3 ms·

I wonder if I'll be attacked for saying this. Here goes. We always find these kinds of shapes because they are the shapes that appear through fluid mechanics. S

I wonder if I'll be attacked for saying this. Here goes. We always find these kinds of shapes because they are the shapes that appear through fluid mechanics. Space is a fluid, too. In a fluid, we have vortices (in the form of whirlpools, tornados, etc) because they allow material and energy to be moved much more efficiently than any of the other structures we don't tend to see in stable systems.

NeverEnough 12y ago
would you disagree with the idea that there are a lot of good ways of describing something, that are true for many cases but very wrong for others?
- blueprint 12y ago
  I don't know what you have in mind. In order for me, or anyone else who bases his/her judgement on fact, to give you an answer which you'll be able to recognize as right, you'll need to point out a concrete problem or question that contains facts that can be independently verified, rather than something abstract and hypothetical.
chriswarbo 12y ago
> In a fluid, we have vortices... because they allow material and energy to be moved much more efficiently than any of the other structures we don't tend to see in stable systems. As a Physicist, I am wary of making such statements since they put the cart before the horse ( http://en.wikipedia.org/wiki/Teleology http://en.wikipedia.org/wiki/Teleology ). I'd be more comfortable saying "In a fluid, we have vortices... as a consequence of the movement of material and energy." In your case I'm assuming it's just a turn of phrase, but there are some hypotheses which actually attribute abstract "goals" to nature, without providing any explanation in terms of mechanical processes; for example http://www.lawofmaximumentropyproduction.com http://www.lawofmaximumentropyproduction.com In constrast, Darwin explained the theory of evolution using the mechanical process of natural selection. The principle of least action can be explained either physically, using quantum interference (eg. in optics), or mathematically, due to the mixture of inductive steps with deductive ones. In constrast, the existence of vortices in fluids because of their efficiency would be like claiming crater lakes can't exist because water flows downhill.
- blueprint 12y ago
  Electrostatic forces keep the surface of a liquid as taut as they can. Undisturbed, and notwithstanding internal vibrations, a spherical droplet of liquid will tend to stay in a sphere because not to do so would require an additional expenditure of energy, that is, in order to counteract those electrostatic forces. So the way I used the term efficient before is in the same way as how it's less costly in energy expenditure, i.e. more efficient, for a droplet to stay spherical. It's the same reasoning behind a number of other things we find in physics. So I'm not convinced that my statement about efficiency leading to appearance of natural structures is incorrect -- maybe more so a difference in how such an observation is commonly phrased.
  - chriswarbo 12y ago
    I was only commenting on the goal-attributing phrasing you'd used, not the Physics. Compare your electrostatic sphere example to my crater-lake example: lakes at a high gravitational potential are inefficient, it's less costly for the water to flow up the sides of a crater and down into the ocean. The reason that doesn't happen is because there is no mechanism for it to do so. If we look at liquid helium, there is a mechanism which allows it (the Onnes Effect) so it does happen. > Electrostatic forces keep the surface of a liquid as taut as they can Yes, but the interesting part of the sentence is "as they can"; we can't just assume that a liquid's surface will be at minimal energy, since that would allow us to solve NP-complete problems with soap bubbles ( www.scottaaronson.com/papers/npcomplete.pdf ) :)

NeverEnough 12y ago

would you disagree with the idea that there are a lot of good ways of describing something, that are true for many cases but very wrong for others?

blueprint 12y ago
I don't know what you have in mind. In order for me, or anyone else who bases his/her judgement on fact, to give you an answer which you'll be able to recognize as right, you'll need to point out a concrete problem or question that contains facts that can be independently verified, rather than something abstract and hypothetical.

chriswarbo 12y ago

> In a fluid, we have vortices... because they allow material and energy to be moved much more efficiently than any of the other structures we don't tend to see in stable systems. As a Physicist, I am wary of making such statements since they put the cart before the horse ( http://en.wikipedia.org/wiki/Teleology http://en.wikipedia.org/wiki/Teleology ). I'd be more comfortable saying "In a fluid, we have vortices... as a consequence of the movement of material and energy." In your case I'm assuming it's just a turn of phrase, but there are some hypotheses which actually attribute abstract "goals" to nature, without providing any explanation in terms of mechanical processes; for example http://www.lawofmaximumentropyproduction.com http://www.lawofmaximumentropyproduction.com In constrast, Darwin explained the theory of evolution using the mechanical process of natural selection. The principle of least action can be explained either physically, using quantum interference (eg. in optics), or mathematically, due to the mixture of inductive steps with deductive ones. In constrast, the existence of vortices in fluids because of their efficiency would be like claiming crater lakes can't exist because water flows downhill.

blueprint 12y ago
Electrostatic forces keep the surface of a liquid as taut as they can. Undisturbed, and notwithstanding internal vibrations, a spherical droplet of liquid will tend to stay in a sphere because not to do so would require an additional expenditure of energy, that is, in order to counteract those electrostatic forces. So the way I used the term efficient before is in the same way as how it's less costly in energy expenditure, i.e. more efficient, for a droplet to stay spherical. It's the same reasoning behind a number of other things we find in physics. So I'm not convinced that my statement about efficiency leading to appearance of natural structures is incorrect -- maybe more so a difference in how such an observation is commonly phrased.
- chriswarbo 12y ago
  I was only commenting on the goal-attributing phrasing you'd used, not the Physics. Compare your electrostatic sphere example to my crater-lake example: lakes at a high gravitational potential are inefficient, it's less costly for the water to flow up the sides of a crater and down into the ocean. The reason that doesn't happen is because there is no mechanism for it to do so. If we look at liquid helium, there is a mechanism which allows it (the Onnes Effect) so it does happen. > Electrostatic forces keep the surface of a liquid as taut as they can Yes, but the interesting part of the sentence is "as they can"; we can't just assume that a liquid's surface will be at minimal energy, since that would allow us to solve NP-complete problems with soap bubbles ( www.scottaaronson.com/papers/npcomplete.pdf ) :)