T.R | Title | User | Personal Name | Date | Lines |
---|
481.1 | Or am I missing the point? | CLARID::PETERS | E Unibus Plurum | Fri Feb 19 1988 17:35 | 11 |
| > Given 2 points A and B situated at equidistance from each other,
> how can I move A without B noticing it ?
What are you talking about Roger? How could points NOT be the same distance
from each other?
How can points notice each other?
Is this a riddle? If you give us more clues you may get more answers.
Steve
|
481.2 | | HLDG02::KEW | Tea break over, back on your heads | Fri Feb 19 1988 18:01 | 3 |
| DYO780::BRAIN_BOGGLERS ??
kp7 etc etc
|
481.3 | | SUNSIP::LIRON | | Mon Feb 22 1988 10:03 | 7 |
| re .1
I read the joke on .0 in a book the other day, and thought
it was extremely funny; but then I'm known to have a strange
sense of humour at times. Oh well, forget it.
roger
|
481.4 | in another theorem, far, far away | PASTIS::MONAHAN | humanity is a trojan horse | Mon Feb 22 1988 17:06 | 4 |
| I think the two points have to form an equilateral triangle in
n-space. Then if you subject them to a gravitational field for a moment
they bend, even though they are still noticing each other. (Every
couple in a field has its moment).
|
481.5 | and farther afield still... | LEZAH::BOBBITT | is it soup yet? | Mon Feb 22 1988 17:15 | 23 |
| well, in order for you to move A without B noticing you can:
distract B while a lovely new point C wanders past in naughty
underthings.
wave huge quantities of cash at B or otherwise assault B's senses
with high pressure sales techniques.
have A tell B to close its eyes and count to 20 million, thus allowing
it to sneak off peacably and be back prior to B's completing the
count.
fold the plane on which they exist at the same rate A moves, so
if A and B can only see on that plane, B will not see A move if
it is folded in particular directions with respect to A's motion.
Have a nuclear bomb create a superb diversionary tactic.
ps: I love the "every couple in a field has its moment..."
-Jody
|
481.6 | | TERZA::ZANE | a little mystery never hurt anybody | Mon Feb 22 1988 17:37 | 24 |
|
Easy.
If we assume that B is always noticing A, then all A has to do is to
move in a circle around B. B will never notice that A is moving since
B is always noticing A and will move to keep noticing A.
If we assume B is not noticing A, then A can move anywhere, anytime
and the question becomes moot.
QED.
Terza
P.S.-Actually, the first would still be true if B only noticed A some
of the time. It would have to find A first to be able to notice if
A moved or not. If there were no other point of reference, and none
was provided in the original question, then B wouldn't be able to
determine whether A had moved or not.
|
481.7 | Outta Site | VAXWRK::SIMON | Hugs Welcome Anytime! | Mon Feb 22 1988 18:21 | 4 |
| Re .0
How about moving A while it's dark.
|
481.8 | How intelligent is point B? | GRNDAD::STONE | Roy | Mon Feb 22 1988 23:30 | 7 |
| If points A and B are on the same piece of paper, you can move the
paper (which moves point A) but to point B it will always appear
to be in the same place. If it is also required that point B remain
in the same place which A moves, simply rotate the paper about point
B.
Everything is relative, right Cousin?
|
481.9 | ... Are all things connected? ... | CURIUS::CIUFFINI | If my Personal Name were a song, it | Tue Feb 23 1988 14:36 | 8 |
|
Actually, 481.0 may be more related to the JEC process than to
Geometry, Brain_bogglers, Puzzles, etc..
:-)
jc
p.s. Of course, it may be more related to itself than anything other!
|
481.10 | yo-yo | RAVEN1::MKENNEDY | Eschew sesquipedalianism! | Wed Feb 24 1988 00:12 | 5 |
| A is a point; hence, subtends no angle. Therefore A can move anywhere
along the line A-B without B's noticing it.
Moffatt Kennedy
Greenvile, SC
|
481.11 | Lets make this a bit more personal | PASTIS::MONAHAN | humanity is a trojan horse | Wed Feb 24 1988 10:57 | 3 |
| But A is always along the line A-B anyway.... Maybe we need to
provide Betty with a compass so that she can work out what direction to
go to find Andy.
|
481.12 | Minor point | GLIVET::RECKARD | Jon Reckard, 381-0878, ZKO3-2T20 | Wed Feb 24 1988 13:32 | 5 |
| Sorry, I think it's pointless to try and refer to A and B as Andy and
Betty. Andy and Betty comprise many points, subtending many inherent angles.
The attempt is poignant, but provides too many red-herring points of view.
Before we get to the point of no return, I think we need to clarify:
Does B have the capacity to notice?
|
481.13 | Linear or Polar coordinates? | CLARID::PETERS | E Unibus Plurum | Wed Feb 24 1988 14:30 | 14 |
| > Given 2 points A and B situated at equidistance from each other,
> how can I move A without B noticing it ?
