exchemist

Good point. I assume either a natural steam reforming of methane: CH4 + H2O <-> 3H2 + CO (endothermic), in which case one might expect to find carbon monoxide associated, or else from natural cracking of hydrocarbons. But as hydrogen molecules are small, they may migrate away from the source of production, complicating efforts to determine how they were generated.

No. Bacteria are too large to penetrate into the material. But it may smell, from chemical compounds absorbed or adsorbed on the plastic. I find plastic food containers do pick up a taint if used for anything with strong smell. And colour, sometimes: tomatoes and turmeric especially.

Which knackers the whole idea of MOND though, doesn’t it?

In the circumstances it is reasonable to assume the results are more likely than not wrong. After all, the whole point of science is to be able to predict what we should expect to observe. So the first thing to do when results are far away from that is to try to reproduce them, in order to check them, before devoting a lot of time to exotic speculation. It seems this was done for another asteroid that this experimenter had applied his technique to - and lo and behold it was found he was off by more than a factor of 10. To make matter denser than the forces of electromagnetism and the nuclear strong force support, one has to resort to gravitation, in bodies containing enough matter to enable it to outweigh them, e.g as in stars.

Not really. Hydrogen in the context of iron and steel is a reducing agent, for reduction of iron oxide to iron. That's what coke does in today's blast furnaces. It's not just a source of heat. But I have answered my own question now: I see "Steel" does in fact appear in the category B list on the chart that @Ken Fabian posted. I must have missed that.

Conceivably. But you still need some credible process for creating one or more elements with an atomic number way beyond anything found in the solar system to date and moreover, they have to be stable isotopes, which seems highly doubtful for theoretical reasons.

Quite so. But I've been looking at the paper that prompted this pop-sci article and I think it is really about something else: https://link.springer.com/epdf/10.1140/epjp/s13360-023-04454-8?sharing_token=mpXkcFl6UFuZEgh4DYZK0YsPkCdkOxEKPl2JoxdvwqHW9N-hyrzP0f-_h1nqnhXLsBVT4-pBXuVn0gcP16CLQEc-ew_UOQdLD1nth6S52AHTdX0rhTFNttiC-j8pe1CuBqagSArD56jvpd9SuXeiQAMMgZtdthJYevFjXzWBsh0= The real interest of these researchers seems to be modelling superheavy metals to see what densities they might have. Their key point seems to be that densities are expected to be high for 2 reasons: (i) as Z increases, the ratio of neutrons to protons in the nucleus goes up, as the Coulomb repulsion between protons has to stay within certain bounds if the nucleus is not to fly apart, and more neutrons help to "dilute" the proton concentration. As a result, the nuclear mass goes up more than linearly with increasing Z. However (ii), the electrons, which determine the effective atomic radius, i.e. the volume the atom occupies, can be accommodated within a greater variety of degenerate orbitals of high angular momentum (f and I suppose maybe even g in some cases) as the principal quantum number goes up, so the atomic radius does not need to expand as fast as Z increases. I suppose what they must have in mind here is overcoming the constraints imposed by the Pauli exclusion principle, rather than electrostatic repulsion between electrons. I don't see anything stating that a nucleus with a Z of 164 is expected to be actually stable, in fact they admit they don't know. My understanding is that the islands of stability are only relative, i.e. the nuclei are less likely to fly apart than those that are not on or near the island. But they do refer to something called "CUDOs" (Compact Ultradense Objects) which they seem to think are a thing in astronomy. I tried to look these up but only got a handful of arxiv references, so I wonder if their existence is established or if they are just hypothetical exotica. Perhaps someone like @Janus would know. They also introduce another idea for a dense form of matter called "alpha matter". In this, they hypothesise a dense nuclear "gas" of alpha particles, bound (somehow?) in a Bose-Einstein condensate, permeated sufficiently by the electron cloud to reduce the Coulomb repulsions. Not being a nuclear physicist I have no idea whether this can really work or whether they are just playing with the idea. So quite interesting, but this is about nuclear modelling not astronomy. It looks to me as if they have thrown in the references to CUDOs and 33 Polyhymnia to make their research look as if it could have some practical applications.

According to Wiki, the only estimate of its mass was by Benoit Carry, whose results are thought to be most likely wrong, by a factor of 10 or more. The technique depends on the perturbations 33 Polyhymnia causes to other bodies, and this is subject to large uncertainties due to its small size. My money is on nuclear physics being right and these results being wrong.

Ah thanks. Your anecdote rang a few bells.

Was that one of the Solvay conferences?

No, you have just misunderstood what was being said about the interior of atoms. The comment about "everywhere and nowhere" is simply a scientist trying to express in simple words what quantum mechanics tells us about how matter behaves at the atomic level. The electrons in atoms behave in some ways more like waves than particles, and this limits the amount of information about the location and properties of them that can be defined at any given moment. Far from being "beyond the laws of physics", quantum theory, which is one of the most important advances in physics of the c.20th, accounts for such behaviour very successfully. As for "solid matter", you need to understand what a solid is, in terms of physics and chemistry. Solids can indeed be thought of as 99% empty space. That has been known since the experiments of Geiger, Marsden and Rutherford, back in 1911. (Again, if you brush up on your history of science, some of this may become clearer to you.)

