Measuring helium in distant galaxies may give physicists insight into why the universe exists

When theoretical physicists like myself say that we’re finding out why the universe exists, we sound like philosophers. However new information collected by researchers utilizing Japan’s Subaru telescope has revealed insights into that very query.

The Big Bang kick-started the universe as we all know it 13.8 billion years in the past. Many theories in particle physics recommend that for all of the matter created on the universe’s conception, an equal quantity of antimatter ought to have been created alongside it. Antimatter, like matter, has mass and takes up space. Nevertheless, antimatter particles exhibit the other properties of their corresponding matter particles.

When items of matter and antimatter collide, they annihilate each other in a powerful explosion, abandoning solely power. The puzzling factor about theories that predict the creation of an equal stability of matter and antimatter is that in the event that they had been true, the 2 would have completely annihilated one another, leaving the universe empty. So there will need to have been extra matter than antimatter on the start of the universe, as a result of the universe is not empty—it is stuffed with stuff that is product of matter like galaxies, stars and planets. A bit of little bit of antimatter exists around us, however it is extremely uncommon.

As a physicist working on Subaru data, I am on this so-called matter-antimatter asymmetry problem. In our recent study, my collaborators and I discovered that the telescope’s new measurement of the quantity and kind of helium in faraway galaxies could provide an answer to this long-standing thriller.

After the Large Bang

Within the first milliseconds after the Large Bang, the universe was scorching, dense and stuffed with elementary particles like protons, neutrons and electrons swimming around in a plasma. Additionally current on this pool of particles had been neutrinos, that are very tiny, weakly interacting particles, and antineutrinos, their antimatter counterparts.

Physicists consider that only one second after the Large Bang, the nuclei of sunshine parts like hydrogen and helium started to kind. This course of is called Big Bang Nucleosynthesis. The nuclei fashioned had been about 75% hydrogen nuclei and 24% helium nuclei, plus small quantities of heavier nuclei.

The physics neighborhood’s most widely accepted theory on the formation of those nuclei tells us that neutrinos and antineutrinos performed a basic position within the creation of, specifically, helium nuclei.

Helium creation within the early universe occurred in a two-step course of. First, neutrons and protons transformed from one to the opposite in a series of processes involving neutrinos and antineutrinos. Because the universe cooled, these processes stopped and the ratio of protons to neutrons was set.

As theoretical physicists, we will create fashions to check how the ratio of protons to neutrons is determined by the relative variety of neutrinos and antineutrinos within the early universe. If more neutrinos were present, then our fashions present extra protons and fewer neutrons would exist in consequence.

Because the universe cooled, hydrogen, helium and different parts formed from these protons and neutrons. Helium is made up of two protons and two neutrons, and hydrogen is only one proton and no neutrons. So the less the neutrons obtainable within the early universe, the much less helium can be produced.

As a result of the nuclei fashioned throughout Large Bang Nucleosynthesis can still be observed today, scientists can infer what number of neutrinos and antineutrinos had been current in the course of the early universe. They do that by trying particularly at galaxies which are wealthy in mild parts like hydrogen and helium.

A clue in helium

Final yr, the Subaru Collaboration—a bunch of Japanese scientists engaged on the Subaru telescope—launched information on 10 galaxies far exterior of our personal which are nearly completely made up of hydrogen and helium.

Utilizing a method that enables researchers to differentiate completely different parts from each other primarily based on the wavelengths of sunshine noticed within the telescope, the Subaru scientists decided precisely how a lot helium exists in every of those 10 galaxies. Importantly, they discovered much less helium than the beforehand accepted concept predicted.

With this new consequence, my collaborators and I labored backward to seek out the number of neutrinos and antineutrinos obligatory to provide the helium abundance discovered within the information. Assume again to your ninth grade math class if you had been requested to resolve for “X” in an equation. What my group did was basically the extra subtle model of that, the place our “X” was the variety of neutrinos or antineutrinos.

The beforehand accepted concept predicted that there ought to be the identical variety of neutrinos and antineutrinos within the early universe. Nevertheless, once we tweaked this concept to provide us a prediction that matched the brand new information set, we found that the variety of neutrinos was better than the variety of antineutrinos.

What does all of it imply?

This evaluation of latest helium-rich galaxy information has a far-reaching consequence—it may be used to clarify the asymmetry between matter and antimatter. The Subaru information factors us on to a supply for that imbalance: neutrinos. On this examine, my collaborators and I proved that this new measurement of helium is per there being extra neutrinos then antineutrinos within the early universe. By known and likely particle physics processes, the asymmetry within the neutrinos might propagate into an asymmetry in all matter.

The results of our examine is a standard kind of consequence within the theoretical physics world. Mainly, we found a viable method by which the matter-antimatter asymmetry might have been produced, however that does not imply it undoubtedly was produced in that method. The truth that the information suits with our concept is a touch that the idea we have proposed could be the proper one, however this reality alone doesn’t suggest that it’s.

So, are these tiny little neutrinos the important thing to answering the age previous query, “Why does something exist?” Based on this new analysis, they only could be.

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