Would this be the final confirmation re the Big Bang?

[beecee]

This article today in https://phys.org/news/2018-06-dark-inflation-gravitational-window-moments.html

Dark inflation opens up a gravitational window on the first moments after the Big Bang:

Dark matter and dark energy may have driven inflation, the exponential expansion of the universe moments after the Big Bang. A new cosmological model proposed by physicists at the University of Warsaw, which accounts for dark inflation, is the first to outline a precise chronology of the main events during the early history of our universe. The model makes a spectacular prediction—that it should be possible to detect gravitational waves formed just fractions of a second after the creation of spacetime.

What do we know about the evolution of universe immediately after the Big Bang? In spite of extensive research carried out over decades, current cosmological models still do not outline a precise chronology of events. Researchers at the Faculty of Physics at the University of Warsaw (UW Physics) have developed a new model in which the exponential expansion of dark matter and dark energy plays a key role. The dark inflation model organises the thermal history of the universe in chronological order and predicts that we should soon be able to detect primordial gravitational waves formed immediately after the Big Bang.

Read more at: https://phys.org/news/2018-06-dark-inflation-gravitational-window-moments.html#jCp

the associated paper is at

http://iopscience.iop.org/article/10.1088/1475-7516/2018/04/046/meta

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OK, there are a couple of extracts from the article that have me rather perplexed, with regards to my current knowledge of the BB and evolution of spacetime/universe. Admittedly I am not that clued up on "eternal Inflation" yet. My perplexed attitude is a result of the following two extracts from the physorg article. Sometimes of course the science writers/journalists can get it wrong or somewhat askew, and of course journalistic sensationalism can always rear its ugly head. The extracts are as follows.... 

Quote

"Inflation is described as a period of supercooled expansion. However, for cosmological models to be consistent, following inflation, the universe should have undergone reheating to a very high temperature, and we have no idea how or when this might have occurred. Just as with inflation itself, we are dealing with energies across a range of 70 orders of magnitude. As a result, the thermal history of the universe is yet to be described."

First question, with regards to the highlighted text, this seems to contradict what I have always been aware of...that is that the universe/spacetime expanded from a hot dense state and has been cooling ever since. So what do they mean by this "reheating" ??

Quote

"Gravitational waves lose energy as radiation. However, inflatons must lose it significantly faster. If inflation involved the dark sector, the input of gravitational waves increased proportionally. This means that traces of the primordial gravitational waves are not as weak as we originally thought," adds Dr. Artymowski."

This I think I understand, so would this reinforce and belay any reasonable doubt re the general BB/Inflationary model? [Much as gravitational waves discoveries reinforced GR and BH's]

 

Exploring further from the original article, one is lead to the following...https://phys.org/news/2018-05-multiversestephen-hawking-theory-big.html

entitled, Taming the multiverse—Stephen Hawking's final theory

Professor Stephen Hawking's final theory on the origin of the universe, which he worked on in collaboration with Professor Thomas Hertog from KU Leuven, has been published today in the Journal of High Energy Physics.

Read more at: https://phys.org/news/2018-05-multiversestephen-hawking-theory-big.html#jCp

the paper:

https://link.springer.com/article/10.1007%2FJHEP04(2018)147

A smooth exit from eternal inflation?

 

Abstract

The usual theory of inflation breaks down in eternal inflation. We derive a dual description of eternal inflation in terms of a deformed Euclidean CFT located at the threshold of eternal inflation. The partition function gives the amplitude of different geometries of the threshold surface in the no-boundary state. Its local and global behavior in dual toy models shows that the amplitude is low for surfaces which are not nearly conformal to the round three-sphere and essentially zero for surfaces with negative curvature. Based on this we conjecture that the exit from eternal inflation does not produce an infinite fractal-like multiverse, but is finite and reasonably smooth.

[Mordred]

Ok supercooling/reheating. When inflation occurs the rapid change in volume and sudden reduction in density causes the supercooling from the initial hot dense state. Then inflation goes through a slow roll phase. The deceleration from the rapid inflation is the cause of the reheating. Now when inflation was first proposed in the False vacuum model. It was soon discovered that the model had a problem. That problem being Runaway inflation, once it started there was no way for it to stop. Later models then had to come up with a mechanism for inflation to stop. This is the slow roll graceful exit. This slow roll exit is also one of the primary contributors to the surface of last scattering in so far as the reheating causes certain particles to drop out of thermal equilibrium leading to the metalicity percentages we measure. Now as this process has very anistropic characteristics and very rapid it is believed that GW waves should be present in the CMB. BICEP2 once thought they had spotted them but it wasn't conclusive enough. This paper presents another possible direction to look for GW waves that the model predicts should be present.

