Schild’s Ladder

Unique story of what another creation, another universe, might be like. On another level, it deals with what humanity will be like after transcendence to a post human state. Greg Egan suggests we will be as divisive and polarized as ever, even deceitful, yet also much more humane and compassionate. Oddly enough, our future descendents will be prone to predjudice​, at least when it comes to the decaying flesh sacks that ordinary or previous humans used to be. These cultural assumptions come back to haunt the ascended, who indeed treat alien microbes with more tespect than their unevolved progenitors. This story is like a mixture of Robert Heinlein on extrapolated societies with Rudy Rucker in higher dimensions. Yes, this is definitely hard science fiction. If you find it hard to accept extrapolations from known physics as an acceptable basis for a plot, maybe this kind of adventure is too much to accept. If you like to speculate, then you will enjoy this ride immensely and have no trouble being able to identify with the characters. This is a good story. Keep it!

Warning, Spoilers...What a thrilling books... up until the ending. It needed about 3 more chapters after the boarder entry to engender a more deserved climax and appropriate resolution. All the buildup explicating complex mysteries that surely exist beyond the surface of the novovacuum - a place with completely different physics than our own universe. Yet here is the ending Egan painted for me: In an escape from the Langoliers the party met a group of garden gnomes that marched them to a rock that contained a pivotal character; they promptly freed this person, didnt really figure out who was communicating at the surface, had a quickie, and left. The end.

This book is great, if you like physics and science fiction, you really can't go wrong here. It's a cerebral, but emotional dive into a concept that doesn't get much time in fiction (I won't go further for fear of spoilers) and I found the imagery compelling. As always with Greg Egan, the science is exciting and thought-provoking.I originally got into this author through one of his short stories, 'The Planck Dive', which was a great read. After that I just snagged all of his book here on Amazon, and I haven't regretted it. If the phrase, "Hard Sci-Fi" makes you smile, what are you waiting for? Buy this book.

I am giving this 5 stars conditionally...this book is for deep thinking science people only. This is not Star Wars or even Dune. To really get it all you're probably going to need to be a physics professional of some kind. I am a layman who is really into this stuff (watch the shows, read the media) and I only understood about 70% or 80% of what was going on. This book is about the science...the character stories are mildly interesting but the characters are not deep...they are mostly used as a platform to explain life in the future. I did not find myself caring about the characters that much.That being said, it was a great book. Lots of mind-melting stuff. The centerpiece of the story is a vacuum metastability event that was triggered unintentionally. But a lot of the book is about describing life in the far future (think 20,000 years+). Human sexuality and identity has become almost alien. People can casually backup copies of their consciousness at will and re-organize their physical bodies on a whim (so everyone is more or less immortal...I think this is a big part of why I didn't care about the characters).If you feel you are pretty familiar with physics, this book will probably be enjoyable, as it explores a lot of stuff you will not find in other science fiction.

Third Egan book for me, and the least enjoyable. Egan loves his science, and so do I, therefore I don't mind an intelligent sci fi book with firm scientific foundations. I like to have my imagination challenged when the effort is worth it. The book has an interesting premise: a future humanity discovered that spacetime is something akin to loop quantum gravity, a geometrical abstract representation. Change the geometry and you change the physics. And these future humans have found a way to tinker with this geometry at the fundamental level. Pretty deep stuff already, not for the scientifically faint of heart. Of course one of these experiments goes horribly wrong. While it was supposed to create a tiny, unstable sub universe with new laws of Physics, it turns out it's not unstable at all, in fact it starts growing, cannibalizing the surrounding "normal" space, eventually swallowing entire planetary systems.Humanity is split into factions, those who want to study the novo-vacuum to stop its growth or even destroy it, and those who think it should be left alone. After all, humans now have encapsulated their consciousness into quantum chips, they can decide to live disembodied as computer simulations, or grow themselves bodies at will, traveling from planet to planet and from body to body as information. In other words, your planet being swallowed by the novo-vacuum isn't such a big deal anymore, so why fret. Even death isn't a problem since your mind is regularly backed up and therefore can be restored if your current body meets an unfortunate end.Eventually a couple of scientists find a quantum trick to inject a copy of themselves into the novo-vacuum, which turns up to be more than they thought. Unfortunately this part reads like an acid trip Kubrick would be proud of, with the author trying to translate abstract mathematical concepts into concrete descriptions, without success. It was impossible for me to care about any of it, I just wanted it to finally end, and by the time it did, I had stopped caring about the whole book. The characters are neither relatable nor likable. It's hard to worry about characters that can't die, and their worries are so alien that it's hard to feel involved in any way. When people exchange mathematical equations as presents, or can model their anatomy in incomprehensible ways depending on the partner they sleep with, how does one relate to them?I appreciate Egan for not dumbing things down to the lowest adolescent common denominator, but things need to stay somewhat interesting. Egan is a fairly prolific author, so I am sure I will find another book of his that keeps me interested.

