Jump to content

exchemist

Senior Members
  • Posts

    3409
  • Joined

  • Last visited

  • Days Won

    51

Everything posted by exchemist

  1. I got off my hamster wheel some time ago. I don't understand the rest of your post at all.
  2. It does seem to be a contentious area: https://en.wikipedia.org/wiki/Male_infertility_crisis Seems doctors don't believe there has been a significant fall in fertility while a number of meta-analysis studies suggest there is at least a fall in sperm count . It may be important that that does not necessarily lead to reduced fertility, provided the count remains above a certain threshold, which apparently it generally does. Curiously, I can find no mention anywhere of antibiotic use having been considered as a possible factor.
  3. As far as I know cellulose, e.g. cotton, is hydrolysed by acid, so by H+ rather than H2O per se. Wool is keratin, which is a fibrous protein. The amide links in this can also be hydrolysed under acid conditions. I don't know whether in neutral water either of the these processes occurs at a perceptible rate, but I suppose it is conceivable over very long periods of time. Maybe someone else here knows more about it.
  4. If they are miscible, i.e. you don't get a layer of one of them on the surface that prevents the materials beneath evaporating, then to a first approximation they will each evaporate at a rate given by Raoult's Law. This states that the vapour pressure of each component will be proportional to its mole fraction in the mixture. For example if a component comprises 1/3 of the molecules in the mixture, it will contribute a vapour pressure 1/3 that of the pure substance. There can be deviations from Raoult's Law when the molecules of 2 substances have more affinity for one another than for molecules of their own sort, or conversely when they have stronger affinity for their own sort than for the other. Here is a link to a fuller explanation: https://en.wikipedia.org/wiki/Raoult's_law. The 2 graphs give you first what happens in an ideal case and then what deviations from Raoult's Law can do. But in all cases the principle will be that of contributing a vapour pressure (which translates to an evaporation rate) more or less in proportion to how much of the mixture each components represents. N.B. this is on a molar basis (not mass or volume), as it depends of how many of the molecules in the evaporating surface layer are of each substance. So if you add a miscible slow-evaporating ingredient it will only slow down the evaporation of the other substances according to proportion of them it replaces in the mixture. (The limiting case is adding salt to water. The vapour pressure of salt is negligible. Dissolving salt reduces the vapour pressure of water and thereby elevates the boiling point. But it can only do so to a limited extent because you can't dissolve that much salt in water, so the maximum mole fraction has a limit.) If however it is a immiscible liquid of lower density, it will float as a layer on the surface and prevent what is beneath from evaporating.
  5. Identical rubbish previously posted elsewhere and shut down, so now it pops up here.
  6. There have, I believe, been reports of reduced sperm count in industrialised societies and some discussion about what might be responsible. Things like endocrine disruptors get mentioned but so far as I know nobody has fingered the widespread prescribing of antibiotics.
  7. I had an idea it might be something like that. So then the issue would be whether a commercial scale mineral transport operation could function with such long intervals.
  8. OK, Interesting. Roughly how many of the requisite planetary alignments would there be per year, or per decade?
  9. But you still stigmatise them as ill. So ill but stable?
  10. Yes the printing of the bible in the vernacular was a significant milestone, democratising the process of reading and interpreting the bible - and thereby to some degree disempowering the clergy. The printing press democratised knowledge of all kinds, a process the internet is taking further today - with even fewer controls on quality.
  11. Ah Hebrew. Why don't you put in "ballocks" and see what matches you get? That's the sort of thing I would do to demonstrate what rubbish it all is. Have you tried something like that?
  12. I’m confused by this. How do you get 14 out of the letters in David? Isn’t v alone 22?
  13. No matter was not "in the form of energy". That is the same confusion as before. There would have been radiation and fields (radiation is a form of oscillating field) that possessed energy. The entity is the radiation, or the field. Energy is one of its properties, along with other properties like direction, phase, frequency, amplitude and so forth. But my very limited understanding of this (I'm not even a physicist) is that when you try to extrapolate back you reach a limit at which our current theories of matter, radiation and fields etc break down. So we can't "see" any further back, even theoretically. Strictly, the big bang theory starts from the limit of credible extrapolation. All the stuff about singularities etc only has the status of conjecture, so far as I know.
