Hi, everybody. 
And welcome to the first lecture in our 
course Exploring Quantum Physics. 
Today, I will introduce the main 
formulation of quantum theory using 
Schrodinger. 
And I will also tell you a little bit 
about a fascinating history of the 
subject. 
But before going to this main part, I 
would like to talk about the process of 
learning quantum physics. 
And about why I think, so many people 
find it difficult and frustrating. 
And I hope that this brief discussion 
will help you avoid this frustration, and 
make the process of learning quantum 
physics here more effective. 
Richard Feynman doesn't really need an 
introduction. 
He was one of the heroes and legends in 
physics, universally recognized as a 
genius. 
He was also a great speaker and 
enthusiastic popularizer of physics. 
In 1979, he gave a series of very 
interesting lectures on quantum physics 
at the University of Auckland in New 
Zealand. 
They're actually available on YouTube 
online and I would encourage you to 
listen to them. 
If you do so, you will see that Feynman 
spends 30 or so, minutes in the beginning 
of his first lecture to prepare the 
audience for what they were going to hear 
next. 
In one of the main messages of this 
introductory part was that no matter what 
Feynman was to do, the audience wouldn't 
be able to understand Quantum Mechanics 
anyway. 
That he talks about physics students and 
physics professors and their level of 
understanding of Quantum Physics. 
Let's listen to what Feynman had to say 
in this regard. 
if I'm going to explain this theory, the 
question is, are you going to understand 
it? 
Will you understand the theory? 
When I tell you first that the first time 
we really thoroughly explain it to our 
own physics students is when they're in 
the third year graduate, graduate 
physics. 
Then, you think the answer is going to be 
no. 
And that's correct, you will not 
understand. 
 >> [LAUGH] . 
 >> But this business about not understanding 
is a very serious one that we have 
between a scientist and an audience. 
And I want to be at work with you, 
because I want to tell you something. 
The students do not understand it either. 
 >> [LAUGH]. 
 >> And that's because the professor doesn't 
understand. 
 >> [LAUGH]. 
 >> This is not a joke, but very interesting. 
 >> So, what Feynman seems to be saying is 
that nobody, not even professional 
physicists, not even himself perhaps, 
really understand quantum physics. 
Well, this is probably the last thing you 
want to hear before starting this course. 
But this is strictly not my intention to 
give you the impression that you should 
give up without even trying. 
On the contrary, I'd like to speculate 
what I think Feynmam might have meant 
there. 
But why I think so many people find it 
difficult to study quantum physics and 
other advanced physic subjects. 
And I hope that this discussion will help 
us further down the road when we 
encounter unusual counter intuitive 
quantum phenomena. 
Let us look at quantum mechanics from the 
perspective of all major physics theories 
out there. 
In this slide, I attempt to present all 
these theories in a single diagram, 
which, of course, is an unrealistic sort 
of silly task. 
And so, the result I should, I cannot, I 
shouldn't be taken too seriously. 
What we have here are three axis, 
labeling fundamental physics constants. 
So, here, I have an the inverse speed of 
light. 
this constant G is the gravity constant, 
which appears in the Newtonion gravity. 
And along the horizontal axis, I have the 
Planck constant. 
We show, as we show, c is the most 
important fundamental constant that 
appears in quantum mechanics and that it 
relates the particle and wave properties. 
Now, the red dots in this diagram 
represent, symbolically, major fields of 
physics. 
For example, on this line, I have two red 
dots. 
So, the one which has all, agree, 
responds to all physical constants being 
zero is just kinematics or classical 
mechanics. 
Essentially, 17th century physics. 
So this dot here, with the finite gravity 
constant, but all other constant. 
0 is the Newtonian Gravity. 
Now, moving up, the vertical axis, to the 
finite speed of light, brings us to a 
theory which takes into account this 
finite speed with which, with which 
interactions propagate. 
And this is the celebrated Special 
Relativity Theory of Einstein. 
Combining it with gravity results in 
General Relativity, another celebrated, 
another very famous geometric theory of 
Einstein. 
