reports that scientists at NASA are working on an experiment to demonstrate the practical possibility of faster-than-light travel.
Einstein's special theory of relativity (SR)
implies that no massive body, that is a body with a nonzero rest mass, can ever travel at or faster than the speed of light. Accelerating a massive body to the speed of light will require infinite energy because, according to SR, the mass of a body moving at the speed of light would be infinite.
However, physicist Miguel Alcubierre
suggested that there is a way around the absolute barrier of the speed of light in Einstein's general theory of relativity
Alcubierre thought it might be possible to travel faster than light by making space, rather than the massive body, "move."
Unlike massive objects, space does not have mass and general relatively shows that it is flexible, that is, it can be made to bend or change shape like an elastic band or trampoline under the influence of gravitational forces exerted by massive objects. Besides, it is known that space has been expanding since the Big Bang
, an idea first intimated to astrophysicists who observed the Doppler redshifting
of the wavelengths of electromagnetic radiation in the visible spectrum (light) reaching us from distant stars, as opposed to blueshift which suggests a source of light approaching us.
The observations have led to astrophysicists talking of a space "fabric" which is pictured as stretching out as the universe expands and which, like an elastic band, may literally snap at a point in which cosmic mass is too thinly distributed for gravitational forces that hold the universe together to act.
Based on the facts above, Alcubierre, in a paper published in 1994, titled "The Warp Drive: Hyper-fast travel within general relativity,"
postulated that a loophole in general relativity could make it possible to "break the light barrier" by other means.
The Alcubierre drive or Alcubierre metric
, based on a solution of Einstein's field equations for general relativity, suggests that it could be possible to achieve faster-than-light travel if negative mass
can be achieved. So rather than exceeding the speed of light within a local frame of reference, the spaceship moves from a point in space to another by making the space ahead to contract while the space behind expands. Note that the ship itself never travels faster than light at any time, rather the ship is in what Alcubierre described as a "warp bubble."
Expressing the idea in more graphic terms, what is involved is changing the geometry of space
by generating waves which cause a contracting distortion in the "fabric" ahead of the spacecraft while stretching or expanding the "space fabric" behind the spacecraft. The spaceship then literally "rides the wave" in a region of space termed the "warp bubble." Note again, the spacecraft does not move in the bubble but like a surfer, it is carried along as the region of space moves due to the action of its drive.
According to TechNewsDaily
, Alcubierre's warp drive theory was used in the 1990s Star Trek TV series: "Star Trek: The Next Generation."
reports that physicist Harold "Sonny" White and a team of researchers at NASA's Johnson Space Center
in Texas are investigating the possibility of creating an artificial "warp bubble." as the first necessary step to a practical warp drive.
Alcubierre's theory suggests that a warp bubble may be created using the principle underlying the Casmir effect. Digital Journal
explains that the Casmir effect is based on the principle that in spite of appearances, space is not vacuum but a seething cauldron of fundamental particle interactions involving creation and destruction of "virtual particles."
According to Digital Journal
, the Casmir effect
suggests it is possible to use vacuum energy fields
to create propulsion and build spacecraft propulsion systems that need little or no fuel to travel in space.
According to TechNewsDaily
, Alcubierre suggested that it could be possible to use energy created in a vacuum, that is, negative energy, to distort the fabric of spacetime and create a "warp bubble."
Theoretical physicists note that although Alcubierre's metric is valid in mathematical terms and consistent with Einstein's field equations
, it does not follow that the principle could ever find practical application for creating "warp drives," primarily because its requirement of negative energy implies some form of exotic matter that has never been demonstrated to exist, although some theoretical models suggest it.
White and his colleagues
are investigating the possibility of generating a spacetime distortion in a field of negative energy in the laboratory. To test whether a warp bubble has been created they shine two precise lasers, the first through the site of the vacuum and the other through ordinary space.
The scientists then compare the two beams to see if the wavelengths of the one going through the vacuum is lengthened or "red shifted" in a manner that implies that the vacuum is stretched and thus harbors a "warp bubble."
The technical difficulties the team is facing, according to TechNewsDaily
, arises from the fact that the experimental setup is so delicately fine-tuned that even the tiniest seismic motion of the earth can disrupt the system.
reports that White is optimistic they will get results but will not commit himself to a time frame.