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Comment by londons_explore | Hacker News Reader

Lego city isn't on earth... So requiring earth amounts of delta-v doesn't make sense...

That's a good point! I'm assuming that it's on Earth as [this set](https://www.amazon.com/dp/B003A2JCOA?tag=duckduckgo-fpas-20&...) shows cities on Earth as destinations for the train.

$243... I finally understand why my parents never bought me these kits lol

The train sets have some really dedicated collectors. This is an old set I think so probably not representative of a regular LEGO set. But yeah they’re not cheap.

This is an old (no longer officially sold) set and Amazon is know to have completely over the top prices for them.

The original price is hard to find but seen to have been between 80€ and 130€ (probably the later).

Current prices for "new/sealed" (quality) sets seem to be around 135€.

Before corona it was around 100€:

https://www.bricklink.com/v2/catalog/catalogitem.page?S=6005...

Sadly LEGO doesn't produce many good train sets in recent years. They had quite a variety of not cheaper but also not very expensive sets when I was young.

Still I won't disagree that Lego had many overpriced not so good sets.

The routes include Moscow and Dublin. What city on Earth has train routes that can reach both of those cities? Another point in favor of Lego City not being on the Earth we know.

Instead of scaling the Legos up, assume that they're life size beings on a Lego sized pseudo-Earth. It's been years since I've done any physics so, I hope I'm not badly off, but I think the gravity will be around 1/900th that of Earth (if we assume radius of Lego world at 1/30 earth, mass of Lego world proportional to the cube). If we ignore the fact that there probably won't be an atmosphere on Lego world, I'm sure there are are various other applications of the square-cube law, etc. that will work in their favor as well.

I believe they'll make it.

It'll actually still be 1/30th of the Earth, since from Newton's law of universal gravitation:

F = G * (m_1 * m_2) / r^2

m_2 * a = G * (m_1 * m_2) / r^2

a = G * m_1 / r^2

If we make m_1 1/30th of its original size and to the same to r:

a = G * (m_1 / 30^3) / (r / 30)^2

a = G * (m_1) / r / 30

As escape velocity v_e is where GPE + KE = 0:

v_e = sqrt(2 * g * r) from the surface of the planet

If g is now 1/30th of it's original amount as shown above, the escape velocity would be sqrt(30) = 5.477 times less, or about 2042 m/s. So yup, they would make it if it's at 1/30th the size of the Earth, with thrust to spare for air resistance.

I'm sure there's a city with train services connecting Dublin, CA (served by the BART) to Moscow, ID. The question might just be when...

There is an underwater-tunnel between france and england with trains running. And there is the irish sea bridge-project with the goal to connect great britain and ireland by train and cars. Making such a route possible in some yet unbuild future reality.

My question exactly. I think the right approach is to do the delta v calculation, and then use it to estimate the size of Planet Lego, by assuming the rocket can achieve orbit.

Yeah, that's reasonable to consider. If we compare to the toy planets in Kerbal, for example, Kerbin is about 1/10 the size of Earth. Low orbit velocity is about 2.3km/s and escape velocity is 3.4km/s. A rocket with 4.25 of delta-v would probably be about right, after factoring in losses to gravity/drag while launching.

If it's not on Earth, why did the Lego figures bother building a Saturn V [0]?

[0] https://www.amazon.com/LEGO-Ideas-Apollo-Saturn-21309/dp/B01...

The saturn 5 model is not lego-city/minifig scale.

This brings up an interesting point in LEGO canon. If we assume that all LEGO franchises take place in the same universe, we'd have to assume that LEGO Angry Birds[0] took place somewhere in the canon timeline of the LEGO universe. Even more problematic would be trying to put BIONICLE[1] somewhere in the timeline, while somehow also being able to fit in LEGO Star Wars[2]. Perhaps the toughest one to piece together would be LEGO Mars Mission[3] and LEGO Life on Mars[4]. While Life on Mars depicts a peaceful relationship between humans and martians, Mars Mission centers on a conflict around powerful energy crystals, which just doesn't match up (especially considering the Martians look completely different in these series).

[0] https://brickipedia.fandom.com/wiki/The_Angry_Birds_Movie

[1] https://brickipedia.fandom.com/wiki/BIONICLE

[2] https://brickipedia.fandom.com/wiki/Star_Wars

[3] https://brickipedia.fandom.com/wiki/Mars_Mission

[4] https://brickipedia.fandom.com/wiki/Life_on_Mars

From the Mars Mission page it seems the non-peaceful aliens aren't Martian natives: > The Aliens have originated from an unknown place in the cosmos, and are also searching for the crystals. In actuality, they are not from Mars And the wiki suggests it's a soft sequel to the Life On Mars setting, making their place in LEGO canon easier to fit together.

In this high altitude video sequence of 'Lego Earth' I see no evidence of familiar coastal outlines. Case closed? https://www.youtube.com/watch?v=CvlXACoVVIo

If there's one thing we learn from E. R. Burroughs' careful multi-volume monograph on Mars, it's that the planet has room for numerous species, each involved in quite different political struggles.

The available amount of delta-v would actually be spot on for an orbital launcher on Kerbin (in Kerbal Space Program).

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