The Dangers of Deep Sea Diving
Forget sharks and predatory animals—the most dangerous aspect of diving is oxygen.
Question: How do you prepare for a dive?
Sylvia Earle: Well preparing for a dive takes different forms depending on what kind of dive you’re going to do. If you’re just going to go snorkeling or holding your breath diving down... no preparation needed, just take a big breath and down you go. Of course it’s nice to have a facemask. It helps to have flippers. It helps if you’re in cold water to have a wetsuit or even a dry suit that will keep you warm if you want to stay more than just a moment or two. For using scuba you first want to make sure that you have air in your tank, that, again the same old thing, that you want to be warm diving in cold water. You’ve got to prepare for that. Using self-contained underwater breathing apparatus, SCUBA, requires a little bit of training, not a lot. The more you do it the more comfortable you are, the more experienced, the more able you are to cope with the unexpected should circumstances arise, but mainly it’s very simple. My instruction back in 1953, before there were classes in learning how to dive was very simple. Two words, breathe naturally, don’t hold your breath because if you do hold your breath while you have compressed air that you have taken in while breathing and you ascend the air that is in your body, in your lungs, in your tissues will expand as you come closer to the surface as you begin to take the pressure off. That’s dangerous. You can embolize. You can get bubbles in your bloodstream. You can get the bends. So "breathe naturally" was really good advice because as you exhale you eliminate the air that you have in your lungs and so you learn not to stay too long because after awhile the air that you breathe, the nitrogen actually gets into your bloodstream, forms little bubbles and you can stay for a short period of time and all of this is closely calculated. You know exactly how long you can stay before you have to count in decompression before coming back to the surface.
A lot of this has been learned in the last 50 years the hard way, by people who have made mistakes who have tried it and have learned that they need to do things differently. I have been part of that learning curve I suppose. In 1970 for the first time I had a chance to live underwater. They call it saturation diving. You stay underwater at a certain depth long enough for your tissues to become saturated with the breathing mix that you’re inhaling. In the first case it wasn’t just air. It was a mixture of nitrogen and oxygen with somewhat less oxygen than we have at the surface and therefore a little more nitrogen because oxygen actually can become toxic if you breathe it under pressure for a long time at a certain depth, below about 30 feet, 60 feet it becomes toxic, dangerous. You can go into convulsions if you have too much oxygen. "How can you have too much oxygen?" you might say. "We need oxygen." We do, but too much oxygen even for us under the right or wrong circumstances can be lethal. It can certainly be harmful, so these are all things that in the process of learning how to dive you can learn and figure out and then…
But it’s a bit like using a telephone. We take for granted that you can pick it up and talk into it. Engineers have carefully crafted the technology so that it is easy to use. Engineers have carefully crafted the mechanism so you can just breathe into a regulator and not actually have to understand how it works if you trust the engineers and I’ve come to rely on engineers through much of what I’ve done to gain access to the sea. I try to understand how the processes work so that if something goes wrong I can react and adjust accordingly, but since I personally am not an engineer I try to work with them to do the heavy lifting when it comes to doing the calculations, getting the systems so that they will work when they need to work. That goes for scuba apparatus. It goes for little submarines that I’ve had the joy of using. I’ve been on the inside track of building submarines, so I do kind of understand what it takes, but I leave the actual calculations to those who know more about it than I do.
Recorded April 14th, 2010
Interviewed by Austin Allen
Forget sharks and predatory animals—the most dangerous aspect of diving is oxygen.
It's just the current cycle that involves opiates, but methamphetamine, cocaine, and others have caused the trajectory of overdoses to head the same direction
- It appears that overdoses are increasing exponentially, no matter the drug itself
- If the study bears out, it means that even reducing opiates will not slow the trajectory.
- The causes of these trends remain obscure, but near the end of the write-up about the study, a hint might be apparent
Through computationally intensive computer simulations, researchers have discovered that "nuclear pasta," found in the crusts of neutron stars, is the strongest material in the universe.
- The strongest material in the universe may be the whimsically named "nuclear pasta."
- You can find this substance in the crust of neutron stars.
- This amazing material is super-dense, and is 10 billion times harder to break than steel.
Superman is known as the "Man of Steel" for his strength and indestructibility. But the discovery of a new material that's 10 billion times harder to break than steel begs the question—is it time for a new superhero known as "Nuclear Pasta"? That's the name of the substance that a team of researchers thinks is the strongest known material in the universe.
Unlike humans, when stars reach a certain age, they do not just wither and die, but they explode, collapsing into a mass of neurons. The resulting space entity, known as a neutron star, is incredibly dense. So much so that previous research showed that the surface of a such a star would feature amazingly strong material. The new research, which involved the largest-ever computer simulations of a neutron star's crust, proposes that "nuclear pasta," the material just under the surface, is actually stronger.
