Information, what is it, then?

[Dabljuh]

This question has haunted me for a year now. What is information? I mean, we can measure it, we can use it, we can cuddle it, but I do not know of a sensible definition of what the universal phenomenon that which we call "information" is.

So far I have only come up with one important aspect of it: Time. Or causality. Without either (they are related) information would be impossible.

So I'm asking you. Maybe one of you has stumbled across a good definition. What is Information?

[fuelair]

That which I need or want to know or which I am presented with helter skelter is information. Any input not previously input or input in a different way that impacts its' importance or utility.

[JoeTheJuggler]

There are a number of different definitions of the word information. What exactly are you after? I don't follow how time and causality are aspects of information.

Have you checked out any dictionary definitions to see if they'll help? They define it with ideas like knowledge, intelligence, data or the communication or reception of communication thereof.

[l0rca]

Information is a form of qualia.

We have no idea what qualia is.

Ha ha.

[Nick Bogaerts]

Since this is in the Science and Mathematics and not the Philosophy section, I'll give the best definition of information I've come across:

Information is a measure of the decrease in uncertainity (entropy) after reception of a message.

If you are mathematically enclined, I suggest Shannon's seminal 1948 paper, A Mathematical Theory of Communication (http://cm.bell-labs.com/cm/ms/what/shannonday/paper.html)

[catbasket]

Trying to paraphrase someone who once attempted to teach me -

A big bucket of numbers is data. The same numbers organised in some way, e.g. tables or spreadsheets, is information.

I could be wrong.

[Dymanic]

Information is a measure of the decrease in uncertainity (entropy) after reception of a message.
The existence of a communications channel, with a sender on one end and a reciever on the other, is assumed under Shannon. Within those parameters, information can be crisply defined. Treating the initial (and tacit) assumptions as though they were universally applicable leads to absurdities. Footprints in snow might be treated as information, but does treating them as such instantly transform the snowfield into a "communications channel"?

[Gord_in_Toronto]

Trying to paraphrase someone who once attempted to teach me -

A big bucket of numbers is data. The same numbers organised in some way, e.g. tables or spreadsheets, is information.

I could be wrong.

This is similar to the definition used in IT -- information is organized data.

YMMV. :covereyes

[Schneibster]

I was going to go to Shannon information but Nick beat me there. It's the best technical definition I know of.

[fuelair]

Since this is in the Science and Mathematics and not the Philosophy section, I'll give the best definition of information I've come across:

Information is a measure of the decrease in uncertainity (entropy) after reception of a message.

If you are mathematically enclined, I suggest Shannon's seminal 1948 paper, A Mathematical Theory of Communication (http://cm.bell-labs.com/cm/ms/what/shannonday/paper.html)
I like mine (well, I would) but this is not bad at all and adds to it (especially as a sub part of my second sentence.)

[Ginarley]

Russell Ackoff's description which discusses a hierarchy from data to wisdom (including information) is the best I have seen. A good explanation is available here: http://www.systems-thinking.org/dikw/dikw.htm (http://www.systems-thinking.org/dikw/dikw.htm)

[Puppycow]

Gregory Bateson (http://www.users.globalnet.co.uk/~rxv/people/bateson.htm) defined information as "a difference that makes a difference".
Hold your hand perfectly still, palm upwards and resting comfortably on a table. With your other hand, drop a small coin into the palm. You will feel the impact, and if the coin is cold, you will feel the coldness of the metal. Soon however, you will feel nothing. The nerve cells don't bother repeating themselves. They will only report to the brain when something changes. Information is difference.

A lizard hunting insects operates on the same principle. The lizard's eye only reports movement to the lizard's brain. If the hunted insect settles on a leaf, the lizard literally cannot see it. But the moment the insect starts to move, whop, the lizard can see it again, and the tongue flickers out and catches it.

But there are differences and differences. Information is difference that makes a difference. You were probably aware, as you dropped the coin into your palm, your eyes told you automatically, without your brain even asking, what the value of the coin was; but you were probably not aware what date it was minted. This is because (unless you are a numismatist) the value of the coin makes a difference to you whereas its date doesn't.

