How can molecules generate thermal (~1ev) photons as heat? - Page 1
Forum section: electronics / general

author: Beamin
author_rank: Super Contributor
timestamp: July 20, 2019, 01:48:29 am
content: It always amazed and or baffled me as to how things can emit photons without having an electron jump down an orbital. Thermal photons in the middle of the IR band are around 1 ev. Since heat is just kinetic energy being converted to photons or electromagnetic do the electrons of one molecule get kicked up in a collision and emit a photon? I thought this could only happen with UV and high voltage. Furthermore how does this process work in the accretions disk of super massive black holes with xrays and could this even make gamma rays photon from with in the nucleus as there is not enough potential energy or distance an electron can jump to make Gev or what ever gamma rays are. Since there is no top to the frequency of very high energy photons what would be the mechanism if the photon comes from the nucleus without radio active decay or is thermal/kinetic energy enough to actually cause this? My understanding is that only electrons changing energy state can radiate photons.On the opposite end how does a long metallic wire emit a photon on an antenna at say 1000 meters in the (300)khz bands? One atom can't make anything that large. physics gets weird along the edges. Or can super high energy collations generate gluons or weak bosons? Are those found in accretion disks? Are there any astro physicists in the house?

author: lordvader88
author_rank: Frequent Contributor
timestamp: July 20, 2019, 05:40:33 am
content: Well photons are also emitted when someone jumps on the floor, so how exactly does that work ? I don't remember if they are RF or microwave energies, but I don't think they are IR level.So an incoming electron cloud of 1 atom/molecule, exerts a force on the electron cloud of atom/molecule 2, at some point some electron does gain energy, and then emit a photon.Why do so many atoms even exist, how is it that so many positive protons and negative electrons even enter into an 'orbiting system ? What would actually happen if an elec/proton meet and stick together, directly, without having the angular momentum to form an "atom" ? I suppose it's incredibly hard to meet and not have AM that doesn't cancel.The whole subject of matter vs anti-matter ratio's, etc. It so hard to make and study, but what in the world can that tell us that we never realize since it's so rare.

author: Nominal Animal
author_rank: Super Contributor
timestamp: July 20, 2019, 11:39:10 am
content: I shall attempt to induce an intuitive grasp of the matter here, not strive for exact representation of the physics involved:Quote from: Beamin on July 20, 2019, 01:48:29 amThere is no "collision" per se, just a change in exactly how the electrons are delocalized around the nuclei. The term you are looking for isspontaneous emission.If we consider a single molecule that does not interact with others, its velocity does not necessarily reflect its temperature. If that molecule is "hot", it means its internal degrees of freedom -- positions of the atoms in the molecule in relation to each other, the "electron cloud" around the nuclei -- contain "extra" energy; i.e., it is in an excited state, vibrating and whatnot. This energy, no matter how low, can be emitted as photons via spontaneous emission. It is a quantum mechanical phenomenon.If we consider a gas, liquid, or a solid, then the velocity of the molecules are involved in the temperature, because the molecules will collide with each other; the thermal energy will relatively quickly reach an equilibrium where some of it is in the velocity, some in the internal degrees of freedom. Again, the excited internal states can drop to lower energy states by emitting a thermal photon spontaneously. In the next few collisions with other molecules, the internal degrees of freedom will accrue more of the left-over energy, and the molecule slow down. (Conversely, if the internal degrees of freedom gain energy from photons, in the next few collisions the molecule will speed up.)(In magnetic fields, the interaction between the electrons and the field exerts "pressure" on the entire molecule, so the molecule can slow down via photon emission even without collisions. Similarly, at very low temperatures, laser light (photons with the same energy and phase) can actually keep atoms in place without heating them up; these are calledoptical tweezers.)Note that even intergalactic space isn't really empty enough to allow many molecules to zip along at huge velocities, while their internal structure is at or near a ground state: there are photons everywhere (microwave background at minimum), magnetic fields, and even an occasional atom or molecule here and there.Quote from: Beamin on July 20, 2019, 01:48:29 amAt highly energetic environments, the electrons around nuclei get so big energy kicks that they fly off completely. You get plasma: atomic nuclei and electron soup. No molecules. No spontaneous emission from molecules, because there are no intact molecules.Instead, you get stuff likebrehmsstrahlungor "braking radiation", electromagnetic radiation produced by the deceleration of charged particles.(Edited to add: If you want to generate x-rays, just peel off Scotch tape off its reel.)Quote from: Beamin on July 20, 2019, 01:48:29 amNo, there are a few other ways (than electron dropping to a lower energy state when bound to an atom, molecule, or lattice), likephononenergy state changes, too.Quote from: Beamin on July 20, 2019, 01:48:29 amIn metals, some of the outer electrons are not bound to any specific atom, but to the entire lattice. It is these electrons that interact with those photons.Quote from: Beamin on July 20, 2019, 01:48:29 amWhen you get to sufficiently high temperatures and pressures, even atomic nuclei break down into quark-gluon plasma. So, a single collision is unlikely to suffice; you need a lot of them in a small volume in a short timeframe to get to that.

