9 ms·
Absolute Hot
- bovermyer 8y agoA temperature so hot that we have to invent a new quantum theory before we can figure out what physics would be like at that level? Yikes.
- SurrealSoul 8y agoLooks like they found a way to measure my mix tape
- deleted 8y ago[deleted]
- Bjartr 8y agoIf this were reddit I would've upvoted you, but this kind of cleverness should, if it constitutes the whole post, should be left to reddit. Now, should this thread ultimately hehehe a discussion on the virtues and approaches to creating mixtapes it would be another thing, but at this point in time I'm not seeing this as a positive contribution to discussion. That is why I downvoted your genuinely amusing comment.
- probably_wrong 8y agoNot that I disagree with you, but I should point out that it's a reference to the video "Absolute hot" of the YouTube channel "Casually explained".
- Bjartr 8y agoPersonally, I don't think that changes what constitutes a good discussion contribution on HN. There's plenty of discussion here going into the details of the physics and the semantics at hand. We don't have to lower the bar for the discussion just because the topic under discussion was presented in a simple way.
- Sangermaine 8y agoYes, Hacker News comments should be reserved for vague libertarianism and blockchain hype.
- SurrealSoul 8y agoNo worries, I knew this isn't the place for it but I couldn't resist. Thanks for your honesty!
- WilliamEdward 8y agotl;dr - no fun allowed.
- Bjartr 8y agoHave your fun, just also contribute to the discussion in a meaningful way. If you're looking exclusively for mindless fun, you're really in the wrong place. And there's nothing wrong with enjoying that kind of thing either, there are just better places to do it than HN.
- rocks 8y agoWhat is "simple english" below languages? Never seen this before.
- antsar 8y agohttps://en.wikipedia.org/wiki/Simple_English_Wikipedia https://en.wikipedia.org/wiki/Simple_English_Wikipedia It is an intentionally simplified version of English. Although, in this case, the meaning of the article seems to have been affected by the simplification. The English version makes it clear that this is a theoretical concept, whereas the Simple English version makes it sound like something concrete/absolute.
- krylon 8y agoIronically, I found the Simple English articles I tried to read harder to understand than the regular ones. Interesting concept, though.
- mmirate 8y agoIronic but inevitable; the simplification appears to mostly be a matter of vocabulary. Reducing the vocabulary usually eliminates most technical jargon, and when the subject-matter is technical, the result is, well, a mess.
- dfxm12 8y agoIt's been around for nearly 15 years. It's geared towards younger folks, folks with learning disabilities that might make it hard for them to read and people who are learning English as a second language. https://simple.wikipedia.org/wiki/Simple_English_Wikipedia https://simple.wikipedia.org/wiki/Simple_English_Wikipedia
- hnryjmes 8y agoor, how my Pixel XL feels in my hand after about 10 minutes of use
- MrEfficiency 8y agoPlanks Constant really changed my understanding of what the universe is made of. Our physics and understanding of matter seems to be relevant under very specific conditions. The moment we can make technology that can impact the smallest of sizes(if this is even possible), we might get an answer for what the universe is. Or maybe it would turn out to be "42" and it still wouldnt make sense.
- dandare 8y agoQuestion: is the analogy of thermal energy as particles flying around and bouncing into each other just analogy? At what temperature would the particles fly at the speed of light? > Above about 10^32K, particle energies become so large that gravitational forces between them would become as strong as other fundamental forces according to current theories. I see, the gravitation would become a problem even before the speed.
- sp332 8y agoYou can't accelerate anything to the speed of light without an infinite amount of energy. It just takes more and more energy to get closer to that speed. https://en.wikipedia.org/wiki/Speed_of_light#/media/File:Lorentz_factor.svg https://en.wikipedia.org/wiki/Speed_of_light#/media/File:Lor...
- louisswiss 8y agoDoes that mean it doesn't take more energy to accelerate an electron to the speed of light than a tennis ball?
- Symmetry 8y agoIn the sense that if you multiple infinity by an arbitrarily large finite number you still have infinity, yes.
