JemmyClever guy
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The Picard Maneuver@lemmy.world
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The Picard Maneuver@lemmy.world
A high voltage electric fence. At some point even standing in front of the thing is enough.
Air only has so much resistance itself. High enough voltage and the closest path to ground is where the charge will go.
Just like with Lightning
Humidity in the air makes that wayyy more dangerous because your skin will be highly conductive and the lower the resistance, the higher the current (which is what really hurts).
I’ve been a human grounding strap a couple times and don’t recommend it. I think the vibrating pain of AC (someone reenergized the outlet on me) is worse than the punch of high voltage (failing spark plug wire I grabbed with metal pliers while diagnosing a misfire).
My arm once got pulled into an electric fence when I was a kid and I couldn’t stop getting shocked until someone physically pulled me away. It was more of a self-control issue than accidentally bridging the gap.
That was the day I learned that some pain can be pleasant. The owner of the property didn’t seem as pleased with my discovery as I did. He had to shut off the fence and yanked my arm away and then told me to go explore my perversions somewhere else. I was too young to understand the word “perversion,” and I’m now eternally grateful to that poor unprepared rancher.
For more fun form a chain with other people and be the furthest from the person touching the fence.
You find it enjoyable? I regularly touch electric fences, but not because I want to but because I’m too stupid to think of another way to figure out if the thing is working. I find it to be the opposite of pleasant.
Oh. Here’s your fix:
A longish piece of green grass. Hold it by one end, then slide it on the fence wire like the grass was a violin bow, getting your fingers closer and closer to the fence. At some point you notice a pinging, or your fingers are touching the fence.
You can use this to gauge, very roughly, how powerful the charge is at that point.
I never said it was pleasant. But sometimes some types of pain are the right kind of pain.
Example of the opposite: when I’m swapping a switch in my old-ass house, sometimes I’m too lazy to turn off the breaker. When I inevitably shock myself, I say “dammit” because I’m trying to concentrate, not discover my preteen proclivities.
Edit: well slap me silly and call me a liar, I literally said the words “some pain can be pleasant.” I blame this error on undeserved confidence and complacency.
This paints a funny picture and caused a chuckle
At approx 3kV/mm, you would have to be pretty close to a 10kV fence.
Humidity plays a big role as does the frequency that the fence is running on. But you would be pretty safe standing a meter away, on that dry sunny day in the picture.
Also above a point, the high voltage causes the conductors to buzz.
Dry? It was a carribean island, right? Probably humid as fuck.
Yes, but it isn’t hosing down with rain…
It was the night before.
That buzzing sound is terrifying, by the way, if you’re close enough to a very high voltage.
In some way it is comforting, you know the power is where it is supposed to be… Walking around a 11kV switchyard that buzz is good.
An interesting way to hear this without endangering yourself is to be near transmission lines in a light rain. Some go over a local park near me, and it’s wild how well you can hear it sometimes.
If I'm not mistaking the buzz is because it's AC hence the buzz frequency is the same as the AC's.
Certainly it makes sense that the high voltage would be generated from mains power using a big fat transformer since that's probably the simplest way to do it.
Yep.
The highest DC voltage I have been near is around 1000V, it didn't buzz, but 1000V AC also doesn't buzz....
10/3 millimeters away, to be precise.
With enough voltage, everything is a conductor.
I have a 10KV electric fence. 5KV to 15KV is typical electric fence voltage in a farm or bear prevention fence. Can’t feel a thing unless you actually touch it.
They are also not lethal. Very low current, just very high voltage. So it only hurts like fuck, but won’t kill a human, cow, or any other mammal that touches it.
They can’t kill you, but I know from experience that they can knock you out for a bit if you get shocked through your head.
They can kill an animal (including a mammal) if they become entangled and give up out of suffering, though.
This is pretty rare, but can happen.
It’s virtually zero risk to a human, though, who can cognize things like getting their hand disentangled from a string (even in a panic situation), or to most mammals, which tend to jerk backwards on contact.
