KipIngram

Way back in the 1980s or so I heard a US Senator being interviewed on TV. There had just been a terror attack of some sort in Europe (this was still back in the day when "such things just didn't happen here"). I forget exactly how this remark got motivated, but I remember him saying that it would always be harder to prevent such attacks in a society that emphasized personal freedom than it would in one that put freedom in the back seat. In other words freedom came with risk, because freedom means freedom for everyone, including people that might use that freedom to plan and attempt bad actions. I remember that really resonated with me, and I had no doubt about what I thought of the "freedom vs. safety" tradeoff - I'll land on the side of freedom every time. One problem with modern actions on this front is that often the actions really don't have as much effect on terrorists as they purport to, but still wind up limiting everyone's freedom.

As far as I'm aware electrons are subject only to the Coulomb force and gravity. Given that they are both inverse square forces and the Coulomb force is much stronger regardless of radii, electrons would always repel each other. (I'm guessing that was your question - the title sort of chopped it off)

Yeah, how easy it is to define "extremism" as only including extremists you particularly disagree with. All to often people think either 1) there are no extremists on my side, only on the other side, or (in my opinion even worse) 2) it's ok for us to be extremists because we're right.

But I don't think the point here is to get a picture of gravity as a phenomenon - the point is to use the phenomenon of gravity to get a picture of other things. So it does make sense to disregard the pieces of your signal that you know can be attributed to things you're not interested in. If one of those pieces is fully predictable, then you can just remove it - the fancy processing has to do with trying to remove things that are not predictable, like local noise. I do agree with you that great care is in order when imposing expectations on the output of an experiment, though. Like any other thing one does, it needs to be done right.

?? If your premise is that angular momentum is not conserved in a central force system, then you are simply wrong and we've pointed that out to you in a variety of ways. What is your ultimate goal here? Let's say you were right, and you can construct a case where angular momentum isn't conserved. Where do you go from there? Is the next step the description of some sort of "free energy device"?

Ah - I see what you mean. Ultimately its a strategy to influence your (potential) sympathizers, not the enemy. it makes sense when you look at it that way. And likewise, maintaining an understanding approach defeats that by making it less likely for the terrorists to gain new support amongst their own people. So yeah, I agree with that - the uncertainty I made reference to becomes one re: the beliefs of bulk of people who might or might not support terrorism, not the extreme people who already are terrorists. I find it much less likely (nearly impossible) that the average run-of-the-mill Islamic person has those extreme beliefs about killing all infidels. I think the people who try to tell us they all share that belief are full of it. Thanks for clarifying.

Sure - I don't really get to work in this area these days, in spite of it being my core training. So these opportunities are like sips of fine wine.

Yes, "squirrel strategy." Some acquaintances and I chat on IRC, and that's what we call it. Never mind all the important stuff - THERE'S A SQUIRREL!!!!! I don't know how much compulsory voting would change things. You're presuming people would (since they knew they had to vote) inform themselves of the issues and vote with the same sort of attitude you and I vote. I think many would resent the requirement and would just "make a motion." That would tend to randomize, and it would still be the extremes that controlled the outcome. Maybe a subset of the increased vote would arise from people who took it seriously because they were not allowed to ignore it, and so that would help some. I'm just not sure how much. I totally agree with you, though, that the right response to people like Nugent and Griffin is to ignore them. Not just the public response - the media response too. Our media behave more like entertainment outlets these days than like real news sources.

I think this depends on exactly what you mean by "can exist." Electrons can exist for periods of time without photon association. But the HUP makes that period of time variable, and I don't know to what extent you could "isolate" an electron such that you prevented such associations for any given period of time T. So in that sense I think such associations are allowed and expected, but in a probabilistic way.

