exchemist

In what academic subject was this set as homework, and what are your thoughts on how to tackle it?

It was the height of the British Empire, though, and long-distance travel by ship was commonplace. Chronometers also were needed to determine longitude for navigation, so society, one way or another, was aware of the way time zones arise. And domestically, "railway time" had been established by the 1840s, to make time uniform across Britain, which was important to run a railway timetable, whereas previously it was not. In fact there is one relic of the Oxford meridian to this day, in the tradition of Tom Tower, at Christ Church, striking at 5 minutes past 9 each evening, which it does 101 times, commemorating the number of original scholars at the college. I remember as an undergraduate questioning whether noon at Oxford was really 5 minutes later than at Greenwich, so, with a bottle of port among us, we chemists sat down in someone'e room and did the geometry. And it is.

I got the same score, having forgotten how to do lowest common multiples and, like you, getting the St Petersburg time zone wrong (I thought it would be the the same as Helsinki).

No, an organism does not evolve during its lifetime. Evolution proceeds by differences in reproduction rate between individuals. Over many generations this affects the genetic composition of the population of organisms. Evolution is something that changes populations, not individuals.

What do you mean by taking a backup? They are passing on their genes to be mixed (at least in the case of sexual reproduction) with those of the sexual partner. So they are making a new mixture, rather than cloning themselves, if that is what you are suggesting.

Ah autism. That accounts for it. Possibly.

The atmosphere, broadly speaking, rotates with the Earth so to a first approximation the rotation does not make anything suspended in the air move, relative to a point on the ground. If this were not so, you would feel a constant wind, always from the same direction, due to the difference in rotational speed between you, on the ground, and the air. When it comes to second order effects, the rotation of the earth plays a role in determining various patterns of air flow in the atmosphere, e.g the jet stream, the trade winds, etc. But do not imagine these are simply due to a difference in rotation rate between the surface and the air above. The jet stream, for instance, flows from west to east, the same direction as the rotation of the earth, but faster, thereby creating a west-east wind, relative to the surface. This and many other air flows arise from a combination of heating and cooling in different parts of the globe with the effects of rotation, via Coriolis effects and so on.

How would your proposed index be an improvement on this?: https://en.wikipedia.org/wiki/Social_Progress_Index

I think trying to reduce the host of factors that comprise a desirable civilisation into a single index is not likely to be successful. I am not convinced all the peoples of the world want or expect the same things from their civilisation or society and I don't think publicising a single index with periodic rankings will capture their imagination. I think people are more interested in indices that reflect specific aspects of a desirable society, for instance an index on press freedom, or on the opportunities available to women. Such things have a clear meaning, whereas a single index putting everything into one pot will not. I also think the term "civilisation" is not the best to use in the context of social development. "Civilisation" encompasses a huge mass of factors: history, language, traditions, religions, moral codes, as well as modes of social organisation, institutions, political systems etc. If, as it appears, you are trying to create an index to rank some form of social progress, you are not talking about a lot of this and indeed a lot of it cannot be ranked in an index at all. So if I were you I would talk of "society" and not "civilisation.

What do you want to discuss?

All I mean is that the word interaction implies an event involving more than one entity. It is an action "inter", i.e. between, entities. What is interacting? There have to be somethings to interact, or it is wrong to describe the phenomenon as an interaction - it would just be an event. Clearly something is there in between (which we may describe by a wave function for example), sufficient to render the next interaction predictable. If there were nothing, there would be no predictability about the next interaction. So it seems to me it is the nature of that something that is up for debate.

S u r e l y n o t.

That view - of reality as a network of interactions and relationships - seems to fit well with Rovelli's relational interpretation of QM. But as it is those interactions and relationships that our mathematics models, such a view of reality implies that what we are doing (or should be doing) in science is to model a physical reality. And to go further, if we model interactions, there have to be some entities that interact, whether or not they can be said to have continuous existence in between. I may be in a minority, to judge by the other comments from the physicists here, but I suppose I am a bit of a Baggotista on this, cf. Jim Baggott's slightly provocative book "Farewell to Reality". (Full disclosure: I worked with him for a while when we were at Shell. Admittedly we are both chemists rather than physicists, which may colour our perspective.)

