Apparently, there existed a physical Wikipedia at some point. Although this physically copy was only a fraction of the true size of the entire website, it got me thinking: how large of a book would you need to make a physically copy of the entire internet?
How do we print the videos?
One frame per page. Make flip books.
It’s gotta be phone book big, minimum.
Just the porn section alone would probably stretch to the stratosphere. And the there’s funny animal videos.
Randall Munroe did a what-if xkcd about how much effort it would require just to keep up with the changes to Wikipedia. Reading this might make for a good starting point.
From here:
“Eric Schmidt, the CEO of Google, the world’s largest index of the Internet, estimated the size at roughly 5 million terabytes of data.”
I saw an estimate of 3000 characters on a page of text. If you equate one character with one byte then it’s 5 * 10^21 / 3000 which is getting close-ish to 2 * 10^18 pages.
That’s a lot of trees.
There are somewhere near a trillion photos on the internet.
How many of those are kittens?
I still have The Whole Internet, Ed Krol, published by O’Reilly and in 1992 it took around 500 pages.
The amount of data online is growing exponentially.
All of them except the tragic cliff’s-edge selfies and dinner.
And then some pirate would upload The Internet to the internet and instantly double its size.
And then somebody on the Dope would start a thread titled “What if the Internet was written by somebody else”, and you can just imagine how long that will be.
For every cat picture on the internet there are at least a dozen more pictures of… you know.
Yeah. “Cats”.
Don’t be silly. It would be zipped, otherwise no torrent client could handle it.
Since @ftg has come up with an approximately correct, factual answer (correct to within factors of order pi as one of my professors was wont to remark), I’ll just post this, which was the first thing that came to mind when I saw this thread.
For this scenario, let’s assume that we are only taking into account words. No videos, direct code, audio, or photos. Only words would be counted in his hypothetical book.
Lest anyone be misled, the book is actually titled Whole Internet User’s Guide and Catalog and was an early book about the Internet, not a printed copy of the entire thing. 
It was inspired by the Whole Earth Catalog, and while this may disappoint some people, it also did not contain the entire planet Earth either.