4 ms·

https://www.nasa.gov/mission_pages/station/research/cciss_feature.html https://www.nasa.gov/mission_pages/station/research/cciss_fe... https://en.wikipedia.org

https://www.nasa.gov/mission_pages/station/research/cciss_feature.html https://www.nasa.gov/mission_pages/station/research/cciss_fe... https://en.wikipedia.org/wiki/Hemodynamics https://en.wikipedia.org/wiki/Hemodynamics etc. Yes, gravity is, by far, the weakest force. None-the-less, it is a force, and definitely effects all sorts of things at all scales.

petschge 7y ago
While technically present at all scales, gravity is so weak that you can ignore it until you get to pretty large scales. Meters or so. An ant barely feels gravity, a bacterium or a single cell don't even know it is there.
- pharrington 7y ago
  If you wanna go down that rabbit hole... one must be as precise as possible when estimating.
- soulofmischief 7y ago
  What does it mean to "feel" gravity? I assure you the ant's biological systems would undergo many changes over generations in the absence of gravity in order to reach homeostasis. A bacterium can't feel anything but did I mention single-celled organisms? No, I mentioned organelles. You are arguing against a straw-man. Furthermore you are completely ignoring the effect of gravitational perturbations on emergent structures. These things don't necessarily "iron out", and if they do, we have not yet ascertained at what level and via what mechanism. You are confusing an object's ability to produce gravity with its propensity for interacting with gravity.
  - ceejayoz 7y ago
    > A bacterium can't feel anything but did I mention single-celled organisms? No, I mentioned organelles. Given that mitochondria are almost certainly descended from captured bacteria, that's an odd quibble.
    - soulofmischief 7y ago
      You're right; I'm just trying to not stray so far from the intending meaning of my post. However, our organelles are indirectly influenced by gravity as a result of cascading interactions with other macro systems. I'm just sure someone could make the argument that one bacteria out there was shown to function identically without gravity, thus dismantling an argument I was never trying to make. Organelles are different because they interact with a larger cell structure, which interacts with a larger tissue structure, the latter two both having experimentally proven dependencies on gravity for optimal performance in their current structure. Yes, a lot of our cells would work more or less the same in zero grav-- but would they have ever formed that way in the first place? Your guess is as good as mine.
eesmith 7y ago
These two links still have no bearing on the topic. You wrote "Gravity is important for heavy elements to cluster in one place in sufficient concentrations to form organelles." Your link #1 concerns blood flow, which is much larger than organelles and has nothing to do with heavy elements. (In any relevant sense - while red blood cells have iron, they don't affect the fluid dynamics.) Your link #2 barely touches on gravity, and doesn't mention organelles or heavy elements. I agree with krastanov - the statement of yours, which I quoted, is preposterous according to a widely held understanding of how things work. As such, it would require strong evidence to overturn those views. What is the basis by which you decided it was correct and important enough to bring up?
- soulofmischief 7y ago
  While OP's words are his own and I'm not necessarily in agreement with them, it's worth pointing out that the circulatory system and organs and organelles which comprise them all have circular dependencies; it's not simply hierarchical based on relative size. A change in any part of the system can propagate both upward and downward.
  - eesmith 7y ago
    The "OP" I'm quoting is you, at https://news.ycombinator.com/item?id=20321707 https://news.ycombinator.com/item?id=20321707 . How are you not in agreement with what you wrote? As to your 'circular dependencies', I'll again quote krastanov in the direct ancestor to this thread: > Unless you mean "gravity is important to make planets, and planets are where we have observed life", in which case you are stretching the meaning of this expression to a meaningless level. This 'circular dependencies' argument is as meaningless as saying that biological organelles are essential to the production of nuclear weapons - true, but not important enough that it's needed to understand the overall process. And there are many things like that. We can model weather numerically without modeling each and every molecule because that low-level interaction doesn't really affect fluid dynamics. Mean field theory can be apply to many complex systems. Yes, there can be chaotic behavior, even in Newtownian systems. But that's beside the point, which is they you have made statements which you seem to assert as fact which don't have any evidentiary support. You might as well muse about the effects of feline ESP on the weather.

petschge 7y ago

While technically present at all scales, gravity is so weak that you can ignore it until you get to pretty large scales. Meters or so. An ant barely feels gravity, a bacterium or a single cell don't even know it is there.

pharrington 7y ago
If you wanna go down that rabbit hole... one must be as precise as possible when estimating.
soulofmischief 7y ago
What does it mean to "feel" gravity? I assure you the ant's biological systems would undergo many changes over generations in the absence of gravity in order to reach homeostasis. A bacterium can't feel anything but did I mention single-celled organisms? No, I mentioned organelles. You are arguing against a straw-man. Furthermore you are completely ignoring the effect of gravitational perturbations on emergent structures. These things don't necessarily "iron out", and if they do, we have not yet ascertained at what level and via what mechanism. You are confusing an object's ability to produce gravity with its propensity for interacting with gravity.
- ceejayoz 7y ago
  > A bacterium can't feel anything but did I mention single-celled organisms? No, I mentioned organelles. Given that mitochondria are almost certainly descended from captured bacteria, that's an odd quibble.
  - soulofmischief 7y ago
    You're right; I'm just trying to not stray so far from the intending meaning of my post. However, our organelles are indirectly influenced by gravity as a result of cascading interactions with other macro systems. I'm just sure someone could make the argument that one bacteria out there was shown to function identically without gravity, thus dismantling an argument I was never trying to make. Organelles are different because they interact with a larger cell structure, which interacts with a larger tissue structure, the latter two both having experimentally proven dependencies on gravity for optimal performance in their current structure. Yes, a lot of our cells would work more or less the same in zero grav-- but would they have ever formed that way in the first place? Your guess is as good as mine.

eesmith 7y ago

These two links still have no bearing on the topic. You wrote "Gravity is important for heavy elements to cluster in one place in sufficient concentrations to form organelles." Your link #1 concerns blood flow, which is much larger than organelles and has nothing to do with heavy elements. (In any relevant sense - while red blood cells have iron, they don't affect the fluid dynamics.) Your link #2 barely touches on gravity, and doesn't mention organelles or heavy elements. I agree with krastanov - the statement of yours, which I quoted, is preposterous according to a widely held understanding of how things work. As such, it would require strong evidence to overturn those views. What is the basis by which you decided it was correct and important enough to bring up?

soulofmischief 7y ago
While OP's words are his own and I'm not necessarily in agreement with them, it's worth pointing out that the circulatory system and organs and organelles which comprise them all have circular dependencies; it's not simply hierarchical based on relative size. A change in any part of the system can propagate both upward and downward.
- eesmith 7y ago
  The "OP" I'm quoting is you, at https://news.ycombinator.com/item?id=20321707 https://news.ycombinator.com/item?id=20321707 . How are you not in agreement with what you wrote? As to your 'circular dependencies', I'll again quote krastanov in the direct ancestor to this thread: > Unless you mean "gravity is important to make planets, and planets are where we have observed life", in which case you are stretching the meaning of this expression to a meaningless level. This 'circular dependencies' argument is as meaningless as saying that biological organelles are essential to the production of nuclear weapons - true, but not important enough that it's needed to understand the overall process. And there are many things like that. We can model weather numerically without modeling each and every molecule because that low-level interaction doesn't really affect fluid dynamics. Mean field theory can be apply to many complex systems. Yes, there can be chaotic behavior, even in Newtownian systems. But that's beside the point, which is they you have made statements which you seem to assert as fact which don't have any evidentiary support. You might as well muse about the effects of feline ESP on the weather.