Life Beyond Earth
Starring Galaxy was born out of a singularity that brought about our whole existence: the Big Bang. An isolated moment in space and time created something out of nothing. For eons, we didn't know much about the universe, but through advancements in science and technology, we're now able to travel back in time right to the point just after the Big Bang, to finally piece together its entire story. In the next 10 minutes, I'll be sharing that story with you.
Ah, to be able to understand the history of our universe, we have to start at the beginning of time. And time itself was born with the Big Bang. Contrary to what its name might suggest, the Big Bang was not an explosion. It can more precisely be described as the rapid expansion of space and time in all directions, releasing immense amounts of radiation.
In 1964, two Americans, astronomer Robert Wilson and astrophysicist Arno Penzias, stumbled upon a cryptic message traveling from the moment of creation itself. Their antenna in New Jersey picked up an odd buzzing sound that puzzled them. After eliminating all possible sources of interference, Wilson and Penzias figured out that they had just discovered the cosmic microwave background, or CMB, the thermal echo of the universe's explosive birth and the most crucial piece of evidence for the Big Bang.
Thanks to this ancient message, we know our universe came into existence 13.7 billion years ago, and it immediately began expanding at an exponential rate. This is known as the inflation Epoch. When it was less than a blink of an eye old—like a billionth of a trillionth of a trillionth of a second old—our universe underwent an astounding growth spurt, faster than the speed of light. Within a fraction of a second, it doubled in size at least 90 times.
But as it expanded, the energy released became more diluted. In just three minutes, the universe had cooled down enough to allow the first particles of matter to form, and the first light elements were created. Neutrons and protons began colliding with each other and formed hydrogen, helium, and lithium. Though the particles were formed, the intense heat from the moment of creation made it too hot for light to shine, and so our universe was plunged into a cosmic Dark Age.
For hundreds of millions of years, space was desolate and devoid of any planets, galaxies, or stars. Then, the age of re-ionization began, and light finally emerged from the darkness with the birth of the universe's first stars, known as Population 3 stars. These are believed to be made of the only ingredients available in the universe at the time: hydrogen, helium, and lithium. These stars are time capsules rich with information about our universe's earliest days, and with the James Webb Space Telescope, we can now look into them with greater detail than ever before.
About 1 billion years after the Big Bang, galaxies began to appear, and there are two theories on how they first came into existence. The first suggests that big clouds of gas and dust collapsed under their own gravitational pull, allowing stars to form and eventually galaxies. The second, which has gained momentum in recent years, suggests that galaxies formed when small lumps of matter kept clumping and swirling together until they eventually grew to the size we're familiar with today.
Our galaxy, the Milky Way, is roughly 13.6 billion years old and contains between 100 to 400 billion stars, spanning about 100,000 light years across. Astronomers are still working on charting the spiral structure of our galaxy. Although using infrared images from NASA's Spitzer Space Telescope, we've discovered that it is dominated by two arms wrapping off the ends of a central band of stars.
Stars and galaxies are still being created to this day, and astronomers estimate that there could be as many as 2 trillion galaxies spiraling through the black ocean of our universe. Four and a half billion years ago, a dense cloud of interstellar gas and dust kept swirling together as gravity pulled more and more material into the center. The pressure in the core was so great that hydrogen atoms began to form to make helium, releasing immense amounts of...