Monday, June 04, 2007

Big -- Mandelbrot Universe

Watch this fractal unfolding, and listen to it too. (It reminds me a bit of scenes near the end of 2001 A Space Odyssey.)
A Mandelbrot the size of the known universe
"An extremely deep dive into the Mandelbrot zoom. If the final frame were the size of your screen, the full set would be larger than the known universe."

There are more Mandelbrot/fractal animations on the same YouTube page. If you want to get a rigid mathematical explanation of Mandelbrot's accomplishments , be sure to listen to the following one as it unfolds:
Mandelbrot Set Zoom

Sunday, May 13, 2007

Is the Universe Finite, or Not?

I've just come across a few interesting items in my quest to understand "life and the universe" and would like to share them with you:
  • On A Finite Universe With No Beginning Or End (a PDF document) - by Peter Lynds of New Zealand, with the following abstract:

    "Based on the conjecture that rather than the second law of thermodynamics inevitably be breached as matter approaches a big crunch or a black hole singularity, the order of events should reverse, a model of the universe that resolves a number of longstanding problems and paradoxes in cosmology is presented. A universe that has no beginning (and no need for one), no ending, but yet is finite, is without singularities, precludes time travel, in which events are neither determined by initial or final conditions, and problems such as why the universe has a low entropy past, or conditions at the big bang appear to be so "special," require no causal explanation, is the result. This model also has some profound philosophical implications."
    If the above paper is too much for you, then from Science a Go Go there's a pair of articles that might make it more digestible: The Universe As Magic Roundabout: Part I plus The Universe As Magic Roundabout: Part II

    Here's an earlier paper by Peter Lynds (also a PDF document):
    Time and Classical and Quantum Mechanics: Indeterminacy vs. Discontinuity

  • For another view, this time about multiple universes, there's Towards observable signatures of other bubble universes (another PDF document) with the following abstract:

    "We evaluate the possibility of observable effects arising from collisions between vacuum bubbles in a universe undergoing false-vacuum eternal inflation. Contrary to conventional wisdom, “typical” observers inside a bubble should have access to a large number of collision events. We calculate the expected number and angular size distribution of such collisions on an observer’s “sky”, finding that for typical observers the distribution is anisotropic and includes many bubbles, each of which will affect the majority of the observer’s sky. After a qualitative discussion of the physics involved in collisions between arbitrary bubbles, we evaluate the implications of our results, and outline possible observable effects. In an optimistic sense, then, the present paper constitutes a first step in an assessment of the effects of other bubble universes on the cosmic microwave background and other observables."

Wednesday, March 07, 2007

How big is BIG?

This morning I was looking at the Web site of the Sloan Digital Sky Survey

Fascinating stuff! SDSS is systematically mapping the entire sky, determining the positions, brightnesses and distances of celestial objects, to give a three-dimensional picture of the universe through a volume one hundred times larger than that explored to date.

They are obviously asking some basic questions. And getting answers, too. one question that really tickles my fancy is described in the article How big is big? Probing the conditions of the universe on the largest scales

Back in May 2006 researchers at SDSS announced the first measurements of galactic structures more than a billion light years across. Now that's getting to be sizable, isn't it!

Thursday, February 01, 2007

Dark energy - the pressure exerted by empty space!

I would never have thought it, and even after reading it cannot begin to properly understand or appreciate this:
... dark energy is the pressure exerted by empty space. From a quantum mechanical perspective, empty space is unstable. According to statistics, photons and subatomic particles pop into the vacuum of space in a way that shows that "empty" is only an approximation: Space actually comprises a statistical soup of particles and antiparticles that are in a constant state of creation. Today scientists can demonstrate this by pumping the gases out of any empty chamber. After every atom has been pumped out, particles begin to percolate into existence in a process called vacuum fluctuation. ...

... unless the vacuum itself exerts the negative pressure observed, then the universe must otherwise be composed of as much as 70 percent dark energy.

Read more in the following Dr Dobb's article: Quantum Mechanical Theory Behind 'Dark Energy'?

Tuesday, January 16, 2007

How Wide is the Universe? - revisited

Way back in November 2005 I asked How Wide is the Universe? and have been pondering it every now and again since then.

Reading Bill Bryson's tour de force "A Short History of Nearly Everything" gave me some additional insights (see the early chapters).

And a few days ago I came across this link at Yahoo! Canada and the following article at which I found especially informative on this matter:

Universe Measured: We're 156 Billion Light-years Wide!
If you've ever wondered how big the universe is, you're not alone. Astronomers have long pondered this, too, and they've had a hard time figuring it out. Now an estimate has been made, and its a whopper. The universe is at least 156 billion light-years wide.
In particular, it neatly outlines one aspect that beforehand I simply couldn't get me head around: why, if the universe is some 13 or 14 billion years old, its diameter in light years can be numerically greater than this. And it turns out that the above figure -- converted, of course, into distance in Light Year units -- cannot simplistically be regarded as the radius which, by being doubled, would lead to a diameter of 27 or 28 billion light years. And the key to this is explained thus:
... the universe has been expanding ever since the beginning of time, when theorists believe it all sprang forth from an infinitely dense point in a Big Bang.

"All the distance covered by the light in the early universe gets increased by the expansion of the universe," explains Neil Cornish, an astrophysicist at Montana State University. "Think of it like compound interest."