[bena]

Yes, I know the paradox. It's simple. It's too simple.

It has huge assumptions. Namely the assumption that the current problems to colonization can be solved in a cost-effective manner.

The longest continuous length of time spent in what limited space flight we have is just under 440 days. Not to mention, all of it was spent in low Earth orbit. Once we go beyond that, we lose all protection from the Earth's magnetosphere.

Then there's also the loss of bone density due to lack of gravity. 1% per month is nothing to sneeze at.

We are not built for space travel. We are built to inhabit this planet. We have evolved to the conditions here.

And before you say that the generation ships will just fake gravity and have appropriate shielding. Where do you get that assumption? We can't fake gravity. We have a space station where they take 10 times the radiation as here on Earth because we can't even realistically shield that.

And then we get to "autonomous probes", the great handwave of people who think they can cleverly sidestep the "humans aren't built for space" issue.

Who builds them? For what purpose? What's our expected return? How can you justify the investment in time and resources to shoot into space, with absolutely no hope of even knowing there's a chance for a return on that investment until generations later, a probe that can at best return data.

And then there's the issue of it being an autonomous probe. Two words that hide a lot of other problems. A lot of other assumptions. One being that we'll have created an intelligence capable of running this thing.

In other words, the Fermi Paradox just assumes that all of these incredibly hard problems can and will be solved and that the solutions are logistically viable.

What if they're not?

[deeeeplearning]

You talk like this is all expected to be done by 21st century humans when in reality if there were civilizations out there capable of doing this colonization they would likely be millions of years our elders and its incredibly foolish to try to guess their intentions or the capabilities of their technology. Your view is painfully anthropocentric.

Just to add, there are plenty of valid criticisms or plausible solutions to the Fermi paradox but I think you've failed to identify a single one.

[bena]

You talk like this is all a forgone conclusion. Technology is not magic. Time is not a salve that solves all issues.

You say that my view is "painfully anthropocentric", but how?

It seems your only response is "but aliens". That is not good enough.

You want to say that it is foolish of me to try and guess their intentions and capabilities, but that's what the paradox does as well. It assumes their intentions are to colonize and their capabilities allow it. With no proof. The only life we have to base anything off of is right here.

And if you think I haven't identified a single valid criticism of the Fermi paradox, then I'm just going to assume you aren't aware of the criticisms.

I've basically touched on this one https://en.wikipedia.org/wiki/Fermi_paradox#Economic_explana...

So no, I'm not saying that just because it can't be done now, it can't be done ever. I'm saying the Fermi Paradox is basically saying "Once you solve these incredibly hard problems, this becomes easy."

I think the Fermi Paradox is phrased wrong. It should state that if it were possible to colonize the galaxy, it would have been done by now.

[SturgeonsLaw]

> You say that my view is "painfully anthropocentric", but how?

I'm not OP but the idea of thinking in terms of "return on investment" strikes me as very 20th century humanity.

Who's to say a future society wouldn't consider finding another civilisation to be a massive ROI? Or that a post-scarcity society living under Fully Automated Luxury Gay Space Communism would even care about a return, instead of just doing things because they care to do them?

[ben_w]

> We can't fake gravity.

Yes we can, it’s a standard part of fairground rides.

(I’ll agree that the unknowns of space colonisation, and of the automation we’d need to be able to afford the infrastructure to even launch a serious effort, may prevent such colony efforts from happening)

[bena]

Centrifugal force does mimic gravity but it's not really something we can do at scale or even in space. When we're talking about a generation ship, we're talking about something a little larger than the Gravitron.

Not to mention, they work within Earth's gravity. Take a tube and spin it around you in space, it does nothing to you because there's no other forces working on you. Nothing putting you in the frame of the spinning tube.

Once you lose the Earth, it becomes a lot trickier to tie you to a frame of reference. Nothing we can make has the mass necessary.

The best we could likely do is accelerate a ship at 1G. But that has problems, because about halfway through your journey, you have to start decelerating. And there's also the issue of turning.

[ben_w]

> Take a tube and spin it around you in space, it does nothing to you because there's no other forces working on you.

Yes, it does — if you are in contact with the structure, the force you feel is the outside acting against your inertia to keep you in uniform circular motion. There is a layer of air in contact with the structure at any moment, so it ends up co-rotating, so anywhere inside except the axis of rotation itself will feel a force proportional to the distance from the axis.

> When we're talking about a generation ship, we're talking about something a little larger than the Gravitron.

Naturally. You can still spin them along and axis: https://en.m.wikipedia.org/wiki/O%27Neill_cylinder

We are a long way from been able to build such structures, and I have doubts about the suitability of human political psychology given the travel times involved and how long countries last for on average, but the physics of spin-gravity is fine, even though there may be noticeable Coriolis effects depending on scale.