What is it that makes a difference to a lizard, to a numismatist, to you? Surely not the same things. What is information for the lizard is not information for you, and what is information for you is not information for the lizard.

This is why the perspective of information is important. Perspective defines what counts as information at all, perspective defines to whom the information makes a difference.

(In other words, only someone who understands Chinese can glean any useful information out of it).

[Dymanic]

Information is difference that makes a difference.

Perspective defines what counts as information at all, perspective defines to whom the information makes a difference.
Though phrased differently, this is pretty much what fuelair said above while introducing what I find to be the critical term: utility. Information (in the "universal" sense the OP craves) can be anything, but only within the context of some kind of goal. Where needs and wants are absent, so is perspective.

[JoeTheJuggler]

So far I have only come up with one important aspect of it: Time. Or causality. Without either (they are related) information would be impossible.

I don't get what you're after, or how this is meaningful.

Is there any term you can put in for x where this statement is NOT true?

"Time. Or causality. Without either (they are related) x would be impossible."

[Soapy Sam]

At one level, all information is a mechanical process.

A key fits a lock. We might say the information required to open the lock is encoded in the key- but if the lock no longer exists, while the key does exist, does the information exist?

I should say not.

The same holds for other information storage media.
A floppy disc is all but useless these days.
A DVD is just a diffraction grating without a dvd player.
Semen is just goop without a womb.

Information is coded interaction.

The course of a flung rock might require a dvd to store the spacetime coordinates in detail, but the course exists independent of information. It's really there. spacetime.
Does the universe become richer in information, every time a rock falls?
I doubt it.

I think "information" is like " number" another of the abstract concepts human brains find useful, but which have no actual existence outwith human referents.

*Dons tin hat and crawls under table*

[Cuddles]

A key fits a lock. We might say the information required to open the lock is encoded in the key- but if the lock no longer exists, while the key does exist, does the information exist?

Yes. Information about what the lock was like.

The same holds for other information storage media.
A floppy disc is all but useless these days.
A DVD is just a diffraction grating without a dvd player.
Semen is just goop without a womb.

They still all contain information, in the same way that a sentence in Chinese contains information, even though I can't read it. What is important is not that the information can be decoded by a particular person in a particular place, it is that it is possible to decode it.

This does raise the question of when does information stop being there? In 1000 years a floppy disc will not be capable to being read and the key to decoding it will be gone. For all intents and purposes it no longer contains information because no-one can read it. However, as long as you know what a lock is, a key contains information even if the specific lock it opens does not exist.

[Soapy Sam]

It only tells you what the lock was like if you already know what keys are for- ie if the context of your background knowledge includes locks and keys. If information is "real" in the sense of an actual , measurable thing , as opposed to a human neural / cultural construct, then it should be discernable and measurable by any intelligence (and perhaps by other things), whether or not there is a shared culture.
I grant you that a dvd found in space by aliens would probably convey the information that it was an artifact (shades of Paley) given that said aliens had senses and intelligence in some way mappable onto ours. They might even deduce that it was a record. They might even manage to play it.
Hell, they might even understand what they saw.
But that just means certain light patterns can interact with suitable other things, like nervous systems, to alter the chemistry thereof.
Where is the " information" in this process?

I could alter alien neurochemistry by belting him/her/it over the head/ braincase/whatever, with a rock. Was the information stored in the rock?
That's what I'm getting at. Information is context dependent. There is a wealth of knowledge among humans about keys and locks. To a cyborg from planet X there is no information in the key about the original lock.

I'm far from confident that a DVD contains information if no dvd player exists.
It contains a series of holes. Those holes only contain meaning in the appropriate context, which is a dvd player. Even then, they only contain meaning when viewed by a human. What is the meaning of information if it is not in a human head.

[Dave1001]

Since this is in the Science and Mathematics and not the Philosophy section, I'll give the best definition of information I've come across:

Information is a measure of the decrease in uncertainity (entropy) after reception of a message.

If you are mathematically enclined, I suggest Shannon's seminal 1948 paper, A Mathematical Theory of Communication (http://cm.bell-labs.com/cm/ms/what/shannonday/paper.html)

that makes sense, perhaps minus the "reception of a message". I think a good starting point for a definition of information from a solipsistic point of view is reduction of apparent uncertainty about apparent reality. An more objective definition of information might be reduction of homogeneity (entropy) in a subsection of apparent reality.

[Dymanic]

Information is coded interaction.I agree. But not all interaction is "coded". The path taken by a rolling rock is influenced by the topography of the hill, but because the influence is exerted directly, there is no coding/decoding, hence, no information.

What is important is not that the information can be decoded by a particular person in a particular place, it is that it is possible to decode it.If that is what is important, it derives its importance from what it assumes: the existence of an agent possessing both the ability to perform the decoding and some reason for doing so.

[Nick Bogaerts]

The existence of a communications channel, with a sender on one end and a reciever on the other, is assumed under Shannon. Within those parameters, information can be crisply defined. Treating the initial (and tacit) assumptions as though they were universally applicable leads to absurdities. Footprints in snow might be treated as information, but does treating them as such instantly transform the snowfield into a "communications channel"?

I would say yes, it could make sense to treat the snowfield as a communication channel, and the snow itself as a two-dimensional signal (the snow depth being the amplitude). That this mathematical model is adequate or not depends very much on what you want to do with it. This example is not too far removed from digital watermarking, where you wish to transmit information (a watermark) through a noisy channel (an image).

[John Hewitt]

This question has haunted me for a year now. What is information? I mean, we can measure it, we can use it, we can cuddle it, but I do not know of a sensible definition of what the universal phenomenon that which we call "information" is.

So far I have only come up with one important aspect of it: Time. Or causality. Without either (they are related) information would be impossible.

So I'm asking you. Maybe one of you has stumbled across a good definition. What is Information?
Data is what is measured in bits and bytes and, so it seems to me, it is also what Shannon defines in his statistical mechanical definition of information. (In fact, in Shannon's day, the words data and information seem to have been used more or less interchangeably so I doubt that he was making any big point when he used the word information.)
Today, the IT curriculum for schools and such like tell us that information is "interpreted data." (This is not really my field of expertise, you understand, but I got lumbered with some IT classes at one time.)

This implication of this is that information cannot be measured in bits and bytes. On the other hand, it does mean that information can be encoded as data provided that the transmitter and receiver share an agreed interpretative mode.
This is the definition of information, and the distinction between information and data, that I now use. However, I find that the more senior and expert a person is, the less inclined he seems to be to follow it.

[Soapy Sam]

There's a danger we mean varied things by the same word.
Shannon's information has always seemed to me to be almost the exact opposite of the general understanding of the word.

[Paul C. Anagnostopoulos]

Information is a measure of the decrease in uncertainity (entropy) after reception of a message.
Righty-o!


Shannon's information has always seemed to me to be almost the exact opposite of the general understanding of the word.
Then maybe you like Kolmogorov complexity better, which is defined as the amount of computation required to specify an object.

~~ Paul

[Dymanic]

I would say yes, it could make sense to treat the snowfield as a communication channel
My question was whether doing so would make the snowfield a communications channel. You yourself provided what I believe to be the operative phrase: "where you wish to transmit". I don't know about time, or causality, but one aspect of information that I would consider indispensible (again, in the universal sense) is: intent; it cannot be defined independent of some goal-derived context. Part of the human perspective seems to include teleological assumptions that are so pervasive and so deeply embedded as to be completely transparent. The pattern-recognition modules return positive results, and subsequent action instantly defaults to "adopting the intentional stance" (if it looks like it might be capable of purposeful intent, treat is as if it is). Before you know it, virgins are being sacrificed to the appeasement of angry gods.

Not everything that could be treated as a communications channel is in fact a communications channel, and treating one as if it is may make sense, but only if it actually is -- otherwise, you may be up all night trying to decipher morse code messages in banging pipes, or micro-hieroglyphics on pebbles you've found (I know someone who actually did this once after being up several days on crank).



