You live during an incredibly special time in the history of the universe. Human beings have made discoveries that have answered crucial questions about our place in the universe and the age of the cosmos — discoveries that may have been impossible to make in the distant future.
For example, we have a reasonable amount of evidence to support the Big Bang theory, which describes the origin of our universe as a tiny concentration of super-hot, super-dense matter. At some point, roughly 12 to 14 billion years ago, an explosive force sparked the universe’s evolution into the tremendous expanse of time and space that has been — and continues to be expanding rapidly in all directions.
How Do We Know There Was a Big Bang?
The Big Bang was first theorized after the astronomer Edwin Hubble discovered that all the other galaxies we can see are moving away from us in all directions at great speeds. In the 1920s, the Belgian priest Georges Lemaître theorized that the universe started as a single atom, a theory supported not only by Hubble’s observations, but by the discovery of cosmic microwave background radiation (CMBR). CMBR is a faint glow of light that fills the entire universe and falls on Earth with equal intensity from every direction. It is the afterglow of the Big Bang, the residual heat from the ancient explosion.
CMBR is also the oldest light we can see. We know that light travels at a fixed speed of 299,792,458 meters per second, and because the universe is so fantastically large, the light from its furthest observable edges takes billions of years to reach us — which means that our images of the most distant visible stars are billions of years old. On a smaller scale, this principle means that since light reflected by the planet Jupiter takes about an hour to reach us, from Earth, we always see Jupiter as it was an hour in the past, not as it is in the present. Astronomy literally allows us to see backward in time.
A Special Time in the History of the Universe
It is crucial to study the CMBR — those who do so are essentially the archeologists of the stars. The radiation is like a fossil of the birth of the universe, before stars, planets and galaxies ever existed, when the universe was hot and violent instead of cold and dark. Early human astronomers realized that the preconceived notion that the Earth is the center of the universe wasn’t quite true — the Earth revolves around the sun, not the other way around.
However, even if our physical location in the universe is not special, our physical location in the observable universe has us at the center. No matter where you look in any direction, the CMBR is the same distance away. If you were to travel to a planet at the edge of our observable universe, the same phenomenon would happen — you’d still be at the center, but now you’d be able to see parts of the universe you couldn’t see from earth — and some parts would now be invisible.
Every planet is the center of its own universe. Space is homogenous and isotropic, meaning that at the largest scales, it’s all the same. No matter where you go, you’ll find stars and galaxies in every direction. We are very lucky to be making these discoveries about our cosmos now. Every moment, we are hurtling farther and farther away from other galaxies. In the future, their light will never reach Earth, and the CMBR will have cooled and redshifted so far that human astronomers won’t be able to detect it.
Imagine if we had not invented the telescope. Had we waited too long to look out into the stars, the secrets of the universe may have been lost to us forever. We still have many questions about the universe — what caused the Big Bang? What came before it, if anything?
We are on a spiritual journey to understand the origins of nature, the meaning of existence. Thanks to science and our fateful place in history, our unanswered questions may one day be answered.