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Well, it's a constant in any medium. Just a different constant.
If your actions inspire others to dream more, learn more, do more and become more, you are a leader.-John Q. Adams
You must accept one of two basic premises: Either we are alone in the universe, or we are not alone in the universe. And either way, the implications are staggering.-Wernher von Braun
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.-Albert Einstein
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I thought about it... but that's not strictly true, anyway, if you consider the relativistic effects of high-density, high-mass objects: in fact, "the speed of light in a vacuum around a given mass is a constant" -- but that's not true, either, because the speed of light is the speed at which one can circumnavigate the universe once in a period of one universe lifetime... and since the universe is expanding, that value is changing constantly (along with the size of a meter, and so forth)... so effectively, the speed of light is a constant only because we want it to be.
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No. In a vacuum the speed of light is constant. No exceptions.
The light can be bent by mass, but not slowed down.
The universe is expanding, yes, so the light is going to need more and more time to travel across it, but the speed is still constant. No implications about it.
In fact, relativity states that the speed of light in a vacuum is the ONLY thing that remains constant in different reference systems. Which can get you down in a very deep rabbit hole: time shrinks and space expands, but whoever are you, wherever are you, you will still get around 300'000 km/s for a ray of light in a vacuum.
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Yes, but the size of a kilometer changes as the universe expands. So does the size of the instruments used to measure it, and the atoms constituting said instruments, so we don't notice... but to an outside (the universe) observer, a difference would be noticeable.
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Dan Sutton wrote: size of a kilometer changes as the universe expands
...but not here.
Dan Sutton wrote: So does the size of the instruments used to measure it, and the atoms constituting said instrument
No.
A distance between very big objects (clusters of galaxies) raises, but in smaller systems (galaxies, planetary systems, the Earth) the objects themself are held by gravitation.
In our local neibourhood, it's not like:
* *
** **
It is like this:
* *
* *
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Yes, but the effect of gravitation and the distances between things are dependent on the speed of light, which is a function of the size of the universe. As the speed of light increases, the sizes of everything and the distances between them adjust accordingly to keep it looking the same to anything inside the event: an observer outside the universe would see everything growing, but to us, it looks as though it's a constant size. In fact, though, the sizes of everything, down to the levels of quarks and so forth, change with the expansion of the universe, as do the distances between them: but from our point of view - because we're part of that process - we can't detect this happening... although, logically, it does. The concept of big objects becoming further apart is also true, but from our point of view as well as from the point of view of an external observer: there are two different paradigms at work here.
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Dan Sutton wrote: speed of light is a function of the size of the universe.
I don't get it. What kind of function? It is constant. In early universe, the space itself was densier, so even if it was as small as a golf ball, a light would need the same time to travel through it. There would be the same amount of space to go through.
Dan Sutton wrote: an observer outside the universe
Wait, what? "Outside the universe" means... where exactly?
Dan Sutton wrote: In fact, though, the sizes of everything, down to the levels of quarks and so forth, change with the expansion of the universe
If it was true, then a structure of the universe - planets and stars and so on - wouldn't change that much during time (looking backwards). Why? There would be no reason to be so. If all particles scale (and, as a consequence, all interactions between them -- beacuse a ratio distances to sizes would be constant), then the early universe would be just a downscaled version of today, like a toy car -- which brings us to a creationstic point of view. Also, it would be as cold as it is today and there wouldn't exist a microwave background, which is a trace of a hot "particle soup" cooked on a birdth of the universe. But we know, that there IS a microwave background. We can observe protogalaxies and other relicts which clearly prove that the very early universe was hot and dense. If particles was small and distant -- as they are today -- then a density would be the same.
