Spacetime, curvature, orbit, matter and reactions

In summary, the film Einstein and Eddington uses a table cloth, bread, and fruit to demonstrate the theory of spacetime. However, this analogy has flaws as it only represents 2 dimensions of space and does not include the crucial time dimension. The idea of light causing shadows in the curved space is also incorrect as the cloth itself represents the space in which light propagates.
  • #1
Elliot.exe
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In the BBC film Einstein and Eddington, Eddington describes the theory of spacetime using a table cloth (space), a loaf of bread (sun) and a piece of fruit (a planet).

The Bread is placed in the middle of the table cloth, this forms curves in the cloth. He then takes a piece of fruit and throws it in. The fruit oribits the bread along the curves. This shows spacetime.

This provoked and idea in my head, The sun is a source of light, In the curves of the cloth there are shadows caused by the sun. The curves of space might have light from the sun causing a "shadow" of light particles or matter in the same way there was a shadow in the cloth. I also think this might cause a reaction as a planet orbits. the idea is rough but in theory it could work.

Or is it all just, like Thunderbirds just string theory

Elliot.exe
 
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  • #2
Well, I wouldn't take the table cloth analogy too seriously (it has big flaws) but you can get gravitational lensing, so I would think you could get other optical effects like shadows.
 
  • #3
Elliot.exe said:
In the BBC film Einstein and Eddington, Eddington describes the theory of spacetime using a table cloth (space), a loaf of bread (sun) and a piece of fruit (a planet).

The Bread is placed in the middle of the table cloth, this forms curves in the cloth. He then takes a piece of fruit and throws it in. The fruit oribits the bread along the curves. This shows spacetime.
No this is not spacetime. This is just space (2 dimensions of it). There is no time dimension in this analogy which is crucial for the gravity model of General Relativity. Follow the links in this post, for better visualizations:
https://www.physicsforums.com/showthread.php?p=2046692

Elliot.exe said:
This provoked and idea in my head, The sun is a source of light, In the curves of the cloth there are shadows caused by the sun. The curves of space might have light from the sun causing a "shadow" of light particles or matter in the same way there was a shadow in the cloth.
You are completely misunderstanding the analogy here. The cloth itself represents the space in which light is propagating. So in this analogy the light from the bread (sun) would propagate only within the cloth, not outside of it. There are no shadows caused by spatial curvature around the sun, but optical distortions are possible as DaleSpam said.
 
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1. What is spacetime?

Spacetime refers to the four-dimensional concept that combines space and time into one unified entity. It is the framework in which all physical events occur and is described by Einstein's theory of general relativity.

2. How does curvature affect spacetime?

According to Einstein's theory of general relativity, matter and energy cause spacetime to curve. This curvature is what we experience as gravity. The more massive an object, the greater its curvature of spacetime and the stronger its gravitational pull.

3. What is an orbit?

An orbit is the curved path that an object takes around another object under the influence of gravity. This can be seen with planets orbiting around the sun or satellites orbiting around Earth.

4. What is matter and why does it interact with spacetime?

Matter is any physical substance that has mass and takes up space. According to Einstein's theory of general relativity, matter and energy are what create the curvature of spacetime. Matter is affected by this curvature and is pulled towards objects with greater mass.

5. How do reactions play a role in spacetime?

Reactions involve the conversion of matter into energy and vice versa. This exchange of energy and matter can affect the curvature of spacetime, thus influencing the behavior of objects within it. In addition, reactions such as fusion and fission in stars can create immense amounts of energy that contribute to the overall structure and dynamics of the universe.

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