So I work in the municipal water industry, and when explaining to new interns what a water hammer is, I tell them to visualize suddenly slamming the doors shut at Walmart on the morning of Black Friday and the ensuing crowd crush that is sure to happen.
That is an awesome way of looking at it. I have always told my guys to think of a wall getting suddenly dropped across the roadway.....(I do site work, including water based utility install)
The funny thing is in any course, class, or apprenticeship concerning electricity they use water pipes as a way of describing electricity through a wire. So I guess we use people in a walmart to explain water in a pipe, and then use water in a pipe to explain how electricity through a wire to people in a classroom and it comes full circle
The answer to that question is that we do not have free will. In a physical form the number of possible outcomes are calculable and is influenced by variables that are measurable. To have free will one would have to exist in a state without space and time 🤷
@@valentinoreid9253 Your conclusion may or may not be correct, but your reasoning is not. First, whether a variable is 'measurable' is dependent on our ability to measure it. What matters is not that, it's whether that variable has an effect and whether that variable is deterministic. Second, some things appear (at the moment anyway) to be non-deterministic, albeit at the quantum level. Third, your final point is illogical. Free will involves making decisions. A decision is a change in state. It therefore requires time, so free will _cannot_ exist outside of time - the exact opposite of what you state. It also requires something to exist which is making that decision, and that something will take up some space. Free will therefore also requires space, so cannot exist outside of it.
@@Grim_Beard I have often found the reality to be different than what is reasoned to be true no matter how sound it may seem in a vacuum. And yes my second point is illogical because it's supposed to be. In a state without space or time all possibilities exist simultaneously.
If moshers behave like a gas, which I will call moshium, then we could calculate: - the density of moshium in various atmospheric conditions - the molar mass of moshium - the boiling point and freezing point - vapor pressure - viscosity - miscibility with other similar macrogases such as protestorium, congregatium, classroomium, marchingbandium, and so forth Someone needs to science this.
An uncle of mine explained electrical flow as being like water when I was a kid(35 years ago). I've applied fluid dynamics to many different practical problems since and it has been very useful in helping me find real world solutions.
As part of my job, I routinely mix fluids of different densities. Watching the density boundary between them expand and then destabilize is one of my favorite things. It really is beautiful.
I always saw crowds as fluid in high school. People would bunch up and move slowly before a tight area, then move quickly through it. Though I never observed any waves...
This is one of the videos I preferred from you guys these last five years! I love how science is interconnected. You learn something, and you never know how or when you'll apply it, and boom, a couple years later it helps you in your work. It's just great!
@Fuert Neigt Hmm.... I have a feeling *someone* here thinks they're smart but is actually stupid. These examples weren't used to prove a hypothesis. Its already been confirmed, and is just redistribution of knowledge in a short overview.
@Fuert Neigt Again, SciShow is just a redistribution of knowledge. If you want to learn physics equations and fluid flow, go to school. This isn't an education. This is surface-level "Oh that's interesting". Don't expect them to show every equation. If you want that, find a PBS channel like Spacetime. When you have to learn equations like the Time-Independent Schrodinger Equation in 3 Space (also called 3D-TISE), or equations in Special and General Relativity such time-dilation, spacial-dilation, and inertial reference frames and how to use it correctly, you'll learn that level of education is much deeper than this YT channel.
@Fuert Neigt You're not very bright... they aren't trying to invent new science. The things that SciShow covers are things that ACTUAL scientists study then they read the journals and *distribute* the knowledge in a fun-form video to make learning fun. This is like a surface-level informative show to help laymen understand the complexities that we actual scientists must dredge through on a daily basis.
The bit about mosh pits is great because the difference between gas and liquid molecules is higher energy, and mosh pits are definitely higher energy than the average crowd!
08:43 Hank says "a hash function needs to be unique, meaning you can never get the same string of gibberish from two different passwords". But that's not actually true, is it. If the hash is 64 characters and the passwords were of arbitrary , then by definition there are more combinations of passwords than hashes: they will sometimes produce the same result. We use MD5 hashes on computer files to check for a change. If the MD5 hash is 64 characters long, the file could be kilobytes, megabytes, or even terabytes+ long. It's not only possible but certain that two entirely different files could result in the same hash. It's just highly unlikely that they will.
Correct. Additionally, unlike with files, with passwords traditionally there is a random "salt" added (kind of analogous to an initial vector for a block cipher in CBC mode), both to make pre-computed dictionaries more unwieldy and to make it less likely to see directly whether multiple users had the same password. This was especially important back before passwords were moved into a shadow password file...
@@zebionic True, but irrelevant to the definition of a hash or the uniqueness question. Salts are a warranty against a dictionary attack on a source of hashed passwords.
Makes perfect sense, psychohistory was a statistical study of human behavior in the books, it could only say things about a large flow of people over large times, much like how fluid dynamics can only say things about a huge number of particles inside a volume. also in much the same way fluid dynamics can say little about what happens after a moment of turbulent flow, psychohistory couldn't say much about a chaotic moment (instead opting to try and avoid the chaos altogether). I suspect Asimov took a huge amount of inspiration from mathematics for Foundation, specifically stochastic processes, fluid dynamics, and thermodynamics.
"You wouldn't expect rabbits to spread out over a landscape at the same speed that, like, a lichen does." I'm not sure I'm lichen that analogy, but I'm not rabbitly against it.
