Sean M. Carroll

I’ll be honest: this was a tough job. Sean Carroll really does his best to explain the basic issues of theoretical physics in a comprehensible and pleasant way. Certainly in the beginning he uses a lot of humour (lots of cats!), nice literary references and a very patient style to successfully present the basics on classical mechanics (from Newton to Einstein) and quantum mechanics.

But somewhere halfway through, he starts with what is the logical main part when it comes to time as a show more physical phenomenon: entropy. And from then on this book becomes a difficult read. From as many as 20 different perspectives, Carroll tries to answer the question why that entropy exists, how it defines the one-directional arrow of time, and why in our universe it runs from past to future (yep, apparently that is not an obvious question).

Everything seems to come down to the initial state of our universe, namely in low entropy. But why was it actually that low back then? Carroll jumps from one issue to another, from one scenario or theory to another, and new aspects constantly appear that make the proposed hypotheses unlikely. It has been cited in some reviews: this book looks like an infinite set of Russian dolls that are put together. But he has to conclude: we know to little (especially on quantum gravity) to give clear answers.

At the end of the book, Carroll ventures into his own hypothesis (he calls it a prediction), which is inspired by multiverse theory. He admits that he is very speculative, but he also defends that approach, because that is simply the way in which science advances. This was a very interesting book, which ultimately does not provide a satisfactory answer to the question why time exists as it exists, but it does provide an honest insight into how science works. show less

Carroll is a fluent lecturer, very personable, and very knowledgeable (and a snappy dresser for a Great Courses professor), but this course is badly organized. After 24 lessons, I feel like I heard the same things repeated a dozen times, and at the end, the main point of the videos, why is there an arrow of time, doesn't seem much better explained than it was several videos earlier. There are all sorts of interesting digressions along the way, into things like neuroscience, and as I said, show more Carroll is so likable and such a good presenter that I kept watching, but this material could have been easily presented in half the time, and it would have become more understandable in the process. show less

შონ ქეროლის "მარადისობიდან დღემდე" ერთ-ერთი იმ იშვიათთაგანი წიგნია რომელიც სამყაროს ენტროპიის და დროის ისარის (მიმართულების) პრობლემას ეხება. ქეროლის თქმით თუ თქვენ მოხვდებით რომელიმე show more წამყვანი ინსტიტუტის ბიბლიოთეკაში და დაათვალიერებთ თაროს სადაც ფიზიკის სახელმძღვანელოები და ლიტერატურა აწყვია, ძალიან გაგიჭირდებათ მოძებნოთ წიგნი რომელიც ეხება ენტროპიის და დროის პრობლემას კოსმოლოგიურ კონტექსტში. თერმოდინამიკა როგორც წესი რჩება ლაბორატორიაში, სამზარეულოში და მექანიკაში. აქ სიტუაცია სხვგავარია, ავტორს სამზარეულოს (ლაბორატორიის) პირობების დათვალიერების შემდეგ გადავყავართ უსასრულობაში. სამყაროს "დასაწყისიდან" მის თერმულ სიკვდილამდე, წარმოუდგენლად შორეულ მომავალში, და უკან დიდ აფეთქებამდე არსებულ ჰიპოთეტურ მარადისობაში.

აქ დასმული კითხვები ერთი შეხედვით უცნაურია, "რატომ გვახსოვს წარსული და არა მომავალი?" "რატომ ვბერდებით და ვკვდებით" ანუ რატომ ვერ იქნება ბენჯამენ ბატონის (ფიცჯერალდის ნოველის გმირი) ამბავი რეალობა. "რატომ ქონდა სამყაროს დიდ აფეთქებისას ექსტრემალურად დაბალი ენტროპია?"
საერთოდ რა არის დრო?

თერმოდინამიკის, სპეციალური და ზოგადი ფარდობითობის, კვანტური მექანიკის მიმოხილვის შემდეგ ქეროლი გვთავაზობს ამ ღრმა პრობლემების გადაწყვეტის მონახაზს. ამ მონახაზში, ჩემი აზრით უნიკალური ისიცაა რომ ქეროლი საწყისი დაბალი ენტროპიის პრობლემით მიდის მულტი სამყაროს იდეამდე. მულტი სამყარომდე ბევრი გზა მიდის უმეტესობა დამატებითი განზომილებების, სიმების და კვანტური თეორიების გავლით, ენტროპიის პრობლემა რამდენადმე დამოუკიდებელი და საინტერესოა.

მიუხედავად იმისა რომ ქეროლს კარგი ანალოგიები და მაგალითები აქვს, არ აკლია იუმორის გრძნობაც, ამ ჟანრის (სამეცნიერო პოპულარული ლიტერატურა) დამწყებ მკითხველს ნამდვილად ვერ ვურჩევ. ჰოკინგის და კაკუს ძალიან გამარტივებულ ახსნასთან შედარებით ქეროლი ნამეტანი არ ზრუნავს ყველა დეტალის დაღეჭვაზე. არადა ზოგიერთი საკითხი ძალზედ ჩახლართული და რთულია. ან მოყავს ისეთი არგუმენტი რომელიც არასპეციალისტი და არამეცნიერი მკითხველისთვის არც ისე ნათელია.
წიგნი საინტერესოა იმითაც რომ მისი მიზანი არაა კოსმოლოგიის ზოგადი მიმოხილვა და მთავარი პრობლემების გამოკვეთა. რითიც მაგალითად ჰოკინგის და კაკუს წიგნები გამოირჩევა. არამედ დასახული აქვს კონკრეტული პრობლემა: - დრო. show less

To say this is an ambitious book is an understatement. Just read the subtitle: On the Origins of Life, Meaning and the Universe Itself. The author, Sean Carroll, is a professor of physics at Cal Tech, which alone entitles him to a certain amount of hubris. Moreover, I learned in a YouTube video that he inherited Richard Feynman’s desk (the physical thing) if not his chair (the position within the Cal Tech hierarchy).

