20 September 2008

Astronomy/cosmology is often mind-boggling...

...which I suppose is inevitable in the sense that our brains are not designed to deal with conceptions of infinity. Consider this report of a gamma-ray burst that occurred 12.8 billion years ago and whose gamma rays are just now reaching earth:
The new record holder, called GRB 080913, was first detected on 13 September by NASA's Swift space observatory. Telescopes around the world soon detected its afterglow at longer wavelengths, and the light spectrum they observed revealed its incredible distance: 12.8 billion light years away.

GRB 080913 exploded less than 825 million years after the big bang. "This burst accompanies the death of a star from one of the universe's early generations," said Swift team member Patricia Schady of University College London.
So, the Big Bang occurs, and the material that will later condense to form the earth starts shooting away from the epicenter. "Shortly afterwards" (825 million years later), this star has formed and explodes, sending a burst of gamma rays toward us (or towards whereever we will be when we eventually exist) at the speed of light. Travelling at the speed of light, those gamma rays reach us now (12.8 billion years later) because we have been slowing down, and they are just now catching up to us.

It's hard to wrap one's mind around such concepts. It's so much easier, I guess, to think in terms of just 6000 years, although to my mind the immense scenario is more awesome and more fitting for a God than the latter...

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