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The Elegant Universe: Superstrings, Hidden…
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The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory (original 1999; edition 2003)

by Brian Greene (Author)

MembersReviewsPopularityAverage ratingConversations / Mentions
9,09183877 (3.97)1 / 153
Well-written, fascinating look at the development of special and general relativity—and the omissions that are driving theoretical research ever since. HOWEVER, and this is a huge caveat, most of the book may be chronicling a misfire. (Lee Smolin's book THE TROUBLE WITH PHYSICS makes a good case for String Theory's failures; I'm about to re-read it to refresh my memory, so I can't go into too much detail yet.)

Greene's storytelling is certainly seductive, but a lot of String Theory's appeal is getting the same results as other theories, but in a more elegant fashion. This is a good thing because it means the theory avoids being outright wrong, but makes it difficult to find results that'll uniquely support strings, and not just the mass of other popular theories.

More troublingly, the experimental evidence that might support strings or these other theories simply isn't showing up. The Large Hadron Collider found the Higgs Boson, but has yet to uncover ANY signs of supersymmetry—the linchpin of string theory and other popular proposals. Oops. Of course, there are always other variants that hold out the hope that supersymmetric partners are just higher mass and harder to reach, but constant tweaking and adjustment kinda undermines the original claims to elegance!

When the book is standing on firmer ground, it's marvelous; Greene is a fantastic writer and explainer. But as an argument for String Theory? Reader beware. ( )
1 vote gregorybrown | Oct 18, 2015 |
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There is a lot in this book. It's taken me quite a while to read it and even longer to review it. For my own interest, I've tried to capture some of the really interesting gems ...much of it historical and going over material that I'm reasonably familiar with. But often, Greene throws in a helpful analogy or a new slant on things. For example, his explanation of the hoary old example of space being deformed like a bowling ball on a trampoline...this has always mystified me as the example has one dimension but space has three or more dimensions, and Greene goes to lengths to try and explain this). However, in the latter part of the book Greene gets into string theory. Clearly, he is a true believer and often simply states that classic theory is inadequate at this point, therefore we MUST use string theory. Well maybe, but there are a lot of eminent scientists around who just don't buy into string theory (Roger Penrose for example). So I was left vaguely unhappy with the book. Nevertheless some good material in it. Here are some interesting extracts from the book.

"..During the past half-century, physicists of each new generation, through fits and starts, and diversions down blind alleys-have been building steadily on the discoveries of their predecessors to piece together an ever fuller understanding of how the universe works.........And now, long after Einstein articulated his quest for a unified theory but came up empty-handed, physicists believe they have finally found a framework for stitching these insights together into a seamless whole a single theory". [Presumably, Greene thinks this is string theory].

"We can speak about the motion of an object, but only relative to or by comparison with another. There is thus no meaning to the statement "George is traveling at 10 miles per hour," as we have not specified any other object for comparison. There is meaning to the statement "George is traveling at 10 miles per hour past Gracie," as we have now specified Gracie as the benchmark........Although at first it sounds completely ridiculous, unlike what happens if one runs from an oncoming baseball, grenade. or avalanche, the speed of approaching photons is always 670 million miles per hour. The same is true if you run toward oncoming photons or chase after them -their speed of approach or recession is completely unchanged; they still appear to travel at 670 million miles per hour".

For instance, Newton's theory of gravity claims that if the sun were suddenly to explode, the earth- some 93 million miles away would instantaneously suffer a departure from its usual elliptical orbit.....Einstein called the indistinguishability between accelerated motion and gravity the equivalence principle? It plays a central role in general relativity.

With the classic example of a ball on a rubber membrane....An important point to note is that the ball bearing itself warps the rubber membrane, although only slightly. Similarly, the earth, being a massive body in its own right, also warps the fabric of space, although far less than the sun.....When the sun causes the fabric of space around it to warp this is not due to its "being pulled downward" by gravity as in the case of the bowling ball, which warps the rubber membrane because it is pulled earthward by gravity. In the case of the sun, there is no other object to "do the pulling." Instead, Einstein has taught us that the warping of space is gravity. The mere presence of an object with mass causes space to respond by warping.....Einstein showed that objects move through space (spacetime, more precisely) along the shortest possible paths- the "easiest possible paths" or the "paths of least resistance." If the space is warped, such paths will be curved. (I assume that this is with respect to some hypothetical outside observer because a "straight line" in this space time is the "line of least resistance". There is no other way to measure a straight line .....). ..........A second shortcoming of the analogy stems from the rubber membrane's being two-dimensional. In reality, although harder to visualize, the sun (and all other massive objects) actually warps the three-dimensional space surrounding it. Figure 3.6 is a rough attempt to depict this; all of the space surrounding the sun- "below," "on the sides," on "top"-suffers the same kind of distortion. I give credit to Greene here. I've never seen any other author make this point and it's always worried me that the examples given of the bowling ball on a trampoline etc were woefully inadequate to explain the warping of space time in multiple dimensions........A third, related shortcoming of the analogy is that we have suppressed the time dimension....... But....acceleration- and hence gravity warps both space and time.

