Astronomy is possibly one of the best hobbies to explore. The standard approach is to buy a telescope and find a convenient dark sky for stargazing. Telescopes can be rather pricey, so amateur astronomers can observe the sky via binoculars or unaided eyes, along with using stargazing programs.
Astronomy is one of the oldest sciences. As civilizations formed, early astronomers began to map the positions of the stars and planets, leading to the development of astrometry. From careful geometric analyses, Aristarchus measured the sizes and distances of the moon and sun and proposed the heliocentric model that was rejected by his contemporaries.
While astronomy became stagnant in medieval Europe, Islamic and Asian astronomers made significant discoveries and established numerous observatories. The Persian astronomer Azophi discovered the Andromeda galaxy, and Arabic and Chinese astronomers discovered the brightest supernova named SN 1006. Moreover, numerous astronomers introduced Arabic names for individual stars.
During the Renaissance and Enlightenment, heliocentrism became accepted, and celestial mechanics was developed to quantify the motions of astronomical objects. Galileo Galilei and Johannes Kepler improved the Dutch refracting telescope to strengthen astronomical observations. Isaac Newton developed a reflecting telescope to eliminate aberrations and increase apertures for viewing.
Astronomy soon became a subset of physics, as astronomers and astrophysicists tackled problems involving planetary science, stellar dynamics, galactic and extragalactic astronomy and cosmology. Inspired by Renaissance telescopes, amateur astronomers eagerly built new telescopes combining reflective and refractive properties to optimize sky observations.
What makes astronomy particularly awesome is its incessant desire to explore the unknown, which is reasonable considering that the universe itself is expanding at an accelerating pace. Modern astronomical catalogs are massive, containing extensive physical and chemical properties of observed planets, stars and galaxies.
Equally amazing are astronomy’s interconnections with other disciplines, such as biology, chemistry, geology, philosophy and history. A predominant issue that remains relevant today is the existence of extraterrestrial life. In an ever-expanding universe with countless unseen planets, declaring that the Earth is the only source of life, including intelligent life, is unlikely.
Renowned physicist Enrico Fermi argued that any intelligent extraterrestrial civilization with some rocket technology and ambitious imperialist desire could colonize the entire galaxy, which means that some intelligent species could have visited Earth. The absence of evidence of any sign of intelligence led to the “Fermi paradox”: if intelligent life is common, then why do we see no evidence of other intelligent life?
Astronomer Frank Drake provided a reductionist argument to quantify the Fermi paradox. He speculated that the number of advanced technological civilizations in the Milky Way Galaxy is the product of seven terms.
The first three terms in the Drake equation are empirical: the number of stars in the Milky Way Galaxy, the fraction of stars that have planets and the average number of planets per planetary system that can sustain life.
The last four terms focus on life that actually develops in planets, the formation of intelligent life, the creation of technological civilizations and the civilization survivability. These terms are speculative and philosophical, resulting in zero to a million advanced technological civilizations in the Milky Way Galaxy.
Since the Fermi paradox suggests that no signs of intelligence were detected, the Drake equation implies that the fraction of intelligent life is very low. Thus, the paradox is resolved in two different ways: either no civilization exists or intelligence is necessarily destructive.
Peter Ward and Donald Brownlee assert that the emergence of complex life on Earth required a rare combination of geological and astrophysical events. In their so-called Rare Earth hypothesis, the scientists argue that complex life requires the correct astronomical parameters, plate tectonics, a large moon, a stable orbit and an evolutionary trigger.
It’s important to note that Ward and Brownlee strongly believe that simple, bacterial life is common, but complex life is rare. Nonetheless, the Rare Earth hypothesis tries to extrapolate Earth’s history to establish the criteria for complex life, as observed by the unique requirements for plate tectonics and a large moon.
First, the Earth isn’t rare considering new planets with Earthlike conditions are being discovered. Second, planets have different atmospheric conditions, so selection pressures can form and sustain complex life with alternative biochemistry, which implies that oxygen is not a requirement for life.
The second hypothesis dictates that intelligent civilizations self-destruct or annihilate other societies in short timescales. Such catastrophes can occur from nuclear warfare, climate change, population instability and resource breakdown. Technological singularity can occur, whereby intelligent species with advanced technology may destroy other signs of intelligence or create superintelligent machines to destroy themselves.
Except for singularity, the catastrophic factors driving the eradication of intelligent civilizations are extrapolated from human-related ailments. If civilizations smarter than human civilizations were to exist, extraterrestrials would use reason and sound judgement to avoid wars, superintelligent competitions and economic collapse. Such civilizations would be sustainable.
Hypothesizing the biology and culture of intelligent civilizations is a matter of science fiction. A physical solution to the Fermi paradox is that distances from Earth to other planets can be vast, spanning over several million light-years. With an accelerating universe, it becomes increasingly difficult to contact nearby planets, much less planets in adjacent galaxies.
Even more possibilities exist. Perhaps humans haven’t been searching long enough. Humans may fail to distinguish alien languages from noise, which means they aren’t listening carefully. Some intelligent civilizations are non-technological, while singularity may allow other societies to communicate in abstract ways, such as through black holes and cosmic rays.
Just thinking about extraterrestrial life is astounding. The eminent astronomer Carl Sagan proposed that advanced extraterrestrial civilizations could store their complete information and knowledge into the Encyclopedia Galactica (a hypothetical version of Encyclopedia Britannica).
Despite the complexity of the Fermi paradox, the search for extraterrestrial life (SETI) should continue in order to enhance learning on the cosmic neighborhood. By using inexpensive radio and microwave astronomy, the cosmos can be explored extensively to discover any technological remnants or artifacts.
SETI research was actively promoted by astronomers and science fiction writers. Subjected to vicious attacks from angry politicians, SETI research was removed from NASA budget in 1981 but was restored in 1982 thanks to Sagan’s intervention. Sadly, in 1994, Congress canceled the NASA SETI program, so SETI is now privately funded.
Science is distinguished from philosophy in that empirical evidence is required to verify theoretical claims. Furthermore, a small probability of finding intelligent civilizations elsewhere is still better than giving up. Congress must be cognizant of scientific research and use the rare opportunity in being productive by funding SETI.
Badri Karthikeyan is a biology major at Drexel University. He can be contacted at [email protected].