The Cosmic Web
Mysterious Architecture of the Universe
J. Richard Gott 2016 Tigard 523.1 GOT
Consider a spherical cow ...
Astrophysicists seek models with a few "universal" parameters, which they fit to the complex (and limited) data they capture with a few dozen large telescopes on Earth and a very few telescopes in orbit. A constrained data set, diligently gathered but biased towards what is easier to observe.
When space access and multilaunch robotic assembly becomes inexpensive, the cheapest place to build and operate telescopes will be in orbit, perhaps around the L2 earth-sun Lagrangian libration point. Most of the mass of a telescope is the primary mirror and its mounting; that can be very light weight in microgravity. How big could that mirror be if fabricated in space, using thousands of tonnes of Earth-sourced materials and equipment produced on Earth, launched to a construction station for a few dollars per kilogram, then transferred to L2?
Imagine hundreds of "cheaper-than-terrestrial" telescopes, sensor/receivers actively cooled below 2.7K deep space, frequently repaired and updated with a steady flow of equipment from Earth, and affordable by modest-sized research teams. What might we see, and be surprised by?
Today, we see tantalizing hints of huge amounts of thin space plasma in filaments between galaxies when we overlay hundreds of images from the Planck space telescope and its 2.2 m² mirror. A single image from a 50 m² (8 meter circular diameter) mirror would provide better information, with less ambiguity; if the mirror was a centimeter-thick low-expansion telescope-grade glass, it would mass 1100 kg. If the entire zero-gee telescope surrounding it massed 18 times as much, it would be 20,000 kg, less than $100K to launch with a $20/MHr launch loop. That mirror would not fit in a rocket fairing, but it could be launched from an 80 km altitude launch loop in a wide flat package, then assembled into a telescope in orbit at a large, permanent construction station.
Even "distant" Earth-Sun L2 is only 1.5e6 kilometers away. A baseline across the Kuiper belt at 67 AU radius would be 2e10 kilometers across. Someday we will do intererometry with large baselines like that.
Thousands of academic departments and many wealthy amateurs could afford the freight costs for their own orbiting 8 meter telescopes. In the long term, the orbiting telescopes will be redesigned, refurbished, and reused in orbit, with old mirrors and structures modified for new uses. A few generations from now, recycled, redesigned orbiting telescopes will explore the sky for anomalies, rather than funded to extend the decimal places on reigning paradigms.
I rather doubt the current "few parameter" models would survive the onslaught of data that hundreds of telescopes like this would produce.
So, what does this have to do with J. Richard Gott's book?
The book is mostly autobiographical, and mentions dozens of papers that Dr. Gott contributed to, and other researchers that he worked with. His method is exploring the 3D macrostructure of visible universe, out to a red shift of perhaps z=0.25, and building huge computer simulations of that universe starting with a "gas" of galaxy-particles. He argues for a "cosmic web" of filaments of galaxies, as opposed to a "swiss cheese" model of disconnected voids in a gas.
Gott spends a lot of pages connecting his models to his prize-winning high school science project about lattices of truncated octahedrons and pseudo-polyhedrons. OK, so the guy is smart and has smart friends. But how about his mistakes? That's what we learn from; our successes can make us afraid to take risks. And how about a little more ink for the differing ideas of his contemporary colleagues?
The last chapter is speculations about the fate of the universe after googleplex-scale years, long after observers have disappeared and speculations can't be tested. This concerns variations of single-parameter dark energy, where w is the ratio of pressure to energy density, presumed to be uniform throughout space and time and approximately equal to -1.
This presumes that there actually is dark energy, rather than some other process making very distant high-z supernovae supernovae appear dimmer than nearby high-z supernovae. This is based on the Phillips relationship, an empirical positive correlation between peak luminosity and luminosity decline time. That's fine for relatively nearby supernovae in a sparse universe with weak gravitational lensing, but in a crowded and dense early universe, light from a supernovae traverses through space with more gravity warping from many less concentrated objects. That will diffuse the light in both space and time, decreasing apparent luminosity and spreading the arrival time of the emitted light, which can take many more and spread-out paths over the Feynman integral. Add a few big-bang-relic micro-blackholes, and there may be many reasons why the light from very distant Sn1a is time-stretched and dim.
All that said, I am probably wrong. What is actually happening will only be apparent after we collect a lot more photons over a much wider spectrum, with much lower noise, much higher angular precision, and from widely spread imagers. We've done a lot with imagers on Earth, in low earth orbit, and a handful at earth-sun L2 ( WMAP, Herschel, Gaia, Planck), with JWST maybe someday (Originally 2007, now planned for March 2021? [announced June 2018] ) I hope.
I am skeptical about universal constants. They are certainly the best models we have, but they are based on observations made from one tiny portion of the universe over a miniscule sliver of time, in a confoundingly intricate universe that hides much from us. We can't even see all the supernovae in our own galaxy, because dust hides most of the galaxy. We shouldn't discard our models, especially on the say-so of unaware dabblers like me, but we shouldn't put them on pedestals either, especially laden with unobservables like "dark" anything. and extra universal "constants" that we only infer because it produces the most symmetrical model. Spherical cows do not produce milk, much less milk in spherical cartons.