Uncovered How Tiny Galaxies Built the Universe

Bright Side

The James Webb Space Telescope has blown our minds again, uncovering how tiny galaxies played a huge role in building the universe. These small galaxies, way back in the early days of the cosmos, were like cosmic overachievers, cranking out stars like there was no tomorrow. JWST's powerful infrared vision revealed these faint, ancient galaxies that we couldn't see before. Turns out, their energy and light helped shape the universe, contributing to something called reionization, which made the universe clear and starry like we know it now. It’s wild to think that these tiny galaxies did so much heavy lifting in the grand cosmic plan. Basically, the JWST just gave us another reason to geek out over the universe!

Transcript

00:00Bang! Or should I say, Big Bang! The Big Bang! Ahem! So, after the Big Bang, the universe

00:07resembled a hot soup of protons, neutrons, and electrons. After it started to cool down,

00:13the protons and neutrons began to combine, first forming ionized atoms of hydrogen and

00:19later, some helium. These ionized atoms of helium and hydrogen attracted electrons, turning

00:26them into neutral atoms. As a result, the light was able to travel freely for the first time

00:32ever, since it was no longer scattering off free electrons. What does it mean? The universe

00:38was no longer dark. At the same time, it was still about a few hundred million years after

00:43the Big Bang, before the very first sources of light started to appear. That's when the

00:48cosmic dark ages came to an end. We don't know for sure what this universe's first light

00:54looked like or how the first star is formed. Luckily, we have the James Webb Space Telescope

00:59to help us find the answers. How come? All because this is an infrared telescope. Why

01:06is it important? Let's figure it out. Imagine a star. It's a very, very old star. Maybe

01:15the first star out there. Light leaves this star 13.6 billion years ago and settles off

01:21on an incredible journey through space and time. It needs to get to our telescopes.

01:27By the time this light reaches us, its color or wavelength shifts towards red. That's something

01:33we call a redshift. It happens because when we talk about very distant objects, Einstein's

01:41theory of general relativity comes into play. According to it, the expansion of the universe

01:47also means that the space between objects stretches, making them move away from one another. But that's

01:53not all. Light stretches too, which shifts it to longer wavelengths. Eventually, this light

02:00reaches us as infrared. In other words, redshift means that light that is originally emitted by

02:07the first stars or galaxies as ultraviolet or visible light gets shifted to redder wavelengths

02:13by the time we catch a glimpse of it here and now. For the farthest objects with very high

02:19redshift, that bare minimum of visible light is shifted into the near and mid-infrared part

02:25of the electromagnetic spectrum. That's why to see those space objects, we need a super powerful

02:32telescope. And if we talk about the Webb telescope, it can see back to about 100 million to 250 million

02:40years after the Big Bang, which is incredibly awesome. So by observing the universe at infrared

02:48wavelength, James Webb lets us see things no other telescope has ever shown before. The primary goal

02:55of this incredible piece of equipment is to study the formation of galaxies and stars that formed in

03:01the early universe. To look that far back in time, we need to look deeper into space. All because it takes light

03:10time to travel back from there to us. So the farther we look, the further we glimpse back in time.

03:17To find the first galaxies, James Webb is going to make an ultra-deep near-infrared survey of the universe.

03:24Then, it'll follow it up with a few other methods of research.

03:29Now, as you remember, the gas between stars and galaxies in the early universe was opaque and energetic

03:35starlight couldn't penetrate it. But then, about one billion years after the Big Bang, it suddenly became

03:42completely transparent. Why? The James Webb telescope might have found the reason.

03:49At one point in the past, the first galaxy's stars emitted enough light to ionize and heat the gas

03:55around them. This helped clear the view over hundreds of millions of years. The newest insights scientists

04:02were about a time period called the era of reionization. That's when the universe underwent

04:08some dramatic changes. After the Big Bang, gas in the universe was unbelievably hot and dense.

