Didn't see it until you called my attention to it.
I don't think that the speed limit gets violated under any circumstances. It is hard to tell is the issue in this case is one of miscommunicating what really happened, or of flawed experimental methods.
The paper and its abstract (note all the weasel words):
While conducting analysis related to a DARPA-funded project to evaluate possible structure of the energy density present in a Casimir cavity as predicted by the dynamic vacuum model, a micro/nano-scale structure has been discovered that predicts negative energy density distribution that closely matches requirements for the Alcubierre metric. The simplest notional geometry being analyzed as part of the DARPA-funded work consists of a standard parallel plate Casimir cavity equipped with pillars arrayed along the cavity mid-plane with the purpose of detecting a transient electric field arising from vacuum polarization conjectured to occur along the midplane of the cavity. An analytic technique called worldline numerics was adapted to numerically assess vacuum response to the custom Casimir cavity, and these numerical analysis results were observed to be qualitatively quite similar to a two-dimensional representation of energy density requirements for the Alcubierre warp metric. Subsequently, a toy model consisting of a 1 m diameter sphere centrally located in a 4 m diameter cylinder was analyzed to show a three-dimensional Casimir energy density that correlates well with the Alcubierre warp metric requirements. This qualitative correlation would suggest that chip-scale experiments might be explored to attempt to measure tiny signatures illustrative of the presence of the conjectured phenomenon: a real, albeit humble, warp bubble.
Harold White1a, Jerry Vera1, Arum Han, Alexander R. Bruccoleri, and Jonathan MacArthur, "Worldline numerics applied to custom Casimir geometry generates unanticipated intersection with Alcubierre warp metric" 81 Eur. Phys. J. C 677 (July 21, 2021) https://doi.org/10.1140/epjc/s10052-021-09484-z
Reactionless thrust would be pretty useful regardless of speed of light violations (if this is from vacuum energy I don't see how it could alter the speed of light either).
More analysis with two out of three answers arguing that it isn't really "negative energy" in the relevant sense and a third not really squarely engaging with the core question even while nominally stating that it is possible to have negative energy (but not necessarily speed of light violations). https://physics.stackexchange.com/questions/47922/can-negative-energy-be-created-by-the-casimir-effect and also negative in practical applications at https://physics.stackexchange.com/questions/45604/alcubierre-warp-bubble-effect-on-gravity-and-space and https://physics.stackexchange.com/questions/643410/how-would-a-warp-bubble-interact-with-an-atmosphere (closed as it is not "mainstream science") and negative energy is only relative to other locations not in absolute terms https://physics.stackexchange.com/questions/162078/what-is-negative-energy and https://physics.stackexchange.com/questions/87425/what-is-negative-energy-exotic-energy (explaining negative energy in the context of GR and proposed laws of physics that rule it out since it leads to singularities and contradictions not physically observed).
5 comments:
Any thoughts on the DARPA warp bubble story?
Didn't see it until you called my attention to it.
I don't think that the speed limit gets violated under any circumstances. It is hard to tell is the issue in this case is one of miscommunicating what really happened, or of flawed experimental methods.
https://thedebrief.org/darpa-funded-researchers-accidentally-create-the-worlds-first-warp-bubble/
The paper and its abstract (note all the weasel words):
While conducting analysis related to a DARPA-funded project to evaluate possible structure of the energy density present in a Casimir cavity as predicted by the dynamic vacuum model, a micro/nano-scale structure has been discovered that predicts negative energy density distribution that closely matches requirements for the Alcubierre metric. The simplest notional geometry being analyzed as part of the DARPA-funded work consists of a standard parallel plate Casimir cavity equipped with pillars arrayed along the cavity mid-plane with the purpose of detecting a transient electric field arising from vacuum polarization conjectured to occur along the midplane of the cavity. An analytic technique called worldline numerics was adapted to numerically assess vacuum response to the custom Casimir cavity, and these numerical analysis results were observed to be qualitatively quite similar to a two-dimensional representation of energy density requirements for the Alcubierre warp metric. Subsequently, a toy model consisting of a 1 m diameter sphere centrally located in a 4 m diameter cylinder was analyzed to show a three-dimensional Casimir energy density that correlates well with the Alcubierre warp metric requirements. This qualitative correlation would suggest that chip-scale experiments might be explored to attempt to measure tiny signatures illustrative of the presence of the conjectured phenomenon: a real, albeit humble, warp bubble.
Harold White1a, Jerry Vera1, Arum Han, Alexander R. Bruccoleri, and Jonathan MacArthur, "Worldline numerics applied to custom Casimir geometry generates unanticipated intersection with Alcubierre warp metric" 81 Eur. Phys. J. C 677 (July 21, 2021) https://doi.org/10.1140/epjc/s10052-021-09484-z
Reactionless thrust would be pretty useful regardless of speed of light violations (if this is from vacuum energy I don't see how it could alter the speed of light either).
More analysis with two out of three answers arguing that it isn't really "negative energy" in the relevant sense and a third not really squarely engaging with the core question even while nominally stating that it is possible to have negative energy (but not necessarily speed of light violations). https://physics.stackexchange.com/questions/47922/can-negative-energy-be-created-by-the-casimir-effect and also negative in practical applications at https://physics.stackexchange.com/questions/45604/alcubierre-warp-bubble-effect-on-gravity-and-space and https://physics.stackexchange.com/questions/643410/how-would-a-warp-bubble-interact-with-an-atmosphere (closed as it is not "mainstream science") and negative energy is only relative to other locations not in absolute terms https://physics.stackexchange.com/questions/162078/what-is-negative-energy and https://physics.stackexchange.com/questions/87425/what-is-negative-energy-exotic-energy (explaining negative energy in the context of GR and proposed laws of physics that rule it out since it leads to singularities and contradictions not physically observed).
Post a Comment