Greg is an interesting writer, pulling in imaginary physics a step ahead of the physics we know. (Or the physics which are known, which isn't aways the same thing.) It can cause things to become a little dense at times, but for a fan of hard SF those parts can be joyous.The only downside is that the human sides of his stories can be a little unsatisfying - as is the case here. He makes a good go of it, but it feels like there's just something lacking.Apart from that, a great romp with some incredible ideas.

Loved it.

For fans of Loop Quantum Gravity

If you're a big fan of hard SF this might be a book for you. It for sure has all the elements and the philosophical depth one expects. But it is really hard hard hard SF. At times it feels like reading a scientific paper on some weird mathematical concept. Probably some people can take it, but for me, even though I do like hard SF, this was too much. I give it four stars for the idea and depth, but only two for readability.

Schild's Ladder fait partie des romans de Greg Egan qui n'ont pas encore été traduits en Français. Soit que le travail de traduction est complexe, soit qu'aucun éditeur n'a à ce jour pris le risque de publier ce livre, dans les deux cas les réserves sont justifiées.C'est un livre que j'ai adoré, mais que je ne peux pas recommander. Sauf sous conditions. Greg Egan est connu pour écrire des livres de Hard-Science Fiction assez ardus, si bien qu'on aime à écrire qu'il faut au moins un doctorat en science pour le lire. Sauf que dans le cas de Schild's Ladder, cette gentille hyperbole est une méchante litote. Pour appréhender Schild's Ladder, il faut un doctorat en physique, et ne pas avoir ensuite décroché. Il faut connaître la théorie de la gravitation quantique à boucles version Carlo Rovelli et Lee Smolin, il faut savoir ce qu'est la décohérence quantique de Heinz-Dieter Zeh, savoir ce qu'est un vecteur d'état, un espace de Hilbert, la géométrie différentielle et la métrique riemanienne, l'invariance de Lorentz....Et il est impossible de s'en passer car c'est le sujet même du roman. Si vous ne maîtrisez pas ces connaissances, le livre sera insupportable à lire et vous n'arriverez pas au bout des 40 premières pages. Schild's Ladder s'adresse à un lectorat très ciblé et assez restreint. Si vous faites partie de ce lectorat, alors Schild's Ladder est un roman fascinant, un tour de force surprenant et un des ouvrages de Greg Egan les plus poussés.Le roman débute vingt mille ans dans le futur. L'humanité est largement dispersée dans la galaxie, transhumanisée, voire pour certains totalement acorporée, et n'a plus vraiment de contact avec la mort, sauf de manière locale et jamais vraiment définitive. Depuis vingt mille ans, l'état des connaissances en physique n'a pas beaucoup évolué, et toute la compréhension de l’univers repose sur une théorie dite des graphes quantiques (dérivée de la gravitation quantique à boucles). Jusqu'à ce que quelques chercheurs dans un coin isolé de l'espace habité tentent une expérience pour tester les limites de la théorie. (Il s'agit en gros de vérifier qu'il n'existe qu'un vecteur d'état du vide). L'expérience tourne très mal, et déclenche une réaction en chaîne en mettant à jour une superposition d'états quantiques plus stables que le vide. Une immense explosion s'en suit, dont le front se déplace à la moitié de la vitesse de la lumière et engloutit sur son passage étoiles et planètes. Les populations humaines se voient contraintes à l'évacuation forcée des mondes les plus proches. Six cent ans plus tard, une autre équipe de scientifiques s'atèle à comprendre le phénomène en réalisant des expériences en bordure de front pour tenter de comprendre les lois physiques nouvelles. Rapidement, deux factions antagonistes se forment. Les Yielders souhaitent pouvoir étudier le plus possible le phénomène, et le comprendre, voire le maîtriser. Les Preservationists veulent le détruire. D'un côté et de l'autre, Tchicaya et son amour d'enfance Mariama vont s'affronter intellectuellement et scientifiquement. Greg Egan utilise des flash backs pour construire les personnalités et relier les décisions de chacun à des événements passés. Puis, un jour, une expérience lève un peu le voile et révèle que l'autre côté de la frontière est emplie de vie. Le vide n'est que dans notre univers...Tout le génie d'Egan va être d'imager un monde dans lequel les lois physiques sont radicalement différentes, et où plus aucune interprétation classique n'a de sens.Dans Schild's Ladder, l'intrigue avance à travers les discussions entre les différents personnages, ou les séminaires scientifiques à bord de la station. Les actions se résument à des expériences de décohérence quantique à base d'impulsions de particules. Rien que cela détournera sans doute nombres de lecteurs, en plus de la complexité du propos à base de tenseurs de densité et de vecteurs d'états. Comme à l'accoutumé, le style d'Egan est aride et sans effet. Lorsqu'Egan construit une révélation, il lâche l'information cruciale au détour d'une phrase, lorsqu'il estime que vous devez avoir déjà compris le twist par vous même, sans faire de rond de jambe. Il n'y a pas de cliff hanger chez Egan. Et comme d'habitude, la fin est abrupte.En conclusion, c'est un roman fascinant, génial et illisible.