Nareed
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December 5th, 2011 at 7:22:13 AM permalink
Quote: Face

Forgive me for backtracking, but it's just been chewing at the back of my mind to the point I could not tolerate it anymore. I just could not believe the facts presented here. (/gasp!) So yesterday, I did it...



You're not much for the phrase "Don't try this at home," are you?

Quote:

Visual inspection revealed nothing, or at least nothing significant. I pressed my lips to the area and it was definately cold, not quite "ice cold", but colder than I've ever felt my skin. Within a minute or two, all pain had subsided and my hand was as good as it ever was.



One ice cube is very different than several, or ice water. but you do support my assertion that damage would not happen in a few seconds.

Quote:

Give me a few days to forget how terrible that bone ache felt and I'll try the salt =/



Make sure your insurance is paid up, and chose a finger you won't regret losing. Seriously, don't try it. Get a kind of semipermeable mebrane and a thermocouple if you must experiment. If that's not enough, get a pig carcass and try the experiment on it. There's a reason scientists use subjects.
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boymimbo
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December 5th, 2011 at 8:01:32 AM permalink
Or watch the various videos out there on the net.
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odiousgambit
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December 5th, 2011 at 8:04:52 AM permalink
Quote: Nareed

Seriously, don't try it. Get a kind of semipermeable mebrane and a thermocouple if you must experiment. If that's not enough, get a pig carcass and try the experiment on it. There's a reason scientists use subjects.



As someone posted before, there are you-tube segments showing people putting salt and ice-cubes on their arms [arms usually]. Evidently [after various hysterics/stoicism depending on subject] some come away with frostbite burns, but these home-made videos I've seen don't really make the aftermath very clear.
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Nareed
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December 5th, 2011 at 8:21:35 AM permalink
Quote: odiousgambit

As someone posted before, there are you-tube segments showing people putting salt and ice-cubes on their arms [arms usually]. Evidently [after various hysterics/stoicism depending on subject] some come away with frostbite burns, but these home-made videos I've seen don't really make the aftermath very clear.



I try not to encourage Darwin Award wannabes. Encouraging knowledge is another matter. Some things are best learned by experiments or practical demonstration, rather than by looking up the answers. The problem is some experiments are dangerous and/or delicate. So I would encourage finding videos from actual scientific demos. One place is Popular Science's website.
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1BB
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December 5th, 2011 at 11:18:36 AM permalink
Quote: boymimbo

Or watch the various videos out there on the net.



You'll probably come across the videos with the dollar bill and the lit cigarette as well.
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Garnabby
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December 6th, 2011 at 2:20:28 PM permalink
Quote: weaselman

Garnabby, four words for you: eschew obfuscation, espouse elucidation.


But true "silence is golden", however procured!

P.S. Can you put that in latin, or spanish too?
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Face
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December 7th, 2011 at 12:17:07 AM permalink
Quote: Nareed

You're not much for the phrase "Don't try this at home," are you?



Not as general rule. I oppose the nanny state, and find most warnings to verge on absurd. Couple that with my penchant for taking risks, experience with cold, and damnable curiousity and I just had to do it. I appreciate all the concern, but really... I'm not partaking in some juvenile test of fortitude, only an experiment. I'm free to cry off at any time, and would do so if things seemed dangerous.

So, the salt. This cube was slightly bigger, something I wasn't concerned with because, as I said, I could cry off at any time. The location of placement was the same, and was nearly entirely covered with a layer of salt (only wanted to do it once, better do it right).

The process began much the same. 5 seconds in and I got the pricklies. 10 seconds in and it got numb. 20 seconds in and the bones in my hand started to ache. That ache again crept up my arm, but wasn't as severe or pronounced as I remembered it with the plain ice. I did notice a marked difference in the rate of melting. I don't know why, but it was a full 30-40 seconds before I felt the first drip. It was lasting forever. I noticed no discernable change after this point, and at a full two minutes twenty, twice as long as the plain ice, the patting of my hand to prevent dripping salt water on the floor caused the cube to slip off. As far as the pain goes, I could have lasted until the cube was gone and probably done another, it was nowhere near the discomfort of the first trial. I assume it's because my general pain level is higher today (recently had a hockey game) whereas last time I was quite comfy. Who knows...