Space: When no mass is present, space is flat, and a small object [seems to be a mass to me] will blissfully be at rest or will travel at a constant velocity. If a large mass comes on the scene, space will warp.....but, as in the case of the membrane, the distortion will not be instantaneous. Rather, it will spread outward from the massive body, ultimately settling down into a warped shape that communicates the gravitational pull of the new body. [Presumably this distortion can only travel at the speed of light?]

By offering the explanation for the expansion of the universe, Einstein achieved one of the greatest intellectual feats of all time. Extrapolating all the way back to "the beginning," the universe would appear to have begun as a point--an image we will critically re-examine in later chapters- in which all matter and energy is squeezed together to unimaginable density and temperature. It is believed that a cosmic fireball, the big bang, erupted from this volatile mixture spewing forth the seeds from which the universe as we know it evolved. In the big bang. there is no surrounding space...... the big bang is the eruption of compressed space whose unfurling, like a tidal wave, carries along matter and energy even to this day. [I've often wondered why we have to extrapolate backwards all the way to a point. Yes we can do that but maybe the universe actually expanded from some a sphere of some finite magnitude....maybe the size postulated for the universe at the end of the hypothesised rapid inflation. Why do we have to assume we have to extrapolate back to a point?]

It's pretty impressive that "No deviations from the predictions of general relativity have been found in experiments performed with our present level of technology".

The frequency of the light (its color) determines the speed of the ejected electrons; the total intensity of the light determines the number of ejected electrons. And so Einstein showed that Planck's guess of lumpy energy actually reflects a fundamental feature of electromagnetic waves: They are composed of particles: photons- that are little bundles, or quanta, of light. The photoelectric effect shows that light has particle properties. The double-slit experiment shows that light manifests the interference properties of waves. Together they show that light has both wave-like and particle-like properties.......Inspired by a chain of reasoning rooted in Einstein's special relativity, de Broglie suggested that the wave particle duality applied not only to light but to matter as well.

Davisson and Germer examined electrons making it through the two slits....... Their experiment therefore showed that electrons exhibit interference phenomena, the telltale sign of waves...... similar experiments lead to the conclusion that all matter has a wave-like character...... de Broglie set down a formula for the wavelength of matter waves, and it shows that the wavelength is proportional to Planck's constant h. (More precisely, the wavelength is given by h divided by the material body's momentum.) Since this so small, the resulting wavelengths are similarly minuscule compared with everyday scales.

But waves of what?...... Born's suggestion is one of the strangest features of quantum theory, but is supported nonetheless by an enormous amount of experimental data. He asserted that an electron wave must be interpreted from the standpoint of probability.

Feynman argued that in traveling from the source to a given point on the phosphorescent screen each individual electron actually traverses every possible trajectory simultaneously;......Feynman showed that he could assign a number to each of these paths in such a way that their combined average yields exactly the same result for the probability calculated using the wave-function approach. (I recall that he did this using the calculations of multiple graduate students...must have been hell working for him).

Just as Heisenberg showed that there is a trade-off between the precision of measurements of position and velocity, he also showed that there is a similar trade-off in the precision of energy measurements and how long one takes to do the measurement. Quantum mechanics asserts that you can't say that a particle has precisely such-and-such energy at precisely such-and-such moment in time. Ever increasing precision of energy measurements require ever longer durations to carry them out.

Since the borrowing and repaying on average cancel each other out, an empty region of space looks calm and placid when examined with all but microscopic precision. The uncertainty principle, however, reveals that macroscopic averaging obscures a wealth of microscopic activity. 'As we will see shortly, this frenzy is the obstacle to merging general relativity and quantum mechanics.

They [physicists in 1930’s-1940’s] found that Schrödinger's quantum wave equation was actually only an approximate description of microscopic physics- an approximation that works extremely well when one does not probe too deeply into the microscopic frenzy (either experimentally or theoretically), but that certainly fails if one does.......... Through a series of inspirational developments, they created quantum electrodynamics. This is an example of what has come to be called a relativistic quantum field theory, or a quantum field theory, The success of quantum electrodynamics inspired other physicists in the 1960s and 1970s to try an analogous approach for developing a quantum-mechanical understanding of the weak, the strong, and the gravitational forces. For the weak and the strong forces, this proved to be an immensely fruitful line of attack. In analogy with quantum electrodynamics, physicists were able to construct quantum field theories for the strong and the weak forces, called quantum chromodynamics and quantum electroweak theory.