This is a popular misconception. Cats can be more accurately described as a Non-Newtonian fluid. They defy normal physics and have retracted shear points.
8:47 Actually, it's usually not the case that hashing algorithms are truly unique, because it's logically impossible if the created hash has a predefined size. Take MD5 (as example ... not to store your passwords, please). it produces 128 bit hashes. The values you can generate with 128 bit are limited, the strings you can input into the algorithm are unlimited though. Since a set containing every possible md5 output is a subset of every possible md5 input, it can't be unique. The uniqueness of those functions is rather an extreme unlikeliness than an actual uniqueness.
You are right that the output of a hash function don't have to be unique, and if the input can be bigger than the output it is logically impossible for it to be unique. But for a good hash function it should be hard, as in practicality impossible, to make an input that matches a predefined output or to find to inputs that give the same output.
@@KenZilla72 Which is the "one way" property, which itself recovers a lot of things about hash functions (he didn't talk about widespread output space)
12:04 every observant coffee addict noticed that it was, in fact, tea shown in that cup. What kind of shenanigans are you trying to pull, Hank? Coffee is serious business!
Yeah, I kind of knew instinctively that crowds flow like water. I tend to act as a fish as much as possible; riding currents, avoiding blockages, seeking open space, and traveling faster than just floating along. I can't stand slow-moving crowds.
Slartibartfast would be proud! Actually, no. He would chuckle politely but somewhat patronizingly at how long it has taken the Earthlings to understand the fundamentals of bistromaths.
I'd argue that they model closer to non-newtonian fluids. If ya poke 'em, they start acting solid VERY quickly, and proportionately to the amount of force applied.
When traffic is described with terms like, "steady stream", "flow reduced to a trickle," "log-jam" - or especially "clogged" and "seriously backed-up," then the only "fluid mechanics" I'm thinking about are plumbers!
Several thoughts I had while watching, some far more random than others: So although people aren't exactly water molecules or gas molecules, they DO get excited. The parallels continue the more you look at it. If we can predict species movements even a LITTLE bit, could this aid in planning for "greenways" and other efforts to allow animals to move safely through human habitats? And for that matter, allow humans to move through animal habitats with less damage to the environment and danger to all species involved? How much milk does one person need in their coffee????
It could be particularly useful to reduce whale strikes; huge cargo ships hit and kill thousands of whales every year, but because whales are negatively buoyant, they sink and are forgotten. These calculations could help reduce instances when ships and whales flow intersect.
Uniqueness isn't really a password hash requirement. It's like door keys, there are many more door knobs than possible keys. Your door key opens another door, but you don't know which one. A password hash works the same way, so your long password can be fit into the 256 or 512 bits of SHA-3.
I just want to say how beautiful is to see Physics applied to Biology so successfully. I am a biologist and I had always thought that sciences need to be separated because it is just too much information to be a "Full" scientist, but sciences should be taught as a whole Physics-Chemistry-Biology are just different points of observation of the same Nature, and mathematics is the language that allows us to connect them all together. But the cryptography one blow my mind off, What could have thought Alan Turing about it behaving like a liquid?
I'm just going to assume fluid dynamics are being used in planning evacuation routes and emergency exit traffic in modern high-rise buildings and malls, because that sort of thing sounds like an application where being able to model movement can make huge improvements in effectiveness.
30 years ago in grad school for applied mathematics, we practiced math modeling by showing the equivalence between an equation used for gas pressure in rocket engines and traffic flow. Since then, I speed up my commutes by always looking for the lane with the least density, no matter how fast it's going, since it's much less likely to experience stop and go traffic.
Yes, like your cat, too :) I used to have a Ginger. Started out as not mine, but after taking him to the vet and then giving him meds for his gums, he decided that I was HIS :P
Groups of people behaving like fluids is in our language as well. Either because we use the same words for both or when we use words specific to fluids for people. Some example, "people *poured* into the stadium", "the group *surged* forward", "the alley *filled* with fans".
This is one of my favorite episodes. No one topic left me feeling I was " getting lost in the weeds". Your presentation of information alongside info on my least familiar areas- internet security and cryptocurrency- helped me grasp everything a bit better! Thanks so much!
hashfunctions are anything but unique. For passwords they appear to be unique in most scenarios cause the size of the hash is just way way bigger than the input, but so called hash-collisions are still common.
Fuert Neigt I work in security and while I don’t think it’s better than ECC or even RSA for the vast majority of applications because of the difficulty in computing fluid dynamics... but, it would be a valid trapdoor function since it would still be far harder to reverse than compute initially. And forget the coffee entirely, it’s a sound idea to apply a transform based on fluid dynamics during encryption.
Interesting. Thanks.Once I was working for this company, and we had to open this cellar, that lead down a tunnel, to another building. The passage had not been opened for decades, and the door was painted shut. Amazing, the lights worked, because we could see them through the window in the door. We forced the door open, and near our feet was like these clouds. With the door open, air flowed, these cloud like things by our ankles, slipped along, just like oil in a stream. The cloud like things looked fluid, but kind of stuck together. The little cloud looked like smoke moving around, and over object on the floor. It looked just like a fluid, but it didn't mix, but sort of helded together like oil, on top of water.
