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View Full Version : Shadows to tell astronomers about early universe



harlequin
2004-May-19, 11:59 PM
No, this is not about Babylon 5...

Astronomers plan to use shadows cast by gas clouds before the first stars formed to prove the early universe.

Cosmic dark age found in shadows (http://www.newscientist.com/news/news.jsp?id=ns99995014)

ToSeek
2004-May-20, 01:31 AM
I thought that sounded familiar:

http://www.badastronomy.com/phpBB/viewtopic.php?t=13322

Jpax2003
2004-May-20, 04:53 AM
No, this is not about Babylon 5...

Astronomers plan to use shadows cast by gas clouds before the first stars formed to prove the early universe.

Cosmic dark age found in shadows (http://www.newscientist.com/news/news.jsp?id=ns99995014)Oh man, I was excited for a minute that JMS had a new project out... or that he was was right all along. But how will shadows tell us about the age of the universe. I mean, afterall, shadows can travel faster than the speed of light.

opli
2004-May-20, 07:09 AM
I mean, afterall, shadows can travel faster than the speed of light.

How can shadows travel faster than the speed of light? They are only where light is not. They are only detected because the light did not travel where they exist. Shadows must travel at the same speed that their neighboring photons would travel.

Jpax2003
2004-May-23, 05:37 PM
I mean, afterall, shadows can travel faster than the speed of light.

How can shadows travel faster than the speed of light? They are only where light is not. They are only detected because the light did not travel where they exist. Shadows must travel at the same speed that their neighboring photons would travel.If you take a batman signal light and shine it on a cloud far away then rotate the spotlight at light speed, there is a point where the spot of light and the bat shadow would be moving across the cloud face faster than the speed of light.