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Misunderstanding Bateson
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Don1
science forum Guru


Joined: 28 Apr 2005
Posts: 1859

PostPosted: Wed Jun 08, 2005 11:53 am    Post subject: Re: Engineers vs physicists and other scientists Reply with quote

Robert Kolker wrote:
Quote:
Don1 wrote:

The majority of people who comprehend that the force we call weight (w)
is a fundamental variable of physics; due to, and proportional to the
variable acceleration due to gravity at various locations are called
engineers.

Those who think the force we call weight varies due to some other
acceleration are (often} called physicists.

Rest mass is the fundemental quantity, not weight. Weight is a function
of the gravitational field. A body would have mass if it were the only
body in the universe.

Bob Kolker

Oh That's right Bob, I forgot to mention that physicists don't even
think that force is weight, and that they are both fundamental
concepts: They've been taught that "Rest mass" is the fundemental
quantity, not weight, and weight is a function of the gravitational
field.

How would they know that a body would have mass if it were the only
body in the universe. What would that mass be compared to?

Don
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zzbunker@netscape.net
science forum Guru Wannabe


Joined: 30 May 2005
Posts: 284

PostPosted: Wed Jun 08, 2005 11:57 am    Post subject: Re: Engineers vs physicists and other scientists Reply with quote

Don1 wrote:
Quote:
The majority of people who comprehend that the force we call weight (w)
is a fundamental variable of physics; due to, and proportional to the
variable acceleration due to gravity at various locations are called
engineers.

Those who think the force we call weight varies due to some other
acceleration are (often} called physicists.

Emgineers are more called assholes and shithead philosophers
than they are called weight subjects.

Since statistics still show that after
8000 years the vast majority of engineers
are in reality dipshit chemists with the
brains of an Eqyptian, the car of
Texan physicist, and a Lawyer from
Microsoft that is not only a mathematician
rather than a Lawyer, they're actually
a moronic Ebonics San Franciso AT&T Hamitonian Lawyer,
rather than a non-Canadian Lawyer with
a measurable IQ.




Quote:

Don
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Sine Nomine
science forum addict


Joined: 25 May 2005
Posts: 59

PostPosted: Wed Jun 08, 2005 1:01 pm    Post subject: Re: Engineers vs physicists and other scientists Reply with quote

"Don1" <dcshead@charter.net> wrote in message
news:1118238820.096334.264490@f14g2000cwb.googlegroups.com...
Quote:

How would they know that a body would have mass if it were the only
body in the universe. What would that mass be compared to?

Don


Your insight into the Mass problem has lead me to submit your name to NASA
as Lead Mass Director on the Mars Mission for Flight 1 which is scheduled to
leave earth on May 12, 2008 for Mars. You don't have to pack any clothes.
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cacak5
science forum beginner


Joined: 29 Apr 2005
Posts: 4

PostPosted: Wed Jun 08, 2005 1:14 pm    Post subject: Re: ??? Quaternions ??? Reply with quote

I'm not sure how well it translates from spacecraft to aircraft, but
try "Space Vehicle Dynamics and Control" by Bong Wie. Chapter 7,
Rotational Maneuvers and Control, includes lots of good stuff
concerning the use of quaternion feedback with PID like controllers.
See, especially, some of Wie's references to this chapter. I used some
of this stuff and got a very simple and robust controller for
spacecraft attitude control that was much better than using Euler
angles.

MzF

weg22@drexel.edu wrote:
Quote:
Hi all,

I am trying to apply PID control on the yaw, pitch and roll angles of
my aircraft to keep it in a desired orientation. However, this
orientation is for a pitch angle of theta=90 degrees -> GIMBAL LOCK!!
To avoid this, I obviously have to use quaternions. However, my
problem is once I have the aircraft attitude information in quaternion
form, how can I apply PID control to that quaternion in order to keep
the aircraft at a specific attitude (e.g. yaw=0, pitch=90, roll=0
degrees)?

Can I apply the "Derivation of Quaternion Error Angles" and still avoid
gimbal lock (see page 120 of:
www.ae.gatech.edu/~ejohnson/Thesis-repro.pdf for more information)?

Thanks in advance,
-Bill
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Guest






PostPosted: Wed Jun 08, 2005 1:23 pm    Post subject: Re: Now how did we end up with this genius for President? Reply with quote

On Wed, 8 Jun 2005 09:10:39 -0400, "John Gilmer" <gilmer@crosslink.net> wrote:

Quote:
So, what's the problem, then?

You're not expected to understand why it's problematic
when legitimate scientific study is thwarted to protect those
who are damaging the environment, among other things.