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You said it, but you don't know you said it: "even if the it was as small as a golf ball, a light would need the same time to travel through it" -- true. But when the universe was that compressed, time dilation around that much condensed mass meant that time itself ran slower. Light always takes one universe lifetime to go right around the universe once: it doesn't matter how large the universe is... but as the universe expands, time runs faster (from the point of view of an outside observer). From the point of view of an observer inside the universe, it always travels at the same speed over the same distance. But "speed" is dependent upon the rate of flow of time - which changes as the universe expands, and thus so does the speed of light and so forth. Consider the type of time dilation effects one would experience within the Schwarzchild radius of a black hole... then realize that the universe is entirely within the Schwarzchild radius of an expanding black hole. But things can change within it: the dilation of the flow of time doesn't preclude other physical effects taking place: there's nothing creationistic about it: in fact, it insists that there was a big bang, and that it's still exploding.
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Dan Sutton wrote: From the point of view of an observer inside the universe
I think this is the point where things fall apart. There is no such thing like "an observer outside of spacetime"... in a spacetime itself. We can look at the universe from higher dimensions, but it's kind of out of topic.
Forget creationists, you didn't answer to my doubts about scaling particles:
If all particles scaled (and, as a consequence, all interactions between them -- beacuse a ratio distances to sizes would be constant), then (...) [the universe] would be as cold as it is today and there wouldn't exist a microwave background, which is a trace of a hot "particle soup" cooked on a birdth of the universe. But we know, that there IS a microwave background. (...) If particles was small and distant -- as they are today -- then a density would be the same.
What means a commonly seen therm hot "particle soup"? It means, that particles was close to each other. What close to each other means? It means, that ratio distance/size is small. If particles scaled, then the ratio distance/size would be constant and the universe would not be dense and hot. Which is not true due to existance of a MWB.
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Well, the "observer outside of spacetime" would be a theoretical construct implying that you could observe the universe from a different reference frame: the way we now observe black holes from outside them. But it wouldn't be quite as theoretical if one accepted the theory that the universe is just an exploding singularity contained within a larger universe: some scientists are starting to believe that this is possible.
Particles can still scale and still move apart from one another in an expanding universe: don't forget that the thing is exploding as well: by nature stuff will move apart from other stuff in explosions! If one factors in the time dilation experienced as one moves away from the center of mass, one can see that in a very early universe, time was running faster on the outer surfaces than right in the middle, and thus, for a while, the universe expanded at different rates depending on how far from the center something was... which is why the universe today is twice the diameter it's supposed to be: logic tells us that the radius should be 13.9 billion light years, but it's really more like 26 billion.
The term "particle soup" implies that particles have not yet cohered enough to form atoms or other organized structures: it refers to simply a mass of quarks, unrelated to one another.
Don't forget also that most subatomic particles have a distinct lifespan: a gluon, for example, will decay very quickly either into background energy (MWB) or some other type of particle - this in itself implies the type of changes you're looking for.
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Dan Sutton wrote: Well, the "observer outside of spacetime" would be a theoretical construct implying that you could observe the universe from a different reference frame: the way we now observe black holes from outside them.
Very interesting point.
Dan Sutton wrote: The term "particle soup" implies that particles have not yet cohered enough to form atoms or other organized structures: it refers to simply a mass of quarks, unrelated to one another.
Well, I know that, but my point was that Big Bang theory says that in this stage of evolution particles hit each other very often. Various types of particles was created and annihilated etc etc. But, if particles scaled, then in that stage of universe they wouldn't hit each other so often. Maybe my understanding is wrong, but I see it that way: If you disintegrate the current universe into particles and distribute them evenly, then the universe would be cold. This means, that if you downscale such disintegrated universe, it will be still cold. However, if particles stays the same size, then condensing them would increase temperature -- and this is what I state: That elementary particles don't scale.
Or maybe we agree, but I cannot express myself clearly.
A quick long google search brought this:
http://www.askamathematician.com/2011/11/q-how-does-the-expansion-of-space-affect-the-things-that-inhabit-that-space-are-atoms-people-stars-and-everything-else-getting-bigger-too/[^]
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I have a feeling we sort of agree: after all, the universe is getting colder -- the early universe was super-hot... the heat death concept refers to when the universe expands enough that its average temperature nears absolute zero -- assuming the idea that the thing will never contract again. Of course, in the scenario in which the universe is simply an exploding singularity in another universe, the temperature will reach that of the outside universe: which would, at this point, appear to be infinitely cold to us due to time dilation effects... However, if you were to downscale a disintegrated universe it would be hot: the implication is that you'd need energy to do it, and that energy has to end up going somewhere (and would be expressed as heat). So regardless of whether elementary particles scale, you'd still experience the types of temperature variation you'd expect.