Carroll begins by acquainting the reader with what he calls the “Core show more Theory,” (a term coined by Frank Wilczek) which refers to our present understanding of the basic laws of physics. He asserts that the physics of everyday life are completely known, even if we lack complete knowledge about all of physics. He contends that while we may continue to develop deeper understanding or more accurate and precise theories, the current conception of the Core Theory will still be essentially valid a thousand years from now because it works. (That is to say, for example, we can send people into outer space with absolute confidence based on its premises.)

Carroll analyzes in detail the process by which scientists form beliefs about the world. Essentially, we engage in the process described by Bayes’ theorem. (In probability theory, Bayes' theorem describes predicting the probability of an event based on prior knowledge of conditions that might be related to the event.) New information can, however, alter and affect our existing “credences,” or beliefs about what must be true.

As Carroll explains, Leibnitz and Spinoza formulated the “principle of sufficient reason,” the surprisingly controversial theory that there must be a reason why things are the way they are rather than some other way. Carroll points out that man seeks to understand the world in terms of reasons or causes - i.e., "existing credences." David Hume, with whom Carroll agrees, argued that the principle of sufficient reason is an empirical observation, not a law of logic. Hence, there may be things or phenomena that simply do not have explanations. They are brute facts — they just are! To Carroll, the existence of the universe itself, and the fact that it was once in a very low entropy state are just such brute facts. [The physicist Richard Feynman, on the other hand, asserted that everything that appeared mystical was simply an insufficiently explained mystery with a physical answer not yet found.]

Although he is a physicist by training, Carroll has mastered a great deal of evolutionary biology, microbiology, and information theory. He provides a cogent explication of the origin of life and subsequent evolution (with a little help from Charles Darwin) that obviates a theological explanation.

Carroll takes issue with the principle of "intelligent design" to justify unexplained complexity. As Carroll argues, one could make a powerful rebuttal to the intelligent design argument based on an important biological process underlying how our universe works, i.e., that of emergence. “Emergence” refers to the self-organization of complex systems.

Life itself is a classic example of an emergent phenomenon. Scientists have found, for example, that polymers (many molecules all strung together to form really long chains) can and do catalyze the formation of other polymers and a diverse number of reactions by themselves. Something new emerges and starts to form a pattern, and if it has a survival advantage, it will continue to happen. Thus, the whole turns into something different than the parts, and its properties can only be understood at the macro level. Think about trying to predict an avalanche that is made up of only snow or sand. How would you know which single grain of either would be the one to set off the avalanche when they are all the same? Emergence indeed seems “miraculous” but it is predictable, and can be replicated in a laboratory. But there is no reason philosophers would necessarily have knowledge of the process of the autocatalysis that characterizes emergence.

Carroll uses the concept of emergence to discuss free will. In a sense, one’s actions and desires may be “determined” at the atomic level, but an explanation of behavior based on atomic phenomena would simply be too complicated and incomprehensible to attempt. Instead, descriptions of acts and desires on a macro level are useful and comprehensible.

While Carroll is an avowed atheist, he is not as polemical as Richard Dawkins, Sam Harris, or Christopher Hitchens. He is an excellent, hard-headed scientist, but he gets a little touchy-feely when he wanders into philosophy. He espouses a philosophy he calls “poetic naturalism.” Here is how he explains this concept:

"By that I mean to emphasize that, while there is only one world, there are many ways of talking about the world. 'Ways of talking' shouldn’t be underestimated; they can otherwise be labeled 'theories' or 'models' or 'vocabularies' or 'stories,' and if a particular way of talking turns out to be sufficiently accurate and useful, the elements in its corresponding vocabulary deserve to be called real.

The poet Muriel Rukeyser once wrote, 'The universe is made of stories, not atoms.' That is absolutely correct. There is more to the world than what happens; there are the ways we make sense of it by telling its story. The vocabulary we use is not handed to us from outside; it’s ultimately a matter of our choice."

Many other scientists would take issue with Carroll on this. There are too many people who think that anecdotal incidents and opinions should hold the same weight as scientifically derived evidence, to the detriment of our political choices, and ultimately the fate of our planet.

Evaluation: With the few exceptions, and some limitations described below on listening to this as opposed to reading it in hard copy, this is for the most part an excellent book, clearly written with a surprising sense of humor, considering the topic.

A Few Notes on the Audio Production:

I listened to an audio version of the book read by the author. I have watched his lectures on YouTube, where he is an excellent speaker and presenter. However, for this audiobook, he reads in “upspeak.” It is as if every assertion is a question. In addition, in an obvious effort to avoid sexism, whenever he refers to an unidentified individual of an unidentified gender he calls him or her “they” or “them.” That locution has become pretty commonplace, but I find it annoying.

Another shortcoming in listening to the book is that in the epilogue, Carroll states that the Core Theory can be encapsulated in Richard Feynman’s path integral formulation of quantum mechanics. That would be okay, except that that formula is quite complex and simply does not lend itself to being read aloud. One would have to look at it to digest it, but Carroll just reads it.

(JAB) show less