
Dichronauts - sohkamyung
http://www.gregegan.net/DICHRONAUTS/DICHRONAUTS.html
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rspeer
I recently read Greg Egan's previous trilogy set in an alternate-physics
universe, the _Orthogonal_ trilogy, and it was excellent. (In _Orthogonal_ ,
time is a space-like dimension, and relativity, optics, and chemistry change
accordingly.)

Not only does Egan invent weird universes and let the reader follow the math
involved to whatever extent they want, he also tells great stories in the
universes he invents.

 _Orthogonal_ tells of a society's quest through deep space, searching for a
way to survive and save their home planet, using technology they have to
invent along the way. (The characters can speak in diagrams, with which they
explain the science to each other and to the reader.) It builds up to include
some plot twists that are only made possible by the strange nature of time and
space.

 _Dichronauts_ seems to be an iteration on this formula (now there are two
time-like dimensions), which sounds more bewildering and constraining to the
plot, but I trust Egan to do it well.

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wyager
Exciting! Egan is one of my favorite authors; he has an incredible
imagination, and is one of few sci-fi authors who often puts an extensive list
of citations in at the end of his books. No doubt the physics in this book are
very carefully thought out. Looks like there are descriptions of the
alternative spacetime he's using at the bottom of the page, so I'll have to
give those a read!

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teraflop
Neat. I noticed that the summary for this popped up on Egan's site a few
months back, but there wasn't nearly enough detail for me to wrap my head
around the premise. Gonna take another look at it now.

For anyone who finds this interesting, you might want to check out Christopher
Priest's _Inverted World_ , which is based on a vaguely similar premise.
(Although much more closely tied to the "real world", and not nearly as
mathematically rigorous.)

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teraflop
Just posting a follow-up comment to say that the interactive simulation is
really the highlight of this set of pages. I was expecting a trivial demo
widget, along the lines of the animated GIFs in the article, but it's actually
a full 3D rigid-body simulation.

Playing around with blocks and ramps in a browser does a great job of taking
the mathematical analysis given in the article, and making it at least
somewhat intuitively understandable. But on the other hand, it doesn't exactly
make a convincing case that a world built according to these rules could ever
be stable!

[http://gregegan.customer.netspace.net.au/DICHRONAUTS/02/Inte...](http://gregegan.customer.netspace.net.au/DICHRONAUTS/02/Interactive.html)

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mrkgnao
I've just come here to say that I came here after literally finishing
_Permutation City_ around two hours back. It was great.

I can't wait to try Schild's Ladder -- differential geometry, yay!

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twic
Is it 'Into Darkness' that has the idea of a space where you can only move
forwards, not sideways? This sounds like that mixed with the rigorous
alternative physics of the Clockwork Rocket series.

That is, it sounds fun, for quite difficult values of fun.

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pmoriarty
I've always been really disappointed in Egan's work. He's been praised to the
stars, so my expectations were kind of high. But when I actually read his
work, I found it to be pretty shallow and dry, with cardboard characters, like
much hard scifi. He kind of reminds me of Vernor Vinge, for whom I'd also had
high hopes, as both authors deal with the singularity a lot -- an idea I
really find compelling. Unfortunately, I find their execution to be pretty
weak, and even their ideas are mediocre.

~~~
TeMPOraL
> _with cardboard characters, like much hard scifi_

I think a lot of sci-fi fans (myself included) don't pay much attention to
that because, well, it's not why we read sci-fi. People are boring. Cool
science and weird technologies and interplanetary-scale politics are fun. For
every story you'd like to tell to make a character "deep", there's a _whole
genre_ dealing with it in real-world settings already. Troubled teenagers?
Sure, there's a section on Amazon just for that. People in love? Every other
book is about this. Etc.

Just my 2¢.

~~~
eropple
I dunno, man. SF exists as a lens to say something about people. The whiz-bang
technology is...I want to say "wank", but I don't mean it pejoratively. That
stuff just doesn't _mean_ much. I have great admiration for folks like Robert
Forward as _people_ , but...once you take away the technology, they're not
saying much. It's potboiler stuff. And that's fine, but I look at that, and
then I look at somebody like Spider Robinson, whose inclusion in _Analog_ got
Ben Bova no end of shitty emails, and...he's actually sayin' stuff. Like, you
don't have to agree with it, but there's something, once you put the book
down, that you can take away.

I don't care how hard your SF is: it is always and without exception about
what technology does _to people_ \--otherwise it's an engineering manual for
something that doesn't exist. A lot of the "greats" of hard SF never got that.
(Forward, again, comes to mind.) I have a more charitable opinion of Egan than
the OP does, to be sure, but I have a _strong_ reaction to the notion that the
human element of this should ever, ever be played down. Everything,
ultimately, is about people. We miss that at our peril.

This is why most of Heinlein (the tail end of his career notwithstanding--we
all know it gets weird, let it lie) still holds up so well despite so much of
technology and society having changed in the interim. Even books that weren't
trying to be hard SF (his juveniles, which IMO are some of his weakest books,
tended towards this) had engineering and mathematical verisimilitude, but it
was a concern set well behind the characters who had _stuff to do and learn
and grow through_. (Most of the time. Lookin' at you, _Red Planet_.)

~~~
wyager
> The whiz-bang technology is wank

Egan is good because nothing in his books is "whiz-bang". He's not writing
about turboencabulators or laser guns; he's writing about worlds in which
nature itself is fundamentally different, and in a much more fulfilling way
than you would find in a fantasy book (because you know Egan's worlds are at
least as mathematically viable as our own).

I disagree that SF exists to say something about people. Authors like Egan use
it to say something about the universe itself, which is a much more vast and
beautiful topic than the everyday goings-on of humans. Perhaps your focus is
too anthropocentric to enjoy it.