- badosu 8y agoNo hadron can achieve the speed of light. See: Ek=mc^2/√(1−(v/c)^2)−mc^2 For v<<c you have significant discrepancies on the energy required to accelerate to a specific speed with regard to mass. I.E. Newton: Ek=(mv^2)/2 As v->c it does not matter as much, the lorentz factor is much more significant, the mass operates just as a base multiplier and sum factor. As v->c, x->0 where Ek~1/x, i.e. tending to infinity with a division by zero when v=c. In conclusion, the speed is the relevant factor instead of mass when near speed of light, regardless of the object being an electron or the mount Everest. Of course, assuming the equation holds ;-)
- OscarCunningham 8y agoSee also: https://en.wikipedia.org/wiki/Negative_temperature https://en.wikipedia.org/wiki/Negative_temperature
- sampo 8y agoSo +0K is the lowest low, and -0K is the highest high.
- OscarCunningham 8y agoRight. In many contexts it makes more sense to use 1/T. Then there's no discontinuity and as things get hotter you decrease smoothly from positive, through 0, to negative.
- dTal 8y ago1/0 seems like a pretty major discontinuity.
- chowells 8y agoThere's no discontinuity at 0. It's a limit point that is unreachable, as far as we know. That's why 1/T is a better measure. It makes it obvious that +0k is the unreachable limit of "adding a quantum of energy results in an infinite increase in entropy". (-0k is the unreachable limit of "adding a quantum of energy results in an infinite decrease in entropy".)
- evincarofautumn 8y agoI remember when I first learned about absolute zero, ages ago, and thought “if it’s unreachable, it must be like an asymptote…but that would mean we’re measuring temperature ‘upside-down’…” Much later, I learned about that very thing (1/T, “thermodynamic beta”) while wikiwalking after hearing about the concept of negative temperature. Then I fell into a rabbit-hole wondering if we also measure speed upside-down in that way, since you can’t accelerate to light-speed. And indeed, when you’re talking about relativistic effects, units of time per distance can be more illustrative sometimes than our intuition of distance per time.
- Jun8 8y agoGood answer from Physics SE on why there's no upper limit to temperature: https://physics.stackexchange.com/questions/1775/why-is-there-no-absolute-maximum-temperature https://physics.stackexchange.com/questions/1775/why-is-ther...
- klodolph 8y agoWould also add to this that ideas about what "temperature" means change when you are switching between equilibrium and nonequilibrium thermodynamics. In nonequilibrium thermodynamics a bunch of your equations go out the window, like the Boltzmann distribution, and all of the rules built on top of that which are many.
- calhoun137 8y agoThis is an amazing video by vsauce called How Hot Can It Get and which deals with the same concepts. I very highly recommend it for everyone. https://youtu.be/4fuHzC9aTik https://youtu.be/4fuHzC9aTik
- teh_klev 8y agoThanks for that, I hadnt' bumped into that channel before. After watching this one I watched the one on how to count past infinity....mind suitably blown :) https://www.youtube.com/watch?v=SrU9YDoXE88 https://www.youtube.com/watch?v=SrU9YDoXE88
- wodenokoto 8y agoIf we are posting great V-sauce videos, "Which way is down" is the best explanation of the relationship between space-time and gravity I have come across. https://youtu.be/Xc4xYacTu-E https://youtu.be/Xc4xYacTu-E
- ssivark 8y agoOoh boy, quantum mechanics is fun :-) Think of the quantum vacuum as having a large number of degrees of freedom waiting to get excited by energy -- like a fleet of unused AWS instances in a system with very effective load balancing. The moment the load (roughly, energy) on the running instances (particle present in the system aka "quanta") increases beyond the threshold for creating a new one (aka rest mass of a new particle), a new instance is spontaneously created. Heating the system is akin to increasing the load on your system, and new instances will keep getting spun up. Is there a limit on how many such particle instances can be created? If we neglect gravity, no -- you can just keep adding instances/quanta and never run out. (and how much ever energy you dump in, the system's temperature will not increase beyond the Hagedorn limit [2]) But if you stop ignoring gravity, the gravitational attraction between the spun up instances will keep increasing as you spin up more of them, eventually forming a black hole at some point (because you cannot squeeze in more than a certain amount of information in a given volume [1]). This is roughly where you wave your hands and and come up with heuristic explanations using Planck length, Planck mass, etc. That's the limit of current understanding. Any refinement to this story would be a massive breakthrough! PS: A relatively sobering (nonetheless exciting) possibility is that much before gravitational effects become important, your "effective field theory" proves insufficient to model the system, and you are led to a "more fundamental" model. [1]: http://scholarpedia.org/article/Bekenstein-Hawking_entropy http://scholarpedia.org/article/Bekenstein-Hawking_entropy [2]: A technical explanation of the Hagedorn limit: At finite temperature, the occupation probability of states is exponentially decaying with energy (i.e. energy divided by temperature gives the log-probability) [3]. But, if the degeneracy of high-energy states grows exponentially, then that could entropically compensate for the exponential decay of the occupation probability, to have more occupation at higher energies than lower energies! The transition point in this tradeoff is the Hagedorn limit. That is why, additional energy is more likely to create new particles/states than simply increase the per-particle energy of the existing ones. [3]: https://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_statistics https://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_stat...
