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.
Comments