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A Big Bounce After All?

If anything ever seemed completely unknowable, it’s the answer to the question of what existed ‘before’ the Big Bang. But it’s an issue laden with unusual interest. If a previous universe collapsed in a ‘Big Crunch,’ will that somehow become the fate of our own? Now a research team working under Martin Bojowald (Pennsylvania State) is developing its own answers to these questions, relying on the theory known as quantum loop gravity.

The grand goal of unifying Einstein’s General Relativity with the perplexing world of quantum mechanics is necessary but highly elusive. We need some way to look at the all but inconceivable energies that must have dominated the universe in its earliest period. And if you accept the idea that quantum loop gravity can do the job (it flows out of Penn State’s Institute for Gravitational Physics and Geometry), then the Big Bang doesn’t close off all knowledge of what went before.

Bojowald and team talk about the ‘Big Bounce,’ a time when gravity becomes so strongly repulsive that it forces the universe into a new expansion. In their view, the ‘Big Bounce’ replaces the classical idea of the Big Bang as the beginning of our universe. As I read what’s coming out of Penn State, that means that the universe before the ‘Bounce’ was contracting, and according to the quantum loop equations, had a space-time geometry not dissimilar from what we see around us today.

Though not exactly. I’m going to turn you over to the news release on Bojowald’s work, but I do want to quote this paragraph from it:

Bojowald reached an additional conclusion after finding that at least one of the parameters of the previous universe did not survive its trip through the Big Bounce — that successive universes likely will not be perfect replicas of each other. He said, “the eternal recurrence of absolutely identical universes would seem to be prevented by the apparent existence of an intrinsic cosmic forgetfulness.”

Lively stuff. Even if quantum loop gravity does provide a window into a previous universe, it’s one that will always leave us uncertain about some of that universe’s properties. But Bojowald will argue, unlike Einstein, that the beginning of the universe had a minimum volume that is not zero, and a maximum energy that is not infinite. That keeps the mathematics alive at a point where General Relativity could not proceed and yields Bojowald’s controversial results.

The Bojowald paper appeared in the online edition of Nature Physics on July 1, with the print edition to follow in August. If you’re interested in following this work, be aware too of Bojowald’s “The Dark Side of a Patchwork Universe” (abstract available), which ties the question of dark energy in with quantum loop gravity and explores implications of the connection.

Cosmology at this level is well beyond my powers, but I’m reminded happily of Poul Anderson’s Tau Zero, the wonderful 1970 novel of a runaway starship moving ever closer to c. The story concludes with the vehicle actually surviving a Big Bounce event to punch through into a new universe. For old time’s sake, here’s a bit of the transition:

The screen blanked. An instant later, every fluoropanel in the ship turned simultaneously ultraviolet and infrared, and blackness plunged down. Those who lay harnessed alone, throughout the hull, heard invisible lightnings walk the corridors. Those in command bridge, pilot bridge, engine room, who manned the ship, felt a heaviness greater than planets — they could not move, nor stop a movement once begun — and then felt a lightness such that their bodies began to shake asunder — and this was a change in inertia itself, in every constant of nature as space-time-matter-energy underwent its ultimate convulsion — for a moment infinitesimal and infinite, man, women, child, ship and death were one.

It passed, so swiftly that they could not tell if it had been. Light came back, and outside vision. The storms grew fiercer. But now through it, seen distorted so that they appeared to be blue-white firedrops that broke into sparks as they flew, fountaining off in two huge curving sheets, now came the nascent galaxies…

Implausible doesn’t even begin to describe it, but what a tale…

Comments on this entry are closed.

  • boomslang July 4, 2007, 12:48

    There’s a very serious problem for “cyclic universe” cosmology which physicists invariably completely overlook: it is logically impossible for the past to be infinite, for if the past truly is infinite, then not enough time will ever have elapsed in order to permit the observed present moment to obtain.

    The math and QM behind this new theory may be informative, but the overall concept of constant Cosmic Bouncing ultimately inductively self-contradicts… you can have only a finite series of previous Bounces, which is not a parsimonious model.

  • A Babe in the Universe July 4, 2007, 14:56

    All us cosmologists have stong ideas about how the Universe works, but that’s the way the ball bounces. Since you enjoy space technology, I hope you like the July 4 post.

