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Author Topic: What is the edge of the Universe?  (Read 2125 times)

Barbara Myers

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What is the edge of the Universe?
« on: 20/04/2011 11:30:01 »
Barbara Myers  asked the Naked Scientists:
   
Scientists are saying that they now think they can see the end of
the universe.  How do they know that?  What makes a rim or edge to the universe?

Thanks

Barb
Eureka, KS

What do you think?
« Last Edit: 20/04/2011 11:30:01 by _system »


 

Offline Mad Mark

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What is the edge of the Universe?
« Reply #1 on: 22/04/2011 01:03:02 »
As I understand it Scientist are now able to see  far enough back in time to see the very first stars light up after the darkness of a few million years after the Big Bang about 13.6 billion years ago. As for seeing the very edge of our Universe all you have to do is look out of your window and you will see it, because we are living on the edge of our Universe.Wait a second and you will get to see what was (probably) going to be outside our Universe a second ago!
 

Offline yor_on

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What is the edge of the Universe?
« Reply #2 on: 22/04/2011 20:25:13 »
Sweet description :)

I'm sort of interested in radiation myself. In one way the universe is boundless, infinite. But the 'light-sphere' we can observe is not. It started to shine at the Big Bang according to our current understanding some 13.? Billions years ago. And as light is defined as a constant unvarying 'speed' that means that light only can 'propagate' the same amount of 'light-years' through space.

So our visible universe is like a 'lighted bubble' where the radiation defines what we can see inside 'SpaceTime'. Assume that outside our bubble there are other 'light bubbles' as there must be if we are to believe in a unlimited space. Then those bubbles goes into eachother, each of them having the exact same 'size', like soap-bubbles able to glide in and out of each other without 'popping'.

It's a fascinating thought.
« Last Edit: 22/04/2011 20:38:11 by yor_on »
 

Offline imatfaal

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What is the edge of the Universe?
« Reply #3 on: 26/04/2011 12:32:35 »
As I understand it Scientist are now able to see  far enough back in time to see the very first stars light up after the darkness of a few million years after the Big Bang about 13.6 billion years ago. As for seeing the very edge of our Universe all you have to do is look out of your window and you will see it, because we are living on the edge of our Universe.Wait a second and you will get to see what was (probably) going to be outside our Universe a second ago!

That's damn close - but a couple of modifications.  It wasn't that the universe was dark - it was that the universe was bright everywhere!  We can now "see back" to the time when the Cosmic Microwave Background Radiation (CMBR) was formed.  This is the remnant of a (close to) homogeneously hot and bright universe - from very soon after the big bang till around 400,000 years everything was a highly energetic mix of plasma and electromagnetic radiation.  Every tiny volume of the universe was producing light; and also because there were free ions and electrons, every bit of the universe was absorbing and scattering light.  Thus the universe was bright and opaque.  In the era of last scattering (what a poetic name) neutral atoms started to form from the charged plasma and the universe stopped being opaque; the last light generated by the plasma that was not absorbed remained to travel the universe.  After much travelling and red-shifting we now see this light as the CMBR. 

The CMBR was predicted as a necessary result of the big bang hypothesis - and its discovery years later went a long way to vindicating this idea.  The reason we can see no further back than the CMBR/Era of Last Scattering is the very fact that previously to that the universe was opaque to light.  There is a distant possibility that once we can detect (easily) neutrinos and gravitational waves we can use them to directly observe the universe prior to 400,000 years after the big bang.
 

The Naked Scientists Forum

What is the edge of the Universe?
« Reply #3 on: 26/04/2011 12:32:35 »

 

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