In his paper titled "Aberration and the Speed of Gravity," S. Carlip argues
that gravity propagates at light speed, and, its "action at a distance" and
the lack of observed aberration is canceled by velocity dependent
interactions.
In this paper, I show why gravitational waves
and gravitons are not the root cause of gravity.
It should be mentioned that gravitational waves are the equivalent of a varying gravitational field and that gravitons are the particles or the building blocks of the gravitational field.
It will be interested to read what the author considers the cause of gravity.
Gravity emerges from an
entangled relationship between spacetime and matter.
The problem is that you try to explain something i.e. Gravity by introducing three new concepts i.e. entangled-relationship, spacetime and matter, which each are also difficult to understand and require a detailed explanation.
Modern physics has two conflicting ideas: 1. gravity propagates at light speed, and 2.
the equivalence principle. Why are these two ideas in conflict?
Okay
The first proposes
that gravity works in the following manner: a person holds a pen in his hand and
drops it. Before it hits the floor, however, the floor must emit gravitons that
propagate at c to create a field of gravity, so the pen can receive the gravitational
information; otherwise, the pen won't fall.
This description is more or less correct, exept that the floor, continuous emits 'gravity' i.e. gravitons.
In practice this means that there is always a gravitational field.
The second idea is often set forth using a thought experiment where the person
holding the pen is in a spaceship.
Thought experiment are often not the best way to study physics. The best way is by using real experiments because in reality real experiments involve much more complications than in thought experiments. For example: in a thought experiment it is easy to travel at a speed of 10 times the speed of light or to include infinite speeds.
General speaking in a space ship it is assumed that the gravitational force of the spaceship, the astronauts and and the pen towards the earth is zero. That means they all have the same speed as the earth and move in one year, like the earth, around the Sun, influenced by the gravitational field of the Sun. That means there are gravitons involved.
The thrust of the engines cause the floor to
accelerate toward the pen when the pen is dropped; otherwise, the pen would float
freely in space and never make contact with the floor. In this scenario, no gravitons
or gravitational field are needed. The floor is on a collision course with the pen and
does not need to send a signal to the pen to let it know it's coming. According to
Einstein, this is indistinguishable from gravity.
As explained above I have doubts about this explanation.
Therefore, this great idea and the one
that precedes it create a paradox: the first idea implies a force is causing the pen to fall,
so a force-carrying particle is necessary. The second idea implies there is no force
The second idea is wrong.
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That begs the question: does gravity require gravitons? Let's examine what may be a
source of gravitons and strong evidence that gravity's velocity is c: gravitational
waves. Equation 2 below is a gravitational-wave equation:
Equation 1
Equation 2
From equation 2 we derive equation 3 which emphasizes that c is a component of
rest-mass energy and not propagation speed.
No comments
Equation 3
Does gravity exist if there are no gravitational waves?
You cannot think about a world without masses and when there are masses there is gravity, these masses influences each other and as a result there are variable gravitational fields change.
When these masses revolve around each other you can observe gravitational waves.
A typical case is our solar system and at a more larger scale the stars in the Milky way Galaxy.
To find out, we take angular frequency to zero.
Mathematically you can do that. But
that is physical an impossible exercise, because it means to reduce the speed of all the planets around the sun to zero. The result will be a total collapase.
In fact the result is that the mathematics does not describe the physical reality.
The time (t') it takes for no waves to propagate a distance r is also zero.
The final result is equation 5:
Equation 4
Equation 5
From a more philosophical point of view: You cannot show from an equation how the universe evolves.
It is the other way around.
First you observe the physical reality. Next you define a general equation which describes this process.
Finally you calculate the parameters of this general equation based on observations.
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Where there are no gravitational waves there is zero angular frequency and zero strain
measured at distance r, but on the left side of equation 5 we see Newtonian gravity is
not zero. Thus, the magnitude of gravitational acceleration does not depend on the
magnitude of gravitational waves nor their quanta. Further, a zero time delay (t')
implies action at a distance.
This whole exersize, playing with mathematical equations, is tricky.
The standard approach is: first perform an experiment and devellop the equations that describe this experiment.
Next make small modifications to the experiment and update the equations.
In the above exercise the modifications are physical unrealistic and lead to wrong conclusions.
A comparison between electric waves and gravitational waves reveals why photons
are observable and gravitons are not.
Photons are visible because we humans have eyes, but the existance of photons has nothing to do with the existance of humans. Photons are a part of electro-magnetic radiation.
The same with gravitons. We humans cannot detect or see them, but that does not mean that they don't exist. Gravitons are a part of gravitational radiation more or less the same as photons are part of electromagnetic radiation.
We can hear noise because we have ears. Some birds navigate because they use the earth magnetic field. See:
https://www.audubon.org/news/lost-birds-rely-earths-magnetic-field-get-back-track
The wave equation i below represents an
electric field (photons) propagating at c. Equations ii through iv demonstrate how
the removal of the electric field (photons) leads to no electromagnetic force:
By contrast, if the gravitational field (gravitons) is removed, Newtonian gravity still
exists
The second idea is wrong.
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Equations v, vi, vii, viii, ix, and x
Assuming gravitons are not the root cause of gravity, what exactly is? If we begin
with the spacetime metric (equation 6), we can derive equations 9 and 10 below:
Equations 6, 7, 8, 9, and 10
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Imagine, for the sake of argument, there is a graviton propagating at velocity c.
It is wrong to compare the speed of gravity with the speed of light. Infact you should always call the first cg and the second c.
Equation 9 shows if the graviton's energy (E) changes, the spacetime must also
change instantaneously; otherwise the constant c would have a different value during
the time it takes the graviton to emit another graviton which then transports
information to surrounding spacetime.
In other words, if the speed of gravity is
limited to c, there would be a time lag where c is no longer c! The same holds for
Planck's reduced constant at equation 10. The very constants physics relies on
would fail to be constant if gravity is required to propagate an information-carrying
particle no faster than c.
It is wrong to compare the speed of gravity with the speed of light. Infact you should always call the first cg and the second c.
A careful examination of equation 9 reveals the graviton's energy, when divided by
Planck's constant, has the same dimension as frequency, and the spacetime has the
same dimension as wavelength.
Frequency and wavelength have an entangled
relationship. If you measure the value of one, you instantaneously know the value of
the other.
Frequency and wavelength have a mathematical relationship.
It is wrong to use the word entangled. It is also wrong to call the concepts 'content' and the multiplication of the concepts 'length' times 'broath' times 'height' an entangled relationship.
In the case of our graviton, a change in its energy instantaneously updates its
surrounding spacetime.
Our graviton does not need to emit a graviton--and neither
does any particle, planet, star, or black hole.
Thus, if the graviton is ever discovered, it is not the root cause of gravity.
Gravity is the result of an entangled relationship between matter and spacetime.
That is easy to write but difficult to explain.
Generally speaking Gravity, matter and spacetime have nothing in common.
Two objects attract each other. Why? That question is difficult to answer.
Has spacetime anything to do with that? The problem is that spacetime is a mathematical concept. Spacetime is not something that exists. It is more or less a description of the evolution of space over a period of time. Space meaning not empty space but the objects within this space.
Matter has a certain energy and moves in certain ways because of a certain configuration of
spacetime, and spacetime has a certain configuration because matter has a certain energy and moves in certain ways.
The problem with this sentence is the concept 'configuration of spacetime'.
What you want to know is how objects move through the universe. The sentence studied, does not give that answer.
Like frequency and wavelength, one does not exist without the other.