We are a Probability, in a Probable Universe
“We are an impossibility, in an impossible universe” — Ray Bradbury
Ray Bradbury was an American author and screenwriter, known for his ability to weave science and fiction together in a novel way, whilst still maintaining an air of realism.¹ Often, he was quoted for saying the above, in direct relation to the awe that is humanity, as well as circumstances that led directly to us. As we are the only humans known to exist, he expressed a sense of rarity in the human condition. However, as he isn’t directly involved in STEM, I do wonder how accurate his statement is- exactly how impossible are we?
First of all, I think that it is necessary to elucidate on the differences between improbable and impossible. A quick google search defines impossible as, “incapable of being, or of occurring” whilst it describes improbable as, “unlikely to be true or to occur”. Within the context of life- and given that we are certain of its existence on earth, I think that Bradbury should have referred to us as a probability- as whilst there is a probability associated with the existence of human life, it is certainly possible.
Taking a closer look at Bradbury’s claim, we can then consider whether our universe is as impossible as he deemed it to be. In fact, according to a study published in 2014, scientists working on the Big Bang Theory have indicated that the cosmic inflation caused by the speeding up of the universe coupled with the Higgs Boson field could have created small fluctuations in the early stages of the universe formation. This would have served to prevent the outward expansion of our universe- that is, humanity and everything else in our universe would have ceased to exist.² Certainly, this did not happen but brings forward that there is a certain probability associated with the existence of our universe. Therefore, maybe Bradley should have indicated that our universe is a probability- not an impossibility.
So, Bradley’s quote should have gone along the lines of, ”We are a probability in a probable universe”. Now, put in such terms, the quote seems less jarring- and leads more to the fact that us being here is very well possible. However, to gain a better understanding of our probability, we should consider the theories on our origin- and by ‘our’, I refer to the current theories on the origin of life on planet earth. First, let's take a look at the well-known theory- the Anthropic principle which is split into two forms- the Weak Anthropic Principle and the Strong Anthropic Principle. According to the Australian physicist Brandon Carter, the former could be understood as, “We must be prepared to take account of the fact that our location in the Universe is necessarily privileged to the extent of being compatible with our existence as observers.”, whilst for the latter, he stated that, “The Universe (and hence the fundamental parameters on which it depends) must be as to admit the creation of observers within it at some stage.”.³ Both forms simply state that the universe exists in a way that allows observers to come into existence. It does not indicate there being some force bending the universe to will the existence of life, nor does it infer that this is the only way that the universe could have evolved. Often, the Anthropic Principle is used incorrectly- in a sort of Post hoc ergo propter hoc argument for claiming that the universe must be the way it is because humanity is here, adding a sense of specialty to humans, based on the idea that everything was created for us.⁴ However, the Anthropic principle simply states that the origin of the universe, its evolution, and universal constants, which result in the formation of life are just as they are. When put in the context of Bradbury’s quote, it highlights his inaccuracy- we are not as impossible as we seem, nor is the universe, but rather we are most likely a byproduct of the evolution of the universe.
Beyond the Anthropic principle, numerous theories have been put forward on the exact origin of life, one building on the other as scientists begin to understand the exact requirements for life. At first, biologists assumed the theory of abiogenesis (or Primordial Soup Theory), which stated that, given the right conditions and presence of certain compounds, complex organic molecules can form which, were considered to be the starting point for life.
The theory was tested by Stanley Miller and Harold Urey, where they were able to show the production of such molecules by using a model simulating early earth conditions- and whose experimental set up can be seen in figure 2. However, as biologists further understood the requirements of life, they soon realized that this theory did not sufficiently solve all of the problems that would be met in creating life. The main problem with the Primordial Soup Theory, which did not explain how cells became ‘alive’, was solved by the Hydrothermal Vent theory which solved the need for a source of energy. Recent advancements, however, have gone a step further and proposed that a Nuclear Geyser System (as seen in figure 3) would be better suited as it provided not only thermal energy but ionizing energy, as well as other known requirements for life.⁵ Therefore, given the numerous theories on the origin of life on earth, as well as the clear presence of the materials required for life, we could begin to conclude that our presence on Earth is much more of a probability than an impossibility.
The Anthropic Principle along with the numerous theories we have on the origin of life gives the impression that the probability of life’s existence is fairly high. It almost makes it seem that what happened on earth, could have easily have happened anywhere else. However, I believe that we should also consider additional external conditions needed for life, and in looking at that we can continue to determine just how probable we really are. For example, looking at our solar system, and the placement of its planets, we could say that earth is considerably unique as it appears to be situated at just the right position for life. This highlights the notion that there must be some dynamic parameter that the earth met to have been able to support life. Scientists have actually coined a term for this phenomenon- the “Goldilocks Zone”, fondly named after the children's fable. It refers to the habitable zone around a star where temperature and pressure are such that liquid water is stable on the surface of the planet⁶. In a sense, it maps out the zones around the star capable of producing and maintaining life, i.e., the fertile zones. We should understand, however, that such a notion does not bring immediate importance to the human race. The Goldilocks zone simply illustrates that the intricate structure that is life requires another layer of conditions to be met for its emergence⁷.