author: GlennSprigg
author_rank: Super Contributor
timestamp: July 20, 2019, 12:26:22 pm
content: Quote from: Nominal Animal on July 20, 2019, 11:39:10 amSO THERE !!!!!!!!I'm not detracting from anything that was said above, and I'm just being 'silly' here......We love our Cats, but I've always joked with the Missus how they JUST convert Cat-Food to Heat !!That being said... WHERE does the actual HEAT come from, within the tissues/muscles in the conversion??I've never understood that specific chemistry/physics !!

author: Nominal Animal
author_rank: Super Contributor
timestamp: July 20, 2019, 01:53:48 pm
content: Quote from: GlennSprigg on July 20, 2019, 12:26:22 pmI don't know much at about biophysics, but Ithinkit is mostly from mechanical movement inside individual cells (in our metabolism), and in small part heat from chemical reactions. Although, at molecular scales, the two become nearly indistinguishable from each other... but I think that as an intuitive approach, that works.In particular,ATP synthaseworks like a mechanical pump. ATP is internally used by cells to provide "power". (Remember that in humans, a quarter to a fifth of all energy use is in the brain, so I am not talking about muscle movement generating heat; I am talking about how the biomachinery inside the cells of all animals generates heat because it contains so many moving parts.)One must remember that us kittens and other mammals, are warmblooded (endotherms; seethermoregulation). It means that our physiology has evolved facilities to keep our internal temperature stable to within a fraction of a degree, to optimize the chemical reactions and mechanics we need to live. Even fever is just an internal facility, and part of warm-blooded immune systems: internal temperature is raised to disadvantage bacteria (and perhaps viruses too). As large agglomerations of cells, we can take the extra heat, but single bacteria and some viruses cannot. Fever is not external, it is internal. Same with shivering. (Edited to add: Bees use that in the macro scale, to kill intruders. They pack close together around the intruder, then shiver/vibrate to generate heat, and kill the intruder with heat.) Cats' purring has a mechanical aspect that seems to promote healing as well.In general, fast small mammals with relatively large surface area need more energy than human intuition says (i.e., comparing them to a human). Plus, cats are obligate carnivores with short intestinal tracts, which means whatever they eat, soon comes out the other end (or the same end, if you happen to have an expensive rug), with nutrient extraction not so efficient. (Which also explains why doggos are so interested in cat nuggets: lots of vestiges of meat left.) To compensate, they (and larger cats too) sleep a lot.Me myself am obviously evolved for slightly colder climates than where I am now. At about 25°C/77°F, my mental faculties start degrading. I work best at about 17°C/63°F. Plus, I have an ample layer of blubber under my skin.

author: TimFox
author_rank: Super Contributor
timestamp: July 20, 2019, 02:16:37 pm
content: At room temperature (about 300 K),kTis about 1/40 eV. This is a useful combination to remember for back-of-the-envelope calculations.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 20, 2019, 03:21:33 pm
content: Quote from: Nominal Animal on July 20, 2019, 01:53:48 pmWhy is it that some people, mostly Asians, have a high metabolism and can eat a lot without getting fat? If the scientific reason for it can be found, how helpful would it be to solve the obesity epidemic?QuoteJust like Big Clive or Allie Moore!

author: Nominal Animal
author_rank: Super Contributor
timestamp: July 20, 2019, 04:31:25 pm
content: Quote from: NiHaoMike on July 20, 2019, 03:21:33 pmBeats me.Quote from: NiHaoMike on July 20, 2019, 03:21:33 pmIt looks like there is a connection at the genetic level with the way human bodies accrue fat and fertility. So, I would not be at all surprised if a medical "cure" for obesity also turns out to make people completely infertile.I'd suggest exercising more, but then again, pot-kettle-black, so...

author: Rick Law
author_rank: Super Contributor
timestamp: July 20, 2019, 04:34:17 pm
content: Quote from: NiHaoMike on July 20, 2019, 03:21:33 pm[ BOLD added to quote ]Differences between races are all in the genes and culture.In the case of fat people - there are plenty of fat Asians in the USA, so while they may be predisposed (gene) to be a certain weight, diet and discipline (culture) here in the USA is different. So, their parts (tummy, thigh, etc.) grow accordingly.If you study the differences, you would found for example Waist-Hip ratio and years-to-mature are also different across race. Correlation however is not the same as causation. Wider hip doesn't mean you WILL need less time to mature. But gene and diet will dictate how much estrogen you generate and when.World is full of different people, each differently adapted to their environment. In time, we may have some implant so every kid grows to be equal... May be...

