7 ms·

This reminds me of a line from "Bill Nye the Science Guy" from when I was younger. Here's what my fuzzy memory recalls: We know more about the moon than our oc

This reminds me of a line from "Bill Nye the Science Guy" from when I was younger. Here's what my fuzzy memory recalls: We know more about the moon than our oceans. Getting to the moon is easy, all you need is a few billion dollars, a rocket pointed at space, and a space suit to keep you pressurized. In the ocean you have to deal with such unimaginable crushing pressures that push the limits of human engineering. Whats insane is that there is life there! There is so much left in the ocean to explore because humans have not been able to get there yet.

kijin 9y ago
The pressure difference between 1 atm and the moon is exactly 1 atm. It's less than the difference between the inside and outside of most car tires. The pressure difference between 1 atm and the bottom of the ocean is hundreds of atm, and the deepest spots can go over 1000 atm. Put this way, it's easy to see why the ocean is so much tougher. Luckily, the ocean is much closer than the moon, and the same gravity that is responsible for the tyranny of the rocket equation actually helps you get to the bottom. We've been to both places: the moon with Apollo landers, and the bottom of the Mariana Trench with bathyscaphes. I hope we'll keep returning to learn more about both. Of course, this will be much easier with robots that don't need to stay at 1 atm.
- noir_lord 9y ago
  Not sure the robots help that much (apart from not dying when things go wrong). As you said in some parts pressure is 1000atm, if we can pressurise the robots to 50atm that still leaves 950atm to deal with, I'm curious what happens to electronics at 100atm, 500atm and 1000atm. I'd imagine some components wouldn't handle that very well. Of course robots have other huge advantages, duration (no messy waste problems, no need for oxygen/carbon dioxide handling systems, no need for (as much) heating) I guess.
  - sp332 9y ago
    It's a lot cheaper to keep a robot than a human operating at that pressure.
  - IndrekR 9y ago
    It is much easier to keep electronics working down there when empty space is filled with liquid instead of pressurised gas (usually nitrogen). It is not the pressure, but pressure difference, that matters and liquids are not as compressible as gas is. Edit: just adding a note that I have worked with submarine electronics[1] for a while and can say we even do not know much about what is happening near the shore, not to even talk about the unexploredness of oceans. Quite a lot of HW/SW in use by scientists is far from modern. We need more initiatives like the Ocean Discovery XPRIZE[2] to bring attention to the field. [1] http://www.flydogmarine.com http://www.flydogmarine.com [2] https://oceandiscovery.xprize.org https://oceandiscovery.xprize.org
  - cr1895 9y ago
    >I'm curious what happens to electronics at 100atm, 500atm and 1000atm. On ROVs and the like, electronics modules are frequently immersed in mineral oil.
- Cacti 9y ago
  As you implied, getting to the bottom of the ocean is about as difficult as getting to the moon, and involves many of the same challenges.
- craftyguy 9y ago
  > It's less than the difference between the inside and outside of most car tires There are tires that are inflated with < 1 atm?
  - kijin 9y ago
