Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why does mass distort space?

  1. Apr 30, 2014 #1
    I understand that the distortion of space is what gives rise to the force of gravity and the Earth is basically stuck in the suns distortion but why does mass cause this distortion. Is it just a property of space that is fundamental or can there be a reason why it causes the distortion and, with more technology and advancements, could be counteracted?

    Also if gravity is a property of all mass is it possible that gravity is a friction that keeps mass from ever achieving the speed of light?
  2. jcsd
  3. Apr 30, 2014 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    You should not try to "extrapolate" an idea when that idea isn't well-understood in the first place. Proposing "gravity is a friction" falls under that description.

    I think you haven't fully understood General Relativity. It isn't a "distortion of space", but rather a distortion of space-time. So I would recommend a simple introduction to General Relativity for you to read (assuming that you already know about Special Relativity and the connection between space and time):

    http://www.physics.fsu.edu/courses/spring98/ast3033/relativity/generalrelativity.htm [Broken]

    Last edited by a moderator: May 6, 2017
  4. Apr 30, 2014 #3


    User Avatar
    Science Advisor

    what do you mean by "mass"?
  5. Apr 30, 2014 #4
    I did understand that it was space-time but I was wondering why mass effects it.

    I will read that though because it will probably help me understand it better at least the concept. I'm good with my calculus but I need to work my way through more of the physics before GR.
    Last edited: Apr 30, 2014
  6. Apr 30, 2014 #5
    Massive objects in space. Special Relativity says matter with mass can't go the speed of light. I kind of want to know why rather than making a right triangle with E=mc^2+pc. I have read that the higgs field is what keeps particles with mass from going the speed of light but why?
  7. Apr 30, 2014 #6
    Particles are necessarily coupled to the metric.
  8. Apr 30, 2014 #7


    Staff: Mentor

    Mass curves spacetime because it has energy and the stress-energy tensor is the source of spacetime curvature according to the Einstein field equation.

    As to why the EFE is correct, like all fundamental physical principles that is simply postulated, and it is justified because it seems to fit the data well.
  9. Apr 30, 2014 #8
    Thank you all, you have been a huge help!!
  10. Apr 30, 2014 #9
    In my GR class, the Einstein field equation was motivated as some sort of 4-dimensional, relativistic analogue to the Poisson equation for Newtonian-gravity, which is equivalent to Newton's inverse square law.

    So, no we don't know why mass curves space-time--it just does, but there were some initial observations, like special relativity, time dilation in a gravitational field, the equivalence principle, and a bunch of tensor calculus/differential geometry that helped Einstein (with some help from his mathematician friend, Marcel Grossmann) to figure that out that it does. Newton's law of gravity also needed to be fixed, just as the rest of Newton's laws needed to be fixed, due to special relativity.

    Incidentally, if you want to get a better feel for why space-time curvature explains gravity, here's a good to read:

  11. Apr 30, 2014 #10
    That's all neat I have much to learn until I can do the math and the physics but I'll bookmark the page. I read a little about the stress energy tensor to get better understanding but I am failing to understand where the energy comes from, is it just the energy of the mass and momentum that bends space-time?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook