Clarifying the dynamics of gravitational field and gravitational wave propagation:

09 February 2024

Dear Mr Tom Hollings,

Your point about the apparent contradiction in the statement about the constancy of the volume of the gravitational field relative to the source seems valid at first glance, but upon closer examination it may not.

The confusion probably stems from a misunderstanding of the concept of 'gravitational field expansion at the speed of light'.

In the context of gravitational waves, it is crucial to distinguish between 'expansion of the gravitational field' and 'propagation of gravitational waves through space'.

Gravitational waves actually propagate outward from their source at the speed of light, carrying energy from the system. These waves are energy-carrying vibrations, like photons, and travel at the speed of light.

However, the expansion of the gravitational field in the traditional sense is not essential for this propagation.

The 'gravitational field volume' surrounding a massive object must be constant relative to that object.

This means that the gravitational effect exerted by the massive body extends indefinitely into space, but the boundaries of the field, perceived from the point of view of the source, remain unchanged in time.

Additional points:

(i) Observational studies indicate that gravity and anti-gravity, driven by dark energy, engage in a constant struggle, with anti-gravity prevailing due to the greater effective mass of dark energy than gravity. As a result, anti-gravity forces prevail in the universe.

(ii) Additionally, it has been observed that there are zero gravity regions around distant galaxies, marking the boundary where the gravitational effect ends and dark energy begins. This indicates that the limit of gravity is not infinite but finite; Where gravity exists, dark energy does not exist, and vice versa.

(iii) Furthermore, dark energy may exist at least in intergalactic space, but the gravitational effect ceases at the boundary of the zero-gravity region surrounding a galaxy. Therefore, the space 'within' gravitationally bound galaxies remains unchanged.

(iv) In general, galaxies are moving away from each other, except for gravitationally bound galaxies or galaxy clusters.

However, this condition is not permanent; In the distant future, gravitationally bound galaxies or galaxy clusters will yield to the effects of dark energy, causing the connections between galaxies to weaken and eventually break up.

Gravitational waves:

Gravitational waves, on the other hand, represent disturbances propagating within space caused by the acceleration or deformation of massive objects. These waves propagate outward through space, carrying with them information about gravitational disturbances. Although gravitational waves do indeed travel at the speed of light, their propagation does not necessarily imply a continuous propagation of the gravitational field.

Conclusion:

Therefore, the constancy of the volume of the gravitational field relative to the source is valid, even in the presence of gravitational wave propagation. The expansion of the gravitational field at the speed of light specifically refers to the propagation of gravitational waves, rather than a continuous expansion of the field.

Regards,

Soumendra Nath Thakur