Quote:
... to be a jackass...

You keep advertising that about yourself, as if anyone
could possibly wonder.

On Wed, 8 Jun 2005 05:07:48 -0400, "John "Credibility <0" Gilmer" <gilmer@crosslink.net>
wrote:

Quote:
...That Bush holds back federal money for such "research" doesn't prevent
private ("commercially-purchased") research from taking place so long as
other laws and regulations are in place.

No one had claimed otherwise.

Actually, the public can and should fund research
which benefits it. Bush wants to avoid the public
finding out how much damage he's doing to it.

Quote:
... I haven't seen ...

Not where you store your head, no, you wouldn't.

On Tue, 7 Jun 2005 12:40:35 -0400, "John "Credibilty <0" Gilmer" <gilmer@crosslink.net>
wrote:

Quote:
Really? "BIG SCIENCE" works EXACTLY that way.

Commercially-purchased, prefocused 'research' isn't.

I'd tell you to avoid being so naive, if there were any
chance for you to manage that.

The problem is actually the muzzling of scientists who
are warning about the damage being done for profit.

Quote:
... and leet [sic]...

Do you ever post sober?

Quote:
So, what's being SAID is that "W" should permit essentiallly un-restricted
"stem cell" reserach [sic] functed [sic]

I guess you may never even be sober.

Nobody's blathering that crap but you.

Quote:
... being a baby and

If you could mature past that, you'd realize that the articles
I've already provided to you contradict your erroneous
notions rather thoroughly.

If you could grow up even more, you'd not believe that a
fascist traitor would somehow be your nanny.

Quote:
... afternoon
map [sic] ...

That must be when you pass out from your drunken stupor
and form a road hazard.

On Tue, 7 Jun 2005 04:08:54 -0400, "John "Credibility <0" Gilmer" <gilmer@crosslink.net>
wrote:

Quote:
But when public money is spent, the ENTIRE public has a right to participate
in the decision on how to spend the money.

So you should object to the fact that Bush is plundering
the US Treasury to load his own and Cheney's pockets
with their treasonous war profiteering.

Quote:
When what these "scientists and engineers" are saying is that the public
should just hand over the cash and let the "scientists and engineers" decide
what's best for us.

Why do you imagine that? Science doesn't work that way.

You should learn about it, if you ever gain the capacity.

What is being said, were you able to read for comprehension,
is that valid scientific results are being ignored/thwarted by
those who'd prefer to let the citizens come to harm thereby,
since it's profitable to the corrupt in those instances.

Quote:
You believe that the POTUS should NOT use his authority to decide how public
money is spent?

You merely fail to comprehend the fact that the occupying
fascist Bush is _misusing_ that 'authority'.

The difference, significant as it is, eludes you, along with
so much else, as usual.

"...science and technology are crucial building blocks for American
prosperity that have not be adequately managed in the last four years..."

http://scientistsandengineersforchange.org/index.php

On Mon, 6 Jun 2005 12:58:21 -0400, "John "Credibility <0" Gilmer" <gilmer@crosslink.net>
wrote:

Quote:
All that "W" is doing is using his legal authority to affect how public
money is spent.

You go ahead and believe that, if it makes your bedwetting diminish.

Let the competent folks deal with reality.

Quote:
... "pppoliticizing" ...

There you go with your pp problem, again.

"A bipartisan, all-star roster of Nobel Prize winners and former federal science officials
accused the Bush administration Wednesday of politicizing science."

http://www.usatoday.com/tech/news/2004-02-18-bush-scientists_x.htm

On Mon, 06 Jun 2005 14:20:17 GMT, "John "Thoughtless" Tibbs" <jwtibbs@earthlink.net>
wrote:

Quote:
I don'tthink ...
jt

You're afraid to think, even if you had the capacity to do so.
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Don1
science forum Guru


Joined: 28 Apr 2005
Posts: 1859

PostPosted: Wed Jun 08, 2005 1:25 pm    Post subject: Re: Engineers vs physicists and other scientists Reply with quote

Steve Ralph wrote:
Quote:
"Don1" <dcshead@charter.net> wrote in message
news:1118236244.365593.3080@g44g2000cwa.googlegroups.com...
The majority of people who comprehend that the force we call weight (w)
is a fundamental variable of physics;

You are the *only* person I know of who thinks weight is a fundamental
quantity.

SR

I don't think weight is a fundamental quantity numbskull. Weight is a
fundamental variable. It varies in proportion to the variable
acceleration due to gravity.

