 |
|
|
|
Next: Larry Niven: Does the Moon have Time Zones?
|
| Author |
Message |
External
Since: Feb 29, 2004
Posts: 25
|
(Msg. 61) Posted: Sun Sep 26, 2004 9:17 am
Post subject: Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: alt>books>larry-niven (more info?)
|
|
|
Look at a Monet portrait from inches, all you see are dots and smears, step
back 10 feet and look at the portrait, Viola' you see a picture. I am
talking about the same effect hear. If you are just a little distance from
the rimwall it looks like a wall, but if you are a few miles to hundreds of
thousands of miles it reflects and refracts light so that it looks like a
mountainside. That way you reconcile Ringworld with Ringworld Engineers,
the observations from both books are harmonized. From space the inside of
the rimwall looks like mountains, from the outside it is a featureless wall.
Add in the fact that dues to sun angle the outside is in perpetual shadow,
so there would be no reason to make it look like anything other than a wall.
Allen W.
"Aidan Karley" <aidan.RemoveThis@abuse.demon.co.uk.invalidated> wrote in message
news:VA.000001bc.026baaaa@abuse.demon.co.uk.invalidated...
> In article <UPadneL0ZfWkJcjcRVn-og.RemoveThis@provide.net>, Allen W. McDonnell wrote:
> > Millimeter deep ripples interlocked in a random looking patter that from
a
> > mile away look like rock formations ect ect ect....
> >
> Hmmm, [puts on mountaineer head] hmmm. Not convinced.
> Are plains-dwellers *that* easy to trick?
> Is LNarry a plains-dweller?
>
> --
> Aidan Karley,
> Aberdeen, Scotland,
> Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233
> |
|
| Back to top |
|
 | |
External
Since: Sep 27, 2003
Posts: 24
|
(Msg. 62) Posted: Sun Sep 26, 2004 9:59 pm
Post subject: Re: Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
In article <7N6dnZv8TvHpXMvcRVn-tw.RemoveThis@provide.net>, "Allen W. McDonnell"
<tanada.RemoveThis@provide.net> wrote:
> "Aidan Karley" <aidan.RemoveThis@abuse.demon.co.uk.invalidated> wrote in message
> news:VA.000001bc.026baaaa@abuse.demon.co.uk.invalidated...
>> In article <UPadneL0ZfWkJcjcRVn-og.RemoveThis@provide.net>, Allen W. McDonnell
>> wrote:
>>> Millimeter deep ripples interlocked in a random looking patter that
>>> from a mile away look like rock formations ect ect ect....
>> Hmmm, [puts on mountaineer head] hmmm. Not convinced.
>> Are plains-dwellers *that* easy to trick?
> Look at a Monet portrait from inches, all you see are dots and smears,
> step back 10 feet and look at the portrait, Viola' you see a picture. I
> am talking about the same effect hear. If you are just a little distance
> from the rimwall it looks like a wall, but if you are a few miles to
> hundreds of thousands of miles it reflects and refracts light so that it
> looks like a mountainside. That way you reconcile Ringworld with
> Ringworld Engineers, the observations from both books are harmonized.
> From space the inside of the rimwall looks like mountains, from the
> outside it is a featureless wall. Add in the fact that dues to sun angle
> the outside is in perpetual shadow, so there would be no reason to make
> it look like anything other than a wall.
The illusion is known in art & architecture as "trompe l'›il" - literally
something which deceives the eye; achieving the appearance of reality by
the use of minute, often trivial details or other effects in painting.
There's a story about two rival artists; one created a mural of an orangery
that was so realistic, its blossoms attracted butterflies. In the end, the
other artist conceded defeat when he saw the insects were painted as well.
Tennant Stuart
--
____ ____ _ _ _ _ __ _ _ ____
(_ _)( ___)( \( )( \( ) /__\ ( \( )(_ _) Greetings to family
)( )__) ) ( ) ( /(__)\ ) ( )( friends & neighbours
(__) (____)(_)\_)(_)\_)(__)(__)(_)\_) (__) @argonet.co.uk & MCR |
|
| Back to top |
|
| |
External
Since: Oct 03, 2004
Posts: 29
|
(Msg. 63) Posted: Mon Sep 27, 2004 12:43 am
Post subject: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
"Allen W. McDonnell" <tanada.DeleteThis@provide.net> writes:
>Add in the fact that dues to sun angle the outside is in perpetual shadow,
>so there would be no reason to make it look like anything other than a wall.
I wonder....
I don't have a feel for how the sun looks from RW. If you are deadbang
center of the arch; i.e equaldistant to each rimwall^H^H^Hrimmountainrange;
how big is the sun to you?
If you are at the rimwall, where is the sun in your sky? My vision
is it so far away that light that arrives is parallel, i.e. "it's
directly overhead" but is it?
This is all a function of the diameter of it (and the shadow squares
that MUST be wider than the arc of the light..) vs distance..
