I use a Fluke infrared temperature measurement meter for various applications.  I have not thought too much about the source of that infrared radiation until recently.  Assume some solid with maybe a crystal structure or not (such as a block of wood) -- I can measure the temperature via the infrared radiation given off by the object.  What is the source of this radiation?  I mean, is it one of (or all of) the following:   charge acceleration (such as charged particle changing direction, striking something, being struck by something). Photon given off by electron in atom changing energy levels. Some other kind of source unknown to me.   If item 3 is the answer, can someone explain.  Thanks.
By conservation of energy, the solid is left in a lower energy state following emission of a photon.  Clearly absorption and emission balance at thermal equilibrium, however, thermodynamic equilibrium is a statement of the mean behaviour of the system, not a statement that the internal energy is constant on arbitrarily short timescales.  The energy has to come from somewhere during emission, and go somewhere during absorption.  Energy in a solid can be stored as kinetic and potential energy of electrons and nuclei, either individually or in collective modes such as phonons and plasmons.  In thermal equilibrium energy will be stored more or less in various forms depending on the temperature and material.  However, even if most of the thermal energy in a particular solid at temperature $T$ is stored in the form of phonons, it could be that phonons primarily interact with light indirectly via electrons, e.g. a phonon excites an electron in a phonon-electron interaction, which can interact with light via the EM field.  Given that light is an EM field, it makes sense to me that it is emitted and absorbed by charged particles.  The electron-photon interaction is probably dominant for visible and ultraviolet light, given that metals are opaque, while semiconductors and insulators are transparent to (visible and UV) light with energy lower than their bandgap. However, once you get into energies in the IR and below, or X-rays and above, other mechanisms apparently take over.  For example, on the high-energy end of the spectrum I've heard that gamma rays can interact directly with nuclear degrees of freedom, which is reasonable considering that gamma rays are emitted during a lot of nuclear reactions.  A review of  might give clues to important light-matter interactions over a broad range of wavelengths.  Whether all of the these processes are involved in blackbody emission is a somewhat different question.  What physical processes mediate energy transfer during blackbody emission, and in which energy ranges are the various processes dominant?
Short circuit or disconnect to bypass a compressor I have an Altec Lansing ATP3 2.1 audio system PCB which I reverse-engineered, and I would like to bypass the JFET compressor that's on it. Its active components are a JFET and four op-amps. I will connect the input to the output so it gets forwarded to the next stage.  My question is: should I disconnect the input and output from the compressor (in that case should I remove power supply as well, which would be very annoying), or can I leave it connected but short-circuited?  The block I want to short-circuit is the pink one on the left.    I realize the image is very small. The sound comes in on the right, in the green box. In the middle yellow box there's some trebble/volume/bass control. The small green box on its left merges the left and right channels to forward it to the subwoofer section, which is the complete left half of this diagram (except the red box on the left, which is just power). Signal then goes through a low-pass, a small equalizer and a compressor (the big purple box). It finally gets amplified in the brown power amp. How do you create a dropdownlist from an enum in ASP.NET MVC? I'm trying to use the Html.DropDownList extension method but can't figure out how to use it with an enumeration.  Let's say I have an enumeration like this:  public enum ItemTypes {     Movie = 1,     Game = 2,     Book = 3 }   How do I go about creating a dropdown with these values using the Html.DropDownList extension method?  Or is my best bet to simply create a for loop and create the Html elements manually? Entering and leaving the UK on the day of visa expiry share login/logout sessions across two installs? ! LaTeX Error: Undefined color `BLACK' i have written all the text in black color, but i get this error several times in the same page:  ! LaTeX Error: Undefined color `BLACK'.   i tried to solve it by writting this: \definecolor{black}{gray}{0,0,0} but it didn´t work.   what should i do? I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents: Access images inside jar converge and converge absolutely of a series $f(x)$ is a continuos fuction in $[0, 1]$ and differentiable twice on $0$.  $U_n=(-1)^{n}f(\frac{1}{n})$. I need to prove that:   $1.