Subject: Can someone please explain?
Posted by: Mixamatosis
Date: Jan 21 17
I've read that it's dangerous to mix ammonia and bleach. Variously I've read that it can produce deadly cyanide gas, chlorine gas (which is said to be bad for you) and even explosions.
However swimming pools are kept fit for use with chlorine, and our urine contains ammonia but then we may clean toilets with bleach. Also many cleaning products contain either ammonia or bleach and it would be easy to use them unthinkingly in combination.
How is it that people aren't generally harmed by these dangers when swimming in swimming pools or doing daily cleaning, or are we being harmed at low level and is the harm cumulative?
Posted by: Mixamatosis
Date: Jan 21 17
I've read that it's dangerous to mix ammonia and bleach. Variously I've read that it can produce deadly cyanide gas, chlorine gas (which is said to be bad for you) and even explosions.
However swimming pools are kept fit for use with chlorine, and our urine contains ammonia but then we may clean toilets with bleach. Also many cleaning products contain either ammonia or bleach and it would be easy to use them unthinkingly in combination.
How is it that people aren't generally harmed by these dangers when swimming in swimming pools or doing daily cleaning, or are we being harmed at low level and is the harm cumulative?
526 replies. On page 5 of 27 pages. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
daver852 
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On the bright side, you know that due to global warming it hasn't snowed in Great Britain in almost 20 years, and that the polar regions are now ice free. It is a bit disheartening that polar bears are extinct, and most of New York City is underwater, but I sleep easier at night knowing that great men like Al Gore and Bill Nye are getting rich. Reply #81. Apr 29 17, 3:59 PM |
brm50diboll
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Apparently people still live in Venice, daver. I wonder why? Haven't they heard the news? "It's game over, man! Game over!" - (my best Bill Paxton imitation from Aliens.) Reply #82. Apr 29 17, 7:47 PM |
Mixamatosis
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Oh Daver! When I bought my house in 1986 we had central heating but it wasn't enough in Winter and we also lit an open fire as well, but from the 90s onwards that's never been necessary and in the last decade or so I've had to buy fans for the Summer. The last time I remember a significant snowfall in London was in 1993 though it does snow very briefly in Winter here in some years but even then it's never gets deep and never lasts long. It's not a big deal here but if you are living in part of the world where you rely on the occasional rain for the life of your crops, animals and yourself, and more recently, more frequently those rains fail to happen, it's no joke. Reply #83. May 01 17, 3:38 AM |
| Mixamatosis
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Apart from the scientific research, which I'm surprised you scientists choose to ignore, the native Americans in North and South America know what's happening. They have been in tune with, and observant of, the environment generation after generation going back a long way. Reply #84. May 01 17, 3:42 AM |
| brm50diboll
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So Part II of my soliloquy on right ascension. When a celestial body is as high above the horizon as it is going to get for that day (or, more commonly, that night), it is said to be "on the meridian". When the sun is on the meridian (at its maximum altitude for the day), it is said to be "local noon". Local noon differs somewhat from official noon because of factors like Daylight Savings Time, observer's longitude, and the elliptical nature of Earth's orbit. For example, here in Longview this time of year, the sun is on the meridian about 1:20 pm. Before the sun reaches maximum altitude, it is ante meridian (am). After the sun has passed its maximum altitude, it is post meridian (pm). Now the same effect occurs for other celestial bodies, but they are usually visible on the meridian at night (the moon can occasionally be seen in the day.) Now considering stars, they follow a cycle called the sidereal day, which is about four minutes shorter than the solar day of 24 hours. That is, the sidereal day is approximately 23 hours and 56 minutes long. The reason for the approximate four minute difference is the Earth's revolution around the Sun. So if Sirius, for example, is on the meridian at 8:46 pm on February 3 somewhere, the next day, February 4, it will be on the meridian at 8:42 pm, and for each day that passes, it reaches the meridian four minutes earlier than the day before. Sirius is a classic "winter star". That is, it reaches the meridian in the early evening hours (between 6-9 pm, approximately) during the winter months. In the summer, Sirius is on the meridian during daylight hours and not