I Does a field affect the originating entity?

[synch]

Eg a gravitational field exists around a mass (A), and no doubt influences any other local mass (B) - but.. - does that field also exert an influence on the original mass (A) ? ie a sort of radial force outwards ?

 

[kuruman]

If you are asking whether mass A can be accelerated by the gravitational field it generates, the answer is no.

 

[Ibix]

Depends what you mean. Extended sources can certainly self-interact. For example the high pressure in the Earth's core is the weight of the outer layers pressing inwards under the gravitational influence of the inner parts.

On the other hand, point sources are problematic in classical physics. You need quantum theory to properly describe electrically charged particles' fields (so says @vanhees71, anyway) and "point" sources of gravity lead to singularities in general relativity, which we hope quantum gravity will sort out.

 

[synch]

Thank you :)

 

[tech99]

If you are asking whether mass A can be accelerated by the gravitational field it generates, the answer is no.

If you are asking whether mass A can be accelerated by the gravitational field it generates, the answer is no.

Will not A will be drawn towards B?

 

[sophiecentaur]

If you are asking whether mass A can be accelerated by the gravitational field it generates, the answer is no.

That statement takes away the symmetry of a situation. The Field (g) is only a description of the effect of the mass of a body. Take two bodies; each has mass and its field causes a force on the other.
You can say the field of body A causes body B to accelerate. But B also has a field and the force of attraction between the two is the same magnitude. The expression
F_A=m_A g_B
can be written the other way round, with A and B transposed so there is no extra significance to a body's mass over its field at the position of the other body. (I appreciate the Maths looks a bit neater one way round, of course.)

 

[vanhees71]

In the relativistic context the answer to the question in the title of this thread is clearly yes. In the electromagnetic context it's known as "radiation reaction" and a notorious problem if you consider point particles. It's not fully consistently solved yet, and I think it's not necessary to fully solve it (if this is possible at all, which I pretty much doubt, but which I also cannot prove mathematically), because the classical point-particle picture is not applicable anyway, because quantum effects have to be taken into account, and there the situation is much better, i.e., QED is well-defined in the perturbative sense at least as an effective theory for not too high energies.

All this analogously holds for gravity too. There you have gravitational waves which affect the motion of the sources (as, e.g., the famous Hulse-Taylor pulsar demonstrates with high precision). Of course in this case we don't have a working quantum description yet.