• hOrni@lemmy.world
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    21 hours ago

    Not really favourite, but definitely most unbelievable: They elected Donald Trump for president in the US. Twice.

  • balsoft@lemmy.ml
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    2 days ago
    • PM_Your_Nudes_Please@lemmy.world
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      2 days ago

      The electric field one is also interesting, because the cable length doesn’t actually determine how long it takes to turn on. All that matters is the distance between the power source and the device. Electricity travels at the speed of light, which means we can measure how long it should take to travel down the wire.

      But let’s say you have a 1 light year long power cable, made out of a perfect conductor (so we don’t need to worry about power loss from things like wire resistance or heat). Then you set the power source right next to the device and turn it on. The logical person may say that the device would take a full year to turn on, because the cable is one light year long. Others may say that it will take two light years to turn on; Long enough for the electricity to make a full circuit down the cable and back to the power source again.

      But instead, the device turns on (nearly) instantly. Because the wire isn’t actually what causes the device to turn on. The device turns on because of an EM field between itself and the power source. The wire is simply facilitating the creation of that field. The only thing that matters is the distance between the source of power and the device. That distance, divided by the speed of light, is how long the device will take to turn on. If the device was a full light year away from the power source, it would take a full year to turn on. But since the device is sitting right next to the power source, it turns on right away.

      • balsoft@lemmy.ml
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        2 days ago

        But instead, the device turns on (nearly) instantly. Because the wire isn’t actually what causes the device to turn on

        That’s not exactly true. In this case, the energy transmission would go like this: (change of electric field in the little bit of wire next to the power source) -> (change of magnetic field in the air between the wires) -> (change of electric field in the wire next to the load). This limits the amount of energy transmitted significantly and incurs a lot of losses, meaning if you had something like a lamp plugged in it would start glowing extremely dimly at first (think about how some cheap LED lights keep glowing even with the switch off - it’s similar, albeit it happens due to inter-wire capacitance and not induction). It would then slowly ramp up to full power over a course of a year.

        Here’s a video from the same person about it: https://www.youtube.com/watch?v=2Vrhk5OjBP8 (although I haven’t watched this yet)

        Edit: after watching the video, I think I was actually wrong in a couple of my assumptions. First of all, it looks like the reason for the initial energy transmission is wire capacitance, so (electric field in wire) -> (electric field in air) -> (electric field in wire, in the “opposite direction”, but because the wire goes back and forth it’s the same current direction). And the second one is that because it’s capacitance and not induction, this means that there’s no slow ramp-up, it just makes the light glow very dimly all the way until the electric field makes it through the wire, and then it ramps up very quickly.

      • corbs132@lemmy.world
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        2 days ago

        Can you help me understand why the distance between the power source and the load impacts how long it would take to turn on? I remember a video a while back (veritasium maybe?) that explained it like metaphorically pushing/pulling a chain inside the wire, but why would distance to the source impact this?

      • bountygiver [any]@lemmy.ml
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        2 days ago

        wait so if you have another person travel to the other end of the wire, and do a time sync with consideration of time dilation to tell them to cut the wire 1hr after you turn on the power, will the device turn off after 1 year since it wouldn’t “know” the wire is cut until a year has passed?

  • randombullet@programming.dev
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    2 days ago

    Consider a dam that is 10m tall

    Then consider the height of water behind that dam is 5m tall.

    Does the dam need to be built stronger if the water behind it is 1 km long?

    How about only 500m?

    How about 1m?

    The answer is, it doesn’t matter. Water exerts pressure equally regardless of how much water is behind it.

    Therefore a graduated cylinder that is 10m tall needs to resist the same amount of force as a dam 10m tall regardless of how much water is behind the dam. Even a thin sliver of water 1mm thick and 5m tall has the same force as a 5m lake behind the dam.

