My name is Professor Tim McKay
and I am a professor
of physics and astronomy
here at the
University of Michigan
where I study
observational cosmology.
The purpose of cosmology
is to try and explain
the origin and evolution
of everything
that's in the Universe
from the earliest possible time
all the way down to today.
Cosmology is a very nice
kind of historical science
because we have the
rare chance to see history.
We actually
get to see the Universe
as as it was at different times
and watch what happens in it.
The way we do this is
to take advantage of
the finite speed of light.
Light travels not
infinitely fast, very fast,
but not infinitely fast.
And so, when we
look at a distant object,
we see it as it was in the past.
The light has spent
a long time traveling to it...
to us, and when it gets here,
we see light that
left it a long time ago.
If we look at a still
more distant object,
we see it as it was
even farther in the past.
So, when we're
studying cosmology,
we look at the light that
has come to us from objects
from the recent past,
the more distant past,
and the very earliest times
by looking at things that are
farther and farther away.
This lets us see the
evolution of the Universe
from what it was like
at the earliest times
when we look at the
most distant things
all the way down to today.
It's like the history
of the Universe
is laid out around for...
around us for us to look at.
Since we're gonna try
and use the light
that travels to us
from very remote objects,
we need to augment
the minimal things
that we can do
just by looking at the sky
with our eyes.
And throughout the history
of science,
we found a whole series
of different ways
to improve people's vision.
The simplest one is
to put glasses on your eyes
to give you a little
bit better vision
using still the eyes
that you start with.
A next stage of this
is to build things
like telescopes,
telescopes that both magnify
distant objects and
make them appear larger
than they would
just to your eyes.
But telescopes
also let you collect
more light than
your eyes would.
Your eyes have a
very small aperture
and let in only a
little bit of light.
Using a telescope like
this is like having an eye
that's about that big.
But we've since made, of course,
much bigger telescopes,
telescopes that have eyes
that are meters in size
and the very largest
telescopes that we use today
have apertures of about
10 meters or about 35 feet.
You can see much more distant,
much fainter things with
such a large telescope
than you can see
with just your eyes.
And it's largely that
improvement in instrumentation
which has led to the
great advances in cosmology
and being able to understand
the history of the Universe
because with these instruments,
we can see that history
so much better than
the ancient Greeks could
looking at it
with just their eyes.
The reason I got into cosmology
was a mix of interest
and opportunity.
I have always liked
observing nature
at every scale and in every way,
from the time
I walk down the street
to when I'm using a super
fancy scientific instrument.
The reason I got involved
in cosmology, though,
is that I took a job
at a place called Fermilab,
a particle physics laboratory,
and they told me I could
do anything I wanted.
And they were starting
a new project there
called the Sloan
Digital Sky Survey
and it was gonna observe
so many things
that it seems so
scientifically rich,
I couldn't resist
working on it.
So, I joined it then
and I've been working on
cosmology ever since.
Observational Cosmology
has had a really great 15 years
because we now really know the
basic history of the Universe
from the Big Bang
all the way down to today.
It's been observed repeatedly,
it's very well understood.
But there remained
some big mysteries
and I'll tell you about
just four important mysteries
that remain in cosmology.
The first has to do with
the very earliest moments
of the Big Bang.
Everyone wants to know
what was there
before the Big Bang.
Was there anything
there before the Big Bang?
How did it happen?
Why did the Big Bang happen?
What initiated it?
Those are very
difficult questions.
We don't have much observational
evidence about them.
But everyone will
always be fascinated by them.
The next two big
questions have to do with
constituents of the Universe,
with stuff that's
in the Universe.
There are two big mystery
components to the Universe.
The first is called dark matter
and dark matter is a kind
of material, a substance
that seems to be very widespread
through the Universe.
There's more of it
than there is ordinary matter,
the kinds of atoms
that we're made of.
And it seems to be something
that interacts gravitationally
but never interacts with light.
The other mysterious
component of the Universe
is something that seems to be
causing accelerated expansion.
The expansion rate of
the Universe used to be slower
than it is today.
It's actually
speeding up with time.
We really have no idea
what's causing it
to speed up like that,
what's causing
accelerated expansion.
But we've given a name to it
even though we don't
really know what it is.
We call it dark energy.
So, dark matter and dark energy
are both very mysterious
aspects of cosmology
that we're hoping to understand.
The fourth big
question is, for me,
the most intriguing question.
We know that everything
that can happen in the Universe
should happen and should happen
freely anywhere it's possible.
And there's one thing
that has happened here on earth
that we've never
seen anywhere else,
and that's the
emergence of life.
Everything about our picture
of cosmology suggests that
if life could
emerge here on earth,
it should have done so freely
in many places in the Universe.
So, we need to find out
whether that's really true.
Our instruments right
now are not quite capable
of telling us whether
there's life on other planets
but in the next few decades,
we should be able
to settle that question
with some level of confidence.
And I really look forward
to the discovery of life
in other places in the Universe.