YES! PEOPLE ACT LIKE FLUIDS! It was 2012 and I was picking out my thesis project for my Master's Degree in Architecture before I ever heard someone besides me talk about crowds of people behaving like fluids. Granted, most of the works cited in this video didn't exist in 2012, but the 2009 Scientific American article about emergency exits seems like it would have been a relevant one. This is an important topic that deserves much more study!
The Bitcoin one was click-bait (or technically keep-watching-to-the-end-of-the-video-bait); it was about hashes in general, not specifically about Bitcoin, it applies just as much to everything else that uses hashes.
Sorta, but not really. SciShow provides overviews at a (generally) high school level and uses common world examples to help viewers understand the concepts... And since most people of *any* education level don't understand cyclic encryption rates or PGP software, Bitcoin is kinda at the top of a very short list of possibilities.
Relative Permeability is definitely a real (and commonly used) thing. I'm a petroleum engineer and the relative permeability of oil =/= the relative permeability of water. This is due to many factors such as polarity, capillary pressure, etc.
"Gibberish" is not the word you're looking for here. Results from the most common hash functions are pretty recognizeable, they all have definite lengths and vocabulary that makes them usually stand out from actual gibberish. Granted, they can be encoded to look like actual gibberish.
@@naiknaik8812 Have you never looked at anything involved with science even once... Including this video? Nature repeats patterns over and over at the smallest and biggest levels.
The marathon beginning reminded me of my ice scoop or any sort of metal scoop that's used to pick up large amounts. You'll understand it if you see it again.
At big races for the start of a marathon (or half marathon) racers are seeded in waves based on how fast they run. Therefore there will be waves, as there are waves for the start. Also people move at the same pace because they are running with people that run at the same pace as they are. I have been at the start line of these types of races many times.
One basic property of hash-functions is, that they are not unique. They can't be because they project an infinite set (ALL the strings) to a finite set (i.e. 128 bit numbers).
So hash smoke mixing with the air has the same properties as the coffee and the milk example. Hash hash functions. On a more serious note, how do they know the mixing produces unique results? It may be extremely unlikely but two different inputs might create the same output.
Cryptographic hashing functions don't actually have to produce unique results for every input, but rather just to make it incredibly unlikely for two inputs to produce the same output (called a collision). Generally a hash function will always output a value of the same size, but can take inputs of any size (even ones larger than the output). Since the input space is much larger (in many cases, technically infinite) than the output, there have to be collisions, but in a good cryptographic hashing function they are incredibly rare and entirely unpredictable. So for example an input that collides with ILoveSciShow could very well be hundreds of characters of total gibberish and an attacker would have a harder time discovering that than the intended password, thanks to the one-way feature of the hashing function.
@@wresing I couldn't say I know a little about crypto and nothing about fluid dynamics lol. But I imagine (guessing here) that if they are analogous as claimed, then they become non-reversible for a similar reason to a hashing function, namely presenting a number of complicated steps that can all be reversed many different ways. Like theoretically you could end up with the same swirls with different initial conditions, provided those conditions also _happened_ to lead to the same swirls, but via a different series of events.
@@thymewizard The difference is that the chaotic processes of fluid dynamics are at least theoretically reversible (although practically they are of course not), while the reversal of a hash function is simply impossible because these are lossy functions, meaning information is getting lost during the hash calculation process.
What worries me (just a little) is that it is possible (although very unlikely) that my random generated passwords have the same hash as simple passwords such as password123...
@@frankschneider6156 That's a great point. So maybe the claim then is just that a researcher can use hash-like math trickery to get some good approximations, but not exact models
Navier Stokes baby!! You can also explain many astrophysical phenomenon, even the dark one with fluid dynamics. Not to mention how much fun looking Special Relativistic Magneto-hydrodynamic is xD
"... liquids behave in pretty liquidlike ways, like birds, and bitcoin." That must've been fun to say. What an awesome sounding sentence, so much alliteration.
No. 3, you're talking about chaotic cryptography. It uses chaos theory, similar to fluid turbulence and double pendulums and lava lamp systems. A tiniest bit of change in any initial condition can result in a completely different outcome. Only the perfectly exact initial conditions can give you the original outcome.
This video made me think of the my grade 4 science teacher having us slam dance in class to illustrate the kinetic molecular theory. Of course, that would have been in the early 1980s; I mean, can you imagine a teacher trying to do something like that these days? Yet I give full credit to Mr. Hunter and his methods for sparking my life long love of science.
Cloudflare actually uses the natural pseudo-randomness of fluid dynamics to improve criptography! They have wall full of lava lamps which they record, and then use the bytes of the video feed to fuel the randomness source for its SSL encryption keys.
I enjoyed your talk on the application of fluid dynamics on crowd flow. I told my daughter and she said that merchants should think about this on black Friday.
Heh, I have an acquaintance who is doing research on crowds and specifically _not_ using fluid dynamics, bc apparently several emergency situations can only be modeled with like 80% accuracy or so using fluids and that's not always good enough.
Viscosity would be pretty analogous to how well a species can adapt to the mobility of the terrain...trees would be very vicious, as they can't propel their own travel...they rely on other methods. Whereas humans, many types of insects, and invasive species would be less viscous. Very interesting; while I did know about human movement being fluid-like, I had never realized the connection with turbulence and stampedes.
Wait it was known for quite a while that a good hash function is chaotic, so the only new thing there is that milk in coffee also behaves chaotic (in the mathematical sense, see chaos theory) 🤔
Permeability does depend on the fluid too. For instance, kerosene and water will have different permeabilities through a material that is hydrophilic (or hydrophobic).
