22 March 1999

The Fourth Dimension by Rudy Rucker

If you have read Flatland and were left wondering about its implications regarding higher dimensions this book is a absolute must read. The book then goes much further than simply explaining the 4th spatial dimension and explores the possibilities of higher universes.

Does it talk about time ?

Extensively, in fact the third part, chapters 9, 10 and 11 all talk about time.
Rucker seems to favour the eternalist model and spends quite a lot of time describing, quite convincingly, a “block universe” in which past, present and future are all equally “real”.

St. Augustine wrote that God is outside of time and that Time exists only within the created universe. On this view, God would perceive something like a block universe, while we would be limited to seeing it frame by frame in the present.

He also writes of time cones, circular time and in chapter 10 analyses the implications of time travel.

In the final chapter "what is reality?" he imagines getting rid of all preconception and building from scratch. At the core he sees only 2 realities that he calls certain: “I exist and I perceive things. I could be a robot, a spirit, an eye of God, a software or who knows what, but I am sure I exist. I am sure I am the entity that is typing these words. You the reader could doubt of my existence, but you know for sure that you exist”

On the perception of things it’s a little trickier, Rucker talks about the philosopher George Berkeley, and his concept of reality, His concept of “spirit” is close to the concept of “conscious subject” or of “mind”, and the concept of “idea” is close to the concept of “sensation” or “state of mind” or “conscious experience”. Berkeley denied the existence of matter as a metaphysical substance, but did not deny the existence of objects such as apples or mountains. Berkeley’s claims on immaterialism has many followers today under the more common term of subjective idealism.

He also mentions quantum mechanics and the implication that might have on our perception of "reality".

All great food for thought.