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Comment by rektide | Hacker News Reader

> If power and efficiency issues are resolved,

My gut feel is that this is a pretty grossly inefficient system by nature. Inducing current in seawater just to give magnetic traction something to push off against seems semi absurd.

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I mean rockets are absurd - burn gas to throw it behind you to push off against. Works in space (the NYT regrets the error).

https://www.nytimes.com/2001/11/14/news/150th-anniversary-18...

That's very true, but "efficient" isn't usually an adjective thrown at a rocket.

Uhhh I feel like rocket makers are obsessed with efficiency. A modest half a percent makes a huge difference in fuel fraction & lift capabilities.

Rockets may be broadly inefficient but they are as efficient as we can make them.

I understand. They're the only orbital game in town, and will be until <INSERT_PET_FUTURISTIC_THINGY>. I guess what I'm, saying, it's more that "efficient" isn't a word that pops up in your head when you imagine "rocket". It's like a demure Dodge Hellcat owner, or a contemplative WWE star.

semi absurd is kinda why DARPA exists!

What? VLSI, VHDL, Multics, Hypertext, GaAs semiconductors, autonomous navigation, GPS, and packet switched networking were a few things they funded. Totally absurd, right? For every successful tech, they probably explored scores that didn't pan out. Basic, high risk research has huge payoffs across society even if you don't like who's funding it or why.

So true. I read once that fundamental physics research on quantum tunnelling in Japan resulted in antennas that immediately reduced satellite dish sizes from meters across to the size of a dinner plate. Now you can connect with a modern smart phone.

I think that was the point.

While we all communicate using TCP/IP, invented as a DARPA program for robust communication in the event of nuclear conflict...

It's an urban legend. ARPANET was an overgrown university network.

And TCP/IP was one of many potential standard protocols

https://en.m.wikipedia.org/wiki/Protocol_Wars

The Register used to make fun of DARPA, saying things like “where every laugh is a mad cackle.”

Purely-electric devices tend to have this property that if you maximize or minimize something with no clear theoretical limitation, your efficiency grows all the way to 1.

On the case of this, my gut feeling tells me that making the magnet really, really big will do it.

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