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?
No WIMPS have been found in reference to the dark matter problem.
What are the dark matter alternatives?
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?
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?
The universe increased expanding rate
is an expression of dark energy measured by supernovae type II events.
What is dark energy?
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?
Is there a common theoretical mechanistic thread
connecting these experimental dots?
In article <qZidnZewGob5elHGnZ2dnUU7-YnNnZ2d@giganews.com>,=20something amiss with BBN?
"Richard D. Saam" <rdsaam@att.net> writes:
There have been recent cosmological experimental disclosures
represented in part by the following:
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
yields a decrease of the predicted cosmological Lithium abundance of
~10%, insufficient to provide a viable solution to the Cosmological
Lithium Problem."
What is the resolution to the Lithium problem?
I, personally, don't know. Note, however, that the observations are not easy.
but there are arguments against black holes as dark matter https://arxiv.org/abs/1808.05910No 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
not evidence of absence. Even though we knew the sources and how many
were produced, it still took a long time before neutrinos were
discovered. Since practically nothing is known about WIMPs, there are
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
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 consider it irresponsible to base a detection on three sigma, so why
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. Theoretically, there is no reason it is not the cosmological constant.
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 cosmological constant is much smaller is not completely clear, but
years ago Weinberg came up with an anthropic explanation, which no-one
has refuted. Also, look for the paper by Bianchi and Rovelli. This is 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
a theory.
No WIMPS have been found in reference to the dark matter problem.
What are the dark matter alternatives?
Primordial black holes are still viable.
but there are arguments against black holes as dark matter https://arxiv.org/abs/1808.05910
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.
Yes, observed BBN expressions are reasonably successful
(except for the Lithium problem),
but the realm of fluid viscosity is different the gas kinematics.
It implies that we are looking at gas phase BBN
and there also exists a viscous BBN,
something like looking at the steam
but knowing the presence of water somewhere.
MILKY WAY CEPHEID STANDARDS FOR MEASURING COSMIC DISTANCES AND
APPLICATION TO Gaia DR2:
IMPLICATIONS FOR THE HUBBLE CONSTANT
https://arxiv.org/abs/1804.10655
The Planck H0 = 67.4 km/s/Mpc is based on CMB.
The reported H0 = 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 consider it irresponsible to base a detection on three sigma, so why
base a tension on it.
The paper reports a 96.5% confidence level
for the difference in the HOs 67.4 and 73.24 km/s/Mpc:
'The best-fit distance scale is 1.006 ± 0.033 , relative to the scale
from Riess et al. (2016) with H0 = 73.24 km/s/Mpc used to predict
the parallaxes photometrically, and is inconsistent with the scale
needed to match the Planck 2016 CMB data combined with LambdaCDM at the 2.9\sigma confidence level (99.6%). At 96.5% confidence we find that the formal DR2 errors may be underestimated as indicated.'
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. Theoretically, there is no reason it is not the cosmological constant. There is no problem.
Here are some Weinberg's thoughts on the problem: http://supernova.lbl.gov/~evlinder/weinberg.pdf
'The problem of the dark energy is also central to today's physics.
Our best attempts at a fundamental theory
suggest the presence of a cosmological constant
that is many (perhaps as many as 120) orders of magnitude greater
than the upper bound set by astronomical observations.Until it is
solved, the problem of the dark energy
will be a roadblock on our path
to a comprehensive fundamental physical theory.'
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 cosmological constant is much smaller is not completely clear, but
years ago Weinberg came up with an anthropic explanation, which no-one
has refuted. Also, look for the paper by Bianchi and Rovelli. This is probably another non-problem.
ditto Weinberg's thoughts from above
Is there a common theoretical mechanistic thread
connecting these experimental dots?
Probably not. To prove that there is, one would have to construct such
a theory.
Maybe the mechanism as simple as recognizing an entirely different phase analogous to liquid and gas relationships.
Then observational cosmology and associated theories
are not eliminated but complemented.
What is the resolution to the Lithium problem?
No WIMPS have been found in reference to the dark matter problem.
What are the dark matter alternatives?
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?
MILKY WAY CEPHEID STANDARDS FOR MEASURING COSMIC DISTANCES AND
APPLICATION TO Gaia DR2:
IMPLICATIONS FOR THE HUBBLE CONSTANT
https://arxiv.org/abs/1804.10655
The Planck H0 = 67.4 km/s/Mpc is based on CMB.
The reported H0 = 73.24 km/s/Mpc is based on photometric parallaxes.
What mechanism explains the difference?
The universe increased expanding rate
is an expression of dark energy measured by supernovae type II events.
What is dark energy?
The cosmological constant problem or the vacuum catastrophe
indicates a vacuum energy theory differing from experiment
by 120 orders of magnitude.
Referencing a good summary article on the Ho tension:MILKY WAY CEPHEID STANDARDS FOR MEASURING COSMIC DISTANCES AND
APPLICATION TO Gaia DR2:
IMPLICATIONS FOR THE HUBBLE CONSTANT
https://arxiv.org/abs/1804.10655
The Planck H0 = 67.4 km/s/Mpc is based on CMB.
The reported H0 = 73.24 km/s/Mpc is based on photometric parallaxes.
What mechanism explains the difference?
