XPost: sci.electronics.design
From: bill.sloman@ieee.org
On 23/02/2026 9:10 am, Ross Finlayson wrote:
> On 02/22/2026 01:38 PM, J. J. Lodder wrote:
>> Bill Sloman wrote:
>>
>>> On 22/02/2026 9:25 pm, J. J. Lodder wrote:
>>>> Bill Sloman wrote:
>>>>
>>>>> On 21/02/2026 10:46 pm, J. J. Lodder wrote:
>>>>>> Bill Sloman wrote:
>>>>>>
>>>>>>> On 21/02/2026 5:52 am, Ross Finlayson wrote:
>>>>>>>> On 02/20/2026 10:31 AM, Bill Sloman wrote:
>>>>>>>>> On 21/02/2026 3:47 am, Ross Finlayson wrote:
>>>>>>>>>> On 02/19/2026 11:45 PM, Bill Sloman wrote:
>>>>>>>>>>> On 20/02/2026 10:48 am, Ross Finlayson wrote:
>>>>>>>>>>>> On 02/19/2026 11:19 AM, Bill Sloman wrote:
>>>>>>>>>>>>> On 20/02/2026 2:44 am, Ross Finlayson wrote:
>>>>>>>>>>>>>> On 02/19/2026 01:45 AM, Bill Sloman wrote:
>>>>>>>>>>>>>>> On 19/02/2026 6:13 am, Ross Finlayson wrote:
>>>>>>>>>>>>>>>> On 02/18/2026 11:06 AM, Ross Finlayson wrote:
>>>>>>>>>>>>>>>>> On 02/17/2026 08:35 PM, Bill Sloman wrote:
>>>>>>>>>>>>>>>>>> On 18/02/2026 5:37 am, Ross Finlayson wrote:
>>>>>>>>>>>>>>>>>>> On 02/17/2026 09:47 AM, Thomas 'PointedEars' Lahn wrote:
>>>>>>>>>>>>>>>>>>>> Ross Finlayson wrote:
>>>>>>>>>>>>>>>>>>>>> On 02/17/2026 03:49 AM, J. J. Lodder wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> I.e., mathematics _owes_ physics more and better mathematics
>>>>>>>> of continuity and infinity.
>>>>>>>
>>>>>>> Mathematics doesn't owe physics anything. Physics exploits tools
>>>>>>> developed by mathematicians, which makes physicists customers for
>>>>>>> the
>>>>>>> work of some mathematicians.
>>>>>>
>>>>>> That is quite arguable.
>>>>>> Much of mathematics wouldn't exist
>>>>>> without (what was once) new input from physics.
>>>>>> Many a luminary, Von Neumann for example,
>>>>>> has said that mathematics will go stale
>>>>>> without regular fresh input from the natural sciences,
>>>>>> bringing new needs.
>>>>>>
>>>>>>> A mathematical physicist like Paul Dirac is an interesting
>>>>>>> hybrid, but
>>>>>>> his biography is titled "The strangest man".
>>>>>>>
>>>>>>> https://en.wikipedia.org/wiki/Paul_Dirac
>>>>>>
>>>>>> Why discredit him by calling him 'a mathematical physicist'?
>>>>>> He was a theoretical physicist,
>>>>>
>>>>> He invented the Dirac function, and bra-ket notation. He was notably
>>>>> more deft with math than most of his contemporaries.
>>>>
>>>> Arguably. The real inventor was Oliver Heavidise.
>>>> (who loved to pester mathematicians with it)
>>>>
>>>> Dirac just gave it another, more elegant name. [1]
>>>> ( \delta(x) versus D H(x) or 1/2 D \signum(x) )
>>>>
>>>> And that 'most of' will depend on how wide you want to draw the circle.
>>>>
>>>>> https://en.wikipedia.org/wiki/Bra%E2%80%93ket_notation
>>>>
>>>> Nothing but notation. You can do without just as well.
>>>> Mathematicians object to it,
>>>> because the notation assumes without proof that adjoints exist.
>>>> (which often needs to be shown, by their standards)
>>>>
>>>>> He reconciled several ostensibly different quantum theories by
>>>>> pointing
>>>>> out that they were notational variations of the same basic idea.
>>>>
>>>> Yes. But imho his most important contribution
>>>> was getting quantum field theory started,
>>>
>>> "Quantum field theory" is just words to me.
>>
>> That is just too bad.
>> All of physics is quantum field theory these days,
>> at least in principle.
>>
>>>> [1] Dirac was an electrotechnical engineer by training.
>>>> He must have known about Heaviside and his operational calculus.
>>>
>>> Perhaps. He did his first degree at Bristol in 1921, and went on to do a
>>> separate degree in math in 1923. Heaviside was a controversial figure,
>>> and might not have been much cited at Bristol back then.
>>
>> Being controversial leads to being well-know.
>> And Heaviside solved a number of fundamental problems
>> in electromagnetism, so any electrical engineer
>> must know about his work.
>>
>> Even Maxwell's equations are only known nowadays
>> in the form Heaviside gave them.
>> Some people even call them the Maxwell-Heaviside equations.
>>
>>> Looking at Heaviside's wikipedia page, I note that he was the first to
>>> use the impulse function (now known as the Dirac function). If Dirac had
>>> known much about Heaviside's work, he probably would have called it the
>>> Heaviside function when he first used it.
>>
>> 'Heaviside function' is already in use for the unit step function,
>> (don't know about when that name originated, guess well before Dirac)
>>
>> Jan
>>
>
> Actually it's usually said that physics is a "gauge" theory,
> (a field theory), not necessarily a "quantum field" theory.
>
> Retro-finitists of the grainy sort who think that reality
> is digital and non-deterministic don't say much, then, do they?
>
> Except "close enough". Which fails, beyond variously
> the first or second order, that mathematicians know,
> and "physicists" shut up and compute.
>
> When I put "physicists" in quotes like that it means "technicians".
>
> Not that there's anything wrong with those, ...,
> just not that they're philosophers of physics
> about the truth of the matters, nor that they're
> "doing science".
Polyani in "Personal Knowledge" put paid to that approach.
https://en.wikipedia.org/wiki/Tacit_knowledge
It you aren't a "technician" in the sense of doing something with your
knowledge there are aspects of reality that you won't be able assess.
--
Bill Sloman, Sydney
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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