  • JD July 4, 2007, 20:20

    Nothing is proven or dis proven. Anyone taking any stance will probably be embarrassed in the future. I remember in the early days of big bang theory there were supposed scientists stating that the bang happened, there was nothing before and this is all there is in a medium of infinite size and duration. Ooooookkaayy and does that come with oceanfront property in Kansas?

    It is entertaining though, watching the various groups trying to push their theories forward. I’m laying long odds on the woman mathematician (can’t remember her name) from Harvard that postulated 21 (?) dimensions etc. . If we’re gonna be convoluted and esoterical let’s go all out:)

  • Adam July 5, 2007, 3:56

    Hi JD

    Are you thinking of Lisa Randall? She has been working on “brane theory” – the idea that the Standard Model fields (EM, Weak and Strong Nuclear) are confined to a 3-D brane in a 4-D hyperspace, while gravity isn’t confined, and so much weaker.

  • Eric James July 5, 2007, 3:57

    Tau Zero was a fun read. I remember it still (even though I haven’t read it in at least 20 years!). It had quite an effect upon my concept of the universe. It seems a logical consequence. If matter and energy can neither be created or destroyed, it seems the only logical alternative is for it to recycle.

    Of course it can’t be proven that matter and energy can’t be created or destroyed in a proto-universe or universe bounce, but it makes sense to me that the quantities of matter and energy must meet a particular mark in order for the universe to exist at all (as we know it).

  • JD July 5, 2007, 15:28


    A good possibility, I must confess my memory is atrocious these days (maybe I can sue the military for cumulative degeneration of my synaptic relays via concussive forces, nah I had to much fun doing it :)

    Any theory of the cosmos which doesn’t address infinity is a non starter in my own opinion. The gentleman from MIT (once again my memory for names truly sucketh) who proposed the four tier system of possible multiverses struck me as having a good theory.

    As far as the various mutations of string/brane I try to read up occasionally to see where it’s going. As I remember there’s at least one brane scenario that addresses an infinite multiverse through the use of higher dimensions. Some of the basic concepts seem to have merit yet appear currently unverifiable. As it stands now even Anderson’s enjoyable tale has just as much actual plausibility as current theories.

  • Paul Dietz July 6, 2007, 13:55

    One problem with the cyclic universe is the second law of thermodynamics. Entropy is constantly being created in our universe, so it can’t be reset to the same initial state without violating this law. Any cyclic theory has to explain where this entropy goes.

  • Adam July 6, 2007, 21:36

    Hi Paul & JD

    Entropy is based on the microstates of any physical system. The information paradox of black hole physics is partly that all that information is destroyed in a singularity – the states become indistinguishable as a singular state and thus effectively “cancelled”. This could happen in a Big Crunch, but that would imply that NO information survives between cycles of the Universe and thus there’s no reason to say it is the same universe born in the next Big Bang.

    JD, Poul Anderson knew the physics of his story was hokey, but it was necessary for the plot. For the ramship to survive the mass of the Universe collapses into a black-hole, but the space-time it is in remains uncollapsed and the black-hole has an ergosphere due to cosmic rotation. In a proper Big Crunch there is no external void – space-time is coextensive with the mass it contains – and thus no ergosphere to survive the Big Crunch in. Good fiction, but creative license for the physics.

  • JD July 9, 2007, 16:33


    Yes, quite true. In my untrained, infantile way I’m simply trying to make the point that the whole area of speculation is far from settled.

    Another point I was attempting to make is how unsatisfying most theories are. The majority seem to say that since the CBR is vaguely discernible our universe is ~35 bly’s in diameter and that’s all, nothing else, zip, nada. While trying to visualize our universe is difficult the concept of all of infinity being summed up inside this bubble is even harder to visualize.

    Some theories do try to address this. Of note the one postulating infinite numbers of various branes within a matrix of higher dimensions. I might add this theory has a universe/brane creation method without a proper big bang, though of course there’s no proper collapse/rebound method either.

    Oh well enough. I’m getting dangerously close to, what is for me, philosophy. Dabbling in philosophy without adequate facilities nearby for immediate hygienic sanitation philosophy is unbearable.

  • ljk July 26, 2007, 9:55

    Before the Big Bang – July 21, 2007

    An excerpt from a talk given by Roger Penrose on his theory
    for what existed, or what happened, before the Big Bang. He
    describes the massive time scales involved as black holes
    eventually explode. He was speaking at a conference in Sydney.


