From: dst+@cs.cmu.edu (Dave Touretzky)
Newsgroups: rec.arts.startrek.tech
Subject: why transporters can't work
Date: 12 Jan 93 09:28:49 GMT
Article-I.D.: cs.C0qIC2.Gyo.2
Organization: School of Computer Science, Carnegie Mellon


I just recently realized why Startrek-type transporters cannot work.  It has
nothing to do with pattern buffers or annular confinement beams; it has to do
with knowing what to transport and what not to.

Imagine that Riker is standing knee-deep in mud when he asks to be beamed
up.  What, exactly, gets beamed up?  On the show we'd expect to see Riker,
all his clothes and equipment, anything he was holding in his hand or in his
mouth, plus a tiny bit of mud appear on the transporter pad.  But which mud?
All the mud  that is above the tops of his boots?  What about the mud on the
ground between his two legs?  How, in general, do you tell mud from boots
when beaming up Riker?  And what if he's not wearing standard-issue boots;
suppose he's wearing sandals made from CLAY?  That's just dried mud.

I think you see the problem:  there's no way in general to determine the
boundary between what should and should not be transported except by
invoking careful human judgement at a very fine level of detail.  For
example, if Riker is standing barefoot on a fur rug, with bits of fur
sticking up between his toes, what should appear on the transporter pad?  Is
the transporter supposed to examine what's between his toes and leave the
fur back on the planet when it beams him up, but take the lint and other
toe-jam along for the ride?  If it leaves the fur, won't it leave the hair
on his legs behind?  (Hair is just dead protein; it's not living cells.)  Or
will it sever the fur and keep it between his toes when he appears on the
pad?

How fine does this discrimination have to be?  Well, consider this:  Riker
is standing barefoot on a polished wood floor.  Just where does the
transporter draw the boundary between stuff-to-grab and stuff-to-leave?  If
it cuts too deep, it will take part of the floor under his feet, marring the
finish.  If it cuts too thin, it will leave bits of human skin behind on the
floor, which also isn't too nice.  (You'd then expect to see plots hinging
on traces of matter left behind by people having transported off of some
surface, which we've never seen.)   Consider also that as Riker's weight on
the wooden floor lessens as he dematerializes, the boards will rise
slightly.  So the transporter has to maintain incredibly fine boundaries
between moving surfaces of possibly great microscopic complexity -- from a
distance of up to 40,000 km.

Let me point out some other examples where judgement is required.  Riker is
sitting in a chair on a hilltop.  The chair has grossly uneven legs, but
it's resting on a grossly uneven hillside, so it's stable.  We beam up Riker
plus chair onto the perfectly level transporter pad.  So the chair
immediately falls over, dumping Riker onto his ass.  Or do we instead beam
up part of the hillside along with the chair, leaving a chunk missing from
the planet's terrain?

The only way I could see all this working is if the computer had such
tremendous artificial intelligence that it could exercise human judgement
about what to beam up and what not to, e.g., "is Riker holding that pole in
his hand expecting to take it with him, or is he merely resting against it?
Well let's see... it extends 18 inches into the ground and is anchored in
cement, so he probably wasn't expecting to take it with him.  He's just
using it for support because he's tired.  Let's shift his limbs around a bit
as we beam him up, to change his center of gravity so he doesn't fall on his
butt when the pole disappears."

I guess I would view this as believable if we occasionally saw questions get
asked during transport.  Example:

  Riker:  "Enterprise, one to beam up -- immediately!"
  O'Brien:  "Do you want the doorknob to come with you, Sir?"
  Riker:  "No, of course not."
  O'Brien:  "Then let go of it please.  Sir."
  Riker:  "Oh, sorry.  Energize."
  O'Brien:  "Ah, just a minute, Sir.  What's that on your feet?"
  Riker:  "Altarean bunny slippers."
  O'Brien:  "Made from live bunnies?  Hmmm.  You want to bring the bunnies?"
  Riker:  "No.  Leave 'em behind."
  O'Brien:  "Aye, sir.  One to beam up, hold the bunnies."

-- Dave Touretzky,  dst@cs.cmu.edu
Newsgroups: rec.arts.startrek.tech