Recently I have listened to The Grand Design by Stephen Hawking and Leonard Mlodinow and below there are a few comments.
The book starts with that philosophy is dead.
“Traditionally these are questions for philosophy, but philosophy is dead. Philosophy has not kept up with modern developments in science, particularly physics. Scientists have become the bearers of the torch of discovery in our quest for knowledge.”
According to authors, nowadays this is the task of science to answer eternal questions like
- “Why is there something rather than nothing?
- Why do we exist?
- Why this particular set of laws and not some other?“
These questions are interesting indeed. So let us see what answers the authors offer.
Hawking and Mlodinow start with the statement that free will is illusion, as inexorable laws of Nature control everything including metal processes (please note that such a statement is a trend in modern science):
“It is hard to imagine how free will can operate if our behavior is determined by physical law, so it seems that we are no more than biological machines and that free will is just an illusion.”
This puzzles me, as this implies that sound vibrations as well as signs on the paper coming from authors basically are the direct voice of Nature. In other words, Nature has chosen the authors to inform other less educated people of its grand design. The question remains open though, how one could be sure that Hawking and Mlodinow are ‘the Ones’.
According to the authors, the M-theory is a scientific framework to answer all questions above and authors are sure that it does it in a perfect way. They find especially worthwhile that the theory explains not only our universe but all possible universes:
“The laws of M-theory therefore allow for different universes with different apparent laws, depending on how the internal space is curled. M-theory has solutions that allow for many different internal spaces, perhaps as many as 10^500, which means it allows for 10^500 different universes, each with its own laws.”
This explains fine tuning perfectly. Our universe is just one among 10^500 other universes. Hence there is nothing special that by chance in one of universes that develop in parallel, excitations of natural neural networks in authors’ brains allow them to comprehend the Nature and its grand design.
Now let us consider what reality is and how scientists find the truth about it:
“Instead we will adopt a view that we will call model dependent realism: the idea that a physical theory or world picture is a model (generally of a mathematical nature) and a set of rules that connect the elements of the model to observations.”
“According to model-dependent realism, it is pointless to ask whether a model is real, only whether it agrees with observation.”
“According to the idea of model-dependent realism introduced in Chapter 3, our brains interpret the input from our sensory organs by making a model of the outside world. We form mental concepts of our home, trees, other people, the electricity that flows from wall sockets, atoms, molecules, and other universes. These mental concepts are the only reality we can know.”
This again puzzles me. Let us consider for example mental visual concepts. There are photons reflected from objects and coming into retina. Neurons connected to retina get excited and then natural neural networks start information processing. An interesting question is however, where resulting visual mental concepts are located. According to physics, this must be in the brain, where neurons are located, where else. Yet, this implies that metal concepts of the three dimensional world until the horizon must be also in the brain. So, is the brain in the world or the world in the brain? What model-dependent realism would say? This is especially interesting as “These mental concepts are the only reality we can know.”
In the book, there are many statements against religion. If I have understood correctly, the main point is that religion is based on belief and science on knowledge. For me however, it is not always clear how to distinguish belief and knowledge. For example I was impressed by the next statement:
“Today we know that helium and lithium, atoms whose nuclei contain two and three protons, were also primordially synthesized, in much smaller amounts, when the universe was about 200 seconds old.”
However, is this knowledge or a belief? Assume that there was Big Bang described by the M-theory as supposed by the book. In one of the 10^500 universes, evolution has finally created two biological machines: Mr Hawking and Mr Mlodinow. Natural neural nets in their brains have produced mental states that in turn have been formed into the statement above. How does it follow from model-dependent realism that these mental states form solid knowledge and not just a belief?
Conclusion. In a search for answers to questions ‘Why’ raised in Grand Design, I personally prefer philosophy (if you know German, there are excellent lecturs by Maarten Hoenen). It well might be that philosophers are less informed about the M-theory but on the other hand they convey better the difference between logic, metaphysics and physics.