“The Big Bang theory requires a recent origin of the Universe that openly invites the concept of creation.”
Fred Hoyle, British mathematician and astronomer
By Mohd Amirul Faisal
When you look at the starry sky filled with millions of stars and galaxies scattered across the Milky Way, you might probably wonder how the early Universe appears to the naked eye if we were transported to that time and place. Roughly around 400,000 years after the Big Bang, the early universe would have been scorching hot for most of the atoms in the Periodic Table of Elements to form and stabilize.
As the surroundings cooled down, simple atoms such as hydrogen, helium, and lithium would become the first elements to colonize every part of the cosmos. These conditions are pristine enough for hydrogen to chemically bonded with helium, creating the very first molecule that is both stable and in actual liquid form called helium hydride.
What role does helium hydride play during the aftermath of the Big Bang? And how would the earliest generation of stars benefit from the creation of these profound molecules?
Traveling more than 1000 km/h to detect invisible particles
This monumental discovery was made thanks to the Stratospheric Observatory for Infrared Astronomy (SOFIA), a telescope mounted on a Boeing 747-SP airplane. They have detected helium hydride, the first molecule to form after the Big Bang, in a nebula located 3,000 light-years away. The molecule was formed by the reaction between a helium ion and a hydrogen atom, making it a crucial discovery as it confirms a prediction made over 90 years ago.
SOFIA’s unique ability to fly above ground level at 45,000 feet and onboard the Boeing airplane with speeds up to 1000 km/h, enables the telescope to detect the molecules without interference from pesky man-made radio waves from below. It still remains a challenge for astronomers to prevent data collected by telescopes from being contaminated. When you are flying tens of thousands of meters above ground level away from the confinements of such interference waves, that obstacle can be completely eliminated. The discovery of helium hydride opened doors of opportunities for researchers to understand the conditions of the early Universe and how the first generation of stars came to be.
The quest to identify these molecules has long commenced since the late 1970s. When technology was still in its infancy stage, theories and hypotheses are the only means for astronomers trying to delve deep into the molecules’ origins. An aging star detected within the regions of NGC 7027 nebula might serve as a suitable place for helium hydride to form without being disintegrated by harsh external conditions. Alas, no one was able to validify the theory up to the point of the discovery of the molecule.
Impossible to ‘detect’ a 13 billion-year-old molecule
The headlines that raved the internet might attract a lot of attention but just because the researchers had discovered helium hydride in the cosmos does not mean that these molecules are 100% the exact same ones that existed back in time. In fact, the further we look into the edges of the Universe, the more void regions we would witness. Gravitation has yet to govern the planets and other celestial objects as galaxies themselves were not there in sight. Roughly around 380,000 years after the Big Bang, nothing but energized elementary particles moving at the speed of light were the only significant events that happened in a scorching hot baby universe.
The first elements that sprouted out of existence would be the lightest elements in the periodic table; hydrogen and helium. In fact, 75% hydrogen and 25% helium made most of the universe back then. Before these elements were formed, the surroundings had to cool down first to a certain degree for the fast-moving electrons to make a downturn. Once an electron collided with a proton, it sparks a chemical reaction at an atomic scale (duh), and finally, hydrogen marks its territory at the top of the periodic table.
Other elementary particles follow suit in a harmonized chain of reactions to produce helium atoms. Now, back to the question of why the first sighting of helium hydride is more than meets the eye. These active bombardments of particles have become known as the Recombination Era, a time when due to the blazing hot conditions, electrons and protons were geared up to continuously clash with each other.
But true molecules were nowhere to be found because hydrogen atoms are still ionized while helium atoms have become a neutral kind. It was not until these particles bind each other that they form a molecule known as helium hydride (HeH+). I have provided a simple equation for better visualization:
He+ + e– → He + H+ → HeH+
It was only a matter of time until most of the remaining hydrogen atoms became neutral as well. Helium hydride’s disappearance from the rest of the pack might have something to do with its molecular DNA. Neutral atoms tend to be more stable than ions. Hence, it had no choice but to interact with neutral hydrogen atoms, forming hydrogen molecules in the process. As the Universe turned 500,000 years old, the oldest molecules still containing traces from the Big Bang have long gone.
The discovery of helium hydride inside planetary nebulae can only mean one thing: the surroundings of these types of nebulae create temperatures high enough to replicate the hundred thousand years old universe that produced the original helium hydride. It might suggest that this molecule has been recycled for millennia contributing to the first stars popping into existence.
More questions arise and more missing puzzle pieces
Helium hydride is believed to be the first molecule in the early Universe. It’s ironic that this exact same molecule was first cooked inside labs before technological advancements made the jump that leads to its discovery in outer space. While the discovery confirms a prediction made over 90 years ago and provides an exciting opportunity for scientists to understand the conditions of the early universe and how the first stars formed, it also raises new questions.
As illustrated in the diagram above, the earliest stars were only formed 200 million years after the Big Bang. So-called Population III stars because they are the last types of stars identified by scientists. In comparison to other typical stars, Population III stars are mostly composed of hydrogen, helium, and minuscule traces of lithium. Nuclear fusion powered their cores and we already knew where this immense energy generation is coming from. However, if the first-generation stars emerged around 200 million years ago and helium hydride only has a short lifetime, how did helium hydride play a crucial role in the formation of these stars?
Then, there is also the Universe’s own Dark Ages where the cosmos was shrouded with darkness due to neutral hydrogen constantly trapping light from their surroundings. It would require a consistent amount of ionized hydrogen to produce a huge supply of helium hydride. That is where scientists can ramp up their curious minds to better understand the sequences of these cosmic events.
It’s undeniable that this discovery had placed wide smiles on many researcher’s faces. Detecting the universe’s oldest molecules provides an important step in adding more substance to the current Big Model alongside the development of hydrogen molecules which in turn contributes to the formation of the first stars. Just like many other fields of science, more questions are bound to emerge the more we unravel the mysteries of the Universe.
Thank you very much for reading! If you enjoyed this article, feel free to share it on social media and spread knowledge to the people around you 😀
References:-
- Faulkner, Dr. D. R. (2019, May 28). Helium hydride: The first molecule?. Answers in Genesis. https://answersingenesis.org/astronomy/helium-hydride-the-first-molecule/
- Clery, D. (2019, April 17). Astronomers have spotted the universe’s first molecule. Science. https://www.science.org/content/article/astronomers-have-spotted-universe-s-first-molecule
- Mathewson, S. (2019, April 18). Astronomers finally spot universe’s first molecule in Distant Nebula. Space.com. https://www.space.com/astronomers-detect-universe-first-molecule-space.html
- Fortenberry, R. C. (2020, February 1). The first molecule in the universe. Scientific American. https://www.scientificamerican.com/article/the-first-molecule-in-the-universe/
- Siegel, E. (2019, April 19). Scientists didn’t really find the first molecule in the universe. Forbes. https://www.forbes.com/sites/startswithabang/2019/04/19/scientists-didnt-really-find-the-first-molecule-in-the-universe/?sh=13efe55d5ee1
- Foust, J. (2018, June 3). Sofia the flying telescope resumes observations after extended maintenance. Space.com. https://www.space.com/40758-sofia-flying-telescope-observations-resume.html
Et illuminare 