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Information Forum

This forum area is for discussions related to the Center for Science in Society working group on Information.

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continuing ...
Name: Paul Grobstein
Date: 2004-05-25 21:13:49
Link to this Comment: 9913

Some more after the fact first meeting thoughts:

The task (I think) really is NOT to replace matter/energy with information as the foundation of physics (or anything else), but rather to find a way to think of matter and energy (previously fused) AND information as aspects of the same thing. For this purpose, it may be useful to think of "information" as the non-randomly distributed aspect of matter/energy (when it is so distributed). This, by itself, might be conceived (following what I think was Jim's suggestion at the earlier brown bag) as "potential" information, with usable information being, as previously suggested, whatever is transformed by a decoder. It is the latter that gives one form of "meaning" to information (this form does not depend on a "subjective" observer; a second form of "meaning" does require a "story teller"). Somewhere in all of this there really IS, I think, an important parallel to both the benefits and the limitations of the syntax/semantics dichotomy in language and, similarly, both the benefits and limitations of "formal languages" in logic and in computer science. There may also be a useful parallel in relation to a brief conversation Steve and I had after the meeting: what currently very much differentiates computers and brains is the assignment in computers of different tasks (computation, storage, energy management) to different components whereas in brains such tasks are done by all components.

The task is ALSO not to conclude that information is totally "subjective", in the sense that it doesn't exist in the absence of a human observer. My "tree falling in the forest" parallel is important but shouldn't be overstated. What is necessary for information, I'm suggesting, is a "decoder", but that decoder need not be a human brain. In this sense, "information" is different from "sound". The latter IS a construction of the brain, and will vary with variations in the construction of brains. What we're looking for in the case of "information" is a characterization that is reasonably (totally?) independent of variations in brains and, like vibrations in the air, can reasonably be expected to exist whether there are brains around or not.

Finally, I'm very much intrigued by the notion that an inquiry into information may also require a reconsideration of, perhaps even a synthesis with understandings of, time. The notion that a physicist's conception of time (to say nothing of most historians) is a construction of the brain intrigued by a year or so ago. And in a language group meeting shortly after I asserted quite seriously that the brain is "temporally flat", and hence that both past and future are necessarily "stories" to make sense of what currently as and prepare for what comes next. So Hartle's suggestion that time may relate to information processing makes a lot of sense to me. At the same time, I think he jumps the gun (as I said) by setting his argument in the context of the "experience" of time. The deeper question, as I see it, is whether time relates to information processing in some more fundamental, non-observer-dependent sense. And .... I think it must. My argument that the brain is "temporally flat" actually extends to "reality". We know of nothing anywhere in science that creates causal links between different locations in time except the present. To put it differently, a "past" event can (so far as we know) influence the future if and only there is some trace of it in the present. Similarly, we know (so far) of no way a "future" event can influence the present or (hence?) the past.

These characteristics of time feel to me much more like the kind of iterative input-output processing that we've talked about in the emergence group than they do like the orthogonal dimension notion of time used by physicists. And, associated with this is a challenge to the notion of "reversibility" that physicists also tend to be attracted by (why?). Many (most?) information processing steps are non-reversible. Having replaced 3 + 5 with 8 there is no way to get 3 + 5 back; similarly replacing TRUE OR FALSE with TRUE is irreversible. And virtually everything involving threshholding (including but not limited to all nervous system processing) is non-reversible. So where does the idea that the most fundamental processes are best described as reversible using time as a location come from, and why does it work so well in the cases where it does? In what way are they different from other cases where the idea is far less obviously relevant?

pushing a little harder
Name: Paul Grobstein
Date: 2004-05-26 07:49:27
Link to this Comment: 9914

Shannon can't deal with a question like what is the information content of a real number (or an integer or any element of an infinite set)? Assuming all elements occur with equal probability, the number of bits is ln infinity, which is either infinity or undefined? And if one occurs with twice the probability of the others, its information content is twice infinity (or undefined) which is the same as the others?

Maybe continuous equations with time as a parameter are a special case of a more general iterative mathematics? Does such a mathematics exist? Under what situations does it resolve into continuous equations with a single time-like parameter? What situations in the "real world" would make such a resolution useful?

re von Baeyer
Name: Paul Grobstein
Date: 2004-06-01 21:48:05
Link to this Comment: 9983

Inspired by Steve's synopsis / our discussion, I went back and reread Chapters 1-4 of von Baeyer. Herewith some resulting thoughts:

Chapters 2 and 3 do indeed make a case for information as related to organization/form/relationship, ie "non-random assembly of matter/energy". And they includethe idea of some kind of active transfer, rather than a passive property. At the same time, there is some tendency to try and treat information as something else, "the irreducible seed from which everything else grows" (p xiii). And a serious neglect of decoders (as on p 26, "... the form of the music - has survived intact").

As Steve said, and is quite apparent on rereading, the book is a physicist's approach to the problem. This is true both in motivation (the chapter 2 title, "Why information will transform physics") and in style. The belief that one has to work from the bottom up (a positive example is the notion that temperature was measured long before it was understood) and that quantification/measurement/mathematics is central is apparent. Where this is most striking is in Chapter 4 where limitations of Shannon are noted but alternative formalisms are not explored along the lines we did at the end of the session today.