The only ones who think mass is a fundamental quantity were taught that
by people who don't know any better.

Quote:


due to, and proportional to the
variable acceleration due to gravity at various locations are called
engineers.

Those who think the force we call weight varies due to some other
acceleration are (often} called physicists.

Don

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Don1
science forum Guru


Joined: 28 Apr 2005
Posts: 1859

PostPosted: Wed Jun 08, 2005 1:28 pm    Post subject: Re: Engineers vs physicists and other scientists Reply with quote

zzbunker@netscape.net wrote:
Quote:
Don1 wrote:
The majority of people who comprehend that the force we call weight (w)
is a fundamental variable of physics; due to, and proportional to the
variable acceleration due to gravity at various locations are called
engineers.

Those who think the force we call weight varies due to some other
acceleration are (often} called physicists.

Emgineers are more called assholes and shithead philosophers
than they are called weight subjects.

Since statistics still show that after
8000 years the vast majority of engineers
are in reality dipshit chemists with the
brains of an Eqyptian, the car of
Texan physicist, and a Lawyer from
Microsoft that is not only a mathematician
rather than a Lawyer, they're actually
a moronic Ebonics San Franciso AT&T Hamitonian Lawyer,
rather than a non-Canadian Lawyer with
a measurable IQ.

That shows how much you know.


Don
Quote:




Don
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Don1
science forum Guru


Joined: 28 Apr 2005
Posts: 1859

PostPosted: Wed Jun 08, 2005 1:31 pm    Post subject: Re: Engineers vs physicists and other scientists Reply with quote

jimp@specsol.spam.sux.com wrote:
Quote:
In sci.physics Don1 <dcshead@charter.net> wrote:
The majority of people who comprehend that the force we call weight (w)
is a fundamental variable of physics; due to, and proportional to the
variable acceleration due to gravity at various locations are called
engineers.

Utter nonsense.

Don't you _wish_ it was?


Quote:
Engineers know better; those people are called idiots.

snip babble

--
Jim Pennino

Remove .spam.sux to reply.
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PD
science forum Guru


Joined: 03 May 2005
Posts: 4363

PostPosted: Wed Jun 08, 2005 1:31 pm    Post subject: Re: Engineers vs physicists and other scientists Reply with quote

Don1 wrote:
Quote:
The majority of people who comprehend that the force we call weight (w)
is a fundamental variable of physics; due to, and proportional to the
variable acceleration due to gravity at various locations are called
engineers.

Those who think the force we call weight varies due to some other
acceleration are (often} called physicists.

Don

Mass, the amount of stuff, is what's fundamental to an object.

Weight and force are both descriptive of an *interaction* between two
things, where the two things typically are made of stuff. Weight does
not belong to the object, it belongs to the *pair* of objects.

Acceleration is once more removed, being the *effect* on an object due
to the *interaction* between two objects.

Remember that heirarchy.

PD
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Don Salad
science forum beginner


Joined: 01 Jun 2005
Posts: 5

PostPosted: Wed Jun 08, 2005 1:43 pm    Post subject: Re: Circular logic Reply with quote

Quote:
http://www.ereleases.com/pr/20050314007.html

-> The notion that everything is connected by pi proves that there is
-> one intelligence, not many,

And apparently, I'm the one who has it.

What about HAMMOND?

Quote:
-> So, while most
-> people spend Einstein's birthday remembering the person he was -
-> 'Absolute Intelligence' highlights that Einstein, along with
-> Muhammad, Jesus, and anyone else that ever lived, is actually
-> "still with us."

There's more nutty goodness at the above URL, and at
http://www.prweb.com/releases/2005/6/prweb248113.htm> ("'Women and
men are symbols for the underlying dynamics present in all entities,'
Yardley says. Conservation of the Circle means women and men share the
same relationship as neutrons and protons, alternating galaxies,
planets and stars, earth and sun, water and fire, circles and
hydrogen. One does not exist without the other, except if one is
hiding.") but this margin is too small to contain my mockery thereof.

We need new groups:
alt.religion.proof-of-pi
alt.physics.proof-of-pi
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Eckard Blumschein
science forum Guru Wannabe


Joined: 28 Apr 2005
Posts: 128

PostPosted: Wed Jun 08, 2005 1:55 pm    Post subject: Re: to Dik T. Winter Reply with quote

Being short of time I restrict to a few essentials.

On 6/7/2005 11:53 PM, Dik T. Winter wrote:

Quote:
Cantor's second diagonal argument only works with actually infinite many
numerals of each number. Otherwise the numbers are rational ones. There
is no other possibility of distinction between real and rational numbers.

