View Single Post
  #2  
Old October 25th 18, 06:15 PM posted to sci.astro.research
Phillip Helbig (undress to reply)[_2_]
external usenet poster
 
Posts: 273
Default Cosmological Problems

In article ,=20
"Richard D. Saam" writes:

There have been recent cosmological experimental disclosures
represented in part by the following:
=20
The 7Be(n,p)7Li reaction and the Cosmological Lithium Problem:=20
measurement of the cross section in a wide energy range at n\_TOF (CERN)
https://arxiv.org/abs/1806.03050
"The new estimate of the 7Be destruction rate based on the new results=20
yields a decrease of the predicted cosmological Lithium abundance of=20
~10%, insufficient to provide a viable solution to the Cosmological=20
Lithium Problem."
What is the resolution to the Lithium problem?


I, personally, don't know. Note, however, that the observations are not=20
easy.

No WIMPS have been found in reference to the dark matter problem.
What are the dark matter alternatives?


Primordial black holes are still viable. Also, absence of evidence is=20
not evidence of absence. Even though we knew the sources and how many=20
were produced, it still took a long time before neutrinos were=20
discovered. Since practically nothing is known about WIMPs, there are=20
no robust predictions for cross sections and hence reaction rates.

Collective Effects in Nuclear Collisions: Experimental Overview
https://arxiv.org/abs/1810.06978
Viscosity plays an important role in measured LHC RHIC nuclear dynamics
Does this viscosity experimental result
influence BBN gas phased mechanisms?


Do you have reason to think so? BBN seems reasonably successful.

MILKY WAY CEPHEID STANDARDS FOR MEASURING COSMIC DISTANCES AND=20
APPLICATION TO Gaia DR2:
IMPLICATIONS FOR THE HUBBLE CONSTANT
https://arxiv.org/abs/1804.10655
The Planck H0 =3D 67.4 km/s/Mpc is based on CMB.
The reported H0 =3D 73.24 km/s/Mpc is based on photometric parallaxes.
What mechanism explains the difference?


Add the error bars and you have a three-sigma difference. Most would=20
consider it irresponsible to base a detection on three sigma, so why=20
base a tension on it.

The universe increased expanding rate
is an expression of dark energy measured by supernovae type II events.
What is dark energy?


Observationally, it is indistinguishable from a cosmological constant. =20
Theoretically, there is no reason it is not the cosmological constant. =20
There is no problem.

The cosmological constant problem or the vacuum catastrophe
indicates a vacuum energy theory differing from experiment
by 120 orders of magnitude.
What is the vacuum energy?


It is clear from quantum field theory what it is. Why the observed=20
cosmological constant is much smaller is not completely clear, but 40=20
years ago Weinberg came up with an anthropic explanation, which no-one=20
has refuted. Also, look for the paper by Bianchi and Rovelli. This is=20
probably another non-problem.

Is there a common theoretical mechanistic thread
connecting these experimental dots?


Probably not. To prove that there is, one would have to construct such=20
a theory.