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I’m tired and not braining much today, so sit back and enjoy this astronomical short on Mars. :)
I’ve read about somewhat arcane nature of piano tuning and the various temperaments used through the ages, but Minute Physics succinctly describes what is going with all the math behind the production of sound.
Many factors cause pianos to go out of tune, particularly atmospheric changes. For instance, changes in humidity will affect the pitch of a piano; high humidity causes the sound board to swell, stretching the strings and causing the pitch to go sharp, while low humidity has the opposite effect. Changes in temperature can also affect the overall pitch of a piano. In newer pianos the strings gradually stretch and wooden parts compress, causing the piano to go flat, while in older pianos the tuning pins (that hold the strings in tune) can become loose and don’t hold the piano in tune as well. Frequent and hard playing can also cause a piano to go out of tune. For these reasons, many piano manufacturers recommend that new pianos be tuned four times during the first year and twice a year thereafter.
An out-of-tune piano can often be identified by the characteristic “honky tonk” wah-wah or beating sound it produces. This fluctuation in the sound intensity is a result of two (or more) tones of similar frequencies being played together. For example, if a piano string tuned to 440 Hz (vibrations per second) is played together with a piano string tuned to 442 Hz, the resulting tone beats at a frequency of 2 Hz, due to the constructive and destructive interference between the two tones. Likewise, if a string tuned to 220 Hz (with a harmonic at 440 Hz) is played together with a string tuned at 442 Hz, the same 2 Hz beat is heard. Because pianos typically have multiple strings for each piano key, these strings must be tuned to the same frequency to eliminate beats.
The pitch of a note is determined by the frequency of vibrations. For a vibrating string, the frequency is determined by the string’s length, mass, and tension. Piano strings are wrapped around tuning pins, which are turned to adjust the tension of the strings.
Piano tuning became a profession around the beginning of the 1800s, as the “pianoforte” became mainstream. Previously musicians owned harpsichords, which were much easier to tune, and which the musicians generally tuned themselves. Early piano tuners were trained and employed in piano factories, and often underwent an apprenticeship of about 5–7 years. Early tuners faced challenges related to a large variety of new and changing pianos and non-standardized pitches.
Historically, keyboard instruments were tuned using just intonation, pythagorean tuning and meantone temperament meaning that such instruments could sound “in tune” in one key, or some keys, but would then have more dissonance in other keys. The development of well temperament allowed fixed-pitch instruments to play reasonably well in all of the keys. The famous “Well-Tempered Clavier” by Johann Sebastian Bach took advantage of this breakthrough, with preludes and fugues written for all 24 major and minor keys. However, while unpleasant intervals (such as the wolf interval) were avoided, the sizes of intervals were still not consistent between keys, and so each key still had its own distinctive character. During the 1700s this variation led to an increase in the use of equal temperament, in which the frequency ratio between each pair of adjacent notes on the keyboard was made equal, allowing music to be transposed between keys without changing the relationship between notes.
Pianos are generally tuned to an A440 pitch standard that was adopted during the early 1900s in response to widely varying standards. Previously the pitch standards had gradually risen from about A415 during the late 1700s and early 1800s to A435 during the late 1800s. Though A440 is generally the standard, some orchestras, particularly in Europe, use a higher pitch standard, such as A444.
Yes, this series is purposefully very user friendly – but it does cover some new stuff – who knew about Magnetars? You will. :)
Well, it never hurts to reinforce an important concept, especially one that many people miss or gloss over when the argumentative fur starts flying.
The universe is an amazing thing. While you are “sitting still” reading this post, you, me, and everyone else are hurdling through space at an unfathomable speed. This is almost as amazing as the fact that we, for the most part, don’t even notice that we’re doing it. The Earth rotates 1,600km/h at the equator, which goes down to 0 at the poles, for an average of 800km/h across the planet. Our orbit takes us around the sun at 107,000 km/h and our solar system’s orbit around the galaxy has us going about 792,000 km/h. On top of that our solar system kind of meanders about at 70,000km/h in our section of the Milky Way. On top of all of that, our galaxy’s movement in relation to the background cosmic radiation has us cruising at a cool 2.1 million km/h through the universe. All tolled, we are moving through space at about 3,000,000 km/h OR 853 km/s OR 0.3% the speed of light. That is damn fast.
