I once traveled from Vladivostok to Moscow by train

printf("%s", name);@piefed.blahaj.zone · 4 days

And the linked post reminded me of a question that arose while riding the train. At the time, I tried to communicate my question to some nice Tajik people (is that the right term for people from Tajikistan?) by literally drawing shapes in the dust on the Siberian prairie, since we didn’t have a common language.

Traveling from Vladivostok to Moscow takes you in the same direction as the sun from our perspective. Does that mean that there is a theoretical speed at which the train could’ve moved and at which the perceived time of day doesn’t pass*? If so, what constants and variables do I need to learn about in order to make the calculations? Earth’s rotation? The trains speed?

*while time of course passes on it’s own, in the sense that I am still approach my impending death in some decades.

Rentlar@lemmy.ca · 3 days

Well, the closer you are to the North Pole, the easier time you will have crossing time zones, distance-wise.

Since I’m doing the math on my phone, I’m using an approximation of the Earth being a sphere with a radius of 6371km, and your train track is directly west, all at the same latitude, and equal longitude based timezones every 15°.

The circle around our Earth at that latitude has a circumference of 2 × pi × 6371 × cos(theta), kilometres, where theta is the latitude (imagine a triangle between the starting location, the centre of our model Earth and a point partway along a line that connects the equator and the centre). Divide that by 24, and that is the distance you need to travel in my model scenario to go back an hour, and thus the speed in km/h the westbound train needs to go to repeat the same hour again consistently.

Examples:

Going directly west from Vladivostok: 1667.92 × cos (43.12°) = 1217 km/h
Going to St. Petersburg: 1667.92 × cos(59.94°) = 835 km/h
Going from the tip of the mainland of the Russian Far East: 1667.92 × cos(66.06°) = 677km/h
To Murmansk: 1667.92 × cos(68.98) = 598 km/h
From Saskylaky, a rural settlement: 1667.92 × cos(71.96°) = 516 km/h
From the uninhabited top of the Russian mainland through a railway on the ocean: 1667.92 × cos(77.74°) = 354 km/h
From Rudolf Island, northernmost island in Russia: 1667.92 × cos(81.76°) = 239 km/h

HobbitFoot @thelemmy.club · 4 days

XKCD answered this but with driving.

https://youtu.be/U8F7UNK9jco

I expect the answer not to change too much by switching to a train.

AllNewTypeFace@leminal.space · 4 days

It would have to be faster than an airliner, as a flight westward (from, say, Tokyo to London) just succeeds in dragging the day out.

palordrolap@fedia.io · 3 days

The Sun’s apparent motion is 15° of longitude per hour. There are 94.3° of longitude between Vladivostok and Moscow, so you’d have to travel the distance in no less than 6 hours 17 minutes to keep up with the Sun. Assuming straight line flight not too far above the ground, that’s about 6400km (4000mi), so you’d need to be travelling around 1020km/h (about 640mph). Not quite supersonic, but you’re going to burn a lot of fuel.

The rail line that covers the distance is by no means a straight line though, so some sections with a large north or south component would need to be covered at a much, much higher rate of speed if you wanted the train to do it… and in fact the first stretch out of Vladivostok heads north-east so that part would be literally impossible to follow the Sun along unless you’re a time traveller.

I once traveled from Vladivostok to Moscow by train

If you walk forward inside a Shinkansen car while the train is moving at top speed, does your personal momentum actually compress the distance between Tokyo and Nagoya, or are you just changing the rate at which the track grid passes beneath your shoes?