Short Wave - The James Webb Space Telescope Is Fueling Galactic Controversy

Episode Date: September 18, 2023

We're entering a new era of astrophysics. The James Webb Space Telescope is helping scientists test existing ideas and models of how the universe was created—on a whole new level. This telescope is sending back images of galaxies forming under a billion years after the Big Bang—way earlier than astronomers had previously expected. Not only that, scientists had anticipated that later—but still very early—galaxies would be small, barely formed blobs; instead, the galaxies in these images have spiral arms. So, today's show is all about GALACTIC CONTROVERSY! Computational astrophysicist Jorge Moreno talks with fellow astronomer and Short Wave's Scientist in Residence Regina G. Barber about how these new findings are stirring up controversy in the scientific community and the lessons we can learn from galaxies. Questions or controversies? Email us at [e-mail]. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. We're entering a new era of astrophysics. One where the ideas and models of how the universe was created are being tested, thanks to the James Webb Space Telescope. JWST is so powerful that with it we can now see deeper and sharper images of the distant universe than ever before. If you were a historian, you would go into the oldest archives to look for the earliest times in our history, right? If you were a paleontologist, you would dig deeper and deeper to find the oldest bones. In astronomy, what we do is look at our history, but we don't have a time machine.

So what we do is we look at really far away distances. Dr. Jorge Moreno, an astrophysicist at Pomona College, says that these images, they show what the universe looked like within the first few billion years of the Big Bang. For reference, the entire timeline of the universe is about 13.8 billion years. The Big Bang gave us this really hot and then soup. But because the universe is expanding, that should cool down and we made the first atoms. And then those atoms and that dark matter created the first stars and galaxies. And then those galaxies merged with each other and made really bright galaxies and quasars.

And that's what we call cosmic known when the growth of galaxy formation is its most active. But the early stages, the early morning part of that process, that's what we're beginning to see with JWS. And scientists can see all of this because of light. See, all the light you see, it's traveling to reach your eyeballs. It takes time. So when the light leaves a star, and when we see the star through a telescope, we're actually looking into the past. For reference, the closest star to us, Proximus Centauri, is about four light years away from the sun. So when we look at it, our nearest neighbor, we're looking at what it was doing over four years ago.

And the big thing on the mind of Jorge and many other astronomers is what these new images from JWST is telling us. about galaxies. So with JWC, we're able to look at the galaxies that are farthest away, and that light has been traveling between that galaxy and us for the longest time. Astronomers are seeing galaxies show up much sooner after the Big Bang and the start of the universe than they ever expected. And it's stirring up a lot of debate within the astrophysics community. I was puzzled, but I felt like there had to be a solution.

It's been often the case that people rush into controversy before really thinking about every possible solution. Today on the show, Galactic Controversy, how the origins of our universe are being tested by the new space telescope and what that tells us about astronomy today. I'm Regina Barber and you're listening to Shortwave from NPR. Okay, not to prolong the suspense, but before we get into controversy and the reality that galaxies formed hundreds of millions of years before we previously thought, we have to understand a few things about galaxies.

For Jorge, the easiest way to understand the varied history across our universe is to think of galaxies like people. Every person has its own personality, its own history. So if you listen to me right now, you will probably detect an accent. If you ask me about my music taste or

the food I like to eat, you could infer something about my history, my family, my ancestry. So the same is true with galaxies. When we look at galaxies and we pay attention to their structure, their color, the way it's moving, it tells us something about its history and its ancestry. But if a galaxy is really far away, it's really hard to really get all those details.

So with JW still were able to actually look at really far away galaxies in a lot of detail and really infer something about the physics of its growth and its history. Can you kind of tell us a little bit about galaxy structures? Because you said they're like people. So what kind of different galaxies can we have? So Edwin-Hubble in the early 20th century classified galaxies into more or less. as two camps, the spirals and ellipticals, spiral galaxies, they look like disks. They have spiral arms.

They're really beautiful. Ellipticals are kind of, they look more like rocky balls. They're really smooth. And so for over the last few decades, people have been imposing this binary. And until now, scientists thought that this early in the history of our universe, that distinction hadn't been made yet for galaxies. They were too young and undeveloped to be anything other than blobs. Which leads us to the first aspect of the universe.

controversy. Structure. The galaxies, they're seen in these images, they're bigger and more structured than they expected. They hit galactic puberty and are starting to form spirals.

Something that I find really interesting is that some of them look a lot like galaxies in the local universe. Like, they seem to have a structure and maybe even spiral arms. That wasn't something we really expected. The second aspect scientists didn't expect to see in these galaxies?

how ridiculously bright they are. If you interpret brightness as mass, then you would say that those galaxies are too massive to exist. Brightness can relate to mask if we say light comes from stars, which we can assume have a certain brightness and a certain mass. And based on that, astronomers can estimate how many stars created that light. And in the computer simulations we run, we have an expectation of how many galaxies of a given mass you should have per unit volume.

and these galaxies that people are observing seem to be too massive at those epochs. Much of the modeling astronomers have done up to this point have led them to believe that there wasn't enough time for galaxies to get this massive in so little time. So it's like if you went to a kindergarten and you saw a teenager. Totally. And there are problems with the assumption that brightness equals mass, right? We know that things can be really bright and not necessarily supermassive. So how are other scientists dealing with this difference? Some people are saying maybe we are not taking into account other effects.