visible. When a particular star is on the meridian in the early evening is a function of its right ascension. If a star with a RA of 0 hours is on the meridian at 8:00 pm one night, for example, then one hour later, any star on the meridian at 9:00 pm will have an RA of 1 hour. A star that reaches the meridian that night at 1:00 am (five hours after the first star) would have (you guessed it!) an RA of 5 hours. As a general principle, subject to the location of the observer and declination effects like circumpolarity (previously explained), stars with RAs of 0-6 hours are best observed in the early evenings after sunset in the fall. Stars with RAs of 6-12 hours are best observed in the early evenings in the winter, stars with RAs of 12-18 hours are best observed in the early evenings in the spring, and stars with RAs of 18-24 hours (actually 24=0, again), are best observed in the early evenings in the summer. But if you are viewing the sky in the predawn hours, you will see different RAs. For example, we say Sirius is a winter star. But Sirius can be seen in the summer, just not after sunset. To find Sirius, the Dog Star, during the August "dog days", you would look for it rising the east (actually, the east southeast) shortly before dawn. This again is a function of right ascension. 6 hours later at night than "early evening" is equivalent to one whole season of the calendar. So if you go out at 7 pm in February, you will see mostly "winter stars", but on the same February night at 1 am, the stars you will mostly see at that late hour will be "spring stars". As a general rule, you can't see a zodiac constellation during its "star sign" in astrology because the Sun is near it. So, for example, Leo is a "spring constellation". As a Leo, I cannot see Leo on my birthday of August 10 because the Sun is in Leo that day (very close to the Cancer border, actually, because of precession of the equinoxes, but still:) Don't go looking for the constellation of your astrology "star sign" on your birthday because the Sun is in or very near that constellation on that day. Truly understanding right ascension requires a planisphere, planetarium, star globe, or computer app, but I've tried to do the best I can with just words here. Reply #85. May 07 17, 4:14 PM |
13LuckyLady
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Schrodinger's cat....dead, alive or never in the box? What do you think, Brian? Reply #86. May 07 17, 4:30 PM |
| brm50diboll
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Interesting question. The answer has to do with one's own personal interpretation of quantum mechanics, which has many extremely counterintuitive characteristics that defy classical comparisons. The traditional "Copenhagen interpretation" says that the waveform contains all possibilities until observed, then "collapses" to only one when an observation is made. Schrödinger basically was critiquing that idea, arguing that the Copenhagen interpretation in the cat in a box thought experiment implied the cat was "both dead and alive" in the box until the box was opened, which certainly sounds ridiculous. But there are other Interpretations of quantum mechanics. I happen to favor the so-called "many worlds" interpretation, which states that every possibility that can happen does in fact happen in some parallel universe, where parallel universes keep branching off from each other constantly with each virtually infinite quantum mechanical choice. So by "many worlds", the cat is alive in some universes but dead in others. If we open the box and find a live cat, then there exists a huge number of parallel universes in which the cat was dead. Can we prove any of this definitively one way or another? No, at least not with our present level of understanding. And the scientific method rules, so any proposition which is untestable is more a philosophical debate than a truly scientific one until and unless someone finds a way to test it. Not everything is testable. Godel's Incompleteness Theorem in mathematics is deeply disturbing to many scientists and mathematicians because it shows that under *any* consistent set of mathematical axioms, there will always be propositions that cannot be proven one way or the other. So a "Theory of Everything" may in fact be mathematically impossible. But the so-called "deterministic" view of science is already rendered invalid by quantum mechanics. This is not an argument for giving up on trying to solve any particular difficult scientific problem, just a statement that some problems may remain unsolvable no matter how much time, effort, (or money, if I may be so blunt) is spent on the problem. Reply #87. May 07 17, 5:37 PM |
| 13LuckyLady
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Awesome! Thank you! There are vast possibilities and to consider one and only one..... ...is impossible. Reply #88. May 07 17, 6:25 PM |
| brm50diboll
