How were massive galaxies able to exist in the early years of the universe long before scientists say it should have been possible? According to a new study, the answer is incredibly simple: The galaxies weren't as big as we thought.
This finding finally answers a major mystery of astrophysics, which first cropped up thanks to the capabilities of NASA's James Webb Space Telescope. In other words, while the camera may add 10 pounds, the space telescope adds a massive number of stars that defy the laws of physics.
The findings of this study were published in the peer-reviewed academic periodical The Astronomical Journal.
Caution: Objects in the James Webb Space Telescope are smaller than they appear
Galaxies are gigantic accumulations of matter, being huge networks of stars, rocks, dust, gas, and more all formed into one enormous structure floating in space.
These galaxies are often ancient, many of them dating back to the earliest years of the universe. Over time, these galaxies grow and evolve, many times merging together and accreting more matter to form truly large galaxies. For example, the Milky Way Galaxy merged with several other galaxies, including the Sausage Galaxy and the still theorized Kraken Galaxy, both of which happened within the last 11 billion years. This made it the massive galaxy it is today, despite it having been formed some 13.6 billion years ago.
Because of this, when NASA was able to look at galaxies just a few hundred million years after the Big Bang thanks to the James Webb Space Telescope, they expected to find small galaxies in the early stages of their life.
However, that's not what they found. Instead, they discovered some truly enormous galaxies, ones that were so big - close in size to the Milky Way as it is now - that they defied all explanation, threatening to upend some of our foundational understandings of the universe.
One of the researchers behind these early studies on these impossible galaxies, Erica Nelson, summed up this puzzling discovery by saying, "It's bananas."
However, a new study by University of Texas at Austin graduate student Katherine Chworowsky may have solved this issue. Simply put, the galaxies in question aren't as big as they seem. They just look that way.
So how is that possible?
Well, the answer lies at the literal heart of these galaxies: The supermassive black holes that reside at their cores.
Supermassive black holes are commonly found at the center of most galaxies. The Milky Way, for instance, is home to Sagittarius A* at our galactic core. These enormous concentrations of gravity are impossibly hungry maws that pull in everything around them, letting nothing escape - not even light.
This last point will be incredibly confusing to the layperson since the study posits that these galaxies seem so huge because of the light emitted by these galactic cores.
But while this seems like a contradiction, it makes sense - it's just as complicated as astrophysics often is.
It must pull it in when supermassive black holes consume matter such as gas. This makes the gas move incredibly fast, with gas particles brushing against one another. This creates friction, and friction creates both heat and light. The more gas that is being consumed at this speed, the more light and heat gets emitted.
There are numerous examples of this happening throughout space. In fact, the brightest objects in existence, quasars, are caused by active supermassive black holes at the center of galaxies consuming so much matter that emits a brightness level unlike anything else.
So how does being brighter lead to scientists thinking galaxies are larger than they actually are?
Stars are also sources of brightness. Often, the brighter a galaxy is, the more stars there must be there. As such, the larger the galaxy, the brighter we often expect it to be. But if the brightness is caused by the supermassive black hole and not the number of stars, then scientists may have misjudged the actual size of the galaxies.
If this is true, then that's one mystery solved. Yes, there are still galaxies from the early years of the universe, but while many are indeed large, they aren't big enough to shatter the standard model of cosmology.
But there is still one lingering problem with all of this. The galaxies may not be impossibly large, but the sheer number of galaxies shouldn't be possible either.
However, this is nowhere near as science-shattering of a problem as the previous one. It simply means that more galaxies formed than we thought possible - and there is a theoretical explanation for this, too: Stars may have formed a lot faster back then. This, too, makes some sense, as the universe would likely have been denser back then before it had billions of years of expansion behind it.
Further research will be needed to confirm these findings as they further add to the growing body of literature, both adding to and challenging our knowledge of the universe.