Visual Basic 5.0 program "VB Train" & "VB2010 Train" - Description and operation
Introduction and Purpose
The purpose of this document is to discus both programs "VB Train" & "VB2010 Train".
Both both are functional identical. "VB Train" is writen in Visual Basic 5.0 and "VB2010 Train" in Visual Basic 2010 Express.
Both programs are used to demonstrate the Length Contraction, a visible illusion by performing a simulation of a train around a race horse track.
To download an executable VB Train.exe select: VB Train.zip
To download an executable VB2010 Train.exe select: VB2010 train.zip
For more information goto: Implementation details
For a description of the mathematics (physics) involved see the above link. The importance of the program is that it is a simulation what an observer observes (sees) from a fixed point.
- When the track is an circle the observer sees the front of the train retarded. This angle is a function of the speed of the train divided by the speed of light. This angle is identical for the front as for the back. That means the observed length of the train is fixed.
- When the track has the shape as a race horse track there are two distinct situations, depending when the train moves away from the observer or approaches the observer.
- When the train starts at the middle of the outgoing leg, the observer sees the back of the train moving earlier then the front of the train. That means the train look shorter.
- When the train starts at the middle of the incoming leg, the observer sees the front of the train moving earlier then the back of the train. That means the train looks longer.
Operation - Control Display - Initial
Immediate after being started the program shows the Start and the Cancel push buttons.
Select the Start pushbutton.
The display changes. See picture 1
The purpose of the display is to select a simulation and to start the simulation.
Three simulations are possible:
In order to select an experiment the Simulation parameter is used The initial value is 1: Round Track Simulation.
- Type 1; This demonstrates a round track.
- Type 2; This demonstrates a race horse track
- Type 3; This demonstrates two long trains (Terrell rotation)
When the Simulation parameter is selected the value is incremented i.e. becomes the value 2. etc.
When the Select Pushbutton is selected the simulation starts.
Operation - Control Display
Operation of the simulation is done from the Control Display.
The Control Display contains four push buttons: "Stop", "Cancel","V >","V <,"V = 0" and "Freeze"
The Display shows the additinal parameters:
- The "Stop" push button is used to stop the program.
After the "Stop" push button is pressed the simulation stops and the text changes to "Select"
- After the "Cancel" push button is pressed the program terminates.
- After the "V >" push button is pressed the speed of the train increases with 1.
- After the "V <" push button is pressed the speed of the train decreases with 1.
- After the "V = 0" push button is pressed the speed of the train immediate stops. See below.
- After the "Freeze" push button is pressed the display is temporary froozen.
When the "Un Freeze" push button is selected the simulation continues.
- The parameter Length Contraction shows if length contraction is used. This parameter can be changed.
- means that no physical length contraction is involved
- means that physical length contraction is involved accordingly to the parameter Lambda
- The parameter v shows the actual speed of the train.
- The parameter c shows the speed of light.
- The parameter Time shows the local time of the watch of the observer.
The track display shows the result of the simulation.
Length Contraction = Off
Length Contraction = On
- Picture 2 shows the result of the simulation for the round track.
What is important (For a round track) when you start the simulation and after you have increased the speed that during the simulation (and v = constant, parameter Length Contraction = OFF) that both the parameter Length and V obs don't change.
- The Black curve shows the real position of the train along the track.
- The two red dots show the retarded positions of both the front and the back of the train.
- The Yellow curve shows the observed position of the train. That is what the observer sees.
- The parameter Length shows the observed length of the train. The rest length is 1000 in VB Train. In VB2010 Train the rest length is 100.
- The parameter V obs shows the observed speed of the train.
- The parameter Proper Time shows the time of a (moving) clock in the train.
In the case that parameter Length Contraction = ON see below in the paragraph Length Contraction
- Pictures 5 and 6 show the result of the simulation for the race horse track.
The target value of the speed v = 6. That means increase the value v slowly from 1 to 2 to 3 to 4 to 5 and finally to 6 and observe what happens.
Both Length and V obs will change. (Length Contraction = OFF).
In this case you will observe is also what is called Terrell rotation.
- When the train moves away from the observer (out going leg) the length decreases. See Picture 5. The length between the two red dots is shorter as the length of the black line.
The observed speed 5,09 is smaller than the actual speed v=6.
- When the train moves towards from the observer (in going leg) the length increases. See Picture 6. The length between the two red dots is larger as the length of the black line.
The observed speed 7,27 is larger than the actual speed v=6.
- When the train is at furthest distance both the length and the speed return to their standard values (Assuming parameter Length = OFF)
Time Dilation / Clock Dilation
Time Dilation is standard implemented using Special Relativity. That means that the moving clock (on the train) runs slower than the clock at rest.
To demonstrate this you have to compare the parameter Time on the Control Display with the parameter Proper Time on the Track Display.
To demonstrate this, you have to do is to increase the speed of the train to a value larger than 10.
