Calibrating the Cosmos

How Cosmology Explains Our Big Bang Universe

Frank Levin, Central 523.18 L665C 2007

I read this book cover to cover, attempting to understand what the measurements are that define current cosmological models, and why those particular models are chosen. As the author uses words rather than algebra, it was difficult for me to follow the arguments. The book I am really looking for probably hasn't been written, but lies somewhere just beyond algebra on the mathematical spectrum. Use equations by all means, but explain them, and the mathematics behind them, using the kind of algebra and calculus that all undergraduate scientists and engineers understand. Use math for expressive precision, not compactness.

I did find some of what I wanted. Mostly references to track down. I learned that spherical symmetry drives cosmology, but not why symmetry must characterize cosmic models. Spheres and epicycles dominated medieval cosmology until Kepler used Tycho's data to derive his three laws concerning elliptical orbits, non-symmetric laws which still define (to very high precision) almost everything we observe, within a billion parsecs. Hubble's additional observations suggest the expansion of space and lead to some version of the big bang. Very distant observations, including the details of the Cosmic Microwave Background (CMB), are low power and noisy, but suggest more details about the big bang.

Galactic rotation measurements by Zwicky and Rubin suggest that most of the mass in the universe is nonluminous. Recent measurements of very distant, high redshift Sn1a supernovae suggest accelerating expansion beginning about 5 billion years ago.

However ...

Most baryonic mass is NOT luminous; almost NONE of it was for the first billion years, and the mass comprising our own solar system was non-luminous and practically invisible 5 billion years ago. 2017 papers by de Graaff et. al. and Tanimura et. al. describe warm/hot gas filaments between galaxies that measured quite indirectly from the Sunyaev-Zel'dovich effect on the cosmic microwave background. This "dark" mass alone is three times the luminous baryonic mass - what else is out there, someday detectable with better instruments?

Not observing something does not define what is not observed. There are an infinite number of models that can describe the same missing points, including models of measurement instruments that miss data. Accumulating data at LHC verifies the likely existence of the Higgs particle, but hasn't discovered supersymmetric particles, or nailed down important behaviors like the mass of some of the quarks. The missing data mostly expresses the limitations of the telescopes we can afford to build using current methods and funding. Perhaps it is time to reallocate funding away from cosmological theory and towards better instrumentation models and design; we need more data, not more intrinsically unprovable hypotheses.

This phrase on page 215 vaguely answers one of my questions:

That hints at the measurement, but not what the measurement is, how noisy it is, how the noise is explained. These distant type 1A supernovae (assumed) are measured against galactic backgrounds a few pixels over a few hours of data capture by the Hubble Space Telescope. The 2013 paper by Jones et. al. infers a z=1.914 redshift type 1a supernova from perhaps 30,000 total photons in two band and 16,000 eV of total energy captured from an entire distant galaxy, with the imputed supernova photons inferred from the difference between brighter and dimmer observations. Subtracting noisy data from other noisy data increases the noise and diminishes the signal, and if the noise model is itself noisy or mathematically inconvenient, the magnitute of the actual signal is quite uncertain.

The rickety ladder of assumptions that leads to this "dim" supernovae is disturbing. The most disturbing assumption to me is that these distant galaxies and their parent clusters are young, perhaps 4 billion years after the big bang. We have no nearby examples of young galaxies to measure with high angular precision. Galactic scale phenomena, such as condensation from the original cloud of hydrogen plasma, may still be underway, and scattering from that thin gas may be why these galaxies are smaller and redder and dimmer. Indeed, off axis gas scattering can stretch the time signal of a pulse by days to months, but the angular distance of that scattered light is much smaller than the resolution of Hubble's cameras.

If we had 1000 times better angular resolution - a launch and giant telescope space assembly problem, not a cosmological problem - we might see that these galaxies are blurred by scattering, and that the pulse from the supernova spreads out as a ring into the still condensing gas around it.

With better measurements of the mass of the down quark, we might learn that USask. Rachid Ouyed's quark-star double pulse supernova model explains many of the supernovae that we lump together as Sn1A. "Classical" Sn1A may also look different from different angles, or in an uncondensed gas cloud. Our own sun formed out of a 9 billion year old gas cloud, triggered by one supernova and seeded by a second one, which provided more of the Al26 radioisotopes that we use to precisely date the solar system, and also add extra heat to the core of the young Earth.

Most scientists prefer "Copernican mediocrity" and statistical averaging for philosophical reasons, but the universe is not governed by philosophy; philosophy that is true and useful should be derived from the observed universe, and evolve as observations accumulate.

Table 12, page 167

Ωb

0.044 ± 0.004

luminous baryons

Ωdm

0.23 ± 0.04

dark matter

ΩM0

0.27 ± 0.04

total mass

ΩΛ

0.73 ± 0.04

dark energy

Ω0

1.02 ± 0.02

relative density (flat)

ΩR

≅ 0

radiation

H0

71 +4/-3

km/s-Mpc

p

≅ 0

pressure from matter and radiation

References

CalibratingCosmos (last edited 2018-01-06 20:50:56 by KeithLofstrom)