What is information ?

I often have the impression that information is a key quantity in physics and especially in quantum physics. So, maybe one could reformulate the whole of physics in terms of information concepts (for instance ; conservation of information, flow of information, etc.). While we all have some feeling of what information means, it becomes really difficult to define it in a clear and objective way. What could be the simplest and clearest definition of information ?

Hi buddha... Information comes in two distinct categories.... That of which we are cognizant... and that of which we are not. Information of which we are cognizant lends itself to a TRUE/FALSE analysis. Information of which we are not cognizant can only be conjectured about... and lends itself to the great field of exploration in order to ascertain whether the conjectures about the unknown are true or false. Cheers

It is an important problem for me , too.
We absorb an energetic information only - our sense react when they are affected by the energetic particles (photons, bosons, baryons).
A space itself is a substance we can not see by our senses. There could be an information but it is not energetic and we can not see it.

This post has been edited by czeslaw on Sep 15 2006, 08:07 AM

By AWT such reformulation cannot be done without lost of information, because the underlying model of AWT is continuous, whereas the information is "digital". Furthemore, here are no signs of information transfer without matter transfer, from which follows, the information is always mediated by the matter, not the vice-versa.

This post has been edited by Zephir on Sep 15 2006, 08:43 AM

Asking about the nature of information is like asking about the nature of energy. We can never really know what it is, but we can describe it. For instance, one can say : energy is that thing which is able to set things in motion. Likewise, I would propose for information the following functional description :

Information is that thing that ,when received by a localised system, changes the probability of that system to evolve in a certain way.

An example - at the human level :
Suppose you hear on the radio that there has been a traffic accident on the road you are driving on, 20 km ahead of your present position. Receiving this information, you might decide to take another road. You could also continue along the same road and hope that you nevertheless will able to pass the accident location in a reasonable time. So, the received information has in any case increased the probability of taking another road.

I think that such a kind of definition lends itself to be merged into quantum physics.

Of course, the information can be mediated just by energy, but I suppose, the information content of the system can be expressed in terms of number of distinct states available. What do you think about such definition?

This post has been edited by Zephir on Sep 15 2006, 05:09 PM

all is information
energy is information

Anything that a observer realizes is information

Actually, there is a whole branch of physics that deals with information as a physical quantity, closely related to thermodynamics.

Yes, I know that. There exists really a lot of definitions, theories, etc.
I was however not really satisfied with these and wanted to start from scratch and in a way which is closer to the "physical world" than to our "information society".

The true is, the physic doesn't knows about information at all, such concept is solely abstract. The discussion about information has no meaning in physic.

It's the details.

This post has been edited by Nick on Sep 15 2006, 09:18 PM

I don't think information can be quantified in the same way we can quantify energy; therefore is irrelevant to physics because I don't think it is feasible to measure it. It is true that photons, bryons etc, carry information (due to their properties of momentum, energy, spin)etc, but how do we measure information from these?

To me, information can be put in the same category with what people call spirit. We have an idea of what that is, but we can not measure it. I don't have any idea of how something that cannot be measured can be put into physics equations.

Indeed, I have the same doubts about this. Nevertheless, I will not give up yet.

Hi buddha et al,

Interesting .

See

http://en.wikipedia.org/wiki/Information_Theory

http://en.wikipedia.org/wiki/Information_entropy

http://www.ccrnp.ncifcrf.gov/~toms/bionet....n.Equal.Entropy

Hope this helps.

-C2.