Singularities and beginning of the universe

[David T]

It seems the most important application of electro dynamic studies over the last century is the atomic bomb and internet porn at 4 glte!! Btw the inatant tendency of this field of study in is it's tendency towards TOE is rather laughable very christian in that regards not surprisingly.

 

[Polymath257]

Thanks a lot. I am not entirely sure what the various R2 or flat top models are.

OK. In your description above, you used the analogy where the potential looks like an English tophat. The quartic hilltop model is a particular case of this. Essentially, if you graph y=1-x^2 and compare to y=1-x^4, the latter is more flat at x=0 than the former. It is a quartic (degree 4) hilltop.

The 'potential' in all of these measures the amount of energy for various strengths of the inflaton field. As in your description above, inflation requires a large value for zero field strength and a smaller value as we move away from zero.

The various potentials just are different mathematical ways to accomplish this that are motivated by other physics.

Most of the models for inflation do not focus on identifying the inflaton, but merely describing its properties.

The R^2 model adds another term to the Lagrangian for gravity. Such additions have been proposed independently of this, so it isn't an unreasonable thing to pursue. In this, there is not a new particle, just an adjustment to how gravity works at large field strengths. But it does give a period of inflation and allows reheating in a natural way (so that inflation is stopped).

Another good source of information:
http://pdg.lbl.gov/2016/reviews/rpp2016-rev-inflation.pdf

 

[questfortruth]

....
Much of the material comes from reading John Barrows "Book of universes" and associated papers.

Please help to publish:

 

[Polymath257]

Please help to publish:

Well, that was wasted time.

 

[questfortruth]

Well, that was wasted time.

Prove it.

 

[Polymath257]

Prove it.

As a referee, I would immediately reject such a paper. It is cranky kookishness from the first page. At best, any respectable journal will simply send it back with a rejection. More likely, they will simply ignore it.

 

[questfortruth]

As a referee, I would immediately reject such a paper. It is cranky kookishness from the first page. At best, any respectable journal will simply send it back with a rejection. More likely, they will simply ignore it.

Please be more polite in the future.

 

[Polymath257]

Please be more polite in the future.

Please don't attempt to publish crap in the future.

 

[questfortruth]

Please don't attempt to publish crap in the future.

 

[sayak83]

OK. In your description above, you used the analogy where the potential looks like an English tophat. The quartic hilltop model is a particular case of this. Essentially, if you graph y=1-x^2 and compare to y=1-x^4, the latter is more flat at x=0 than the former. It is a quartic (degree 4) hilltop.

The 'potential' in all of these measures the amount of energy for various strengths of the inflaton field. As in your description above, inflation requires a large value for zero field strength and a smaller value as we move away from zero.

The various potentials just are different mathematical ways to accomplish this that are motivated by other physics.

Most of the models for inflation do not focus on identifying the inflaton, but merely describing its properties.

The R^2 model adds another term to the Lagrangian for gravity. Such additions have been proposed independently of this, so it isn't an unreasonable thing to pursue. In this, there is not a new particle, just an adjustment to how gravity works at large field strengths. But it does give a period of inflation and allows reheating in a natural way (so that inflation is stopped).

Another good source of information:
http://pdg.lbl.gov/2016/reviews/rpp2016-rev-inflation.pdf

Thanks a lot. I was confused by the proliferating number of inflation models. More clearer now.
At lest now one knows which of the models are more likely to be true if inflation is correct. There were just too many being invented before.

Also good to see that my simple explanations earlier were not outdated by the Planck data.

 

[Polymath257]

Thanks a lot. I was confused by the proliferating number of inflation models. More clearer now.
At lest now one knows which of the models are more likely to be true if inflation is correct. There were just too many being invented before.

Also good to see that my simple explanations earlier were not outdated by the Planck data.

Yes, I was wrong.The PDG link mentions some question about whether the HIggs properties are consistent with them being the inflaton, but mention there is a 'tension' rather than it being ruled out.

Also, this was from data independent of the Planck data.