This is why you should never try to remove a tree from a power line yourself.
Electricity always takes the path of least resistance back to the source. A tree, and possibly your body, may end up being the “path of least resistance”.
You won’t know if YOU are the path of least resistance or it the line is even energized until it’s too late.
Yup, this is why I shoot fallen tree limbs with a shotgun.
Off of power lines, right?
Yup, nothin’ like a little buckshot in the mornin’.
Yeah for when the little plants and leaves and dandelion wisps fall near my deck I got some anti vermin shot rounds for the .38
At 10,000V and at sea level, you need to be at about 4mm from that fence for the air to arce.
A few posts above I was curious and actually went and checked it.
Also, a high voltage electric fence with indicator lights that he already knew were off.
about 10kV per cm i believe. you're only at risk of it arcing to your body if you're within a centimeter of the wire. and that assumes your body to ground is a good conductor (it's not)
As a PhD who has tried doing home improvement projects, it’s the most believable thing in the film.
Some pleeb shouted at me, “I thought you were an engineer!” And I shouted back, “A software engineer!” while I hammer a nail with my shoe.
Ah, a C programmer.
I’m a regular engineer and yeah I pull such shit. Listen, there’s a reason I tell everyone not to do what I do.
The difference between a regular idiot doing a dangerous job and an engineer doing a dangerous job is the engineer knows which parts of the job he’s risking imminent death on. There may often be no other difference.
When it comes to an engineer doing a dangerous job in a domain other than his or her own, I would say that all the engineer knows is how bad things can be fucked up when one is trying to do expert stuff outside one's own domain, because they've been in a position were they were the experts and some non-expert was saying things and trying stuff for their expert domain.
After seeing others do it in one's own expert domain one generally realizes that "maybe, just maybe, that's exactly how I look outside my domain of expertise to the experts of that domain when I open my big fat mouth".
Really?
Genuinely asking, I’m just an engineer… with very very bad grades. Passed was enough for me.
Once a professor asked me if I wanted to take the exam again because it was clear that I knew more than what I showed on the exam (a lot of 2 + 2 = 5 mistakes, I was fairly good at that and owe most of my low grades to that). I asked him if I passed, he said yes. Fuck that shit, I’m taking that grade and parading it across town, wooohoo 🥳.
As they say, a PhD is about learning more and more about less and less. Some of the smartest people at conferences I've attended legitimately risk death crossing the street.
Lol 😂, reminds me of some of the professors at uni 😂.
Actually some of the most naïve people I’ve ever met were theretofore academically successful.
My fiancee has a couple degrees while I just graduated high school. She’s incredibly smart but I’m definitely more street savvy. She grew up a bit sheltered.
At 10kV, a random stick would be all it takes to start an arc. He knows what he’s doing.
True, True… Hay who thought it was safe to run 10,000V Wire through a flammable overgrown jungle?
The people who wouldn't cry about a dino BBQ scenario.
I'm genuinelly curious were you got that from.
I actually went and checked the minimum air gap to avoid arcing at 10,000V at standard sea level air pressure and it's actually measured in millimeters.
Further, is the voltage differential there between parallel conducting lines or is it between the lines and the ground?
I'm really having trouble seing how a dry stick would cause arcing between two of those lines short of bringing them nearer than 4 mm in the first case, much less between one of the lines and the ground in the second case if its being held at chest level.
PS: Mind you, it does make sense with a stick which is not dry - since the water in it makes it conductive - but then the guy himself would be part of the conductive circuit, which kinda defeats the point of using a stick.
What you want to do is create an arc between the stick and the line, and not have it transfer to you. A dry stick would do this quite well, since it would be at ground voltage and as such would provoke a short arc without electrocuting yourself. The fence also probably doesn't have all that much power, likely can't deliver more than a few amps, so it would be quite safe even.
IIRC, he was messing with the kids and knew it was off because the lights were off. He proceeded to put his hands on it and convulse wildly as a joke.
He was messing with the kids when he grabbed the wires, not when he threw the stick.
