Welcome back my friends!
from today, we're gonna start a new series which is called:
Physics homework
together we'll have 20 or perhaps even more online meetings like this... (30?)
and during these sessions 
We'll discuss about this book:
"Physics Told"
This will be like a guide to us , schrolling though all fundamental Pysics
Let's get stated!
we're all closed in homes for reasons that go beyound ourselves...
(Corona Virus spread quarantine measurements)
this souldn't stop us to keep studing though
what would happen, i thought i we'd do same pyshics lessons?
 You all know i've written this book: The Story Tale of Pshyscis
many of you have asked me to explain some ideas and parts of the book
or to discuss about some chapters from it
that's when i thought to discuss each chapter one by one
Allowing us to make 20 of maybe even 30 pyshics lessons
Here's how we shal proceed:
I will record the pysics lessons first
and i'm going to publish them on youtube
on the same day and the same time frame
meaning on Tuesday at eight o'clock P.M.
I won't be abble to do this always though
because sometimes i got a very busy schedule.
but when i will be available i shall let you know in advance.
After you'll get to see the pysics lesson, once it's available
namely: on Twesday evening at 8 P.M.
I invite you all to join our community on our discord channel
link above: www.discord.gg/presura
this discord channel is already known to some of you.
it is actually one of the biggest channels in ROMANIA  (has almost 5k members)
And apparently the biggest one in the world to deal with science and education
ON this discord channel, once you get in
you'll be able to ask me questions directly
when you open the Discord app
search the Audio channel
the discussions channel
and you will find me there
and you'll be abble to ask me questions about the latest lesson i posted
and of course i will answer even to other different kind of question if there's any
further more:
i will also broadcast a live streaming too
so that you could see me while i answer your questions
after that some of those questions will be recorded 
and i will upload them on the internet with their respective answers
before we start todays lesson of physics
i'd like to tell you a couple things about this book
as some of you may already know i've graduated 2 universities. 
I graduated first the Electrical Engineering specialty
and later i also graduated Pyshics too
simply because i liked physics very much
after that i went abroad where i got my P.H.D on the solid physics field
And right now i'm a researcher on a research facilty of a tech company
as you may see, once i graduated physics i got into the experimental field
both in PhD and in research I did a lot of experimental physics
Although i still conserve that nostalgic feeling of the theoretical physics
because... why did i want to study pshysics the first time?
i just wanted to understand, what world are we living in
how does it work?!
That's why i started to study physics in the first place
I discovered it was an incledibly amazing world!
and i wanted to ge to know more and more...
And thereby, even if i've been trained in the experimental physics field
i still kept on studying theoretical physics
i've even took some classes during my P.H.D
I've read books and done a lot of math
and this way i've got to discover this amazing wonder! whics is physics..
I compare the studying of physics with the climbing process of a moutain
The same way that climbing a mountain requires a lot of energy from you
The same kind of effort is also necessary with physics too. cause you need to know a lot of math
for example...
Mathematics is the language of nature
As Gallilei used to say.
i can say i got lucky because i got a very Good math teacher
Professor Dragos Constantinescu from the  Valcea Town...
And he has taught me to see math just like a puzzle
He taught me to play with math and to enjoy it
And that's why i've been very lucky cause i learned math in a funny way
and when during my Electrical University
i read the famous Richard Faynman's book
The modern Physics
which is full of equations... that's how i learned to solve those physics equations
And i enjoyed solving them
This way i got to discover physics through math
And this helped me during my career a lot
and also allowed me to understand...
The real properties of nature, meaning physics in the end
all this through the mathematical language.
This thing is pretty visible too in my book:  Physics Told
Those of you who have read my book...
you might have noticed that it contains a story part 
and also a dedicated math section as well
The mathematical sections are like a storyline
of my personal journey in physics using math
Because i din't get inspired to write this book
By readind other popular mainstream physics books
No, i only wrote this manual citing real physics courses
taking those courses, and doing all the math
being curios to see by myseld what are those relativity equations
Saying: look that's what they mean
what are the quatum fields equation? Here's what they mean etc...