$if $\sum_{n=1}^\infty U_n$ converge then $f(0)=0$.  $2.$if $f(0)=f'(0)=0$ then $\sum_{n=1}^\infty U_n$ converge absolutely.  Now, from the detail that $f(x)$ is differentiable twice on $0$ I think I need to write $f(1/n)$ with Maclaurin series with 2 degree but it doesn't work very nice. can you guide me please? thanks! How permanent magnets work?Are they working with motion of electrons? I have being using Skype for a long time on my Ubuntu 14.04 LTS. From this morning on, Skype simple cannot connect to my account anymore.  That is my Skype version:     Skype 4.3.0.37   © 2014 Skype and/or Microsoft   My Ubuntu system:  LSB Version:    core-2.0-amd64:core-2.0-noarch:core-3.0-amd64:core-3.0-noarch:core-3.1-amd64:core-3.1-noarch:core-3.2-amd64:core-3.2-noarch:core-4.0-amd64:core-4.0-noarch:core-4.1-amd64:core-4.1-noarch:cxx-3.0-amd64:cxx-3.0-noarch:cxx-3.1-amd64:cxx-3.1-noarch:cxx-3.2-amd64:cxx-3.2-noarch:cxx-4.0-amd64:cxx-4.0-noarch:cxx-4.1-amd64:cxx-4.1-noarch:desktop-3.1-amd64:desktop-3.1-noarch:desktop-3.2-amd64:desktop-3.2-noarch:desktop-4.0-amd64:desktop-4.0-noarch:desktop-4.1-amd64:desktop-4.1-noarch:graphics-2.0-amd64:graphics-2.0-noarch:graphics-3.0-amd64:graphics-3.0-noarch:graphics-3.1-amd64:graphics-3.1-noarch:graphics-3.2-amd64:graphics-3.2-noarch:graphics-4.0-amd64:graphics-4.0-noarch:graphics-4.1-amd64:graphics-4.1-noarch:languages-3.2-amd64:languages-3.2-noarch:languages-4.0-amd64:languages-4.0-noarch:languages-4.1-amd64:languages-4.1-noarch:multimedia-3.2-amd64:multimedia-3.2-noarch:multimedia-4.0-amd64:multimedia-4.0-noarch:multimedia-4.1-amd64:multimedia-4.1-noarch:printing-3.2-amd64:printing-3.2-noarch:printing-4.0-amd64:printing-4.0-noarch:printing-4.1-amd64:printing-4.1-noarch:qt4-3.1-amd64:qt4-3.1-noarch:security-4.0-amd64:security-4.0-noarch:security-4.1-amd64:security-4.1-noarch Distributor ID: Ubuntu Description:    Ubuntu 14.04.3 LTS Release:    14.04 Codename:   trusty   Any suggestion why or how to fix it?  Thanks in advance. Layover in Europe to the US - allowed? Many people have asked questions on this site regarding the rules for layovers, with no definitive answers. The rules are constantly in flux and it is very difficult to get a clear answer from government websites. I would like to buy a plane ticket for my mother-in-law (who has a visa) from Ukraine to the US. Most available flights have at least one layover in Europe. My understanding is that EU countries (minus some special cases and US citizens) are currently banned from travel to the US. If we buy a ticket with a layover in, say, Switzerland, can there be a problem? Is this allowed under current rules? Can anyone please help and tell me if this sentence is correct?  &quot;A significant amount of zombies were detected in your city.&quot;  In my opinion it should be &quot;A significant amount of zombies was detected in your city.&quot; because &quot;amount&quot; should be in agreement with &quot;was&quot; even though amount usually refers to something plural. Are both (was and were) acceptable in this case? Edit1: Yes, &quot;number&quot; would be the correct one in this case. So allow me to ask one more thing.  &quot;A significant amount of purchases were detected...&quot;  Does the use of &quot;number&quot; apply in this case also? As purchase is not exactly a thing/person. And if no, is it correct to say &quot;A significant amount of purchases were detected...&quot;? Edit2: So, please tell me what is the correct phrasing?  &quot;A significant amount of purchases were detected...&quot; &quot;A significant amount of purchases was detected...&quot;  Or, since purchases are countable, is the use of &quot;number&quot; instead of &quot;amount&quot; correct here, as in:  &quot;A significant number of purchases were detected...&quot; &quot;A significant number of purchases was detected...&quot;  Or would amount be correct since a purchase involves money and it refers to the amount of money? Would greatly appreciate an answer, and if possible a detailed explanation. Blender 2.79b is installed (from .exe) on my computer, currently. And I just downloaded the Blender 2.8 release candidate 2 (.zip).  When I create something in Blender 2.8, after I save it, I cannot open it again because the computer tries to open the blend file in version 2.79b. And manually selecting the 2.8 version from zip file does not work.  How can I open my blender 2.8 files? Do I have to delete Blender 2.79b? Why was Hagrid's wand snapped in two when he was expelled from Hogwarts? Why was he banned from performing magic? Yes, he was expelled from Hogwarts after being framed by Tom Riddle as being responsible for Moaning Myrtle's death via Aragog the Acromantula. But why did he receive this punishment?  ‘What’ve you been feeding [the pumpkins]?’ said Harry. Hagrid looked over his shoulder to check that they were alone. ‘Well, I’ve bin givin’ them – you know – a bit o’ help.’ Harry noticed Hagrid’s flowery pink umbrella leaning against the back wall of the cabin. Harry had had reason to believe before now that this umbrella was not all it looked; in fact, he had the strong impression that Hagrid’s old school wand was concealed inside it. Hagrid wasn’t supposed to use magic. He had been expelled from Hogwarts in his third year[...] Chamber of Secrets - page 90 - Bloomsbury - chapter 7, Mudbloods and Murmurs  Why would Hagrid's wand be snapped in two and he not be allowed to do magic when:  Attendance and completion of an education at Hogwarts was not compulsory by wizarding law¹; homeschooled children were allowed to do magic for their lessons, and then do magic fully when they turned 17. The Weasley twins dropped out of Hogwarts after practically destroying parts of the castle with fireworks (and conjuring an awesome swamp on the fifth floor), yet were allowed to do magic despite not completing Hogwarts or any kind of homeschooling curriculum (that we know of). No Death Eater character that we know of was banned from using magic, despite their crimes and devotion to Voldemort. I don't recall any Death Eater wands being snapped and the owner banned from performing magic after being convicted of Death Eater crimes (please do correct me if I'm wrong). For example, Bellatrix Lestrange's wand was not snapped in Goblet of Fire when she received a life sentence in Azkaban and, as we know, her wand played a fairly significant part in Deathly Hallows.  ¹I realize in Deathly Hallows Voldemort made attendance at Hogwarts compulsory; however, by that time, Hagrid had been cleared of the charges of being responsible for Myrtle's death and was allowed to use magic again. Let $f$ be increasing on $[a,b]$ and $a < x_1 < \dotsb < x_n < b$. Show that $\sum_{k = 1}^n [f(x_k^+) - f(x_k^-)]\leq f(b^-) - f(a^+)$. Is it possible to downgrade an OEM Windows 8 install to Windows 7? I recently purchased an ASUS K55A. Like all Windows 8 machines, it come with a UEFI feature called Secure Boot. This basically makes sure that the laptop won't load anything other than the Windows 8 OEM version that came with it.  However the Asus UEFI allows for me to disable Secure Boot, and therefore I should be able to revert to Windows 7, Linux, etc. (drivers may or may not be supported). When I insert my Linux Mint boot disc and try to boot from it, though, nothing happens. There isn't even a boot priority list in the UEFI settings (I can provide screenshots later). It just says "Windows 8 Bootloader" and also on the other tab it says "WINDOWS 8 BOOT OVERRIDE".  Has anybody purchased a Windows 8 machine and successfully installed Windows 7 or Linux on it? Often floats may land quite a bit later in the document than the point they are created, sometimes after a section break.  Is there a way to force a new section to start on a new page, after any unplaced floats? In Days Of Future Past, Quicksilver spends a lot of time playing with electronics.  In his famous tour de force scene in the Pentagon, he specifically puts his headphones on before running around the kitchen.  But why?  Does the music on his Walkman speed up with him as he uses it, or is it still operating at "normal" speed? Or indeed, does any electronic device that he touches speed up? What are all the correct answers to the Squirrel's questions, and what is the reward when I get them all correct? I encountered The Squirrel at "A tree."              |   |                                                                         |   |                     "   Hello, I'm The                        |             |                        Squirrel. I can                        |             |                      provide you candies,                     |             |                      and lots of things.                                    |                      I know how much you                                    |        _.-'''-,      love candies. But I                                    |      .'        `\     feel alone in this                                    |     /           /          forest.       "                         |        |    /      .--^_^                                                   |        |    |     /  C ,,\                                                           |    |    |   \  _.)                           ___                            |     \   |   /  \                   ____.----'.-'                            |      '-, \./ \)\)               .-' --  __.-'                   |            \        `-/   );/           ___/  - _.-'                        |             \_________''--'-'________.-' --    /                            |              -   --        -  -     -     __.-'                                              -    --    -     --   --  /                                                 _________________________.-'                                 He asks you some questions. What are the correct answers, and what is the reward for getting them correct? If every ideal is principal show the same is true for the image of a homomorphism.