Oh yeah everyone knows electricity
.It looks so easy, and it is easy, but then it kills you.
Anything conducts electricity if there is enough of it.
Is his PhD in Electrical Engineering?
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!
Why people gotta hate on a movie three decades old that remains perfect?
Gotta meme to keep it alive
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.
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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 from 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.
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 you it’s actually the kind you have to take in account if you want max performance.
Ah ah ah…
You didn’t say the magic word
Wet wood from the ground is probably a better conductor than dinosaur scales
Literal lol
Did dinosaurs have scales?
They couldn’t even read music at all 😞
They sold a lot of coke though
They did in Jurassic Park
Obviously: how would they weight themselves otherwise?
Why would they? Dinosaurs were notoriously body positive
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 👌
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.
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.
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.
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.
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.
A high voltage electric fence. At some point even standing in front of the thing is enough.
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.
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.
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.
This paints a funny picture and caused a chuckle
For more fun form a chain with other people and be the furthest from the person touching the fence.
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
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 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.
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.
With enough voltage, everything is a conductor.
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.
That buzzing sound is terrifying, by the way, if you’re close enough to a very high voltage.
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.
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.
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…
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.
Also, a high voltage electric fence with indicator lights that he already knew were off.
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.
Scroll down to “The Encased Mosquito.” Hammond wasn’t even in the scene.
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.
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.
Selling the bit is important too
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I invite you to touch an electric fence with a stick then.
With your stick?
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
You’re describing my pre-internet childhood.
(It wasn’t a 10k volt t-rex fence though)
i’m not touching your stick man, gross!
I always thought that was a piece of fence.
not a phd in physics huh