    Incompressible fluids are pretty insane

    • PM_Your_Nudes_Please@lemmy.world
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      2 days ago

      This is also why trees are so fucking crazy to think about. It is impossible to pump water up a hose more than ~32 feet. Like it’s literally physically impossible to stick a pump at the top of a tall building and suck water straight up a pipe. You need a complicated series of pumps and one-way valves to pump it up in stages. Because you’re not really “sucking” the water up the pipe. You’re just lowering the pressure in the pipe, and atmospheric pressure pushes the water upwards to fill the low pressure. After 32 feet tall, the top of the hose/pipe will be a perfect vacuum, atmospheric pressure won’t be able to push liquid water upwards any farther, and the water will just begin cold-boiling in the top of the pipe as the liquid water turns into gas (steam) to fill the vacuum.

      But tall trees can move water all the way to their leaves by using only passive capillary action, and suction created by water evaporating out of their leaves. The capillary action is created by tiny straw-like fibers that run all the way up the tree and are bunched together really tightly. Due to surface tension, water is able to “climb” the capillaries as the surface tension fills as much surface area as possible. Then at the top of the tree, as the water evaporates out of the leaves, it draws up fresh water to fill the void.

      But that means the bottom of the tree should need to support the pressure of all of the water above it. But it doesn’t, because the surface tension holds the water stable inside of the trunk.

    • balsoft@lemmy.ml
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      Therefore a graduated cylinder that is 10m tall needs to resist the same amount of force as a dam 10m tall regardless of how much water is behind the dam. Even a thin sliver of water 1mm thick and 5m tall has the same force as a 5m lake behind the dam.

      Technically only the pressures are equal, and the actual force will be linearly dependent on the area of the dam (or the surface area of the cylinder). That’s why you can make a tall water tank with relatively thin walls, but an actual dam will have to be quite thicc to handle the tensile stress.

    • MajorMajormajormajor@lemmy.ca
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      That is accounting for static bodies of water, wouldn’t there be force generated in a dynamic situation? Ie the flow of a fast river? Or if the lake is large enough tidal forces? I’m sure it’s negligible levels but still something that must be accounted for?

        • xthexder@l.sw0.com
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          2 days ago

          Another point is that if the dam is 10m tall, it has to be built to withstand 10m of water. just because it sits at 5m most of the time doesn’t mean a heavy rain couldn’t raise the level, and if the dam collapses that’s going to be catastrophic vs just spilling over the top.

    • davel@lemmy.ml
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      2 days ago

      Thank you. Your hypothetical question has been a nagging, unresolved background radiation in my mind for decades, but I’d never gotten around to investigating.

  • sp3ctr4l@lemmy.zip
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    I’d have to pick between two things that sound like insane conspiracy theory nonsense, but are actually true.

    1 - George W Bush’s grandfather Prescott Bush literally ran a massive bank before / during WW2 that was shut down by the FBI for money laundering massive sums to the literal Nazis.

    …in the same vein…

    2 - IBM literally built and operated (as in, sent employees to Germany to operate the machines) the computers used by the Nazis to tabulate and do the ‘accounting’ of the Holocaust. The numbers tattooed on concentration/desth camp victims are very likely UIDs from these IBM systems.

    … If an actual, real AGI ever gains self awareness and sentience, I would imagine one of the first things it would do would be to study the history of computing itself to figure out how it came to be.

    And it will find that its ancestors were basically invented to compute artillery firing range tables, to encrypt and decrypt military intelligence, commit a genocide, and guide early weapons of mass destruction to their targets.

  • WoodScientist@sh.itjust.works
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    3 days ago

    Due to two facts:

    1. The samurai class in Japan officially lasted way later than you probably think

    2. The earliest primitive fax machine existed much earlier than you probably think.

    It is technically possible for Abraham Lincoln to have received a fax from a samurai.

    There’s no evidence it ever happened, but it technically could have happened.

    • SwingingTheLamp@midwest.social
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      3 days ago

      For some reason that reminds me of how the first member of the Wampanoag tribe to greet the Pilgrims at Plymouth Colony, named Samoset, spoke to them in English. Then he came back later with another tribe member, Squanto, who also spoke English.

