# Exercise 1.1 in Quantum Processes Systems, and Information

I was going through Quantum Processes Systems, and Information by Benjamin Schumacher and Michael Westmoreland and could not understand the very first exercise which goes like

Exercise 1.1 Identify at least seven distinct physical representations that this sentence has had from the time we wrote it to the time you read it.

What do the authors actually mean by this?

## 1 Answer

I don't have the book in front of me, but I guess the meaning is about the different ways to represent the same information:

1. First - he probably wrote it on a paper.
2. Then someone probably typed it into a computer in english letters, and looked on it on a screen - what we see on the screen is some finite amount of tiny dots called pixels, so on the screen the sentence is just a collection of pixels.
3. The computer doesn't know english, so it went through several layers of encoding and compiling - let's assume that the first encoding layer is Unicode.
4. But the computer doesn't know Unicode as well, so a compilation to binary machine code is needed to take place.
5. Then something translated the zeros and ones of the machine code to electric signals - Baiscally 1 is translated to some value of voltage, 0 is translated to near 0 voltage. The computer understands electricity and now he can process this information.
6. This sentence got to my computer over the Internet, which means that the binary representation of this sentence was translated somehow to optical pulses that went through optical fibers all the way from the server to my home.
7. In my home there is a router that translates this optical pulses to another kind of electromagnetic-radiation, that thing called "Wi-Fi". The EM waves travels all the way to the antenna in my computer.

There are a lot more than 7 layers I guess, and this was very roughly speaking and general, but I think you got the idea.

• Never saw that book, but this exercise is funny. Nice answer though. Is this book any good? Commented Aug 16, 2022 at 3:48
• Never heard of this book. Maybe @seeker could answer that
– Ohad
Commented Aug 16, 2022 at 5:43