so if we uh consider where's my where's
my little set of atoms gone
uh where my atoms go
all right
if absolute zero all movement stops does
that include the orbit of electrons
around the nucleus of an atom
no
that's a really really good question
because that embodies i would argue at
least three modules worth lecture
modules worth of material to address
that that's a fantastic question you're
not going to take three modules with
your answer right
first of all
at the absolute zero of temperature
you can't get there but even if you
could and people can get down to very
very low temperatures
the electrons are still whizzing around
there are fluctuations uh in in
particles and uh
the summer caused by thermal excitations
that the temperature that you've just
talked about
and some are just intrinsically quantum
mechanical they're just that they're in
the system and so even if you call the
system to absolute zero which you can't
but if you could
then there'd still be the quantum
fluctuations and i think therefore they
could still be effectively orbits around
an atom first of all you can't reach
absolute zero and you can look at that
two ways you can look at that actually
put aside all the quantum mechanics
stuff and let's just look at the
thermodynamics that was done centuries
ago there's something called the third
law of thermodynamics loosely stated and
i don't want to raise the ire of all the
professional physicists out there but
loosely stated what the third law tells
us is that you can never in a finite
number of steps you can never reach
absolute zero
at high temperatures the atoms are
vibrating quite strongly about their
equilibrium positions these we can
regard these little bonds here as being
like springs and so the atoms are
vibrating and then as we cool down these
vibrations get less and less and less
but even as we approach absolute zero we
can never get rid of the zero-point
energy motion so the atoms will still
have this uh zero-point energy motion
associated with with quantum mechanics
at the quantum mechanical level we have
the heisenberg uncertainty principle and
heisenberg uncertainty principle tells
us we can never precisely know the
position of something because if we know
precisely the position of an electron
then we have a huge uncertainty in its
momentum and thus a huge uncertainty in
its energy which means it could in
principle have a you know a very very
large energy
uh according to quantum mechanics again
using heisenberg's uncertainty principle
electrons are confined in a small space
in the atom uh
so-called bore radius which is about 10
to the minus 10 meters and again
according to the laws of quantum
mechanics if they can find in that space
um
they are strongly confined and therefore
there's an uncertainty in their momentum
and velocity so they certainly aren't at
rest even at absolute zero quantum
mechanically you still have vibration
because you have a small amount of
uncertainty about where the position of
an electron or nucleus or an atom is
if the universe is expanding slower than
the speed of light
why hasn't the light from the big bang
already passed us you shouldn't it's a
mistake to think of the big bang
happening at a particular place the big
bang happened everywhere it's just at
the time everywhere was very close
together and since then everywhere has
been flying apart from everywhere else
but of course we were kind of in the
middle of the big bang when it happened
because we wanted part of that
everywhere and so the explosion the
light that that explosion created was
all around us then and has streamed away
from us but bits of the explosion that
were not where we are uh has been
traveling towards us and some of that's
arrived some of that's already past us
the big bang is isn't isn't
at a fixed point in the in space if you
like it's not that it happened there and
it didn't happen everywhere else space
and time are created from the big bang
so if you like as the universe is
expanding it's always got a remnant of
the big bang in it and we can actually
see it it's this thing called the cosmic
microwave background
the cosmic microwave background is a
very weak source of light it's very
wimpy sort of radio waves because the
explosion has cooled down a lot just
because of the expansion of the universe
but we can still detect it and in fact
you can see it for yourself if you turn
on your television and it's not tuned to
any particular channel so you just see
that fuzz on the screen about one
percent of the little fuzz that you see
there the apparent noise is actually you
your television detecting
cosmic microwave background photons so
you can actually see the light from the
big bang yourself this is the beauty of
looking out in astronomy
what we're not only looking out at
distances we're looking back in time
and so you one way of thinking about
those if you if you imagine we're at the
center of a big sphere and and the
surface of that sphere is
is that blanket of radiation and it's
just propagating to us and it's
propagating from all directions so so
now you can see that
whichever direction you look you're
going to be able to see some remnant of
this radiation it i mean it does
interact with each other and and it in
some sense it does go past us but it's
also coming from other directions that
one of the most amazing things about
this radiation of course is that it's so
uniform it's it's a com almost
completely uniform in temperature that's
showing that the universe is what is
called isotropic it looks the same in
all directions if i look out that
direction far enough and look out in
that direction far enough and can
measure the temperature of the radiation
coming back towards me it's it's almost
the same
it's the differences between that
radiation once you've taken out certain
effects like the fact that we're moving
through the milky way and
stuff like that once you once you take
those out those differences in those
temperatures is is is only about 10 to
the minus four degrees kelvin
are you good at sport
well i love playing cricket
not batting but i always loved
love bowling when i was a kid i wasn't
very good but i did i did enjoy get a
lot of fun out of that yeah making
batsman hurry a little bit but i was
never very good at it but great fun
i used to be i used to be
no absolutely
not
woefully bad terrible well
i think so i enjoy sports certainly i
play football with all the boys and
enjoy myself and they haven't kicked me
out yet so i guess that's okay
i try is i guess the short answer uh i
mean over the years i've done various
books i used to do quite a lot of judo
uh i used to be a goalkeeper for a
fighter side football team i used to
play
football
at my college as a goalkeeper and i got
this this
was kicked in by one of my defenders so
this is sunk and rotated round um i
actually think physical exercise is bad
for you you should keep away from it
look at all the damage that's done with
physical exercise with sports just keep
away from it if we didn't do it we'd be
much healthier i used to play
five-a-side football and i got a knee
bandage on still because i ruptured the
ligaments in my knee but uh
unfortunately sooner or later it caught
up with me and i ended up falling
awkwardly and tearing a whole bunch of
ligaments which kind of put an end to it
am i good at sport um i used to be
i used to be a rower and i used to be a
runner and i'm trying to become one
again
so yeah i like sport
so
when nature tells you that you really
can't walk around without a bandage
you'd give up the sports
i i i love sport and i would like to
think i'm really good at it but i'm not
good enough to uh have ever uh i played
at school and i played at university and
i
represented my local town at swimming
and i had trials for yorkshire at
cricket
so i was all right
but i never i never made it to the full
uh
level of a professional in or anywhere
near as good i would have loved to have
been but no
my father we lived in wembley my father
bought
two tickets for the world cup in 1966
and
he would go with either me
or my brother-in-law ian
and
as it turns out as my brother-in-law
reminds me
ian didn't go to the cup final i did so
i saw
england
win the world cup