When you do that you will observe that Proper Time runs behind Local Time.
The maximum will be reached when v = 30, which is equal to the speed of light. In that case the parameter Proper Time will become froozen.
In picture 3 & 4 both the time Local Time is 204 and the Proper Time is 200
In picture 5 the time Local Time is 91 and the Proper Time is 90
In picture 6 the time Local Time is 155 and the Proper Time is 152 and
Physical Length Contraction
Physical Length contraction is an option. To include physical Length contraction you have to change the parameter Length Contraction from OFF to ON.
- For Simulation 1 with the round track Length Contraction is rather straight forward. The easiest way to observe it when V becomes lager than 20.
For speeds above 29 when you select "V Inc" the speeds in creases more slowly.
- For Simulation 2 with the "Race horse Track" Length Contraction becomes slightly more difficult.
- When the train moves away from the observer (out going leg) the observed length even becomes more smaller.
- When the train moves towards from the observer (in going leg) the the observed length does not become as large.
The Command "V = 0"
The parameter "V = 0" is specific important to demonstrate Terrell rotation, Specific for Simulation 2 i.e. "The Race Horse Track" with parameter "Length Contraction" = OFF.
To demonstrate select "Start", Select Simulation 2, select "Select" and increase the speed to 5.
- When the train is in the out going leg select "V = 0". What you will observe that the train will stop but that the two red points will continue to move. The dot at the back will stop the first when it has reached the back of the train. The dot at the front will continue to move until it has reached the front.
This simulates that the observer will first (in this situation) that the back of the train has stopped and than the front.
- Increase the speed again to 5 and now in the in going leg select "v = 0". You will observe the reverse.
In the simulation of Terrell Rotation two trains are used.
For a description See: Terrell Rotation
To perform a simulation:
- Select Start Push button.
- Select Simulation 3
- Select Select Push button.
- Select v> Push button 10 times slowly. Finally you will get v=10.
Observe how the train moves from left to right.
- Select Freeze Push button. This will freeze the display.
- Select Length Contraction ON
- Select UnFreeze Push button. This will unfreeze the display.
Observe how the train moves from left to right.
Picture 7 and Picture 8 show Terrell rotation with "Length Contraction" = OFF with the train moving from left to right.
When Picture 7 is selected you can see the train at the fartest left.
- Picture 7 shows the train left from the center. Picture 7 also shows length expansion.
- Picture 8 shows the train right from the center. Picture 8 also shows length contraction.
When Picture 8 is selected you can see the train at the fartest right.
Picture 9 and Picture 10 show Terrell rotation with "Length Contraction" = OFF with the train moving from left to right.
When Picture 9 is selected you can see the train at the fartest left.
- Picture 9 shows the train left from the center. Picture 9 also shows length expansion.
- Picture 10 shows the train right from the center. Picture 10 also shows length contraction.
When Picture 10 is selected you can see the train at the fartest right.
Reflection 1 - General
The most important message of the simulation is: that what you see (observe) at each instant is not the reality.
When Length Contraction is OFF and in the case of the round circle this means that you will not see the train at its real physical position, but retarded.
In the case of the "Race horse track" the observed length of the train changes as a function of the distance and is a function if the train is moving away or approaching you and also of the speed v.
- In all three simulations length contraction is an option.
This means that in all simulations (When Length Contraction = ON) that the length of the train becomes shorter as a function of the speed of the train i.e. lambda
- The question is if this is physical correct? Is this in agreement with actual experiments?
This means for simultion 2 i.e. the Race horse track:
The question is even more complicated: should there be both length contraction when the train moves in a straight line and in a circle, or is there only length contraction when the train moves in a straight line ?
- That in the out going leg that the observed length even becomes more smaller.
- That in the in going leg the observed length does not become as large. There is both length expansion and length contraction.
Reflection 2 - frequency & Doppler effect
However there is one more issue.
As part of the simulation the observed length of the train changes. Suppose the train emits a light with a certain frequency. What are the consequences with the observed frequency, if any.
- When the train moves in a circle, I do not expect any change
- When the train approaches the observer, the observed length increases. IMO the same will happen with the observed frequency. A change towards the red.
- When the train approaches the observer, the observed length decreases. IMO the same will happen with the observed frequency. A change towards the blue.
Reflection 3 - Length contraction
In this reflection different aspects of Length contraction are discussed.
3.1 Is Length contraction vissible?
The issue is more: Is it possible that length contraction is observed but that it is not physical? If that is the case length contraction is a vissible illusion.
The answer is: Yes. That is the whole purpose of the simulation. The observer observes that the length of the train is shorter as the actual length. The emphasis is on: observes. This happens when the train moves away from the observer and is a funtion of the speed of light.
However the reverse can also happen: the observer observes that the length of the train is longer then the actual length. This happens when the train approaches the observer.
Both effects can be demonstrated in the simulation 2 (Horse rack track) and 3 (Terrell rotation.
