This post is using advanced data and concepts from PLANCK's mission, excerpted from the ESA site:
"The image of the Cosmic Microwave Background taken by ESA's Planck satellite is the most precise snapshot of the
infant Universe ever made. Released in March 2013, this image contains a wealth of information about the properties
and history of the Universe for cosmologists to decipher."
"Fluctuations in the CMB correspond to the cosmic seeds that would evolve into all the structure observed in the Universe
today – from stars and planets to galaxies and galaxy clusters.
Planck's precise data enables cosmologists to investigate a huge variety of models for the origin and evolution of the cosmos.
The new image of the CMB has confirmed that the standard model of cosmology is a very good description of the Universe.
Dominated by the as yet unexplained dark matter and dark energy, the cosmos we live in appears to have begun almost
14 billion years ago with an early period of accelerated expansion, called inflation, during which the seeds of cosmic
structure were embedded in the Universe.
The data from Planck have allowed cosmologists to set very tight constraints on many parameters of the standard model,
including the Hubble constant (H0), which describes the expansion rate of the Universe today, the densities of baryonic matter,
dark matter and dark energy (Ωb, Ωm, ΩΛ), and the spectral index (ns), which describes the relative amount of primordial
fluctuations – the seeds of nascent cosmic structures – on different scales."
......... End of excerpts..............................................
And from this site: http://sci.esa.int/p...ave-background/
Gravitational lensing of the Cosmic Microwave Background
"Several observable effects arise from the interaction between CMB photons and the large-scale structure they crossed
during their journey. One of the most intriguing is gravitational lensing, the deflection of light as it travels in the vicinity of
massive objects such as galaxies and galaxy clusters. Gravitational lensing creates tiny, additional distortions to the
mottled pattern of the CMB temperature fluctuations.
On their way to the Solar System, where they are eventually detected by the sensors on board Planck, photons from the
CMB may cross many different massive systems as well as empty spaces. The photons encounter structures in different
evolutionary stages, since the massive structures grow denser and the cosmic voids become less dense as time goes by.
All of the structures from the different cosmic epochs contribute to bending the path of CMB photons. The total effect of
these multiple deflections is a modification to the pattern of CMB temperature fluctuations, thus changing the typical
'shapes' of hot and cold spots in the CMB.
As a result of the detection of gravitational lensing experienced by CMB photons, cosmologists can use Planck to explore
13 billion years of the formation of structure in the Universe."
Comments on Hubble's Constant and Expansion of the Universe
1) To understand this graph and any other graph that depicts the timeline of the evolutionary universe, one
and only one question arises: How come the time axis is calibrated when optical or EM observations of the
universe are done with different instruments (microwaves, IR, UV, X-Rays)?
1.1) There is no sense of depth while observing the Universe beyond a radius of 100 yl or less, even with
the most powerful scope. Within this radius, parallax effects are used, separated six months (2 AU).
Beyond that radius, parallax effect has no value, and the sense of depth is LOST.
1.2) Only after 1923 (Mont Wilson's observatory, Dr. Hubble and colleagues) Andromeda was identified as a galaxy,
and many others were found in the next decade. The calculation of its distance was based on relative luminosity
of known objects (like Cepheids) and the inverse square law of apparent luminosity (a relative value).
And only around 1929, when Hubble finished his primary work, his empirical constant began to be used on the
basis of red-shifting of the fundamental lines of absorption from known elements and 70 years of spectroscophy
pioneered by Kirchoff and other, by mid XIX century.
The whole history is covered here: https://en.wikipedia...ki/Hubble's_law
Then, such a "constant" was applied to what was observed and photographed, and distances were assigned only
on this elementary basis: a simple arithmetical relationship.
D = c . ( L– L0)/(H0 .L0) = c . z /H0 (L is Lambda)
1.3) The above formula suffered many corrections for values of H0 and also z red-shift formerly measured,
being that, originally, Hubble's estimation for H where around 500 Km.sec-1.MParsec-1.
Currently, and following ESA information: http://sci.esa.int/p...ubble-constant/
there are two different values for H0:
Derivation by astrophysics in the past 20 years gives H01 = 73.5 Km.sec-1.MParsec-1, with 2% uncertainty.
Derivations by PLANCK's mission data processing gives: H02 = 67.4 Km.sec-1.MParsec-1, with 1% uncertainty.
Using H01 and the speed of light c0, the age of the universe can be calculated as T01 = c0/H01+0.22 By, wich gives
an estimated age (others) of 13.77 By and an estimated radius of the Hubble's Sphere of 13.55 Byl (CMB edge).
Using H02 = H0 and the speed of light c0, the age of the universe can be calculated as T02 = c0/H02+0.22 By, wich
gives an estimated age (PLANCK) of 14.78 By and an estimated Hubble's Sphere radius of of 14.51 Byl (CMB edge).
ESA notes that, given that H0 was obtained by two completely different methods, is extraordinary that both
values are so close. The differences (measurements within the local universe and from the infant universe) are
something that has to be evaluated and conciliated.
