HDTenEightyP/NetNews huggingface dataset:
From: leb@violet.ccit.arizona.edu (BASEL, LESLIE)
Newsgroups: alt.folklore.science
Subject: Mirror Images
Date: 26 Dec 92 01:54:00 GMT
Distribution: world,local
Organization: University of Arizona
News-Software: VAX/VMS VNEWS 1.41

Hah! I found the time and the article.

Scientific American Dec 1980 (vol 243 iss 6) pps 206 - 228
Mirror Images by David Emil Thomas:

  "Consider, 1st, a puzzling and fundamental question about the plane
mirror.  Why does such a mirror exchange right for left but not up and
down?  In other words, why is it that when a book  is held up to a plane
mirror each letter appears reversed  and the sequence of letters
run from right to left, whereas the order of the lines from the top
of the page to the bottom is unchaned?	This paradox  can be traced
to the confusion  between the handedness of an image and it orientation.
Actually, for an observer facing a plane mirror the directions right
and left are not changed any more than	the directions up and down.
This fact can be demonstrated by comparing a clock face with its image
in a plane mirror.

  "The transparent clock face is particularly useful in that its num-
erals serve to define lateral directions in the plane tangent to the
mirror at its center of curvature.  For example, 11:00 identifies the
direction from the center of the clock face to the numeral 11.	Simi-
larly, 5:30 identifies the direction from the center of the clock to
the point midway between the numerals 5 and 6.	(It is assumed through-
out this discussion that the observer and the object  are close to
the axis of the mirror the line through the mirror's center of curv-
ature that is pendicular to the tangent plane at that point).

  "This coordinate system provides a means of explicitly describing
the elusive distinction between handedness and orientation.  The
numerals in the plane-mirror image of a transparent clock face run
counterclockwise order, just as the numerals viewed through the back
of the clock face do.  Comparing the real object with the image 'face-
to-face' then, it is apparent that neither the direction 9:00 (right)
nor 3:00 (left) nor 12:00 (top) nor 6:00 (bottom) is changed by the
plane mirror.  Because orientation is not changed along any direction
in the plane of the mirror, the numerals in the image of a clock face
run in counterclockwise sequence.  But plane mirrors (and all other
mirrors) do invert the directions forward and backward: Whereas the
actual clock's front faces away from the observer, the image clock's
front faces toward the observer.  This single inversion  creates
an image with reversed handedness. It is for the same reason that
the image of a right handed glove is left handed."

[There follows more of the explanation with many pictures and
diagrams that lead through many different types of mirrors and
various inversions, reversions, and distortions that may be of
interest but I am not talented enough to convey in ascii chars]

I hope that this clears up the discussion.

Rodger Coghlan

PS All typos are mine and not in the original
PpS ditto any poorfeading problems (sigh)
Newsgroups: alt.folklore.science
From: billn@hpcvaac.cv.hp.com (bill nelson)
Subject: Re: Hot Water flow mystery.
Organization: Hewlett-Packard Company, Corvallis, Oregon USA
Date: Sat, 26 Dec 1992 11:40:05 GMT

dannyb@panix.com (Daniel Burstein) writes:
: regarding the questions about why the hot water from the tap would at firs
: flow quite rapidly, then reduce in intensity, while the cold water didn't...
:   
: There are a number of things going on.
: 
: 1) There may be different piping systems, particularly if the building has
: undergone renovation.  While steel pipes have very little pressure related
: expansion (at least with thepressures normally encountered), plastic
: piping will have somewhat more.

In either one, the flow would increase as the pipes heated. This is not
what is happening.

: 2) There may be air in the system.  This will definitely compress under
: pressure, thus giving extra push when a valve is first opened.

Why would this make any difference? The pressure remains the same, air
or no air. Also, the change is not that rapid. No change occurs until
the water coming out of the faucet starts to get hot.

: 3) The water heater tank may have a bladder or similar expandable
: container in it.

No - they have no such thing. Pressure tanks on a well system have such
a bladder. However, this is not the cause - once again, the change is
not immediate.

