I recall on a film about the deep sea (The Abyss I think) the deep sea divers where breathing in liquid oxygen instead of gas form as you can carry less of this around. How viable is this idea, can we breath liquid oxygen? Im not sure how cold this is which i think would be a problem for us but wouldn't a similar form be the best idea for breathing under water or far distance space travel?
It would have to be damn cold, I think I remember being told its boiling/condesing temperature is about -180 C (my internets gone funny again so I can't search, or go on any other websites apart form the two I have open)
I think it was a "magic" substance simply introduced for the plot.
At depth the amount of oxyen that you absorb goes up as the pressure does (the partial pressure)
With normal air (20% or so O2) the partial pressure of O2 starts to make you feel a little drunk at delow 30m or so.
This is called Nitrogen Narcosis or "Narks"
This increases as you go deeper - amateur diving is usually limited to 50m for this reason. I think it becomes totally toxic at about 90m.
For this reason commercial divers switch at depth to a mixture that contains less Oxygen. It normally replaces Nitrogen with Helium too as this reduces the risk of the bends.
The plot idea was that if you breathed a liquid you'd have no cavities in the body that could be crushed at deph. But there is a lot more to it than that as you can see with the oxgen toxicity problem
No Jake nitrogen narcosis is quite separate from the oxygen partial pressure matter. That is why deep divers use helium, the partial pressure of oxygen can be adjusted in the gas mixture but nitrogen is no good as a carrier or diluent gas because of the narcosis problem. I have no idea what the mechanism for nitrogen narcosis is though.
It has been thought about and already done. A liquid that can transport oxygen is available.
A liquid is used for diving to great depth. Gasses get more dense and viscous under pressure. This is why helium oxygen mixture is used for deep diving. Helium's low atomic number keeps its viscosity low under pressure.
But it does keep getting thicker as depth increases. Liquids don't increase viscosity with depth and remain breathable. The maximum depth using liquid breathing is unknown.