3.2 Is Length contraction physical?
In both simulations 2 and 3 it is possible to test physical length contraction by turning the parameter "Length contraction" on. But that does not answer the question if there exist physical length contraction. The only way to test that is by performing real experiments A thought experiment is not enough.
3.3 What is the explanation of Length contraction?
- The explanation of vissible Length contraction is because all what you see in the distance is something what happened in the past and all what you see (vissible) involves light. That is why the speed of light is the most important factor to understand vissible Length contraction and vissible Length expansion.
- The explanation of physical Length contraction should explain how, when the speed of the train increases, that its length decreases and that when the speed of the train decreases, that its length increases. This assumes that when the train is back at its initial position no length contraction can be detected.
Part of this whole discussion depents also on the concept rigid rod. The concept of
rigid rod seems to indicate that dependent about the material used the length of a rod can change as a function of speed. This also seems to indicate when we use a rigid rod or a rigid clock there is no physical length contraction involved.
A different problem with any train is that its behaviour depends about the position of the engine:
- When the engine is in front (in the direction of movement) there is length expansion.
- When the engine is in the back (i.e. a pushing effect) there is length contraction.
- When the engine is in the middle the length in total does not change.
Reflection 4 - How to demonstrate physical length contraction.
There are two approaches to demonstrate physical length contraction assuming the length of the train is l.
At the beginning of the experiment (v=0) all the clocks along the track should be synchronized such that they all show the same proper time.
In the standard approach is to place as many clocks as possible along the horse rack track in simulation 2, a distance l apart. The same can be done in simulation 1 and 3.
- a different approach is to place two clocks at the beginning at end of the train, but that is more to test time dilation or better the physical behaviour of a clock
The basic idea is that all clocks in the reference frame of the track (are at rest) and indicate the same time.
- In the case of simulation 1 synchronization can be performed with a synchronisation signal, starting at the center of the circle, towards all the clocks. When this signal reaches each clock the clock is reset. This works because the distance is the same.
(We assume, that the clocks are physical at rest.)
- In the case of simulation 3 (with a straight track) clock synchronization can be done as explained in:
- In the case of simulation 2 the easiest way is only to place clocks (equally spaced) along one straight leg.
As part of the experiment there are two observers at the beginning and end of the moving train. The whole experiment exists that each observer writes down, when his position coincides with a clock (at rest) the number of counts of the clock at rest.
At the end of the experiment both observers should compare their results.
All of this can only be decided by a real experiment.
In fact the same experiment should be performed in both directions.
- When the results are the same there is no physical length contraction.
- When the train moves towards the left and when there is physical length contraction,
the back of the train will first coincide with a clock then the front because the train has to move forward. That means the number of counts at the back will be lower as in the front.
- When the train moves towards the left and when there is physical length expansion,
the front of the train will first coincide with a clock then the back because the train has to move forward. That means the number of counts at the front will be lower as in the back.
Reflection 5 - Time dilation
Time is something that has to do with the existance of the Universe and with our existance.
Existance and the concept of time are inherent coupled together. They are inseparable.
The universe as a whole changes and evolves constantly. The same for our galaxy and the same for our planet, the earth.
Humans also change and for each individual we call, that he or she becomes older in time.
We could also consider that the Universe changes in time, what we mean then is some sort of universal time which defines the age for the whole of the universe. (Which came into existance at the moment of the Big Bang?)
In this reflection different aspects of Time dilation are discussed. Time dilation is closely related to the behaviour of clocks.
5.1 Is Time dilation vissible?
Time and Time dilation are not vissible. Time dilation is only vissible in as much time is linked to the physical behaviour of a clock.
5.2 Is Time dilation physical?
As written in the previous sentence: Time dilation is linked to the physical behaviour of a clock.
The problem is that there are many different types of clocks and all these different clocks behave differently. The strategy of course should be that all clocks should show the same time, always, under all conditions, but that is not that simple.
5.3 What is the explanation of Time dilation?
Each clock is a physical process and as such the behaviour of a clock is dependent about the mechanical and functional operation of a clock. This in turn can have consequences when the clock is moved compared with a clock which is not moved.
For example there are clocks, which operation is based on light signals. If you have two of these and the speed of these clocks is different relatif to the speed of light than the behaviour, its total number of counts, will be different.
What is important that this has nothing to do with the Universal age which increases lineair. It is the clock, which shows the age of the Universe, which should be used to describe the movements in our solar system, at global scale.
Reflection 6 - More to read
- To read more about the physical behaviour of clocks please read this document:
Clock and Centrifuge
This document discusses the behaviour of a clock (using light signals) in a linear accelerator and a centrifuge.
The bottom line is that all such clocks don't work properly.
Original 24 April 2013
Modified 25 Mai 2013
Modified 10 April 2014
Modified 25 April 2015
Modified 29 September 2017
Modified 1 Februari 2020
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