4 ms·

Simple solution - relativity holds up. Our light cone is much smaller than the galaxy. The universe could be teaming with intelligent life but not so full that

by jtolmar 10y ago

Simple solution - relativity holds up. Our light cone is much smaller than the galaxy. The universe could be teaming with intelligent life but not so full that you'd expect any to overlap the period where we're both using radio waves to communicate.

btilly 10y ago
The Milky Way is about 100k light years across. If colonization proceeded at 1% of the speed of light, it would take 10 million years to colonize the galaxy. That is roughly 0.2% of the time that the Earth has existed. And a bit under 2% of the time since the Cambrian that we've had complex life forms. Speed of light is a barrier for intergalactic colonization. It is not a barrier for an advanced civilization trying to colonize a galaxy. Even a relatively large galaxy such as our own.
- sampo 10y ago
  > Speed of light is a barrier for intergalactic colonization. The distance to Andromeda is about 20x times the diameter of Milky Way. But of course this is massively longer that hopping from a solar system to the next.
  - btilly 10y ago
    Right. There are no intermediate stopping points between the two. And Andromeda is in our local cluster and so close on the scale of the universe. Point of interest, we'll meet Andromeda in about 3 billion years or so. Point of additional interest. Due to the expansion of the universe, it is impossible even in theory to travel to most of the galaxies that we can see. Point of amazement. Our telescopes can pick out more galaxies in the universe than individual stars!
TheOtherHobbes 10y ago
Once you get to civs that last >10^6 years, the galaxy becomes a trivial size. The galaxy - and the speed of light limit - are also trivial distractions to any low-energy civs that evolved to run at a much slower metabolic rate, or adapted themselves to same. With Fermi, the smart money is on the galaxy being full of life - but it's either avoiding Earth completely, or it's here already and doesn't want to be seen. Besides - the goals and technology of >10^6 civs are literally unimaginable from a human perspective. We assume that exploration and travel are major interests. They may not be. There may be other pastimes we're completely unfamiliar with - ones which make getting into metal spaceships and banging atoms together to make them move through spacetime in a linear way seem about as interesting as sleeping in tree branches are to us.
- adrianratnapala 10y ago
  The thing is that all told, humans pick more fruit than other primates, and have more visible effects on forests than other primates. It's not unreasonable to think something similar applies to space-capable supercivilisations.

by jtolmar 10y ago

btilly 10y ago

The Milky Way is about 100k light years across. If colonization proceeded at 1% of the speed of light, it would take 10 million years to colonize the galaxy. That is roughly 0.2% of the time that the Earth has existed. And a bit under 2% of the time since the Cambrian that we've had complex life forms. Speed of light is a barrier for intergalactic colonization. It is not a barrier for an advanced civilization trying to colonize a galaxy. Even a relatively large galaxy such as our own.

sampo 10y ago
> Speed of light is a barrier for intergalactic colonization. The distance to Andromeda is about 20x times the diameter of Milky Way. But of course this is massively longer that hopping from a solar system to the next.
- btilly 10y ago
  Right. There are no intermediate stopping points between the two. And Andromeda is in our local cluster and so close on the scale of the universe. Point of interest, we'll meet Andromeda in about 3 billion years or so. Point of additional interest. Due to the expansion of the universe, it is impossible even in theory to travel to most of the galaxies that we can see. Point of amazement. Our telescopes can pick out more galaxies in the universe than individual stars!

TheOtherHobbes 10y ago

Once you get to civs that last >10^6 years, the galaxy becomes a trivial size. The galaxy - and the speed of light limit - are also trivial distractions to any low-energy civs that evolved to run at a much slower metabolic rate, or adapted themselves to same. With Fermi, the smart money is on the galaxy being full of life - but it's either avoiding Earth completely, or it's here already and doesn't want to be seen. Besides - the goals and technology of >10^6 civs are literally unimaginable from a human perspective. We assume that exploration and travel are major interests. They may not be. There may be other pastimes we're completely unfamiliar with - ones which make getting into metal spaceships and banging atoms together to make them move through spacetime in a linear way seem about as interesting as sleeping in tree branches are to us.

adrianratnapala 10y ago
The thing is that all told, humans pick more fruit than other primates, and have more visible effects on forests than other primates. It's not unreasonable to think something similar applies to space-capable supercivilisations.