Again, a press to the lips found my skin colder than I've ever felt it. I did notice a red spot where the cube had been. I went and had a smoke, checked it again (approx 3 min after ice removal) and my hand was as good as it ever was. No redness, no pain, no evidence whatsoever of the experiment.

So two things - First, while salt water is able to reach a lower temp than plain water, I don't believe the RATE of heat transfer changes. The heat would leave my hand at the same speed, there would just be more removed. Second, anyone ever watch Deadliest Catch? The Bering Sea freezes, the water always at salt waters temp of phase change. And everytime they quote the temp (which they do CONSTANTLY when talking about people falling in) it's always in the 20's. It's only a handful of degrees, which I didn't think would matter all that much. At least in my example, it didn't, and I feel I proved my point.

So there you have it. I've no doubt salt + ice, or just ice alone, could cause damage, whether it's a "burn" or total destruction of a limb. But at least now we have an idea of the scale which would have to be reached for injury to occur. I would suspect that for noticble damaged it would take well more than 5 minutes of constant contact, salt or no, for someone to experience a burn as the Father offered. And that'd be a hell of a big ice cube to last that long.

I stand by my call of shenanigans, Father. ;)
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FrGamble
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December 7th, 2011 at 9:06:40 PM permalink
Dear Face, thank you so much for your sacrifice and efforts - I don't know what to say. Next time I see her I will have to let her know that her shenanigans caused innocent and good people who she doesn't know to suffer. Seriously I guess I should say thanks, did I tell you about the time a student was late to class because he said he licked a flagpole in the frezzing cold and his tounge stuck, oh well nevermind I'm sure that is not true either... :) Peace.
Face
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December 7th, 2011 at 10:08:37 PM permalink
Quote: FrGamble

Dear Face, thank you so much for your sacrifice and efforts - I don't know what to say. Next time I see her I will have to let her know that her shenanigans caused innocent and good people who she doesn't know to suffer. Seriously I guess I should say thanks, did I tell you about the time a student was late to class because he said he licked a flagpole in the frezzing cold and his tounge stuck, oh well nevermind I'm sure that is not true either... :) Peace.



Your quite welcome, Father, but twas nothing. I'd hardly call it suffering, just a short period of discomfort that was far more tolerable than the pain of my nagging curiosity. Nor would I blame her, since kids will be kids and no one even suggested, let alone forced, me to do it. Just make sure her conditions were similar to mine if you do confront. Ice CAN cause damage, and if she was involved in those youthful "feats of strength" and left it on for an absurd amount of time (a very large chunk or repeated normal cubes), she might well have incurred damage. But a single cube from a fountain drink, I'd say, nears the impossible.

But just FYI, the tongue is absolute truth. I never tried it (that's one "Do Not Try At Home" warning that mirrored my common sense) but I have had my lips stick to metal things in winter, such as a lighter, fishing lure, hunting knife, etc, and it has peeled lip skin. And I have licked a finger and stuck it to a flagpole after watching Christmas specials, and it does stick. And idiot friends who've licked ski lift lap bars, and is was hilarious and terrible. That old standby is no myth.
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Nareed
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December 8th, 2011 at 7:52:17 AM permalink
Quote: FrGamble

Next time I see her I will have to let her know that her shenanigans caused innocent and good people who she doesn't know to suffer.



Actually it was your question here concerning her actions that led Face to try to get frostbite. Had you not asked about it, she could have set herself on fire, or jumped off a bridge, or done any other number of unwise things, and Face and his hand would have remained blissfully unaware of them. :)
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weaselman
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December 8th, 2011 at 8:00:21 AM permalink
Quote: FrGamble

Seriously I guess I should say thanks, did I tell you about the time a student was late to class because he said he licked a flagpole in the frezzing cold and his tounge stuck, oh well nevermind I'm sure that is not true either... :)


Priceless! Thank you, father!
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Face
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December 12th, 2011 at 9:03:28 PM permalink
TOPIC: "Random Snowflakes"

It's that time of the year when you're bound to hear some inspirational message conveyed with the point that "No two snowflakes are ever the same". Me being me, I had to challenge the idea and as a result now believe this cliche to be false.