I was impressed (again) by the von Baeyer/Feynman notion of data compression, ie that the atom notion (or Newton's laws or Einstein's equations etc) "contain lots of information". Actually, I think there's a caveat needed here: they don't so much contain lots of information as lots of predictions. Whether those are actually "information" (at least "new" information) requires first the expansion and then the testing of those expansions against new observations (to the extent they summarize old observations they do indeed contains lots of "observations", but "information"?).

Regardless, the compression business inclines me to suggest an appropriate modification in the early suggested decoder approach to information. Perhaps it is not enough for a decoder to simply map from one set of non-random matter/energy distributions to another. Perhaps it needs to do so in a way that a way that has a many to one character, ie that produces a compression.

Along these lines, an interesting issue is the idea of "faithful" compression, ie a reliably reversible one. My guess is that the reversibility of compressions (like information itself) is cryptically dependent on presumptions about available decoders (context). To put it differently, my guess is that compression is generally irreversible to one degree or another (and this may link to issues of time and indeterminacy).

on being "unfaithful"
Name: Anne Dalke
Date: 2004-06-08 20:04:52
Link to this Comment: 10072


(Today's follow-up query:
if "hello" is used for in-face conversations,
and "ahoy" was once a candidate for telephone-greetings,
what is the appropriate salutation for on-line postings--
the one which the decoder can't help but "get"?)

Okay, getting serious, trying to get all this (very impressed w/ today, Eric...). What I saw you doing, first, was offering a clear/compelling counter to the "root" definition of "information" which von Baeyer, via Steven, gave us last week ("the imposition of form onto something): Bregman's claim that "the way that sensory imputs are grouped by our nervous systems determines the patterns that we perceive" (bottom up, not top down, w/ multiple compressions along the way).

What I'm trying to understand now is whether these compressions can in any sense be said to be "faithful"(=reversible, as per Paul, above?) or are rather necessarily irreversable--but incorrectly identified as "unfaithful"; are rather "fruitful."

What helps me here is the really interdisciplinary work of Michel Serres, whom I mentioned this morning as being an adroit translator of techniques from the fields of literature, philosophy, science and painting into a new theory about (among other things) "The Origin of Language." In the essay of that title (the subtitle of which is "Biology, Information Theory, and Thermodynamics"), Serres proposes that we think of each level of this interlocking series of information-processers as integrating "the information-background noise couple that was given off at the preceding level." As what functions as an obstacle @ one level is incorporated into information @ the next, each new level is operating as a filter or "rectifier" of noise. Serres uses the metaphor of a series of chemical reactions @ different temperatures to describe this process; he also quite compellingly (to me) suggests that we might understand each level of information as functioning

as an unconscious for the global level bordering it.... when [the noise-information couple] crosses the edge...the subsequent system decodes or deciphers...residual background noise is progressively eliminated....packages of chance are filtered, level after level....The traditional view of the unconscious would seem to be the final black box...Beyond it we plunge into the cloud of meaningless signals. Perhaps this box protects us from the deafening gasps of the stochastic....In this way...common functions of psychoanalysis could be rewritten in terms of a physics of energy and a theory of signals...

In another of the essays collected in Hermes: Literature, Science, Philosophy, Serres adds the very cute (=potentially useful to us?) notion that

communication is a sort of game played by two interlocutors considered as united against the phenomena of interference and confusion...they are in no way opposed...; they are on the same side, tied together by a mutual interest: they battle together against noise...struggling together against a common enemy. To hold a dialogue is to suppose a third man and to seek to exclude him; a successful communicaton is the exclusion of the third man....By his inclusion in the circuit, the third man blurs the message and renders it unintelligible; by his exclusion, he renders it intelligible and assures its transmssion.

[Here comes the punch line, at least for those of you interested in thermodynamics:]

According to the editors of Hermes (Jose Harari and David Bell), Serres calls this included/excluded third man the "demon" (!), or a "parasite,"

an operator that interrupts a system of exchange. The abusive guest partakes of the host's meal, consumes food, and gives only...conversation in return. The biological parasite enters an organism's body and absorbs substances meant for the host organism....(noise or static in information theory in English is translated as parasite in French). Thus the parasite first presents itself in a negative guise, is viewed as malfunction, an error, or a noise within a given system. Its appearance elicits a strategy of exclusion....By experiencing a perturbation and subsequently integrating it, the system a more complex stage....

[in other words, it is actually noise that generates the need for compression and the next level for interpreting it]

Thus, by virtue of its power to perturb, the parasite ultimately constitutes...the condition of possibility of the system. In this way the parasite attests from within the primacy of disorder; it produces by way of disorder a more complex order.....Order is not the law of things but their exception....One must rethink the physical universe...the transformational universe of thermodynamics, and the informational universe of noise according to a founding disorder and its power to modify reality....

Okay: got all that--I think, including what it is that motivates us to pay attention. (One of Eric's sticking points was that "attention plays a very important role in these processes...but I don't know anything about attention.") The studies he mentioned, as demonstrating that children "get excited when they are shown something new," could well provide a clue here. This, too, is the core idea of a great novel I've just finished reviewing for my CSem on Storytelling this fall: Jonathan Lethem's Motherless Brooklyn, in which a man w/ Tourette's Syndrome proves to be a particularly excellent detective precisely because he is obsessively attentive to quirky (="new"?) details that others dismiss as noise, and thereby enabled to turn them into useful information...

