# A new model that predicts no Big Bang **URL:** \ **Category:** Factual Questions\ **Created:** [February 10, 2015, 6:36pm UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314 "2015-02-10T18:36:04Z")\ **Posts on this page:** 17\ **Page:** 3
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [February 13, 2015, 2:40am UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/41 "2015-02-13T02:40:34Z")
> [@Chronos](#): > > … in fact, I don’t think that there’s any set of coordinates for the surface of a sphere that doesn’t have at least one coordinate singularity somewhere, even though none of the points is inherently pathological. Certainly not in any kind of Cartesian deformation. But it might be interesting and informative to try to discover a consistent, non-terminal system for graphing the surface of a sphere, or conclusively proving that it is not possible. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 13, 2015, 4:33am UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/42 "2015-02-13T04:33:12Z")
I think it follows from the no-hair theorem. If there were a nonsingular set of coordinates, you could pick one of them, and comb the hair in the coordinate direction. ---
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [February 13, 2015, 2:13pm UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/43 "2015-02-13T14:13:25Z")
> [@Chronos](#): > > I think it follows from the no-hair theorem. If there were a nonsingular set of coordinates, you could pick one of them, and comb the hair in the coordinate direction. I think you mean the Brouwer fixed-point theorem (with its colourful metaphors about porcupines and salon products). ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [February 14, 2015, 6:49pm UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/44 "2015-02-14T18:49:33Z")
> [@MikeS](#): > > To be fair, they don’t dispute these. In their model, the whole Universe was in a hot, dense state at some point nearly fourteen billion years ago, and then it expanded. The difference between this new model and the conventional “Big Bang” model is that in their model, there wasn’t an “initial singularity”, i.e., the Universe was never the size of a point. Why? Because quantum. (At least, that’s my level of understanding for the “why” of it.) > > The only way that this model differs from the conventional model is that it avoids the Universe being infinitely dense and hot at some initial instant. And, to be fair, we’re pretty sure that’s true already; real infinities simply don’t occur in nature, and if you ask 100 physicists whether the density of the Universe was **really** infinite at some initial instant, if they’re being honest they’ll say “probably not; we don’t yet understand how physics works in such circumstances”. Whether this is the correct explanation for how the Universe “avoided” being infinitely dense is another question entirely. This is why we love you around here. And why we’re glad you’re asymptotic and not exponential. > [@Chronos](#): > > Simple example of a coordinate singularity: For (almost) any point on Earth, you can specify its latitude and longitude, and if you change either coordinate, you’re looking at a different point. But what’s the longitude of the North Pole, and where are you if you change your longitude starting from the North Pole? The coordinate system behaves weirdly there. But that’s just a point on the sphere, not inherently any different from any other point on the sphere. Standing at the North Pole, you can step forward, or backwards, or left or right, and it works just like anywhere else on the surface. Latitude and longitude have a coordinate singularity at the North Pole, but not a real singularity. And this is why we love you. But this is the thread winner: > [@leahcim](#): > > Now if they could only find the rest of the Higgs Able Seamen. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [February 14, 2015, 6:54pm UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/45 "2015-02-14T18:54:53Z")
Nitpick: The BBT doesn’t insist that the universe was a single point during the singularity. If it’s infinite now, then it was infinite then too (according to Brian Greene, anyway). The requirement is that density was infinite, so if the universe is finite, then it would also have been infinitesimally small (a point). Of course, the “observable universe” is finite and would have been a single point at that time. You can almost always count on news articles about cosmology to gloss over that point and assume the universe is finite, just to simplify the text. I don’t blame them, but we just have to be careful about extrapolating from what we learn from news articles, or even books by Brian Greene. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [February 14, 2015, 6:57pm UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/46 "2015-02-14T18:57:18Z")
Well crap. I’m going to have to get in the habit of using Preview, because I totally goofed up a quote above. Lemme try that again. > [@Asympotically\_fat](#): > > It’s well-known that altering the equation of state in the early Universe can avoid the big bang singularity - a classic example would be a cosmological model which contracts at a decelerating rate before reaching a finite minimum size and expanding. Classically these models are ruled out by Hawking’s singularity theorem but this is true only if certain energy conditions are true and quantum fields are known to violate energy conditions which are reasonable for classical fields. This is why we love you around here. And why we’re glad you’re asymptotic and not exponential. ---
**Author:** ![Asympotically\_fat](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Asympotically\_fat](https://boards.straightdope.com/u/Asympotically_fat)\ **Post date:** [February 15, 2015, 12:25am UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/47 "2015-02-15T00:25:47Z")
> [@Chronos](#): > > I think it follows from the no-hair theorem. If there were a nonsingular set of coordinates, you could pick one of them, and comb the hair in the coordinate direction. Think of it this way: for any coordinates covering the entire sphere there must be two basis vector fields, however by the hairy ball theorem each basis vector field must be discontinuous or be **0** at some point (and thus not be a basis at that point), meaning the coordinates will always have some form of bad behaviour in the coordinate system. ---