Selling the bit is important too
I always saw it as being part of messing with the kids, he looks at the warning lights on top of the fence first. And for my headcannon at least, Grant is savvy enough to know that’s no way to test if the fence is live or not, lol.
As someone who has worked with academics, the more specialised the person, the less common sense they seem to hold onto.
As such, if this was outside their PhD specialisation, then it'd absolutely make sense that this wouldn't occur to them.
My professor (computer science - NP complete problems specific) had a theory.
Higher up your education, more and more you learn about less and less.
I am convinced he accidentally stumbled across Buddhism all on his own (he was a religious Christian, the generous, do not judge others kind). Because Buddha seems to have done his PhD in nothing. Even "wrote" the whole dissertation on nothingness.
My university basically gave up with a couple of professors. They hired a personal assistant, full time, just to try and keep them organised. They apparently settled on 3 phone calls, to make sure they made lectures on time. It even extended to things like reminding them to actually get their wives birthday presents, and personal book keeping.
It seems the human brain has a capacity limit. The more specialist knowledge shoved in, the less room for more normal knowledge. Eventually it displaces even the most basic common sense.
Meet the German word *Fachidiot*: (derogatory) A person who is only interested in their own trade or research area and has few or no other interests or skills.
I'd like to report that the more specialized a medical doctor is, the less common sense they have.
Had a doctor chew me out because he couldn't be bothered to simply turn the computer on.
That was the issue. Pushing a button was beneath him. Cool man, I'm the only one here at this hour and the phones have to be manned constantly. That ticket can go to another department and wait until they come in morning.
Also, low priority and I noted that the doctor refused to simply turn it on.
I think that ticket sat there for over a month.
He must have skipped all of the Electrical Engineering classes in his Paleontology program.
Well, I have an EE Degree specialized in Digital Systems - pretty much the opposite side of Electronic Engineering from the High Power side - and I would be almost as clueless as that guy when it comes to testing a 10,000V fence for power.
On the other hand I do know a lot of interesting things about CPU design ;)
What’s the most interesting thing you could tell us about CPU design, something that a layman could appreciate.
You should know as a software developer I write inefficient code and appreciate all the extra clock cycles we get these days haha.
First a fair warning: I learned this stuff 3 decades ago and I've actually been working as a programmer since then. I do believe the example I'll provide still applies up to a point, though CPUs often implement strategies to make this less of a problem.
=====
CPU's are internally like an assembly line or a processing pipeline, were the processing of an assembly instruction is broken down into a number of steps. A rough example (representative but not exactly for any specific CPU architecture) would be:
- Step 1: fetch assembly instruction from memory
- Step 2: fetch into the CPU data in memory that the instruction requires (if applicable).
- Step 3: execute arithmetic or binary operation (if applicable).
- Step 4: evaluate conditions (if applicable)
- Step 5: write results to memory (if applicable)
Now, if the CPU was waiting for all the steps to be over for the processing of an assembly opcode before starting processing of the next, that would be quite a waste since for most of the time the functionality in there would be available for use but not being used (in my example, the Arithmetic Processing Unit, which is what's used in step #3, would not be used during the time when the other steps were being done).
So what they did was get CPUs to process multiple opcodes in parallel, so in my example pipeline you would have on opcode on stage #1, another that already did stage #1 and is on stage #2 and so on, hence why I also called it an assembly line: at each step a "worker" is doing some work on the "product" and then passing it to the next "worker" which does something else on it and they're all working at the same time doing their thing, only each doing their bit for a different assembly instruction.
The problem with that technique is: what happens if you have an opcode which is a conditional jump (i.e. start processing from another point in memory if a condition is valid: which is necessary to have to implement things like a "for" or "while" loop or jumping over of a block of code in an "if" condition fails)?
Remember, in the my example pipeline the point at which the CPU finally figures out if it should jump or not is almost at the end of the pipeline (step #4), so everything before that in the pipeline might be wrong assembly instructions being processed because, say, the CPU assumed "no-jump" and kept picking up assembly instructions from the memory positions after that conditional-jump instruction but it turns out it does have to jump so it was supposed to be processing instructions from somewhere else in memory.
