My name's Jim Al-Khalili, and I'm a
professor of physics at the University of Surrey
so my area of expertise is theoretical
physics, so I deal with the equations
and the mathematics of physics
At the moment we don't have any alternatives to the Big Bang theory -  this is all the evidence
and it's very powerful evidence, points to the universe having a very definite beginning 13.8 billion years ago
throughout the sixties and seventies
evidence became available, for instance
suggesting that if the Big Bang theory
was correct
the temperature of deep space should be
a specific temperature, and sure enough
that's what was found. If the Big Bang
theory was correct then all the elements
we see in the universe, hydrogen, helium,
their distribution should be a certain proportion
that's exactly what we see, so everything
we look at,  the expansion of the universe
that it's getting bigger, so in the past
it must have been smaller
if you wind the clock back far enough
you reach a point in time that was the
beginning.  All of it points to the Big Bang theory
so that is not in any doubt.  The
question of life is a quite separate one
because you need the Big Bang to create
the universe and then the universe
within the universe you have to have
stars and galaxies form and planets to
form and the complex elements to be
cooked inside stars, only then can life emerge
How life began? Now that's still a mystery
Obviously, Sheldon
He's everyone's favorite character.
Sheldon has done as much as anyone in
the last 20 years to make physics cool
so yeah he's brilliant
Yes, and we don't know
because there's two kinds of time travel. There's time travel to the future and that
is possible because we can slow time
down either by traveling close to the
speed of light or finding a black hole
that we can orbit around for a while
Einstein said very clearly that by
slowing time down
you can reach the future, but the other
type of time travel, the more interesting
type is going back to the past, and
that's where I say we don't know because
Einstein's theory of relativity, our best theory
current theory of the nature of time
says yes it's possible
and yet it leads to many paradoxes, and
we're not quite sure how to resolve
these paradoxes, maybe there are parallel universes
maybe Einstein's theory needs
to be replaced with something better or
that some adjustment that rules out time
travel so for the moment is not
impossible, but we're not quite sure just yet
I think in my area of physics the next
big thing will be to discover
what particles make up dark matter. Dark
matter makes up over ninety percent of
all the stuff in the universe, all the
mass in the universe and yet we don't
know what it's made of. Now there are 
experiments in CERN at the large
Hadron Collider which we hope in the
coming next few years will discover new
type of particle, and that we will be
able to say that's the particle that
dark matter is made of, and that will be
a very exciting discovery, and certainly it
will win Nobel prizes for people, but
it is one of these big mysteries that
everyone says we must know the answer to this
And that led to important discoveries
about the nature of electrons that led
to important discoveries about x-rays
and actually also led to the invention
of the television