Snowflakes can be very varied indeed. Sometimes, on a very cold, dry night, they come down almost as diamond dust. I have seen some I would judge to be fractions of a millimeter, yet big enough to see the detail with naked eye (these are the ones I find to look like the stereotypical representation we see in decorations, very symetrical and very geometric). I believe the record for largest fallen snowflake is fifteen inches, although I would estimate a "typical" big flake as two to three.

Now, snowflakes are just ice, which forms as a crystalline structure. That right there slashes the possible configurations of the water molecules by a great number as they can't join randomly or haphazardly. And in the history of Earth as we know it, I'd put the number of flakes fallen somewhere over the number 10 followed by, I dunno, one hundred thousand zeroes? (I'd be interested if anyone could ball park it better than a top-'o-the-head guess, although I assume it's probably impossible)

Doesn't it stand to reason that they've been duplicated possibly hundreds if not thousands of times? I haven't done any book work yet, just thought experiment, but I think if I can find the proper numbers and do a little crunching, I can prove mirror snowflakes are not the unicorns people believe them to be. Rather, I think they could be seen in a lifetime, maybe even within a decade or year.

But before I do I thought I'd open it to discussion, see what all the thinkers here feel on the matter. Random snowflakes - any truth to it whatsoever?
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weaselman
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December 13th, 2011 at 5:41:49 AM permalink
I'll start with the first part for now:
Quote: Face

And in the history of Earth as we know it, I'd put the number of flakes fallen somewhere over the number 10 followed by, I dunno, one hundred thousand zeroes? (I'd be interested if anyone could ball park it better than a top-'o-the-head guess, although I assume it's probably impossible)



It is actually much less than that. The hardest part is to estimate how much snow actually falls on Earth every year. The record annual snowfall in US seems to be just under 1000 inches or 25.4 meters. Granted, some areas (South Pole?), probably, get much more snow, but others don't get any at all, and there is more of the latter. There were ice ages, but there were also some very hot periods (especially, towards the beginning of the history). Besides, this is the record number, not an average, so, I think, it is appropriate to be used as high estimate. You'll see in the end that it does not matter very much for the qualitative answer if I happen to underestimate it by a few orders of magnitude.

Now, the surface area of the Earth is about 500 million square kilometers, or 5*10^14 square meters. Multiply this by 24.5 to get 1.3*10^16 cubic meters of snow per year.
The age of the Earth is about 5 billion years, so 6.5*10^25 cubic meters total. Snow is about 12 times less heavy than water. Let's say 10 times for simplicity, which makes one cubic meter to be about 100 kilograms. This gets us to about 6.5*10^27 kilogram of snow since the beginning of time.

Now, a snowflake contains about 10^19 molecules, and a single water molecules weighs about (16+2)/6.022*10^23 ~ 3*10^-23, which makes one snowflake to be about 3*10^-4 grams, or 3*10^-7 kilograms.

Bringing it all together, we get about 2.2*10^34 snowflakes since the beginning of time. Only 34 zeroes, give or take, not at all close to thousands (1, followed by just a hunderd zeroes is an enormous number, greater than the number of atoms in the whole observable universe, way larger, than its age in nanoseconds or size in Planck lengths etc.).

Unfortunately, I don't know crystal science well enough to speculate on how many different configurations can 10^19 molecules form, but something tells me it's a lot :) I would guess, while not entirely impossible, it is extremely unlikely the a pattern ever repeats itself exactly. However, if you asked if two snowflakes are ever "alike", where "alike" is defined as not distinguishable with a naked eye, that would be a different story. I would think, that the later statement is, probably, false.
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Face
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December 13th, 2011 at 12:00:46 PM permalink
Jumpin Jehoshaphats! I feel gorged on information.

Thanks for bringing things into perspective, weasel. I'm rubbish at conceptualizing the very large, and this "very rough estimate" is quite what I was looking for.

