Earth’s average air pressure at sea level is 14.7 pounds per square inch. That means every square inch in every direction, both the outside and the inside of your nostrils, for example. And because the pressure on the inside of your nose, except for those deep breaths, equals the pressure on the outside. The flimsy cartilage isn’t compressed against the septum. Your body evolved to stand up to the weight of an atmosphere some 500 miles thick and all those jumbled air molecules banging together. That banging is measured as the pressure.
“But it’s just air, right? How can it exert such force?” It’s still matter regardless of its being an invisible gas, so gravity makes it, as it makes you, have weight. All those air molecules bang together in random directions exerting pressure. You live beneath an ocean of air where the air pressure is higher. Farther up, less overlying atmosphere, less pressure. Deeper down, say in a mine below sea level, higher pressure. Now imagine the pressure under the ocean of water, say at the location of the sunken Titanic.
Crushing Pressure
Let’s go with close approximations: If you scuba dive, you increase the (hydrostatic) pressure on you body by one atmosphere for every 33 feet of descent. At a depth of 33 feet, therefore, you bear the weight of two atmospheres (29.4 lbs/sq. in). At about 66 feet down, you have to bear up against three atmospheres of pressure, or 44.1 pounds per square inch. You can do the math for every unit of 33 feet of increased depth, generally adding up uniformly since water is not a very compressible compound (thus its use in hydraulics) though it undergoes some squeezing at great depth. Now calculate the pressure at a depth of 13,000 feet, that is, more than two miles (5,280 ft X 2) down. Those water molecules bang together under the weight of the overlying water.
Okay, too lazy to get out the calculator or put pen to paper? Thirteen thousand divided by 33 equals 393.9 times 14.7. Add the one atmosphere of sea level pressure to that number and you’ll get 5,790.33 pounds per square inch. Crushing pressure.
Styrofoam Cup
I remember a styrofoam cup dropped into the depths of the “Tongue of the Ocean” in the Bahamas. Open on one end like your nose, it was squeezed into a miniature version of itself, and even though it expanded on its way back up to the surface, it still wouldn’t make a decent shot glass back on the surface. Had it been enclosed, it would have looked like a small pith ball.
Need any more of a lesson? Then suck the air out of an empty plastic water bottle to see the crushing pressure of the atmosphere at work. As you lessen the pressure on the inside, the outside pressure implodes the plastic.
Even Military Subs Have Limited Dive Depths
I recall the tragic accident of the USS Thresher, an atomic submarine that sank below its dive depth, that is, below the pressure its hull was designed to withstand. Photos of the wreck revealed the implosion that destroyed it and its crew. When the Navy attempted to contact the vessel, it picked up a distress signal, but there was no way of saving anyone who might have survived the initial crushing. If you have ever used a power washer, you know its ability to cut through wood. Pressure (power) washers range from about 1,800 pounds per square inch to about 3,000 psi. Now imagine increasing that to the 5,790.33 psi at a depth of 13,000 feet. Those inside the Thresher where the ocean breached any part of the hull would have probably been killed instantly, shredded by that “pressure washer.”
So, diving to great depths is a dangerous activity. We know it, but we still do it. And today the Coast Guard is searching for a lost deep-dive submersible that descended with paying ($250,000 each) customers to see the Titanic at 13,000 feet. As of this writing on June 21, 2023, the pilot and passengers are still missing with time running out on their air supply—that is, running out if the vessel hasn’t already imploded under the pressure of 5,790 pounds per square inch.
Pressure Changes with Altitude, also
Would you spend $250,000 for a day of pleasure if you knew there was a real possibility that you might be almost instantly shredded if the hull is breached? “Maybe,” you say, “I don’t have that kind of money. Heck, a trip to Disney’s make-believe worlds drains my credit card; I’m certainly not about to fork over a quarter mil to put myself in a dangerous predicament at 13,000 feet. Anyway, I saw the movie and the documentaries.”
But have you ever taken a flight in a pressurized airplane? Going up is also fraught with danger from pressure change as a recent private airplane wreck indicates. The crash of that jet seems to have resulted from a loss of cabin pressure, just the opposite of the probable fate of the missing submersible.