And THIS (finally) puts me in mind of what I thought was my fuddy-duddy literary distinction, last week, between (arbitrary) "sign" and "symbol" (which partakes of that which it symbolizes--the cross for Christianity, for example). Maybe the various levels/layers of compression might (in my language) be understood as the movement from sign to symbol, the making, via compression, of something meaningful out of something that, on a first pass through, seems unrelated to the larger whole. Not unfaithful, then, but becoming (not so curiously) MORE faithful--and certainly more fruitful.

Concluding anecdote: My son Sam has been doing some yard work. He asked me the other evening whether or not he should pull up some (unidentifiable-by-us) plant. I said, "Let it grow. It might be a flower." He said, "If I don't know what it is, it's a weed. I pull it up." Is this a male/female, science/humanities divide, splitter/lumper divide? If he doesn't know what it is, he throws it out. She saves it, because you can never know what might be useful one day. ....

Enough--though participants in this seminar may want to take a look @ Serendip's site map and some of Ann Dixon's observations about its structure (which I pass on w/ her permission); they might help nudge us to some larger (or finer) principles; see

Thanks Ann, thanks Eric, thanks all.

entanglement...requiring rectification?
Name: Anne Dalke
Date: 2004-06-11 12:08:49
Link to this Comment: 10097

Picking up on the invitation to post here "thoughts about any given discussion (or anything else that seems relevant)"....I find it hard to keep the forums of all these working groups straight; the various topics have a way of (randomly? not-so-randomly?) connecting, of weaving themselves into a somewhat entangled and not-yet-coherent pattern in my (ditto) brain....

For instance, a book review recommended by Roland Stahl in the Graduate Idea Forum led me back to the forum for the Symposium on Beauty, which seemed to anticipate, in different language, our searching together here for a theory of information that operates through a range of ever-more "rectified" levels.

See, for instance, these two comments from the Beauty forum about the movement from disorganization to organization--

thank you for the talk tonight:
i was really excited about your idea that beauty is found in the movement from dissorganization to organization....[that the] process of moving from organization to dissorganization ..could beauty...

and Sought: The Grand Unifying Theory of Beauty:
a beautiful thing is a plateau were things look (momentarily) understandable, but which "sows the seeds of its own destruction, opens the door for something else"--and is powerful precisely because it holds this sort of promise. (Category A, presumably, always gives way to Category B.) If that's the case, then Al's theory works nicely w/ the one Mark gave us two weeks ago, both in its insistence on the "momentariness of the experience of beauty" (because it will always be transcended) and in its ability to function on several levels @ once--or rather, in our ability to hold two worlds simultaneously in mind, a process that is only beautiful as the patterns are solving, not after they settle.

Think I'm badly in need of a rectifier.....

Poetry Police to the Rescue
Name: Anne Dalke
Date: 2004-06-16 23:24:27
Link to this Comment: 10109

okay, looks like the rectification's all on me...

I was delighted by the newness of y'day's session--the notion, primarily, that our evolving "theory of information" may need to incorporate simultaneous subtraction and addition--that is, contra physics, irreversible information loss along w/ information gain.

(I've just acquired another example of this to lay alongside Eric's information loss/gain in phonological categories and Paul's lateral inhibition in neurobiology. My daughter Lily is interning this summer @ a project in urban farming. Each night she brings home some new green for me to incorporate into dinner; tonight she brought a salad mix that included 8 kinds of lettuces and 6 kinds of greens. Halfway through dinner, we realized that we could only taste the distinctiveness of each green if we ate our salad one leaf @ a time; we tasted a mouthful of 6 or 8 distinct greens as one indistinct blend. So...there's some sort of "lateral inhibition network" operating in/among our taste buds, too?)

The significance of this simultaneous loss/gain only came clear to me when, at long last, George went to the board y'day morning and demonstrated how (in a series of mathematical equations I couldn't follow, but explanations I could...) the process of categorization is a function, a process of converting/transforming one set to another. Most striking, to me, was George's idea that the only interesting categories are those in which not an identity, but a likeness (="equivalence") is noted among individual items, which are then "collapsed" into fewer groupings than the originals. If everything is unique (=not collapsible/groupable in a category w/ other "like" things) then, as per Eric, "you can't get an explanation": you have no comparison to reason w/ or come to understand. In thinking about the "transformation that is information," then (thank you George) "1-to-1 mappings are trivial", a.k.a. "categories with 1 object in them are useless."

Now, to keep you scientists honest, just one bit of fine point here...

On a totally wierd--not intended to be informative OR educational--website called Rose is a rose is a rose... you'll find a good explanation of why Paul's use of a line from Gertrude Stein doesn't quite work as an example of this process of "addition, w/ resulting creation of something not otherwise there" (in other words, that "no rose is there until an observer has a particular category schema of 'rose' to apply to what she sees").

When Margaret Thatcher belted: "A crime is a crime is a crime is a crime...", she joined ranks with those [who don't know that] G.S. didn't use the phrase: "A rose is a rose is a rose is a rose..." What she actually wrote was: "Rose is a rose is a rose is a rose...," meaning the girl's name and comparing it to the flower.

Meaning: that one thing was interpreted here in terms of another, that the word-category "rose" in Stein's line had two items in it--the girl and the flower-- and that the former was being explained in terms of the later. In George's language, this is one of those categories that does NOT map 1-to-1, and is interesting precisely because it does not. There is an equivalence relation, not an identity one, between the two items, and the fun here is figuring out just what the likeness consists of....