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 20, 2019, 07:16:25 pm
content: Quote from: Rick Law on July 20, 2019, 04:34:17 pmIs "skinniness" a recessive trait? My parents are skinnier than Tiffany Yep's parents yet Tiffany Yep is a lot skinnier than me. (Needless to say, I'm jealous of her...) That appears to be really unusual since none of my other friends exhibit that.

author: Beamin
author_rank: Super Contributor
timestamp: July 20, 2019, 07:25:45 pm
content: Asians tend to walk a lot and eat many small meals that are full of simple carbs. If they miss a meal they crash because of not having energy stores. I live with Asian people and they are obsessed with food and constantly eating. Its also genetic.But how exactly does the ATP turn into heat? I know it turns into movement by a microscopic molecule scale "ratchet" where bonds form and break linearly as muscles contract. But how atp factors into sugar to co2 and h2o is a mystery.So can one atom have heat? or is it just its velocity? Also when they say plasma in electronics do they mean the valance electrons are striped or all of them are gone leaving a bare nucleus? In chemistry we never dealt with anything below valance electrons. a proton and hydrogen ion are two different things but the same.If the density of the universe is one h atom per cubic meter is the temp of that atom from the cmb heating it to 2.7k? Or are they independent? Why is the electric field such a close effect; <1mm, while a magnet can go a few cm, but RF is infinite? How can the gauge boson be a photon for all three aspects of the force if a photon has both a magnetic and right angle electric field?

author: Nominal Animal
author_rank: Super Contributor
timestamp: July 20, 2019, 10:24:48 pm
content: Quote from: Beamin on July 20, 2019, 07:25:45 pmSeecellular respiration.Quote from: Beamin on July 20, 2019, 07:25:45 pmHeat is fundamentally about transfer of energy. If you talk about a single atom, it depends on how you look at one.Even a single atom can have one or more electrons in an excited state, and emit photons. In that sense, yes, one atom can have heat, and it is not just its velocity. Yet, we're then making the assumption that that excited state was a result of heat exchange, and that is not necessarily true. It could be that the atom nucleus was hit by some high-energy particle or photon, and underwent some nuclear reaction, and that caused the electrons to get excited. Is that heat? One can argue either way.Until that atom interacts with something else, its velocity is just its velocity; associating any of it with heat means we assume the atom is a part of a system that is at rest in the frame we measured the atom velocity in.Yeah, it's all relative. It is also much better to think of heat as the property of a system or subsystem of atoms, and not of individual particles. That's the way I do it in MD simulations, if I want the results to resemble anything physical.Quote from: Beamin on July 20, 2019, 07:25:45 pmIn plasma, all the electrons are stripped. The state where only some of the electrons are stripped away, is called ionized gas.Quote from: Beamin on July 20, 2019, 07:25:45 pmThe cosmic microwave background is blackbody radiation corresponding to a temperature of 2.725 K. If you consider a region of gas at density of 1 atom per cubic meter, the atoms in the gas will interact ("collide") with each other, so that their velocities will eventually have the Maxwell-Boltzmann distribution. The temperature corresponding to that distribution depends on the total energy in that gas.Since energy cannot be destroyed, it means that the energy involved in the Big Bang is still around. (A lot of it is in neutrinos and such, that don't interact with ordinary matter too well, though.) That gives you the minimum average temperature of say intergalactic gas.If you had a subsystem of atoms (say, some wisp of gas) colder than CMB, those atoms would soon be heated up by the photons in the CMB to 2.725 K. Remember spontaneous emission? Atoms and molecules absorb and emit thermal photons, and eventually they'll be in equilibrium with the heat bath, the distribution of photons they absorb. (But, because CMB is pervasive throughout the universe, it means the cold atoms and molecules will heat up to the CMB temperature, eventually.)Quote from: Beamin on July 20, 2019, 07:25:45 pmBeats me!

author: Beamin
author_rank: Super Contributor
timestamp: July 21, 2019, 06:57:12 am
content: I often also wonder how the cmb still reaches us, shouldn't have passed us and moved on to some distant place? Seems if it came from a point or pulse in a set space and time it would extend outward in a shell. I know it has something to do with the fact you are always at the center of the universe. Is this because of the time vs distance? If the universe was smaller then old would this not be the case?

author: Nominal Animal
author_rank: Super Contributor
timestamp: July 21, 2019, 09:54:44 am
content: Quote from: Beamin on July 21, 2019, 06:57:12 amThing is, it didn't come from a point in space, but basically from everywhere in the very early universe. The CMB is from an era when the universe became sparse and cold enough for photons to not be immediately absorbed; as if the entire universe was an LCD, and suddenly turned clear, allowing all those photons to travel freely.This is why the CMB photons are roughly equally distributed around the current universe.(While the universe is finite in volume, it has no boundaries, and that's how and why the photons are still "here". The photons have travelled some 13 billion lightyears, but the point they originated from in the original universe is much farther away now, because the universe has expanded in the mean time.)

