Smolin neatly explains properties the theory of everything must have and the logical necessities of having the observer be a part of the system (Topos logic?). And this is the first thing in my (limited) reading stating that both time and space are quantized. Spin networks which describe spacetime as graphs is also worth digging into. ( )

Lay people think gravitons are massless and propagate at the speed of light.

This (as usual) is a purely dogmatic assertion based on SR. Everybody knows that the quantum phenomena violates SR. Quantum electrodynamics shows that “virtual particles” do not care for anything of old causality based physics, but are best described on the basis of chance and necessity of dialectics – two widely differing world views.

Most forces - chemical, electromagnetic, weak and strong nuclear etc., forces are supposed to be mediated by the exchange of virtual particles between mass centres; some of those virtual particles are well known. If the gravitational force is similarly due to the exchange of virtual gravitons, then there is no reason to believe that they should follow SR. If the virtual gravitons follow the limit of the speed of light, then there would be no way for these to keep the vast range of clusters and super, super clusters of galaxies in dynamic equilibrium. Local random motion of individual galaxies or other cosmic bodies would either break up and/or disallow cluster formations and we would see a uniform distribution of galaxies in the visible universe.

Look Smolin! I have had enough of your wisdom and teaching of physics to me. I thought our last encounter few weeks ago was clear enough.

It will be out of topic to talk about the infinite, and we have done so many times before. But I will try it again for the last time. I must remind you again that any causality (The “view of understanding” for Hegel) based philosophy; theology or science does not accept or believe in the infinite. Giordano Bruno was burnt on the Stake for declaring that the universe is infinite. Einstein denied any infinite universe. I quoted him before and explained why he had to assume a finite universe.

By definition infinite means something that has no limit and, is not bounded by anything else. If there are two infinites, then these two has a common boundary in between, so these are not infinite but become finites within even a bigger infinite and so on. So the “infinite hierarchies of infinities” is sheer nonsense and mysticism and I am not surprised that it “blew up the mind” of the MIT Professor. With that blown-up mind this Professor can do neither math nor science, because everything is darkened for him from that blow-up.

In mathematics you put an arbitrary origin (0) on a straight line and extend this to the right and left side to plus or minus infinities. But do you change infinity by this operation? Now I ask you if you can; to go to one end of your plus and minus infinites and come back to the origin again. If you cannot do that, then your halved infinities are also infinite and no matter how many times you divide it this will be the same! Galileo was smarter than us “scientists” when he said that addition, subtraction, expansion or compaction etc. or any other mathematical operation has no meaning for the infinite and it remains unchanged! Mathematics and physics pragmatically use the concept of infinite series for example, as a tool for approximation, calculation, measurement etc. of finite quantities and objects to certain limits, and that’s all! ( )

Not bad. This book talks about the possibilities of Quantum Gravity as a candidate to be the Unifying Theory of Physics, the Holy Grail if you will. Smolin speaks of his time as an undergraduate and as a postdoc and all of this other stuff of how the theory was developed. It borrows some things from Quantum Chromodynamics and all of that, but it isn't too bad.

I probably won't read it again, but maybe I will read more stuff by Lee Smolin. ( )

This book provides an introduction to quantum gravity aimed at the general public. It provides three different approaches to quantum gravity, doing a decent job of discussing the strengths and weaknesses of each. The author discusses black holes and multiple universes in the journey.

His approach to each subject is historical, tracing development of key idea and briefly mentioning the people involved.

Overall the book is interesting and a rather light read. Although it is aimed at the general public, it is probably a little light for the people who would be interested in reading it. ( )

I liked parts of this book, as it introduced some new ideas that I had not been exposed to. On the other hand, I miust not have been paying attention because he lost me at several crucial points and after those points, the ideas became just words on a page. I don't have the desire to re-read this to determine who was at fault.