The Poetry Police

Name: Eric Raimy
Date: 2004-06-22 09:17:59
Link to this Comment: 10116

This is a quote from Gallistel (1980) "The Organization of Action" which I think is relevant to our discussion about the 'reversibility' of functions.

"For example, the analysis of insect walking in Chapter 5 clarifies the manner in which hierarchical organization resolves what Turvey (1977) calls the degree of freedom problem. Roughly speaking, the degrees of freedom problem boils down to the problem that the higher levels cannot possibly be bothered to instruct the lowest levels exactly how to carry out a required action, such as walking. There are too many slightly different circumstances. The higher levels must in some sense issue a simple walk command, leaving it to lower levels to determine exactly how the business of walking shall be carried on from moment to moment. Chapter 5 shows in some detail exactly how this conception is put into practice in the walking of insects. A very similar analysis of walking applies to the cat (Pearson 1976), so the principles particularized in Chapter 5 appear to be quite general"

Out of the puddle, into a hole
Name: Anne Dalke
Date: 2004-06-23 14:22:51
Link to this Comment: 10118 off here on the side a little bit, paddling about in my own small puddle, thinking about what the construction/reception of literary texts might subtract from/add to our conversation about the necessary loss (and addition) that goes into information-construction, and w/ it the inevitability of irreversibility...wondering what the study of literature has to contribute toward this very particular project of defining a new theory of information. Would it help us to think about those things--literary texts--which are (classically) defined as NOT being the conveyers of information?

Basically, my thoughts are branching in two (looks like opposite?) directions.

My favored version of the varieties of literary theories floating round these days is reader-response theory, which fits quite nicely into the notion of information-as-relation: the text occurs in the interaction between the writing and the reading; it comes into existence when it is read.

This is complicated considerably, however, by the very basic/classic idea that the primary value of literature is not the practical purpose of communicating information. As William Paulson says in The Noise of Culture: Literary Texts in a World of Information (1988), what is "irreducably literary" never coincides w/ "what is sent": "The nonpoetic part of the message is something that we already know" (i.e.: we don't go to poetry for news). Why do (some of us) go to it, then? In a long-ago forum on The Two Cultures, a sharp distinction was made between scientific texts (designed to be precise, to transfer information, to be decoded in a single, unambiguous way), and literary language (intentially more ambiguous and playful IN ORDER to evoke a wide range of responses, interpretation and dialogue). (N.B.: ordinary everyday language plays @ both ends of the spectrum, and we often misunderstand one another because it does so--we get confused when we are TELLING someone something, and they misinterpret us as INVITING a response!).

As Paulson observes, literary studies is the one field where we examine the text TO KNOW THE TEXT (vs. sociology or physics, where you read the text to know the referent, as a pointer towards something "extra-textual"; in Liz's terms, "to hear what the world is telling us"). Where this might be helpful in our search for a new theory of information is in the notion that it is literature's failure to communicate information that actually becomes the vehicle for new information : that is, taking the time to interpret (what the rest of you would dismiss as) "noise-- "why are the words arranged in that order, w/ that cadence, those rhymes?"--is a very useful method for promoting the generation of new information. As Wallace Stevens said,
"...speech is not dirty silence
Clarified. It is silence made still dirtier."

On the other hand: I'm intrigued by the possibilities for thinking generated by the sort of literature which refuses to make choices, refuses to do the "squeezing" that our (currently operative) definition of information insists upon. This other (quite contrary?) line of thinking has to do w/ the fairly recent phenomena (accelerated by the capacities of computer technology) of the generation of hyptertext. A pre-computer/classic example of this is the work of Jorge Louis Borges, esp. his short story "The Garden of Forking Paths," which observes that "in all fictional works, each time a man is confronted with several alternatives, he chooses one and elminates the others; in [this chaotic work] he chooses--simultanously--all of them. He creates, in this way, diverse futures, diverse times which themselves also proliferate and fork."

As Italo Calvino (also the writer of many hypernovels) explains, "the central idea of the whole story is a manifold and ramified time in which every present forks out into two futures so as to form a growing and bewildering network of divergent, convergent, and parallel forms of time. This idea of infinite contemporary universes in which all possibilities are realized in all possible the very reason why the protagonist feels authorized to carry out [a murder]... perfectly sure that...if he commits this crime here and now, in other universes he and his victim will be able to hail each other as friends and brothers."

If more conventional fiction constructs a strong narrative precisely by making such choices (i.e., by giving up on alternative possibilities) hypertext explicitly refuses to make such decisions, refuses to "lose" any information...

maybe it is so unsatisfactory precisely for that reason?
We NEED the loss...
in order to gain...

Not sure whether I've just talked myself into or out of a hole.

notes from a conversation with Jim
Name: Paul Grobstein
Date: 2004-07-02 16:01:04
Link to this Comment: 10281

"Paradoxes", in the Russell sense, are CREATED by formal axiomatic systems. Such systems allow sentences that
  1. have because of their internal structure, along with self-referentiality, no "resolution" into True or False.
  2. are "poorly linked" to other allowed sentences, ie neither they not their negations can be inferred
Are these the same sentences or different?, ie are there TWO problems with FAS or just one?

