and one more thing, john doe

[Blake Stacey]

Quoting Geocoda at aol.com:

>
> Sheldon Glashow actually said:
>
> But oddly there has been a new development, in which a new class of
> physicists is doing physics, undeniably physics, but physics of a 
> sort that does not
> relate to anything experimental. This new class is interested in 
> experiment from
> a cultural but not a scientific point of view, because they have focused on
> questions that experiment cannot address.
>
> So, not to nitpick and qualify, Johnny, but you've misunderstood a couple of
> key points.
>
> 1) It's physics, for sure
> 2) It is not temporarily, but permanently outside the experimental method
>

<snip>

 From Barton Zwiebach's **A First Course in String Theory** (2004), p. 8:

"It should be said at the outset that, as of yet, there has been no 
experimental
verification of string theory.  In order to have experimental verification one
needs a sharp prediction.  It has been difficult to obtain such a 
prediction. String theory is still at an early stage of development, 
and it is not so easy
to make predictions with a theory that is not well understood.  Still, some
interesting possibilities have emerged."

Two pages later:

"As a theory of quantum gravity, string theory will be needed to study 
cosmology
of the Very Early Universe.  The deepest mysteries of the universe seem to lie
hidden in a regime where classical general relativity breaks down.  String
theory should allow us to peer into this unknown realm.  Some day, we may be
able to understand the nature of the Big Bang, and know whether there is a
pre-Big Bang cosmology.

"Most likely, answering such questions will require a mastery of string theory
that goes beyond our present abilities.  String theory is in fact an 
unfinished
theory.  Much has been learned about it, but in reality we have no complete
formulation of the theory.  A comparison with Einstein's theory is
illuminating.  Einstein's equations for general relativity are elegant and
geometrical.  They embody the conceptual foundation of the theory and feel
completely up to the task of describing gravitation.  No similar equations are
known for string theory, and the conceptual foundation of the theory remains
largely unknown.  String theory is an exciting research area because the
central ideas remain to be found."

And the last paragraph of the first chapter:

"Describing nature and formulating the theory -- those are the present-day
challenges of string theory.  If surmounted, we will have a theory of all
interactions, allowing us to understand the fate of spacetime and the 
mysteries
of a quantum mechanical universe.  With such high stakes, physicists 
are likely
to investigate string theory until definite answers are found."

To sum it up in one word, string theory is "protoscience".  **Given** future
advances in our understanding, it **will be** within the realm of experimental
verification or falsification.  At present, it might callously be dismissed as
a mathematical game, but the "game" has in fact already had a payoff.  The
study of Dirichlet branes, a topic which came into vogue in the mid-1990s, has
led to new ways of formulating, exploring and teaching gauge theories, which
were developed half a century ago and were thought to be a different subject
altogether.  Yang-Mills gauge theories are useful tools, and we **already
have** experimental proof that some subatomic particles obey them.  Therefore,
in an indirect way, the "mathematical game" of string theory has already had a
useful result, one which will remain valid whether or not strings themselves
stay in favor.  Supersymmetry, another out-there concept from high-energy
physics, began with people trying to explore string theories back in 
the 1970s.
It has since become a field of study on its own, and (thanks to Ed Witten and
others) beginning around twenty years ago it has found applications in quantum
mechanics, the study of diffusion, and other subjects, all of which have
"everyday" applications.  Supersymmetry, the child of string theory, is all
growed up and has children of its own:  this third generation is **already**
proving useful, and will continue to do so, even if its "grandparent" fizzles
into obscurity.

In the sixteenth century, one could have dismissed the Copernican model of the
Solar System as a mathematical game, a technique for calculation that had no
real bearing on reality.  Copernicus's editor took this very stance in the
preface to Copernicus's 1543 book which laid the model out.  In fact, the
predictions made of the planets' motions were sometimes **worse** with the
Copernican model than with the Ptolemaic model which preceded it.  All the
charges brought against string theory now could be brought against the
Copernican solar system in 1600, and probably even more so, since until his
work testing the model led Kepler almost up to inventing calculus, no new math
came out of Copernicus.

The situation changed, of course, when Kepler showed that the planets moved in
ellipses, not circles, superseding Copernicus's model and giving it an even
more elegant mathematical formulation.  In string theory, the analagous event
might be the Second Superstring Revolution back in the '90s.  Copernicus was
vindicated and boosted out of the "protoscience" stage when Galileo (and the
others who followed) made the telescopic observations which proved the Earth
was not the center of the cosmos.  The analagous event to this 
discovery in the
history of string theory has not happened yet, and of course, it might never
happen at all.

**All** scientific models pass through a protoscience stage, even if 
this stage
only lasts an hour.  One might be able to guess a new equation in the morning,
work out its consequences by lunch, and compare them to experiment by 
teatime. The new model could then be proven wrong or deemed 
provisionally acceptable in
time for dinner.  Naturally, if the math is harder or if the essential
experiments have not been done, this process will take longer.

String theory in seven words:  "Tiny strings.  Hard math.  Maybe, big payoff."

I am unable to find anything in Glashow's statement which indicates 
that string
theory is "permanently outside the experimental method".  He uses the present
tense, "does not relate", rather than saying "can never relate".  He does say
"questions that experiment cannot address", but "cannot" here refers to the
present situation, not an everlasting verity.

Blake Stacey