Ian Bland:
"Pmb" wrote in message

Without question - Yes. That's what Feynman meant when he said in
"Character
of Physical Law" page 76
------------------------------------------
..., the mass of an object changes when it moves, because of the
conservation of energy. Because of the relation of mass and energy the
energy of associated with the motion appears as an extra mass, so things
get heavier when they move.
------------------------------------------


This is what I had always thought. Why then does there appear to be
controversy about it?

There's no controversy about what feynman said. The only so-called
"controversy" was one created by pmb in an attempt to support his
own idiosyncratic usage of the term "mass" by misconstruing or
quoting out of context, statements made by highly regarded physicists.

The source of the gravitational field is stress-energy tensor which
contains more than just the mass of the bodies. It would appear that his
misuse of the terminology has led right into the trap the physics faq
warns against.

Does the mass really increase by a factor of \gamma in the relativistic
mass for a particle in an accelerator? If so, then one would naively
conclude that any object would look like a black hole for large enough
relative velocities. This is obviously not correct, unless one believes
the earth would become a black hole if a proton passed by at a large
enough velocity. After all, in the proton rest frame, the earth is
moving at the same velocity as the proton moves in the earth's rest
frame. Therefore, it follows from the (mis) use of "mass" to mean
"relativistic mass", the "mass" becomes large enough for large enough
velocities that the object undergoes gravitational collapse. This
is obviously not correct.

See the following two physics faqs for additional information regarding
the pitfalls associated with using the term "relativistic mass" to mean
"mass":

http://math.ucr.edu/home/baez/physic...lack_fast.html

http://math.ucr.edu/home/baez/physic...y/SR/mass.html

In short, physicists use the term "mass" to mean "rest mass", unless
specifically defined other wise, and even then it isn't likely to be
designated as `m' with no subscript to eliminate confusion. The only
person who appears to have a problem with this is pmb. Why, I can only
guess.

Pmb:
"Ian Bland" wrote in message

This is what I had always thought. Why then does there appear to be
controversy about it?

I have no idea.

You should, since the only so-called controversy here is the one
you're attempting to create.

Some people (e.g. waite) don't understand the relationship between mass
and weight. These people always avoid the fact that a moving body weighs
more than the same body at rest.

And you think the relativistic mass is the `m' that goes in the
"weight", right?

Instead they post lame comments that I don't understand the difference
in that weight is not mass. Duh!

If you think that, then you haven't understood the comments.

These same ignorant people are unable to understand that weight is
'proportional' to mass. In this case its the passive gravitational aspect of
mass to which weight refers to. However the quantitative measure is exactly
the same when measured locally. I.e. if W = weight and M_g = passive
gravitational mass and m = m_o/sqrt[1-(v/c)^2] = mass, m_o = rest mass and g
= locall acceleration due to gravity then

W == M_g*g = mg

In other words - Since W depends on velocity and g does not then M_g = m
must depend on velocity.

So, following your argument, one would conclude that a cosmic ray
muon passing through the center of the earth, with a \gamma 0f 7 x 10^8
would turn the eartg into a black hole from which the muon (as well
as what could be loosely called "the rest of us") could never escape?
That would seem to fly in the face of logic. That might not be a problem
for you, but for the rest of us, the physics faqs point out that this
kind of logical fallacy is what happens when taking relativistic mass
too seriously.

"FrediFizzx" wrote in message ...
"Bilge" wrote in message
...
| Pmb:
|
|
| This is an honest question -
|
| No one's buying that, so you might as well not bother and save
typing
| 5 words and a hyphen.
|
| even if the slime that provoked it...
|
| Well! I must say,
|
| I am gross and perverted, I'm obsessed 'n deranged
| I have existed for years, But very little had changed
| I am the tool of the Government, And industry too
| For I am destined to rule, And regulate you
|
| I may be vile and pernicious, But you can't look away
| I make you think I'm malicious, With the stuff that I say
| I am the best you can get, Have you guessed me yet?
|
| I am the slime oozin' out
| From your news on usenet
|
| You will obey me while I lead you
| And eat the garbage that I feed you
| While you post and we don't heed you,
| Don't got for help...no one will believe you
| Your mind is totally controlled
| It has been stuffed into my mold
| And you will do as you are told
| Until the rights to you are sold
|
| That's right, Pmb..
| Don't click that mouse button
|
| Well, I am the slime from your post before
| Oozin' along on your livin'room floor
|
| I am the slime from your post before
| Can't stop the slime, but Pmb don't know
|
|
| ---
| [with apologies to Frank Z]

AHAHAHAHA! No need to apologize; I think Frank would approve.

