The philosophy of galactic civilizations.

 

Above: Artists' view of Stanford Torus. 

Even if faster-than-speed light travel is possible. It doesn't make the galactic-scale civilizations possible. The interstellar civilizations would be far different than humans who live on Earth. Every single planet in the universe holds its unique biosphere. That means that other planets would be poisonous for a civilization. 

That wants to travel to another planet or solar system. Communication between planets in different solar systems would be difficult. The thing is that the most dangerous biospheres are similar biospheres that existed on a planet where that hypothetical civilization left. 

That makes deadly viruses and microbes possible. So even if we think that civilization wants to travel to another solar system and stay there, they need an artificial world. A giant space station like Stanford Torus might be a better possibility than landing on planets. The deadly microbes can turn humans into liquid in the second. 

The species that land on the unknown planet whose biosphere is similar to their own would get viruses and bacteria. And they have no immune defense against those species. Those microbes are a worse threat than any xenomorph. But if we think that the species would modify their body by using biotechnology in all models those creatures need the species from their target planet. 

Those organisms involve genetic material that makes them suitable and adapted to that environment. That means that the species turns colonists into another species. There are visions that the space industry like asteroid mining forms humans that ever visit on Earth. Those space humans would be physically weak because they spend their entire lives in a zero-gravity environment. 

That life environment modifies their bodies. And maybe. They start to use genetic engineering to make them more suitable for that environment. Futurologists predict that in the future there will be people in space who never see Earth. Or maybe those hypothetical creatures ever visit on planets. Maybe someday those space humans turn into their own species. And maybe in the future, those creatures would be species that travel to another solar system. 

But if we think about galactic-scale civilizations those things would anyway be far different than our civilization. The ultimate distance and enormous scale make those civilizations harder to control than we even imagine. But could there be galactic-scale civilizations? 

When we think about the Kardashev scale. That model means the ability to use energy. The ability to benefit from things like the energy of supermassive black holes doesn't mean that civilization can live on multiple planets. 

If our hypothetical civilization is near some supermassive black hole they can collect energy from that black hole's relativistic jets. Or they can cover a small black hole by using a ball. That makes it possible to use the black hole's energy. But it doesn't mean that civilization can travel between stars. Or maybe those journeys are one-way trips where the cryostatic embryos travel to another solar system. 

https://bigthink.com/13-8/galactic-civilizations-may-be-impossible-heres-why/