In
my blog post several days ago I complained about what I called a
double standard followed by many a modern physicist. The double
standard is that theoretical physicists spend huge amounts of time
speculating about strange, far-out concepts such as spacetime
wormholes, time travel, parallel universes, string theory and
multiverses (things for which there is no observational support), but
the same individuals dismiss as nonsense many possibilities such as
ESP for which there is a great deal of evidence (much of it
accumulated by scientists and documented in scientific papers that
have been published for decades). That evidence includes compelling
ganzfeld studies that show a success rate of about 31% greatly in
excess of the expected success rate of 25%. For
example, this study says, “if
one considered all the available published articles up to and
including 1997 (i.e., Milton and Wiseman’s 30 studies, plus 10 new
studies), 29 studies that used standard ganzfeld protocols yielded a
cumulative hit rate that was significantly above chance (31%).” An ESP study involving only artistically gifted people reported a success rate of 50%, twice the success rate expected by chance.
Schematic depiction of ESP
The
very next day I read a book The Eerie Silence
by physicist Paul Davies that contained a passage that almost seemed to have
been written in response to my blog post. He discussed exactly the
same discrepancy I discussed, using the same term that I used
(“double standard”) to describe it; however Davies tried to
defend this double standard.
Before
trying to rebut this reasoning by Davies, let me make clear that I am
a longtime Paul Davies fan. I have enjoyed many books he has written,
and in 19 cases out of 20 I find his reasoning to be convincing. But
in the example I will now discuss, I think Davies fails to come up
with a convincing argument.
Davies
starts out like this:
The
point about modern physics is that weird entities like dark matter or
neutrinos are not proposed as isolated speculations, but as part of a
large body of detailed theory that predicts them. They are linked to
familiar and well-tested physics through a coherent mathematical
scheme. In other words, they have a place in well-understood theory.
As a result, their prior probability is high.
Davies
is on extremely dubious ground here. Neutrinos are predicted by the
Standard Model of Physics, but dark matter is not at all predicted by
that theory. There are no particles of dark matter mentioned in the
Standard Model of Physics. Physicists believe in the likelihood of
dark matter not for theoretical reasons but because of observational
reasons, because they need dark matter to help explain certain
observations. Exactly the same thing can be said about ESP.
Dark
matter is not at all “linked to familiar and well-tested physics
through a coherent mathematical scheme.” It is instead a
completely mysterious alleged thing that we basically know nothing
about. We have zero tested equations that describe dark matter, and also
zero equations that describe ESP. That really leaves dark matter and
ESP in the same ballpark.
In
the case of a similar and equally important mysterious phenomenon –
dark energy – we can say that there is a strong theoretical basis
for believing that there is something like dark energy. However, the
problem is that the theory (quantum field theory) tells us dark
energy should be at least a trillion trillion trillion trillion
trillion times more powerful than it is. This is the widely discussed
“vacuum catastrophe,” often referred to as the worst prediction
in the history of science. Scientists continue to believe in dark
energy, even though their theories are almost infinitely out of whack
with our observations about how much dark energy exists. So is dark
energy something that is “linked to familiar and well-tested
physics through a coherent mathematical scheme”? No it isn't. You
can't use such language when the theory gives an answer that is wrong
by a factor of 1,000,000,000,000,000,000,000,
000,000,000,000,000,000,000. So any claim of theoretical rectitude
can't be used for dark energy – but scientists continue to believe
in it.
In
truth, neither dark matter nor dark energy is part of “well
understood theory.” They are mysterious things that we do not have
any well-established theory for (at best we have half-baked,
super-speculative or “way off the mark” theories). The same
thing can be said about multiverses, parallel universes, time travel
and wormholes.
I
may also note that Davies errs when he suggests that the “prior
probability” of something is “high” when it can be “linked to
familiar and well-tested physics through a coherent mathematical
scheme.” With sufficient ingenuity, a physicist can create all
kinds of bizarre, improbable theories that are linked in some way to
existing physics. Inventive physicists have done that, creating a
thousand and one conflicting theories of time, space, particles, and
forces, including countless different varieties of string theory,
inflation theory and quantum gravity. The
fact that you can somehow link your theory in with existing physics
does not show it has even one chance in 100 of being correct. As
Davies himself says in another book, “It is easy to construct artificial
universe models, albeit impoverished ones bearing only a superficial
resemblance to the real thing, which are nevertheless mathematically
and logically self-consistent” (Information and the
Nature of Reality, page 68).
