Alcubierre, Einstein, and Warp Drive
famous Canadian Science Fiction novelist
Mark A. Carter has reprinted an article here for your
edification written by
George Dvorsky for the The
Daily Explainer on 11/26/12. You should find it interesting.
NASA might build its very first warp drive
A few months
ago, physicist Harold White
stunned the aeronautics world when he announced that he and his
team at NASA had begun work
on the development of a faster-than-light
warp drive. His proposed design, an ingenious re-imagining
of an Alcubierre Drive, may
eventually result in an engine that can transport a spacecraft
to the nearest star in a matter of weeks - and all without violating
Einstein's law of relativity.
We contacted White at NASA
and asked him to explain how this real life
warp drive could actually work.
Vulcan command ship, as imagined in Star Trek, features
a warp engine similar to an Alcubierre Drive. Image copyright
© CBS Studios Inc. All Rights Reserved.
The idea came
to White while he was considering
a rather remarkable equation formulated by physicist
Miguel Alcubierre. In his
1994 paper titled, The
Warp Drive: Hyper-Fast Travel Within General Relativity,
Alcubierre suggested a mechanism by which
space-time could be warped
both in front of and behind a
Kaku dubbed Alcubierre's
notion a "passport to the universe." It takes advantage
of a quirk in the cosmological code that allows for the expansion
and contraction of space-time,
and could allow for hyper-fast
travel between interstellar destinations. Essentially, the empty
space behind a starship would be made to expand rapidly, pushing
the craft in a forward direction - passengers would perceive
it as movement despite the complete lack of acceleration.
speculates that such a drive could result in speeds that
could take a spacecraft to
Alpha Centauri in a mere
two weeks - even though the system is
4.3 light-years away.
to Alpha Centauri in a mere two weeks
travel is attained because it is space that moves, not the object.
In terms of the
engine's mechanics, a spheroid object would be placed between
two regions of space-time,
one expanding and one contracting. A
warp bubble would then be generated that moves
space-time around the object,
effectively repositioning it - the end result being
faster-than-light travel without the spheroid or spacecraft
having to move with respect to its local frame of reference.
nothing locally exceeds the speed of light, but space can expand
and contract at any speed," White
said. "However, space-time
is really stiff, so to create the expansion and contraction
effect in a useful manner in order for us to reach interstellar
destinations in reasonable time periods would require a lot of
And indeed, early
assessments published in the ensuing scientific literature suggested
horrific amounts of energy - basically equal to the
mass-energy of the planet
Jupiter or 317 Earth masses.
As a result, the idea was brushed aside as being far
too impractical. Even though nature allowed for a
warp drive, it looked like we would never be able to
build one ourselves.
said White, "based on
the analysis I did the last 18
months, there may be hope." The key, says
White, may be in altering the geometry of the
warp drive itself.
In October of
last year, White was preparing
for a talk he was to give for the
kickoff to the 100 Year Starship
project in Orlando, Florida.
As he was pulling together his overview on
space warp, he performed a sensitivity analysis for the
field equations, more out of curiosity than anything else."
My early results
suggested I had discovered something that was in the math all
along," he recalled. "I suddenly realized that if you
made the thickness of the negative vacuum energy ring larger
- like shifting from a belt shape to a donut shape - and oscillate
the warp bubble, you can greatly
reduce the energy required - perhaps making the idea plausible."
White had adjusted the shape
of Alcubierre's ring which
surrounded the spheroid from something that was a flat halo to
something that was thicker and curvier.
the results of his Alcubierre Drive
rethink a year later at the
100 Year Starship conference in
Atlanta where he highlighted his new optimization approaches
- a new design that could significantly reduce the amount of
exotic matter required. And
in fact, White says that the
warp drive could be powered
by a mass that's even less than that of the
Voyager 1 spacecraft.
That's a significant
change in calculations to say the least. The reduction in mass
from a Jupiter-sized planet
to an object that weighs a mere 1,600
pounds has completely reset
White's sense of plausibility - and
drive could be powered by a mass less than the Voyager 1 spacecraft.
plausibility is all fine and
well, of course. What White
needs now is a real-world
proof-of-concept. So he's
hit the lab and begun work on actual experiments.
a modified Michelson-Morley interferometer
- that allows us to measure microscopic
perturbations in space-time,"
he said. "In our case, we're attempting to make
one of the legs of the interferometer appear to be a different
length when we energize our test devices."
White and his colleagues are trying to simulate the
tweaked Alcubierre drive in miniature by using lasers
to perturb space-time by
one part in 10 million.
Of course, the
interferometer isn't something that
NASA would bolt onto a spaceship.
Rather, it's part of a larger scientific pursuit.
test device is implementing a ring of large potential energy
- what we observe as blue shifted relative to the lab frame -
by utilizing a ring of ceramic capacitors that are charged to
tens of thousands of volts," he told us. "We will increase
the fidelity of our test devices and continue to enhance the
sensitivity of the warp field interferometer
- eventually using devices to directly generate
negative vacuum energy."
He points out
that Casimir cavities, physical
forces that arise from a quantized
field, may represent a viable approach.
And it's through
these experiments, hopes White,
that NASA can go from the
theoretical to the practical.
for that Chicago Pile moment
Given just how
fantastic this all appears, we asked
White if he truly thinks a
warp-generating spacecraft might someday be constructed.
the field equations predict that this is possible, but it remains
to be seen if we could ever reduce this to practice."
White is waiting for is existence
of proof - what he's calling a
Chicago Pile moment - a reference to a great practical
1942, humanity activated the
first nuclear reactor in
Chicago generating a whopping
half Watt - not enough to power a light bulb," he
said. "However, just under one year later, we activated
a ~4MW reactor which is enough
to power a small town. Existence proof
Pile-1 photo courtesy of Wikipedia
Pile-1 (CP-1) was the world's first
nuclear reactor. The construction of
CP-1 was part of the Manhattan
Project, and was carried out by the Metallurgical Laboratory
at the University of Chicago.
It was built under the west stands of the original
Stagg Field. The first man-made self-sustaining
nuclear chain reaction was initiated in
CP-1 on 2 December 1942,
under the supervision of Enrico Fermi.
Fermi described the apparatus as "a crude pile of
black bricks and wooden timbers." Made of a large amount
of graphite and uranium, with "control rods" of cadmium,
indium, and silver, unlike subsequent reactors, it had no radiation
shield and no cooling system.
approach notwithstanding, White
did admit that a real-world warp drive
could create some fascinating possibilities for space
travel - and would certainly reset our sense of the vastness
of the cosmos.
loophole in general relativity
would allow us to go places really fast as measured by
both Earth observers, and observers on the ship - trips measured
in weeks or months as opposed to decades and centuries,"
But for now,
pursuit of this idea is very much in
science mode. "I'm not ready to discuss much beyond
the math and very controlled modest approaches in the lab,"
Which makes complete
sense to us, as well. But thanks to these preliminary efforts,
White has already done much
to instill a renewed sense of hope and excitement over the possibilities.
Faster-than-light travel may
await us yet.