Explaining a universe composed of matter

Credit: CC0 Public Domain

The universe consists of a massive imbalance between matter and antimatter. Antimatter and matter are actually the same, but have opposite charges, but there's hardly any antimatter in the observable universe, including the stars and other galaxies. In theory, there should be large amounts of antimatter, but the observable universe is mostly matter

"We're here because there's more matter than in the universe," says Professor Jens Oluf Andersen at the Norwegian University of Science and Technology's (NTNU)Department of Physics. This great imbalance between matter and antimatter is all tangible matter, including life forms, exists, but scientists don't understand why.

Physics uses a to explain and understand how the world is connected. The standard model is a theory that describes all the particles scientists are familiar with. It accounts for quarks, electrons, the Higgs boson particle and how they all interact with each other. But the standard model cannot explain the fact that the world consists almost exclusively of matter. So there must be something we don't yet understand.

When antimatter and matter meet, they annihilate, and the result is light and nothing else. Given equal amounts of matter and antimatter, nothing would remain once the reaction was completed. As long as we don't know why more matter exists, we can't know why the building blocks of anything else exist, either. "This is one of the biggest unsolved problems in physics," says Andersen.

Researchers call this the "baryon asymmetry" problem. Baryons are subatomic particles, including protons and neutrons. All baryons have a corresponding antibaryon, which is mysteriously rare. The standard model of physics explains several aspects of the forces of nature. It explains how atoms become molecules, and it explains the particles that make up atoms.

"The standard model of physics includes all the particles we know about. The newest particle, the Higgs boson, was discovered in 2012 at CERN, says Andersen. With this discovery, an important piece fell into place. But not the final one. The standard model works perfectly to explain large parts of the universe, so researchers are intrigued when something doesn't fit. Baryon asymmetry belongs in this category.

Physicists do have their theories as to why there is more matter, and thus why we undeniably exist. "One theory is that it's been this way since the Big Bang," says Andersen. In other words, the imbalance between matter and antimatter is a basic precondition that has existed more or less from the beginning.

Quarks are among nature's smallest building blocks. An early surplus of quarks relative to antiquarks was propagated as larger units formed. But Andersen doesn't care for this explanation. "We're still not happy with that idea, because it doesn't tell us much," he says.

So why was this imbalance present from the beginning? Why did quarks initially outnumber antiquarks? "In principle, it's possible to generate asymmetry within the standard model of physics—that is, the difference between the amount of matter and antimatter. But we run into two problems," says Andersen.

First of all, scientists have to go way back in time, to just after the Big Bang when everything started—we're talking about 10 picoseconds, or 10-11 seconds after the Big Bang.

The second problem is that temperatures have to be around 1 trillion degrees Kelvin, or 1015 degrees. That's scorching—consider that the sun's surface is only about 5700 degrees. Regardless, it is not sufficient to explain baryonic matter. "It can't work. In the standard model, we don't have enough matter," Andersen says. "The problem is that the jump in the expectation value of the Higgs field is too small," he adds for the benefit those with only a minimum grasp of physics.

"It's probably not just our imagination that's imposing limits, but lots of possibilities exist," says Andersen. These possibilities therefore need to work together with the standard model. "What we're really looking for is an extension of the standard model. Something that fits into it."

Neither he nor other physicists doubt that the standard model is right. The model is continuously tested at CERN and other particle accelerators. It's just that the model isn't yet complete. Andersen and his colleagues are investigating various possibilities for the model to fit with the imbalance between matter and antimatter. The latest results were recently published in Physical Review Letters.

"Actually, we're talking about ," says Andersen. His group is considering processes of change in matter, like water turning into steam or ice under changing conditions. They're also considering whether matter came about as a result of an electroweak phase transition (EWPT) and formed a surplus of baryons just after the Big Bang. The electroweak phase transition occurs by the formation of bubbles. The new phase expands, a bit like water bubbles, and takes over the entire universe.

Andersen and his colleagues tested the so-called "two Higgs doublet" model (2HDM), one of the simplest extensions of the standard model. They searched for possible areas where the right conditions are present to create matter. "Several scenarios exist for how the baryon asymmetry was created. We studied the electroweak phase transition using the 2HDM model. This phase transition takes place in the early stage of our universe," says Andersen.

The process is comparable to boiling water. When water reaches 100 degrees Celsius, gas bubbles form and rise up. These gas bubbles contain water vapour which is the gas phase. Water is a liquid. When it transitions from the gas phase to the liquid phase in the early universe during a process in which the universe expands and is cooled, a surplus of quarks is produced compared to antiquarks, generating the baryon asymmetry.

Last but not least, the researchers are also doing mathematics. In order for the models to work in sync, parameters or numerical values have to fit so that both models are right at the same time. So the work is about finding these parameters. In the most recent article in Physical Review Letters, Andersen and his colleagues narrowed down the mathematical area in which can be created and at the same time correspond to both models. They have now narrowed the possibilities.

"For the new model (2HDM) to match what we already know from CERN, for example, the parameters in the can't be just anything. On the other hand, to be able to produce enough baryon asymmetry, the parameters also have to be within a certain range. So that's why we're trying to narrow the parameter range. But that's still a long way off," says Andersen. In any case, the researchers have made a bit of headway on the road to understanding why we and everything else are here.