  • J Clarkson October 25, 2007, 8:28

    I think that this theory has the most merit so far, as it appears to explain an number of inconsistencies with classical Big Bang theory. Let’s say this is the correct theory, and that there are also an infinite number of parallel universes (as Deutsch suggests). Think about that for a moment. An infinite number of previous and present parallel universe. A Multiverse, without end or beginning. Now, that would explain our existence. It might also allow God to peek into the scene, for surely at least one universe will produce a being that could survive the death of its own universe, and ‘know’ everything. We are like ants sailing on leaves trying to imagine New York and the human world, when we delve into these matters. People who say that science alone has the answers, have little imagination. Science is just the best tool to know our little leaf. We know nothing about the entire picture, and probably never will. What then of the human mind, the most complex thing we know about in this universe? If such complexity can be created here, then nothing is impossibile. There must be greater beings than us somewhere. Of course it could all be mathematical mumbo jumbo, and if so, then we can forget my high thoughts. Lets see what Planck produces…

  • Rob MacRiner November 13, 2007, 15:26

    Rob MacRiner rmacriner@sympatico.ca , robmacriner@hotmail.com

    Answer to Question: Why does time seem to exist only in a forward direction?

    Time seems to only exist in a forward direction because the universe is expanding. If the Universe reaches Critical Velocity and starts to contract ….then time, as we measure time will reverse according to the Big Bang / Big Crunch Theory. The reason for this is that time does not exist without change or movement….. (change or movement of particle matter or energy as we know it). If matter has no movement either expanding or contracting then time does not exit for that matter. However Time can exist around non moving particle matter if something is either expanding or contracting around it.

    If the expansion of matter increases as in the case of our universe, or an expanding object, or even light…then time increases relative to the rate of expansion. Example: if carbon A is heated and expands faster than carbon B (which is not heated) then time increases in carbon A relative to carbon B…However as Einstein pointed out…time is relative to the observer…and you need something of contrast to make that comparison….fortunately our universe offers lots of contrast …otherwise we would have a very difficult time figuring this out. Time being relative to the observer can exist at different speeds based on the rate of expanding matter. If you are on riding on a beam of light than time is much different than your friend riding on a sound wave. Of course time is relative to the observer, therefore your time is much faster only to him, or any body else who is not on a beam of light.

    If matter contracts or condenses then time actually reverses…as in the case of a contracting universe…so Planks Quantum would be measured as zero time for the entire Universe…and time starts at the point of the Big Bang (once matter is on the move again)… In the case of a Black Hole, relative to our expanding universe)… there is also no time. (except for matter being sucked into a Black Hole….this matter would be reversing in time, until at which point it becomes part of the Black Hole mass, then time (in a Black Hole) as in Planks Quantum is zero….which is odd because the Universe is still expanding around the Black Hole…but it is consistent with the theory that. Time can exist around “non moving matter” if something is either expanding or contracting

    Time as we know it is measured in a forward direction and will continue until the point of critical velocity…at which point time starts to reverse…and for a brief moment…the point where the Universe changes from expanding to contracting…time will again be zero…as in Planks Quantum. However…during the forward direction of time…(while the Universe is expanding)…Black Holes are continuing to suck up matter…and should in theory at some point converge with other Black Holes….Therefore…as the universe is expanding from the Big Bang…there is multitude of matter which is not expanding (Black Holes)…which might well be unexploded Planks Quantum matter from the Big Bang…and the Black Holes with their massive gravitational force are sucking up matter which was attempting to expand but was not able to overcome the stronger force of the Black Hole…like mini-Plank Quantum’s converging within the universe …When the Universe reaches Critical Velocity and then all matter in our Universe starts to contract…heading towards the Big Crunch….the multitude of Black Holes converging (up to that point) should in theory rapidly increase the speed of reverse time …acting as an accelerant force of a contracting Universe with their collective gravitational force …So the reverse of time.(the journey the contracting Universe is taking towards the Big Crunch)…should happen much quicker than the time it took for the Universe to go from the Big Bang to Critical Velocity…That is of course Time relative from the Big Bang to Critical Velocity ……in contrast to …….Time Relative from Critical Velocity to the Big Crunch. Mathematically it might be possible to estimate this time.… Rob MacRiner rmacriner@sympatico.ca Nov 2007

  • ljk November 29, 2007, 13:31

    Tape shows how physicist predicted parallel worlds

    From The Guardian, Nov. 26, 2007

    The only known recordings of a brilliant physicist who predicted the existence of parallel universes have been found in the basement of his rock star son’s flat.