I, too, am ignorant of any sort of crystal science, and using 10^19 units to make anything, even if it was simple triangles, would leave you with a ridiculously high number of possible combinations. That sucks =( lol

Because yeah, my original thought was pertaining to exact replicas down to the molecular base. I've often looked at those really small ones I mentioned in my OP, and given enough time, I'm sure I could find 2 that looked alike. I wanted to know the possibility that they were identical. It seems I have severely underestimated the smallness of water molecules.

From what I've read, ice crystals typically form in hexagons. Wouldn't 10^19 water molecules / 6 = "ice units"? And taking a leap of faith and assuming snowflakes are symetrical, couldn't we then take that number and divide it in half, and just figure how many different combinations of these remaining units there are? (since what changes on one side would have to change on another) Or did I just bastardize the entire concept of math, science and logic? ><

If I'm in any way correct, then it seems that I'd have to figure out the possible configurations of [(10^19 / 6) / 2] "ice units", then figure the probability of two of these configurations repeating within 2.2*10^34 times.

In the words of Jeremy Clarkson, "How hard could it be?" ;)
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P90
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December 13th, 2011 at 12:41:51 PM permalink
Remember what you said about numbers with 100,000 zeroes?

If you have just 10,000 elements, there will be something on the order of 10^35000 possible combinations.
For 10^19 elements, there would be something about 1.20247678*10^168091349662870733545 or over 10^^21 possible combinations. That's a number with a sextillion digits. If you gathered every single data storage device in the world, it would only just be enough to simply store that number in decimal notation, and it would take a few to send that number between the Old World and the New World using all communications methods combined.

These combinations hold for different elements, since molecules involved are the same, the number is much smaller. But "much" is still an order of magnitude somewhere around 10^1,000,000,000,000. So in absence of very strict formal structure the probability of identical crystals is zero.
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Nareed
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December 13th, 2011 at 1:31:17 PM permalink
I read somewhere that a Googleplex (10^10^100) is too big a number to actually measure anything in the universe.

Is this so? I can comprehend a Google (10^100), barely. But that's where I draw the line :)
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weaselman
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December 13th, 2011 at 2:23:04 PM permalink
It's actually spelled "googol" and "googolplex", nothing to do with google.com :)
Googleplex is actually what they call Google.com's HQ :)

As to what you can measure with it, yeah ... like I said earlier, it is hard to come close to even 10^100 (the googol) enumerating various "things" in the universe (there are far fewer atoms in the universe for example), leave alone 10^10^100.
There are some extravagant examples that could still invoke googolplex. Here is one.
If you pack the whole universe solid with dust, and number every particle, so that they are all different, the number of different ways to arrange those particles would be somewhere close (as in within a few googols, probably :)) to one googolplex.
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Garnabby
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December 13th, 2011 at 4:11:19 PM permalink
Quote: Face

"No two snowflakes are ever the same". Me being me, I had to challenge the idea and as a result now believe this cliche to be false.


Were some two, or more, things exactly the same, wouldn't those also occupy the same, or a common, space and time? Ie, as one entity, or one which has many such vantage points? As opposed to that old lament of the ancients, "You can never swim in the same river (again)."

Another thing that comes up in such discussions is the enantiomorphism paradox.
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odiousgambit
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January 16th, 2012 at 1:33:47 PM permalink
So you want to be a Scientist, eh. Well, speaking for myself anyway, prepared to be humbled if you really study it.

Something unexplained to my satisfaction anyway is the way sunrise and sunset do not change evenly this time of year. We just came away from the shortest day late in December, so the days are indeed getting longer. But not in a balanced way: the sunrise actually gets later in the morning, then is the very same time of the morning way into January. The effect of longer days comes purely from the evening sunset being later, and there was no earlier sunrise until just yesterday or so [around here]. [edited]

I have puzzled over this for a long time and have come across this, which clearly leads to some pretty damn complicated stuff. It still baffles me that the facts 'Earth 's tilt is about 23.5 degrees' and "Earth's orbit isnot a perfect circle, but is instead an ellipse' causes mornings to be shorter than evenings, yet we do not have to keep resetting our clocks. Instead sunrise and sunset change in an unbalanced way.

