🚀 go-pugleaf

> Turtles all the way down?

Yes -- and it's turtles all the way up too :)

(can anyone tell me where I got this quote from...
 I'd like to be able to give a reference.)

In article <SWRA01.94Sep27121133@cs19.cs.aukuni.ac.nz>,
Stephen David  Wray <swra01@cs.aukuni.ac.nz> wrote:
>
>> Turtles all the way down?
>
>Yes -- and it's turtles all the way up too :)
>
>(can anyone tell me where I got this quote from...
> I'd like to be able to give a reference.)

From Hawking's "Brief History of Time".
Are you a former UH student? i.e who I think you are?

Best regards,

Siemion Fajtlowicz.

Stephen David  Wray (swra01@cs.aukuni.ac.nz) wrote:

: > Turtles all the way down?

: Yes -- and it's turtles all the way up too :)

: (can anyone tell me where I got this quote from...
:  I'd like to be able to give a reference.)

Terry Pratchett's novels are one source. I suspect this is a scientific
urban legend. Biochemically and structurally, of course, it ->is<- turtles
all the way down--there is very little random about cellular structure and
dynamics at any level. The question, though, is whether the information
transfer/processing continues down past the synaptic level.  Given the
need to coordinate vesicle production in the soma with vesicle usage in
the synapses (for both the dendrites and axon), I suspect there is at
least 'housekeeping' interaction. 

--
Harry Erwin
Internet: herwin@gmu.edu 
Just a dumb graduate student working on Katchalsky network models....
(And if you believe that, I have a ranch in California to sell you.)

HARRY R. ERWIN (herwin@mason1.gmu.edu) wrote:
: I have questions in my mind about the currently popular research into
: quantum non-locality in neural systems. However, I do know of mechanisms
: by which a few synapses with patterned releases of neurotransmitter can
: control the dynamics of a dendrite (Barlett Mel's work), a couple of basal
: dendrites can cooperate to control the dynamics of a neuron (preliminary
: modeling work), and perhaps 500 principle cells in a nerve cell assembly
: can control the spiking of 10,000-40,000 neurons. These seem to involve
: (at least in the latter two cases) stochastic resonance in an actively
: tuned system. Once at the level of 10,000-40,000 neurons, the next few
: stages up (leading to the entire brain) are currently the subject of
: active research. So it seems the turtles do extend down to the synapse. 
: Has there been any study of structured dynamics within the synapse? 


I've not run across too much above the single neuron level.
Most of what I've seen has been in conjunction with microtubules, and so is
primarily intraneurolnal. (No particular reason it should be I suppose
except unwillingness to stick a neck or two out on it yet.) These particular
discussions tend to end at the synapse.

Functionally, the discussion could be interneuronal, since it would deal
more with the activity going on at the time, and hence the particular piece
of processing at hand. And as someone (Earl Miller?) pointed out, the result
of a visual image can be carried by a single neuron, heading back north from
the visual cortex. That result was somewhat suprising, contrasted with the
fact that you expect most things to be carried by many. 

Perhaps there's something which can help root out the effect if it is
strictly intraneuronal by focusing on the visual system mentioned.

BTW, I've completed my application to Radford. That conference was too much
fun. And it's such a nice place. I'm going to try to work with Karl.

--
dynasor@infi.net                                       The Doctor is on.

John Robert Ross uses it as the Fragestellung of his 1967 Dissertation
on "Constraints on Variables in Syntax" and notes that "The anecdote
is told of William James.  I have been unable to find any published
reference to it, so it may be that I have attributed it to the wrong
man, or that it is apocryphal."

			Steve Helmreich

math0@menudo.uh.edu (Siemion Fajtlowicz) writes:

>In article <SWRA01.94Sep27121133@cs19.cs.aukuni.ac.nz>,
>Stephen David  Wray <swra01@cs.aukuni.ac.nz> wrote:
>>
>>> Turtles all the way down?
>>
>>Yes -- and it's turtles all the way up too :)
>>
>>(can anyone tell me where I got this quote from...
>> I'd like to be able to give a reference.)

>From Hawking's "Brief History of Time".
>Are you a former UH student? i.e who I think you are?

Is the full story of the old lady there too, or is it just
the punchline?


--
						-- Mark---
....we must realize that the infinite in the sense of an infinite totality, 
where we still find it used in deductive methods, is an illusion. Hilbert,1925

> : > Turtles all the way down?
> 
> : Yes -- and it's turtles all the way up too :)

> Terry Pratchett's novels are one source. I suspect this is a scientific
> urban legend. Biochemically and structurally, of course, it ->is<- turtles
> all the way down--there is very little random about cellular structure and
> dynamics at any level.

Ahh.. I recall hearing the "Turtles all the way down" quip being
attributed to an Indian "swami" who, being asked about the structure
of the universe, and replying that the world was a plate carried on
the backs of four elephants, was asked what the elephants rested on.

He replied that they stood on the back of a giant turtle.

On being asked what the turtle stood on, he got annoyed and replied...
"Its turtles all the way down".

Actually, I rather like the "TATWU,T" re-quip :)

Recursion appeals...

