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PostPosted: Mon Apr 09, 2012 3:43 pm 
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For a clock, someone might think to use their own pulse. At rest, their heartbeat might be constant enough to give an a rough idea of the time scale involved and how much different it is on Phalanos.

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PostPosted: Mon Apr 09, 2012 8:53 pm 
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aspqrz wrote:
Why use candles for accurate time measurement?

Even the ancients had better methods!

Hourglasses (C8th AD at the earliest), once they figure out to use powdered eggshells for the "sand" rather than actual sand (which is an abrasive and gradually widens the hole to make the hourglass less accurate) ... oh, note that "hourglass" is a generic term ... they came in a variety of sizes and durations, down to, IIRC, the minute and half minute.

Clepsydrae also (4000 BC in China! Used as stopwatches to time customers in Athenian Brothels by 400 BC!) would be an earlier possibility.

I would guess that the rate at which sand falls through an hourglass and that rate at which water flows through a hole under the pressure of its own weight both depend on gravity.

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PostPosted: Mon Apr 09, 2012 8:55 pm 
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rust wrote:
One of the projects I am working on now and then is a pseudo-historical / fantasy
setting where a dimensional gate enables scholars from Earth to visit another world.
This world has a slightly lower surface gravity than Earth. The visitors will probably
feel a difference, but do they have a way to measure the difference with medieval
scientific instruments ?

Would it be possible to set up a balance in the gate, with one arm in, and subject to the gravity of, each world?

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PostPosted: Mon Apr 09, 2012 9:49 pm 
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Cyborg IM1 wrote:
For a clock, someone might think to use their own pulse.

Galileo did.

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PostPosted: Tue Apr 10, 2012 12:54 pm 
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Agemegos wrote:
Would it be possible to set up a balance in the gate, with one arm in, and subject to the gravity of, each world?

Not really, in the current version the gate is a painting of a location on the
other world, and a specific spell instantly transports the persons in front of
the painting to the location the painting shows, so it is now more like tele-
portation than like a typical gate or portal.
As for the gravity thing, after some more thoughts I have com to the con-
clusion that I will give the characters some hints, like the increased range
of a crossbow and such, but that I will leave everything else (the idea that
it has to do with gravity, potential methods to determine the differences in
the two worlds' gravity fields, etc.) to the characters.
Good ideas will be rewarded with significant improvements of the relevant
knowledge skills, if the characters ignore the hints and the problem, some
non-player character will have the right insight - and the reward - later in
the campaign.


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PostPosted: Wed Apr 11, 2012 2:31 pm 
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You might also impose some negative DMs to Hit until they adjust their "reflexes" to the new gravity.

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PostPosted: Sun Apr 15, 2012 6:38 am 
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Agemegos wrote:
They didn't. Not until the Renaissance. Galileo Galilei was the first person to time objects falling through different distances and to discover that they accelerate.


That's why it's a great height. Certainly differences in the fractions of a second won't be won't noticeable without somewhat precise instruments, but if something is hitting the ground a full five later, I'd think even with someone just calling out the count the difference in gravity might be noticeable.

It really depends on how much knowledge they have, as opposed to technology. If the visionaries/theories exist, but the mechanisms don't, there's potential. For instance, a savant overhears the peasant porters they brought along for grunt work discussing how they enjoy the work in the "other world" because lifting heavier loads is easier and so they don't need as many trips to shift items, so it's less tiring. He wonders why that is. Perhaps later, he hears one of the adventurers/mercenaries, like some English longbowman talking about how it's tricking shooting his bow on the world because there's something "off" about the world and while short range shots are only mildly influenced, his long-range accuracy is seriously off because his arrows seem to travel further. Discussions with the bowman might lead the savant to wonder if there's something different about the air on the world, but further tests might be needed.

It might eventually lead to very tall cliff, its height measured and compared against something on Earth by using rope (a lot of rope). Some people are the bottom, a few at the top with cannonballs and a signal mirror. The moment the cannonball is dropped over the edge, they shine the signal mirror to those at the bottom. Some person with a steady nerve starts to call (or probably sing - it's much easier to keep a reasonable time singing) out the numbers. If something at some rope-length on Earth takes 12 seconds to hit the ground while on this alien world it takes 16 seconds, after numerous repeats, they might start to wonder.