Shannon's information has always seemed to me to be almost the exact opposite of the general understanding of the word.Because what is generally considered most important is content, something that is explicitly ignored under Shannon.

[Cuddles]

I'm far from confident that a DVD contains information if no dvd player exists.
It contains a series of holes. Those holes only contain meaning in the appropriate context, which is a dvd player. Even then, they only contain meaning when viewed by a human. What is the meaning of information if it is not in a human head.

But where does the information go? At what point do you draw the line and say there is no longer any information? A DVD contains information when it is made, there is no argument there. If we put a DVD in a box and hide it for thousands of years, at what point does it no longer contain information? When DVDs are not popular so most people can't use it? When the last DVD player breaks and no-one can read it? When the last person who built DVD players dies so no-one knows how to build something to access the information? When the last person who has used a DVD dies so no-one is sure what it is for? When the last piece of history describing the use of DVDs is gone?

I would say that even in the last case it could still be possible to determine that there is information encoded, even if it is not readable, much like trying to translate ancient languages. This raises a similar point to whoever mentioned Chinese earlier. I can't get any information out of Chinses writing, but I still know that it contains information. I don't agree that information depends entirely on context. The question of accessing information is not the same as the question of whether it exists. I think that information exists whether I, or by extension anyone else, can read it. A cyborg from Planet X might not be able to read a DVD, or even work out that it is supposed to contain information, but the information is still there, whether he knows it or not.

[Dymanic]

But where does the information go? At what point do you draw the line and say there is no longer any information?
It's a variant of the traditional conundrum: when a tree falls in the forest and there's no one around, does it make a sound? And while I experience an involuntary eyeball-roll upon encountering the term, I think l0rca may have nailed it in post #4 above with: "Information is a form of qualia."

[Soapy Sam]

Then maybe you like Kolmogorov complexity better, which is defined as the amount of computation required to specify an object.

~~ Paul
How much computation does a rock take to fall down a mountain? Yet the path it ends up taking may be incredibly complex, due to trivial stuff like the compressibility of another rock it hits , the rate of spin etc , etc. Absolutely impossible to compute in advance, yet the rock generated this path with consummate ease.

In Shannon's sense, that course may be impossible to express simply, so it's information heavy. While I appreciate the value of Shannon's POV in his original context (signal / noise) - it seems pretty inapplicable here, as does any notion that the path requires information to define it at all. It doesn't. It can be described in terms of information. It can possibly be described in terms of the will of the gravity gods. It just seems equally perverse to do so in cases like this. I think information is a metaphor- useful in some cases, not in others.

Because what is generally considered most important is content, something that is explicitly ignored under Shannon.
I'd say "meaning", but I think we mean the same thing.

But where does the information go? At what point do you draw the line and say there is no longer any information? A DVD contains information when it is made, there is no argument there. If we put a DVD in a box and hide it for thousands of years, at what point does it no longer contain information? When DVDs are not popular so most people can't use it? When the last DVD player breaks and no-one can read it? When the last person who built DVD players dies so no-one knows how to build something to access the information? When the last person who has used a DVD dies so no-one is sure what it is for? When the last piece of history describing the use of DVDs is gone?

I would say that even in the last case it could still be possible to determine that there is information encoded, even if it is not readable, much like trying to translate ancient languages. This raises a similar point to whoever mentioned Chinese earlier. I can't get any information out of Chinses writing, but I still know that it contains information. I don't agree that information depends entirely on context. The question of accessing information is not the same as the question of whether it exists. I think that information exists whether I, or by extension anyone else, can read it. A cyborg from Planet X might not be able to read a DVD, or even work out that it is supposed to contain information, but the information is still there, whether he knows it or not.

I'd argue with your starting assumption. I'm not sure it's meaningful to say there is "information in" a dvd at any point. There are holes in a dvd. Put those holes in the right situation and you'll get pictures. Put those pictures in the right situation, you'll get physical changes in synaptic growth. I'm still looking for the information. What I'm seeing are processes.