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• Are you aware that you are currently wearing underwear? Until I asked that, you probably forgot… or at least you weren't consciously thinking about it. Why weren't you consciously thinking about it? Well, there's a lot going on in the world and your brain tends to muffle things that aren't important. In general, things that don't change probably aren't important. So when you repeat a word over and over and over and over and over and over again, your brain gets desensitized to it. Your brain starts to muffle that word because it follows the pattern of something that isn't important. This is called semantic satiation.

• It's the opposite of deja vu, jamais vu. Basically its been said to the brain so many times it ignores it and the signal that normal tells you 'I know that word it's “Welcome” ' turns off and then leaves you stumped as to why you have written such a weird foreign word.

• Radio waves have two features that make it possible to carry information. One is the amplitude or “power” of the wave - you can thing of this as how “big” the wave is. The other is the frequency of the wave - you can think of this as how fast the wave goes up and down. When you send a signal with a transmitting radio, the circuits can control the amplitude and frequency of the wave - the power and up-down speed. In the same way, the circuits in the receiving radio can also detect that information. By changing the amplitude to be slightly larger or smaller over time, you can send information such as “big, small small, big big, small, big big big”. The circuits in the radio can use this like a code to translate between sounds or images and radio signals. By making the changes and translation very very fast, we can have live radio broadcasts. This is called “Amplification Modulation” or A.M. radio. Alternatively, you can do the same thing by changing the frequency of the wave slightly between faster and slower, to send the same kind of information. This is “Frequency Modulation” or F.M. radio. There are some advantages and disadvantages to both styles, which I'm not totally familiar with. When you turn on your radio, you can choose between listening to A.M. or F.M. usually. Then, you must pick a frequency to listen to, such as 93.1 (this is a specific number referring to the speed of the waves. I don't remember the units used). That tells your radio to only pay attention to waves that are at or very very close to that frequency. Then, your radio starts translating the waves and gives you sound!

• AM propagates better mostly due to the frequency band and it will bounce off the ionosphere to achieve very long ranges. FM requires more power and has shorter range but can have a better sound quality because of this.

My understanding is that the first stars were formed by large balls of dust that were gravitationally attracted to themselves in such a way that caused the dust to spin around until stars were formed. If entropy always increases, how did the dust become ordered in such a way to create stars?

• Imagine you're on the beach and want to build a sandcastle. The sand is scattered all over the beach. It is completely unlike a sandcastle. It's a mess. Mess is what scientists call “entropy”. More mess, more entropy. Some of the sand is smooth where the tide (which is going out) has washed over it. The entropy there is lower because the sand is less messy. You dig up some of this damp sand because it will make a nice solid castle that won't crumble. Having finished your castle, you stand back and admire it. The sand in your castle is very neat and tidy, so it has lower entropy than the rest of the beach. But the sand you dug up has left a big disorderly hole, so entropy has gone up there. The amount of mess added by the hole is greater than the amount of order added by your castle, because the hole adds more mess than the castle takes away. Similarly, the creation of a star makes that part of space nice and tidy, but makes the overall messiness of the universe higher than it was before the star was there.

• If entropy always increases, herein lies the problem. The total entropy increases, but it is able to decrease locally. This means stars can form. However, while that entropy decreases locally, the total entropy will have increased because entropy adds up logarithmically, not linearly; from Wikipedia: “…[the] entropy [of a system is defined as being] proportional to the logarithm of the number of possible microscopic configurations of the individual atoms and molecules of the system…”.

• Reality exists as an objective absolute—facts are facts, independent of man's feelings, wishes, hopes or fears.
• Reason (the faculty which identifies and integrates the material provided by man's senses) is man's only means of perceiving reality, his only source of knowledge, his only guide to action, and his basic means of survival.
• Man—every man—is an end in himself, not the means to the ends of others. He must exist for his own sake, neither sacrificing himself to others nor sacrificing others to himself. The pursuit of his own rational self-interest and of his own happiness is the highest moral purpose of his life.