OK, so this is getting serious. I'm still having trouble with the idea that it
is mere chance that A and B are the same distance from each other. My Euclidean
space does not allow for A to be nearer to B than B is to A.
If you have some other dimensions to play with that allow you to bend the rules
then chances are you can move A at will, and B will be so confused it won't
know where to look, and so won't notice that A has gone walkabout.
I think this is a trick question. Roger, are you there?
Steve
|
481.14 | | SUNSIP::LIRON | | Wed Feb 24 1988 17:12 | 8 |
| Thanks for all the suggestions. It's good to see that there still
exist people who are stimulated by the mathematics (instead of
wasting their time in futile pastimes).
Now remember that A and B are both inside a circle C with radius r;
in what direction do you stroke C to make sure he becomes vicious ?
roger
|
481.15 | viscous circles indeed | LEZAH::BOBBITT | is it soup yet? | Wed Feb 24 1988 19:22 | 10 |
| In order to turn C into a vicious circle, you must apply negative
behavior modification techniques in the -x direction. As the pressure
increases, the circle will feel stress and will begin to deform
in the -x direction. C will begin to come around to your way of
thinking (figuratively speaking, of course) within a short period
of time (t). As it spins, this pressure gradually affects
all sides, forming the popular skating move known as the death spiral.
-jody
|
481.16 | | TERZA::ZANE | a little mystery never hurt anybody | Wed Feb 24 1988 21:27 | 10 |
|
Re: .14
Circle C with radius r should only be stroked counterclockwise, that
is, to the left, a sinistra.
Terza
p.s.- But if C becomes vicious, will B finay notice A?
|
481.17 | Careful, now | NEARLY::GOODENOUGH | Jeff Goodenough, IPG Reading UK | Wed Feb 24 1988 21:51 | 7 |
| > Circle C with radius r should only be stroked counterclockwise, that
> is, to the left, a sinistra.
But, of course, if you stroke its bottom it should be to the right
to get the same effect.
Jeff.
|
481.18 | the light at the end of the tunnel | ZFC::DERAMO | Your wish is my .com | Thu Feb 25 1988 00:26 | 4 |
| Hey, do you think we can put as many replies here as in the
word association football topic (396)? (-:
Dan
|
481.19 | go on give us a clue... | LAMHRA::WHORLOW | Progress:=!(going_backwards>coping) | Thu Feb 25 1988 05:24 | 31 |
| G'day from Downunder,
Now if you draw a line from A to B you get A-B. Since a point has
only position and no size, then A-B=0. ergo nothing changes so B
doesn't notice whatever A does. Or maybe
A and B are equidistant in time not space and so that would add
another dimension so to speak....
Howabout if there was a six-foot high brick wall between A & B then A
could even make rude gestures at B and B would not notice.
Now if A was BEFORE a Mirror and B was its reflection in the mirror
then the resultant view of A by A would Always be A which would
make B redundant so he can go home and wouldn't care what happened
to A.
Now if A was on top of B (ie occupying the same point) on one plane
then by lowering A away from a casual observer, there is no way
they would B noticing A go-away.
re.2 if you saw the problem, did you see the answer?
In the immortal words of Tom Sawyer's enemy, Judge Thatcher's son
I holler 'Nuff' Whats the answer? How about a clue??
Derek
|
481.20 | | SUNSIP::LIRON | | Thu Feb 25 1988 12:28 | 11 |
| re .19
Conceptually, I would agree with your approach.
Let me just give you a couple of additional hints:
. Could you specify what is the _longest_ distance
from A to B ?
. The circle (C) should never be confused with the point C
(still going around in naughty underthings)
roger
|
481.21 | That's a different effect | PSTJTT::TABER | Eunuchs are a trademark of AT&T | Thu Feb 25 1988 17:29 | 9 |
| > > Circle C with radius r should only be stroked counterclockwise, that
> > is, to the left, a sinistra.
>
> But, of course, if you stroke its bottom it should be to the right
> to get the same effect.
If you stroke it's bottom, that's "a Sinatra." (It helps if you address
the circle as "honey.")
>>>==>PStJTT
|
481.22 | Noticing = seeing? | MARVIN::KNOWLES | Sliding down the razorblade of life | Tue Mar 01 1988 14:00 | 6 |
| B, being a point, can't have stereoscopic vision; so A can gallivant
directly towards or away from B without fear of detection.
The stroking of the circle is, by definition, tangential.
b
|
481.23 | A more solid solution | LAMHRA::WHORLOW | Progress:=!(going_backwards>coping) | Wed Mar 02 1988 01:53 | 37 |
|
G'day again,
Well now....
