it from bit or bit from us?
TRANSCRIPT
It From Bit Or Bit From Us?
Majid Karimi
Research Group on Foundations of Quantum Theory and Information
Department of Chemistry, Sharif University of Technology
On its 125th anniversary, July 1st, 2005 issue of Science highlighted several questions for which we do not have any answer.
Do Deeper Principles Underlie Quantum Uncertainty and Nonlocality?
How and Where Did Life on Earth Arise?
concept of
information
Brukner and Zeilinger’sinformational interpretation of
quantum mechanics
Roederer’s, pragmatic definition of information
We would like to show that
to what extent (if any) thesenew approaches (informationbase approaches) may havethe power to resolve thesemysteries about quantumphysics and life.
Information: From Aristotle to Landauer & WheelerIn
form
atio
n: F
rom
Aris
totle
to
Land
auer
& W
heel
er
I think of my lifetime in physics as divided into three periods. In the first period. I was in the grip of the idea that Everything is Particles. I call my second period Everything is Fields. Now I am in the grip of a new
vision, that Everything is Information —John
Archibald Wheeler, Geons, Black Holes, and Quantum Foam.
Aristotle believed that the universe was entirely ordered by themetaphysical forms.
“The form informs matters, the mattermaterializes the forms”Information referred to the processes
by which a form (or idea or essence)entered into something material andgave it a specific shape or character, thusin-forming it.
Info
rmat
ion:
Fro
m A
risto
tle to
La
ndau
er &
Whe
eler
Maxwell’s demon
Maxwell (1871): discussion about the limitations of the second law of thermodynamics
Szilard (1929): “The decrease of entropy by intelligent beings”
• The relationship between information and measurement (information gain)
Info
rmat
ion:
Fro
m A
risto
tle to
La
ndau
er &
Whe
eler
Mathematical theory of communication
Hartley (1928):The idea of using logarithms to measure of information content
Shannon (1948):mathematical theory of communication
The fundamental problem of communication is that of reproducing at one point either exactly
or approximately a message selected at another point
anything is a source of information if it has a number of possible events.
any signal carries information about a source if we can predict the state of the source from the signal.
Shannon ingeniously showed how the concept of
information could be used to quantify facts aboutcontingency and correlation in a useful way
Quantification of ‘information’
Reduction of information to a mathematical formula
Resemblance between information theoretic Shannon entropy and the thermodynamic Boltzmann entropy
Brillouin (1951)
• free information• bound information• interconvertibility of information and negentropy
Information is physical
Landauer(1961) discovered that logical operations that get rid of information, such as erasure, necessarily require the dissipation of energy.
the erasure of 1 bit of information requires a minimal heat generation of KTln2.
Information is physical
Information is stored in material system in accordance with the laws of physics and, information is transferred from place to place by physical means. So, information is not a non- physical entity
Information handling takes place in the physical world
It from Bit
J. A. Wheeler believes that information is the fundamental category from which all else flows, in other words, physical existence, at the deepest level is composed of information or bits.
It from bit symbolizes the idea that every item of the physical world has at bottom - at a very deep bottom, in most instances - an immaterial source and explanation;
Quantum Mechanics
Quantum Mechanics has two conceptual kinds of problems:
local-realism (nonlocality)measurement problem
Niles Bohr:There is no quantum world. There is only an abstract quantumphysical description. It is wrong to think that the task of physics is to
find out how nature is. Physics concerns what wecan say about nature
Brukner and Zeilinger’s interpretation
• The whole physical description is based on propositions
• we have knowledge or information about an object only through observations.
The only way we are able to understand any phenomena in nature is through the epistemological structure of classical physics and
everyday experience
From the theorem of Bell and Kochen- Specker we know that for a quantum system one
can not assert definite truth values to all conceivable propositions simultaneously
A system is nothing else more than a construct based on a complete list of propositions together with their truth values
vx
(1)The velocity of the object is (2) The position of the object is
In an attempt to describe quantum phenomena we are unavoidably put in the following situation:
1) the description of a quantum system has to be represented by the propositions which are
used in the description of a classical system
2) those propositions cannot be assigned to a quantum system simultaneously.
How to join these two , seemingly inconsistent, requirements?
Knowledge and information
Finiteness of Information
indefiniteness of the truth values for complementary propositions is due to that:
The information content of a quantum system is
finite
This kind of randomness must then be irreducible, that is,it cannot be reduced to ‘hidden’ properties of thesystem. Otherwise the system would carry more informationthan what is available..
A quantum system cannot carry enough information to provide definite answers to all questions that
could be asked experimentally.
Thenby necessity the answer of the quantum system to some questions must contain an element of randomness.
Irreducible randomness results from the finiteness of information
How much information a quantum system can carry?