04:17Hundreds of millions of years passed, and it cooled down. But then, something baffling happened. It was as

04:23if the universe hit the repeat button, and the gas became ionized and hot once again. It could have

04:29happened because of the formation of early stars. After that, millions of years later,

04:34this concoction became transparent. For a long time, researchers have been hoping to find definite

04:42evidence that could explain these changes. And now, the telescope has finally shown that those

04:48transparent regions are located around galaxies. Astronomers have seen these galaxies reionize the gas

04:56surrounding them. Even better, they've managed to measure how large these transparent regions are.

05:03They're ginormous compared to the galaxies themselves. Imagine a hot air balloon. And now,

05:09imagine a pea floating inside. You've got it. And guess what? These tiny galaxies drove the entire

05:17reionization process, clearing huge regions of space around them. These transparent bubbles kept growing

05:24until they merged and caused the entire universe to become transparent. The research team chose to

05:32target a period of time before the end of the era of reionization. At that time, the universe was not

05:39quite opaque, but not quite clear either. It was a patchwork of regions of gas in different states. To find out

05:47this cool fact, the astronomers aimed the James Webb telescope in the direction of a quasar, an incredibly

05:54bright space object. It acted as a giant flashlight traveling towards us through different regions of

06:00gas. It was either absorbed by the patches of near-opaque or moved freely through the areas where the gas

06:07was transparent. The scientists then used Webb to examine galaxies in that region of space. They found out

06:16that these galaxies were usually surrounded by transparent regions with a radius of about 2

06:22million light years. For comparison, the area the galaxies cleared was almost the same distance as the

06:29space between our home Milky Way galaxy and our nearest neighbor, the Andromeda galaxy. And the telescope

06:35witnessed those galaxies in the process of clearing the space around them. It was the end of the era of

06:41reionization. Until then, no one had evidence of what caused reionization. The team is planning to dive

06:51into research about other galaxies in five additional fields. The Webb telescope's results from the first

06:58field have been overwhelmingly clear. And even though the astronomers had expected to identify a few dozen

07:05galaxies existing during the era of reionization, they actually managed to spot 117.

07:14Now, let's talk a bit about the main hero of today's show, the James Webb Space Telescope.

07:19It's an absolutely stunning piece of equipment which is around 100 times more powerful than the Hubble Space

07:25Telescope. And the latter has observed places that are 13.4 billion light years away. The James Webb

07:33telescope is also on the pricey side, to put it mildly. Even though originally the cost of the telescope

07:39was estimated to be just 1 to 3.5 billion dollars. The whole development process cost around 10 billion

07:47dollars. For comparison, it cost NASA 4.7 billion dollars to build and launch the Hubble telescope.

07:54And it was another 1.1 billion dollars to fix it in orbit.

07:59Even though the James Webb telescope itself is three stories high and the size of a tennis court,

08:06its mirrors are the lightest large telescope mirrors of all time. During the manufacturing process,

08:12they underwent a 92 percent reduction in weight. When you look at them, the telescope's mirrors

08:19seem to be gold. But in reality, they're made of beryllium. This is a steel gray, lightweight,

08:26and brittle metal. A gold coating is applied to each mirror, that's true. But they can't be produced

08:31entirely out of gold, since this precious metal tends to expand and contract, even with small

08:37temperature changes. So, the total amount of gold in the James Webb Space Telescope is less than two

08:44ounces. That's a golf ball-sized piece of gold. And the gold plates covering the mirror are less than

08:501,000 atoms thick. As for the telescope's abilities, it would be able to clearly see a US penny from 24

08:58miles away and a football from 340 miles away. James Webb's telescope side is cooling itself down,

09:06and its temperature doesn't rise higher than minus 370 degrees Fahrenheit. That's cool enough to make

09:13liquid nitrogen. A truly enormous five-layered sun shield surrounds the telescope and reflects away

09:20as much sunlight as possible, letting the telescope stay cool.

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