From a Newtonian perspective Gravity acts instantly. If the Earth needed to wait 8 minutes for the suns gravity to hold it in orbit we would spin off out of the galaxy. A physician named Laplace postulated this in 1825.
I would imagine that the best place to measure the propagation of gravity would be in an event such as a supernova. There are tremendous energy to mass conversions that would effect the gravity between the supernova and an observer on Earth. If Gravity propagates instantly you would get a different event observed on Earth than if gravity is limited by the speed of light and a "gravity wave" traveling at the speed of light is unable to overtake and slow down or blue shift the radiation traveling towards Earth from the supernova. When you ask what is the speed of gravity is from this perspective you are really asking how accurate is your stopwatch.
Physics according to Einstein uses the speed of light as a limit to gravity propagation non locally. The relativistic calculations work for many applications, but they are not very easy to use for doing things like calculating satellite orbits.
I guess it all depends on what you want to do with a calculation. When I go to a restaurant and need to calculate a tip it is easier for me to move the decimal point in my mind than try to do it out on paper. I have friends that make their children do it out longhand on paper for the practice.
Slashdot Mirror
1. It's hard to find any information about submarine communications on the internet other than disinfo.
2. I have come to the conclusion that for the most part submarines have a hollow center section (I don't think this fact violates anybody's NDA?)
From a Newtonian perspective Gravity acts instantly. If the Earth needed to wait 8 minutes for the suns gravity to hold it in orbit we would spin off out of the galaxy. A physician named Laplace postulated this in 1825.
I would imagine that the best place to measure the propagation of gravity would be in an event such as a supernova. There are tremendous energy to mass conversions that would effect the gravity between the supernova and an observer on Earth. If Gravity propagates instantly you would get a different event observed on Earth than if gravity is limited by the speed of light and a "gravity wave" traveling at the speed of light is unable to overtake and slow down or blue shift the radiation traveling towards Earth from the supernova. When you ask what is the speed of gravity is from this perspective you are really asking how accurate is your stopwatch.
Physics according to Einstein uses the speed of light as a limit to gravity propagation non locally. The relativistic calculations work for many applications, but they are not very easy to use for doing things like calculating satellite orbits.
I guess it all depends on what you want to do with a calculation. When I go to a restaurant and need to calculate a tip it is easier for me to move the decimal point in my mind than try to do it out on paper. I have friends that make their children do it out longhand on paper for the practice.
What is the gravity there on Venus compared to Earth?