A cryptographic hash function doesn’t need to be unique, it needs to have a large enough number of solutions that the chance of collision is very low. MD5 results in a 128bit number meaning that there are 3.4x10^39 possible results.
You didn't mention that the Romans knew that crowds of people act similarly to a fluid. Vomitoria are the large entrances into stadium seating, and the name comes from Latin for "to spew forth". There's a misconception that this spewing was of food, but it was actually just people being treated as a fluid.
@@frankschneider6156 I didn't know about Cloudflare, but 2 years ago, Tom Scott made a video about how Google uses lava lamps to keep the internet secure: ruclips.net/video/1cUUfMeOijg/видео.html
I think this issue suffers from the same semantic problem that the "speed of light" has. Lightspeed isn't really the speed of light, just like fluid dynamics isn't really about the dynamics of a fluid. They are simply shared emergent properties that arise from similar systems.
So I work in the municipal water industry, and when explaining to new interns what a water hammer is, I tell them to visualize suddenly slamming the doors shut at Walmart on the morning of Black Friday and the ensuing crowd crush that is sure to happen.
That is an awesome way of looking at it. I have always told my guys to think of a wall getting suddenly dropped across the roadway.....(I do site work, including water based utility install)
Clever!
That is why some dams have surge tanks, so that when if a gate is suddenly shut off the water behind it has somewhere to go so the pipes don't burst.
The funny thing is in any course, class, or apprenticeship concerning electricity they use water pipes as a way of describing electricity through a wire. So I guess we use people in a walmart to explain water in a pipe, and then use water in a pipe to explain how electricity through a wire to people in a classroom and it comes full circle
@@arthas640: walmart training officer: Picture electricity going through a wire...
Philosophers: Spend centuries arguing about whether humans have free will.
Physicists: You act exactly like water molecules.
Grimbeard well it’s because people in crowds operate on the same very simple rules when it comes to movement, (but i know you’re kidding haha)
The answer to that question is that we do not have free will.
In a physical form the number of possible outcomes are calculable and is influenced by variables that are measurable.
To have free will one would have to exist in a state without space and time 🤷
@Fuert Neigt Thanks for that 😁 tbh I feel as dumb as a rock most of the time
@@valentinoreid9253 Your conclusion may or may not be correct, but your reasoning is not.
First, whether a variable is 'measurable' is dependent on our ability to measure it. What matters is not that, it's whether that variable has an effect and whether that variable is deterministic.
Second, some things appear (at the moment anyway) to be non-deterministic, albeit at the quantum level.
Third, your final point is illogical. Free will involves making decisions. A decision is a change in state. It therefore requires time, so free will _cannot_ exist outside of time - the exact opposite of what you state. It also requires something to exist which is making that decision, and that something will take up some space. Free will therefore also requires space, so cannot exist outside of it.
@@Grim_Beard I have often found the reality to be different than what is reasoned to be true no matter how sound it may seem in a vacuum.
And yes my second point is illogical because it's supposed to be. In a state without space or time all possibilities exist simultaneously.
If moshers behave like a gas, which I will call moshium, then we could calculate:
- the density of moshium in various atmospheric conditions
- the molar mass of moshium
- the boiling point and freezing point
- vapor pressure
- viscosity
- miscibility with other similar macrogases such as protestorium, congregatium, classroomium, marchingbandium, and so forth
Someone needs to science this.
Underrated comment.
I for one would love to know what the boiling point and freezing point of a mosh pit would be.
Y’know. For science.
The boiling point is when the bass drops
An uncle of mine explained electrical flow as being like water when I was a kid(35 years ago). I've applied fluid dynamics to many different practical problems since and it has been very useful in helping me find real world solutions.
Neat
As part of my job, I routinely mix fluids of different densities. Watching the density boundary between them expand and then destabilize is one of my favorite things. It really is beautiful.
Sounds like you've got a RUclips channel in the making ....
As Bruce Lee once said,
"Be like water."
Expected this comment. Was not disappointed. :-)
One person fluid simulation?
@@kennylex one person is millions of cells
No, he said that many times.
I'd rather be like whisky... just have the ability to make people drunk and pass out.
I always saw crowds as fluid in high school. People would bunch up and move slowly before a tight area, then move quickly through it. Though I never observed any waves...
Right!!? We never get to actually see it in action!
coryman125 You weren't high enough. I mean you couldn't see from overhead.
I ran through crowds back when I was a high school freshman just to see how the crowd is affected by my stirring
@@mikebeacom4883 I have, in fact, been that high.
One of the coolest SciShow vids of 2019 hands down!!!
the marathon one looks like what happens when an intake valve opens in a port/runner.
mentions Laminar flow
*Smarter Every Day wants to know your location.*
petr shv
Snatch block
Snatch block
Snatch block snatch block
Your profile pic be lookin’ familiar, what is it?
Somewhere in Montana
The Left can't Meme that didn’t help me whatsoever
@@Cool_Kid95 Its a commission of a character of mine, so unless you follow ResidentRabbit on Twitter its unlikely.
Crowds can be analysed as if people had no thoughts or intentions. ... Why does that not surprise me?
If you have read Isaac Asimov's Foundation series, that would explain it...
Because you survived Covid?
So a mosh pit is James Brownian motion 😂
Nice
Someone please explain this joke.