: 4) there may be an extra "booster" pump on the heated water line which
: added a bit of pressure which gave an extra push when the water is first
: turned on.

Why? What would be the purpose? Also, no immediate change.

Trust Occam's razor. It is a case of the washer in the faucet expanding as
it heats - thus reducing the flow.

Bill
From: srcriro@chv.lincoln.cri.nz
Newsgroups: alt.folklore.science
Subject: Re: Perceiving "Neon/Florescent" Colors
Date: 22 Dec 92 23:28:09 GMT
Organization: Canty Agriculture & Science Centre

Apropo:My understanding is that these colours actively floresce in the 
presence of
the UV in natural light, you can't expect to reproduce their properties with
any mix of conventional dyes.
 
I believe similar stuff is put in washing powder to make your wash "whiter"
and "brighter" [than what one wonders...].
 
--
Geoff, Sysop Equinox (equinox.gen.nz) +64 (3) 3854406 [4 Lines]
                               Voice: +64 (3) 3852101
        "Hi. You have just entered the fourth dimension. Small isn't it?"


......brighter than the same washing WITHOUT the optical brighteners.

Tootle pip.......Ian O

aka Ian Orchard, SCItest Lab, Industrial Research Ltd, ChCh NZ
From: oahvenla@snakemail.hut.fi (Osma Ahvenlampi)
Newsgroups: alt.folklore.science
Subject: Re: Perceiving "Neon/Florescent" Colors
Date: 22 Dec 92 20:45:27 GMT
Organization: Helsinki University of Technology, Finland
Distribution: inet
NNTP-Posting-Host: lk-hp-4.hut.fi
In-reply-to: pstryjew@colsun.Central.Sun.COM's message of 21 Dec 92 21:56:08 GMT

In article <1h5ehoINN707@cronkite.Central.Sun.COM> pstryjew@colsun.Central.Sun.COM (Pete Stryjewski) writes:

>How does the human eye perceive "Neon/Florescent" color (i.e. hot pink, blaze
>orange, the Crayola Florescent Crayons)?  

>I assume it has something to do with absorption of UV light, but where in the
>spectrum do they reside?  Are they hiding in the "visible" spectrum?  How are
>the dyes made, I can't make them with additive mixing of the three primaries.

>I haven't been able to get an answer to this question for years (well, I just
>asked a couple people, that is the extent of my research).

When a high energy foton, such as a UV wavelenght foton hits an electron in an
atom, the electron usually absorbs at least a part of the fotons energy, by
taking a "higher" orbit around the nucleus. Usually, this high energy state
doesn't last very long, and the electron drops back into it's normal orbit,
releasing the just absorbed energy. If the amount of absorbed energy was in the
visible wavelenght spectrum, you can see the foton emitted.
So, the fluorescent colors look brighter than they should in the lighting,
because they show not only the visible light falling on them, but also drop
a portion of the UV lights energy level to a visible wavelenght.
If the above sounds difficult, remember that energy and wavelenght are just
about the same thing. The higher the frequency, ie. the shorter the wavelenght,
the more energy it contains.
--
Osma Ahvenlampi  -  oahvenla@snakemail.hut.fi   * Workstation power for micro-
All my opinions are not necessarily really mine * computer price: Amiga := FUN
Newsgroups: alt.folklore.science
From: pstryjew@colsun.Central.Sun.COM (Pete Stryjewski)
Newsgroups: alt.folklore.science
Subject: Perceiving "Neon/Florescent" Colors
Date: 21 Dec 92 21:56:08 GMT
Reply-To: pstryjew@colsun.Central.Sun.COM
Organization: "Sun Microsystems Computer Corporation, Dallas, TX."
NNTP-Posting-Host: stimpy.central.sun.com


How does the human eye perceive "Neon/Florescent" color (i.e. hot pink, blaze
orange, the Crayola Florescent Crayons)?  

I assume it has something to do with absorption of UV light, but where in the
spectrum do they reside?  Are they hiding in the "visible" spectrum?  How are
the dyes made, I can't make them with additive mixing of the three primaries.

