3 ms·

> If it super conducts, but it isn't useful in the real world, then we will be waiting for theory to - hopefully - give us some insight into how to improve thin

> If it super conducts, but it isn't useful in the real world, then we will be waiting for theory to - hopefully - give us some insight into how to improve things to useful. This only can carry a small amount of current. Thank you for this. > This is made out of lead. Even if it is useful for transmission, the difficulty of working safely with lead in a factory may mean it is impractical. Have you been to a hardware store lately? A huge amount of pipe fittings for gas and non-potable water are made from lead. Factories don’t find it hard to work with lead. It might be inadvisable but it’s not hard. We can argue about the "working safely" part, but in terms of "does this make it impractical?" the answer seems to be no under the current global regulatory environment.

beepbopboopp 3y ago
[flagged]
- mlyle 3y ago
  Nah. We have a reasonable understanding of fluids. It's just that the two things we say as simple explanations (the plane pushes air downwards causing an equal and opposite reaction to push the plane up; faster flow on top of the wing "sucks the plane upwards") are both only partial truths. Sometimes you get arguments between partisans for each of these two simplified explanations, but really both are bogus.
  - didgeoridoo 3y ago
    I’ve never understood how this battle could possibly persist, considering that planes can fly upside-down. The fact that Bernoulli’s Principle creates a low-pressure zone on the top of the aerofoil just gives you laminar flow at higher angles of attack. It really isn’t that mysterious, unless you insist that only a single physical law is allowed to come into play.
    - mlyle 3y ago
      > I’ve never understood how this battle could possibly persist, considering that planes can fly upside-down. That's orthogonal. Planes flying upside down still have air flowing faster over the new "top" of the wing than the bottom. Though, a common misunderstanding is that air must be taking the same "time" to go over the top and the bottom. This is not true. You can build a pretty good mental model of flight with either simplified mechanism, but you end up underestimating performance by a fair bit.
      - blagie 3y ago
        > You can build a pretty good mental model of flight with either simplified mechanism, but you end up underestimating performance by a fair bit. I've never hear of a good mental model built on Bernoulli's Principle. They are either: - Wrong - Give no intuition The key question is /why/ air moves faster on one side, and once you get away from the misconception of same time, I've never heard an intuitive argument. Redirecting air down: - makes complete sense - can be demonstrated by sticking your hand out the window of a car - works with flat airfoils (sails, kites, etc.), and explains those well too And the shape of the wing comes in from wanting the leading edge parallel to incoming airflow, and the other edge parallel to outgoing airflow. On a sail, I can adjust the shape. On a steel wing, I can't much, so I make a shape which works across different angles of attack. All of the other mechanisms, you can gradually work in from there to get accurate models. Toss in air moving to the low-pressure area, and having momentum, and you get why helicopters are less efficient than planes, as well as vortex shedding. It all builds up. As a corollary, Bernoulli tells you where air moves faster, but that follows from lift. Not the other way around. At least in any model which fits the human brain.
        ddalex 3y ago
        Why are you benchmarking models to human intuition? If you apply the same reasoning to quantum mechanics you'll have a bad time. I'm sure models can accurately compute how much of the wing lift comes from the suction effect on the top of the wing versus the push on the bottom of the wing.
  - cooper_ganglia 3y ago
    In the Vsauce video "Do Chairs Exist?" (I highly recommend it!), Michael talks about the concept of vagueness and how defining boundaries can lead to paradoxes. While it was primarily dealing with an ontological perspective, the linguistic perspective of a particular line has always stood out to me. Perhaps it makes a bit more sense in context of the full 40-minute video, but it is: >"Composites are causally redundant. Believing in chairs is like believing that, while yes, the burning gas from my stove completely describes why the water in a pot boils, there’s ALSO a magical invisible substance called boil-o that comes out of my stove that does the same thing as the flame at the same time, and if there was no boil-o, the flame would warm the water just the same, but there IS boil-o... Chairs are no more real than boil-o. Composites over-determine what happens in the world." Like your example with lift and fluid dynamics, simple explanations like "plane pushes air downwards" or "faster flow sucks the plane upwards" might be insufficient, but they're at least useful to the layman. It also reminds me of how Richard Feynman answered the question, "What is the feeling between 2 attracted magnets?" by explaining that it would be impossible to give a complete answer. Feynman pointed out that when you ask why two magnets attract each other, there are different levels of understanding depending on your background knowledge. For someone with no knowledge of physics, the simple explanation would be the existence of a magnetic force causing the attraction. However, delving deeper into the question raises complexities that can be challenging to explain. Feynman highlighted the difficulty of answering "why" questions in general. Explaining magnetic attraction in terms of something else that we are more familiar with, like rubber bands, would be misleading and circular, as it ultimately comes down to electrical and magnetic forces. He acknowledged that some aspects of the natural world may need to be accepted as fundamental elements without a more profound explanation. This is echoed in the Vsauce video, where defining boundaries and attempting to explain everything can lead to paradoxes and vagueness. The concept of "boil-o" illustrates how composites, like chairs, can over-determine what happens in the world and our own perception, making their actual explanation even more elusive.
- cornel_io 3y ago
  We 100% know why airplanes of every shape and size stay aloft, and can calculate lift/drag extremely accurately based on the geometry of the plane and the airflow, in both steady state and much worse conditions. We have great approximations for steady state that make perfect sense and simplify the situation greatly and make it more understandable without simulation, even if they gloss over some details. Where are you getting this terrible information that we don't know how flight works? Have you ever talked to literally anyone who has worked in aeronautical engineering, or even studied the basics of fluid dynamics?
  - VagabundoP 3y ago
    Yeah, but what about Bumblebees. Yeah, didn't think so. ;)
    - MattPalmer1086 3y ago
      They figured that one out too... Something to do with vortices...
      - VagabundoP 3y ago
        Yeah I was being sarcastic. Forgot the /s. :(

