Mega Engineering

Welcome to Mega Engineering! For those who don't know, mega engineering is engineering on the mega scale and larger - more than 1,000 kilometres. When humanity advances, it may try some things on this list.

The entries will take the following format:

• Megaproject Name

• Description

• Energy and Mass Requirements

• Time Requirement

• Civilisation Class Requirement

The resources available to civilisations come from this table, from Robert A. Freitas' Xenology:

Civilization	Class	Nominal Lifetime	Nominal Power	Total Available Energy	Total Available Mass
Planetary	Type I	5 Ga	10 PW	1.57 UJ	5.97 Nog
Stellar	Type II	5 Ga	100 YW	15.7 QJ	1.99 Ug
Galactic	Type III	2.5 Ta	1 DuW	78.9 OcJ	2.49 Qug
Universal	Type IV	100 Ta	10 QuW	3.16 DvJ	147 Ocg

The extended SI Prefixes are from Sbiis Saibian's excellent Extended Munafo Prefix System. The civilisation class requirements don't show when it is first possible, but when it can become routine.

Let's begin.

Moving A Planet at 1%c
Description: Moving an entire planet would be useful, if you wanted to transport it to another star where the industry is more developed, or where the raw materials are needed. This assumes that the planet travels around 30 light years (size of the Local Interstellar Cloud) at 1%c.
Energy Requirement: 26.8 DuJ
Mass Requirement: 5.97 Nog
Time Requirement: 300 a
Civilisation Class Requirement: Late Type II (Interstellar Civilisation)

Moving a Star at 1%c

Description: Eventually, it may be economical to move stars closer to other stars, to have them be in more convenient locations. My calculations assume that the star is moved at 1%c, for a distance of 500 light years (the distance from Earth to Beta Canis Majoris).

Energy Requirement: 8.94 QJ

Mass Requirement: 1.99 Ug

Time Requirement: 5 ka

Civilisation Class Requirement: Early Type III (Galactic Civilisation)

Move an Entire Galaxy at 1%c

Description: What if one day, a civilisation decides it will expend resources to move its galaxy to another galaxy (to eat it?) at 1% of the speed of light. What civilisation class would it need? The EMT requirements are easy to work out. This assumes the other galaxy is 2.5 million light years away, a.k.a. the distance from Earth to M31.

Energy Requirement: 11.2 OcJ

Mass Requirement: 2.49 Qug

Time Requirement: 25 Ma

Civilisation Class Requirement: IMPOSSIBLE (without significant investment of resources)