• Imagine there was a 10,000 year long party in philosophy. In this party, you could freely speculate about what it meant to be a human being. We have lots of great (and, incidentally, still useful) insights from people like Buddha, Socrates, Homer, the writer of Gilgamesh, Aristotle, Aquinas, Spinoza, Maimonides, and many many many more. Then, along comes Darwin, who more or less proves that the purpose of man is to make more of himself. That's it. So, the simple case of “the purpose of man” was solved scientifically. Worse, it was solved in a way that certainly precludes an inherent lofty position for humans, at least in a biological sense, and (I think by most interpretations) likely in a divine sense. At this point, the party's over. But, nobody's happy about it. So, what do we do to get the party started again? We decide that it doesn't matter what has been the purpose of man in the scientific sense. However humanity came to be, our qualities give us the ability to define and redefine ourselves. There are many takes on this idea, both pedestrian and radical, but the thread that I find useful is this: Maybe there is no “meaning” to humanity. But, maybe the original question was just badly formulated, and so you shouldn't feel sad. Evolution has endowed you with the ability to feel happy, reverent, loving, and awed. The universe may be big and cold, but you're small and warm. And, after all, that's not so bad.
• The idea behind “existence precedes essence” is that Sartre derives two categories for consciousness. One on level, you have something like a chair, in which essence precedes existence because we need a model designed prior to our actually having built the chair. This is what Sartre called the “in-itself.” On the other hand, Sartre used the “for-itself” to denote dynamic human consciousness where the fundamental derivative was “nothingness.” Consciousness is random and projected into experience but fundamentally, there is no basis for the consciousness that I am outside of my experience. The for-itself has mobility and can change, it can grow, learn whereas the chair cannot, which is where the distinction comes from. A pretty ingenious but important critique of existentialism should also be made - and this is why I've always liked Charles Taylor. Taylor criticized Sartre's idea of radical freedom because he argued that this completely conceptually “free” and “limitless” existence didn't exist contextually or practically. All of us, despite realizing our ultimate freedom, make choices within the confines of our contextual web of existence (Heidegger's “web of significance”) and thus, the idea of radical freedom becomes somewhat incomprehensible. I have this whole string of affairs tied to my life - my job, my relationships, my family - and so despite waking up and realizing that my life has no purpose, I'm filling it with this contextual purpose that I've built. So to destroy that for something like “radical freedom” doesn't make sense because all of my choices in my life are presented to me against the background of the life I've built for myself with the freedom I've already been given. In other words, I make all my choices in context, considering the things that compose that background. I can't just jump outside that context to explore radical freedom as if those things weren't linked to the way I define or make choices for myself. This is why most people can realize their freedom but fail to capitalize.

This is going to be one of those “it depends” answers, because of the sheer wealth of classical music. It's been a while since I've done music theory, but I would like to share what I know, and if anyone can fill in the gaps or correct me, get right in there!

Three of your questions can be explained together; the only one I can't give anything on is the question: are composers flanked by underwriter musicians who don't seem to get credit for their role? I'll have to pass on that. When it comes to composing a piece for an orchestra, you decide what instruments you want. This is as true for Bach as it is for Beethoven as it is for Hans Zimmer. The differences in their setup are from their respective philosophies of music, and also because the orchestra constantly developed and grew, in no small part due to new instruments being invented and incorporated. The cor anglais, for example, was developed around 1720, making it impossible for it to appear in any baroque piece. In this way, you don't have to take a tally of who will show up; you decide from the outset what instruments you want, and modern conventions will help decide how much of one section is used.

So, you have a musical idea, and you've decided how big you want your orchestra to be. Not every composer would know every instrument inside out; I don't think there are many who could play a multitude of instruments. What they would know, is how each instrument sounds (its timbre), and what their comfortable note range is (its tessitura). They would also know what sounds well together. Strings and winds such as flutes are quite nice, for example. You wouldn't want to strain a flute player to screech out a note they can barely reach, in the same way you don't want to strain a soprano's voice by forcing them to go higher and higher. It sounds bad and it damages the instrument. As for composition, there are a couple of ways to go about it, and this is the “it depends” territory. Firstly, you don't need to write out five different violin parts of varying complexity if you don't want to. More often than not, if you take a gander at an orchestral score, String Instruments are grouped as follows:

• First Violins
• Second Violins
• Violas
• Cellos
• Contrabass

Note that each term is plural. You don't write out each and every violin player, just their designation. Chances are if you were to write five different violin parts with complexity, they become special enough to warrant their own section and focus, making the piece more of a concerto or a concerto grosso. I do admit that if you wanted really subtle harmonies and melodies, then yeah! Add in Third, Fourth, and Fifth Violins, and have them interacting. Be prepared for it to be washed away from the rest of the orchestra, though.

Also note that a violin can only bow, I think, two notes reasonably at one time. In most orchestral scores, they only play one, so if you wanted a minor third, (D and F), then get the first violins to play the F, and the second violins to play the D. That's how you split up harmony in orchestras. What's great is that you can double up the voices: so we have the First and Second Violins doing a sweet-ass minor third with D and F. Now let's add some colour and have a Soprano singer on a high D, and an Alto singer on the F below it. Same notes, and yet you're being attentive to what each instrument is capable of. A great example of composing for an orchestra is shown in the film Amadeus, where Mozart has to explain to Salieri what is going on in the Confutatis in his Requiem.