What the hell does this have to do with ghosts?
Glad you asked. Read the rest of this entry »
I love these vids. :)
Every once and awhile something good bubbles up from the seething mass known as tumblr. This is a good summary of what sex and gender are and how they interact in our society.
“It seems like on here at tumblr there’s a lot of misinformation going around. people are using sex and gender interchangeably as if they mean the same thing. There’s a lot of unclear information and everything seems rally vague and distorted so the goal of this post is to help clear some of this up.
What are the differences between sex and gender?
The main difference is that sex describes your body’s biological reproductive role. Humans as a species reproduce sexually, as opposed to species which reproduce asexually, such as by budding. In human reproduction, a sperm cell will fertilize an egg cell and cause a pregnancy.
We call people whose biology designated them to be sperm depositors “male” and we call people who are designed by biology to be pregnancy carriers “female”. That is all these terms mean, they reference what role we would play in reproduction if we decided to produce offspring.
Gender on the other hand, is a big mass of controversy. See, unlike biological sex, gender is not innate. We are not born with a gender. Gender is a social construct–that means it only exists as long as society propagates it.
What is gender?
Gender is an oppressive force that dictates to people how they should behave, dress, act, what their role in life is, how to interact with other people, etc.. While specific gender roles and norms vary from culture to culture, in every culture, gender exists to tell people how to live, and it is always oppressive.
Gender is a hierarchy which places males above females. Gendered interaction dictates that women defer to men, that men are taken more seriously, that men are more credible, that men are treated as superior.
In our society, femininity is the gender role forced on to women, and masculinity is the gender role forced on to men. We also label objects and clothes and behaviors as “feminine” or “masculine” based on how these objects are linked to oppressive gender roles.
Why is femininity oppressive?
From the day we are born, female people are forced against our will in to the gender role of femininity. People will immediately begin to judge this tiny human, telling her she is “cute” and “pretty”. Even as she is first learning language and what words mean, she is also learning that it is rewarding to be “pretty” and that she receives praise for it. She will learn this way, since her birth, that her value as a person is determined by her visual appeal to others.
There is much literature written on the oppressive nature of femininity. In short, femininity is how society tells women to behave. Femininity is policing one’s appearance as if we are a visual object, paying rent in beauty just to exist in the world. Femininity is in our meekness, our smallness, how we are trained to put ourselves second and put men especially first, to be accommodating, to accept disrespect from men, to not have boundaries lest we insult men, to put male feelings above our own safety and bodily autonomy.
Femininity is not innate to women. It is something we are taught, something we are forced in to. Women do not naturally behave meekly, we are not born wanting to put make up on our faces.
The idea that gender is innate oppresses women.
Historically, women have been told that femininity, this forced gender role of being innate and subservient and meek and stupid and focused on vanity/appearance, is actually a biological innate part of who we are and is exactly what makes us women.
This idea, that femininity is natural to women, has been used to keep us out of science, to keep us oppressed housewives, because that is all that gender dictates we are good for (remember, gender is a hierarchy which tells you how to live).
Gender is obviously not innate–the existence of feral children, generally cases of extreme negligence, illustrates to us just how gender is something we are taught and not something we are born with. Women are not born with the idea that they must shave their legs and be meek and accommodating to men. This is not natural to us. Gender oppresses us.
Gender is an oppressive belief system and buying in to it continues the oppression of women.
The solution is gender abolition. If we abolish gender, nobody would be told how to live, what to wear, or how to behave. There would be no hierarchy placing males above females. Biological sex would continue to exist, because it is something made by evolution and required for reproduction of our species. But gender, the idea that your biological sex says anything about your personality, would not exist.
Males and females would each be permitted to have any kind of personality.
We would not needlessly assign femininity or masculinity to hobbies or toys or any other objects in order to limit peoples’ interests. Everyone could be free to be who they truly are, without oppressive gender labels telling people how to live.
Abolishing gender is best for everyone involved, and also liberates women from the oppressive system of gender.”