The Big Bang: Was there a singularity?

[Sorcerer]

When Hubble first observed the expansion of the universe, the obvious conclusion was that if we extrapolate backwards, there was a point in time where the size of space was 0.

Now we have observed that space is expanding at an accelerating rate.

If we visualise the graphs of these two, with time being the x axis and the 3 dimensions of space's size being the y axis. In the uniform expansion model the graph is linear with a 1:1 gradient and neatly crossing the origin.

But, if we visualise this graph by extrapolating backwards from a universe with accelerating expansion, the line forms an asymptote with the x axis pushing the origin back to infinity.

So how can there have been a singularity? Or how can the universe be finite in age?

Edited March 12, 2015 by Sorcerer

[Strange]

I don't think many people think the singularity was a physical "thing". We need a theory of quantum gravity to better understand what happened in the early universe.

 

Here is one attempt to address the question: https://briankoberlein.com/2015/02/10/beginning/

[Sorcerer]

I thought the obvious hypothesis would be that at some point in size of the universe's gravity over comes expansion and then it collapses into a singularity. However then if the accelerating expansion we observe today isn't uniform, how can we say we are a typical observer, the typical observer back then wouldn't have observed anything like this, it would have been infinitely accelerating.

But yes what you linked is another solution/hypothesis that works.

However how can the universe be infinitely old and the 2nd law of thermodynamics be true? Wouldn't we currently be experiencing "Heat Death".

Ok, so I'm not an expert at all, but I've read if a distant observer viewed an object falling into a singularity, it would never acutally see it cross the event horizon. What if we took this idea as we looked back in time towards the initial singularity, the entire universe being the observer of the past would never actually see itself reach the origin? Does that make any sense?

Edited March 12, 2015 by Sorcerer

[Strange]

Ok, so I'm not an expert at all, but I've read if a distant observer viewed an object falling into a singularity, it would never acutally see it cross the event horizon.

 

This is not quite true. You wouldn't see it cross the event horizon, but you would see it disappear. And, as far as I know, there is no event horizon associated with the big bang singularity.

[Sorcerer]

Isn't it the horizon of all events?

What happens if we look the other way towards the future? (sorry completely offtopic)

Edited March 12, 2015 by Sorcerer

[Strange]

Isn't it the horizon of all events?

 

Sorry, I'm not sure what you are asking...

 

 

What happens if we look the other way towards the future? (sorry completely offtopic)

 

There is only a singularity in the future of the universe if it collapses again and, as you say, the observed acceleration seems to make that unlikely.

 

Interestingly, when you fall through the event horizon of a black hole, the singularity (which, again, probably isn't a "thing") changes from being in front of you, to being in your future.

[Sorcerer]

Feel free to edit the wiki http://en.wikipedia.org/wiki/Event_horizon#Interacting_with_an_event_horizon

[Strange]

Feel free to edit the wiki http://en.wikipedia.org/wiki/Event_horizon#Interacting_with_an_event_horizon

 

What needs editing?

[Sorcerer]

Well I'm trying to envisage a singularity in the past, singularities in the present (if they exist) follow these rules, observing something in space is the same as observing something in time. So if we look back towards a singularity at the beggining of our universe we would see an event horizon and we would see everything stretched towards it infinitely. Where did I go wrong?

[Strange]

Well I'm trying to envisage a singularity in the past, singularities in the present (if they exist) follow these rules, observing something in space is the same as observing something in time. So if we look back towards a singularity at the beggining of our universe we would see an event horizon and we would see everything stretched towards it infinitely. Where did I go wrong?

 

I don't think there is a requirement for all singularities to have an event horizon. And not all event horizons are associated with a singularity; for example the event horizon seen by an accelerating observer. But I may very well be wrong.

 

In fact, there is an event horizon for the observable universe (the largest distance from which light emitted now can ever reach the observer in the future) - but we are "inside" that horizon.

