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Dandelion Seeds Fly Using ‘Impossible’ Method Never Before Seen in Nature

nature.com

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Re: Dandelion Seeds Fly Using ‘Impossible’ Method Never Before Seen in Nature

#81

Post by HHest »

mdda wrote: post #76
nl wrote: post #70

Earlier quoted context omitted.

That would 100% be possible with image recognition. Segment using UNet, then measure the remaining joined pixels. (Well thanks for the downvotes. I do this as my job, so I guess I'm doing the impossible or something)

Perhaps people are wondering how your UNet is going to see the bristles on the other side of the dandelion seed.

Think you are misunderstanding what they are counting. The bristles of the seed sit on a stalk and are quite visible individually for the most part, because they are quite thin and stick out in different directions. If you were to place it so that the stalk points toward you, like in the Nature video, the bristles would stand out really clearly.

https://commons.wikimedia.org/wiki/File:Dandelion_seed_-_May...

Re: Dandelion Seeds Fly Using ‘Impossible’ Method Never Before Seen in Nature

#82

Post by neuronic »

dnautics wrote: post #60
mindfulhack wrote: post #31

It's like nature's had millions of years to crunch through its own AI / machine learning of evolution and adaptation, and we're about to unleash the same thing on an impossibly faster scale. Imagine the technological breakthroughs that are going to happen. I'm optimistic.

Genetic algorithms have been around in CS for a long time, in lots of highly effective optimization problems, particularly in structural problems. They don't seem to be as good for AI/ML problems (though the jury is still out in hyperparameter type stuff). Gradient descent via backpropagation is quite effective here, and that is very much not like how the dandelion pod evolved.

Maybe that's as meta as it gets about evolution. The mechanisms of evolution itself are put under selection pressure once we put alternatives out there.

Once we truly break the barrier between metal and meat, artificial processes may create real life in completely unforeseen ways. Gives a new ring to "asexual reproduction".

Re: Dandelion Seeds Fly Using ‘Impossible’ Method Never Before Seen in Nature

#84

Post by mafm »

onion2k wrote: post #71
creep wrote: post #62

Earlier quoted context omitted.

I don't think worship is an "animistic" quality. I think the tendency to worship is very much a refined trait in highly intelligent organisms.

You're right in the sense that ritualised, repeated behaviour performed for no obvious gain is something very unusual. Most animals don't waste energy on things that don't have a material impact on their life. I'd disagree with your point about intelligence though. It's simply that we have more resources than we need. Even the stupidest animals would develop rituals if they could afford to.

Animals like rats and pigeons actually do develop superstitious rituals.

Skinner documented it in 1948, and there's a fair bit of literature on it.

https://psychclassics.yorku.ca/Skinner/Pigeon/

Re: Dandelion Seeds Fly Using ‘Impossible’ Method Never Before Seen in Nature

#85

Post by mhandley »

aidos wrote: post #3

That was a lovely little diversion! There’s a brief 1 minute clip in the article that’s worth watching. I do have one question though, how is the air flowing up through? It the seed not falling for that to happen?

It flys in the same way a glider flys. A glider generates lift over the wings, but the lift comes from the airflow, and you get the airflow by trading potential energy for kinetic energy. Thus the glider is always descending through the airmass, albeit at a very shallow glide angle. But the airmass itself isn't stationary - the sun heats the ground unevenly, so some air above it is warmer and rises, and some parts are colder and sink, with winds circulating between them. A glider can stay airborne for hours if the pilot is good at finding rising air, and circling within it. So long as the air is rising faster than the glider is descending within the airmass, the glider will gain altitude.

The dandelion is doing the same thing. It's creating lift by descending slowly within the airmass, though the process of creating lift is via the vortex ring, rather than airflow over wings. Its aim is to fall very very slowly. Then it will often be falling slower than the airmass is rising, and it will be carried up and far away. Of course there's no pilot, so it can't actively seek out rising air, but there are an awful lot of dandelion seeds, and only a few need to get lucky to spread a long way.

Re: Dandelion Seeds Fly Using ‘Impossible’ Method Never Before Seen in Nature

#86

Post by nosjwshere »

paavoova wrote: post #48

Perhaps ignorance on my part, but: why do they require highspeed cameras and laser illumination to figure this out in 2018? Shouldn't physics by able to model such a relatively simply structure and how air would move through and around it?

reverse engineering is cheaper

Re: Dandelion Seeds Fly Using ‘Impossible’ Method Never Before Seen in Nature

#87

Post by CraneWorm »

strainer wrote: post #33

""" """ "" ^v^ "" "" ^v^ "" "" ^v^ "" ... low pressure """...""" held by vortex ######### ### dandelion falling """"""""" """ rising air I wonder about the chances of creating this kind of toroidal vortex above a duct for lift. It seems necessary for the air to pass in the same direction as the lift, yet lift is normally created by throwing air in the opposite direction.

I had to read your comment twice before I realized it's not, in fact, a short poem.

[Edit] Maybe it is after all. :)

Re: Dandelion Seeds Fly Using ‘Impossible’ Method Never Before Seen in Nature

#88

Post by pouetpouet »

ehnto wrote: post #27
lordnacho wrote: post #12

Earlier quoted context omitted.

Yes, the seed is falling, but the vortex slows the fall enough for it to be useful in distributing the seed as far as possible.

Some seeds have a small leaf attached, making them spin as they fall and slowing their descent for the same purpose. It's not about flying, just about prolonging the time spent in a moving body of air.

Sycamore and linden are the perfect example of this.

Re: Dandelion Seeds Fly Using ‘Impossible’ Method Never Before Seen in Nature

#89

Post by rcxdude »

captain_perl wrote: post #21
wahern wrote: post #15

Earlier quoted context omitted.

They're different ways to describe the same phenomenon. "[B]oth 'Bernoulli' and 'Newton' are correct." https://www.grc.nasa.gov/www/k-12/airplane/bernnew.html

> They're different ways to describe the same phenomenon. Well ... they're actually different ways to incorrectly describe the same phenomenon. Wind tunnels are still used for aircraft design because we can't accurately model aerodynamics.

They're both correct in that both need to be true for lift to occur. If there is a force upwards on the wing then there needs to be an opposing force, and this necessarily must come from a difference in air pressure between the top and the bottom of the wing. Also, for the force upwards to exist, there must be an acceleration of the air around the wing downwards. It's also true that for a pressure difference between the top and bottom of the wing to exist, the air must accelerate downwards and vice-versa. Similarly, the low-pressure air on the top of the wing must be going faster, and faster air must be lower pressure (it is, however, not true that the air travelling over the top of the wing must take the same time to pass the wing and the air travelling over the bottom. This is in fact usually false).

These are all fairly straightforward consequences of the basic rules which air must follow when flowing. The wing produces lift because the shape of it means that all the consequences of the above are the only ones which follow all the rules, much like a sudoku or crossword. The details of actually solving the full puzzle (in way which tells you how much lift and drag you get) turn out to be fiendishly complex, but the basic reasoning is not too hard to understand, apart from the fact that people get confused by the fact that you can explain it 'simply' in multiple different ways by focusing on only one part of the whole crossword.

Re: Dandelion Seeds Fly Using ‘Impossible’ Method Never Before Seen in Nature

#90

Post by TeMPOraL »

comex wrote: post #80
mdda wrote: post #76

Earlier quoted context omitted.

Perhaps people are wondering how your UNet is going to see the bristles on the other side of the dandelion seed.

Take photos from multiple angles?

Now you have a pretty ugly correspondence problem to solve.
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