The are picking them up - lots of them. But all of that is rejected (at least the local whispers) because only one of the LIGO facilities detects them. Now, if you mean "slight less local" whispers, like from the motion of bodies in our solar system, then the question has more merit. I guess it has to do with just how big the difference between the "screams" and the "whispers" are. I'm sure that we'd have been proud of anything that could be firmly ascribed to gravity waves since we're just starting out in this endeavor. But later, when we have much more sensitive facilities such that we could detect (for example - not sure if we'll be able to do this) the motion of Jupiter through the solar system, we'd remove that from the data as we processed it because we know Jupiter is there and we know we're not interested in that information.

Well, voter turnout is a problem; I agree. And i do fault non-voters for that, though they are of course free to do as they wish. If you sit back and let the 10% on each end do all the arguing and voting, then you're going to have to put up with a government that whipsaws back and forth between the two extremes, and that's certainly what we've had recently. I'd think, though, that "wrathful behavior" on one end would tend to motivate more people on the other end to vote, so in that sense it's not only pathetic behavior but also a flawed strategy.

Very true, and they'd need to use statistical techniques to guard against that. But at the same time, knowledge of what particular sought after events will "look like" in your apparatus is additional information that you can take advantage of. Of course, you also run the risk that such knowledge is flawed, in which case you're now looking for the wrong thing. But all of these things can be treated statistically, and I have to assume they have been. A simple example is knowing that you're looking for a particular frequency in your signal. Using either analog circuit techniques or digital processing of the output you can "lift that component" out of the results. If you assume the wrong frequency you won't find anything. But if you are close you hear something, and then you can fine tune. I'm sure they're taking the results they got on the black hole merger and using them to refine our expectations about such events. I think a lot of our physics experiments historically have "designed in" some expectation about what we expect to see - that's not a new thing at all.

I think that depends entirely on their mind set. If it's just a myth that they truly want "infidels" dead, then understanding is what we want. But if it's not a myth then understanding won't help. So you have an opinion on that, and it could be right. Each of us has to form an opinion on that in order to have rational thoughts about what we should do. But none of us knows for sure whether we're right or not.

It seems they still have sensitivity upgrades to do on several of these facilities. I'm guessing that in a few years we'll be picking up stuff like this routinely. It's really great that we got a "scream event" the way we did - it proves that the systems work and that we haven't wasted our money putting them in. I once read some stuff about home-built radio telescopes. By definition they were small, of course, since they were intended to be within reach of individuals. But if you had access to a parcel of land you could do the same kind of thing there - deploy several of them in an array, hundreds of meters apart, and use the same sort of time sync circuitry I mentioned above to get them locked together. Then you'd (sort of) have a very large radio telescope. I read last night they're planning a space-based gravitational observatory in the future. An array of satellites following Earth's orbit, but well away from Earth. I think it mentioned a 5 million kilometer arm length.

Why would the terrorists want a less-negotiation-minded adversary in control? Surely they don't really think they can win a full-on showdown. If I were in their position I'd want the most conciliatory, discussion-minded adversary possible. Not that I think they really want to negotiate, but that would be the environment that would let them "get away with more."

That's very possible. I don't really understand the logic they're expecting people to apply, though - this sort of thing would make me want a tougher-minded government in place, not a less-tough-minded one.

Right. That's why having two LIGO facilities far apart helps - each will be affected by different local noise sources, so anything that shows up on one but not the other can immediately be rejected. It also allows some directional resolution (where in the sky did the wave come from), though two facilities can only determine a line along which the source would have been. A third facility not collinear with the other two would allow full triangulation. I read that there was another facility in Europe that should have been able to detect the black whole merger, but unfortunately it was offline at the time of the event. In seismic work you place a 2D array of sensors (potentially tens of thousands of them) out over the landscape, and you design them so you can sync their clocks very accurately (sub-microsecond in the ones I helped design). Then with all of that data you can make very detailed pictures of the sub-surface structure. The companies that make the equipment generally don't do that, though - they just collect data. Other companies specialize in the data analysis. Getting the detailed design right in such ways is critical - "sort of right" doesn't get you there in seismic and I'm sure it doesn't for LIGO either. We actually equipped each sensor with a voltage controlled oscillator for its main clock, and the time sync algorithm adjusted them all until they all literally ran at the same frequency. Even though they were completely separate units that communicated only by radio, they nonetheless functioned more as though they were a single circuit. I'd really enjoy a detailed presentation of LIGO engineering issues - I'm sure there is some very, VERY impressive work involved. Science is wonderful, but seeing truly high quality engineering implementations can be equally inspiring. "The devil's in the details" really applies to stuff like this.

