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We May Finally Understand the Moments Before the Big Bang

an artist's illustration of the big bang
An artist's interpretation of the Big Bang. (Image credit: NASA's Goddard Space Flight Center/CI Lab)

There's a hole in the story of how our universe came to be. First, the universe inflated rapidly, like a balloon. Then, everything went boom.

But how those two periods are connected has eluded physicists. Now, a new study suggests a way to link the two epochs.

In the first period,  the universe grew from an almost infinitely small point to nearly an octillion (that's a 1 followed by 27 zeros) times that in size in less than a trillionth of a second. This inflation period was followed by a more gradual, but violent, period of expansion we know as the Big Bang. During the Big Bang, an incredibly hot fireball of fundamental particles — such as protons, neutrons and electrons — expanded and cooled to form the atoms, stars and galaxies we see today.

The Big Bang theory, which describes cosmic inflation, remains the most widely supported explanation of how our universe began, yet scientists are still perplexed by how these wholly different periods of expansion are connected. To solve this cosmic conundrum, a team of researchers at Kenyon College, the Massachusetts Institute of Technology (MIT) and the Netherlands' Leiden University simulated the critical transition between cosmic inflation and the Big Bang — a period they call "reheating."

Related: From Big Bang to Present: Snapshots of Our Universe Through Time (opens in new tab)

"The post-inflation reheating period sets up the conditions for the Big Bang and, in some sense, puts the 'bang' in the Big Bang," David Kaiser, a professor of physics at MIT, said in a statement. "It's this bridge period where all hell breaks loose and matter behaves in anything but a simple way."

When the universe expanded in a flash of a second during cosmic inflation, all the existing matter was spread out, leaving the universe a cold and empty place, devoid of the hot soup of particles needed to ignite the Big Bang. During the reheating period, the energy propelling inflation is believed to decay into particles, said Rachel Nguyen, a doctoral student in physics at the University of Illinois and lead author of the study.

"Once those particles are produced, they bounce around and knock into each other, transferring momentum and energy," Nguyen told Live Science. "And that's what thermalizes and reheats the universe to set the initial conditions for the Big Bang."

In their model, Nguyen and her colleagues simulated the behavior of exotic forms of matter called inflatons. Scientists think these hypothetical particles, similar in nature to the Higgs boson, created the energy field that drove cosmic inflation. Their model showed that, under the right conditions, the energy of the inflatons could be redistributed efficiently to create the diversity of particles needed to reheat the universe. They published their results Oct. 24 in the journal Physical Review Letters.

A crucible for high-energy physics

"When we're studying the early universe, what we're really doing is a particle experiment at very, very high temperatures," said Tom Giblin, an associate professor of physics at Kenyon College in Ohio and co-author of the study. "The transition from the cold inflationary period to the hot period is one that should hold some key evidence as to what particles really exist at these extremely high energies."

One fundamental question that plagues physicists is how gravity behaves at the extreme energies present during inflation. In Albert Einstein's theory of general relativity, all matter is believed to be affected by gravity in the same way, where the strength of gravity is constant regardless of a particle's energy. However, because of the strange world of quantum mechanics, scientists think that, at very high energies, matter responds to gravity differently.

The team incorporated this assumption in their model by tweaking how strongly the particles interacted with gravity. They discovered that the more they increased the strength of gravity, the more efficiently the inflatons transferred energy to produce  the zoo of hot matter particles found during the Big Bang.

Now, they need to find evidence to buttress their model somewhere in the universe.

"The universe holds so many secrets encoded in very complicated ways," Giblin told Live Science. "It's our job to learn about the nature of reality by coming up with a decoding device — a way to extract information from the universe. We use simulations to make predictions about what the universe should look like so that we can actually start decoding it. This reheating period should leave an imprint somewhere in the universe. We just need to find it."

But finding that imprint could be tricky. Our earliest glimpse of the universe is a bubble of radiation left over from a few hundred thousand years after the Big Bang, called the cosmic microwave background (CMB). Yet the CMB only hints at the state of the universe during those first critical seconds of birth. Physicists like Giblin hope future observations of gravitational waves will provide the final clues. 

Originally published on Live Science. 

