BigBang: Why extrapolate to singularity?

Why not assume a beginning with all the matter being contained in a small but finite volume? The density would be extreme, but not infinite.

I sometimes wonder about the possibility of a beginning with a mixture of matter & antimatter most of which mutually annihilated leaving only normal matter. The energy from the mutual annihilation would fuel the expansion of the remaining normal matter.

The above scenario could have a beginning with the matter & antimatter occupying a large volume of space.​

 

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You may be making the common mistake of thinking that space existed before the Big Bang, and a volume of matter expanded into it like an explosion.

There is a really Big Problem with this scenario: if it's true the universe would look different in different directions. Or alternatively we must be located at the centre of this explosion because the universe does look the same in all directions, and is still expanding away from our location at the same rate in all those directions.

 

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the common mistake is to think the science of cosmology begins and ends with the classical Big Bang theory. And all the goofy interpretations such as the big explosion theory. At this time in modern cosmology inflation theory predicts that the inflation event was the origin of our universe. This event happened to a soliton in a quantum scalar field. This quantum scalar field isn't part of our universe. It's an eternal inflation field. Inflation theory predicts these inflation events are eternal into the future. As far as predictive theories go Inflation Theory makes testable predictions about our actual inflation event. In this respect inflation theory brought cosmology to a testable science. One of the experiments was to examine the CMBR for any evidence that our universe could have 'bumped' with another member of the multiverse. The result was null or inconclusive with a discussion about examining the PLANCK experiment with the greater resolution of the CMBR. Cosmology and gravitational theory are what's been happening the last 30 years. Some of it got famous and some of it gets ignored.

 

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A Singularity need not necessarily imply infinity per se.
The BB Singularity and a BH Singularity occur at the Planck/quantum level where our laws of physics and GR break down or are not applicable.
Remembering that the Planck scale simply is a mathematically derived assumption at which the quantum effects of gravity reign supreme.
In essence then, a future validated QGT may reveal a surface of sorts within this quantum/Planck realm, or it may push our limits of knowledge back a smidgin or two.
As yet we are not sure.

 

From my Post #1

From PaddoBoy Post # 4

All the matter in the universe being contained in a singularity rather than a very small finite volume seems like infinite density to me.

BTW: I wonder why do almost folks assume a singularity at the center of a Black Hole. Why not assume all the matter in a small finite volume? This seems more reasonable to me.

 

You are inferring the classical point Singularity.
I spoke of the quantum/Planck realm at which GR breaks down, and the possibility of a surface existing at somewhere within that region.
Where the laws of physics and GR break down can also be inferred as "Singularity"

For the same reasons as the BB Singularity. Our laws of physics and GR break down at the quantum/Planck level.


http://www.damtp.cam.ac.uk/research/gr/public/bh_hawk.html

Black Holes and Quantum Gravity


Why bother?
Black holes arise in general relativity, a classical theory of gravity. However, we need to include quantum effects to understand black holes properly.

Roger Penrose and Stephen Hawking showed thirty years ago that, according to general relativity, any object that collapses to form a black hole will go on to collapse to a singularity inside the black hole. This means that there are strong gravitational effects on arbitrarily short distance scales inside a black hole. On short distance scales, we certainly need to use a quantum theory to describe the collapsing matter. The presence of a singularity in the classical theory also means that once we go sufficiently far into the black hole, we can no longer predict what will happen. It is hoped that this failure of the classical theory can be cured by quantising gravity as well.

 

because assumptions have a tendency to make an ass out of you. The science of cosmology is beyond such nonsense assumptions.

 

IMHO the correct understanding of GR leads you to a big bang where the whole universe was akin to a frozen-star black hole, and not a point-singularity.

 

Many if not most physicists do. Read the wiki article section on the big bang singularity; it is a short paragraph.

 

Even if one accepts the existence of a yet undiscovered state of matter that would enable frozen stars to exist by preventing gravitational collapse, at the time of the Big Bang there was no matter much less a gravitational collapse, so it seems a wholly inappropriate analogy.

 

It's appropriate because the universe expanding over time can be likened to pulling away from a black hole across space. Google on universe inside-out black hole.

 

So, analogous to the theory of evolution, Big Bang theory doesn't say anything about an initial cause, only what happened after whatever it was (since, logically there must be one).

 

http://newt.phys.unsw.edu.au/einsteinlight/jw/module6_Planck.htm

Except the BB in the first instance, was an evolution of space and time, and at that time in proceedings, it was too hot for any matter to exist at all.

 

BigBang: Why extrapolate to singularity?

