Randomness thread, part two.

[Poopadoop]

Dog after eating weed brownies.

[Poopadoop]

"One humanely culled alpaca is a tragedy, 132,000 Covid deaths in agony is a statistic."

https://www.bbc.co.uk/news/uk-england-bristol-58255378

[MadMojoMonkey]

One woman was briefly arrested after spraying officers with a water pistol, but was quickly de-arrested.

LOL. Don't try that in the states, lady. I don't think de-arrested is a thing, here.

More than 140,000 people from around the world had signed a petition addressed to Prime Minister Boris Johnson to stop Geronimo's destruction.

LOLOL. WTF?! The PM is supposed to change the law so one diseased llama can continue to contribute what exactly to the economy?

"around the world" C'mon, hoomanz... it's great that you care, but try to care about something less stupid.

[Poopadoop]

Have you seen the alpaca? He is (or least he was) pretty cute.

Otherwise yeah, fuck off people and get a life.

What was weird about that is when they went to get him, he was in a stable with other alpacas. Isn't the idea of the cull to stop the spread of the disease? If it is, why wasn't he quarantined away from other animals, and if he wasn't, why don't his stable mates have the disease too?

[boost]

Have you seen the alpaca? He is (or least he was) pretty cute.

Otherwise yeah, fuck off people and get a life.

What was weird about that is when they went to get him, he was in a stable with other alpacas. Isn't the idea of the cull to stop the spread of the disease? If it is, why wasn't he quarantined away from other animals, and if he wasn't, why don't his stable mates have the disease too?

Llamagate.

I bet you could make an inadequate but livable income by spearheading the conspiracy with a youtube feed/chan presence.

[Poopadoop]

Llamagate.

I bet you could make an inadequate but livable income by spearheading the conspiracy with a youtube feed/chan presence.

Another one for Ong if none of the bitcoin/fruit picking/bartender/truck driver/Amazon stocker plans don't pan out.

[OngBonga]

I bet poop thinks about me every day when he gets up in the morning and goes to work.

[Poopadoop]

I think about you all day every day, am considering quitting my job so I can devote more time to reading your posts.

[MadMojoMonkey]

I just think ongie is the best and stuff. I think about him as often as I think about my cats, I suppose. In that it's probably more than most but less than a few.

Hey, ongie... are you secretly cats? That might explain a few things, actually.

[OngBonga]

No, I'm secretly dogs.

[Poopadoop]

This is a cool one.

[MadMojoMonkey]

I am a fan. I hope his pace of releasing videos picks up again. He just upgraded to a bigger lab space and from the looks of this video, it's very nice.

I mean... the kid making deadly vapors in your garage is fine and all, but it's still nice when they grow up and get their own chem lab to make deadly vapors in. You know.

Did you see the one where he turned toilet paper (that's bog roll to you Brits) into alcohol?

[Poopadoop]

Yeah, that was a good one too.

[oskar]

Happy 20th 9/11 to the last murican on the site!

[oskar]

I wonder how the maga chuds are feeling now that Biden was the one to end the war after their guy got cold feet.

[oskar]

[Poopadoop]

^^^ That is sooooo cringe.

[MadMojoMonkey]

I'd say it's crass to say "Happy [anniversary of tragedy]" but I mean... we already have Thanksgiving, so ...

Thanks, I guess..?


@ hotel : 30 minutes of muffins in remembrance of those lost lives.
WTF?

[oskar]

Thanks, I guess..?

You're welcome!

You know what they say about tragedy and time... you let enough time pass and James Cameron will write a love story about two young lovers being separated by the towers, and even though the ending will be sad, true love will transcend... only if one dies of course, because otherwise those two would have been over each other after a weekend in NY. Talking about the movie. Titanic was heading for NY. Coincidence?

[OngBonga]

Isn't Oskar Austrian? I'll have to mark my calendar to remind myself to wish him a Happy Hitler's Birthday.

[oskar]

You missed it this year. You should set a reminder.

[Poopadoop]

The sound is grating as hell, but the visual is bitchin'.

https://twitter.com/Rainmaker1973/st...15418133544965

[OngBonga]

Very cool. I had the sense to minimise the volume before playing it. Good job, I think he found the brown note.

[MadMojoMonkey]

Chladni plates are so cool.

I could go on for hours about standing waves. I can't fully explain the patterns on that plate without seeing how it's supported underneath.

Like, when he does the first and third patterns, he's rubbing the plate with one hand and holding the edge with the other hand.
Where he rubs creates an anti-node - a location where the vibrations add up constructively.
Where he holds creates a node - a location where the vibrations add up destructively.

