XPost: sci.physics.relativity
From: bill.sloman@ieee.org
On 21/02/2026 7:47 am, J. J. Lodder wrote:
> Bill Sloman wrote:
>
>> 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.
>
> Then don't behave like one.
> You've been long enough in SPR by now for an idea of who is who.
>
>>>>> 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.
>
> Felix Bloch discovered it in the MHz regime, iirc.
> (he measured relaxation times)
>
>>> 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".
>
> Yes. Progress often comes from having more advanced instrumentation.
Developing more advanced instrumentation can let you tackle previously
intractable problems. People talk about a solution looking for a problem.
>> Super-conducting quantum interference devices used to need liquid
>> helium.
>
> Yes, so what. You have that available, if needed, in a research lab.
If you've got enough money. If you need helium-3 as your refrigerant,
you apparently need political influence as well.
>> Presumably high temperature super conductors could let you get
>> away with liquid nitrogen, which is lot cheaper.
>
> Yes. but for research the cost of liquid Helium is not really important.
But only if you have enough money.
>> 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.
>
> There is no need to go overly defensive,
> the problem was you being too aggressive.
I don't see it as a problem.
> As for new research technique:
> it has to be tried before you can know what can be done with it.
> Meanwhile the results are publishable.
It helps if they are publishable in a high impact journal.
When I was a graduate student one of the lecturers kept his students
busy publishing papers on the properties of the simpler conpounds of
technicium - the lightest element that hasn't got a stable isotope. He
had contacts in the reactor business that let him get hold of enough of
it to do that kid of work. The results got published in mior league
journals.
>> 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.
>
> Really, there is genuine science and technology
> at less than a hundred megabuck a year.
My father got his 25 patents in the paper industry, which - while
capital intensive - isn't in the hundreds of megabucks a year category.
My last job was with Haffmans B/V in Venlo in the Netherlands who made
instrumentation for breweries.
--
Bill Sloman, Sydney
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
|
