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An Indian site, YourStory, has an unusually broad ranging interview with Richard Stallman. While much of the background and goals will already be familiar to SN readers, the interview is interesting not only for its scope but also that India is starting to take an interest in these matters.
To know Richard Stallman is to know the true meaning of freedom. He's the man behind the GNU project and the free software movement, and the subject of our Techie Tuesdays this week.
This is not a usual story. After multiple attempts to get in touch for an interaction with Richard Stallman, I got a response which prepared me well for what's coming next. I'm sharing the same with you to prepare you for what's coming next.
I'm willing to do the interview — if you can put yourself into philosophical and political mindset that is totally different from the one that the other articles are rooted in.
The general mindset of your articles is to admire success. Both business success, and engineering success. My values disagree fundamentally with that. In my view, proprietary software is an injustice; it is wrongdoing. People should be _ashamed_ of making proprietary software, _especially_ if it is successful. (If nobody uses the proprietary program, at least it has not really wronged anyone.) Thus, most of the projects you consider good, I consider bad.
(Score: 2) by HiThere on Monday September 04 2017, @04:54PM (2 children)
Sorry, it's been a long time since physics. Now that you say so I remember that EM and gravity fall off as the square, so you are right, magnetism falls off as the cube. But that's only far enough away that you get the two poles acting about equally. When you get closer the computation becomes quite difficult as you're combining two "falls off as the square" effects which conflict with each other. As you approach one of the poles it becomes sufficiently dominant, that the other fades into insignificance. I think that was where that "4th power" effect came from.
What's really going on is difficult to model, which is why they always trot out that "lines of force" model, but what's really happening is more line induced magnetism reacting against two poles which each fall off as the square in strength, but which conflict. And the resultant effect depends on whether the particle is charged, ferro-magnetic, or para-magnetic. Or just unresponsive. And then there's the field created by a charge running along a wire, which produces a linear effect, but the line isn't usually straight. I never even tried to calculate from first principles how an electro-magnet field was generated. It was hard enough for a straight wire. (This was multiple decades ago, and that wasn't my main interest in physics. And I dropped out about the time they started using tensors.)
Anyway, that third power response is the effect you get at a distance from the magnet. When you get closer the effects become stronger and not evenly spread.
In a way it's sort of like "jerk". Nobody ever calculated the higher derivatives, they always stop with acceleration, but acceleration has to start, and that's a higher derivative. And that has to start, which is a higher derivative. The "jerk" at the start of acceleration actually theoretically has an infinite number of derivatives, each of which acts for a shorter period of time. But rate of change of acceleration is always something that happens for a very short period of time, for lots of very good reasons. So people tend to ignore it. But if it weren't for jerk, glass wouldn't break when you dropped it.
Now this seems to mean that a strong magnetic shield would need to have LOTS of magnetic poles, which may be impossible. OTOH, if it has lots of magnetic poles, the effect at a distance would be minor. So you may be right that it can't be done...but the situation is complex enough that I'm going to keep hoping it's doable. (How would one calculate the effects of a rotating magnetic field? Usually the speed of rotation is slow enough that this can be ignored, but one rotated electronically might be able to do it fast enough that...?? Or what about a pulsing one? That last, though, doesn't sound like a low energy solution.)
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 2) by HiThere on Monday September 04 2017, @04:56PM
Sorry, that was largely thinking out loud. I'm not really sure of ANY of that. As I said, it's been a long time since physics.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 2) by Immerman on Monday September 04 2017, @08:21PM
No worries, I think out loud here a fair bit myself.
I think you're wrong about "jerk" though - firstly it's quite common to consider the rate of change of acceleration, mostly as a comfort thing. Elevators are a common example - some accelerate gradually, while others transition quite rapidly, giving a "stomach in your throat/feet" feeling. Where glass is concerned the problem is its rigidity, which means any impact with another rigid object will cause a spike of acceleration as the contacting point comes to a stop nearly instantly. Often considered as as an "impulse" a spike of infinite force for zero duration, that imparts a definite finite change in momentum. Hard drives have a similar weakness - that "20Gs of impact resistance" can easily be overcome by, say, tapping a screwdriver against its casing. Rigid body collisions invariable involve rather ridiculous momentary accelerations.