The difference is less than 3 sigma so may not be real. If there is
a difference, time-variable dark energy would be one possibility.
The Adam Riess colloquium I posted about earlier https://www.youtube.com/watch?v=eSPCy-IJaPg
is still relevant and easy to follow.
On 11/9/18 1:37 AM, Steve Willner wrote:
MILKY WAY CEPHEID STANDARDS FOR MEASURING COSMIC DISTANCES AND
APPLICATION TO Gaia DR2:
IMPLICATIONS FOR THE HUBBLE CONSTANT
https://arxiv.org/abs/1804.10655
The Planck H0 = 67.4 km/s/Mpc is based on CMB.
The reported H0 = 73.24 km/s/Mpc is based on photometric parallaxes.
What mechanism explains the difference?
The difference is less than 3 sigma so may not be real. If there isReferencing a good summary article on the Ho tension:
a difference, time-variable dark energy would be one possibility.
The Adam Riess colloquium I posted about earlier https://www.youtube.com/watch?v=eSPCy-IJaPg
is still relevant and easy to follow.
Measuring cosmic distances with standard sirens Physics Today, Dec 2018
universe expansion using supernovae Ho1 = 73.24 +/-1.74 km s^-1 Mpc^-1
and
Planck satellite's CMB fluctuations Ho2 = 67.74 +/-.46 km s^-1 Mpc^-1
The hope is to resolve Ho tension with standard siren determination.
There is one currently available measurement GW170817
with the hope of many more.
The actual event rates for BH/BH, NS/NS, and BH/NS coalescences are
rather uncertain. To date 7, 1, and 0 of these (respectively) have been observed (https://arxiv.org/abs/1811.12907), and with continued GW-detector tweaks and improvements) it seems likely that the detection rates will increase by a factor of 3-10 over the next decade.
[Moderator's note: The James Webb Space Telescope is more like a
traditional telescope in space, the successor to HST in some sense, but
with more emphasis on the infrared.
The CMB is observed at lower frequencies
As far as I know there is no CMB satellite in the works,
but some ground-based stuff such as the Simons Observatory. -P.H.]
[Moderator's note: The James Webb Space Telescope is more like a traditional telescope in space, the successor to HST in some sense, but with more emphasis on the infrared.
JWST wavelength range is roughly 0.6 to 27 microns
The CMB is observed at lower frequencies
much longer wavelengths than JWST.
All ground-based and balloon telescopes study relatively high
multipoles, i.e., relatively small angular scales.
I think it's only
the lower multipoles that carry information on H, but I may be wrong.
Visible light is about 0.4 to 0.7 microns (400 to 700 nm (nanometers),
there is a bit of overlap between HST and JWST.
JWST is more or less a normal reflecting telescope, with a CCD as
detector.
You can easily search for "Planck focal plane" on the web and find an
image showing lots of horns and other radio-astronomy stuff. Planck has
a wide frequency range, with frequencies from 30 GHz to 857 GHz, corresponding to wavelengths between a centimetre and about a third of a millimetre, the latter being about 300 microns. Typical traditional ground-based radio astronomy is in the GHz range and below, so
wavelengths from centimetres to metres.
https://space.mit.edu/home/tegmark/movies.html
In the plots, as usual, larger angular scales are on the left, smaller
ones on the right.
In article <pv93gv$pfo$1@gioia.aioe.org>,
helbig@asclothestro.multivax.de (Phillip Helbig (undress to reply)) writes:
Visible light is about 0.4 to 0.7 microns (400 to 700 nm (nanometers),
That range is what the human eye can see. In practice, the term
"visible" often refers to light detectable by instrumentation
suitable for visible light, say from 300 nm (the atmospheric cutoff)
to 1000 nm (the intrinsic silicon limit).
Typical traditional
ground-based radio astronomy is in the GHz range and below, so
wavelengths from centimetres to metres.
Frequencies up to 15 GHz (wavelength 2 cm) were pretty common even
when I was in school. Nowadays, the VLA https://public.nrao.edu/telescopes/vla/
makes images up to 50 GHz, and ALMA
https://public.nrao.edu/telescopes/alma/
goes up to 950 GHz (though I don't think the highest frequencies are
100% operational yet).
In practice, the term
"visible" often refers to light detectable by instrumentation
suitable for visible light, say from 300 nm (the atmospheric cutoff)
to 1000 nm (the intrinsic silicon limit).
(In the same fashion, this silicon is a 'metal' of course!)
950 GHz sounds like an interesting LNA design problem!
Is there any pointer to the solutions they use? (Other metals than
silicon, undoubtedly..)
I wrote:
In practice, the term
"visible" often refers to light detectable by instrumentation
suitable for visible light, say from 300 nm (the atmospheric cutoff)
to 1000 nm (the intrinsic silicon limit).
In article <5c2cab94$0$22362$e4fe514c@news.xs4all.nl>,
Jos Bergervoet <bergervo@iae.nl> writes:
(In the same fashion, this silicon is a 'metal' of course!)
Heh. (Silicon is a semiconductor, not a metal, for anyone who is
confused.) I reported how the language is used in practice. Human
language is not always logical. I don't think I've seen silicon
described as a metal, but it wouldn't shock me. Actually, come to
think of it, doesn't silicon become a metal at very high pressure?
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