Thanks, John, that's an excellent point. Information should not be objectified as seems to be presently happening in physics. Not only does the world change but also observers change.

cheers,

Heraclitus

In regard to the article by Brukner and Zeilinger:

"...interference fringes arise if and only if there is no possibility, not even in principle, to determine which path the particle took. And, most importantly, it is not relevant whether or not we care to take note of that information [i.e. path information?]. All that is necessary is whether or not the information is present somewhere in the universe. Only if such information is not present do interference fringes occur.

Indeed, the most interesting situations arise if the path information is present at some point in time, but deleted or erased in an irrevocable way later on. Then, as soon as that information is irrevocably deleted, the interference fringes can occur again." [Č. Brukner & A. Zeilinger, Quantum Physics as a Science of Information, in 'Quo Vadis Quantum Mechanics?', edited by A. Elitzur, S. Dolev, N. Kolenda, (Springer, 2005), p48]

This is an example of the kind of muddied thinking that can happen when information is objectified. The first statement is correct, although I'm not sure what "even in principle" can actually mean. The wording that betrays the inbuilt assumption regarding information is "deleted or erased". This type of thought would never occur in classical physics (which existed before computers). Image trying to delete the "path information" of a planet! What 'path information' must mean to be physically real is some observable physical trace or record resulting from the changing location of an object. An observable causal effect of some sort--the wake of a boat, for example. In terms of a planet, it might be an influence on the paths of other planets. Or, it could be a series of observations of apparent position, from which orbital position is calculated on the basis of (Newtonian) theory--in both cases in regard to some (artificial) reference frame. What would it mean to "delete" or "erase" such information? Does it mean to erase the path itself, the influences it had, or the human record of it? In the computer age, we are used to deleting information from files. We are not obliged to think about the correlated physical changes occurring in the computer hardware, the physical "path" of that information.

It is a mystery to me what the last statement can mean. If information means causal effects (rather than stored bits), even if it were somehow possible to undo these effects that have already occurred, this would not rewind time and undo the path that was actually taken by a given particle. We can change the circumstance for future particles (by opening of closing the slit), but this has nothing to do with information, unless it is the information about the state of the slit.

--Dan

Thanks, John

Your further observations on temperature are very enlighteningl. I'll have a look at the article you mention. If this were just a physics discussion, I probably wouldn't have much to say!

--Dan

  • [deleted]

  • Post #30

Dan,

Too true. Observation is change.

One of the sources of some of my insights come from complexity theory and its dichotomy of order and chaos, with complexity as the mediation. I have adapted it somewhat though. To me it is more order and energy. It is just that energy tends to interact with order/structure at its weak points. The crack where the water and grass come through. The splits in the bark where the tree expands. The Tunisian fruitseller setting himself on fire. The places most studied and observed are also the most rigid and formalized. It the places where there is less organization and rigid structure which are most open to change and the energies initiating it. Once a system becomes so completely formalized that it cannot accept change and the energy manifesting it, that it therefore cannot continue to grow, that it becomes a closed set and can only lose energy.

The past is inherently ordered, while the future is inherently chaotic, yet the energy moves onto future events, as the structure of the past fades away. The present is that complex intermediation of energy and order. Energy moves to the future, as information moves to the past.

More on Brukner & Zeilinger:

"In order to obtain interference fringes, one has to erase the information carried by the [scattered] photon in an irrevocable way. That can best be done by detecting the photon, not in the image plane, but in the focal plane of the lens... [since] a point in the focal plane of a lens corresponds to an incoming momentum (or direction) on the other side of the lens. Thus it follows that registration of the photon in the focal plane projects the state of the scattered photon onto a momentum eigenstate which does not contain any position information. Therefore, once the photon is registered in the focal plane, all position information is gone and the corresponding electron interferes with itself." [Brukner & Zeilinger, op cit, p50] It is true that a photon registering in the image plane (for example on a photographic plate) gives position information only, and no momentum (direction) information; whereas, the same photon, if registered in the focal plane, would give direction information only, and no position information. (This is true whether you think of photons or wave fronts.) In either case, however, in being registered the photon is absorbed and has no further path! The part about projecting into an eigenstate is standard quantum mumbo jumbo to describe this optical situation. However, it subtly adds in the notion of information as a kind of substance "contained" in the state or "carried" by the photon. This substance is then supposed to have the causal power to prevent or allow interference, depending on its presence or absence. Information is being treated somewhat as heat was before the kinetic theory (i.e. 'caloric'). I submit that this is nonsense. --Dan

Final remarks on Brukner & Zeilinger:

"It has not escaped our attention that our way of reasoning also leads to new possibilities for understanding why we have quantum physics. i.e., for answering Wheeler's famous question: Why the quantum? Identifying systems with the information they carry, we note that information is necessarily quantized. One can have one proposition, two propositions, three propositions, etc., but obviously the concept of, say, √2 propositions is devoid of any meaning. Therefore, since information is quantized that way, our description of information, which is quantum mechanics, also has to be quantized." [Brukner & Zeilinger, op cit, p59] This reasoning simply begs the question (why the quantum?). Information is quantized by definition, because that is how it has been defined (e.g. by Shannon). To say that the world is quantized because we have defined it to be so is hardly a physical answer to the mysteries of the micro realm. It is simply one more idealist cop-out, attempting to reduce physical reality to human terms. --Dan

All thoughts of analysis are based on leverage due to evolution with the stick. Plato's very own postulate of 'knowing the lever..' is a truism of many worthy attributes, but now with added irony.

5 days later

  • [deleted]

  • Post #35

Major propositions in physics connected with notion"the same"

for example:

1.Einstein's relativity of simultaneity. The same time doesn't exist...