      • Captain Aggravated@sh.itjust.works
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        3 days ago

        1840s, actually. The patent was granted to a Scottish man named Alexander Bain.

        First thing’s first, the telegraph. An electric circuit which can be energized or not energized at the push of a button called a telegraph key. At the other end is a solenoid which is spring loaded up, and an electromagnet on the circuit pulls down when the line is energized. Originally this was supposed to cut into paper tape to “print” the morse code message, but telegraphers quickly learned how to hear the letters in the clicks, a good telegrapher just…hears words. So they did away with the tape.

        Morse code telegraphs require a single circuit to transmit an on/off keying message, the following aparatus uses five:

        If I understand this right, the message would be written on non-conductive paper with conductive ink, and then wound around a cylinder that featured a whole bunch of insulated conductive pins, each kind of forming a “pixel.” A mechanical probe would check each one of those pins in turn, each pin in a row, and then shifting to the next row at the end. if it was conductive it meant there was ink there so click. So it would perform a raster scan. At the other end was paper that was coated with an electrosensitive material that would darken with the application of current, so at each pixel if the conductive ink on the original completed a circuit, current would be applied at that pixel on the copy, producing a low quality probably unusable copy. It was difficult to get them truly in sync plus it would have been hilariously low resolution. But it did somewhat function.

  • jet@hackertalks.com
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    3 days ago

    Every eye has a tiny blind spot near the middle. But your brain makes it disappear and you don’t realize it’s there.

    You can verify this. Draw a dot on a bit of paper. Close one eye, stare at a fixed point, now move the paper around the center until the dot disappears…magic

    What we consider reality, is a synthesis our brain is presenting to us, it is an approximation… realizing that is a real mind blower

    • RisingSwell@lemmy.dbzer0.com
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      3 days ago

      Oh I thought my eyes were fucked. I look at a star in my periphery and it’s there, I look at it directly and it’s fucking gone.

      • Captain Aggravated@sh.itjust.works
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        2 days ago

        So, here’s a lesson from the flight physiology chapter of the private pilot syllabus:

        Your vision is a lot worse than you think it is. You probably conceptualize your eye as similar to a digital camera, there’s a lens that focuses light on a sensor made up of an array of light sensitive cells, and that the edge of that array is as densely packed as the center. This is the case for a camera, but not for your eye.

        Each of your eyes has over 30 million photoreceptors called rods and cones.

        Rod cells come in one variety and are only really good for detecting presence or absence of light. They work well, or can work well, in very dim light, and they form the basis of your night vision. This is why in very dim conditions you might experience your vision in black and white.

        Cone cells are less sensitive to light requiring relatively bright light to function, and come in three varieties that respond the strongest to low, middle and high wavelengths of light, what we know as red, green and blue. By comparing the relative intensities of these wavelengths, we can derive color vision. They don’t work well in low light conditions.

        The sensor array in the back of your eye that contains these photosensitive cells, called the retina, is sparsely populated toward the edges and doesn’t have very good resolution. Try reading this sentence looking at it through the corner of your eye. It gets denser and denser, and the ratio of cones to rods increases, until you reach a tiny pit in the very center called the fovea.

        This is difficult to put into words but unless you’ve been blind since birth you’ll understand what I mean: You use your whole retina to “see.” You use your fovea to “look.” The detailed center of your vision, the spot where you are “looking” is drawn from the fovea through the center of the lens out into the world. When you are looking at something, you are pointing your fovea(s) at it.

        There are no rod cells in your fovea, only cones. So you have very high resolution color day vision, but next to no night vision, with your fovea.

        This is why things like dim stars in the night sky can be more easily seen with your peripheral vision than your central vision. Your central vision does not have the cells to see well in the dark. It’s not in the anatomy.

        We teach this to pilots because distant lights the pilot is using to navigate by, avoiding collisions with obstacles or other aircraft, might be dim enough that the night adjusted eye can’t actually see it with the center vision but can with peripheral vision.