- deleted 8y ago[deleted]
- RichardCA 8y agoI have a really simple question. Has anyone ever done an experiment to confirm that SR comes into play at ultra-high temperatures?
- shaded-enmity 8y agoHmm, at school we were taught that the maximum temperature is such that wavelength of the emitted black-body radiation would equal Planck length, is this rationale no longer sound?
- InitialLastName 8y ago> maximum temperature is such that wavelength of the emitted black-body radiation would equal Planck length ... Also known as the Planck Temperature, which is the highest listed possibility for absolute hot in TFA.
- wnoise 8y agoIt was never sound. Black-body radiation describes the distribution of power emitted at given wavelengths or frequencies emitted by an ideal black body. 1. Distributions don't have one wavelength. There is a "peak" wavelength at which most power-per-wavelength is emitted, but there is still power emitted at all wavelengths no matter what temperature something is. 2. There is not sufficient reason to believe that the Planck length is a limit on the wavelength of light. This would break Lorentz symmetry. 3. Most things aren't ideal black bodies, but still have temperatures. Even if very hot objects couldn't emit light of Planck length, they can still couple to the environment and emit heat in other ways.
- nategri 8y agoIf you like this, you might enjoy: https://en.wikipedia.org/wiki/Negative_temperature https://en.wikipedia.org/wiki/Negative_temperature
- hinkley 8y agoWouldn't fusion trigger at much, much lower temperatures? We are talking about the theoretical limit of temperature, but what is the practical limit? There's a point beyond which heating hydrogen just gets you helium and more heat, but heating anything heavier than iron gets you something colder than the inputs.
- sigi45 8y agoIsn't fusion a reaction which has to happen? I would think that at that energy level there are no more elements which are able to form.
- deleted 8y ago[deleted]
- brailsafe 8y agoTLDR; It's Natalie Dormer.
- dang 8y agoPlease don't do this here.
- wnoise 8y agoUnfortunately, this a terrible name, concept, and even article. The vast majority of it is directly from a pop-science NOVA episode and not actually well-backed. There are reasonable bounds you can place on energy density where we expect current physical theories to stop making sense. But energy density is not the same as temperature. It is true that for things like ideal gases, temperature is roughly "energy per degree-of-freedom", which is an energy density of sorts, but that's not fundamentally what temperature is. Temperature is nothing more than a specific measure of how energy will flow due to entropic effects. In the right systems, this can be arbitrarily high without a high energy density. (In fact, elsewhere on this very post, people have pointed out "negative temperatures" where the temperatures become "hotter than infinity", they "wrap around" to negative.)
- snowwrestler 8y agoIf the temperature wraps around to negative, doesn't that imply a maximum value at the wrap point? Do we know the temperature value at which it wraps to negative? Is it literally "infinity Kelvin?"
- wnoise 8y agoYes, the wrap point is literally infinity, wrapping to negative infinity. https://en.wikipedia.org/wiki/Negative_temperature https://en.wikipedia.org/wiki/Negative_temperature is not terrible, for an overview, though the disclaimer is just annoying at this level. For thinking about this point, it's much easier to talk about "thermodynamic beta" (sometimes called "coolness" or "coldness") which is just 1/T = partial S/partial E. The behavior of a spin system that admits negative temperatures can be described smoothly in terms of beta -- hotter systems have beta that is lower, and zero is not particularly special. Now, any real system is coupled to the rest of the environment, so can't be in equilibrium at a negative temperature, as it would continuously leak heat until it cooled down enough to have some positive temperature. But if its internal equilibration proceeds much faster, then it's still useful to talk about its temperature as a quasi-equilibrium case.
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- kazinator 8y agoNote how T stands for temperature, so we can use the symbols NIL for absolute zero and T for absolute hot.
- mustardo 8y agoThis video is probably the best explanation https://www.youtube.com/watch?v=oHyctwgE6m4 https://www.youtube.com/watch?v=oHyctwgE6m4