--
A host is a host from coast to coast.................wb8foz.DeleteThis@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433 >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Feb 29, 2004
Posts: 25
|
(Msg. 64) Posted: Mon Sep 27, 2004 12:43 am
Post subject: Re: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
>
> I don't have a feel for how the sun looks from RW. If you are deadbang
> center of the arch; i.e equaldistant to each
rimwall^H^H^Hrimmountainrange;
> how big is the sun to you?
>
> If you are at the rimwall, where is the sun in your sky? My vision
> is it so far away that light that arrives is parallel, i.e. "it's
> directly overhead" but is it?
>
> This is all a function of the diameter of it (and the shadow squares
> that MUST be wider than the arc of the light..) vs distance..
>
I THINK it is directly overhead, but I would want to stand there to be sure.
The sun is spherical so light from all across the surface is lined up with
your location vertically. The Rimwall itself will be outside the arc of the
sun from your point of view on the surface so you will see a full size sun
up there somewhere in the sky. I am confident it would appear to be
directly overhead, but not enough to bet serious money on it 
Allen W. >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Jun 11, 2004
Posts: 8
|
(Msg. 65) Posted: Mon Sep 27, 2004 2:08 am
Post subject: Re: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
>I don't have a feel for how the sun looks from RW. If you are deadbang
>center of the arch; i.e equaldistant to each rimwall^H^H^Hrimmountainrange;
>how big is the sun to you?
The distance from RWmedian to the sun is 95 megamiles, or 1.02 au. So from RW
median, the sun will appear to be 1/(1.02)^2, or 95.8%, its apparent size as
seen from earth. Given atmospheric distortion and our eyes' intolerance for
direct solar viewing, you wouldn't see the difference, istm.
>If you are at the rimwall, where is the sun in your sky? My vision
>is it so far away that light that arrives is parallel, i.e. "it's
>directly overhead" but is it?
The rimwall is 0.5 megamiles from the RWmedian. So the angle to the center of
the RW sun, as seen from the rimwall, relative to overhead, is arctan (0.5/95)
or 0.30 degrees. This is half of the angle subtended by the body of the sun at
that distance (the RW is approximately the same width as the sun), so again,
with the naked eye, you wouldn't see it. >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Jun 18, 2004
Posts: 20
|
(Msg. 66) Posted: Mon Sep 27, 2004 4:00 am
Post subject: Re: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
In article <cj7no8$31b$2@reader1.panix.com>, David Lesher wrote:
> If you are at the rimwall, where is the sun in your sky? My vision
> is it so far away that light that arrives is parallel, i.e. "it's
> directly overhead" but is it?
>
In the order of a degree off-zenith. Whether that would be noticed by
near-Stone-Age societies is ... a dramatic element.
--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233 >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Jun 18, 2004
Posts: 20
|
(Msg. 67) Posted: Mon Sep 27, 2004 5:00 am
Post subject: Re: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
In article <41577F03.89E31364.DeleteThis@alcyone.com>, Erik Max Francis wrote:
> casual observer.
>
No disagreement. But that's a loaded term!
--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233 >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Jun 18, 2004
Posts: 20
|
(Msg. 68) Posted: Mon Sep 27, 2004 1:00 pm
Post subject: Re: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
In article <4157B567.864D2362.TakeThisOut@alcyone.com>, Erik Max Francis wrote:
> Even with them, it'd be incredibly difficult. 20 minutes of arc is not
> exactly a huge shift.
>
The diameter of the Moon or Sun from the Earth is about 27 minutes
of arc.
--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233 >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Aug 31, 2004
Posts: 29
|
(Msg. 69) Posted: Mon Sep 27, 2004 6:55 pm
Post subject: Re: Rim Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
"Allen W. McDonnell" <tanada RemoveThis @provide.net> writes:
>Heck with that, you could just rough up the surface on the interior side so
>that even vertical it would look like a mountainside from a distance. You
Interesting idea. *
--
* PV something like badgers--something like lizards--and something
like corkscrews. >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Aug 31, 2004
Posts: 29
|
(Msg. 70) Posted: Mon Sep 27, 2004 6:58 pm
Post subject: Re: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
David Lesher <wb8foz.TakeThisOut@panix.com> writes:
>I don't have a feel for how the sun looks from RW. If you are deadbang
>center of the arch; i.e equaldistant to each rimwall^H^H^Hrimmountainrange;
>how big is the sun to you?
Almost exactly the size of our sun. Don't try to measure it - it's about
the same as the size of the full moon, by a wonderful coincidence.
>If you are at the rimwall, where is the sun in your sky? My vision
>is it so far away that light that arrives is parallel, i.e. "it's
>directly overhead" but is it?
If you're in the center of the ringworld, it's straight overhead. At an
edge it's something like half a degree off of vertical, if I remember some
calculations I did a while back. *
--
* PV something like badgers--something like lizards--and something
like corkscrews. >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Aug 31, 2004
Posts: 29
|
(Msg. 71) Posted: Mon Sep 27, 2004 7:07 pm
Post subject: Re: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
Erik Max Francis <max.TakeThisOut@alcyone.com> writes:
>And? Do you really think that a shift of 20 arcmin is really all that
>noticeable by means of dead reckoning?
