
The truth about toilet swirl (2015) [video] - ValentineC
https://www.youtube.com/watch?v=mXaad0rsV38
======
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!'.

~~~
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](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.

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

~~~
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](http://theroadchoseme.com/the-
equator)

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

------
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.

------
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.

~~~
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.

------
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...](http://www.nature.com/nature/journal/v207/n5001/abs/2071084a0.html)

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...](http://web.aeromech.usyd.edu.au/history-
chapters/C3%20ThermoFluids.pdf) ...

> 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!

------
rosstex
Are there more examples of synced videos like these?

------
euske
It has a better looking url:
[http://toiletswirl.com/](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](https://www.youtube.com/watch?v=mXaad0rsV38)

------
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.

