BurtJordaan » May 18th, 2020, 4:35 am wrote:What you and I are doing is searching for alternative diagramming in order to make it more intuitive, but this cannot alter the inherent principles of physics. … The applicability of SR is limited to

flat spacetime… so I disagree. In a particular inertial frame,

a single spacetime event may not have infinite unique coordinate designations.

Even with local flatness, we still have to come to grips with the non-Euclidean relation of space and time in the interval formulas. We might argue for locally flat

space but there is no flat

spacetime. When spacetime is forced on a flat map, some

single events get s-t-r-e-t-c-h-e-d, as they do with Mercator projections.

"

Although the geometry of space-time is not Euclidean in the ordinary sense, there is a geometry which is very similar, but peculiar in certain respects. …the interval between two space-time points [events]…We give it a different name because it is in a different geometry…some signs are reversed and there is a c in it." -

Feynman p.97

BurtJordaan wrote:I have a problem with many of your out of context little quotes.

I'll try to provide better context. But do parse

my posts ad lib. It helps focus on exactly where we disagree. Such as…

BurtJordaan wrote:"4D contact" is really at the core of our disagreements.

That's progress. So is this...

I don't recall using "interval time" but certainly I use "interval speed".

What a great concept! I think a "real" physicist almost beat me to it. Let's examine the relevant quote you

most wish to ignore.

Richard Feynman is a hero to most physicists.

He was a grad student of the great teacher,

John Wheeler.

He earned a Nobel prize for QED which deals with light.

This is from his book on

Relativity and Spacetime (excerpted from his revered

lecture series).

Heck, I'd wager even hyksos thinks he was pretty bright.

You've seen part of the quote before. I got a bit more (asterisks for context,

bold = mine).

"

In our diagram of spacetime, therefore, we would have a representation something like this: at 45° are two lines (actually,…light cones) and points on these lines are all at zero interval from the origin. Where light goes from a given point is always separated by a zero interval as we see from equation. (5.5)*. Incidentally, we have just proved that if light travels with speed c in one system, it travels with speed c in another, for if the interval is the same in both systems,** i.e. zero in one and zero in the other, then to state that the propagation speed of light is invariant is the same as saying that the interval is zero." –

Feynman p.99

*refers to these equivalent interval expressions as seen in two different inertial frames:

t’² – x’² – y’² – z’² = t² – x² – y² – z²**"systems" refers to different (primed & unprimed) inertial frames.

Am I the only one who thinks that's worth reading a few times? He refers to

zero interval separation no less than

five times! Maybe that's

important. And you've got to ask, how in the world did he intuit

c = c’ from a

zero interval? Don't dismiss this lightly. Feynman's not kidding around. He considers this a

proof!I believe he subconsciously sensed what I've explicitly stated in two equivalent ways:

If he sensed that two

different coordinate designations with zero interval separation are the

same 4D event then:

c is an absolute speed limit because nothing gets closer than contact!If Feynman considered

interval speed as analogous to conventional speed and realized

zero interval speed is uniquely invariant:

c is an absolute speed limit because nothing is slower than absolute rest!Unfortunately, Feynman's wonderful lectures flow like free association. He moves on to the light cone and causality so, there’s nothing more there to give you. Pity, if he had gone just two sentences deeper, he might have gotten a second Nobel prize. Still, we shouldn't blame Feynman. After all, he never had the opportunity to discuss physics with

me.

What's your excuse?