There's no shortage of mysteries to be solved right now in cosmology.
How did the universe begin? How is it evolving? What is its ultimate fate?
I want to build instruments to explore parts of the universe that are not seen yet.
I hope that there are surprises waiting for us.
My name is Cynthia Chiang.
I'm an associate professor in physics at McGill University,
and I'm an observational cosmologist, so I build telescopes for a living.
One of the wonderful things about radio astronomy is that we are able to see the
universe in ways that we cannot see with our own eyes.
If you pick a particular frequency lower than 1420 megahertz,
you can tune into a particular slice of the universe's history.
We think that the universe began its life in the Big Bang,
which happened about 14 billion years ago.
That time the universe was very hot and very dense. As the universe has expanded
and it's cooled down, it's transitioned through different phases.
Hydrogen is a very special tool for us in cosmology,
and the reason why we rely on it so heavily is because it's the most abundant
element in the universe,
and hydrogen is special because it naturally glows with radio light,
and we can use this emission of hydrogen to kind of map out where it is in the universe.
Anytime you look at any object with a telescope,
you're kind of seeing that object in the past. Because the universe is expanding,
the light from the hydrogen is stretched out or redshifted in proportion to how
far away the hydrogen is or equivalently how long ago the light was emitted.
So the way we can use radio telescopes to kind of peer back in time and map out
the history of the universe is by measuring this redshifted emission from
hydrogen.
The first thing that you need for a radio telescope is something to receive the
light, and so depending on what kind of instrument you're building,
that can either be a reflector,
like a dish of some sort that gathers light and then focuses it onto a receiver.
Or sometimes in our experiments we just have bare antennas that sit and look at
the sky.
We have to bring it down about halfway.
The radio signals that we're looking for are typically very faint,
and so immediately after you receive that radiation,
the first thing that you want to do is amplify it,
And then there's usually digitizing electronics that turn those analog signals
from the telescope into numbers that then we can put on the computer.
Start off in one sec. Alright, go ahead.
The reward in doing this work is that by knowing the science and the kinds of
things that you have to measure,
that informs our design so that we're able to build a machine that's
specifically targeting our goals,
and then we can optimize it to our heart's content.
It's going to take off, climb to 50 feet, and then hover over the antenna.
Then we'll run config F P G A and we'll start up a dump base band dump spectra
and send it up to fly past.
One of the greatest challenges of observing in the radio is that there's all
sorts of interference at radio wavelengths created by humans.
FM radio, AM radio, TV towers, cell phone towers, all sorts of stuff.
So we often end up in strange places out in the middle of nowhere where it's
quite literally quiet, radio quiet, so that we can get a better view of the sky.
The most recent sites that I've worked at are in the high Arctic,
Northern Canada and also Marion Island, which is an island in the sub Antarctic.
It's located about halfway between South Africa and Antarctica,
and it's about 2000 kilometers away from anything else.
Marion is windy and it's rainy and it's cold year round.
The winds are especially bad.
My team has two experiments that ran from Marion Island and one of 'em,
PRIZM was designed to be a Cosmic Dawn experiment,
so specifically looking for the signature of the first stars illuminating in the
universe, roughly about a hundred million years after the Big Bang.
It's exciting to study because we basically have no measurements of this period.
The experiment consists of two antennas each about the size of a coffee table.
The way the PRIZM antennas work is that they are basically very sensitive
thermometers or microphones as you can think about it.
They just kind of measure the average intensity across the entire sky.
So we're not trying to make pictures with these antennas.
The frequencies that we're looking at from Cosmic Dawn are actually exactly FM
radio that plus a little bit more.
So if you can imagine tuning into all of the radio stations at the same time
with your car radio.
What we're listening for is the static from the early universe,
but within that static buried deep within there for a few of those radio
stations we're listening for where the static is a little quieter.
The other experiment that we have set up is an interferometer that is trying to
map out the low frequency sky as a first step towards future observations of the
Dark Ages at about 400,000 years after the Big Bang.
It's one of the periods in the most distant history that we have yet to
access, and we have zero measurements of the Dark Ages so far.
The universe turned from this glowing ionized plasma and became transparent
Light was created at this point known as the Cosmic Microwave Background,
and that's sometimes known as the afterglow of the Big Bang.
In addition to that light being released,
the universe became cold enough for the first neutral hydrogen atoms to form.
The hydrogen that was created at that point was basically all there was,
and the universe,
the Cosmic Microwave Background gives us literally a photo of the universe in
its infancy.
But that snapshot is also preserved in the distribution of hydrogen throughout
the Dark Ages.
One of the very exciting things is that if we could one day map out that
distribution of hydrogen in full three dimensions,
we could learn a huge amount about our universe. The ALBATROS experiment,
it's an array of antennas,
and these antennas will all observe together to produce an image of the sky.
The next array that we're going to build in full is in the high Arctic,
so when that's fully operational, the antennas will be spanning about 10,
15 kilometers or so between the ones that are most distant from each other.
Our goal with ALBATROS is to make maps or take pictures of our Milky Way
galaxy at very low frequencies,
and to get an image of the Milky Way that's significantly sharper.
We have to understand our Milky Way emission before we can subtract it off and
look for the Dark Ages signal behind it.
So that's our very first step is kind of knowing our enemy before we fight it.
Then we, we'll try to fight it and get to the cosmology.