@@sohopedeco Brownian motion is particles moving in fluid, James Brown was a musician...
@@stevebutchart3638 It turns out I didn't even know what mosh pit meant. 😅
"Living with a Hernia"...Sorry, that's Yankovic's Theorem:D
I’m gonna like this video bc you started with traffic flow.
Respectfully, a Civil Engineer.
Ok, but they saved the thermodynamics for last, so…
Really respectfully, a meche dropout lol
This is one of the videos I preferred from you guys these last five years!
I love how science is interconnected. You learn something, and you never know how or when you'll apply it, and boom, a couple years later it helps you in your work. It's just great!
“Students, today we are modeling the movements of the moshers.”
"ROCK & ROLL!"
That's about the time I start modeling alpha decay.
yes professor, I volunteer as a molecule. PLAY THE MUSIC!
School field trip to Wacken open air.
I love this channel!
I recently start my own channel and you guys have really inspired me.
Thank you!
When I clicked this video I was expecting something like sand. This is much more interesting.
@Fuert Neigt Hmm.... I have a feeling *someone* here thinks they're smart but is actually stupid. These examples weren't used to prove a hypothesis. Its already been confirmed, and is just redistribution of knowledge in a short overview.
@Fuert Neigt Again, SciShow is just a redistribution of knowledge. If you want to learn physics equations and fluid flow, go to school. This isn't an education. This is surface-level "Oh that's interesting". Don't expect them to show every equation. If you want that, find a PBS channel like Spacetime. When you have to learn equations like the Time-Independent Schrodinger Equation in 3 Space (also called 3D-TISE), or equations in Special and General Relativity such time-dilation, spacial-dilation, and inertial reference frames and how to use it correctly, you'll learn that level of education is much deeper than this YT channel.
@Fuert Neigt You're not very bright... they aren't trying to invent new science. The things that SciShow covers are things that ACTUAL scientists study then they read the journals and *distribute* the knowledge in a fun-form video to make learning fun. This is like a surface-level informative show to help laymen understand the complexities that we actual scientists must dredge through on a daily basis.
@@aerysgaming894 Thank you for fighting the good fight!
Same, Merlin!
The bit about mosh pits is great because the difference between gas and liquid molecules is higher energy, and mosh pits are definitely higher energy than the average crowd!
08:43 Hank says "a hash function needs to be unique, meaning you can never get the same string of gibberish from two different passwords". But that's not actually true, is it. If the hash is 64 characters and the passwords were of arbitrary , then by definition there are more combinations of passwords than hashes: they will sometimes produce the same result. We use MD5 hashes on computer files to check for a change. If the MD5 hash is 64 characters long, the file could be kilobytes, megabytes, or even terabytes+ long. It's not only possible but certain that two entirely different files could result in the same hash. It's just highly unlikely that they will.
Correct. Additionally, unlike with files, with passwords traditionally there is a random "salt" added (kind of analogous to an initial vector for a block cipher in CBC mode), both to make pre-computed dictionaries more unwieldy and to make it less likely to see directly whether multiple users had the same password. This was especially important back before passwords were moved into a shadow password file...
@@zebionic True, but irrelevant to the definition of a hash or the uniqueness question. Salts are a warranty against a dictionary attack on a source of hashed passwords.
They didn't know how right they were when they said, "Just go with the flow".
This reminds me of Asimov's "Psychohistory"
Makes perfect sense, psychohistory was a statistical study of human behavior in the books, it could only say things about a large flow of people over large times, much like how fluid dynamics can only say things about a huge number of particles inside a volume. also in much the same way fluid dynamics can say little about what happens after a moment of turbulent flow, psychohistory couldn't say much about a chaotic moment (instead opting to try and avoid the chaos altogether). I suspect Asimov took a huge amount of inspiration from mathematics for Foundation, specifically stochastic processes, fluid dynamics, and thermodynamics.
Yes, The inevitable Seldon Crisis.
"You wouldn't expect rabbits to spread out over a landscape at the same speed that, like, a lichen does."
I'm not sure I'm lichen that analogy, but I'm not rabbitly against it.
Nobody liked Hare's Moldy old puns, but he didn't care, coz he was a Funghi.
...OMG what have you started here....
Interestingly, my mental image upon hearing that phrase was wondering what the flow of werewolves would look like.
Number 1: Cats
This is a popular misconception. Cats can be more accurately described as a Non-Newtonian fluid. They defy normal physics and have retracted shear points.
@@dinorancher5560 Sorry, but I prefer to be ignorant 👁️👄👁️
@@keenban rip to knowledge, but I'm different
@@dinorancher5560 How can they be non-Meowtonian, they're cats ?! ;-p
First thought when reading the title of the video
Interesting concepts. What about the similarities between cats and liquids? If I fits, I sits. Lol
8:47 Actually, it's usually not the case that hashing algorithms are truly unique, because it's logically impossible if the created hash has a predefined size.
Take MD5 (as example ... not to store your passwords, please). it produces 128 bit hashes. The values you can generate with 128 bit are limited, the strings you can input into the algorithm are unlimited though. Since a set containing every possible md5 output is a subset of every possible md5 input, it can't be unique.
The uniqueness of those functions is rather an extreme unlikeliness than an actual uniqueness.
You are right that the output of a hash function don't have to be unique, and if the input can be bigger than the output it is logically impossible for it to be unique. But for a good hash function it should be hard, as in practicality impossible, to make an input that matches a predefined output or to find to inputs that give the same output.
