"Hello,
friends!" "The biggest and the
most powerful space telescope in the world," was launched by NASA some days ago. It's named the James Webb Space Telescope. "Using this, you can time travel of
sorts." "I mean, it isn't
possible to go back in time," "but
with this, you can get a glimpse of history." "And I'm not talking about the history
made in the last 5-6 years," "literally,
millions and billions of years' history can be looked at using this
telescope." "More
specifically, 13 Billion Years!" The
universe began with the Big Bang 13.8 billion years ago. And this telescope can look till 13 billion
years ago. About 0.7 billion years after
the universe began. But how can it be
possible? "Come, in today's Blog, let's understand this phenomenon." """Liftoff from a tropical
rainforest," "to the edge of
time itself," "James Webb
begins a voyage back to the birth of the universe.""" """Nature has its way of being
even more creative than we are." So
we have always been surprised by what we see in the sky.
"That's why building a telescope has always been
interesting.""" """I
don't think that human beings have the obligation to learn about space. " But it will be foolish and shortsighted not
to do so. "It may hold the key to
our survival.""" The most
special thing about this telescope is that
it has been designed mainly to detect infrared light. "When you look at the sky," "with a normal telescope," you see the wavelengths of visible lights. The light that you can see with your naked
eye. Do you remember studying about
Electromagnetic Spectrum in school? The
Electromagnetic waves in a broad spectrum.
"It includes X-rays, Ultraviolet rays, radio waves,
microwaves," "and in there,
there is a small range of visible light."
The light that we can see with our naked eyes. "The normal telescopes that you can buy
at any shop," help you look only at
the wavelength of the visible light. "The
range of visible light is between blue colour to red colour," and red has the biggest wavelength. "And as you know, with electromagnetic
waves," "the bigger the
wavelength," the easier it is for
the electromagnetic waves to pass
through any object or obstacle. Like the
radio waves. The radio that you listen
to. The wavelengths of radio waves may
span more than kilometres.
"For this reason, you can listen to the radio waves
that pass through buildings even." The
wavelengths of infrared are bigger than that of red. But we can't see infrared with our naked
eyes. The advantage of using a telescope "for looking at infrared, can be seen in
this photo." The photo on the left
was taken by the Hubble Space Telescope. The most powerful space telescope we had till
now. You can see the space dust in it. And you can see the clouds of gases forming. But infrared wavelength can pass through the
dust and clouds and we'll be able to see
what lies behind this. The picture on
the right is what we imagine we would be
able to see with the James Webb telescope.
"Basically, you can say that"
"we'll get a more high-quality, HD picture." The word Infrared basically means below red. "This word comes from Latin," Infra means below. So Infrared literally means Below Red. Because its frequency lies below that of red. And frequency is inversely proportional to
wavelength. You'll recall this. "Anything that radiates heat," emits infrared waves. "Humans, animals, the Sun, fire" each of these emits infrared waves. "That's why in night goggles," "you would've seen soldiers use night
goggles often, " they basically
detect infrared. "Through the night
vision goggles, you get a view like this."
It is captured by infrared cameras.
"Since the telescope will look at stars and galaxies of stars, and planets," "all of which radiate heat," it'll be possible to capture and look at the
infrared waves.
The other advantage of infrared is that "when a telescope looks at stars at such
a distance," "stars that are
billions of kilometres far from us,"
"when the light from those stars reaches the telescope," "the light has travelled such a
distance," "that by the time
it reaches here," "and as we
know the universe is slowly expanding,"
the wavelength of the light gets stretched. The wavelength gets elongated. This phenomenon is known as the Red Shift. "That the wavelength of the light has
stretched a bit," and has shifted
towards the colour red. "With
telescopes," "the bigger the
mirror they are equipped with," the
more light they'd be able to capture. And
the resolution of the image that we get will be that much higher. "That's why, with the creation of more
and more advanced telescopes," they
are being equipped with bigger mirrors. "The
mirror of the Hubble Space Telescope,"
was of this size. And you have
the mirror of the James Webb Space Telescope beside it. This entire mirror is plated with 24karat
gold. Because gold is the best at
reflecting red light. "Because of
gold, the reflectiveness of this mirror is at 98%."
There's a problem here.