So everytime i learned someting
first i did the math and then..
i tried to understand by myself what it also reprsents
Therefore this manual is actually an interpretation
of what i actually understood with my own mind from those equations
That's why i told you before that the study of physics is just like climbing a mountain
Once you get to read this book
or maybe you'll try to solve this book's equations
at the ending...
you may disover very advanced physics stuff
like the higgs boson that i mention on it
Somehow you'll find your self on the tip of a mountain
and from there you'll be able to see the world.
you may already know what's the view like on the top of a mountain.
You can see the rivers, the hills.. and all the houses
Therefore you've got an overall view of the whole picture
thats what it feels like whe you study physics and you manage to get through all the book
You reach the top of the mountain and there it just  feels like you meet Einstein
it's just like you're next to Einstein and you get to watch in his company
All this Greatness, all this beauty
That lies embedded in the great Universe where we live
Isn't that extraordinary?
Let's take this journey together!
My physics manual has over 20 chapters
and more than 600 pages
here you see the table of contents
Let's get a little bit through the content to realize what's in for us
The first chapter treats the subject of Astronomy
and we'll talk about it today.
The next chapter is about the fundamentals of quantum mechanics
We'll discuss things like the Force of Gravity and the Tide cycles
And many other things from Newton's classical  mechanics
Next it follows the Electricity and Magnetism
What is electricity and why do we take the shock?
Next there is the Electro-magnetism
The Electro-Magnetism is a Bigger Theory that unifies these two fenomena under a single frame
That's where we'll take the Maxwell equations in account
Next we'll move to the Theory of Relativity
because in reality the Electro-Magnetism is actually a gate toward Relativity.
That's how Einstein managed to develop his Theory
Once we move past this in the 5 Chapter... 
In the sixth chapter w'' discuss Einstein's first Theory
The Special Thoery of Relativity
We'll discuss about the Twins Paradox
Time Dilatation and Space Contraction
Extremely interesting things!
And later we'll get through the General Theory of Relativity
An even more complex Theory!
Where we'll see that the Space Curves Time.
Many many interesting Things!
On Chapter 8 i will discuss about the real implications about The General Theory of Relativity
In the modern Astronomy, like the Gravitational Waves 
The Cosmic Background Radiation
As much as we can fit into a single class
Each one of this topic is extremely Vast!
Then We'll continue with the Quantum Mechanics
What happens with that small objects?
How can they be present in more places at once? (Superposition)
What is their essence? 
I repeat Agan: i won't be abble to give very specific insights about it
But at least we'll get the Essence!
 next It follows modern Aspects of Quantum Mechanics
The principle of least dispense of action
and the classical Field Thoeries.
This is something that i still need to evaluate if we'll face these subjects 
Some very interesting Stuff from a Mathematical perspective
And very useful for those who may be interested into the math equations
We'll also discuss about the Quantum  Field Theories like:
Q.E.D : Quantum Electro Dynamics
And next: The consequences of the Q.E.D.
The physics of the Elementary Particles
What are those known Elementary particles? 
The Barions, Hadronds, Boson etc...
The Q.C.D : Quantum Chromo Dynamics
We're gonna find an amazing story on this subject: Q.C.D
How did scientist managed to figure out what protons are actually made of?
Because Protons are also made of other very small elementary particles called: Quarks
How did they  figure out that they have three color Charge?
Very beautiful!
Next it follows the Electro-weak interaction
Which Unifies the Electromagnetic Force with the Weak Force
And then i'm gonna be talking about some other more modern things
Current studies regarding the Physics of elementary particles.
We'll talk about Inflation, superSymmetry
Some parts of it at least, cause it's a pretty big subject still
And close to the end we'll inspect the Strings Theory
 
In its two variants.
With Fermions and without Fermions
The super String Theory
And Perhaps we'll finish with this chapter:
Physics of the common life and the Future!