On earth, yes - you would be able to see that much movement simply by
putting a stick in the ground and marking the endpoints of the shadow 12
minutes apart. Since you can derive a perfectly usable east-west line in
this amount of time (the book actually says 15 minutes, but close enough),
it's significant.
On the other hand, on the ringworld YOU'RE doing the moving, trying to take
a direct sun bearing from two widely-spaced places on the ground. 20
minute's accuracy isn't impossible (provided you have something to protect
your eyes from the sun!), but it would take a skilled observer for sure. *
--
* PV something like badgers--something like lizards--and something
like corkscrews. >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Jun 18, 2004
Posts: 20
|
(Msg. 72) Posted: Tue Sep 28, 2004 4:00 am
Post subject: Re: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
In article <415849C1.ADEEF95F.RemoveThis@alcyone.com>, Erik Max Francis wrote:
> > > Even with them, it'd be incredibly difficult. 20 minutes of arc is
> > > not
> > > exactly a huge shift.
> > >
> > The diameter of the Moon or Sun from the Earth is about 27
> > minutes
> > of arc.
>
> And? Do you really think that a shift of 20 arcmin is really all that
> noticeable by means of dead reckoning?
>
Not greatly disagreeing, but since that level of accuracy was
available pre-telescope on Earth ... and the RW has nights (even if the
astronomy is decidedly different from Earth) ... I wouldn't put it past a
sub-telescope technology there.
Always beware of absolutisms (including this one)!
--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233 >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Jun 18, 2004
Posts: 20
|
(Msg. 73) Posted: Tue Sep 28, 2004 4:00 am
Post subject: Re: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
In article <41588589.54C646F8 RemoveThis @alcyone.com>, Erik Max Francis wrote:
> The
> only way it could be truly apparent is if you could stand flush against
> a perfectly straight rimwall,
>
Hmmmm. I've been doing assistant work for the Harvard (USA
somewhere, Boston?) Centre for Astronomy helping them to annotate their
scanned library. Frequently I've seen references to checking the
horizontality of the axles of a meridian transit telescope by "observing
the zenith in a mercury reflection". I don't know the technique's
details, but it's obviously so well known to not need detailed
description.
Deduction - getting a zenith to better than a few minutes is
plausible in a non-telescope society. Science feeds technology;
technology feeds science; please climb onto the merry-go-round!
--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233 >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Jul 14, 2004
Posts: 62
|
(Msg. 74) Posted: Tue Sep 28, 2004 6:29 am
Post subject: Re: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
Aidan Karley <aidan DeleteThis @abuse.demon.co.uk.invalidated> wrote in message news:<VA.000001e6.0d2681b9 DeleteThis @abuse.demon.co.uk.invalidated>...
....
> Hmmmm. I've been doing assistant work for the Harvard (USA
> somewhere, Boston?) Centre for Astronomy helping them to annotate their
> scanned library. Frequently I've seen references to checking the
> horizontality of the axles of a meridian transit telescope by "observing
> the zenith in a mercury reflection". I don't know the technique's
> details, but it's obviously so well known to not need detailed
> description.
An undisturbed pool of liquid mercury has a highly reflective surface
that
is almost exactly horizontal, over a very large area. The technique
they're referring to uses that fact to make very accurate measurements
of
even very small deviations from exactly vertical. However, it's
difficult to keep such a pool clean, and it requires precise measuring
instruments to take advantage of this fact. It's 19th century
technology. >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
External
Since: Aug 31, 2004
Posts: 29
|
(Msg. 75) Posted: Tue Sep 28, 2004 3:26 pm
Post subject: Re: Sun arc, was Rim Wall/Transport System [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
|
|
|
Erik Max Francis <max DeleteThis @alcyone.com> writes:
>We're talking about the difference in the position of the Ringworld's
>sun from the point of view of the Ringworld centerline vs. near a
>rimwall. Do you realize how long a trip that is?
Yes I do, and I was agreeing with you!.
>Yes. You could detect the difference if you were clever and cared
>enough. If you're the average joe looking up at the sun, there's no way
>the change would be obvious, apparent, or even barely noticeable. The
>only way it could be truly apparent is if you could stand flush against
>a perfectly straight rimwall, because then you could look up and notice
>that the Sun was not also flush with the rinwall. But the rinwalls are
>sculpted mountains, so even that isn't possible.
More interesting was someone saying that most of the ringworld wall would
get no sunlight at all. If it's as black as space, it would make a much
less imposing piece of landscape, and the mountains, which would get light
by virtue of sticking out, would look a lot more natural. Neat. *
--
* PV something like badgers--something like lizards--and something
like corkscrews. >> Stay informed about: Rim Transport System |
|
| Back to top |
|
| |
|
You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
|
|
|
|
|
|
FAQ
Search
Profile
Private Messages
Log in/Register/Password