It cannot be extrapolated meaningfully ? You can correctly extrapolate only if you know the present (or some point), we do not know the limits of universe or limits of spacetime, so it cannot be traced back to origin. What we are doing is just starting at t = 0, assigning lot of properties even at t = 0, and making furious high end calculations with the help of high speed chips, it may not have any relationship whatsoever with the reality. But this is the best fit model with good number of adjustments.

 

How much hot ? Where did the temperature come from at t = 0 or around that ? You see the temperature is the property of matter, (motion?), (thermodynamics?), if the matter did not exist at all then where did the temperature come from ? This way you are saying that space and time evolved with temperature and (pressure). I have included pressure because the copy paste which you are going to make now will contain that too.

Why this partiality with other physical variables like surface tension, viscosity, humidity etc ?

Please avoid pasting for 'God' sake, just wondering if you follow what you read.

 

Much, much hot.

Temperature is normally described as a measure of the translational kinetic energy of atoms or molecules. In this case though the 'temperature' is referring to the high amount of energy in the volume of space.

Why?

 

What I'm continually wondering is how you manage to survive...period!
I have explained to you many times how cosmology advances from t=0 or more properly t+10-43 seconds. Think the recombination era, 380,000 years post BB approx......Think the first three minutes......
file:///C:/Users/BARRY/Downloads/The+First+Three+Minutes+-+a+modern+view+of+the+origin+of+the+universe+-+S.+Weinberg.pdf
And of course I have posted two excellent tutorials for forumites such as yourself, that are ignorant in cosmology.
Be that as it may, and if that reputable link is too complicated for you, here's another in more simplistic language.........
http://astronomy.swin.edu.au/cosmos/c/cosmology
Cosmology
Cosmology is the study of the nature of the universe as a whole entity. The word cosmology is derived from the Greek kosmos meaning harmony or order. Cosmologists are interested in the formation, evolution and future of the universe and its constituents.

Most objects we can see with telescopes are large or exist at extreme distances (e.g. planets,stars, galaxies, clusters of galaxies and even superclusters). The majority view of cosmologists is that all these objects were formed after an initial, extremely hot and dense formation event, about 14 Gigayears ago, that has created (and continues to create) the space we see around us. This event is called the Big Bang.

Whilst the hot Big Bang model does seem to explain much of what we observe around us, there are still many fundamental questions that exist. What is the majority of the matter in the universe made of? How common are planets around stars? What causes some galaxies to be elliptical, spiral or irregular in shape? What is the geometry of the universe? What is the mysterious dark energy? Is there a cosmological constant? Is it a variable? Do other universes exist?

As well as the properties of the largest objects (e.g. galaxies and large scale structure), cosmology is becoming increasingly concerned with the properties of the smallest objects.

To help determine what happened at the beginning of the universe, cosmologists need the help of particle physicists. The Big Bang model describes a very hot and dense beginning to the universe in which many interesting particle physics phenomena occur. These phenomena have influenced the type of universe we live in.

In the earliest stages the universe was tremendously hot and matter could not exist. The universe was radiation dominated. As the universe expanded and cooled elementary particles could be created, which later formed the lightest elements such as hydrogen, helium and lithium. Heavier elements had to wait for stars to form so that they could be made via nucleosynthesis in the high temperature, pressure and density centres of massive stars.

The Standard Model of particle physics is a mathematical description of the 12 fundamental particles (6 leptons and 6 quarks) and 3 forces (electromagnetic, weak and strong). It is thought that at ~10-11 seconds after the Big Bang all 4 (current epoch) forces (the three mentioned above plus gravity) became separate forces. However at around ~10-43 seconds after the Big Bang (thePlanck Time) all 4 forces were unified into one single force. The process of the forces separating from each other is called spontaneous symmetry breaking.
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Simply put, all reputable links, and even the most basic ones for dummies, show "the god" and his fabricated "Grimm Brothers" view of cosmology, as on the level of a fairy tale. This was highlighted most assuredly with the "Black Neutron Star" paper which has faded into oblivion, and the promised follow up paper which never eventuated.

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Something not touched on yet, in this thread, is the entropy of the early universe. Today this is much higher for the simple reason there is a lot more room for all those particles, and because the early universe was much smoother than today.

Then there's the rule that gravitational potential is negative, which explains why gravitationally collapsed bodies have more (gravitational) entropy than gas and dust clouds. This means black holes are a limiting case (of an increase in gravitational entropy).

But apparently this is all a bit confused or at best unclear, so I've read.

 

Doesn't Inflation explain the low entropy of the early Universe?