It would be another confirmation, but science never stops looking for other evidence so its never final confirmation lol

Edited June 9, 2018 by Mordred

[beecee]

1 hour ago, Mordred said:

Ok supercooling/reheating. When inflation occurs the rapid change in volume and sudden reduction in density causes the supercooling from the initial hot dense state.

Of course!! How bloody dumb of me! 

Quote

Then inflation goes through a slow roll phase. The deceleration from the rapid inflation is the cause of the reheating. Now when inflation was first proposed in the False vacuum model. It was soon discovered that the model had a problem. That problem being Runaway inflation, once it started there was no way for it to stop. Later models then had to come up with a mechanism for inflation to stop. This is the slow roll graceful exit. This slow roll exit is also one of the primary contributors to the surface of last scattering in so far as the reheating causes certain particles to drop out of thermal equilibrium leading to the metalicity percentages we measure. Now as this process has very anistropic characteristics and very rapid it is believed that GW waves should be present in the CMB. BICEP2 once thought they had spotted them but it wasn't conclusive enough. This paper presents another possible direction to look for GW waves that the model predicts should be present.

Beautifully succulently put, easy to understand answer answer. Thanks.

Quote

It would be another confirmation, but science never stops looking for other evidence so its never final confirmation lol

Yep, certainly...much like the answer I gave to another doubting Thomas yesterday re "scientific theories" They do grow in certainty over time understanding of course that in principle it always remains potentially falsifiable. Thanks again.

Edited June 9, 2018 by beecee

[Mordred]

 

Your welcome for the GW waves this is detectable by looking for the B modes as opposed to the e modes of the Baryon acoustic osscillations. Here is a Wayne Hu summary, I've alwsys liked his works and his article on early universe particle physics is excellent. On my website see link on signature.

http://background.uchicago.edu/~whu/intermediate/summary.html

 

[Mordred]

As this is relevant and also a good time to introduce a quick lesson on Baryon Acoustic oscillations. During inflation while photons readily encounter free electrons the waves are effectively washed out. However during the surface of last scattering when the free mean path increases , The photon to electrons interactions is described by Thomson scattering, With two distinctive modes representing the scalar quantities while the other polarization mode being a tensorial product. {GW waves) this group handles the curls of the field while the former the gradient field values. Here is a quick summary of Thomson scattering itself.

 http://www.ira.inaf.it/~ddallaca/P-Rad_4.pdf

The E modes are the gradient quantities, such as density and temperature, while the B modes being the curl polarizations. Anyways the two polarization modes will correspond to the Stokes parameters Q and U respectively in much the same mannerism by analogy to the electric E modes and the magnetic B modes. The polarizations we are measuring however are temperature anisotropies of the surface of last scattering. This measures in essence the incoming and outgoing scattering events between the photons and electrons. This multipole temperature field is quadrupole in nature. [latex] \mathcal{l}=0[/latex] is monopole (scalar} [latex] \mathcal{l}=l[/latex] is the dipole anisotropies, and [latex] \mathcal{l}=2[/latex] for quadrupole. The third polarization mode being the  T (temp) mode.

Anyways the math is fairly intensive so I won't go into it unless requested. However for DM we can use the mass to luminosity relation and how this involves temperature to look for GW waves in the CMB in the dark sector. Side note it was this ratio that led Zwicky to the missing mass problem in the first place.

 

 

Edited June 9, 2018 by Mordred

[beecee]

17 hours ago, Mordred said:

Ok supercooling/reheating. When inflation occurs the rapid change in volume and sudden reduction in density causes the supercooling from the initial hot dense state.

 

16 hours ago, beecee said:

Of course!! How bloody dumb of me! 

Readily observed of course when one releases the gas in a pressure spray can.

18 hours ago, Mordred said:

BICEP2 once thought they had spotted them but it wasn't conclusive enough. This paper presents another possible direction to look for GW waves that the model predicts should be present.

It would be another confirmation, but science never stops looking for other evidence so its never final confirmation lol

Yeah remember "debating" the BICEP2 original results with a couple of anti science and GR nuts on another forum. Quickly they jumped onto the bandwagon criticizing science in general as trying to pull the wool over the general populace's eyes. While most certainly the original "discovery release" was premature, it still took scientists themselves particularly those involved with some findings with the Planck experiment, to retract the original results and the likely occurrence of those results being muddied due to  dust and debris. I saw it as a confirmation of science and the absolute fact that results and theories are being tested and reappraised all the time.

Again, thanks for a great easily understood answer and other relevant information that you gave.