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

June 8, 2018, University of Warsaw
A comparison of the current inflation model of the evolution of the Universe to the dark inflation model recently proposed by scientists from the Faculty of Physics at the University of Warsaw. Credit: UW Physics

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 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 and dark 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 formed immediately after the Big Bang.

The earliest structure of the universe we can study today is cosmic microwave background (CMB) radiation. This electromagnetic relic dates back to around 380,000 years after the Big Bang and is surprisingly homogeneous, even in regions that are so far apart that light couldn't have covered the distance between them in the time available. In 1979, Alan Guth proposed inflation as a simple explanation for this uniformity: The current vast distances between the homogeneous regions are so great because at one time, there was an extremely rapid expansion of spacetime, enlarging a billion billion billion times over in just fractions of a second. This is said to have been driven by a hypothetical inflation field and particles known as inflatons.

"The fundamental problem with inflation is that we don't really know when exactly it occurred, or at what energy levels. The range of energies at which inflation could have occurred is vast, stretching over 70 orders of magnitude," explains Prof. Zygmunt Lalak (UW Physics). He adds, "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."

Measurements of CMB radiation via the Planck satellite have been used to estimate the composition of the contemporary universe. It turns out that dark energy comprises as much as 69 percent of all extant energy/matter, with dark matter comprising 26 percent and ordinary matter just 5 percent. Dark matter and ordinary matter don't interact at all, or their interactions are so weak we are only just starting to notice dark matter's gravitational impact on the movement of stars in galaxies and galaxies in clusters. Dark energy should be a factor responsible for the accelerated expansion of the universe.

"Our inflation model is significantly different from those proposed in the past. We started with the assumption that since today, dark matter and comprise up to 95 percent of the universe's structure, then both factors must also have been extremely important immediately after the Big Bang. This is why we describe the dark sector of the universe as responsible for the inflation process," explains Dr. Michal Artymowski (UW Physics), main author of the paper published in the Journal of Cosmology and Astroparticle Physics.

In the proposed model, inflation is driven by a scalar field. The properties of the field mean that inflation isn't permanent and it must come to an end—at some point, the rate of expansion of the universe will start slowing instead of accelerating. At the point of this shift, new relativistic particles are formed, behaving in the same way as radiation. Some of these particles are described by the Standard Model, while others may correspond to particles predicted by theories beyond the Standard Model, such as supersymmetry.

"In our models, the new particles are the result of gravitation, which is a very weak force. The process of formation of particles is ineffective, and at the end of inflation, inflatons continue to dominate the universe," says Olga Czerwinska, Ph.D. student at UW Physics.

In order to recreate the observed dominance of radiation in the universe, inflatons should lose energy rapidly. The researchers propose two physical mechanisms that could be responsible for the process. They reveal that the new model predicts the course of events of the universe's thermal history with a far greater accuracy than previously.

The model's predictions concerning primordial gravitational waves are especially interesting. Gravitational waves are vibrations of spacetime itself, and they have already been detected several times. In each case, their source has been the merger of a pair of black holes or neutron stars. Current cosmological models predict that gravitational waves should also appear as a result of inflation. However, all the evidence suggested that vibrations of spacetime caused by inflation would be so weak by now that no existing or future detectors would have been able to register them. These predictions were revised when physicists from the University of Warsaw took into account the effects of the dark sector of the universe.

"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.

The estimates made by the Warsaw physicist are optimistic. Data suggests that could be detected by observatories currently at the design stage or under construction, such as the Deci-Hertz Interferometer Gravitational Wave Observatory (DECIGO), Laser Interferometer Space Antenna (LISA), European Pulsar Timing Array (EPTA) and Square Kilometre Array (SKA). The first events could be detected in the coming decade. For cosmologists, this would be an unprecedented discovery, paving the way for research into gravitational events that took place immediately after the Big Bang—a period hitherto impossible to study.

The dark model has another fascinating aspect: it is highly dependent on gravitational theory. By comparing the 's predictions with data collected by gravitational observatories, cosmologists should be able to provide new verifications of Einstein's general theory of relativity. What happens if they find discrepancies? It would mean that observational data provides the first information on the properties of real gravity.

