• last week
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! Credit:
CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0/:
Redshift: Georg Wiora (Dr. Schorsch), https://commons.wikimedia.org/wiki/File:Redshift.svg
Beryllium nuggets: W. Oelen, https://commons.wikimedia.org/wiki/File:Beryllium_nuggets_2.jpg
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Transcript
00:00Bang, or should I say Big Bang, the Big Bang, ahem.
00:05So after the Big Bang, the universe resembled a hot soup of protons, neutrons, and electrons.
00:12After it started to cool down, the protons and neutrons began to combine, first forming
00:17ionized atoms of hydrogen and later some helium.
00:22These ionized atoms of helium and hydrogen attracted electrons, turning them into neutral
00:27atoms.
00:28As a result, the light was able to travel freely for the first time ever, since it was
00:33no longer scattering off free electrons.
00:36What does it mean?
00:37The universe was no longer dark.
00:40At the same time, it was still about a few hundred million years after the Big Bang before
00:44the very first sources of light started to appear.
00:48That's when the cosmic dark ages came to an end.
00:51We don't know for sure what this universe's first light looked like or how the first stars
00:56formed.
00:57Luckily, we have the James Webb Space Telescope to help us find the answers.
01:02How come?
01:03All because this is an infrared telescope.
01:06Why is it important?
01:08Let's figure it out.
01:12Imagine a star.
01:13It's a very, very old star, maybe the first star out there.
01:17Light leaves this star 13.6 billion years ago and settles off on an incredible journey
01:22through space and time.
01:25It needs to get to our telescopes.
01:28By the time this light reaches us, its color, or wavelength, shifts towards red.
01:33That's something we call a redshift.
01:37It happens because when we talk about very distant objects, Einstein's theory of general
01:42relativity comes into play.
01:44According to it, the expansion of the universe also means that the space between objects
01:49stretches, making them move away from one another.
01:53But that's not all.
01:54Light stretches too, which shifts it to longer wavelengths.
01:58Eventually, this light reaches us as infrared.
02:03In other words, redshift means that light that is originally emitted by the first stars
02:08or galaxies as ultraviolet or visible light gets shifted to redder wavelengths by the
02:13time we catch a glimpse of it here and now.
02:17For the farthest objects with very high redshift, that bare minimum of visible light is shifted
02:22into the near and mid-infrared part of the electromagnetic spectrum.
02:28That's why to see those space objects, we need a super powerful telescope.
02:33And 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!
02:45So by observing the universe at infrared wavelength, James Webb lets us see things no other telescope
02:51has ever shown before.
02:54The primary goal of this incredible piece of equipment is to study the formation of
02:59galaxies and stars that formed in the early universe.
03:03To look that far back in time, we need to look deeper into space.
03:08All because it takes light time to travel back from there to us.
03:13So 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
03:22survey 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
03:35and energetic starlight couldn't penetrate it.
03:38But then, about 1 billion years after the Big Bang, it suddenly became completely transparent.
03:44Why?
03:45The James Webb Telescope might have found the reason.
03:49At one point in the past, the first galaxies' stars emitted enough light to ionize and heat
03:55the gas around them.
03:57This helped clear the view over hundreds of millions of years.
04:01The newest insights scientists got were about a time period called the Era of Reionization.
04:07That's when the universe underwent some dramatic changes.
04:12After the Big Bang, gas in the universe was unbelievably hot and dense.
04:17Hundreds of millions of years passed, and it cooled down.
04:20But then something baffling happened.
04:22It was as if the universe hit the repeat button, and the gas became ionized and hot once again.
04:29It could have happened because of the formation of early stars.
04:33After that, millions of years later, this concoction became transparent.
04:38For a long time, researchers have been hoping to find definite evidence that could explain
04:44these changes.
04:45And now, the telescope has finally shown that those transparent regions are located around
04:51galaxies.
04:53Astronomers have seen these galaxies reionize the gas surrounding them.
04:57Even better, they've managed to measure how large these transparent regions are.
05:03They're ginormous compared to the galaxies themselves.
05:07Imagine a hot air balloon, and now imagine a pea floating inside.
05:12You've got it, and guess what?
05:14These tiny galaxies drove the entire reionization process, clearing huge regions of space around
05:21them.
05:22These transparent bubbles kept growing until they merged and caused the entire universe
05:27to become transparent.
05:30The research team chose to target a period of time before the end of the era of reionization.
05:37At that time, the universe was not quite opaque, but not quite clear either.
05:42It was a patchwork of regions of gas in different states.
05:46To find out this cool fact, the astronomers aimed the James Webb Telescope in the direction
05:52of a quasar, an incredibly bright space object.
05:56It acted as a giant flashlight, traveling towards us through different regions of gas.
06:01It was either absorbed by the patches of near opaque, or moved freely through the areas
06:06where the gas was transparent.
06:10The scientists then used Webb to examine galaxies in that region of space.
06:15They found out that these galaxies were usually surrounded by transparent regions with a radius
06:21of about 2 million light years.
06:24For comparison, the area the galaxies cleared was almost the same distance as the space
06:29between our home Milky Way galaxy and our nearest neighbor, the Andromeda galaxy.
06:35And the telescope witnessed those galaxies in the process of clearing the space around
06:39them.
06:40It was the end of the era of reionization.
06:43Until then, no one had evidence of what caused reionization.
06:49The team is planning to dive into research about other galaxies in five additional fields.
06:56The Webb Telescope's results from the first field have been overwhelmingly clear.
07:01And even though the astronomers had expected to identify a few dozen galaxies existing
07:06during 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.
07:20It's an absolutely stunning piece of equipment which is around 100 times more powerful than
07:25the Hubble Space Telescope.
07:27And the latter has observed places that are 13.4 billion light years away!
07:32The James Webb Telescope is also on the pricey side, to put it mildly.
07:37Even though originally the cost of the telescope was estimated to be just 1 to 3.5 billion
07:44The whole development process cost around 10 billion dollars.
07:48For comparison, it cost NASA 4.7 billion dollars to build and launch the Hubble Telescope.
07:55And it was another 1.1 billion dollars to fix it in orbit.
08:01Even though the James Webb Telescope itself is three stories high and the size of a tennis
08:06court, its mirrors are the lightest large telescope mirrors of all time.
08:11During the manufacturing process, they underwent a 92% reduction in weight.
08:17When you look at them, the telescope's mirrors seem to be gold, but in reality, they're
08:21made of beryllium.
08:23This is a steel gray, lightweight and brittle metal.
08:27A gold coating is applied to each mirror, that's true.
08:30But they can't be produced entirely out of gold, since this precious metal tends to
08:34expand and contract, even with small temperature changes.
08:40So the total amount of gold in the James Webb Space Telescope is less than 2 ounces.
08:45That's a golf ball sized piece of gold.
08:48And the gold plates covering the mirror are less than 1,000 atoms thick.
08:53As 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.
09:03James Webb's telescope side is cooling itself down, and its temperature doesn't rise higher
09:08than minus 370 degrees Fahrenheit.
09:12That's cool enough to make liquid nitrogen.
09:15A truly enormous five-layered sun shield surrounds the telescope and reflects away as much sunlight
09:21as possible, letting the telescope stay cool.
09:25That's it for today!
09:28So hey, if you pacified your curiosity, then give the video a like and share it with your
09:32friends.
09:33Or if you want more, just click on these videos and stay on the Bright Side!

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