Visual Studio program "VB2010 Gal MOND" - Description and operation

Introduction and Purpose

The purpose of the Visual Basic program "VB2010 Gal MOND" is to demonstrate galaxy simulation using MOND
For a copy of "VB2010 Gal MOND.exe" select: VB2010 Gal MOND.zip.
This zip file also contains the program "VB2010 Gal MOND PP", which involves Parallel Programming.
For the technical details of this program select: VB2010 Gal MOND PP operation
The program "VB2010 Gal MOND" is base around the question: MOND - What is involved
For the background information about MOND go to:Gal_Mond.bas: Galaxy Simulation in 2 D with MOND

The initial purpose was to simulate a galaxy in 2D using Newton's Law. For background information goto: Program "Gal 2D.bas": Galaxy Simulation in 2 D
For more information goto: Implementation details

For performance issues to Compare Visual Basic 5.0 with Visual Studio 2010 goto


Description

The Visual basic program program "VB2010 Gal MOND" consits of 3 Forms (or displays):


Operation - Control Form

Operation of the program is done from the Control Form.
This dispay shows 3 Commands: Start, End and Stop. This depends about were you are during program execution. After startup the Control Form shows 9 Parameters which can be selected: # ring,# star, methode , v , # steps , B Hole , Curve #, Ext Disk and MOND When MOND is selected the following 3 parameters are displayed:
M min , a0 , Loop cnt and Error.

As an operator the first thing you have to do is to modify the parameters and than to select the Start command.
During Program execution the following messages are possible:


Display Form

The "Display Form" shows the result of the simulation.
The top right corner shows a number. The starting value is 100. That means all the stars in each ring are displayed.
When the value is 1 only one star in each ring is displayed. This allows you to observe the movement of the stars in one particular direction.
When the value is 2, 2 stars in each ring are displayed.


Print Form - Part 1

This Form shows the result of the simulation at the end of the "Mass Calculation" phase in six columns.


Print Form - Part 2

This display shows the numerical results during each simulation.


Program Evaluation - Without simulation

The following are tests are all done without any real simulation.
Starting point are the standard parameters. Ater the message:
Perform Simulation ?
Select NO Command

The galaxy rotation curves 1,2,3, 4 and 5

The purpose of this test is to simulate the different galaxy rotation curves. The only parameter to change is the curve #

200 |xxxxxxxxx                   *               x            **                           x
    |                     *                    x            *      *                       x
    |                 *                      x             *           *                  x
    |              *                       x              *                            x  
    |             *                      x                *                        X
    0             *                    x                  *                 x
      curve 1           curve 2             curve 3           curve 4             curve 5

                             Galaxy Rotation Curves   
Curve # Mond loop counter error total mass
1 On 57 257,14 1248854956
2 On 25 9,24 59198490
3 On 36 0,173 46095610
4 On 25 21,865 96574836
5 On 34 0,092 93288744
The parameter Loop counter shows the number of loops to calculate the lowest error value during the "mass calculation phase." The parameter Error shows this error value.

Galaxy rotation curve #3 is the best curve to simulate. The speed increases lineair.
Galaxy rotation curve #4 is the most difficult to simulate. Constant C4= 0.1
From the "Form Print" you can see that there is the large error between the target and the simulated galaxy curve.
The final target values are: 193.9 188.3 186.4 182.7 and 180.9 (decrease)
The final actual values are: 191.7 192.5 193.5 193.7 and 193.9 (flat)
The important lesson is: Galaxy rotation curves where there is a clear maximum speed and then the speed decreases can not be simulated using MOND
Galaxy rotation curve #1 is the completely flat curve.
Observe calculated rotation curve has the values 200.0 285.7 285.7 285.7 etc.
Most important lesson: There is no mass in the disc This raises an each more serious problem When you measure the speed of the disc of a galaxy as being flat, than you can not explain that using MOND, because in that case there is no matter in the flat disc

Galaxy rotation curves 1 and Black Hole

The purpose of these test is to observe the influence of a Black Hole
Test Curve # v BH loop count error total mass
1 1 140 0 55 180 299850080
2 1 200 1 57 255,35 1229539440
3 1 200 1500 69 184,96 2083760232
4 1 200 15000 1000 1,227 15000003873
  1. Observe rotation curve has the values 140.0 200.0 200.0 200.0 200.0 etc.
  2. Observe rotation curve has the values 200.2 285,1 285,1 285,1 285,1 etc.
  3. Observe rotation curve has the values 200.0 261.6 261.6 261.6 261.6 etc.
  4. Observe rotation curve has the values 200.2 200.3 200.4 200.4 200.4 etc.
The important lesson is: By introducing a large BH you can get a complete flat galaxy rotation curve with MOND

Galaxy rotation curve 1 and MOND versus Newton

Test Curve # MOND M Init loop count error total mass
1 1 Off 111613713709
2 1 On Yes 57 257,14 1248854956
3 1 On No 10 35,863 116548964824
For test 1 the grv is: 200, 200, 200, 200, 200, 200, 200, 200, 200 and 200
For test 3 the grv is: 437, 706, 880, 1020, 1137, 1234,1319, 1385, 1440 and 1459

Galaxy rotation curve 2 and a0 - fixed curve

The purpose of this test is to observe what happens if you MOND and the only parameter that is changed is a0. The rotation curve is the same.
Test Curve # a0 loop count error total mass
1 2 8 24 8,942 58447645
2 2 0.8 24 8,942584476455
3 2 0.08 248,942 5844764551
What the test shows is that when you decrease a0 with a factor 10 the mass m0 is increased with a factor 10.
This behaviour is in agreement with the rule: v1 = SQR(SQR(G * m0 * a0)
This rule describes with v1 being constant when you decrease a0 with a factor 10, m0 should increase with a factor 10. And vice versa.
Important lesson: That by changing the Universal Constant a0 you can give the galaxy any mass value you like.