The second pattern he makes he's not touching the edge, so the entire edge becomes an anti-node, and a circular node forms.

[OngBonga]

I'm no expert obviously, but my take is that the pattern is purely a product of the pitch of the sine wave. He's using different tools to create different sine waves. Touching the table will have a dampening effect but won't change the pitch.

I presume the nodes and antinodes are caused by the vibration of the air, not the table. The table is causing the air to vibrate, and that shapes the air, with the nodes being low pressure regions and the antinodes being high pressure. The powder tends towards low pressure when it vibrates.

That might be completely wrong though.

[MadMojoMonkey]

These waves on this heavy metal plate are not significantly affected by the air. The waves that form on the plate are based on what patterns of standing waves can form. When he rubs the plate, he's injecting a huge range of frequencies. Those frequencies that can resonate on the plane take longer to dampen out. So the sand on the table is pushed away from locations with large vibrations and settles into locations with no vibrations.

The air above a drum head plays a significant role in the sound of the drum, but this table is very different. The drum head moves through "large" displacements, and move a volume of air as they do so (2 volumes, since the 2 sides of the drum head are typically separate).

There are 2 basic types of standing waves that can form on a circular sheet. Those with circular nodes and anti-nodes and those with diameter nodes and anti-nodes.
The waves with circular nodes move a lot of air out of the way, and that dissipates the energy quickly. These waves give the drum it's characteristic punch or pop sound.
The waves with diameter nodes tend to slosh the air above and below the drum head back and forth in an oscillation that stays close to the drum head. This doesn't dissipate energy as quickly and gives drums the longer, semi-pitched ringing tones.

The circular boundary on the drum is held stationary and is a permanent node for everything that happens on the drum head.

The table in the video is different because the edge of the table is not secured, and is therefor a permanent anti-node.

In either case, if you touch the drum head or table while exciting it, the location of the touch places a node - a location where there is no vibration.

This is true on guitar strings, if I pluck a guitar string that activates a huge range of frequencies on the string. If I also touch it at the node of any of the overtones in the harmonic series, then only those frequencies which share a node where I touched can ring out. Because my finger will dampen all waves which would vibrate the string at that point. But waves that would not vibrate the string where I touch it continue to ring out, as my finger isn't "in their way" so to speak.

[OngBonga]

Fascinating.

These waves on this heavy metal plate are not significantly affected by the air.

Well, I was suggesting the opposite... that the air is affected by the plate.

So the sand on the table is pushed away from locations with large vibrations and settles into locations with no vibrations.

This makes equally as much sense as the idea of low and high pressure regions in the air causing the movement of the powder. I'm more inclined to accept your explanation though, what with you being educated on the subject while I basically guess.

[MadMojoMonkey]

I really think the moving air is a red herring on this one.

I'm struggling to state it concisely, though. Moving air has lower pressure than stationary air.
This is how a carburetor works.

At any rate, if you play with a chladni plate (I know that's not a common experience for people who aren't me), you can touch it in various places and feel the way the plate is vibrating where there is and isn't sand.

And the plate is shaking up and down, normal to the plane, in its oscillations, which makes sense that it will throw the sand up off the plate since that's the direction it's moving. The sand gets tossed in a random-ish direction (mostly up) and if it lands where the oscillation will toss it up again, then it keeps bouncing around. But if it lands where there is no motion, then it comes to rest.

[Poopadoop]

I really think the moving air is a red herring on this one.

I'm struggling to state it concisely, though.

The air would have to be moving a lot faster than the plate is vibrating to move the sand particles, no? Less density and all that?

And the air is only moving because of the plate (caveat emptor), so there's energy lost there.

The plate molecules (at least at the top of the plate) are also directly in contact with the sands, and most of the air molecules aren't.

How's that?

[MadMojoMonkey]

I don't know how fast the wind is moving, and I don't have an intuition for finding any nodes in the air movements.

The sand-lines on the chladni plate collect on the boundaries where the oscillations pass through 0 displacement. So at any given time that the section on one side of a sand line is displaced upward, the regions on the other side of the line are displaced downward.

The air above the plate sloshes back and forth across the sand lines as the regions on either side go through a cycle of oscillation. It also sloshes throughout the regions, though, and pulls air in from other neighboring regions. It's not clear to me that there would be any "dead" zones or nodes in the air movement.

My gut says if there are, they'd be near the anti-nodes shown by where the sand lines aren't. Meaning the highest air pressure would be there, and the lowest average pressure over a period of oscillation would correspond to the sand lines.

