What Is The Energy of a Point In Space?

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Discussion Overview

The discussion revolves around the concept of energy at a point in space, particularly in relation to electromagnetic radiation and its perception. Participants explore the implications of observing light and energy from different vantage points in spacetime, touching on theoretical aspects of electromagnetic fields and the nature of energy in relation to observation.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the nature of energy at a point in spacetime, suggesting that the energy ascribed to that point may vary based on the observer's location.
  • Another participant introduces the electromagnetic stress-energy tensor as a framework for understanding energy and momentum density at a point, indicating that the same field can appear differently from various perspectives.
  • A participant states the energy of a photon is given by E=hf, relating this to the energy of light observed at a point.
  • One participant argues that a single point is undefined in terms of energy or curvature, suggesting that meaningful measurements require considering neighboring points and their interactions.
  • Another participant discusses the Doppler effect as a reason for the perceived differences in energy based on relative motion, explaining how light can shift in frequency depending on the observer's movement.
  • A participant expresses uncertainty about whether they are discussing the energy of the electromagnetic field or spacetime, seeking clarification on the coexistence of different energies at a single point.

Areas of Agreement / Disagreement

Participants express differing views on the nature of energy at a point in space, with no consensus reached. Some focus on the electromagnetic field, while others consider broader implications involving spacetime and observation.

Contextual Notes

Participants highlight the complexity of defining energy at a point, noting that it may depend on various factors such as observation angles, relative motion, and the framework used for measurement. There are unresolved questions regarding the relationship between energy, observation, and the nature of spacetime.

  • #31
How far is it from point A to point B?
 
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  • #32
gary350 said:
How far is it from point A to point B?

I've often thought about that. Seems to me you cannot have a 'point A and a point B' alone. Because as points there's no way to measure their separation.

A dimensionless point has no dimensions in itself. In a surroundings lacking dimensions there's nothing we can say in terms of dimension.

Given a third point we can start measuring. That third point could be part of the first point if it is given dimensions, thickness, height, width...

Then the distance from A to B becomes in terms of A the number of times you can divide the width of A into the interval.

Hence the need for three. Three is the smallest number.
 
  • #33
I think it's time to close this thread as the contributions become more and more meaningless and tend towards unsubstantial speculations.

Thread closed.
 
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