Explore further: Taming the multiverse—Stephen Hawking's final theory about the big bang

More information: Michał Artymowski et al, Gravitational wave signals and cosmological consequences of gravitational reheating, Journal of Cosmology and Astroparticle Physics (2018). DOI: 10.1088/1475-7516/2018/04/046

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danR
1.8 / 5 (5) Jun 08, 2018
"Our inflation model is significantly different from those proposed in the past." --Artymowski

"different FROM"

Now there's a Pole who really knows his English prepositions. Difference entails a qualitative comparison, not quantitative. How many anglophones, even academics, would have used the incorrect 'than' in this sentence? Probably most of them.
_________
Now, after that (almost) entirely frivolous observation, folks, do carry on with something of substance...
IwinUlose
5 / 5 (2) Jun 08, 2018
thanks dan.
cantdrive85
2.6 / 5 (10) Jun 08, 2018
LOL! Dark inflation is real in modern cosmology as the dark pseudoscience is expanding much faster than real understanding of the Universe.
KelDude
2.3 / 5 (9) Jun 09, 2018
Dark energy and Dark matter are just excuses to fix the models and theories of the universe. They actually do NOT exist at all. I find it embarrassing that they're actually being discussed and taken seriously at the professional level.
Reg Mundy
2.5 / 5 (8) Jun 10, 2018
The current vast distances between the homogeneous regions are so great because at one time, there was an extremely rapid expansion of spacetime, enlarging a billion billion billion times over in just fractions of a second. This is said to have been driven by a hypothetical inflation field and particles known as inflatons.

Doesn't this sort of stuff make you feel that, somehow, the current scientific theories of how it all works are simply crap? Time for a rethink on the fundamentals!
Benni
1.6 / 5 (7) Jun 10, 2018
Dark energy and Dark matter are just excuses to fix the models and theories of the universe. They actually do NOT exist at all. I find it embarrassing that they're actually being discussed and taken seriously at the professional level.


.......now they add to that fiction with a newly coined preposterous statement, "Dark Inflation".

What is with Pop-Cosmology these days? Always reaching for the next level of preposterous narratives with Dark Inflation.

These storylines have simply become sporting events Pop-Cosmologists entertain themselves with, and there will always be a bunch of suckers out there who will swallowup junk like this, you can identify them by the 1 Star votes they cast against any criticism of dumb stuff like these narratives Pop-Cosmologists entertains themselves with. Right RNP? Jonesy?
Reg Mundy
1 / 5 (5) Jun 10, 2018
The current vast distances between the homogeneous regions are so great because at one time, there was an extremely rapid expansion of spacetime, enlarging a billion billion billion times over in just fractions of a second. This is said to have been driven by a hypothetical inflation field and particles known as inflatons.

Doesn't this sort of stuff make you feel that, somehow, the current scientific theories of how it all works are simply crap? Time for a rethink on the fundamentals!


Wow! Somebody gave me a five on this! I'm only used to getting hundreds of ones from autobots and the Stumpy bunch. Does this mean we have a new visitor who actually THINKS?
Benni
2 / 5 (4) Jun 10, 2018
The current vast distances between the homogeneous regions are so great because at one time, there was an extremely rapid expansion of spacetime, enlarging a billion billion billion times over in just fractions of a second. This is said to have been driven by a hypothetical inflation field and particles known as inflatons.

Doesn't this sort of stuff make you feel that, somehow, the current scientific theories of how it all works are simply crap? Time for a rethink on the fundamentals!


Wow! Somebody gave me a five on this! I'm only used to getting hundreds of ones from autobots and the Stumpy bunch. Does this mean we have a new visitor who actually THINKS?


.....click on your name ( Reg Mundy) & look at your Activity comments, everyone is listed. Shotguy voted against you.
Caliban
5 / 5 (4) Jun 10, 2018
One can only suppose that you clowns will have to wait for the primordial gravitational waves predicted by this hypothesis to still be energetic enough to be measurable by devices currently in development to be measured or --in support of your contention-- not, to be able to make any legitimate to the contrary, since you have already rejected --out of hand-- how well it conforms to observation, and right out of the gate, at that.

It would certainly help your general credibility as would-be Science critics if you were aware of the difference between your elbows and a hole-in-the-head.
Benni
1.8 / 5 (5) Jun 10, 2018
wait for the primordial gravitational waves predicted by this hypothesis to still be energetic enough to be measurable by devices currently in development to be measured


Hey Cal, just in case you hadn't already thought about it, if the g waves are primordial & move at the speed of light and the velocity of our galaxy through space is about 370 miles /sec compared to light at 186,000 miles/sec, maybe you can explain how we will ever detect waves that have long passed us up?

Keep in mind, you stated "primordial" as in the primordial phase of the Universe a few million years after the Biggo Bango, Maybe you can explain how our galaxy has managed to outrun all those early GWs that are older even than planet Earth?
cantdrive85
1.7 / 5 (6) Jun 10, 2018
primordial gravitational waves predicted

In the end, we'll probably determine these "gravitational waves" are just due to extremely energetic electromagnetic events waving the ether.
Ojorf
3 / 5 (4) Jun 11, 2018
Hey Cal, just in case you hadn't already thought about it, if the g waves are primordial & move at the speed of light and the velocity of our galaxy through space is about 370 miles /sec compared to light at 186,000 miles/sec, maybe you can explain how we will ever detect waves that have long passed us up?


LOL!

OMG!

You don't know the first thing about relativity, what a STUPID question.

Go read up on relativity Benni, it answers your question!

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