He certainly would ;-)

"Some scientists claim that hydrogen, because it is so plentiful, is
the basic building block of the universe. I dispute that. I say that
there is more stupidity than hydrogen, and that is the basic building
block of the universe." - Frank Zappa

Dirk Vdm

On Sun, 26 Oct 2003 "Robert J. Kolker" wrote:

Joe Fischer wrote:
There really isn't any purpose in knowing the quantity
represented by "relativistic mass", it was thought to be useful
at one time, but was found to be of very limited use and the
term definitely gives the wrong impression about what causes
the non-linear value of energy of motion at high relative
speeds.

I find the notion that matter becomes more sluggish or inert as its
velocity relative to the frame where inertness is measure goes up.

Can you reword that and make a complete sentence or
statemant out of it?

Nothing about an object changes because something
else is moving relative to it, and nothing about the same object
changes because it moves relative to something else.
These are the only two possibilities, so motion changes
nothing (absolute velocity nuts not welcome).

When
you accelerate electrons in an acclerator the faster they go, the harder
(i.e. the more energy) is required to increase their speed.

It is related to stopping distance, obviously if an object
requires a greater stopping distance, it takes more energy to
stop it, and if it takes more energy to stop it, it takes more
energy to get it going.

Yes, yes, I
know it is the momentum that is going up with velocity
[m_rest*v/sqrt(1-v^2)] but intuitively it -seems- as though the
electrons are getting heavier and heavier.

Not if you understand physics, with slow acceleration,
nothing about an object changes, no matter what.
There are things that intuition helps with, and some
things it does not.

While this is an abuse of the
terms mass, massive, heavier it is also intuitive. In -The Feynman
Lectures-, R. Feynman makes use of this not completely exact locuation,
so it is not an act of stupidity to abuse the terms --- PROVIDED, one
knows exactly what the quantities involved are.

And the fact is, momentum and kinetic energy are NOT
"quantities", they are mathematical "values".

Purists prefer not to use this locuation. As long as the defnition is
clear and out there, no harm is done by abusing the language a bit.
After all we still talk about sunrise and sunset, don't we?
Bob Kolker

If you say "relativistic mass", and say it is a calculated value
and not a "quantity" or attribute of matter, fine.

The terms begin with mass, and the qualifiers of the that
word have to be added to converse rationally.
You can write about relativistic mass all day and never
get a complaint, as long as you use a different identifier
for relativistic mass than is being used for mass.
As long as terms are defined in an article, they can
meann anything. I like to use p for pressure, but being
I know p is often used for something else, I specify that
p will mean pressure.

It should not require a college degree to work out
a way to do this so that there is no disagreement.
The qualifiers or descriptive adjectives follow
a rational pattern.

Dog
Spotted dog
Brown dog,
Big dog
Little dog.

But they are all dogs, and everybody should
agree.

Joe Fischer

Pmb:

Also note that there are always different ways to describe things and this
is no difference. But some ignorant people (e.g. waite) claim that there are
no other way than their way - and that of course is a very bogus claim and a
claim that they are unable or unwilling to back up.


That isn't what the "some ignorant people" to whom you refer are
telling you. What you are being told is that "relativistic mass"
is not a synonym for "mass" and that no one (excluding you) uses it
that way. "Relativistic mass" is an inherently newtonian concept.

On Sun, 26 Oct 2003 "Ian Bland" wrote:

"Pmb" wrote:
For many years now I've requested proof of these baseless claims that the
term 'mass' always refers to 'rest mass' yet nobody is willing to prove
it. [snip]

So, a simple question. If I accelerate some particles (type doesn't matter)
to just below c in a particle accelerator, situated somewhere on earth,
whose weight can be measured to astonishing accuracy because it is mounted
on my patent Astonishingly Accurate Very Large Spring Balance, does it (the
whole system) become heavier?
Ian

Since motion is relative, it should be acceptable to
consider any object to be "at rest" and the other object moving.

So, sure, when the electrons get going close to c, the
accelerator gets so heavy, it sinks into the ground, never
to be seen again. :-)

Joe Fischer

"Joe Fischer" wrote in message
...
On Sun, 26 Oct 2003 "Ian Bland" wrote:

"Pmb" wrote:
For many years now I've requested proof of these baseless claims that
the
term 'mass' always refers to 'rest mass' yet nobody is willing to prove
it. [snip]

So, a simple question. If I accelerate some particles (type doesn't
matter)
to just below c in a particle accelerator, situated somewhere on earth,
whose weight can be measured to astonishing accuracy because it is
mounted
on my patent Astonishingly Accurate Very Large Spring Balance, does it
(the
whole system) become heavier?
Ian

Since motion is relative, it should be acceptable to
consider any object to be "at rest" and the other object moving.

