spot blog

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.

Orb Festival

Durian

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.

previously: Beginningless.

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.

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.

Word for the Day: Ekpyrotic

Ekpyrotic comes from ekpyrosis, greek for conflagration. In Stoic philosphy it 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 supernovas.

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 intervals.

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 waves.

Fascinating. The implications are enourmous.