Perhaps someone smarter has some insight?
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Doc
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January 16th, 2012 at 6:05:56 PM permalink
I am not an astronomer at all, though I think the Wizard has some moderately-serious interests in this area, so perhaps he should be speaking up here. I have never looked into this topic enough to be able to explain the answer, but I think I can give a hint as to why such a unbalanced effect should not be too surprising.

Suppose you are looking down perpendicularly upon the earth's orbit from very high above and visualize it as a definite ellipse (exaggerated from what it really is) with the sun at one of the foci. The earth's rotational axis is tilted, so from your perspective it forms a line rather than a single point. Think about the direction of that rotational axis line and about the major axis of the orbital ellipse, then consider the point in time when the earth passes one end of the major axis.

At that point in time, the rotational axis line, even if extended, does not pass through the sun; i.e., the earth's rotational axis is not aligned with it's orbital axis. Although the earth is nearest to (or farthest from) the sun when it crosses the orbital major axis, that date is not the winter or summer solstice, which is the date that the rotational axis (extended) would appear, from your "over-orbit" perspective, to pass through the sun. I believe this lack of axis/orbit symmetry is what gives rise to the lack of symmetry in the sunrise/sunset pattern.
odiousgambit
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January 17th, 2012 at 4:10:15 AM permalink
Quote: Doc

I believe this lack of axis/orbit symmetry is what gives rise to the lack of symmetry in the sunrise/sunset pattern.



I think you are on to something. And I have been reading more.

I was thinking about the whole business as I woke up [was my sub-conscious mind working on this while I was dreaming?] and I have decided that each element must be examined separately. What is happening A#1 is that what I will call the "breadth of the day" is wandering, causing what is called "shifting solar noon". Let's imagine that a day's length does not change. Even so, with elliptical orbits, the time of sunrise and sunset is likely to be changing. I am at the point of imagining a planet on a non-tilting non-elliptical orbit and what happens every complete rotation. The star the planet is orbiting appears to be at one point, then on one complete rotation, why would the star seem to appear at the same spot when the planet has moved along its orbit? [edit:further thought makes me realize this is largely to be expected] We here on Earth expect the Sun to be at that same spot 24 hours later. Why is that? Because the Earth returns to this spot in the nature of its rotation speed! This has to be true! [edit: currently I believe that this must be true if it holds after a great number of rotations and the Earth has moved along on its orbit] This apparently is very common, the study of it has a name: analemma. There must be a reason why a planet in a stable orbit tends to have a rotation that does this.

Our analemma: Because this return to the same spot is not perfect, and because of the effect of the tilted axis, time-lapse photography would show the Sun tracing a figure eight in the sky [over the period of a year I guess]. Astonishingly to me, other planet's do something similar:

from wikipedia, other analemmae:

Mercury: a nearly straight east-west line.
Venus: resulting curve is an ellipse.
Mars: teardrop
Jupiter: ellipse
Saturn: technically a figure 8, but the northern loop is so small that it more closely resembles a teardrop
Uranus: figure 8
Neptune: figure 8
Pluto: figure 8

Unless I am wrong, what I read into this is that if rotational speed was willy nilly, the breadth of the day would wander like crazy. Couldnt there be such planets that don't coordinate rotation speed with a similar daily view of the host star? In a few rotations of said planet, sunrise could easily be changed to what had been the time of midnight, etc, if someone had a clock that was set to time one rotation. It is somewhat miraculous [calling Fr G!], if you ask me, that we can set our clocks to one rotation of the Earth and expect such constancy of sunrise, sunset, etc. We get used to it, and then it becomes a mystery to be solved at winter solstice as to exactly what is going on.


That's where I am with this, anyway. Feel free to tell me I am all wet.
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weaselman
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January 18th, 2012 at 6:31:52 AM permalink
Quote: odiousgambit

We here on Earth expect the Sun to be at that same spot 24 hours later. Why is that? Because the Earth returns to this spot in the nature of its rotation speed! This has to be true! [edit: currently I believe that this must be true if it holds after a great number of rotations and the Earth has moved along on its orbit] This apparently is very common, the study of it has a name: analemma. There must be a reason why a planet in a stable orbit tends to have a rotation that does this.



