Re: Question on Spacetime dilation.

Hi Tom.
You have limited reading comprehension skills,
(sorry the truth hurts), about on my level when
I was in Grade 7, try to improve.

On Dec 19, 11:46 am, Tom Roberts <tjroberts...@xxxxxxxxxxxxx> wrote:
Ken S. Tucker wrote:
Alen wrote:
I would think that, if
delta^u_v = e^u.e_v
then e_v = 1/e^v

Wow Alen, that's an original way of writing
and looks correct to me, haven't seen it done
like that before!

There is a very good reason for not having seen it before -- it is
nonsense!

Once again Tom, your limited exposure and under-
standing of REAL math becomes apparent, as you
failed to account for the "domain of applicability",
i.e. unit orthogonal basis vectors.
Myself I would NOT do it that way, but I've seen
some genius mathematicians who know more than I
do, and way more than you Tom, take that type of
approach, it's called initiative.

This is what happens when you use notation like a black box,
without understanding what the symbols actually represent. In particular:
* you are confusing indexes that label components of a tensor
with indexes that label basis vectors.
* you are confusing the Kronecker delta (which is a matrix of
real numbers) with the mixed metric components (which are the
components of a rank (1,1) tensor). Both are sometimes notated
as delta^u_v which probably contributed to your confusion (though
the mixed metric components are more commonly notated g^u_v).
* that division written above has no real meaning (e^v is a basis
vector, which is not an element of any division algebra).

Ken, you do this all the time,

Tom, you FAILED to read what I wrote, read
"haven't seen it done like that before!"
what does that mean??

and it completely invalidates >90% of
what you write around here.

LOL, Since you're obviously illiterate that
is likely to occur, and benefits me.

I rarely respond, as you clearly do not
understand the issues,

How would you know Tom, you can't even read.

and prefer to rant and rave rather than learn
something.

Where is this so-called "rant and rave"?

Hint: write down what EVERY symbol means, including what
type it is and the type(s) of its argument(s), if any.
In particular, what is the "." in your
"delta^u_v = e^u.e_v"??? -- there is no normal dot product

Of course there is, you want to understand a
simple definition of the metric,

g_uv = e_u.e_v
g^u_v = e^u.e_v , Kronecker delta.
g^uv = e^u.e^v .

defined between a vector (e_v) and a covector (e^v). And
what are the "/" and the "=" in "e_v = 1/e^v"??? ["="
cannot be equality when applied to incommensurate types.]

Again I'll stress, within "the domain of applicabilty"
Alen's notation looks ok to me.

In GR it's fairly common to approximate
g^00 = 1/g_00 , g^11 = 1/g_11
that works 99.9% of the time in weak fields,
and is where Alen's suggested notation will
lead to.

Unlike you Tom, I'm NOT a goose-stepping idiot who
automatically assumes an unfamiliar suggestion is
verboten, on the contrary, I respected my fellow
poster's (Alen) suggestion, and after consideration,
and wide experience with variations of notation,
find it reasonable, that's my expert opinion.

A few century's ago the sqrt(-1) was considered
near cranky, I can provide many examples like
that in the evolution of mathematics.
Using Tom's attitude and his ilk, only Roman
Numerals would be allowed if I allowed him to
stifle progress, but I won't.

Maybe Alen is a math genious, and knows more
than Tom does, but that's easy to do anyway.
Regards
Ken S. Tucker
.

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