As a science communicator, I don't think a week goes by without a press release popping up in my inbox informing me of astronomers having discovered some new record-breaking object.
Sometimes it is the smallest planet ever discovered or the most iron-deficient star. But a very common claim is a distance record: for example, the farthest galaxy from Earth ever seen.
When it comes to record-breakers of this nature, I have complex feelings shaped by decades of writing about them. Such announcements need to be analyzed carefully because sometimes they are not that big of a deal, but sometimes they signal dramatic changes in what we can do or understand.
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Distance records are an excellent indicator of the current state of astronomy. Finding very distant galaxies is difficult. In general, objects become smaller and fainter with distance (although sometimes strange exceptions happen), so to detect them at all, you need huge telescopes.
Then comes the difficulty of actually determining their distance. We can't do this directly; we can't jump on board a starship Enterprise and keep your eyes on the odometer as we warp our way there. That's why we measure distances in other ways.
The most common method is observing the redshift: the Universe is expanding, and at the same time space sweeps away galaxies. Light leaving a distant galaxy loses energy as it fights expansion, so by the time it reaches us, its wavelength has been stretched, which astronomers call redshift. For historical (and mathematical) reasons, we say that a photon whose wavelength is doubled has a redshift of one; if the wavelength is three times longer, the redshift is two, and so on. Since the speed at which a galaxy is moving away from us is related to its distance, determining the galaxy's redshift can be used to measure this distance.
It's also not an easy task, since converting redshift to distance requires understanding some rather mysterious features of the universe—like how much normal matter, dark matter, and dark energy it contains, to name a few. But we have accurate enough numbers for these parameters to get a decent idea of the distances.
And this is where the “record holder” really appears. Sometimes I see an article or announcement about a new galaxy that beats the previous record, but it will have a redshift of, say, 7.34, whereas the previous record was 7.33. This difference is quite small! And depending on your preferred values of cosmic parameters, the difference could be as little as a million light years. In our example of an object with a redshift of 7.34, we are talking about a distance of about 13 billion light years, so the record holder is definitely not crossing another galaxy. Besides, simply finding a galaxy that triumphs over another via its nose (or spiral arm, I guess) doesn't really tell us all that much about the nature of the cosmos.
On the other hand, there are cases and such records do tell us something important.
When I was working on the Hubble Space Telescope in the late 1990s, It has become common to find objects with redshifts around 6.0. because the observatory was designed in part to be able to see extremely distant galaxies. Some objects have been discovered that could be even more distantbut many of them were difficult to confirm. Over time, astronomers using Hubble and other telescopes have been able to see galaxies even further away, using clever techniques such as random gravitational lensing.
Then, in 2021, our capabilities took a giant leap with the launch of James Webb Space Telescope. Its infrared eye is more sensitive to high-redshift objects, and its huge 6.5-meter mirror outperforms Hubble's smaller optics at collecting photons. Soon, papers were published claiming galaxies at redshifts of 10, 11, and even higher—and while many of these preliminary measurements turned out to be false, some were eventually confirmed at redshifts greater than 14. This is one of those cases where the record holder is important: it tells us that we have a new way of observing the cosmos, which usually leads to a new era of astronomical discovery.
Whatever it's worth at the time of this writing. The current record holder is a very bright red blob galaxy called MoM-z14 at a redshift of 14.44.. But by the time you read this, who knows?
These records also have important scientific significance. For example, light travels very quickly, but not indefinitely. The light from these far-off galaxies takes billions of years to reach us, meaning that the further away they are, the earlier in the cosmic timeline we see them. Any new entry means that we have added information about our knowledge of the early Universe, and sometimes even means that we are seeing the Universe at a different stage of its development.
For example, when space was very young, it was opaque. But then at some point stars and supermassive black holes formed. emit energy and make it transparent. By discovering galaxies from that period, we can learn about the environment of space at that time, just a few hundred million years after the formation of the Universe.
We will also learn about the galaxies themselves. Why do they shine so brightly at this age? They have supermassive black holes that feed heavily on falling matter, but How did these black holes get so huge so quickly?? The more distant a galaxy we find, the more data we have to unravel these mysteries.
Additionally, this database of remote objects can be used to learn about them in general. We might find that most distant galaxies have some average luminosity, some exceed it, and none are brighter. This would tell us about the physics of how galaxies form, how they grow, and how they emit light. If there is a single brightest distant galaxy, this could place severe constraints on its behavior.
And there is one more record that will be difficult to break or even confirm. When we look back far enough, we will no longer see galaxies at all. Why not? Because they would not have formed yet! It took the galaxies several hundred million years to come together. dark matter serves as a gravitational basis, allowing ordinary matter to collect and condensegathering in colossal quantities that eventually formed nebulae, stars and planets. If we can look far enough into deep space, far enough into the past, we can look into a time when these structures did not yet exist.
Honestly, we've already done this; Microwave telescopes have detected the fireball of the Big Bang, a remnant of light from the universe's initial expansion that fills the sky. gently glowing longwave background (according to distance records, its redshift is about 1000!). But there is a gap of several hundred million years between now and the time when galaxies first began to appear, and we know very little about it. Every record holder we find squeezes that boundary a little tighter.
The universe is beautiful, dark and deep, but with our powerful telescopes and smart brains, we continue to move forward. Therefore, I welcome every new record. At this stage of our search, every breakdown is a step into new astronomical territory.
