- In science fiction,
one of the most powerful widely thing tools in battle
is the force field.
We've all seen them,
a transparent paper thin yet impenetrable field
that can be shaped and morphed into practically anything.
So with all the money that the military spends
on making new and advanced weapons,
you think they would invest in something
as powerful as a force field?
So why don't they exist?
Are they physically possible?
Well, if you're going to make a force field
you need a force.
Right now, there are four known forces of the universe,
gravity, the electromagnetic force
and the strong and weak nuclear forces.
But could any of them be used to make a force field?
First let's look at gravity,
the reliable force that keeps us from flying off the earth
that holds the solar system and the galaxy together.
Could we somehow mold gravity into a force field?
Well, gravity kind of has the exact opposite properties
of a force field.
A force field needs to repel things,
be ridiculously strong so that nothing can penetrate it
and be focused into a thin plane.
Gravity is an attractive force
and a pretty weak one at that.
The gravity of an entire planet
is counteracted every time you pick up a pencil.
It also works over large distances
and isn't easy to manipulate, especially into a thin plane.
So there's not much hope
of making gravity of force field.
Next, there's the electromagnetic force.
You know, the one that powers your PlayStation
and lets you watch cat videos.
It's a bit of a better option than gravity but not by far.
It can be repulsive
which is what you would want in a force field.
So it's got that going for it,
but it's completely useless against any insulating material
like rubber or plastic.
Also like gravity,
it can't really be focused into a thin plane.
So sorry, electromagnetic field,
you can't be a force field either.
The last two forces are the strong and weak nuclear forces.
The weak force is the force of radioactive decay.
It heats up the earth's core
and is responsible for volcanoes, earthquakes
and continental drift.
The strong force holds the nucleus of atoms together.
It gives energy to the sun and stars
effectively lighting up the entire universe.
So could either of these make a good force field?
Well, the problem is that
both nuclear forces are too short ranged.
They act over only a few nuclei
which makes them extremely difficult to manipulate.
In fact, the only way scientists have of manipulating them
are too low subatomic particles up in atom smashes
or to detonate atomic bombs.
So unfortunately they won't work as force fields either.
So if none of the forces could work as force fields
does that mean they are impossible?
The laws of physics simply won't allow it?
Well not quite, scientists have another lead.
The fourth state of matter.
The first three states of matter
are gases, liquids and solids
and the fourth is something called plasma.
We're not too familiar with plasma
because it's not very abundant on earth
but it's actually the most common form
of visible matter in the universe,
making up the sun, the stars and interstellar gas.
But what is it?
When you heat up a gas to extremely high temperatures
the electrons are torn away from their mother nucleus
because of all the extra energy they get from the heat.
Because the gas particles have lost electrons
they become positively charged
this new type of gas where the electrons are free
and the particles have charged, is called plasma.
Because of all the charged particles,
plasma can be influenced by an electromagnetic field
even being shaped into a thin plane
or what's known as a plasma window.
Plasma windows are currently used to weld metal
using electron beams
as they can separate vacuum from air.
They may not be force fields in the traditional sense
as they're not made of force,
but they mimic the properties of a force field pretty well.
We've already mentioned that they can be manipulated
so we could make any shape we wanted with a strong
and intricate enough electromagnetic fields.
They can separate air from vacuum
which means that in theory
we could have a spaceship made entirely out of plasma.
And importantly,
when plasma is heated to extremely high temperatures,
it becomes what's known as impermeable plasma.
It becomes very thick and matter has passing through it.
An impermeable paper thin, easily manipulated substance?
This sounds like a pretty good imitation force field,
so why aren't we using them?
Well, plasma only becomes impermeable
at extremely high temperatures.
I'm talking harder than the surface of the sun temperatures.
We have the technology to reach these temperatures
just not without using a huge amount of energy.
So plasma windows are usually only
about three feet high and one foot wide.
However, as technology improves,
it's not difficult to imagine bigger
and stronger plasma windows in the future.
But can a plasma window alone
ever really be enough to withstand
cannonballs, bullets and laser beams?
In science fiction force fields
are practically indestructible.
Could a plasma window ever really be indestructible?
Well famous physicist Michio Kaku
thinks that plasma windows on their own
may not be enough to live up
to the great expectation of force fields in science fiction,
but stacking on a couple of layers of other stuff,
might do the trick.
He imagines that
if we ever did have force field type things,
the top layer would be a supercharged plasma window
hot enough to vaporize metals.
The second layer would be a flat web
of high energy laser beams
vaporizing anything that made it through the plasma window.
And the third layer would a sheet of carbon nanotubes
only one atom thick
but 100 times stronger than steel.
At the moment carbon nanotubes
are only a few millimeters long
but Kaku expects that this will change
as technology improves over the years
and we'll be able to make shapes of any length we like.
This combination of plasma, lasers and carbon nanotubes
would truly be impenetrable to most forms of matter.
But, yes, there's still a but,
none of these layers would be any use against a laser beam,
being transparent and stopping light going through,
you don't really go hand in hand.
Unless one way this multilayered shield could stop a laser
is if one of the layers became partially opaque
upon sensing sufficient light intensity.
This technology kind of already exists.
It's called photo chromatics.
You know, there's glasses that look like regular glasses
but then when they're exposed to sunlight,
they turn into sunglasses?
That happens because there are molecules in the lenses
that can exist in two states.
In one state, the molecule is transparent
but when exposed to sunlight,
it changes to its opaque state blocking out the sun's rays.
However, at the moment, photo chromatics
that can stop a laser beam don't exist.
Right now the technology just isn't there
to do justice to the impressive force fields
we see in the movies
but Michio Kaku classifies force fields
as a type one impossibility.
That is impossible by today's technology,
but achievable he thinks within the next 100 years or so.
Of course, this is just one theory
and it's very difficult to make predictions
about the future.
There are obviously a lot of kinks to work out.
For example, if plasma becomes really thick
when will it become opaque?
And some of the things mentioned in this video
may be discovered to be impossible,
but they haven't yet.
So what do you think force fields, possible or impossible?
Thanks for watching guys.
This video was based on a chapter of the book
Physics of the Impossible by Michio Kaku
I've linked it in the description below
along with any other sources that I've used.
If you liked this video,
make sure to like this video and subscribe for more physics
and sometimes math. Bye