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# Three Roads To Quantum Gravity (Science Masters Series)

by
Lee Smolin

The Holy Grail of modern physics is a theory of the universe that unites two seemingly opposing pillars of modern science: Einstein's theory of general relativity, which deals with large-scale phenomena (planets, solar systems and galaxies), and quantum theory, which deals with the world of the very small (molecules, atoms, electrons). In Three Roads to Quantum Gravity, Le
...more

Paperback, 256 pages

Published
July 4th 2002
by Basic Books
(first published 2000)

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## Community Reviews

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When he wrote this book, around 1999, I think he was more part of the mainstream. He presents several different approaches to the very difficult problem of unifying gravity and quantum mechanics. It's clear that his heart belongs to ...more

This book isn't too bad but I don't think I retain much. the feline analogy and cosmological evolution are cute ideas, and the black hole stuff is fascinating. but much of it is extremely speculative and cryptic rambling. Or maybe I just get more cynical of theoretical physics day by day. That's fine, and at least Lee Smolin acknowledges that it is speculative, but at least don't be so incredibly ...more

but thank the lord most of the ...more

**DNF!**

I'm sorry. Even from the (relatively) short part I read it's clear Smolin is a brilliant scientist, but a writer he is not. The writing is just painful, rambling at times. Very little is explained, and what is explained is done so in the most simplistic ways by comparing certain concepts in quantum theory with daily life events that might work had Smolin not drawn it out to the max, making me forget what he was trying to explain in the first place. This book and I, unfortunately, must part w ...more

At the minutest level of reality (spacetime on Planck scale) are strings (“a string is actually made of discrete pieces, called string bits, each of which carries a discrete amount of momentum and energy”). Part ...more

Since the postulation of theory of relativity (theory of cosmos, which describes the structure of space and time), and quantum mechanics (laws of microcosm, which describes atomic structure, nuclear forces, and nature of basic component of matter); physicists until now have struggled to explain gravity (which is a manifestation of spacetime fabric in presence of matter) in terms of quantum mechanics (quantum gravity). In this book the author attempts to exp ...more

Feb 12, 2015
Gaurav EVHS Desale
added it

Divide an inch in two. Now divide each half again, and then repeat the division, over and over. Can you go on for ever, or do the laws of physics eventually get in the way? Is the fabric of space infinitely divisible, or is it ultimately made up of "atoms" - tiny chunks of space that can never be split?

This question may seem almost unanswerable. But as physicist Lee Smolin writes in Three Roads to Quantum Gravity , some of the newest ideas in physics are pointing to a surprising answer: space an ...more

This question may seem almost unanswerable. But as physicist Lee Smolin writes in Three Roads to Quantum Gravity , some of the newest ideas in physics are pointing to a surprising answer: space an ...more

I found this work to be brilliant and very thought-provoking and would highly recommend it to anyone w ...more

Smolin starts out string, the first few chapters regarding "why we don't ask what's outside the universe" and "why classical logic is unsuitable for cosmology (and real life)" were really great. As you make it further into the book things fall apart a littl ...more

I think this one is better by far than Gre ...more

"...the first principle of cosmology must be 'There is nothing outside the universe' . . . This first principle means that we take the universe to be, by definition, a closed system. It means that the explanation for anything in the universe can involve only other things that also exist in the universe . . . ...more

Feb 16, 2009
DJ
rated it
really liked it

Recommends it for:
any young scientist interested in today's fundamental questions in physics

Shelves:
popular-physics

Lee Smolin stormed his way onto my fantasy grandfather list the fateful summer of 2008 when I realized physics and I were more than just a fling. His The Trouble with Physics was a fatherly introduction to the current state of the edges of theoretical physics and I was hooked. Needless to see, I was ecstatic to find "Three Roads to Quantum Gravity" under my Christmas tree this year and devoured it on plane ride to Thailand soon after.

"Three Roads to Quantum Gravity" is Smolin's briefing to the p ...more

"Three Roads to Quantum Gravity" is Smolin's briefing to the p ...more

"The Holy Grail of modern physics is the theory of 'quantum gravity'. It is a search for a view of the Universe that unites two seemingly opposed pillars of modern science..." et cetera. Let's unpack these two sentences. The first mentions the Holy Grail, which I think is not the right analogy for a mathematical description of spacetime. I seem to remember the Holy Grail as the one identified by In ...more

"We shall have the basic framework of the quantum theory of gravity by 2010, 2015 at the outside.", he says on the last page.

The book was published in 2001. We're in 2014 and we're still nowhere near a solution. Although he hints in Time Reborn that we need a new descriptive language for a unifying theory of gravity which ought to have non-mathematical tools and which must include time as a fundamental building block.

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

The author gives a very solid and understandable overview of the main avenues o ...more

Still, Smolin does give very detailed explanations for the different versions of String Theory, Loop Quantum Gr ...more

I passed it along to some Christian friends who enjoy advanced science - you might think that a book of superb science, founded in relativity ...more

En ollut oikeastaan koskaan ennen lukenut silmukkakvanttipainovoimasta. Liekö syy, että siitä ei ole tullut mitään sitten viimeisen 15 vuoteen, vai omasta lukemattomuudestani? Onko ehdotuksia lisäsmolineiksi?

Niin ja otsikossa puhutaan kolmesta tiestä. Se kolmas liittyee mustien aukkoje ...more

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Lee Smolin is a theoretical physicist who has made influential contributions to the search for a unification of physics. He is a founding faculty member of the Perimeter Institute for Theoretical Physics. His previous books include The Trouble with Physics, The Life of the Cosmos and Three Roads to Quantum Gravity.

More about Lee Smolin...
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Manny wrote: "We can't possibly predict what a unified theory would lead to. When people were developing the foundations of quantum mechanics in the 1...moreNov 30, 2015 04:04PM

Fortunr wrote: "Robert wrote: "Well, we are agreed on the matter of how many good books there are! Feynman's QED is an excellent layman's intro to his...moreNov 30, 2015 04:12PM