What if dark matter and dark energy did not exist and were only due to a misinterpretation of the red shift of light or a measurement bias?
What would be the implications/consequences?
$\begingroup$
$\endgroup$
3
-
$\begingroup$ You can generate a lot of questions like this. What if gravity did not exist and were only due to a measurement bias? What if light did not exist and were only due to a measurement bias? What if stars did not exist and were only due to a measurement bias? Or guraffes, for that matter? $\endgroup$– WillOAug 8 at 12:50
-
2$\begingroup$ But of course redshifts are not the only, or even the best, evidence for dark matter. $\endgroup$– ProfRobAug 8 at 19:49
-
$\begingroup$ This post contains two separate questions. You could read this: en.wikipedia.org/wiki/…. and this: en.wikipedia.org/wiki/Dark_energy $\endgroup$– my2ctsAug 9 at 9:43
Add a comment
|
1 Answer
$\begingroup$
$\endgroup$
I'll start with dark matter, since I think the evidence for that is stronger and more multi-stranded.
It isn't clear what you mean by "misinterpretation of redshift" - I am presuming you mean the form of the redshift-dstance relation in cosmology. This in principle gives us measurements of the density of matter (dark or otherwise) and the density of dark energy. It is not evidence for dark matter in isolation.
The evidence for dark matter is found in the dynamics of stars and gas in the Milky Way and other galaxies (note that since the publication of Gaia proper motions, this does not only rely on velocity measurement through redshift); in the dynamics of galaxies within clusters; gravitational lensing by galaxy clusters; the evolution of cosmic structure with time; the angular power spectrum of the cosmic microwave background and from the primordial abundances of helium and deuterium.
Thus if there is no dark matter, it isn't just a question of not interpreting cosmological redshifts correctly; there are many areas of physics, everything from General Relativity to nuclear physics, that would need to be re-evaluated. That is why dark matter is generally accepted as a working hypothesis even though we can't yet directly detect it.
I think dark energy is a little different. Whilst there are plausible candidates and mechanisms to explain and produce dark matter, dark energy is truly mysterious. I think it is also fair to say that the evidence for dark energy, although strong, is not as strong or as wide-ranging as for dark matter. It does rely to a great extent on a correct interpretation of the redshift-distance relation at moderately large redshifts using "standard candles" (type Ia supernovae), that may not be as standard as one would like.
Thus one implication of the lack of dark energy is that it would mean we may not understand the standard candles or their environments well enough.
Secondly, if there were no dark energy we have independent evidence from the cosmic microwave background that the universe is geometrically flat. This would mean we would need to almost treble the amount of matter in the universe and it isn't clear how this is possible, particularly if you are also saying there is no dark matter! The census of normal matter is only about 5% of what would be required.