On Deep Field Views: How did we get ahead of the light from distant seen objects?

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  • Member since
    January, 2014
On Deep Field Views: How did we get ahead of the light from distant seen objects?
Posted by Space-Jeff-Time on Monday, January 13, 2014 2:41 PM

Our increasingly deep field Hubble views are mind blowing. So much so that I would appreciate guidance past my personal paradox with these discoveries.

If all matter began as a single point at the moment of the big bang, how is it that the viewer (Hubble & Me) of objects as distant as 12 billion light years away is seemingly ahead of the light photons from that object to receive it? (Based on the common description that light-years is the amount of time for light to reach a  viewer)

Is the more accurate way to perceive seeing such objects that the light being captured is a beacon that was set in motion on a fixed plane to be later captured, irrespective of where the object creating the light eventually went or whether in fact it still exists? If the latter is the case, and we are viewing light from a single moment in time of an object, would it be possible to see light from that same object emanating from another position to which it traversed over the course of billions of years? Whoa. 

Thanks for any guidance...

  • Member since
    July, 2001
  • From: PA, USA, Earth Moderator
Posted by DaveMitsky on Tuesday, January 14, 2014 8:50 PM

Cosmological distances can be measured in a number of different ways.


Light travel time, or lookback time, is is the difference between the age of the Universe at the time of the observation (i.e., the present) and the age of the Universe at the time photons were emitted from the object being observed.



Look at it this way.  You can only see so far with the unaided eye.  A binocular allows you to see farther and a small telescope farther still. Large professional observatory telescopes and satellite telescopes allow astronomers to detect galaxies that are extremely distant.  With each "view" you are looking back farther into time, since light has a finite speed.  

All the while, the universe continues to expand so the distances between galaxies grow increasing greater with each passing second.  However, we can only observe these galaxies as they were at the time their light was emitted. 



Comoving distance takes into account the expansion of the universe and is a measure of how far distant objects really are at present.


Due to cosmological expansion, the observable universe - a sphere of potential detection centered on the Earth - is believed to be 28 billion parsecs or 93 billion light years in diameter.  The entire universe may be much, much larger.



Dave Mitsky

Sic itur ad astra!

Chance favors the prepared mind.

A man is a small thing, and the night is very large and full of wonders.

  • Member since
    February, 2014
Posted by Architeuthis on Sunday, February 16, 2014 11:06 AM

Interesting. I was asking myself something similar, recently: how come all the light in the universe hasn't passed us by already--unless the universe is expanding faster than the speed of light? Anyway, the Hubble images you're referring to probably came from phenomena that came into being a few billion years after the universe began, giving our galaxy time to move further out.

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