exchemist

No, this is also as stated in Diarmaid MacCulloch's "A History of Christianity", MacCulloch being Professor of Church History at Oxford.

Surely that cannot be right. If the metric itself expands, it must affect everything in the cosmos, mustn't it? Obviously in a bound system all that would happen is the dimensions stretch a bit locally, i.e. not enough to materially alter its configuration. But I can't see how anything can be exempt from a change in the metric. The metric defines the unit of length itself, doesn't it?

Are you sure about that? I should have thought that if the metric itself expands, then the dimensions of everything must do so, though the change for points close together would be very small.

St Paul (Saul of Tarsus) was a Roman citizen and travelled extensively in the Eastern Med. According to the Wiki entry on him, Koine Greek was probably his first language, even though he was a Jew. https://en.wikipedia.org/wiki/Paul_the_Apostle. This lists what sources we have for his life. There seems no particular reason to doubt that he was a real person.

Hmm, do you mean that a glass prism gains mass if you shine a light through it? I struggle to see how that would work, I must admit. Unless..........you mean that the coupling of the radiation to the medium "lends" some of its energy to it as it passes through, which I guess it does if its refractive index deviates from unity.

Surely St. Paul wrote in Greek because he was not writing to Aramaic-speaking Jews, but to people in and around Asia Minor (Colossians, Ephesians, Galatians, Corinthians, Thessalonians etc.) who spoke Greek, it being the end of the Hellenistic period in the Eastern Med.

Sort of, ish. Light is not energy of course: it has energy (E=pc = νλ), which can be added to that of an entity that absorbs it, which will then gain mass according to E=mc².

Sure. My interest in the issue was merely that I often, when explaining E=mc² to lay people, use the example of charging and discharging a battery, to show that the formula says mass and energy go hand in hand, rather one being converted into the other, which is what the uninitiated frequently seem to think, probably due to the association of Einstein's formula with the mass defect in nuclear fission. And then it struck me suddenly that, while it may seem comprehensible that an object with mass, like a battery, may in theory gain or lose a tiny amount of mass, it is less obvious what happens to something nebulous and apparently massless, like the magnetic field of a solenoid when it is energised. So I wanted to make sure my way of explaining it covered that case as well.

Oh I see what you mean. But as there isn't really a classical picture of covalent bonding in chemistry, it's a tiny bit artificial.

Not sure that's a great example, as elemental silicon has a giant covalent structure, in which the bonding involves electrons in motion in orbitals shared between atoms, but no doubt one could consider changes to a purely ionic structure that would alter the energy of the lattice and thus its mass. So I do take your point.

Where does the methane come from?

No indeed. My question was far more basic, simply whether a static electric or magnetic field has mass as a consequence of its stored energy. I realise now that my question was at one level a bit stupid, since if a battery gains mass when charged (albeit to an unmeasurably small degree ), it means the energy in the chemical bonding goes up and gains mass - and the energy of that bonding is a sum of the electrostatic potential and kinetic energy of the electrons. So it seems to me now that a static field must indeed have an associated mass, even though this feels unintuitive when one thinks of the magnetic field of a solenoid for example. Also, from the other (very interesting) replies, it dawns on me that I should not find this idea of fields having mass unintuitive, since (as I understand it, very vaguely) fundamental particles are considered in QED to be excitations of a field. I probably need to let go of this rather 6th form idea of mass applying to things called "particles" of matter, as distinct from insubstantial things called "fields". You are psychic! I was just replying. (I was out most of yesterday.) There is some excellent food for thought in this thread and I'm glad I left it long enough for those replies to come in before responding.

Responding today to the thread in Speculations, it struck me I don't know how to treat the stored energy in a static EM field, according to E² = (mc²)² + p²c². Since, unlike the situation with EM radiation, there is no motion involved, I presume the second term does not apply. But does a static field gain rest mass, as its stored energy increases? Seems weird if true. I've a feeling I'm missing something here. Can anyone help?