We'll discuss how can we apply very advanced physics to the comong things around us
How can we make connections between reality and these physics principles 
The first Chapter is Titled: the Beginings of Astronomy
While the first section is: The language of nature and its limtations
It's actually a story about the insufficiency Theorem of Goeder (correct name?!)
And i wanted to treak this subject
Because i wanted to remind myself that as a limited Human been
I'm not sure if i will ever be able to fully comprehend the whole workings of the Univers
That's what (Goeder ?!) Teorem actually tells us
It tells us that if we take a mathematical system
And that mathematical System is right.
meaning there are no contradictions
It still cannot be complete Pay attention: Complete!
Therefore into that math system there's always gonna be a sentence
Which we can't find a proof for
And the thing is that math stand as the base of physics
In other words, some how, hidden into the physics
There should also be some hidden sentences (principles)
Which they cannot be demonstrated
In other words, we know for sure that today
On the current Date
That there are some questions out there
which we can't find an answer for!
This looks incredible to me! 
The second Section is called: The shape of the Earth
And actually from here till the end of the chapter..
I will talk about a thing that has really fascinated me
Where things that are really incredible:
How big is the Earth, how big is the Moon or how far is it
Have actually been discovered by the Ancient Greeks
2000 or even more, 2500+ years ago...
before modern Age
How was it possible?
Well the key to teir succes...
or even the key of physics and research
Is that you always have to look around the corner.
Imagine yourselves: we're here on Earth and we're able to look at the moon
Can we telljust by looking  how big is the Moon?
Well.. we can't really tell. The moon might be
Smaller and Closer to us... or it could be even bigger and farther away
That's what the section about "The shape of the Earth" is all about
How did the ancient Greeks realized  that the Earth
well it can be Dodged by light. Meaning it's not of infinit size
Because if you look at it on the surface you can see a hill and then another one...
It would look like it's just an infinite and Flat plane
Which is still a subject of discussion. [ Flat Earth :)) ]
Therefore how can we figure out if the Earth is finite?
Well there is a phenomena that we all get to see it
But which is not that obvious
Namely: The Sun's motion in the Sky
If we measure the Speed of this apparent motion
We''ll see that each hour, The Sun travels aproximatively 15 degrees
The apparent motion of the Sun in the Sky
In one day (24 hours)
we get approximatively 360 degrees
But as you know 360 degrees is actually the angle of a full Circle
Therefore it comes the next intuition:
Wait a sec: if the sun moves around with this speed for 24 Hours...
Then basically it should reach back the same position 
Maybe doesn't that suggest the sun's is actually circling the Earth?
in other Words: The Sun is high above.  Then in hides somewere underneath the Earth
It reaches the other side of the Earth
After which it rises the other way... And that's how it circles the Earth
So it must be
Because if we multiply 15 degrees with 25 hours
we'll actually get a fully 360 degrees circle
If the Earth can be circled around... how big is it?
how can i know this? :))
i mean you just gotta keep going an going
another horizont and still another one...
At that time the Ancient Greeks  had still not sailed around all the globe
In order to ble able to figure out how big it is was
So you do realize that in principle is very hard to find out how big is the Earth
Despite this... one of the ancient Greeks: Called Erastotene
he has actually measured the size of the earth!
we can see this on the picture: we can see the Earth
And on its surface there are 2 cities: Alexandria
A city which is btw in Africa
The north Africa
And Siene. which is a city that lies on the same meridian, but only further south.
Here we cand also see the Sun light beams
And we cand notice that if the Earth is actually round
The same way that Erastotene  presumed
Because he tough since the Earth can be circled this should be also the most optimal shape
And Also as Aristotele used to say: the circle is the most perfect shape
we can see the sun light beams
And we cand also notice how during the same period of the day
A stick lying in the ground in Syene, hasn't got any shadow
while the other stick, that's found in Alexandria, manifests a shadow
By calculating the size of the shadow in Alexandria 
and knowing the distance between the two cities
That's how Erastoene was able to calculate the radius of the Earth
Isn't that beautiful?