I.e. the nodes of the table's displacement would correspond to anti-nodes in the air displacement.

Both of which would tend to move the sand to the same locations.


IDK. Maybe those slight differences in average pressure does apply a tiny force on the sand particles when they're airborn. A lot of tiny pushes when there's very low friction can add up.


Maybe ong's not totally incorrect in his hypothesis, even if it's not a dominant factor, is all.

[Poopadoop]

I don't know how fast the wind is moving

It's not wind, it's air.

That was my point. If you make a metal table vibrate it's going to move with more energy than the air around it, which it is also moving. If it has more energy, it's got more power to move the sand. It's also closer to the sand and it's a solid, so both things mean more contact with the sand, which means more likelihood of contact between molecules.

Like if I bang my desk the things on my desk jump. If I make the exact same movement with the same force on the air in front of them they don't do anything.

Ergo, the air isn't doing fuck all there.

[MadMojoMonkey]

Don't get me wrong, my gut was to completely write off ong's hypothesis.

But the more I tried to come up with a picture for what the air is actually doing, the more I had to admit Bernoulli's principle applies when there is moving fluid - and it says among other things that all else held equal, a fast moving fluid has lower pressure than a slower moving fluid.

So a pressure differential from high to low *may* establish as the plate forces the air around.

And as I noted... while the sand is airborn, the friction on it is minimal, and tiny variations in air pressure throughout its time of flight may move it slightly, causing it to land back on the plate differently than if this was performed in a vacuum.

However, the end result in vacuum would look the same. IF the air plays a role, that role is minimal.

[Poopadoop]

However, the end result in vacuum would look the same. IF the air plays a role, that role is minimal.

I mean yeah, obv. the air will do SOMETHING because it's there and in contact with the sand particles. The question is whether it contributes to the end result in any meaningful way. And if the end result if the air were removed is the same, that suggests the air isn't doing anything systematic.

[Poopadoop]

In other news, it's an illuuuuussion!

[OngBonga]

I'm struggling to state it concisely, though. Moving air has lower pressure than stationary air.

This is actually fairly easy to understand if visualised. Maybe I can adequately explain it, I'll give it a go.

Air that isn't moving much still moves because the particles are colliding. But the motion is pretty random. As air begins to flow, the motion of the particles isn't so random, and instead tends to be in the same direction. I think we need some kind of visualisation...

We need a channel with walls...

------------------------------------------------

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Imagine mostly motionless air sitting in that channel. As particles collide, they bounce off the walls of the channel. This creates a force on the walls... pressure. Now imagine the air flowing in one direction... there are fewer collisions, because most of the air is flowing in the same direction. Thus, fewer particles are hitting the wall. Less force on the walls, lower pressure.

That's why flowing air has lower pressure.

I really think the moving air is a red herring on this one.

To be clear, I didn't intend to mean air movement in the sense of flowing (wind), I meant vibrating air (sound). But I'm in no doubt I was wrong and you're right when you explain it's the plate's vibrations that cause the pattern, not the air. My idea was basically that the plate causes the sand to move, and the difference in air pressure (the sound) causes slightly different angular motion of the sand, as the sand tends towards the lower pressure regions. But your explanation makes a lot more sense, frankly, that some regions of the plate vibrate more than others, and the sand tends towards regions where there is less vibration.

However, the end result in vacuum would look the same.

If this is true (and I don't doubt it) it does destroy my hypothesis.

[OngBonga]

In other news, it's an illuuuuussion!

This looks fantastic... from this angle. From any other angle it would look shit.

[Poopadoop]

This looks fantastic... from this angle. From any other angle it would look shit.

I can't really get my around how it would look from any other angle, so I'll take your word for it.

But, I'd reckon it'd be even more fantastic if that was actually how the house really was built, rather than an illusion.

[Poopadoop]

This is actually fairly easy to understand if visualised. Maybe I can adequately explain it, I'll give it a go.

Air that isn't moving much still moves because the particles are colliding. But the motion is pretty random. As air begins to flow, the motion of the particles isn't so random, and instead tends to be in the same direction. I think we need some kind of visualisation...

We need a channel with walls...

------------------------------------------------

------------------------------------------------

Imagine mostly motionless air sitting in that channel. As particles collide, they bounce off the walls of the channel. This creates a force on the walls... pressure. Now imagine the air flowing in one direction... there are fewer collisions, because most of the air is flowing in the same direction. Thus, fewer particles are hitting the wall. Less force on the walls, lower pressure.

That's why flowing air has lower pressure.

ITT Ong explains grade 7 physics...

