🚀 go-pugleaf

> HAYHURS@IUBACS.BITNET
> If ou follow the course of development, the speed of sound was a barrier
> for a very long time; now we have broken the speed of sound.  A lot of
> questions about doing that involed the effects of approaching that mark.
> The spped of sound was a barrier - you could fly up to it, break it, &
> cross over BUT NOT FLY AT IT.  Who says that the speed of light is not
> similar?

Well, there are several meanings of "impossible"... at least three.
One might mean something like "it is impossible to trisect the angle",
or "it is impossible to square the circle", or "it is impossible to
completely solve the halting problem".  These are absolutely
impossible.  They involve abstract entities, the definition of which
make it completely certain beyond rational question that they cannot
be done.

Then there are things like "it is impossible to travel FTL", or
"it is impossible to travel in time", or "it is impossible to
extract work from a system in equilibrium", or "it is impossible
to build a perpetual motion machine".  These involve models
of the real world.  The abstract entities in the model constitute
absolute impossibilities, and the only question is whether the
model accurately describes or resembles reality.

Finally, there are things like "it is impossible to make a heavier
than air flying machine", or "it is impossible to travel faster than
10mph by rail", or other examples.  These merely involve things that
haven't been done yet.  There is no particular well-founded model of
the situation that forbids the situation.

Now it seems to me (and I don't mean to put anyone down here, mind you)
that most people making the argument "well we broke the sound barrier,
so maybe someday we'll break the light barrier" are classing all
"impossible things" as things of the third kind.  It is my belief that
supersonic travel was an "impossibility" of the third kind.  After all,
there were known objects that traveled supersonically, and (as far as
I know) there was no well-checked model of supersonic airflow which
disallowed it.  So all that remained was a small matter of engineering.

But impossibilities of the second kind, FTL for example, are NOT a
small matter of engineering.  Finding them "possible" will require
building a new basic model of reality, and one just about as radical
as one which would allow a perpetual motion machine.  In the Navy, the
difficult is one immediately and the impossible takes a little longer.
But I note that even the Navy hasn't tackled impossibilities of the
first or second kinds, only the third kind.

So, to answer the question posed, *I* say they are not similar.
FTL and FTS are not really remotely in the same class of "difficulty".

( Note well, I am NOT, repeat, NOT saying that FTL is absolutely
  impossible.  After all, conservation of matter was once thought
  to be pretty secure until it became conservation of mass-energy.
  It's just that the analogy of FTL to FTS is flawed. )

( Somebody else mentioned that aerodynamic equations of some sort
  predicted infinite stresses at SoS, "just like" special relativity
  predicts infinite mass at SoL.  But the two are NOT "just alike".
  The aerodynamic equations were engineering equations that were
  developed to model subsonic airflow, and were tested against
  reality for only fairly narrow ranges of conditions.  Special
  relativity, on the other hand, is intended to model velocities and
  interactions of all kinds, and has been tested very thoroughly
  indeed, very close to lightspeed indeed. )

--
All things dull and gargully,
All creatures short and squat,
All thngs rude and nasty,
The Lord God made the lot.
                                --- Monty Python
-- 
Wayne Throop      <the-known-world>!mcnc!rti!xyzzy!throopw