Spyman

Galaxies, stars systems and large bodies are held together by gravity. Tiny bodies, atoms and molecules are held together by nuclear forces. In a Newtonian view of space expansion, I think there has to be something that brings the objects apart and this something will have to struggle with the forces holding things together. The force that seems to expand space gets stronger with greater distance, while gravity gets weaker when the distance increases and on very small scales the nuclear forces are dominant. With the understanding that Earths gravity is not able to continue to shrink the Earth because of the dominant nuclear forces on small scales, it is very reasonable to conclude that the expanding force is not able to swell the Earth either because on this scale it is also countered by their stronger forces and gravity on top of that as well. On very very large scales even gravity gets so weak that the force expanding space gets the upper hand and can start to inrease the size between galaxies. But on the scales of galaxies and down to nuclear particles the expanding force are dominated by the other forces. This does not mean that small objects don't swell due to expansion, I think that it is considered that they do, but the measurable expansion in space takes place over tremendous vast distances while the distances on atomic level is infinitesimal puny. The force expanding space should of course be acting inside matter too, slightly increasing the distance between particles, but on this scale the nuclear forces are large compared to the expanding force which is dwindling down to a vanishingly tiny level. The particles are held inside matter at a certain distance due to balance of forces and when adding the expanding force, it is offsetting this distance a tiny bit, this offset only causes the nuclear forces between the particles to rebalance with a slightly larger distance. Bound systems only expands until they reach a slightly larger size where the forces that holds them together counter and stop the expansion. So bound systems don't continue to expand but they are a tiny bit larger due to the expanding force, this tiny bit is so teeny-weeny that it is not measureable and esteemed unimportant. "A cosmological constant has the effect of a repulsive force between objects which is proportional (not inversely proportional) to distance. Unlike inertia it actively "pulls" on objects which have clumped together under the influence of gravity, and even on individual atoms. However this does not cause the objects to grow steadily or to disintegrate; unless they are very weakly bound, they will simply settle into an equilibrium state which is slightly (undetectably) larger than it would otherwise have been." http://en.wikipedia.org/wiki/Metric_expansion_of_space Here is a good link I think you should read: MISCONCEPTIONS ABOUT THE BIG BANG

The deceleration itself does not bring the objects together. I suggest you make the following experiment: Put a ball in a bucket, take the bucket and hold it firmly while you rotate with your arms streached out. Will the ball move closer towards you when you slow down the rotation speed ? If deceleration is involved the ball will roll out if you decelerate fast enough, and if not it will stay in the bucket.