@@KenZilla72 Which is the "one way" property, which itself recovers a lot of things about hash functions (he didn't talk about widespread output space)
@@claudebbg Yes, but the "one way" is not only that it must be hard to find the original input but any input that matches the hash.
idc, time to make fluidcoin
12:04 every observant coffee addict noticed that it was, in fact, tea shown in that cup. What kind of shenanigans are you trying to pull, Hank? Coffee is serious business!
"people aren't actually water molecules"
* Is 60% water molecules*
That's like saying sandwiches are breads.
- how many breads have you eaten
too many..
Atomic Lizard IS THAT A JOJO REFERENCE?!
@@user-vn7ce5ig1z nah it's even worse. It's like say sandwiches are grass because the grain used to make the bread is s grass
Yeah, I kind of knew instinctively that crowds flow like water. I tend to act as a fish as much as possible; riding currents, avoiding blockages, seeking open space, and traveling faster than just floating along. I can't stand slow-moving crowds.
Stirring coffee is like cryptography. Is this step one to having a super computer in the form of a Italian restaurant?
That's what I thought haha
Slartibartfast would be proud!
Actually, no. He would chuckle politely but somewhat patronizingly at how long it has taken the Earthlings to understand the fundamentals of bistromaths.
Do you think a bunch of people tripping and forgetting to hit the floor would behave like a gas or a liquid once they take off?
I wasn't watching the video when he said "lichen" and I heard "lycan". Got real concerned for a second there.
whats ''lycan''
You didnt know about the werewolf issue?
I was paying attention and looking directly at the video. I heard lycan as well.
@@polarisdsmb2015 It's a type of werewolf that can shape-shift at will.
@@polarisdsmb2015 'Lycan' is an old word for 'wolf,' it's used to refer to werewolves a lot.
Yes, I think cats are the closest thing to an actual solid living thing to act like a liquid
Seriously, who are you? You are EVERYWHERE!
@@4Nulla He's just some guy without a moustache. Don't ask too many questions
I'd argue that they model closer to non-newtonian fluids. If ya poke 'em, they start acting solid VERY quickly, and proportionately to the amount of force applied.
"But that's impossible!" "No, just highly unlikely!"
Very, very improbable?
When traffic is described with terms like, "steady stream", "flow reduced to a trickle," "log-jam" - or especially "clogged" and "seriously backed-up," then the only "fluid mechanics" I'm thinking about are plumbers!
Several thoughts I had while watching, some far more random than others:
So although people aren't exactly water molecules or gas molecules, they DO get excited. The parallels continue the more you look at it.
If we can predict species movements even a LITTLE bit, could this aid in planning for "greenways" and other efforts to allow animals to move safely through human habitats? And for that matter, allow humans to move through animal habitats with less damage to the environment and danger to all species involved?
How much milk does one person need in their coffee????
Sonja Johnson we are also social / herd animals so many of the species movement things apply to us too.
It could be particularly useful to reduce whale strikes; huge cargo ships hit and kill thousands of whales every year, but because whales are negatively buoyant, they sink and are forgotten.
These calculations could help reduce instances when ships and whales flow intersect.
When I'm teaching the phases of matter I always use crowds of people (particularly at concerts) to describe the different phases ^,^
Uniqueness isn't really a password hash requirement. It's like door keys, there are many more door knobs than possible keys. Your door key opens another door, but you don't know which one. A password hash works the same way, so your long password can be fit into the 256 or 512 bits of SHA-3.
I just want to say how beautiful is to see Physics applied to Biology so successfully. I am a biologist and I had always thought that sciences need to be separated because it is just too much information to be a "Full" scientist, but sciences should be taught as a whole Physics-Chemistry-Biology are just different points of observation of the same Nature, and mathematics is the language that allows us to connect them all together.
But the cryptography one blow my mind off, What could have thought Alan Turing about it behaving like a liquid?
So if we crack a hole in the top of the crowd, it flows out of the bottom faster?
If fire's coming out of the hole, yep
I'm just going to assume fluid dynamics are being used in planning evacuation routes and emergency exit traffic in modern high-rise buildings and malls, because that sort of thing sounds like an application where being able to model movement can make huge improvements in effectiveness.
You see this in train stations too
If it's big enough, there'll be an information stand or little stores to break up the walking traffic
30 years ago in grad school for applied mathematics, we practiced math modeling by showing the equivalence between an equation used for gas pressure in rocket engines and traffic flow.
Since then, I speed up my commutes by always looking for the lane with the least density, no matter how fast it's going, since it's much less likely to experience stop and go traffic.
Hey cats are liquid lol!
aww you're cat is very cute🐱
Yes, like your cat, too :) I used to have a Ginger. Started out as not mine, but after taking him to the vet and then giving him meds for his gums, he decided that I was HIS :P
I'm just here to see how many cat comments there are.
Primalxbeast Add plus 1 for my comment
Cats don't make comments. And we are not secretly running the world.
i fully expect cats to be one of these items
Groups of people behaving like fluids is in our language as well. Either because we use the same words for both or when we use words specific to fluids for people. Some example, "people *poured* into the stadium", "the group *surged* forward", "the alley *filled* with fans".
correction to title: ""**3 Surprising Things That Act Like Low Resolution Models of Fluids**""
You're not wrong. There's a reason most of these can't be used as anything more than a starting basis for new research and methodologies.
