A Redshift Lookup Table for our Universe
			
		
		
		
			How far away is "redshift six"?
Although humans are inherently familiar with 
distance and 
time, 
what is actually measured for astronomical objects is 
redshift, 
a color displacement that depends on exactly how energy density has evolved in our universe.
Now since cosmological measurements in recent years have led to a 
concordance on what 
energy forms 
pervade our universe, it is now possible to make a simple table relating observed 
cosmological redshift, labeled "z", with standard concepts of distance and time, including the 
extrapolated time 
since the universe began.
One such table is 
listed above, where redshift z is listed in the first and last columns, 
while the corresponding universe age in billions of years is listed in the central column.
To find the meaning of the rest of the columns, please read the 
accompanying technical paper.
Although stars in our galaxy are effectively at 
cosmological redshift zero, 
the most distant 
supernovae 
seen occur out 
past redshift one, 
which the above chart shows occurred when the universe was approximately half its present age.
By contrast, the most distant 
gamma-ray bursts yet observed occur out 
past redshift six, occurring when the universe was younger than one billion years old, 
less than 10 percent of its present age.