**Author:** ![Asympotically\_fat](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Asympotically\_fat](https://boards.straightdope.com/u/Asympotically_fat)\ **Post date:** [February 15, 2015, 2:10am UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/48 "2015-02-15T02:10:04Z")
> [@Learjeff](#): > > Nitpick: The BBT doesn’t insist that the universe was a single point during the singularity. If it’s infinite now, then it was infinite then too (according to Brian Greene, anyway). The requirement is that density was infinite, so if the universe is finite, then it would also have been infinitesimally small (a point). > > Of course, the “observable universe” is finite and would have been a single point at that time. > > You can almost always count on news articles about cosmology to gloss over that point and assume the universe is finite, just to simplify the text. I don’t blame them, but we just have to be careful about extrapolating from what we learn from news articles, or even books by Brian Greene. The expansion of the observable Universe is not solely due to the expansion of space. If we think of the big bang singularity as being a moment in time, then the observable Universe is like the inside of the [light cone](http://en.wikipedia.org/wiki/Light_cone) of an event at the singularity\* and the light cones of the event always shrinks to a point at the event even when space is not expanding. Now each particle horizon is unique to each observer at rest relative to the CMBR, so from this point of view it seems like the big bang singularity must be made up of multiple events and hence as I said we are specifically viewing it as a moment in time, this suggests it was a moment of time made up of different points in space. This is what I guess Brian Greene means when he says the big bang singularity was not a single point in space. However some care (as always!) is needed. Firstly the above is true wherever there are particle horizons which can exist in both infinite and finite Universes (and will exist for all FLRW cosmologies with realistic parameters), so by the above “argument”, even finite Universes don’t shrink to single points in space at the big bang. However the real problem is that spatial volume(even to the point of being finite/infinite) can’t be really meaningfully defined at the big bang singularity so whether it is finite or infinite in size is moot. In fact it is a little dangerous to think of singularities as being events or sets of events in spacetime at all as at the very least they are places where they don’t obey the rules that we have set down for spacetime. \*This contradicts what I go onto say in the last paragraph about it being dangerous to think of singularities being sets of events. In order not to get bogged down in detail about what I _actually_ mean here, I’ll skip over this point. ---
**Author:** ![Asympotically\_fat](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Asympotically\_fat](https://boards.straightdope.com/u/Asympotically_fat)\ **Post date:** [February 15, 2015, 2:58am UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/49 "2015-02-15T02:58:44Z")
I should’ve made clearer: particle horizon = boundary of the observable Universe. ---
**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\ **Post date:** [February 16, 2015, 2:56am UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/50 "2015-02-16T02:56:13Z")
> [@rsa](#): > > Is this some sort of cyclical universe without the “infinities” of the big bang and big crunch? If not cyclical, why in a universe of infinite age would something special happen about 14 Bya? Sometimes an eternal Universe gets bored. ---
**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\ **Post date:** [February 16, 2015, 2:57am UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/51 "2015-02-16T02:57:14Z")
> [@DrCube](#): > > Black holes occur in nature. Has any stellar object ever been positively identified as one? ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [February 16, 2015, 12:04pm UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/52 "2015-02-16T12:04:31Z")
> [@Asympotically\_fat](#): > > Bohmian mechanics itself is hardly outre, its a well established interpretation of QM and like all of the main interpretations has several desirable features as well as a few not so desirable features Bohmian mechanics is often useful alternative way of viewing quantum mechanical problems for example John Bell was particularly keen on Bohmian mechanics and investigating limitations of hidden variable theorems (like Bohmian mechanics) led him to his famous theorem. The question here is whether Bohmian mechanics has been applied correctly in a relativistic/general relativistic context. Obviously the authors would say yes, but that doesn’t mean everyone would agree. That’s the first thing that jumped out at me, too: what they essentially do is take the paths particles follow in classical general relativits (geodesics) and replace them by the ‘trajectories’ the hidden variables (particle positions) in Bohmian mechanics follow. This is something whose significance is not at all clear to me—basically, that seems to me to be a kind of semiclassical approach (quantum matter on classical spacetime), which I don’t see as being very well founded in regions of size/curvature at or around the big bang. It seems to me that this should be exactly where you’d have to think about bona fide quantum gravity effects. Also, the singularity is avoided basically by dint of the fact that Bohmian trajectories can never cross, and hence, can’t have been ‘all in one place’, so to speak; but that, to me, seems to address a different issue from the physical singularity in big bang models. I’m not sure it’s necessarily the case that even if you can get all matter to avoid one another, the metric doesn’t blow up anywhere. (But maybe the attendant relativists can elaborate on this point…) ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [February 16, 2015, 12:54pm UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/53 "2015-02-16T12:54:00Z")
