What-If 0050: "Extreme Boating"

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Re: What-If 0050: "Extreme Boating"

Postby gnutrino » Tue Jun 18, 2013 6:40 pm UTC

SemisolidSnake wrote:Of course, you'd have to melt your tungsten in the presence of an inert [atmosphere] since diamond combusts at much lower temperatures than it melts. And....those are the wrong types of engineering questions I'm supposed to be thinking about at this time of day. :)


Actually I don't think even an inert atmosphere would save you, Wikipedia says tungsten reacts with carbon at ~1500ºC and Tungsten Carbide has a melting point of 2870ºC. So I think the tungsten would react with the diamond and the resulting compound would melt. Someone should still totally try this anyway though, For ScienceTM.

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Re: What-If 0050: "Extreme Boating"

Postby Antior » Tue Jun 18, 2013 7:54 pm UTC

Meh, you can probably contain it in a sufficiently strong electromagnetic field. That's how they contain nuclear fusion plasmas (although those are charged so easier to contain with electric fields) and levitating frogs (which aren't commonly charged).

Also @ video of mercury 'destroying' aluminium: Airplanes have lots of aluminium in them. In case you were wondering, this is the reason why you aren't allowed to take mercury with you on a flight.

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Re: What-If 0050: "Extreme Boating"

Postby cjmcjmcjmcjm » Tue Jun 18, 2013 9:13 pm UTC

BeerBottle wrote:When using liquid nitrogen to cool a vacuum trap (used to protect pumps from sucking in organic solvents), it is important not to let air into the trap before removing the liquid nitrogen. Otherwise you may notice your trap full of a nice blue liquid. Take this time either to marvel at the magnetic liquid oxygen you have condensed, perhaps holding a bar magnet up to the side of the flask, or otherwise run for your life as the whole thing is probably just about to explode.

This brings back nice memories of my undergrad research
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Re: What-If 0050: "Extreme Boating"

Postby PM 2Ring » Wed Jun 19, 2013 1:55 am UTC

I reckon you'd need very dense paddles to row on mercury. In high school, I once had the opportunity to attempt to submerge a cube of steel in a beaker of mercury (using my bare hands, of course). It was not easy to do.


Diadem wrote:Stick your hand in a jar of liquid nitrogen, hold it there for half a minute, take out your hand. Admire what is left of your hand.

No thanks. I have no qualms about briefly dipping my fingertips into liquid nitrogen, though I wouldn't submerge them for more than a second or two at a time. I've frozen rubber bands under LN just using my fingers, without incurring any damage. OTOH, having LN poured onto the palm of your hand isn't pleasant, even if your hand's held at a steep angle so that it runs straight off.


As for liquid helium, you'd have to be very careful with your boat construction, since that stuff leaks through gaps that are too small for air to get through. And the mean density of the boat has to be very low, since the density of liquid He is about 1/8 that of water.

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Re: What-If 0050: "Extreme Boating"

Postby gladiolas » Wed Jun 19, 2013 2:11 am UTC

Bismuth melts at 271.5 C, and the liquid is denser than the solid, like water and gallium. Wikipedia says silicon is also denser as a liquid than as a solid. It might be interesting to speculate on rowing through lakes of bismuth or silicon.

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Re: What-If 0050: "Extreme Boating"

Postby TranquilFury » Wed Jun 19, 2013 3:39 am UTC

I've seen liquid tungsten.

Through a welding hood, naturally.

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Re: What-If 0050: "Extreme Boating"

Postby Mikeski » Wed Jun 19, 2013 4:55 am UTC

gladiolas wrote:Bismuth melts at 271.5 C, and the liquid is denser than the solid, like water and gallium. Wikipedia says silicon is also denser as a liquid than as a solid. It might be interesting to speculate on rowing through lakes of bismuth or silicon.

The relative density of solid and liquid $material doesn't change how you'd row through it, though.

The only difference vs. materials without that property is you could row into a bismuth-berg or silicon-berg and re-enact the Titanic's last moments.

