New On-line Cosmology Calculator

• marcus
In summary, an astronomy professor at a University in Iowa has created a webpage containing various online astro java applets, including a "cosmology calculator." By default, the calculator uses a Hubble parameter of 70, a matter density of 0.27, and a cosmological constant of 0.73. By inputting a redshift, the calculator can determine the distance and recession speed of the observed object. Additionally, there is a rule of thumb for estimating recession speeds for redshift values between 1.5 to 6. This rule can be found on the professor's webpage or in an explanatory paper by Davis and Lineweaver.

marcus

Gold Member
Dearly Missed
An astronomy prof who teaches at a University in Iowa
maintains a resource page of online astro java applets
for students and general public to use
and one of the applets is "cosmology calculator"
http://www.earth.uni.edu/~morgan/ajjar/Cosmology/cosmos.html [Broken]

Here is her homepage
http://www.earth.uni.edu/smm.html [Broken]

If you try out the "cosmology calculator" and want it to give mainstream consensus answers similar to Ned Wright's and so on, then leave the Hubble parameter 70 (the default)
and put 0.27 in for the matter density ("omega")
and put 0.73 in for the cosmo. const. ("lambda")

Then every time you put in a redshift z (like z = 6.4 for a recently observed quasar) and press "calculate" it will tell you
how far away the thing was when it emitted the light we are now receiving from it

how far away it is now

how fast it was receding from us when it emitted the light we are now receiving

Last edited by a moderator:
A nifty rule of thumb for recession speeds

http://www.earth.uni.edu/~morgan/ajjar/Cosmology/cosmos.html [Broken]

leave the Hubble parameter 70 (the default)
and put 0.27 in for the matter density ("omega")
and put 0.73 in for the cosmo. const. ("lambda")

For z in the range 1.5 to 6, good rule of thumb for recession speeds is this:

add one to the redshift and multiply by 0.4
this will give the speed that the thing was receding
at the moment it emitted the light that we are seeing
and it will give the ("then") recession speed as a
multiple of c.

So redshift 1.7 implies 1+z = 2.7 implies it was receding at just over the speed of light

And redshift 5 implies 1+z = 6 implies it was receding at 2.4 times speed of light

This is an approximate, not exact, rule. It seems accurate to two significant digits which often gives a good enough idea, and saves having to use one of the online calculators or (godforbid) do an integral.

So that quasar observed in 2002 with z = 6.4 was retreating at almost 3 c when it sent us its light.
It might occur to someone to ask how it happens that the light ever got here. It must have begun its journey by actually losing ground to the Hubble flow and being swept back away from us---how can it eventually arrived here? Davis and Lineweaver discuss this in an explanatory paper "Superluminal Recession Velocities" that I believe you can find by google as well as by the arxiv search function.

Last edited by a moderator:

1. How accurate is the "New On-line Cosmology Calculator" in predicting cosmic events?

The "New On-line Cosmology Calculator" is a highly accurate tool that uses advanced mathematical models and data from the latest scientific research to predict cosmic events. However, it is important to note that no prediction tool can be 100% accurate.

2. What types of calculations can be done with the "New On-line Cosmology Calculator"?

The "New On-line Cosmology Calculator" can perform a variety of calculations related to cosmology, such as calculating distances between celestial objects, predicting the evolution of the universe, and estimating the age of the universe.

3. Is the "New On-line Cosmology Calculator" user-friendly for those without a background in cosmology?

Yes, the "New On-line Cosmology Calculator" is designed to be user-friendly for individuals without a background in cosmology. It provides clear instructions and explanations for each calculation, making it accessible to a wide range of users.

4. Can the "New On-line Cosmology Calculator" be used for educational purposes?

Yes, the "New On-line Cosmology Calculator" can be a valuable educational tool for students and anyone interested in learning more about cosmology. Its user-friendly interface and accurate calculations make it a great resource for educational purposes.

5. Is the "New On-line Cosmology Calculator" constantly updated with new data and research?

Yes, the "New On-line Cosmology Calculator" is regularly updated with the latest data and research in the field of cosmology. This ensures that the calculations are as accurate as possible and reflect the most current understanding of the universe.

Replies
5
Views
4K
Replies
1
Views
2K
Replies
67
Views
29K
Replies
4
Views
2K
Replies
548
Views
209K
Replies
2
Views
2K