It actually does not return to the same spot (thus, the analemma). It would only be the case if the orbit was a perfect circle, and there was no axis tilt (then analemma would be just a single dot). Each of these factors alone results in a fairly simple sinusoidal drift in the daily sun position on the sky, but when they get superimposed on each other, the result is a pretty complicated curve.

Quote: odiousgambit

Couldnt there be such planets that don't coordinate rotation speed with a similar daily view of the host star? In a few rotations of said planet, sunrise could easily be changed to what had been the time of midnight, etc, if someone had a clock that was set to time one rotation.



Indeed. This difference between the "true solar time" and "mean time" (roughly what the clock shows) is called equation of time. On Earth, the largest value for it is only about 16 minutes, but that is because the axis of rotation is not tilted all that much (only about 23 degrees), and the orbit is only slightly elliptical.

Uranus is a notable example of a planet with a very significant axis tilt (it literally can be said to be "lying on its side"), and the time equation on it often reaches several hours. Conceivably, there could be places and times there, where noon happens "at night" (before sunrise or after sunset). I don't know if this is really the case there, but it very well could be.
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FrGamble
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January 18th, 2012 at 2:37:08 PM permalink
I find all of this stuff pretty miraculous!

I hope this doesn't take us too much off on a tangent but we have a parishioner who is working on the James Webb space telescope and he gave a presentation to the parish the other day. It was really interesting. Lots of cool stuff was talked about, including the possibility of seeing back to the beginning of time. However, we spent a lot of time talking about where this telescope will orbit. It will be in a L2 orbit. This was described as being a million miles away from the Earth and on the night side of Earth (away from the sun). It was also shown to not only orbit that far away from Earth but also have what looks like a mini orbital movement of its own. Can anyone shed some light on this type of orbit for me? Also how in the world could a French scientist in the year 1772 have discovered this possibility? Cool stuff.
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January 18th, 2012 at 3:29:26 PM permalink
There is a pretty good illustration and discussion of the L2 orbit for this satellite at this web site. I think it is possible for the device just to follow the path of the L2 point around the sun, staying on the dark side of the earth, but there is probably some improvement in stability by letting it "wobble" in a controlled mini-orbit.

As for how Lagrange could have found the solutions to the 3-body problem, well, there were a number of pretty clever mathematicians a few centuries ago -- Newton, Euler, the Bernoullis, Keppler, etc. -- and Lagrange was one of them. Imaging what they could have done with today's tools!
odiousgambit
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June 24th, 2012 at 12:36:34 AM permalink
If we mine asteroids, I've heard the most valuable mineral will be water, if the rock has some. It's the incredible value of water in space vis a vis on Earth. Didn't we discuss recently that water is where they get oxygen in space?

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Face
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January 26th, 2013 at 12:54:54 AM permalink
Back again, and I got another ice problem. It was all fun and games laughing with Ayecarumba a few days ago, but now I'm starting to get nervous...

I have this tank, see. It's about 4' x 2' x 1.5', a tick over 100gal. I usually keep native fish and invertebrates over the summer and release them in fall, but this year I'm attempting a crayfish farm so it's still full. In the fall, the water evaporated to the point the pumps didn't work, and I left it. About 2 weeks ago, it started to freeze.

I immediately added a bunch of hot water to both melt the ice and raise the levels, and it worked fine. The <1" of ice went away and I got the pumps running again. But this last week or so, we got hit with a nasty cold front and even with the pumps running it began to freeze again.

I was laughing with Ayecarumba and posting pics, thinking it was no big deal. At the time, I had about 1.5" of ice that completely covered both sides, both ends, the bottom, and the top; it was just one, big, ice box of water. It was kind of neat to look at, and I wasn't yet scared.

By the time I got done posting about it and browsing DT/WoV, the ice was 2". By the time I woke up 8 hours later, it was 4". When I woke up this morning, the pumps were struggling. By this evening, the pumps were froze solid and ceased operation.

My question is - How does ice work? It has been my thinking that as the ice forms, it'll displace liquid water due to it's larger volume. As long as I keep some part of the surface open, the displaced water has somewhere to go and the tank pressure will not rise. My fear is that I got it all wrong, and I'm about to lose a lot of time, hundreds of dollars of equipment, and suffer a not-insignificant amount of water damage to my garage.

