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On Sep 21, 3:07*am, J G Miller wrote:
On Sun, 20 Sep 2009 13:37:49 +0100, The Natural Philosopher wrote:
What is ACTUALLY happening is anybodies guess.

How then, are they ever going to plot a course for the mission to Mars?

Why do you think they had to fake the moon landings ;-)

MBQ

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On Sun, 20 Sep 2009 21:22:33 +0100, Paul Martin
wrote:

In article ,
Bill Wright wrote:

It's been a lovely few days. We call it an 'Indian Summer' when it's nice at
this time of year. The sky is blue, there is very little wind, and the fruit
trees are laden with nature's bounteous harvest.

It is also normal that the good weather breaks shortly after the equinox.

And that good weather never occurs in the school holidays.

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"Stuart Noble" wrote in message
om...

This thread interests me, not because I understand a bloody word of it,
but because people with degrees in the subject end up squabbling over what
appear to be fundamentals. Is that the nature of the beast maybe?
So far we seem to have graduates from Imperial College and York, but I may
have missed some. Any chance of the others combatants declaring their
credentials? Not as a dick waving exercise, but to give people like me an
insight into the extent to which experts can disagree.

There is no disagreement with the fundamental laws or the equations
governing them (well not in this thread).
There are a group who think the equations are universal and a group that
think they are not.
So far the group that don't think they are universal have posted stuff that
the "universal" group can't or won't explain. other than to state they are
universal so must apply.

There are a lot of scientists and mathematicians trying to produce a
universal model ATM, the latest attempt is called string theory. They
wouldn't be doing this if the others were universal would they?
What the "universal" group are saying is that the people working on string
theory aren't as clever as they are as the existing maths is universal.

To see why some think they are not universal have a look at
http://www.superstringtheory.com/index.html and then decide for yourself if
you can apply E=mc2 everywhere and interchange mass for energy at a whim.

You will notice that at least one problem they are working on is the fact
that relativity tends not to work unless you ignore the effect of gravity
(http://www.superstringtheory.com/basics/basic3.html). Something you can't
do in the real world even if you are TNP.
The reality is that this is not an argument between experts at all.

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In article , Norman Wells
wrote:
The Natural Philosopher wrote:

However most scientists even today working outside the field of
physics don't have more than a hazy understanding of relativity, so
you find plenty of folks who think like Norman, that relativity
doesn't apply outside of nuclear situations. Not that he is in any
sense a scientist, or scientifically trained.

Nevertheless, it does.

No it doesn't except where mass and energy are actually interconverted,
which does not happen as a matter of normal physical operations which
just effect energy-energy conversions.

As 'Natural Philosopher' has been trying to explain to you: According to
general relativity mass and energy are simply two ways to observe the same
fundamental property. So if any system gains energy it also gains mass. if
you disagree with that you are rejecting one of the axioms of general
relativity.

Been some years since I read it, but if you doubt this, go and read
'Gravitation' by Misner, Thorne and Wheeler. If you can cope with the maths
it should explain it to you. IIRC The smaller book by Berry also dealt with
this, but I can't recall as it was ages ago I read that as well.

You say that if I raise a lump of lead against the force of gravity, it
gains potential energy and therefore mass. Tell me, what mass has been
created, not its quantity but its nature. Is it electrons, neutrons,
protons, complete atoms or what? If it's complete atoms of lead, please
tell me how the energy knows to create atoms of lead, ie each with 82
protons, 122 neutrons and 82 electrons, rather than any other atoms. If
it's other atoms, is it not the case that sufficient raises and
lowerings of the block will eventually change its chemical composition?

Actually it is that every atom, electron, or other 'particle' in the system
tends to gain intertial mass by an amount that sums to the total increase
in energy of the system when you take the c-squared factor into account.

This is linked to effects like atomic clocks based on level transitions
altering their output. which are easily measured these days if you have the
kit and have a clue. So yes, people have measured this via application of
general relativity, and measured the effect on the atoms and molecules.
Look up the papers in the journals if you want to know, rather than refuse
to accept ot.

I can't help it if you don't understand all this or refuse to accept it,
though. Afraid that's your problem, not one for physics. So far as I know,
you aren't a university academic mis-teaching poor students and confusing
them about this. So it is none of my concern if you refuse to accept what
'Natural Philosopher' keeps trying - remarkably patiently - to tell you.
:-)

BTW A distinction I think may have got missed earler was between fission
and chain-reaction/stimulated fission. Yes, 'natural' decays like those
that generate radon naturally are, indeed, 'fission'. But an engineered
reactor or bomb tends to also exploit other effects that stimulate fission.
e.g. a chain reaction. And no, that doesn't mean it has to explode. To
understand why, feel free to learn some Nuclear Physics. :-)

That's my 2p worth. I'll get back to doing something useful. ;-

Slainte,

Jim

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On Mon, 21 Sep 2009 13:29:33 +0100, John Rumm wrote:

however the relativistic difference in mass (approx 1x10^-16 kg), is
dwarfed by the effects of the variation in gravitational field caused by
the 1m height differential, so the experiment is fatally flawed before
you begin.

Which is greater in effect on the balance loads at a difference of 1 m high --
the gravitational field difference or the atmospheric buoyancy?

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Norman Wells wrote:
John Rumm wrote:
Norman Wells wrote:

To test that, it's vital to have a definition of 'mass', isn't it?

You see, according to the definition in Chambers Dictionary of
Science and Technology, mass is defined as 'the quantity of matter
in a body'. That must mean that it's a direct measure of the number
of atoms the body contains, since all matter is composed of atoms.
From that it follows that, however hot any amount of something is,
it has exactly the same mass as it always had, because it always
contains the same number of atoms.

