Quantization in Black Body Radiation Why does energy need to be quantized to explain black body radiation? Wouldn't the approximate normal distribution of the kinetic energy of particles at a certain temperature be sufficient, ie. few particles have high enough energy to oscillate at higher frequencies.
How can blackbody radition be explained by quantization? I don't understand why quantization makes a peak on the blackbody radiation curve (so there is no ) and the relationship between that peak and quantization concept.  When the blackbody is heated, it starts to glow. All atoms start to vibrate. Total heating energy must be divided and equally shared by all atoms of blackbody. Right?  But what happens next?  Do some atoms get much more energy to radiate at higher frequency and waste the energy? What happens at the atomic level, so quantization can explain it? What does classical physics claim, so it can not explain the radiation curve?
If just a single photon hit a single slit interferometer, what would happen? Would you just see a dot on the screen, or would there be a diffraction pattern? Furthermore, if you had a double slit interferometer but also had which-path information would there still be a diffraction pattern even though there is no interference? Using nohup to keep a script running indefinitely I am very new to Linux and I've only been using it to SSH to my web server using Putty. The issue I am having is this:  Basically I've got 2 php scripts. One get_tweets.php constantly listens for tweets on twitters Streaming API whilst the other - parse_tweets.php logs these into a db. In order for these to work they've to be kept running continuously.   I've been using the following commands to run them in the background and from what I've seen they run for most of the day, however whenever I log on to my computer in the morning the scripts have stopped and I've to run commands again.  nohup php my_script.php &gt; /dev/null &amp;   I'm just wondering if that is normal based on the commands I am using, should they run indefinitely when using nohup and if not what is the alternative? A CRON job?  Thanks for the help What does the human body use oxygen for besides the final electron acceptor in the electron transport chain? My biology teachers never explained why animals need to breathe oxygen, just that we organisms die if we don't get oxygen for too long. Maybe one of them happened to mention that its used to make ATP. Now in my AP Biology class we finally learned the specifics of how oxygen is used in the  due to its high electronegativity. But I assume this probably isn't the only reason we need oxygen.   What other purposes does the oxygen we take in through respiration serve? Does oxygen deprivation result in death just due to the halting of ATP production, or is there some other reason as well? What percentage of the oxygen we take in through respiration is expelled later through the breath as carbon dioxide? What defines the maximum size for a command single argument? I was under the impression that the maximum length of a single argument was not the problem here so much as the total size of the overall argument array plus the size of the environment, which is limited to ARG_MAX. Thus I thought that something like the following would succeed:  env_size=$(cat /proc/$$/environ | wc -c) (( arg_size = $(getconf ARG_MAX) - $env_size - 100 )) /bin/echo $(tr -dc [:alnum:] &lt;/dev/urandom | head -c $arg_size) &gt;/dev/null   With the - 100 being more than enough to account for the difference between the size of the environment in the shell and the echo process. Instead I got the error:  bash: /bin/echo: Argument list too long   After playing around for a while, I found that the maximum  was a full hex order of magnitude smaller:  /bin/echo \   $(tr -dc [:alnum:] &lt;/dev/urandom | head -c $(($(getconf ARG_MAX)/16-1))) \   &gt;/dev/null   When the minus one is removed, the error returns. Seemingly the maximum for a single argument is actually ARG_MAX/16 and the -1 accounts for the null byte placed at the end of the string in the argument array.  Another issue is that when the argument is repeated, the total size of the argument array can be closer to ARG_MAX, but still not quite there:  args=( $(tr -dc [:alnum:] &lt;/dev/urandom | head -c $(($(getconf ARG_MAX)/16-1))) ) for x in {1..14}; do   args+=( ${args[0]} ) done  /bin/echo "${args[@]}" "${args[0]:6534}" &gt;/dev/null   Using "${args[0]:6533}" here makes the last argument 1 byte longer and gives the Argument list too long error. This difference is unlikely to be accounted for by the size of the environment given:  $ cat /proc/$$/environ | wc -c 1045   Questions:   Is this correct behaviour, or is there a bug somewhere? If not, is this behaviour documented anywhere? Is there another parameter which defines the maximum for a single argument? Is this behaviour limited to Linux (or even particular versions of such)? What accounts for the additional ~5KB discrepancy between the actual maximum size of the argument array plus the approximate size of the environment and ARG_MAX?   