Plasma universe (UCL)

Uploaded by UCLTV on 08.06.2011

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>> One of the things that interests me about the sun
in particular is the fact that it is this hot,
dense plasma sitting in the cold vacuum of space.
Plasma's often referred to as the fourth state of matter.
So if you have a solid, you can heat the solid,
and turn it into a liquid.
So first to second.
If you heat the liquid, you can turn it into a gas,
the third state, but if you keep heating your gas,
you can actually rip apart the atoms that make up the gas,
and you can tear the electrons from the atoms, and then you end
up with a plasma, which means you have a soup of positively
and negatively charged particles.
I think that plasma still invokes some sense of mystery
when you hear that word, and that maybe we think it is
some kind of exotic and uncommon substance,
and what we want to do this evening is show you
that actually it's a very interesting
and a very abundant substance.
As a space scientist, I'm extremely interested in plasma
because 99% of the known universe is in a plasma state.
I mean, most people in their day-to-day lives don't
necessarily experience plasma.
Maybe they're familiar with it because we have
so many plasma TVs now, but as a space scientist,
it's absolutely fundamental to understanding the universe.
We're looking at the plasma here which has a temperature
of about 80,000 Kelvin, 80,000 degrees Centigrade,
so incredibly hot gases, and it's actually helium
which is giving off the light at this temperature.
If you heat helium enough, you can make it shine
in the ultraviolet light.
I study our local plasmasphere, the sun.
So the sun's outer atmosphere is a very hot plasma,
and it actually is a very interesting physical place
to study, and it is also something
that really does directly impact us here on the Earth as well.
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