---
**********************T***H***E***L***E***M***A**********************
 44. For pure will, unassuaged of purpose, delivered from the lust of
    result, is every way perfect. -- LIBER AL vel LEGIS
******************************IN*LVX*********************************
Stephen Wray <swra01@cs.aukuni.ac.nz>
Department of Computer Science,phone: x8359, fax: +64 9 373 7453
University of Auckland, Private Bag 92019, Auckland, New Zealand.

shelmrei@nmsu.edu (Stephen Helmreich) writes:



>John Robert Ross uses it as the Fragestellung of his 1967 Dissertation
>on "Constraints on Variables in Syntax" and notes that "The anecdote
>is told of William James.  I have been unable to find any published
>reference to it, so it may be that I have attributed it to the wrong
>man, or that it is apocryphal."


There are lots of modern references to this type of story around.
For instance, I believe that I saw it in Sherry Turkle's
contribution to Graubard's (1988) The AI Debate (MIT Press).

The story itself, though, is very old.  It probably can be traced
back to the creation myths of native North Americans.  For example,
in the creation myth of the Hurons and the Iroquois, all that exists
is water and the animals that live in and on water, including the
Great Turtle.  When a divine woman falls to the world, she is placed
on the back of the Great Turtle, who sends the other creatures one
by one to dive to the bottom of the sea to find some earth.  When
some is eventually found (in the version of the legend I have, it
is found by Toad) and given to the woman, she places it around the
shell of Great Turtle, and it forms the beginning of dry land.
"On all sides, the land grew larger and larger, until at last it
formed a great country, one where trees and other plants could live
and grow.  All this country was borne on the back of Great Turtle,
and it is yet today.  Great Turtle still bears the earth on his
back" (Clark, 1960).

I found this in Clark, E.E. (1960) Indian legends of Canada. Toronto:
McClelland & Stewart (reprinted as a paperback in 1992).  Clark's
version of the myth was recorded in 1874, north of Lake Erie, by
a 75-year old Huron sub-chief.  When he told the story, he noted that
he had first heard the myth from the elders of his people when he
was a youth.

So, I suspect that the notion of "turtles all the way down" predates
Hawking's book by a long time, though his book can be used as a
citation.  BTW, Turkle's version of the anecdote is presented much
more positively than is Hawking's.
--
Michael R.W. Dawson                       email: mike@psych.ualberta.ca
Biological Computation Project, Department of Psychology
University of Alberta, Edmonton, AB CANADA T6G 2E9
Tel:  +1 403 492 5175   Fax: +1 403 492 1768

HARRY R. ERWIN (herwin@mason1.gmu.edu) wrote:
: I have questions in my mind about the currently popular research into
: quantum non-locality in neural systems. However, I do know of mechanisms
 < stuff deleted>
: tuned system. Once at the level of 10,000-40,000 neurons, the next few
: stages up (leading to the entire brain) are currently the subject of
: active research. So it seems the turtles do extend down to the synapse. 
: Has there been any study of structured dynamics within the synapse? 
--

  Hmm...  When descending between levels, beware of the M.C. Escher
"strange loop" phenomenon, as in the Endlessly Rising Canon described
so well in _Escher, Godel, & Bach_ by Hofsteader.  Transitivity is only
meaningful in tensors of rank 0, ie, scalars.  Your neural nets models
may be purely electrical, but the wetware also has multiple other routes
of communication between parts, including chemical, magnetic, and
possibly gravitational, not counting true quantum mechanical effects
and "action at a distance". 

  In short, regardless of mechanism, don't forget to also check the 
case where the turtles, ultimately, form a strange loop and end 
up standing on themselves.

  wade
-------------------------------------------------------------------------
R. Wade Schuette                        Internet: schuette@eecs.umich.edu
Ann Arbor, MI 48105 USA                 voice:  313.996.7479 (work)
-------------------------------------------------------------------------

        

I heard the "Turtles all the way down" remark attributed to an
audience member at one of Bertrand Russell's lectures, for what that's
worth.
 Lisa Harris

The "Turtles all the way down" quote, as commonly referred to, comes from
Lewis Carroll.  "Goedel, Escher, Bach" may be the path through which many of
us youngsters have become familiar with it.  There are seminal books whose
fruit is the number of individauls drawn to a subject.  One needs to remember
that authors are themselves drawn to a subject and they are likely to refer
to these seeds.

-- 
--gary forbis@u.washington.edu

A reductionist would say that a turtle is elementary particles all the
way up. A biologist, by contrast, would probably prefer the quote the way 
that it is written: that to understand the system, you have to understand its 
high level functionality and, at best, the dynamics which this imposes meets 
the substrate related stuff half way a hierarchy of ordering. An evolutionary 
dynamicists (if such a job title exists) would be concerned with the involute 
complexity which led this actual hunk of matter to be where it is at this 
particular moment, seeking the most parsimonious solution and falling closer to 
the biologist that the reductionist. More "Turtles is where it's at, right now, 
man, but all is flux; like, wow, man. Deep."

_________________________________________________

  Oliver Sparrow
  ohgs@chatham.demon.co.uk