I got one pump running again and have a 6" open hole in the ice. None of the glass looks bowed nor do the seams seem to be pulling apart, but I imagine something like this will look completely fine right up until the point it explodes.

I'd much appreciate some direction. I'm kind of thinking I'm good, but it's too expensive a mistake to not ask. If you're rusty on your chemistry, then feel free to just take bets on whether my garage will stay dry until April ;)
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Nareed
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January 26th, 2013 at 4:55:21 AM permalink
It depends on temperature. Water is odd in that it expands when it freezes, yes, but as the ice gets colder it contracts. Also, if the tank is open, regardless of whether or not it's covered with ice, the opening provides an outlet for pressure.

Remember when soda came in glass bottles? Back then a sealed bottle left inside the freezer had a good chance of blowing up as the contents turned to ice and expanded. But an open bottle wouldn't blow up.
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kenarman
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January 26th, 2013 at 7:33:46 AM permalink
If you pumps and lines are plastic and are able to expand some when they freeze they should survive. If they are metal there is a good chance they will be hooped.

If you can keep any liquid water from becoming trapped under the ice so that it can't expand when freezing then the tank might survive. If you have trapped water that can only expand sideways then it will take the tank out.

I had an outdoor fish tank that I left outdoors every winter and let freeze but it wasn't glass. I always drained it to about 1/4 full at the end of the season.
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98Clubs
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January 26th, 2013 at 4:04:49 PM permalink
Ice works by the hydrogen-bonding system. Therefore at 39F water is at its maximum density. Below that temperature, hydrogen bonding becomes relevant and the density of water decreases until frozen. When water freezes into ice, any dissolved gasses (Soda bottles can EXPLODE) either remain trapped in the structure, or are driven out. Ice is especially dangerous in a closed container, as the resulting pressure increase due to the reduced density can bend steel, shatter glass, and ruin an ordinarily sound encasement. Fish tanks are not immune... as the side pressure can also break the glass (remember, you're fighting gravity in pushing that ice UP)
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Face
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January 26th, 2013 at 6:39:03 PM permalink
Thanks all for the replies.

I’m well aware of the power of ice in a closed system. Last year it buckled my driveway, 4” thick asphalt heaved and cracked. Must’ve lifted it 3” and cracked it 10’ long from one side to the other. I even had an engine block crack. That was a good 0.5” of steel and it split a 0.25” crack about 5” right down the sucker. Forget about forgotten pop cans in the freezer, I know how serious it can be. It’s entirely the reason I felt the need to ask.

If I’m reading y’all right, it seems your thoughts are mirroring mine. Basically, water is densest right before it freezes. Upon freezing, it expands to make an ice crystal, which is where any pressure would come from. This pressure, due to the open surface, shouldn’t build; the water will just go up and out the hole. In other words, since the water touching the glass is frozen, this “ice box” is already at its maximum volume. Any other pressure built as the result of additional freezing will be in the interior of the tank and will “squeeze the water”, so to speak. Since the water has somewhere to go (the hole in the surface), I’m good to go.

I only question your response, 98clubs, to do with gravity. Understand that it’s not a sheet of ice on the surface of the water. Every single side, all six of them, are frozen 4” - 5” inches thick. If I were to smash the tank with a hammer, I wouldn’t lose a drop. I’d just have a 100gal tank made out of ice =) Also, the water alone in a tank this size is pushing 900lbs. It’s certainly not a flimsy piece of glass. If it was indeed frozen solid and fully contained, I’ve no doubt it would shatter regardless. But since I got the hole in it, I’m hoping I’m ok (?)
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98Clubs
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January 26th, 2013 at 8:46:21 PM permalink
Pressure acts in 3 dimensions. If the Ice is anchored to the glass, then the forces are transmitted. A hole in the ice with liquid water under it is OK for the water, the ice, however, is still exerting force against the glass. Now if you cut the ice away from the glass so that it was truly floating in the water, then there is only the effect of mass.

My response about gravity presumed that A.) the ice was not floating, and B.) there was no hole in the ice to allow further expansion of the water.
Some people need to reimagine their thinking.
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