Understanding our universe
NASA’s three big questions uncover details about the vast space we inhabit
October 14, 2022
From here on Earth, the inner workings of faraway galaxies might seem all too distant from our lives. Why are we looking into space when we have so many problems to solve here? Why then does the National Aeronautics and Space Administration (NASA) invest billions of dollars year after year in spacecraft and research, constantly trying to make sense of the endless space that surrounds us?
To understand our significance on Earth is to understand our history; to do that, we must first go back to where it all began, 13.8 billion years ago.
How did we get here?
The universe started as nothing but an infinitely small, infinitely dense ball of matter. Amazingly, every object in our universe emerged from this tiny point, expanding to a size so large that no one would be capable of measuring it. Despite our constantly improving space technology and countless research efforts, scientists can only speculate at best on how we got here.
“In the earliest moments, the universe expanded outwards way faster than you would think in just tiny fractions of a second,” upper school physics teacher Chris Spenner said. “We still haven’t figured out what really happened at that point; our laws of physics don’t accurately describe that as far as we know.”
Of all the techniques used to peel back the curtain of time on our universe, scientists have found the most success studying the radiation emitted by the Big Bang. This radiation, known as the Cosmic Microwave Background (CMB), represents the residual heat left behind from the universe’s expansion. Although the CMB is invisible to the naked eye, mapping it with the right equipment allows scientists to look back on our universe’s evolution to as far as just 300,000 years after its creation.
“Scientists look at the early release of energy and light that’s been traveling the universe all this time to work backwards and figure out how the early universe was structured,” Spenner said. “There are scientists who frequently go to the South Pole, for example, to reliably conduct these experiments.”
One such experiment, known as the Balloon Observations of Millimetric Extragalactic Radiation and Geophysics (BOOMERANG) experiment, launched in 1998 and was one of the first to accurately model the early structure of our universe. By sending three balloons equipped with telescopes to circumnavigate the South Pole, the researchers of the BOOMERANG experiment collected the largest, most accurate set of CMB data we have to date.
After the Big Bang, the universe is dominated by theories that we’re pretty confident in, like general relativity and quantum mechanics. We can use these and the distribution of energy and matter in the early universe to model how long it would take for the first stars and galaxies to form — Chris Spenner, physics teacher
Although most details surrounding the Big Bang will likely remain foggy for the foreseeable future, scientists today have an accurate grasp on how most celestial objects are formed, according to Spenner.
“After the Big Bang, the universe is dominated by theories that we’re pretty confident in, like general relativity and quantum mechanics,” Spenner said. “We can use these and the distribution of energy and matter in the early universe to model how long it would take for the first stars and galaxies to form.”
Most solar systems form when gravity causes clouds of dust and gas to coalesce and collapse, creating planets and stars. As smaller planets either leave or start orbiting larger planets as moons, the solar system turns into somewhat of a self contained system, where outer planets protect the inner ones by deflecting objects that might otherwise harm the smaller planets. Not all solar systems may form like ours did; in fact, researchers have discovered several solar systems with two or even three stars at their center.
“There’s so many different types of solar systems out there,” Astronomy Club Officer Kaitlyn Wang (11) said. “There are ones with binary stars rotating against each other and ones with black holes at the center. Our solar system is the most basic kind, and there’s so much to explore.”
Despite our ever-expanding knowledge of our solar system and the structure of our universe, there are still objects out there that don’t fit our current theories and laws of physics: namely, dark matter and dark energy. Scientists believe that both play a role in the constant accelerating expansion of the universe, but beyond that they remain a complete mystery.
“Right now our explanation is just that there’s this thing we don’t understand, but we can sense the effect it has on space and time,” Kaitlyn said. “The terms [dark matter and dark energy] are just a way to describe something that we don’t understand yet.”
How does the universe work?
Despite the turbulent nature of their creation, stars and galaxies follow quite stable life cycles often lasting billions of years. While galaxies vary widely with respect to how they form and disappear, all stars follow similarly structured life cycles from birth to death. Every star in our universe relies on hydrogen to shine, so their life cycle ends when that supply of hydrogen depletes. Smaller stars like the sun will gradually grow dimmer until they stop shining, while larger stars will explode as supernovas at the end of their life cycles.
“Over the course of my lifetime, the night sky isn’t really going to change substantially,” Spenner said. “There might be the occasional supernova or comet, which are surprising but also kind of expected to happen. On a bigger scale, things are definitely still changing; galaxies are constantly evolving, stars are being born and dying.”