There were (probably) many more particles in the early universe than there are now: many of them will have disintegrated into energy (as seen in the microwave background) and so forth.
Talking about elementary particles is tricky: if you try to look inside one, you don't find anything: ultimately, it's a simple configuration of energy: a field, if you like. To me, it appears (to oversimplify it horrendously) that a unit of mass is nothing much more than a twist in spacetime/energy which slows the speed of light in its local vicinity - think of light in a liquid, for example - from that we derive time dilation effects, gravity and so forth - as Einstein points out, mass and energy are essentially the same thing, so one way to express mass is to state that it's a value to show just how much of a twist in spacetime there is. I guess the question is whether that twist itself occupies more physical space as the universe expands: I have a feeling that it probably does -- which is a tricky thing because it implies that Planck's constant isn't a constant at all... but inasmuch as we're capable of measuring it, it certainly appears to be one.
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Dan Sutton wrote: However, if you were to downscale a disintegrated universe it would be hot: the implication is that you'd need energy to do it, and that energy has to end up going somewhere (and would be expressed as heat). So regardless of whether elementary particles scale, you'd still experience the types of temperature variation you'd expect.
Well, you convinced me. Honestly, an idea of a pure energy is still mysterious for me. Despite we experience it in everyday life. I think we can end this fascinating discussion here. 
Dan Sutton wrote: I guess the question is whether that twist itself occupies more physical space as the universe expands: I have a feeling that it probably does -- which is a tricky thing because it implies that Planck's constant isn't a constant at all... but inasmuch as we're capable of measuring it, it certainly appears to be one.
It will take some time until we find definite answers for this kind of questions. Theory of Everything maybe... Wait for it.
Besides, there is an interesting theory saying that matter is discrete to a Planck scale... inside a black hole. I don't know how it differs from a plain quantum theory, but I saw it in "news" sometime ago. They wrote that it implies that there is no actual singularity in a centre of black hole. It is just packed to it's limit. The theory might solve an information loss paradox (hopefully). Discrete Black-Hole Radiation and the Information Loss Paradox[^].
PS1. Out of curiosity: Are you a Physicist? As for me, I'm just a passionate of astrology, especially when it comes to crazy Mars missions (like Mars One[^]).
PS2. "There are two things that mankind will never understand: black holes and women's brain."
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Funny you should mention the Planck thing: I've thought of it myself: I have a feeling that all singularities detonate as soon as they form, having achieved critical mass. However, current theory holds that a singularity has zero size -- but if that were the case, then there would be zero time flow within it, and thus (to the outside observer) the detonation would take an infinite amount of time to occur -- which violates a number of principles, not least that of heat death. So in fact, I think the singularity is probably one Planck length in diameter - which allows the explosion to occur - and, as you say, solves any other number of inconveniences.
Talking about singularities is vaguely problematic, in that they're mathematical derivatives rather than observed phenomena: we believe they're there, but theory states that they don't form until after the black hole itself comes into existence: mathematics says they must exist and thus they do... but that's as close as we're going to get - at least for now.
I'm not a bona-fide physicist, no - but I am fascinated by the subject and I study it quite a bit. I will, however, admit to being a science-fiction freak -- it's a great genre for getting the mind working...
Speaking of the science fiction, and of the Theory of Everything, Greg Egan suggests in his book "Distress" that as soon as anyone is able to explain exactly how the universe works and provide such a grand unifying theory, the universe will rearrange itself spontaneously so that it has always worked that way. Similar quantum theory suggests that a lot of reality exists because we observe it: that, for example, there was no such thing as a quark until someone discovered them, and then, at that point, the universe had always had quarks in it. Unfortunately, quantum theory supports this type of retroactive creation... I wonder what we've done with this conversation!
