What Does the Maximum Proper Distance at z ~ 1.7 Mean in Cosmology?

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In summary, when looking at a graph of proper distance at the time of emission as a function of redshift in a model-universe with only matter, there is a maximum at z ~ 1.7. This maximum represents the distance at which light from sources with high redshifts (indicating a larger distance in the past) and low redshifts (indicating a smaller distance in the past) originate from. The maximum does not have any specific significance.
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Niles
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Homework Statement


Hi all.

When looking at a graph that shows the proper distance at the time of emission as a function of the redshift z in a model-universe with only matter, the proper distance at time of emission has a maximum at about z ~ 1.7. What does this maximum mean?

I can see that light with a high redshift must come from a source, which was initially close to us, and similarly light with a small redshift also comes from close to us. But again, what about the in-between, i.e. the maximum?
 
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  • #2
Since it's distance at the time of emission, yes, small z comes from sources nearby in distance and time and large z comes from sources that are currently far away, but were close at the time of emission because the universe was so much smaller. I think that's what you are saying. So, sure, then there must be a maximum. I don't think that maximum has any particular significance.
 
  • #3
Ok, thanks. I didn't suspect it having any meaning, but it's always nice to get a second-opinion.
 

FAQ: What Does the Maximum Proper Distance at z ~ 1.7 Mean in Cosmology?

What is proper distance in cosmology?

Proper distance is a measurement in cosmology that takes into account the expansion of the universe over time. It is the distance between two objects at a specific point in time, and it is measured in units of length (such as kilometers or light years).

How is proper distance different from comoving distance?

Comoving distance is a measure of the distance between two objects in terms of the expansion of the universe. It takes into account the expansion of space itself, rather than just the distance between two objects at a specific point in time. Proper distance is the comoving distance at a specific point in time.

How is proper distance calculated?

Proper distance is calculated using the Hubble constant, which is a measure of the rate at which the universe is expanding. The formula for proper distance is d = (c/H0) x z, where d is the proper distance, c is the speed of light, H0 is the Hubble constant, and z is the redshift of the object.

What is the significance of proper distance in cosmology?

Proper distance is a crucial factor in understanding the expansion of the universe and the concept of cosmic distance. It allows scientists to measure the current and past distances between objects in the universe, and to track the changes in these distances over time.

How does proper distance relate to the age of the universe?

The proper distance between objects in the universe is directly related to the age of the universe. As the universe continues to expand, the proper distance between objects will increase. By measuring the proper distance and the rate of expansion, scientists can estimate the age of the universe.

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