The Ancient greeks figured out that the Sun Circles the Earth
But the same way they also figured out that even the stars also circle the earth
The stars togheter with the whole celestial Vault
appear to be circling around the earth
We can see this in the night when we get out
we see the whole stars in the sky in a certain position
and later after 2 hours when we look back
you cand notice that all the stars have moved in place
And you cand notice this effect pretty well when you have a telescope
Usually those who buy a telescope for the first time
we point it toward a planet, to Jupiter for example
And we can observe Jupiter pretty well.
After which we'll go to our friends to tell them
quickly, came an see by yourseves how well you can observ the Jupiter planet through this telescope.
And you friends came to the telescope and guess what?
It's no longer there!
it's not! Because meanwhile the stars in the sky moved away a little bit.
And that's when we gotta adjust the telescope position in order to show them the Jupiter planet again.
Well the ancient greeks knew these kind of things
and there was the following problem:
Look: you only have 2 kind o possibilities in the end
Either the whole celestial vault (the sky) with stars and planets...
with all that it is, it moves around the Earth
Or either, as it would be more natural, others said..
The Earth rotates around it's own axis of rotation
because if the earth were to spin around its axis of rotation
while the Sky holds in a fixed position, we get he same effect
Apparently the motion is relative
Well today is a common information that the Earth spins around itself
And this thing has been accepted by physicians only around the years 1600
only with Gallilei
Why instead, why?
because nowadays we see it as the right way to be
The earth spins around its axis while the stars are fixed point in the sky
Why didn't the ancient greeks accepted this fact since the beginning
Why did they presume instead that the earth is still while the sky vault moves around it 
Many people claim this to be due to religious indoctrination
thinking they were indoctrinated, there was the medieval era...
and they were not allowed to think freely
That's not true. It has nothing what to do with that.
it has to do with another argument in science
because science was the one factor that actually didn't promote this argument
namely:
The greeks thought the following way:
If the earth spins around its own axis, then that means that on its surface
I'm actually travelling with a certain speed
How big is this speed? it cand be calculated...
And they did made some calculations
Resulting in about 1500 km/h
So they thought, what you mean, that we travel so fast at the surface of the earth?
That's not possible!
Well look what would happen if things were to be this way
Let's say that i thow an object from a tower
while the earth's surface travels ath 1500 km/h
well in that case, before reaching ground 
the earth keeps moving ahead leaving the ball somewhere behind
This motion distance for a tower 20 m in height
should result in 1 km back the tower
In other words if a drop a ball of a 20 m height tower
it should then fall 1 km back
Which is not what we observe in real life
The Ball falls in the same place (close to the tower)
So they came to the conclusion that this is a good logic
The world cannot rotate open itself
And that's how it ended. in conclusion it was scientist themselves who rejected the idea
Of course the change in tought came from scientists men  too, 1000 years later
That the truth was indeed the other way around. And that the earth spins around the Sun
Well then you might ask: how is this possible in the end?
if the earth spins then why does the ball doesn't fall 1 km back?
Well in this case this regards something that we call: Inertia conservation 
let me explain briefly
have you ever seen those movies of the WW2 ?
When the airplane drops the bombs
And when they were recorded from the airplane's inside
You can see the bombs dropping just straight down
on the other hand, if we look at the plane from a certain distance
we'll always see how the dropping bombs have a parabolig trajectory
Thus they travel..
They travel in the direction of movement almost tuned to the plane
Why? because despite us dropping them down the plane..
The bombs will also gain an almost instantaneous speed...
Into the direction of movement of the plane
The same principle is also valid when we drop the ball from the tower too
We might let the ball fall down while the earth travels with 1500 km/h
But in that instant the ball will gain the same speed too
of about 1500 km/h in the same direction
And basically it will fall tuned to our motion
thus here on Earth we have feeling that it falls right down to the ground
This is the corect answer that we found only 2000 years after the ancient greeks
The next section is about the moon's size 
And the distance of the Sun to the Earth
We already mentioned how hard it is to tell how big is the moon
The moon can be smaller and closer
Or bigger and further away, how could we determine this?