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Re: What-If 0050: "Extreme Boating"

Postby tups » Wed Jun 19, 2013 11:33 am UTC

Angelastic wrote:...<snip> because the fog you see when you pour out liquid nitrogen is made of liquid oxygen. The water does condense out of the air (as a solid) but that's not the thick fog you see.

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taemyr wrote:
tups wrote:The density of bromine is not "about the same as water". It is in fact very heavy, about 3100 kg/m³.


Wheras water is 1000kg/m³. So about the same.


By applying the same logic you may say that the density of Bromine is very nearly the same as that of liquid Gallium, and that the value of pi is just about identical to 10.

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Re: What-If 0050: "Extreme Boating"

Postby Vroomfundel » Wed Jun 19, 2013 12:07 pm UTC

Why all this negativity towards liquid nitrogen - after all, it's being used to treat skin diseases!
On a second thought, it might be because 'treat' is used in its broader meaning and is actually closer to 'burn the shit out of'

So yeah, it's contact with the skin is definitely unpleasant - ask my brother, who had a few dozens of warts removed with liquid nitrogen in a military hospital before his compulsory military service. It produces a strong burning sensation, disappearance of tissue and noticeable burn-like scar.
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Re: What-If 0050: "Extreme Boating"

Postby Copper Bezel » Wed Jun 19, 2013 12:15 pm UTC

tups wrote:By applying the same logic you may say that the density of Bromine is very nearly the same as that of liquid Gallium, and that the value of pi is just about identical to 10.

He also notes that gallium is "not anywhere near as dense" as mercury, when that's a factor of ~2, not ~3. So, yeah, odd. I mean, the approximation only needs to be precise enough for the purpose, so I wouldn't question the statement by itself, but the inconsistency seems odd. Maybe I'm thinking of it wrong - maybe it's more important to look at the total mass added per volume, rather than the ratios of the densities themselves. In that case, mercury would be the clear outlier, and gallium would be a slightly bigger step from bromine than bromine is from water.
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Re: What-If 0050: "Extreme Boating"

Postby orthogon » Wed Jun 19, 2013 12:28 pm UTC

tups wrote:By applying the same logic you may say that the density of Bromine is very nearly the same as that of liquid Gallium, and that the value of pi is just about identical to 10.

Pi is kind of annoying, though, since logarithmically it's halfway between 1 and 10 so it's hard to know which way to round it. On the other hand, 2π is 10, as near as dammit. But that doesn't reckon with the usual uncertainty as to whether a factor of 2π should be applied at all to any given calculation of loop bandwidth, corner frequency etc. Given this, the approximation 2π~1 neatly sidesteps the need for careful thought and/or consultation of university notes.
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Re: What-If 0050: "Extreme Boating"

Postby Barstro » Wed Jun 19, 2013 1:11 pm UTC

Vroomfundel wrote:
Barstro wrote:I just saw that there is an entirely different Thread for What-Ifs. Is there a way for a Moderator to join them, or would other people just keep making What-Ifs in the Individual thread?

If by other people you mean me, who happenened to create them the last two times, then no - I won't be creating further threads here :-) still, what-ifs don't generate nearly enough traffic so our rudimentary discussion here is almost as large as the "official" one


I hope you don't think me disparaging your start of this, or any, thread. But not knowing how the programming of Forums works, I just wonder if things could be set up so that whether one starts in "What-If" or in "Individual", they ended up in the same thread for the What-If comic so that two different conversation streams did not happen.
Last edited by Barstro on Wed Jun 19, 2013 1:56 pm UTC, edited 1 time in total.

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Re: What-If 0050: "Extreme Boating"

Postby 3rdtry » Wed Jun 19, 2013 1:28 pm UTC

It's a real shame that mercury is toxic. It's so much fun to play with.

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Re: What-If 0050: "Extreme Boating"

Postby Copper Bezel » Wed Jun 19, 2013 1:40 pm UTC

It happens with individual strips anyway, since there are often two people jumping to be the first to post on a new comic.

