Timeline for What is the evidence that dark energy exists? (as of 2020)
Current License: CC BY-SA 4.0
21 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 12, 2021 at 20:18 | comment | added | ProfRob | No answer as usual. | |
| Jun 23, 2020 at 21:23 | answer | added | Andrew Steane | timeline score: 5 | |
| Feb 17, 2020 at 4:21 | comment | added | safesphere | @Allure I’ve explained my point quite extensively. If you still don’t see it, there is nothing more I can do, sorry. Regarding your last link, FLRW is not the only metric for an isotopic universe, so isotropy is not a proof of FLRW. Secondly, CMB is not even isotopic: en.m.wikipedia.org/wiki/Axis_of_evil_(cosmology) - Good luck! | |
| Feb 17, 2020 at 0:30 | comment | added | Allure | @safesphere read the paper in more detail, it doesn't address #4 of the above and I don't see how it could be either. But it's kind of moot anyway because the paper alludes to DES testing H(z), and DES has been operating for 6 years so it's presumably done the measurement. Besides FRW is pretty solidly grounded (see e.g. arxiv.org/pdf/1605.07178v2.pdf testing one of the fundamental assumptions) so I don't see your point. | |
| Feb 13, 2020 at 5:57 | comment | added | safesphere | @RobJeffries “Forums like this are full of people who underestimate the capacity of others for critical thinking.” - Ah, yes! And some of them even go as far as to blame others for underestimating the capacity of others for critical thinking! - “none of these alternate cosmologies have supplanted the $\Lambda CDM$ model” - And yet some dare to claim that such a great model is invalidated by direct observations with a certainty of $4.4\,\sigma$: physics.stackexchange.com/questions/530143/… :) | |
| Feb 13, 2020 at 5:03 | comment | added | safesphere | @Allure “SN1a [...] data indicate either that the geometry of the Universe is not Friedmann or that the luminosity distance is dominated at low redshift by an accelerating component” -royalsocietypublishing.org/doi/pdf/10.1098/rsta.2011.0285 | |
| Feb 12, 2020 at 22:31 | comment | added | ProfRob | Forums like this are full of people who underestimate the capacity of others for critical thinking. The idea that thousands, of cosmologists are restricting their work only to FLRW cosmologies is wrong. However, none of these alternate cosmologies have supplanted the $\Lambda CDM$ model because whilst they are capable of explaining individual results (like the type Ia supernovae) in isolation; they are incapable of explaining all the other observations too. The whole purpose of cosmological observations is to falsify models, including $\Lambda$CDM if necessary. | |
| Feb 12, 2020 at 19:43 | comment | added | Allure | @safesphere are you claiming that geometry removes the ability of supernovae to act as standard candles? | |
| Feb 12, 2020 at 19:10 | comment | added | Gary Godfrey | So far these 5 tests point to the existence of a constant curvature which could either be a fundamental constant $\Lambda$ or an energy density of something. If this curvature is found to vary in space/time or some dark energy stuff is detected, then dark energy on the right side of Einstein's field equation will be the best answer. | |
| Feb 12, 2020 at 18:30 | review | Close votes | |||
| Feb 20, 2020 at 15:07 | |||||
| Feb 12, 2020 at 18:08 | answer | added | A.V.S. | timeline score: 7 | |
| Feb 12, 2020 at 13:57 | comment | added | safesphere | @Allure Candle brightness depends on geometry. Consider a simple example of you are at the North Pole and light from the South Pole coming to you along the meridians evenly from all directions. The brightness of this source in any specific direction is zero. However, in a plane, the brightness of the source observed at the same distance is not zero. | |
| Feb 12, 2020 at 12:55 | comment | added | Allure | @safesphere eh, the candle data implies acceleration based on our understanding of redshift. We know redshift which gives us a recession velocity, and we have a standard candle which gives us a distance. We can plot a distance/velocity graph which gives us the Hubble law, and see how the Hubble constant changes with distance. I don't see where the Friedmann equations come into this. Please spell it out. | |
| Feb 12, 2020 at 12:20 | comment | added | safesphere | @Allure In #1, the candle data implies acceleration based on the Friedman geometry of spacetime. The exact conclusion is not that the universe definitely accelerates, but that either it accelerates or its geometry is not FLRW. Like I said above, all this evidence is model dependent. Using the same data with a different model yields a different result. The very idea of dark energy doesn’t come from observations, but from the inability of the FLRW metric to explain them. Sorry I am not familiar enough with #4, but it sounds similar to #1. | |
| Feb 12, 2020 at 12:05 | comment | added | Allure | @safesphere Can you explain how the Friedmann equations are related to #1 or #4 of the lines of evidence in the OP? | |
| Feb 12, 2020 at 12:02 | comment | added | safesphere | @annav There is no dark energy or the need dark energy outside of the Friedmann model. The concept of dark energy doesn’t come from observations. It comes from a dramatic failure of the Friedmann model to explain them. This model mismatches the observed matter content of the new inverse by 95% and is invalidated with the confidence of 4.4 sigma by the Hubble tension (physics.stackexchange.com/questions/530143/…). It is hard to imagine a more spectacular scientific failure. | |
| Feb 12, 2020 at 9:53 | comment | added | anna v | @WhitePrime This is a mainstream physics site, and for main stream physics there is ample evidence for the need of dark matter and recently dark energy in order to fit the observations. What they actually are, is a different problem under research presently both experimental and theoretical. | |
| Feb 12, 2020 at 9:50 | comment | added | anna v | @safesphere your logic is circular. When one uses energy and momentum conservation to define the existence of the neutrino, one is using special relativity algebra but one is not supporting special relativity. One makes a model in the context of special relativity, and if the model is validated, the results stand. neutrinos are now in the elementary particle table. Consistency is not "support" in the way you used it. | |
| Feb 12, 2020 at 8:23 | comment | added | White Prime | Actual evidence for Dark Energy and Dark Matter? Zero. | |
| Feb 12, 2020 at 6:27 | comment | added | safesphere | All this evidence is model dependent. One cannot justify the existence of dark energy to support the Friedmann model by using the Friedmann model to support the existence of the dark energy. This is a circular logic. | |
| Feb 12, 2020 at 5:32 | history | asked | Allure | CC BY-SA 4.0 |