 

[sayak83]

Runaway Inflation and Multiverse

My previous posts provide a brief overview on how the inflation theory works. In the very early moments (10^-35 seconds or so), a small region of space was in a state of false vacuum, having a high energy density value of a Higgs (or some other) scalar field. The value depends a bit on the specific theory of inflation, but Vilenkin estimates it to be 10^70 tons/cc. But this region of high energy false vacuum is extremely small, about 10^-26 cm in diameter. Thus the total mass of this region of small vacuum needed to give rise to our universe (and all the Multiverse) can be as small as 26 grams.

As noted earlier this false vacuum has very high negative pressure (or tension) which creates repulsive gravity by Einstein's laws. The expansion is exponential doubling it's diameter in every 10^-37 seconds. Based on the inflation potential, the time required for the scalar field to decay into low energy values of our "true" vacuum is 10^-35 seconds. Hence the diameter of the universe increased by 2^100 fold while it's volume increased by 2^300 folds in just 10^-35 seconds. Since mass density of the false vacuum is constant, the total energy of the universe also increases by this amount (balanced by negative gravitational potential energy). Once the inflation field decays into the lower energy true vacuum state, all this energy is converted into matter-antimatter and radiation energy creating the hot expanding "fireball" of the Big Bang which then expands by orthodox radiation pressure balanced by gravity following Hubble law.

However decay of the inflation field from high energy false vacuum state to low energy true vacuum state is determined by quantum laws similar to that of decay of radioactive elements. It's a random decay given by a half life. The half life gives the amount of time it takes for half of the volume of false vacuum region to transition into true vacuum. This value again depends on the nature of the inflation field, but values are between 10^-30 to 10^-35 seconds. Yet an undecayed region of false vacuum doubles in size in 10^-37 seconds. So doubling rate is anywhere between a 100 to a billion times greater than the halving rate! Thus the inflationary false vacuum regions increases without bound becoming larger and larger at an unbelievable pace even as regions true vacuum form within it like bubbles in a boiling water forming "Island universes" of conventional vacuum, matter and energy.... one of which is ours. Most of the leading inflationary models have this creation of bubbles of individual island universes within an ever growing matrix of false vacuum as an unavoidable consequence.

Thus inflation theory which explains and predicts many important features of the visible universe also predicts this rich large scale Multiverse picture as its consequence.

In this figure the square blocks are false vacuum regions while the spherical regions are the island universes.

It is very important to note that inflation has predicted and explained major major aspects of cosmology and while the field that creates inflation has several viable alternatives, inflation itself is not much in doubt. As we see in the article below

Cosmic Inflation’s Five Great Predictions – Starts With A Bang! – Medium


But inflation is not some theoretical behemoth that’s disconnected from observables. Rather, it made five new predictions, and we’ve confirmed four so far! It may also have predicted things we haven’t yet figured out how to observe, like a multiverse, but that doesn’t take away from its successes in the least.


Another excellent link for inflation
http://scienceblogs.com/startswithabang/2011/10/28/why-we-think-theres-a-multiver/

 

[Ben Dhyan]

Hmmmm....not exactly on topic but what do you think? In this universal model, what do they mean by the void in which the physical matter 'holes' exist, the 95% dark energy and dark matter?

Celestial boondocks: Study supports the idea that we live in a void
June 6, 2017

In a 2013 observational study, University of Wisconsin–Madison astronomer Amy Barger and her then-student Ryan Keenan showed that our galaxy, in the context of the large-scale structure of the universe, resides in an enormous void — a region of space containing far fewer galaxies, stars and planets than expected.

Now, a new study by a UW–Madison undergraduate, also a student of Barger’s, not only firms up the idea that we exist in one of the holes of the Swiss cheese structure of the cosmos, but helps ease the apparent disagreement or tension between different measurements of the Hubble Constant, the unit cosmologists use to describe the rate at which the universe is expanding today.

Results from the new study were presented here today (June 6, 2017) at a meeting of the American Astronomical Society.

The tension arises from the realization that different techniques astrophysicists employ to measure how fast the universe is expanding give different results. “No matter what technique you use, you should get the same value for the expansion rate of the universe today,” explains Ben Hoscheit, the Wisconsin student presenting his analysis of the apparently much larger than average void that our galaxy resides in. “Fortunately, living in a void helps resolve this tension.”

