Spaceships with warp drive can travel to just about any alien planet as easily as
we travel to anywhere in the world in a matter of hours. At maximum warp the
Enterprise from Star Trek, The Next Generation, can go nine thousand times
the speed of light. And if you think that's fast, the Millennium Falcon from
Star Wars can go nine million times the speed of light. By comparison, the fastest
man-made object, the Juno probe around Jupiter, goes a whopping 0.0002 times the
speed of light. this is still super fast by earthly standards - 46 miles or 74
kilometers per second, but at this rate it would take 20,000 years to reach the
nearest alien planet, Proxima Cenauri. If we had warp drive like the Enterprise,
we could make it a day trip - there and back in only nine hours. But isn't warp
drive all a bunch of science fiction fantasy? Isn't faster than light travel
forbidden by Einstein's Relativity. Well, it turns out there's a loophole. And to
be honest, before I started researching this subject, I thought this video was
going to be all tongue-in-cheek. But I was shocked at the volume of real
science that's been done in this subject. Turns out there are a lot of scientists
who've been inspired by Star Trek. And I think you're going to be shocked that
although warp drive is highly theoretical, it is based on some real
physics. How would such a warp drive work? And is it really plausible?
The unorthodox, crazy physics of the warp drive is coming up right now!
In 1994, Mexican physicists and Star Trek fan, Miguel Alcubierre, published a paper on
the warp drive while still a PhD student, and became instantly famous. How did he
figure this out? He did this by manipulating Einstein's equations of
General Relativity. This was a purely geometric manipulation. What you have to
understand is that general relativity, at its core, is about the geometry of
space-time. Einstein showed that gravity is a geometric warping of
space-time. By manipulating this geometry to look the way a warp field would look
for a spaceship, Alcubierre made the equations find an answer to the idea of
a warp drive, regardless of whether it was feasible or
whether other laws of physics would allow it. It was more of a thought
experiment. But his equations are mathematically consistent solutions to
Einstein's equations. And this is how Alcubierre's warp-drive would work:
Take a spaceship and put a bubble of space around it. If you can compress
space in front of the bubble, and expand space behind the bubble, then you can
make the bubble of space along with the spaceship move. This would be like riding
a wave on a surfboard. You're not moving on the surfboard, but
the surfboard is moving because it is being pushed by the wave. This is where
the loophole is an Einstein speed limit, that nothing can move faster than the
speed of light. This speed limit only applies to objects traveling within
space, not the movement of space itself. Space can move at any speed. So that
bubble of space, and Alcubierre geometric solution can move at any arbitrary speed,
theoretically even 9,000 times the speed of light. Alcubierre figured out a geometry
that would fold space in such a way that a ship would not move in its frame of
reference, but the space that it was resting on, would travel. But can space
really move at faster than light speed? Our observations seem to indeed
confirm this. For example, the space very far away from us at the edge of the
universe, is moving faster than the speed of light. Any light from galaxies or
stars in this space, is light that we will never see. In addition, as I showed
in the previous video, space inside the black hole's event horizon moves faster
than the speed of light. So this is a real phenomena and should not be
discounted. Let's look at out Alcubierre's warp drive more carefully, and what it is
doing to the space-time around the spaceship. Space is being expanded at
the back of the spaceship, and being contracted in front of it. Can space
expand and contract like this? Yes, space is allowed to do both. Space is
malleable according to general relativity. it can bend, stretch. Space is
contracting around you and Earth right now. That's what gravity is.
Similarly space can expand too. It's expanding right now on a cosmological
scale, because when you look through a telescope, you can see that faraway
galaxies are red shifted. The galaxies are not moving locally. It
means that the space between those galaxies and us is expanding. Alcubierre's
warp-drive creates a kind of bubble around the ship which is like the
surfboard. The ship's sits within the bubble, analogous to you standing on the
surfboard Your ship does not move within the
bubble itself, so Einstein's laws are not violated, but the bubble of space is
moving or carried by a kind of wave that is being created in space. So how would a
warp engine make space contract in front and expand in the back. This is not easy.
Space is a fairly stiff fabric on the order of this equation. C is the speed of
light to the fourth power, so this is a very large number. And to make space warp
locally, around a spaceship like this, requires a lot of mass, or its energy
equivalent via E=MC^2, densely concentrated around the
spaceship. And more importantly, this is not just regular mass or regular energy.
This is negative mass and negative energy, because in order to create
expansion of space you need some kind of anti-gravity. How do you get anti-gravity?
You need negative matter, or exotic matter. This is something that would
theoretically have negative gravity. The problem is negative matter is not known
to exist Note that negative matter is not anti
matter. Antimatter does not have negative gravity. It has positive gravity. It's
just like matter, except it has the opposite charge. So an antimatter proton
would have a negative charge, and an antimatter electron would have a
positive charge. Antimatter does exist. But this anti-gravity negative matter is
something completely different. It has never been detected. Imagine something
that weighs negative 1 kilogram. What does this mean? it may not even exist?