    It's easy to build a solid container with < 1 atm inside. But I don't think such a container will fit the definition of a pneumatic tire. Any flexible container with < 1 atm inside will collapse until the pressure inside reaches equilibrium with the air outside. It will collapse further if there's a heavy load on top of it, or maybe less if it's a run-flat tire with rigid structures inside. Perhaps if you were on top of a very tall mountain or, even better, another planet, you could get away with filling your tires with less than < 1 atm and still have them functional.
    - Dylan16807 9y ago
      The prompt was talking about pressure between the inside and outside of the tire. If that's slightly under 1atm you have a perfectly normal but overly soft tire. People actually use pressures that low for rock crawling. (For reference a typical car tire is just over 2atm relative, 3atm absolute)
- amorphid 9y ago
  > The pressure difference between 1 atm and the moon is exactly 1 atm. It's less than the difference between the inside and outside of most car tires. I forget the moon has a hint of an atmosphere. [1] The pressure is 3×10^−15. I wonder when, if ever, you'd need to take that into account. [1] https://en.m.wikipedia.org/wiki/Atmosphere_of_the_Moon https://en.m.wikipedia.org/wiki/Atmosphere_of_the_Moon
maxxxxx 9y ago
The oceans are also a fr....ing big area to explore even if you send probes down
- zodPod 9y ago
  Did you just edit "freaking"?
  - maxxxxx 9y ago
    I meant "frigging" but I didn't want to trigger anyone.
    - bauerd 9y ago
      Pointless self-censorship is my trigger
    - jawilson2 9y ago
      Blasphemy! He's said it again! Yes! Yes, he did! He did!
  - knicholes 9y ago
    I was hoping it was an edit of "fracking."
    - maxxxxx 9y ago
      I was tempted to leave out the "r" though.
- deleted 9y ago
  [deleted]
- account435 9y ago
  damit bob
dsp1234 9y ago
Copied from a previous response to the same quote: There are approximately 3x10^28 molecules of water per cubic meter (assuming pure water, which is obviously not the case). A third of the way to the moon, there are approximately 7x10^6 molecules of hydrogen per cubic meter[0]. From high earth orbit (assume 60k km), it's about 300k km to the moon. The average depth of the ocean is about 3.5km. For simplification, let's assume that a molecule of water and a molecule of hydrogen have the same density (which they don't) From high earth orbit, in a straight line to the moon, there would be about 2x10^12 hydrogen molecules in the way. From the ocean surface to the average depth, there would be about 1x10^32 water molecules in the way. Not getting into the optical properties of water vs hydrogen, or the fact that the math is much different for a probe orbiting the moon, there's just more "stuff" between the ocean surface and the ocean floor, and a satellite and the moon. [0] - http://www.physicsoftheuniverse.com/facts.html http://www.physicsoftheuniverse.com/facts.html
- KGIII 9y ago
  LOL I recognize that. It was a reply to me. For reference: https://news.ycombinator.com/item?id=15338480 https://news.ycombinator.com/item?id=15338480
dyeje 9y ago
This reminds me of that Futurama joke where the spaceship is dragged underwater by a large fish on unbreakable tether: [Ships Cockpit. The room is glowing red and a klaxon beeps. Leela watches the depth gauge.] LEELA Depth at 45 hundred feet, 48 hundred, 50 hundred! 5000 feet! FARNSWORTH Dear Lord, that's over 150 atmospheres of pressure. FRY How many atmospheres can this ship withstand? FARNSWORTH Well it's a spaceship, so I'd say anywhere between zero and one.

