If for some reason the existential risks mentioned in the last post made you feel insignificant in anyway, let the following serve as consolation and reason to feel significant (and quite literally “central”) to the universe as human beings existing in this period of time.

From a temporal perspective of the evolution of the universe, we live close to a point in time where the universe is switching over from slowing down its expansion to speeding up its expansion. This is important from an observational standpoint, because as the expansion continues distant galaxies and regions of the universe will be disappearing from sight leaving the Milky Way and some of its closest neighbors in isolation. After a sufficient amount of time, light will no longer be able to reach us in ways that permit practical observation of these distant regions. This also includes light that gives evidence of the “big bang” via the cosmic background radiation. Thus, new astronomers in the future may not even be able to observe other galaxies to convince them that they live in a universe with many others. It is also somewhat peculiar that we exist in a period of time where the expansion is neither too weak nor too strong to even detect in the first place. In fact, this is essentially the only time period in the universe’s evolution where a detection of this expansion and the existence of dark energy could be possible! [Read more about this here]

Moving from this larger cosmic scale to our Solar System, there are still more ways we are living in a central moment in time. Within an order of magnitude, we exist halfway through the main life of our Solar System, which began about 4.5 billion years ago and will end in 5-6 billion years when the Sun turns into a red giant and ultimately a white dwarf.

Moreover, we also exist about halfway through the period of time on Earth which permits the survival of life like us. In the past, until about half a billion years ago, the Sun was too faint and the Earth lacked an oxygen-rich atmosphere. In the next half a billion years, the Sun’s luminosity will be increasing causing temperatures on Earth to rise high enough to where the Earth’s oceans will evaporate away and the atmosphere will escape into outer space. This stage will have some drastic consequence’s for Earth in the future, but goes to show that we are currently in the most suitable period for life on Earth.

Relative to the more recent evolution of humans on Earth, there is one more way we are in a pivotal moment in time. We are at the end of an exponential expansion in human population. In the past century, the human population quadrupled, and doubled twice in just the last 100 years. This is the first time this has ever happened in history, and will likely be the last since there are strong doubts that Earth could even handle such a large capacity.

Whether you want to regard these as mere coincidences, or formulate some kind of anthropic arguments as justification, know that this all really happens to be the case. Perhaps we can let this increase our awareness and inspire us to live accordingly.

Most of the ideas mentioned here are discussed and explored more thoroughly in The View from the Center of the Universe by Joel Primack and Nancy Abrams.