Glashow, Salam, and Weinberg showed, in essence, that at high enough energy and temperature such as occurred a mere fraction of a second after the big bang electromagnetic and weak force fields dissolve into one another, take on indistinguishable characteristics, and are more accurately called electroweak fields. When the temperature drops, as it has done steadily since the big bang, the electromagnetic and weak forces crystallize out.

According to the standard model, just as the photon is the smallest constituent of an electromagnetic field, the strong and the weak force fields have smallest constituents as well. As we discussed briefly in Chapter 1, the smallest bundles of the strong force are known as gluons, and those of the weak force are known as weak gauge bosons (or more precisely, the W and Z bosons)....For like-charged particles, the photon carries the message "move apart," while for oppositely charged particles it carries the message "come together."....... . Similarly, the gluons and weak gauge bosons are the messenger particles for the strong and weak nuclear forces....... the odd man out in our discussion of the quantum theory of the forces of nature is gravity.

If the three colors- the three different strong charges -that a quark can carry were all shifted in a particular manner (roughly speaking, in our fanciful chromatic language, if red, green, and blue were shifted, for instance, to yellow, indigo, and violet). and even if the details of this shift were to change from moment to moment or from place to place, the interactions between the quarks would be, again, completely unchanged. For this reason, just as we say that a sphere exemplifies rotational symmetry because it looks the same regardless of how we rotate it around in our hands or how we shift the angle from which we view it, we say that the universe exemplifies strong force symmetry: Physics is unchanged by...... it is completely insensitive to...... these force-charge shifts. For historical reasons, physicists also say that the strong force symmetry is an example of a gauge symmetry........ For the case of the gauge symmetry associated with shifting quark-color charges, the required force is none other than the strong force itself.

I found the following explanations of "quantum foam" to be especially helpful....."from a purely classical standpoint, we would expect this placid and flat image of space to persist all the way to arbitrarily small length scales. But quantum mechanics changes this conclusion radically. Everything is subject to the quantum fluctuations inherent in the uncertainty principle even the gravitational field. Although classical reasoning implies that empty space has zero gravitational field, quantum mechanics shows that on average it is zero, but that its actual value undulates up and down due to quantum fluctuations. Moreover, the uncertainty principle tells us that the size of the undulations of the gravitational field gets larger as we focus our attention on smaller regions of space"........It is on such short distance scales that we encounter the fundamental incompatibility between general relativity and quantum mechanics. The notion of a smooth spatial geometry, the central principle of general relativity, is destroyed by the violent fluctuations of the quantum world on short distance scales. On ultramicroscopic scales, the central feature of quantum mechanics-the uncertainty principle is in direct conflict with the central feature of general relativity the smooth geometrical model of space (and of spacetime)......But note that you become aware of the discrete nature of the picture only when you examine it on the smallest of scales; from far away it looks smooth. Similarly, the fabric of space-time appears to be smooth except when examined with ultramicroscopie precision. This is why general relativity works on large enough distance (and time) scales the scales relevant for many typical astronomical applications but is rendered inconsistent on short distance (and time).

All objects undergo quantum jitter,....... This holds true for the loops in string theory as well; no matter how placid a string appears it will always experience some amount of quantum vibration. The remarkable thing, as originally worked out in the 1970s, is that there can be energy cancellations between these quantum jitters and the more intuitive kind of string vibrations....... As an important example, Scherk and Schwarz found that for the vibrational pattern whose properties make it a candidate for the graviton messenger particle, the energy cancellations are perfect, resulting in a zero-mass gravitational-force particle. This is precisely what is expected for the graviton; the gravitational force is transmitted at light speed and only massless particles travel at this maximal velocity.

If string theory is right, each of the infinitely many resonant patterns of string vibration should correspond to an elementary particle. An essential point, however, is that the high string tension ensures that all but a few of these vibrational patterns will correspond to extremely heavy particles (the few being the lowest-energy vibrations that have near-perfect cancellations with quantum string jitters). And again, the term "heavy" here means many times heavier than the Planck mass......when quantum mechanics is taken into account, continually increasing the energy of a string does not continually increase its ability to probe finer structures, in direct contrast with what happens for a point particle........ The upshot is that no matter how hard you try, the extended nature of a string prevents you from using it to probe phenomena on sub-Planck-length distances. [This seems to me to be a significant problem for string theory].