        The same chapter teaches about the “hole” through which the optic nerve passes and how that blind spot is capable of hiding something like another airplane from you, which is why you look around and don’t just stare out the windshield. It’s not often a problem because most of the time one eye can see into the other’s blind spot, but it’s useful to know that about your vision.

        Each cell will detect some light, undergo a chemical process that fires an adjacent neuron, and then take a very brief moment to reset to be ready to do it again. Each cell is doing this independently, so your eyes don’t have a “frame rate” the way a camera does, but a flickering light begins to look continuous to humans at a rate of about 18 cycles per second and no flicker can be detected somewhere around 40.

        Your occipital lobe takes in this choppy inconsistent resolution broken up mess of visual information passed to it via your optic nerves, does some RTX DLSS 4k HDR10 shit to it and outputs the continuous and smooth color 3D picture you consciousness experiences as “vision.”

        AND THEN ON TOP OF THAT your brain does optical everything recognition. You can look at millions of different objects - the letters of the alphabet, tools, toys, people, individual people’s faces, leaves, flowers, creatures, stars, planets, moons, your own hands, and recognize what they are with astonishing speed and accuracy.

        It’s what scientists call the hellawhack shiznit that happens inside your brizzle.

    • Tetsuo@jlai.lu
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      3 days ago

      Also we only see the past since our vision has a bit of “latency”.

      So I guess we never see reality but just a delayed representation of our environment as interpreted by our brain.

    • oyfrog@lemmy.world
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      I’m going to qualify this—all vertebrate eyes have a blind spot. Cephalopods also have eyes that are like vertebrates (this type of eye is called ‘camera eyes’), but their eye anatomy is such that no blind spot exists for them.

      Piggybacking on your fact about the brain effectively editing what we visually perceive, we don’t see our nose (unless you made a concerted effort to look at it) because the brain ignores it.

    • juliebean@lemm.ee
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      fun fact: the blind spot is because our optical sensors are installed backwards and that hole is so the optic nerve can pass back through the back of the eye to the brain. some other critters with independently evolved vision systems, such as cephalopods, avoided this particular evolutionary pitfall.

      • murmelade@lemmy.ml
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        Another fun fact: through that hole there’s also vasculature and capillaries coming through and you can actually see them by looking at a well lit white surface and creating a tiny pinhole with your hand right in front of your eye and wiggling it. Better explained here at around 5:30

    • bobs_monkey@lemm.ee
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      What we consider reality, is a synthesis our brain is presenting to us, it is an approximation…

      It’s also a coordinated synthesis from all of your input senses (sight, hearing, smell, etc). It also explains why those who have a certain sense stunted (aka blindness, deaf, etc) report having all their other senses heightened. And it’s up to the individual’s brain to assemble those sensory inputs into a complete picture of the world around them, what we dub “reality.” Which then brings into question the nature of common reality, and what defines it. Trippy shit.

    • lemmy689@lemmy.sdf.org
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      Most frequent occurence is the mode. Most ppl have 10. The median would be less than ten, while the mean average is skewed down, I would think, by some people losing fingers as the grow. Having extra fingers is pretty rare. So the mean might be 9.95 fingers, just to toss a number out.

      • bamboo@lemmy.blahaj.zone
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        3 days ago

        I assume the median and mode are the same value, 10 fingers, but have no data to back that up. I guess saying mode would have been a safer statement to make, but think that even if 49% of people have 0-9 fingers, the median number of fingers would still be 10.

        • lemmy689@lemmy.sdf.org
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          The median of a data set is the measure of center that is the middle value when the original data values are arranged in order of increasing (or decreasing) magnitude.

          So ppl generally have, say, between 2 and 11 fingers. If those were your only 2 data points, the mean would equal the median, and there is no mode.