    The tapes document how Hugh Everett, a quantum physicist, developed his idea at the age of 24, while a graduate student at Princeton University in 1957. Everett’s theory gave rise to the concept of a multitude of universes, or a “multiverse”, where all life’s possibilities play out. It means that somewhere Elvis is still rocking, the Nazis won the second world war and England qualified for Euro 2008.

    Full article here:


    There is a bio on Hugh Everett in the December issue of Scientific American
    magazine, but it is not free online:


  • ljk January 10, 2008, 15:38

    Emergence of a Big Bang singularity in an exact string background

    Authors: Shinji Hirano, Anupam Mazumdar

    (Submitted on 17 Dec 2007)

    Abstract: The origin of Big Bang singularity in 3+1 dimensions can be understood in an exact string theory background obtained by an analytic continuation of a cigar like geometry with a nontrivial dilaton. In a T-dual conformal field theory picture there exists a closed string tachyon potential which excises the singular space-time of a strongly coupled regime to ensure that a higher dimensional universe has no curvature singularity. However in 3+1 dimensions the universe exhibits all the pathology of a standard Big Bang cosmology.

    The emergence of a singularity now owes to a higher dimensional orbifold singularity which does not have a curvature singularity in higher dimensions, suggesting that close to the compactification scale an effective description of 3+1 dimensions breaks down and bouncing universe emerges in 5 and higher dimensions.

    Comments: 4 pages, 1 figure

    Subjects: High Energy Physics – Theory (hep-th); Astrophysics (astro-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics – Phenomenology (hep-ph)

    Cite as: arXiv:0712.2777v1 [hep-th]

    Submission history

    From: Anupam Mazumdar [view email]

    [v1] Mon, 17 Dec 2007 17:11:25 GMT (13kb)


  • ljk January 18, 2008, 10:49

    Ekpyrotic cosmology resurfaces

    Alternative theory to Big Bang resolves teething problems


  • ljk February 20, 2008, 11:16

    The Phantom Bounce: A New Proposal for an Oscillating Cosmology

    Authors: Katherine Freese, Matthew G. Brown, William H. Kinney

    (Submitted on 19 Feb 2008)

    Abstract: An oscillating universe cycles through a series of expansions and contractions. We propose a model in which “phantom” energy with a supernegative pressure ($p less than – \rho$) grows rapidly and dominates the late-time expanding phase. The universe’s energy density is then so large that the effects of quantum gravity are important at both the beginning and the end of each expansion (or contraction). The bounce can be caused by high energy modifications to the Friedmann equation governing the expansion of the universe, which make the cosmology nonsingular. The classic black hole overproduction of oscillating universes is resolved due to their destruction by the phantom energy.

    Comments: New York Academy of Sciences Proceedings, Origins of Time’s Arrow Conference, October 2007

    Subjects: Astrophysics (astro-ph)

    Cite as: arXiv:0802.2583v1 [astro-ph]

    Submission history

    From: Katie Freese [view email]

    [v1] Tue, 19 Feb 2008 03:57:20 GMT (23kb)


  • ljk March 28, 2008, 16:22

    Was There A Big Bang?

    Authors: Robert K. Soberman, Maurice Dubin

    (Submitted on 25 Mar 2008)

    Abstract: The big bang hypothesis is widely accepted despite numerous physics conflicts. It rests upon two experimental supports, galactic red shift and the cosmic microwave background. Both are produced by dark matter, shown here to be hydrogen dominated aggregates with a few percent of helium nodules. Scattering from these non-radiating intergalactic masses produce a red shift that normally correlates with distance. Warmed by our galaxy to an Eigenvalue of 2.735 K, drawn near the Earth, these bodies, kept cold by ablation, resonance radiate the Planckian microwave signal. Several tests are proposed that will distinguish between this model and the big bang.