The competition between forces from protons and neutrons inside a neutron star create super-dense shapes that look like long cylinders or flat planes, referred to as "spaghetti" and "lasagna," respectively. That's also where we get the overall name of nuclear pasta.
Caplan & Horowitz/arXiv
Diagrams illustrating the different types of so-called nuclear pasta.
The researchers' computer simulations needed 2 million hours of processor time before completion, which would be, according to a press release from McGill University, "the equivalent of 250 years on a laptop with a single good GPU." Fortunately, the researchers had access to a supercomputer, although it still took a couple of years. The scientists' simulations consisted of stretching and deforming the nuclear pasta to see how it behaved and what it would take to break it.
While they were able to discover just how strong nuclear pasta seems to be, no one is holding their breath that we'll be sending out missions to mine this substance any time soon. Instead, the discovery has other significant applications.
One of the study's co-authors, Matthew Caplan, a postdoctoral research fellow at McGill University, said the neutron stars would be "a hundred trillion times denser than anything on earth." Understanding what's inside them would be valuable for astronomers because now only the outer layer of such starts can be observed.
"A lot of interesting physics is going on here under extreme conditions and so understanding the physical properties of a neutron star is a way for scientists to test their theories and models," Caplan added. "With this result, many problems need to be revisited. How large a mountain can you build on a neutron star before the crust breaks and it collapses? What will it look like? And most importantly, how can astronomers observe it?"
Another possibility worth studying is that, due to its instability, nuclear pasta might generate gravitational waves. It may be possible to observe them at some point here on Earth by utilizing very sensitive equipment.
The team of scientists also included A. S. Schneider from California Institute of Technology and C. J. Horowitz from Indiana University.
Check out the study "The elasticity of nuclear pasta," published in Physical Review Letters.
Scientists think constructing a miles-long wall along an ice shelf in Antarctica could help protect the world's largest glacier from melting.
- Rising ocean levels are a serious threat to coastal regions around the globe.
- Scientists have proposed large-scale geoengineering projects that would prevent ice shelves from melting.
- The most successful solution proposed would be a miles-long, incredibly tall underwater wall at the edge of the ice shelves.
The world's oceans will rise significantly over the next century if the massive ice shelves connected to Antarctica begin to fail as a result of global warming.
To prevent or hold off such a catastrophe, a team of scientists recently proposed a radical plan: build underwater walls that would either support the ice or protect it from warm waters.
In a paper published in The Cryosphere, Michael Wolovick and John Moore from Princeton and the Beijing Normal University, respectively, outlined several "targeted geoengineering" solutions that could help prevent the melting of western Antarctica's Florida-sized Thwaites Glacier, whose melting waters are projected to be the largest source of sea-level rise in the foreseeable future.
An "unthinkable" engineering project
"If [glacial geoengineering] works there then we would expect it to work on less challenging glaciers as well," the authors wrote in the study.
One approach involves using sand or gravel to build artificial mounds on the seafloor that would help support the glacier and hopefully allow it to regrow. In another strategy, an underwater wall would be built to prevent warm waters from eating away at the glacier's base.
The most effective design, according to the team's computer simulations, would be a miles-long and very tall wall, or "artificial sill," that serves as a "continuous barrier" across the length of the glacier, providing it both physical support and protection from warm waters. Although the study authors suggested this option is currently beyond any engineering feat humans have attempted, it was shown to be the most effective solution in preventing the glacier from collapsing.
Source: Wolovick et al.
An example of the proposed geoengineering project. By blocking off the warm water that would otherwise eat away at the glacier's base, further sea level rise might be preventable.
But other, more feasible options could also be effective. For example, building a smaller wall that blocks about 50% of warm water from reaching the glacier would have about a 70% chance of preventing a runaway collapse, while constructing a series of isolated, 1,000-foot-tall columns on the seafloor as supports had about a 30% chance of success.
Still, the authors note that the frigid waters of the Antarctica present unprecedently challenging conditions for such an ambitious geoengineering project. They were also sure to caution that their encouraging results shouldn't be seen as reasons to neglect other measures that would cut global emissions or otherwise combat climate change.
"There are dishonest elements of society that will try to use our research to argue against the necessity of emissions' reductions. Our research does not in any way support that interpretation," they wrote.
"The more carbon we emit, the less likely it becomes that the ice sheets will survive in the long term at anything close to their present volume."
A 2015 report from the National Academies of Sciences, Engineering, and Medicine illustrates the potentially devastating effects of ice-shelf melting in western Antarctica.
"As the oceans and atmosphere warm, melting of ice shelves in key areas around the edges of the Antarctic ice sheet could trigger a runaway collapse process known as Marine Ice Sheet Instability. If this were to occur, the collapse of the West Antarctic Ice Sheet (WAIS) could potentially contribute 2 to 4 meters (6.5 to 13 feet) of global sea level rise within just a few centuries."
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