HN Theater @HNTheaterMonth

It does! https://www.youtube.com/watch?v=mXaad0rsV38

Definitely has an effect - https://www.youtube.com/watch?v=mXaad0rsV38

Whether or not it meets the standard of 'appreciable' is subjective i suppose.

⬐ Jedd

This is poor science, and very weak support for 'definitely'.

I didn't watch this all the way through this time, but I do recall watching it back in 2017 when it was posted -- IIRC he did this experiment <sic>, asserting all variables were controlled for, but in a garage with leaky walls, on a poorly insulated floor, with no control test and only once, in one location.

Consider that hurricanes don't form within 5 degrees (~ 550km) of the equator - which gives a good indicator of just how strong (or not) the Coriolis effect is.

⬐ thatcat

Hurricanes don't form near the equator due to the equatorial subduction zone.

⬐ Jedd

Hmm, I hadn't heard this claim before.

And searching for neutral questions like 'Why don't hurricanes form near the equator' reveals consistently Coriolis Effect explanations.

Wikipedia's article on subduction makes no mention of weather events at all.

Do you have any citations for your claim?

⬐ mattbk1

Perhaps something relating to this was meant? https://en.wikipedia.org/wiki/Thermohaline_circulation

⬐ thatcat

My mistake, I was misremembering some things related to the the Inter Tropical Convergence Zone from geography class 10 years ago.

As an aside, the ITCZ is a trigger for hurricanes when it moves too far from the equator.

https://www.eoas.ubc.ca/courses/atsc113/sailing/met_concepts...

⬐ emmelaich

There has been experiments, published in Nature in the 60s that did confirm an effect. I personally know one of the authors.

The tub they used was something like 60cm deep and 3 or 4m in diameter.

I can pull up the reference if you like.

It wasn't perfectly reproducible though; in classic fashion when they demonstrated for a local newspaper (Sydney Morning Herald) the water went the "wrong" way.

I have given the url / details here in HN a few years back.

⬐ Jedd

That it's not perfectly reproducible should be setting off alarm bells, even for people who would really like this effect to work at the scale of a few metres.

⬐ steerablesafe

It's probably reproducible in the sense that if you do it a 100 times you get a strong statistically significant effect. They were probably unlucky that day.

⬐ emmelaich

I'm not sure that any experiment is perfectly reproducible. Though I would be very surprised to see a hurricane going the wrong way at mid-latitudes!

Anyway, we're in agreement that it is a thing, and we just need a big enough tub to demonstrate it, correct?

The force is perfectly calculable, and we can compare that to the effect of, say, a breeze across the top.

ps. the reference https://www.nature.com/articles/2071084a0

"Published: 01 September 1965 The Bath-Tub Vortex in the Southern Hemisphere LLOYD M. TREFETHEN, R. W. BILGER, P. T. FINK, R. E. LUXTON & R. I. TANNER

pps. my earlier mention https://news.ycombinator.com/item?id=15122988 Nature volume 207, pages1084–1085(1965)"

⬐ Jedd

Yeah, I can't access that Nature link from 1965.

AIUI the math is that the delta in acceleration across a 1m bathtub north-to-south would be 1x10-8 m/s/s due to Coriolis ... so your starting conditions would have to be at a level of perfection that I don't think anyone's achieved, certainly not some bloke in a drafty garage with a kiddy's wading pool one time.

I accept that in theory that delta definitely exists, but I don't accept that it can be, has ever been, observed at the tiny scales of a few metres, let alone the 100mm (toilet flushes) that's typically asserted by the faithful.

I accept that across dozens of kilometres we definitely do see this phenomenon as it generates consistent, hemisphere-dependent, large wind events (eg hurricanes) once you get a good way from the equator.

Genuine demonstration of this effect:

https://www.youtube.com/watch?v=mXaad0rsV38

⬐ imron

The real truth about toilet swirl is that toilets in Australia don't swirl, they flush: https://www.youtube.com/watch?v=X11zXXEgIes

⬐ djsumdog

When I lived in AU and later NZ, I'd get this question and I'd respond the same way. AU and NZ toilets are almost always dual-flush (dual flush toilets were invented in AU) and they push water quickly front to back, not in a swirl like US toilets.