So, sure, when the electrons get going close to c, the
accelerator gets so heavy, it sinks into the ground, never
to be seen again. :-)

Joe Fischer


I give up

It seems a simple enough question; does mass increase as velocity does? If
the "mass" being piled on at high speed isn't really massive, then it isn't
mass, is it? It's "resistance to acceleration" perhaps, but it's not even
really that, since apparently nothing intrinsic to whatever is zooming along
at high speed has actually changed. All one can say is that high speed
objects have one characteristic associated with increased mass; resistance
to acceleration. But they don't weigh any more (as a massive object would)
their gravitational pull isn't increased (as it would if mass had increased)
and, er, they haven't got any more mass at all.

It isn't mass then is it?

Einstein seemed to think that mass was dependent on velocity. I thought he
wrote a paper on the subject. I *thought* he based a relatively famous
theory on this.

But if it *isn't* mass; why then does nuclear binding energy have mass,
real bona fide mass that weighs something, and why is it generally held that
heating something increases its mass (albeit very very slightly)? If
energetic objects are not more massive (real, boy that weighs a lot mass)
then what happens to the famous mass energy equivalence expressed by that
famous equation?

I'm only a layman. I'm just interested. I don't have an axe to grind and I'm
not trying to prove or disprove anybody famous or otherwise right or wrong.
I just can't sleep nights until I know if very fast objects are heavier than
slow ones.

Thanks.

Ian

"Ian Bland" wrote in message
...
"Joe Fischer" wrote in message
...
On Sun, 26 Oct 2003 "Ian Bland" wrote:

"Pmb" wrote:
For many years now I've requested proof of these baseless claims that
the
term 'mass' always refers to 'rest mass' yet nobody is willing to
prove
it. [snip]

So, a simple question. If I accelerate some particles (type doesn't
matter)
to just below c in a particle accelerator, situated somewhere on earth,
whose weight can be measured to astonishing accuracy because it is
mounted
on my patent Astonishingly Accurate Very Large Spring Balance, does it
(the
whole system) become heavier?
Ian

Since motion is relative, it should be acceptable to
consider any object to be "at rest" and the other object moving.

So, sure, when the electrons get going close to c, the
accelerator gets so heavy, it sinks into the ground, never
to be seen again. :-)

That is an incorrect assumption. The worlds most powerfull particle
accelerator couldn't accelerate any proton to such a speed as to weigh as
much as a paper clip. Never mind making it so heavy as to sink into the
ground.

Instead of making comments like this why don't you simply do a calculation
fischer? I've explained how to do it. Give it a try.

I give up

It seems a simple enough question; does mass increase as velocity does?

The correct approach to answering this question if first to define mass.
Once the term is defined then the answer to your question follows. And this
is rather simple.

Definition #1: Define a quantity 'm' is defined such that mv is conserved
where v = coordinate velocity
Definition #2: Define a quantity 'M' is defined such that MU is conserved
where U = 4-velocity

It then follows that m depends on speed and M does not.

fischer and a few others claim that you can't call 'm' mass and that you
must call 'M' mass. They claim that this opinion is the only opinion that
makes sense. That's a rather silly view to hold.

If the "mass" being piled on at high speed isn't really massive, ...

'really' is not a term that can be used in physics unless to define a
criteria to establish what to call 'real and what not to call 'real' and
that's pretty ambiguous. All you end up doing is saying that some things go
in drawer X and other things go in drawed Y.

It's "resistance to acceleration" perhaps, but it's not even
really that, since apparently nothing intrinsic to whatever is zooming
along
at high speed has actually changed.

Mass was an intrinsic property of an object in Newtonian mechanics. It is no
longer an intrisic property in relativistic mechanics - depending on how you
define it. It's like the rate at which a clock ticks - That is a constant in
Newtonian mechanics but not in relativistic mechanics. same thing with
length - objects contract in th direction of motion. I have a feeling that
fischer does not understand that part of relativity. At one time fischer
made a comment to the effect that engineers don't have to take these things
into account when they've designed rockets etc. so we're being unreasonable
for discussing them. For example: He wanted me to calculate the mass
increase in an asteroid. The increase amounted to a few grams out of
millions of tons. That was cause for fischer to claim that mass increase is
useless.


All one can say is that high speed
objects have one characteristic associated with increased mass; resistance
to acceleration. But they don't weigh any more (as a massive object would)

But they do weight more.

their gravitational pull isn't increased..

It is increased. In fact light, which has no rest mass at all, has a
gravitational pull.

Einstein seemed to think that mass was dependent on velocity.

He was never really consistent on that fact oddly enough. He did associate
mass with energy when it came to a continuous distribution of mass but he
associated mass with rest energy when it came to single particles. However
he didn't apply that definition when the particles were photons - He quite
clearly and consistently stated that light has mass.

I thought he
wrote a paper on the subject. I *thought* he based a relatively famous
theory on this.

