Hello. This is 6 Minute English from BBC
Learning English. I’m Sam.
And I’m Neil.
Have you ever made a snowman or enjoyed
a cold drink on a hot summer’s day?
Slippery in winter and cooling in summer,
ice is made when water gets so cold
it freezes. But there’s much more to
ice than skiing holidays and cold drinks.
Yes, in an exciting discovery, the
James Webb Space Telescope recently
detected the coldest ices ever in outer space,
something Nasa scientists think could
explain the origins of life on Earth.
For years scientists have debated how
life started on our planet. Billions of years
ago, long before the dinosaurs, animals
or even plants existed, the Earth had a
watery environment of oxygen-free gases
and chemicals known as the primordial soup.
It had the potential for life to develop,
but something was missing.
So how did we jump from the primordial soup
to the first living plants, animals, and eventually
humans? And how does ice fit into the story?
That’s what we’ll be finding out in this
programme, and as usual, we’ll be learning
some useful new vocabulary as well.
But first I have a question for you, Neil.
We know ice is frozen water, but do you
know the chemical symbol for water?
Is it: a) H2O, b) HO2 or c) H2O2?
Well, I really hope I get this right.
I think the answer is H2O.
OK, we’ll find out or check if you’re right
later in the programme. Astronomer,
Professor Melissa McClure, worked with the
Nasa scientists who found ice on Europa,
one of Jupiter’s moons. Here she explains to
BBC World Service programme, Science in
Action, one theory linking ice to
the beginnings of life on Earth.
There's sort of these two alternatives for how
you could have had life arise on Earth, and one
is that the very basic building blocks, like
water, and methane, and CO2 – like, those
molecules were definitely brought to Earth
by ices in comets, and maybe once they
were on Earth, then they reacted with
either geothermal heat or some kind of lightning
strike to form more complex molecules.
Earth’s primordial soup lacked the building
blocks of life – a phrase describing the
most basic biological and chemical units
needed to support living things,
elements like oxygen and carbon.
Professor McClure thinks these missing
elements were brought to Earth in comets - large
bright balls of dirt and ice which travel around
the Sun in outer space.
It’s possible that when comets hit Earth
billions of years ago, elements in the ice were
scattered and struck by lightning – a bright
flash of light produced by electricity moving
in the atmosphere. This resulted in the
complex molecules needed for life on Earth.
Exactly how this happened is not known,
but it involves biomolecules, molecules like
DNA which are found in living things. Ice is
not a biomolecule, but when it mixes with
carbon, the atoms in ice molecules
change to produce complex molecules – and
that’s when interesting things start to happen.
Here’s Professor McClure again, explaining
more to BBC World Service’s, Science in Action.
If they have a carbon atom in them then
they’re complex organic molecules, so
things like very simple alcohols like methanol
or ethanol, like what you would drink, are
complex organic molecules. And these
molecules could react and start a sort of a
reaction chain that would eventually lead
to something like a biomolecule.
Ice can react with other elements to create
organic molecules, for example the alcohol,
methanol. Here, the adjective organic means
related to living plants and animals. That’s
different from how we use the word to talk
about ‘organic food’, meaning food that
hasn’t been grown using artificial chemicals.
When these organic molecules met the
primordial soup - so the theory goes - it
produced a chain reaction – a series of
chemical reactions in which one change causes
another. It was this chain reaction which
created the first living cells and eventually,
humans. Quite impressive for a
little piece of frozen water!
Speaking of water, Sam, what was the answer
to your question about the chemical
symbol for water. I said it was H2O.
Which was the right answer, Neil! Each
molecule of water, and ice, contains
two atoms of H, that’s hydrogen, joined to
one atom of oxygen. OK, let’s recap the
vocabulary we’ve learned from the programme,
starting with primordial soup – the
environment on Earth before there were
any plants or animals, which
created the conditions for life.
The phrase the building blocks of life refers
to the most basic biological and chemical
units needed to support
living plants and animals.
A comet is a large object travelling in space
which orbits the sun and
has a bright, burning tail.
Lightning is a flash of bright light produced
by electricity moving in the atmosphere.
The adjective organic means relating to
living plants and animals. And ‘organic food’
means food which has been
grown without using chemicals.
And finally, a chain reaction is a series of chemical
reactions in which one change causes another
which in turn causes another.
Once again, our six minutes are up. Goodbye!
Bye bye!