July 18, 2007
Turok on Edge
Neil Turok writes about cosmology and The Cyclic Universe
on John Brockman's Edge.Org
In recent years, the search for the fundamental laws of nature has forced us to think about the Big Bang much more deeply. According to our best theories — string theory and M theory — all of the details of the laws of physics are actually determined by the structure of the universe; specifically, by the arrangement of tiny, curled-up extra dimensions of space. This is a very beautiful picture: particle physics itself is now just another aspect of cosmology. But if you want to understand why the extra dimensions are arranged as they are, you have to understand the Big Bang because that's where everything came from.
Turok rejects the Anthropic principle and questions the "landscape" of possible universes that String Theory predicts. He goes on to give Dark Energy a central role in triggering the next Big Bang, but I am confused about how. On one hand he says "it is the decay of dark energy which leads to the next Big Bang" but "the dark energy itself causes these two membranes to attract".
Previously: Word for the Day: Ekpyrotic.
Posted by spot at 11:38 AM
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July 17, 2007
Posted by spot at 11:34 PM
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After 18 months of gestation, my friend Thomas Williams has released an
amazing abstract music-video Durian
which synchronizes custom animated Fractal Flames
with 3D geometry and the music of Steve Nalepa
Posted by spot at 05:08 PM
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GPU Fractal Flames
RapidMind has implemented the Fractal Flame
renderer (from the Electric Sheep
) with their parallel language. The result
renders 1280x720 at 10 frames per second on a GeForce 8800 vs 0.16 fps on a 7600 Duo (speedup of 60x). I can't tell if their implementation includes Density Estimation. I hope they have a setup at Siggraph, I would love to play with it.
Previously: GPUFlame by Simon Green.
Posted by spot at 01:29 PM
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July 11, 2007
Pix on Ubuntu
I haven't been taking many pictures lately but irresistible moments turn up now and then... Worse I was procrastinating the task of copying the photos from camera to computer and selecting and correcting them because I hadn't yet done this with Ubuntu Linux and I wasn't sure it would work. Before I had always used Photoshop under Windows, but that was no longer possible
. Eventually the flash chip filled up (in the middle of the fireworks on Independence Day of course). I am happy to report the process went flawlessly.
I plugged in the camera with USB (before I had used the SD slot on my laptop, but it has a proprietary interface) and a window popped up asking if I wanted to import. I said yes and several minutes later (USB is slower than SD) all the photos had been copied to a directory and rotated according to the exif tags. Super! I tried using F-Spot to select and correct, but it wants to import stuff into its database rather than just operating on files. And its color correction controls are lame. Gthumb is a great browser, but it doesn't have the capability to copy images between folders. Fortunately the gnome file browser is up to the task. And then to crop and correct I used the Gimp, which has a clunky interface compared to Photoshop, but it got the job done. See the results for yourself.
Posted by spot at 11:43 AM
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July 04, 2007
Word for the Day: Ekpyrotic
Ekpyrotic comes from ekpyrosis
, greek for conflagration
represented the all-engulfing cosmic fire, the contractive phase of
eternally-recurring destruction and re-creation. These days it's an
Austrian metal band
Oh and the Ekpyrotic
Universe is a alternative cosmology to Inflationary
Theory, which has been the consensus since the early 90s when it
was discovered to predict the fluctuations in the cosmic background
radiation and the large scale structure of the universe. The idea is
that quantum fluctuations near the beginning of time inflate and
become seeds for galaxies.
The problem is that inflation is just patched on to the standard model
of quantum+gravity that runs the world we see here and now. And
then in the late 90s dark energy had to be thrown in to cover the
accelerating expansion seen by measuring the redshift of
So physicists have been searching for models that predict the
fluctuations and the accelerated expansion rather than suffering them
as patches. The Ekpyrotic Universe has been one such option, based on
the idea from String Theory that the Big Bang is the collision between
branes in a higher
dimensional space. In the Cyclic version of this theory these
intersections, and hence universes like ours, recur at trillion year
But these theories suffered from their own mathematical complications
of too many dimensions and singularities. These problems have reportedly
been solved in the past couple of months. How can these theories
be distinguished? By measuring gravitational
Fascinating. The implications are enourmous.
Posted by spot at 01:00 PM
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