B How do fields retain their uniformity with interposing objects?

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Interposing objects like Mercury or Venus do not diminish the gravitational influence of the Sun on Earth due to the linearity of gravitational fields, where the total gravitational effect is simply the sum of the contributions from each source. Newtonian gravity and Maxwell’s equations are linear, meaning that the presence of additional sources does not alter the fundamental influence of the primary source. While general relativity and quantum electrodynamics introduce non-linearities, in many scenarios, fields retain their integrity despite interposing objects. Gravitational waves are expected to experience phenomena like gravitational lensing, similar to electromagnetic radiation, but current detection methods are not yet sensitive enough to confirm this. The discussion highlights the distinction between static and changing fields, emphasizing that static fields are not described by particles or waves.
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Why don't interposing objects interfere with the integrity of a field's energy between the source and its absorber?

For example, the Sun's gravitational field spreads uniformly through space. If there are interposing objects like Mercury or Venus between the Sun and the Earth, why don't they reduce the amount of gravity that the Earth experiences? The gravitational field may act as a particle or wave (that wraps around the interposing object), but there would be less energy past that point by doing so in either case.

So, if there are a number of interposing objects between the source and target, how does a field retain its integrity and uniformity wrt its inverse square aspect?
 
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In general, there are no mechanisms in physics. Only the appropriate mathematical model. I used the example recently of the electric field being uninterrupted by intervening charged particles.

GR is more sophisticated mathematically than classical EM, but there is still no mechanism to "explain" the Einstein Field equations. Newtonian gravity is physically inexplicable, as Newton himself famously declared.
 
A static field is not described by a wave or a particle. Changing fields can be described by waves or particles (if one has a quantum theory for that field), and may well be affected by objects they encounter. As far as I know we expect gravitational waves to experience gravitational lensing in much the same way EM radiation does. Our gravitational wave detectors are not yet sensitive enough to confirm that, however.
 
Clueless123 said:
the Sun's gravitational field spreads uniformly through space. If there are interposing objects like Mercury or Venus between the Sun and the Earth, why don't they reduce the amount of gravity that the Earth experiences?
Ok, so just a small bit of terminology. The word you are looking for is “linearity”, not “uniformity”.

A uniform field would be a field that is the same everywhere. An inverse-square field is not uniform, it gets weaker the further away you go from the source.

A linear field is one where the total field at a point is simply the sum of the fields from each of the sources. This is the concept you are looking for.

Newtonian gravity is linear. The gravity from 2 sources, say the Sun and Venus, is simply the sum of the gravity from each source alone. Venus does exert its own gravity, but it doesn’t change the influence of the sun.

Maxwell’s equations are also linear, so they exhibit this same feature you are interested in. However, both Maxwell’s equations and Newtonian gravity are approximations to other theories (quantum electrodynamics and general relativity) that are non-linear. So there are scenarios where you cannot treat the fields as linear and the presence of two sources does result in a loss of “integrity” as you described.
 
Ibix said:
A static field is not described by a wave or a particle. Changing fields can be described by waves or particles (if one has a quantum theory for that field), and may well be affected by objects they encounter. As far as I know we expect gravitational waves to experience gravitational lensing in much the same way EM radiation does. Our gravitational wave detectors are not yet sensitive enough to confirm that, however.
A field is a field. When quantized there are specific states of the quantum fields, which can be interpreted in some sense as "particles". I'd rather talk about "quanta" though, because particularly for the electromagnetic field, a spin-1 massless field, the particle interpretation is pretty far from being a good intuitive picture. There's no way to localize a photon. There's not even a position observable in the usual sense!
 
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