Is Physical Information Real My question is about physical information and whether or not it is something real or merely fancy math. My problem is that physicists seem to talk as if information is real - however when they describe what it is they make it sound like it's merely a mathematical abstraction.
For example, if a bowling ball were to fall into a black hole, the physical bowling ball disappears from our universe completely - however (according to Hawkings) the bowling balls physical information is stored in two dimensions in the event horizon.
This is very similar to how the idea of information is used in the Universe is a hologram theory - in which our universe is a three dimensional representation of two dimensional information.
The question I have is: Is this information real or is it just mathematical BS? I mean, if my cat is merely the 3D representation of 2D information about my cat - then where is this information and what is it? Is it energy? Is it potential? Is it whatever determines whether or not a quark spins to the left or to the right? Or is it merely fancy math?  
 A: This is a topic that is often glossed over in science, because it is very nuanced.
A philosopher would characterize science as a field under epistemology, the study of knowledge.  It answers questions about what we can know.  Ontology is the study of what is "real."  However, what can we say about reality in the first place?  It turns out that we can say very little.  Due to many philosophical concepts, epistemology can say nothing about the real world without an ontological assumption.  Philosophy has many of these, such as the infamous "I think therefore I am."  Once you accept particular assumptions about your reality, you can use your knowledge to make more statements about reality.
Science is empirical.  Empiricism is a subset of epistemology.  Thus, a philosopher would state that science does not tell you anything about reality.  However, even the most hearty of skeptics will agree that you can't stop there.  It does a disservice to science.  It's important to explore what science does claim, and to see how close it gets to ontology.
Science's knowledge is in the form of predictive models.  Science claims that, if you can measure "reality," capturing part of it in a set of numbers (like lengths and masses), then you can use that information and their mathematical models to predict what you might measure in the future.
The power of science is that it identifies behaviors in "reality" which appear so consistent and reliable that you can almost claim they are true.  As an example, F=ma is incredibly reliable (on reasonable scales).  If you can show that you can measure a mass and measure a force, you can reasonably believe you can predict its accelerations.  More importantly, if you have a much more complicated structure, such as a truss or a body of flowing water, you can use these simple building blocks (like F=ma) to make predictions about the entire complicated structure.
More importantly, the power of science is that these predictions are pretty astonishingly good.  Science has a track record for being one of the most effective tools humanity has for exploring physical phenomena.  When an engineer uses science to state that a sky-scraper will withstand an earthquake, they are right remarkably often!
Some of the challenge that has arisen is that science is so effective at predicting that people start to talk about it as though it is actually true.  Philosophy calls this process abduction (contrasting with deduction and induction).  Induction is accepting that the "best" theory is actually true.  In many cases, science is such a good predictor of physical phenomena that we engage in abduction and declare it to be the "true" reality we live in.
Most good scientists are well aware of this issue.  They are aware that their theories can be wrong.  However, despite this, we still talk in ontological terms.  We still talk about what "really" would happen.  This is partly due to language.  Natural languages never evolved to deal with predictions that are just this good, so the language required to accurately depict the uncertainty just isn't there.  I would claim that, contextually, it is assumed that all statements written in a scientific form come with the assumption that they are derived from a set of axioms, and the results may be invalid if one of those axioms is invalidated.
So in the end, the information in the hologram you speak of is exactly as real as science's model of the cat you threw into the black hole in the first place (okay, I admit it, you had two different parts to this question, one with black holes, one with cats.  I just stitched the two together).  Science provides an answer which says "if you act as though your cat is encoded as 'information' on the surface of the black hole, science states the predictions which arise from that model will be very consistent with any measurements you take in reality."
Now how good is this prediction?  It's a pretty extreme situation.  Black holes are very hard to study, and cats dislike being thrown into them.  However, scientists are constantly striving to explore more extreme situations.  We dive deeper into quantum mechanics.  We dive deeper into relativistic environments.  From this work, the behavior you describe above, with the cat turning into information, is the best model the scientific community can provide you.  It's up to you to throw the cat in and find out!
So is science reality?  We don't know.  It's entirely possible that the physical world we see in scientific theories is actually the real world.  However, at a philosophical level, we can never prove that.  We do have to recognize that scientific theory appears to be notably consistent with reality.  We don't really know what happens when you throw a cat in a black hole in reality, but if I had to predict what would happen before I did it, I'd rely on the models science provides.
Okay, maybe I lied a bit.  I'd probably also rely on models provided by the Humane Society.
A: From the point of view of quantum field theory, the only difference between you and complete vacuum is the arrangement of quantum fields. Namely, you and vacuum ("nothing" in a layman's language) are made of the same "things", the only difference is how you configure these "things". That's information.