The "halting problem" is closely related to "indeterminacy", ie computers go into infinite loops when a set of instructions has an indeterminate outcome.

notes from a conversation with Jim
Name: Paul Grobstein
Date: 2004-07-02 16:52:58
Link to this Comment: 10282

"Paradoxes", in the Russell sense, are CREATED by formal axiomatic systems. Such systems allow sentences that
  1. have because of their internal structure, along with self-referentiality, no "resolution" into True or False.
  2. are "poorly linked" to other allowed sentences, ie neither they not their negations can be inferred
Are these the same sentences or different?, ie are there TWO problems with FAS or just one?

The "halting problem" is closely related to "indeterminacy", ie computers go into infinite loops when a set of instructions has an indeterminate outcome.

Name: Anne Dalke
Date: 2004-07-06 17:48:59
Link to this Comment: 10356

...w/ a little background grumbling here regarding a '"lost" posting
(in retrospect, irreversibly superior to this one....)

Formal systems create and then (I have this right?) can't tolerate the paradoxes they have created? Thus distinguishing themselves from literature, which generates, revels in, even exacerbates the paradoxical, the simultaneous-holding-of-two-contrary-ideas (not to put too fine a point upon it, see Keats on Negative Capability here: "being in uncertainties w/out an 'irritable reaching' for resolution").

So...might this new theory of information we're searching for (or rather, ourselves constructing....) be robust enough to generate-and-tolerate the paradoxical, the self-contradictory--if not the illogical and logically false? (As above: by relaxing the consistency requirement?)

where last week's conversation took me....
Name: Anne Dalke
Date: 2004-07-14 13:05:56
Link to this Comment: 10418

...into this experimental (what the Quakers call "experiential") revision:
Re-Writing Descartes, by Re-doing Mathematics

A Looser Grip...?
Name: Anne Dalke
Date: 2004-07-20 16:17:19
Link to this Comment: 10440

I'll be out of town for the remainder of the week, so/and will be sorry to miss this week's session. Wanted to offer, however, as my contribution/consolation, the news from late last week (my source is the July 16, 2004 Philadelphia Inquirer, so others may have more details/more authoritative info on this:

"Galactic black holes may have looser grip":

Stephen says some "information" sucked into black holes escapes over time, contradicting some of his most famous work on the phenomenon....In the 1970s, Hawking said that...a black hole...contained no information about the inside matter and once the hole evaporated, all information was lost. This however, created a paradox, since the laws of quantum physics assert such information can never be completey wiped out....He will now argue that the black holes never quite shut themselves off completely and, as they emit more heat, they eventually open up and release information.

I'd be delighted if someone (Al? Liz?) could explain to me how both claim A and claim B jive (they don't jive, do they?) w/ the assertion (from our 6/22 discussion) that physicists are actually NOT invested in reversibility....

Name: Paul Grobstein
Date: 2004-07-23 10:37:54
Link to this Comment: 10468

From the NY Times 22 July 2004 (Dennis Overbye, "About Those Fearsome Black Holes? Never Mind"):

"Stephen W. Hawking threw in the towel yesterday, or at least an encyclopedia ... The encyclopedia was the stake in a famous bet Dr. Hawking and another Caltech physicist, Dr. Kip Thorne, made with Dr. Preskill in 1997. Dr. Hawking and Dr. Thorne said information about what had been swallowed by a black hole could never be retrieved from it; Dr. Preskill and many other physicists said it could. The winner was to get an encyclopedia, from which information could be freely retrieved.

This esoteric sounding debate is of great consequence to science, because if Dr. Hawking had been right, it would have violated a basic tenet of modern physics: that it is always possible to reverse time, run the proverbial film backward and reconstruct what happened in, say, the collision of two cars or the collapse of a dead star into a black hole. "

Sounds to me like exactly the same issue we talked about in relation to whether the combustion products of two different crumbled bags were or were not distinguishable And thought we SETTLED that issue, concluding it was NOT the case that physics had/needed "a basic tenet ... that it is always possible to reverse time".

Do we or do we not need to go back to this? Is "physics" being misrepresented in the newspaper article or is there some issue at stake re reversibility that we didn't get straight?

Lindell/Grobstein on Hawking plus
Name: Paul Grobstein
Date: 2004-07-23 16:23:28
Link to this Comment: 10469

From an email exchange 23 July between Steven Lindell and Paul Grobstein:


I think you got it wrong (I'm sorry I could not have been there). Although thermodynamics implies macroscopic ensembles may be irreversible, this is only practically. In theory, all the movements of all the particles in the system obey mechanics, classic or quantum. These microscopic laws are entirely reversible in time. It is a very subtle and elegant point. 

Whether these laws still hold at the boundary/singularity of a black hole is the big argument. A good article to look at is "Black Holes and the Information Paradox" which appeared in Scientific American in 2003. Stephen Hawking also discusses it at length in his popular books.


Steve -

Could indeed be wrong, is part of how I work, and I'd rather discover it now then after I've built something that fails because a piece is bad. THINK, though, that we walked through this. Can of course STILL be wrong, is why I want to go back and get it cleared up. If possible, since it seems to have been unresolved/troubling people as far back as Poincare.

Am not worried about black holes (interesting as they may be to Hawking and others), nor even about whether physicists have found and continue to find it useful to describe some sorts of observations in terms of time symmetric, reversible interactions/processes. What I am worried about is the idea that time symmetry is "a basic tenet" of physics. And even that doesn't bother me so long as "basic tenet" is understood to mean "something that physicists have found/believe they will continue to find useful in making sense of things". Its if "basic tenet" means "something that if changed would call into question very large amounts of what has so far been successfully understood" that I'm concerned and, in that case, I want to know what exactly would be challenged and how.