The principle of quantization of information states that:
“An elementary system carries 1 bit of information.”
“Do Deeper Principles Underlie Quantum Uncertainty and Nonlocality?”
The state of an elementary system specifies the answer to a single yes/no experimental
question
Elementary systems cannot carry enough information to specify definite answers to all experimental questions that could be asked
Questions lacking definite answers must receive a random outcome
Randomness must be irreducible because if it could be reduced to hidden properties, then the system would
This conflict between local realistic view and quantum mechanics has led to numerous experiments, interestingly, all of which support quantum mechanics. This means that if nature is governed by the predictions of quantum theory, the “locality principle” is simply wrong, and our world is nonlocal.
according to the Bell’s theorem, any local realistic view of the world is incompatible with quantum mechanics
In other words, Bell demonstrates that for entangled state, the explanation of all correlations between two particles with a local realistic model is impossible.
Entanglement
they consider the case of two Qbits systems carrying therefore 2 bits of information, i.e. representing the truth value of two propositions. the Bell states:
if we ask the two questions whose answers describe the result of a joint observation:Are both spins in the same direction along x?Are both spins in the same direction along y?
then we end up with a maximally entangled state.“yes, yes" “yes, no" “no, yes”“no, no"
Entanglement is explained as arising when all of the N bits of information associated with N elementary systems are used up in specifying joint rather than individual properties, or more generally, when more of the information is in joint properties than would be allowed classically
In which way do these four states carry two bits of information in a nonlocal way?”
Information is a fundamental notion which the inherent nature of quantum particles and quantum processes are based on its concept.
External reality depends as well on our experimental answers to questions about the quantum events
Reality and information are two sides of the same coin. It does not make sense to talk about reality without the notion of information about it, and it is pointless to talk about information without something where it refers to.
What can be said about reality, defines what can exist.
The ultimate goal in Brukner and Zeilinger’s approach
Information is the irreducible kernel from which everything else flows. Then the question why nature appears quantized is
simply a consequence of the fact that information itself is quantized by necessity.
It might even be fair to observe that the concept that information is fundamental is very old knowledge of humanity, witness for example the beginning of gospel according to John: "In the beginning was the Word".
the more contentious question becomes whether or not physics needs another, richer concept of information than Shannon’s definition.
what is the meaning of information?
Does information, as mentioned above; really play an active role in physical processes to shape the Universe?
If so, when and where does information begin to play an active role, actually controlling processes in the Universe?
Are information and information processing exclusive attributes of living systems, related to the very definition of life that entangled with concepts such as meaning, intention and specific functions?
where is there room in physics for the notion of information, not merely in the static, passive and technological sense, but in the active life, observation and meaning sense?
How does a lofty, abstract notion like meaning or intention emerge from the blundering, purposeless antics of senseless atoms?
Pragmatic Information
Roedere emphasizes that to address and answer these questions, a definition of this ubiquitous concept must be found that is truly objective and independent of human actions and human- generated devices To accomplish this idea, he turns to the
process of interaction as the underlying basic, primordial concept
Pragmatic Information
he divides all interactions between two bodies into the two major categories:Force-field driven interactions between elementary particles
and ensembles of particles in the physical domain, Interactions between classical mass pointselementary particles in the quantum domaingravitational interaction between macroscopic bodies Information-based interactions between certain kinds of
complex systems that form the biological domain,interactions between an insect orbiting around light bulb and this light source,interactions between microorganisms and imbalance in concentration of glucose,interaction between instrument and object during a physical measurement.
Pragmatic Information
interaction in informational base is an arrangement in which the presence of a specific form, shape or pattern in complex system A (the emitter) —not its field, energy or forces—leads to a specific, univocal change in complex system B (the recipient).
Roederer defines pragmatic information as that which represents the univocal correspondence between pattern and specific change
Pragmatic information does not appear as an active, controlling agent in the physical interaction processes.
This concept plays no active role in the abiotic world, unless an observer such as life form (or device designed and built by intelligent beings) intervenes for measurement or modeling
without “observers”, there is no information
Roedere posit :
information is the defining concept that separates life from
any natural (i.e., not made) inanimate system.
life is information at work, therefore,information appeared, in its fundamentalpragmatic form, when and where lifeappeared in the universe and, conversely,life appeared whenever and whereverinformation-driven interactions began.
What is the relationship between information and reality?What is the relationship between physics and reality?
What is the role of physics? “It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature”
It From Bit or Bit from US?
The laws of physics result from our observation of the universe
Wheeler’s “Meaning Circuit dictum”:
Physics gives rise to all phenomena,
Phenomena in turn give rise to chemistry, biology and communicators
Questions of communicator lead to measurement and the laws of physics.