This is one of my favorite episodes. No one topic left me feeling I was " getting lost in the weeds". Your presentation of information alongside info on my least familiar areas- internet security and cryptocurrency- helped me grasp everything a bit better! Thanks so much!
hashfunctions are anything but unique.
For passwords they appear to be unique in most scenarios cause the size of the hash is just way way bigger than the input, but so called hash-collisions are still common.
This is nuts. Mind blown. Keep them coming
do you have a bf i will kiss him
Literally stirring coffee as he starts talking about stirring coffee.
Nobody:
Science: cryptography is like a cup of coffe
Fuert Neigt ok boomer
Fuert Neigt I work in security and while I don’t think it’s better than ECC or even RSA for the vast majority of applications because of the difficulty in computing fluid dynamics... but, it would be a valid trapdoor function since it would still be far harder to reverse than compute initially. And forget the coffee entirely, it’s a sound idea to apply a transform based on fluid dynamics during encryption.
OMG the coffee pot analogy is fantastic to explain the topic about hash functions!
Interesting. Thanks.Once I was working for this company, and we had to open this cellar, that lead down a tunnel, to another building. The passage had not been opened for decades, and the door was painted shut. Amazing, the lights worked, because we could see them through the window in the door. We forced the door open, and near our feet was like these clouds. With the door open, air flowed, these cloud like things by our ankles, slipped along, just like oil in a stream. The cloud like things looked fluid, but kind of stuck together. The little cloud looked like smoke moving around, and over object on the floor. It looked just like a fluid, but it didn't mix, but sort of helded together like oil, on top of water.
Mosh pits as gas particles. I'll never experience a metal concert the same again. Well done, SciShow, well done.
YES! PEOPLE ACT LIKE FLUIDS! It was 2012 and I was picking out my thesis project for my Master's Degree in Architecture before I ever heard someone besides me talk about crowds of people behaving like fluids. Granted, most of the works cited in this video didn't exist in 2012, but the 2009 Scientific American article about emergency exits seems like it would have been a relevant one. This is an important topic that deserves much more study!
ENTER PASSCODE:
*sees a cup full of almost-but-not-quite-entirely-unlike tea and a jug of milk*
I think your infinite improbability drive is acting up.
This was fascinatingly deep.
Awesome video! Infact , most awesome video I ever seen! Keep up the good work!
Software dev here. That is some A+ explanation of hash functions. Good job!
Meh, I'd have given it a C++
The Bitcoin one was click-bait (or technically keep-watching-to-the-end-of-the-video-bait); it was about hashes in general, not specifically about Bitcoin, it applies just as much to everything else that uses hashes.
Including stoners?
- it wasn’t clickbait more like an example. He said like birds but you didn’t say that was clickbait.
Sorta, but not really. SciShow provides overviews at a (generally) high school level and uses common world examples to help viewers understand the concepts... And since most people of *any* education level don't understand cyclic encryption rates or PGP software, Bitcoin is kinda at the top of a very short list of possibilities.
Great, down to earth explanation of password hashing mechanism. +1
Relative Permeability is definitely a real (and commonly used) thing.
I'm a petroleum engineer and the relative permeability of oil =/= the relative permeability of water. This is due to many factors such as polarity, capillary pressure, etc.
Scishow the knowledge I gain from this company is wonderful. Thank you for continuing being an amazing school.
4:10 laminar flow, destin's favorite
"Gibberish" is not the word you're looking for here.
Results from the most common hash functions are pretty recognizeable, they all have definite lengths and vocabulary that makes them usually stand out from actual gibberish.
Granted, they can be encoded to look like actual gibberish.
The universe recycles everything.
As above, so below, and beyond I imagine.
All things are connected indeed
just like how me peeing is connected to how the world spins around the sun
@@naiknaik8812 Have you never looked at anything involved with science even once... Including this video? Nature repeats patterns over and over at the smallest and biggest levels.
@@ThrottleKitty , have you ever heard of a joke? You should try them out sometime. Lol
@@BackYardScience2000 Not really so much a joke, as a snarky sarcastic comeback that was neither accurate or amusing.
The marathon beginning reminded me of my ice scoop or any sort of metal scoop that's used to pick up large amounts. You'll understand it if you see it again.
At big races for the start of a marathon (or half marathon) racers are seeded in waves based on how fast they run. Therefore there will be waves, as there are waves for the start. Also people move at the same pace because they are running with people that run at the same pace as they are.
I have been at the start line of these types of races many times.
I guessed ants and cats.
cute
I tuned into this wanting to see traffic get mentioned, I was not disappointed
One basic property of hash-functions is, that they are not unique. They can't be because they project an infinite set (ALL the strings) to a finite set (i.e. 128 bit numbers).
So hash smoke mixing with the air has the same properties as the coffee and the milk example. Hash hash functions.
On a more serious note, how do they know the mixing produces unique results? It may be extremely unlikely but two different inputs might create the same output.
Cryptographic hashing functions don't actually have to produce unique results for every input, but rather just to make it incredibly unlikely for two inputs to produce the same output (called a collision). Generally a hash function will always output a value of the same size, but can take inputs of any size (even ones larger than the output). Since the input space is much larger (in many cases, technically infinite) than the output, there have to be collisions, but in a good cryptographic hashing function they are incredibly rare and entirely unpredictable. So for example an input that collides with ILoveSciShow could very well be hundreds of characters of total gibberish and an attacker would have a harder time discovering that than the intended password, thanks to the one-way feature of the hashing function.
