If you ever want to experience and an alien world then look no further than the world's oceans.
It was giant leap for mankind to walk along the moon, but walking
on the ocean floor will take us to the very limits of what's possible.
At 1814 meters in length the Busselton Jetty is amongst the longest in the world.
Even so, you'd need to stick two such jetties end-to-end to reach the oceans floor which is still
only a third of the way to the very bottom of the Mariana Trench. For every
10 meters we descend pressure increases by 1 bar the equivalent of an atmosphere
pressure, or what we experience at sea level. This means that if we were to tip
the jetty onto its end and stand at bottom then we be experiencing 180 bar
pressure. This is to the equivalents of been holding 150 ton blue whale in the
palm of my hand. This pressure acts on all points in your
body, pushing them inwards. Solids and liquids can handle the squeeze but air
cavities get shrunk. The air inside my helmet its kept at high pressure. This
allows my lungs to expand and also stops my ears from exploding. As we descend deeper
and deeper and pressures increases, then we so too to need to increase the
pressure inside the helmet. Gases dissolve in liquids which is how fish
can breathe oxygen while remaining underwater. The amount of gas which can
be dissolved is proportional to the pressure of that gas. Higher pressure
means more gas can be dissolved. This is known as Henry's law. In order to
illustrate how this can be a problem for divers, I've brought with me this
bottle of soft drink into which is dissolved about 50 liters of carbon
dioxide. It's kept in solution due to extreme pressure; about 80 bar of it.
However, if we were to release it suddenly then it all it escapes into a fountain
of sugar and bubbles. Now imagine that but in your blood
high-pressure nitrogen in the air which drivers breathe readily dissolves into
the bloodstream, coming out if they ascend too quickly. It accumulates around the
joints, which is why decompression sickness is
often cooled the bends. Even on the way down high-pressure gases will still kill you
in particular, through nitrogen narcosis and oxygen toxicity; both of which can
knock you out by the time you reach 100 meters. This is because our bodies just
weren't designed to deal with extreme concentrations of these gases inside our
bloodstream. In order to counteract this divers going to extreme depths will
replace these gases but something like helium. While all gases will eventually
kill you, some take much greater pressures to do so. Technical divers use
nitrox heliox and other exotic mixtures to work on deep-sea
infrastructure. Even so, the farthest we've been able to reach is 330 meters.
All of these problems stem from using high-pressure air, so what if we removed
the need for air entirely. That's the idea behind liquid breathing; an
experimental and in some ways terrifying new form of respiration. As featured in
James Cameron's "The Abyss", liquid breathing uses a special family of
molecules known as perflurocarbons which possess just the right structure to
dissolve large quantities of oxygen. The blood vessels within your lungs
Can't tell the difference between oxygen held in the air with oxygen
health in perflurocarbon and will take it in just as readily. The technology
works so well that the rat scene in the movie uses a real-life rodent which is
breathing in a perflurocarbon mixture. The humans however were acting.
Perflurocarbons are much more viscous than air, which means that a special type of
respirator is needed to push the liquid in and out of your lungs.
While delivering oxygen has been pretty successful, it's much harder to remove
carbon dioxide. On top of that from the limited human trials we've conducted the
whole experience feels like drowning. As pressures increase further and further
our very cells starts betray us. In 2013 the ugly animal Preservation Society
voted the blobfish as the world's ugliest animal. However I
think they're being a little bit unfair. The blobfish
or psychrolutes marcidus are a species of fish living off the Australian
coast in depth of up to 1.2 kilometers. Down here
they don't look nearly as bad. This fish, just like all life on Earth, is made up
of cells which contain a cell membrane. This allows nutrients waste and
signaling molecules to be transported. At high pressure the lipids which make up
this membrane become much more stiff preventing transport from occurring. To
counteract this the blobfish uses much softer lipids, akin to substituting
butter for vegetable oil. Combined with extreme pressure, the resulting rigidity
is perfect for life in the abyss. Unfortunately when we humans bring these
fish up to the surface, the low-pressure reveals their soft gelatinous foundation.
With our human cells optimised to operate at pressures of one atmosphere
as we descend deeper and deeper and pressures increase the lipids which make
up our cell membranes becomes so rigid that they cease to function correctly.
After one kilometre blackouts and death ensur. Until we turn into human-shaped
blobfish this is the hard limit on how deep we can dive.
Walking along oceans floor will make us face new challenges, both in engineering as well it's as
our very biology. For now the oceans depths lay firmly out of reach.
This has been James Dingley from the Atomic Frontier. Keep Looking Up.