Likewise.

So you're trying to see how to get from step 2 to step 3? A one-input NOR gate is just an inverter; if you have the inverse of the input to that gate already available, then you can just remove the gate and use it. That's the gist of how they got from 2 to 3. I think there's an error, though - I think the D in diagram 2 should have become /D in diagram 3. Were these diagrams given, as part of the problem, or did you produce them? In the final diagram two things have happened: 1) one-input NORs of some signal X have been dropped because /X is also available directly, and 2) the two one-input NORs on either side of the wire marked with the arrow A+BD have been dropped, since inverse of inverse is no change.

You're implying that those negative techniques work. I think it's those extreme "edge people" that both produce and respond to such things, whereas its the more sensible middle segment that really steers election outcomes. Furthermore, anyone who attaches behaviors like Griffin's to the candidates in elections is behaving irrationally - no politician should be held responsible for the character of the people who vote for him or her. We're science-minded here, and we're supposed to know that any single correlation doesn't necessarily prove a causal connection. The general character of the Democratic party and candidates / office holders is not less today than it was a few days ago just because one supporter behaved in a tacky way.

Well, I imagine these measurements are not done directly with individual photons. The link Strange posted earlier made reference to extensive filtering and averaging methodologies to separate signal and noise - that implies a macroscopic number of photons in play. By the way, this may or may not be related, but I used to work in the seismic segment of the O&G industry, and we were interested in relatively low frequencies (low by EE standards at least, on the order of hundreds of Hz.) A modulation technique called sigma-delta worked in those frequency ranges, and you can get some quite impressive resolutions using those methods. We used 24-bit A/D converters. In our case too the instantaneous value of the acquired signal wasn't useful - a lot of processing has to be applied over many periods of the signal and even over repetitions of the generated excitation (using trucks that "shook the ground"). That's called "stacking" - you presume the signal response is the same in every case, but the noise will be different, so you can average it out.

That's not how I read your premises - that they implied no force perpendicular to the radius vector. And that is exactly when angular momentum is conserved. But that isn't the same as no tangential force. There is no force perpendicular to the radius. In circular motion that is the same as "no tangential force." But in elliptical motion that is not true, because in elliptical motion the motion is not everywhere perpendicular to the radius (if it were the radius would never change). So there is a force component parallel to *motion* at some locations along an elliptical path. Edit: Sorry - crossposted with swansont. In other words, yes, you are incorrect in saying there is no tangential force.

Well, you could set it up as simultaneous equations by introducing a new variable: 3x+8 = y 5x-4 = 3y which become 3x - y = -8 5x - 3y = 4 But that really makes the problem more complicated than it needs to be. Step one in solving that is to multiply the first equation by 3 and subtract them, which eliminates y.

You did specify zero torque in your OP - premise 1 and premise 3. Each of those describes a central force. Therefore angular momentum is conserved. Imagine that you lay a Cartesian x/y coordinate system down on top of your system, with the central point at the origin and such that at time t the radius vector lies along the x axis. You then stipulate that the force is directed along the x axis at that time. So the y component of momentum is conserved, but the x component is not. Shortly later, the radius vector is no longer parallel with the x axis. Therefore the x component of momentum now contributes to the component of momentum perpendicular to the (new) radius vector. So the force cannot affect the component of momentum perpendicular to the radius vector now, but it does affect the component of momentum that will be perpendicular to the radius vector later. This is why the speed of the object can change. These are really fundamental things, and we've explained them to you several ways - you're starting to come off as stubborn about this.

Thanks Strange - reading the first link now.