Finally, moving along the horizontal axis 
to find a Planck's constant, brings us 
to, actually, the subject of our course, 
non-relativistic quantum mechanics. 
So, the results of this part, which we 
are not going to discuss too much in this 
course, which combines the relativistic 
effects and the quantum mechanical 
effects. 
And this is, so called Quantum Field 
Theory or Quantum Electrodynamics. 
They are more complicated theory. 
Actually, I could have added here another 
dot which has all fundamental physics 
constants. 
This is this would be theory of 
everything. 
It doesn't really exist yet but everybody 
wants to get it. 
So, this has been one of the holy grails 
of physics for many years. 
Now going back to learning quantum 
physics and what does it all have to do 
with it. 
so let us discuss what theory governs our 
everyday lives. 
What is sort of our comfort zone? 
And I would claim that we are somewhere 
here in this area. 
Certainly, the life skills that we 
encounter in our everyday lives are much 
larger than atomic. 
The velocities are certainly much smaller 
than the speed of light. 
And well, we do experience gravity on a 
daily basis. 
So, we're somewhere here. 
And here is also where our intuition 
works. 
And if we say, we understand something, 
what we usually mean by that is that we 
can relate a phenomenon to another 
phenomenon that occurs here in this area. 
So, for example, if we were to say that 
we really understand quantum mechanical 
effect, it would often times imply that 
we would have found a way to relate it by 
something that we all ready know here. 
But the problem with all this advanced 
physics subjects, especially with quantum 
physics, is that such a mapping, such a 
relation is not always possible. 
In other words, it's not always possible 
to meaningfully project quantum 
mechanical phenomena on this classical 
axis. 
And if no classical analog exist, this is 
what we call strange. 
And this is what we find difficult. 
But on the other hand, if we were to 
imagine a fictitious civilization of tiny 
species that lived on atomic scales 
somewhere in this area. 
So, this guys would have had really a lot 
of problems understanding our classical 
work. 
So, the problem is not really with the 
quantum physics itself but with our 
centristic position on how we want to 
understand it. 
But now, how do[UKNOWN] quantum physics 
if we can't really regularly understand 
it at intuitive level. 
Fortunately, there is a way to do so. 
By speaking in common language of all 
physic theories, that is not rooted in 
and is independent of our classical 
world. 
And this is, of course, mathematical 
formalism that needs to be developed. 
And it may turn out that two seemly 
unrelated phenomena, lets say, on the 
classical side and on the quantum side, 
may be explained by similar differential 
equations or something like that. 
And by studying those, we can develop 
intuition about something which is 
otherwise, inaccessible to us. 
But after this discussion, you may ask, 
why bother studying quantum physics if 
it's not really relevant to our everyday 
lives? 
So, the modulation comes from 
experiments. 
And more recently, also from ecological 
advances that creates systems and 
devices, which operate further, on the 
right of this axis. 
The take home message here, is that when 
you study quantum physics or any other 
advanced physics subject, for this 
measure, you should actually be prepared 
to encounter phenomena that may appear 
bizarre at the first sight. 
And that you may find difficult to 
understand. 
When it does happen don't panic and 
certainly don't drop the course because 
of that, and don't assume that others 
find these things obvious. 
It's certainly not the case. 
so, I think the best way to understand 
such new concepts is first, understand 
experimental data that support them. 
And then, develop or understand a 
mathematical formalism and the proper 
theory that describes these phenomena. 
So, when you use this theory again and 
again, you will develop your own 
intuition and get the feeling about a 
deeper understanding of the subject. 
So, speaking about the mathematical side, 
so I should mention that of course 
quantum mechanics is a demanding subject. 
And it, we will have to use certain vast 
mathematical techniques. 
But there will be lectures with different 
sort of levels of mathematical 
sophistication. 
Some of them will be pretty advanced, 
some of them actually won't use much math 
at all. 
And so, I, I hope that all of you with, 
with different backgrounds in different 
levels of mathematical preparation will 
find something that is useful and 
interesting.