The answer is: let's look around the corner :)
Just like Aristarh did
On this picture you can see what was his logic
It's about the moon eclipse
During a moon eclipse, the Sun illuminates the earth while at the same time
the moon get's into the shadow of the earth, that's why it's not so visible
At the top you can see the original picture:
What Aristarh Thaught it was happening
while in the picture below you can see what it actually happens in reality
In both cases though, you can see that 
The moon gets through the shadow and it gets covered in it
And Aristarh was able to calculate how fast 
the moon travel between that shadow spaceso he realized in this case that moon
Can only be a couple times smaller than the earth
Since he knew the Earth has only about 6000 km in diameter
He was also able to determine the Moon's radius too
which is aproximatively about 1500 km in diameter
Now,  once we know how big is the moon
Can we also find out how big is the Sun too?
or how far away is it from us? of course...
 
We just have to look around the corner
but which corner?
Well the same corner that Aristacol from Samos looked at 
The same Aristacol
You can see the following picture
where the Sun the moon and the Earth form together at a given moment
they form a rectangular triangle
This is something that really happens in reality when the moon is on its first quarter
Because that's the moment when we'll see the moon to be lighted exactly in half
Just like in the picture..
On this rectangular Triangle we already know a side
which is the distance from the moon to the Earth
in order to solve the pitagorean Triangle as we learned at school
we need to know all the traingle sides
And since we know that the one angle has 90 degrees
we also need a second angle. And this is exactly the second angle that was measured by Aristacos
Naming, the angle between the Sun, the earth and the Moon
He observed the sky in that particular moment when the moon was at it's first quarter
Where's the moon? There it is!
And where's the Sun? look it's there in the Sky too..
What is the angle between them? well it gotta be approx 89 degreees...
Hmm let's put the values in our equations
he inserted them and that's how he calculated the distance between the Sun and the Earth
Of cours, this angle of approx 89 degrees is very hard to measure
because if that angle was of 90 degrees then the Rectangular triangle would be very elongate
And the measurement errors would be very huge
Anyway, he did some few mistakes but eventually he finally found the distance between the Sun and the earth
With a small uncertainty about a factor of 2 or 3...
The next three and the last sections of this chaper
are focused on the planetary model
In other words what's the motion of planets in the solar System
This stuff has been of an extremely importantce in the history of Physics
Because it was the basis of  Newton's work, And physics in general
And the big revolution in Physics actually
it started around the years of 1500
With Copernicus, with Galileo Galilei
When they discussed about that planetary system model
And in short here is the story too
My story begins with the experience of Tolemeu
He was an astronomer living about in the 100 years A.C.
Who had a particular interest ..
regarding the motion of the planets in the sky
so What are the planets?
If we take a look at the sky we shall see the stars
The same way the ancient greeks used to see them too
So again: all the stars move
around the earth in the celestial Vault
But to simplify we should return to our current model
Which describes the Earth as a spinning celestial  body
So according to this model, we spin on the Earth
Once every 24 hours pretty quick
While the Sky is static instead
If we're actually living in this physical model 
Then we must also understand that all the stars are placed in the same fixed position
Only that, among these special Constellations
There are some special Kind of "Stars"
Which the Greek School called them Planets!
Meaning moving stars. Why?
Because they displace themselves from one constellation to another
This argument is valid for The planet Mars for example
starting from one constellation and ending to another one and so on...
And this kind of motion is very special
because there are only a few bodies (planets) that exhibit this kind of behavior
This is something that remained in the Astrology
Why is that? well' you know too what i'm talking about
When where you born for example? - in that specific date... 
ah that is the arrow constellation! :)
and what planet lied in the arrow constellation when you were born?
- Well Jupiter Planet! ah, well then that's supposed to mean this and that... etc :))
Of course The Astrology has no scientific basis..
 
but the basic idea holds true: Planets move from one constellation to another
And Ptolemeus asked himself: what the deal with the planets motion? 