Additional info:  uname -a Linux graeme-rock 3.13-1-amd64 #1 SMP Debian 3.13.5-1 (2014-03-04) x86_64 GNU/Linux I'm using a PIN code to log on my computer. However, Num ⇩ is always turned off, even if on before shutting down my computer. This is quite annoying as I always have to retype my PIN.  I've tried the suggestions  (same as ). But with no result. If I don't enable num lock on log in screen and use the numbers above the normal keys, num lock turns on after log on. Then it's too late, unfortunately.  So, how can I make num lock enabled by default when logging in? Thanks.  Edit: While I still want to solve this, I've figured it is not such a big problem. I will need to press some key for the "enter PIN screen" to show, and using Num ⇩ works and enables num lock. But then, still annoying if the computer was only locked (with num lock on) and I turn it off, hehe. Intuition on the Kullback–Leibler (KL) Divergence I have learned about the intuition behind the KL Divergence as how much a model distribution function differs from the theoretical/true distribution of the data. The source I am reading goes on to say that the intuitive understanding of 'distance' between these two distributions is helpful, but should not be taken literally because for two distributions $P$ and $Q$, the KL Divergence is not symmetric in $P$ and $Q$.   I am not sure how to understand the last statement, or is this where the intuition of 'distance' breaks down?   I would appreciate a simple, but insightful example. What potions actually grant fame or glory, or put a stopper in death? Are there any? ‘You are here to learn the subtle science and exact art of potionmaking,’ [Snape] began. He spoke in barely more than a whisper, but they caught every word – like Professor McGonagall, Snape had the gift of keeping a class silent without effort. ‘As there is little foolish wand-waving here, many of you will hardly believe this is magic. I don’t expect you will really understand the beauty of the softly simmering cauldron with its shimmering fumes, the delicate power of liquids that creep through human veins, bewitching the mind, ensnaring the senses ... I can teach you how to bottle fame, brew glory, even stopper death – if you aren’t as big a bunch of dunderheads as I usually have to teach.’&#185;   Philosopher's Stone - page 102 - Bloomsbury - chapter 8, The Potions Master   Are there any canon potions that actually grant fame or glory, or stopper death? I'm looking for specific canon-based answers from sources such as the Harry Potter books, interviews with J.K. Rowling, or information from Pottermore. Maybe because it's early I'm overlooking the obvious, but offhand I can't think of any canon potions that fit this criteria exactly.   &#185;I edited in the entire paragraph that I can teach you how to bottle fame, brew glory, even stopper death comes from for clarity. Hopefully this will be helpful and provide a better context for the comment in question. Notice these sentences:   Shops are open late in summer.   Summer is a traditionally viewed as a slow season for games.   At the summer solstice, the days are longest and the nights are shortest.   it's time to start thinking about what 2016's Song of the Summer will be.    In English class, they told us that "the" is used for the things that are known.  One example for this was a phrase like "The man who killed his wife".  So when we are speaking of that man, we know what he did. Somehow we know something more than nothing about him. He's not just every man in the world.     So Now I'm confused about why "the" is not used in the first and second sentences. Can anyone please explain it for me? reports:  Two mathematicians have uncovered a simple, previously unnoticed property of prime numbers [...]. Prime numbers, it seems, have decided preferences about the final digits of the primes that immediately follow them. Among the first billion prime numbers, for instance, a prime ending in 9 is almost 65 percent more likely to be followed by a prime ending in 1 than another prime ending in 9.  Do these insights make breaking keys based on primes more mathematically plausible in a shorter amount of time? I would like to solve the beginner's standard exercise which claims that a point of $\mathrm{Spec} \ R$ is closed iff it is a maximal ideal.  The reverse implication is easy. The direct one seems much subtler. If $P = V(I)$ then, since there exist a maximal ideal $M$ containing $P$, it would follow that $\{P, M\} \subseteq V(I) = P$, whence $P=M$. In order to show the existence of $M$ I applied Zorn's lemma to the set of ideals containing $P$.  