- Space telescopes, telescopes in general,
are astronomers' most powerful tool
for looking back in time.
Traveling back in time is the stuff of science fiction,
but looking back in time is science fact.
It's something that we actually do,
and it's made possible by the finite speed of light.
And so, if one looks at, say,
a person in the room next to you,
you're not seeing them as they are.
You're seeing them as they were a few nanoseconds ago
because that's how long it takes light
to travel about one meter – a few nanoseconds.
So, when we look at the Sun we're not seeing it as it is.
We're seeing it as it was 500 seconds ago.
And if we look at the nearest star,
we see it as it was four years ago.
And with the Webb, we will be looking back in time
more than 13 billion years to see the birth
of the first stars and galaxies to form after the Big Bang.
Well, the telescope looks frankly different
than most other telescopes that you've seen pictures of.
And all of those differences that you see are there
to enable the Webb's unique science mission,
to see the birth of the first stars and galaxies
in the universe and to give humanity
its first high-definition view of the infrared universe.
The light from the first stars and galaxies
is emitted in the ultraviolet part of the spectrum.
But as it travels to us through the expanding space,
the wavelength of that light
is stretched to infrared wavelengths.
And so, to observe it today, we have to work in the infrared.
So, the things that make the JWST unique
are its infrared capability in combination
with the very large size of its primary mirror.
And this giant primary mirror that the JWST has
is the first time that any infrared telescope in space
has had a giant mirror.
And that mirror will give the JWST the ability
to see fine detail that is very similar to Hubble's.
And so, the images will be as breathtaking
as the Hubble images and this will be the first time
that humanity has seen the infrared universe
in high-definition.
And for an infrared telescope to work well,
it has to be made very, very cold
because anything that is warm emits infrared light
and if we didn't make the telescope very, very cold,
it would be blinded by its own infrared emission.
And so, the JWST will not orbit the Earth
the way the Hubble space telescope does.
It will go to a special spot in space
called the second Lagrange point of the Sun-Earth system.
We just call it the L2 point for short.
And we determined that if we put the JWST
at this special spot in space, the L2 point,
all the sources of heat on it would lie in one direction.
The sources of heat are the Sun, the Earth, and the Moon.
And from the L2 point, those sources
are always in one direction so we realized
that we could deploy a giant sunshield
such that the telescope will always live
in the shadow of the sunshield.
And in that configuration it will cool passively
by simply radiating its heat away
to the cold darkness of space.
Our whole lives are just a fleeting moment.
The day-to-day tribulations that we torture ourselves with
here on the Earth, whether it be politics or something else,
all of it is terribly insignificant
in terms of this universe that we're embedded in
and that is evolving around us.
The big picture is not the picture
that we spend most of the time arguing with each other about
in our lives on the Earth.
And I'm hopeful that we'll be able to find a way
to avoid destroying the Earth long enough for us
to really understand the universe that we're embedded in
and long enough for us to really understand the worlds
that we now know exist
around nearly every star in the galaxy.
Today the search for life,
the search for extraterrestrial life
is no longer the stuff of science fiction.
There are billions of habitable worlds in our galaxy alone,
and there are billions of galaxies.
And so it's somewhat inconceivable
that we are alone in the universe,
but we've learned how to search for life on exoplanets.
And now we need to begin the long,
methodical business of doing that.
JWST will start that process and do some spectroscopy,
transit spectroscopy as they call it
to understand exoplanet atmospheres,
the chemistry of those atmospheres.
The search for life should be
some of the most exciting science
that we do over the next 20 or 30 years in space astronomy
with Webb and other missions.
The highest priority mission that we will start building
in this decade is very much focused
on exoplanets and the search for life.