Like for example, maybe there is a supermassive black hole that's shining on the galaxy itself. Or maybe we're not taking into account dust. Yeah, and hot dust gets really bright in the infrared, right? Like JWST is an infrared telescope. So this dust might be making the galaxies look brighter. So there are some details like that. People who are doing this more carefully are taking into account. They're really bright, but they need not be that massive.

And then there are other people who are more into making extraordinary claims that these galaxies actually break cosmology and that we need to revise our understanding of how the universe is expanding. So there are some astrophysicists in our community that are trying to answer these questions by altering past theories. Like there was a paper that came out recently trying to explain these early galaxies by combining two old theories. And in doing that, claiming that the universe, universe may be twice as old as we thought, from 13 or 14 billion years to 26 billion years. Our third controversial aspect of these early galaxies. The first theory is the very well-accepted idea that the universe is expanding.

So I spend a lot of time at the Carnegie Observatories in Pasadena. And if you look up in the mountains, in Mount Wilson, Edwin Hubble used those telescopes to find that the universe is expanding. So how do we know this? So if you measure the distances to galaxies and also you measure their colors, you see that the farther way a galaxy is, the closer to the red it gets. So it's a little bit like if you hear an ambulance, if it's moving away from you, the pitch is going to go down. But if it's coming towards you, the pitch is going to go up. So if a galaxy is moving towards you, it's getting bluer. If it's moving away from you, it's getting redder.

Now, this was in the early 20th century, and then Fritz's, you. who was at Caltech at the time, he said, no, there is an alternative. Maybe rather than having expansion, the light is just losing energy. When light is emitted, maybe it's blue, but it gets tired, quote-unquote, as it's traveling towards us. So blue light has more energy than red light. So that was like the alternative model. That model has been ruled out by observations. So the fact that the paper combines a well-accepted model with an unaccepted one

and poses the possibility that both are happening, It's controversial, and it's getting pushed back from astronomers like Jorge. So basically what this author did is he took the galaxy sizes from J.W. St.S. face value and assumed that they were the same size as the Milky Way. I think it's really clever, but I think in science, if you already have a model that's simpler than that, you should stick to it unless you have extraordinary evidence to do otherwise. Right. But you don't think this explains the data.

I don't think it explains the data, and I can tell you why. Yes. So this paper looks at the angular sizes of galaxies in JWST. It's basically the size of something, the way it's how big something looks. So the size of a galaxy on the sky depends on two things. It depends on how big it is intrinsically and also how far away it is. So for example, I had two chihuahuas and I love them. But imagine you have a chihuahua and a great thing.

and you might ask yourself which one looks bigger. Well, if the Great Dane is really far away and the Chihuahua is right in front of you, the Chihuahua is going to look bigger, even though intrinsically the Great Dane is bigger. So there is a third component, the expansion of the universe. That creates a really weird effect,

which is if you're looking at nearby galaxies, they look big, then you look far away, they look smaller, but eventually when you go really far away, they look big again. So we're getting an age of a universe just by sizes of galaxies, and that assumption is already not great. Yes, so the problem with that whole approach

is that there's a diversity of sizes and galaxy sizes do change they grow. And also there are extraordinary implications if the age of the universe is twice as old as we think. Like stars? Yes, that one prediction this model makes is that we should be able to find stars that are much older than 13.7 billion years.

There should be stars out there that are 25, 26 billion years old. nobody has found them. So either you basically get rid of decades of understanding of stellar evolution or you believe this model. It sounds like basically you're saying we just need more data. We need more evidence. What do you think are lessons for our field when it comes to jumping into all these controversies? I invite the community to take a step back.

I think it's really exciting to find things that could potentially destroy all the models we have. But I think we need to be a little bit extra cautious. And I think there is an issue with our culture of doing things in our brush. I think something the galaxies, in my opinion, teaches the galaxy is working with JWST. You see them, they are getting brighter and dimer. And I think that's something we need to learn from them. That it's important to just have times where we're really excited to discover things. But there are times where we need to quiet, down, take a break, and really think things clearly and slowly.

There is a lot of other areas that are also important that people are kind of like not paying so much attention or maybe not funding enough because they're obsessed with the biggest Chinese thing. Like galaxies in the early universe. Exactly. I want to thank you so much for talking to us about galaxies. I love galaxies and this has been wonderful.

Thank you so much. You bet. If you've been enjoying this episode, give us a follow so you can get alerted each time we publish a new episode. And before, we head out, a quick shout out to our Shortwave Plus listeners. We appreciate you for being a subscriber. Shortwave Plus helps support our show, and if you're a regular listener, we'd love for you

to join so you can enjoy the show without sponsor interruptions. Find out more at plus.mpr.org slash shortwave. This episode was produced by Rachel Carlson. It was edited by Rebecca Ramirez and Burley McCoy. Anil Oza Check the Facts. Josh Newell was the audio engineer. Special thanks to James Davenport for some extra astro help. Beth Donovan is our senior director and Anya Grenman is our senior vice president of programming. I'm Regina Barber. Thank you for listening to Shortwave from NPR.