[Poopadoop]

See if you can explain why the house looks all curvy and whacky now, professor.

[OngBonga]

I can't really get my around how it would look from any other angle, so I'll take your word for it.

Can't mentally visualise perspective art from different angles.

ITT Ong explains grade 7 physics...

Completely understands why flowing air has lower pressure.

[OngBonga]

[Poopadoop]

Can't mentally visualise perspective art from different angles.

I know how it works, you don't.

But I can't visualize it from different perspectives and you can. Yeah, that adds up.

I bet you I could show you 10 different illusions and you wouldn't be any better than chance at describing how they'd look from 90 degrees away.

Completely understands why flowing air has lower pressure.

You're grade 7 physics teacher must be very proud.

[OngBonga]

I know how it works, you don't.

Quite the assumption.

[MadMojoMonkey]

The house is an interesting one because normally I see perspective art on a street or floor.
Also, they tend to have recognizable objects in them - the distortion of which is obvious because we have an expectation of what their proportions should be.

But the house is all random curves and shading. There aren't any recognizable things to throw off the perspective view.

And the fact that it's vertical means that you have a pretty reliable angle of viewing from the ground, at least. So the distance to the far away parts is the same if those parts are high on the wall.


I think the house illusion still looks wonky from other angles, even if the wonkiness isn't the same as from other angles. I mean the illusion still works from other angles.


I want to see a video of someone moving past the house, now. Does it look totally wrong because none of the "in front / behind" stuff changes as you'd expect when passing a 3D object with those curves?

[Poopadoop]

Quite the assumption.

He says while he frantically googles "how do illusions work"...

[Poopadoop]

I want to see a video of someone moving past the house, now. Does it look totally wrong because none of the "in front / behind" stuff changes as you'd expect when passing a 3D object with those curves?

Not quite what you asked for, but pretty cool nonetheless.

[OngBonga]

He says while he frantically googles "how do illusions work"...

The point of trolling is to not be obviously trolling.

[OngBonga]

I want to see a video of someone moving past the house, now.

I tried to find such footage but gave up and settled for still images from other angles.

I don't think it looks great from other angles, but admittedly it's better than I expected.

[Poopadoop]

The point of trolling is to not be obviously trolling.

It's definitely not to form a cogent argument, so yeah if that's what you're doing then well played.

[OngBonga]

It's definitely not to form a cogent argument, so yeah if that's what you're doing then well played.

What are you even doing? I know I like to argue shit for the sake of it, but you're taking it to another level here.

[Poopadoop]

What are you even doing? I know I like to argue shit for the sake of it, but you're taking it to another level here.

Trolling is only fun when you're doing it?

[MadMojoMonkey]

I don't think it looks great from other angles, but admittedly it's better than I expected.

Same.


The room illusion is well known to me. There's one at the St Louis Science Center that you can walk around in, and there's a live video feed to outside the room. So you can explore how weird the shape of the room has to be for it to look like a 2D projection from an off-kilter viewing angle.

@poopy I was thinking more like this problem with perspective art.

[Poopadoop]

Same.

Much of the illusion is due to how the visual system constructs depth, so walking around shouldn't change it much.

Fun fact: the visual image on the retina is only 2D. What hits your retina if you stand in front of the house is pretty much identical to what hits it when you look at a photo. The brain creates the perception of depth using different cues, like assuming darker things are out of the light and thus behind lighter things, and that smaller things are further away and that shapes tend to be regular, so if one end looks smaller than the other it must be farther away.

e.g. the curvy looking bit at the bottom of the house is created by having a lighter shade above a darker shade. The shading I think also contributes to the curvy aspect as things that are "in front" are lighter than things "further back".

@poopy I was thinking more like this problem with perspective art.

Kind of obvious from what I said above, but the 2D top and bottom images are different, and there's no depth cues in the bottom one, so no illusion.

That thing should work fairly well from any angle though, just like the house, as long as you're looking more or less straight down on it.

[Poopadoop]

My bank is asking me if I want to provide them with biometric data so they can confirm my identity when I do online banking from home or on my phone.

Uh yeah....uh no.

[OngBonga]

Much of the illusion is due to how the visual system constructs depth, so walking around shouldn't change it much.

Tells me I don't understand how they work, proceeds to demonstrate you don't know how they work.

The illusion only properly works from the correct angle. From the incorrect angle, the image appears elongated or flat.

[OngBonga]

My bank is asking me if I want to provide them with biometric data so they can confirm my identity when I do online banking from home or on my phone.

Uh yeah....uh no.

