If vacuum energy has some positive value x in the context of general relativity, and the casimir effect can have a region go below vacuum energy by more than x, from what I understand it should then qualify as negative energy in a relativistic context. I once asked about this on an online physics forum and the response at https://www.physicsforums.com/threads/is-reverse-time-dilation-posssible.98775/page-2#post-821108 suggested that if you consider the vacuum energy to be the same thing as dark energy in cosmology (as is often suggested by physicists, for example at https://www.space.com/25238-dark-energy-quantum-vacuum-theory.html ), then based on the resulting value for the positive energy of the vacuum, a plate separation of less than about 10^-5 meters in Casimir experiments would be sufficient to have negative energy in the relativistic sense.
The wikipedia article on wormholes also notes in the section on traversable wormholes at https://en.wikipedia.org/wiki/Wormhole#Traversable_wormholes that various physicists including Stephen Hawking and Michael Morris/Kip Thorne (who first published the traversable wormhole solution) have suggested that Casimir energy might in theory supply the necessary negative energy to hold open a wormhole, for example they link to the Morris/Thorne paper at https://authors.library.caltech.edu/9262/1/MORprl88.pdf where they write on p. 1447 that 'The following model explores the use of the "Casimir vacuum"12 (a quantum state of the electromagnetic field that violates the unaveraged weak energy condition11) to support a wormhole'. But another section of the wormhole article at https://en.wikipedia.org/wiki/Wormhole#Raychaudhuri's_theorem_and_exotic_matter says that more than just any old kind of negative energy is needed for a traversable wormhole, that it's required to have a negative energy field that violates the "averaged null energy condition" and that the Casimir effect in flat spacetime wouldn't do this, but it goes on to say that 'calculations in semiclassical gravity suggest that quantum effects may be able to violate this condition in curved spacetime.[44] Although it was hoped recently that quantum effects could not violate an achronal version of the averaged null energy condition,[45] violations have nevertheless been found,[46] so it remains an open possibility that quantum effects might be used to support a wormhole.' On Fri, Nov 18, 2022 at 4:51 PM Brent Meeker <meekerbr...@gmail.com> wrote: > That's an energy density lower than the surrounding vacuum. The > conducting plates exclude longer wavelengths relative to their spacing. > This is not the same as negative energy in the vacuum. > > Brent > > On 11/18/2022 3:38 AM, John Clark wrote: > > On Tue, Nov 15, 2022 at 3:00 PM Brent Meeker <meekerbr...@gmail.com> > wrote: > > * > A stable wormhole requires threading by negative energy density. >> Since no such negative energy field is know and it's existence would >> imperil the stability of matter, its existence seems highly unlikely.* >> > > In the Casimir Effect (which has been experimentally confirmed) the narrow > space between 2 flat conducting plates has a negative energy density, and > that causes an attraction between the 2 plates because there is more energy > outside the plates pushing the plates together than there is between the > plates pushing the plates apart. > > John K Clark See what's on my new list at Extropolis > <https://groups.google.com/g/extropolis> > pl6 > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to everything-list+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/CAJPayv1LP6u9D2pgtUw0TnUYTJwREKF%2BeeNuTJR38aKB6pDj8w%40mail.gmail.com > <https://groups.google.com/d/msgid/everything-list/CAJPayv1LP6u9D2pgtUw0TnUYTJwREKF%2BeeNuTJR38aKB6pDj8w%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to everything-list+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/c60f9d09-7433-3fef-7cf5-041d61862079%40gmail.com > <https://groups.google.com/d/msgid/everything-list/c60f9d09-7433-3fef-7cf5-041d61862079%40gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAPCWU3K%2BRriDH_GKp8nty6vWbGHriSo4pLTUfPG0vAuT3KycGg%40mail.gmail.com.