In a universe governed by the laws of string theory, the conventional notion that we can always dissect nature on ever smaller distances, without limit, is not true. There is a limit, and it comes into play before we encounter the devastating quantum foam of Figure 5.1. Therefore, in a sense ....., one can even say that the supposed tempestuous sub-Planckian quantum undulations do not exist. A positivist would say that something exists only if it can at least in principle-be probed and measured..... String theory tells us that we encountered these problems only because we did not understand the true rules of the game; the new rules tell us that there is a limit to how finely we can probe the universe and, in a real sense, a limit to how finely our conventional notion of distance can even be applied to the ultramicroscopic structure of the cosmos. The supposed pernicious spatial fluctuations are now seen to have arisen in our theories because we were unaware of these limits and were thus led by a point particle approach to grossly overstep the bounds of physical reality.

Physicists describe these two properties of physical laws —that they do not depend on when or where you use them —as symmetries of nature. By this usage physicists mean that nature treats every moment in time and every location in space identically symmetrically—by ensuring that the same fundamental laws are in operation........ Through the equivalence principle of general relativity, Einstein sig nificantly extended this symmetry by showing that the laws of physics are actually identical for all observers, even if they are undergoing complicated accelerated motion...... if you perform some experiment and then decide to rotate all of your equipment and do the experiment again, the same laws should apply....This is known as rotational symmetry, and it means that the laws of physics treat all possible orientations on equal footing........ there is [also] a quantum-mechanical notion of spin that is somewhat akin to the usual image but inherently quantum mechanical in nature.

If the particular Calabi-Yau shape singled out by the equations of the theory were to have three holes, we would have found an impressive postdiction from string theory explaining a known feature of the world that is otherwise completely mysterious. But finding the principle for choosing among Calabi-Yau shapes is a problem that as yet remains unsolved. Nevertheless—and this is the important point—we see that string theory provides the potential for answering this basic puzzle of particle physics, and this in itself is substantial progress....... there are examples of Calabi-Yau spaces that, when chosen for the curled-up dimensions required by string theory, give rise to string vibrations that are closely akin to the particles of the standard model. [This is starting to sound like a bit of an apology for string theory]

"....the density of the universe at the Planck time was simply colossal. At such energies and densities gravity and quantum mechanics can no longer be treated as two separate entities as they are in point-particle quantum field theory. Instead, the central message of this book is that at and beyond these enormous energies we must invoke string theory. In temporal terms, we encounter these energies and densities when we probe earlier than the Planck time of 10+3 seconds ATB, and hence this earliest epoch is the cosmological arena of string theory.

For our present purpose, the important thing to note is that the phase transition results in a decrease in the amount of symmetry displayed by the H2O molecules. Whereas liquid water looks the same regardless of the angle from which it is viewed it appears to be rotationally symmetric-solid ice is different. It has a crystalline block structure, which means that if you examine it with adequate precision, it will, like any crystal, look different from different angles. The phase transition has resulted in a decrease in the amount of rotational symmetry that is manifest.

At time zero, as the size of the universe vanishes, the temperature and density soar to infinity, giving us the most extreme signal that this theoretical model of the universe, firmly rooted in the classical gravitational framework of general relativity, has completely broken down.
Nature is telling us emphatically that under such conditions we must merge general relativity and quantum mechanics-in other words, we must make use of string theory. [I'm surprised that Greene harbours no other ideas...just string theory]

Valiant attempts by physicists such as Hawking and James Hartle of the University of California at Santa Barbara have tried to bring the question of cosmological initial conditions within the umbrella of physical theory, but all such attempts remain inconclusive. In the context of string/M-theory, our cosmological understanding is, at present, just too primitive to determine whether our candidate "theory of everything" truly lives up to its name and determines its own cosmological initial conditions,....Rather, it appears that the complete formulation of string/M-theory must break the traditional mold and spring into existence as a full-fledged quantum-mechanical theory........Currently, no one knows how to do this........ With guarded optimism, we can envision that a reframing of the principles of quantum mechanics within string theory may yield a more powerful formalism that is capable of giving us an answer to the question of how the universe began and why there are such things as space and time.

Among the many features of string theory that we have discussed in the preceding chapters, the following three are perhaps the most important ones to keep firmly in mind. First, gravity and quantum mechanics are part and parcel of how the universe works and therefore any purported unified theory must incorporate both. String theory accomplishes this. Second, studies by physicists over the past century have revealed that there are other key ideas many of which have been experimentally confirmed that appear central to our understanding of the universe. These include the concepts of spin, the family structure of matter particles, messenger particles, gauge symmetry, the equivalence principle, symmetry breaking, and supersymmetry, to name a few. All of these concepts emerge naturally from string theory. Third, unlike more conventional theories such as the standard model, which has 19 free parameters that can be adjusted to ensure agreement with experimental measurements, string theory has no adjustable parameters. In principle, its implications should be thoroughly definitive they should provide an unambiguous test of whether the theory is right or wrong........ No doubt, achieving a full understanding of string/M-theory will require a great deal of hard work and an equal amount of ingenuity.