I haven't been able to get an answer to this question for years (well, I just
asked a couple people, that is the extent of my research).

Answers/Ideas?

Pete Stryjewski
pstryjew@colsun.Central.Sun.COM
From: csa09@seq1.keele.ac.uk (Paul Singleton)
Newsgroups: alt.folklore.science
Subject: Re: very cold beer
Date: 22 Dec 92 18:48:48 GMT
Organization: Keele University, England

From article <1992Dec22.053523.19270@dcc.uchile.cl>, by jpasini@cipres.cec.uchile.cl (Pasini Krug Jose Miguel):

> In article [...] mag6@po.CWRU.Edu (Martin A. Gulaian) writes:

>>If you stick a bottle of beer in the freezer and forget about it for
>>a while, but not too long, it will be extremely cold (10 deg F?) but not
>>frozen when you take it out.
>>
>>If you've timed it right, you can pop the top off the bottle and watch
>>as the beer flash-freezes solid in a matter of a seconds. The first time

Isn't this super-cooling?  I remember melting sodium thiosulphate crystals,
then letting it cool (remaining liquid) and "seeding" it with a small
crystal.  Maybe other seeds would work.  This was hobby chemistry for
12-year-olds.  We weren't allowed beer.
----
  __   __    Paul Singleton (Mr)           JANET: paul@uk.ac.keele.cs
 |__) (__    Computer Science Dept.        other: paul@cs.keele.ac.uk
 |  .  __).  Keele University, Newcastle,    tel: +44 (0)782 621111 x7355
             Staffs ST5 5BG, ENGLAND         fax: +44 (0)782 713082
Newsgroups: alt.folklore.science
From: bcadamso@nella9.cc.monash.edu.au (B.C. Adamson)
Subject: Re: Hot Water flow mystery.
Organization: Monash University, Melb., Australia.
Date: Mon, 21 Dec 1992 06:50:59 GMT

vnelson@ccu.umanitoba.ca (Gerald Vernon Nelson) writes:

>In <1992Dec14.214841.4240@dbsun.uucp> check@dbsun.uucp (checkett) writes:

>>I have a question that bothers me every morning. I wake up and go to the john
>>to have a shave and turn on the hot water full blast. Over the next 20-30
>>seconds the water temperature goes from freezing to quite hot as desired. 
>>The problem is that the flow rate of the water drops off as the temp goes up. 
>>If I don't touch the faucet the flow nearly stops. What is happening? 

>When the faucet is closed, the water pressure is at a maximum.
>When you open the faucet, water rushes out because of the high pressure.
>But the pressure drops because youve created a leak, so the flow rate
>drops off.

>Potential is highest when no current flows, as soon as current flows, 
>pressure drops due to internal losses and line losses.
>Works the same with electricity, and air lines.

>Vern Nelson

Funny, I always assumed that the hot water was making parts of the tap
expand and altering the gap that was available for the water to come
through.

Boyd.
From: worden@bouncer.nsc.com (Dennis Worden)
Newsgroups: alt.folklore.science
Subject: Re: More Monty Hall
Date: 22 Dec 92 18:57:41 GMT
Distribution: usa
Organization: National Semiconductor Corporation


 
|> >Monty hasn't given you new information, he has given you a new
|> >question.  At the point where he asks you if you want to switch, the fact
|> >that you had a 33% chance previously doesn't affect you new decision; two
|> >doors, one prize.
|> 
|> The fact that the door which used to be closed is now known to be a loser
|> is new information.  Specifically, if I guessed a goat (probability 2/3),
|> then he's now shown me where the winner is.
|> 
|> 	- kitten

The fact that you now have an open door with a goat behind it does not
change the fact that you have 2 door and 1 prize.  The opening of the
third door only tells you that the prize is not behind that door, it does
not add any information as to where the prize really is.  Or put it another
way, if you consider this new information on the same puzzle, why do you
freeze the probability of the original guess at 33%?  To freeze the original
probabilities at their "pre-new-information" levels means that your are not
using that new information.  The new information would apply equally to all
doors that are left, and adjusts the probability to 50%.  The original
assumption of 33% chance per door was based upon 3 closed doors.  The new
question is which of 2 closed doors has the prize.