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There is a certain "vanity" in assuming all problems may be solved scientifically. Certainly if that were proved true, it could put a lot of philosophers and theologians out of business. An old statement I have heard and passed on to others, for whatever it's worth (if anything): The larger the island of knowledge, the longer the shoreline of wonder. Put another way, the more we know, the more we are aware of we don't know. Or as a certain former Defense Secretary said (I'm paraphrasing a bit since I don't remember the exact words and I'm not bothering to google it before typing this, although I'm sure it can be found (under Rumsfeld)): There are knowns and unknowns. There are things we know we don't know and there are things we don't know we don't know. Teenagers "know everything" because they aren't experienced enough to recognize what they don't know. I, by contrast, am very certain of things I know I know, but very, very, uncertain of things I know I don't know. You know? Reply #89. May 07 17, 6:44 PM |
| daver852
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If two black holes of absolutely equal mass and spin, one being of matter and the other of antimatter, collided, how would angular momentum be conserved? Reply #90. May 07 17, 8:30 PM |
| brm50diboll
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I assume this is a purely hypothetical question as I have never heard of a black hole composed of antimatter. All antimatter in our universe that we know of is transient because it is vastly outnumbered by matter and tends to run into it, annihilating it and the matter it strikes, producing gamma rays (photons of very high energy.) Black hole mergers produce larger black holes, and whatever happens to the particles that were inside those black holes when they formed remains forever unknown to us beyond the event horizon of the merged black hole. I speculate that the law of conservation of angular momentum remains conserved, even in this case, as the angular momentum of an object composed even of antimatter is a function of its mass, and the mass of antimatter is positive, not negative. So in the simplified case of one 15 solar mass black hole composed of matter colliding with one 15 solar mass black hole composed of antimatter, both of which exhibit similar rotational properties in their accretion disks just outside their event horizons, while the merged black hole may contain only gamma ray photons; nevertheless, by mass-energy equivalence, the result would be observable to us as a 30 solar mass black hole with an accretion disc of similar rotational properties as its progenitors. Speculation about such objects as "white holes" and "wormholes" notwithstanding, I don't believe black holes originating from antimatter exist in our universe, but I certainly can't prove it, and I will readily admit I'm not a physicist. Reply #91. May 07 17, 9:06 PM |
| brm50diboll
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So Brian, what exactly is this "ecliptic" thing you keep mentioning? Reply #92. May 11 17, 2:01 PM |
| brm50diboll
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The ecliptic is the apparent path of the Sun through the sky over the course of the year. Now the stars and constellations are not visible during daylight with the naked eye, but they are still there, even with the Sun smack in the middle of them. Telescopes are actually capable of observing the brighter stars during daylight. And in the rare case of a total solar eclipse, the stars surrounding the Sun become visible briefly. Because of the Earth's tilted axis (about 23.5°), the Sun appears to change declination during the course of the year as well as right ascension. The Sun reaches its northernmost point in the sky (declination +23.5°) on the summer solstice, approximately June 21. Its right ascension that day is 6 hours. The circle on the Earth where the sun passes through the zenith that day is called the Tropic of Cancer, because in ancient times it was in Cancer, but due to precession of the equinoxes, today, the Sun is in Taurus just barely on the Taurus side of the Taurus-Gemini border, at the time of the summer solstice. Similarly, the Sun reaches its southernmost declination at the winter solstice, approximately December 21 at declination -23.5°. The circle on the Earth where the Sun passes through the zenith that day is called the Tropic of Capricorn, because in ancient times the Sun was in Capricornus that day, though, due to precession of the equinoxes, it is now in Sagittarius at the winter solstice. Its RA at that time is 18 hours. Now, the traditional 12 constellations that lie on the ecliptic are referred to as the zodiac constellations. There is a difference between the actual constellations in astronomy and the "star signs" of astrology. Two of them have slightly different names. In astrology, the names are Scorpio and Capricorn. In astronomy, the names are Scorpius and Capricornus. In astrology, the twelve "star