And that sort of sums it up. Greene reckons string theory has the potential to give us the answers but we still don't have the answers. My concern is that many other eminent researchers think that string theory leads nowhere and that there are so many parameters that you can "prove" anything. So I'm left with very mixed feelings about the book. The universe might be elegant but Greene's explanations are not. I still give it five stars. ( )
  booktsunami | Jan 8, 2024 |
Heavy material but written in a way that’s easy to digest.
Very solid writing style overall as I’ve enjoyed many books by this author. ( )
  sarahthescribbler | Jan 7, 2024 |
I read this string theory & quantum physics stuff & it is so far removed from our everyday lived experiences that I cannot wrap my head around it. I feel as though there will come a breakthrough of much greater simplicity. ( )
  BBrookes | Dec 2, 2023 |
First, despite being 20 years old, this book isn't particularly dated. Lots of questions about string theory still remain.

Greene writes very clearly as he describes first the theories of Einstein and of Quantum Mechanics, then why they don't reconcile with each other and how string theory brings them together--at least in theory. As a non-scientist, I am still not 100 percent certain how physicists can derive so many facts from an unproven theory, but Greene explains things about as well as it is possible to do so. I found it a compelling and not particularly difficult read. Before I read the book, I had watched Greene's PBS series based on it (and Greene's second PBS series based on his later book, The Fabric of the Cosmos.) This predisposed me to like the book and its author, since Greene's star power and ability to communicate complex ideas quite clearly is pretty amazing. If you're buying this book used, try to get a copy with the updated preface and epilogue. ( )
  datrappert | Aug 23, 2023 |
Green is one of the best at explaining concepts of science. ( )
  mykl-s | Aug 11, 2023 |
Not bad, but probably the most difficult book I have ever read. I think I understood about 10% of it. ( )
  zeh | Jun 3, 2023 |
A good, layperson's introduction to string theory by a prominent physicist. The NOVA specials on P.B.S. are better, but go here for some more meat. For someone like myself who is interested in physics but not scientifically or mathematically inclined, this is a good book on the subject. ( )
  tuckerresearch | Jan 4, 2023 |
Read in high school and opened my mind on why the teacher was actually burning for physics apart from the lame stuff he had to teach about. ( )
  Schnapsbrenner | Oct 17, 2022 |
An excellent explanation of a theory we've all heard of but which few non-physicists, I fear, have much grasp of. Building up from the basics, through general relativity and quantum mechanics, Greene paints a phenomenally rich and compelling picture of superstring theory (and its derivatives) with analogies perfectly suited to make this ephemeral set of ideas intuitive. I'm convinced! A must-read. ( )
  KatherineJaneWright | Jul 17, 2022 |
7/8/22
  laplantelibrary | Jul 8, 2022 |
Not my cup of tea. I have the 1999 edition and had high hopes for gaining insights into the current state of universe, but it was not to be. What I did find was a somewhat self-aggrandizing tome on theoretical notions, guesses and suppositions amid a plethora of name-dropping episodes wholly absent in comparable books such at Einsteins' "Relativity," Feynman's "QED" and Hawking's "The Grand Design." Green's arguments and explanations elbows-rubbing incidents reminded me of those heated theological battles over the potential number of dancing angels on the head of a pin. Like I said, not my cup of tea. ( )
  Renzomalo | Jul 21, 2021 |
My belief is based on the fact that string theory is the first science in hundreds of years to be pursued in pre-Baconian fashion, without any adequate experimental guidance.

Philip Warren Anderson




Since the middle of the 20th century, the fundamental problem of physics has been finding the Theory of Everything: A theory that would reconcile Relativity, Einstein's theory of the very large; to live alongside of Quantum Mechanics, the paradoxical theory of probabilities on the subatomic level. Both worldviews have been proved, insofar as any scientific theory is ever proved. And neither will allow for the other to be completely correct.

Professor Greene (who disdains the title of "Professor" or "Doctor", by omission) explains the two theories very well, even to someone who has read about them innumerable times. (In particular, his explanations of Relativity are extraordinary well done.)

This incredible clarity of purpose and prose continues when he continues into string theory, quantum gravity, and M-theory, although it is dimmed a bit. The book is not math-heavy by any means, relegating such diversions to the endnotes.

(Unfortunately, there are also many fascinating historical explanations relegated to these same notes. Turning to an endnote, the reader never knows if they'll find an historical illumination, or a block of equations.)