The original naive way to handle this problem was to not process any assembly instructions after a conditional jump opcode had been loaded in step #1 and take the processing of the conditional jump through each step of the pipeline until the CPU figured out if the jump should occur or not, by which point the CPU would then start loading opcodes from the correct memory position. This of course meant every time a conditional jump appeared the CPU would get a lot slower whilst processing it.
Later, the solution was to do speculative processing: the CPU tried to guess if it would the condition would be true (i.e. jump) or false (not jump) and load and start processing the instructions from the memory position matching that assumption. If it turned out the guess was wrong, all the contents of the pipeline behind that conditional jump instruction would be thrown out. This is part of the reason why the pipeline is organised in such a way that the result of the work only ever gets written to memory at the last step - if it turns out it was working in the wrong instructions, it just doesn't do the last step for those wrong instructions. This is in average twice as fast as the naive solution (and better guessing makes it faster still) but it still slowed down the CPU every time a conditional jump appeared.
Even later the solution was to do the processing of both branches (i.e. "jump" and "no-jump") in parallel and then once the condition had been evaluated throw out the processing for the wrong branch and keep doing the other one. This solved the speed problem but at the cost of having double of everything, plus had some other implications on things such as memory caching (which I'm not going to go into here as that's a whole other Rabbit Hole)
Whilst I believe modern CPUs of the kind used in PCs don't have this problem (and probably also at least ARM7 and above), I've actually been doing some Shader programming of late (both Computing and Graphics Shaders) and if I interpreted what I read correctly a version of this kind of problem still affected GPUs not that long ago (probably because GPUs work by having massive numbers of processing units which work in parallel, so by necessity they are simple) though I believe nowadays it's not as inadvisable to use "if" when programming shaders as it used to be a few years ago.
Anyways, from a programming point of view, this is the reason why C compilers have an optimization option of doing something called "loop unrolling" - if you have a "for" loop with a fixed number of iterations known at compile time - for example
for(int i = 0; i < 5; i++){ /* do stuff */ }- the compiler instead of generating in assembly a single block of code with the contents of the "for" loop and a conditional jump at the end, will instead "unroll the loop" by generating the assembly for the body of the loop as many times as the loop would loop - so in my example the contents of that "for" loop would end up as 5 blocks in assembly each containing the assembly for the contents, one after the other, the first fori=0, the next fori=1and so on.As I said, it's been a long time since I've learned this and I believe nowadays general CPUs implement strategies to make this a non-problem, but if you're programming microcontrollers or doing stuff like Compute Shaders to run on GPUs, I believe it's actually the kind of thing you still have to take in account if you want max performance.
Edit: Just remembered that even the solution of doing the parallel execution of both branches doesn't solve everything. For example, what if you have TWO conditional jump instructions one after the other? Theoretically would need almost 4 or everything to handle parallel execution for it. How about 3 conditional jumps? "Is you nested for-loop screwing your performance? More news at 11!".
As I said, this kind of stuff is a bit of a Rabbit Hole.
Ah ah ah...
You didn't say the magic word
Is his PhD in Electrical Engineering?
Just because you’re very good at one thing doesn’t mean you’re good at another. Sometimes the further you go down one path, the less you know about everything else.
He must be a real good paleontologist to forget that wood is a bad conductor.
He was so good that John Hammond sought him out to invite him to the park to check it out before it opened.
Hammond didn’t pick him, the insurance company did. The company insisted on only him, likely because he was a notorious skeptic who would be able to look past the sensationalism of the dinosaurs to let them know a realistic risk assessment. The dinner scene where he and Ellie criticize Hammond is exactly why they wanted him there.
Point being, no indication is actually given that he was smarter or more published than the others in his field, because that isn’t really what the insurance was after.
