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03-03-2021, 08:32 AM
(This post was last modified: 03-03-2021, 10:59 PM by stevebowers.)
https://iopscience.iop.org/article/10.10...382/abdf6e
In this study, we develop a model of a general warp drive spacetime in classical relativity that encloses all existing warp drive definitions and allows for new metrics without the most serious issues present in the Alcubierre solution. We present the first general model for subliminal positive-energy, spherically symmetric warp drives; construct superluminal warp-drive solutions which satisfy quantum inequalities; provide optimizations for the Alcubierre metric that decrease the negative energy requirements by two orders of magnitude; and introduce a warp drive spacetime in which space capacity and the rate of time can be chosen in a controlled manner.
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03-03-2021, 11:04 PM
(This post was last modified: 03-04-2021, 02:28 AM by stevebowers.)
From the last part of the abstract;
Quote:We show that a class of subluminal, spherically symmetric warp drive spacetimes, at least in principle, can be constructed based on the physical principles known to humanity today.
Note the word
subliminal 'subluminal'. That is consistent with the
subliminal subluminal, causally-conservative warp motes we use in OA. I think we may have made the right choice there; if any kind of warp metric has practical use in the real universe, it will likely propagate at a speed slower than, or equal to light, just to conserve causality.
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I have to admit that I find the concept of subliminal warp drives rather interesting, although it’s obviously a typo (or overly enthusiastic auto-correction).
Selden
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03-04-2021, 01:51 AM
(This post was last modified: 03-04-2021, 01:57 AM by SeanR.)
I see only one problem with this.
It was almost two millennia between Eratosthenes measuring the circumference of the earth, and Magellan circumnavigating it.
I don't want to wait 1800 years for warp drive travel to be a thing, and that is a problem.
Of course, our advancements have, thus far, been exponential, so maybe. I can definitely hold out 18 years. 180 years is a bit iffy.
Edit. Others already knew or suspected it was round. Eratosthenes did the math.
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03-04-2021, 04:07 AM
(This post was last modified: 03-04-2021, 04:08 AM by Vitto.)
High physics is far away from my specialization, said so, I'm the only one that sometimes wonders the reason of scientific papers like this based on assumptions that could be very possibly be false, like negative energy?
For a more "down of Earth" example I'd say design climber for space elevators when you lack a material to create them (on Earth).
Perhaps I just find them too much removed from common science
Quote:I don't want to wait 1800 years for warp drive travel to be a thing, and that is a problem.
C'mon, I'm not gonna say AIs but MAAAAYBE we will see the first DNIs!
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(03-04-2021, 04:07 AM)Vitto Wrote: High physics is far away from my specialization, said so, I'm the only one that sometimes wonders the reason of scientific papers like this based on assumptions that could be very possibly be false, like negative energy?
Negative energy and the things that grow out of it like wormholes and warp drives is predicted by/shakes of out the equations relating to Relativity Theory - which has been experimentally verified in multiple ways and on multiple levels.
As such this makes negative energy and related much harder to dismiss.
We haven't actually proved the existence of negative energy yet and a lot physicists seem to take the position that even though it seems to shake out from Relativity Theory the eventual creation of whatever comes after Relativity (a Theory of Everything perhaps) or the eventual merger of Relativity and Quantum Theory will 'surly' eliminate negative energy and/or wormholes and warp drives as theoretical possibilities. However, so far there has been little real progress on either of these things, either in general or in terms of a theory that doesn't rely on a bunch of more or less untestable starting assumptions (dozens of extra dimensions, ultra tiny hypothetical structures like strings that we have no way of experimentally verifying,etc.) or other things that give physicists fits.
And so negative energy (and the things arising out of it) persists.
Todd
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Quote:Negative energy and the things that grow out of it like wormholes and warp drives is predicted by/shakes of out the equations relating to Relativity Theory - which has been experimentally verified in multiple ways and on multiple levels.
Right and I knew it, d'oh!
I meant exotic matter when I wrote that and wrote negative energy instead
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I believe the Cassimere Effect is a demonstration of negative energy. The big question mark about Alcubierre was, I believe, the need for imaginary rest mass. This paper says it can be done with normal matter.
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I am not optimistic about the development of any meaningful superluminal drive.
Partially because I somewhat doubt the physics of negative energy and none of the candidates for types of exotic matter that I've heard about seem likely to be possible for us to design with, build with, contain, and use.
Partially because the speed of light seems to be a fundamental limit on causality - the rate at which any energy can change anything distant from itself. And I believe in a fairly strong causality. OA with its notion of wormhole mouths created by entanglement and then moved apart through realspace, with preservation of the Vissier limit on propagation of change, seems (barely) plausible to me. An out-and-out superluminal drive that can be used to go in any direction does not.
But mostly because of how much more horrible it makes the Fermi Paradox. I can buy the notion that we're alone in this galaxy, or alone in the nearest 200 galaxies. We literally don't know how long the odds were. But if you now introduce a superluminal drive, and aliens at least as smart as us who can use it, we suddenly have to explain why we're alone in countless millions upon millions of galaxies.
All those places where life could have arisen is one thing without a superluminal drive. But if there is one, then we have to consider places where life could have arisen anywhere in the universe, because if they have arisen and discovered a superluminal drive we'd have met them by now.