The question is the following: is there any other proof of the above implication that does not (indirectly) use the axiom of choice? My concern is that I may be using a cannon to shoot a fly. Also, it would be the first time that I see closedness of points to require the axiom of choice. If the axiom is indeed needed in general, are there "nice" classes of rings for which we could get away without it? Getting absolute path of a file Using media queries in Lightning component Does 10 heads in a row increase the chance of the next toss being a tail? I assume the following is true: assuming a fair coin, getting 10 heads in a row whilst tossing a coin does not increase the chance of the next coin toss being a tail, no matter what amount of probability and/or statistical jargon is tossed around (excuse the puns).   Assuming that is the case, my question is this: how the hell do I convince someone that is the case?   They are smart and educated but seem determined not to consider that I might be in the right on this (argument). How to remove warnings like `Unknown media type ...` What do I know, when deciding whether to cast Counterspell? I'm not entirely clear on how Counterspell works, when trying to counter higher-level spells: the CS description only talks about disrupting a creature you can see, within 60 feet, casting a spell.   However, when trying to counter a higher level spell:   Do I know what spell is being cast?  Do I at least know (somehow intuit, based on VSM components) the level of the spell? Or can I tell the spell/level of the spell by sensing a disturbance in The Weave? (I.e., if the spell is being cast using Subtle Spell, can I still tell what's going on?)   The point of the question is to determine how fruitful CS can be in combat--if I know what the other guy/gal is casting (or at least the level), I can decide whether I want to spend my L8 slot to counter his/her L8 slot. But if I have no idea, and I end up using a L8 slot to counter a L3 spell... seems a bit painful.  Hope this made sense! Store pictures as files or in the database for a web app? My question is fairly generic and I know there might not be an 100% answer to it. I'm building an ASP .NET web solution that will include a lot of pictures and hopefully a fair amount of traffic. I do really want to achieve performance.  Should I save the pictures in the Database or on the File system? And regardless the answer I'm more interested in why choosing a specific way.  Many thanks, Stefan   DUPLICATE: , ,  and probably some others.    COMMENT: Thanks for many good answers. I will go for a file based solution even if I like the idea of having a 100% database driven solution. It seems that there are today good solutions to do what I want with databases etc but I have a few reasons for not doing it.   I will be on a hosted solution, I have huge amount of storage(10gb) but only 300mb for the database. It will cost a lot for extra storage in the DB. I'm not an DB expert and as well not in control of settings of the DB. A DB based solution might need custom configuration as it looks like.   If we will move to run the site on our own server I might consider a DB based solution. thanks, Stefan How can I automatically center an image? I use:  \documentclss{mwrep} ... \begin{figure}   \includegraphics{a.jpg} \caption[Long caption]{Caption} \label{pic-a} \end{figure}   How can I make images to be always visible on the center of page? (To be more specific: the center of the image should be between the left and right margin - I use different left and right margins). I don't want to put anything after every \begin{figure} in my document.  Important: I don't want to waste an entire page on a single image at the very center of the page. I want only horizontal alignment. (left &lt;-> right) How do I take great HDR photos of moving objects? By moving objects, I mean cities with cars, ocean with moving water, malls with people moving by.  I tried it on moving people and had noticeable ghosting, using bracketed shots at + and - 2ev.  What's the basic technique on getting sharp looking HDR photos in areas that are moving? I'm assuming it's not bracketed shots but a single shot with exposure editing? Connect Java to a MySQL database I want to utilize beamer's \uncover command within ChemFig's reaction scheme environment, i.e.:  \schemestart     \chemname[-1ex]{\chemfig[][scale=1]{*5(-=(-=[:-60]O)-O-=)}}{Furfural}     \uncover&lt;2-&gt;{         \arrow(furfural--mf){-&gt;[*{0}HDO][]}         \chemname[-1ex]{\chemfig{*5(-=(-)-O-=)}}{2-Methylfuran}     } \schemestop   However, this results in numerous "undefined control sequence" errors.  Is there a way to use beamer's \uncover command within ChemFig?  Here is a full MWE:  \documentclass[10pt]{beamer} \usepackage{chemfig}  \begin{document}  \begin{frame} \frametitle{Stuff}  \schemestart     \chemname[0ex]{\chemfig[][scale=1]{*5(-=(-=[:-60]O)-O-=)}}{Furfural}     \uncover&lt;2-&gt;{         \arrow(furfural--mf){-&gt;[*{0}\textbf{HDO}][]}         \chemname[0ex]{\chemfig{*5(-=(-)-O-=)}}{2-Methylfuran}     } \schemestop  \end{frame}  \end{document}