New subforum is new; people will get used to it with time.
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Re: What-If 0050: "Extreme Boating"

Postby Vroomfundel » Wed Jun 19, 2013 6:14 pm UTC

Shame indeed. Maybe on another planet an intelligent civilization has, say, three different naturally occuring liquid substances and they can splash about in all three. Maybe they even have seas of those three different liquids, with each global power having three independent navies for the three types of sees, with only a limited fleet of "amphibia" vessels, which are either universal or convertible (both would exist) and can sail all seas, or at least two types thereof, but will be vulnerable on all as they won't be as well optimized for the particular enviornment.

Meanwhile, we're stuck on the boring earth, with just water and heavy water. But wait, heavy water is in fact quite cool! We don't have seas of it but at least enough to conduct any of the discussed experiments
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Re: What-If 0050: "Extreme Boating"

Postby teelo » Wed Jun 19, 2013 6:52 pm UTC

What would it be like to row a rowboat on water?

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Re: What-If 0050: "Extreme Boating"

Postby Timecubist » Wed Jun 19, 2013 8:26 pm UTC

So my friend at Rolls Royce posed an interesting question - If you dropped Tungsten on Lava, would it be crystalized or amorphous upon freezing? I was leaning towards Amorphous, but I can't find the critical cooling temperature of Tunsten, so I thought I'd ask if anyone had a better idea?

My logic is that Tunsten = 3400o , lava is ~1600 o ..which is greater in difference then lava vs outer space.

Of course , I dont know if dropping lava in outer space would cause it to be Amorphous either.

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Re: What-If 0050: "Extreme Boating"

Postby Pfhorrest » Wed Jun 19, 2013 9:38 pm UTC

teelo wrote:What would it be like to row a rowboat on water?

Well for starters, water has a melting point of 273 K, which is hot enough that many substances which are inert at ordinary interstellar temperatures can react violently. It is also a powerful solvent, so you'd best hope your boat isn't made of something like sodium chloride...
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Re: What-If 0050: "Extreme Boating"

Postby indemoveritas » Wed Jun 19, 2013 10:20 pm UTC

I join your forum to comment on a topic I know well.
Please treat me kindly.

tups, you are correct. The fog above an open surface of liquid nitrogen is condensed water vapor.

Liquid nitrogen will kill you by asphyxiation, freezing, or physical explosion when contained, but not by direct chemical reaction.
Liquid oxygen will kill you by freezing or physical explosion, and also by supporting combustion.
The concentration of oxygen in liquid oxygen is about 5000 times that of air.
Demonstrating the reactivity of liquid oxygen is nerve wracking.
The order of addition of fuel, heat and LOx is critical; in that order, combustion. Rapid, unquenchable combustion.
Add fuel, LOx and then heat, and get deflagration or explosion.
Spilling LOx on oneself is a potential example of the second case, with the heat provided by the friction of frantically shedding a lab jacket.

Not for the squeamish, or those disturbed by cognitive dissonance,
a USN training video about handling liquid oxygen, Man from LOX on youtube.

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Re: What-If 0050: "Extreme Boating"

Postby rmsgrey » Wed Jun 19, 2013 11:02 pm UTC

Pfhorrest wrote:
teelo wrote:What would it be like to row a rowboat on water?

Well for starters, water has a melting point of 273 K, which is hot enough that many substances which are inert at ordinary interstellar temperatures can react violently. It is also a powerful solvent, so you'd best hope your boat isn't made of something like sodium chloride...

...or, worse, a nice ductile metal like Sodium...

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Re: What-If 0050: "Extreme Boating"

Postby mcvoid » Thu Jun 20, 2013 12:20 am UTC

Thank you for fixing the RSS feed so I could read this inside Mail!

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Re: What-If 0050: "Extreme Boating"

Postby roband » Thu Jun 20, 2013 9:04 am UTC

He talking about Jaws?
Bigger boat and that?

He doesnae say that.
Chief Brody and the boat? I've seen it a hundred times, it does my head in. Brody sees Jaws and he says to Quint, "YOU'RE going to need a bigger boat," not, "WE'RE gonna need a bigger boat."

