Re: [ANN] SR/InertialFrames v2.2.1

Am Sonntag000025, 25.05.2025 um 13:46 schrieb Julio Di Egidio:

On 25/05/2025 06:31, Thomas Heger wrote:

Am Samstag000024, 24.05.2025 um 19:53 schrieb Ross Finlayson:

On 05/24/2025 08:21 AM, Julio Di Egidio wrote:

On 24/05/2025 16:48, Ross Finlayson wrote:

On 05/21/2025 04:47 AM, Julio Di Egidio wrote:

>

A clock hypothesis: is a pretty usual idea, that there
are no closed time-like curves and furthermore that whatever
meets has whatever clocks meet. Einstein called it a, "the time",

>
That's false on all accounts, including the time travel
side of things, you still cannot get your head around
which, apparently.  That said, thanks for asking:
>
The "clock hypothesis", in simple terms, is the principle
that all working clocks tick at the same rate (the proper
time rate) in their own frame.  Drop that and you drop
any chance of doing any physics at all: together with
the use of light signals, clocks are fundamental to
contemporary physics and the very measurement process.
>
It is also equivalently the hypothesis that the local
experience of time is universally the same for every
particle and every observer: and I do not actually
mean anything psychological, rather the rate of getting
old, just like the rate of atom decay, is a physics fact.
>
And note that none of that is about inertial frames and
motion only: time proper ticks at the same rate every
time every place.  Indeed, time dilation and length
contraction are only relativistic effects, we know that,
don't we? "Nothing is actually slowing or shortening
aboard that ship", which remains canonical relativity.

>
Ah, no, "clock hypothesis" is usually that there's
a, "universal time", for example an Einstein's "the time".

>
'a universal time' for the entire universe does not make sense!
>
We need actually the concept of 'local time' and sets of locations, which share the same local time and build in sum what I call a 'time domaine'.
>
On-time-only-universe is plain wrong!
>
The reasons to think so are a little tricky.
>
But there exists a good book about this topic, which I like to recommend:

 A resident clown chimes in.
 How fucking pathetic to put it charitably.
 

'Local time' is an important concept by e.g. Henry Poincaré.
Why time should be a local parameter is justified by a number of reasons.
For instance the very idea of GR is based on 'many timelines', not just a single one.
But also pair-production and the issue of 'anti-matter'  can be nicely be explained by different 'worlds' which have their own, but opposite time.
There are a few more topics, where local time would be important.
But a very good reason is actually 'symmetry'.
Because if you take time as local parameter, you could combine time with the (also local) axes of space to fourvectors, if you regard the axis of time as imaginary (what Poincaré actually did).
Now you could create four-vectors, with imaginary scalar parts.
These mathematical objects do in fact exist and have the nice name 'complex four-vectors' (aka 'biquaternions').
This can be symbolized by a geometric figure called 'star tetrahedron', if you add the inverted imaginary four-vector from our world 'head down' to our own, which has a 'four spike vector' 'head up'.
These things called 'biquaternions' are not known to a wider audience, but have already turned out to be extremly useful in phyics (and other realms).
I have depicted this topic in my 'book' about 'structured spacetime':
https://docs.google.com/presentation/d/1Ur3_giuk2l439fxUa8QHX4wTDxBEaM6lOlgVUa0cFU4/edit?usp=sharing
which I would recommend, because it is still free to read or download and actually much easier to read (and also much nicer) than most books in theoretical physics.
The 'very good reason' for this concept, btw, is its simplicity.
The main diasadvantage is, that it is very counter-intuitive.
TH