So he studied the topic pretty well
You can see in the picture the case of Mars
we can see the celestial Vault with the constellations
In the center there's once again the spinning Earth 
And we cand notice that the planet Mars
it moves from one constellation to another one, and it then returnes back
after a two years long period
furthermore the planet has also another motion which is called "Demote" (retrograde)
meaning that
that it moves forward after which it stops
it comes back into the constellation.... to lately still keeping moving in the same direction
What is the deal with this retro motion of the planets?
Actually what's is the motion of all the moving objects in the sky?
Because in the end even the Sun moves between the constellations
He drew all the Data on the paper.. and the result was the planetary model of Ptolemeus
Which you can visualise on this picture
what do we see on it? in essence we can distinguish the Earth
I repeat again, this is the self spinning model of the earth around its axis
Which it keeps rotating every 24 hours
in the distance we have the constellations
and among the constellation there's the motion of the planets
meaning the moving stars: Mars,  Saturn, Jupiter
And the Sun, cause it moves too though the constellations
The Sun takes around one year (according Ptolemeus model in the picture above)
Mars takes about 2 years and so one...
furthermore mars instead has even a Demote movement
its either forward and either backward
And Ptolemeu managed to describe this kind of demote motion with what he called:
Epicycle!
As we can see here the Epicycle representation (spiral)
So what did Ptolemeus did in the end? He took all planets
He placed them pretty well and he basically rebuilt
The whole solar System
Just like watchmaker does
And this way he described every planet
It may have an epicle, a given motion, how long it lasts and so on...
And tis model, this school of thought.. it has been used since the 1500 years
Around 1500 there came another astronomer
Whose name was Copernico
And Copernico was interested about the planes motion too
Only that he had an incredibly brave thought.
Incredibly crazy idea!
He took a look at the retrograded  Motion (Demote)
I think i can model this kind of demote motion in a completly different way!
Not by presuming that all the planets and stars move around the Earth
But the other way around. Including the Earth itself. (pay close attention)
Even the earth itself., they all rotate around the Sun
How's that?
Let's take a look on the following picture what Copernico actually did
The picture describes the demote motion taking the Mars planet in account
He claimed the following: 
The Earth is a planet too in reality, and it spins around the Sun
Pay attention: it rotates each years!  we don't mean the self spinning rotation of the Earth around itself (24 hrs)
but once a year the earth goes around the sun
Once every 2 years even Mars goes around the sun too
Except for Mars travels slower than the Earth
This is a common rule for planets which are more distant than the earth
That's what causes the Earth when it comes closer to Mars
To manifest a pretty weird behaviour
Meaning that while we're observing Mars, we cand see how it displaces forward...
Only that at a given moment, the earth comes close to mars
And given the Earth's bigger speed it overcomes it and...
For a very short time we "feel" like Mars goes Backwards
After which if we keep looking at Mars, we can observe how it moves forward instead still 
In other words, said Copernicus:
The demote motion is not a result of the Epicycle!
But it comes more as a result of the fact that planets spin around the Sun
Meaning that the earth is not in the center of the Universe!
That's where all the revolution Began in physics
What fascinates me the most instead, is something else
Because if you take a look at how well Copernicus managed to model the Theoretical Data
The experimental Data at that time did not fit pretty well to their undestanding. Just like Ptolemeus did.
In other words: this new model of Copernicus
Managed to explain the planetary system without bringing too much new experimental data 
Not very much scintifical evidence to sustain one model compared to the other one.
Despite this, Copernicus model instead was more simple and likely
Because as you see we can get the Epicyles out of the way
And in physics this is very important
Beause in physics usually it pervades the Occam principle
Razor Occam,  which says that:
If there are 2 things explaining reality
And they are very different, usually the right one is also the simplest
And this case
The Copernicus Model is more correct, Not necessarily for it's accuracy, rather than being simpler instead
The one who managed to model very well the planets orbits in the Sky
Was johannes kepler
johannes kepler lives approx around the years 1600
shortly after Copernicus
And he also had a partneship with a danish astronomer
Which was called Tycho Brahe
And the thing is that Tycho Brahe was a very reach man!
