From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.physics
Subject: Re: Teleportation?
Date: 26 Nov 1998 19:14:39 GMT

In <365D754F.175E@ix.netcom.com> Uncle Al <UncleAl0@ix.netcom.com>
writes:
>
>Gil Hagi wrote:
>>
>> Hi, I'm doing my chem ISP on the feasability of teleportation. I was
>> just wondering what thoughts you people might have about how possible
>> this is, what potential hurdles might exist in making this possible.
>> From what I see, the only physical problems with teleportation are
>> heisenberg's uncertainty principal (which I hear someone has found a
>> way around), and computing power (which will be there in a few
>> years...)
>>
>> So what else is there?
>>
>> Gil.
>
>If you are going to transport the substance, figure out he E=mc^2 energy
>of 70 kg of human being. If you are going to transport the information...
>how many bytes are we talking? Read some Claude Shannon and note a mole
>contains 6x10^23 little fellas.



   The nice thing is that a lot of info is redundant.  Your body
contains a lot of water molecules (in fact numerically MOST of the
body's molecules) which can go anywhere-- only vague info on placement
needed, and none at all on orientation.  Same for a lot of generic
chemicals in solution.  Proteins?  You only have 100,000 different ones
or so (same number as the number of your genes) and once you identify
one, it takes only ln(100,000) = 6 x ln10 = 14 bits to say what you've
got (assuming modest code library on receiving end).  Add a few more
for spacial orientation (say 6, giving 32 possible solid angles for the
agreed "head" to point in)  if it's a lipid-bound protein, and 2 x 9 x
ln10 = 40 bits or so for the nanoassemblers to place it on the 1 meter
square 2-D receiver plate (again, assuming a code library grid for
receiver placement).  Think of it as DVD for humans.  How many protein
molecules in a human?  Figure 100,000 dalton molecules (1.7e-21 kg) and
10 kg of protein and you get 6e21 molecules, each specified (if you
give each a number like a stone in some old cathedral being moved from
here to there) by 50 bits.  Add it up for proteins and you've got 6e21
molecules to place, each requiring 14 + 6 + 40 = 60 bits of info.
Total of 4e22 bits, perhaps, and that's a pretty good start.

Present fiberoptic info transfer rates are only 1e11 bits/sec or 3e18
bits/yr.  So it would 10,000 yrs to transfer a human.  But Moore's law
works for this kind of thing, also, and you get a factor of 10
improvement every 8 years, with no obvious law of physics in the way
for a long while.  That means in 40 years we should be able to transfer
this in 5 weeks or so. People will be faxed and photocopied, but not
like on Star Trek.  Instead, the human in metabolic statis will be
grown out of a 2-D replicator plate (on which layers are assembled by
nanomachines) over the space of weeks to months.  Not the greatest for
business convention travel, but a good way to get to Pluto or that
earthlike planet around Alpha Centauri A, maybe.   Also good for
cryonics, or backup copies in case you get cremated by a volcano, or
something.  Whether this is "you" or not is a semantic, not a
scientific question.

From: sbharris@ix.netcom.com (Steven B. Harris)
Newsgroups: sci.physics,sci.physics.research
Subject: Re: Downloading hardware from the Internet
Date: 26 May 1999 00:16:40 GMT

In <7i3nap$kov@news.tue.nl> Karel Knechten <karelk@stack.nl> writes:

>I think it will be impossible to transport everything [as
>information], unless one can build it up from it's atoms - and that's
>impossible because of Heisenberg.
>
>Greetinkz,
>Karelk


    Heisenberg keeps you mostly from seeing where electrons are-- it
doesn't keep you from locating atoms reasonably well-- we'll all seen
the AFM and STEM pics.  If you have a bunch of little machines that
feel out surfaces and identify atoms and send the positional
information to a bunch of other machines which assemble atoms from a
stock into an idential 2-D surface, you're off an running.  You can
tear down a 3-D object on one side of your transmitter, and build it up
on the other side, an atomic or molecular layer at a time.  You might
have to keep the object quite cold while the process goes on, but for
many objects that's not a problem.

   How fast?  Drexler of the Nanotechnology crowd has done some
prelimary calculations on how fast machines with arms made of tubes of
carbon atoms might be able to move them, and it's quite fast-- millions
of times a second.  How fast you can put down a layer will depend on
how much information is in it, just as tiling a floor with some jigsaw
puzzle scene takes longer than a simple pattern.  So crystals will go
fast, and biological specimens will go slowly.  It won't be like Star
Trek, but more like watching bamboo grow, I suspect.

   Biological specimens might not go as slowly as you think, though,
since there isn't as much information even in an organism as first
appears.  If a human has 100,000 genes for that many proteins, you need
only send the structure for each of 21 amino acids once, then the full
amino acid code for each of the 100,000 proteins once, and after that
the machines only have to look at the protein well enough to
distinguish it from all others (which can be done by reading only a few
amino acids), and then  the entire molecule can be ripped out at the
transmitter end, and the data sent as one 16-bit code number with a tag
denoting a protein found, to the other.  At which point the assembler
gets the appropriate protein molecule from the store, and tacks it down
to the spot.  And so on.  A few more bits may be needed for orientation
of some proteins.  Water molecules are generic and a lot of lipids
also.  Orientation will matter only for things found naturally in
organisms tacked to a solid phase, and even then, only such orientation
which is expected to be resistant to thermal buffeting in the live
organism, which isn't much.

   Since cells and small clusters of cells (embryos) can be recovered
from liquid helium now, there is not problem in sending such things by
matter trasporter, and having them arrive "alive" (revivable).  For
larger collections like organs and organisms the technology awaits only
good methods of cryopreservation which obviate chilling injury and ice
damage (which happens now mostly between cells and due to osmotic
forces, contrary to a lot of SF hoopla).  It should be possible to
replace enough water in organisms with organic solvents that little ice
is formed on solidification, and most of the liquids vitrify.  This may
allow cryopreservation of organs and even people with immediate
viability (true suspended animation).  Matter transmission of vitrified
organisms, including people, ought to be possible.  FAXing and
Photocopying of people is not a physical impossibility, so far as I can
tell-- it's just a matter of technology.

   For some of the philosophical implications, one can see Algis
Budrys' _Rogue Moon_ (1960) and many other SF tales that have followed.
What makes you YOU, and what makes a repaired vitrified you, YOU, and
what makes a copy, or a transmitted version of you, YOU?  These are
more value judgements than meaningful physics questions.  They don't
have objective answers.  The question of identity is the problem of the
Sorites paradox, also known as the Thesius's ship problem (replace a
ship a board at a time, and when does it cease to become the original
ship?).  We are information beings, and it's the information that makes
us who we are, not the atoms.  But how much information is critical to
identity?  How is it that quantitative changes finally add up to a
qualitative change?  We have no answer for that because qualitative
changes are usually in the mind's eye.  But it'll be fun to grapple
with when the time comes.

                                      Steve Harris