In this chapter the title of this book is explained i.e. the meaning of the words:
In order to explain those words the following concepts are introduced:
In order to explain what "force" means and to make "force" visible the program BASIC is used.
The reality is everything around us: Our earth including all the human beings, the sun, the planets, all the stars i.e. the total universe. We are part of the reality.
The reality includes everything, (very) large or (very) small, visible and invisible for us.
The purpose of this book is:
When you want to describe the reality, you can start with a description of what you see i.e. you do observations. However we have to be careful: what we see is not a very accurate description of the reality.
For example: When a car moves away from an observer, the car seems to become smaller. When a car approaches an observer then the car seems to become larger. However when you are in the car, the size of the car stays the same. This means our eyes are not in all situations a very good tool to describe the reality; more is involved.
Our eyes are specific not a good tool when you stay in a fixed position. When you want to describe the reality you have to move around i.e. you have to move in space.
A description of the reality ,by doing observations, is the first step of understanding. However when we want to understand fully, more is involved.
When you observe the reality immediate two things become apparent:
First many things that we observe are or behave the same: An apple always falls down. Water always flows from high to law. Those general phenomena we call: basic facts or laws.
Secondly many (all?) phenomena don't happen all at once, but require one or
more actions to happen first i.e. those phenomena happen in a chain, one
after an other.
That what should happen first we call that the cause.
That what should happen next we call that the result.
For example: it does not rain suddenly out of a blue sky. First there are small clouds, then big ones and then finally it can start to rain.
For example: Before an apple falls from a tree, first you have to plant a sibling, then the sibling has to grow and become a tree, etc. etc.
The fact that things happen one after an other and or require that certain things have to happen first, means, that those facts are related to one other. To find those relations, means, to improve (to deepen) our understanding.
For example: You, I, we all human beings are part of a chain which already exists for at least 2 million years. In reality this chain is much longer and when this chain will end nobody knows. Each link in this chain (i.e. each human life) is one cycle, starting with birth and finishing with dead.
Understanding of the reality is important. When we understand that phenomena can happen as a chain of events, then, given certain facts we can predict what will happen in the future. If necessary we can then take appropriate actions to change what should happen i.e. change the future
When we describe the reality we describe what we see now i.e. at a certain moment from a specific location. But is that the reality with the emphasis on the.
As already explained before, if you want to describe the reality more accurate you have to move through space and describe at each position what you see. That means you should describe the reality independent of your position.
The same is true when time becomes involved: you should describe the reality independent also from your point in time.
In reality there is not one reality but there are many (millions) of realities but there is only one reality that you can call NOW. Each of those realities has a description. Each of those descriptions is a description of everything , the whole universe, at the same moment, completely independent of the observer. This is the first step.
For example: during the time that you read this you are moving your head from left to right. Each of the positions of your head represent one reality. At the same time ,which each position of your head, I am also doing something of which you are not aware and what you can not see. All of that belongs to the same reality.
In a second step you can describe what the observer sees, or how he or she is influenced.
The computer simulations as part of this book show the reality at one moment (i.e. one reality) independent of the observer.
Most simulations show how objects (stars or planets) move through space in two dimensions. Space is considered absolute.
For example: in case 5 objects are considered then at each calculation cycle five dots are shown. Each dot represents the real position of the object. The five dots together show all the positions at one moment (reality).
At the next calculation (five) new dots are shown. The (five) old dots are not cleared. When you do that you get a good idea how the objects move in time through space.
There is one problem with that approach and that is that sometimes all the objects move from the screen because all the objects have a certain base speed. To solve that, the display is centred around one object. As a result what you see is in the centre of the screen one fixed dot. One dot less new dots (four instead of five) are shown at each calculation cycle.
In case of a simulation of earth and moon the display will show the following: One fixed dot in the centre which represents the earth. One new dot which represents the real position of the moon relative to the earth.
If you want to see what an observer sees certain calculations or conversions are involved.
If the distance between the object and the observer are small then those conversions are simple. If the distance is large then those conversions are more complex because time has to be included. Time in this case means the time before you see something.
To explain this and to make this clear, is the major topic of this book.
The most important aspect of our every day live is change. It is more or less the spill of our existence. Every one has more or less a good idea what change is. When something changes it becomes and behaves different.
The weather changes every day i.e. is different as the day before, the previous hour etc. When you try to understand, you changes. When you try to convince some one else about your opinion, hopefully he or she will change. This all depends to what extend we are open for change.
When you read this book you change. Maybe while reading this book you start thinking. Maybe you will get difficulties to sleep. That is not the intention of this book.
There are many ways something can change.
The temperature of water can change. It can increase (become hotter) or decrease (become cooler)
When a train moves, its position along the track changes. When you walk on a square, your position changes. When you fly, your position in space changes
Many things change in similar ways. Water always flows from high to low i.e. always behaves the same and as such behaves normal. We also call that logical and common sense. Descriptions of the physical reality which behaves the same are called laws.
The reader of this book should become very careful when some one uses or whenever he or she reads the words:
You can call the use of alcohol "common sense", in order to have a good party. A much more critical approach, which first starts with a definition of what is: "a good party", will tell you, that there are many other ways to have a memorable occasion for all.
The most important reason why we all know that things can change is because we can remember what we have seen i.e. we have a memory. What is our memory ?
Our memory is a part of our brains. In our brain many activities take place. One of those activities is that we can store images of what we see in our brains.