Edited March 12, 2015 by Strange

[Mordred]

Singularity has two meanings in science, one is the point like BH, the other is singularity conditions, This can mean a condition that the maths and physics no longer makes sense. Ie infinities. The T=0 point like descriptive is just our observable portion of our observable universe. We do not know if the universe is finite or infinite. A finite beginning cannot become infinite in volume. So if it's finite in the past, it's finite now and vise versa

[MigL]

There is a requirement for singularities to have a horizon. 'Naked' singularities are not allowed.

However the BB singularity ( if there was one ) could be different as there is no 'outside' to shield it from.

 

That being said, Sorcerer, if we look back into the past expecting to see the event horizon of the BB singularity, we would be 'outside' the universe. This is an impossibility as the BB singularity and its attendant horizon is what expanded to become the universe.

[John]

But, if we visualise this graph by extrapolating backwards from a universe with accelerating expansion, the line forms an asymptote with the x axis pushing the origin back to infinity.

 

So how can there have been a singularity? Or how can the universe be finite in age?

Others with greater knowledge of cosmology have provided good information, but I'd like to chime in here to say this reasoning is a bit flawed, in a sense seemingly similar to that employed by Zeno in his paradoxes.

 

As a counterexample, consider the graph of y = x², and imagine we're living on the curve at the point (100, 10000). Observations made at various points on the curve will show us that y is growing, and the growth is accelerating, but looking back to x = 0 (assuming we can), we'll see that y = 0 as well, and furthermore, this point is a finite distance (100 units) away along the x axis. That is to say, accelerating expansion does not imply that the size of the universe was never zero (though other physical considerations may).

 

Of course, I may have misunderstood your post. In that case, disregard.

Edited March 13, 2015 by John

[Brad Watson_Miami FL]

Sorcerer and everyone,

 

"The Big Bang (supermassive white hole) ~13.82 billion years ago was the result of a supermassive black hole in another universe. Our universe & that SBH share the same event horizon. That SBH & SWH formed an Einstein-Rosen bridge (wormhole). This duality combines these two singularities in a birth-life-death-rebirth cycle within The Conglomerate of nonparallel-universes (multiverse). This 'simple' cause-and-effect explains both infinite space and eternity. Self-replication is the simplest plan for everything from a cell to a universe to a mind."


Note to moderator: I AM not "trying to hijack this thread". I AM replying to the op with the truth in a quote.

[Strange]

I AM replying to the op with the truth in a quote.

 

Putting something you made up inside quotation marks does not make it true.

[Mordred]

That's not the truth, that is one of numerous models one without supporting evidence. We have zero zip evidence of a multiverse. We have zero zip evidence of a rotating universe which is one of the consequences of that model.

 

No matter how slow a rotation you cannot maintain a homogeneous and isotropic universe. So observation evidence doesn't support the above model.

 

This forum is specifically for mainstream questions and answers. What one would find in a textbook for example.

 

The model you presented has been considered before it is not a unique idea. However no study has been able to support it. A universe forming from a wormhole has a preferred direction. Black holes rotate that rotation will impart its rotation upon ours. Measurements show no rotation.

 

Poplowskii tried this model for years its still has not gained mainstream acceptance. Last I checked he is now trying an ADS/CFT approach.

Edited March 13, 2015 by Mordred

[imatfaal]

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Moderator Note

 

BradWatson

 

Whilst you might not have been trying to hijack you were most certainly were hijacking. Do not do so again.

 

Can we stop discussing the branch - I think there is already a thread in Specs.

 

Responses to threads should never include your own speculative material. Threads on the main boards are for discussion of accepted science and those hypotheses that are receiving academic examination. Threads in Speculations are for the OP to explain, enlarge, defend their own idea - not for the promotion of other Speculations.

 

Do not respond to this moderation

 

[Phi for All]

Note to moderator: I AM not "trying to hijack this thread". I AM replying to the op with the truth in a quote.

 

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Moderator Note

The only truth I see is that you have no idea why it's wrong to post untried, untested speculation in a section that students trust to be mainstream science. You also see nothing wrong with trying to make every discussion about your idea. You exhibit an extremely selfish and self-promoting behavior that is anathema to productive, meaningful science discussion. It's not going to be tolerated any longer. Please stop.