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Re: What-If 0050: "Extreme Boating"

Postby Red Hal » Thu Jun 20, 2013 9:17 am UTC

Alright, angry Charlie; YOU'RE gonna need a bigger hutch, 'cos I've just seen a massively geometrically-modified rabbit.
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Re: What-If 0050: "Extreme Boating"

Postby orthogon » Thu Jun 20, 2013 10:54 am UTC

In his accent, the vowel sounds in "we're" and "you're" are pretty indistinguishable, and the cigarette between his lips would inhibit his ability to distinguish "w" from "y". Add to that the mumbling, the lack of stress, the incidental music etc... I've listened to it several times and whilst I lean towards "you're" I don't think it's clear-cut. Is there some Word of God or similar on the matter that I don't know about?
xtifr wrote:... and orthogon merely sounds undecided.

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Re: What-If 0050: "Extreme Boating"

Postby roband » Thu Jun 20, 2013 11:00 am UTC


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Re: What-If 0050: "Extreme Boating"

Postby orthogon » Thu Jun 20, 2013 12:28 pm UTC

roband wrote:We're (you're?) referencing this http://www.youtube.com/watch?feature=pl ... QRU#t=291s :)

Right you are. Thanks. I now realise that the whooshing I could hear was the sound of a pop culture reference sailing over my head :)
All the same, what does he say? "We're" or "you're"?

[EDIT: typo]
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xtifr wrote:... and orthogon merely sounds undecided.

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Re: What-If 0050: "Extreme Boating"

Postby eran_rathan » Thu Jun 20, 2013 12:44 pm UTC

Timecubist wrote:So my friend at Rolls Royce posed an interesting question - If you dropped Tungsten on Lava, would it be crystalized or amorphous upon freezing? I was leaning towards Amorphous, but I can't find the critical cooling temperature of Tunsten, so I thought I'd ask if anyone had a better idea?

My logic is that Tunsten = 3400o , lava is ~1600 o ..which is greater in difference then lava vs outer space.

Of course , I dont know if dropping lava in outer space would cause it to be Amorphous either.



It would tend to be very fine-grained crystals, assuming mafic lava (olivine) for simplicity.
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Re: What-If 0050: "Extreme Boating"

Postby roband » Thu Jun 20, 2013 12:45 pm UTC

orthogon wrote:
roband wrote:We're (you're?) referencing this http://www.youtube.com/watch?feature=pl ... QRU#t=291s :)

Right you are. Thanks. I know realise that the whooshing I could hear was the sound of a pop culture reference sailing over my head :)
All the same, what does he say? "We're" or "you're"?
Gary initially says "We're".

Angreh Charleh corrects him to "You're"

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Re: What-If 0050: "Extreme Boating"

Postby Klear » Thu Jun 20, 2013 12:46 pm UTC

Pfhorrest wrote:
teelo wrote:What would it be like to row a rowboat on water?

Well for starters, water has a melting point of 273 K, which is hot enough that many substances which are inert at ordinary interstellar temperatures can react violently. It is also a powerful solvent, so you'd best hope your boat isn't made of something like sodium chloride...


Hopefully nobody would be so foolish to even have a whole lake filled with dihydrogen monoxide, right?

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Re: What-If 0050: "Extreme Boating"

Postby orthogon » Thu Jun 20, 2013 12:49 pm UTC

roband wrote:
orthogon wrote:
roband wrote:We're (you're?) referencing this http://www.youtube.com/watch?feature=pl ... QRU#t=291s :)

Right you are. Thanks. I know realise that the whooshing I could hear was the sound of a pop culture reference sailing over my head :)
All the same, what does he say? "We're" or "you're"?
Gary initially says "We're".

Angreh Charleh corrects him to "You're"

That you misunderstood my question for comic effect, I can handle; applaud, even. What's vexing is that you quoted me just before I fixed my typo. :oops:
xtifr wrote:... and orthogon merely sounds undecided.

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Re: What-If 0050: "Extreme Boating"

Postby PhysProf » Thu Jun 20, 2013 3:05 pm UTC

One thing left out of the liquid helium section: when a superfluid (below 1.9K), it has zero viscosity. That will make it impossible to row your boat - the oars will slip through the LHe without any resistance at all. No resistance --> no force on oar, by Newton's 3rd law. LHe is *very* neat stuff: zero viscosity, infinite thermal conductivity, etc.; just don't try and row across a lake of the stuff.

