8 ms·
Scientists report asymmetry between heating and cooling
- ThalesX 3y agoDoes this mean ideal building design is as cool as possible and using energy for heating?
- kccqzy 3y agoI'm not an expert at all, but from my understanding, the ideal building is one that has so much insulation that its interior is kept at a set temperature with very little cooling and heating needed.
- cameronh90 3y agoYou still need to get rid of heat generated from inside buildings and potentially deal with the impact of ventilation.
- kccqzy 3y agoThere's heat recovery ventilation.
- gtbcb 3y agoYou also need to exchange air with the outside so that CO2 doesn't build up with people inside.
- juggertao 3y agoDepends on the climate. Houses built in southern Italy are like that (white paint, shutters on windows, ...) But in the Sweeden the opposite, optimize for heat.
- WinstonSmith84 3y ago> But in the Sweeden the opposite, optimize for heat. Not that much. As you mentioned just above, shutters are a layer of insulation. In Sweden, they have big glass windows and no shutters. The purpose is clearly to get the tiny bit of daylight in winter for health sake, but in terms of insulation, it would be better to have shutters, and smaller windows.
- neilwilson 3y agoThe other way around. Generally it is best to create an insulated box that stays warm when it is very cold and then cool it down when it is hot - because the reason it gets hot is due to increased energy outside (normally the big glowy thing in the sky) and that energy can be captured and used to power a house sized fridge. Energy to warm things up tends to be the sort of energy we can't really use any more.
- bmitc 3y agoI always feel a little stupid or strange reading a lot of these science headlines and introductions. I wasn't aware that people considered there to be a symmetry between heating and cooling. I thought that the entire point of thermodynamics is that they are asymmetric. Even the article mentions that it's been known that heating is more efficient than cooling.
- extractionmech 3y ago> On the other hand, cooling at the microscopic level involves the release of energy from individual particles, resulting in a dampening of their motion. This process corresponds to the system losing energy, leading to a decrease in the intensity of particle movement. It actually makes sense, doesn’t it? Heating the object adds energy constructively. In cooling, energy removed from one particle may in fact be absorbed again by neighboring particles, so it is not ‘efficient’. So I’d venture a guess at saying the object cools from outside until it is entirely cooled.
- hsuduebc2 3y agoAnd heating in that coming only from outside. Hah. I never realized that.
- jacquesm 3y agoHeating and cooling are rarely nicely split up in time. While you're heating something it is also cooling and while you're cooling something it is also warming up. This usually limits your ability to heat something up or to cool it because at some point these two are in balance.
- deleted 3y ago[deleted]
- schiffern 3y ago>And have questions like: 'Why don't we have a device like a microwave oven for fast cooling?'" Isn't that... just a blast chiller? (AKA a convection oven in reverse) It's not commonly found in households, but that's different from saying "we don't have a device" that does this. EDIT: Yes folks, I do understand how the principles of operation differ. Point being that the humble countertop convection oven definitely qualifies as "a device like a microwave oven for fast heating," and a blast chiller is just the reverse of that.
- tomrod 3y agoMicrowaves penetrate the interior of objects (outside of metal) that are in their Faraday cages, leading the internal temperature of those objects to rise dramatically. Blast chillers work like reverse ovens, from the surface to the interior.
- echelon 3y agoMicrowaves target the resonant frequency of intermolecular hydrogen bonds and impart vibration. It's a very special mechanism that doesn't really lend itself to this sort of analogy.
- deleted 3y ago[deleted]
- tomrod 3y agoPrior question was specifically about a quote and asked the question why a blast chiller isn't a reverse microwave.
- jmilloy 3y agoNo, because I think microwaves heat in a very different way from radiant heat gain (or loss) such as in an oven or this chiller you're talking about. The internal water is heated directly.
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- EGreg 3y agoDoes this have anything to do with volatility drag in trading? https://en.wikipedia.org/wiki/Volatility_tax https://en.wikipedia.org/wiki/Volatility_tax
- rpmisms 3y agoConsidering that Brownian motion applies (chaotic movement, generally in liquids, caused by heat), yes, the market mirrors the laws of physics here.
- cmrx64 3y agoThe theorems of thermal kinematics derived apply to limited models with a quadratic energy potential, localized on a spatial manifold. is there any reason to believe the market is described by this sort of model?