He even had an island of his own
They say than he was also kind of a Tiran on that island... btw.
But puting this aside...
He also managed to build the most advanced astronomical observatory of those times
You can see it on this picture
You may notice you cannot see any kind of telescope here
Because at that time they havent been discovered yet
You can see instead a pretty small hole on the left side, from the top
And we can see also the astronomer on the right side bellow
Which has to look at the stars through that small hole
To slide the machine on the main axis (down, up, right left)
And determinig this way the position of the stars
Or of the planets too
Because that's what Tycho Brahe Did. He measured the orbits of the planets with an unparalleled level of precision
After that though, he passed away
 
the respective data remained with Kepler
So Kepler thought: how could i check, how can i know
Which model is the real one Describing our planetary System?
Could it be the Ptolemeus one? Or could it be the Copernicus' one?
So he tried and strived the best to his abilities
He studied and gone through hell :)) studying all the pre-written math tables
Because at that time there were no calculators
He kept sliding through the math tables and comparing all data
Trying to match the information somehow
He kept doing that despite all failures..
Without any obvious result
Meanwhile he managed to figure out that the planets orbit
Is not that very Cicular as Copernicus  claimed
It not a Perfect circle. But it has to be an Ellipse
But what kind of mathematical shape is that? how can you describe it?
That's something he didn't know then
but after all his studies though the math tables he finally found a number
And that number was: 1.00429
and in that moment he had a flash
Wait, i've already met this number in another table!
He check quickly though the tables and he realized: the orbit must be an Ellipse!
The orbit mush be an Ellipse... So wat's the deal, What do i mean by that?
I only say that..
Scientist work very, very much on their field 
It's not true that you can have a touch of Genius, just like that
I mean, when kepler saw that number the first time (1.00429) 
He didn't know that the orbit should be an ellipse
He only had seen that number before in another table 
And this way he figured out using those tables..
That it should be an ellipse
That the way science work.
You work first a lot, without getting any idea, the first years, neither the second year, or the third...
And all of a sudden, you may remember  something you have already met many years before
And you put them all together
Well that's what Keppler did. 
And Keppler did this pretty well. He proved that the planet Mars orbit is actually an Ellipse
And btw, you can also draw an ellipsoidal shape too with a pencil
Using a thread just like in the picture
On which you can place the thread exactly between the two points, S and S' prime
 
The thread is pulled by a pencil
And then you can draw around the 2 points, an Ellipse
This is an Ellipse!
The Ellipse is actually the geometrical coordinate of those  2 points
Which have together a sum of their distances Always constant
Yeahh...
 
here we come at the end of this first lesson from our series: 
Physics at home!
On which we study together my whole physics manual
Where we discuss about all the fundamental physics
From quantum mechanics to the theory of relativity
If you liked it, i invite you to subscribe right now
There's a button bellow (hit the notification ring as well) 
Ahh, i also invite you to read my other second book 
A journey through the universe: Astrophysics told
Dedicated specially for Children above 10 years of age 
Or even Adults of course.
You can find me on Instagram or Facebook
And the most importantly: you can find me on disord
Here there's the program of our Discord Channel
www.discord.gg/presura
And be aware that every evening from 8 p.m.
We have a lot of discussions about many subjects
We'll always be there.
If you go to discord and acces the audio channel, and you find me there
You cand alwasy ask me questions, anytime
You're invited to participate to our discussions
Now instead, is the right moment to go to discord (Twestday 3/16 expired date)
Since i will log too on discord, i'm waiting for you there!
On my Audio channel, with questions regarding this precise physics lesson 
I'm gonna have an audio short broadcasting too
So that you can see me in live  (Almost every Tuestday at 20:00 GTM 2.0 Bucharest)
I'm wating to meet you there! :)
And don't forget: I'm gonna video tape some of the answers to your questions 
And you'll be able to see them on the next Video lesson (Next Twesday)
Your question has the change to be in my video next time
Let's get on discord! :)
