2 ms·

Well, I'd argue that sentence one is incorrect. Things that fade out quickly are less diffuse, though more fully diffused when measured at the same distance. G

by quesera 11y ago

Well, I'd argue that sentence one is incorrect. Things that fade out quickly are less diffuse, though more fully diffused when measured at the same distance. Gravitational force is both much weaker and (for that of large bodies) diffused over a much greater area than electromagnetic force (of very small bodies). These are the circumstances of the example comparison. "More diffuse" vs. "more greatly diffused" appears to be our disconnect here. Something which is "more diffuse" is expected to be less measurable at a single point, all other variables controlled. This is true of gravity but not for the reasons implied. Nevertheless, if the total gravitational force of the relevant object from the example (earth) was concentrated into the same area as the total EM force of the magnet, we would have a black hole in our kitchen. Fortunately, that gravitational force is diffused over much a larger area. Things which are more diffuse are necessarily diffused over a larger area. Not all things which are diffused over a larger area are necessarily more diffuse. I see the hangup, and I appreciate your objection. Edit: and thank you for the EM force inverse power law correction. I was using distant memories of the math for EM radiation, which is obviously different. But if those numbers are right, it supports the argument that gravitational force is less concentrated...and therefore more diffuse, does it not?

ars 11y ago
> Gravitational force is both much weaker and (for that of large bodies) diffused over a much greater area than electromagnetic force (of very small bodies). No, that is simply not true. Not at all. You keep saying this, and it keeps being not true. I don't really know how else to say it to you. You have a mistake in your intuition. > Nevertheless, if the total gravitational force of the relevant object from the example (earth) was concentrated into the same area as the total EM force of the magnet, we would have a black hole in our kitchen. No! That is not true. If you turned the earth into a black hole, and placed that black hole in the center of where the earth used to be, you would notice NOTHING whatsoever in your kitchen. NOTHING. You could not tell the difference. > Things which are more diffuse are necessarily diffused over a larger area. And gravity is NOT diffused over a larger area than electric charge. If you had enough electric charge to pull on you (assuming you were of opposite charge, at the same ratio as your mass vs earth mass) placed in the center of the earth it would act IDENTICALLY to gravity. And that charge would be very small, much much smaller than gravity, because gravity is WEAKER than the electric force. NOT because it is more diffuse. > Edit: and thank you for the EM force inverse power law correction. I was using distant memories of the math for EM radiation, which is obviously different. Not EM force. Magnets with two poles. EM force is the regular inverse square. > But if those numbers are right, it supports the argument that gravitational force is less concentrated...and therefore more diffuse, does it not? No it does not. It just means you have two opposite magnets that cancel each other out at a distance. If it were electric charge, which is a monopole, it would not happen.
- quesera 11y ago
  I'm really struggling to understand how you're not following my meaning here. I will take just one point, because it's probably adequate to cover the entire disconnect. I wrote: > Gravitational force is both much weaker and (for that of large bodies) diffused over a much greater area than electromagnetic force (of very small bodies). I mean: - *the* gravitational force is much weaker than *the* electromagnetic force - large bodies (earth sized) have more *gross* gravitational force than refrigerator magnets have *gross* EM force. - the gravitational force of an earth sized body extends, in the realm of practicality, much farther than the EM force of a refrigerator magnet. In fact both extend into infinity, but that's only interesting in the theoretical sense. Are any of those statements incorrect? If so, you're right and my intuition and everything else is wrong. If not, then I think we're talking past each other, and I apologize for the confusion.
  - ars 11y ago
    > Are any of those statements incorrect? Yes, the third one is incorrect. > If so, you're right and my intuition and everything else is wrong. The reason you think this way is because magnets fall off by the power of 5 (approximately, it's not a specific number, but depends on the geometry of the magnet), because of the two poles. If on the other hand you played around with charged objects (which are monopoles like gravity) your intuition would work better for this. But unlike magnets highly charged objects are not commonly found around the house. ---------- Also the second one is debatable - the acceleration of one magnet to another is higher that the acceleration of an object falling on earth. Even a lightly charged object can accelerate another object at greater than what the earth can manage. The reason I use acceleration to measure gross force is because gravity (and charge) depend on the product of the two objects and distance - the only single number you can assign a single object is acceleration and even that depends on distance.
    - quesera 11y ago
      I still think I am not explaining myself clearly enough. When I say gross force, I mean the sum total of all relevant force exerted by the object. So the gross gravitational force of the earth is strong enough to hold the moon in orbit, but clearly the magnet has no such ...strength. Now obviously (I shouldn't use that word!) in the case of massive bodies like earths and moons, there's a more complex interaction going on than a one-sided force. But there's a total magnitude of force that just doesn't exist in the magnet. A lit match burns paper more readily than the sun, but clearly the sun distributes a larger amount of gross energy over a wider area than does a match. > Even a lightly charged object can accelerate another object at greater than what the earth can manage Ack. Considering acceleration without mass is no way to properly reason about force! Surely I remember that much, at least. Regardless, I will desist and defer. Though I do wish I felt that I now understood something more clearly than I did before. :(