- rpmisms 3y agoMirrors != described by. Plenty of non-physical phenomena mirror physical occurrences, and this is one of them.
- i-use-nixos-btw 3y ago> While no immediate practical applications exist, the researchers envision enhanced efficiency in micromotors, microscale cargo transport, and materials that can self-assemble or self-repair. Everyone who has ever written a grant application will recognise this wording.
- lelandbatey 3y agoI'm curious what the meaning behind the recognition is. Is it "this has applications potentially anywhere!" Is it actually code for "very dangerous military applications, DARPA please pay attention to me!"
- lupire 3y agoSwarm of killer robots.
- koolba 3y agoIt’s code for: We’re not sure what it can do, but throw some more money at us and we’ll eventually tell you!
- epgui 3y agoIt’s code for: we are really interested in continuing to research this and we believe it’s important (for reasons that nobody will really understand apart from the other 5-6 world experts), so we are making this statement as much of a marketing stretch as possible without it being technically dishonest. Getting research funding is just a brutally competitive game.
- jacquesm 3y agoIn lots of published papers there is some kind of call-out for the requirement of future research. https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=more+research+is+needed&btnG= https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=more... A sentence like that or a variation thereof is part of the 'dance' around funding.
- Jweb_Guru 3y ago
- ninjaK4t 3y ago[dead]
- andrewflnr 3y agoThe phys.org article and science paper text are both impenetrable for different reasons (though I don't blame the paper). Can anyone explain this result like I have a college degree but not in physics? I'm especially interested in what the actual difference in "microscopic" process is between heating and cooling.
- AndrewKemendo 3y agoThey experimentally demonstrated that it takes significantly more energy to move a microparticle the same distance when cooled than the amount of energy it would take when heated.
- albertgoeswoof 3y agoCold things are harder to move than hot things
- kamray23 3y agoHow can that be possible, though?
- AYBABTME 3y agoIf something is already bumping around randomly, all you need to do is constrain the bumping along some dimensions and it will move less randomly and more frequently toward the remaining free dimensions. That's easier than having to provide all the energy to do the movement directly.
- quux 3y agoConstrained energy basically acts as mass right? So would an intuitive way to think of this be that the warm particle has more energy, but moving it confines where that energy can be so it behaves as if it has more mass?
- narrator 3y agoAlso, water that is heated reaches cooler temperatures faster: https://en.wikipedia.org/wiki/Mpemba_effect https://en.wikipedia.org/wiki/Mpemba_effect
- jackcosgrove 3y agoMy first thought upon reading the article was that absolute zero bounds coldness whereas there is no limit to how energetic a particle or bulk can be. Am I on the wrong track?
- WiseWeasel 3y agoThe upper limit would be magnetic force or materials required for containment in order to further energize.
- juggertao 3y agoAbsolute zero is very far away for all practical purposes to act as a bound.
- cjfd 3y agoThere is an upper limit when so much energy is put in that it creates a black hole.
- pmontra 3y agoActually there are temperatures below zero Kelvin, but they are hot https://en.wikipedia.org/wiki/Negative_temperature https://en.wikipedia.org/wiki/Negative_temperature
- angiosperm 3y agoWe knew about this: some kinds of heating can affect all the molecules, but cooling generally only those colliding with the walls.
- cmrx64 3y agoThis explanation is unrelated to anything considered. It trivializes what the paper actually studies, we certainly had no such theorem before this work.
- angiosperm 3y agoAcknowledged, good point.
- a_gnostic 3y agoWhile deployed, soldiers I know noticed hot water freezes faster than cold water. The Mpemba Effect, was later proven under some conditions (1) 1. https://www.smithsonianmag.com/smart-news/new-experiment-shows-why-sometimes-hot-water-cools-faster-cold-water-180975543/ https://www.smithsonianmag.com/smart-news/new-experiment-sho...
- Charon77 3y agoWell I mean there are more configurations in which a particle moves or otherwise vibrates, whereas there are less configurations with cooling. It's like if you have sand and water, it's really quick to mix the two together, but waiting for them to settle requires minutes to hours.
- quickcheque 3y agoI usually don't like to make such a meta comment, but in this case, it appears HN fails basic heat transfer and thermodynamics.