signs" are of equal distance, 30° (or two hours of right ascension) apiece. In astronomy, the boundaries between the zodiac constellations are somewhat irregular and unequal. In addition, the ecliptic actually passes outside the boundaries of the twelve zodiac constellations for a few days in December. By astronomy (not astrology), the Sun is actually in the constellation Ophiuchus the Serpent Bearer for a few days in December as it leaves Scorpius and heads towards Sagittarius. Because of this, Ophiuchus has sometimes been called the "thirteenth" zodiac constellation, but it is not recognized by astrology. Now the moon, the planets, and most asteroids also follow paths in the sky that are close to the ecliptic. Special emphasis on the words *CLOSE TO* ! They are typically, unlike the Sun, not exactly *on* the ecliptic, but a few degrees from it. The Moon, for example, can be as far as five degrees away from the ecliptic and the planets are also off the ecliptic most of the time by a similar distance. This is significant, because if the Moon was actually exactly *on* the ecliptic, every single full moon would be a total lunar eclipse, and every single new moon would be a total solar eclipse. Because the Moon can get a few degrees away from the ecliptic, eclipses are rare. The Moon, in addition to passing through the zodiac constellations and Ophiuchus, can also enter a corner of the constellation Cetus the Whale from time to time. The word "ecliptic" actually comes from eclipse because eclipses always occur when the Moon is crossing the actual ecliptic, instead of just near it. When planets cross the ecliptic (similarly rarely as in the case of the Moon), phenomena such as transits of the Sun (for Mercury and Venus only) and occultations can occur. As an important aside, *this* year, 2017, we are going to have the first total solar eclipse in the contiguous USA for a long time on August 21 That's right: there will be a total eclipse of the Sun visible in much of the USA on August 21 of this year. Look for it, Americans. USA! USA! In Leo, as well! Reply #93. May 11 17, 2:40 PM |
| 13LuckyLady
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Brian, interesting reading. Thanks! Thirteenth zodiac constellation not recognized? Even more to consider.... :) Reply #94. May 11 17, 3:31 PM |
| brm50diboll
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Appreciate your response. I am heading somewhere with these "soliloquies" of mine, but it will take awhile to get there. Ophiuchus the Serpent Bearer is connected to the only "split" constellation of the 88 official ones: Serpens the Serpent. Part of Serpens is to the left of Ophiuchus, and part of Serpens is to the right of Ophiuchus. Even though the two parts of Serpens are not connected, they are officially considered one constellation, not two. Reply #95. May 11 17, 4:13 PM |
| brm50diboll
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Brian, how long do stars burn before they die out? Reply #96. May 16 17, 11:51 PM |
| brm50diboll
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It depends on the size of the star when it first formed. Paradoxically, the larger the star, the shorter its lifespan. This is because, even though larger stars have more "fuel" to burn, they burn it at vastly higher rates than smaller stars because their greater gravity compresses their cores more, leading to higher core temperatures and geometrically increased rates of fusion, and it is in fact nuclear fusion that produces the energy of stars. Our Sun is a medium-sized star which is almost half way through its expected lifespan of 10 billion years (for reference, the universe itself is about 13.7 billion years old.) Class O blue stars are the giants of the star world, and have lifespans of only a few million years before they swell into supergiants and die in spectacular supernova explosions. At the other end, red dwarfs like Proxima Centauri (the closest star to us other than the Sun at 4.2 light years), weigh only about 1% of the Sun's mass but have estimated lifespans of tens of trillions of years. I say "estimated" because their lifespans are so much longer than the age of the universe that no red dwarf star ever formed has yet come close to running out of fuel. Most nuclear fusion in stars converts hydrogen into helium, the two most common elements in stars. This hydrogen to helium fusion is what defines the "main sequence" which the vast majority of stars belong to. But when they get old, near the end of their lifespans (as determined by their sizes), they begin fusing other elements and leave the main sequence. How stars die is also a function of their masses, and I will leave that discussion for another day. Reply #97. May 17 17, 12:06 AM |
| brm50diboll
|