The (narrow) concern arises because I (tentatively) think that irreversibility is a fundamental aspect of "information processing" and I (much less tentatively) think that information-processing is a physical process and so can't go on in any way that can't be conceived of in terms of existing physics. I certainly admit the possibility that trying to understand "information" might require physicists to deeply change how they think about matter/energy, but the information inquiry isn't even remotely far enough along to even suggest that. Hence, for the moment, I'd like to stay consistent with physics insofar as it seems relevant.

So, here's where I THINK we are. Al says that there are at the moment some violations of time symmetry familiar to and acknowledged by physicists. And that the relation between mechanics (classical AND quantum) and the second law of thermodynamics has bee/continues to be a source of disagreement within the physics community (see also Tony Rothman's Time talk); ie it remains an admissible interpretation in that community that increasing entropy actually DOES involve an information loss rather than simply APPEARING to involve an information loss because of observer "coarse graining". Moreover, there seems to be a quite acceptable way to think of quantum mechanics that DOES involve information loss, not in the evolution of the wave function itself when undisturbed (which is indeed described by time symmetric equations) but associated with the collapse of the wave function necessary for connecting the wave functions to the world we perceive. As Al pointed out, "Quantum measurement is an irreversible process", ie there is no way to go backwards from measurement/observation to the original wave function (the same observed value can result from lots of different wave functions"). Assuming the collapse is causally significant (ie affects the future wave function), such irreversibilities are propagated forward in wave function evolution and so are inherent in a quantum mechanical physical description.

Bottom line, I don't think the information discussion is (yet?) in serious conflict with physics. But it does APPEAR to be in conflict with journalistic summaries of the Hawking matter (by pretty careful journalists), and perhaps with some physicists? I can live with the former, but still want to be sure there isn't something out there that's going to rear up and bite us later.



I agree with you as soon as there is an observer in the process. My naive reply simply meant unobserved information, in which case the measurement process never occurs. It is simply fascinating how the observer changes this fundamental idea. I really don't know what to make of it, but am anxiously awaiting the critiques of Stephen Hawking's new work. Is it even possible that consciousness changes how we interpret physics? I don't like the sound of that.


Steven -

Not sure that the upcoming critiques of Hawking will be relevant to what we're playing with; there are problems enough in the physics to keep the physicists occupied for a while.

Glad we agree that in some sense all bets are off "as soon as there is an observer in the process", but that in turn raises the very interesting question of exactly what an "observer" is (eg, would a "decoder" suffice?).

Not surprised we also have a disagreement in taste. I, of course, like the possibility "that consciousness changes how we interpret physics" a lot. Interesting to sometime try and understand what's behind that difference in taste.


Paul -

I'm not even sure if it is a matter of "taste" but simply sleeping at night. In fact, if I'm sleeping (unconscious) does this change the laws of physics in the room from when I am awake?!


what sleeplessness gets you....?
Name: Anne Dalke
Date: 2004-07-25 13:40:18
Link to this Comment: 10473

Steven, in your I'm not even sure if it is a matter of "taste" but simply sleeping at night....

is a bait I can't help (as a life-long insomniac) but pick up.

During one of those recent sleepless nights, I was reading a text Al recommended to us several sessions back: it's Stapp's The Mindful Universe (2004). The claim, basically, is that the "peculiar sundering of nature" accomplished by René Descartes (for much more on whom see Writing Descartes), who conceived "nature to be built out of two sorts of substances: 'matter,' which was located in and occupied space, and the 'mental stuff' that our ideas, thoughts, sensations, feelings and efforts are made of...was abandoned by physicists during the twentieth century." Stapp reviews both the Copenhagen interpretation (the fundamental and revolutionary way in which the founders of quantum mechanics brought conscious human experiences into basic physical theory--per Bohr, recognizing that "in the drama of existence, we ourselves are both actors and spectators") --and Einstein's struggle, til the end of his life, to "get the observer's knowlege back out of physics," to resist "Berkeley's principle that "To be is to be perceived."

My own current (humanist's) understanding of information is that it doesn't exist w/out an observer, w/out being measured or decoded. So (for me), your "simply meant unobserved information" is oxymoronic: consciousness does change how we interpret physics. The interpretation is itself a conscious act.

Not Knowing Where He Would End...
Name: Anne Dalke
Date: 2004-07-29 11:05:41
Link to this Comment: 10520

Sorry to miss the End of Information. Thought I'd add (what is usually appropriate at the end of all "essays") two short bibliographic (actually biographic) notes. Intrigued, first, by the debate between Paul and Steven re: time symmetric, reversible interactions/processes...unresolved/troubling people as far back as Poincaré, I went that far back, read about Jules Henri Poincaré....

Didn't learn much about his views on irreversibility, but did learn a lot about his methods of working, and found in this account a vivid rendition of the iterative, recursive "brain trick" we were offered, a few weeks ago, as an alternative to formal axiomatic systems. Poincaré was nearsighted and had poor muscular coordination (I got an image here of a turn to abstract mathematics, due to difficulties in negotiating the material world)--and he wrote very interestingly about his own thought processes:

He made visual links between the new ideas he was assimilating, would start working w/out knowing where he would end, write formulas to call up associations of ideas, take up and as quickly abandon subjects, never working in the evening in order not to trouble his sleep...assuming all along that his unconscious was continuing the work of reflection when he wasn't consciously at work. I hear these descriptions, taken together, as an account of an insistently self-referential "looping" process between the logical and the intuitive.

