normal pace). Which is why both Luke and Darth see the blasts traveling at the speed of light.

Answer 2

Try reading "The Elegant Universe" by Brian Greene. It covers these questions nicely.

Basically gravity "moves" at the speed of light. So if the Sun disappears we would not know it for 8.5 minutes. To get out of a gravity well you just have to move away from it with more force than it is pulling you back with. The force depends on the mass of the object. Oh, by the way, gravity never goes away. It gets weaker the farther you move from an object but it is always there.

As to the laser question: If Luke fires a laser from a speeder bike the laser does not move faster, now this part is important, in that reference frame. Luke will always see it as moving at the speed of light.

Answer 3

If the Sun were to just disappear then the Earth would fly off in the direction it was moving after about 8 minutes. Gravity works at the same speed as light.

No, the laser would not move any faster. The speed of light (3 x10^8 m/s) is the cosmic speed limit.

Answer 4

Gravity is not an object, a force, a wave, or a form of energy. Gravity does not consume energy and it does not do work. Okay? Have we all got that yet?

Gravity does not move, and it does not have a characteristic velocity, as light does. Instead, gravity is a property of the space-time continuum. It is absolutely ubiquitous, and conforms to universally uniform principles.

If the sun could somehow be instantaneously removed from reality (don't worry, by the way; that can't happen.), then earth would instanly be released from its gravitational attraction, and we would not know why for a little more than eight minutes.

But all the stuff about gravity waves and the "speed of gravity" is bad science.

Answer 5

The gravity (acceleration) on earth is 9.81 m/s^2. However on other planets and moons it varies depending on the mass of the planet. They say that gravity is caused by an objects mass warping space and time. The analogy I saw was a metal ball circling arond a very large funnel. Which didnt help me visualize space and time very much to be honest but W/E.

If the sun disappeared we would sling off into outer space. Because our current velocity wouldn't change but we would no longer be attracted towards the sun. If we got close enough to one of the larger planets such as Jupiter we may just begin to orbit the respective planet.

Answer 6

According to theory, gravity moves at the speed of light. This was proven in an experiment summarized at the following site: http://www.space.com/scienceastronomy/gravity_speed_030107.html

Therefore, since we are approx. 8 light minutes from the sun, if it disappeared suddenly then we would not feel the effect for 8 minutes. As you suggest, our orbit would just fly off once the effect of the sun's gravity disappeared.

As to Luke Skywalker firing a laser blast, if his speedster is going faster than the speed of light, he would outrun his own laser blast since light can not go faster than the speed of light. He'd end up probably blowing up his own speedster!

Answer 7

Don't know about the Luke thing... but, if the sun were suddenly just "gone", we would know *nothing* about it until 8 1/3 minutes later. The gravity well that earth is trapped in would retain it's shape for the exact amount of time it would take for space to adapt to the sudden absense of mass, which is assumed to happen at the speed of light.

Answer 8

No such thing as the speed of gravity. It's acceleration due to gravity (about 9.8 meters/second/second). If the sun disappeared, the Earth would most likely gravitate towards the next largest object in the solar system, Jupiter. It's a messy calculation though, with all other planets exerting their force.

Answer 9

The gravity bends gentle. This has been examined and examined. This proves one ingredient. pictures do have mass. whilst they have mass they ought to be affected whilst gentle tries to flee from a gravitational field. the shortcoming of understanding of the gentle leads to different arguable assertion. i do no longer understand is there any measurements of velocity of sunshine under 0 gravity in vacuum. there's a pink shift phenomena of sunshine properly documented and used to degree the fee of stars, galaxies and so on. If the theory of persevering with gentle velocity is authentic then one rationalization would desire to be the frequency shifts downwards in direction of pink. this could decrease the capability of the gentle. A stress reduces the capability. The capability help could be decreased velocity or pink shift. that's the only attainable rationalization attainable at the instant. I strongly propose study somewhat analyze papers in this undertaking.

Answer 10

In that the force of gravity performs work, it must have an energy source. Stephen Hawking in "A Brief History of Time," page 92, paragraph 3, states; "Like light, gravitational waves carry energy away from the objects that emit them". What you are seeking is found in the physics trilogy which is: E = mc2, m = E/c2, and c2 = E/m. The first two equations describe our universe as being created of the "c2" value, or that of physical time, or that of electromagnetic energy. The third equation is that of a field of time, or that of a field of gravity. These three equations state that as the value of "c" forms our physical universe, the value of "c" itself is separate from the first two (c^2). The force of gravity is one form of energy unlike the electromagnetic energy forming mass, and is a form of energy itself that constructs electromagnetic energy. This form of existence is an influence of all forms of energy and mass, due to its velocity of "c" as it passes through them forming a condition like a negative vector into which all forms of energy seek to attain. It is similiar to a large whirlpool forming in a lake that draws all else to itself. Each individual, in its own small manner, does the same to all mass and energy.

Lastly, no matter the mass speed and the added energy (speed) by which it increases, it only reaches the speed of light and then there is no more mass, thus no more acceleration.