He did. In his paper "The Foundation of the General Theory of Relativity",
Einstein wrote

"The special theory of relativity has led to the conclusion that inert mass
is nothing more or less than energy, which finds its complete mathematical
expression in a symmetrical tensor of second rank, the energy-tensor."

But if it *isn't* mass; why then does nuclear binding energy have mass,
real bona fide mass that weighs something, and why is it generally held
that
heating something increases its mass (albeit very very slightly)?

fischer adheres to a definition which relies on a zero momentum frame. Mass
in rest frame is "energy in rest frame"/c^2. When the energy of an object
is increased and its momentum doesn't change then the rest energy does not
change. Thus there is an increase in rest mass.

I'm only a layman. I'm just interested.

All excellant questions!

I don't have an axe to grind and I'm
not trying to prove or disprove anybody famous or otherwise right or
wrong.
I just can't sleep nights until I know if very fast objects are heavier
than
slow ones.

Then you can sleep tonight since it is an incontrovertible fact that a
moving body weighs more.

Pmb

Subject: Relativistic Mass
From: "Pmb"
Date: 10/26/03 2:30 PM US Mountain Standard Time
Message-id:




Definition #1: Define a quantity 'm' is defined such that mv is conserved

Correction, the mass of a free particle m is defined by
m = g_mu_nuP^muP^nu

Definition #2: Define a quantity 'M' is defined such that MU is conserved

Correction, m was already defined above.

It is increased. In fact light, which has no rest mass at all, has a
gravitational pull.

Correction, light that has no mass, but does have energy and momentum which
does contribute to Einsteins field equations in the stress energy tensor.


"The special theory of relativity has led to the conclusion that inert mass
is nothing more or less than energy, which finds its complete mathematical
expression in a symmetrical tensor of second rank, the energy-tensor."

The word mass is qualified in the quote.

Then you can sleep tonight since it is an incontrovertible fact that a
moving body weighs more.

That's a Newtonian description and leaves out the angle at which the light
moves with respect to the planet. Using the same concepts for mass and weight
that you are using an object actually wieghs less when the motion is virticle
than while still. See section 3 of chapter 10.
http://www.geocities.com/zcphysicsms/chap10.htm#BM10_3

Ian Bland:

It seems a simple enough question; does mass increase as velocity does?

Unequivocally, no. The confusion caused by "relativistic mass" is
precisely the reason for not using it to mean "mass".

If the "mass" being piled on at high speed isn't really massive, then
it isn't mass, is it? It's "resistance to acceleration" perhaps, but
it's not even really that, since apparently nothing intrinsic to whatever
is zooming along at high speed has actually changed.

Right. Electrons differ from muons by their masses. Electrons do
not become muons by virtue of changing frames.

All one can say is that high speed
objects have one characteristic associated with increased mass; resistance
to acceleration. But they don't weigh any more (as a massive object would)
their gravitational pull isn't increased (as it would if mass had increased)
and, er, they haven't got any more mass at all.

It isn't mass then is it?

No, it's kinetic energy. This is exactly analogous to newtonian
physics in which the kinetic energy is (1/2)v^2. No one calls
this kinetic energy a mass increase, so why do it in relativity?
The concept of "relativistic mass" can be useful in very limited
situations, but it's more like vernacular which is peculiar to
a specific situation than a rigorous concept.

[...]

But if it *isn't* mass; why then does nuclear binding energy have mass,
real bona fide mass that weighs something, and why is it generally held that
heating something increases its mass (albeit very very slightly)?

Not to confuse the issue still further, but the binding energy of
stable nucleus is negative, otherwise the nucleus could reach a
lower energy state by falling apart. So, the bindinding energy cannot
be due to the kinetic energy of the nucleons.

If
energetic objects are not more massive (real, boy that weighs a lot mass)
then what happens to the famous mass energy equivalence expressed by that
famous equation?

Nothing happens to it. The equation is:

E^2 = (pc)^2 + (mc^2)^2

or in a form more useful for illustrating the point:


[E^2 - (pc)^2]/c^4 = m^2

That is the definition of the mass. Note that the mass here is always
the same for any object. What differs as a function of velocity are its
total energy E and its momentum p (which is analogous to the newtonian
situation, in which you have a mass m moving at some velocity and
calculate the energy and momentum - the only difference being how
you calculate the energy and momentum).


I'm only a layman. I'm just interested. I don't have an axe to grind and I'm
not trying to prove or disprove anybody famous or otherwise right or wrong.
I just can't sleep nights until I know if very fast objects are heavier than
slow ones.

If you want an answer that you can be certain isn't being given as
a personal opinion held by someone responding to your post to this
newsgroup, see the two physics faqs I referenced in another response.