2 Heisenberg's uncertainty. The same time can't to measure....

3.Pauli's exclusion principle. The same energetic level only one fermion....

It seems to me very interesting.

Somebody thought of that?

7 days later

James Gleick's quote, that "The universe computes its own destiny." is true. A more interesting observation is that it appears to take just as long to perform this "prediction" as it does for the events to unfold. This has a direct bearing on the question of determinism and free will. Absolute determinism states that free-will cannot exist, since, in principle, all events can be predicted before they happen. But that conclusion is based on a false assumption. In order to make such a prediction, one needs to possess more than just the equations of physics, one also needs to know all the initial conditions. But the information content, and hence the storage requirement for the latter is astronomically larger than the former. Nothing in the universe, including the universe itself, has a large enough memory capacity to store this amount of information "symbolically". But the universe can do it "non-symbolically", by merely being itself. In other words, it is an analog computer, not a digital one. And it is its own analog. It "predicts" all its future activity by simply doing it. Thus, the prediction and the event are one and the same thing. Consequently, the prediction can never occur before the event, whenever the event in question actually requires all the information content of the universe in order to make the prediction; and only the universe itself has the capacity to do even that.

Dear Robert McEachern,

You say, "Nothing in the universe, including the universe itself, has a large enough memory capacity to store this amount of information "symbolically". But the universe can do it "non-symbolically", by merely being itself. In other words, it is an analog computer, not a digital one. And it is its own analog. It "predicts" all its future activity by simply doing it. Thus, the prediction and the event are one and the same thing"

I have said almost exactly the same thing a number of times, so of course I agree with you completely.

Edwin Eugene Klingman

6 days later

  • [deleted]

  • Post #38

Dan

Could you please drew attention to my essay

http://fqxi.org/community/forum/topic/1413

19 days later

Greetings Dan,

I thoroughly enjoyed your essay. We agree on many arguments you make. I too have concluded we simply cannot know the truth of 'what is' the Universe. And compared this with knowing another person truly. We can only know ourselves and our measurements of 'what is'. Any attempts to model 'what is' I characterize as 'metaphysical' and argue will ultimately fail!

And because we agree, I ask you to read my essay, "The Metaphysics of Physics", to see for yourself! In it, I have included a reference to you. Please comment and rate!

Best wishes,

Constantinos

  • [deleted]

  • Post #40

Hi Dan,

I really liked your essay, especially how you go about drawing the distinction between data and information. Many physicists have long decried the misappropriation of the word 'quantum' by mystics, etc. Isn't today's misappropriation of the word 'information' quite ironic then? I hear you.

- Shawn

Dan,

I just read your essay, which I found very well written. A couple of things came to mind:

1. I agree that it's optimistic to expect nature to have a bottom to its complexity. Nevertheless I, and many other people, like to speculate about what such a fundamental level might be like if there were one. I think this is OK because physics is inherently optimistic; we assume we can make some sort of sense out of the world. Once you grant yourself that, there is no limit to human ambition. However, each recent generation of scientists has made fools of themselves by assuming they were near the bottom!

2. I would hope that we as humans can modify our thinking and approaches to nature in response to what nature throws at us; in other words, I would like to think that physics is more about our ideas being modified by what we learn than about us trying to put nature into a straitjacket. Quantum theory, for instance, was mostly forced on us by observation. The human insistence that the world be commensurate with rational thought, which you view with skepticism, seems to me like a moving target, because our ideas of "rational thought" in relation to science change whenever nature hits us with something we don't expect. Of course, it's possible that humans may be incapable even of asking the important questions; we'd never expect a rabbit to be able to ask the important questions, and are we really different from a rabbit in the grand scheme of things? I think so, but my view is hardly unbiased.

Anyway, it was a great read. Take care,

Ben Dribus

    • [deleted]

    • Post #42

    Dear Dan, i think the underlying reason for Zeilinger et al. to state the world to be quantized is not because of Shannon, but because of the underlying logics with which we neccessarily must operate in this world. You can't say X and NOT-X are true at the same time (for example X exists and at the same time does not exist).

    I gave you a positive scoring, because your essay is well elaborated, interesting to read and inspireing to me.

    All the best,

    Stefan

    5 days later

    Dan,

    You were way too low in the rankings. I just kicked you up much higher and hope that more people will see your essay and reward it.

    Edwin Eugene Klingman

    • [deleted]

    • Post #45

    The computer and the universe

    John Archibald Wheeler

    Abstract

    The reasons are briefly recalled why (1) time cannot be a primordial category in the description of nature, but secondary, approximate and derived, and (2) the laws of physics could not have been engraved for all time upon a tablet of granite, but had to come into being by a higgledy-piggledy mechanism. It is difficult to defend the view that existence is built at bottom upon particles, fields of force or space and time. Attention is called to the "elementary quantum phenomenon" as potential building element for all that is. The task of construction of physics from such elements is compared and contrasted with the problem of constructing a computer out of "yes, no" devices.

    Preparation for publication assisted by the University of Texas Center for Theoretical Physics and by National Science Foundation Grant No. PHY78-26592.

    http://www.springerlink.com/content/ck753337h0515573/

    Dear Dan,

    If the world turns out to be Turing-computable (that is, in principle, possible to be carried out by a Turing machine), we would know there is a computer program that actually carries out exactly the same computation if our universe and no exhaustive modelling of the natural world would further be needed, unless you mean by that that the only way to account for a specific natural phenomenon is to actually run the computer simulation in order to see what happens. This would be very challenging to do so in practice as the simulation may require the same amount of resources than the universe took in order to reach that configuration (but it may also be the case that there is faster a more optimal computation).