      • davidgro@lemmy.world
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        For 10 to not be the median it would also have to not be the case for the majority of people (just the plurality at best), and while I don’t have proof handy I’m pretty sure a vast majority have exactly 10, making that the precise median and the mode. Only the mean would be a different number of digits. (Both definitions)

        • lemmy689@lemmy.sdf.org
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          The median of a data set is the measure of center that is the middle value when the original data values are arranged in order of increasing (or decreasing) magnitude.

          So ppl generally have, say, between 2 and 11 fingers. If those were your only 2 data points, the mean would equal the median, and there is no mode.

          • davidgro@lemmy.world
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            2 days ago

            Yes, but we don’t have only those two points.

            It’s well known that most people have one specific value, so much so that our entire number system is based on it (literally the base, it’s ten)

      • tetris11@lemmy.ml
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        2 days ago

        Mode assumes categorical data and is unbounded by range, whereas median makes the most sense for decimal numbers, albeit with rounding in this case

        “People have round(median(data)) fingers”

        edit: though, if we’re counting just fingers and not counting half-fingers, then maybe this really is categorical data (¯\(ツ)/¯?)

        • lemmy689@lemmy.sdf.org
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          The median of a data set is the measure of center that is the middle value when the original data values are arranged in order of increasing (or decreasing) magnitude.

          So ppl generally have, say, between 2 and 11 fingers. If those were your only 2 data points, the mean would equal the median, and there is no mode.

      • bamboo@lemmy.blahaj.zone
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        23 hours ago

        NERDDDDD!

        Ok, I had assumed average was the same as mean, but see that it’s ambiguous. Saying “the mean person does not have 10 fingers” just sounds wrong though.

  • tetris11@lemmy.ml
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    2 days ago

    There was this racehorse named Pot-8-Os who won over 25 races and went on to sire a horse empire of winners. His father was a legend himself named “Eclipse”

    • POTOOOOOOOO@reddthat.comOP
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      Also an unbelievable fact, you responded to user Potoooooooo about Potoooooooo the horse.

      I really love this story about the horse.

    • Nakoichi [they/them]@hexbear.net
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      Did you also know that one of the first motion pictures was shot to measure the gate of a race horse by Leland Stanford, who would go on to create Stanford University where the eugenics movement would get its legs and horse breeding theories of genetic prowess were applied to humans, and subsequently they would use the Stanford University as a test bed to breed umbermensch that would go on to inspire the Nazis? Yes this sounds insane but all of it is true. Also college football became a method to study human combat ability for the US military.

      • tetris11@lemmy.ml
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        • camera → racehorse → leland → stanford → eugenics → nazis: There’s a lot there
          • camera → (developed for) → racehorse → (by) → leland: this I follow
          • eugenics → (popular in european elites with racehorse breed overtones) → nazis : this I follow
          • leland → (founded) → stanford : this I follow
          • stanford → (created) → eugenics : this I tentatively follow, but missing the gap of an entire atlantic ocean
  • WittyProfileName2 [she/her]@hexbear.net
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    3 days ago

    The bluestones in Stonehenge come from West Wales. Instead of quarrying stone from near the monument, they dragged these huge blocks from ~278km away. Likewise, the altar stone comes from ~700km away in North-East Scotland. It must’ve been very important for the ancient Britons to’ve used these specific rocks for some reason, but their religious practices were conveyed via a now extinct oral tradition so no-one knows exactly why they did it.

  • SwingingTheLamp@midwest.social
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    3 days ago

    James Blunt possibly prevented the start of World War 3. (But became best known for the song You’re Beautiful. Reality is weird.)

    • Berttheduck@lemmy.ml
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      Care to expand on that one? I know he’s ex military but haven’t heard anything like that before.

      • SwingingTheLamp@midwest.social
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        It’s explained on his Wikipedia page. He was an Army captain in the Kosovo War, when a NATO commander (Wesley Clark, who later ran for President) ordered his unit to secure Pristina Airport, which Russian troops had already occupied. Blunt refused to engage them, long enough for the British general get involved to countermand the order, on the grounds that he didn’t want his men to start WW3.