I read this book in my teens. Since then I hadn’t read it. The only things I remembered was that there was a Cloud hurtling toward the Sun, there were Americans and British involved, and that there was a lot of formulas, diagrams, and lengthy expository footnotes on several pages…
After re-reading it, the book’s central question is still the best of it:
“What is the nature of human intelligence?”
The Cloud answers by saying that one should attach labels to one’s neurological states, be it anger, headache, embarrassment, happiness, or melancholy. These states could then be interpreted as being just labels. If someone wished to tell someone else that he was suffering from any kid of ailment, he should make no attempt to describe that particular neurological state. What he should do was to display the label in question. Communication would be just label swapping between two entities.
The basic premise for the Cloud is that intelligence is based on our usage of language, which is most simplistic with its focus on on/off states (eg, being a headache one of the examples Hoyle uses). Intelligence of far greater depth would ask for more, because communication cannot be based on just 2 states due to its complexity. If one would want to characterize the actual neurological state producing an headache, that device/being would have to possess a more sophisticated communication (the device would have to pass Turing’s Imitation Game to be able to mimic intelligent life). As a side note, the way Hoyle found to instantiate the communication between the Cloud and us was to devise an audio/video system to relay the cloud’s responses into readable text. Quite ingenious at the time…
I didn’t really care for the rest of the plot: Cold War interactions, American vs British, etc. On top of that, the characterization is very weak, but that’s normal for the time the book was written (Arthur C. Clarke a fellow Brit is better than Hoyle, but characterization-wise he’s not much better than Hoyle).
57 years later since its publication what can we say about the book? First and foremost it has to be read under the lens of time. We have to put ourselves in the 50’s and imagine what it would have been like to live in that époque. Seen from today’s standards the novel has dated pretty badly. It’s full of stereotypes and idiosyncratic scientific debates. What saves it are the philosophical questions revolving around the cloud’s intelligence and basic human similarities to the scientists who are eager to understand it, i.e., Hoyle’s philosophical debate revolving around the nature of human intelligence is the book’s best feature.
I still remember Carl Sagan saying that we were made of star-stuff… And that’s one of the coolest things I ever learned in science.
Bottom-line: If you’re interested in vintage SF, by all means read it. If you’re interested in eschatological fiction (the fate of the world, etc), it should be read as well. If you’re interested in the History of SF, it’s also compulsory. If you couldn’t care less about these aspects, avoid it.
SF = Speculative Fiction.