From Osher Doctorow

COPYRIGHT NOTICE
Tachyons As Causal Objects
Copyright By Owner Osher Doctorow Ph.D.
First Published 2005

The "Heisenberg attitude" toward physics arguably was to take refuge in
algebra or other abstract branches of mathematics when questions of
physical reality occurred. While Schrodinger and Einstein had "real
physics intuitions", Heisenberg's intuition was "infinite matrices"
(for those familiar with this, not merely through an isomorphism
between l2 and L2 but on its own). When asked about reality, one of
his famous remarks was roughly that it was enough for the result to be
in the algebra.

This type of thinking persists today with tachyons, which are avoided
by relativists because of their association with superluminal speeds
there as well as negative masses, while they are "half-used" by
quantum/superstring physicists as "semi-causal objects" which in modern
language would be called "virtual" in the sense that they "exist at a
non-physical level but follow 'non-existence laws' whereby they produce
or cause real objects or events or processes through avoiding their own
instantiation or physical existence." The quantum/sperstring people
avoid them as physical (but not virtual) objects because of their
imaginary masses.

The above paragraph is full of logical paradoxes, and it is almost but
not quite meaningless. There is a way to transform it or translate it
so to speak in order to make it meaningful, namely to regard tachyons
as being in a different physical phase or dimension from most of the
rest of matter and energy. Here phase is used in the sense of liquid,
solid, gas, plasma, Bose-Einstein condensate, superfluid,
superconductor, arguably black hole, etc.

Why does translating this into phase/dimension language make it
meaningful? Because objects in particular phases/dimensions tend to
stay there (although not always), and also because you don't have to
claim that objects in different phases/dimensions have no physical
existence - we just needn't observe them if we're in a different phase.

Doesn't this contradict the verification principle of Einstein? I
don't think so. What really "contradicts verification" is virtual
objects or virtual particles or tachyons conceived of as exerting
causation but not themselves physically existing.

In a way, it's hard to analyze this without relating the various uses
of "existence" across different fields or disciplines. In logic, and
mathematics, the backward E symbol stands for "there exists a/an",
which is roughly the same as "for at least one", regarded as logical
operators (existential quantifier, actually). Physical existence
refers to objects or events or processes being "real", and here we come
to a difficulty. Most people, including most scientists, think of
"real" as roughly equivalent to "observable". But observable by whom?


There are quite a few different "observable" meanings.

A. We or some instrument can detect it regardless of what phase we or
it is in.

B. Like A provided that we're in a "communicating phase" (for example,
"inside vs outside black holes" would be non-communicating phases).

C. We may not have the present technology to detect it, but we consider
that if we did have advanced enough technology, we'd detect it.

Meaning B above is especially interesting, because it reminds us that
one of the roles of theory is to transcend experiment or concreteness,
to postulate a part of reality that is not experimental. We would
probably all agree that "explanation" is such a role, and from that we
could argue that "causation" has such a role often, but now we've
wandered into much more "tangible" physics because we've got to decide
whether something that we can't observe can nevertheless cause
something that we do observe. The answer is "yes, it can and does,"
and strangely enough history is the best example. Atoms weren't
observed in electron microscopes at the time that they were first used
as both causation and explanation in physics and chemistry. These two
sciences would have been delayed considerably had people waited to
observe atoms before theorizing and predicting and explaining. And of
course we still don't observe many of the particles/strings/objects
that we deal with but nobody would suggest shutting off arXiv or Front
For the Mathematics arXiv for that reason.

If tachyons are real in quantum/superstring theory, then it becomes
difficult to exclude their reality in general and special relativity.
And so, with Sir Arthur Stanley Eddington who first proposed the
reality of superluminal objects to my knowledge (although he believed
that we can't communicate with them), I think that we'll eventually
decide that tachyons and tachyon condensation are real and physical and
that their causation operates through a type of inertia that keeps them
in their mostly non-communicating phases/dimensions.

Osher Doctorow