Is Warp Drive Physically Possible?
- uploaded: Jun 19, 2014
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The physics of spacetime described by Einstein's Theory of General Relativity allows spacetime to become warped due to the relationship between matter/energy density and the gravitational field described by the Einstein Field Equations. Matter and Energy found in the large scale structure of the universe creates a positive torsion in spacetime, causing the warping of spacetime which is associated with the strength of the gravitational force. In quantum mechanics, zero point energy fluctuations can create negative energy density which should theoretically, in a large enough density, create a negative torsion on spacetime in general relativity. The consequences of these theories, when combined, could change our common sense notions of motion and provide a way to challenge the cosmic speed limit, the speed of light. In 1994, Miguel Alcubierre developed a geodesic equation to describe space-time warped in a bubble around a ship, creating a "warp drive". The warp drive proposed by Alcubierre could achieve near light speeds and even faster-than-light speeds by distorting space-time. To accomplish this, a theoretical device would generate a field of negative energy that would squeeze or stretch space-time, creating the bubble. The bubble would ride the distortions like a surfer on a wave. As evidenced by the uniformity of the Cosmic Microwave Background from the Big Bang, which is explained by inflationary cosmology, space-time can expand so quickly that objects can move faster than the speed of light. Therefore the current models of physics generally allow for the existence of a warp field that can accelerate objects faster than the speed of light. The real questions to ask is whether or not such a warp field can exist on macroscopic scales and if so can it remain stable for long enough to observe its effects, on light in a laser interferometer for example. Moreover it is unknown how it is technologically possible, i.e under what conditions does matter allow for the creation of a negative energy density? In 1948, Theoretical Physicists Hendrik Casimir and Dirk Polder proposed that a negative presssure can exist due to quantum vacuum fluctuations operating on very small scales in space and time and that if two uncharged metallic plates in a vacuum, placed a few micrometers apart the quantum fluctuations should create a force between the 2 plates due to a differential vacuum energy density between the inside and outside of the plates. In a classical description, the lack of an external field automatically means that there is no field between the plates, and no force would be measured between them. However when the zero-point field is instead studied using the QED vacuum of quantum electrodynamics, it is seen that the plates do affect the virtual photons which constitute the field, and generate a net force. The force can give either an attraction or a repulsion depending on the specific arrangement of the two plates. Although the Casimir effect can be expressed in terms of virtual particles interacting with the objects, it is best described and more easily calculated in terms of the zero-point energy of a quantized field in the intervening space between the objects. It was not until 1997, however, that a direct experiment, by Steve Lamoreaux, described above, quantitatively measured the force (to within 15% of the value predicted by the theory) Previous work in the 1970's had observed the force qualitatively, and indirect validation of the predicted Casimir energy had been made by measuring the thickness of liquid helium films by Sabisky and Anderson in 1972. Subsequent experiments with liquid Helium-3 approach an accuracy of a few percent. Using Bose-Einstein Condensates it may also be possible to suppress background effects occurring between individual molecules, such as the Van Der Waals Forces, which will help to quantify the necessary boundary conditions in the second quantisation calculations of Quantum Electrodynamics. This would allow the effect of the vacuum to become dominant in the medium and allow for a more direct observation of negative energy density affecting it. This could also allow for further studies in solid state physics on how the Casimir effect could be controlled at the nanoscale and what physics and applications can be gained from it. Some of this research, although abstract, may help us to understand how electronic transitions occur at the smallest of scales and how to suppress noise, such as that caused by the Casimir effect, in nanoscale circuitry, such as in the emergent fields of quantum circuitry. Therefore by probing some deep questions of physics, and examining theories such as "Warp Drives" we may uncover a great deal of knowledge and gain proposals for some interesting experiments, perhaps even stumbling upon the foundations of warp drive itself along the way.
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