I could be wrong but I remember Hammond choosing Grant, not the insurance company
No it’s the insurance company. It’s that scene the very beginning where the lawyer is going to visit the the guy digging for Amber. He’s the lawyer for the insurance company, he mentions that he’s going to get Grant. Then the other archaeologist says he won’t get Grant cuz Grant’s a digger. Which now I think about it I guess means that Hammond is interfering with the impartiality of the evaluators by bribing them.
Here’s the transcript
Scroll down to “The Encased Mosquito.” Hammond wasn’t even in the scene.
They didn’t have electric fences in the jurassic era, duh. /jk
Yeah that’s people with PhDs in my experience
Yeah, in this case it’s so high voltage that the resistance of the dry stick wont mean as much.
I invite you to touch an electric fence with a stick then.
I’ve installed a few, and you do have to test them somehow.
Best way is a long piece of grass, hold it about 30cm down and touch the other end to the fence. Most you get is a little tingle
i'm not touching your stick man, gross!
You’re describing my pre-internet childhood.
(It wasn’t a 10k volt t-rex fence though)
With your stick?
Wet wood from the ground is probably a better conductor than dinosaur scales
Did dinosaurs have scales?
They couldn’t even read music at all 😞
They sold a lot of coke though
I dont think so, bananas are a relatively new thing iirc.
Mmmmmh, nom nom nom nom.
That’s exactly the right amount of dopamine hit I’m scrolling for. Now I can turn off my phone and roll over to sleep. Thanks bud 👌
Obviously: how would they weight themselves otherwise?
Why would they? Dinosaurs were notoriously body positive
They did in Jurassic Park
Literal lol
I don’t remember the scene, but personally I’d test an electric fence with a nonconductor. You’ll probably get some sparks but won’t die. You do you, ppl in this thread.
Clearly his PhD is not in electrical engineering or biology
It’s actually a PhD in trombone. Someone misheard it one time, and nobody has ever thought to follow up.
“Oh, Alan? Yeah, he has a doctorate in bones or something.”
His job is beach
Hey it's a "It's a UNIX system" movie, isn't it?
Did you know the weird 3d file system navigation thingy was a real program (just not widely used)?
But I can't get over the way she held the mouse lol
The funny thing about that quote is that it really was a Unix system that was shown on screen.
What was the name of the 3D file manager again?
It had a wonderfully bizarre name: *fsn*
I know that!
He probably wanted to prevent significant arcing by using a higher impedance test apparatus due to the high voltage.
Oh yeah everyone knows electricity
.
Anything conducts electricity if there is enough of it.
It looks so easy, and it is easy, but then it kills you.
At least he's smart enough to know you Don't whizz on the electric fence
Mythbusters did it.
not a phd in physics huh
Yep. Very domain specific knowledge but couldn’t pour piss outta a boot with the instructions on the heel.
The first film paints a different picture.
The whole point of his story in that film was his growth and development, started saying “kids smell” and ended holding two of them safe.
He was the one throughout who kept his head, stayed competent in the face of fear and dealing with chaos.
Characters in Jurassic Park are portrayed as flawed, imperfect people who make mistakes. None of the plot relies on them being idiots or anything, but people screw up, panic on occasion, and don't know things from time to time.
Dr. Grant using a stick to test the fence is a mistake, albeit a small one without real consequences. While it doesn't distract from his character arc of how he feels about kids, it is his character simply messing up.
I also disagree with the person you replied to. While their assessment is correct, Dr. Grant is a character with a lot of time working in the field and therefore has a lot of practical skills. He does way, way better than a doctorate in mathematics working in academia would. Writing off *all* people with a doctorate (or experts in general) as being hyper specialized is a mistake.
He is already standing too close and that stick would arc with that many volts flowing through it. The most likely outcome in reality if it had been energized. The arc would have jumped from the stick to him and no more New Zealand guy.
With only 10'000 V? That's a common Livestock Guardian*. Reaches at most 1 cm.
