Exploring the Cosmos: The Tools That Let Us See the Universe
Starting today, Earth will be passing through a meteor shower. However, in the grand scope of astronomy, the human eye is a rather limited tool. Thankfully, increasingly powerful instruments are enabling us to delve deeper into the cosmos and further back in time, revealing new insights into the origins of the universe. Nowadays, scientists can…
Starting today, Earth will be passing through a meteor shower. However, in the grand scope of astronomy, the human eye is a rather limited tool. Thankfully, increasingly powerful instruments are enabling us to delve deeper into the cosmos and further back in time, revealing new insights into the origins of the universe. Nowadays, scientists can observe phenomena ranging from exoplanets orbiting distant stars to individual galaxies and even the broader universe.
“The universe is actually mostly empty space,” says Jean-Paul Kneib, a professor at EPFL’s Laboratory of Astrophysics. “There isn’t much that’s hidden.” The key, he explains, is knowing what you’re looking for, building the right instrument, and aiming it in the right direction—then doing some “housekeeping” to clear the view.
“Our galaxy sits in the foreground of our field of vision, blocking our view beyond it,” Kneib continues. “So if we want to map hydrogen in the early universe, for example, we first have to model this entire foreground, then remove it from our images until we detect a signal a million times fainter than the one emitted by the Milky Way.”
Back in Galileo’s time, astronomers could only sketch what they saw through their telescopes. But today, we can observe the universe in its entirety, right back to its beginnings, thanks to rapid advancements in astronomical instruments. And more breakthroughs are on the horizon.
The James Webb Space Telescope (JWST), launched in December 2021, aims to capture events from 13 billion years ago when the first stars and galaxies were forming. The Square Kilometre Array (SKA) radio telescope—currently under construction and set to be completed by the end of the decade—will probe even further back, to a time when the universe contained mostly hydrogen, the element that makes up 92% of all atoms.
“One effective way to detect this gas is to operate in the radio frequency range, which is exactly what the SKA will do,” says Kneib. “The goal is to detect a signal a million times smaller than the foreground signals.”
Another exciting project on the horizon is the Laser Interferometer Space Antenna (LISA), managed by the European Space Agency (ESA). Scheduled for launch in 2035, LISA will observe gravitational waves, offering insights into the growth of black holes and possibly the waves generated just after the Big Bang.
However, these advanced instruments wouldn’t be as effective without progress in other fields. “As it stands, we don’t yet have the software to process the data from the SKA,” Kneib notes, but he remains confident that advancements in computer science, AI, and processing power will soon close the gap. AI, in particular, is becoming invaluable for analyzing vast amounts of data, spotting anomalies, and even calculating the mass of galaxies.
“Using the gravitational lensing effect, where a massive object bends light from a distant source, scientists can now calculate the mass of galaxy clusters with one percent accuracy,” says Kneib. “We can even train AI models to identify distortions in images caused by gravitational lenses. Given that there are probably 200 billion galaxies in the universe, this is a huge help—even if we only measure the mass of one galaxy in every thousand.”
But do the images we see truly represent what’s out there? A well-known image from 2019 showed a donut-shaped ring of light surrounding a black hole. Would we see that ring if we got close enough?
“It wasn’t an optical photo,” Kneib explains. “It was a digital rendering. To observe the millimeter-wavelength signals emitted by the black hole, scientists combined data from multiple ground-based telescopes to create an image as if it were taken by a telescope the size of Earth. The final image was reconstructed using interferometry—a technique that measures wave interference.”
“But,” Kneib adds, “the image does correspond to a real signal related to the matter in the dust cloud surrounding the black hole. In simple terms, the dark area is the black hole, and the lighter area is the matter orbiting it.”
In astronomy, calculations are crucial, but visualization is just as important. Kneib, who can read the majestic image of the Lagoon Nebula, situated 4,000 light-years away, like a book, emphasizes this. “That image was produced using optical observations at different wavelengths to show various gases. While there’s some artistry involved in enhancing the colors, the image is also highly meaningful for physicists. The colors indicate the presence of different gases: red for hydrogen, blue for oxygen, and green for nitrogen. The compact, dark regions contain large amounts of dust, typically where stars form.”
Visualization becomes even more crucial when studying objects in more than two dimensions. “By studying the cosmos in three dimensions, we can measure the distance between celestial objects,” Kneib explains.
In early April, scientists working on the Dark Energy Spectroscopic Instrument (DESI) project, including astrophysicists from EPFL, announced they had created the largest-ever 3D map of galaxies and quasars in the universe.
But that’s not all: researchers are also exploring the universe in the fourth dimension—time—unlocking incredible possibilities for observing bright, transient phenomena. “For instance, we still don’t fully understand the origin of fast radio bursts, which are incredibly bright bursts of electromagnetic radiation that last only a few seconds at most, and sometimes just a fraction of a millisecond,” Kneib says.
Will we ever discover life on an exoplanet? Kneib believes it’s a real possibility. “With infrared interferometry, we might even be able to capture an image of a planet orbiting another star. The image might be blurry, but we could still observe and characterize features like clouds and surface variations. This could happen in the next 20 or 30 years.”
However, for some fundamental questions, images alone may not provide all the answers. Why is the universe expanding at an accelerating rate? Is it due to dark energy? Why is 80% of matter invisible? Are our understandings of gravity completely off? Future generations of astrophysicists will keep their eyes on the skies and their screens as they strive to unravel these deep cosmic mysteries.
Sharmeen Khan is a freelance writer at SciTech Magazine.
Sharmeen Khan is an expert in astrophysics and space technology, hailing from Pakistan. With a strong academic background and a passion for the cosmos, she has conducted extensive research in these fields. Sharmeen also gained valuable experience as an intern at SUPARCO, Pakistan's national space agency. Her work has been recognized in various scientific publications, and she is dedicated to advancing our understanding of space. Sharmeen is committed to inspiring the next generation of scientists through her outreach and educational efforts.