It's all horribly imprecise to us in the modern day (or even after somewhat accurate clocks are invented), but they'd have to make do with what they have. Also, given they don't have a memory that digital or mechanical timepieces exist, this level of accuracy would be acceptable to them.


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PostPosted: Sun Apr 15, 2012 7:10 am 
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epicenter wrote:
It might eventually lead to very tall cliff, its height measured and compared against something on Earth by using rope (a lot of rope). Some people are the bottom, a few at the top with cannonballs and a signal mirror. The moment the cannonball is dropped over the edge, they shine the signal mirror to those at the bottom. Some person with a steady nerve starts to call (or probably sing - it's much easier to keep a reasonable time singing) out the numbers. If something at some rope-length on Earth takes 12 seconds to hit the ground while on this alien world it takes 16 seconds, after numerous repeats, they might start to wonder.

Twelve seconds. 2,300 feet. Anyone know any seven-hundred-metre cliffs?

I'd use trig to measure the heights of the cliffs, by the way. Half a mile of rope is a lot to deal with, and tricky to support the weight of.

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PostPosted: Mon Apr 16, 2012 2:09 am 
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Agemegos wrote:
aspqrz wrote:
Why use candles for accurate time measurement?

Even the ancients had better methods!

Hourglasses (C8th AD at the earliest), once they figure out to use powdered eggshells for the "sand" rather than actual sand (which is an abrasive and gradually widens the hole to make the hourglass less accurate) ... oh, note that "hourglass" is a generic term ... they came in a variety of sizes and durations, down to, IIRC, the minute and half minute.

Clepsydrae also (4000 BC in China! Used as stopwatches to time customers in Athenian Brothels by 400 BC!) would be an earlier possibility.

I would guess that the rate at which sand falls through an hourglass and that rate at which water flows through a hole under the pressure of its own weight both depend on gravity.


Well, IAMOP*, but it would seem, on first consideration, that the *speed* at which the sand *falls* would be affected, but would the *rate of flow*?A
And, assuming that's wrong, why would candles burn at the same rate? Surely the capillary action that draws the fuel up through the wick would also be affected by gravity as well, making them even more inaccurate?

And, if we're measuring localised differences, it depends on how localised and what sort of communication methods you have ... you could position the timing mechanism somewhere where the observation *isn't* and communicate start/end times (which would get into measuring communication speeds ... presumably lightspeed for flasher/heliograph, sempahore/optical telegraph or electricity speeds for telegraphy/telephony) reasonably accurately.

Phil
(* "I Am Not A Physicist")


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PostPosted: Mon Apr 16, 2012 7:52 am 
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aspqrz wrote:
Well, IAMOP*, but it would seem, on first consideration, that the *speed* at which the sand *falls* would be affected, but would the *rate of flow*?

I'm not sure, but it seems very likely. The rate is obviously zero at zero gravity, and it's hard to imagine that it suddenly switches on to the full Earth-normal rate at some critical value of gravity. This being the case, the rate has to vary with gravity over at least some ranges. And the point is that if you aren't sure, and I'm not sure, how are mediaeval scholars going to be sure about it?

Quote:
And, assuming that's wrong, why would candles burn at the same rate?


I don't think candles would be any use even if they did burn at the same rate under different gravity. I'm pretty certain that the rate at which candles burn must be affected by air pressure and the concentration of oxygen in the air. And even if they did provide an accurate standard of time, they just aren't anything like precise enough to be of any use. You can't measure anything more precisely than about the nearest quarter of an hour, and we're talking about timing phenomena that take only seconds.

Quote:
Surely the capillary action that draws the fuel up through the wick would also be affected by gravity as well, making them even more inaccurate?


I don't know what determines the rate at which candles burn. I think it has to do with a feedback between the melting of wax and the burning of melted wax, and is not rate-limited by the supply of wax up the wick. If you drain away the pool of molten wax in the candle the wick burns faster, not slower. I'm not sure that high gravity would directly counteract capillary action—I would have guessed that it was limited more by air pressure. But anyway, the different air on a different world will rule out the candle as a portable standard of time even if nothing else does.

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© My posts on SFRPG must not be reproduced beyond the board except with explicit permission from me.


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