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May 30, 2005

Three Roads to Quantum Gravity

I suspect that the difficulty of the book and the concept in general contributed to the small group showing to discuss Lee Smolin's “Three Roads to Quantum Gravity”. I also had a hard time getting through the book as I felt many concepts were touched upon too briefly. I think that since the author approached the theory of quantum gravity from three different perspectives and each had its own terminology and history, the book would have been three times as long if he had tried to go into more detail. The fact that the book is billed as “It would be hard to imagine a better guide to this difficult subject. -- Scientific American” makes me wonder how bad other books on the topic are.

The book focuses on the history and current state of research into quantum gravity. It is not out to answer all of the questions and assures you that there is still much to be done. This is a very different outcome from many of the other books we have read in the group that had a distinct viewpoint and a definitive ending. The author does maintain a good level of objectivity when talking about the competing theories that are outside of his field of research. He makes a point towards the end of mentioning that in doing so he upset all camps, which in his mind means he found the proper balance between them.

Having read other book about quantum physics in the past I found this book more challenging and felt that for many of the concepts introduced I didn't grasp them. I'd be tempted to read it again, but think that with the general objections raised about the author's approach to the subject I might find a second read more infuriating than rewarding. Instead I'd probably delve into the extensive list of recommended further readings the author includes after the very helpful glossary. Some of the scientific concepts I did pick up are that space and time are defined of discrete indivisible units, black holes emit radiation and as such shrink over time, and that there is the concept of the horizon which hides information from the observer.


I collected a few more notes and references than usual while reading this book and they are listed below:

2: Human perception is too coarse to see the building blocks of nature.
3: Quantum theory was invented to explain why atoms are stable.
9: The three roads are:
1.From quantum theory: based on string theory
2.From relativity: based on loop quantum gravity
3.From new ground: based on questioning the base assumptions, more philosophical, “What is time?”
17: There is nothing outside the universe.
20: The world is nothing but an evolving network of relationships.
27: We will never be able to see the entire universe. Based on the size of the universe and speed of light.
34: Only one mathematical model for quantum theory, but a multitude of interpretations.
48: One universe, sen by many observers, rather than many universes, seen by one mythical observer outside the universe.
51: Stories are best to describe processes (like humans) that unfold over time, versus a description of an object like a rock.
52: Artists cannot turn a process into a thing.
52: But even rocks have stories that just take place over longer time periods.
58: The cone of light determines what events could possibly influence or be influenced by other events.
59: Relationships between events is the causal structure of a universe.
62: Smoothness of space and time are illusions; really discrete events that can be counted.
62: Plank scale: 10^-23 cm, 10^-43 second.
63: Big bang is really the big freeze as the Plank temperature is hotter than anything in the universe.
75: Black holes stretch the wavelengths of light that are close but don't get sucked into into.
79: Mass increases as you approach the speed of light.
92: Black hole evaporation is the process in which a black hole decreases in mass due to Hawking radiation.
93: Entropy is a measure of missing information.
94: What is the nature of the information trapped in a black hole?

Wonderful Life

I have to disagree with the general theme of Stephen Jay Gould's “Wonderful Life”. I don't place as high an emphasis on chance/luck as he does. I think if you were to wind back time you could predict the outcome again with a high degree of certainty. The problem, which is easier to explain if you say it is luck, is that the number of variables that go into one species surviving over another are too difficult to track and analyze over any reasonable time scale. Evolution is still about adaptation to the changing environment, the problem is the environment is constantly changing, so what made one species the most adapted a minute ago might have changed (think asteroid hitting the earth). This is why I think you can predict what will survive if you play out all of the what-if scenarios, provided you can think of them all. The shear number of interdependencies between everything makes this unrealistic, hence luck can instead be used to explain the outcome.

The author's discussion on the impact that visual representation can have on a concept was great and I think has lead to the misconception of equating evolution with progress, which is isn't. I could have done without the middle section of the book where every creature from the Burgess Shale was described in detail. I felt like the author wanted to give the reader a taste of what it was like to reread all of the highly technical descriptions of those animals by the teams that reexamined them.


32: Evolution, to professionals, is adaptation to changing environments, not progress.
38: Branches in the tree of life don't join for animals but can in plants.
39: Typical tree of life graphs promote a “placement in time is conflated with judgment of worth” view.
44: Perhaps we are only an afterthought, a kind of cosmic accident, just one bauble on the Christmas tree of evolution.
48: Evolution is part luck, the “replaying life's tape” experiment.
54: History of life is not a continuum, but includes brief periods of extreme change such as geological mass extinction.
56: Why did multicellular life appear so late?
129: Science is a process of correction.
213: Homology and analogy similarities play an important role. Homology is simple inheritance of features present in common ancestors An example is the number of neck vertebrae is the same for humans, giraffes, and bats. Analogy is separate evolution for the same function. An example is the wings of birds, bats, and pterosaurs.
228: Three evolutionary theories on the disparity in the Burgess:
1.There was an abundance of empty space to fill allowing almost any kind of organism design to be tried and survive for awhile.
2.The organisms were more flexible allowing more designs to be tried for the same solution by sharing a common ancestor.
3.Organisms experienced large jumps that allowed certain ones to flourish as the multicellular life form was still in the early stages of evolving.
234: Better survival is a prediction to be tested, not a definition of adaptation.
276: Scientific innovation is usually stifled by conceptual problems, but factual.
284: The replay concept is appealing since it is a history that did not have to be, any number of changes in the reply would have produced a different outcome.
320: Homo sapiens are an entity, not a tendency.

May 22, 2005

A foot high

To badly paraphrase a quote: "If your stack of technology magazines ever gets more than a foot tall, throw them all out. The technology has already changed." I can't find the original using Google right now, I'm sure it had more wit :)

I bring the quote up since my magazine stack has reached this point. Magazine Stack

I think two factors played into this backlog. First is that during my commute I've changed to reading The Economist instead of the latest technology magazine. I made the switch a year ago to get a foreign perspective on world events, particularly related to the Iraqi war.

Secondly, for about six months, I just got sick of technology. The computer industry moves at a break neck pace and to keep track at any meaningful level requires constant attention. It wasn't information overload, it was more about trying to retreat and figure out what in the landscape I cared enough about to want to devote time to.

That in itself is a thought that I'd spent time on recently. What are my priorities? I'm interested in too many things only adds to the amount of information I'd have to read to stay current. Blah. Lost of train of thought.

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