Un libro sólo para especialistas. Repito, sólo para quienes tengan conocimientos de las matemáticas de la relatividad general y los fundamentos de la mecánica cuántica. No hace falta ser experto en gravedad cuántica para seguir las argumentaciones, ni mucho menos. De hecho, cuando Hawking habla para otros físicos es un divulgador de primera, capaz de presentar temas abstrusos de un modo claro y conciso, todo lo contrario que hace en sus nefastos libros de divulgación popular. Y Penrose saca mucho partido a la notación de brakets, por ejemplo. Pero es imprescindible tener conocimientos al nivel de licenciatura de relatividad general y cuántica.

En su campo, un clásico imprescindible.

Un libro que te enseña algo más que solo MC o RG te enseña pensar como haría un científico desde 0 gran lectura que incita a desarrollarte aún más y más y da alas a la bestia de tu curiosidad

This book was recommended to me by a good friend a while back, who insisted I purchase my own copy because he couldn't stand to part - even temporarily - with his. So I did. Maybe a month later, co-author Sir Roger Penrose spoke at a local university and I was fortunate enough to see him, as well as have my very untouched copy of The Nature of Space and Time signed by him. Only recently did I read it, and I'd be lying if I said I could comprehend more than half on my own.
Reading this book, more a collection of expository scientific essays than anything else, worked itself out into a research project for me; every chapter was organized by subtopics or sub-processes that required a considerable deal of Wikipedia look-ups on my end to keep up with the content (which, by the way, must, must, must be read in order). The back-and-forthness of it, however, did pay off in the end in that if someone asked me, "What the hell is 'spacetime' anyway?" I could explain to them (though not nearly as eloquently as Hawking or Penrose--it's a start, right?) the relationship between theoretical "space," physical space and the effect that they have on time and its perception. The Nature of Space and Time sparked in my interest in reading more on theoretical physics, and I'd quickly recommend the book to anyone with a shared interest who 1) has a PhD or 2) doesn't mind three hours plus of research per fifty lines of text.

And all those mathematical equations and terms like Lagrangian and Eulers numbers which I learned in calculus back in undergrad emerged. A very technical read - I skimmed through most of it and highlighted the 'absorbable parts'. More Stephen Hawking in the future for me!

Vent'anni fa Stephen Hawking e Roger Penrose hanno tenuto una serie di conferenze per raccontare come loro pensavano si potessero mettere insieme la teoria della relatività generale e la teoria quantistica dei campi. Non che ci si sia riusciti nemmeno ora a farlo, intendiamoci. Ad ogni modo questo libro raccoglie il testo di queste lezioni. Ve lo dico subito: se non avete studiato fisica a livello universitario non ci capirete molto, o almeno io non sono riuscito a cavarci molto, anche perché la versione epub che ho letto (e che tanto per dire ha un ISBN errato nel colophon...) ha perso dei caratteri una volta letta con Aldiko che è tra i pochi programmi che permettono di leggere un file protetto da DRM; una versione pdf sarebbe stata migliore. Penrose si fa capire un po' di più, Hawking è davvero tosto. Stranamente in un paio di punti mi è parso che Libero Sosio si sia perso: solo che non sono riuscito a copiarmi il testo, sempre per colpa del DRM :-(

Interesting book, but way above my head. It should come with a warning that you need a PhD in physics to read it. I understood only a small fraction of it. I recommend A Brief History of Time for an approachable Stephen Hawking book.

Couldn't follow it. Much physics and prior theory is required. Didn't make it through even half of the book.

Non posso valutare un libro di cui ho capito davvero pochissimo. A netto del fatto che si tratta del risultato di un dibattito risalente al 1994 e che, pertanto, potrebbe essere in alcuni punti obsoleto, il libro (come peraltro dichiarato in Premessa) richiede una conoscenza tecnica della teoria della relatività generale della teoria quantistica. Che io non ho. Insomma, non è un libro divulgativo. Per nulla.

Up front: this book is not for everyone. I’m actually not certain it was for me. I haven’t really studied physics since the courses I took in the early 1990s in university. This was originally written a few years later, but assumes more than merely a rough knowledge of Relativity and Quantum mechanics – you actually need something more than just a basic introduction to really grasp what’s going on here.
But, armed with the internet, I persevered, more or less.
The science may be a bit dated, but since the book is 20 years old, that shouldn’t be too surprising. It’s also hard to tell without more physics, and more recent physics, than I have.
As a result, this is going to be a rather shorter review than I often write.
Hawking and Penrose are having a friendly conflict about the nature and structure of the universe. This is not a book for generalists or people with a passing interest in relativity and quantum mechanics. While the authors assume you have a basic familiarity with the relevant mathematics and quantum mechanics, I might suggest that basic familiarity is more along the lines of post-graduate.
Overall rating: 3 stars, but I should probably actually go with 2. What I understood was interesting, but what I understood wasn’t enough of the book. This isn’t a popular science book. Penrose and Hawking are talking much closer to the level the operate at. If you’re close to that level, the book is probably a lot more enjoyable.

"Time is the fire in which we burn." Delmore Schwartz

"...time is a companion who goes with us on the journey and reminds us to cherish every moment, because it will never come again." Jean-Luc Picard

I found the information in this set of 3 lectures to be somewhat interesting but because I am not a student (or practitioner) of science I found it to be a bit too specific to the field of physics/quantum mechanics/advanced maths/etc. for my general interest.

That said, one big problem I have with this is that he mentions god several times, and given there is no proof of god, why is he continually referring to a scientific "nothing" in his lectures? Even though I am not a scientist, the fact he mentions god tells me his science is not completely rooted in reality but rather at least in some part is rooted in mythology, and that tells me he lives in a world in which I do not live.

E' difficile definire questo libro un libro di divulgazione. In realt� si tratta di una serie di lezioni (tre a testa pi� una discussione finale) in cui gli autori dimostrano le proprie teorie in merito alla natura dello spaziotempo attraverso lo studio delle singolarit� nell'ambito della meccanica quantistica e della relativit� generale. Per farlo fanno ampio uso di strumenti matematici molto complessi. Per comprendere appieno le dimostrazioni � necessaria una conoscenza specialistica di matematica e fisica (non basta qualche corso di analisi, geometria e fisica generale). Nonostante ci� il libro rimane comunque godibile anche ai non addetti ai lavori, a patto per� di accontentarsi di cogliere solo le idee e i concetti generali.

Hawking promised that his and Penrose's lectures and debate would be technical, and he delivered on that promise. I liked the book because it's always entertaining to read two great minds bicker a little bit, and I did learn some information about black and white holes, singularities, and the origins of the universe, but I didn't understand most of the book. The jargon is real. There are tons of equations I couldn't possibly understand. What I did appreciate, though, is that Hawking summarized his lectures at the end, and Hawking was a master at making complex ideas seem simple for people like me.
In the debate, I couldn't tell you who won. Penrose seems to say that Hawking wins by comparing their debate to one between Einstein and Bohr, one that people at the time claimed Bohr won. Penrose says he's like Einstein in this debate and Hawking like Bohr, which seems to indicate he felt Hawking won.
Overall, the book is short and a quick read if you're not really trying to understand everything in it. If you want to do that and really make a study of it, you could. But if you just want to get a little out of it and be entertained and challenged, this could work for you too. It helped me, during an off month from work, to keep my brain in motion, at least.