Speed of Light Limit
Scientists have long believed nature has a speed limit. It's the speed of light -- 186,000 miles (299,300 kilometers) per second. And the principle that nothing can go faster would mean most science-fiction tales of interstellar travel are impossible. At that speed, it would take us many generations to reach even the closest galaxies. Now, however, physicists are coming closer to finding out how, in some situations, light may actually travel faster than that. And, there seems to be ways to theoretically circumvent the light speed barrier for purposes of interstellar travel - even within the framework of current physics.
articles & documents
Breaking the Light Speed Limit
Howstuffworks
Once thought to be unbreakable, the speed of light as set by the laws of physics has been exceeded in two recent experiments, according to a New York Times news report. R
Faster than a Speeding Light Wave
Physical Review Focus, 19 May 2000
The starship Enterprise routinely flies faster than light, but of course, nothing really goes that fast. Well, almost nothing. Physicists have been concocting light pulses that do travel faster than c (the speed of light in a vacuum) for almost two decades, although none of the experiments could be used to send information that fast, according to most physicists. The latest demonstration, described in the 22 May PRL, may be the most dramatic, as it dispenses with some of the complexities of most other experiments. R
Faster-than-Light Laser Pulses?
John G. Cramer, Department of Physics, University of Washington
Can c, the speed limit of the universe, the speed of light in vacuum, be exceeded? In July, 2000, the science-oriented news media were full of reports that pulses of laser light had broken the speed-of-light barrier. R
How to travel faster than light?
Richard Milton, Alternative Science
In his long and distinguished career, Arthur C Clarke has had a disconcerting habit of thinking of things first, that others dismiss as nonsense. Now, in his latest prophetic work "3001: The Final Odyssey" -- looking forward to the next millennium -- Clarke may well have done it again, this time by giving a simple five-letter name to a fictional propulsion unit -- the "SHARP Drive". R
Inconstant Speed of Light May Debunk Einstein
Reuters, August 7, 2002 (news article)
A team of Australian scientists has proposed that the speed of light may not be a constant, a revolutionary idea that could unseat one of the most cherished laws of modern physics -- Einstein's theory of relativity. R
Is Light-Speed in Your Future?
Wired News, June 11, 1999
Star Trek fans longing to travel at warp factor 9, take heart: New research indicates that travel faster than the speed of light is theoretically possible. R
Light can break its own speed limit, researchers say
Associated Press, July 20, 2000 (news article)
Scientists have apparently broken the universe's speed limit. For generations, physicists believed there is nothing faster than light moving through a vacuum -- a speed of 186,000 miles per second. But in an experiment in Princeton, New Jersey, physicists sent a pulse of laser light through cesium vapor so quickly that it left the chamber before it had even finished entering. R
Light Exceeds Its Own Speed Limit - Or Does It?
New York Times, May 30, 2000
The speed at which light travels through a vacuum, about 186,000 miles per second, is enshrined in physics lore as a universal speed limit. Nothing can travel faster than that speed, according freshman textbooks and conversation at sophisticated wine bars; Einstein's theory of relativity would crumble, theoretical physics would fall into disarray, if anything could. Two new experiments have demonstrated how wrong that comfortable wisdom is. R
Light pulses flout sacrosanct speed limit
Science News, Vol. 157, No. 24, June 10, 2000
Five years ago, a wave of discontent swept away the 55-mile-per-hour U.S. speed limit. Nowadays, some physicists are taking a hard look at the 670-million-miles-per-hour speed limit of light in a vacuum, or c. R
Observation of Superluminal Behaviors in Wave Propagation (purchase required)
D. Mugnai, A. Ranfagni, and R. Ruggeri - Physical Review Letters, May 22, 2000, Vol. 84, Issue 21
Physicists have been concocting light pulses that travel faster than c (the speed of light in a vacuum) for almost two decades, although none of the experiments could be used to send information that fast, according to most physicists. The latest demonstration, described in the 22 May PRL, may be the most dramatic, as it dispenses with some of the complexities of most other experiments: The light pulses travel through free space--not a highly absorbing material--and their superluminal (faster than light) feat covers a distance of 30 wavelengths, much farther than in any previous work.
