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 23 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
brm50diboll 
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So back to my promise at the end of post #437. The issue in models is understanding dimensions. Just how many spatial dimensions are there, really? There is a fifth dimension beyond that which is known to man.... https://tinyurl.com/ydqowsyh Sorry, couldn't resist. Anyway, there are actually a lot more than 3 spatial dimensions, if you follow string theory, anyway. There appear to be as many dimensions as needed to work out the mathematics of a particular problem in theoretical physics. But those dimensions beyond the three we perceive are said to be tightly curled up at the subatomic level. But I digress. If we assume that the three familiar spatial dimensions are "curved" by at least one other, unseen, fourth dimension, how can we model this? Well, consider a two dimensional "flat" universe. (Here I could digress into a discussion of Edwin Abbott's 1884 "Flatland", but I will resist.) Now imagine that two dimensional universe as the surface of a sphere in three dimensions. The surface is curved in the third dimension, but if the sphere is large enough, it is difficult to notice the curvature. Even today, there are those who apparently seriously believe the Earth is flat. What if our entire universe is the "surface" of a very large four-dimensional "hypersphere"? The terms "finite but unbounded" come to mind. Standing on the surface of the Earth and traveling in one specific heading (a so-called "great circle" route), one could, in principle anyway, travel completely around the world and back to one's starting location eventually no matter *which* original heading was chosen. Suppose that were true for our universe. Pick a random "straight line" to head out on. After trillions of years (maybe), no matter which direction you picked, you would arrive back at the point you started from because the three dimensions we perceive are curved slightly by the presence of an unseen fourth dimension. Now to our model. Imagine a two dimensional "surface of a sphere" universe with flat "galaxies" painted on it. Now suppose the sphere *expands". As it expands, all the "galaxies" would get further away from all the other "galaxies". But what is really interesting is that if we calculate the "speed" at which our "galaxies" are moving away from each other, no matter which "galaxy" we pick as our home reference, the further away another "galaxy" is from us, the "faster" it appears to be moving away from us as our "universe" expands. Hubble's Law in action! What if we run this expansion backwards in time? Then, at some point in the past, all the universe would have been located at a fixed point at the "center" of our "hypersphere". That point is not on the present surface of the "hypersphere" though, so the Big Bang did not occur at a fixed point in our present universe. But this idea is the genesis of the Big Bang Theory, (and I'm not talking about the TV show here.) Reply #441. Jan 08 20, 1:23 PM |
DireWolf74
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I used to think the 4th dimension was time. If you have an X,Y,Z point on a grid and draw a line from it to another point in space, the amount of time that it takes to get there is a variable that can be manipulated by gravity. But that can't be right, can it? Anyhoo...here's something more useful. A Beginner's Guide to the Fourth Dimension https://www.youtube.com/watch?v=j-ixGKZlLVc Reply #442. Jan 08 20, 3:00 PM |
| brm50diboll
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Nice video. Yes, time, under certain circumstances, could be considered a dimension, but not a *spatial* dimension. String theory, as I said, posits multiple *spatial dimensions*. How many? Well, mathematics doesn't care, so as many as you need to make your particular theory hold together. I'm not an expert in string theory, but I've read some on it, and the numbers generally used are 11 or 12. All those above the three familiar ones are "degenerate", which is to say, highly coiled up at the very tiny level of subatomic space in the other three dimensions. But, ignoring string theory for the moment, there is no *mathematical* reason that *any* arbitrary number of non-degenerate spatial dimensions could exist. As a starting point for this, typically the "fourth dimension" is considered, with models as in your video of tesseracts, which is the fourth dimensional analog of a cube, but there are, by extension, "fifth-dimensional hypercubes", "sixth-dimensional hypercubes", "seventh-dimensional hypercubes", and so forth ad infinitum, with two dimensional "shadows" which can be modeled as in your video. These are spatial dimensions, not to be confused with temporal (or time) dimensions. By the way, advanced theoretical physics also posits additional temporal dimensions, so-called "imaginary time". Some may ask, do these things really exist? Well, at the risk of sounding like Bill Clinton, it depends on what your definition of "real" is. Does i (the square root of -1) exist? You can't own i apples, but i has a very definite meaning in some physics problems. The next video is long, but shows my surface model from my last post https://www.bing.com/videos/search?q=hubble%27s+law+demonstration&view=detail&mid=E36485E851790EF249BDE36485E851790EF249BD&FORM=VRRTAP Reply #443. Jan 08 20, 5:01 PM |
| brm50diboll
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My last post should have read "no reason ... could *not* exist". Try this next video on for size: https://tinyurl.com/tev84yn Reply #444. Jan 08 20, 5:11 PM |