Apparently, the world is composed of scores of vibrating, undulating loops of string, looped through dimensions beyond our perception. These explanations are are deftly written, and hold the readers attention well. When the narrative moves along to the five competing string theories, and to M-theory, the One Ring of that will unite modern physics, the story becomes a little difficult to follow. But this is a minor quibble.

When the author details his own small contribution to the field, it is downplayed, giving much credit to his collaborators. A sense of barely contained pride is present in the text simultaneously, giving a wonderful tension to this chapter.

Since string theory is unproven, the book can't help but end on a tenuous note. The author is hopeful that technology will advance to the point where it is possible to prove that superstring theory is more than a blue-sky physicist's dream. ( )
  neilneil | Dec 7, 2020 |
This was my breakthrough book with General Relativity.

I remember reading it on a plane as a teenager and when the author's analogies (which are great) of Einstein's General Theory of Relativity finally broke through to me, something switched on in my brain. My jaw literally dropped, and I looked out over the clouds, into the stars, with absolute disbelief. At that moment, my entire understand of the world around me, and in me, was profoundly and forever changed. I almost cried when I understood the implications of relativity.

As the book continues on, however, the author seems to leave the layman behind. Perhaps I am sub-layman, and others who consider themselves laymen found the latter quantum mechanics chapters easy to grapple with. But I lost my ability to comprehend his writing as the theories and jargon piled on heavier and heavier.

And don't get me started on the string theory chapters. What the hell is string theory. Like seriously.

In conclusion, I must rate this book highly because it was my first taste of the world of relativity, but I can't say I got much out of the quantum mechanics or string theory because they were just too tough to handle.

Maybe I'm just dumb.

( )
  TwilightLoki | Jul 27, 2020 |
De vez en cuando surge un maestro de la divulgación científica. Brian Greene saltó a la fama de la divulgación científica con este libro. Se trata de una introducción a la teoría de cuerdas, una de las estructuras intelectuales más complejas paridas por la mente humana. El estilo es muy claro y ameno -se ve que el autor se divierte escribiendo- y resulta una lectura apasionante y muy enriquecedora incluso para lectores con formación física, pues las ideas de las que habla no están en la carrera. El libro tuvo tanto éxito que hasta hicieron un documental, con el propio Greene como presentador. Y es un documental muy bueno. Los lectores pueden descargárselo gratuitamente (en inglés) de aquí. Ahora Greene ha sacado un nuevo libro, The fabric of Cosmos, que he empezado a leer. En él se habla de la estructura del espaciotiempo, nada menos, pero el estilo sigue siendo ameno. Y el libro es muy interesante, desde luego. Mi nota para éste es Muy, muy bueno. ( )
  Remocpi | Apr 22, 2020 |
Letto con il dubbio di leggere qualcosa di superato (1999) ho trovato l'ennesima riprova della mia assoluta incapacità di comprendere cose che fatico ad immaginare ed immaginare cose incomprensibili. Bellissimo in ħ. ( )
  gi0rgi0 | Mar 25, 2020 |
Greene is an interesting physicist. I'm not sure many more "traditional" physicists would always agree with his ideas, but they make for interesting reading and thinking. This is a typical example and thus recommended. ( )
  scottcholstad | Jan 15, 2020 |
Whenever I try to read popular science books like this it feels like every sentence is an important idea, and when one enters my brain, two others get ejected and I end up dumber than when I started. Maybe there's a law of physics that will explain that. Too bad I won't remember it!

Finally finished! A great book for the non-science-y who want some understanding of string theory without the math. It was slow reading and I had to take notes to remember things, but still enjoyable reading. Greene explains everything so clearly, uses great analogies, and has a wonderful way with words to boot. ( )
  badube | Mar 6, 2019 |
The Elegant Universe is a popular explanation of string theory. Yet, it is so much more than that. It is an illumination of the fascinating journey that physics has taken since Isaac Newton.

Starting with a brief overview of Newton's mechanics, dr. Greene then delves into fairly detailed non-mathematical descriptions of both Einstein's special and general relativity. Quantum mechanics is then briefly examined, especially the quantum weirdness phenomena and the uncertainty principle.

Then it's on about the super-symmetrical string theory, the physics' latest attempt to merge the generally hostile general relativity and quantum theories into a single theory describing all of nature's forces, including gravity.

Learn how this theory builds on the premise that the universe is built from tiny strings whose vibrations produce elementary particles such as photons, how there are likely more than three spatial dimensions, how transformations of these tiny dimensions create self-repairing rips in the fabric of space and how it all affects the cosmos around us.

