Sunday, May 14, 2006

How warp drive works

"The Warp Drive
Kris Holland

In front of the bubble, space contracts, decreasing the distance to the destination. In back, space expands, increasing the distance from the departure point."

Yes, this is standard picture for w = -1 zero point vacuum energy neglecting boundary effects for now:
/\ > 0 expands space and creates a universal blue shift.
/\ < 0 contracts space and creates a universal red shift.
This is the "reverse Doppler shift" (B. Cornet)

"The Warp Drive
In a rush to flee the solar system? Scientists have an interstellar travel plan, but it entails a brief stint outside the known universe

By Gregory Mone
Popular Science
May 2006

What: A spacecraft that travels at faster-than-light speeds by distorting, or “warping,” the fabric of spacetime. Instead of trying to move through space, the warp drive moves space itself. The ship sits inside a bubble of spacetime bound by a negative energy field that races across the cosmos.

Why: Chemical and nuclear propulsion, solar sails and ion thrusters all are too slow to reach the nearest star systems within a human life span. At faster-than-light speed (more than 186,000 miles per second), a warp-drive ship would travel 4.5 light-years to Alpha Centauri, the closest sun to our own, in about four years.

Who: This warp-bubble model is based on thought experiments conducted by theoretical physicist Miguel Alcubierre of the National Autonomous University of Mexico, theoretical physicist Chris Van Den Broeck of Cardiff University in Wales and, most recently, by mathematician José Natário of the Higher Institute of Technology in Lisbon, Portugal.

Where: For now, warp drive exists only in science fiction.

When: Figure on some point between the distant future and never. Theoretical research continues to advance, but there's no launch date in sight.

How To Pilot a Warp Ship:

Fuel Up: Start beyond Earth's immediate gravitational pull. Convert matter into negative energy (particles with negative mass that are repelled by gravity rather than attracted to it).
Curve Spacetime: Emit pulses of negative energy to curve spacetime. Form a sphere around the ship with the energy, insulating passengers in their own private spacetime bubble.
Drop Out: The bubble warps spacetime so drastically that it actually slips out of the visible universe. Only a narrow tube of negative energy keeps it tied to our world.
Expand Space: Now that the craft is protected in its spacetime bubble, the real work can begin: Expand space behind the bubble at faster-than-light speed, and shrink the space in front.

The Warp Drive To-Do List
A few not-so-minor challenges you'll need to tackle before takeoff
Discover Negative Energy: There are no known particles with negative mass. The closest scientists have come is a phenomenon called the Casimir effect, wherein empty space between two conducting plates behaves as if it contains negative energy."

There is confusion on this. The above is only for w > -1/3. For w < -1/3 it's the opposite. Zero point vacuum energy has w = -1 neglecting boundary plate effects.

"Devise a Way To Manipulate It: Even if scientists could transform matter into negative energy, they would still have to find a way to focus it and create an infinitesimally thin, yet extraordinarily stable, bubble of the stuff around the spaceship.
Harness Dark Energy: In recent years, cosmologists have been studying a mysterious force called dark energy that they think is accelerating the expansion of the universe. If scientists could generate it at the back of the bubble, it might move, or expand, space."

/\ = |/\|cos(2piMagnetic Flux/Flux Quantum)

"Build Bubble Brakes: Because the spacetime carrying the ship would be completely cut off from the outside of the bubble, there would be no way to send a signal to turn off the warp drive. The signal would never get there, and the ship would never stop."

Not so. Control is in the thin skin fuselage.

Illuminating the far side of light speed
Is it even possible to outrun light? You can't move through space faster than the speed of light. But it is possible for space itself to expand faster than light, because it's not moving relative to anything, at least not that we know of. Cosmologists believe that the entire cosmos expanded faster than the speed of light in the first moments after the big bang.
What would it be like in the bubble? The area inside the bubble of negative energy would be isolated—a kind of pocket universe—so passengers wouldn't experience any ill effects from the acceleration. The ship would actually be at rest in its local space, like a pedestrian carried along on a moving sidewalk.
Would warping space be risky? It could produce the luminous equivalent of a sonic boom, a shock wave with infinite energy. And yes, that would be bad. Or, since the bubble would be connected to normal space by only a tenuous tube of energy, it could pinch off into a new universe, trapping travelers forever. Better pick your crewmates wisely.
Could I return before I left? Although time inside the bubble would tick at the same rate as on Earth, the bubble itself could get back before you left. That's because the passage of time is relative; it depends on the observer's velocity. As a general rule, if you can beat light, you can beat time."

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