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SCIENCE & SPIRITUALITY
Professor Federico Capasso: The Quantum Scientist - P2/2
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Wonderful viewers,
welcome to
Science and Spirituality.
On today’s episode,
we will be continuing
our discussion with
our featured scientist
from last week’s program
- Dr. Federico Capasso,
a Robert L. Wallace
Professor
of Applied Physics
at the Harvard School
of Engineering
and Applied Sciences
in the USA.
Over the years,
Professor Capasso has
become primarily known
for his pioneering work
on novel quantum devices
such as avalanche
photo-detectors,
which are light sensors
that process
optical communications
to electrical signals,
resonant tunneling diodes,
ultra-fast transistors,
quantum cascade lasers, and other
semiconductor devices.
Recently he made a splash
in the scientific world
when he and his
research team observed
a repulsive, instead of
the normally attractive,
quantum force from the
so-called Casimir effect.
A possible
future application
of this phenomenon is
the ability to make nano,
or extremely small,
objects levitate.
This new finding
was the cover story of
the January 2009 edition
of the prestigious
scientific journal “Nature”.
In an interview with
Supreme Master
Television, Dr. Capasso
explains more about
this important discovery.
Now let us
join the discussion.
In 1948,
there was a relatively
famous Dutch physicist
by the name of Casimir.
He had been working
with Niels Bohr
in Copenhagen,
world famous physicist.
And he was working then
at the Philips Research
Laboratories.
And there were
some data in the lab
they could not understand.
So, out of an interesting
chain of thinking,
Casimir, out of the blue,
came out to propose his
famous Casimir effect.
You take two metals;
there is no charge
on these two metals.
Two metals are
like my two hands.
Now we know that
if there is a positive
and negative charge
they attract each other.
If there is a same charge,
positive/positive,
they repel each other.
Now he said,
take two neutral metals,
put them close enough.
What does he mean
close enough? Hundred
nanometers distance.
So one nanometer,
one billionth of a meter.
Then he said,
quantum mechanics
tells you that they
will attract each other
even though
there is no charge.
When he proposed this,
some people were thinking,
“this sounds so crazy,”
and the math was
kind of very difficult.
But then he provided
a physical explanation.
In the old days
of classical mechanics,
a vacuum
was what remained if
you emptied a container
of all its particles and
lowered the temperature
down to absolute zero.
However,
the notion of a vacuum
has completely changed
with quantum physics -
as now we know that
the vacuum is not empty.
All fields, in particular
electromagnetic fields,
have fluctuations
even in a vacuum
with temperature
at absolute zero.
We call this
vacuum energy,
or zero point energy.
The force discovered
by Dr. Hendrik Casimir
is another example
of the spectacular
manifestation
of vacuum energy
fluctuations.
Professor Capasso next
discusses the Heisenberg
Uncertainty Principle
and links it
with vacuum energy
and Casmir effect.
In quantum mechanics,
there is not
a state of absolute rest.
So there is nothing
like an atom at rest,
a molecule at rest,
even if you are
at zero temperature,
and you can
go arbitrarily close
to a zero temperature
but never reach it.
There is an inherent motion
that will never stop,
no matter how you
actually cool the matter.
These metal plates,
if you look at one metal,
it’s true that
the charge is zero.
But in time, because of
this continuous motion
of the electrons,
we know that
metals have electrons
that are negatively
charged particles that
can move around freely.
And there is a background
of positive ions.
So the metal
is actually neutral.
But what happens is that
the electrons fluctuate
because of this motion.
So on these plates you
have charged fluctuation.
On the actual surface,
you might have
an imbalance of charge,
on one side of the plate
you might have a patch
of positive charge;
on this side
you might have a patch of
negative charge, right?
On the other plate
which is in front
I will find the
opposite side of charge.
I have positive here,
negative here.
Positive here where
there is negative here.
So, there is going to be a
small attraction, because
of this charge fluctuation.
And the fascinating thing
is, between
any microscopic objects,
these forces are
not only between metals.
If I take a book like this
and a book near here,
and put it very close,
there is going to be,
if I put them very close,
a similar force,
much weaker than
in the cases of metal.
So this is a universal force,
this Casimir force that is
between any macroscopic
or microscopic bodies,
starting from molecules,
going up
to macroscopic things.
When we return,
we’ll continue with the
amazing Casmir force,
which originates from
quantum fluctuations
or vacuum energy.
Welcome back to
Science and Spirituality
where we are exploring
the Casimir force.