    Comments: 9 pages, 4 figures

    Subjects: General Physics (physics.gen-ph)

    Cite as: arXiv:0803.3604v1 [physics.gen-ph]

    Submission history

    From: Robert K. Soberman [view email]

    [v1] Tue, 25 Mar 2008 18:30:23 GMT (325kb)


  • Adam March 29, 2008, 5:13

    Physics conflicts? It conflicts with philosophical prejudices against a beginning to time, but the Big Bang is the end-result of physics, not in conflict with it. it’s a generic prediction of General Relativity and doesn’t conflict with anything in physics, just a certain distaste of singularities.

    However intergalactic gas clouds are rather visible and would’ve been noticed by now because of their absorbing properties – unless they’re magic gas clouds… but that’d conflict with physics wouldn’t it?

  • andy March 29, 2008, 8:07

    Another problem with that idea is that gas clouds tend to do interesting things when they crash into each other (e.g. trigger star formation, give off lots of radiation), which is contrary to the observations of dark matter, which seems to be for the most part non-interacting.

  • Adam March 29, 2008, 16:07

    Hi andy

    Have you read the paper yet? It’s just a preprint submission, not a submission to a journal – I can’t imagine it’d survive a peer-review savaging because their claims are rather outrageous – that the solid hydrogen clusters have been observed as a certain class of meteor and the micrometeoroid counts of Pioneer X and XI were due to the “cosmoids”.

    Still instead of the usual anti-Big Bang rant they’ve proposed a couple of observational texts, that the CMB should be invisible out past ~ 3.5 AU and that deep space probes in a certain configuration should show a measurable red shift. I have a sneaky feeling the density of baryonic matter they’ve imagined is liable to cause Jeans collapse all over the place, but I have to do the numbers to be sure.

  • ljk April 10, 2008, 9:33

    Before the Big Bang: A Twin Universe?

    PhysOrg.com April 9, 2008

    The universe that came before ours
    was its identical twin, a new study
    by Alejandro Corichi from
    Universidad Nacional Autonoma de
    Mexico and Parampreet Singh from the
    Perimeter Institute for Theoretical
    Physics suggests. Since the
    pre-bounce universe is contracting,
    it will look as if we were looking
    at ours backward in time….


  • ljk June 20, 2008, 17:12

    Big rip avoidance via black holes production

    Authors: Julio C. Fabris, Diego Pavon

    (Submitted on 16 Jun 2008)

    Abstract: We consider a cosmological scenario in which the expansion of the Universe is dominated by phantom dark energy and black holes which condense out of the latter component. The mass of black holes decreases via Hawking evaporation and by accretion of phantom fluid but new black holes arise continuously whence the overall evolution can be rather complex. We study the corresponding dynamical system to unravel this evolution and single out scenarios where the big rip singularity does not occur.

    Comments: 15 pages, two figures. Key words. Cosmology, phantom energy, black holes

    Subjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics
    (astro-ph); High Energy Physics – Phenomenology (hep-ph); High Energy Physics – Theory (hep-th)

    Cite as: arXiv:0806.2521v1 [gr-qc]

    Submission history

    From: Diego Pavon [view email]

    [v1] Mon, 16 Jun 2008 08:30:49 GMT (44kb)


  • bob conrad February 25, 2009, 18:47

    I am a mere layman; not a physicist or mathematician, nor am I a college trained theorist by any means. I have had a lifetime interest in anything space related, have studied and otherwise educated myself in the field; possibly I’ve seen too many episodes of Star Trek, granted. I do maybe have some interesting, though not entirely original, hypotheses concerning the universe, its beginning and future, which I’m sure can (and will) be explained away by the “professionals”, but I’m going to post anyway!
    Perhaps the “Big Bang” has never stopped “banging”! Maybe it is the “outlet” of a “white hole” somehow, and has been expelling recombinant matter since the “beginning of time”. The material would eventually, ultimately, be taken up by a “black hole” (The “Elemental Particle”) and the cycle repeats over and over and…
    Perhaps this could explain the “Missing Matter” in the universe, without having to rely on undetectable, unprovable “Dark Matter”, or “Dark Energy”, and could explain the increasing acceleration and expansion of the universe (WHAT are we accelerating toward, or from???!!!)
    Please explain to me, you experts and professionals, why this is not possible; but PLEASE do it gently– I may be stupid, but I ain’t dumb, I may be ignorant, but I’m trying to educate and enlighten myself. Respectfully, I thank you, Bob Conrad