For example: we can look at a clock.
Each time when you do that, you store in your brain a picture of this clock i.e. the position of the dials. That is not enough to explain change. You become your self aware of change when you start to compare those pictures. Then you realise that they are not identical but different: the position of the dials in each picture is different. That is when you become aware of change.
There are basically two ways in which things can change: fast and slow. A car can move fast or slow. You can walk fast or slow. However what really do we mean with fast and slow.
Throughout this book you will constantly see that we will ask ourselves the question: What does such and such (exactly) mean, i.e. we will try to describe things (objects) as accurate as possible.
When we describe change, we compare. When we compare, we compare the state, position or situation of an object. When we describe change we compare the state at two different moments. In order to make an accurate comparison those two different moments, or better the difference between the two moments, has to be identical.
For this we use a clock. A clock is a physical object which indicates the time.
In order to compare accurate we have to be sure that the clock always behaves identical. If it does not then we have a problem. This is one of topics of this book.
Suppose you have two clocks which always behave the same and always show the same time. At one day you take the second clock with you on a trip to outer space. When you return back home you compare the two clocks and you observe that there is a difference between the two. The question is: Which clock shows the right time?
To answer that question you must first define what means: the right time. Maybe both clocks, initially, before you started your trip, both did not show the right time.
Speed is a calculated number that indicates how fast (or slow) the position of an object changes.
Speed is the difference in position in a certain time interval.
Two concepts are important in the definition of speed:
Difference in position between the points A and B is the position of B minus the position of A. Or simple the distance between A and B.
Time interval from going from A to B is the time on the clock when you reach B minus the time on the clock when you left A.
For example: Suppose the distance between A and B is 100 km and you left A at 2 o'clock and you reached B at 3 o'clock then your speed was 100 km in one hour.
On the other hand if you reached B at 4 o'clock then your speed was 100 km in 2 hours or 50 km in one hour. Meaning you travelled slower.
The (average) speed v between two points A and B can be expressed in the following formula:
v12 = (s2 - s1) / (t2 - t1) (1.1)
= delta s / delta t
O--------------------A---------------------------B
s1,t1 s2,t2
O is the origin from which you make your measurements.
A is your start position
B is your end position
s1 is the distance from O to A
s2 is the distance from O to B
t1 is the time when you start your trip in A
t2 is the time when you reach the end of your trip in B
One of the more difficult questions is how does something get speed.
We all know that the Moon moves around the Earth and the Earth around the Sun. So both the Moon and the Earth have a certain speed. They seem to have this speed forever.
On the other hand we also know that if you want to move a ball you either have to kick the ball or you can throw the ball. What happens is that first the ball will move quickly, then slower and slower and finally the ball stops. This means the speed of the ball is not constant.
Acceleration is a calculated number which indicates how fast (or slow) the speed of an object changes.
Acceleration is the difference in speed in a time interval.
Two concepts are important in the definition of acceleration:
What do they mean ?
Difference in speed between two points A and B is the speed of B minus the speed of A.
Time interval is identical as discussed paragraph 4.0 i.e. time interval from going from A to B is the time on the clock when you reach B minus the time on the clock when you left A.
There are two possibilities:
When we give a kick against a ball the speed of the ball increases or the ball accelerates. After some time the speed of the ball decreases or the ball decelerates.
The acceleration a12 encountered between two points A and B can be expressed in the following formula:
a12 = (v2 - v1) / (t2 - t1) (1.2)
= delta v / delta t
O--------------------A---------------------------B
v1,t1 v2,t2
In the paragraph 4.0 the following question was raised: How does an object get speed. To raise the same question in a different way would be: How does the speed of an object change.
The answer of this question is: When the speed (direction of movement) of an object changes then forces (plural) are involved i.e. can be calculated.
When we apply a force (action) against an object the speed of that object increases (or decreases). The more force we apply the more its speed changes.
We can describe this mathematical in the following form:
F :: delta v (1.3)
The :: means is equivalent with. Delta v means a change in speed.
Because delta v is the same as acceleration we can also write (1.3) in the following form:
F :: a (1.4)
The above describes in words that if we apply a force (F) the acceleration (a) increases. It does not describe with how much.
To quantify the relation between force and acceleration we use the concept of mass. Mass is equivalent with what we common understand as the weight of the object. (In reality weight is force)
Equation (1.4) now becomes:
F = m * a (1.5)
In words equation (1.5) means: When I apply the same force to two different balls with the same mass then the acceleration of both balls will be identical. When I apply the same force to two different balls and one ball has twice the mass of the second ball then the acceleration of the first ball will be twice less (or half) the acceleration of the second ball.
When I apply to one ball twice as much force as to a second identical ball then the acceleration of the first will be twice as much as for the second ball.
Perform program BASIC.TXT
The important lesson of program BASIC is that when you apply a force the speed changes during the time that the force is active. If no force is applied then the speed is constant (or zero).
To get a better understanding of what force means it is easier to consider force as the property to move i.e. force is always something physical and "visible"
When you throw a ball against an other (same type of) ball then the first ball will stop rolling and the second ball will start to roll i.e. the property to move of the first ball will disappear and will be taken over (go to) by the second ball.
The same is true for the person who throws the first ball. The 'property to move of that person' will be reduced with the same amount as the 'property to move of the first ball' will be increased.
Return back to INDEX.TXT