Lucidly written in a clear, non-technical style, it is a pleasure to read as the author steers clear of both too convoluted popular culture references (like Cartman rolling down the hill in Hidden Universes) and from too inside-baseball like descriptions of the science and mathematics behind it.

One of the best popular science books that I've read. It is bound to blow your mind and bring you up to date on the state of modern physics, even though it's not of the newest date. Hopefully in the future dr. Greene will take the time to write a follow-up to bring us up to speed on the newest developments in string/M-theory. ( )
  matija2019 | Jan 8, 2019 |
(Original review, 2001)

The Kabbalah also describes 10 dimensions and beings that inhabit them. Perhaps these beings are real and at certain levels of dimensional perception they have already seen and experienced these advancements in human history like a child being taught 2+2 to the wave compilation of an electron Y=h/mc = 2.43*10-12m.

Mathematics, My Daddy says is simply a game or a toy for the mind. I enjoy playing with math though I truly know now that it is not Universal Knowledge. Mathematics is like some sports. It brings Me fun and excitement. Sometimes I get low scores and I feel sad, but My Daddy simply tells Me that if I want to perfect the exams, I have to study harder. As you all can see, all the so called greatest mathematicians and scientists and physicists humans' scholars humans gave so much high regards to have immediately realized that all those books and all those studies and all those "humans once thought of as knowledge" became child's play if not garbage right upon My Daddy revealed this Universal Truth and Knowledge. Literally speaking, humans are among the most primitive civilizations in The Universe and yet we humans are very arrogant, sinful and blasphemous because we, humans do not know any better.

The numbers below show and reveal the absolute humans' ignorance of The Universe: here on earth, humans' system of #counting #interpreting Time is by almost literally "counting" the tiks and the toks of our grandma's clocks:

a #millisecond timer counts from 0 to 1000 in 1 second.
a #nanosecond timer counts from 0 to 1000000 in 1 second.
a #picosecond timer counts from 0 to 1000000000 in 1 second

Humans' degrees of comprehension can only barely grasp what a picosecond is. This is the very reason why humans have so much avoided putting mass(m) on Time(t) because if that were so, and truly IT IS, mathematics would be useless as an old garbage program or application. So they humans began fooling themselves falsely thinking that they humans have been acquiring knowledge while truly what they have been acquiring and feeding their minds with are to the letter, garbage. THE UNIVERSE deals with Time as events, and with it, mass, energy, velocity, speed, and acceleration and everything. Each one, IS unique.

NVMEsecond is 1 second divided by 1 x 10 raised to the exponent 666.
NVMElightyear is 1 Lightyear multiplied by 1 x 10 raised to the exponent 666.

NVMEparticles are subsubatomic particles with lives half-lives ranging within trillionth of a trillionth of a trillionth...... of a trillionth of a NVMEsecond. They interconnect each and everything in The Universe. The Universal Internet. These particles are seemingly like "very tiny bubbles" connected to each and everything. Serving as Time Timers Transmission Mediums, these particles burst (in series) into tinier smaller particles. A Universal Timer Counter that can count 9999999999999999999 x 1 x 10 raised to the exponent 99999999999999999 within very small fraction of a NVMEsecond. Signals or information from 9999999999999999999999999 billion different star systems from 9999999999999999999999999 billion different super clusters 9999999999999999999999999 NVMElightyears apart are being transceived to and fro within small fractions of NVMEsecond.

How does someone describe, something - that we haven't developed a language for, so that we CAN describe it.
===
We start with 27 dimensions - of creation.
Outside creation we have some dimensions … that are born (not created).
These dimensions … contain .. what is needed - for the created dimensions (so that they can exist).
===
In the these dimensions ... every particle is … omnipresent (Read: infinity speed).
This .. is not: x=(a number) .. but .. f(x,l)=a result (that contains many different things). Among them - time (both movement and dimensions).
It also contains :
- The ability for life.
- The ability to create.
- The ability for "producing energy" (The emptiness between the rings).
(The energy is not produced, in the manner we use it, in "the daily
language", but as a result of two waves - "gathering mass", so that they can
become a wave.
"The Vacuum" between the waves - "becomes energy"
#####
[Read the beginning again: I said that we didn't have developed a language for this, yet.]
#####
- f(x,l) means here: function of (x=mass) and (l=liquid).
So … a "function of mass, liquid" - is OUR beginning .. LEADING to - the understanding
of the foundation … for creation.
...Then we can see:
-- Every star (included our sun), "plays" - "its own melody".
.....As long as the melody … is unchanged ... the star is "healthy".
.....When the melody changes - the star, starts "to die".
.....Through the understanding of string theory - this melody can be "repaired", so
........string theory may be a kind of "medical science" - in THIS context.
===
This is a simplified version, of a description - of what string theory might be.
The function … contains many more elements than mentioned here.
The main point, with this simplified explanation - is to show the possibility
for that we must look at string theory - in perception wider than
"x=(a number)".

