How Does Space-Time Influence the Fall of an Apple?

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Discussion Overview

The discussion centers around the influence of space-time curvature on the fall of an apple, exploring concepts of gravity, acceleration, and the nature of forces in the context of general relativity. Participants engage with theoretical perspectives and interpretations of gravitational effects on objects in motion.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions how space-time curvature affects the fall of an apple, seeking a visualization of this concept.
  • Another participant proposes that the Earth's surface is accelerating upward due to core pressure, suggesting that this upward acceleration affects the apple's motion through inertia.
  • A different participant asserts that gravity is not a force but a curvature in space-time, emphasizing the need for answers within this framework.
  • Some participants challenge the idea of upward acceleration of the Earth's surface, labeling it as nonsensical and arguing that the apple's downward motion can be explained through general relativity as movement along a straight line.
  • There is a contention regarding the interpretation of acceleration in general relativity, with one participant asserting that the apple's apparent acceleration downward is a result of the upward acceleration of the Earth.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of gravity and acceleration, with no consensus reached on the explanations provided. Disagreements arise particularly around the interpretation of upward acceleration and the role of space-time curvature.

Contextual Notes

Participants reference different interpretations of gravitational effects and the nature of forces, indicating a reliance on varying definitions and assumptions about space-time and acceleration.

thinker93
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I've been wondering since a long time how does the space time curve affect the apple. If the apple isn't attracted by any force but because of the space time, then help me visualise the correct picture of space time which makes the apple fall on the earth.
 
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The surface of Earth is accelerating upward (due to the pressure in its core), pushing the tree to accelerate upward, pulling the apple stems to accelerate upward. By the inertia of the apples they lag downward and place tension on the stems and branches (and pressure on the roots and everything below). If the stem breaks then the apple stops accelerating and keeps going at the speed it already had, but the tree keeps on accelerating upward and the accelerating ground catches up with the apple. Just like if the apple tree were in a rocket-elevator in outer space.

Where does space-time curvature come into it? It allows the opposite sides of the planet not to be getting any further apart, despite their accelerating in seemingly opposite directions.
 
Last edited:
To cesiumfrog,
I'm not talking about Newton's discovery. If you have ever read about space time, you would surely know that it is the space time curve that creates gravity. Gravity is not a force. It is actually a curve in the space time. I want my answer in this context.
 
Cesiumfrog's claim that "The surface of Earth is accelerating upward (due to the pressure in its core)" is non-sense anyway.
 
HallsofIvy said:
Cesiumfrog's claim that "The surface of Earth is accelerating upward (due to the pressure in its core)" is non-sense anyway.
No its not, his description was actually exactly what the OP was asking for.

The apple "accelerating" downwards is not actually an acceleration in GR but instead it is its movement along a straight line aka it have no acceleration. When it lies still it don't move according to a straight line any more and thus it must be accelerating, as such if you implement GR every part of the surface is accelerating upwards while if you throw an apple it stops accelerating upwards, while the rest do accelerate upwards making it look like the apple is accelerating downwards when it is actually the other way around.
 
@thinker93: read again, cesiumfrog gave the answer.
 

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