You need to brush up on your history of science. The "flat planet" was already out of date by 300BC, when Eratosthenes made a pretty good stab at calculating the circumferences of the Earth. Every sailor will have known the sea curves out of sight at the horizon. The Greeks were seafarers. As for new ideas overturning established ones, that has always been a feature of science, throughout its history. Obviously you are right that individual scientists, being human, cannot help but have a personal investment in the hypotheses they espouse. However science is a collective enterprise, founded on reproducible observation of nature. It is, in the end, that which determines which theories are successful and which ones fall by the wayside. The personal preferences of individual scientists cannot prevent that. If someone were to come forward with observations that do not fit relativity, then first they would be carefully checked and, if confirmed, there would be Nobel prizes for anyone improving on relativity to account for the new observations. But if someone were to come along, as they regularly do on forums like this one, with some silly notion they have just pulled out of their arse with no observational support, then they would be dismissed as just another anti-relativity crank and sent packing. As for a board of ethics, as so much scientific research is now done all over the world, there are a lot of papers produced, many good but inevitably some bad, and a few even fraudulent, i.e. with fake data. The system of peer review is intended to catch those, but at times it fails to do so. There is not much more that can be done to prevent that, given the decentralised nature of scientific work. However, as I indicate above, in the end, results that cannot be reproduced will be discarded and so will any theories that rely on them.

I think the point of the link I provided is that in general a given characteristic may result from more than one bit of DNA. So there is not a one-to-one correspondence, in the way you were enquiring about. But I'm just a chemist, so not an expert on this stuff. There may be others here who can explain better.

Your "definition" of momentum is wrong and you are using the wrong formula. According to special relativity, E=mc² is not applicable to a photon. I went over this in post 11 of this thread.

This sheds some light on your question: https://knowyourdna.com/skin-color-genes/

Exactly. But I can elaborate. Firstly, there is no way to define "perfection" in this context. What can it mean? Secondly, there will always be sub-optimal features of any creature, however it has been bred. You can breed for one - questionable and highly subjective - ideal of physical beauty but end up with a creature prone to disease, or with a horrible temperament, or with allergies, or poor digestion etc. When you breed to optimise one aspect you inevitably sacrifice others.

No.

No idea. I am not an expert on pesticide chemistry.

Ah but that’s in the LM, when they were actually on the moon. What about the command module, which was less stressful and more comfortable? https://space.stackexchange.com/questions/35869/which-module-had-more-comfort-in-terms-of-living-space-the-lunar-module-or-th

In the case of IPA, if it is just the pure alcohol not much is going to go wrong with it over time. If there is any long-term oxidation it might generate a bit of acetone, that's all. The main risk would probably be degeneration of the container, if it is plastic rather than glass. Pesticides may however be a different kettle of fish, being more complex molecules that may possibly break down or oxidise in a variety of ways. So for those I would probably not want to exceed the stated shelf life too much, not by more than a year or two at most.

No, you have made that bit up about the amount of disturbance being associated with mass.

Yes, there is energy in fields, for example in an energised electromagnet. With photons, the “medium” is the electric and magnetic fields. A photon is a travelling disturbance in those fields.

No, a wave is not energy. A wave is a disturbance in a medium that has energy. A wave has many properties, of which energy is just one. If you are perhaps thinking of E=mc² , you need to be aware that that is a special case of Einstein's more general expression relating energy to mass and momentum, which is : E² = (mc²)² +(pc)² . p in this expression is momentum. For objects at rest relative to the observer, p=0, so it reduces to the familiar E=mc². But for light, which has no rest mass, m=o, so the expression reduces instead to E=pc. It is this that governs the energy of a photon, not E=mc². In fact, if you apply to this de Broglie's relation from quantum theory, which relates momentum to wavelength: p=h/λ (h is Planck's constant), you get something interesting. For any wave, the speed, c, frequency ν, and wavelength, λ, are related by c = νλ. So you can write 1/λ = ν/c. de Broglie's expression then becomes p = hν/c, and so E=pc becomes E=hν. This is Planck's famous equation for the energy of electromagnetic radiation.

This looks to me like quite an advanced applied mathematics question and as such is beyond me, I'm afraid. I started wondering about catenaries for a moment, but I don't know what I'm talking about. I think @studiot may be a mathematician. I wonder if he has any ideas.

I can't help you with the maths, but physically I think it may not be correct to assume that the surface of the droplet becomes vertical when the maximum mass it can support is reached. You have a constant surface tension (of 70 dynes/cm or so) and there will come a point at which the weight of the water exceeds the force from the vertical component of this tension. But it is not immediately clear what maximum angle from horizontal the surface will attain when that point is reached. It could well be that the weight becomes too much when the angle is only π/4, or some other angle. I think this has to be calculated.