Ah well, what can be said to be "true" is another kettle of fish entirely. In science one tends to avoid bald truth statements. for the standard Popperian reason, viz. "truth" in science is only provisional. But the statements we make, with whatever caveats, are nevertheless about something that we think is real, I would say.

Yes I agree it is about what one means by "real". I would contend that those calculational conveniences, and more importantly the concepts which we relate to one another in our calculations, do in the end purport to tell us something about physical existence, i.e. what we think is real, even if they do not claim to be definitive. Otherwise why bother? I think the scientist must believe there is an objective reality out there to be modelled, or he or she would not make the models. To borrow from St. Paul, we may "see through a glass darkly", but surely we have to think we are dimly perceiving something real, don't we?

Yes, up to a point. However I always dislike the tendency to make out physics is all about maths. Physical concepts come before, or simultaneously with, the maths. You have to describe an electron and its properties in words before you can do any maths involving it. So yes, physics makes mathematical models, but the building blocks that the maths connects and manipulates are concepts of physical entities and their attributes that are, of necessity, described in words. The writer quoted also seems to me to somewhat evade the issue about "reality" when she says the wave function is "made up". That suggests it is a fiction. However the fact that this made up maths fits the observations so well shows it is a model of reality that is pretty accurate. So while no one would claim a wave function "is real", the wavelike behaviour it describes does at least represent an aspect of reality.

I bloody well hope so! 😁

Indeed. However, if there is 5-fold degeneracy in the rotational levels (in the ortho spin isomer), would that not be expected to affect the gas phase molar entropy?

It's best not to think of solubility in black and white terms. There are degrees of it. I don't know for a fact, but my guess would be that glycine has appreciable solubility in glycerol, but less than in water. I would expect the same to be true of many other polar compounds. When it comes to ionic compounds (inorganic salts) it may be a more complex picture, depending on the success that a big molecule like glycerol has in binding to a small, charged ion. Others here may have more knowledge of this than I do. But directionally yes, glycerol, being polar, should be able to dissolve polar species significantly.

Interesting. The BBC article doesn't explain how it works but I've found this paper with an abstract and a diagram that help explain this: https://www.sciencedirect.com/science/article/abs/pii/S0306261920311776 Here is the diagram: It seems from this that these microbes generate CO2 and H+ ions by decomposing organic matter below the surface of the soil and in the process release free electrons (!). The electrons are captured by the anode of the circuit. The cathode lies on the soil surface, which is exposed to oxygen in the air. There, H+ ions are combined with oxygen plus electrons from the cathode to produce water. So the net effect is oxidation (electron removal) of the organic matter, producing CO2 underground and water on the surface. The slight mystery is that this paper is from 2 years ago, so it seems unclear why the BBC has decided to report it as news only now.

Well then, since the spin of ¹⁴N is +1, that of ortho N2 will be +2, with potential components +2, +1, 0 -1, -2, so 5-fold degeneracy, vs single states for the para version. I suppose this should show up in entropy calculations for nitrogen in some way.

I suppose there are also in theory spin isomers of other diatomic gases. But probably the spacing between rotational levels is too small for this to produce discernable effects. It’s something I’d never previously thought about.

Ah the light dawns - maybe. I didn't realise that by "extra degrees of freedom" you might have in mind the 3-fold degeneracy of the triplet rotational states. If so then, er, yes, we're saying the same thing!

No. The pitch is determined by the rate at which successive peaks and troughs in the sound waves arrive. The starting and stopping of every syllable of the conversation will also arrive at the same rate, since both are determined by the speed of sound relative to the receiver.

In general I think the Doppler effect would speed up the conversation, just as it would raise the pitch of the speakers. Relativistic time dilation is another thing.