NB: Amongst other things, I didn't appreciate how he glossed over the Kaluza-Klein theory; how it tied in with Einstein &; String-theory. Kaluza & Klein formulated GR in 5 dimensions & Electromagnetism, Maxwell’s equations simply fall out of the theory. This was the tie to String Theory which also encompasses both theories as Maxwell’s equations have already been unified with the rest minus GR in the standard model. ( )
  antao | Oct 18, 2018 |
Good but not gripping. Sometimes the analogies were not all that helpful and seemed to take a lot of time for little explanatory power, but on the whole still plenty to learn from listening to the book. ( )
  TravbudJ | Sep 15, 2018 |
Complessivamente è un buon libro di divulgazione,che si occupa di teoria delle stringhe in maniera comprensibile,lasciando alle note alcune considerazioni più matematiche.Fa emergere anche la passione dei fisici teorici che si cimentano in questa branca della fisica.Manca di obiettività,essendo stato scritto da un fisico che si occupa di teoria delle stringhe e non presenta un punto di vista oggettivo sulla mancanza di evidenze sperimentali,ad esempio.Lettura consigliata. ( )
  AlessandraEtFabio | Dec 22, 2017 |
At long last I have finished this book. It took me a long time to read it, not because I didn't find it interesting, but because I needed to have periods of uninterrupted time to read and absorb the information. Uninterrupted time seemed to be at a premium this spring.

However, having read it, I believe I can say I understand string theory a little bit whereas, before I read it, I had barely even heard of string theory. Dr. Greene's illustrations and examples helped a lot to make a rather arcane subject comprehensible. One example, though, really jarred me. On page 264 he is talking about wormholes and uses the idea of a bridge between the World Trade Centre Towers to illustrate the concept. Of course, this was written before 9/11 but it occurred to me that the terrorists really chose their target well when it is used even in a scientific text to illustrate something of massive size.

Dr. Greene is obviously that rarest of scientists i.e. someone who can explain their specialty in terms a novice can easily understand.

Having said all this, a part of me still wonders if string theory isn't some giant hoax foisted on us by physicists who sit around and laugh uproariously at how gullible we are. I work in biochemistry research and I'm used to not seeing the particles I work with (enzymes) but at least we can perform experiments which show reactions in the presence of and in the absence of the particles and thereby demonstrate that there is a difference. String theorists seem mostly to manipulate equations and then say they prove what they set out to prove. It's a little too esoteric for my liking. I'll stick to biochemistry. ( )
  gypsysmom | Aug 25, 2017 |
Brian Greene has a knack for image and metaphor, which makes his explanations of superstring theory and symmetry (not the same as what we learned in Geometry class in 10th grade) almost deceptively comprehensible. An enjoyable read (that I admittedly have yet to finish) it provides a comprehensive view of the state of string theory as it existed 7 years ago. There are major books out there right now that question the viability of string theory, so if you're looking for the *most* up-to-date information on what's been going on in physics, this is not the book to read. But it is a *great* place to start for the armchair physicist who wants to learn the definitions of the Strong Force, the Weak Force, and Electromagnetism, among other things. It's descriptions of mass and space will stretch the limits of your imagination... and in general, if you *can* imagine the things that Greene describes, chances are, you're a genius who can see in more than three dimensions. Lucky you! ( )
  voncookie | Jun 30, 2016 |
Brian Greene has a knack for image and metaphor, which makes his explanations of superstring theory and symmetry (not the same as what we learned in Geometry class in 10th grade) almost deceptively comprehensible. An enjoyable read (that I admittedly have yet to finish) it provides a comprehensive view of the state of string theory as it existed 7 years ago. There are major books out there right now that question the viability of string theory, so if you're looking for the *most* up-to-date information on what's been going on in physics, this is not the book to read. But it is a *great* place to start for the armchair physicist who wants to learn the definitions of the Strong Force, the Weak Force, and Electromagnetism, among other things. It's descriptions of mass and space will stretch the limits of your imagination... and in general, if you *can* imagine the things that Greene describes, chances are, you're a genius who can see in more than three dimensions. Lucky you! ( )
  anna_hiller | Jun 22, 2016 |
The only reason I give this 3 stars instead of 4 is because the description of relativity and QM in this is worse than in his 'Fabric of the Cosmos', and I'm not sure why they're included at all when they are already in the other book... ( )
  AlienIndie | May 20, 2016 |
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2 editions of this book were published by W.W. Norton.

Editions: 0393058581, 039333810X

 

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