Most people seem to be instead answering the question "what books would you use to teach yourself?", or "what books would you use for college physics?". But if we're talking about all of humanity learning from these books, we might as well bust out the most enormous, powerful tomes there are.
1. Modern Classical Physics, <PERSON> and <PERSON>
Assuming civilization preserved three other books for mathematics, there's no reason to go all the way back to <PERSON>. That's probably the most inefficient way of doing it, because information is always synthesized and compressed over time.
<PERSON> is the T in Gravitation by MTW, the 'bible of general relativity' that weighs in at over 1000 pages. <PERSON> really loves huge books, and his recently released Modern Classical Physics clocks in at over 1500 pages. Reviews on Amazon warn that the book is heavy enough to generate gravitational waves; it easily weighs more than a newborn child.
It disposes of Newtonian mechanics in a few pages and proceeds to cover every field of classical physics, including special and general relativity, statistical mechanics, optics, elasticity, fluid dynamics, and plasma physics.
To put that in perspective, some physicists thought that the field was essentially finished by 1900. Modern Classical Physics covers everything known by 1900, including enough applications to jumpstart civil and mechanical engineering, in just half of its pages. The second half is devoted to some of the most important new fields of physics after 1900, namely relativity and plasma physics. Of course, the other important fields all involve quantum mechanics.
2. 800
Quantum Mechanics, Cohen-Tannoudji
This book also spans over 1500 pages, and it's rarely used for courses because its length is unmanageable, mostly from the piles of special topics. To give a sense of it, the third chapter (of 14) alone has 15 appendices, the first of which is a "reader's guide" to tackling the rest of them.
<PERSON> works in the field of atomic, molecular, and optical physics, essentially 'applied quantum mechanics'. His enormous book will let civilization retrace the historical development of quantum mechanics, then get a good part of the way to reconstructing lasers, spectroscopy, and the periodic table. The only thing that's missing is the application of quantum mechanics to fundamental physics.
3. Quantum Field Theory in a Nutshell, <PERSON>
Quantum field theory is the quantum mechanical framework used to describe fundamental physics; it's been called 'the language Nature speaks'. <PERSON>'s book gives a whirlwind tour, then launches into a remarkable series of applications. He covers the fundamental theory and then the Standard Model of particle physics rather quickly, then links it to condensed matter physics, explaining phenomena like superconductivity and superfluidity. Combined with the practical knowledge from the first two books, that gets us most of the way to understanding how the entire LHC works. Combined with three books on engineering, we might be basically ready to build it!
<PERSON> concludes with speculative topics like supersymmetry, grand unification, and string theory, and I think that's the best part. With these books, we've not only gone to the edge of current knowledge; we've peeked over it into the unknown. 800