I've also never clogged an AU or NZ toilet. Not to say you can't, just that it's much more difficult with their design.

⬐ sosborn

Does this mean I should be proud about my incident at an Auckland hotel 6 years ago?

⬐ djsumdog

I'm not sure if "proud" is the right word.

⬐ Double_a_92

Neither do they in Europe... It's probably just a 'murican thing.

⬐ Taniwha

and non-toilets have the hot tap on the other side potentially biasing things when they are filled

⬐ stephen_g

Yeah, American toilets are weird. First time I saw one (at LAX after flying in from Australia) I thought it was broken - firstly given the huge amount of water in it at the start, and then the way it fills up when you flush it! I really thought it was going to overflow.

⬐ trapperkeeper74

I guess people are proud of their excements and want to parade them around as long as possible by making it take an unnecessarily long time and wasting as much water as possible. It's like, to them, toilets should have a flush song and they need to selfie vlog dance about their "accomplishment" like saying "first."

⬐ grecy

I am from Australia, have been living in North America for 10 years.

I have also driven across the Equator twice - once in Ecuador[1] and recently in Gabon, West Africa[2].

It's funny to watch the guys standing on the Equator tricking tourists with a swirl of their wrist to supposedly demonstrate this effect.

I thoroughly enjoy watching the stars change as I progress from the Northern Hemisphere to the Southern, and the water direction slowly change.

[1] http://theroadchoseme.com/the-equator

[2] http://theroadchoseme.com/the-equator-gabon

⬐ euske

It has a better looking url: http://toiletswirl.com/

Actually, Veritasium merged the two videos into one because it is easier to watch on a smartphone. https://www.youtube.com/watch?v=mXaad0rsV38

⬐ emmelaich

All mention of Coriolis should refer to this 1965 Letter in Nature magazine titled "The Bath-Tub Vortex in the Southern Hemisphere"

http://www.nature.com/nature/journal/v207/n5001/abs/2071084a...

As you can read below, even with extreme care the Coriolis effect can be overwhelmed by very small perturbations such as how the lid is lifted.

http://web.aeromech.usyd.edu.au/history-chapters/C3%20Thermo... ...

> At Tom Fink’s invitation, Professor Lloyd M. Trefethen of Tufts University, USA, spent a short sabbatical in Mechanical Engineering in 1964/65. Already famous for his work on surface tension phenomena, he led us into a repeat of the experiments on the bathtub vortex that had recently been conducted by Ascher Shapiro at MIT. After much careful design, a circular tank of some 2.4m in diameter and 0.4m depth was constructed and installed in one of the subterranean dungeons of the old Peter Nicol Russell building. Carefully designed procedures and their diligent execution resulted in absolutely conclusive results that were published in Nature [Trefethen, et al, 1965). A re-enactment for the local media was a disaster: Bilger and Tanner muffed the removal of the covering baffles creating a great vortex in the water that then went out the wrong way. ‘Scientists baffled’ cried the media. We even made Time magazine!

⬐ tgarma1234

It's clickbait to generate youtube views. Seriously how many times have we seen this trick?

⬐ foobarbecue

How many times have you seen the baking soda / vinegar volcano demonstration? The more the better, in my opinion, and I'm a volcanologist.

⬐ tomxor

TLDW; They try toilets which dont work so they create a larger vortices in kiddy pools.

just lol, they are so excited... I do hope they realise that there was never any debate about the Coriolis effect being real, cos ya know... math. Only debate was that the effect is not strong enough compared to other forces acting on small vortices in fluids, i.e toilets.

⬐ aaron695

> Only debate was that the effect is not strong enough compared to other forces acting on small vortices in fluids, i.e toilets.

Pretty sure there's no debate here, it's not.

⬐ function_seven

It’s clear they know that. Now a lot of people who didn’t have a great way to learn both how the Coriolis effect works, and also how weak it is on smaller scales.