-- 
Dennis Worden, not representing $  When the TEAM succeeds, you succeed,
anybody, not even himself, in   $  but when the Team fails, you're FIRED.
any way shape or form.          $  Don't EMAIL me at worden@berlioz.nsc.com
From: shag@aero.org (Robert M. Unverzagt)
Newsgroups: alt.folklore.science
Subject: Re: Two high tides (Was: Full moon and tides)
Date: 21 Dec 1992 17:54:15 GMT
Organization: Organization?  You must be kidding.
NNTP-Posting-Host: aerospace.aero.org

In article <scottj-211292091243@iamac-1.dml.georgetown.edu> scottj@magic.dml.georgetown.edu (John L. Scott) writes:
> The high tide facing the moon is, of course, explained by the gravitational
> pull of the moon.  However, there have been at least two explanations for
> the high tide on the opposite side of the earth:
> 
>    A.  The moon stretches the earth
>    B.  Centrifugal pseudo-force
> 
> So... which is it, A, B, both, or neither?
> 
Neither.  Well, sort of A, I guess -- it depends what you
mean by "strethes the earth".  Bad ascii graphics follow:

			       _______
                              /       \
          __                 /         \
         /  \                A    B    C
         \__/                \         /
         moon	              \_______/
			        earth

Points A, B, and C all experience some amount of "pull" from
the moon.  It's easy to see (as you point out above) that
point A is pulled more than B, the center of the earth.  It's
also easy to see from the above diagram that point C feels
less pull than B;  therefore C "rises" relative to B, just as
A does.

Is that what you mean by "stretches the earth"?

Shag


-- 
       Rob Unverzagt        |
  shag@aerospace.aero.org   |   The will to a system is a lack of integrity.
unverzagt@courier2.aero.org |                        - Friedrich Nietzsche 
   18348@rhodes.aero.org    |
Newsgroups: alt.folklore.science
Subject: Re: Perceiving "Neon/Florescent" Colors
From: Geoff@equinox.gen.nz (Geoff Mccaughan)
Date: 22 Dec 92 21:26:38 +1200
Organization: Equinox Networks
X-Newsreader: TIN [version 1.1 PL8]

Pete Stryjewski (pstryjew@colsun.Central.Sun.COM) wrote:

>How does the human eye perceive "Neon/Florescent" color (i.e. hot pink,
blaze
>orange, the Crayola Florescent Crayons)?  

>I assume it has something to do with absorption of UV light, but where in
the
>spectrum do they reside?  Are they hiding in the "visible" spectrum?  How
are
>the dyes made, I can't make them with additive mixing of the three
primaries.

>I haven't been able to get an answer to this question for years (well, I
just
>asked a couple people, that is the extent of my research).

>Answers/Ideas?

My understanding is that these colours actively floresce in the presence of
the UV in natural light, you can't expect to reproduce their properties with
any mix of conventional dyes.

I believe similar stuff is put in washing powder to make your wash "whiter"
and "brighter" [than what one wonders...].

--
Geoff, Sysop Equinox (equinox.gen.nz) +64 (3) 3854406 [4 Lines]
                               Voice: +64 (3) 3852101
        "Hi. You have just entered the fourth dimension. Small isn't it?"
Newsgroups: alt.folklore.science
From: billn@hpcvaac.cv.hp.com (bill nelson)
Subject: Re: very cold beer
Organization: Hewlett-Packard Company, Corvallis, Oregon USA
Date: Sat, 26 Dec 1992 00:23:12 GMT

mag6@po.CWRU.Edu (Martin A. Gulaian) writes:
: 
: Why does the WHOLE beer freeze solid? If the beer is only, say, 20 deg F
: below freezing, how can it absorb all the heat from the freezing ice? To
: rephrase, a beer-sized block of ice would drop a beer-sized glass
: of water a lot more than 20 deg F before melting. Shouldn't the inverse
: apply here? 