What’s Your Point, Donald?
Life is risky at best, but we’re inclined to evaluate potentially equally dangerous actions as less risky than others, especially when we judge them in the context of their rewards. Millions of us take flights on pressurized planes without much thought about cabin pressure. Thus, millions accept flying as a minimal risk, though still a risk. Some of us recognize more risky ventures, but engage in them anyway. Comedian Brian Regan has a skit about a party in which some braggadocio tries to impress everyone with his exploits only to have another partygoer, an astronaut, quietly say, “I walked on the moon”—a feat impossible to top by any Earthbound braggadocio.
Apparently, some of us have brains that demand a diet of high risk so we can feast on neurotransmitters. Climbing ice walls, climbing tall buildings just to get a selfie, or skydiving are among the risky actions we take. Millions of us have played contact sports, skied down steep rocky or treed slopes, gone snorkeling in waters where sharks live, or driven over the speed limit on a country road. We constantly face and evaluate risks that we take in the contexts of their potential rewards.
Some risks are avoidable, but living on this planet means submersion in an ocean of risks from sitting on a bus next to a coughing rider to eating at a buffet in Vegas, where some previous diner might have done some double-dipping in the condiments. Risk is inevitable.
But very risky ventures are not inevitable, such as climbing Mt. Everest or spending $250,000 to see the Titanic that lies almost 13,000 feet underwater. Sure, those who survive can say at a party, “I climbed Mt. Everest,” or “I dived to see the Titanic,” but the dead never get that rush of neurotransmitters.
We make inferences all the time. Those aboard the submersible, even after signing the waiver that mentions the word death three times, certainly inferred their safety. Right now I assume that my desk chair will hold me while I type this. I assume that the floor of a public building won’t collapse beneath my weight. Of course, the risks of both of those seem minimal. But they do exist, and they make a point about living. Our ability to evaluate risk is what enables us to live without anxiety.
This Is Not Your Practice Life
Every so often I feel the need to reiterate the main theme of this website. Seeing the news about the missing submersible has brought that saying to the forefront of my brain. But I have been as guilty of taking risks as others, and two ocean experiences come to mind.
One: I decided to go ocean kayaking by myself off St. Thomas. As I rowed seaward, I found myself fighting a current that carried me toward a rocky promontory. Waves increased in height, with crests higher than my head when I was in the wave troughs. So, I had to row like some olympic sculler. That I am writing this little incident today indicates that I rowed myself out of danger. Whew! Lesson learned: I won’t go off kayaking alone in choppy waters and strong currents.
Two: Scuba diving off the Pitons of St. Lucia, I found myself sinking because I hadn’t adjusted for “neutral buoyancy” as I got caught up in looking at the coral environment and tumbled volcanic blocks that ocean life had colonized. Toward the end of the dive I had to use more of my tank’s air for buoyancy, more, that is, than normal. That limited my dive time. When I found myself at 90 feet, I realized that I had to ascend to spend the requisite five minutes at 15 feet to avoid the bends. As I watched my tank’s pressure gauge fall toward the “red” zone, I remember being somewhat anxious, my mortality revealing itself through the voluntary risk I had taken. But, again, Whew! I’m here.
As the deaths of uncounted seafarers reveal, the ocean has been merciless. The convenience and relative safety of sea travel today coupled with luxury unknown in ancient, medieval, and early modern times seem to minimize risk, but the Titanic’s and the nuclear USS Thresher’s sinking—like the sinking of other vessels—inform us that dangers still exist. Signing a waiver doesn’t eliminate the risk. Supposed rational justification doesn’t change the level of danger. The brain can fool itself, misjudge, and mistake potential rewards for failsafe assurances. *
Comparative Risks
You’ve heard it from friends and family: “Drive safely.” Those in the submersible, possibly today beyond rescue, might have heard “Dive safely.” But no advice serves when we take extraordinary risks, such as riding a rocket into space or taking a submersible into the depths just for the sake of the experience or for the sake of saying something like Regan’s astronaut’s incomparable “I walked on the moon.”