Galaxy rotation curve 2 and a0 - fixed mass

The purpose of this test is to demonstrate what happens with the rotation curve if you study the same mass distribution changing the parameter a0.
Starting point is rotation curve 2.
It is important that the parameter Loop count is set to -1, in order to prevent the mass calculation phase.
Test Curve # Mond a0 M init V 1 V 10 loop count error total mass
1 2 Off 8 No200 200 -1 130252103693
2 2 On 8 No 216 1554 -1 2826130252103693
3 2 On 0.8 No 122 874 -11360 130252103693
4 2 On 0.08 No 68 491 -1542 130252103693
5 2 On 0.008 No 38 276 -1140 130252103693
6 2 On 0.0008 No 21 155 -1234 130252103693
What can you learn from the above test?
In the tests we keep the total baryonic mass constant. MOND is tetsted by modifying a0

Galaxy rotation curve 2, # stars, MOND versus Newton

The purpose of this test is to demonstrate what the difference is between Newton and MOND when the total number of stars is different
Starting point is rotation curve 2.
Test Curve # # star MOND total mass Mond total mass
1 2 25 On 119435874 Off 131093341851
2 2 50 On 58447645 Off 130252103693
3 2 100 On 29103195 Off 128614178511
4 2 200 On 14463346 Off 127071520697
What the results show is that the total mass of a Galaxy is independent of the number of stars when Newton is considered. This is as expected.
With Newton when the number of stars is increased with a factor of two, the mass of each star is decreased with a factor of two and this has no influence on the overall rotating curve of the galaxy.
For MOND the result is different. The total mass decreases when the # of stars increases.
With MOND when the number of stars is increased with a factor of two, the mass of each star is decreased with a factor of four, in order to explain that the total mass decreases with a factor of two and as such has no influence on the overall rotating curve of the galaxy.
At the same time if you assume that the total mass stays constant (like with Newton) than an increases in the number of stars with MOND will change the overall speed pattern of the Galaxy.


Extended disc with Newton - Curve 6

Curve #6 is special. In this case the galaxy mass is directly calculated. This allows to compare the same mass distribution under different circumstances i.e the visibility of the stars.
Test #ring #star Mond Ext disk Con C6 V nr dens nr Total mass
1 10 50 Off 1 1 221.4 4.27 144590730173
2 10 50 Off 1 3 144 0.57 73078628956
3 10 50 Off 1 1.6 177.3 2.34 112955607832
4 20 50 Off 2 1 183.6 0.76 199868406309
5 20 50 Off 2 1.6 141.6 0.23 136172354007

Important lesson: When observation equipment improves the amount of missing matter to explain the observed galaxy rotation curve decreases.


Program Evaluation - With simulation

The following are tests are all done with a real simulation.
Starting point are the standard parameters. Ater the message:
Perform Simulation ?
Select Yes Command In the following table are 6 tests. The parameter disp # is at the top right corner of the display form. The value 1 means that only 1 star in each ring is displayed.
Test Curve # Ext Disk Mond disp # # ring # stars chaos loop count error total mass
1 2 1 Off 100 1025 60 131093341851
2 2 1 On 100 10 25 400 249,852119435874
3 5 1 Off 100 10 25 90 121112362053
4 5 1 On 100 10 25 2000 290,138 185041948
5 2 1 Off 1 10 25 60 131093341851
6 2 1 On 1 10 25 400 249,852 119435874
7 5 1 Off 1 10 25 90 121112362053
8 5 1 On 1 10 25 2000 290,138 185041948
9 4 2 Off 2 20 30 90 532103053781
10 4 2 On 2 20 30 2000 290,138 1229720034
  • The tests 1 to 4 have a display number of 100. That means the simulation shows all the stars. When you start each simulation you will observe that all the stars follow each other in circles. This stabble pattern will continue for some time until you will observe that some stars will move away, are jected and "chaos" start at a certain angle. This angle is the parameter chaos in the above table. This chaotical pattern is strictly a behaviour of the accuracy of the simulation and not so much a physical phenomena. When you compare MOND with Newton than MOND is more stable.

    A whole different issue is at stake in the tests 5 to 8. In that case only one star is displayed (because disp # = 1). In test 5 and 6 ( with curve # = 2) after the start of the simulation you will observe an almost flat galaxy rotation curve as expected.


  • Reflection

    The most difficult issue with MOND is that you cannot simulate the solar system.
    A similar problem is that you cannot simulate a Galaxy Rotation curve which after the bulge reaches its maximum speed and than very slowly starts to decrease. In such a case with MOND the curve stays flat and there is no mass at all in the disc. This is a serious problem.

    A whole different problem that when two stars merge with Newton this has almost no influence on the stars in its neighbourhood.

    See also: Philosophical considerations about galaxy simulations
    See also: Scientific American September 2015. How Einstein reinvented Reality


    Reflection 2 - Visual Basic 5.0 versus Visual Studio 2010

    When you compare Visual Basic with Visual Stodio than Visual Basic is the winner.

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    Created 18 September 2015
    Updated 22 March 2016

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