The reason for that is that a void — with far more matter outside the void exerting a slightly larger gravitational pull — will affect the Hubble Constant value one measures from a technique that uses relatively nearby supernovae, while it will have no effect on the value derived from a technique that uses the cosmic microwave background (CMB), the leftover light from the Big Bang.

The new study not only firms up the idea that we exist in one of the holes of the Swiss cheese structure of the cosmos, but sheds light on how we measure the rate at which the universe is expanding today.

The new Wisconsin report is part of the much bigger effort to better understand the large-scale structure of the universe. The structure of the cosmos is Swiss cheese-like in the sense that it is composed of “normal matter” in the form of voids and filaments. The filaments are made up of superclusters and clusters of galaxies, which in turn are composed of stars, gas, dust and planets. Dark matter and dark energy, which cannot yet be directly observed, are believed to comprise approximately 95 percent of the contents of the universe.

The void that contains the Milky Way, known as the KBC void for Keenan, Barger and the University of Hawaii’s Lennox Cowie, is at least seven times as large as the average, with a radius measuring roughly 1 billion light years. To date, it is the largest void known to science. Hoscheit’s new analysis, according to Barger, shows that Keenan’s first estimations of the KBC void, which is shaped like a sphere with a shell of increasing thickness made up of galaxies, stars and other matter, are not ruled out by other observational constraints.

“It is often really hard to find consistent solutions between many different observations,” says Barger, an observational cosmologist who also holds an affiliate graduate appointment at the University of Hawaii’s Department of Physics and Astronomy. “What Ben has shown is that the density profile that Keenan measured is consistent with cosmological observables. One always wants to find consistency, or else there is a problem somewhere that needs to be resolved.”

The bright light from a supernova explosion, where the distance to the galaxy that hosts the supernova is well established, is the “candle” of choice for astronomers measuring the accelerated expansion of the universe. Because those objects are relatively close to the Milky Way and because no matter where they explode in the observable universe, they do so with the same amount of energy, it provides a way to measure the Hubble Constant.

A map of the local universe as observed by the Sloan Digital Sky Survey. The orange areas have higher densities of galaxy clusters and filaments. Sloan Digital Sky Survey -

Alternatively, the cosmic microwave background is a way to probe the very early universe. “Photons from the CMB encode a baby picture of the very early universe,” explains Hoscheit. “They show us that at that stage, the universe was surprisingly homogeneous. It was a hot, dense soup of photons, electrons and protons, showing only minute temperature differences across the sky. But, in fact, those tiny temperature differences are exactly what allow us to infer the Hubble Constant through this cosmic technique.”

A direct comparison can thus be made, Hoscheit says, between the ‘cosmic’ determination of the Hubble Constant and the ‘local’ determination derived from observations of light from relatively nearby supernovae.

The new analysis made by Hoscheit, says Barger, shows that there are no current observational obstacles to the conclusion that the Milky Way resides in a very large void. As a bonus, she adds, the presence of the void can also resolve some of the discrepancies between techniques used to clock how fast the universe is expanding.

Celestial boondocks: Study supports the idea that we live in a void

 

[Polymath257]

Hmmmm....not exactly on topic but what do you think? In this universal model, what do they mean by the void in which the physical matter 'holes' exist, the 95% dark energy and dark matter?

Well, dark matter tends to follow the distribution of regular matter. But that sentence in the article was a bit of a non-sequitur.

The point here is that the large scale structure of the universe looks sort of like a swiss cheese: relatively dense regions with a lot of galaxies and large, spherical 'voids' where galaxies are relatively rare. The article claims our galaxy is in one of the voids. Because the voids will expand faster than 'normal', this can throw off measurements of the overall expansion and lead to conflicts between different methods of measuring that expansion.

I have seen suggestions that the increased expansion of the voids with respect to the 'cheese' might even be an alternative to using dark energy as an explanation of some supernova measurements. This is still controversial, though.

 

[Ben Dhyan]

Thanks Polymath.

 

[Laika]

Many thanks to @sayak83 for sharing the information in this thread. I'm not going to pretend I understand it all, but I'm grateful someone has tried to explain it. Alot of time and effort went into that and its much appreciated.