kijin 9y ago

The pressure difference between 1 atm and the moon is exactly 1 atm. It's less than the difference between the inside and outside of most car tires. The pressure difference between 1 atm and the bottom of the ocean is hundreds of atm, and the deepest spots can go over 1000 atm. Put this way, it's easy to see why the ocean is so much tougher. Luckily, the ocean is much closer than the moon, and the same gravity that is responsible for the tyranny of the rocket equation actually helps you get to the bottom. We've been to both places: the moon with Apollo landers, and the bottom of the Mariana Trench with bathyscaphes. I hope we'll keep returning to learn more about both. Of course, this will be much easier with robots that don't need to stay at 1 atm.

noir_lord 9y ago
Not sure the robots help that much (apart from not dying when things go wrong). As you said in some parts pressure is 1000atm, if we can pressurise the robots to 50atm that still leaves 950atm to deal with, I'm curious what happens to electronics at 100atm, 500atm and 1000atm. I'd imagine some components wouldn't handle that very well. Of course robots have other huge advantages, duration (no messy waste problems, no need for oxygen/carbon dioxide handling systems, no need for (as much) heating) I guess.
- sp332 9y ago
  It's a lot cheaper to keep a robot than a human operating at that pressure.
- IndrekR 9y ago
  It is much easier to keep electronics working down there when empty space is filled with liquid instead of pressurised gas (usually nitrogen). It is not the pressure, but pressure difference, that matters and liquids are not as compressible as gas is. Edit: just adding a note that I have worked with submarine electronics[1] for a while and can say we even do not know much about what is happening near the shore, not to even talk about the unexploredness of oceans. Quite a lot of HW/SW in use by scientists is far from modern. We need more initiatives like the Ocean Discovery XPRIZE[2] to bring attention to the field. [1] http://www.flydogmarine.com http://www.flydogmarine.com [2] https://oceandiscovery.xprize.org https://oceandiscovery.xprize.org
- cr1895 9y ago
  >I'm curious what happens to electronics at 100atm, 500atm and 1000atm. On ROVs and the like, electronics modules are frequently immersed in mineral oil.
Cacti 9y ago
As you implied, getting to the bottom of the ocean is about as difficult as getting to the moon, and involves many of the same challenges.
craftyguy 9y ago
> It's less than the difference between the inside and outside of most car tires There are tires that are inflated with < 1 atm?
- kijin 9y ago
  It's easy to build a solid container with < 1 atm inside. But I don't think such a container will fit the definition of a pneumatic tire. Any flexible container with < 1 atm inside will collapse until the pressure inside reaches equilibrium with the air outside. It will collapse further if there's a heavy load on top of it, or maybe less if it's a run-flat tire with rigid structures inside. Perhaps if you were on top of a very tall mountain or, even better, another planet, you could get away with filling your tires with less than < 1 atm and still have them functional.
  - Dylan16807 9y ago
    The prompt was talking about pressure between the inside and outside of the tire. If that's slightly under 1atm you have a perfectly normal but overly soft tire. People actually use pressures that low for rock crawling. (For reference a typical car tire is just over 2atm relative, 3atm absolute)
amorphid 9y ago
> The pressure difference between 1 atm and the moon is exactly 1 atm. It's less than the difference between the inside and outside of most car tires. I forget the moon has a hint of an atmosphere. [1] The pressure is 3×10^−15. I wonder when, if ever, you'd need to take that into account. [1] https://en.m.wikipedia.org/wiki/Atmosphere_of_the_Moon https://en.m.wikipedia.org/wiki/Atmosphere_of_the_Moon

maxxxxx 9y ago

The oceans are also a fr....ing big area to explore even if you send probes down

zodPod 9y ago
Did you just edit "freaking"?
- maxxxxx 9y ago
  I meant "frigging" but I didn't want to trigger anyone.
  - bauerd 9y ago
    Pointless self-censorship is my trigger
  - jawilson2 9y ago
    Blasphemy! He's said it again! Yes! Yes, he did! He did!
- knicholes 9y ago
  I was hoping it was an edit of "fracking."
  - maxxxxx 9y ago
    I was tempted to leave out the "r" though.
deleted 9y ago
[deleted]
account435 9y ago
damit bob

dsp1234 9y ago

Copied from a previous response to the same quote: There are approximately 3x10^28 molecules of water per cubic meter (assuming pure water, which is obviously not the case). A third of the way to the moon, there are approximately 7x10^6 molecules of hydrogen per cubic meter[0]. From high earth orbit (assume 60k km), it's about 300k km to the moon. The average depth of the ocean is about 3.5km. For simplification, let's assume that a molecule of water and a molecule of hydrogen have the same density (which they don't) From high earth orbit, in a straight line to the moon, there would be about 2x10^12 hydrogen molecules in the way. From the ocean surface to the average depth, there would be about 1x10^32 water molecules in the way. Not getting into the optical properties of water vs hydrogen, or the fact that the math is much different for a probe orbiting the moon, there's just more "stuff" between the ocean surface and the ocean floor, and a satellite and the moon. [0] - http://www.physicsoftheuniverse.com/facts.html http://www.physicsoftheuniverse.com/facts.html

KGIII 9y ago
LOL I recognize that. It was a reply to me. For reference: https://news.ycombinator.com/item?id=15338480 https://news.ycombinator.com/item?id=15338480

dyeje 9y ago

This reminds me of that Futurama joke where the spaceship is dragged underwater by a large fish on unbreakable tether: [Ships Cockpit. The room is glowing red and a klaxon beeps. Leela watches the depth gauge.] LEELA Depth at 45 hundred feet, 48 hundred, 50 hundred! 5000 feet! FARNSWORTH Dear Lord, that's over 150 atmospheres of pressure. FRY How many atmospheres can this ship withstand? FARNSWORTH Well it's a spaceship, so I'd say anywhere between zero and one.