All this talk of circles and touching and... enough to take one's
mind off the loci..
Now how about the longest line? Seems to me if there can be a longest
line, then the line length must be finite. Now a plane is not finite,
therefore, arguably, A and B cannot lie on a plane (or a plain or
a steppe); so where can A and B reside?
How about on a sphere? Now the longest line from A to B can be defined
being of length 'Pi times R' where Pi is that well known Mathematician's
friend with a value often given as 22/7 and R is the Radius of the said
sphere.
NOW, if A is 'over the horizon' from B and given that the sphere is not
transparent, then A cannot ever be seen from B so he can go
skinny-dipping or whatever takes his fancy without B noticing.
What d'yer reckon? Am I getting warmer??
Or perhaps (word association here warmer = colder = polar = old problem
about going S then W then N and getting back to start point...)
Howabout if A, being over the horizon from B travels around the sphere
at a constant radius from B ? A will remain 'equidistant from B' regardless
of how far he travels.
Is that close?
Derek
|
481.24 | Pretty close :-) | 43668::GOODENOUGH | Jeff Goodenough, IPG Reading UK | Wed Mar 02 1988 13:59 | 9 |
| > Now how about the longest line? Seems to me if there can be a longest
> line, then the line length must be finite.
How about the largest number? [Eric, please don't type it in this
file :-)]. Same difference.
> NOW, if A is 'over the horizon' from B
Unless A is sitting on top of B, it will always be 'over the horizon'!
|
481.25 | ex | LAMHRA::WHORLOW | Progress:=!(going_backwards>coping) | Fri Mar 04 1988 05:38 | 40 |
| Ah yer ah er G'day,
> > NOW, if A is 'over the horizon' from B
> Unless A is sitting on top of B, it will always be 'over the horizon'!
'Pends how big R is in the sphere and how high B is relative
to the surface of the sphere.... unless.. and here we go off at another
tangent... A is along the tangent and is therefore free to move...
No that would put them back on the same plane.
Suppose B was a point above the sphere, and A ran around the parallel
of latitude (as it were) coincident with the point of contact of
the tangent from B to the sphere? Range of view of
B ~= SQRT(ht of B in feet)+3 miles on the earth (given its not
foggy etc).
If A were to sit on B's back, piggy back style, provided A did not
eat in B's ear, B might be content to carry A around thereby A moving
without B noticing (A is attached to a large helium balloon with
lift = A's mass so B can't feel A sitting on his back)
or suppose A and B were along the centre line of a mobius strip
and A and B start off at a run along the centre (one should always
tear down the dotted line.......rip..... (these jokes??? are getting
worse) they could run forever and B would not notice A had moved
- given that they ran at the same speed and A did not stop at
McDonalds for a McPuke and chips.
Now the title of the last note was "pretty Close" followed by a
smiley face.... Is that a hint I ask myself like 'A & B must be
pretty close' like coincident. or was it merely that we're getting
warmer? I must confess I need the weekend to mull this one over
some more - and as I must go and get my car out of the menders -
I'll see you on Monday (net permitting) - in the meantime how about
a tiny hint (you can send it under plain brown paper cover to me
via e-mail so's not to spoil it for others.. ;-)
Derek
|
481.26 | | YIPPEE::LIRON | | Fri Mar 04 1988 09:59 | 17 |
| re .25 (Derek)
> the tangent from B to the sphere? Range of view of
> B ~= SQRT(ht of B in feet)+3 miles on the earth (given its not
> foggy etc).
This is true to a certain extend, if you know what I mean.
But what if A happens to move faster than the light ?
The theory says there will be a distortion of 1.75; recent research
however indicate that it is more likely to be 21.43.
In that case, supposing B is aged 25 (this is just an example, don't
take it literally), how many revolutions will it take for him to get back
to the age of 8 ?
roger
|
481.27 | | NEARLY::GOODENOUGH | Jeff Goodenough, IPG Reading UK | Mon Mar 07 1988 14:50 | 19 |
| Re: .25
Aha. I'd supposed B to be fixed to the surface of the sphere. If
B is allowed to move, or, heaven forfend, even jump upwards, we
are into a whole new sphere game.
Re: .26
> But what if A happens to move faster than light ?
I believe that A would become infinitely massive, and could no longer
be contained in non-dimensional space. In the resultant explosion
as A metamorphoses into a solid object, B would be blown away and
cease caring whether A was there or not. In the absence of an
observer, A would also cease to exist, plummeting back though time.
I estimate the time it would take to reach the age of 8, as postulated,
would be 7.4 femtoseconds.
Jeff.
|
481.28 | Thanx Uncle Albert | VISA::BIJAOUI | Tomorrow Never Knows | Mon Mar 07 1988 17:06 | 17 |
| � I believe that A would become infinitely massive
You believe well. 'A' mass is:
m0
m = ----------------
___________
/ v�
\ / 1 - -----
V c�
v is the speed of A
c is the speed of light
m0 is naturally the mass of A when v=0.