First of all I would like to make it clear that this is NOT my model or in anyway somehow preferred personally by me. It is the deemed current victorious model amongst all others, by the scientific consensus, because it is the only one which is able to explain and predict observed phenomenas. Yes, there are difficulties and not everything can be explained, more work needs to be done. This does not falsificate a model, it is deemed wrong when the predictions are opposed by observations. I never said that there was only ONE model either, I said that the only accepted models are based on space expanding through a change in metric. There are more than one model that are built on the Big Bang and General Relativity. Did you even bother to read the first link found in the first search you posted? Let me qoute a small part from it: "Today, it is more common to find in the scientific literature proposals for "non-standard cosmologies" that actually accept the basic tenets of the big bang cosmology, while modifying parts of the concordance model. Such theories include alternative models of dark energy, such as quintessence, phantom energy and some ideas in brane cosmology; alternative models of dark matter, such as modified Newtonian dynamics; alternatives or extensions to inflation such as chaotic inflation and the ekpyrotic model; and proposals to supplement the universe with a first cause, such as the Hartle-Hawking boundary condition, the cyclic model, and the string landscape. There is no consensus about these ideas amongst cosmologists, but they are nonetheless active fields of academic inquiry. Today, heterodox non-standard cosmologies are generally considered unworthy of consideration by cosmologists while many of the historically significant nonstandard cosmologies are considered to have been falsified. The essentials of the big bang theory have been confirmed by a wide range of complementary and detailed observations, and no non-standard cosmologies have reproduced the range of successes of the big bang model. Speculations about alternatives are not normally part of research or pedagogical discussions except as object lessons or for their historical importance." http://en.wikipedia.org/wiki/Non-standard_cosmology Yes, there are more than one scientific accepted model, but they all depend on basics of the Big Bang theory. Anyone can post crap on the internet so of course there are a lot of NOT accepted models that is unable to fulfill scientific demands and accurate explain observed phenomenas. I make claims based on the scientific consensus with valid references and evidence thereof and you make claims based on a search with google on the internet, that likely include a lot of crackpot ideas, who do you really think looks "ignorant"? As time pass and the model continues to accurate predict observations the reliability of the model increases. It is not deemed false until it is contradicted. Yes, the assumptions might be wrong and the models could be false, but right now "Taken together, the only theory which coherently explains these phenomena relies on space expanding through a change in metric". These models continues to match observations and thereby continues to validate the underlying assumptions too. So far the reliability of the model have increased with every observation we have made. You are of course free to belive that the current models accepted by the scientific consensus is wrong and subscribe to any model you feel fit to your faith, but there are no doubts that this is the conclusion made by the scientific community. I have showed you that it is established knowledge by the scientific consensus that alternate models that doesn't include metric expansion can't explain all observed phenomenas. It is also established by the scientific community that we don't know the total size or shape of the Universe, that the Universe don't have any gravitational center, that the Big Bang was not a traditional explosion with a blast front moving through space or that the Earth is not placed in a central specially favored position. I have supported evidence that this are the mainstream view according to the scientific community and that everything else are "non-standard" alternatives. The factually correct scientific explanation has been given to you. You have once again FAILED to provide any evidence supported with reputable references. I suggest you stop your long winded whining and crying of the endless possibilities for the slight possibly of the scientific consensus to be wrong in their cosmological conclusions, because so far the current explanation and models stands. You can come back when you have any whit of evidence to the contrary. Your actually confirm that I was right on spot, you are disputing the scientific consensus and tries to miscredit its conclusions. I don't give a hoot about Michael Critchton's opinion, questioning the scientific consensus is outside the scope of this thread and best fit in its own thread, in some other subforum. I repeat: This thread is in the subforum "Sciences" and "Physics" where scientific fact and mainstream physics rule. ---------- Anyone can go back read what you said, but lets repeat it again for clarity: cypress said: "General relativity theory precludes the possibility of particles traveling faster than C, thus expansion in every direction from a constant reference frame is disallowed." and: cypress said: "The mass of the universe is of course traveling outward much slower than the radiation wave front and this expansion of mass is generally taken to be the referred to as the expansion of the universe. This are NOT what the General Relativity or the Big Bang theory states, you are clearly contradicting the mainstream view of both theories. Either you have serious problems expressing yourself or your knowledge level of said theories are severely lacking, in both cases what you said are wrong. Your indications of the validity of scientific consensus is not relevant to this argument and neither is the Big Bang theory. This is what you said: cypress said: "So it is not incorrect to describe an alternate reference frame whereby matter near the boundary is moving outward relative to the universes center of gravity." The true fact is that there does NOT exist any shred of evidence at all for an universal gravitational center in space. This is NOT an argument on precision, what I note again is your over reliance on your ability to express yourself or your illusory knowledge level. This is what you said: cypress said: "The Universe is known to be finite, therefore it would seem that it must have one center of gravity." The true fact is that there does NOT exist any shred of evidence at all for the Universe to be finite in size. Which reminds me of your words: "Garbage in garbage out" that can be applied to your logic here. Well, you said this: cypress said: "The observations you summarized are also consistent with uniform expansion of a classical 3 dimensional space of generally uniform density from a observation point near the center." and this: cypress said:" A traditional three dimensional outward expansion of space/time includes a blast front which is the remnants of the initial explosion of energy and matter and the source of background radiation." And I acknowledge that the assumption of Copernican principle were we are not privileged observers might be wrong, but for the moment the model accurately fits observation in contrary to your proposed uniform expansion which is not able to explain all phenomenas. ---------- You are still twisting the words and trying to change the argument, I repeat: I have NEVER claimed that any assumptions or scientific models are 100 percent foolproof. As opposed to your lies of what I have claimed, I have several times acknowledged that assumtions and models not only might be wrong but also are likely to need corrections. Anyone can go back and read what I said in my old posts. The claims you have made that I consider should not be trusted are the following: That space are unable to expand faster than light according to General Relativity, that Big Bang theory is about matter moving outward from an traditional explosion, that the Universe have a gravitational center inside space, that the size of the Universe is finite, that there exists accepted alternate models which are able to explain all observed phenomenas without invoking metric expansion, that scientific conclusions are based on popular opinions and finally that because assumtions can't be validated, scientific models relying on them are mere guesswork without any supporting evidence at all. Everything we know and all our scientific models relies on assumptions and there always exists the possibility that any of them are wrong. We have no other alternative than to observe the reality to the best of our ability and from measurement try to distinguish which assumtions and models that resembles the world around us. We do not know everything and some parts of the models might turn out wrong but that does not mean that we are totally uncertain, that we are in pitch black darkness without knowing anything. We have actually managed to collect some evidence and some knowledge since the dawn of humankind. When we lay the cosmological puzzle and put the pieces we have found together we start to see a picture, and we have models which are able to explain how the Universe could have been able to develop, to turn out like the picture. These models are able to very accurately predict observations we make both on distant objects in outerspace and on small particles in physics labs. The current status of our gathered knowledge and evidence is that the only models we have that qualifies and are able to explain all the observations depend on metric expansion. This models are not only the best models that we have available, they are also currently the only ones because every other model so far has been ruled out, everything else has been proved false. Newtonian mechanics is superseded by General Relativity. I am going to repeat a small part of the quotes from my first post in this thread: Scientists have tested carefully whether these assumptions are valid and borne out by observation. Observational cosmologists have discovered evidence - very strong in some cases - that supports these assumptions, and as a result, metric expansion of space is considered by cosmologists to be an observed feature on the basis that although we cannot see it directly, scientists have tested the properties of the universe and observation provides compelling confirmation. Taken together, the only theory which coherently explains these phenomena relies on space expanding through a change in metric. Additionally, scientists are confident that the theories which rely on the metric expansion of space are correct because they have passed the rigorous standards of the scientific method. In particular, when physics calculations are performed based upon the current theories (including metric expansion), they appear to give results and predictions which, in general, agree extremely closely with both astrophysical and particle physics observations. This evidence is taken very seriously because the level of detail and the sheer quantity of measurements which the theories predict can be shown to precisely and accurately match visible reality. The level of precision is difficult to quantify, but is on the order of the precision seen in the physical constants that govern the physics of the universe. http://en.wikipedia.org/wiki/Expansion_of_the_universe#Observational_evidence Farewell cypress, I hope you manage to improve your medieval model to a more modern one some day.

