Why is it important that the rocket that just landed take off again so soon?

While that's worded in customer benefit, I think the actual reason is supply-side: hovering is costly, and so landing the stages as cheaply as possible implies doing it quickly.

I've always had the impression that space missions aren't too frequent.

This may be because they are so expensive; if reusable rockets decrease the launch costs significantly enough, there may be many more launches.

I agree this is a possibility - a special subtype of the collapse. It seems unlikely to be a convergent enough high probability outcome that it could explain the fermi paradox.

One of the most likely candidates for filter (and variant of our future) is not mentioned here. That is, technological progress will simply end much sooner than usually expected, without any catastrophic events. There is not a filter, but a solid wall on the way from current technology to dyson sphere and starship building.

IMHO murder rates are incredibly gun-dependent, and I don't meant it as a gun-control argument, because politics is downstream from culture, so they are gun-culture dependent, not gun-law dependent. (Pro-gun culture with restrictive laws just means a huge black market, like drugs.)

Anecdotally, it is not easy to find black market guns in Eastern Europe. The supply of the ex-Yugo civil wars and drunk Soviet soldiers dried up, the international dealers and organized crime simply do not care about the minimal profits they could make on retail, they want it wholesale into conflict zones and whatnot. It is not a good black market retail business, unlike drugs, customers won't return every day or week. Retail black market could be based people owning 10-20 guns, private collectors, and occasionally sell one, there are a lot of people in the US who are like that but almost none in EE.

Things like not having a lot of game around to hunt play a role. But more likely, there are only two stable equilibria, everybody or nobody having guns, EE is tending towards nobody, the US has so many already that the only possible equilibrium state is everybody.

3) Can you enumerate some specific world-states that you think could lead to revival in a worse-than-death state?

Any sort of Hansonian future, where your mind has positive economic value.

If you had copies, how altruistic do you think you would be toward them?

A century ago there were scientists who said the same. Just because somebody is working on a problem doesn't mean it will be solved.

You find what is going to be on exam, you memorize it, you pass the exam, you forget it.

Why?

Because you don't care for knowledge, you just want a diploma.

Why?

Because companies don't care for knowledge that university gives (and don't really need it), they just want to see your diploma. If you don't have it, good luck finding a decent job.

Why?

Because one who finished the university at least isn't completely dumb and lazy. If you have such a method to filter job applicants, why not use it?

That is how it worked for me. Is it different in countries where higher education is not state-funded?

I'm not sure your counter-example is that accurate either. This is a report for only recent time and so the historical accuracy is not guaranteed but from 2012 to 2014, individual violence outweighed group violence by about 9 times. http://www.copenhagenconsensus.com/sites/default/files/conflict_assessment_-_hoeffler_and_fearon_0.pdf. I think it is safe to assume that historically it's at least similar.

When we look at the total historical view of violence we can not limit ourselves to just "war" or "group violence", and this data was included in Pinker's presentation. Therefore, kings, presidents, and chiefs, (if we consider them the sole source of the conflict, which we shouldn't) only contribute approximately 1/9th of the total global violence.

Sure there's a correlation that increased substances increase violence, but that in no way suggests that historical increased violence is due to increased substances. I don't think we have any kind of data that shows that these substances have been steadily decreasing over the past 10,000 years the same way that violence has been decreasing over the last 10,000 years.

Actually, I don't find these conjectures desperate or crazy at all, because it's what I'd do. Moving off this biological substrate onto something more reliable, hardy, efficient, and copyable seems like a no-brainer level "Good Idea". If there's any advanced intelligent life out there at all, one of its highest priorities is going to be finding more durable substrate to live in than sloppy, unoptimized and non-designed biochemistry.