But there is no distinction in mathematics.

If this would be the case then there was no difference between countable
and uncountable sets. Presumably you are nonetheless correct in that
most mathematicians and their definitions do not exactly comprehend what
makes the reals different from the rationals


Quote:

It is impossible to really calculate with real numbers because real
numbers include infinitely many numerals. Omitting the very property to
be actually infinite changes the real number into a rational one.
There is no way out.

You only do not see it.

If you are claiming to have an alternative, you definitely do not share
the natural meaning of real numbers, see above.


Quote:
I asked you before and ask you again, what is the definition of that
"numerical identification"?

To have an approachable address (house number) consisting of a finite
number of numerals.

Oh. Well, that is, in my opinion, completely uninteresting.

Do not ask for things you consider uninteresting.


Quote:
The required elements are a_n with all n that are included in n->oo
In order to understand this meaning you have to accept Cantor's notion
of (fictitious) actual infinity, quasi looking from outside.

You are again talking completely unmathematical.

Well, mathematicans like you do not (yet) look from outside.

Quote:
But rationals have, [an approachable numerical identity] whether they are embedded
in the reals or not.

I consider this a widespread fallacy.

Quote:
What about embedded rationals, one can not
even quantify a required number of numerals to be included. If one
intends to include the number 1 then one has to add infinitely many
zeroes.

1 = 1.0 = 1.00 = 1.000 = 1.0000 = 1.00000

And now you are making a mistake:

= 1.000...


Quote:
I hesitated telling you that the usual notion of sets is not consistent
with the continuum. On might call it a fictitious set of infinitely many
elements. However, none of these can be isolated. So the original
meaning of a set got lost.

Still not clear. I do think you do not accept set theory.

I disapprove Cantorian set theory. The notion of a set is nonetheless a
reasonable one.


Quote:
I do not think so. Imaginary and complex numbers are likewise originally
based on counting. Your question and my spontaneous reply were a bit too
straightforward. I should add that a foremost important basis of any
number is to represent an isolated element.

Sorry, in mathematics sqrt(-311) is a straightforward representation of
that number. As is pi, e and what you want. And they are isolated
elements.

They are just problems and do not correspond to a completely
approachable numerical solution/representation.


Quote:
E. g. pi can be thought of infinitely many a_n.

Yes? It can be approached arbitrarily close by rationals, so I would think
it is approachable.

I meant 'zugänglich' with approachable and referred to a reasonable
approach. Arbitrarily close is likewise not a fully adequate term
because it is impossible to come close to infinity. Any arbitrarily
chosen number x can be multiplied arbitrarily by any y, and e.g. with
y=10000000, x*y is larger than 2*x.



Quote:
I repeatedly stressed that Cantor's proof is a natural definition of the
reals. His (Meray's) definition is equivalent on condition infinity is
meant literally, not just like 'arbitrarily large'.

But that is not yet the definition.

If so, then the definition is not consistent with the difference between
countable and uncountable sets.

Quote:
I do not even have an idea what Baudet the definition belongs to.

Baudet's definition starts with sets of rationals.
Defines an equivalence relation betwee those sets,

What is his non-equivalence condition?

Quote:
defines addition, multiplication and ordering between the equivalence
classes, and there you are, the reals.

Weierstrass' starts with multi-sets,
i.e. sets where elements can occur more than once. He looks at the finite
sums of the elements of the sets, defines an equivalence relation, etc.,
and there are the reals.

I wonder why Ebbinghaus did not mention such amusing magic.

Quote:

Leibniz's dx has proven to te beyond mediocre efforts to provide a
'sound' basis.

There is no sound basis behind the dx. They are quantities that come out
of thin air without a proper definition.

Berkeley's objection was presumably not valuable.

Prehaps, but apparently Leibniz himself was aware that he could not
properly define 'dx'. At one time he introduced a curve as a polygon
with infinitely many sides with length dv. Actual infinity?

Interesting question.



Quote:
Lawvere & Kock?

Can you please briefly tell me the essence?

I am not yet very far in it, but from what I have gathered until now:
They introduce numbers d != 0 with the property that d^2 = 0. Of
course this violates the law of the excluded middle, but you can get
away with it. They adjoin such number to the reals, and see: all
functions become continuous, and dx and dy are well-defined.

Looks indeed a clever idea. Brouwer realized that tertium non datur is
not valid for infinity. I guess it is also not valid for the genuine (in
the sense of uncountable) reals. Why is such stuff widely unknown?


Quote:
I think your tone is not the best already quite some time.

