this post was submitted on 05 Oct 2023
442 points (98.7% liked)

> Greentext

7512 readers
7 users here now

founded 2 years ago
MODERATORS
 
all 29 comments
sorted by: hot top controversial new old
[–] [email protected] 105 points 1 year ago* (last edited 1 year 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 1 year 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 1 year ago

(シ_ _)シ

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

You need energy to decelerate, though.

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

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

[–] [email protected] 13 points 1 year ago

Fridge magnets are the secret of infinite energy

[–] [email protected] 10 points 1 year 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 1 year 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] 3 points 1 year 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] 68 points 1 year 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 1 year 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 1 year ago (1 children)

Why? Because fuck physics, that's why!

[–] [email protected] 52 points 1 year ago (3 children)
[–] [email protected] 13 points 1 year ago

It's a high tide train ride!

[–] [email protected] 5 points 1 year ago

Or to the sun

[–] [email protected] 5 points 1 year ago

Ride the tides then

[–] [email protected] 8 points 1 year ago (4 children)

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

[–] [email protected] 9 points 1 year 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 1 year 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] 7 points 1 year ago* (last edited 1 year 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 1 year 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.