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Comment Spielman is hardly ab outsider (Score 4, Informative) 81

Kalai and Spielman are both very talented and have done a lot of work in many different branches of mathematics. Moreover, in this particular context they proved an equivalent version of the conjecture that was much closer to their own sort of work. The problem in question has many different equivalent formulations such as that described here is essentially a statement about vector spaces that anyone with some basic linear algebra background could understand. This is a very common tactic in mathematics if one has a tough problem: try to find equivalent problems that are in other subfields of math where their might be techniques to handle them.

Comment Re:There's an old curse (Score 1) 527

Not really. Africa and South America both have very little in the way of high tech manufacturing and even if not many directly died there there would be substantial economic collapses. One could easily see the tech level going back much further to early 1800s or even earlier. The timespan that's a direct concern is getting technology from about 1850 levels to 1970s or so which is where we had all the bootstrapping of using fossil fuels and the like. There will be some advantages the second time around, such as the fact that many metals will have been minded and extracted and thus will be ready for reuse (e.g. a lot of aluminum and some titanium) so it isn't completely clear what would happen. The exact details might make a big difference.

Comment Re:There's an old curse (Score 1) 527

Sure, we could be deeply wrong about things. In this case though, the primary issue is whether we are correct about basic thermodynamics. It is possible that we're wrong, but it isn't that likely. And yes, of course it isn't definitive: we've barely started looking into these things. But it should be deeply concerning.

Comment Re:There's an old curse (Score 1) 527

Please read the article I linked to. One can detect a K3 civilization not just from the total power output but from the fact that the spectrum will look different. In particular, there will be a lot more infrared radiation from waste heat than there will be in a regular galaxy so the proportion of light at different wavelengths gives one good data. There are also other ways to detect aspects of K1 and K2 civilizations such as looking for megastructures.

Comment There's an old curse (Score 4, Interesting) 527

There's an old curse that seems relevant: "May you live in interesting times." Times are certainly interesting. At this point, it seems like some sort of full-scale war between NATO and Russia is more likely now than it has been any time since the 1980s (granted then it would have been NATO against the USSR but the basic point is the same). Worse, at least historically the military and diplomats spent much of their time making sure that things didn't spiral out of control. Without the Cold War feeling, people may feel less of a need to guard against such issues. Worse, Russian military doctrine currently describes a limited nuclear strike on conventional military targets as a de-escalation . While in official documents they reserve that terminology for using nuclear weapons to handle direct conventional military attacks on Russia itself, one finds very worrying the level of doublethink where one describes being the first to use nukes as de-escalating a situation.

During the Cold War, one popular explanation for the Fermi paradox, the apparent lack of highly advanced civilizations in the universe, was that species end up blowing themselves up. For most of my life, this belief looked almost quaint but it is not looking disturbingly likely. At this point, the evidence for some sort of serious barrier to civilizations emerging substantially is much stronger than it was a few decades ago. The apparent lack of K3 or K2.5 civilizations is at this point substantially robust with around 100,000 galaxies searched and almost no sign of any civilization using a substantial fraction of its galactic energy output With this return to Cold War norms, it looks like we need to not only take seriously that there's a Great Filter, but that the Filter might be nuclear war. That's especially the case because a nuclear war does not need to kill every member of the civilization to completely destroy any hope of a technologically advanced civilization. If not enough natural resources have been consumed by the civilization (e.g. the easily accessible coal and oil) then even if the species survives it may not have the ability to reboot itself to a high tech level since getting to a high tech level may actually require access to these resources (in which case one gets essentially one chance to get to be a high tech civilization).

Comment The real worry should be Kessler Syndrome (Score 4, Interesting) 98

There's a serious risk that in low-Earth orbit if one has enough debris it could cause a cascade of destruction where debris hits satellites breaking them up into more debris which hits more satellites and so on. Such a cascade is called Kessler Syndrome . If this happens it could render many orbits unusable for years. In that context, deliberately destroying satellites should maybe be considered a war crime since the potential for collateral damage impacting all of humanity is so severe.

Comment Re:Typical Liberal Thinking (Score 2) 109

In the case of natural gas power plants. . . For now, they're much better than coal. For the future, solar power and nuclear fusion will eventually kill them off.

If we ever get fusion to work effectively it might end up killing everything off. But in the moderate term, solar isn't going to be the only one. A combination of nuclear fission, solar, wind, geothermal and hydroelectric is much more viable and solves many of the problems. Fusion is a very long way off and it is likely that we'll stop having susbstantial fossil fuel use well before fusion is a common power source.

Comment Re:This is great (Score 1) 73

Agree with your last two paragraphs (and the point about how right now storage is mainly going to be used for fossil plants is certainly important) . I think however you may be underestimating how often wind power gets wasted in some areas, although it may be an issue of where exactly one is looking. For example, in the US there's a lot of wind power in Texas but it often gets wasted. And if one is a smaller, isolated grid, such as many islands, this problem is even more severe. But you are right that "vast majority" was probably too strong especially in the context of Western and Central Europe which has done a good job integrating their grids.

Comment Re:This is great (Score 1) 73

It reduces it but not as much as a naive calculation suggests since a) conventional plants have startup times where you burn a lot more, b) due to slow startup time you need some fossil fuel running all the time if you don't have a lot of storage so if there's a sudden lull in wind or solar you can still keep the grid steady. There's an excellent book that covers all these issues for laypeople, "Before the Lights Go Out" about the history and future of the electric grids by Maggie Koerth-Baker. Her book focuses on the American grid (well grids really since there are three main grids, East, West and Texas) but most of the book applies to pretty much any large-scale grid.

Use the Force, Luke.