I said that everything that radiates heat emits infrared waves. "When the telescope will start
working," the telescope will
radiate some heat too. Some infrared
waves will be emitted from within the telescope. It'll interfere with the waves coming from
the galaxies and we wouldn't be able to
get good high-quality pictures. "To
avoid this," this James Webb
Telescope will work only at the cold temperatures of -223°C. The temperature needs to be so low for it to
work. "On Earth, the temperature
hasn't fallen below -89°C." So how
could this telescope be kept so cold? It
is possible to do it in space. "It
is possible because it is very cold in space," unless there's sunlight. "If sunlight falls on you in the
space," the temperature would rise
rapidly. As is the case on the moon. "Because there isn't any atmosphere on
the moon," The temperature may fall
to -170°C there. "But as soon as
there's sun," the temperature rises
to 120°C. It is very problematic for
this telescope. No sooner would sunlight
fall on this telescope it would be
problematic as everything would heat up rapidly. So they needed to stop the Sun. "To avoid this problem," a Sun Shield has been installed on this James
Webb Telescope. This Sun shield is in the
shape of a kite and is as big as a
tennis court. So the telescope could
remain protected from the Sun. "For
this, a very special material has been used," Kapton.
Several materials were tested to see
which material could be used to block the Sun most effectively and to keep the telescope cool. It was later discovered that Kapton was artificially created. "This Sun Shield comes with 5 layers of
Kapton," and each layer is thinner
than a strand of human hair. There's a
vacuum gap between each layer.
So that its effectiveness could be increased. "Apart from this, each layer has an
aluminium coating on it." And the
two layers closest to the Sun have a
coating of doped-silicon. "This
space telescope isn't being deployed near the Earth," as the Hubble Space Telescope was. Hubble is close to the Earth and orbits
around it. But this will be deployed 1.5
million kilometres away from the Earth. At
the point known as the L2 point. L
stands for Lagrange Point. "This
point will be on the other side of the Sun," "because obviously," it is important to block the heat and light
of the Sun as much as possible for the
better functioning of this telescope. "And
the L2 Point is special because," it
keeps revolving with the Earth. So the
Sun will be hidden throughout the revolution.
Look at how its orbit will be. The
Earth's shadow will keep the Sun hidden.
"It's similar to when you look at something in the direction of the
Sun," you can't see clearly because
of the sunlight. It's the same as when
you cover the Sun with your hand. And
you get to see clearer. It's the same
with the telescope.
NASA has said that the entire procedure of creating and
launching it is so complicated that
they have identified more than 300 potential problems that may arise. "More than 300 single points of
failures," "if any of them
come true," then the entire project
would be as good as over. $10 Billion
has been spent on this project. This
amount is so huge that NASA had to
defund several research projects and
direct the money to this project to make it possible. "Along with NASA, the European Space
Agency" and the Canadian Space
Agency are also participating in this. The
scientists have pinned their hopes that "using
this, they would be able to study" how
did stars and galaxies form after the Big Bang.
"As I told you, with this telescope, you can look 13 billion years
into the past." The Hubble Space
Telescope could look to only 1 billion
years after the Big Bang took place. So
about 12.8 billion years ago. But the
James Webb Telescope can look to 0.3 billion years after the Big Bang. As you can see in this diagram. When the stars began to form first. You'd ask how is it possible to look into the
past? The answer to it is very simple. The light takes some time to travel the
distance. "And by the time the
light reaches from one place to the other," a lot of time would have passed. Especially when it involves distances this
large. The light from the Sun reaches
the Earth by travelling approximately 8
minutes. "It means that if the Sun
vanished suddenly, for example," "it
will take 8 minutes for people to find out on Earth," to see that the Sun has disappeared. "In a way, you can say that we are
looking 8 minutes into the past" when
we see the Sun.
"Similarly, apply this logic on a large scale." "The stars and galaxies that are
millions of light-years away from us,"
when we look at them through the telescope "or we gaze at the stars from the
Earth," we are actually seeing them
as they were millions of light-years ago.
The universe is so huge that "there
are stars that are 13 billion lightyears away from us," "by the time their light reaches
Earth," "13 billion years
would have elapsed," "and what
we get to see today," are the
events of 13 billion years ago. This way
we can get a glimpse of history. "With
this logic," "theoretically,
it is also possible that" "if
we go 100 million lightyears away from the Earth," we teleport to a planet that is 100 million
lightyears away from the Earth. "And
on that planet, we build a very powerful telescope and look at the Earth," we'll get to see the Earth as it was 100 million
years ago. We'll get to see dinosaurs! But the practical problem to doing this is
that "by the time we go to the
other planet and look back at the Earth,"
"it will take a much longer time to reach the other planet," than the years that we can look back to. "So if it becomes possible to travel by
teleporting," we'll be able to
watch history occurring on the Earth. And
would actually be able to time travel. "Additionally,
it will be also interesting to see "
the new planets that the James Webb Telescope discovers. Can it find a planet with Earth-like
conditions? Where life can be possibly
found. Time will tell. I hope you'd like this blog "If you did, you can watch this blog on
Space Tourism as well" if you are
interested in the field of space. And
you can check out my other science-related blogs by clicking on this playlist here. Let's meet in the next blog. Thank you very much!