KJW

Or as Rowan Atkinson has said: The freedom to be inoffensive is no freedom at all.

I don't agree with this because one also has to consider that the laws of physics determine the intrinsic size of the units that we define. The constancy of the fundamental constants is implied by the constancy of the laws of physics. For example, suppose you measure the length of some object. You use a steel ruler to measure the object in metres. But you could count the number of iron atoms along the edge of the ruler. Thus, instead of measuring the length of the object in metres, you have measured the object in terms of iron-to-iron interatomic distances. Any change in the laws of physics that alters the iron-to-iron interatomic distance would also alter the length of the object by the same amount, and therefore the length of the object in terms of iron-to-iron interatomic distances would be unchanged. But this invariance implies that the changes of the laws of physics cannot be measured, which justifies the assumption of the constancy of the laws of physics. When you express the fundamental constants in terms of their dimensions, the result is a system of equations. When this system of equations is inverted, you obtain a definition of the Planck units in terms of the fundamental constants. In principle, you could measure everything in terms of the Planck units. The laws of physics govern the intrinsic size of the Planck units, but you can't actually measure the Planck units because everything is measured relative to the Planck units, and therefore the laws of physics cannot be anything but constant. Also, because the Planck units are expressed in terms of the fundamental constants, the fundamental constants cannot be anything but constant. As I see it, the use of natural units is about making all the ostensibly different dimensions of measurement the same. So, whereas time and length appear to be different, multiplying time by c rescales time so that it is the same as length. And when this is done, c becomes 1 and dimensionless (but only because time and length now have the same dimensions).

@Killtech, I think you are on the verge of realising that c (and the other fundamental constants) must be constant because when we measure something, it is relative to the definition of the units that have been used, and therefore, in order to obtain a definite value for a measurement, the units of measurement have to be assumed to be intrinsically constant.

When I first saw this a few days ago, I thought it might be a joke. It reminds me of the Scunthorpe problem.

The deflection of light by the Sun is twice that predicted by Newtonian gravity. Half of this value (equal to the value predicted by Newtonian gravity) satisfies the equivalence principle and is the result of the gravitational time dilation. The remaining half is due to the curvature of the three-dimensional space. I believe that these two halves are equal because the spacetime trajectory is lightlike.

Perhaps it would help if you read the Wikipedia article on the history of atomic theory: https://en.wikipedia.org/wiki/History_of_atomic_theory Knowing the history of atomic theory provides an understanding of how the knowledge of atoms developed over time.

Another example is a chemical synthesis, the product of a particular chemical reaction on a starting material whose structure is known by whatever means. It may be that the substance produced has never been produced before. In this case, there is no known sample with which to compare our substance produced. But the substance produced is not entirely unknown, either. It is likely to be the substance that was intended to be produced on the basis of what is known about the chemical reaction. And if it is not the substance that was intended to be produced, then it is likely to be in some way related to the starting material or the substance that was intended to be produced. In either case, it becomes much easier to analyse the spectra of the substance than if the substance is truly unknown. Proton nuclear magnetic resonance spectroscopy is especially useful in this regard.

There is a force acting on the wires due to the magnetic field. Magnetic field??? Where did THAT come from???

The solubility of Ca(OH)2 decreases with temperature. However, heat may speed up the equilibration. The solubility of CaCO3 is actually not very low (0.013 g/L @ 25 °C, although it will be lower in Na2CO3 solution), so the problem I mentioned above may not be as much of a problem as I had suggested. I think heating the mixture with stirring will eventually complete the reaction. In a laboratory setting, one could use a Soxhlet extractor to extract Ca(OH)2 into the flask containing the Na2CO3 solution, though this is probably overkill.

I think it's like eye of newt. Welcome to the alchemy forum. The problem with trying to react undissolved calcium hydroxide is that the solid particles tend to become coated with insoluble calcium carbonate, preventing further access of the calcium hydroxide to the carbonate solution.

