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Gravitational Waves in Newtonian Physics

The theory of gravitational waves has different assumptions and does not conform to Newtonian gravity. The claims of LIGO are not justifiable.

The basic terminology will be provided in turn. This post is long to justify that conclusion.

quotes are from britannica or Wikipedia.

Gravity
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Gravity is the universal force of attraction acting between all matter. It is by far the weakest known force in nature and thus plays no role in determining the internal properties of everyday matter. On the other hand, through its long reach and universal action, it controls the trajectories of bodies in the solar system and elsewhere in the universe and the structures and evolution of stars, galaxies, and the whole cosmos. On Earth all bodies have a weight, or downward force of gravity, proportional to their mass, which Earth's mass exerts on them. Gravity is measured by the acceleration that it gives to freely falling objects.
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Note: Gravity is measured for a free falling object.

Gravitational field:

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In classical mechanics as in physics, a gravitational field is a physical quantity. A gravitational field can be defined using Newton's law of universal gravitation. Determined in this way, the gravitational field g around a single particle of mass M is a vector field consisting at every point of a vector pointing directly towards the particle. The magnitude of the field at every point is calculated applying the universal law, and represents the force per unit mass on any object at that point in space. Because the force field is conservative, there is a scalar potential energy per unit mass at each point in space associated with the force fields; this is called gravitational potential.
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Note: Therefore in classical physics every body has a gravitational field related to its mass.

Free Fall:

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In Newtonian physics, free fall is any motion of a body where gravity is the only force acting upon it.
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There is a famous experiment for free fall where a heavy ball and a feather are released at the same time in a vacuum chamber. Both fall identically hitting the floor at the same instant.

If I put a feather on the surface of the ocean it does not fall to the bottom but instead rests on the surface due to the weak force of gravity and the density of the water below it. Just a gust of wind can move it; when the wind subsides the feather will rest again, by gravity.

The Earth has substantial lakes and oceans. As a fluid in free fall the water settles to a flat surface, except for other forces like wind.

The Moon orbits the Earth; the gravitational fields must interact.

Tidal Force:
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In celestial mechanics, the expression tidal force can refer to a situation in which a body or material (for example, tidal water) is mainly under the gravitational influence of a second body (for example, the Earth), but is also perturbed by the gravitational effects of a third body (for example, the Moon). The perturbing force is sometimes in such cases called a tidal force (for example, the perturbing force on the Moon): it is the difference between the force exerted by the third body on the second and the force exerted by the third body on the first.
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As the Moon gets closer to the Earth its force of gravity at the Earth's surface is greatest at its closest. This observation follows Newton's  description for gravity.

Earth Tide:
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Earth tide (also known as body tide) is the displacement of the solid earth's surface caused by the gravity of the Moon and Sun. Its main component has meter-level amplitude at periods of about 12 hours and longer. The largest body tide constituents are semi-diurnal. Though the gravitational forcing causing earth tides and ocean tides is the same, the responses are quite different.
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Note an Earth tide is different than an ocean tide due to the amount of mass being affected by the external force; water is flexible but the crust is not.

There are reports of the detection of a black hole merging with a neutron star at a great distance. This event was detected by looking for gravitational waves as expected by Einstein.

A change in gravity in Newtonian physics:

If a distant body in the universe changed its mass the tidal force exerted by that object from that distance would change.
A calculation is required to determine the new  force and its accompanying deformation in Earth's crust, it it could be measured.
This calculation requires the correct mass and distance for accuracy.

As far as I know this calculation has never been done for the LIGO events.

There are reports of the detection of a black hole merging with a neutron star at a great distance. This event was detected by looking for gravitational waves as expected by Einstein.

A change in gravity in Space Time.

Gravitational Wave:

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Gravitational waves are disturbances in the curvature (fabric) of spacetime, generated by accelerated masses, that propagate as waves outward from their source at the speed of light. They were proposed by Henri Poincaré and subsequently predicted by Albert Einstein on the basis of his general theory of relativity. Gravitational waves transport energy as gravitational radiation, a form of radiant energy similar to electromagnetic radiation.

Newton's law of universal gravitation, part of classical mechanics, does not provide for their existence, since that law is predicated on the assumption that physical interactions propagate instantaneously (at infinite speed) – showing one of the ways the methods of classical physics are unable to explain phenomena associated with relativity.
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The description is explicit this behavior  is not Newtonian.

How does this theory work:

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In Einstein's general theory of relativity, gravity is treated as a phenomenon resulting from the curvature of spacetime. This curvature is caused by the presence of mass. Generally, the more mass that is contained within a given volume of space, the greater the curvature of spacetime will be at the boundary of its volume. As objects with mass move around in spacetime, the curvature changes to reflect the changed locations of those objects. In certain circumstances, accelerating objects generate changes in this curvature, which propagate outwards at the speed of light in a wave-like manner. These propagating phenomena are known as gravitational waves.

As a gravitational wave passes an observer, that observer will find spacetime distorted by the effects of strain. Distances between objects increase and decrease rhythmically as the wave passes, at a frequency equal to that of the wave. This occurs despite such free objects never being subjected to an unbalanced force. The magnitude of this effect decreases in proportion to the inverse distance from the source.
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My interpretation:

In the special theory of Relativity the accelerating observer encounters spacetime curvature. Other observers do not see that observer's unique space time.Space time curvature is not real space, though it is called a fabric of space.
Everyone else observes normal physics. This is the famous twin paradox for relativity.

Consequences:
1) no one but the observer at the black hole observes any space time curvature.

2) Observers here on Earth using LIGO cannot observe a distant curvature.
3) Here the universe follows normal Newtonian physics.

4) LIGO could not detect ripples in the fabric of space.

5) if two neutron stars merged in distant space the event must be detected  using Newtonian physics.


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