Scientists Claim To Break Speed-of-Light Barrier
Space.com, July 19, 2000
If zooming beyond the local speed limit is punishable by law, then some scientists may have a gargantuan speeding ticket to pay. In a controversial experiment reported in this week’s journal Nature, scientists at the NEC Research Institute in Princeton, New Jersey claim to have broken the ultimate speed limit -- the speed of light. Though hotly contested, some say this achievement could dramatically increase the speeds at which we can send and receive information. R
Scientists Try to Prove a Higher Speed of Light
Space.com, May 30, 2000
Scientists have long believed nature has a speed limit. It's the speed of light -- 186,000 miles (299,300 kilometers) per second. And the principle that nothing can go faster would mean most science-fiction tales of interstellar travel are impossible. At that speed, it would take us many generations to reach even the closest galaxies. Now, however, physicists are coming closer to finding out how, in some situations, light may actually travel faster than that. R
SETI, the Velocity-of-Light Limitation, and the Alcubierre Warp Drive
H.E. Puthoff, Ph.D. - Physics Essays, Vol. 9, No. 1, pp. 156-158, 1996
Alcubierre's recent "warp drive" analysis within the context of general relativistic dynamics, indicates the naivete of the assumption of impossibility of faster-than-light-speed travel. We show here that Alcubierre's result is a particular case of a broad, general approach that might loosely be called "metric engineering," the details of which provide yet further support for the concept that reduced-time interstellar travel, either by advanced extraterrestrial civilizations at present or ourselves in the future, is not, as naive consideration might hold, fundamentally constrained by physical principles. R
SpaceTime Hypersurfing
Michael Szpir, American Scientist, Vol. 82
In some future history, 1994 may be remembered as the year that the warp drive was first conceived to be a physical possibility. Long a cliche' of science- fiction writing, the warp drive has transported countless fictional characters through light-years of interstellar space in the time it takes for you or me to travel to the market. Unfortunately for real-world travelers, the warp drive has always been thought to be inconsistent with the laws of physics. But all this has changed. R
Speed Of Light May Not Be Constant, Physicist Suggests
ScienceDaily, Oct. 6, 1999
A University of Toronto professor believes that one of the most sacrosanct rules of 20th-century science -- that the speed of light has always been the same - is wrong. R
Speed of Light, Other Constants May Change
Space.com, 15 August 2001
The speed of light and other fixed numbers (called constants) that scientists rely on to explain the universe and its formation mathematically may not be so constant, according to a new study conducted by an international team of researchers. The research was met with caution by many scientists, who also said that if it is accurate, then the adjustment to theories would be significant and far-reaching. R
Taking A Shot At Einstein
U.S. News & World Report, May 26, 2003
Seeking a grander theory, rebel physicists break a cosmic speed limit. As we near the end of our first century in a relative universe, challenges to Einstein's theory are in the air. R
The Alcubierre Warp Drive
John G. Cramer, Analog Science Fiction and Fact Magazine, 1996
An overview and exploration of Alcubierre's work and its implications. Two years ago Alcubierre published a remarkable paper which grew from his work in general relativity, the current "standard model" for space-time and gravitation. His paper describes a very unusual solution to Einstein's equations of general relativity, described in the title as a "warp drive", and in the abstract as "a modification of space time in a way that allows a space ship to travel at an arbitrarily large speed". R
The Speed of Light - A Limit on Principle?
Laro Schatzer
A physicist's view on an old controversy. Contemporary physics states that no object should be able to travel faster than the speed of light. Although the value of c appears to be enormous when compared with conventional traveling speeds, it suggests a limit which renders a practical realization of interstellar travel improbable. Surely, the question remains: Are faster-than-light speeds possible? At the present time most scientists believe that the correct answer should be "no". However, it has to be emphasized that there is no definite proof for this claim. R
The Speed-of-Light-Limit Argument
Bernard Haisch, Ph.D.
The Leading Theory-Based Rejectionist Argument (which we all know). The speed of light is a universal upper limit. Distances between stars range from 4.3 light years to Alpha Centauri to a hundred thousand light years across the Milky Way galaxy to millions of light years between galaxies. These facts are incompatible with tens of thousands of apparent visitations. R
The Warp Drive: Hyper-Fast Travel Within General Relativity (PDF format)
Miguel Alcubierre, Classical and Quantum Gravity, 11 (1994), L73-L77
It is shown how, within the framework of general relativity and without the introduction of wormholes, it is possible to modify a spacetime in a way that allows a spaceship to travel with an arbitrarily large speed. By a purely local expansion of spacetime behind the spaceship and an opposite contraction in front of it, motion faster than the speed of light as seen by observers outside the disturbed region is possible. The resulting distortion is reminiscent of the `warp drive' of science fiction. However, just as happens with wormholes, exotic matter will be needed in order to generate a distortion of spacetime like the one discussed here.
