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What is the speed of gravitational waves?

  1. Jan 29, 2012 #1
    I was wandering through the net when I came to know that the Newtonian gravitation suffers discrepancies at some regions of space.

    On further reading I came to know about gravitational waves. Fundamentally matter has mass and mass is responsible for gravity. Then it may be anything from small meteor to big galaxies. They all form their own gravitational waves in space time fabric.
    My question is

    What is the speed of such gravitational waves?

    If it is the speed of light, it means that if the Sun is moved from its original position suddenly, there will be a gradual wave of disorder moving outwards in our solar system.

    That means Earth will lose its orbit after 7.5 minutes?
    also Pluto will lose its orbit after 328 minutes???

    I do not understand this phenomena.
     
  2. jcsd
  3. Jan 29, 2012 #2
    You're right, it is the speed of light, although it is yet to be experimentally measured. You're also right that the planets will lose their orbit in order of distance from the Sun.
    Skip to 7:20 in this video for a visual explanation
    Hopefully someone else will give more information.
     
    Last edited by a moderator: Sep 25, 2014
  4. Jan 29, 2012 #3

    Bill_K

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    Science Advisor

    In general relativity you need to be careful in formulating such thought experiments as "what if the sun suddenly moved", because conservation of energy and momentum are central to the theory and the sun cannot suddenly move or disappear. Also a star simply moving along in a straight line does not produce a wave.

    An oscillating source such as a pair of stars orbiting about one another does cause gravitational waves, and they propagate outward at the speed of light.
     
  5. Jan 29, 2012 #4
    As I understand gravitational waves are simply space-time waves. Given that then what exactly is inflation if space can expand in a manner such that two objects would appear to be moving apart from one another faster than light?
     
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