Yeah, and aren't the equations of fluid dynamics totally time reversible?
@@wresing I couldn't say I know a little about crypto and nothing about fluid dynamics lol. But I imagine (guessing here) that if they are analogous as claimed, then they become non-reversible for a similar reason to a hashing function, namely presenting a number of complicated steps that can all be reversed many different ways. Like theoretically you could end up with the same swirls with different initial conditions, provided those conditions also _happened_ to lead to the same swirls, but via a different series of events.
@@thymewizard The difference is that the chaotic processes of fluid dynamics are at least theoretically reversible (although practically they are of course not), while the reversal of a hash function is simply impossible because these are lossy functions, meaning information is getting lost during the hash calculation process.
What worries me (just a little) is that it is possible (although very unlikely) that my random generated passwords have the same hash as simple passwords such as password123...
@@frankschneider6156 That's a great point. So maybe the claim then is just that a researcher can use hash-like math trickery to get some good approximations, but not exact models
Navier Stokes baby!!
You can also explain many astrophysical phenomenon, even the dark one with fluid dynamics. Not to mention how much fun looking Special Relativistic Magneto-hydrodynamic is xD
Number 3 just flew right over my head
"... liquids behave in pretty liquidlike ways, like birds, and bitcoin." That must've been fun to say. What an awesome sounding sentence, so much alliteration.
+
So, from what you are saying, we have started down the road to creating psychohistory.......great, wonderful.......
No. 3, you're talking about chaotic cryptography. It uses chaos theory, similar to fluid turbulence and double pendulums and lava lamp systems. A tiniest bit of change in any initial condition can result in a completely different outcome. Only the perfectly exact initial conditions can give you the original outcome.
I’m now much more appreciative of my “fluid power” certificate I received in school!!! XD
Shout out to Mr.Mark!!!!
One of my lecturers in fact worked on the mosh-pit Brownian motion paper. Thermodynamics is metal af
This video made me think of the my grade 4 science teacher having us slam dance in class to illustrate the kinetic molecular theory. Of course, that would have been in the early 1980s; I mean, can you imagine a teacher trying to do something like that these days? Yet I give full credit to Mr. Hunter and his methods for sparking my life long love of science.
What a fantastic episode! Cheers for this one! Really enjoyed it.
Next: scientists find movement among human crowds has negative energy.
Cloudflare actually uses the natural pseudo-randomness of fluid dynamics to improve criptography!
They have wall full of lava lamps which they record, and then use the bytes of the video feed to fuel the randomness source for its SSL encryption keys.
I enjoyed your talk on the application of fluid dynamics on crowd flow. I told my daughter and she said that merchants should think about this on black Friday.
Heh, I have an acquaintance who is doing research on crowds and specifically _not_ using fluid dynamics, bc apparently several emergency situations can only be modeled with like 80% accuracy or so using fluids and that's not always good enough.
I love the comment section of this channel as much as the video content itself. ❤️
Thank - you .
I always feel smarter after watching one of your videos.
Ooooh can you do a similar one comparing electricity (resistance, conductivity, transitors etc.) and finances (purchasing, interest, banks etc.)?
Viscosity would be pretty analogous to how well a species can adapt to the mobility of the terrain...trees would be very vicious, as they can't propel their own travel...they rely on other methods. Whereas humans, many types of insects, and invasive species would be less viscous. Very interesting; while I did know about human movement being fluid-like, I had never realized the connection with turbulence and stampedes.
Wait it was known for quite a while that a good hash function is chaotic, so the only new thing there is that milk in coffee also behaves chaotic (in the mathematical sense, see chaos theory) 🤔
Permeability does depend on the fluid too. For instance, kerosene and water will have different permeabilities through a material that is hydrophilic (or hydrophobic).
A cryptographic hash function doesn’t need to be unique, it needs to have a large enough number of solutions that the chance of collision is very low. MD5 results in a 128bit number meaning that there are 3.4x10^39 possible results.
🤘GAS PARTICLES 🤘
Weird, yet fascinating concept
You didn't mention that the Romans knew that crowds of people act similarly to a fluid. Vomitoria are the large entrances into stadium seating, and the name comes from Latin for "to spew forth". There's a misconception that this spewing was of food, but it was actually just people being treated as a fluid.
So you talk about cryptography and fluids, and dont mention the Lava lamps? :)
An entire wall of them perhaps?
@@jimmystyles670 At Google
@@BertGrink Not Google, but Cloudflare's SF office.
@@frankschneider6156 I didn't know about Cloudflare, but 2 years ago, Tom Scott made a video about how Google uses lava lamps to keep the internet secure: ruclips.net/video/1cUUfMeOijg/видео.html
@@BertGrink That is about Cloudflare.
Which incidentally is a company that does more harm than good usually.
I don't know what makes me more happy.
Thinking of webpage logins as a coffee
Or thinking of coffee as a login.
I think this issue suffers from the same semantic problem that the "speed of light" has. Lightspeed isn't really the speed of light, just like fluid dynamics isn't really about the dynamics of a fluid. They are simply shared emergent properties that arise from similar systems.
I thought they were playing on Travis Scott's Astro World concert. But this came out a year ago! Wow.