⬐ latch

Derek Muller, the Veritasium guy, has a PhD in physics and a focus on the use of media for physics education. What you're seeing is his (and Destin's) successful take on how to make learning fun.

⬐ beefman

Muller's PhD is in physics education, not physics.

⬐ degenerate

OK that was pretty cool. Props to these guys for taking such simple thoughts/ideas and generating interesting content. Youtubers like this are the modern-day Bill Nye. The faster we all 'cut the cord' and ditch TV, the faster we can force the return of quality creative content like this. Either because TV dies outright, or networks are monetarily forced to put effort into quality programming again.

⬐ criddell

Why would I want to cut the cord and ditch TV? Television is awesome. I wish I had time to watch more of it.

⬐ trapperkeeper74

Troll.

⬐ criddell

How is that a troll or even provocative? Last Sunday was the Game of Thrones finale and there was a lot of excitement over it. That's not because TV sucks and everybody should ditch it. Tonight I'll watch a baseball game on TV. Over the weekend I had it on more than usual because I was watching the Harvey news.

Television is wonderful.

⬐ trapperkeeper74

Either you're hillariously sarcastic or not the sharpest instrument trying to rationalize their undying, partisan team promotion for glowing consumption.

Assuming the former: GoT isn't "TV," it's multiplatform, third-party, ad-free, cable HBO.

How is:

- arranging your life around schedules of broadcasts

- sitting through long, pointless ads wasting one's limited life

- sitting in one place because a service isn't completely available except within an old, outdated, building subscription service framework

- watching local lazy or "must carry" propaganda or in-bubble-centric, watered-down, biased national/cable news that doesn't address real issues (VICE and Democracy Now are good)

"wonderful?" Is that anything like Trump "wonderful" or Apple "wonderful" when they charge $750 to "repair" a $0.25 part by throwing away a fixable board.

⬐ criddell

You have a very narrow definition of what constitutes television. It isn't 1978 anymore.

⬐ PhantomGremlin

The advantage of television channels and networks is they provide "curation". Someone needs to wade thru the crap and find the "quality programming" you desire.

Take the average Nova or Frontline episode. It's not cheap to produce. Do you think people could afford to put the work into making shows like that if all they could count on was the crumbs that Google threw at them from page views on Youtube?

And even if the funding could be solved, how would you discover this programming? There are very few HN submissions that ever get much notice. And the HN crowd is not nearly big enough to provide enough Youtube eyeballs to actually fund "real" programming.

⬐ rosstex

Are there more examples of synced videos like these?

⬐ Jedd

I really can't tell if this is an expensive and sophisticated troll, or they're genuinely bewildered.

Using a graphic showing several thousand kilometre-wide pool with one edge touching a pole is disingenuous. At that scale, yes, you're going to observe Coriolis effect.

Hurricanes don't form within five degrees of the equator -- that provides a useful data point for the lower end of the scale required to see the effect.

Sydney's 34 degrees south, but the velocity delta at 1 metre distance would be dwarfed by various other environmental factors and starting conditions. (Temperature deltas and wind, especially for the outdoor pool, vortices produced by the elbow close to what looks like a 19mm outlet, texture on the PVC liner, etc.)

Plus of course in any dual-pool-emptying experiment, there's a 25% probability of this result.

I'm miffed that a single experiment gets described as 'this is science, dude!'.

⬐ yladiz

Of course you couldn't take what they did and publish it, but it's good enough to explain a concept to a large group of people (and maybe, sure, on such a small scale it's not possible and was that 25% chance of happening). Don't forget that the videos are for both entertainment and for learning purposes and, while potentially dubious, it is still an experiment and I trust these two guys (both of which have Ph.Ds in some form of physics, I believe) to perform the experiments well. I would absolutely consider what they did popular science.

⬐ ngrilly

The video description says: "For the record Destin and I repeated the experiment 3-4 times each in each hemisphere and got the same results every time."

⬐ quickthrower2

25% for independent yes but not conditional.

Given the result was shown on the video there is a 100% probability it would happen for the attempt shown on the video.