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  • rod
    Alan Guth periodically reports on the many particles created and used in the inflation model of the Big Bang. A good example is magnetic monopoles, as abundant as hydrogen and could be used to make stars too :) I read an interesting report today on the Hubble constant,
    Interesting folks. Another report indicating the Hubble constant, H0 is a miscreant ☹ I like this in the report:
    "It looks like a small difference, only 7%, but it is significant considering that we are talking about precisions of 1 or 2% in the value of the Hubble constant," as emphasised by Licia Verde, who jokes: "It is like trying to thread a 'cosmic needle' where its hole is the H0 value measured today and the thread is brought by the model from the furthest Universe we can observe: the cosmic microwave background." In addition, she points out some of the consequences of the discrepancy: "The lower the H0 is, the older the Universe is. Its current age is calculated at about 13.8 billion years considering that the Hubble constant is 67 or 68 km/s/Mpc; but if its value were 74 km/s/Mpc, our universe would be younger: it would be approximately 12.8 billion years old." I check info like this using the cosmology calculators,
    I used the #1 at the link and found an age for the Hubble time about 12.9 billion years old using 74 km/s/Mpc. However that is for the flat model based upon inflation. The open universe shows 10.746 years old, changing no other parameters. Looks like the cosmology department has wiggle room. I think the inflation folks enjoy some wiggle areas too in the math department :)
  • rod
    Okay, 10.746 years old is 10.746E+9 years old - my bad.
  • Dwight Huth
    You can't consider our Universe to be an infinity small that expanded because the space around the small particle that was our Universe was infinitely infinite prior to the Big Bang.

    For all intense and purposes all of this talk about points of infinity sounds like a black hole.
  • rod
    Dwight Huth, interesting view. It appears that 3-D space was infinite in size before the Big Bang event when our universe started out smaller than an electron in diameter. This is a critical assumption I feel in cosmology models like the multiverse scenario. My concern. Is inflation and the Big Bang model as reliable and secure science as the astronomy that resulted in the overthrow of the geocentric universe and acceptance of the heliocentric solar system? Keep in mind that the geocentric doctrine featured the immovable Earth, the Sun moved around the Earth, including all other lights in the firmament and the Earth did not move. I see inflation and Big Bang - much more tentative when compared with this standard of testing.
  • Mikelso
    Admin said:
    We May Finally Understand the Moments Before the Big Bang : Read more
    Taking us back to the very moment of the big bang is a point in time and a place, just before the flash point of the explosion where was that spot located ? if nothing existed can something from nothing occur in physics ? where did this place exist? Am I the only one thinking like this? Please take it easy on me I'm a newbie but this has always been on my mind since I heard about the " Big bang"
  • rod
    Mikelso, you said "just before the flash point of the explosion where was that spot located ?" From my understanding of the Big Bang model, there is no *spot or center* from which the universe evolved out of thus there is no explosion from a center point expanding outward, 3-D space created instantaneously, everywhere with matter/energy spread, everywhere. If there was, the universe we see today has a center and Big Bang rejects this concept. You can get an open or flat universe (inflation is flat cosmology). Today astronomers see the cosmic microwave background radiation, but in the Big Bang model, another universe or multiverse exist far beyond the CMBR where matter/energy can exist in any form, it seems along with many different laws of science - it seems. Alan Guth et al in inflation theory - argue what seems to be the universe created from nothing but now inflation theory combined with multiverse defines what was there before the Big Bang. I already discussed scientific testing and the geocentric teaching vs. heliocentric solar system testing and observations. I am glad this report discussed the inflaton particles in inflation - something not commonly reported. In the Big Bang model, the first stars cold also be made of dark matter too, not just Population III stars composed chiefly of hydrogen, helium, and perhaps a little lithium. I read reports where these are *dark stars* :)
  • wingedhippo
    Admin said:
    We May Finally Understand the Moments Before the Big Bang : Read more
    The Universe/Nature, i.e. NOTHING & SOMETHING has no time point of its origin. So, just as you cannot determine the beginning of Nothing, you cannot determine the beginning of Something. And please bear in mind: NOTHING cannot create SOMETHING and SOMETHING cannot turn into NOTHING.
  • Jurandyr
  • wingedhippo
    Jurandyr said:

    1. Space-time is an irrational idea. Time (concept) cannot marry Space (physical reality).
    2. Quote: "This is a speculative proposal description of a mechanism (Concept). To become a Theory must be explained using Math. "
    No way. In physics, we explain. Maths does not explain anything. It describes.
  • Manuel Antolín
    If protons and neutrons are assumed as being the first appearing , what about quarks?
    This has not been taken in account in dealing with the "formation" of matter, as it looks a bit hard to imagine as a previous stage in the matter formation process.
    If, as it is said and commonly accepted, 1/3 of energy phased into matter, and 1/6 of this matter phased into the normal matter as we see it, as the Universe was inflating / expanding, it should go of itself that the first phase of the matter conforming had to be the quark formation, as they are today conforming the matter as we know it.
    TLDR: there is not real / final comprension of the origin of the Universe yet.