For generations, the topic of extraterrestrial beings has fascinated society to a prodigious extent. To this day, it remains one of the most iconic subjects for sci-fi movies and media as a whole. Many people have also claimed to have witnessed an Unidentified Flying Objects (UFO) before, and there are numerous widespread conspiracy theories on aliens (case in point, those regarding the remote government establishment Area 51 hiding them from the public). However, it is important to note that none of these have been proven, and so far haven’t noticed any trace of other life in the universe.
In our local group alone, scientists have speculated there is at least a few million habitable planets that could potentially sustain life. Chances are that you, during at least one point in your life, have pondered if intelligent life thrives elsewhere in the universe. But if intelligent life does exist, why haven’t we seen any? Where are all the aliens? These notions lead us to the Fermi Paradox, named after physicist Enrico Fermi. In hopes of contacting extraterrestrial life or at least informing them about life on Earth, NASA has put a series of voyagers drifting across space. The two most notable ones were the Voyager 1 and 2, which each included a 12-inch golden record that contains sounds about the culture and nature of life on Earth. As of right now, we have not received any results. Check out their real-time location in interstellar space
It is important to note that any extraterrestrial life not within our local group of galaxies, is basically out of our grasp forever. Due to the expansion of the universe, other groups of galaxies are moving away from our group at an astronomically fast rate, and it would take billions of billions of years for any spacecraft of our current technology to reach them.
The Kardashev Scale
Developed by Nikolai Kardeshev in 1964, the Kardeshev scale can be used to measure a particular civilization’s technological success through its energy input and output. Based on the scale, a civilization of Type 1 is able to control and harness all the power available to their planet using renewable energy. Earth is estimated to be at around 0.7, as we still rely on fossil fuels, but we are expected to reach 1 in a few hundred years.
A type 2 civilization is capable of harnessing all the energy of its host star and its solar system. This can hypothetically be done by an invention known as a Dyson sphere, which envelops the entire star and absorbs its massive energy output for our own use. We are expected to reach this stage in thousands of years.
A type 3 civilization is one that is able to harness all the energy of its entire galaxy for itself, something Kardeshev estimated to happen in 100,000 years to one million years. By that time, who knows how advanced humans will be?
There are more levels to this scale, with type 4 being able to traverse and harness the entirety of the universe, but those are so technologically advanced that we cannot even seemingly imagine if and when humanity would reach that level.
Great Filters Throughout these levels of the Kardashev scale, lie great filters - which could explain everything. A filter is defined as a really hard obstacle for society to overcome, and a few examples could be asteroid impacts (which wiped off 90% of living species on earth before, including dinosaurs), nuclear war, or even global warming. So far, life on earth has passed many great filters and survived, but there are many major ones that have yet to come for us to surpass. One solution to the Fermi Paradox is that it is extremely rare for life to pass through certain filters, and there are very few alien civilizations that pass them. If this is true, then maybe life is very rare due to these filters, and there are no alien civilizations still thriving near us. Other potential solutions There are many more scenarios that can be used to solve the Fermi Paradox and explain why we haven’t seen extraterrestrial life, as explained through this infographic: A lot of these solutions include some sort of Type 3 or Type 4 civilization somehow influencing our lives without our knowledge, which could be true. Ignorance may also be bliss. Our own technology may also limit us, not being advanced enough or taking too much time. Or maybe, we truly are alone in this universe. Scientists still haven’t deciphered exactly how life forms arise and the “ingredients” needed, and maybe the conditions could be so specific and rare for life to develop that Earth is so far the only place in the universe with just the right conditions. The universe has existed for 13.9 billion years, perhaps numerous alien civilizations thrived and ended. All of these solutions are just theories though, and there is no way to know for sure what is true at this point in time. For now, let's just sit back, gaze at the stars, and admire the beauty of the universe. Citations: Davis, Matt. "Is the Universe a Graveyard? This Theory Suggests Humanity May Be Alone."Big Think, 10 Sept. 2018, https://bigthink.com/matt-davis/is-the-universe-a-graveyard-the-great-filter-theory-explains-why-we-havent-found-alien-life.
Hariharan, Raghav. "The Fermi Paradox | BLUEsat UNSW."BLUEsat UNSW, 18 Sept. 2018, https://bluesat.com.au/the-fermi-paradox/.
"The Fermi Paradox — Where Are All The Aliens? (1/2)."YouTube, https://www.youtube.com/watch?v=sNhhvQGsMEc. Accessed 28 June 2020.
"The Golden Record."NASA Jet Propulsion Laboratory California Institute of Technology NASA Jet Propulsion Laboratory California Institute of Technology Voyager Jet Propulsion Laboratory California Institute of Technology Jet Propulsion Laboratory California Institute of Technology Voyager, https://voyager.jpl.nasa.gov/golden-record/. Accessed 28 June 2020.
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