I beg your pardon for questioning the Holy grail. At least my intention
is always factual, and I still hope for getting understood.

Regards,
Eckard
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Eckard Blumschein
science forum Guru Wannabe


Joined: 28 Apr 2005
Posts: 128

PostPosted: Wed Jun 08, 2005 2:08 pm    Post subject: Re: to Dik T. Winter Reply with quote

Searching for Lawver and Kook (Thank you!) I found the sentence

Euler affirmed that a real should be determined as a ratio between
infinitesimals.

in

http://www.cms.math.ca/Events/summer04/abs/tt.html

Eckard
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Jesse F. Hughes
science forum Guru


Joined: 24 Mar 2005
Posts: 801

PostPosted: Wed Jun 08, 2005 2:25 pm    Post subject: Re: mathematician salaries Reply with quote

"Jesse F. Hughes" <jesse@phiwumbda.org> writes:

Quote:
You could try the archives dept., too, for information about a
dissertation.

Harvard's archives have no works by any Mark Demers.

My faith in mankind (and particularly in Mark Demers) is badly
shaken. I need a good lie-down.

--
Jesse F. Hughes
"Well, if I can get [my proof of FLT accepted], then I hopefully get a
book deal down the road, and maybe I get to go on 'Oprah'."
James Harris, on the rewards of mathematical endeavours.
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JEMebius
science forum Guru Wannabe


Joined: 24 Mar 2005
Posts: 209

PostPosted: Wed Jun 08, 2005 2:55 pm    Post subject: Re: ??? Quaternions ???-- Reply with quote

Hello Bill and Zigoteau,

There exists a vast literature on PID control of quaternion variables;
just look for "quaternion PID control" on your favorite search engine.
Many of the papers in question appeared in journals of the AIAA. One can
obtain paid subscriptions to AIAA journals or otherwise buy separate
articles.

Google Scholar search:
http://www.scholar.google.com/scholar?q=quaternion+PID+control&hl=en&lr=&start=10&sa=N

My thanks for drawing my attention to the Gibbs-Rodrigues representation
of 3D rotations.
I knew about this from Rodrigues's A.D. 1840 article, but never learned
that Gibbs also studied 3D rotations along this path.

Whatever savings in numbers of arithmetical operations one may achieve
by a representation different from the unit quaternion representation,
one will be set back by the effort needed to test if the rotation at
hand is a half-turn, and subsequently handling half-turns separately.
Half-turns are kind of troublemakers in the 3D rotation business; they
often need special treatment.

I prefer the quaternion representation because of its robustness and
freedom from exceptional cases. In practice one even need not normalize
at each time step; deviations from unit norm build up about half a unit
in the least significant decimal place per time step. So with the 18D
precision of Intel floating point arithmetic one will not incur a
single-pixel error on the usual 800x600 resolution until after many
weeks of running a dynamical simulation.

Finally I would like to draw your attention to a paper of mine at arXiv
at URL

http://www.arxiv.org/PS_cache/math/pdf/0501/0501249.pdf

where conversions of 4D rotation matrices into quaternions and vice
versa are treated.

This stuff ie easily specialized to 3D by putting a00 = 1 in the 4D
rotation matrix.
Conversion from quaternions to 3D matrices is of course Euler-Rodrigues;
conversion of 3D rotation matrix to quaternion shows up the trickiness
associated with half-turns.

Good luck and happy flying: Johan E. Mebius



Zigoteau wrote:

Quote:
Hi, Johan and Bill,


I know that Euler angles are widely used, but they are computationally
quite clumsy and have discontinuities starting at 90°. Do you know
about the Gibbs-Rodrigues representation, which is described in:

http://www.arxiv.org/ftp/cs/papers/0104/0104016.pdf

Even if you eventually want Euler angles, the GR representation has a
number of quick algorithms e.g. for combining two rotations in
sequence. When generating a rotation from its Euler angles, the
resulting sequence of GR vectors goes as follows: the origin -> a
coordinate axis -> a coordinate plane (xy, yz or xz) -> all of space.
Extracting the Euler angles just involves retracing your steps.

Cheers,

Zigoteau.


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ošin
science forum Guru


Joined: 05 May 2005
Posts: 408

PostPosted: Wed Jun 08, 2005 3:19 pm    Post subject: Re: Engineers vs physicists and other scientists Reply with quote

Quote:
A "fundamental variable?" Do you even blink when you use those together?
Like saying it's "relatively absolute."

Like when I was a six year old, my father always got a chuckle out my habit
of using the phrase "almost exactly".
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