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Re: What-If 0050: "Extreme Boating"

Postby socom » Thu Jun 20, 2013 3:36 pm UTC

rmsgrey wrote:
Pfhorrest wrote:Well for starters, water has a melting point of 273 K, which is hot enough that many substances which are inert at ordinary interstellar temperatures can react violently. It is also a powerful solvent, so you'd best hope your boat isn't made of something like sodium chloride...

...or, worse, a nice ductile metal like Sodium...


Oh, a sodium boat would be fun... :mrgreen:

Speaking of alkalis, cesium has a melting point only slightly above room temperature (it melts in your hand, provided of course it's in a safe container - otherwise it melts your hand). A cesium lake would be pretty easy to row a boat in, at least until it exploded from contact with air moisture. :wink:

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Re: What-If 0050: "Extreme Boating"

Postby Red Hal » Thu Jun 20, 2013 4:01 pm UTC

It is, indeed, "you're".
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Re: What-If 0050: "Extreme Boating"

Postby KarenRei » Fri Jun 21, 2013 10:25 am UTC

Oh, a sodium boat would be fun... :mrgreen: [/quote]

I'd expect, for the most part, the boat to float with little resistance due to a thin layer of hydrogen forming beneath it. I'm not sure how much of a problem you'd have with ignition or the boat "skipping" about, and I'd expect it'd depend on your design.

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Re: What-If 0050: "Extreme Boating"

Postby Pfhorrest » Fri Jun 21, 2013 4:35 pm UTC

PhysProf wrote:One thing left out of the liquid helium section: when a superfluid (below 1.9K), it has zero viscosity. That will make it impossible to row your boat - the oars will slip through the LHe without any resistance at all. No resistance --> no force on oar, by Newton's 3rd law.

I'm not superfamiliar with superfluids, but something seems intuitively wrong about this, so maybe you can explain.

Zero viscosity means that it won't "stick" to its container or objects passing through it at all, and therefore won't have any friction as it flows through and around things. But certainly if you shot a high-velocity column of the stuff at something (like water out of a fire hose), that something would still get knocked back as the the molecules bounced off of it and changed direction, imparting their momentum into the target, yes? It wouldn't magically flow around anything you shot it at and pass by unfelt by the target?

If so, then you should still be able to paddle through a lake of the stuff. The lake won't "grab" the paddle at all, so you'll have less traction to push the fluid around, but you will still be deflecting molecules as you intersect the paddle with their direction of motion, changing that direction and the momentum of the paddle (and thus you and thus the boat you're sitting on) in the process, too.
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Re: What-If 0050: "Extreme Boating"

Postby socom » Fri Jun 21, 2013 5:01 pm UTC

Pfhorrest wrote:If so, then you should still be able to paddle through a lake of the stuff. The lake won't "grab" the paddle at all, so you'll have less traction to push the fluid around, but you will still be deflecting molecules as you intersect the paddle with their direction of motion, changing that direction and the momentum of the paddle (and thus you and thus the boat you're sitting on) in the process, too.


Hmm, I hope we can get a proper quantum physicist to comment but I do believe that - when it comes to superfluids - it is no longer correct to treat the substance as a collection of molecules. Rather, the entire volume of the fluid is in a single quantum state and has zero entropy which means that its molecules cannot move with respect to one another.

That's at zero point energy, though. In practice you can have a little entropy in your superfluid (which is why superfluid can exist at above-zero temperatures); in these conditions it sort of exists as a superposition of being a superfluid and not being a superfluid (yeah, quantum physics is weird like that). The "ordinary" component of this state could presumably do the things mentioned in your comment but as the temperature drops the mechanism becomes less effective until, ultimately, the ordinary phase is completely gone and no further movement is possible.

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Re: What-If 0050: "Extreme Boating"

Postby socom » Fri Jun 21, 2013 5:21 pm UTC

KarenRei wrote:
socom wrote:Oh, a sodium boat would be fun... :mrgreen:


I'd expect, for the most part, the boat to float with little resistance due to a thin layer of hydrogen forming beneath it. I'm not sure how much of a problem you'd have with ignition or the boat "skipping" about, and I'd expect it'd depend on your design.