author: Beamin
author_rank: Super Contributor
timestamp: July 21, 2019, 12:05:10 pm
content: Quote from: Nominal Animal on July 21, 2019, 09:54:44 amIn my mind I try to trace back the path of the photon. I can understand the universe is like a loaf of raisin bread that rises and the raisins are the stars and spread apart but if you think of that the CMB photons would come and go. We can see distant galaxies because its still in view and not past the particle horizon but we will always see the cmb? The universe needs to fix this problem of me understanding it. That's how flat earthers think if I can't understand it its not possible.

author: Buriedcode
author_rank: Super Contributor
timestamp: July 21, 2019, 01:10:37 pm
content: What is this thread about really? Nominal Animal put great effort into trying to explain the original question, but then... metabolism and cellular respiration in mammals.. heat generation.. CMB.. its all over the place.btw, heavier/fat people have higher metabolism than skinny people, because it is generally the process of energy usage, heaver -> more cells -> more energy usage. The whole "skinny people have faster metabolism" is an old generalization that won't die, hyperthyroidism aside. Those who claim to not eat much but gain weight really do eat a lot, and those who claim to eat a lot but not gain weight don't eat as much as they think. It's not quite as simple as "energy in = energy out" because its hard to measure either accurately, but it isn't magic, and it isn't "just metabolism".Beamin, I understand you ask these questions out of genuine curiosity, but perhaps start off with more specific questions. You always seem to ask one question, then a load more semi-related questions. It makes it difficult to know what answers you need.

author: Nerull
author_rank: Frequent Contributor
timestamp: July 21, 2019, 03:50:50 pm
content: The universe was entirely filled with hot plasma which constantly emitted and absorbed photons and made it opaque. As this plasma cooled and began to deionize it became transparent. After this time, the thermal radiation emitted by these atoms could travel freely through the universe.When you look far enough away, you're also looking back in time to this era. Because this occurred everywhere, there will always be a distance at which it is visible because the light has taken all this time to reach us. The light from the recombination era that was closer to us has already passed us by, and more light from further away has yet to reach us. The CMB is a constantly expanding shell, as light from further and further away finally makes it here.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 21, 2019, 04:40:00 pm
content: Quote from: Buriedcode on July 21, 2019, 01:10:37 pmI have noticed that quite a few of my skinny friends eat as much as I do if not more. I even went on a date with one (Allie Moore) and not only was I surprised how much she ate, she insisted on paying for her fair share since she feels bad about others having to pay for it. She's also very tolerant of cold weather, supporting the fast metabolism theory.

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 21, 2019, 04:57:26 pm
content: Quote from: Nominal Animal on July 20, 2019, 04:31:25 pmQuite possibly, and yes.It's all related to how a given organism optimizes energy storage vs. energy delivery. Metabolism is one partial measure of that, but it's only a small part of the story.It is easy to figure out that those mainly come, historically, from environmental factors, at least when we as a species were still evolving biologically. It's becoming unclear whether we still are, at least in the same way and at the same pace as we used to (due to the fact human societies have largely "replaced" the role of biological evolution with culture, science and technology...)Talking about people that apparently eat a lot and don't gain weight - first we tend to have this impression, but real figures may show us otherwise. Many people think they don't eat much, but if they just noted what they really ate every day, they might be surprised. Then it's not just all about quantity, but about quality as well. Eating 500g of green beans is not the same as eating 500g of cereals every morning.So we are a combination of genetic and environmental factors, and we're leaning towards behaviors that are less and less adapted to our current environment. How much we eat and how much exercise we get is not the whole story. WHAT we eat counts as much, but probably a lot more even. The current diet of the average human being on this planet, except maybe a small minority, has nothing much to do with what it was just a few decades ago.Getting "abnormally" fat is basically the result of eating behaviors that are not adapted to both our individual genetics and our environment.But as you hinted, trying to "solve" the obesity problem by trying to modify how our body functions rather than trying to act in a more adapted way is a slippery approach that may yield unexpected results...

author: Beamin
author_rank: Super Contributor
timestamp: July 21, 2019, 06:51:08 pm
content: Quote from: Buriedcode on July 21, 2019, 01:10:37 pmThat's what my mind does; it likes to wonder and I learn a lot from the discussion here. I think the hardest question I have asked got answered here with two off topic posts in a thread: How does dust form in space: the answer was electrostatic attraction not gravity, and UV radiation. Tangents are tangential. I now know that the CMB doesn't heat the one H atom per cu m of space. Now my mind wonders how dark matter gets sucked into black holes and we must be able to measure this?Is there a empty dark matter wake behind black holes?