⬐ mchahn

"I'm miffed that a single experiment gets described as 'this is science, dude!'".

A single data point is still a data point and this is still science.

⬐ Jedd

> A single data point is still a data point and this is still science.

Both presenters are enthusiastic and engaging, undeniably. And yes, this is a data point.

But this isn't science.

Partly because they claim they've 'proved it because we eliminated variables' (3'57"), when they clearly haven't.

Partly because one of the basic tenets of science is repeatability. As I noted above, there's a 1 in 4 chance of getting this result if you assume equal probabilities of clockwise / counter-clockwise. That assumption should be the starting point of any experiment around this effect.

Food colouring should have been put in - for some of the repeated experiments at least - before the valve was open, to confirm the water was in fact still motionless. (Or to show that it wasn't.)

Similarly that little match-stick cross on one of the pools - those should have been present on both pools, probably several of them, spread around the surface (though surface motion is not necessarily indicative of sub-surface movements).

I could go on.

⬐ djsumdog

It really isn't science. It's pop science, and although I do enjoy the Smarter Every Day guy, I do agree it's kinda disservice to understanding how things work. They should have repeated the experiment; gotten some sensor experts to see if they could quantify the "stillness" of the water, etc.

We've had pop science before (Mr Wizard anyone?), and we're just seeing more of it today. Real science is slow, methodical and doesn't infer causality from one experiment. It says, "Maybe x caused y; let's do some more tests." It's the QA person who says "Happy path works. Let's break it and see if we can inject some Javascript."

Bill Nye is a mechanical engineer/comedian/kids host. Tyson is physicists. They're smart, but they're not experts on everything.

Like I said, I like these guys, but I realize it's not science. It's half entertainment/half makes you think. In these videos it's fun, but in the political arena, _science_ presented this way can be weaponized:

https://www.youtube.com/watch?v=yecefLsE44U

⬐ poopchute

"They should have repeated the experiment;"

From the video description:

"For the record Destin and I repeated the experiment 3-4 times each in each hemisphere and got the same results every time."

⬐ Jedd

That wasn't mentioned in the video, so I missed that (I usually avoid clicking 'read more' on youtube descriptions).

'3-4 times' sounds a bit wobbly -- I'm hoping that they meant they repeated it 3 times in one place, 4 in the other.

⬐ yladiz

I agree about Bill Nye, that he's more of a science educator than expert about any one specific topic, but Tyson is definitely an expert on astrophysics. He talks about a lot of stuff that he isn't an expert in because he's a popular guy, and for that reason I'm not very fond of his speaking engagements, but it's not fair to say he's not an expert at anything.

⬐ Jedd

I'm aware that I'm likely coming across as curmudgeonly.

My other half is a science educator, so I'm also very aware of the problems of getting kids (or even adults) excited about science.

On the other hand, I don't like the pseudo-science cruft the media and our society is full of, and I suspect there's some vague links between misrepresenting what the scientific method actually looks like, and people taking advantage of that growing murkiness.

I'm not questioning the credentials of these guys. Just the validity of this ersatz experiment.

> ... gotten some sensor experts to see if they could quantify the "stillness" of the water, etc.

They did have some archetypal (glasses-wearing) geek do a quick sound bite towards the beginning describing the effect being observed at small scales as 'bunk', but that's all we get from that side of the argument.

Interestingly in the video you can clearly see there's direct sunlight hitting one side of the indoor pool, and parts of the outdoor one. And during the time lapse section of the video, you can see surface debris on the indoor pool swirling around.

If the Coriolis effect worked at this scale, then you'd see consistent circular motion of water in these sized tubs even without emptying.

⬐ christophilus

I'm pretty sure one of them has a PhD in physics, and the other is a rocket scientist (I think for NASA). So, these guys understand science. What they do in their YouTube videos is bring science to the masses-- not always in the most disciplined form. They've interviewed some of the world's leading scientists, have taught Neil deGrasse Tyson a thing or two about hellicopter physics, etc. I think they are doing a lot of good, in the same vein as Bill Nye.