2) Adopting the value H01 of 1.3), the visible universe radius is 13.55 Byl (astrophysical measurements plus WMAP data).
IF H01 is time-invariant, then everything we observe at the universe is older than our Earth now. The Hubble's sphere
contains celestial objects that evolved from the primordial explosion at t=0, and the further we observe with telescopes,
the older is the light that reaches us. So, we always look into the past with astronomical observations.
A very crude ratio of expansion can be derived by dividing Hubble's radius by age, which give almost 1 ly per year
since CMB was formed.
But this simplicity implies the time-invariance of H0 and several other cosmological aspects, the first one introduced by
A. Friedmann in 1922 with his equations of an universe in expansion, derived from Einstein's Field Equation. This theory
might have been the inspiration for Le Maitre original Big Bang theory in 1927.
From this theory survives (as per Wikipedia) the Scale Factor R(t), which affects the Hubble "constant", making it
R(t) dependant, as well as the z red-shift.
Excerpt from Wikipedia (Hubble's law):
Suppose R(t) is called the scale factor of the universe, and increases as the universe expands in a manner that
depends upon the cosmological model selected. Its meaning is that all measured proper distances D(t) between
co-moving points increase proportionally to R. (The co-moving points are not moving relative to each other except
as a result of the expansion of space.)
3) Excerpt from Wikipedia (Comoving and proper distances):
In standard cosmology, comoving distance and proper distance are two closely related distance measures used by
cosmologists to define distances between objects. Proper distance roughly corresponds to where a distant object
would be at a specific moment of cosmological time, which can change over time due to the expansion of the universe.
Comoving distance factors out the expansion of the universe, giving a distance that does not change in time due to
the expansion of space (though this may change due to other, local factors, such as the motion of a galaxy within a
Comoving distance and proper distance are defined to be equal at the present time; therefore, the ratio of proper
distance to comoving distance now is 1. At other times, the scale factor differs from 1. The Universe's expansion results
in the proper distance changing, while the comoving distance is unchanged by this expansion because it is the proper
distance divided by that scale factor.
4) Wikipedia: Missconceptions about the size of the universe.
The comoving distance from Earth to the edge of the observable universe is about 14.26 gigaparsecs
(46.5 billion light-years) in any direction. The figure quoted above is distance now (in cosmological
time), not distance at the time the light was emitted.
For example, the CMBR that we see right now was emitted at the time of photon decoupling, estimated to have
occurred about 380,000 years after the Big Bang, which occurred around 13.8 billion years ago. This radiation
was emitted by matter that has, in the intervening time, mostly condensed into galaxies, and those galaxies are
now calculated to be about 46 billion light-years from us.
5) The root of the discussion in this thread:
I quote a complain by a cosmologist about the use of light travel time in the media:
Why the Light Travel Time Distance should not be used in Press Releases
By Edward L. Wright (02 August 2013)
Since public information offices in the US never want to mention the redshift of an object, distances are usually
given as light travel time distances. This has one simple property: the distance in light years is never greater
than the age of the Universe in years, avoiding at least one appearance of speeds greater than the speed of light.
This doesn't really satisfy the simplicity requirement, because a numerate listener will ask: if a distant cluster of galaxies
is 9.1 billion light years away in a universe that is 13.7 billion years old, how did the cluster get so far away in only 4.6
billion years? If must have been travelling faster than the speed of light! Apparently it takes several minutes for this
question to arise, and by that time the presenters are out the door. So I get an E-mail.
So here I will list the reasons why this press office policy is really dumb:
- The redshift z is usually the only number in the whole story that is unambiguous and likely to be correct.
- Distance is defined as the spatial separation at a common time. It makes no sense to talk about the difference in spatial positions of a distant galaxy seen 9.1 billion years ago and the Milky Way now when galaxies are moving.
- If an SR-71 blackbird flies over at Mach 3 and you hear the sound 30 seconds later, then answer to the question "How far away is it?" is clearly not 30 "sound seconds" or 10 km.
- The Universe is homogeneous and isotropic, so it has no edge. Thus there cannot be a maximum distance. Distances greater than speed of light times the age of the Universe are commonplace.
The article contains a few more paragraphs and some graphs.
So, the problem is simple: There is no consensus between something currently being NOW X billion light years in the past flowtime (age) and its location being NOW at Y billion light years far away from us. Or, simplifying, there is no consensus (worldwide) about HOW the visible universe from the PAST has expanded and objects are co-located NOW in the time-space at this day.
The only problem about this claim is that the difference between Y billion light years (possible distance TODAY, Y billion years after, which is unobservable) and X billion light years back in time (X billion years) can't and won't be proved. NEVER. (Unless we may leave a message for someone Y billion years in the future to check it for us. But probably, the Solar System will be gone by then).
Or, as I used to say:
Billion years OLD or Billion years LIGHT AWAY?
Edited by rhertz, 19 May 2019 - 11:12 PM.