https://en.wikipedia.org/wiki/Formose_reaction

Broadly speaking, you are asking how a chemist knows what a given substance is. In the modern day, we have several instruments that provide spectroscopic data that helps identify the structure of a substance. It should be noted that this depends on the purpose of the investigation. For example, if we simply wish to check that the substance is what it is claimed to be, then one can simply compare a spectrum of the unknown with a spectrum of a known sample. The spectrum itself need not provide much information about the structure because all one needs is that the two spectra be the same, like comparing fingerprints. By contrast, if the substance is truly unknown, then one would choose spectroscopic data that provides useful information about the structure. And different instruments provide different information about different aspects of the structure. For example, a low-resolution mass spectrum tells one the molecular mass of the substance. A high-resolution mass spectrum tells one the molecular formula of the substance. A proton nuclear magnetic resonance spectrum provides information about the environment of each hydrogen atom in the molecule, including couplings to adjacent hydrogen atoms. X-ray crystallography provides what is more or less an actual picture of the molecule, including precise bond lengths and bond angles (though this does require a good quality single crystal of the substance, and substantial computer processing of the diffraction data, and may not provide a complete picture). There is of course a lot more that could be said, but I think the above provides a glimpse into the world of the working chemist.

Unless you can produce a metric that describes what you are saying, it violates General Relativity. And unless this metric agrees with measured data, it violates reality. Although we don't currently know what dark energy is, any hypothesis needs align with General Relativity, by which I mean that it needs to use the same language as General Relativity.

As I see it, the band gap is the minimum energy difference between the bands, whereas the width of the bands themselves can increase the energy difference that is accessible. A 1 eV band gap corresponds to an infrared photon of wavelength 1240 nm, whereas a 4 eV band gap considered to be an insulator corresponds to an ultraviolet photon of wavelength 310 nm. Thus, the band gap of a semiconductor is thermally accessible, whereas the band gap of an insulator is not visibly accessible. I was unable to locate data on band widths, so I can't at present say that the energy difference between the bands admits visible photons. I'm guessing that there is an immediate absorption and lossless reemission that is due to the continuum of energy differences between the bands. This is different to refraction and different to absorption by non-metallic materials. However, I must say that the details are getting somewhat beyond me. Have you ever seen rhodamine B? It forms shiny dark green crystals and a violet solution (and violet smears in trace amounts on a white benchtop). I find this intriguing.

I don't know if thermal excitation is necessary for a metallic lustre. The energy of visible photons may be sufficient to bridge the band gap. And because of the almost continuum of energy levels, reflections would occur over a broad spectrum, appearing as an opaque metallic lustre.

It's my understanding that's how semiconductors work. It's why the conductivity of semiconductors increases with temperature instead of decreases like normal conductors.

I think enough time has passed that we can now do the problem.

He probably got it from a chemical supplier, and he knows it's silver nitrate probably because that's what it says on the label of the bottle it came in. My point is that modern day chemists do not start from scratch. They (to use a well-known quote) stand on the shoulders of giants. It should be noted that knowledge of chemistry developed over time and in parallel with knowledge of physics. I think that the scope of your questions is too large for anyone here to provide you with genuine help, as much as they may try. I recommend that you study a chemistry textbook aimed at school children. However, you may find this Wikipedia article interesting (though I haven't fully read it myself): https://en.wikipedia.org/wiki/History_of_chemistry

Ooh, don't tell the Americans that... they'll accuse you of being a communist. That's one thing I'll never understand about Americans... the way they fiercely defend their right to be exploited by the rich.

... would it be a red state or a blue state? I've also heard Trump say that Mexico should become a US state. Maybe Claudia Sheinbaum should take him up on that offer. Then Trump would have to open the border with Mexico and allow Mexicans free reign of the US. Wouldn't THAT piss off his MAGA supporters?

And that's just ONE billion dollars. For 400 billion dollars, it would take almost 12800 years. So, to accumulate 400 billion dollars in almost 12.8 years would require a THOUSAND dollars every second. Can you imagine what that would look like in coins?

This is a discussion forum, not a proofreading service.

Viruses are not sufficiently alive to be considered successful abiogenesis. One hypothesis I have seen is the RNA hypothesis, where RNA molecules act as both replication templates and catalysts, thus fulfilling the necessary requirements of life. However, it still seems like an enormous hurdle to go from that to having proteins as catalysts and therefore requiring the implementation of a genetic code.

But even if one has all the ingredients in place, there still has to be that final step where it all comes together to become a living cell. It's all well and good to be able form a primordial organic soup from simple compounds over millions of years by energetic processes such as lightning, etc., but even if all the molecules that make up life have somehow been made and are present at the same place at the same time, there is still the hurdle of it all becoming organised as a living cell.

No, as in abiogenesis, but with all the components present at the same place and time. If one had something like a bacteria "smoothie", could this self-organise into live bacteria, and has this ever been observed? I'm guessing it hasn't, but thought I'd ask anyway.