I don't think you can really call it a temperature change. It is simply
a state change - from supercooled liquid to ice - both having the same
specific heat.

Bill
Newsgroups: alt.folklore.science
From: mcampbel@cs.ucf.edu (Mike Campbell )
Subject: Re: Non-Relflecting object
Organization: University of Central Florida
Date: Sat, 26 Dec 1992 15:30:55 GMT

carl@SOL1.GPS.CALTECH.EDU (Carl J Lydick) writes:

>In article <schumach.725151168@convex.convex.com>, schumach@convex.com (Richard A. Schumacher) writes:
>>Or, empty space. Once when it was necessary to have a very
>>dark background for some high-speed flash photography, we
>>waited until night and used an open window as the background.
>>It worked great. Of course, it's necessary that there be no
>>light sources or nearby objects (anything is a potential 
>>reflector) visible through the window; what constitutes a 
>>source or "nearby" will depend on your application.

>I'm afraid that "empty space" is anything but.  Were your claim even close to
>accurate, there'd be a lot of astronomers out of business.

Why?
Newsgroups: alt.folklore.science
From: kpapai@rahul.net (Ken Papai)
Subject: Re: very cold beer
Organization: a2i network
Distribution: usa
Date: Wed, 23 Dec 1992 15:21:24 GMT

In <Bzon6v.IyM@chinet.chi.il.us> koziarz@chinet.chi.il.us (Louis Koziarz) 
writes:

>>>>If you've timed it right, you can pop the top off the bottle and watch
>>>>as the beer flash-freezes solid in a matter of a seconds. The first time

>Doesn't the frozen beer/ice expand and break the bottle, or gush out the top?
>Every beer I've left in the freezer had broken in this manner.

That's because you're drinking cheap beer.  Good beer does not break the
glass.  Esp. if you are drinking out of twist-off bottles.  Anyway, beer
should not be frozen, good beer should be enjoyed at a temp. well above 
freezing, esp. depending on the beer.  A good bet for most good beers
is 39 to 46 degrees F.  Just ask the expert.
-- 
Ken Papai <kpapai@rahul.net>
From: koziarz@chinet.chi.il.us (Louis Koziarz)
Subject: Re: very cold beer
Organization: Chinet - Public Access UNIX
Date: Tue, 22 Dec 1992 22:44:54 GMT

>>>If you've timed it right, you can pop the top off the bottle and watch
>>>as the beer flash-freezes solid in a matter of a seconds. The first time

Doesn't the frozen beer/ice expand and break the bottle, or gush out the top?
Every beer I've left in the freezer had broken in this manner.

-- 
Louis Koziarz
koziarz@chinet.chi.il.us

Caught a SIGSEGV - .newsrc trashed
Newsgroups: alt.folklore.science
From: fnord@panix.com (Cliff Heller)
Subject: Re: More Monty Hall
Date: Tue, 22 Dec 1992 17:46:08 GMT
Distribution: usa
Organization: Right Bleedin' Church of Libertine Obfuscatology

In <1992Dec21.214559.22343@berlioz.nsc.com> worden@bouncer.nsc.com (Dennis Worden) writes:



>Now reword the situation a little:
>After Monty opens the door with the goat behind it, he then asks you to
>choose between the remaining two doors, one with the prize, and the other
>with the goat.  You have a 50% chance of picking the correct one (remember,
>the third door does not exist in the wording).  You have a 50% chance
>of picking the correct door here.  You have the same information as before,
>the only change is that instead of asking you to "switch", you are asked
>to "pick from start".  Either way, you have two doors in front of you,
>and one prize.  

WRONG.

I could easily separate you from your money if you think that there is no
new information added.  The fallacy in your reasoning is quite intuitive
and understandable.  It is not, however, based on logical reasoning.

Just because there are two door in front of you, one with the prize, it
does not imply 50/50 probability.


>The fallacy here is assigning the 33% chance from the door Monty opened
>totally to the last door.  The 33% distributes across both door, afterall,
>just because you now know the prize isn't behind one of the doors, doesn't
>tell you where it is.  That 33% chance splits evenly between the remaining
>two doors, and you have 50%.  To believe otherwise is the same as saying
>you approach three doors, one of which is open and has a goat, two of
>which are closed.  Whichever door you pick only has a 33% chance of being
>right, the other door has a 67% chance of being correct.  Now that doesn't
>make any sense does it?

You are making a fool of yourself.
This is a well known problem.

-- 
    / \      Reverend fnord                 | "King Kong died for your sins!"
   /   \     fnord@panix.com                | 
  / <0> \                                   | "Don't just eat a hamburger, 
 /_______\   Church of Obfuscatology, Inc.  |  eat the HELL out of it!"
From: shag@aero.org (Robert M. Unverzagt)
Newsgroups: alt.folklore.science
Subject: Re: mean failure time vs power-to-weight ratio (was: Re: Sig file)
Date: 21 Dec 1992 17:45:28 GMT
Organization: Organization?  You must be kidding.
NNTP-Posting-Host: aerospace.aero.org

In article <pete.724946089@extro.ucc.su.OZ.AU> pete@extro.ucc.su.OZ.AU (Peter Alexander Merel) writes:
> shag@aero.org (Robert M. Unverzagt) writes:
> >In article <1grnvaINN5i7@cat.cis.Brown.EDU> ST201026@brownvm.brown.edu (nathan marsh) writes:
> >> In article <1gqv3tINN6so@news.aero.org>, shag@aero.org (Robert M. Unverzagt)
> >> said:
> >> >He plotted power-to-weight ratio vs. mean time to failure for
> >> >all sorts of things -- alarm clocks, cars, gas turbines,
> >> >Saturn V's, etc. on log-log paper.  You guessed it -- it's a
> >> >line.
> >
> >Right -- higher power-to-weight decreases mean time to failure.  For
> >a "typical" launch vehicle it was something like 4 hours between
> >failures.  You can't do too much about it for rockets -- decrease the
> >power and you don't get enough "oomph" (note the technical jargon),
> >increase the weight and you're in the same boat.  Moral -- expect to
> >lose a Space Shuttle now and then.
> 
> Oh dear; does this mean that we should start to worry about the sun?
> 
Good point -- what's the power-to-mass ratio of the sun, anyway?


-- 
       Rob Unverzagt        |
  shag@aerospace.aero.org   |   The will to a system is a lack of integrity.
unverzagt@courier2.aero.org |                        - Friedrich Nietzsche 
   18348@rhodes.aero.org    |
From: mag6@po.CWRU.Edu (Martin A. Gulaian)
Newsgroups: alt.folklore.science
Subject: very cold beer
Date: 22 Dec 1992 00:39:51 GMT
Organization: Case Western Reserve University, Cleveland, OH (USA)
Reply-To: mag6@po.CWRU.Edu (Martin A. Gulaian)
NNTP-Posting-Host: thor.ins.cwru.edu


If you stick a bottle of beer in the freezer and forget about it for
a while, but not too long, it will be extremely cold (10 deg F?) but not
frozen when you take it out.

If you've timed it right, you can pop the top off the bottle and watch
as the beer flash-freezes solid in a matter of a seconds. The first time
I did it was by mistake and I only noticed when I tipped the bottle to
my lips and nothing came out.

I assume that the pressure in the capped beer bottle depresses the
freezing point of beer the same way that the freezing point of water drops
with increased pressure. When the bottle is uncapped, pressure returns to
normal, the beer finds itself supercooled, and freezes in a hurry, starting
at some tiny bubble maybe.

My question for the net:

Why does the WHOLE beer freeze solid? If the beer is only, say, 20 deg F
below freezing, how can it absorb all the heat from the freezing ice? To
rephrase, a beer-sized block of ice would drop a beer-sized glass
of water a lot more than 20 deg F before melting. Shouldn't the inverse
apply here? 

Does something weird happen to the specific heat of water below its
normal freezing point? Does beer not freeze the same way that water
does?

Or should I just drink my beer at refrigerator temperatures since it tastes
better that way anyway?

*MG
Newsgroups: alt.folklore.science