* though it probably has enough ampere to kill a cow
Now if he'd just tossed the stick at it longwise so that it touched several wires at the same time, it might get a result. I'm personally not sure how much a reaction you'd get out of dry wood with 10,000 volts. Stripping the bark off of green stick with definitely be better, or a wet stick. Although if electricity arced through the stick at least it probably wouldn't kill him because of the amount of resistance that stick has.
You ever saw a electric fence at a high security installation? I just texted a guard at nearby prison and he said theirs are 5000 volts. He said when its humid they tingle when you get a few feet away. He also says they will kill you dead. He goes on to say its why they have another fence as a barrier to prevent people who don't respect them from killing themselves. I know the ones at a nuke were marked lethal and would kill birds from time to time. They were just marked high voltage but the plant guys told us they were very high voltage at a higher frequency.
Yep, Volt makes sparks, Ampere makes hurt.
Tesla coils usuallly have around 100k Volt and don't kill you. Tasers 20k to 40k i think? The high voltage in guardians is mostly so that it connects.
I always thought that was a piece of fence.
Idiot didnt know the MAD was 2’2", SMDH.
Considering these fences are enough to take down dinosaurs, it may set the end of the stick on fire from the resistance, so still works?
Why people gotta hate on a movie three decades old that remains perfect?
Gotta meme to keep it alive
Even throwing a metal pipe against it won’t do anything. Electric fences have one electrode in the ground, and that’s how your body makes the circuit. If they had run and jumped onto the fence, then jumped off on the other side they would have been fine with the fences still active.
Source: I’ve set up an electric fence and been shocked multiple times, once through my head.
You’re assuming the dinosaur fence operates on the same principal as a regular livestock electric fence. I put it to you that the Dino enclosures use alternating positive and negative stringer wires, where touching one won’t do anything, but touching two will make a short circuit.
That would make a lot of sense, but as we can see the stringers are connected together, meaning they’d just short out if they were alternate polarities. To me this indicates that it’s like a standard livestock fence, with an electrode in the ground somewhere and the circuit completing through the animal.
However, considering my 16’x48’ pig enclosure required a three-foot rod to be grounded, a system large enough for a sauropod would need a lot of grounding. Considering this, the fact that they used a circuit-through-animal design indicates it probably wasn’t the best way to do it.
Spared no expense…
Maybe the stringer spacers are polymer though. Like those separation bars you see on residential power lines
Maybe they’re polymer but they look pretty metallic and there’s an awful lot of them. Plus if the stringers are under enough tension for a full grown man to climb them they wouldn’t need separators.
uhm, I’ve seen (touched, oops) electric fences (low power tho) with both conductors in the wire, uncovered but not touching.
Yet Tim gets shocked when hanging on the fence when it turns on while he’s climbing down. I trust movie science far more than your acquired knowledge. Your ignorance is probably what’s holding you back from full blown deity.
Ever seen birds standing on powerlines?
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Yeah. Therefore the wood won’t do anything.
The higher the voltage, the less the electricity cares how good a conductor something is. Air is a shitty conductor, and yet, lightning doesn’t give a shit.
How good of a conductor wood is depends on its state. If it is very dry and not salty, this should be safe (although he could have taken the piece of wood more at the end to increase the distance between him and the fence and the length=isolation through the piece of wood). If it is wet and salty, it might be dangerous.
There was a major storm just a few hours before this, so the wood is likely wet. However, he threw it against the fence; he wasn’t touching it when it made contact with the wires.
I never thought about that. Lol.
A PhD wouldn’t know anything about science, so its pretty accurate really :/
Edit: It’s the internet so naturally im being downvoted for learning but after looking it up, I was wrong. The PhD does stand for philosophy doctorate, but no longer refers specifically to the feild of philosophy as it once did. Apologies to anyone offended.
You realize you can have a PhD… in science? (Any specific kind of science you wanna pick.)
You can get a philosophy doctorate in science? Honestly no, I didn’t realize that at all
The trick lies in philosophy coming from Greek philosophia which is love for/love of wisdom. It never referred to what we understand as philosophy, but rather affinity for studying.
That's interesting, I wonder why they differentiate some like MDs and EDs but not others.