Unfortunately this attempted explanation makes a common mistake. Matter is not converted to energy. What the equation says is that mass implies the presence of a type of energy, called rest energy. Both mass and energy are properties of physical systems. Neither is "stuff". You can't have a jug of energy, nor can you have a jug of mass. Any system comprised of matter that gains or loses energy will also gain or lose mass, according to the formula. So yes, your battery will gain or lose mass when charged and discharged. Note that both mass and energy are gained and lost together. They are not converted from one to the other. They go hand in hand. The formula is an incomplete, short, form of the full formula, which is E² = (mc²)² + p²c², where p is momentum (as measured from some frame of reference). So energy can be present due to momentum as well as due to rest mass. This accounts for the energy in radiation, which has no mass. If you have a nuclear reaction in which rest mass is lost, it just means some of the rest energy has been converted to energy in other forms, including energy in radiation and kinetic energy of particles. Just as when you discharge your battery, it too loses mass due to the release of electrical energy.

Well yes, to the extent that you swallow some of them and digest them. But that is going to be an infinitesimal proportion of your dietary intake.

Though it would presumably accelerate osteoporosis, eroding the gain.

Aha. Thanks very much. (I experienced 6 weeks of anosmia myself, without any apparent lung infection, with the plain vanilla original variant, back in March 2020).

That was deliberate on my part, once I had decided that generating a telephone number, via a series of ad-hoc, wild assumptions, would be too tedious and ultimately fairly meaningless. But do feel free to have a go........

That raises a question: the virus seems to work by binding to ACE2. I had thought ACE2 was most abundant in the lungs, rather than in the nose and throat. Yet Omicron typically gives a runny nose and sore throat, like other upper respiratory tract viruses. Do these also work via ACE2? If so why do they not also invade the lungs? Or do they work another way, and if so, does it suggest Omicron may also now be gaining entry by a different mechanism?

But you still have the same problem with an orbit around L2, as I understand it. There is a still a tendency for the object to drift either inward towards the Earth/Sun or outward away from them, i.e. to drift perpendicular to the plane of the object's orbit.

Relatively few, I should have thought. The only ways material can be incorporated in your cells are via respiration and metabolism, i.e. what you breathe in and out and what you eat and drink. Since nothing you eat and drink comes from your colleague we are really talking about breathing, specifically how many atoms from the CO2 and H2O you each exhale becomes incorporated in the other's cells. Since CO2 and water you breathe in does not become part of your cells to any significant extent, it would be the CO2 and H2O converted via photosynthesis to O2 and carbohydrate that you might subsequently breathe in or ingest. So if you want to minimise any exchange of atoms, get rid of all the office plants, and do not, on any account, eat any office-grown tomatoes. 😁 But as for numbers, it would be a difficult exercise to do, a huge range of assumptions would have to be made and the resulting telephone number would be essentially meaningless.

Well I suppose we should be grateful this is not promoting invermectin.......yet............🤪

Insofar as they control the behaviours in ADHD patients that lead them to suffer elevated risks of infection, yes. Otherwise, no. Or at least not according to my reading of these links. Specifically, there seems to be nothing here to suggest that a non-ADHD person would benefit from taking these medications.

As in the VW beetle (originally Hitler's "Strength Through Joy" car), the Porsche series derived from it and the VW camper van, all of which use flat 4 or flat 6 "boxer" engines. As the cylinders are more exposed, these can also make air cooling practical, simplifying the design. Which reminds me of a story from my time in the Lubricants division of Shell UK, at the end of the 70s. Some fellow lodged a quality complaint that the Shell engine oil he had bought had gone solid in the sump and ruined his engine. We analysed a sample of the strange jellylike material from his engine and found traces of what seemed to be the oxidation products of ethylene glycol. Further enquires revealed that as winter was coming on, he had decided it was time to put antifreeze in the engine. He had opened the only filler cap he could see and poured it in........ We also, at that time, made a special product for British Rail, called Rotella HST, for the Paxman Valenta engines in the High Seed Train. These were prone to leak traces of coolant into the oil system. From memory this product had some sort of boosted antioxidancy, to resist the autocatalytic effect of glycol oxidation products in the oil. But I digress.

Actually I was wrong on one point: seems kerosene is used for rocket fuel. So no doubt they could collect a kerosene fraction from this pyrolysis process and use it. But it's not very environmentally friendly, as the other fractions are carbon-rich fuels. I'm not sure we want to burn our waste plastic if we can help it.