In the preface Isaac Asimov states "From year to year more words are invented to convey new concepts and new discoveries. In 1960 no one had ever heard the words quasar, pulsar, mascon, laser or transfer-RNA. Those words did not exist because they represent findings made since 1960".
Now, consider how many new terms have made their way into our language since this book was published in its original two volumes back in 1959 and 1972 respectively.
My edition was updated and fully revised in one volume in 1974. So, as you can imagine no mention of biotechnology, supercolliders or string theory, and the section on quantum theory is not even worth mentioning really. This is not a criticism of the book itself, it may have even been updated since - for all I know.
At the end of the day, it will provide the reader with a good grounding in the general sciences that can always be expanded on by further reading.

Both Asimov and Arthur C. Clarke used a lot of hard science in their fantasy/science fiction stories. As a fan of Sci-Fi myself, I initially bought this book with that in mind. ( )