Auther: Adwita Sinha
In the beginning there was a bang, or the big bang to be specific, and then there was a chain of events which lead itself to us, humanity. That is what we as humans think of when we think of the universe and in layman terms it is that. But to scientists, that very chain of event which brought us here, succeeding the big bang is of great interest, particularly the very beginning and they just had a breakthrough.
A historic discovery made by the phenomenal James Webb telescope a year ago is making headlines today. One of the galaxies captured by this telescope has now been declared as one of the oldest ever to be discovered. As per the study published in the journal ‘Nature’, published on the 15th of August, scientists place the galaxy to have been created a mere 390 million years after the big bang, which astronomically speaking, is quite early, placing the galaxy to be 13 billion years old compared to Earth’s 4.5 billion years. The stories on this galaxy are truly a tale as old as time.
The discovery was made by a team led by Steven Finkelstein, an astronomer at the University of Texas at Austin along with the CEERS team aka Cosmic Evolution Early Release Science Survey which is somewhat of a mouthful. The galaxy has been named, Maisie’s galaxy after Finkelstein’s daughter to commemorate the fact that these discoveries were made on her birthday (now that’s a gift to brag about).
This pops an important question; how do scientists determine the age of galaxies? To determine the age of these celestial bodies, astronomers measure their redshift – the amount that their colour has been shifted due to their motion away from us. As light travels through the universe to us from a distant source, it results in wavelengths of light the source is emanating to get stretched out, causing them to lose energy and change frequency. In simpler terms, the once blueish, high-frequency and short-wavelength light gradually turns to reddish, low-frequency and long-wavelength light. Astronomers refer to this change as “redshift” because the light is essentially being “shifted” toward the red end of the electromagnetic spectrum. In an expanding universe, the farther back in time we look, the higher an object’s redshift.
In the case of Maisie’s galaxy, the light had been traveling for tens-of-billions of years before hitting the James Webb Telescope making it somewhat complicated because the light in this case had shifted down to infrared making it invisible to the naked eye. So, the scientists followed up their estimates with measurements from the James Webb Telescope and landed on the number 11.4. But the universe is good at deception. The same study reevaluated redshifts of other galaxies and placed a galaxy earlier thought to be formed 250 million years after the big bang to actually have been created 1 billion after it. The South Korean deaging incident but at a cosmic level.
Maisie’s galaxy is one of the four distant galaxies detected by the James Webb telescope with all dating back to 300-500 million years post big bang. Turning back time to when these galaxies were formed the universe was a mere 2% of what it is today but a lot denser and hence are consequently comparatively lighter about 5 times less than what our milky way weighs
This discovery has also been crucial in understanding what ancient galaxies are like and simultaneously broken many notions scientists had made regarding the same. To their genuine surprise they found that Masie’s galaxy and other such galaxies were forming stars at a much faster rate than the had expected; and that too blue ones (ironical considering we were measuring the redshift). Blue stars contain more energy and hence expel much more energy into the universe. This discovery had scientists revisiting their theories on the early universe; and one consistent with other early galaxies.
One thing that is in line with scientist’s predictions however, is their composition. Their excessive blueness is indicative of the fact that these galaxies are scarce in metals and are primarily comprised of Hydrogen and Helium. This suggests that galaxies closer to the Big Bang had less time for metal formation. The Helium is simply the vast amounts of Helium expunged into the universe at the time of Big Bang and when something is so close to such a historic event, by which I mean the very creation of history, then you are bound to be influenced.
Our early universe still remains shrouded in mystery but one that excites the human curiosity. The limits to which we can go to satisfy that curiosity is clearly at display in this marvellous discovery. A little-known facet of this universe which seemed beyond our reach a few years ago is now actively being investigated. Our insatiable thirst to know more has led us some pace whose magnitude is incomprehensible. We as humanity have gotten a step closer to identifying how it all began and how it all came to be.