Again, you are the one in control. You don't need to take a tally, nor make an all-purpose piece. The more you listen to pieces, and get used to how each instrument sounds and what they are capable of (flutes being suited to melodies, and brass instruments being well suited to harmony, for example) will go a long way to structuring an orchestral piece. Winds and Strings can copy one another, and their setup is similar:

• Flutes
• Clarinet
• Oboe
• Bassoon

Similarly, for choir voices:

• Soprano
• Alto
• Tenor
• Bass

This setup for tonal range and splitting up the voices (Sopranos and Altos, Flutes and Clarinets, and First and Second Violins being the top half, with Tenors and Basses, Oboes and Bassoons, and Cellos and Contrabasses being the bottom half) is known as SATB format. String quartets do the same thing [First Violin, Second Violin, Viola, Cello].

In this way, you cheat. Compose for one section, then copy it over for the others, if you want a big all-together-now! part. The fun happens when you get the different sections interacting, creating a great interplay. An example I can give is Beethoven's 5th Symphony First Movement, which neatly shows winds and strings playing separately, and using brass for added “oomph”.

Well if we are talking non professionals (so College (though many top band colleges are pretty close to professional) on down), the reason is because the conductor helps them rehearse and does help them keep in time and things like that.

But for professionals, you are right. The musicians ARE really really good. They know their parts, and generally the “rehearsal” is playing through the song once before the performance, then the performance. With the understanding that each person knows their part perfectly, and they do. You will notice that in lower level bands, like in high school, the conductor is keeping a steady beat a lot. This is to help the players. But you will notice in professional levels many times it seems like the conductor isn't keeping the beat really at all… this is because the musicians don't really need help with keeping the beat anymore because they are quite good.

Now what does he do? Well think of it this way. Get 20 people together and have them close their eyes. Now everybody clap at the same beat together. It will be pretty easy to do that. Now have them slow down at the same pace together… not too easy at all. “How slow are we going down to? How fast do we slow down?” All these things people have difficulty doing without any sort of cue. That is where a conductor comes in.

Or another thing a conductor helps with is emotive expression. Playing a single instrument in a band doesn't actually give you a good representation of what the band sounds like to the audience. If you are a clarinet, for example, you can hear the clarinets REALLY well, the flutes pretty well, and the brass sitting behind you will be particularly loud. It can be difficult hearing the trombones though on the other side or something like that. While good players do know how to balance and how to listen, it helps having the conductor signal “more, more!” or “back off a little” since he is hearing everybody.

He also cues different sections which is helpful for placement issues, as well as when you get into mixed meters such as 9/8 where it can be broken up as 2+3+2+2 and the next bar be 3+2+2+2 and keep switching around. In cases like that it is helpful having somebody denoting where the emphases are.

And then there are cues that come down to the conductor. The conductor decides when a certain instrument comes in. For example the brass section is holding a long note, and then the conductor decides the flutes to come in, and then the clarinets. The conductor also decides how long pauses last and whatnot. Where it is difficult to do with a large band.

You will notice small chamber groups (like 4 members) don't need a conductor, but that doesn't mean they aren't synchronizing. They are constantly watching each other for the beat, and many times the lead of the group will be the one to signal cut offs and starts by their body movement, so still acting as a “conductor”, but it is hard for somebody in the 5th row to see somebody sitting in the 1st row for these cues, which is why the conductor is at the top.

• General Relativity says space-time is curved,
• each object with mass distorts space-time,
• photons have no mass, but still follow the geometry of curved space-time, so its path is distorted.

Temperature can rise arbitrarily high in many systems (ex: quantum harmonic oscillator). However, in certain systems with a finite number of possible states, the temperature can become negative (ex: two state system with population inversion). This negative temperature is effectively higher than infinite temperature.

In order for the temperature to return to a positive temperature, as long as the object at negative temperature is kept in a heat sink, the absolute value of the temperature will keep going up, until it reaches negative infinity. Then, since negative infinity Kelvin is the same as positive infinity Kelvin, the temperature starts dropping from there. This has to be true, since the third law of thermodynamics essentially states that nothing can ever be at zero kelvin.

SOURCE: http://www.reddit.com/r/Physics/comments/15pcjb/absolute_zero_is_the_lowest_possible_temperature/

Occam's razor says that all else being equal—that is, if all the other conditions stay the same, and if the explanations are equally good in all other ways—more parsimonious explanations are more likely to be right. And this makes perfect sense: every bit you add onto your explanation can only make the odds of it being true go down, not up—just like the odds of rolling three 6s in a row on a die is lower than the odds of rolling two 6s in a row.

SOURCE: http://www.reddit.com/r/explainlikeimfive/comments/14s3rj/eli5the_boltzmann_brain_paradox/

SOURCE: http://www.reddit.com/r/explainlikeimfive/comments/1u7znz/why_do_months_have_different_number_of_days/

http://www.reddit.com/r/socialskills/comments/1dwuui/amazing_ted_talk_on_body_language/ http://www.reddit.com/r/explainlikeimfive/comments/1dx3or/eli5_what_is_happening_when_my_foot_falls_asleep/ http://www.newyorker.com/reporting/2008/06/30/080630fa_fact_gawande?currentPage=all