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Old May 19th 21, 03:05 AM posted to sci.astro.research
Nicolaas Vroom
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Default Sagittarius A*, S62 and S1.

Op woensdag 28 April 2021 om 18:31:27 UTC+2 schreef Nicolaas Vroom:
Sagittarius A* is considered a large Black Hole at the center of
the Milky Way.


Some more details about the simulation of Sagittarius A*
The simulation is performed in cycles.
At each cycle, for each object, based on the present velocity and position,
the acceleration, velocity and position of the next cycle are calculated.
The time between each cycle (dtime) is 200 seconds.
The astronomical time is dtime * cycle_number + t0.
t0 is the astronomical time of cycle 0. Normally set equal to 0.
Considering the update of all the pixels of a display as a simultaneous
event, than the update all the positions of all the objects, which all reflect
the same astronomical time, are also simultaneous events.
What this means is that there are no moving clocks involved.
This means that the algorithm used to calculate the positions etc. does not
require the speed of light. This is different for the masses of objects
which have to be calculated, in advance, based on observations.
In Newton's case the speed of gravity propagation is set to infinity.
This also means that gravity forces act instantaneous.

The calculation of the initial state of the objects at t0 is more complicated.
In that case the positions of all the objects involved have to be calculated
at a sequence of events before t0. What is also important that the time
when the positions are measured and the time that events take place i.e. the
time that objects are at these positions is earlier. The reason is the light
travel time, which is the distance between the position of the measurement location
and the position of the measured event, divided by the speed of light.
When all that is taken into account the positions at t0 can be calculated
but also at t-1, t-2 etc.
Using these positions the masses of the objects involved can be calculated.
This is 'rather' simple using Newton's Law but very complicated using GR.

As already mentioned as part of the simulation no moving clocks are involved
i.e. time dilation is no issue.
The same with length contraction.
To read more about the universe in 3D, please study this link:
http://users.telenet.be/nicvroom/VB%20Universe3D.htm

Nicolaas Vroom