*A lesson that all criminals should learn before they engage in criminal activity like home invasion or robbery and a lesson all spring breakers should learn before drinking heavily on a hotel balcony.
“But it’s just air, right? How can it exert such force?” It’s still matter regardless of its being an invisible gas, so gravity makes it, as it makes you, have weight. All those air molecules bang together in random directions exerting pressure. You live beneath an ocean of air where the air pressure is higher. Farther up, less overlying atmosphere, less pressure. Deeper down, say in a mine below sea level, higher pressure. Now imagine the pressure under the ocean of water, say at the location of the sunken Titanic.
Crushing Pressure
Let’s go with close approximations: If you scuba dive, you increase the (hydrostatic) pressure on you body by one atmosphere for every 33 feet of descent. At a depth of 33 feet, therefore, you bear the weight of two atmospheres (29.4 lbs/sq. in). At about 66 feet down, you have to bear up against three atmospheres of pressure, or 44.1 pounds per square inch. You can do the math for every unit of 33 feet of increased depth, generally adding up uniformly since water is not a very compressible compound (thus its use in hydraulics) though it undergoes some squeezing at great depth. Now calculate the pressure at a depth of 13,000 feet, that is, more than two miles (5,280 ft X 2) down. Those water molecules bang together under the weight of the overlying water.
Okay, too lazy to get out the calculator or put pen to paper? Thirteen thousand divided by 33 equals 393.9 times 14.7. Add the one atmosphere of sea level pressure to that number and you’ll get 5,790.33 pounds per square inch. Crushing pressure.
Styrofoam Cup
I remember a styrofoam cup dropped into the depths of the “Tongue of the Ocean” in the Bahamas. Open on one end like your nose, it was squeezed into a miniature version of itself, and even though it expanded on its way back up to the surface, it still wouldn’t make a decent shot glass back on the surface. Had it been enclosed, it would have looked like a small pith ball.
Need any more of a lesson? Then suck the air out of an empty plastic water bottle to see the crushing pressure of the atmosphere at work. As you lessen the pressure on the inside, the outside pressure implodes the plastic.
Even Military Subs Have Limited Dive Depths
I recall the tragic accident of the USS Thresher, an atomic submarine that sank below its dive depth, that is, below the pressure its hull was designed to withstand. Photos of the wreck revealed the implosion that destroyed it and its crew. When the Navy attempted to contact the vessel, it picked up a distress signal, but there was no way of saving anyone who might have survived the initial crushing. If you have ever used a power washer, you know its ability to cut through wood. Pressure (power) washers range from about 1,800 pounds per square inch to about 3,000 psi. Now imagine increasing that to the 5,790.33 psi at a depth of 13,000 feet. Those inside the Thresher where the ocean breached any part of the hull would have probably been killed instantly, shredded by that “pressure washer.”
So, diving to great depths is a dangerous activity. We know it, but we still do it. And today the Coast Guard is searching for a lost deep-dive submersible that descended with paying ($250,000 each) customers to see the Titanic at 13,000 feet. As of this writing on June 21, 2023, the pilot and passengers are still missing with time running out on their air supply—that is, running out if the vessel hasn’t already imploded under the pressure of 5,790 pounds per square inch.
Pressure Changes with Altitude, also
Would you spend $250,000 for a day of pleasure if you knew there was a real possibility that you might be almost instantly shredded if the hull is breached? “Maybe,” you say, “I don’t have that kind of money. Heck, a trip to Disney’s make-believe worlds drains my credit card; I’m certainly not about to fork over a quarter mil to put myself in a dangerous predicament at 13,000 feet. Anyway, I saw the movie and the documentaries.”
But have you ever taken a flight in a pressurized airplane? Going up is also fraught with danger from pressure change as a recent private airplane wreck indicates. The crash of that jet seems to have resulted from a loss of cabin pressure, just the opposite of the probable fate of the missing submersible.
What’s Your Point, Donald?
