exchemist
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exchemist last won the day on February 29
exchemist had the most liked content!
Profile Information
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Location
London
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Interests
Rowing, choral singing, walking.
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College Major/Degree
Chemistry MA, Oxford
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Favorite Area of Science
chemistry
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Biography
Trained as a patent agent, then gave it up and worked for Shell, in the lubricants business for 33 years. Widowed, with one teenage son.
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Occupation
Retired
exchemist's Achievements
Scientist (10/13)
727
Reputation
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The Beginning of the Universe
exchemist replied to Chris Sawatsky's topic in Astronomy and Cosmology
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. -
The Beginning of the Universe
exchemist replied to Chris Sawatsky's topic in Astronomy and Cosmology
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. -
How many M-Type asteroids will Earth (truly) need?
exchemist replied to GeeKay's topic in Other Sciences
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. -
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.
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That reply makes no sense.
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What would be the level of knowledge of your intended audience?
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The Shadow of the Wind, Carlos Luis Ruiz Zafon, in English translation.
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do you believe demon possessions and fallen angels are real
exchemist replied to knowledgeispower917's topic in Religion
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. -
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.
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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.
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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?
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Indeed, as in fact is mention of “vibrations” [man]😁. With Tesla, it’s usually something to with magnets, though I was fascinated to learn, from a crank poster on this forum called Tom Booth, that Tesla also speculated about perpetual motion machines of the 2nd kind, capable of converting 100% of input heat to work.
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I am wondering about your mental stability.