  14. Yup, that’s a (quite common) misconception. We can only speculate about what might have been first, but what’s for sure it wasn’t just “energy” somehow existing on its own. That would be as silly as claiming that what came first was “momentum”, without saying the momentum of what. You can’t have a jug of energy any more than you can a jug of momentum, or velocity. All these are properties, not entities. Incidentally, “m” in Einstein’s equation does not stand for matter, it stands for mass, which, like energy, is a property of matter, not a free-standing entity. Another misconception is that the equation predicts “conversion” between energy and mass. What it actually says is that rest mass has energy. It’s not one or the other but both at once. The entities involved are radiation and matter. Energy and mass are properties. In the early stages of the big bang model, there is thought to have been radiation, and sub-nuclear particles, I think. It will have been these entities that possessed the energy.
  15. My understanding of this subject is that the killer, economically, is the huge cost of the change of momentum required to bring extracted minerals back to Earth. These asteroids are on a very different orbit from that of the Earth and momentum change (rocket power) is very expensive, per kilo of payload. By introducing fusion as a technical mcguffin to overcome that obstacle, it seems to me one is already making the exercise so far from practical reality as to have little meaning. It then risks turning into one of those "What if the sky were made of concrete?" questions.
  16. Well temperature is proportional to energy so in a way it is just a matter of choice of units whether one talks about temperature or energy in this context. To my way of thinking the distinction between the role of modes is not real, since all degrees of freedom that are excited (at NTP in gases vibrational modes generally aren't) contribute 1/2kT each to the overall energy - which means temperature, in effect. Yes, pressure is proportional to the temperature (or energy) in the translational modes, but it is also proportional to that in the non-translational modes too, as they are all equal. One test of the idea that the translational modes are special might be if one could make a case that the flow of heat is transmitted only through translational motion. I am sceptical, since the modes all exchange energy.
  17. That reply makes no sense.
  18. What would be the level of knowledge of your intended audience?
  19. The Shadow of the Wind, Carlos Luis Ruiz Zafon, in English translation.
  20. You have already asked this in another thread and you have already had answers. I suggest you stop posting idiotic videos. Nobody is going to watch them and it looks like spamming. There is no reliable evidence, that's why.
  21. Seems like rather a non-sequitur to my post, which was pointing out the absurdity of the claim that 1/3 of the New Testament is concerned with casting out demons. I also suggested that a lot of these "demons" were how people of the time interpreted mental illness, epileptic fits etc. That seems fairly uncontroversial. Nothing I said was a commentary on modern stories about supposedly paranormal experiences. But as for how I explain those, I share the view of others on the thread that some people tend to resort to paranormal explanations for experiences they can't account for. Others, of a more sceptical turn of mind or better educated, don't.
  22. Equilibration between degrees of freedom takes care of that. The pots are all connected together, in other words. Pressure, I grant you, is due to translational motion, (which is why a solid exerts no pressure), but I don’t follow your “and therefore the temperature”. Especially since solids do have a temperature.
  23. That seems to me a rather perverse way of seeing it. Surely all that is happening is that there are now 5 pots to fill instead of 3, when energy is added, so the rate of rise of the level is slower, for a given rate of addition? What experiment could be imagined to show that rotations do not contribute to temperature? I'd have thought there would be no such experiment, since energy is rapidly equilibrated among all degrees of freedom.
  24. I'm struggling with this. What does it means to say that rotational degrees of freedom don't contribute to temperature? Surely they do, since the heat capacity (Cᵥ) of a diatomic gas is 5/2R rather than 3/2R, once temperatures have been reached at which rotational levels are populated. And then it goes up to 7/2R once vibrations are excited. So these degrees of freedom affect the temperature of the substance for a given energy input. Is that not contributing to temperature?
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.