Michel tries to compare the effect with a slowed rotation for Earth.

I think the spin speed has an significant influence, the rotation creates an artificial gravity were buoyancy will force submerged denser objects outward towards the wall.

LOL, If you drive the Virgil with Unobtainium Hull there is no need for roads.

You are trying to change the argument, nobody has claimed that any scientific models are 100 percent foolproof. This is what I said in post #30: "the scientific accepted models might of course be wrong and they are likely to be subject to at least minor revisions when our knowledge and technology advance, to fit with new observations and so on" I have already agreed that the scientific model can be wrong and even that it is likely to need changes. This is not the argument either, I have never claimed that you try to tear down specific models. This is what I said in post #46: "In other words you are disputing the scientific consensus, because they have choosen a model over the alternatives based on assumptions, observations and knowledge" My interpretation is that you do try to miscredit judgements by the scientific consensus. The main argument is whether the science community are correct when they have considered all available assumptions, observations and knowledge and came to this conclusion: "Taken together, the only theory which coherently explains these phenomena relies on space expanding through a change in metric". You have made several repeted claims throughout the thread, that there exists alternatives, other serious valid competing models, which is false and goes against the scientific consensus. Secondly you claim that we can't validate assumtions, but the assumtions that goes into a model are tested together with the models and if a model past the test then the assumptions also have. Thirdly you seem to think that the scientific consensus don't rely on the scientific method and are instead some cind of popularity contest based on peoples opinions which is very wrong. ---------- You have also made a whole slew of other claims that are clearly false and of which you have not yet provided any evidence or admitted that you were wrong thereof: Wrong, according to the theory of General Relativity. Wrong, according to the theory of Big Bang. Wrong, according to scientific consensus there is no known universal gravitational center in space. Wrong, the Universes shape or size is certainly not known according to scientific consensus. Wrong, according to the Copernican principle we are not privileged observers. Wrong, according to the theory of Big Bang. ---------- In summary, you are disputing the scientific consensus on several important cosmological points and have clearly tried to undermine its credibility by suggesting choosen assumptions and models are not tested but instead depends on opinions and popularity. And to all of this crap, you have supported the mighty evidence of your empty words... (In contrary to the massive evidence behind scientific consensus.) Conclusion: Your claims are not to be trusted and you have failed to provide any evidence at all for your case.