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Is the universe expanding, or it is simply our abilty to see further into the universe that is expanding? If we can't see the reaches of the universe, how can we know that it is expanding?
And, if it is expanding, what is it expanding into? Does the absence of matter mean that space doesn't exist?
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Well, the general consensus is that it's expanding because everything we observe out there is somewhat red-shifted, thus the Doppler effect tells us that everything's retreating from everything else. The question of what it's expanding into is more interesting: my own theory which I've held for a long time, and which is now becoming accepted by various factions within astrophysics, is that the universe is actually an exploding singularity within a larger universe: this explains several things, such as the fact that the size of the universe is (mathematically) much greater than it should be. In theory, if the universe is 13.7 billion years old (as is currently stated) then its radius should be 13.7 billion light years, since it shouldn't be possible for it to expand faster than the speed of light. But in fact, it's something like twice that: a conundrum which has stumped physicists for a while now. However, if the universe is an exploding singularity, then its theoretical radius is determined by the radius of the event horizon of the black hole surrounding such a singularity -- into which matter can fall from outside. This would explain massive objects on the boundaries of what we can see - such as quasars and so on - which conventional closed-system theory cannot explain - and also where all that extra mass came from. There would be a shift in perception between what we can see and the universe outside, simply because of the time dilation effect one would perceive when approaching a large center of mass. Furthermore, if one were to calculate the distribution of matter inside a black hole with the mass of the universe, then one would actually come out with a distribution of matter virtually identical to what we can see now. My theory goes on to state that (a) all singularities detonate at the instant they form (having achieved critical mass), but that because of the time dilation effect, an outside observer would not detect the explosion: it would appear to take an almost infinite time to occur (although, to an entity inside the exploding black hole, time would proceed at a regular pace, with the "outside" appearing almost infinitely slow, and thus unfathomable: there would be a definite interface between "inside" and "outside"; and that (b) a singularity is not zero-sized at all, but is in fact one Planck length: this removes the problem of it actually taking an infinite length of time for the explosion to occur (as seen from outside). This theory is supported by the fact that known black holes, such as the supermassive type seen at the center of the Milky Way, do radiate massive quantities of energy - primarily in the form of neutrino jets at the poles, as they spin - as Hawking pointed out a few weeks ago, the idea that information cannot leave a black hole is patently false: we see it happening all the time. There's still a hell of a lot of thinking to be done on this subject, in any event.
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A well reasoned explanation, which is better than most of the time when it is simply stated 'scientists say...' and to counter that simple arguement is to invite ridicule.
While I may not understand what you wrote, or agree with it, as I said, it is a possible, well explained answer.
Thank you,
Tim
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Thanks! [Disclaimer: I'm not sure I agree with it, either, but it does have the benefit of being an explanation which isn't currently disprovable, and which does explain a lot of "that weird sh*t" which seems to plague the field...!]
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WALL OF TEXT!
<voice type="Ebeneezer Scrooge"> Bah. dumb bugs </voice>
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Somehow I was thinking that Number of Programmers and Code Quality would be inversely proportional.
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They are. If you re-write it a little, you get: Q = c·t/N
Thus quality is proportional to time, and inversely proportional to the number of programmers.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Seems a bit incomplete to me, you need to add the number of managers, and the level of customer involvement AKA feature creep. 
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If your actions inspire others to dream more, learn more, do more and become more, you are a leader.-John Q. Adams
You must accept one of two basic premises: Either we are alone in the universe, or we are not alone in the universe. And either way, the implications are staggering.-Wernher von Braun
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.-Albert Einstein
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I'll buy that. Change "programmers" to "people". LOL!
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I was thinking more in the lines of:
NQM(2f+1)/t=c, where:
- N is the number of programmers on the project;
- Q is the quality of the final product;
- M is the number of managers on the project;
- f is feature creep (in percents of the original number of features);
- t is the time taken to develop the product;
- c is a constant
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