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Yeah, it's just a crazy idea. And sure if they did exist then there'd be a 'ripple' or something early on in the big bang when they joined together and became 'transparent' to the rest of the stuff. Still if dark matter is ever found and it turns out to be 'bound up' monopoles....

Seems as good a candidate as any of the other dark matter 'particles' But I know squat about particle physics*.

George H.

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You understand a few more of them than I do, then!

I'm still not sure what "grok" means ;-)

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=A0 =A0(Richard Feynman)

Robert Heinlien's "Stranger In a Strangeland"

Not my kind of reading. I never liked "science" fiction.

SiaSL isn't science fiction, it's half-baked religion. Heinlein was the one that dared L. Ron Hubbard to start Scientology. (For anyone who doesn't know the story, Hubbard bragged that he could make a lot more money by starting a religion than by writing SF. He was quite right, but that shrewdness just about exhausts his admirable qualities.)

Cheers

Phil Hobbs

In that case, I *definitely* want nothing to do with it.

ic

=A0 =A0(Richard Feynman)

Ever notice the parallel between religion and science?

Years ago, it was thought that religion answered ALL quesstions. People get lost in religion, and if you don't adhere to the rules, you get branded as a heretic and persecuted and/or drummed out of society.

Today, it's thought that science answers ALL questions. People get lost in science, and if you don't adhere to the rules, you get branded 'non-scientific' and persecuted and/or drummed out of ...you get the idea.

Wonder what's next? Non-causal, simultaneity?

I wouldn't subscribe to your picture of religion above, but it's perfectly true that we have a number of rather unpleasant modern religions nowadays: scientism (as opposed to science, though there's some overlap in the participants), environmentalism, and anti-humanism.

By "environmentalism" I don't mean folks like me, who keep the thermostat turned down, make a point of living close to work, and try not to waste stuff--I mean the folks that think that the sky is falling, that fracturing rock a mile below the ground water level can hurt anything, and (especially) that the planet would be better off without any people on it.

Cheers

Phil Hobbs

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Thank you, i learned something today.

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I suspect that until someone has sufficient problem with core noise to actually specify the test conditions there won't ever be any.

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Thanks. My inspiration was opposite, as even amorphous materials still have magnetic domains. It is kind of a fineness of dimension thing. The surface of glass is smooth to low microscopic levels but not at 10000 times magnification.

?-)

Yeah, noise is not usually something anybody needs to know about.

My need has to do with AC current sensing at very low levels.

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How low? Accuracy? Trip point, or characterize the current exactly? Are you measuring the field adjacent to a single conductor?

Have to double check, but 5 mils away from a 36Awg wire should be able to have noise floors below femtoAmps/rtHz. Linearity better than 0.1%; absolute accuracy on the order of 1-3%; and repeatable accuracy better than 0.1%

I have designed portable AC magnetic field sensors with noise floor densities below noise of earth's field, into the femtoTesla/rtHz to replace SQUIDs for oil field exploration - much cheaper, and much easier to work with in the field. Don't recommend that exact design here, they were over 18 inches in diameter and weighed around 20lb

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Accuracy is not a problem. BTW the Hall effect device located in the gap may have higher noise than anything but noise specs for HE sensors are fairly ambiguous too although Allegro does have what they call "low noise" HE devices.

Sounds kind of expensive... I see DC squids and RF squids. Do they work up to about 20 kHz ?

BTW, I thought high temperature superconductivity wasn't quite there yet ?

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Actually, less than $100 each sensor.

Don't know a lot about SQUIDs, except know they're being used to map

My design does NOT use any superconducting principle. The design has such a low noise floor that it can replace SQUIDs because the noise floor does not have to be much lower than the earth's magnetic field's noise. In other words, the sensor only has to be as good as the measurement environment; making SQUIDs an overkill.