by quesera 11y ago

ars 11y ago

> Gravitational force is both much weaker and (for that of large bodies) diffused over a much greater area than electromagnetic force (of very small bodies). No, that is simply not true. Not at all. You keep saying this, and it keeps being not true. I don't really know how else to say it to you. You have a mistake in your intuition. > Nevertheless, if the total gravitational force of the relevant object from the example (earth) was concentrated into the same area as the total EM force of the magnet, we would have a black hole in our kitchen. No! That is not true. If you turned the earth into a black hole, and placed that black hole in the center of where the earth used to be, you would notice NOTHING whatsoever in your kitchen. NOTHING. You could not tell the difference. > Things which are more diffuse are necessarily diffused over a larger area. And gravity is NOT diffused over a larger area than electric charge. If you had enough electric charge to pull on you (assuming you were of opposite charge, at the same ratio as your mass vs earth mass) placed in the center of the earth it would act IDENTICALLY to gravity. And that charge would be very small, much much smaller than gravity, because gravity is WEAKER than the electric force. NOT because it is more diffuse. > Edit: and thank you for the EM force inverse power law correction. I was using distant memories of the math for EM radiation, which is obviously different. Not EM force. Magnets with two poles. EM force is the regular inverse square. > But if those numbers are right, it supports the argument that gravitational force is less concentrated...and therefore more diffuse, does it not? No it does not. It just means you have two opposite magnets that cancel each other out at a distance. If it were electric charge, which is a monopole, it would not happen.

quesera 11y ago
I'm really struggling to understand how you're not following my meaning here. I will take just one point, because it's probably adequate to cover the entire disconnect. I wrote: > Gravitational force is both much weaker and (for that of large bodies) diffused over a much greater area than electromagnetic force (of very small bodies). I mean: - *the* gravitational force is much weaker than *the* electromagnetic force - large bodies (earth sized) have more *gross* gravitational force than refrigerator magnets have *gross* EM force. - the gravitational force of an earth sized body extends, in the realm of practicality, much farther than the EM force of a refrigerator magnet. In fact both extend into infinity, but that's only interesting in the theoretical sense. Are any of those statements incorrect? If so, you're right and my intuition and everything else is wrong. If not, then I think we're talking past each other, and I apologize for the confusion.
- ars 11y ago
  > Are any of those statements incorrect? Yes, the third one is incorrect. > If so, you're right and my intuition and everything else is wrong. The reason you think this way is because magnets fall off by the power of 5 (approximately, it's not a specific number, but depends on the geometry of the magnet), because of the two poles. If on the other hand you played around with charged objects (which are monopoles like gravity) your intuition would work better for this. But unlike magnets highly charged objects are not commonly found around the house. ---------- Also the second one is debatable - the acceleration of one magnet to another is higher that the acceleration of an object falling on earth. Even a lightly charged object can accelerate another object at greater than what the earth can manage. The reason I use acceleration to measure gross force is because gravity (and charge) depend on the product of the two objects and distance - the only single number you can assign a single object is acceleration and even that depends on distance.
  - quesera 11y ago
    I still think I am not explaining myself clearly enough. When I say gross force, I mean the sum total of all relevant force exerted by the object. So the gross gravitational force of the earth is strong enough to hold the moon in orbit, but clearly the magnet has no such ...strength. Now obviously (I shouldn't use that word!) in the case of massive bodies like earths and moons, there's a more complex interaction going on than a one-sided force. But there's a total magnitude of force that just doesn't exist in the magnet. A lit match burns paper more readily than the sun, but clearly the sun distributes a larger amount of gross energy over a wider area than does a match. > Even a lightly charged object can accelerate another object at greater than what the earth can manage Ack. Considering acceleration without mass is no way to properly reason about force! Surely I remember that much, at least. Regardless, I will desist and defer. Though I do wish I felt that I now understood something more clearly than I did before. :(