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Author Topic: How far back in time can we see with powerful telescopes?  (Read 3187 times)

Offline Fortran

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Being a really thick bastard I'm having a bit of hubble trouble, that is, I am told the hubble has produced pictures of the universe as it was some  12.5 billion years ago, or about 1 billion years after it formed.

It seems to me that if this is the case then we maust have been travelling away from that point almost as fast as light since that time.

Or to put it another way,

Suppose I let off a flash-bang grenade then travel at light speed for 13.5 million years then as I stop and look back I will see the flash as it occured 13.5By ago - this is doing my head in....
« Last Edit: 15/05/2009 09:23:26 by chris »


 

Offline Vern

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Re: How far back in time can we see with powerful telescopes?
« Reply #1 on: 14/05/2009 15:24:26 »
The thinking now seems to be that space itself is expanding. So now we have two components to account for the vast distances that we sense between the most distant objects that Hubble can detect. One is a Doppler effect and the other is the expansion of space. Given the flexibility of these two assumptions any present distance is easily explained. The constraint of natural law is removed.

It is interesting that the most distant galaxies Hubble can detect seem to be like the galaxies we see close by. They contain the same amount of heavy metals. They also seem to possess a magnetic field similar to present day galaxies. These findings are troubling for some theories of the cosmos. 
« Last Edit: 14/05/2009 15:26:38 by Vern »
 

Offline Fortran

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Re: How far back in time can we see with powerful telescopes?
« Reply #2 on: 14/05/2009 17:08:45 »
Wouldn't it be great if we could see ourselves out there and our own galaxy appeared as it is today!  - that'd be a head scratcher!
 

Offline Vern

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Re: How far back in time can we see with powerful telescopes?
« Reply #3 on: 14/05/2009 22:24:14 »
Maybe the edge of the universe acts as a mirror and reflects light back to us. We might be seeing ourselves among the distant galaxies :)
 

Offline LeeE

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Re: How far back in time can we see with powerful telescopes?
« Reply #4 on: 15/05/2009 02:31:04 »
Being a really thick bastard I'm having a bit of hubble trouble, that is, I am told the hubble has produced pictures of the universe as it was some  12.5 billion years ago, or about 1 billion years after it formed.

It seems to me that if this is the case then we maust have been travelling away from that point almost as fast as light since that time.

Or to put it another way,

Suppose I let off a flash-bang grenade then travel at light speed for 13.5 million years then as I stop and look back I will see the flash as it occured 13.5By ago - this is doing my head in....

If you let off a flash-bang and then travel away from it at light speed for 13.5 billion years, then stop and turn around to look at it, you will indeed see the flash as it appeared 13.5 billion years ago i.e. when you let it off (it'll be a lot dimmer though, because of the inverse-square law).  This is because you, and the light, have been traveling away from where you let off the flash-bang for 13.5 billion years.  However, because you have been traveling at light speed, no time will have actually passed for you.
« Last Edit: 15/05/2009 02:34:14 by LeeE »
 

Offline Fortran

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How far back in time can we see with powerful telescopes?
« Reply #5 on: 15/05/2009 18:31:10 »
So just how fast has our galaxy been travelling away from these other galaxies to be able to look back and see a time when our galaxy would have been there not here?
 

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How far back in time can we see with powerful telescopes?
« Reply #5 on: 15/05/2009 18:31:10 »

 

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