As Poincaré himself wrote in Mathematical Definitions,
It is by logic we prove, it is by intuition that we invent.
Logic, therefore, remains barren unless fertilized by intuition.

From Nonconformism to (Im)probability
Name: Anne Dalke
Date: 2004-07-29 11:20:14
Link to this Comment: 10521

My second bibliographic/biographic note has to do with Thomas Bayes, whom I'd never heard of before last week. Having been tutored into some understanding of "the unlikelihood factor," I got interested in what sort of brain/body/life would have been drawn to such profoundly skeptical formulations. Discovered that Bayes was an 18th century English Presybterian minister who published two books during his lifetime: the first on the Principal End of the Divine Providence, the second an introduction to the Doctrine of Fluxions...

What got me curious, of course, was how he got from the first to the second; I wanted to understand the movement/the link between an argument that God's end was our happiness and one that was a defence of Newton's calculus; got even more curious to know how/if Bayes' theology informed/impelled his posthumously published "Essay Towards Solving a Problem in the Doctrine of Chances." I wanted to know what sort of universe (actually, what sort of understanding of God) lay behind Bayesian probability (as understood now--presumably more extensively than Bayes himself formulated it: "expected utility is the probability of an event times the payoff received in case of that event").

What I learned was that Bayes, like his father, was a "dissenter" or "nonconformist." What I learned was that that term, most generally, describes those who refused to conform to the "formularies and rites" of the established church. (I was also reminded that both the Methodists among whom I was raised and the Quakers with whom I now worship were Nonconformists.) I didn't learn anything specific about Bayes' theology--

but it did amuse me mightily to recognize the congruity between our discovering, at the end of this Working Group, the limits of the box (of formal axiomatic systems), our considering possible ways out of the box, including the trick of looking @ our starting points and seeing what we might change--and our doing so by relying, in part, on the work of a non-conforming minister who articulated a theory of reverse probability, a means of calculating, from the number of times an event has not occurred, the probability that it will occur in the future trials.

Final note of possible interest (presumably already known by the physicists and computer scientists among us): Bayesian inference has been used in recent years to develop algorithms for identifying spam.

A useful theory of information indeed.

End of Bibliography
Name: Anne Dalke
Date: 2004-07-31 14:06:59
Link to this Comment: 10560

Stanislaw Lem, quoted in The Mind's Eye (thanks, Doug, for the loan), gives a wonderfully elaborate description of the "brain trick" Paul offered us a few weeks ago, a vivid account of the brain as a system that is not formally axiomatic, and so offers (not to put too fine a point upon it) "an escape from the snares of Godelization":

Consciousness is in its physical aspect an "informational standing wave," a certain dynamic invariant in a stream of incessant transformations, peculiar in that it represents a "compromise" and at the same time is a "resultant" that...was not at all planned for by natural evolution....certain very old evolutionary solutions to problems of control and regulation, common to the nervous system, were "carried along"....These solutions ought to have been, from purely rational, efficiency-engineering standpoint, canceled or abandoned, and something entirely new designed....But...disencumbering itself of the inheritance often as much as hundreds of millions of years old--did not lie within its power....evolution is a dragnet 'that lugs after it innumerable archaisms, all sorts of refuse'....

What, then, is consciousness? An expedient, a dodge, a way out of the trap...a function that, once begun, will not admit of any closure--i.e. any definitive completion. It is...only a plan for such a closure, for a total 'reconciliation of the stubborn contradictions of the brain'..."Beneath the conscious" there goes on a continuous battle for full representation--in it--of that which cannot reach it in fullness, and cannot for simple lack of space; for, in order to give full and equal rights to all those tendencies that clamor for attention at the centers of awareness, what would be necessary is infinite capacity and volume. There reigns, then, around the conscious a never-ending crush, a pushing and shoving, and the conscious is...a cork upon the fretful waves...consciousness is a kind of dodge, a keeping with...opportunism--i.e. finding a quick, extempore way out of a tight corner...

In order to fashion a likeness of must deliberately introduce into the informational asymmetry, acentric tendencies; one must, in a word, both unify and make discordant....emotions...must to some extent be at odds with...reason; they must possess self-destructive tendencies....they must feed internal tensions...the logic of the creation...must...contain certain antinomies. Consciousness escape from the snares of Godelization...this solution has sidestepped the contradictions of which every system that is perfect with respect to logic is subject. So, then...

to simulate man, it is necessary that we reproduce certain of his fundamental contradictions.... only a system of mutually gravitating antagonisms...will resemble "a star contracted by the forces of gravity and at the same time expanded by the pressure of radiation." The gravitational center is, very simply, the personal "I," but by no means does it constitute a unity....(303-306)

Re: From Nonconformism to (Im)probability
Name: David Ross
Date: 2004-08-02 06:22:25
Link to this Comment: 10562

Anne's background link on Bayes suffered from a bit of dyslexia. Try

My own favorite introduction to Bayesian thinking is at

There's a nice tension in thinking about learning as Bayesian updating (incremental) or continuing revelation (allow for divine leaps of insight).

The End of History
Name: Anne Dalke
Date: 2004-08-02 22:11:25
Link to this Comment: 10566

Thanks, David, for giving us a link that works, and another that usefully (to me) calls attention to the "subjectivist" aspect of Bayes' emphasis on "prior possibilities" (vs. the "objectivist" who "doesn't state" his judgements...interesting distinction).