Regarding
ESP, Davies says the following:
Telepathy
is not obviously an absurd notion, but it would take a lot of
evidence for me to believe in it because there is no properly worked
out theory, and certainly no mathematical model to predict how it
works or how strong it will be in different combinations. So I assign
it a very low (but non-zero) prior probability. If someone came up
with a plausible mechanism for telepathy backed up a proper
mathematical model which linked it to the rest of physics, and if the
theory predicted specific results – for example, that the
'telepathic power' would fall off in a well-defined way as the
distance increases, and would be twice as strong between same-sex
subjects as mixed-sex subjects – I would sit up and take notice. I
would then be fairly easily convinced if the experimental evidence
confirmed the predictions. Alas, no such theory is on the horizon,
and I remain extremely skeptical about telepathy in spite of the many
amazing stories I have read.
Here
Davies professes quite a demanding set of criteria before we can
believe something: (1) that we should only believe something if it is
predicted by some mathematical model; (2) that this model should be
“linked to the rest of physics”; (3) that the model should make
specific numerical predictions that can be confirmed. Does it make
sense to advance such a set of criteria as a prerequisite for
believing in something? It certainly does not.
One
reason is that a very large fraction of all things that we do believe
in (inside and outside of the sciences) do not satisfy such a set of
criteria. But we accept such things nonetheless because we have
observations that compel us to believe in them. I refer to things
such as love, hate, psychological discomfort, newly discovered
species, gamma ray bursts, and earthquakes. Consider, for example,
when a biologist discovers a new species of animal in Brazil. It is
not at all something predicted by some mathematical model, but it is
accepted as a new scientific finding nonetheless. Even in the hard
physical sciences we have things that are accepted even though they are
not at all predicted by existing models. A recent example is the
discovery of the acceleration of the universe's expansion, which
left scientists stunned, having been predicted by no popular theory.
What
Davies describes here is a model of verification that is sometimes
followed (but often not followed) in the world and physics and
astronomy, but such a model of verification is actually uncommon in
many other sciences. Sciences such as psychology, geology, and
biology make relatively little use of mathematical models and prediction. If you pick up a
textbook on zoology you will see almost no equations or mathematical
models anywhere. In such sciences there is no standard at all that
some new scientific conclusion must be supported by some mathematical
model.
As
for Davies' idea that ESP would need to be supported by some
theoretical model “linked... to the rest of physics,” such a
prerequisite does not make any sense. It amounts to saying, “I
refuse to believe in something unless it is similar to things I have
already learned.” I may note that some of the greatest advances in
physics and astronomy occurred when scientists started to postulate
things that did not fit in with the previous framework of ideas. When
quantum mechanics was introduced, it did not fit in at all with
physics as it had been previously understood. When the Big Bang
theory was introduced, it did not fit in at all with the previous
cosmological ideas of scientists such as Einstein, who favored the
idea of an eternal, static universe.
Davies
suggests the idea that we should not take an observed phenomena
seriously unless we have a theory of how it works, one that makes
good predictions. That is a misbegotten principle that scientists
themselves do not follow. When scientists observe a new type of
phenomenon, they accumulate observations for the phenomenon, and at
the same time start working on theories to explain the phenomenon. It
may be decades or centuries later that a theory arrives that finally
explains the phenomenon. An example is pandemics. The phenomenon was
studied for centuries before scientists such as Pasteur finally came
up with a decent theory to explain it.
It
would have made no sense around 1600 to have said, “Don't believe
in pandemics – we don't have a good theory to explain it.”
Another example is lightning. Scientists observed it for a long time,
but did not develop a decent model to explain it until the 18th
century. It would have made no sense around 1500 to have said, “Don't
believe in lightning – we don't have a good model to explain it.”
What
Davies' criteria amounts to is a kind of plea that he should be
excused from taking something seriously whenever that thing does not
have characteristics that allow him to study it in the way that he is
most familiar and comfortable with studying things. That's a lame
type of reasoning. We can imagine the same type of reasoning being
used by a biologist: “I refuse to believe in galaxies or other
reputed deep space-objects, because I cannot view them through my
microscope, or place them in my test tubes, or study them in a cage
or an aquarium.”
A
wiser approach is that we should take a phenomenon seriously whenever
we have repeated compelling evidence for its existence, regardless of
whether we have familiar off-the-shelf methods for studying the
phenomenon, and regardless of whether the phenomenon comfortably
meshes with our preconceptions.
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