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Conceptually and per unit measurement the force of gravity is many orders of magnitude weaker than the force of electromagnetism. No argument there. But that's

by quesera 11y ago

Conceptually and per unit measurement the force of gravity is many orders of magnitude weaker than the force of electromagnetism. No argument there. But that's just not the way the force of gravity is thought about by humans, because the gravitational effect is so small as to be undetectable between human-scaled bodies. So we attribute gravity to more massive things, and consider it only en masse, never divisibly. To the extent that the gravitational force of the earth has measurable effects on more things than the electromagnetic force of the refrigerator magnet, it is more...spread out. More distributed. More diffused. It follows the same inverse square law as everything else, but it does a lot more of it, over human-scaled distances. And this is how high school physics teachers can be counterintuitively correct, but I think the takeaway is more about how hopeless humans are at conceptualizing very large numbers than about physics.

ars 11y ago
So if people are bad at it, then why make it worse by using an incorrect word? Also the magnetic force in a physical object does not follow inverse square, it's more like inverse of the 5th root (because there are no magnetic monopoles the two fields cancel out very quickly at distance). So if anything the magnetic force is more diffuse than gravity since it fades out so quickly. So if anything the magnetic force is less diffuse than gravity since it's concentrated right near the object. The fact that both of those sentences are correct tells you quite definitively that diffuse is very very much an incorrect word.
- 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.

by quesera 11y ago

ars 11y ago

So if people are bad at it, then why make it worse by using an incorrect word? Also the magnetic force in a physical object does not follow inverse square, it's more like inverse of the 5th root (because there are no magnetic monopoles the two fields cancel out very quickly at distance). So if anything the magnetic force is more diffuse than gravity since it fades out so quickly. So if anything the magnetic force is less diffuse than gravity since it's concentrated right near the object. The fact that both of those sentences are correct tells you quite definitively that diffuse is very very much an incorrect word.

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.