Thanks, too, for attending to the tension between incremental/revelatory learning (what Poincaré, above, calls the necessary "corrective" of logic by intuition, intuition by logic?)....

Speaking of what lies "above," I mentioned there earlier the short stories of Jorge Luis Borges, in which characters simultaneously choose several paths/diverse futures....

My main supplier of good reading this summer, Gerry LeChance, has just directed me to John Barthes' "The Literature of Exhaustion," wherein is mentioned Borges' (hopefully invented) "favorite third-century heretical sect," the Histriones, "who believe that repetition is impossible in history and therefore live viciously in order to purge the future of the vices they commit; in other words, to exhaust the possibilities of the world in order to bring its end nearer."

What interests me, of course, is the echo here, in literature and (imagined?) history, of the discussion, above re: the investment (or not? this is still unsettled?) of physicists in the (ir?)reversibility of physical phenomenon, the (non?)recursiveness of physical patterns....

Just for the record, according to Barth, the aim of the Histriones was "to get history done with so that Jesus may come again the sooner...." Not exactly where I am (or the Information Group was) heading, but a rather striking (?!) example of where the imagining of non-repeatable events could take us....

more on hawking/black holes
Name: Paul Grobstein
Date: 2004-08-04 14:46:07
Link to this Comment: 10590

Some more exchanges added with permission (a little belatedly ... sorry)

23 July

Paul -

The only information I have is from the NYTimes article that Jim circulated. Hawking is supposed to have said that the black hole gives back information to the universe, but in a "mangled" form. Sounds like entropy increase to me!


Paul -

Yes, you reported my position correctly. I think Steve is thinking at the Newlton's law, Schroedinger equation level. Reminding him of the irreversibiity of a quantum measurement is probably a good idea.


23 - 26 July

Hi Paul,

I think the quote you have pasted in here misrepresents what Hawking actually states about what he changed his mind about. Hawking did admit that he lost the bet and that matter can and does get out of black holes when they disintegrate. What Hawking did not say was that the matter that came out was the same as when it came in. For our purposes, Hawking says that the matter comes out 'mangled' which makes the matter unrecognizable in our world which suggests to me that 'information' can still be lost in the black hole. In fact, I don't think this part has changed at all since the matter comes out 'mangled'.

Jim's first post of this from the NYTimes has this part of Hawking's statement in it. I would go back and read that one to clear things up a bit. Also, the expert (I'm pretty sure its the guy who won the bet) that the NYTimes talked to said that he didn't fully understand the talk. Hawking's paper on the subject is coming out soon so we should wait until then to make any decisions about what we've talked about.


Eric -

Yeah, got similar email from Al. And I noted "mangled" as well, didn't include in quote because ... key question here is the same one that came up when we were talking earlier about burning crumpled pieces of paper. IF burning two different crumpled pieces of paper gives you the same thing, THEN there is "information loss" (ie you can't tell from what you get which of the two you started with). But if burning two different crumpled pieces of paper gives you two different somethings, each of which is uniquely related to the appropriate one of the two original crumpled pieces of paper, then there is NO information loss, no matter how "mangled" the products are relative to what they started as. So, "mangled" doesn't help, by itself. Need to know in what sense "mangled". And STILL need to know why Hawking (or anyone else) would CARE if something is mangled enough to lose information.

Not inclined at the moment to discount what we've talked about, just checking. But suspect we will have to settle the matter for ourselves, rather than expect Hawking's paper on the subject to do so. Isn't just a question of whether anyone understands Hawking, is also a question of whether what is on Hawking's mind (black holes?) happens to have any relation whatsoever to the "information" problem that's on ours. Could well turn out that he/physicists/journalists mean something by it entirely different from what we're worrying about, no?


I think you're right that Hawking may not be focusing on the same aspects of this problem as we are. This doesn't discount Hawking's thoughts though. I think its a matter of H not really seeing the importance of what he is saying to our discussion.

Here is the part about 'mangled' that is of direct relevance to our discussion:

"But there was a hitch, as Dr. Hawking pointed out. The radiation coming out of the black hole would be random. As a result, all information about what had fallen in - whether it be elephants or donkeys - would be erased. In a riposte to Einstein's famous remark that God does not play dice, rejecting quantum uncertainty, Dr. Hawking said in 1976, "God not only plays dice with the universe, but sometimes throws them where they can't be seen."" This is from the NYTimes article. (

Given this missing tidbit from the article you posted the query about, I think we're OK in the line of thought we pursued and are about 'less wrong' as we were before Hawking changed his mind. Black holes still destroy information. The disconnect between what we are focusing on and what Hawking and the other physicists who were disagreeing with him is that I think they lost interest in the information question and paid attention solely to whether 'stuff' came out of black holes. We have focused on the more subtle question of whether the information comes back out too. From the quote above, I think Hawking might agree with what we're doing. You should email him a link to our discussions.


Eric -

Agree issue is "mangled". But think "all information ... would be erased" is EARLY Hawking and claim now is that, albeit mangled, "information" is coming back out. Whether so or not, for us the question is still, it seems to me, why Hawking or any other physicist would care. Not inclined to worry unless/until we get a compelling answer to THAT question.


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Name: Webmaster
Date: 2006-08-08 11:04:44
Link to this Comment: 20143

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