> [@BrainGlutton](#): > > Has any stellar object ever been positively identified as one? The known object that is most likely to be a black hole is [Sagittarius A\*](http://en.wikipedia.org/wiki/Sagittarius_A*), which is generally accepted to be the black hole at the center of the Milky Way galaxy. Even then, we haven’t actually “seen” the black hole or its accretion disc; the evidence largely stems from the fact that there’s nothing else it could be given its incredibly large mass (4.1 million times that of the sun) and its relatively small size (only 17 times larger than the size of the Sun, if not smaller.) Astronomers have proposed a large-scale project to actually get images of the event horizon; [check back on ten years.](http://eventhorizontelescope.org/index.html) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 16, 2015, 3:53pm UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/54 "2015-02-16T15:53:12Z")
…And I just realized that I earlier typed “no-hair theorem” when I meant “hairy ball theorem”. And **Asymptotically Fat** either made the same mistake I did when he read it, or he recognized my mistake and managed to figure out what I meant anyway. For reference, the “hairy ball theorem” is that you can’t comb a hairy ball smooth (there must be some point that has a whorl or a cowlick or a bald spot), while the “no-hair theorem” basically says that black holes are really boring, and can’t have most of the properties that other objects have. ---
**Author:** ![Asympotically\_fat](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Asympotically\_fat](https://boards.straightdope.com/u/Asympotically_fat)\ **Post date:** [February 16, 2015, 9:40pm UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/55 "2015-02-16T21:40:20Z")
> [@Half\_Man\_Half\_Wit](#): > > That’s the first thing that jumped out at me, too: what they essentially do is take the paths particles follow in classical general relativits (geodesics) and replace them by the ‘trajectories’ the hidden variables (particle positions) in Bohmian mechanics follow. This is something whose significance is not at all clear to me—basically, that seems to me to be a kind of semiclassical approach (quantum matter on classical spacetime), which I don’t see as being very well founded in regions of size/curvature at or around the big bang. It seems to me that this should be exactly where you’d have to think about bona fide quantum gravity effects. This is a point I must say struck me too: approximating quantum gravity as a correction to classical physics will surely have a limit and that limit would seemingly be reached in the very early Universe. > [@](#): > > Also, the singularity is avoided basically by dint of the fact that Bohmian trajectories can never cross, and hence, can’t have been ‘all in one place’, so to speak; but that, to me, seems to address a different issue from the physical singularity in big bang models. I’m not sure it’s necessarily the case that even if you can get all matter to avoid one another, the metric doesn’t blow up anywhere. (But maybe the attendant relativists can elaborate on this point…) It’s a little complicated, but an essential element to Hawking’s singularity theorem(s) is that two arbitrarily-close past-directed timelike geodesics originating at some event A will intersect at some finite proper time. This can be shown to happen when certain energy conditions are obeyed. The other element is that when certain causality conditions are obeyed this can be shown to lead to geodesic incompleteness and, depending on how strict your conditions are, that all past-directed timelike curves originating on some spatial slice have a proper time which is less than or equal to some finite maximum. These ideas are in many ways stronger than whether the metric blows up anywhere and indeed the actual proofs offer no clues as to where the metric might blow up if at all it does blow up. If the congruences of geodesics that intersect and form the essential element of the proof of Hawking’s singularity theorem are replaced by congruences of geodesics that don’t cross, then the singualrity theorem doesn’t apply (that of course doesn’t prove there aren’t singularities of any type, but I don’t think that would necessary). However to me saying that for particle trajectories, the classical geodesics are replaced by Bohmian trajectories doesn’t mean that necessarily the singularity theorem would still not apply to the background spacetime. ---
**Author:** ![Asympotically\_fat](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Asympotically\_fat](https://boards.straightdope.com/u/Asympotically_fat)\ **Post date:** [February 16, 2015, 9:50pm UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/56 "2015-02-16T21:50:51Z")
> [@Chronos](#): > > …And I just realized that I earlier typed “no-hair theorem” when I meant “hairy ball theorem”. And **Asymptotically Fat** either made the same mistake I did when he read it, or he recognized my mistake and managed to figure out what I meant anyway. > > For reference, the “hairy ball theorem” is that you can’t comb a hairy ball smooth (there must be some point that has a whorl or a cowlick or a bald spot), while the “no-hair theorem” basically says that black holes are really boring, and can’t have most of the properties that other objects have. I actually thought of the point I made before I read you post, so it was very clear what you meant, but I did notice your mistake, but I didn’t bother pointing it out:D ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [February 18, 2015, 10:25pm UTC](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314/57 "2015-02-18T22:25:07Z")
> [@BrainGlutton](#): > > Sometimes an eternal Universe gets bored. So that must explain the black holes. [Previous page](https://boards.straightdope.com/t/a-new-model-that-predicts-no-big-bang/712314.md?page=2)