Timeline for How do people calculate proportions of dark matter, dark energy and baryonic matter of the universe?
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
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| Sep 2, 2014 at 9:44 | comment | added | John Rennie | @gwho: the process for calculating the best fit values of the parameters is iterative, yes. | |
| Sep 2, 2014 at 9:43 | comment | added | ahnbizcad | @John Rennie ah, so it's an iterative problem | |
| Sep 2, 2014 at 5:21 | comment | added | John Rennie | @gwho: you put in initial guesses for the values of the parameters, then you use the model to compute the CMB spectrum and you compare it with the observations. Unless you made extraordinarily lucky guesses your calculation won't match reality, so you start adjusting your parameters to improve the fit. | |
| Sep 1, 2014 at 18:25 | comment | added | ahnbizcad | I'm most likely missing something, but it sounds like circular reasoning to me. Use those constants to create a model that we use to determine the proportions? Haven't we already assumed the proportions with those constants? | |
| Jul 4, 2013 at 6:15 | comment | added | Michael | +1: good answer. Re the parameters: scalar spectral index and curvature fluctuation amplitude have to do with the endpoint of inflation (measuring how lumpy the universe was at the start of the big bang), and the reionization optical depth basically measures how many CMB photons get jumbled by scatterings during the era where the first stars formed (since this happens much later than the CMB itself is formed you need to untangle the two effects). | |
| Jun 26, 2013 at 6:11 | history | answered | John Rennie | CC BY-SA 3.0 |