Explore further

New finding of particle physics may help to explain the absence of antimatter

More information: Jens O. Andersen et al, Nonperturbative Analysis of the Electroweak Phase Transition in the Two Higgs Doublet Model, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.121.191802
Journal information: Physical Review Letters

Citation: Explaining a universe composed of matter (2019, February 4) retrieved 26 August 2019 from https://phys.org/news/2019-02-universe_1.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Feb 04, 2019
"Antimatter and matter are actually the same, but have opposite charges, ...". Antimatter and matter are actually the same, but they are different!

Feb 04, 2019
Doug. are you the same or, are you similar, to your reflection in a mirror?

I just thought, using that as an analogy? Is this not "similar" to te postulated thought experiment of Schrödinger's cat?

Speculating here. The world you see in your mirror only exists while you are viewing it. When you stop looking, you turn out the lights in your world, it no longer has a visual existence.

Where I am going with this, is to wonder if that missing anti-matter was a Universal mirror image? That disappeared into non-existence as an effect of the Big Bang?

Yeah, I know. That would place us into insurmountable quandary of trying to guess Before the Big Bang.

"Muahaha!" He utters with fiendish glee.

Feb 04, 2019
Phase transitions. Like condensation from plasma to gas to liquid, freezing from liquid to solid. But the initial state is before plasma, like quark-gluon soup or whatever.

Feb 04, 2019
You'd think that when the evidence is overwhelmingly against a hypothesis or model that hypotheses or model would at least be set aside but no, despite the current inflation model predicting 50% of all matter being antimatter (much less than 0.0000000000001% is antimatter) the model remains.

CP Violation has thus far constituted little more than wishful thinking. As Wikipedia puts it:
"It [CP Violation] plays an important role both in the attempts of cosmology to explain the dominance of matter over antimatter in the present Universe..."

With such loose science even religious themes are becoming competitive, after all, they present models and claim that the proof is pending, just like many aspects of the Big Bang including the one mentioned above...

Feb 04, 2019
Why does our world have a particular non-zero baryonic number? The term "asymmetry of baryogenesis" does not explain anything; this is simply a statement of fact. The availability of the energy is a necessary but not sufficient condition. The method of creation of the matter, our universe consists of, was different than that in accelerators. The space and its evolution are the primary sources of phenomena in Mega- and micro-worlds. Thus cosmology and particle physics have the same active agent - physical space.

Feb 04, 2019
CP violation is a proven fact. At least three mesons show it in their neutral current decay pathways, and the first was discovered in the 1960s (neutral kaon decay).

Feb 05, 2019
Supersymmetry is at the electron-positron creation level only.

Feb 05, 2019
I am not sure what Andersen mean with "In the standard model , we don't have enough matter," Andersen says. "The problem is that the jump in the expectation value of the Higgs field is too small,"". But I note that the LHC sees a standard model [SM] single SU(2) doublet Higgs, not a two Higgs SU(2) doublet.

As far as I know we can still rely on the three Sakharov conditions [SC] to generate matter/antimatter symmetry after inflation ended and released its potential energy [ https://en.wikipe...nditions ]. The simplest SM extension and and so far most promising I know of is the neutrino sector. Neutrinos have no mass constraint in the SM, yet we see they have mass (causes observed neutrino oscillations). AFAIU SM has scant CP symmetry violation but neutrino experiments see at - so far - low significance that neutrinos seem to have the exact size and direction that would fulfill SC. In 5 years we should know.

Feb 05, 2019
there is plenty antimatter inside the nucleus of every proton and neutron that makes us all - in fact the gluon singlet state is 50:50 split matter and anti-matter.

They likely are, as they have no matter/antimatter constraint - gluons is a boson (strong) force carrier, not a matter fermion such as quarks that builds up baryons.

The rest of your speculation loses me, it does not seem very relevant to the matter/antimatter symmetry breaking. (E.g. the 'going back in time' aspect of particle fields is just a mathematical model, information cannot really travel back in time so (parts of) fields cannot. Et cetera.)

Feb 05, 2019
If matter and antimatter were "actually, the same, but have opposite charges", this would mean that C symmetry would be conserved. It is not. Nor is CP symmetry, nor is CT symmetry. Only CPT symmetry is conserved, which means matter and matter are the same, except they have opposite charge, parity and dependence on time, according to the real laws of physics.

Feb 06, 2019
If half of the galaxies in the universe were composed entirely of antimatter (anti-galaxies) we'd never be able to tell. Only thing that would be an indicator would be the regions of intergalactic space where intergalactic gas surrounding galaxies and anti-galaxies meet, in these regions there would be gamma ray production from matter antimatter annihilation. Thing is these regions would quickly depopulate (if true, they already have) leaving no contact zones between matter and antimatter regions.

It's very possible that half of the matter in the universe is anti.

Feb 06, 2019
@Kron, why would the gas and dust stop coming out? You do realize that the gamma and X-ray emissions are easily detectable and would be noted if they were there, right?

Given not much radiation from annihilation is detected, the conclusion is there are a very low percentage of gamma and X-rays from annihilation, and the universe is made of matter with a percentage of antimatter determined by how much of this easily detected radiation is in fact seen, right? And that percentage is on the close order of 0.00001%.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more