Greetings OAs

[Tony6Whiskeys]

Greetings OAs. By way of an intro...... I'm living in the mountains of British Columbia, Canada. Been an Hard SF addict since childhood and even tried writing a bit. I was a geologist - spent 30 years working across Europe, North America and SE Asia.  Gardener, traveler, humanist, lover of maps and other great mysteries as well as good red wine.  Decidedly amateur interest in writing, prehistory, paleoanthropology and deep time.

Oh yeah and I was trying to find out how I might calculate how fast a spacefaring civilization could spread through the galaxy , well the Orion Arm actually, (without any obviously impossible FTL drive) when I stumbled upon you guys! Anyone out there that can point me in the right direction to get an answer to that? 

Cheers

[Rynn]

Welcome to the group those are some great interests, especially the wine lol.

How fast a space faring civilisation might colonise the galaxy is a question with no clear answer, it depends on a lot of assumptions such as reasonable interstellar velocities, time between colony ship launches, cultural factors etc. I've seen estimations anywhere between 0.2 to 100 million years! For an in-depth look at the later I'd recommend looking into the 2019 Global Trajectory Optimisation Competition. It's an annual competition affiliated with the European Space Agency where groups around the world are tasked with finding optimum, efficient interplanetary transfer methods. In that year for their 10th anniversary they made it a competition to simulate colonising the galaxy. The rules were that Sol could launch two kinds of spacecraft: a fast runner that can't change course and colonises one system, and a mothership that travels slowly but has delta-V to adjust course and drops off colony pods to nearby systems as it passes. The emphasis on this competition is efficiency, and the ground rules were quite conservative by sci fi standards;

• Sol can only launch 5 ships: 3 motherships and 2 fast ships.
  
• Motherships carry 10 settlement pods that they can drop by nearby systems as they pass by
  
• Fast ships travel to one system only and colonise it.
  
• After 2 million years of being colonised a system can launch up to 3 settlement ships, which travel slow and colonise one system.
  
• Motherships and settlement ships travel at ~0.05% light speed, fast ships at 0.5% light speed.
  

The teams focused on the optimum way to colonise the galaxy with these constraints. Most went for sending the fast ships on trips far across the galaxy so that a wave of colonisation could happen backwards. The winning team had the galaxy colonised fully after 90 million years. This is part of the simulation of the team that placed third in the competition (yellow dot is sol, green lines are the path of fast ships, purple lines are the motherships, red lines are the settlement ships);



Obviously these are very conservative figures. There are speculative but realistic designs for interstellar drives that can manage 1-10% of light speed, and there's no physical reason why a colony would be restricted to only a few launches every million years. You could likely cut an order of magnitude or more from the winning team's speed by swapping these figures, colonising the galaxy in less than a million years, but the purpose of this competition was efficiency so that would kind of defeat the point

What this shows though is that on "merely" geological time frames a space faring species could colonise the whole galaxy with minimal effort.

[Vitto]

Hello, welcome!

Not sure if there is a page on this matter in particular, I guess this one is the closest on the argument:

Propulsion Performance Statistics

Without descending into the (low!) sci-fi tech of Orion's Arm you can have an antimatter drive theorically reaching a peak speed of 0.7c, so, calculating refuelling and repairs you can probably go from an edge of the galaxy to the other side in 200k years, I guess. If hitting a space debris don't make you vapourize mid course
Realistically you have probably to double or triple that number but I still think a civilization can engulf a whole galaxy in less than a million year.
As Rynn said these are "mere" geological times and probably one of the strongest points of the Fermi Paradox.

[Drashner1]

Hi There - Welcome to OA!

Please feel free to ask any questions that come to mind, to join in on any ongoing conversations, or to start new ones if you are so inclined.

To add to Rynn's excellent post:

Calculations/estimates for rates of interstellar colonization seem to usually be based on the assumed speed of the colony ships and how long each colony generally takes to build up to the point where it can launch its own colonies.

This topic used to be something that was discussed a lot in futurist circles and generated a lot of papers and books and such. I have some of them in my files and will see what I can dig up this week in terms of either info or recommendations.

A potential challenge in this area is that most of the references I remember (which are generally written for the layperson) don't necessarily go into the math underlying the estimates they reach. But my memory is fuzzy and it may be a case of checking the source material for the reference list and then providing relevant info from there.

I'll get back to you.

On a more OA related note - we actually have a couple of ongoing threads atm (in General Setting Discussion) that relate to this - one on interstellar probes over the course of OA history and the other on interstellar colonization. Basically, what did these things look like early in the OA timeline and then how did they change over time as technology and know-how improved?

Finally and re the Propulsion Performance page - that page is rather old and probably needs some updating, both on general principles and due to changes in our 'take' on how the setting works that have developed over time. This is something of a constant underlying thing with OA - we are constantly adding to or updating the setting based on the discussions here (and to a lesser degree on the Discord). Overall, we are also aiming to get things better organized, but given that OA runs entirely on volunteer labor, it's sometimes a slow process. Please bear with us.

