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Could We Find a Door To A Parallel Universe?
p1234 writes "Though no direct evidence for wormholes has been observed, this could be because they are disguised as black holes. Now Alexander Shatskiy of the Lebedev Physical Institute in Moscow, Russia, is suggesting a possible way to tell the two kinds of object apart. His idea assumes the existence of a bizarre substance called "phantom matter", which has been proposed to explain how wormholes might stay open. Phantom matter has negative energy and negative mass, so it creates a repulsive effect that prevents the wormhole closing. 'US expert Dr Lawrence Krauss, from Case Western Reserve University in Cleveland, Ohio, points out that the idea rests on untested assumptions. He told New Scientist magazine: "It is an interesting attempt to actually think of what a real signature for a wormhole would be, but it is more hypothetical than observational. Without any idea of what phantom matter is and its possible interactions with light, it is not clear one can provide a general argument."'"
You don't even need to be a physicist for that - being an electrical engineer is enough. Things like imaginary current etc. *do* appear in electrics; see http://en.wikipedia.org/wiki/Imaginary_part for instance.
It's a little hard to tell from this very brief article, but what he calls "phantom matter" is what other physicists call "exotic matter" or sometimes "negative matter," which violates one of the positive energy-conditions, and thus has negative energy (in some reference frame). Matt Visser's book Lorentzian Wormholes has a lot more technical details about the various formulations of the positive-energy conditions.
http://www.geoffreylandis.com
I had the wonderful opportunity to see a talk by one of the experts of (and I think original proposer of) dark matter.
That's not likely, or if it is true, it's not very relevant. Fritz Zwicky first proposed dark matter (in it's current incarnation) back in the 1930s. However, no one else in the field started to consider this idea until the 1970s (Zwicky died in '74) when other independent bits of evidence started to come in that hinted at dark matter. At that time, people in the field were particularly mindful that the problem could be resolved by either dark matter or by modifying our theories. But as time went on, more and more independent pieces of evidence came in which addressed the same issue. Now, the problem is that if you want to account for each of these observations by modifying our dynamica/gravitational theories, you have to do a different modification in each instance. On the other hand, ALL of these observations are resolved by introducing dark matter. The door was virtually shut on modified theories with the analysis of the Bullet Cluster, which simply cannot be explained by modified gravitational theories. And actually, dark matter is not so esoteric; there are many current theories in particle physics that [independently] predict the existence of a particle that would meet the characteristics that we observe and would also be naturally produced in large quantities during the big bang.
Cayley sedenions are a 16 dimensional field. But zero has divisors in sedenion algebra. Octonion multiplication isn't associative, though. Nor is quaterionion multiplication commutative. It just depends on what characteristics you require for the purpose at hand, really. Froebenius' theorem tells us that only real, complex and quaternionic algebrae are associative division rings over real scalars. But if you only need finite fields (as is often the case in practical applications), an Artinian ring is often iteratively solvable for any given application, of arbitrary dimension.
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