There is dark energy as sure as there is light in the world. It just may not be a simple scalar multiplier in our equations as we had hoped it would be. Dark energy is what the scientific consensus says that over 95% of the mass-energy of the universe is comprised of. This is backed by many studies and a new study to be published in the Astrophysical Journal (1) which also pairs with earlier research that showed the dark matter may not be the same in every direction (2). This indicates to my theorizing mind that the dark energy will turn out to be a scalar. I have more than speculation to back this up (3).
The dominant cosmological model is known as the concordance model or LambdaCDM. Lambda stands for the cosmological constant, which represents the dark energy. CDM means Cold Dark Matter. The normal, baryonic, matter we are made of is like dust on a couch by comparison. The mass energy we can see, touch, and are made of represents less than 5% of the universe. There are numerous studies that back this up.
What the works of Jacques and Kang have done is lead us to question the assumption that dark energy needs to be perfectly isotropic, look the same, in every direction. This is good, valid, valuable work and should be taken very seriously.
This does not mean it does not exist. My own unpublished theoretical musing was that dark mater and dark energy may be related phenomena. For this to make sense there have to be scalar (Higgs like) and vector (electromagnetism like) dark energy fields. What is and was a bit out there was that I theorized they could be reactive to the Ricci scalar. The Ricci scalar tells us how curved space time is at any given point. Which relates to how strong gravity is. This worked out to make dark matter that would annihilate to various forms of energy and not be detected in Earth bound experiments, while showing us strong evidence in astronomical observations.
I am not saying that the above cited papers support my theory. What I am saying is that some minor modification to the Lambda CDM model may be required. It may be mathematically more complex than a cosmological constant. It may be a cosmological function of some sort. Maybe with the leading term being a constant and quadratic in the dark energy fields for higher orders of correction, and more precise measurements? We don’t know.
That said, we can all relax. We know how much of the universe we don’t know about.
One of our strongest lines of evidence is computer simulations which match our views of the universe at the largest scales.
1. Cosmology, Early-Type Host Galaxies of Type Ia Supernovae. II. Evidence for Luminosity Evolution in Supernova. Kang,, Yijung , et al. Astrophysical Journal.
2. Evidence for anisotropy of cosmic acceleration, Astronomy&Astrophysics (2019). Jacques Colin, et. al. Astronomy&Astrophysics.
3. Farmer, Hontas. A Lagrangian which mathematically models Lambda CDM cosmology and explains the null results of dark astroparticle searches. Physics, DePaul University. s.l. : BePress, Vixra, 2013.