Is Flat-Earth's Gravity Theory Flawed Due to Relativistic Acceleration?

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Discussion Overview

The discussion revolves around the concept of gravity as proposed by flat-Earth theories, specifically examining whether gravity could be explained by a constant upward acceleration of the Earth. The conversation explores implications of relativistic effects on acceleration and gravity, including perspectives from different frames of reference.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that if gravity is not due to mass attraction, a constant upward velocity would not suffice to replicate gravitational effects, implying a need for constant acceleration instead.
  • The same participant questions whether it would be possible to maintain indefinite acceleration and discusses the implications of relativistic effects on mass and acceleration as perceived from different frames of reference.
  • Another participant notes that in relativity, acceleration is relative, highlighting that different observers may measure varying values of acceleration based on their relative motion.
  • This participant introduces the concept of "proper acceleration," which is the acceleration experienced by an object and measured by an accelerometer, suggesting that if the flat Earth were accelerating upwards at 1 g, an inertial observer would measure a decreasing acceleration as their relative velocity approaches the speed of light.

Areas of Agreement / Disagreement

Participants express differing views on the nature of gravity and acceleration in the context of flat-Earth theories. There is no consensus on the validity of the flat-Earth model or the implications of relativistic acceleration.

Contextual Notes

The discussion includes assumptions about the nature of gravity and acceleration that are not universally accepted. The implications of relativistic effects on mass and acceleration are also not fully resolved.

Who May Find This Useful

Individuals interested in discussions about gravity, relativistic physics, and alternative theories of Earth’s shape may find this conversation relevant.

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I just recently heard about how this small but still existent flat-Earth society believe that gravity on our supposedly flat Earth is caused by the Earth always moving upward at a constant velocity.
Now obviously assuming the Earth is flat and that gravity isn't caused by mass attraction, then this still couldn't be the case because you would need a constant acceleration upwards rather than a constant velocity to have the same effect as gravity.

So I was wondering, in this scenario - whatever the force is that is accelerating the Earth - would it be possible to keep accelerating it indefinitely? From an observer not on the Earth, it would seem that the mass of Earth would increase without bound as it reaches the speed of light and thus the acceleration couldn't be maintained with the same force being applied. However, for an observer on the Earth it would still be experiencing the same acceleration since from its perspective they are still stationary in a sense.

Are both these observations correct? And would observing that the humans on Earth are experiencing the same gravity effects even when their acceleration is now negligible in the other frame of reference be pretty much the same as observing them slowing in time?
 
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yes =)
p.s. "flat-Earth society" - fantastic...
 
In relativity, acceleration is relative too. Although all inertial observers agree whether an object is accelerating or not, they disagree over the value of a non-zero acceleration. An inertial observer who is momentarily at rest relative to an accelerating object ("comoving inertial observer") will measure a larger acceleration than observers who have non-zero relative velocity, and the acceleration tends to zero as the relative velocity approaches the speed of light.

The acceleration measured by a comoving inertial observer is called "proper acceleration". It the "g-force" that the object experiences and what is measured by an accelerometer attached to the object.

If the "flat earth" was accelerating upwards with a constant proper acceleration of 1 g, the acceleration measured by an inertial observer would gradually decrease to zero.
 
Thanks for your contributions :smile:
 

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