beepbopboopp 3y ago

[flagged]

mlyle 3y ago
Nah. We have a reasonable understanding of fluids. It's just that the two things we say as simple explanations (the plane pushes air downwards causing an equal and opposite reaction to push the plane up; faster flow on top of the wing "sucks the plane upwards") are both only partial truths. Sometimes you get arguments between partisans for each of these two simplified explanations, but really both are bogus.
- didgeoridoo 3y ago
  I’ve never understood how this battle could possibly persist, considering that planes can fly upside-down. The fact that Bernoulli’s Principle creates a low-pressure zone on the top of the aerofoil just gives you laminar flow at higher angles of attack. It really isn’t that mysterious, unless you insist that only a single physical law is allowed to come into play.
  - mlyle 3y ago
    > I’ve never understood how this battle could possibly persist, considering that planes can fly upside-down. That's orthogonal. Planes flying upside down still have air flowing faster over the new "top" of the wing than the bottom. Though, a common misunderstanding is that air must be taking the same "time" to go over the top and the bottom. This is not true. You can build a pretty good mental model of flight with either simplified mechanism, but you end up underestimating performance by a fair bit.
    - blagie 3y ago
      > You can build a pretty good mental model of flight with either simplified mechanism, but you end up underestimating performance by a fair bit. I've never hear of a good mental model built on Bernoulli's Principle. They are either: - Wrong - Give no intuition The key question is /why/ air moves faster on one side, and once you get away from the misconception of same time, I've never heard an intuitive argument. Redirecting air down: - makes complete sense - can be demonstrated by sticking your hand out the window of a car - works with flat airfoils (sails, kites, etc.), and explains those well too And the shape of the wing comes in from wanting the leading edge parallel to incoming airflow, and the other edge parallel to outgoing airflow. On a sail, I can adjust the shape. On a steel wing, I can't much, so I make a shape which works across different angles of attack. All of the other mechanisms, you can gradually work in from there to get accurate models. Toss in air moving to the low-pressure area, and having momentum, and you get why helicopters are less efficient than planes, as well as vortex shedding. It all builds up. As a corollary, Bernoulli tells you where air moves faster, but that follows from lift. Not the other way around. At least in any model which fits the human brain.
      - ddalex 3y ago
        Why are you benchmarking models to human intuition? If you apply the same reasoning to quantum mechanics you'll have a bad time. I'm sure models can accurately compute how much of the wing lift comes from the suction effect on the top of the wing versus the push on the bottom of the wing.
- cooper_ganglia 3y ago
  In the Vsauce video "Do Chairs Exist?" (I highly recommend it!), Michael talks about the concept of vagueness and how defining boundaries can lead to paradoxes. While it was primarily dealing with an ontological perspective, the linguistic perspective of a particular line has always stood out to me. Perhaps it makes a bit more sense in context of the full 40-minute video, but it is: >"Composites are causally redundant. Believing in chairs is like believing that, while yes, the burning gas from my stove completely describes why the water in a pot boils, there’s ALSO a magical invisible substance called boil-o that comes out of my stove that does the same thing as the flame at the same time, and if there was no boil-o, the flame would warm the water just the same, but there IS boil-o... Chairs are no more real than boil-o. Composites over-determine what happens in the world." Like your example with lift and fluid dynamics, simple explanations like "plane pushes air downwards" or "faster flow sucks the plane upwards" might be insufficient, but they're at least useful to the layman. It also reminds me of how Richard Feynman answered the question, "What is the feeling between 2 attracted magnets?" by explaining that it would be impossible to give a complete answer. Feynman pointed out that when you ask why two magnets attract each other, there are different levels of understanding depending on your background knowledge. For someone with no knowledge of physics, the simple explanation would be the existence of a magnetic force causing the attraction. However, delving deeper into the question raises complexities that can be challenging to explain. Feynman highlighted the difficulty of answering "why" questions in general. Explaining magnetic attraction in terms of something else that we are more familiar with, like rubber bands, would be misleading and circular, as it ultimately comes down to electrical and magnetic forces. He acknowledged that some aspects of the natural world may need to be accepted as fundamental elements without a more profound explanation. This is echoed in the Vsauce video, where defining boundaries and attempting to explain everything can lead to paradoxes and vagueness. The concept of "boil-o" illustrates how composites, like chairs, can over-determine what happens in the world and our own perception, making their actual explanation even more elusive.
cornel_io 3y ago
We 100% know why airplanes of every shape and size stay aloft, and can calculate lift/drag extremely accurately based on the geometry of the plane and the airflow, in both steady state and much worse conditions. We have great approximations for steady state that make perfect sense and simplify the situation greatly and make it more understandable without simulation, even if they gloss over some details. Where are you getting this terrible information that we don't know how flight works? Have you ever talked to literally anyone who has worked in aeronautical engineering, or even studied the basics of fluid dynamics?
- VagabundoP 3y ago
  Yeah, but what about Bumblebees. Yeah, didn't think so. ;)
  - MattPalmer1086 3y ago
    They figured that one out too... Something to do with vortices...
    - VagabundoP 3y ago
      Yeah I was being sarcastic. Forgot the /s. :(