Science, Physics, Relativity, Faq's and Feedback

Historical Overview #4

Roughly 20 years ago I started with "My Homepage" and again it is time to give an overview of what I have done.
This is not my first Historical Overview.


1. Understanding

What means understanding. Understanding means in some sense that we all agree about something. This something in our case are the laws of nature. One starting point is that we all agree about the definitions of the concepts we use.
One of the first concepts should be that the laws of nature, that means the descriptions of the physical processes, should be completely indepent any of human involvement. If you accept that, than if two humans observe two events either simultaneous or not simultaneous is of no importance for the behaviour of these processes. With observe we mean that each events emits a lightsignal which the observer can detect. What is important is the physical relation between the two events, because there can be common cause. This common cause can be an instantaneous event like an earth quack, which can tricker a sunami or be continuous in nature. Physical processes which causes are continuous from origin for example are the movement of the planets around the sun. In general all astro physical processes.
In short the understanding of all astro physical processes have nothing to do with human involvements. If you support that view than also the concept of visible universe is of no physical significance. What we want to understand is the universe in a much larger sense and not "strictly" based on what we see.
The same with concepts like vissible mater versus dark matter. What is important are concepts like baryonic matter versus non--baryonic matter. A whole different issue is the relation between the speed of light and the behaviour or evolution of astro physical processes. There is almost none, except that visible objects continuously emit radiation in the form of photons. This type of radiation we call electromagnetic radiation or emr.
When you want to understand the behaviour of objects in general in the entire universe a whole different form of radiation is at stake which we call gravitational radiation or gr.
The fact that emr and gr are something completely different can easily be observed when the earth is inbetween the sun and the moon. In that situation the moon becomes almost invisible, but it has absolutely no influence on the movement of the moon. A different case are black holes. BH do not emit emr (in general) but they emit gr. In the above maybe the reader gets the impresion that light is not important in astronomy. In fact it is, but only in the area to perform observations, not in the area of the physical processes that take place inside the astrophysical objects. Within that same context it does not make sense to define the speed of light constant. First of all because the speed of light i.e. the speed of photons, by itself is also a physical process, subject of external influences. Secondly constant in vacuum, while in practice when we want to use the speed of light there is no vacuum. Thirdly because one of the major questions in physics is: if the speed is affected by gravitation.

2. what does it mean: we all agree?

We all agree that the earth is round. With all I mean 99% of the people that have expressed their opinion. For these people it is clear that the earth is round and not flat. The same with all the planets and stars. We also all agree that Newton's law is a powerfull tool to describe the motions of the planets around the Sun. The power of Newton's law is that it is based on the concept that the sum of all the forces with act on each object caused by the other objects is zero. This laws follows the rule that no human involvement is at stake. This law strictly describes the workings of the solar system or any collection of astro physical objects. We all agree that Newton's law assumes that the gravitational force acts instantaneous. That is wrong. The proposed solution is General Relativity, but I doubt if we all agree that this is correct. The problem is that to try to use GR for practical examples, is extremely difficult.
However there are more problems.
There are some major differences between Newton's law and GR. The first starts from a much more global point of view and the second from a local point of view. The first uses the concept absolute, however I would doubt if Newton ever used that concept and the second uses the concept relative. We all agree that when you are standing on a platform the passing train is a moving object, but that does not mean that it makes sense to call the person on the platform a moving object from the point of view of an observer in the train. GR calls both persons at rest in their own inertial reference frame. But what is the purpose of such a frame in a global context?

Does it make sense to call a person anywhere on Earth, on Mars, on Jupiter anywhere at rest in their own inertial reference frame? I doubt that.

3. What are the issues involved when you want to perform simulations using Newton's Law

Newton's Law is compared with General Relativity a very simple law. The main reason is that force of gravity is assumed to act instantaneous. Newton's Law starts from the concept of one 3D reference frame. Within this reference you place n points which represent the position of the objects you want to study. Next you assign to each object a mass value and a speed and your simulation is ready to start.

4. What are the issues involved when you want to perform simulations using General Relativity

General Relativity is compared with Newton's Law very complex. One reason is that it is very difficult to "translate" the mathematics of GR for practical examples, specific when Black Holes are involved. A different reason is that force of gravity propagates with the speed of light.
       H         H
     H     L       H
   H       H         H


   H           H
      H       H

Figure 1
To get an idea what is involved in a practical example. Consider two objects with an equal mass m0. Those two objects rotate around each other in 1 second. There is also a third object involved which rotates at a distance of 1 light second around the center of gravity of the two objects.

Figure 1 at the left shows two objects which are indicated with the letter X. The two objects are considered to be Black Holes.
The two BH's are surrouned by 4 letters: 2 times the letter H and two times the letters L. Those 4 letters are the starting point of the gravitational waves which rotate outwards. The two letters H stand for High, to indicate that the gravity field is the strongest. The two letters L stand for Low, to indicate that the gravity field is the lowest.
The two BH's rotate counter clockwise in 1 second.

  • After 1/4 second the two BH are vertical direction, That means that the letter H in red has rotated to the position L West.
  • After 1/2 second the two BH are again in horizontal position, That means that the letter H in red has rotated to the position H South.
  • After 3/4 second the two BH are again in vertical direction. That means that the letter H in red has rotated to the position L East.
  • After 1 second we are back to the original position, and the letter H in red has completed on revolution.
In reality the letter H in red, which represents the strong gravitational field, did not perform 1 rotation, but moved up "North" a distance of 1 light second. During this transport the gravitational field went weaker.
Now let us study some numbers. The following table shows the result of 5 tests. The masses are indicated as sun masses.
test T m0 m1 dist r0 r1 v0 v1 angle T
1 1 1 1 1887 944 944 5929 5929 0,36
2 1 40 40 6445 3227 3227 20278 20278 1,23
3 0.02 40 40 476 238 238 74706 74706 0,09
4 2001 2 0.001 299792 150 299642 0.5 941 57
5 1928 40 40 1000000 500000 500000 1629 1629 191

5. The importance of gravitational waves

Figure 1 gives an impression that gravitational waves are important to study the behaviour of binary objects like binary BH's or binary Neutron stars. They are not. Gravitational waves are important when triple systems are considered or for LIGO type of experiments which primary objective is to measure gravitational waves.
Gravitational waves are not important what is important is the gravitational radiation or energy by each of objects i.e. Black Holes.
         <---- 1

  a                   A

         2 ---->
Figure 2
To get an idea what is involved in a practical example. Consider two objects with an equal mass m0, which rotate around each other.

Figure 2 shows the position of the two objects for each at 5 different instances.

  • Object 1 is indicated at the instances A, B, C, D and E.
  • Object 2 is indicated at the instances a, b, c, d and e.
When you use Newton's Law the gravitational force acts instantaneous. That means Object 1 at position A is instantaneous affected by object 2 at position a. When at B by b etc.
For low speeds relatif to the speed of light this is no problem, but for larger speeds this can be a problem.
What this means is that when object 1 is at "E" the gravitational radiation emitted by object 1 did not have enough time to reach position "e". In fact object 2 at "e" is affected by the retarded position of object 1. This can be position "D". When the distance between the two objects is d, than the travel time t = d/c.
When the speed of the object is v. This defines a distance v*d/c and an angle v/c , which is normally much less than 1.
What this means that the concept of graviatational waves is of almost no importance within the spherical space defined by the rotating objects. The whole issue is the amount of gravitational radiation and energy loss of the two objects.

The results of the simulations I have performed on rotating objects with Newton's Law and when this retardation is included that the objects move away from each other. The distance expands and there is no contraction or merging.

Created: 20 Okt 2016

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