| DireWolf74
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I've read some on string theory too, not a bunch. I was out of school when it was first proposed. Saw a couple of interesting programs on PBS about it too. Maybe on "Nova". Reply #445. Jan 08 20, 6:49 PM |
| DireWolf74
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Cool video. Basically, anything past the 3rd dimension is cubes inside of other cubes. Or did I miss something obvious? Reply #446. Jan 08 20, 6:52 PM |
| brm50diboll
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We could quibble on what "inside" means in this context. But what the video showed actually was 2D "shadows" of rotating hypercubes. We humans simply can't visualize the hypercubes themselves. To take the tesseract example specifically, a normal 3D cube (dimensions labeled x, y, and z) has 8 vertices, 12 edges, and 6 faces. But a tesseract (dimensions labeled w, x, y, and z) has 16 vertices, 24 edges, 12 faces, and 8 cells. The term "cell" doesn't exist in 3D. It is a region of 3D space crossing over in four dimensions, and its "shadow" looks like a cube. You can "unfold" a normal cube into 6 squares (the faces). Similarly, you can "unfold" a tesseract into 8 cubes (the cells). For a fifth-dimensional hypercube, the numbers would be 32 vertices, 48 edges, 24 faces, 16 cells, and 10 "4D hypercells". Reply #447. Jan 08 20, 7:36 PM |
| DireWolf74
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Okay, I think I get it now. It's the 10 "4D hypercells" that would be intangible then? They don't exist in the physical realm. They are just representations of what we think a 4D object would look like in a 3D world. Waiting for my assessment professor. Mind you...I have no formal education after high school. I was a State Scholar my senior year, determined by GPA and SAT/ACT scores. But I went straight into the Army at age 17. So go easy on me. Reply #448. Jan 08 20, 9:47 PM |
| brm50diboll
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I appreciate your interest. I am doing the best I can to try to explain difficult concepts. Models are useful in understanding, but their limitations need to be pointed out. Unfortunately, pointing out fine details can come across as both confusing and, worse, condescending, and I certainly don't intend either . What words mean in general English usage and what they mean in a strict scientific context can be quite different. So here, "cell" is a very difficult word to define properly for the context. A cell "shadow" (of a tesseract or other hypercube) looks like a cube, but it isn't really a cube. Hypercubes are not the only multidimensional figures. There are hyperspheres and hyperhedrons, for example. The shadow of a hypersphere would look like a sphere. The shadow of a "hypertetrahedron" would look like a tetrahedron. The simplest example of that, the 4D pentahyperhedron, would have 5 cells whose shadows would look like tetrahedrons. It is a problem with the limitations of language. The best I can say is: Shadows of multidimensional figures may look like 3D figures, but they aren't. Reply #449. Jan 08 20, 10:24 PM |
| DireWolf74
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That makes sense. Just like if drew a picture of a three dimensional cube on a flat piece of paper. The cube would look 3D, but it can't be. Reply #450. Jan 08 20, 11:28 PM |
| DireWolf74
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Take this lost "I" and throw it up in my last post somewhere. Typing on my phone stinks. Still wish I could edit my posts. That's the perfectionist in me screaming. Reply #451. Jan 08 20, 11:32 PM |
| DireWolf74
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After my grilling on the GC thread, it's my turn to ask you a question. I'm guessing that you are somewhere in the ballpark range of my age which is 45. You are probably younger even. Ever watch Mr. Wizard's World when you were growing up? https://youtu.be/5tiv-VNFrOQ I learned so much from watching his show every week that by the time I was taking Advanced Placement Physics classes my last two years of high school, I already knew the answers to a lot of the things our teacher was giving lessons on. Reply #452. Jan 09 20, 12:59 AM |
| brm50diboll
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I am actually 56. I was born August 10, 1963. I watched Mr. Wizard a few times. My undergraduate degree is in Chemistry, and I have taught Chemistry for many years, so I have done many of the sorts of things shown in the video for my classes. Nowadays, high school administrators don't like Chemistry teachers blowing up hydrogen-filled balloons inside classrooms. Some sort of nonsense about "safety" or other. In my day, as a student, we played with mercury drops for hours from an open flask of mercury that must have weighed 20 pounds, and none of us got brain damage - Muhahahahaha! But I digress. Actually, I show a lot of these sorts of videos in my Chemistry classes. Much safer than actually doing them yourselves, but I still enjoy throwing sodium and potassium metal in water and watching it explode. I have taught Chemistry, AP Chemistry, Biology, AP Biology, Physics, AP Physics, Astronomy, Geometry, Algebra, and Precalculus. I wish I had had the opportunity to teach Calculus, as I have over 50 hours of college level mathematics, but the administrators wanted me mostly to stick to science and only teach math when they had holes in their faculty coverage. Reply #453. Jan 09 20, 10:38 AM |
| DireWolf74
