MadSci Network: Astronomy

Re: How could objects be further than 14 billion light years apart?

Date: Thu Jul 6 10:01:10 2000
Posted By: Meghan Gray, Grad student, Astronomy, Cambridge University
Area of science: Astronomy
ID: 962601777.As

Hi Dave,
There's been a lot of excitement recently as new and powerful astronomical 
surveys discover objects further away than any that have been detected
before.  It seems that every week the record gets pushed back a little

The basic answer to your question is that even if the universe is only (!)
14 billion years old we can see objects further away than 14 billion light 
years because the universe is expanding.  Because of of this expansion,
the object is further away now than it was when the light that we see
today was emitted.  Or in other words, the light from the object may have
been travelling for close to 14 billion years, but the distance we measure
now must be greater than 14 billion light-years because the universe itself
has gotten bigger since the time the light was emitted!

The Sloan Digital Sky Survey is one of the major surveys that is turning
up extremely distant objects.  Their web page has a comprehensive
discussion of your very question, so I would recommend you look there
for more information!


[Moderator's note: several other questions and answers on our site also deal
with this topic. Try using our search engine, with 'universe expansion distance'
in the search box, to find out more.]

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