One of the difficulties (perhaps *the* most important one) in modern science education is the large "gap" between what is known by researchers and what is known by the general public. When the gap becomes too large, all sorts of pseudoscience can exist and thrive (especially in the internet age), because people are unable to "connect the dots" between basic knowledge and state of the art. Here Arthur C. Clarke's "Third Law" becomes an issue: Any sufficiently advanced technology becomes indistinguishable from magic. To pick one concrete example: everyone knows the amazing things smartphones can do, but very few people have an understanding of how they work. They might as well be gifts to humans from Prometheus as far as most people are concerned. But while I have great admiration for HL Mencken (particularly his writings on the "booboisie"), (I've always had admirations for such curmudgeons, such as Mark Twain and George Carlin (particularly in their later, more cynical years)) nevertheless, Mencken was wrong about physics and wrong about advanced mathematics. Smartphones exist because of solid state physics, which exists because of quantum mechanics, which exists because of advanced mathematics. Only an unfortunately tiny percentage of the population is able to connect the dots here, though. To most people, smartphones may as well be magic, and while most people do believe they are grounded in science, unfortunately, they see that belief as "faith in science". Science is not a faith. Most of what I write in this thread is not about smartphones, but about astronomy. I believe that highly educated people, even nonscientists, are capable of connecting the dots given enough time and effort. One of the statements most irritating to scientists is: "it's just a theory". Theories in science aren't fanciful guesses, unlike the common usage of the word. So "it's just my theory that stars are millions or billions of years old" is based on what? Faith in "high priests" of science like Carl Sagan? That's not how science works. Scientists are constantly trying to disprove each other. Nothing gets a scientist more attention than overturning established paradigms through the use of the scientific method. So since no human is a million years old, on what *do* astronomers base their statements about the lives of the stars, some ritualistic mantras passed down since Galileo and Copernicus? No, astrophysics, which is a branch of physics which is particularly dependent on spectroscopy. So, to go any further in the story, I must try to tackle the Hertzsprung-Russell diagram (or HR diagram, for short). It is a difficult undertaking, but the dots *can* be connected. Reply #98. May 25 17, 10:19 PM |
| brm50diboll
|
The only information we really have about stars is their light. Fortunately, thanks to spectroscopy, that is actually a *lot* of information. Although it is usually only obvious for the brighter stars, all stars have color and, it turns out, color corresponds to the surface temperature of stars (or any hot material, including gases and plasmas that can be recreated in laboratories on earth.) Ranking colors of stars from hottest to coolest, we have : blue, white, yellow, orange, and red. With spectroscopy and analysis of the light's blackbody curve, the surface temperature of the star can be determined very precisely, within just a few degrees. A method of classifying stars by their surface temperatures using letters has been developed and is traditionally taught in introductory astronomy courses using the mnemonic: Oh, Be A Fine Girl, Kiss Me. That is, the traditional spectral classifications are, from hottest to coolest: O B A F G K M. Each main category has been subdivided into subcategories with numbers from 0-9 (0 hottest, 9 coolest). The Sun, for example, an average yellow star, is spectral classification G2. Spectral classification, color, and surface temperature are all related to each other and are plotted on the horizontal (x) axis of the HR Diagram. The vertical (y) axis of the HR Diagram is a different parameter, absolute magnitude or luminosity (previously discussed). How this parameter is determined I will look at later. Then I will put the two pieces together to tell what the HR Diagram tells us, and, more importantly, why it tells us this. Reply #99. May 31 17, 10:59 AM |
| Mixamatosis
|
Looking back at one of the posts about the things we don't know we don't know (a la Rumsfeld).... if there are things we don't know we don't know, isn't it possible that it's because we haven't needed to know them. If we needed to know them, and we didn't know them, we'd know we didn't know them wouldn't we? e.g We know we don't have a sure fire cure for all cancers because having a cure is a need. If no one in the human race had felt a need for a certain piece of knowledge which exists (theoretically), how would we know we didn't know it? It's late at night so it's possible what I'm writing doesn't make sense, but it seems to, to me, at the moment. Reply #100. May 31 17, 4:11 PM |
526 replies. On page 5 of 27 pages. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
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