Mass isn't defined as invariant rest mass. Though maybe one should
make it the distinction between mass and inertia?

"Autymn D. C." wrote in message oups.com...
Mass isn't defined as invariant rest mass.

Apparently it usually is nowadays, whether you like it or not.

Dirk Vdm



Though maybe one should
make it the distinction between mass and inertia?

Autymn D. C. wrote:
Mass isn't defined as invariant rest mass.

Yes, it's oxymoronic to say a relative quantity
like "mass" is invariant in one Frame, picking
the arbituary "rest frame".

Dirk will never understand that, we've tried.
He's stuck in 1905 SR.

Though maybe one should
make it the distinction between mass and inertia?

In GR, you have 3 components for "mass" given by,
p^0, p , p_0 , where "p_0" is the "rest mass" and
is NOT invariant.
Ken

Autymn D. C. wrote:
Mass isn't defined as invariant rest mass.

Yes, it is. Today, when a physicist says "mass", he/she means the invariant.

In the past some authors used the word "mass" to mean what we call
"relativistic mass" today; because of the PUN on the word "mass",
careful modern authors do not use that phrase at all (except to refer to
its historical usage).

The meaning of this word has CHANGED over time. In this
newsgroup there will probably be a storm of replies claiming
other than what I said above. And there will also be replies
from people without a clue (e.g. Ken S. Tucker's below).
I am describing how the word is actually used by physicists
working in the field, TODAY.


Though maybe one should
make it the distinction between mass and inertia?

OF COURSE one must do so -- mass is a definite quantity, and "inertia"
is ill defined at best. Mass appears in lots of equations of physics,
"inertia" appears in none of them (e.g. there is no mathematical symbol
associated with it). What, precisely, do you think the word means?

This is physics; being "precise" means writing an equation.


Ken S. Tucker wrote:
Yes, it's oxymoronic to say a relative quantity
like "mass" is invariant in one Frame, picking
the arbituary "rest frame".

This is false (and confused). Mass is indeed invariant (meaning
independent of coordinate system or "frame"), in both SR and GR. This is
basic and fundamental -- an object's mass is the norm of its 4-momentum.


Tom Roberts

"Tom Roberts" wrote in message ...
Autymn D. C. wrote:
Mass isn't defined as invariant rest mass.

Yes, it is. Today, when a physicist says "mass", he/she means the invariant.

In the past some authors used the word "mass" to mean what we call
"relativistic mass" today; because of the PUN on the word "mass",
careful modern authors do not use that phrase at all (except to refer to
its historical usage).

The meaning of this word has CHANGED over time. In this
newsgroup there will probably be a storm of replies claiming
other than what I said above. And there will also be replies
from people without a clue (e.g. Ken S. Tucker's below).

Pmb seems to have left the building.
I wonder when Tucker will follow.

Dirk Vdm

"Tom Roberts" wrote in message
...
Autymn D. C. wrote:
Mass isn't defined as invariant rest mass.

Yes, it is. Today, when a physicist says "mass", he/she means the
invariant.

In the past some authors used the word "mass" to mean what we call
"relativistic mass" today; because of the PUN on the word "mass", careful
modern authors do not use that phrase at all (except to refer to its
historical usage).

The meaning of this word has CHANGED over time. In this
newsgroup there will probably be a storm of replies claiming
other than what I said above. And there will also be replies
from people without a clue (e.g. Ken S. Tucker's below).
I am describing how the word is actually used by physicists
working in the field, TODAY.

And I suspect it has been that way for some time. Landau does not even
define it in the Classical Theory of Fields.

Thanks
Bill



Though maybe one should
make it the distinction between mass and inertia?

OF COURSE one must do so -- mass is a definite quantity, and "inertia" is
ill defined at best. Mass appears in lots of equations of physics,
"inertia" appears in none of them (e.g. there is no mathematical symbol
associated with it). What, precisely, do you think the word means?

This is physics; being "precise" means writing an equation.


Ken S. Tucker wrote:
Yes, it's oxymoronic to say a relative quantity
like "mass" is invariant in one Frame, picking
the arbituary "rest frame".

This is false (and confused). Mass is indeed invariant (meaning
independent of coordinate system or "frame"), in both SR and GR. This is
basic and fundamental -- an object's mass is the norm of its 4-momentum.


Tom Roberts

Ken S. Tucker wrote:
Yes, it's oxymoronic to say a relative quantity
like "mass" is invariant in one Frame, picking
the arbituary "rest frame".

What Tom is about to write is...

false (and confused). Mass is indeed invariant (meaning
independent of coordinate system or "frame"), in both SR and GR. This is
basic and fundamental -- an object's mass is the norm of its 4-momentum.
Tom Roberts

Ok, that's what I said about "p" , in agreement with Autymn, he's
accurate.

Define the momentum components p^0 , p , p_0 and while your
at it define the spatials p^i , p_i for us, consistent with GR.

In GR, spacetime is nonorthogonal, meaning the component
p^u =/= p_u.

As a simple example using association,

p_0 = g_00 p^0 .

In a g-field, recall g_00 =/=1, hence the geometry fractures by
the imposition of energy in the near-field and g_00 =/= g^00.

Ok, define, define, define.
I think Tom can do it, I'm listening...
Ken

Dirk Van de moortel wrote:
"Tom Roberts" wrote in message ...
Autymn D. C. wrote:
Mass isn't defined as invariant rest mass.

Yes, it is. Today, when a physicist says "mass", he/she means the invariant.

In the past some authors used the word "mass" to mean what we call
"relativistic mass" today; because of the PUN on the word "mass",
careful modern authors do not use that phrase at all (except to refer to
its historical usage).

The meaning of this word has CHANGED over time. In this
newsgroup there will probably be a storm of replies claiming
other than what I said above. And there will also be replies
from people without a clue (e.g. Ken S. Tucker's below).

Pmb seems to have left the building.
I wonder when Tucker will follow.

Dirk Vdm

Do the math. $1 billion of taxpayers money is
wrapped in GP-b, that's a lot, so be less
arrogant.

In one definition it works, in the other it
doesn't.

We have missile upstairs that will, properly
determined, set forth the theoretical agenda
for the next few decades and more possibly a
century.

Anyone who can contribute is invited to remark,
but shut the ****in idiot remarks out, we're
flyin' high and data is eminent, for the future
generation of physicists, have respect as would
to those who have given their lives to make
theses missions possible.
Ken S. Tucker

In article ,
Dirk Van de moortel wrote:

Pmb seems to have left the building.

He posted on physicsforums.com just yesterday. Apparently he's been
having health problems.

http://www.physicsforums.com/showthread.php?t=85243

--
Jon Bell Presbyterian College
Dept. of Physics and Computer Science Clinton, South Carolina USA

Tom Roberts wrote:
Yes, it is. Today, when a physicist says "mass", he/she means the invariant.

What one means doesn't make it right.

In the past some authors used the word "mass" to mean what we call
"relativistic mass" today; because of the PUN on the word "mass",
careful modern authors do not use that phrase at all (except to refer to
its historical usage).

What's wrong with it?

OF COURSE one must do so -- mass is a definite quantity, and "inertia"
is ill defined at best. Mass appears in lots of equations of physics,
"inertia" appears in none of them (e.g. there is no mathematical symbol
associated with it). What, precisely, do you think the word means?

One hears a distinction yet equivalence between inertial mass and
gravitational mass. If they are equivalent, then a relativistic object
would through greater mass [or as you would groundlessly say through
greater stress-energy because of momentum] have stronger gravity. I
invoked inertia because it was an experimental, not postulated,
property so it would be better to assign it to the variant or
relativistic mass.

-Aut