Saturday, March 22, 2008

I'm So Glad The Universe Is So Big

Yesterday, Earth happened to cross a gamma ray burst beam. Had we been within a few thousand light years of the source, all life on Earth would be extinct by now. Everyone we love would have been gone. Life on Earth would have been terminated. It would have been a quick death because the devastation moves toward us at the speed of light--there would not be any advanced warning.

We were so lucky, the source is about 7,500,000,000 light years away, so I am still typing and you are still reading this. (One light year is about 9,460,000,000,000 km.)

The Bad Astronomer Blog has a good write up about this. A particular interesting passage:

"Let me put this in perspective for you. Imagine a one megaton nuclear weapon detonating. That’s roughly 50 times the explosive yield of the bomb dropped on Nagasaki. Devastating.

The Sun, every second of every day of every year, gives off 100 billion times this much energy. That’s every second. A star is a terrifying object.

In the few seconds that a gamma-ray burst lasts, it packs a million million million times that much energy into its beams. In other words, for those few ticks of a clock the GRB is sending out more energy than the Sun will in its entire lifetime.

There is, quite simply, no way to exaggerate the devastation of a gamma-ray burst."

BTW, the picture of the satellite on this post is the Swift satellite, the detector of yesterday's burst. It was designed specifically to look for gamma ray sources in the sky.

1 comment:

J said...

The star exploded, 7.5 billion years ago and the light just hit earth after traveling 5.9 trillion miles per year for a period of 7.5 billion years. Thus, the light traveled for 44,250,000,000,000,000,000,000 miles before arriving here. To give you some idea how large a number we are talking, think about this chart of numbers:

Number of zeros
3 thousand
6 million 1000 thousand
9 billion 1000 million
12 trillion 1000 billion
15 quadrillion 1000 trillion
18 quintillion 1000 quadrillion
21 sextillion 1000 quintillion

And thats only half way across the universe!