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Empirically we seem to be converging on the idea that the expansion of the universe continues forever (see Wikipedia for a summary of the possibilities), but it's not totally slam-dunk yet. If there is a Big Crunch, then that puts a hard limit on the time available.

If - as we currently believe - that doesn't happen, then the universe will cool over time, until it gets too cold (=too short of negentropy) to sustain any given process. A superintelligence would obviously see this coming, and have plenty of time to prepare - we're talking hundreds of trillions of years before star formation ceases. It might be able to switch to lower-power processes to continue in attenuated form, but eventually it'll run out.

This is, of course, assuming our view of physics is basically right and there aren't any exotic possibilities like punching a hole through to a new, younger universe.

Yes, good point that I hadn't thought of, thanks. It's very easy to imagine far-future technology in one respect and forget about it entirely in another.

To rescue my scenario a little, there'll be an energy cost in transporting the iron together; the cheapest way is to move it very slowly. So maybe there'll be paperclips left for a period of time between the first pass of the harvesters and the matter ending up at the local black hole harvester.

That, and/or increased sweating, and/or larger temperature gain between inspired and expired air, or wearing fewer/thinner clothes. There's lots of ways to dump heat.

I would definitely expect someone with a faster metabolism to put out more total net heat, which is measurable with difficulty, and also consume oxygen faster (and produce carbon dioxide faster) which is measurable with some difficulty, but a lot less.

Therefore they must not vary all that much in terms of metabolism.

I don't think that follows, or at least not without a lot of other explanation, even if you grant that temperature doesn't vary in any significant way between people (which I'm not sure I do). The body has multiple mechanisms for maintaining temperature, of which metabolic rate is only one. It seems entirely plausible to me that people run their metabolisms at different rates and adjust their peripheral vasodilation and sweating rate to balance it all out near 37 C/98 F. Core temperature might vary between people by only a few degrees, but surface temperature varies much more widely.


Also, they were not just AIDS researchers but AIDS activists and campaigners. The conference they were going to was expecting 12-15,000 delegates (depending on the report); it's the most prominent international conference in the area but far from the only one. As you say, a terrible loss, particularly for those close to the dead. The wider HIV/AIDS community will be sobered, but it will not be sunk. If nothing else, they coped with far higher annual death rates before effective therapies became widespread in the developed world.

The story of this story does helpfully remind us that the other 'facts' about this situation - which we know from the same media sources - may be similarly mistaken.


Much of modern medicine involves covering up symptoms with drugs proven to do this, without understanding the underlying cause of the symptom.

What, really? There certainly is a lot of that approach around, but it's not what I think of when I think of modern medicine, as opposed to more traditional forms. Can you give examples?

Most of the ones I can think of are things that have fallen to the modern turn to evidence-based practice. The poster-child one in my head is the story of H. pylori and how a better understanding of the causes of gastritis and gastric ulcers has led to better treatments than the old symptom-relieving approaches. (And I'll tell you what, although Zantac/Ranitidine is only a symptomatic reliever, it was designed to do that job based on a thorough understanding of how that symptom comes about, and it's bloody good at it, as anyone who's had it for bad heartburn or reflux can attest.)

When I think of modern medicine, I think of things like Rituximab, which is a monoclonal antibody designed with a very sophisticated understanding of how the body's immune system works - it targets B cells specifically, and has revolutionised drug treatment for diseases like non-Hodgkin's lymphomas where you want to get rid of B cells. So much so that for some of those lymphomas, we don't have very robust 5 year survival data, because the improvement over traditional chemotherapy alone is so large that the old survival data is no use (we know people will live much longer than that), and Rituximab hasn't been widely used for long enough to get new data. In the last 25 years our understanding of cancer has gone from "it's mutations in the genes, probably these ones" to vast databases of which specific mutations at which specific locations on which specific genes are associated with which specific cancer symptoms, and how those are correlated with prognosis and treatment. And as a result cancer survival rates have improved markedly. We don't have "A Cure For Cancer", and we now know we never will, any more than we can have "A Cure For Infection", but we do have a good enough understanding of how it happens to get much better at reducing its impact.

Even modern medical disasters like Vioxx are hardly a result of a lack of understanding the underlying cause, but more us learning more about other complexities of human biology. Admittedly we don't yet fully understand how pain works, but we do know enough to know that targeting COX-2 exclusively (rather than COX-1 as well, which looks after your gut lining) would be safer for your gut. This is understanding down at the molecular level. It turns out in large scale studies that they are safer for your gut, but of course they're not very safe for your heart, so we've stopped using them. And actually doing the full-scale research on modern rationally-designed drugs like Vioxx suggests that similar old drugs (that we never bothered to test) have the same effect on hearts.

Interesting stuff, thanks; looking forward to the rest of the series.

As an aside, this makes the benefits of being able to rely on trust most of the time very apparent. Jack and Jill can coordinate very simply and quickly if they trust each other to honestly disclose their true value for the project. They don't even need to be able to trust 100%, just trust enough that on average they lose no more to dishonesty than the costs of more complex and sophisticated methods of bargaining. (Which require more calculating capacity than unaided humans have evolved.)

I find similar techniques help with my children.

It seems closely related to the technique where, to stop them doing something you don't want them to do, you encourage them to do something else that prevents them from doing the first thing. (There's a snappy name for this that I've forgotten.) So, for example, stopping them from bothering another child by getting them interested in an entirely different activity.

I really don't think we have to posit nanoassemblers for this particular scenario to work. Robot drones are needed, but I think they fall out as a consequence of currently existing robots and the all-singing all-dancing AI we've imagined in the first place. There are shedloads of robots around at the moment - the OP mentioned the existence of Internet-connected robot-controlled cars, but there are plenty of others, including most high tech manufacturer. Sure, those robots aren't autonomous, but they don't need to be if we've assumed an all-singing all-dancing AI in the first place. I think that might be enough to keep the power and comms on in a few select areas with a bit of careful planning.

Rebuilding/restarting enough infrastructure to be able to make new and better CPUs (and new and better robot extensions of the AI) would take an awfully long time, granted, but the AI is free of human threat at that point.

One thing I should mention where I wasn't able to get a very good match between my own observations and mainstream science.

The Sun and the Moon are very, very close in their apparent diameter in the sky. They are almost exactly the same size. You can measure them yourself and compare, although this is a bit fiddly; I certainly got well within my own measurement errors, although those errors were large. However, you can verify it very easily and directly at the time of solar eclipses. They are so near in size that the wobbliness of the Moon's orbit means that sometimes the Sun is just-smaller than the Moon (when you get a total eclipse) and sometimes it is just-bigger (when you get an annular eclipse).

But they are very, very different in their actual size, and in their distance from the Earth. In Father Ted terms, the Moon is small and close; the Sun is large and far away. In rough terms, the Moon is 400,000 km away and 3,400 km across, and the Sun is 150m km away and 1.4m km across. You don't have to change any one of those four measurements much for them to be quite different apparent sizes from the Earth. Indeed, if you do the calculations (which I can personally attest to), if you go back far enough in time they weren't the same apparent size, and nor are they if you go forward a long way in to the future.

Why? Why this coincidence? And why is it only happening at just the times when humans are around to observe it?

So far as I know, we have no good theories apart from "it just happened to work out that way". This is pretty unsatisfying.

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