Yeah fuck that. It's annoying enough to have to find the card reader so you can get a code, but I just about accept that inconvenience.

Whatever happened to simply having a good password?

[Poopadoop]

Tells me I don't understand how they work, proceeds to demonstrate you don't know how they work.

The illusion only properly works from the correct angle. From the incorrect angle, the image appears elongated or flat.

Look closer Merlin. That's not the same image from a different angle, it's two different images.

[Poopadoop]

Yeah fuck that. It's annoying enough to have to find the card reader so you can get a code, but I just about accept that inconvenience.

Whatever happened to simply having a good password?

The kicker is if that your bank account gets hacked, it's the bank's liability not yours. They're basically asking people to give them a retina scan as a favour to them.

[OngBonga]

Look closer Merlin. That's not the same image from a different angle, it's two different images.

It's the same image, just the top one is not quite completed. At least I think it's the same image, what with both images coming from the same website showing the work. Note the black line going through the image, it correlates perfectly in both images.

[OngBonga]

The kicker is if that your bank account gets hacked, it's the bank's liability not yours. They're basically asking people to give them a retina scan as a favour to them.

Depends how you get hacked, if they can prove it's due to your own negligence you haven't got a leg to stand on, but yeah you're right, they're simply trying to cover their own asses because fraud does cost them a fortune.

[OngBonga]

Look at the markings on the pavement, in particular the two lines to the right of the "camp" paper that meet at an angle. It's the same image from a different angle.

I mean, surely you know that's what it's going to look like from that angle.

[OngBonga]

It's exactly the same principle as road markings saying "SLOW" or whatever. From afar, it reads perfectly, but as you get nearer and the angle changes, it becomes more and more elongated. Only in this case, you're approaching directly so you don't need to do any mental rotation.

[Poopadoop]

It's the same image

If only you're online perception were as good as your imagery. Oh wait, it is.

They're not the same image.

[OngBonga]

Well whoever did these obvious-to-you different images did a truly remarkable job of using the exact same part of the pavement, so kudos to that guy.

[Poopadoop]

Look at the texture and colour of the pavement lol.

The only things identical are that both have a crack in them, which is hardly a unique feature in pavement.

[Poopadoop]

I mean you've obviously trying to gaslight me into thinking you have brain damage and really can't see the obvious differences there, but anyways here's a few:

1. Crayons are different. On top they look like they're drawn on the pavement, on the bottom it's hard to tell but they look like they could be real. In either case, there's a shadow present on the green crayon in one but not the other. Also, in the top one the crayons are each a uniform colour but in the bottom they have horizontal stripes.
2. Drawing on paper is coloured in in one and not the other.
3. Bottoms of cups are different colours.
4. Shading near letter B present in one and not the other.
5. Star on cup completely visible in one but only partially in the other.
6. Cup has been shopped in bottom figure to be stretched out much more than the angle of view suggests.

[CoccoBill]

I'm with ong on this one, those photos are of the same damn place or someone's gone though an exorbitant amount of work to make them look very similar. The texture change is from lighting. Look at the black streaks on the asphalt going away from the camp-sign, or up from the letter C. They all match.

[CoccoBill]

As already said, top photo is unfinished. The shadows under the objects are still missing.

[CoccoBill]

https://mcpinney.com/3d-sidewalk-chalk-art-2012/

[OngBonga]

I'm 99% sure you're trolling but on the off chance you're not, I implore you again to study the marks on the pavement which perfectly correlate in both images.

The slight difference in shade of the pavement is easily explained, clearly these photos are not taken at the same time so the light conditions are relevant. To have an identical crack go through two different images would be quite a coincidence in its own right, but to also have marks on the pavement that meet at an angle at precisely the same place in both images (just under the letter P), we're moving into ridiculous probability here.

Especially given that both these images came from the same website.

But I'll entertain you for just another minute. Let's assume they are actually different images. Initially we were talking about what it would look like from different angles. What do you suppose the top image looks like from the angle of the bottom image? What about vice versa?

[CoccoBill]

ITT poop learns about lighting and perspective.

[OngBonga]

lol cheers cooco, I couldn't be bothered to find the website I found these images from, seemed more fun to just argue with poop.

[CoccoBill]

Ok poop, ready to man up and admit it?

[OngBonga]

You can still play the trolling card poop to save face, I've given you that out several times.

[Poopadoop]

Yeah I guess we just have a different definition of "identical." If by that you meant it was the same image but taken after six hours of work on it then yeah you got me.

And yeah, duh, the shades aren't there 'cause they haven't drawn them in yet. Fine.