Relating the mass simply to the number of atoms would seem to preclude
any gain is mass with velocity (something intrinsically linked with
time dilation), and time dilation is something that has been
observed. Mass it seems is not as "fixed" as classical physics would
have us believe.

If you're going to talk about mass, as you have, you have to know what
it means, not say in Humpty Dumpty fashion "it means just what I choose
it to mean - neither more nor less".

The very point I made to you.

So, what is mass? What is your definition?


The property of an object that leads to its inertia.

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Stuart Noble wrote:
Norman Wells wrote:
John Rumm wrote:
Norman Wells wrote:

To test that, it's vital to have a definition of 'mass', isn't it?

You see, according to the definition in Chambers Dictionary of
Science and Technology, mass is defined as 'the quantity of matter
in a body'. That must mean that it's a direct measure of the number
of atoms the body contains, since all matter is composed of atoms.
From that it follows that, however hot any amount of something is,
it has exactly the same mass as it always had, because it always
contains the same number of atoms.

Relating the mass simply to the number of atoms would seem to preclude
any gain is mass with velocity (something intrinsically linked with
time dilation), and time dilation is something that has been
observed. Mass it seems is not as "fixed" as classical physics would
have us believe.

If you're going to talk about mass, as you have, you have to know what
it means, not say in Humpty Dumpty fashion "it means just what I
choose it to mean - neither more nor less".

So, what is mass? What is your definition?


This thread interests me, not because I understand a bloody word of it,
but because people with degrees in the subject end up squabbling over
what appear to be fundamentals. Is that the nature of the beast maybe?
So far we seem to have graduates from Imperial College and York, but I
may have missed some. Any chance of the others combatants declaring
their credentials? Not as a dick waving exercise, but to give people
like me an insight into the extent to which experts can disagree.

Engineering, Cambridge.

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Bambleweeny57 wrote:
On Mon, 21 Sep 2009 11:58:51 +0000, Stuart Noble wrote:

This thread interests me, not because I understand a bloody word of it,
but because people with degrees in the subject end up squabbling over
what appear to be fundamentals. Is that the nature of the beast maybe?
So far we seem to have graduates from Imperial College and York, but I
may have missed some. Any chance of the others combatants declaring
their credentials? Not as a dick waving exercise, but to give people
like me an insight into the extent to which experts can disagree.

The politest description of much of this thread might be Newtonian v.
Einsteinian physics.

Newtonian physics is good for about 99.99% of what we observe & do as
humans.

Einsteinian physics starts to "kick in" at the extremes.

No, it kicks in everywhere. Its just the two worldviews converge at
small scale low energy events.

Newton is a good approximation to Einstein, for small energies.

Much of the
physics in this area is still theoretical & difficult to fully grasp with
a strong mathematical background and this is the reason for "discussions"
amongst scientists. Significant sums of money are going into test these
theories with things like the LIGO gravity wave detector and the Large
Hadron Collider.

This is where I duck ;)


That's not really about relativity much though. That's about fine
structu Not how it behaves in a gravitational field.

BW

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brightside S9 wrote:
On Sun, 20 Sep 2009 18:56:58 +0100, "Norman Wells"
wrote:


Look, his formula can be used to calculate the energy that could
theoretically be released from a certain mass, or to calculate the
mass that could be formed from a certain amount of energy. And you
can do that with any mass or any amount of energy at any time. But
those calculations only have any significance or relevance if what
you're doing is actually converting mass into energy or vice versa.
And mass is not actually converted into energy on earth in any
processes except nuclear reactions and radioactive decay, whatever
you may think.

No you forgot chemical reactions. However because the change in mass
is so small and inperceptible, chemistry has aworkable law of
"Conservation of Mass", which is confusing *you*.

Common example given in physics text books is the explosion of 1kg of
dynamite. This results in a mass loss of about 0.6nkg and energy
release of 5.4MJ. So for chemistry the mass loss is *imperceptible*
but the energy release is obvious.

That's circular. The writers have assumed that e=mc^2 applies, calculated a
spurious result in a case where it clearly doesn't actually apply, and
concluded that chemical reactions therefore obey the formula.

Isn't it convenient that in all of these cases where e=mc^2 is erroneously
applied, the change of mass they say occurs can't actually be demonstrated
because it's always so 'imperciptibly small'?

If you consulted a _chemistry_ text book it would doubtless say that there
is no loss of mass at all, the energy coming not from destruction of matter,
which would be required for mass loss, but from the chemical reactions in
which compounds of high chemical energy combine to form compounds of lower
intrinsic energy.

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Stuart Noble wrote:
Norman Wells wrote:
John Rumm wrote:
Norman Wells wrote:

To test that, it's vital to have a definition of 'mass', isn't it?

You see, according to the definition in Chambers Dictionary of
Science and Technology, mass is defined as 'the quantity of matter
in a body'. That must mean that it's a direct measure of the number
of atoms the body contains, since all matter is composed of atoms.
From that it follows that, however hot any amount of something is,
it has exactly the same mass as it always had, because it always
contains the same number of atoms.

Relating the mass simply to the number of atoms would seem to
preclude any gain is mass with velocity (something intrinsically
linked with time dilation), and time dilation is something that has
been observed. Mass it seems is not as "fixed" as classical physics
would have us believe.

If you're going to talk about mass, as you have, you have to know
what it means, not say in Humpty Dumpty fashion "it means just what
I choose it to mean - neither more nor less".

So, what is mass? What is your definition?


This thread interests me, not because I understand a bloody word of
it, but because people with degrees in the subject end up squabbling
over what appear to be fundamentals.

I agree. It should be so simple. But what can you do if people use words
to mean whatever they want them to, and fail to define their terms even when
pressed?

Is that the nature of the beast maybe?

No, just the standard of the participants. Some, like me, want to clarify
issues. Others want to obscure them.