5 ms·

There is not much difference. The relativistic factor is 1.030107, that is a ~3% change. EDIT: My amateur physics say that the gravitational well adds 9.7% to

by deletes 13y ago

There is not much difference. The relativistic factor is 1.030107, that is a ~3% change. EDIT: My amateur physics say that the gravitational well adds 9.7% to that. I tried the same calculation for earth and it gave a sensible result: a change of 6.95 * 10^-10. Here is an answer from physics exchange which gets the same result: http://physics.stackexchange.com/questions/10089/gravitational-time-dilation-at-the-earths-center http://physics.stackexchange.com/questions/10089/gravitation...

Zikes 13y ago
That's about 11 days per year, or 43 minutes per day.
InclinedPlane 13y ago
Keep in mind that differences in gravity will also affect time dilation.
- gus_massa 13y ago
  And this correction goes in the other way.
  - deletes 13y ago
    No, time in a gravitational well runs more slowly relative to someone outside, just as your experience time slower if you are traveling very fast.
    - gus_massa 13y ago
      You are right. I was confused because the satellites in orbit need a different speed at different height, and in that case the when the special relativity effect increase the general relativity effect decrees. http://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System#Relativity http://en.wikipedia.org/wiki/Error_analysis_for_the_Global_P...
    - machrider 13y ago
      I think the point was that time in the center of the star is more affected by gravity than at the surface. Whereas someone on the surface (if that were possible) would experience greater time dilation relative to the center due to his high relative velocity. So for those two points (surface vs center), the two time dilation effects are working opposite each other. Edit: I may have been reading too much into it. The effects you see will depend on which positions you're comparing, and people in this thread haven't really specified.
      - deletes 13y ago
        I think you mixed up some things. There is no gravity or time dilation in the center of a massive spherical object.
        nealabq 13y ago
        If you're in a small empty room in the middle of a neutron star, you will be floating weightless, but you're still at the bottom of a gravity well. Since it's the well, not the acceleration that affects time, time will tick slower for you. (Don't try this at home.) (And if you do, don't touch the walls.)
        deletes 13y ago
        Spacetime in the center of a perfect spherical object is the same as a point in empty space, you can't tell them apart. Of course that only counts for the exact point in the center. So the time will not tick slower there as to someone far from any objects.
        ubercow13 13y ago
        What? The lowest potential in a uniform sphere is at the centre not the surface (http://en.wikipedia.org/wiki/File:GravityPotential.jpg http://en.wikipedia.org/wiki/File:GravityPotential.jpg). Also graviational time dilation depends on the potential not the force (curvature) so it is irrelevant if the point at the centre is shifted in spacetime
JonnieCache 13y ago
12.7% over 16km sounds like quite a lot to me. Especially since we're talking about time.
BaryonBundle 13y ago
The quoted example admits that it ignores strong fields and non-relativistic matter, which we have already established to be dealing with. The angular momentum of an element of volume in the neutron star likely contains enough kinetic energy to affect the Einstein field equations in a significant way. General relativity can't be ignored, but the Newtonian approximations has this habit of being nearly right more often than not. I know that for rotating black holes the Kerr solution to the Einstein equations offers the best way to test these metric-based questions but I'm not sure if that's what you'd use for a Neutron Star.

by deletes 13y ago

Zikes 13y ago

That's about 11 days per year, or 43 minutes per day.

InclinedPlane 13y ago

Keep in mind that differences in gravity will also affect time dilation.

gus_massa 13y ago
And this correction goes in the other way.
- deletes 13y ago
  No, time in a gravitational well runs more slowly relative to someone outside, just as your experience time slower if you are traveling very fast.
  - gus_massa 13y ago
    You are right. I was confused because the satellites in orbit need a different speed at different height, and in that case the when the special relativity effect increase the general relativity effect decrees. http://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System#Relativity http://en.wikipedia.org/wiki/Error_analysis_for_the_Global_P...
  - machrider 13y ago
    I think the point was that time in the center of the star is more affected by gravity than at the surface. Whereas someone on the surface (if that were possible) would experience greater time dilation relative to the center due to his high relative velocity. So for those two points (surface vs center), the two time dilation effects are working opposite each other. Edit: I may have been reading too much into it. The effects you see will depend on which positions you're comparing, and people in this thread haven't really specified.
    - deletes 13y ago
      I think you mixed up some things. There is no gravity or time dilation in the center of a massive spherical object.
      - nealabq 13y ago
        If you're in a small empty room in the middle of a neutron star, you will be floating weightless, but you're still at the bottom of a gravity well. Since it's the well, not the acceleration that affects time, time will tick slower for you. (Don't try this at home.) (And if you do, don't touch the walls.)
        deletes 13y ago
        Spacetime in the center of a perfect spherical object is the same as a point in empty space, you can't tell them apart. Of course that only counts for the exact point in the center. So the time will not tick slower there as to someone far from any objects.
        ubercow13 13y ago
        What? The lowest potential in a uniform sphere is at the centre not the surface (http://en.wikipedia.org/wiki/File:GravityPotential.jpg http://en.wikipedia.org/wiki/File:GravityPotential.jpg). Also graviational time dilation depends on the potential not the force (curvature) so it is irrelevant if the point at the centre is shifted in spacetime

JonnieCache 13y ago

12.7% over 16km sounds like quite a lot to me. Especially since we're talking about time.

BaryonBundle 13y ago

The quoted example admits that it ignores strong fields and non-relativistic matter, which we have already established to be dealing with. The angular momentum of an element of volume in the neutron star likely contains enough kinetic energy to affect the Einstein field equations in a significant way. General relativity can't be ignored, but the Newtonian approximations has this habit of being nearly right more often than not. I know that for rotating black holes the Kerr solution to the Einstein equations offers the best way to test these metric-based questions but I'm not sure if that's what you'd use for a Neutron Star.