Time Dilation in Gravitational Fields vs Acceleration on Earth

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Discussion Overview

The discussion revolves around the concept of time dilation in gravitational fields compared to acceleration, specifically questioning whether these effects are additive. Participants explore the nuances of gravitational time dilation, acceleration, and the implications of being in a gravitational field versus an accelerating frame of reference.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions if time dilation experienced on Earth is greater than that in a rocket accelerating at 9.8 m/s² due to the combined effects of gravitational field and acceleration.
  • Another participant asserts that there is no time dilation due to acceleration, emphasizing that gravitational time dilation is solely based on gravitational potential.
  • A participant challenges the idea of additive effects, asking if standing on Earth's surface while accelerating increases gravitational potential.
  • There is a discussion about whether resisting free fall contributes to gravitational potential and how this relates to time dilation.
  • Clarifications are made regarding the distinction between pseudo gravitational fields in accelerating frames and true gravitational fields.
  • Questions arise about whether the discussion pertains to proper acceleration or coordinate acceleration in relation to time dilation.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between acceleration and gravitational time dilation, with no consensus reached on whether these effects are additive or how they interact.

Contextual Notes

Participants reference concepts of gravitational potential and time dilation without resolving the complexities of how these concepts interact in different frames of reference.

mcgnms
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TL;DR
Is the time dilation of being in a gravitational field additive to acceleration since geodesics also experience time dilation?
If I'm standing on Earth, is my time dilation actually greater than if I was in a rocket accelerating at 9.8m/s^2 in deep space due to me being in a gravitational field on top of the acceleration? Geodesics experience time dilation in gravitational fields, so it seems like there is an additive effect, right? I'm trying to eliminate special relativity and kinetic time dilation out of this equation, purely looking at three components here:

1) Time dilation just by being in a gravitational field
2) Time dilation from acceleration
3) Time dilation from resisting free fall in a gravitational field

Is #3 some combination of #1 and #2?
 
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There is no time dilation due to acceleration, neither gravitational nor any other type.

Gravitational time dilation is due to gravitational potential, and that is the same whether it is gravitational potential from a real gravitational field or the pseudo “gravitational” potential from an accelerating reference frame.
 
Dale said:
There is no time dilation due to acceleration, neither gravitational nor any other type.

Gravitational time dilation is due to gravitational potential, and that is the same whether it is gravitational potential from a real gravitational field or the pseudo “gravitational” potential from an accelerating reference frame.
Right, but my question still stands. Are these effects additive? When you stand on Earth's surface, whether or not you're in free fall or standing on the surface...you have gravitational potential. Now on top of that, since you're standing (and therefore accelerating at 1G), you have even more gravitational potential, right?

Another analogy to get to the root of my question. Say Observer A is standing on the surface of Earth and Observer B, right next to them, begins free fall down a deep hole into the earth. At the very moment Observer B begins free fall, they are still just as deep in Earth's gravity well, but are also not accelerating anymore. Therefore, is their clock less dilated at that instant now?
 
mcgnms said:
Now on top of that, since you're standing (and therefore accelerating at 1G), you have even more gravitational potential, right?
No. Why would this be true? Gravitational potential is purely about your position in the gravitational field, not your acceleration.
 
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I'm confused then, you just said that acceleration creates a pseudo gravitational field that acts like gravitational potential. Did I understand that correctly? So by resisting free fall and therefore accelerating, you presumably create gravitational potential, right?
 
mcgnms said:
I'm confused then, you just said that acceleration creates a pseudo gravitational field that acts like gravitational potential. Did I understand that correctly?
No. I said that an accelerating reference frame has a pseudo gravitational field and potential. If you use an accelerating reference frame then there will be “gravitational” time dilation both for accelerating and non-accelerating clocks. If you use an inertial frame there will be no gravitational time dilation for accelerating nor non-accelerating clocks.
 
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Dale said:
If you use an accelerating reference frame then there will be “gravitational” time dilation both for accelerating and non-accelerating clocks. If you use an inertial frame there will be no gravitational time dilation for accelerating nor non-accelerating clocks.
Are you talking about proper acceleration for the clocks or just their coordinate acceleration w.r.t. the chosen reference frame ?
 
cianfa72 said:
Are you talking about proper acceleration for the clocks or just their coordinate acceleration w.r.t. the chosen reference frame ?
I was talking about coordinate acceleration.
 
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