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September 29, 2010

Metamaterial-based model of the Alcubierre warp drive to go up to 25% of the speed of light

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Arvix - Metamaterial-based model of the Alcubierre warp drive by Igor I. Smolyaninov of the University of Maryland.

Alcubierre imagined a small volume of flat spacetime in which a spacecraft sits, surrounded by a bubble of spacetime that shrinks in the direction of travel, bringing your destination nearer, and stretches behind you. He showed that this shrinking and stretching could enable the bubble--and the spaceship it contained--to move at superluminal speeds. Igor Smolyaninov at the University of Maryland, points out that if these kinds of bubbles are possible in spacetime, then it ought to be possible to simulate them inside a metamaterial. The metamaterial would only be an emulation, so that we can learn about how the physics work and eventually figure out if we can and how we would build it.

Electromagnetic metamaterials are capable of emulating many exotic space-time geometries, such as black holes, rotating cosmic strings, and the big bang singularity. Here we present a metamaterial-based model of the Alcubierre warp drive, and study its limitations due to available range of material parameters. It appears that the material parameter range introduces strong limitations on the achievable “warp speed”, so that ordinary magnetoelectric materials cannot be used. On the other hand, newly developed “perfect” magnetoelectric metamaterials are capable of emulating the physics of warp drive gradually accelerating up to 25% of the speed of light.


Metamaterial susceptibilities measured experimentally in the 100 GHz range look adequate to emulate the Alcubierre warp drive to achieve 25% of light speed.

In this paper we explore if electromagnetic metamaterials are capable of emulating the warp drive metric. Since energy conditions violations do not appear to be a problem in this case, metamaterial realization of the warp drive is possible. We will find out what kind of metamaterial geometry is needed to emulate a laboratory model of the warp drive, so that we can build more understanding of the physics involved. It appears that the available range of material parameters introduces strong limitations on the possible “warp speed”. Nevertheless, our results demonstrate that physics of a gradually accelerating warp drive can be modeled with newly developed “perfect” magnetoelectric metamaterials built from split ring resonators. Since even low velocity physics of warp drives is quite interesting, such a lab model deserves further study.


Three dimensional maxwell equations of the gravitational field coincide with the macroscopic Maxwell equations in a magneto-electric material.

The equations show that while “the true warp drive” in vacuum is prohibited, values in a material medium make a warp drive model thermodynamically stable at least at subluminal speeds. However, in classical magnetoelectric materials, such as Cr2O3 and multiferroics, actual values of magnetoelectric susceptibilities are two orders of magnitude smaller than the limiting value described by equation (9), so that the warp drive model is impossible to make with ordinary materials. On the other hand, recently developed “perfect” magnetoelectric metamaterials built from split ring resonators allow experimentalists to reach the limiting values described by equation(9), and make a lab model of the warp drive possible.


Arxiv - Metamaterials proposed as perfect magnetoelectrics

German (Wurzburg and Bremen) researchers -
using millimeter wave spectroscopy of the complex transmission coefficient the electrodynamic properties of a metamaterial of split ring resonators have been investigated. The sensitivity to the magnetoelectric e ect has been obtained within tilt sample geometry and calculated within 4 X 4 matrix formalism. We prove experimentally and within a circuit model calculation that metamaterials from split ring resonators reach the maximum theoretical values of the magnetoelectric susceptibility limited by E2 < = e m. This value appears to be about two orders of magnitude above the typical coupling constants for conventional magnetoelectrics like Cr2O3.

Magnetoelectric susceptibility of a metamaterial built from split ring resonators have been investigated both experimentally and within an equivalent circuit model. The absolute values have been shown to exceed by two orders of magnitude that of classical magnetoelectric materials. The metamaterial investigated reaches the theoretically predicted value of the magnetoelectric susceptibility which is equal to the geometric average of the electric and magnetic susceptibilities. The split ring metamaterial satisfies the upper bound given by equation (9 - thermodynamically stable solution). Equation (10) also provides an upper bound on the largest possible “warp speed”, which is achievable within the described metamaterial model. This upper bound is reached at n(subscript infinity), and equals to one quarter of the speed of light.


Other Work to use currently accessible tech to emulate extreme Physics New Scientist - Hawking radiation glimpsed in artificial black hole

Francesco Belgiorno of the University of Milan, Italy created a black hole analog using laser pulses.

To see if this lab-made event horizon was producing any Hawking radiation, the researchers placed a light detector next to the glass, perpendicular to the laser beam to avoid being swamped by its light. Some of the photons they detected were due to the infrared laser interacting with defects in the glass: this generates light at known wavelengths, for example between 600 and 700 nanometres.

But mysterious, "extra" photons also showed up at wavelengths of between 850 and 900 nanometres in some runs, and around 300 nanometres in others, depending on the exact amount of energy that the laser pulse was carrying. Because this relationship between the wavelength observed and pulse energy fits nicely with theoretical calculations based on separating pairs of virtual photons, Belgiorno's team concludes that the extra photons must be Hawking radiation (Physical Review Letters, in press).

Not everyone is ready to agree. Adam Helfer at the University of Missouri in Columbia says the term Hawking radiation is best reserved for actual black holes with gravitational fields.


Background on the Alcubierre warp drive concept

An Alcubierre Warp Drive stretches spacetime in a wave causing the fabric of space ahead of a spacecraft to contract and the space behind it to expand. The ship can ride the wave to accelerate to high speeds and time travel.



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