Hope this helps and once again - Welcome to OA!

Todd

[Tony6Whiskeys]

Hello, welcome!

Not sure if there is a page on this matter in particular, I guess this one is the closest on the argument:

Propulsion Performance Statistics

Without descending into the (low!) sci-fi tech of Orion's Arm you can have an antimatter drive theorically reaching a peak speed of 0.7c, so, calculating refuelling and repairs you can probably go from an edge of the galaxy to the other side in 200k years, I guess. If hitting a space debris don't make you vapourize mid course
Realistically you have probably to double or triple that number but I still think a civilization can engulf a whole galaxy in less than a million year.
As Rynn said these are "mere" geological times and probably one of the strongest points of the Fermi Paradox.

Hell 1 million years is normally a tight error bar in geological time 

[Tony6Whiskeys]

Welcome to the group those are some great interests, especially the wine lol.

How fast a space faring civilisation might colonise the galaxy is a question with no clear answer, it depends on a lot of assumptions such as reasonable interstellar velocities, time between colony ship launches, cultural factors etc. I've seen estimations anywhere between 0.2 to 100 million years! For an in-depth look at the later I'd recommend looking into the 2019 Global Trajectory Optimisation Competition. It's an annual competition affiliated with the European Space Agency where groups around the world are tasked with finding optimum, efficient interplanetary transfer methods. In that year for their 10th anniversary they made it a competition to simulate colonising the galaxy. The rules were that Sol could launch two kinds of spacecraft: a fast runner that can't change course and colonises one system, and a mothership that travels slowly but has delta-V to adjust course and drops off colony pods to nearby systems as it passes. The emphasis on this competition is efficiency, and the ground rules were quite conservative by sci fi standards;

• Sol can only launch 5 ships: 3 motherships and 2 fast ships.
  
• Motherships carry 10 settlement pods that they can drop by nearby systems as they pass by
  
• Fast ships travel to one system only and colonise it.
  
• After 2 million years of being colonised a system can launch up to 3 settlement ships, which travel slow and colonise one system.
  
• Motherships and settlement ships travel at ~0.05% light speed, fast ships at 0.5% light speed.
  

The teams focused on the optimum way to colonise the galaxy with these constraints. Most went for sending the fast ships on trips far across the galaxy so that a wave of colonisation could happen backwards. The winning team had the galaxy colonised fully after 90 million years. This is part of the simulation of the team that placed third in the competition (yellow dot is sol, green lines are the path of fast ships, purple lines are the motherships, red lines are the settlement ships);



Obviously these are very conservative figures. There are speculative but realistic designs for interstellar drives that can manage 1-10% of light speed, and there's no physical reason why a colony would be restricted to only a few launches every million years. You could likely cut an order of magnitude or more from the winning team's speed by swapping these figures, colonising the galaxy in less than a million years, but the purpose of this competition was efficiency so that would kind of defeat the point

What this shows though is that on "merely" geological time frames a space faring species could colonise the whole galaxy with minimal effort.

Appreciate it.... so much to dig into here it's a bit overwhelming so thanks for the pointers!

[MacGregor]

Welcome to OA!

[Everything4404]

Welcome to OA!

[Worldtree]

welcome!

[Drashner1]

So - as promised - I'm getting back to you. A little later than planned, but I think I've found some things you'll like. Specifically:

Checking my library, I cracked open my old copy of Interstellar Migration and the Human Experience.

Chapter 19 is a paper by William I. Newman and Carl Sagan titled Non-linear Diffusion and Population Dynamics, of which a partial copy can be found HERE.

You may need to scroll down to find the pages that are included. You can also do a google on the chapter title and it comes up at the top under 'scholarly articles' for the title.

The chapter on Google Books in incomplete, but I can type in the relevant sections and/or equations to fill in the gaps, if you'd like.

In a nutshell, they provide a number of equations that could potentially be used to calculate time before a given interstellar colony would launch new colonies itself which feeds into overall time to colonize the galaxy. Plus a good bit of analysis and info around this subject.

Possibly also relevant and more helpful is another paper I found by the same authors titled Galactic Civilizations: Population Dynamics and Interstellar Diffusion, which is very conveniently available in full as a PDF. I've only skimmed a little bit of it, but it seems to cover the same general subject and is by the same authors, so I'd say the odds aren't terrible that it might also cover the same info as the first reference, and possibly in even greater depth.

Worst case scenario it covers related information, perhaps.

Coming at this from a different direction - typing 'time to colonize the galaxy' into YouTube turns up a number of videos, some of which may contain useful information.

Getting on to bedtime here, but if I think of any other sources I have on hand that relate to this, I'll give them a look and post if anything relevant turns up.

Hope this helps,

Todd