One of the most concerning changes discovered by scientists in recent years is the expansion of the universe. Not only has the universe been constantly growing larger since the Big Bang, but studies have shown that the expansion is happening at an accelerating rate, much faster than even the speed of light.
“When scientists detected and observed the CMB radiation, it showed that the universe was expanding,” Kaitlyn said. “When they looked at things that were far away, the wavelengths they saw became longer because they were moving away from us. This effect, redshift, tells us that things farther away appear more red because red is the longest wavelength of light.”
As the universe continues to expand, with it comes no new galaxies or stars. As a result, the ones we have now will gradually drift farther away from us into the outer edges of our universe, leaving us with nothing to see except an empty night sky billions of years into the future.
Currently, scientists calculate the total number of galaxies in our universe to be somewhere between 100 and 200 billion. They arrived at this rough estimation by employing telescopes to take snapshots of the night sky and counting the galaxies contained within that tiny sliver of space. Compiling over 10 years of photos from the Hubble Space Telescope, researchers can study the distance between galaxies in each image and project their observations onto the entire universe.
“If you viewed the contents of the universe with sufficiently poor vision, it would appear roughly the same everywhere and in every direction,” NASA said. “That is, the matter in the universe is homogeneous when averaged over very large scales.”
Out of the billions of galaxies in our universe, each one contains its own unique set of stars and exoplanets, waiting to be discovered. One by one, scientists are just now beginning to uncover the secrets of these planets, all the while in search for the one thing deemed so scientifically probable yet still unattainable: life.
Are we alone?
In an inky void of darkness, hidden within an isolated alcove of the Milky Way galaxy, life evolves. And for all we know, our planet is its sole occurrence, a cosmic anomaly of this universe. As we lie on the Earth’s surface, gazing up into the infinite abyss of space, human curiosity compels the question — might there be another us?
“By observation, nature never does anything one off ever,” said upper school astronomy teacher Dr. Eric Nelson. “If you look at where we are, there’s no one of a kind anything that nature produces. So I would expect that life would not be a one-of-a-kind event on Earth.”
Indeed, Earth does not harbor life because it is special — far from it. According to a University of British Columbia analysis, an estimated 6 billion Earth-like planets are scattered throughout our galaxy, each with optimal conditions for producing life. Yet each planet we’ve examined has come up empty. Perhaps we are looking for the wrong signs.
For the last few decades, research has been primarily focused on searching other planets for technosignatures, chemical and electromagnetic signals caused by technological activity. Even light years away in space, these technosignatures are easily observable, a telltale sign of living organisms. As we scour through the universe, examining the billions of planets that might conceal life, technosignatures are our primary target. However, this strategy assumes that all life mirrors us, with sprawling cities and bustling machinery – such may not be the case.
“Intelligent life is infrequent,” Dr. Nelson said. “If you look at the history of the Earth, life has been evolving for about four billion years, and the dinosaurs dominated for 250 million years. Dinosaurs would not have gotten anybody’s attention unless you did a fly by. Nobody would have known they were here because they did not become technologically advanced.”
While technosignatures are unable to detect primitive lifeforms, given the amount of planets that may contain life, some scientists are optimistic we will eventually discover another intelligent civilization. A driving factor of our estimates on the probability for intelligent life is the Drake Equation. Utilizing constants that range from definitive, like the average rate of star formation, to highly ambiguous, like the fraction of intelligent lifeforms that develop interstellar communication, the Drake Equation has been the starting point of extraterrestrial life research for decades. While the equation’s creator Frank Drake passed away on Sept. 9, his work continues to direct our search.
As for non-intelligent lifeforms, they may be closer than calculated estimates suggest. NASA’s Mars rover Perseverance has begun collecting rock samples in early 2021, many of which show promising signs of life. Given that such a finding would be unlikely, scientists will need to conduct additional examination back on Earth. As for now, only time will tell how this discovery shapes the search for extraterrestrial life.
While this progress gives hope for the future, many additional technological advancements could further our understanding of life in space. The question is, which ones would be most impactful?
“[Traveling at] warp speed, if we could do that, but being able to actually travel someplace farther outside our galaxy and being able to hear transmitted [messages],” said aeronautics club adviser Anthony Silk.