Forget fire; even a coin-sized chunk of sodium thrown into water will explode, and larger chunks will explode spectacularly. The biggest "sodium party" I've ever heard of involved a four-kilogram block which exploded with the force of a depth charge (you can read about it on Theodore Gray's WPT website; not sure what the forum policy is for posting links but it's easy to google).

With a boat-sized chunk of sodium an explosion would be inevitable, and it would be massive. I wouldn't expect the cruise to last more than a few seconds - expect an earth-shaking explosion throwing chunks of the boat every which way. These would then trigger more explosions as they splashed down hundreds of meters from the original blast site. Bottom line is, you *really* wouldn't want to be in (or for that matter, anywhere near) the boat. :mrgreen:

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Re: What-If 0050: "Extreme Boating"

Postby Pfhorrest » Fri Jun 21, 2013 6:15 pm UTC

socom wrote:Hmm, I hope we can get a proper quantum physicist to comment but I do believe that - when it comes to superfluids - it is no longer correct to treat the substance as a collection of molecules. Rather, the entire volume of the fluid is in a single quantum state and has zero entropy which means that its molecules cannot move with respect to one another.

Even so, even if we have to treat the fluid as a continuous substance instead of a bunch of discrete particles, if you can deflect the fluid then it can deflect you as well, can't it? For analogy, say you're in a room where all the walls and floor and ceiling are frictionless. You have no way to grab onto the floor and stop yourself from sliding along it, but when you eventually hit one of the walls you still bounce off of it, right? It seems that a zero-viscosity fluid should function similarly: it will slip across surfaces without any friction but it will still turn around when it collides with something, in turn pushing that something.

I mean, if you swatted your paddle at the superfluid, it wouldn't just pass through like there was nothing there, would it? It wouldn't come out "wet", because none of the fluid would stick to it, but it would still impact and push the paddle back, right?
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Re: What-If 0050: "Extreme Boating"

Postby Lazy Tommy » Fri Jun 21, 2013 10:35 pm UTC

rhomboidal wrote:hehe, I just hope the "third sound" isn't the "brown note."


There's also "fourth sound" and "fifth sound" in superfluids. I first read about them in the article on liquid helium in the McGraw-Hill Encyclopedia of Physics. The topic seems to be very obscure -- even Wikipedia barely mentions it and it has no main entries for it.

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Re: What-If 0050: "Extreme Boating"

Postby PhysProf » Sat Jun 22, 2013 2:57 am UTC

socom wrote:
Pfhorrest wrote:If so, then you should still be able to paddle through a lake of the stuff. The lake won't "grab" the paddle at all, so you'll have less traction to push the fluid around, but you will still be deflecting molecules as you intersect the paddle with their direction of motion, changing that direction and the momentum of the paddle (and thus you and thus the boat you're sitting on) in the process, too.


Hmm, I hope we can get a proper quantum physicist to comment but I do believe that - when it comes to superfluids - it is no longer correct to treat the substance as a collection of molecules. Rather, the entire volume of the fluid is in a single quantum state and has zero entropy which means that its molecules cannot move with respect to one another.

That's at zero point energy, though. In practice you can have a little entropy in your superfluid (which is why superfluid can exist at above-zero temperatures); in these conditions it sort of exists as a superposition of being a superfluid and not being a superfluid (yeah, quantum physics is weird like that). The "ordinary" component of this state could presumably do the things mentioned in your comment but as the temperature drops the mechanism becomes less effective until, ultimately, the ordinary phase is completely gone and no further movement is possible.


Superfluids really are that weird - check out Wikipedia's section on liquid helium (I can't post the link, since I'm a noob).

Superfluids are a single quantum state of all the atoms, and their collective energy, linear momentum, and angular momentum are likewise quantized. This means that when you put a little paddlewheel in superfluid LHe and spin it, it spins without any resistance at all - it can't start a collective motion of the fluid. Similarly, trying to whack it with a paddle won't do any good, for the paddle can't start a collective motion. This means the LHe really doesn't interact with the paddle at all, as non-classical as that sounds.


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