exchemist

I was addressing your comment about the rotation rate and the size of the object, in reply to @swansont. That was about Arawn, was it not?

As far as I can see the rotation rate of Arawn (5.47hrs) doesn't present any issues. Most astronomical objects rotate, either due to past collisions or due to angular momentum of the material from which they condensed.

Can you explain why you think 3D printing in a vacuum or under higher ambient pressures would present a challenge? I can't see what the problem would be. So long as the material in question would not be a liquid that might boil under vacuum, that is.

I am not aware that there is any law requiring individual companies to be net zero by any deadline. What industry is this, in what country, and what pressure is there for it to achieve net zero unilaterally? Yes that went through my mind too. As did Spike Milligan's remonstration: "Look, I died in the war for people like you."

Hard to disagree with these sentiments in general. There is undoubtedly a big element of 20:20 hindsight in a lot of criticism of previous generations. We simply knew much less then. This is normal: society learns as science advances. But to be fair to Thunberg (and to my 19yr old son) it is people one or two generations older than them who are today's decision-makers. There have been inexcusable levels of complacency, and blank refusal to face facts, from a lot of people of our generation, which the coming generation understandably finds very frustrating, especially as they are the ones who will be saddled with the consequences of dilatory action by our generation. Finger-pointing is on the whole not a constructive exercise, as it makes the pointer angry and the pointee defensive. The thing to do is recognise the issue and cooperate in solving it. Thunberg has been great at raising the profile of the subject but, being autistic, is no diplomat. That should not be surprising.

Well let's see. The volume of a sphere 60km in radius will be 4/3 π . (6x10⁴)³ ~ 9 x 10¹⁴ m³ (again check my arithmetic). If it's ice with a density of 1000kg/m³, that is 9 x 10¹⁷ kg. g at the surface of this planetoid will be GM/r², i.e. 6.7 x 10⁻¹¹ x 9 x 10¹⁷/(6 x 10⁴)² ~ 1.7 x 10⁻² m/sec². , if my maths is correct. That would be about 3 times the centripetal acceleration needed to keep the body together. So if my arithmetic is right there is no issue here: the body would be expected to stay in one piece. But where does this velocity figure come from that you are quoting? By the way, I have looked up Arawn on the web and I can find plenty of references to its rotational period but no reference at all to this being anomalously fast, or any puzzle about why it does not break up, in any of them. Which is just as expected if my estimate above is of the right order of magnitude. So indeed it starts to look like ballocks.

Seems this thing has a rotation period of 5.4hrs and a radius about 60km. That would imply a centripetal acceleration at the surface, rω² = 60x 10³ x (2π/(5.4x3600))² if my arithmetic is right, which I think works out at ~ 6 x 10⁻³ m/sec². That's not huge but I suppose the gravitation of a body that size will also be small.

Yes but none of the mechanisms being speculated about are artificial. The alien stuff comes into Loeb's article as a throwaway remark at the end and does not reference any hypothesis that is being studied seriously. If indeed the excess acceleration is inversely proportional to the square of the distance from the sun, it is directly proportional to the intensity of solar radiation flux experienced by the object. Ockham's Razor would favour a number of natural hypotheses over alien space drives.

I don't know but, purely speculating, I wonder if (assuming you are right and it is true) it could be because organisms that move about can end up in a wider variety of habitats, and therefore are exposed to wider range of evolutionary pressures.

The chief effect of altitude training is to increase the concentration of red corpuscles in the blood. You have yet to give any reason why your breathing hypothesis would affect obesity. Why would more red blood cells make you thinner?

If legislation drives the desired behaviour, the ones that adapt best will be the most profitable. Legislation has the virtue that it provides a level playing field for all players in the market and the most ingenious in adapting will benefit.

Oh I see. Comparing a temperature of 10C with one of 30C and applying the gas equation pV=nRT, the change in concentration of oxygen would be 283/303 ~ 93%. So yes there would be 7% less oxygen in the air at a given altitude in a county with an ambient temperature of 30C, compared one of 10C. This is about the same change as you get by climbing 600m above sea level, i.e. a bit over halfway up a munro in Scotland. For comparison, the British rowing squad does its altitude training at 2000m (in Austria). I doubt that 7% makes much difference. You are ignoring by far the most obvious effects, which are diet and lifestyle. What the UK and the US have in common, sadly, is a rather sedentary lifestyle and bad diet, driven by the disappearance of the the culture of eating home-cooked food at family mealtimes, and the pervasiveness of soft drinks.

So you think there is less oxygen in the air in hot countries? That's untrue. Where did you get such a weird idea?

I think your metaphor about the little pigs overlooks a crucial point. This is that industry will only move when pushed by legislation. And legislation on climate mitigation measures will only become a priority when the voters treat it as such. So one has to pursue twin tracks: yes, the technocratic one you advocate to implement changes, but also a PR campaign to keep the pressure on legislators to act urgently. In the UK, the electricity transition is well under way and the shift on vehicles is starting to build momentum (though more help is needed on the charging network and associated electricity infrastructure). But the government is still ducking the issue, completely, on domestic heating and insulation. So we need to keep the pressure on our elected representatives.

Ah I see. Firstly, what's your evidence for that? Secondly, by what mechanism do you think better breathing would avoid weight gain?

I can't make much sense of this. In a sentence, what point are you trying to make?

Yeah. Bye.

Yes, it's an answer. Bye. 😄

OK so you would not want the freedom to work anywhere in the EU, then. It is still helpful when moving around Europe, I think, to countries not within the Schengen area, and for things like health cover when visiting. But not game-changing.

Can you try to rephrase this? It appears meaningless.

No, it's the electromagnetic interaction.

EU citizenship, if you do not already have it, is definitely worth having. But I think they have quite tough requirements for fluency in Dutch, familiarity with Dutch customs etc. But you may already speak it of course, living where you do.

I would think it will be a measure of the elasticity in the arteries, which are supposed to act as dampers, absorbing the shock of the pulse by stretching and then progressively returning to the unstretched state. If your arteries have hardened, the pulse pressure will go up higher because there isn't so much "give" in them.

Yes I've occasionally wondered why he had a Low Countries name: van rather than von and Beethoven pronounced Bayt-hoven are very Flemish.

Well it's fairly obvious he wasn't black. That's a ridiculous idea, given the time, place and circumstances of his life. God preserve us from people trying to shoehorn identity politics into everything. The identification of this Ashkenazi woman is interesting though, as it was that strand of hair that gave rise to the lead poisoning hypothesis. They think he had hepatitis B, I gather, though his wine drinking will not have helped.