Though a warp drive would certainly be helpful, recent developments have also had a tremendous impact. The launch of the James Webb Space Telescope earlier this year is one of the premier advancements in recent history, expanding the potential scope of our search. Since initially releasing images in July, the telescope has pictured a multitude of intergalactic landmarks, notably capturing the clearest image of Neptune’s rings in 30 years. With the ability to produce such high-resolution photos, illuminating even the most hidden crevices of space, this novel technology may be one of the keys to unlocking the secrets of extraterrestrial life.
There’s an adage that says that a ship can stay safe if it stays in the harbor. But that’s not why ships are built. You got to send them out, you’ve got to take those risks. Otherwise, we’ll never get out of the harbor, never do anything — Dr. Eric Nelson, astronomy teacher
While advancements in technology can allow us to potentially discover such intelligent lifeforms, we might not be prepared for the ensuing ramifications. Movie cliches of being invaded by monstrous extraterrestrials are far-fetched, but if we happen to uncover a more technologically advanced civilization in the deep recesses of space, there may be cause for concern.
“The human history of when a more advanced technological civilization runs across a less advanced one has never worked favorably for the less advanced culture, ever,” Dr. Nelson said. “I don’t think there’s an exception to that.”
Regardless of intent, more developed civilizations can destroy less developed ones without ever being actively hostile. Consider humanity’s impact on the natural world. From a squirrel’s perspective, it is inconceivable to cut down a tree. Yet, we clear forests not out of hostility towards squirrels, but out of a desire for resources and land, motives incomprehensible to them. Likewise, if we encountered a more technologically advanced civilization, they may have incomprensible motives that inadvertently harm us.
Foreign pathogens pose yet another issue. Each planet has specialized microbes that function in its biosphere, and contacting extraterrestrial lifeforms holds a high risk of transmission. In an interconnected age where diseases can cause economic shutdowns across the globe, an interstellar virus would have unfathomable consequences. With no Earth-based precedent to conduct research or develop antibodies from, such a virus could easily eradicate the human population.
Then why should we search, or should we be searching at all? Should the potential dangers be enough to dissuade us?
“There’s an adage that says that a ship can stay safe if it stays in the harbor,” Dr. Nelson said. “But that’s not why ships are built. You got to send them out, you’ve got to take those risks. Otherwise, we’ll never get out of the harbor, never do anything.”
This mentality drives scientists’ search for extraterrestrial life. We pursue knowledge relentlessly in the hopes that our discoveries will expand our understanding about the world we live in. For, at the heart of scientific discovery lies the intrinsically human desire to explore the unexplored, to comprehend the incomprehensible. It is this unquenchable curiosity that has brought us thus far, and what motivates us to pursue the next chapter of our interstellar tale.
“[Searching for life] could tell us more about how the universe works,” Silk said. “And who knows what it could actually be? Sometimes you don’t know what you’re looking for until you actually find it, so some people are searching just to see what’s out there.”
Over a millenia ago, the first European seafarers sailed to North America. Harrowing tales accompanied their journey, telling of mythical beasts and demonic fiends that might wish them ill. Yet they embarked nonetheless, traveling into uncharted waters with no knowledge of what might await them. The search for extraterrestrial life is the same. We are unaware of what we may discover, and what the potential impact may be. But if we do find life, our world will be forever changed.
Our desire for understanding is too strong, the potential for impact is too great. Entranced by the siren song of the universe, we cannot help but wonder at the enigmatic nature of life. It is a clarion call to our inherent curiosity, a culmination of everything that science stands for. It is what makes us human
“If [extraterrestrial lifeforms] turn out to be superior to us, in terms of technology or other [advancements], then that would probably be a wake-up call that we’re not the most advanced out there,” Astronomy Club member Audrey Cheng (10) said.
Human-centric thinking remains prevalent in many communities, beliefs that the universe centers around humanity. Discovering life in space would eliminate this perspective, shattering this idealistic lens that we view ourselves through. With the potential for such great disruption, our curiosity urges us to continue searching, to ascertain a definitive answer regardless of the possible dangers.We have only explored but a small fraction of the known universe, searching on the slight off-chance that we may find something. But according to NASA, despite the improbable odds to find life, how could we possibly not search? Our desire for understanding is too strong, the potential for impact is too great. Entranced by the siren song of the universe, we cannot help but wonder at the enigmatic nature of life. It is a clarion call to our inherent curiosity, a culmination of everything that science stands for. It is what makes us human.