With the previous ELI12 under control, let's ELI>12 overhead line catenary a little more. For instance, why do you need tension in the first place?

Fact of the matter is that using a rigid conductor is problematic with high voltage AC (skin effect and such), plus it's more visually intrusive than wires. Meanwhile, a wire will sag, regardless of how much tension you can practically apply. So you need a few devices to help keep the wire at height.

For one, the wire is supported every few dozen metres. Secondly, there's a second wire strung above the first one. And while both wires are pulled taut, there are dropper wires between the upper and lower wires, which vary in length. Longer near the poles, while at the shortest near the middle between two poles, which creates a structure similar to a suspension bridge to keep the contact wire within a tight margin of vertical space.

In case people don't want to click a link, let me explain it here:

If you want to use overhead line electrification, you need to suspend a wire over the rails. In theory, you could simply hang up a wire, but whichever amount of tension you choose, if it's warmer outside, the wire will droop, potentially causing damage, while if it's colder outside, the wire will pull taut and may snap. So you want a system to account for external temperature.

Instead of picking a tension at a standard installation temperature, you pick an amount of desired tension and use weights to pull it taut. Now, if the wire heats up and extends, the weights drop, and if the wire cools down and contracts, the weights are pulled up.

And to keep the amount of weight you need to add under control, you use a series of pulleys to control the tension in the wire.

In NL, the mainline system looks a lot simpler: They have only one wheel, but that's two pulleys: a larger one and a smaller one. The larger one holds the weight, while the smaller one holds the wires.

(do it again now!)
Hard like heroic, more than you can handle

Take any tech bro take on transit, and if you try to perfect it, you'll almost always end up with a train.

Relevant xkcd about these xkcd's:

Every sixty seconds, a woman in Britain gives birth. She. Must. Be. Exhausted.

To be Devil's Advocate:
Given that the rest written in Comic Sans, it may be an early elementary school exercise, aimed at teaching kids to do multiplications. In this case, it's tolerable and/or defensible to find a simplification for pi.

That said, making pi equal to 3 would have been more accurate for that...

Men, do yourself a favour.

If a girl ghosts you because of the phone you use, she's clearly too shallow to bother with, and it's worth ghosting her back.

Girls, do yourself a favour.

If you've got a problem that a guy uses a 'droid, you may want to reconsider your priorities.

Same. Though can we also add a button to hide all content pertaining to US state politics? "The governor of Arkansas-" I live in The Netherlands, that shit has no bearing on me

I remember someone got into such a billboard and replaced the ad with IKEA-style instructions on how to replace the ads in those billboards.

Can somebody build & sell a dumb electric car? Or at least one not permanently internet-enabled and/or that has no functionality and capabilities locked behind software and subscriptions?

Let's face it, he's trying to build a vacuum tube over many hundreds of km's. The energy you need to keep that at reduced pressure is more than a Little Boy or a Fat Man. The pods are the size of somewhere between a coach and a railway carriage, with seating built to Frecciarossa Executive Class. It's propelled using Maglev tech, so you need a not-insignificant amount of power to also move your pods. And getting into or out of your vactube is going to take some extra work.

One thing that I've seen being pointed out by some critics is that a maglev system is often quoted to cost about a billion per unit distance, while high speed rail is quoted at about 500 million, about half. But then the Hyperloop shows up and is quoted at 250 million. How do the economics of that work? I mean, you take a maglev, which is twice as expensive as conventional but very precise regular railway, but by adding a vacuum tube, which is an added system that takes a ton of energy to even get it start making operational sense, you somehow cut costs in half from effectively a regular railway? I'm no economists, but that makes no economic sense.

The tech looks really snazzy in CGI renderings until you start to look into the engineering and physics to make it actually work. At which point it becomes awful.

So what if we tried?

First thing, the vacuum tube has to go. This is the number one obstacle preventing it from ever working. We'll still accept the special right of way for high speeds though, we'll just make our pods amazingly aerodynamic. Given the fact that our constraining factors may just become simpler, we can rig our pods to form a hyperpod chain, which allows us to bundle power and improve reliability and efficiency via an economy of scale. We can lower the seating quality in some of these pods and sell those seats for a lower price, making up for it in volume. We can still power everything with green energy, we're still using our own hyperway, with a very narrow path that our hyperpods can take, so rigging up an electrification scheme via an infrastructure power supply is quite easy. If we want to deploy quickly and make true on our 250 million quid per unit distance, we may have to rely on proven technology, so we probably base our new hyperway structure on two steel beams being kept a fixed distance of 1435mm apart. Bonus: there's a lot of largely compatible infrastructure at both ends that we can now use, as well as a giant pool of trained professionals around the world, so we can cheap out on stations and hyperway maintenance can be quite cheap and quick.

I just invented a train again, didn't I?

Elon is a con artist and I will take no criticism.