This document summarizes Dr. Edmund Schluessel's presentation on alternative cosmological models that could potentially explain the accelerating expansion of the universe without dark energy. Some models discussed include the steady state universe, closed universe, Big Rip, anisotropic cosmologies like the BKL model, Gödel's rotating universe, and electric black holes which could have different internal geometry. While unconventional, these models are still theoretically plausible and worth exploring within the framework of general relativity to better understand dark energy and the early universe.

1. Beyond the Big Bang: Exotic Cosmologies
Edmund Schluessel
Worldcon 75

2. Who am I?
● Dr. Edmund Schluessel
– 2005-2011: Cardiff University
theoretical physics group
● Sathyaprakash’s group:
Gravitational wave detection
● Fred Hoyle: steady-state universe
& panspermia
● Miguel Alcubierre: “warp drive”
– Thesis: “Long-wavelength
gravitational waves and cosmic
acceleration”
http://orca.cf.ac.uk/38028/
● Looking at ways to explain
cosmology without dark energy
– Also attempted short fiction author! io9.com, 27 Sept 2011

3. The conventional wisdom up to 1997
● The universe started with a big bang 15 billion years ago
● Since then it has expanded evenly in all directions (“isotropy”)
● It is filled with basically the same stuff everywhere (“homogeneity”)
● Its geometry is Euclidean (“flat geometry”)
● Expanding in line with Einstein’s theory of general relativity, with no
or quite small cosmological constant (the “CDM” model)
From Universe Today

4. 1998: everything goes to Hell
● Measuring expansion of the universe from distant (500 million light
years+) supernovas (Riess & Perlmutter)
– Universe’s expansion is speeding up – opposite of what CDM says!
● And it’s way too much for a cosmological constant to explain
● COBE satellite: Universe is slightly anisotropic – “pancake” of about 1
part in 100,000
● Turner’s & Riess’s best guess: “dark energy” which is:
– Invisible to light, only interacts by gravity(!)
– “negative energy density” i.e. negative mass(?!)
– 70% of the universe(!!!)

5. Combat the orthodoxy!
● Older models, now considered obsolete but that are still neat ideas
● Weird but still plausible models
● Unlikely models
● Avoiding math as much as possible!

6. The “steady state” cosmology
● Serious competitor to Big Bang – Fred Hoyle, Hermann Bondi,
Thomas Gold, 1949
● Universe “beginning” troubling
● Steady-state fills universe with an energy field, constantly creating
new matter (2 atoms/volume of Mt Everest/year)
● Fred Hoyle, The Black Cloud (1957)
● 1964 – Cosmic microwave background detected – makes Big Bang
more likely

7. The closed universe
● Soviet attitude opposite: universe should have a beginning and an
end
● Universe would someday end in a “big crunch”
● Universe has finite mass
● Perfect 4-dimensional sphere
● Can go around the universe & come
back to where you started!
● Poul Anderson, Tau Zero (1970)
● This model has not been ruled out...
From Adler, Bazin & Schiffer, Introduction to
General Relativity

8. The Big Rip
● The dark energy model has an unknown parameter, w
● If w is less than -1, then space explodes (div-by-zero error in reality)
● Infinitely-increasing anti-gravity makes solar system, planets, atoms
fly apart
● Stephen Baxter, “Last Contact” (2007)
From Caldwell, Kamionkowski & Weinberg, „Phantom
energy & Cosmic Doomsday“ (2003)
Jeremy Teaford, Vanderbilt University

9. The Big Rip, redux
● The Big Rip creates infinite tidal forces...but is it really the end of
spacetime?
● “Kruskal transformation” of coordinates suggests it might not be!
● Raises the possibility of transmitting information out of a doomed
Big Rip universe into whatever comes after, with gravitational waves
● Schluessel, E., “Propagation of gravitational waves in a universe with
slowly-changing equation of state” (2014) ArXiv:1406.4526

10. Anisotropic cosmologies
● What we’ve looked at so far have all been driven by “scalar fields” i.e.
matter & energy (albeit exotic “dark energy”)
● But you can also drive expansion by having gravitational waves built
into spacetime – waves in spacetime itself, frequencies of ~10 billion
years
● With gravitational waves, the expansion cannot be even in all
directions
Vibrating sphere. Russell Herman, UNCWVibrating sphere. Russell Herman, UNCW

11. The BKL cosmology
● Belinsky, Khalatnikov & Lifshitz
● Modification of the closed universe model
● Universe oscillates between “pancake” and “cucumber” shapes, with
cylindrical and disc-shaped “Big Bounces”
● This universe continually renews itself
● Stephen Baxter, Manifold: Time (1999)
● This model can explain “dark energy” and anisotropy, with a bit of
tuning! Also – mixing!

12. The Gödel cosmology
● Kurt Gödel was a brilliant & perverse thinker
● Gödel’s idea: have the universe spin on an axis
ds2 = ½ ω-2[-(dt+exdz)2 + dx2 + dy2 + ½ e2xdz2]
● Space & time get tied up – “inhomogeneous” universe
● If you travel out in space, you eventually arrive back where you
started at a different point in time – possibly in the past
● Stephen Baxter again, The Time Ships (1995)
From Buser, Kajari &
Schleich,
„Visualization of the
Gödel universe“ (2013)

13. Inside a black hole...
● Outside a black hole, the effects are well-known (well, by relativity
standards)
– Space gets stretched out, and people falling in get “spaghettified”
by tides
– But to a distant observer, they’re moving faster and faster until, at
an “event horizon”, they seem to be moving at the speed of light
– Meanwhile, time will seem to slow down (or to the person falling
in, the universe will speed up)

14. ...a whole new universe?
● Go inside a black hole, and it gets weirder
– Time and distance reverse roles – “time” is marked by how far
you are from the center
– The center of the black hole looks like a spindle-shaped “Big
Bang”
– The event horizon looks like a pancake-shaped “Big Rip”
– The universe overall has the geometry of a cylinder
– Alas, it’s always contracting in one direction while it grows in the
others...this can’t represent our universe.
– BUT...

15. Electric Black Holes, Awesome, Right?
● If an ordinary black hole has mass
m then it has an event horizon at
r = 2m from its center
● But if a black hole has mass and
electric charge q, then it has two
event horizons at
(yes, I know, math)
● Think of it like a coconut –
“normal” space outside, “normal”
space inside – and in the “shell” &
“meat”, an area where distance &
time reverse roles...
r=m±√m
2
−q
2
Andrew Hamilton, University of Colorado

16. Maybe we’re over thinking this
● It is – just barely – possible to choose conditions so that a person
living in this “meat” zone sees a universe somewhat like our own
● Still the problem of an asymmetrical Big Bang (this time a pancake)…
● But expansion in all directions, driven by a mysterious field with
what looks like negative energy density!
● Is “dark energy” really just a simple EM field, seen from a different
perspective?

17. Some conclusions
● Everyone scrambling to explain “dark energy” with new physics
● Everything I’ve just talked about is contained in unmodified,
Einstein-classic general relativity
● “Hard” science fiction doesn’t need fictional science (but there’s
nothing wrong with that...)
● Lots of potential in weird corners of what is already established

18. Thank you!
● Questions?
● To contact me:
– Twitter: @stlemur
– E-mail: see me
● These slides available online: