HDTenEightyP/NetNews huggingface dataset:
From: hedley@metro (Mark Hedley)
Subject: Re: oversampling (was Re: using green marker on CDs)
Organization: Sydney University Computing Service, Sydney, NSW, Australia
Date: Thu, 1 Oct 1992 06:05:44 GMT

From article <2078@sdrc.COM>, by scjones@thor.sdrc.com (Larry Jones):
> In article <HOD.92Sep29175752@amazon.chem.columbia.edu>, hod@amazon.chem.columbia.edu (Hod Greeley) writes:
>> In article <mmaster.2ac79753-e@parnasus.dell.com> mmaster@parnasus.dell.com (Michael Masterson) writes:
>>    Oversampling raises the base frequency of the sampling to a much
>>    higher level than it was before, so that more gradual filters can be
>>    used to ensure that no out of band digital noise gets mixed in with
>>    the analog signal.  if you only sample once, then you have to use very
>>    steep filters, and they're rougher on the end signal than the more
>>    gently sloped filters that are possible with oversampling.
>> 
>> What you're talking about is just raising the sampling frequency, not
>> what I think of as oversampling.  No matter what you do with a CD, you
>> can't change the original sampling rate, so you can't help out your
>> filters by increasing the bandwith.
> 
> Ah, but you can!  The way oversampling works is by sending samples into
> the D to A converter at a higher rate than the original sampling frequency
> (hence OVERsampling).  For 8 times oversampling, you send 7 extra samples
> into the converter for each original sample -- that raises the frequency
> of the digital noise, moving it farther away from the analog signal and
> thus making it easier to filter out.  The tricky question, of course, is
> where do you get the extra samples to feed into the D to A?  There's no
> way to interpolate reasonable values since you don't have sufficient
> information to do so (thank you, Mr. Nyquist), so what to do?  Since the

Wrong!! With Nyquist sampling (which can be assumed for CD) the time domain
can be perfectly reconstructed - it is called sinc interpolation.

> signal could literally have done anything between samples, there's no
> good reason to use any particular value as opposed to any other, so the
> simplest thing to do is just use zeros.

It certainly does matter what is between the samples! If you shift the data
one place then the signal would become your first interpolated value after
each sample - which is obviously nonsense.

See my earlier post.

Mark Hedley
hedley@ee.su.au.oz

Newsgroups: alt.folklore.science
From: steven@syacus.acus.oz.au (Steven Malikoff)
Subject: Re: Metal Foil and Fillings
Organization: ACUS Australian Centre for Unisys Software, Sydney
Date: Tue, 29 Sep 1992 03:31:19 GMT

dmeiklej@gssec.bt.co.uk (David Meiklejohn) writes:
: Why does metal foil coming into contact with your teeth cause pain?
: David.

I've also noticed, for some strange reason, that petrol vapours also
cause a sharp pain in the teeth I have fillings in... Sort of weird,
I can feel it when I fill my car up with petrol at the service station.
   Other volatile solvents don't seem to have any effect (not that I go
around testing which ones would :)  Does anyone else have this problem?

Steve Malikoff.
steven@syacus.acus.oz.au
From: ccuppern@s.psych.uiuc.edu (Cyndi Cuppernell)
Newsgroups: alt.folklore.science
Subject: Diamonds in my floor wax
Date: 3 Oct 92 00:53:55 GMT
Organization: UIUC Department of Psychology


When I purchased some acrylic floor stuff recently (Future brand),
I noticed they had a contest.  They put a "diamond" into every
bottle.  However, the majority of these "diamonds" are made of
acrylic.  A few are real diamonds.  You are supposed to take this
"diamond" to your local jeweler, who can tell you if it is real or
fake, usually for a fee.

So here's my question:

How many different ways are there to distinguish a real diamond
from a fake, acrylic or glass? -- 
                 
         ________________________________
         |                              |
         |          WARNING             |
         |                              |
         |   .sig UNDER CONSTRUCTION    |
         |                              |
         |         PLEASE USE           |
         |       ALTERNATE ROUTE        |
         |                              |
         | (ccuppern@s.psych.uiuc.edu)  |
         |______________________________|
                                           
Organization: School of Computer Science, Carnegie Mellon, Pittsburgh, PA
Newsgroups: alt.folklore.science
Date: Fri,  2 Oct 1992 16:34:15 -0400 
From: "Andrew C. Plotkin" <ap1i+@andrew.cmu.edu>
Subject: Re: Speed of gravity
	<1992Oct2.121831.431@ecc.tased.edu.au>

This question comes up in sci.physics constantly. I do not know GR, but
the accepted answer seems to be the following, more or less:

Gravitational effects move at the speed of light. However, it is true
that (for example) the Earth orbits as if it was always attracted
straight towards the *true* position of the Sun, not the
eight-minutes-delayed position (the position from which we see sunlight
come.) 

Is this not contradictory? Well, no. It comes out of the fact that when
you do calculations in GR, you don't use simple (x,y,z,t) coordinates,
but icky rank-four tensors, which I don't understand. Basically, when
you work out the math for the motion of two *freely falling* bodies, you
get that each feels a force towards the *true* position of the other.
It's as if each body sees the path the other will follow, computes how
it will move, and then predicts where it will be and is attracted to
that position, thus beating the lightspeed delay. This sounds pretty
magical, but apparently it falls out of the math ok. (The path of each
object is determined by the gravity fields, and the gravity fields are
determined by the motions of the objects; so it's almost understandable
how they can cancel this way. Almost. :-)

Of course, this fails miserably for objects that are *not* freely
falling. Imagine that someone attached a long cable to the Sun (using
lots of superglue, I guess) and gave it a sudden short yank, which sent
the Sun whizzing straight up out of the solar system at .5 lightspeed.
We wouldn't notice anything for eight minutes -- during which the Earth
would be apparently attracted in a direction that the Sun has never
actually been. Then the ripples in space-time would reach us -- or, put
another way, the gravitons emitted from the Sun after the yank would
start to reach us. The force felt by the earth would wobble around for a
while. When it settled down, it would again be pointing towards the true
position of the Sun (until someone else yanked on the cable again.)

Clear? Yes? No? Well, learn more GR, and then ask on sci.physics. (I
think this question is going into the FAQ there soon.)

--Z

"And Aholibamah bare Jeush, and Jaalam, and Korah: these were the borogoves..."
From: ross-c@scs.leeds.ac.uk (R Clement)
Newsgroups: alt.folklore.science
Subject: Re: oversampling (was Re: using green marker on CDs)
Date: 30 Sep 92 09:47:39 GMT
Organization: The University of Leeds, School of Computer Studies
Originator: ross-c@csparc12

In article <1992Sep29.213143.6551@rosevax.rosemount.com> grante@aquarius.rosemount.com (Grant Edwards) writes:
>
>Do you interpolate between the two samples read off the disk in order
>to generate the 7 "extra" samples that you are creating to allow you
>to use fewer poles in your output filters?  It wouldn't do any good to
>read a sample, write that to the D/A 8 times, then read the next
>sample and repeat, since the spectrum of the output signal will the
>same, right?

Right. What you describe is add-sample interpolation, the worst realistic
interpolation method I know of. Better is linear interpolation (draw 
straight lines between samples) , polynomial interpolation (fit curves
to the samples). 

What is generally used in CD players etc (I hope!) is an interpolating filter.
Add zeroes to the sample, (e.g. three zeroes per sample to get 4*) and
then filter the result at 1/2 the new (4*) sampling rate.

If the interpolation was perfect, the aliasing noise that would have
started at 22.05khz now starts at 88.2khz. In reality it would not be that
good, but it's still a lot easier to filter off something starting at 
(e.g. 40khz) and leave everything up to 20khz than to filter everything
above 22.05khz and leave the same.

Cheers,

Ross-c

PS: I'm not a comp.dsp guru, I hope everything is correct.
Newsgroups: alt.folklore.science
From: slb22@cunixb.cc.columbia.edu (Seth L. Blumberg)
Subject: Re: Phony SCIFI on TV and in Movies
Reply-To: slb22@cunixb.cc.columbia.edu (Seth L. Blumberg)
Organization: Columbia University
Date: Wed, 30 Sep 1992 16:47:14 GMT

In article <1a2g05INNik@gap.caltech.edu> carl@SOL1.GPS.CALTECH.EDU writes:
>In article <1992Sep26.102000.28905@klaava.Helsinki.FI>, cust_ts@klaava.Helsinki.FI (Tero Sand) writes:
>>>>Er, just what's the difference between a "force field" with high enough
>>>>resolusion (i.e., short enough wavelength) to simulate matter, and matter
>>>>itself?
>>>
>>>The force field does not simulate matter, just the shape.  The colour and 
>>>the rest are supplied by holograms.
>>>
>>
>>I think what Carl meant was '.. as far as energy usage is concerned'.
>
>No, what I meant was, "If you're producing a force field that simulates the
>shape of the matter, and you're doing it at a short enough wavelength to be
>convincing, what's the difference between the force field and actual matter?"
>In particular, it strikes me that you're basically talking about projecting the
>wave function of the matter whose tactile properties you're simulating.  Now,
>maybe you're only projecting the wave function of a thin film of the matter,
>rather than a solid object, and you're giving it rigidity via a coarser "force
>field," but still, I can't see the difference between this alleged fine force
>field and just creating the matter.

Well, that's like saying that you can create hydrogen by beaming the hydrogen
alpha line into space at a sufficient amplitude.  Or by giving a beam of light
an elliptical polarization varying according to the wave function for the
hydrogen atom.

Fundamentally, it depends on how you define a "force field."  If you define a
force field as electromagnetism, you get none of the properties attributed to
it in ST/ST:TNG in particular or SF in general.  If you define it as a
quantum-mechanical node/antinode pattern, you run into serious
reality-checking problems.  If you just wave your hands over it and refuse to
define it, it'll do exactly what you want, but you end up sounding as arrogant
as Humpty Dumpty.  This is what ST:TNG seems to be doing here.
Seth L. Blumberg          | "Once again, fear and superstition triumphed over
slb22@cunixb.columbia.edu |    science and technology."
On CI$: 76460,1666        |        -- Anton Braun Quist, quoting Ed Whitaker
   > No one I know shares my opinions, least of all Columbia University. <
Newsgroups: alt.folklore.science,alt.folklore.urban
From: bzs@ussr.std.com (Barry Shein)
Subject: Re: "Normal" body temperature
Organization: The World
	<1992Sep24.112128.16933@infodev.cam.ac.uk>
	<1992Sep25.194708.11692@cbnewsd.cb.att.com>
	<1992Sep25.214704.5476@news.acns.nwu.edu>
	<1992Sep27.145854.21702@infodev.cam.ac.uk>
	<EACHUS.92Oct1094810@Dr_No.mitre.org>
	<1992Oct1.180749.26047@hubcap.clemson.edu>
Date: Sun, 4 Oct 1992 07:21:56 GMT


The legend I heard was that he used the hottest day somewhere in Italy
for 100 and the coldest day somewhere in Germany for 0.

At any rate, if any of these legends are true it does show the
inherent superiority of Fahrenheit over Celsius for common use since
the former is a scale of human experience (whether body temperature
and cold water or days in summer and winter) which is what most people
want to gauge when they ask the temperature. I have nothing against
scientists and engineers using C, of course, or Kelvin for that
matter, but for common usage F seems more sensible.

Even if the legends aren't true the above is true, since the scale of
0..100 fits the various legends so well.

I suppose next they'll be giving us metric time, 10 hours/day, 100
min/hr, 10 months/year and all that.

--
        -Barry Shein

Software Tool & Die    | bzs@world.std.com          | uunet!world!bzs
Purveyors to the Trade | Voice: 617-739-0202        | Login: 617-739-WRLD
From: rf@cl.cam.ac.uk (Robin Fairbairns)
Newsgroups: alt.folklore.science
Subject: Re: Metal Foil and Fillings
Date: 29 Sep 92 10:40:44 GMT
Reply-To: rf@cl.cam.ac.uk (Robin Fairbairns)
Organization: U of Cambridge, England


In article <1992Sep29.033119.8393@syacus.acus.oz.au>,
steven@syacus.acus.oz.au (Steven Malikoff) writes:
|> dmeiklej@gssec.bt.co.uk (David Meiklejohn) writes:
|> : Why does metal foil coming into contact with your teeth cause pain?
|> : David.
|> 
|> I've also noticed, for some strange reason, that petrol vapours also
|> cause a sharp pain in the teeth I have fillings in... Sort of weird,
|> I can feel it when I fill my car up with petrol at the service station.
|>    Other volatile solvents don't seem to have any effect (not that I go
|> around testing which ones would :)  Does anyone else have this problem?

Maybe it's lead in the petrol (arf arf arf).
--
Robin (dump Brian Kay) Fairbairns                    rf@cl.cam.ac.uk
U of Cambridge Computer Lab, Pembroke St, Cambridge  CB2 3QG, UK
Disclaimer: I'm not as stupid as this, really - it just seemed funny
            at the time I hit the `followup' button
From: egl1@cunixf.cc.columbia.edu (Elizabeth G. Levy)
Newsgroups: alt.folklore.science
Subject: Re: Phony SCIFI on TV and in Movies
Keywords: laser phaser sound wave
Date: 30 Sep 92 20:53:21 GMT
Reply-To: egl1@cunixf.cc.columbia.edu (Elizabeth G. Levy)
Organization: Columbia University

In article <1992Sep30.191335.18118@cs.yale.edu> rescorla@rtnmr.chem.yale.edu (Eric Rescorla) writes:
>In article <1992Sep30.163850.8112@news.columbia.edu> slb22@cunixb.cc.columbia.edu (Seth L. Blumberg) writes:
>>Pardon me if I'm wrong, but doesn't the term "phaser" as currently used refer
>>to a projector of coherent *acoustical* energy? (Sort of the audio equivalent
>>of a laser, in other words.)  I have seen detailed instructions for building
>>these, using a simple high-voltage oscillator circuit and a few (dirt-cheap)
>>piezoelectric transducers....
>That may be true, but Star Trek phasers clearly cannot be acoustical
>in nature, as they work in vacuum.

Space is not a vacuum.  The audible explosions clearly contradict your
hypothesis! :-)


--
"I was trying to figure out which of my friends were hedgehogs, and which
were foxes...."
"Shakespeare wrote _King Lear_, NOT _King Leo_...."
Xref: sparky alt.folklore.science:3665 alt.folklore.urban:24947
From: styri@hal.nta.no (YuNoHoo)
Newsgroups: alt.folklore.science,alt.folklore.urban
Subject: Re: "Normal" body temperature
Date: 6 Oct 92 11:47:15 GMT
Reply-To: styri@nta.no
Organization: Bohemians and Globetrotters, Unlimited

In article <1992Oct5.200833.20539@unixg.ubc.ca>, Derek K. Miller writes:
>
> I think the Celsius scale IS in the scale of human experience - water freezes
> at 0 (important to know for everything from mixing drinks to sticking
> your tongue on metal poles) and boils at 100 (ditto for tea, pasta,
> and to prevent scalding yourself).

I guess this is the right place in this thread to insert the view that
Fahrenheit is more accurate that Celcius.  :-)

---
YuNoHoo	 "Recycled postings'R'us"
From: lasner@watsun.cc.columbia.edu (Charles Lasner)
Newsgroups: alt.folklore.science
Subject: Re: using green marker on CDs
Date: 4 Oct 92 00:30:05 GMT
Reply-To: lasner@watsun.cc.columbia.edu (Charles Lasner)
Organization: Columbia University

In article <1992Oct3.172859.17773@hpcvaac.cv.hp.com> billn@hpcvaac.cv.hp.com (bill nelson) writes:
>bzs@ussr.std.com (Barry Shein) writes:
>: 
>: I am very, very skeptical of this green marker effect.
>: 
>: However, to play the devil's advocate, something I see missing in
>: these experiments which claim identical bit streams is timing. Timing
>: of the bits and how they hit the speakers can be very critical in the
>: quality of the sound perceived, even if the bits when taken as a whole
>: are indistinguishable.
>
>It appears you do not understand compact disc circuitry. The bit stream
>does not get to the speakers. The binary bits (which form discrete
>numbers) are run through a digital to analog converter/filter system.
>This analog signal is then amplified before going to the speakers.

Perhaps another vantage point:

They make separae CD "head" units that send the digital signal out to a 
separate D-A module for further processing.  The D-A module is ignorant
of the source of the bits and is bound by design to reproduce the exact
same thing for an identical bit pattern.  Further, the data stream is
buffered in the processing unit just ahead of the actual D-A convertors.
By their design, they operate as a "FIFO" which effectively means that
data arriving "earlier" is being processed "now" and "eventually" the
data arriving right now will be processed.  The rate the data is processed
at is not determined by the contents of the bits, but is pre-ordained by
the clock design of the processor.  The only requirement is that the
inherent buffer in the FIFO circuits must never be allowed to be totally
empty, because this would imply that there was perhaps no data to process
at the proper time, which would lead to a change: a severe loss of output
at that time.  So, the whole idea is to keep the buffer partially full 
at all times.  Thus, the CD is allowed to be a little "sloppy" and can
in fact jitter because it is a mechanical device.  But on average, it
sends data at the required rate.  Instantaneously there are moments of
too fast and too slow bit sending, but the FIFO is designed for that
very purpose.  It just gets a little fuller or emptier as a consequence
of the moment.  Meanwhile, it clocks out constant frequency of samples
as long as the overal stream keeps coming in time.  The sloppier the
source, the bigger the FIFO's max capability has to be to ensure a
well-clocked output.

Thus, the bits themselves in the digital value sense are the only thing
that matters.  If it is true that a bitstream analysis shows no difference
between the treated and untreated CD's, then there is no basis for the
marker to have made any difference that could be audible.  There is no
point to complicating the measurements by introducing analog-world
measurements or even human-fallible listening tests: if the bits are the
same, nothing has changed.

cjl
From: Mark.OLeary@newcastle.ac.uk (M.D. O'Leary)
Newsgroups: alt.folklore.science
Subject: Re: Solar Flares -> Gas Laser?
Summary: Good 'ole 'Ringworld Engineers'
Date: 29 Sep 92 23:41:33 GMT
Distribution: alt.folklore.science
Organization: University of Newcastle upon Tyne, UK NE1 7RU

In article <Bv1L8t.A4@immd4.informatik.uni-erlangen.de> kabreuer@cip.informatik.uni-erlangen.de (Klaus Breuer) writes:
>
>
>Now, in his book "Engineers of the Ringworld", he describes a ring around
>a star (1 AU distance), lined with a superconducter matrix.
>In his story, the creators of that ring used the matirx to manipulate
>the stars magnetc field and cause it to emit a plasma flare, a few 
>million miles long and travelling in a straight line.
>The flare would stretch and turn into a violet laser, emitting a short
>burst, about 10km in diameter.
>
>a) CAN a ring-shaped conducter manipulate a star's magnetic field in
>such a way, can he furthermore guide the resulting plasma flare?

Errr, yes. But I cant give you math for it (though I did once see an article
where it had been worked out as feasable)

>b) How could the flare turn itself into a Gas Laser? Niven usually thinks
>his stories through very well, but I always thought a laser needs 2 mirrors
>to get the light waves in phase...

If you can get a large population of electrons in a high energy excited state 
and then trigger them all to drop down to a lower level, the emitted photons 
will all be in phase. This is how gas lasers work (many years since I had to 
study this though, so a better explanation could doubtless be made)
Summary: no mirrors, it works as stated.

>
>c) What would the energ content be? Enough to vaporize a large asteroid
>(say 3km diameter) in a reasonable period of time?

At least!! A laser with a main sequence *star* as power source!!!!

The *really* amazing thought was pointing this flare away from the ring and 
using it as a combined photon/hydrogen torch *STARDRIVE* to move the
_entire system_.... Wow. (Although I recall that Niven points out the problem 
of the star slipping out of the gravitational sweet spot at the  heart of the 
ring, and so leaving it behind...)

>d) Assuming the above were all possible, could the laser be aimed at any
>direction, or could it only be aimed at the conducter itself?

I suspect that the laser could be aimed with accuracy only close to the ring
surface, but gross positioning ought to be possible in any orientation.

>Klaus Breuer, Rudelsweiher Str. 6b, 8520 Erlangen, Germany

Congrats on reading a great book! I recommend to all the 'Ringworld' books.
Staggering physics, but _feasible_ (if you allow for the manipulation of 100
million x jupiter masses of a material of near-infinite tensile strength...)

Mark
Newsgroups: alt.folklore.science
From: ketil@spurv.ii.uib.no (Ketil M. Malde)
Subject: Re: Speed of gravity
Reply-To: ketil@ii.uib.no
Organization: student of computer science at the University of Bergen, Norway
	<1992Sep30.171546.9136@news.columbia.edu>
Date: 1 Oct 92 00:14:33

In article <1992Sep30.171546.9136@news.columbia.edu> slb22@cunixb.cc.columbia.edu (Seth L. Blumberg) writes:


   But wait a minute...the mass of a black hole is concentrated at the
   singularity, which is necessarily inside the event horizon.  If

You know this for a fact? :-)  

   gravitational field propagation takes place at the speed of light,
   wouldn't that mean we'd never "see" the gravitational pull of the
   black hole? Or are we just getting the graviton flux emitted
   immediately before the mass collapsed to form a singularity,
   stretched out until the end of time by the good offices of general
   relativity?

   I'm confused....

Me too.  But: couldn't the black hole be somewhat like the (dirac)
delta fuction, i.e. be zero everywhere except in one point, and still
have an integral?

I must disclaim that I don't have the slightest idea of what I'm
talking about, though.

--
 = Ketil Malde                     In real life:  ketil@ii.uib.no =
 = Nuke the whales!                    Honk if you love unicorns! =
Newsgroups: alt.folklore.science,alt.folklore.urban