Oeuf Corse, no wonder how much energy it would take ( E = mc� ).
Pierre
|
481.29 | Aha! Physics! | COMICS::KEY | Confused? You will be | Mon Mar 07 1988 19:28 | 10 |
| Re. .27, .28
Since m0 (initial mass of A at rest) is zero (A is a zero-dimensional
point), its mass will still be zero no matter how close to "c" (the
speed of light, not to be confused with "C", still wearing naughty
underthings) A may venture. Similarly, it would require no energy
at all to reach the speed of light. A is probably therefore already
moving at light speed, and B has merely overlooked the fact.
Andy
|
481.30 | pffft! | INK::KALLIS | A Dhole isn't a political animal. | Mon Mar 07 1988 20:54 | 6 |
| Re .29:
A zero-mass item going at light speed is a photon. Therefore, B
can't see A. If B did, A would be absorbed (hence, destroyed).
Steve Kallis, Jr.
|
481.31 | Is that an e-neutrino or a �-neutrino? | SLTERO::KENAH | My journey begins with my first step | Tue Mar 08 1988 16:09 | 7 |
| >A zero-mass item going at light speed is a photon. Therefore, B
>can't see A. If B did, A would be absorbed (hence, destroyed).
Not necessarily -- A could be a neutrino, which also has a rest mass
of zero. And neutrinos aren't easily absorbed.
andrew
|
481.32 | | PASTIS::MONAHAN | humanity is a trojan horse | Tue Mar 08 1988 22:44 | 13 |
| The original question presupposes that Betty is aware of the
continued existance of Andy. Now photons and neutrinos are only
detectable when they are absorbed like falling into blancmange, or
bounced like Eeyore. Hence Andy cannot be a photon or neutrino.
The fact that Andy also has zero dimensions excludes most other
physical explanations for this awareness, and I think only leaves
telepathy, which means that Andy (and Betty) are sentient beings, which
justifies the personalisation.
My personal theory is that Andy (and maybe Betty too) is one of the
angels that danced on the top of a pinhead. Perhaps his real name is
Abdiel.
|
481.33 | ah ... neutrinos? | COMICS::DEMORGAN | Richard De Morgan, UK CSC/CS | Wed Mar 09 1988 12:00 | 1 |
| It has not been proved that neutrinos have zero rest mass ...
|
481.34 | volunteer in a good cause | PASTIS::MONAHAN | humanity is a trojan horse | Wed Mar 09 1988 18:51 | 3 |
| Will anyone who finds a stationary neutrino please put it in an
inter-office envelope and send it to me. When I have enough I will
weigh them and post the result here.
|
481.35 | | AKOV11::BOYAJIAN | $50 never killed anybody | Thu Mar 10 1988 13:58 | 7 |
| re:.34
There's a whole bunch of them heading your way right now.
It's up to you to catch them. :-)
--- jerry
|
481.36 | | VIA::RANDALL | back in the notes life again | Thu Mar 10 1988 16:24 | 5 |
| re: .34
Did you try looking in a neutrino station?
--bonnie
|
481.37 | | MANANA::RAVAN | Tryin' to make it real... | Fri Mar 18 1988 22:48 | 15 |
| [The following just showed up on the usenet, and this seemed an
appropriate place to put it.]
<From: [email protected] (andy frederick)>
>
>This next one is from my calculus teacher in my freshman year. He had a
>horrible habit of explaining the wrong way too much and oversimplifying the
>correct way so that we were always confused. When I heard this I just had
>to write it down. It sums up trigonometry beautifully. Unfortunately, he
>said it with a straight face:
>
> "Whatever works with sine will usually work with cosine --
> just replace all the things with co-things."
-b
|
481.38 | Please make like Daisy,...... | LAMHRA::WHORLOW | Progress:=!(going_backwards>coping) | Mon Mar 21 1988 03:00 | 11 |
|
And give me an answer do,
I'm half crazy......
about this problem. I've exhausted my brain and my friends' brains
too.
Derek - even a concrete hint would do!
|
481.39 | C'est dingue, ce non-sens! | LOCLE::RATCLIFF | Je penche, donc je tombe. Pierre Dac | Sat Aug 06 1988 18:47 | 6 |
| The author of this "riddle" (and the longest path) is Jean Tardieu;
Derek, in .38, would like a *concrete* hint, so here's another from
same:
Given a wall, what's happening behind it?
John.
|
481.40 | | RAVEN1::MKENNEDY | | Mon Aug 15 1988 19:48 | 2 |
| I'm examining the wall. It's made of brick, but I don't think I'll
stick around. See ya.
|