It's been a couple of years since I last read one of Egan's books - I thought I could handle it; I thought I'd kept reasonably up to date with scientific developments (as up to date as a Humanities graduate could decently expect to be). But, of course, while I've been browsing through the odd New Scientist or reading a couple of recommended 'Pop Science' books from Amazon, Egan has been meeting proper scientists for chats about how their latest work is going, searching out obscure (well, obscure to everyone I've ever met) papers on the web, and generally thinking about things far removed from, say, whether the difference between Fosters and Stella Artois really justifies the latter's high price.
You need to be wide-awake and stone cold sober when you start reading Schild's Ladder.
That all said, Schild's Ladder has the most marvellously Pulp premise at its heart: a scientific experiment gone perilously awry that has sent a tremendous sphere of unstoppable annihilatory force ripping across the galaxy at half the speed of light! This being an Egan novel rather than an E.E. 'Doc' Smith one, 250 years later we find the colonies in its path being calmly evacuated as the scattered clades of humanity devote their considerable intellect and technological prowess to studying and understanding the swelling sphere of 'novo-vacuum'. The main problem for the group on the research ship 'Rindler', however, is whether or not the novo-vacuum should be destroyed immediately the means to do so exists, or whether they should try and live with(in) it. Humanity, it seems, may well have come a long way in 20,000 years, but not so far that we can't still recognise something of ourselves in our descendants.
It's fairly easy to guess which side Egan sympathises with, but this conflict between the factions adds a very human dimension to Schild's Ladder, one very necessary if we're not to be swallowed up entirely by the mathematics and physics therein. His characters might not be masterpieces of emotive characterisation but they're colourful enough and sufficiently well-presented to carry the story along. You can believe in them and understand why they talk the way they talk about what they talk about.
There's actually very little physical description of the characters in Schild's Ladder; although conversations often sound like ordinary face-to-face human conversations more often than not they're anything but - something you'd think would serve either to alienate us from them or make the details of their specific modes of communication seem like frivolous narrative add-ons. Egan manages to convey a complex mix of humanity and difference with his characters, however, such that 'old-fashioned' (23rd century) humans, when they appear, seem repellently alien to us, not the super-enhanced, hyper-mediated, acorporeal beings that constitute humanity in 22,000AD.
No one, but no one, writes sf like this, that so consistently makes you blink helplessly at a page you've just read for the fourth time and are still no nearer to grasping. I had to skim entire paragraphs of expository dialogue rife with lines like: 'Everyone knows that it's an axiom of quantum mechanics that you can form superpositions of any two state vectors: if V and W are possible physical states, then so is aV + bW, for any complex numbers a and b whose squared magnitudes sum to one.' (page 90)">
That said, I really enjoyed Schild's Ladder. If you can't 'get' all the science behind it then you should get enough to be astonished, as usual, by Egan's ferocious learning and rigorous application of it to reality.
Egan often seems to be writing in both a different language and different genre to anyone else out there in his merciless use of multiple scientific disciplines; his application of cutting edge theory is unlike anything else I'm aware of. Even now, after Egan has been consistently putting out astounding books for over a decade, he doesn't seem to have any competition.
Certainly I think Egan is writing some of the most 'honest' sf there has ever been, refusing to pull his punches for the sake of a comfortable narrative or so as to pander to our hopelessly inadequate Star Trek visions of what the future will be like.
Of course, other sf writers publish books that employ some fairly heavy science, but I'm not aware of anyone else who so blatantly refuses, as I said, to pull any punches in the name of 'storytelling' as Egan does. I'm not surprised at this, given the level of research, knowledge and application that an Egan work demands, and I know I wouldn't want to read nothing but Egan (it's too close to the razor's edge of comprehensibility to be a truly comfortable read), but Schild's Ladder is a noble vision of our future, for all the human faults displayed within, and you won't regret spending a little bit longer than usual reading it (and if anyone can explain 'quantum graphs' to me I would be grateful!)