XPost: sci.physics.relativity
From: bill.sloman@ieee.org
On 20/02/2026 9:35 pm, J. J. Lodder wrote:
> Bill Sloman wrote:
>
>> On 20/02/2026 7:41 am, J. J. Lodder wrote:
>>> wBill Sloman wrote:
>>>
>>>> On 20/02/2026 12:13 am, J. J. Lodder wrote:
>>>>> Bill Sloman wrote:
>>>>>
>>>>>> On 19/02/2026 9:56 pm, J. J. Lodder wrote:
>>>>>>> Bill Sloman wrote:
>>>>>>>
>>>>>>>> On 19/02/2026 7:49 am, Ross Finlayson wrote:
>>>>>>>>> On 02/18/2026 12:43 PM, Python wrote:
>>>>>>>>>> Le 18/02/2026 à 20:13, Ross Finlayson a écrit :
>>>>>>>>>> ..
>>>>>>>>>>> and, you know, magnetic monopoles, is widely employed
>>>>>>>>>>> in medical imaging and the like.
>>>>>>>>>>
>>>>>>>>>> No.
>>>>>>>>>
>>>>>>>>> Resonance imaging (NMR) is a thoroughly different mechanism
>>>>>>>>> than Roentgen rays.
>>>>>>>>
>>>>>>>> But as the name implies, it's nuclei of the atoms involved that
>>>>>>>> exhibit the resonance. It's a remarkably low energy effect, and you
>>>>>>>> need remarkably high magnetic fields to get it to give you a
>>>>>>>> detectable signal.
>>>>>>>
>>>>>>> Nevertheless, it is easily demonstrated in the kitchen
>>>>>>> with some simple electronics.
>>>>>>
>>>>>> Sort of.
>>>>>>
>>>>>> https://en.wikipedia.org/wiki/Nuclear_magnetic_resonance
>>>>>>
>>>>>> There are lots of different ways to exploit nuclear magnetic resonance.
>>>>>> The earth's magnetic field is high enough to let you devise experiments
>>>>>> that can demonstrate the effect on a kitchen table.
>>>>>
>>>>> Nothing 'sort of'.
>>>>> You -can- easily demonstrate the effect on the kitchen table.
>>>>> (at audio frequencies) Wikipedia is right here.
>>>>
>>>> Yes, but we were talking about medical imaging, not nuclear magnetic
>>>> resonance in general, and your assertion is the irrelevance here, as the
>>>> text you snipped pointed out.
>>>
>>> Which 'we' dear Bill?
>>
>> If you can't work that out, you aren't worth talking to.
>
> Understood, your majesty.
>
>>> I replied to your
>>> ===
>>>>>>> But as the name implies, it's nuclei of the atoms involved that
>>>>>>> exhibit the resonance. It's a remarkably low energy effect, and you
>>>>>>> need remarkably high magnetic fields to get it to give you a
>>>>>>> detectable signal.
>>> ===
>>> which is just plain wrong.
>>
>> In your ever-so-authoritative opinion.
>
> FYI,
> Behaving like a stubborn ass doesn't improve your credibity in general.
Calling people stubborn asses doesn't help yours either.
>>> As a matter of fact, zero to ultra-low frequency NMR
>>> is a flourishing research field these days,
>>
>> It's cheap to do, so lots of graduate students get stuck with studying
>> it. The results of their research don't seem to get published in
>> high-impact journals.
>
> Why can't you just admit that your statement that 'remarkably high
> fields are needed to give you a detectable signal'
> is just plain wrong?
It does depend on what your are trying to detect. It's certainly true in
a lot of situations of practical interest. Laboratory NMR machines did
go in for high magnetic fields.
> As a matter of fact NMR can be done in zero or near-zero fields,
> at very low frequencies.
> FYI, there is a large Wikipedia article devoted to it.
>
That does depend on " highly sensitive magnetic sensors - SQUIDs,
magnetoresistive sensors, and SERF atomic magnetometers".
Super-conducting quantum interference devices used to need liquid
helium. Presumably high temperature super conductors could let you get
away with liquid nitrogen, which is lot cheaper.
I was a chemist for long enough to be aware of the difference between
faddish research technique that you only found in research labs and more
practical approaches that you run into in industry.
Since I spent quite a few years working on electron-beam
microfabricators which sold for about a million dollars into
semiconductor fabs that cost about $500 million dollars (back then) my
idea of "industry" covers some fairly high end gear.
--
Bill Sloman, Sydney
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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