If you’re a fan of the Search for Extraterrestrial Intelligence (SETI) and the Fermi Paradox, then it’s likely you’ve heard of a concept known as the Great Filter. In brief, it states that life in the Universe may be doomed to extinction, either as a result of cataclysmic events or due to circumstances of its own making (i.e., nuclear war, climate change, etc.) In recent years, it has been the subject of a lot of talk and speculation, and not just in academic circles.

Stephen Hawking and Elon Musk have also weighed in on the issue, claiming that humanity’s only chance at long-term survival is to become “interplanetary.” Addressing this very possibility, a research team led by NASA’s Jet Propulsion Laboratory (JPL) recently created a timeline for potential human expansion beyond Earth. According to their findings, we have the potential of going interplanetary by the end of the century and intragalactic by the end of the 24th!

The paper that describes their findings was recently published in the July 27th, 2021, issue of Galaxies The team responsible was led by Jonathan H. Jiang, a Principal Scientist and group leader with NASA JPL’s Earth Science Section. He was joined by Kristen A. Fahy, a member of the Earth Science Section at NASA JPL, and Philip E. Rosen, a retired energy industry engineer.

The Great Filter was proposed in 1996 by Robin Hanson, an economist and research associate at Oxford University’s Future of Humanity Institute (FHI). In an essay titled “The Great Filter – Are We Almost Past It?” he proposed that there must be something in the grand scheme of biological evolution that prevents life from emerging and/or reaching a state of advanced technological development.

This was Hanson’s proposed resolution for why humanity’s attempts to find intelligent life – despite its assumed statistical probability – have failed thus far (aka. Fermi’s Paradox). But as Hanson makes clear in his paper, the Great Filter Hypothesis also has immense implications for humanity. Depending on where the Filter is located – an early stage of development or a later one – humanity may have already passed it or is nearing it (neither scenario is particularly reassuring).

For the sake of their study, Jiang and his colleagues proposed that since the end of World War II (and the development of nuclear weapons), humanity has entered a “Window of Peril” from which it has yet to extricate itself. Essentially, from this point onward, human beings have had the capacity to destroy themselves, either as a result of nuclear war, biowarfare, or anthropogenic climate change – which Hanson suggested as possible examples of “the Filter.”

To determine if humans have the potential to spread beyond Earth before we ruin it, wiping ourselves out, they created a foundational model that predicts the earliest possible launch dates for human-crewed missions from cis-lunar space to selected destinations throughout the Solar System and nearby stars. As Jiang explained to Universe Today via email:

“Initially, we looked at the relationship between reach and complexity of deep space missions as they relate to the development of computing power, expressed quantitatively as transistors per microprocessor, within the timeframe of the Space Age. Knowing the trend of computing power expressed in this easily quantifiable manner, along with some necessary assumptions, that trend was then used to help project trends for deep space missions into the future.”

Graphic representation of the relative distances between the nearest stars and the Sun. Barnard’s star is the second-closest star system to the Sun and the nearest single star to us. Credit: IEEC/Science-Wave/Guillem Ramisa

This raises another important concept, which is Moore’s Law, named for American engineer Gordon Moore. In 1965, Moore observed that the number of transistors on an integrated circuit (IC) could be expected to double every two years. Rather than being a “law” in the strictest scientific sense, this observation serves as a means of characterizing the exponential growth of computing in the latter half of the 20th century and into the 21st (coinciding with the Space Age).

As Jiang explained, their model was created with
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