# Alcubierre drive

Two-dimensional visualization of the Alcubierre drive, showing the opposing regions of expanding and contracting spacetime that displace the central region. The Alcubierre drive or Alcubierre metric (referring to metric tensor) is a speculative idea based on a solution of Einstein's field equations in general relativity as proposed by theoretical physicist Miguel Alcubierre, by which a spacecraft could achieve faster-than-light travel if a configurable energy-density field lower than that of vacuum (i.e. negative mass) could be created. Rather than exceeding the speed of light within its local frame of reference, a spacecraft would traverse distances by contracting space in front of it and expanding space behind it, resulting in effective faster-than-light travel. History Alcubierre metric The Alcubierre metric defines the warp-drive spacetime. Mathematics of the Alcubierre drive where is a positive definite metric on each of the hypersurfaces. and with arbitrary parameters . Related:  Faster than Light Travel

Faster-than-light Faster-than-light (also superluminal or FTL) communications and travel refer to the propagation of information or matter faster than the speed of light. Under the special theory of relativity, a particle (that has rest mass) with subluminal velocity needs infinite energy to accelerate to the speed of light, although special relativity does not forbid the existence of particles that travel faster than light at all times (tachyons). On the other hand, what some physicists refer to as "apparent" or "effective" FTL[1][2][3][4] depends on the hypothesis that unusually distorted regions of spacetime might permit matter to reach distant locations in less time than light could in normal or undistorted spacetime. Although according to current theories matter is still required to travel subluminally with respect to the locally distorted spacetime region, apparent FTL is not excluded by general relativity. FTL travel of non-information Daily sky motion Light spots and shadows

Wormhole A wormhole, also known as an Einstein–Rosen bridge, is a hypothetical topological feature of spacetime that would fundamentally be a "shortcut" through spacetime. A wormhole is much like a tunnel with two ends each in separate points in spacetime. For a simplified notion of a wormhole, visualize space as a two-dimensional (2D) surface. In this case, a wormhole can be pictured as the 2D surface of a tube that connects different parts of the surface. The mouths of a wormhole are analogous to the holes at either end of the tube in a 2D plane. Researchers have no observational evidence for wormholes, but the equations of the theory of general relativity have valid solutions which contain wormholes. The American theoretical physicist John Archibald Wheeler coined the term wormhole in 1957; however, in 1921, the German mathematician Hermann Weyl already had proposed the wormhole theory, in connection with mass analysis of electromagnetic field energy.[12] Definition Time travel

The Warp Drive Could Become Science Fact A warp drive to achieve faster-than-light travel -- a concept popularized in television's Star Trek -- may not be as unrealistic as once thought, scientists say. A warp drive would manipulate space-time itself to move a starship, taking advantage of a loophole in the laws of physics that prevent anything from moving faster than light. A concept for a real-life warp drive was suggested in 1994 by Mexican physicist Miguel Alcubierre, however subsequent calculations found that such a device would require prohibitive amounts of energy. Now physicists say that adjustments can be made to the proposed warp drive that would enable it to run on significantly less energy, potentially bringing the idea back from the realm of science fiction into science. "There is hope," Harold "Sonny" White of NASA's Johnson Space Center said Friday (Sept. 14) at the 100 Year Starship Symposium, a meeting to discuss the challenges of interstellar spaceflight. Warping Spacetime

Mustafa's Space Drive: An Egyptian Student's Quantum Physics Invention Remember the name, because you might see it again: Aisha Mustafa, a 19-year-old Egyptian physics student, patented a new type of propulsion system for spacecraft that uses cutting edge quantum physics instead of thrusters. First, a little background: One of the strange quantum facts at work in Mustafa's engine idea is that there's no such thing as a vacuum, devoid of particles, waves, and energy. Instead the universe's supposedly empty spaces are filled with a roiling sea of particles and anti-particles that pop into existence, then annihilate each other in such a short space of time that you can't readily detect them. Mustafa invented a way of tapping this quantum effect via what's known as the dynamic Casimir effect. In terms of space propulsion, this is amazing. Aisha's invention is so promising that her university's staff aided with a patent application. [Image: Flickr user gordontarpley]

White–Juday warp-field interferometer Motivation for the experiment The NASA research team lead by Harold White and their university partners currently aim to experimentally evaluate several concepts, especially a redesigned energy-density topology as well as an implication of brane cosmology theory. If space actually were to be embedded in higher dimensions, the energy requirements could be decreased dramatically and a comparatively small energy density could already lead to a measurable (i.e. using an interferometer) curvature of spacetime.[1] The theoretical framework for the experiment dates back to work by Harold White from 2003 as well as work by White and Eric W. Davis from 2006 that was published in the AIP, where they also consider how baryonic matter could, at least mathematically, adopt characteristics of dark energy (see section below). Theoretical framework The metric derived by Alcubierre was mathematically motivated by the cosmological inflation. Interferometer experiment Results 

Faster than Light Travel Warp Drive More Possible Than Thought, Scientists Say HOUSTON — A warp drive to achieve faster-than-light travel — a concept popularized in television's Star Trek — may not be as unrealistic as once thought, scientists say. A warp drive would manipulate space-time itself to move a starship, taking advantage of a loophole in the laws of physics that prevent anything from moving faster than light. A concept for a real-life warp drive was suggested in 1994 by Mexican physicist Miguel Alcubierre; however, subsequent calculations found that such a device would require prohibitive amounts of energy. Now physicists say that adjustments can be made to the proposed warp drive that would enable it to run on significantly less energy, potentially bringing the idea back from the realm of science fiction into science. "There is hope," Harold "Sonny" White of NASA's Johnson Space Center said here Friday (Sept. 14) at the 100 Year Starship Symposium, a meeting to discuss the challenges of interstellar spaceflight. Warping space-time Laboratory tests

NASA’s NEXT ion drive breaks world record, will eventually power interplanetary missions Proving yet again that Star Trek was scarily prescient, NASA has announced that its NEXT ion drive — NASA’s Evolutionary Xenon Thruster — has operated continually for over 43,000 hours (five years). This is an important development, as ion thrusters are pegged as one of the best ways to power long-term deep-space missions to other planets and solar systems. With a proven life time of at least five years, NEXT engines just made a very big step towards powering NASA’s next-gen spacecraft. Ion thrusters work, as the name suggests, by firing ions (charged atoms or molecules) out of a nozzle at high speed (pictured above). A diagram of an electrostatic ion thruster (as in NASA’s NEXT, and most other ion thrusters) With such puny thrust, a NEXT-based ion drive would need to run for 10,000 hours — just over a year — to reach a suitable speed for space travel. Moving forward, it now remains to be seen if NASA will use the NEXT on an actual spacecraft. [Image credit]

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