(theme music)
- G'day everyone and welcome
to The Trekzone Spotlight,
Matt Miller with you.
Joining me today is Dr. Tamara Davis
from The University of Queensland.
And you're an astrophysicist.
- That's right.
- Thanks for your time today.
- Thanks so much for chatting with me.
- Now, Professor Stephen Hawking,
who's diagnosed with
motor neurone disease,
given two years to live, five
decades later, here we are.
He's passed away, sadly, at the age of 76.
What does he mean to you?
- Stephen Hawking was
really an inspiration,
both as a physicist and as a human being.
You can see he overcame
enormous personal challenges,
physical challenges in
order to be able to do
his research, and yet,
excelled in so many ways.
I remember Stephen Hawking from being,
when reading the Brief History
of Time, as a teenager.
And being absolutely
dumbfounded by the fact
that physics was explaining
questions that previously
had only been the domain
of philosophy and religion.
Like, how did the universe begin?
And when I realised that
you could actually go
and ask physics quantitative questions
and figure out how in quantum physics
you might have been able
to create a universe.
That was a revelation to me.
And it was probably one
of the initial sparks
that inspired my real profound
interest in cosmology,
and is where I am today.
- [Matt] My tweet said yesterday said
that he shaped our lives.
He really did that, didn't he?
- Yeah, I think he was fantastic in
that he communicated his research as well.
He was not satisfied with just
discovering profound things
about the universe,
he wanted to share that
knowledge with everybody.
And that desire is quite common,
the skill to do it is really difficult,
but he did it really well.
And I love A Brief
History of Time, his book,
that first book there.
In that it didn't shy away
from asking really difficult questions
about us and trying to
explain the details.
He didn't just give you the
cartoon version of the physics,
he actually said, "No, check this out.
"I've got imaginary time.
"We've got square roots
of negative one in here.
"And how does that work?
"And if time goes this way."
And trying to explain the
depth of complexity in a way
that a lay reader could understand.
I know a lot of people
walked away from that book
without fully comprehending
what was going on,
but I think everyone went
away with a sense of wonder.
- What were some of his key discoveries?
- So, Hawking's most famous
for his studies of black holes.
And, we know that black holes are so dense
that light can't escape
their gravitational pull.
But Hawking discovered
that black holes should actually glow.
Now, this light that's emitted
from around black holes
is now known as Hawking radiation.
And it seems to contradict everything
we thought we knew about
black holes, but it doesn't.
And the way that, that works
is that the black holes,
you have the event horizon,
if you go closer to the black
hole then the event horizon,
that's the point of no return.
You can never escape,
no light that you emit will ever get out.
Very bad for your health, don't do that.
But, Hawking radiation isn't
being emitted from inside.
Nothing emerges from the event horizon,
it's actually created by
effects in the quantum vacuum
just outside the event horizon.
And because it starts from outside,
does not violating any
of the quantum rules,
or the rules of the black holes.
But interestingly, you can't
creates something from nothing.
So, if light and particles
are being created outside
of the black hole,
where is the energy coming from?
And to make that happen,
the black hole has to pay.
And it pays with the only
currency it has, its mass.
So, as it glows, that takes
energy away from the black hole
and reduces its mass.
And so the black hole slowly shrinks.
It's known as black hole evaporation.
And it goes all the way to the point
where the black hole disappears
in a blinding flash of
light and is no more.
- How does someone on Earth
discover that? (laughs)
- (laughs) yeah, well interestingly,
the people who are famous for
inventing some of the code
that became WiFi, which is
some Australian astronomer
who was working at the
Parkes Radio Telescope.
We're actually looking for
this Hawking radiation flashes
from evaporating black holes.
They never found that,
but in the process of trying to process
radio signals quickly, they
figured out how to do WiFi.
So, that was one of the side benefits in
which Hawking indirectly
changed our lives.
And admittedly, we haven't
seen Hawking radiation.
So, we can't experimentally
confirm that it's there,
but it's been theoretically confirmed
in a wide variety of different ways,
different types of derivations
that we're pretty
confident that it's there.
So, that's really exciting.
And the reason that it's so
exciting is because Hawking
was taking seriously
the idea of what happens
when you deal with quantum
physics in the vicinity
of a black hole, in strongly curved space.
And that was a trailblazing effort by him,
which explained things that
no one had ever seen before.
And the same theory that
he was using to explain
that translates into really
interesting implications
about the universe as a whole.
For example, it gives you ideas about
how you could create a universe
from the quantum vacuum,
from essentially nothing to start with.
And the big quest in
modern physics is to try
and figure out a quantum
theory of gravity.
We have these two fantastically
successful theories,
quantum physics does great with particles,
all the little nitty gritty stuff.
General relativity does a
fantastic job of gravity.
And we've tested both of those
in a huge number of ways.
Just one quick example is
our GPS' on our phones wouldn't work
if we didn't take into
account general relativity.
So, it's become part of our everyday life.
But the two theories are
fundamentally incompatible.
We know that they don't work together.
And that has perplexed
physicists for a century.
And we're trying to figure that out.
So, by delving into that area,
that's one of the ways
in which Stephen Hawking
has really advanced our understanding.
We haven't got to a final answer yet,
but we're, he laid the
foundation for a whole new type
of study that is occupying
us physicists these days.
- [Matt] Do you think we'll
ever get to a final answer
in all of this?
Would that just make it boring?
- The final answer is not with us yet.
Who knows whether we're
gonna be able to get there.
- [Matt] Is it 42?
- (laughs) Yeah, the concept could be 42.
But then what's the question?
(both laughing)
Yeah, but the quest for
a theory of everything,
that's one of the things that
people have been looking for.
So, Stephen Hawking had a
really good quote about this,
which I'll try and remember.
It went along the lines of,
"If we understand a theory of everything,
"it will be the ultimate
triumph for human reason."
And concluded that with,
"It would be like
knowing the mind of God."
Paraphrasing someone.
And he had to explain
that question many times
or that statement many times,
because as a devote atheist
he wanted to be clear that,
"No, no, I'm not talking about
"we're actually gonna see a
deity or understand a deity."
He's explaining that with the
physics that we're using here,
you can show how you can create a universe
and how everything within that
universe evolves naturally
without the need for a deity.
So it would be like
understanding the rules
that were laid down by physics
that made our universe.
And that would be sort of
like seeing the mind of a god.
- [Matt] So, Stephen has
really left physicists
around the world with
plenty to keep them occupied
until the next great mind
comes along, hasn't he?
- Yeah, and I think the
idea of the next great mind
is perhaps a little bit overblown
because there's some really famous people.
You've got the Einsteins,
you've the Stephen Hawkings,
the people that become
really recognisable figures.
But a lot of this research
is not done in isolation,
Hawking collaborated
on most of his papers.
And you chip away with little
bits of knowledge and lots
and lots of different people
contributing new ideas,
building on the old, sometimes
breaking down the old
when we realise we've made a mistake
and building up higher
in a different direction.
And it's a real communal effort
and the number of physicists
working on these kinds
of questions is now huge,
and we're building on the foundation
that was left by Stephen Hawking
and many of his contemporaries
and those that came before.