Now you could substitute the energy equivalent of negative matter, which is
negative energy. This comes from E= - MC^2.
But again, what the heck is negative energy? This is not the same as an
absence of energy. It is energy with a value less than zero, that would
theoretically create anti-gravity and allow you to expand space time. But
anti-gravity has never been seen in a lab. There's not a known distribution of
energy that can produce anti-gravity or negative mass. It has never been found in
any accelerator or observed in nature. Even Alcubierre called his
results "nonsensical." However, anti-gravity, negative mass, and negative energy are
not forbidden in Einstein's equations. Could this mean that if we are clever
enough, we could create it? Let's presume that we could. There is a group at NASA
called the "Advanced Propulsion Team," also known as "Eagleworks" who is working with
on this assumption, and they have even created an artist's rendering of what a
warp drive spaceship would look like. They even call it the "Enterprise."
Alcubierre's original warp bubble around a spaceship would have required a lot of
negative energy - the energy equivalent in fact, of all the mass in the universe! So
it was obviously not feasible. But further reworking of Alcubierre's
original concept by NASA physicist Harold White reduced the negative energy
requirement to the equivalent of about 700 kilograms, or 1500 pounds. This is
still a lot of energy - about a thousand hydrogen bombs worth, but may not be out
of the question, and makes the concept somewhat plausible.
If negative energy can be created how did dr. white make Alcubierre's engine go
from nonsensical to plausible? He did this by changing the shape of the warp
bubble around the ship to a torus, shaped somewhat like a doughnut, and by
oscillating the negative energy field. These changes, he said, not only makes the
warp field more efficient, but also makes space around the ship more pliable for
expansion and contraction. Dr. White's calculations show that a 10 meter
diameter ship could go at 10 times the speed of light. Now you might say, "why is
there torus around the ship?" the torus is what would create the negative energy
field around the ship. You would think that since space is expanding in the
back, you need the negative energy directed at the back of the ship. But if
you do the math what you find is that the negative energy is needed all around
the ship. That's why the ring in the concept renderings is around the
spaceship itself. White's team has even tested the feasibility of warping space
by doing a very small-scale tabletop test. They've attempted to slightly warp
the trajectory of a photon, changing the distance it travels over a fixed length.
The first test was done in 2013 and was "inconclusive." Tests by other teams have
shown that if such a device could be built, it could hypothetically work, but
perhaps not past the speed of light. But even achieving a speed of say 10%
the speed of light would be a huge breakthrough, because it would still be
50,000 times faster than the fastest speeds that we can achieve today. Is
negative energy even realistic? Some scientists have pointed to the Casimir
effect as displaying a kind of negative energy. This is a quantum mechanical
phenomenon that occurs when two conducting plates are brought very close
together, something on the order of 10 nanometers. When this is done, a certain
proportion of the virtual particle frequencies between the plates are
excluded, because not all frequencies will fit between the 10 nanometer space.
Whereas all frequencies will fit outside the plates. The pressure outside the
plates, thus, is greater than the pressure inside the plates. And this can be seen in
a physical attraction of the plates that brings them together. The sonic analog of
this is shown in this video. So the thought is that if the total vacuum
energy is 0, then this would mean that the energy between the plates must be
negative. Some scientists have proposed harnessing this negative energy of the
vacuum on a large scale. But this is flawed because while the energy between
the plates is less than the vacuum energy, it is not negative, it is still
positive. There is no negative curvature. This is not negative energy, and cannot
be harnessed to power our warp drive. So given the problems I talked about, is all
hope lost for the warp drive? Not quite! There is one observational phenomenon
that should give us hope that negative energy or antigravity may exist. The
observable universe is expanding at an accelerating rate. This is called Dark
Energy. See my video on that. We have no idea what it is, why it exists, or where
it comes from, but 70% of our universe is made of this dark energy. And this energy
behaves like anti-gravity, or negative energy. Essentially it is some kind of
energy or force that's pulling space apart. It's expanding space. Well,
expansion of space is precisely what we need to create a warp drive. Is it
possible that sometime in the future, if we can develop a better theoretical
understanding of dark energy, we can learn to harness its power, and use it
for the warp engine? Our universe is full of stuff. So we could potentially have a
near endless supply of it, if we knew what the heck it was, and how to
manipulate it. Some technologies are inspired by
mathematical equations. It took 40 years to go from E=MC^2 to the
first atomic bomb. In the past 20 years, the warp drive concept has gone from
impossible to plausible. Maybe in the next 20 years it can go from plausible
to possible? Maybe it can become reality given enough time, and given more thought-
provoking episodes of Star Trek, to inspire the next generation of
physicists? Yes, please!
Arvind Asha here. If you like our videos,
then consider subscribing. And ring the
bell so that you can be informed when we
upload more fascinating videos. We make one to two videos a week. We'll see you
in the next video!