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NASA artist’s 1998 rendition of warp drive travel.
The ring around the spacecraft generates a negative-energy field. From today’s
perspective, the negative-energy field would no longer be necessary. Credit:
NASA; Digital art by Les Bossinas (Cortez III Service Corp)
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The warp engine of the Enterprise, Star Trek's starship,
could become a reality much sooner than we thought.
Or that is, at least, what is deduced from a recently
published work in 'Classical and Quantum Gravity' by a team of researchers from
the Applied Physics group , specialized in advising governments and companies
on scientific and technological issues.
In their study, the researchers openly announce the first
feasible model of a curvature motor, one based on the idea proposed more than
20 years ago by Mexican physicist Miguel Alcubierre , who has explicitly
endorsed the research.
"Many people in the field of science" - says
Alexey Bobrick, first author of the article - "are familiar with
Alcubierre's motor and believe that bending impulses are not possible in the
physical world due to the need to use negative energy. But this, however, is no
longer the case."
The Alcubierre engine, the starting point
In 1994, Miguel Alcubierre published in the same magazine
(Classical and Quantum Gravity) an ingenious solution to the equations of the
General Theory of Relativity.
Known since then as 'Alcubierre's metric', his idea allowed
a spacecraft to travel at more than 300,000 km / s , that is, faster than
light, but without violating any laws of Physics.
To achieve this, Alcubierre proposed that the ship travel
inside a space-time warp bubble. Behind the ship, spacetime would stretch,
pushing the bubble, while in front of it it would shrink, bringing the target
closer and closer.
The ship, inside the bubble, would remain immobile in a flat
space (not deformed) and would not therefore violate the law that prevents
traveling faster than light. It would be something like a person who stands
still on a conveyor belt that is moving at full speed.
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Photo. The graph shows a space-time warp bubble,
inside which (yellow) a ship would remain in flat space. The bubble would
expand the space behind the ship and compress it in front of it, allowing
high-speed travel - Gianni Martire (Applied Physics)
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In fact, the ship proposed by Alcubierre would be
transported by the bubble at superluminal speeds, but it would be space, and
not the ship, that would 'move' with its repeated dilations and contractions.
Relativity, in effect, prohibits any object from traveling
faster than light through spacetime, but it says nothing about the maximum
speed that spacetime itself can reach. With his idea, then, Alcubierre took a
great first step towards the famous 'bending motor' from the 'Star Trek' series
, which by the way, served as inspiration for his work.
The problem, however, is that in order to create the
space-time deformation bubble that provides the impulse, matter with negative
or exotic density would have to be used to obtain negative energy, which does
not exist, which leaves the Alcubierre engine totally outside our scope.
The more negative energy there is in the bubble, the greater
its speed of propagation, which would easily exceed that of light.
For those reasons, the physicist community had long since
discarded the engine proposed by Alcubierre, and the general idea was that
humanity would never build propulsion systems based on the warping of
space-time.
NASA itself, the researchers say, has been trying
unsuccessfully since 2012 to design physical deformation units at the
Eagleworks laboratories at the Johnson Space Center in Houston, Texas.
A solution without negative energy
But the new study has managed to avoid that problem. In
Bobrick's words: "We went in a different direction than NASA and other
researchers. Our research has shown that there are actually several more types
of bending momentum in General Relativity . In particular, we have formulated
new classes of curvature impulse solutions that do not require negative energy
and therefore can occur in the physical world."
Giving up the negative energy proposed by Alcubierre,
however, comes at a price in terms of speed.
The curvature motor proposed by the researchers, in effect,
“is subluminal and, in principle at least, can be built on the basis of
physical principles known to mankind today. It cannot exceed the speed of
light, but almost,” the researchers write.
In any case, they add, “We have shown that all the
criticisms of Alcubierre's famous motor are irrelevant because there is a whole
variety of other units of curvature that are physical, and that can be used.
Therefore, the Applied Physics team has shown that bending field mechanics is
not dead before birth, but is a viable physical science."