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Wow! Incredible credentials there Brian. (Took me two times to write Brian instead of Brain). My advanced science classes were my favorite subjects in school. Instead of going into the Army, I had considered trying to get involved with NASA is some way. My grades and ACT scores were good enough to get me accepted into Cornell and I was very close to going in that direction. But my parents really couldn't afford to add much to my tuition and the idea of massive student loans was not very appealing to me. So unless I qualified for a full ride, it wasn't an option. My plan was to finish college at U of Illinois when I got out of the military, but life has it's own ideas of what you should do sometimes. :-) I did manage to get some college credits while in the service. I took this test that the others in the group had been going to classes for months for and studying real hard. I just walked in the day of the test, sat down and 20 minutes later I was done. 3 college credits. Nobody else was close to being done and I saw them looking at me like I was nuts as I walked up to hand in my paper. They actually thought that I blew the test off or didn't fill out everything. Nope! Reply #454. Jan 09 20, 11:08 AM |
| DireWolf74
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And I don't know why I thought your were younger than me. Probably for no other reason that you joined this site after I did. Reply #455. Jan 09 20, 11:09 AM |
| DireWolf74
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"Much safer than actually doing them yourselves, but I still enjoy throwing sodium and potassium metal in water and watching it explode." We did these exact experiments in front of our high school. Pretty cool stuff right? Of course my teacher for my advanced science classes was also the same teacher that threw parties for us at his house with alcoholic beverages and everything. He also was stupid enough to get caught cheating on his wife with one of my 16 year old female classmates. ;-) Uh oh! Still loved his classes...right up until the moment that he had to resign and leave town in the middle of the night. Reply #456. Jan 09 20, 11:32 AM |
| brm50diboll
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I have always been very careful not to do anything that might possibly even be construed as inappropriate behavior with students. I have seen too much of the sort of thing you described happen to other teachers at schools I've worked at. Obviously, they brought it on themselves. You wonder how intelligent people can do such stupid stuff. There was a baseball coach when I was in high school who took the baseball team out to a liquor store for beers before a game. When the administration checked the team bus after the game, it was full of empty beer cans. The school board president didn't want to do anything (his son was on the baseball team), but they couldn't hush it up so they had to fire the coach. The team didn't win another game the rest of the season. Apparently, they needed their beer. Reply #457. Jan 09 20, 11:43 AM |
| DireWolf74
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Used to notice a direct correlation between my bowling score and the amount of beer or J.D. that I had been drinking. There was a definitive point of no return. For a short while, it would relax me more and I wouldn't be thinking about all the steps it takes to roll a ball with perfect form. I've had scores in the 260-280 range. Drink too many and I'm too relaxed and can't hang on to the bowling ball very well. Reply #458. Jan 09 20, 11:59 AM |
| DireWolf74
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There's some science related stuff in there somewhere so it counts for this blog. :-) I used the word "correlation" and the arc of a bowling swing is physics related. Reply #459. Jan 09 20, 12:02 PM |
| brm50diboll
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So returning back to the idea of Hubble's Law and the expansion of the universe, if we go backwards in time, we expect the Universe to be smaller the further back we go. If we go far enough back, the universe is located at a single point in spacetime. At this point, the universe (time and space) begins with an expansion. This is the Big Bang Theory. Now the Big Bang Theory is not the only cosmological origin theory for the universe (although it is the dominant one at present). There have been multiple theories. The term "Big Bang" was actually a derogatory term coined by an astronomer who believed in a competing theory. That would be the eminent Fred Hoyle, who believed in a "Steady State Theory" and scoffed at the idea of one beginning for the universe. Hoyle believed the universe was expanding as Hubble's data showed, but that new matter was continually being created as the universe expanded to maintain the "density" of matter in the universe at a constant. There is no evidence of continuing matter creation, however, so the Big Bang Theory (as strange as its name may be) is the current working paradigm in cosmology, although the time when it began has been subject to considerable revision over my lifetime. Currently, the accepted age of the universe is around 13.8 billion years. One of the problems in fixing that time is the realization that the universe hasn't expanded at the same rate over its entire history. There is this matter of "inflation" to deal with. Maybe next time. Reply #460. Feb 19 20, 12:21 PM |
526 replies. On page 23 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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