Large energy of gravitational waves vs. electromagnetic waves

Robert C. Hilborn (2017) calculated that gravitational waves hold 16 times the energy content of analogous electromagnetic waves.

The calculations in our previous blog post suggest that the reason for the high energy density is that gravitational waves perturb the metric of space. We are able to extract a lot of energy using rigid rods.

Why do gravitational waves change the metric of space?

Larger inertia in the radial direction

Our Minkowski & newtonian model explains the stretching of the spatial metric by the fact that the inertia of any object is larger when it moves radially in a gravity potential well. The inertia is smaller if the object moves horizontally.

The speed of light is slower in the radial direction of the potential well. All objects move slower in the radial direction if they make a 90 degree turn from a movement in the horizontal direction.

We introduced the axiom that a slower speed of light to some direction necessarily involves the squeezing of all force fields in that direction. Every measuring rod becomes shorter in that direction. One may speculate that this is due to a slower speed of light.

Thus, everything moves slower or is shorter in the radial direction. That is equivalent to a stretched metric.

Why is the inertia larger in the radial direction? We conjectured that the object draws energy from the gravity field, or puts energy into it. The energy apparently comes from a distant location. Shipping mass-energy over a long distance involves inertia.

From what distant location does the energy come? If gravity would only have finite reach and have homogeneous strength, we were able to explain the inertia by assuming that the energy comes from the "surface" of the gravity field.

If we have a test mass hanging from a rope which at the "surface" is attached to a spring to keep the system in balance, then moving the test mass lower transfers energy from the test mass to the spring system at the surface. We would expect inertia to be larger when energy moves a long distance over the rope.

The inertia in the horizontal direction has increased because the test mass ships with it negative energy of the gravity field. But the inertia in the radial direction is even larger because besides shipping the existing negative energy, the test mass draws more negative energy from a distant location ("surface"), or returns negative energy back to the surface.

What exactly is required to harvest a lot of energy from a gravitational wave?

To harvest energy from a gravitational wave, we need rigid rods whose effective length gets contracted inside the wave.

It is enough that the gravity field squeezes some other force field. That probably happens if gravity is coupled to the quantum of that other force field. The coupling allows gravity to tamper with the other force field.

In this reasoning we did not use the attractive nature of gravity at all.