3.5 Stars out of 5 stars
I’m a fan of String Theory, but I came to this book more than two decades after it was written. Because of that, one thing bugged me throughout this book. How much has actually changed in one of the most fringe areas of physics? The book starts out with a recap of basic physics (i.e. quantum vs relativity). The problem is I am familiar with all the ideas explored in this book. I’ve read all but Brian Greene‘s newest book, Until the End of Time, before this, and that, coupled with all the other material I’ve consumed, made the recap feel more distracting than anything. While I am a big proponent of constantly reconsuming things, especially ideas outside your realm of expertise, this book is necessarily less well developed as everything that has come since. The sign of a good scientist and author is to learn how to communicate better with time. It isn’t particularly bad, but it was easy for me to zone out.
Then we get into string theory. Even here, most of the major ideas I was familiar with. I was hoping to leave this book with a better appreciation of the finer details of the theory, but I found it was most effective at communicating the broad ideas. Then the finer details were really hard to get through and failed to make a lasting impression. I feel like this book would have been a much more positive experience if I had read it earlier in life because it would have been an excellent introduction to the field and precursor to Greene‘s own follow up book, The Fabric of the Cosmos. I do think it is time I return to Greene‘s other novel, The Hidden Reality, which was the first book of his I ever read; that was with very little background.
If you’re interested in learning more about this theory, I highly recommend watching the Loose Ends video I posted at the top of this post. For a brief review, string theory is a theory that the smallest things of nature are these tiny vibrating strings of energy, where the vibration of each string is what defines the type of particle it is (e.g. quarks, neutrinos, electrons, etc.). These strings can perfectly reproduce our current model of particle physics, but it comes at a cost. 1) it requires the existence of many more dimensions, and 2) it suggest all of our particles have a twin symmetric particle. Why don’t we see these other dimensions? They are small and folded in onto one another. If you have a problem with the idea of tiny dimensions, I found it helpful to remember our current 3D space used to me much much more constricted before they began to expand. They don’t say this explicitly, but my mind figures, perhaps the process of expansion only applied to the 3 dimensions we see. I wonder what Greene would say to that logic? Take it with a grain of salt. This theory is fundamentally mathematical, and we have yet to show it experimentally.
The physic’s true success is in connecting Quantum Mechanics with General Relativity because the math of the two fundamentally disagree with one another (i.e. I think in particular situations like a black whole with large gravity in and very small spaces). The true beauty, as Greene suggests, is not that it necessarily needs to be a description of reality; it is that String Theory proves the two laws are reconcilable. It may be that this is not necessarily the true description of our reality. Nevertheless, it shows that a connection can exist. Now is it worth believing? That’s where things get really complicated.
The theory itself, I love despite my issues with the book. It’s a fascinating concept with compelling motivations. There are many Goodreads reviewers who seem to approach string theory with a level of cynicism. Some who dismiss it because they struggle to understand it. Others who dismiss it because it breeches into the currently unknowable. However, there is a strong argument to be made about using the information we have available to best describe the nature of the universe. As we strive to improve these descriptions we can push ourselves forward in hopes that it can be improved further. That may or may not happen. The problem I have with opponents to this theory is that they seem comfortable dismissing a theory that may very well be the nature of reality simply because the physics is so difficult to constrain. Such a mindset will merely ensure that what is currently unknowable remains unknowable.
The Large Hadron Collider was hoped to show indirect evidence for String Theory. The energies and technology needed to observe strings are far outside our wheelhouse, but string theorists had hoped the energy at the LHC would be enough to produce the larger by products of the theory, the symmetric particles that we have yet to observe. This did not happen. However, string theorist had already noted it may be more difficult to reach the energies needed than those achieved with the LHC. The simplest explanation as to why string theorists were unable to simply make a fixed prediction of what energies are needed to produce the predicted particles is that there are a large array of possible configurations of string theory. At one time, it was small enough to brute force the process, but we now recognize far too many solutions exist to truly test them. It is, in that way, currently unfalsifiable. Nevertheless, we are brought back to the point I made before: it is still the best way we have to describe reality.
If you are interested in this topic, you could read this book. It’s worth noting most people I see enjoyed this book much more than myself. However, there is an ample supply of more recent resources you can pursue too, or you could read the book and follow up with the most recent discussions available. Here are some of the resources I sought out. The first video I posted at the top of the blog was a fantastic discussion about the history and current state of SH hosted by Greene at the World Science Festival in 2019. Sean Carroll did a discussion with Greene, where Brian Greene put his bets at String Theory being a real description of reality at 50/50 shot (obviously an off the cuff comment). This was a great casual discussion. Another episode of Sean Carroll‘s podcast had a more formal, string theory specific, discussion as well. Lastly, Greene discusses String Theory, black wholes and other topics with Leonard Susskind (one of the founders of String Theory) in the late 2020 on the WSF YouTube channel.
Of these, if you are coming in blind, I would recommend you check out the WSF YouTube discussion first. If you’re someone more familiar with it, you may find these other resources interesting too. Lastly, there is, of course, Greene‘s adaption of this book on PBS which I have not watched, but I will soon.