Our guest today is
Professor Federico Capasso,
a Robert L. Wallace
Professor
of Applied Physics
at the Harvard School
of Engineering
and Applied Sciences.
The Casimir force is
an important factor
to consider when we try
to scale down machines
into such tools as
Micro Electromechanical
Systems (MEMS)
or even to nano-scale
mechanical systems.
The attractive Casimir
forces could make things
stick together
and possibly
jam the machinery.
Micro Electromechanical
Systems are typically
micrometer scale devices,
and are commonly used
in many industries.
This is a micromachine
that we made
at Bell Labs.
This was in 2000.
I just had heard so much
about the Casimir effect,
and said, “How am I
going to measure it?”
Simple!
I had my colleagues
at Bell Labs make for me
this Micro Electro
Mechanical System
(MEMS).
What is MEMS?
It’s important!
Absolutely! Your airbags.
I hope
you are never going
to have an accident.
But if all of a sudden crash
or to suddenly
stop your car,
the airbag pops out
and makes sure you don’t
get crushed against
your steering wheel.
And what controls this
is a MEMS device.
So MEMS are
in everyday life.
So essentially,
they are chips
that have mobile parts.
You see, this is a seesaw;
it is essentially made in
silicon, but it is all gold.
And then we got a sphere
which is metalized of gold.
Then we decide
to move the sphere
closer and closer
to this plate.
Now you see
this plate is designed
so it can rotate
around this axis, right?
And so now,
if I approach this here,
there will be
a Casimir force, an
attractive Casimir force.
So the sphere,
as it gets close,
will pull up, and you have
a seesaw effect, right?
So now, how do we
measure the force?
We show this force
kind of in a colorful way
by this here, by measuring
this tiny rotation angle.
This is an angle
which is less than
one millionth of a degree.
So we have to measure it
by very
sophisticated technique,
by electrical method.
So we measure
this Casimir force
between a gold sphere and
a metalized gold plate,
as we vary the distance
between the two.
And this is
the first part of the story.
Then, I started to think,
“Now,
if I change materials,
I change the shape,
and I can design
quantum fluctuation.”
Because
this quantum fluctuation
of metal matter depends
not on the material.
Say if you have
gold, silver,
other material changes,
they depend on the shape.
And they depend also
on what is between
the two materials.
So if you somehow
put a liquid between
the sphere and the plate,
things change.
Suppose you take
two metals and you
put them inside the fluid.
Now you have two metals
separated by fluid.
So this is shown here.
So we did an experiment.
Essentially, we lower
the sphere of gold
towards a gold plate
inside the fluid.
It is not important
what the fluid is.
In this case,
the Casimir force is
always an attractive force.
If you change the lower
plate from gold to silica.
Silica is like a
transparent glass; in fact,
it is used in chips all over.
It’s a very common
material, silica.
And you keep
the same liquid.
Now quantum mechanics
tells us that this force
becomes repulsive.
See, what we measured is
this repulsive force.
We did not demonstrate
yet quantum levitation,
but the editor and
the reviewers of “Nature”
were so excited about it
and they said,
“We want to put this
on every cover,
so you can also put
what you want to do next,
what your vision is.”
A type of levitation
many are familiar with
is magnetic levitation,
and superconductive
levitation forces
have already been
successfully applied in
high speed Maglev trains
in Europe and the Far East.
Now I cannot make
Maglev trains because
it is so weak, the force.
But this can be
very important
for nano-technology.
If you make chips
smaller and smaller
with mobile parts
and the parts become
closer and closer,
at some point
they can stick together
quantum mechanically.
Our vision is we can use
this quantum levitation
due to the
repulsive Casimir force
to keep parts away
from each other.
So if you like, the fluids
here are like a quantum
mechanical lubricant.
Super lubricant is
what some people
have called it.
So the idea is
we can use this subtle
quantum mechanics
due to fluctuation
to try to eliminate
static friction – stiction
– in future
nano-mechanical devices.
Our appreciation to you,
Dr. Capasso, for your
insight and vision and
for giving us an overview
of your research
on the intricacies
of the Casimir effect
and your development
of quantum devices.
We look forward to
more good news
as you and your team
explore the many wonders
in our universe.
Blessed viewers,
thank you for
your company today on
Science and Spirituality.
Coming up next is
Words of Wisdom,
after Noteworthy News.
Please stay tuned to
Supreme Master
Television for more
constructive programs.
We’ll see you next time.
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