Life is risky at best, but we’re inclined to evaluate potentially equally dangerous actions as less risky than others, especially when we judge them in the context of their rewards. Millions of us take flights on pressurized planes without much thought about cabin pressure. Thus, millions accept flying as a minimal risk, though still a risk. Some of us recognize more risky ventures, but engage in them anyway. Comedian Brian Regan has a skit about a party in which some braggadocio tries to impress everyone with his exploits only to have another partygoer, an astronaut, quietly say, “I walked on the moon”—a feat impossible to top by any Earthbound braggadocio.
Apparently, some of us have brains that demand a diet of high risk so we can feast on neurotransmitters. Climbing ice walls, climbing tall buildings just to get a selfie, or skydiving are among the risky actions we take. Millions of us have played contact sports, skied down steep rocky or treed slopes, gone snorkeling in waters where sharks live, or driven over the speed limit on a country road. We constantly face and evaluate risks that we take in the contexts of their potential rewards.
Some risks are avoidable, but living on this planet means submersion in an ocean of risks from sitting on a bus next to a coughing rider to eating at a buffet in Vegas, where some previous diner might have done some double-dipping in the condiments. Risk is inevitable.
But very risky ventures are not inevitable, such as climbing Mt. Everest or spending $250,000 to see the Titanic that lies almost 13,000 feet underwater. Sure, those who survive can say at a party, “I climbed Mt. Everest,” or “I dived to see the Titanic,” but the dead never get that rush of neurotransmitters.
We make inferences all the time. Those aboard the submersible, even after signing the waiver that mentions the word death three times, certainly inferred their safety. Right now I assume that my desk chair will hold me while I type this. I assume that the floor of a public building won’t collapse beneath my weight. Of course, the risks of both of those seem minimal. But they do exist, and they make a point about living. Our ability to evaluate risk is what enables us to live without anxiety.
This Is Not Your Practice Life
Every so often I feel the need to reiterate the main theme of this website. Seeing the news about the missing submersible has brought that saying to the forefront of my brain. But I have been as guilty of taking risks as others, and two ocean experiences come to mind.
One: I decided to go ocean kayaking by myself off St. Thomas. As I rowed seaward, I found myself fighting a current that carried me toward a rocky promontory. Waves increased in height, with crests higher than my head when I was in the wave troughs. So, I had to row like some olympic sculler. That I am writing this little incident today indicates that I rowed myself out of danger. Whew! Lesson learned: I won’t go off kayaking alone in choppy waters and strong currents.
Two: Scuba diving off the Pitons of St. Lucia, I found myself sinking because I hadn’t adjusted for “neutral buoyancy” as I got caught up in looking at the coral environment and tumbled volcanic blocks that ocean life had colonized. Toward the end of the dive I had to use more of my tank’s air for buoyancy, more, that is, than normal. That limited my dive time. When I found myself at 90 feet, I realized that I had to ascend to spend the requisite five minutes at 15 feet to avoid the bends. As I watched my tank’s pressure gauge fall toward the “red” zone, I remember being somewhat anxious, my mortality revealing itself through the voluntary risk I had taken. But, again, Whew! I’m here.
As the deaths of uncounted seafarers reveal, the ocean has been merciless. The convenience and relative safety of sea travel today coupled with luxury unknown in ancient, medieval, and early modern times seem to minimize risk, but the Titanic’s and the nuclear USS Thresher’s sinking—like the sinking of other vessels—inform us that dangers still exist. Signing a waiver doesn’t eliminate the risk. Supposed rational justification doesn’t change the level of danger. The brain can fool itself, misjudge, and mistake potential rewards for failsafe assurances. *
Comparative Risks
You’ve heard it from friends and family: “Drive safely.” Those in the submersible, possibly today beyond rescue, might have heard “Dive safely.” But no advice serves when we take extraordinary risks, such as riding a rocket into space or taking a submersible into the depths just for the sake of the experience or for the sake of saying something like Regan’s astronaut’s incomparable “I walked on the moon.”
*A lesson that all criminals should learn before they engage in criminal activity like home invasion or robbery and a lesson all spring breakers should learn before drinking heavily on a hotel balcony.
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