Whether this adds to our ‘impossibility’ (or probability) relies on the fact that we would need to consider the numerous habitable zones we have found outside of our solar system. Known as exo-planets, these are objects that orbit stars, forming external solar systems of their own. Due to better observational technologies, NASA has an extensive repository on these extrasolar planets, where they have found at least ten that have conditions very similar to that of earth. Of course, we have yet to find life on another planet, but we should also remind ourselves that the furthest manned flight has gone is to the moon- and in general, our crafts have barely gone beyond the solar system. Even our best observational methods cannot traverse the surface of a planet and determine whether early life is there or not. Nevertheless, the existence of exo-planets deemed suitable for life does in fact lessen the rarity of the origin of life. Again, still, not as impossible as Bradbury had it seem.
However, I do wonder that, in giving his quote, maybe Bradbury was referring to the existence of not just life, but intelligent life- like humans. In this context, I can begin to understand his expression. In fact, a recent study published in 2020 by PNAS- Proceedings of the National Academy of Sciences in the United States of America, used a simple statistical method- Bayesian analysis, to determine the statistical probability of the emergence of intelligent life. Based on the fact that although life has existed on earth for approximately 300 million years whilst human life-what we deem intelligent life, has only come into existence recently, the study infers that given the right conditions, it is very probable that life can come into existence on some Earth-like planet in a distant solar system. However, in the context of intelligent life, the study reports an almost 50:50 probability, indicating that if we were to reverse the clocks and rerun earth’s evolution, we may very well not be here. Of course, the analysis could not have provided statistical absolutes, but rather tried to provide a proxy of how likely what happened on earth could happen again⁸. With this in mind, and in the context of Bradbury’s quote, and his emphasis on our impossibility, one would still refer to intelligent life as a probability, as although the study indicates the relative rarity of intelligent extraterrestrial life, it emphasizes its lack of absolute accuracy due to having a sample size of 1- earth, as the only source of information for such a question.
Therefore, looking at Bradbury’s quote from varying angles, I believe that he may have exaggerated in his description of the existence of life on our planet, and the existence of the universe. This does not come as a surprise, as Ray Bradbury is no Astrophysicist- or Astrobiologist, and it is quite easy to get sucked into the hype of how special humans and ‘our’ universe is. However, I do believe that given the literature, whilst there may be a certain level of ‘rarity’ to intelligent life, the existence of life in our universe may not have been as impossible as Bradbury made it seem. Hence, I believe that for accuracy’s sake, rewording his quote as ’We are a probability in a probable universe.’ fits much better with what we currently understand on the origin of life, and our universe.
: We are an impossibility in an impossible universe.(N.d.). https://quoteinvestigator.com/2016/06/06/impossibility/
:Shah, Tina (June 2014).Our universe is impossible and we shouldn’t exist, Higgs-boson scientist says. https://www.techtimes.com/articles/9131/20140626/our-universe-is-impossible-and-we-shouldnt-exist-higgs-boson-scientist-says.htm
:Carter, B. 1974. “Large number coincidences and the anthropic principle in cosmology.” In Confrontation of Cosmological Theories with Observational Data, Proceedings of the Symposium, Krakow, Poland, September 10–12, 1973. (A75–21826 08–90) Dordrecht, D. Reidel Publishing Co., 1974, p. 291–298.
:Siegel, Ethan (Jan. 2017).How The Anthropic Principle Became The Most Abused Idea In Science. https://www.forbes.com/sites/startswithabang/2017/01/26/how-the-anthropic-principle-became-the-most-abused-idea-in-science/?sh=675a8617d690
: Maruyama, Shigenori, Ken Kurokawa, Toshikazu Ebisuzaki, Yusuke Sawaki, Konomi Suda, and M. Santosh. 2019. “Nine Requirements for the Origin of Earth’s Life: Not at the Hydrothermal Vent, but in a Nuclear Geyser System.” Geoscience Frontiers 10 (4). Elsevier B.V.: 1337–57. doi:10.1016/j.gsf.2018.09.011.
: NASA- Exoplanet Exploration Program, What is the habitable zone or ”Goldilocks zone”? — Exoplanet Exploration: Planets Beyond our Solar System(n.d.). https://exoplanets.nasa.gov/faq/15/what-is-the-habitable-zone-or-goldilocks-zone/.
: Scharf, Caleb (July 2014). Is Earth’s Life Unique in the Universe? https://www.scientificamerican.com/article/is-earth-s-life-unique-in-the-universe/
: Kipping, David. An objective Bayesian analysis of life’s early start and our late arrival. Proceedings of the National Academy of Sciences Jun 2020, 117 (22) 11995–12003; DOI:10.1073/pnas.1921655117
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