
English: 
What you're going to see
is a clip from one of Dr. Lewin's lectures.
There is a laser pointer and a slit.
And as you see, the laser pointer
is being projected on the screen.
You can see how the sides are getting cut,
As Dr. Lewin reduces the gap between the slits.
Exactly as you would expect it to.
But now, as the gap between the slits
decreases further,
things start getting weird.
The laser point starts
getting wider horizontally.
This is so nonintuitive as Dr. Lewin starts making the vertical
slits narrower and narrower.
The laser pointer just
keeps getting wider.
It's almost like magic.
Well, what you are seeing is
a fundamental principle of nature at work

English: 
What you're going to see
is a clip from one of Dr. Levin's lectures.
There is a laser pointer and a slit.
And as you see, the laser pointer
is being projected on the screen.
You can see how the sides are getting cut,
As Dr. Levin reduces the gap between the slits.
Exactly as you would expect it to.
But now, as the gap between the slits
decreases further,
things start getting weird.
The laser point starts
getting wider horizontally.
This is so nonintuitive as Dr. Levin starts making the vertical
slits narrower and narrower.
The laser pointer just
keeps getting wider.
It's almost like magic.
Well, what you are seeing is
a fundamental principle of nature at work

English: 
The Heisenberg uncertainty principle is
generally written as, Delta X times Delta P
is greater than or equal to H over four pi.
Well, What on earth is that supposed to mean?
Now it's basically talking about
the position
and the momentum of the particle.
X is the position of the particle
and P is its momentum.
Momentum is basically the quantity
of motion that an object has.
So now Delta X,
is the uncertainty in position.
While Delta P is
the uncertainty in its momentum.
If we were to multiply the two
uncertainties, then it must be
greater than or equal to H over 4 pi.
Now, H is really small.
So we generally do not observe
this principle in our daily lives.
But when we start looking at particles
like atoms or electrons or photons
like the ones that were being emitted
by the laser pointer,
that's when things get interesting.
When we were reducing the gap between

English: 
The Heisenberg uncertainty principle is
generally written as, Delta X times Delta P
is greater than or equal to H over four pi.
Well, What on earth is that supposed to mean?
Now it's basically talking about
the position
and the momentum of the particle.
X is the position of the particle
and P is its momentum.
Momentum is basically the quantity
of motion that an object has.
So now Delta X,
is the uncertainty in position.
While Delta P is
the uncertainty in its momentum.
If we were to multiply the two
uncertainties, then it must be
greater than or equal to H over 4 pi.
Now, H is really small.
So we generally do not observe
this principle in our daily lives.
But when we start looking at particles
like atoms or electrons or photons
like the ones that were being emitted
by the laser pointer,
that's when things get interesting.
When we were reducing the gap between

English: 
the two slits, we were basically
reducing Delta X for the photons.
And by reducing Delta X,
we were getting more and more precise
about where the photons
were passing through from.
In fact, we were getting so precise that
at a certain point we would break the,
uncertainty relationship,
and to stop that from happening.
The uncertainty in momentum along
the x axis has to go up.
And that's why,
the photons that were previously traveling
straight start drifting off towards the left
and towards the right
thereby creating an uncertainty
in momentum and ensuring
that the uncertainty relationship isn't broken.
You see what's going on here.
The more precise and more accurate your
measurement is of one quantity, the less
certain you can be about the other.
And that's the uncertainty principle.
Now, principles like this underlie
the core of quantum mechanics.
And it may seem strange and completely
non-intuitive, but it's the very
nature of our amazing universe.

English: 
the two slits, we were basically
reducing Delta X for the photons.
And by reducing Delta X,
we were getting more and more precise
about where the photons
were passing through from.
In fact, we were getting so precise that
at a certain point we would break the,
uncertainty relationship,
and to stop that from happening.
The uncertainty in momentum along
the x axis has to go up.
And that's why,
the photons that were previously traveling
straight start drifting off towards the left
and towards the right
thereby creating an uncertainty
in momentum and ensuring
that the uncertainty relationship isn't broken.
You see what's going on here.
The more precise and more accurate your
measurement is of one quantity, the less
certain you can be about the other.
And that's the uncertainty principle.
Now, principles like this underlie
the core of quantum mechanics.
And it may seem strange and completely
non-intuitive, but it's the very
nature of our amazing universe.
