this post was submitted on 05 Oct 2023
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[–] [email protected] 106 points 10 months ago* (last edited 10 months ago) (5 children)

This actually works. All you have to do is decelerate the train once (because it's spinning with the world while you build it).

And solve the trivial engineering task of reducing all friction and air resistance to zero. Oh, and that of getting on and off the train.

[–] [email protected] 52 points 10 months ago (1 children)

And solve the trivial engineering task of reducing all friction and air resistance to zero.

Well shit, anyone can do that. Just put a little WD40 on it

[–] [email protected] 3 points 10 months ago

(シ_ _)シ

[–] [email protected] 10 points 10 months ago (1 children)

You need energy to decelerate, though.

[–] [email protected] 30 points 10 months ago (1 children)

Just use magnets.
Pls send my Nobel price by mail, I'm not good at speeches.

[–] [email protected] 13 points 10 months ago

Fridge magnets are the secret of infinite energy

[–] [email protected] 10 points 10 months ago

You build your track dead straight - like, not conforming to the surface direct through the crust straight. Now the train accelerates downhill for the first half of the journey, and decelerates uphill for the second, neatly coming to a stop at the destination. Oddly enough, in the spherical cow universe where you build this, all the maths cancels such that you get a constant travel time regardless of the start and end locations. On earth it's about 40 minutes

[–] [email protected] 3 points 10 months ago

you could conceivably get on and off the train with shuttle "station" trains that travel on parallel tracks to catch up with the main train

[–] [email protected] 3 points 10 months ago

🤔 A vacuum tube maglev would do the trick.

Actually Isaac Arthur talks about something like that on his channel. An Orbital Ring, he calls it.

[–] [email protected] 69 points 10 months ago (1 children)

I think I had this idea when I was ten. I knew I should have patented it. Fuck.

[–] [email protected] 13 points 10 months ago

I swear I came up with the iphone... my design was a triple flip phone, screen up top, keypad in the middle and an ipod wheel down bottom

[–] [email protected] 57 points 10 months ago (1 children)

Why? Because fuck physics, that's why!

[–] [email protected] 52 points 10 months ago (3 children)
[–] [email protected] 13 points 10 months ago

It's a high tide train ride!

[–] [email protected] 5 points 10 months ago

Ride the tides then

[–] [email protected] 5 points 10 months ago

Or to the sun

[–] [email protected] 8 points 10 months ago (4 children)

This would be possible if there was a material unaffected by gravity, right?

[–] [email protected] 9 points 10 months ago (2 children)

I think in that case, the earth would just depart the location of the train, leaving it drifting in space.

[–] [email protected] 2 points 10 months ago

I was assuming the rails are strong enough to keep the train on the Earth, but I guess infinite friction from the movement and rotation of the Earth probably isn't survivable by any railway material. Hypothetically, if you had a material unaffected by gravity (train), and a material that is absolutely invincible (the rails, and they are anchored to the center of the Earth), now does it work?

[–] [email protected] 1 points 10 months ago

It's impossible to even reason about what something entirely unaffected by gravity might or might not do because everything, including gravity, is relative. Something not affected by Earth's gravity would probably get carried away by the wind, but something not affected by the Sun's gravity would float away from the sun (relative to the Earth) and appear to have some sort of mysterious acceleration from our perspective. If the object isn't affected by the Milky Way's gravity, even more shenanigans.

[–] [email protected] 7 points 10 months ago* (last edited 10 months ago)

No, the problem is not gravity, is that the train attached to earth has velocity dictated by the Earth movements, and keeps it because of inertia. In your theoretical experiment, the train would be launched on space at constant velocity.

[–] [email protected] 4 points 10 months ago

The problem isn't gravity, it's friction. The train would functionally be in orbit. The reason why things can't be in orbit at ground level is not because of gravity but because of friction (incl. air resistance).

If you eliminated friction (vacuum tube, frictionless surface, etc.) you could indeed have the train moving without any additional energy after getting it up to speed (and if you get it up to orbital speeds, the frictionless surface isn't even necessary). However, this isn't really practical (obviously).

If there is a nugget of a good idea in here, it's a train that never needs to accelerate or decelerate, just maintain a constant speed. Much of the energy of a train is lost in the stop-and-start.