The Nature of Gravity
The Mice - Intersecting Galaxies
Gravity has been one of the bigger mysteries to man. Isaac Newton’s attempts to understand it spawned a new branch of mathematics and a better understanding of mechanics. Einstein explored it in his unified field theory and warned others to stay away from such a tough problem.
One concept that is interesting is “What is the speed of gravity?”. In a thought experiment, if something very massive suddenly appeared in the vicinity of Pluto’s orbit, would it take four hours for the Sun’s gravity to have an effect on its motion (four hours is the amount of time light takes to get to Pluto from the Sun) or would it be near instantaneous? The Sun’s field is already “there” but the Sun is also affected by the gravity of the planet – it is a two-way interaction – which is the basis of some of the string theories that try to explain how these fields are “communicated”.
Of course this thought experiment is impossible in the real world but could the speed of gravity be faster than light? And how does gravity work over vast interstellar distances? It obviously has an effect as observed in intersecting galaxies in the Hubble picture above. Maybe re-examining the role of gravity in the cosmos could better explain some of the strange effects, such as the expanding universe, that have been attributed to “dark matter” or “dark energy”.
Some of the ideas on the speed of gravity are explored in this paper:
2 thoughts on “The Nature of Gravity”
January 31, 2007 at 12:04 pm
Check out “Star Trek: Generations” — A mad scientist is attempting to change the direction of a mysterious ribbon that transports people into another dimension. He has figured out a way to destroy stars, thus by affecting the gravitational path of the ribbon. There are problems with this story-line, if gravity travels at the speed of light. The second star destroyed would have to be several light years away, and the gravitational adjustment would take years to reach the ribbon’s relative position to that of the next star that is destroyed.
January 31, 2007 at 12:44 pm
Interesting storyline. He may have figured a way to “warp” gravity in line with the series taking liberty with the speed limit.
There was some activity on this a few years ago when they did an experiment when Jupiter moved in front of a quasar. The scientists claimed that the experiment proved that gravity does travel at the speed of light, but there were quite a few dissenters that thought the conclusions of the experiment were wrong.