Since time immemorial, philosophers and scholars have contemplated the beginning of time and even tried to determine when all things began. It’s only been in the age of modern astronomy that we’ve come close to answering that question with a fair degree of certainty. According to the most widely-accepted cosmological models, the Universe began with the Bang Bang roughly 13.8 billion years ago.
Even so, astronomers are still uncertain about what the early Universe looked like since this period coincided with the cosmic “Dark Ages.” Therefore, astronomers keep pushing the limits of their instruments to see when the earliest galaxies formed. Thanks to new research by an international team of astronomers, the oldest and most distant galaxy observed in our Universe to date (GN-z11) has been identified!
Measuring the expansion of the universe is hard. For one thing, because the universe is expanding, the scale of your distance measurements affects the scale of the expansion. And since light from distant galaxies takes time to reach us, you can’t measure what the universe is, but rather what it was. Then there is the challenge of the cosmic distance ladder.
What happened to all the lithium? The question has stumped astronomers for decades. While cosmologists have successfully predicted the abundance of the other light elements from the Big Bang, lithium has always come up short. Now, a team of astronomers may have found the reason: lithium-rich asteroids are smashing into white dwarves.
The oldest light in the universe is that of the cosmic microwave background (CMB). This remnant glow from the big bang has traveled for more than 13 billion years. Along the way, it has picked up a few tales about the history and evolution of the cosmos. We just need to listen to what it has to say.
“Science is not only compatible with spirituality; it is a profound source of spirituality. When we recognize our place in an immensity of light years and in the passage of ages, when we grasp the intricacy, beauty and subtlety of life, then that soaring feeling, that sense of elation and humility combined, is surely spiritual.” – Carl Sagan “The Demon-Haunted World.”
Learning about the Universe, I’ve felt spiritual moments, as Sagan describes them, as I better understand my connection to the wider everything. Like when I first learned that I was literally made of the ashes of the stars – the atoms in my body spread into the eternal ether by supernovae. Another spiritual moment was seeing this image for the first time:
In July of 2015, NASA’s New Horizons probe made history when it became the first mission ever to conduct a close flyby of Pluto. This was followed by the spacecraft making the first-ever encounter with a Kuiper Belt Object (KBO) – known as Arrokoth (aka. 2014 MU69) – on Dec.31st, 2018. In addition, its unique position in the outer Solar System has allowed astronomers to conduct rare and lucrative science operations.
For almost a century, astronomers have understood that the Universe is in a state of expansion. Since the 1990s, they have come to understand that as of four billion years ago, the rate of expansion has been speeding up. As this progresses, and the galaxy clusters and filaments of the Universe move farther apart, scientists theorize that the mean temperature of the Universe will gradually decline.
But according to new research led by the Center for Cosmology and AstroParticle Physics (CCAPP) at Ohio State University, it appears that the Universe is actually getting hotter as time goes on. After probing the thermal history of the Universe over the last 10 billion years, the team concluded that the mean temperature of cosmic gas has increased more than 10 times and reached about 2.2 million K (~2.2 °C; 4 million °F) today.
For astronomers, astrophysicists, and cosmologists, the ability to spot the first stars that formed in our Universe has always been just beyond reach. On the one hand, there are the limits of our current telescopes and observatories, which can only see so far. The farthest object ever observed was MACS 1149-JD, a galaxy located 13.2 billion light-years from Earth that was spotted in the Hubble eXtreme Deep Field (XDF) image.
On the other, up until about 1 billion years after the Big Bang, the Universe was experiencing what cosmologists refer to as the “Dark Ages” when the Universe was filled with gas clouds that obscured visible and infrared light. Luckily, a team of researchers from Georgia Tech’s Center for Relativistic Astrophysics recently conducted simulations that show what the formation of the first stars looked like.
Weighing the universe is a tricky task, but a team of astronomers have used a clever technique to measure how many galaxy clusters are in the cosmos, and from there come up with a total amount of matter. The answer: 31.5±1.3% of all the energy in the universe.
No matter which direction you look in the Universe, the view is basically the same if you look far enough. Our local neighborhood is populated with bright nebulae, star clusters, and dark clouds of gas and dust. There are more stars toward the center of the Milky Way than there are in other directions. But across millions, and billions, of light-years, galaxies cluster evenly in all directions, and everything starts to look the same. In astronomy, we say the Universe is homogeneous and isotropic. Put another way, the Universe is smooth.