I am truly sorry if you got hurt from my joke and therefor apologize. But to my excuse I must say that you were asking a seemingly scientific question in the General Discussion area and explicit asking us to explain it without the scientific reasonable explanation thereof.

There is a secret circular rail track for every planet placed in the orbits. The track has cogged sides and goes straight through the planets. Inside the planets there exists a hidden mechanism with cogwheels and springs. Deep down in the core lies the central engine fueled by magic from fairies and powered by mighty trolls. (It's emitting the gravity we observe here on Earth only as a small side effect.)

In other words you are disputing the scientific consensus, because they have choosen a model over the alternatives based on assumptions, observations and knowledge. A lot of things will always remain unknown, if no assumptions is allowed to stand then like swansont said you can toss all science and knowledge. If you accept the scientific consensus then I suggest you take the scientific answer and be content with it. The factually correct scientific explanation has been given to you. If you want to dispute any of the assumptions, observations or knowledge that is included in the conclusion made by the scientific community, I suggest you start to specify your arguments against it and support it with reputable references for any evidence you will use. You have yet to show that there exists any valid alternatives and when you do, (actually if, which I doubt), the debate will be about which one has most evidence supporting it, not whatever people favor. Ok, let's do that: Please back up your claim that General Relativity prevents space from expanding faster than light speed. (or do you have a different Theory of Relativity than the scientific community?) Your first purpose seems to be to use incorrect knowledge of the Theory of General Relativity to argue that The Bear's Key was wrong. But by doing so you also accepted that the underlying assumtions that goes into General Relativity are correct. Your purpose after that is not so clear, the entire discussion that followed from your initial post seems to be focused on the purpose for you to avoid admitting that you were wrong from the beginning. Once again, You have failed to provide ANYTHING other than your own words.

"the two forces that are presented to the turnarounds by the 100 kg mass will cancel each other out and the force that was used to accelerate the 100 kg mass will propel the spacecraft." a theory concerning space propulsion But if you accept the velocity reduction provided then you should realize that the two U-turns will no longer balance out.

The world that we live in are not simple or easy to understand and as such it can take a lot of time to explain complicated models. That does not mean that persons are stupid or that there are no uses for these models. If people are saying that you are not clever enough or that the theory is to complicated, then to me, that only indicates that they don't want to spend their time educating you, (or that they don't fully understand it themselves). Relativity has been tested and found to be correct, there exists scientific facts and evidence. In normal everyday life we don't need the precision of relativity and ordinary Newton mechanics will suffice, we can travel to the Moon with Newton alone, but we can not accurate predict Mercury's orbit without Einstein. If you really want to and spend time researching and reading you will start to get an "simpler" understanding thereof and there is nothing saying that you can't become an expert, if thats your wish. Here are some Links for you to read and then you can come back with more specific questions: http://en.wikipedia.org/wiki/Tests_of_general_relativity http://en.wikipedia.org/wiki/Principle_of_relativity http://en.wikipedia.org/wiki/Special_relativity http://en.wikipedia.org/wiki/General_relativity http://en.wikipedia.org/wiki/Albert_Einstein

Word twisting, this is what I said which everyone clearly can see in my post #41 above: "It is established knowledge by the scientific consensus that alternate models that doesn't include metric expansion can't explain all observed phenomenas. It is also established by the scientific community that we don't know the total size or shape of the Universe, that the Universe don't have any gravitational center, that the Big Bang was not a traditional explosion with a blast front moving through space or that the Earth is not placed in a central specially favored position. I have supported evidence that all this, (above), are the mainstream view according to the scientific community. (Together with explanations and references thereof.)" Do you dispute the accuracy of the claims made by the scientific consensus? This is clearly very false, you are twisting words again and trying to hide the real argument. It is very relevant to the argument if ideas are accepted by the scientific community or not. I already told you in post #34 that this is NOT some random popular opinion, it is the model accepted by the scientific community. Their judge does have some more weight and I even tried to explain it further in my post #41 above: "The mainstream models and any other accepted model is constantly tested in accordance with the scientific method and as such they get revised or scrapped with new observational evidence. The only models that survive are those that can withstand the rigorous scrutiny from other scientists and valid repetable tests. Therefor the current mainstream models approved by the scientific consensus have a much higher probability to be correct than any wild guesses pulled straight out of the air by unknown random strangers on the internet." If you are on some strange crusade against the scientific consensus or the scientific method and want to contest their credibility I suggest you start another thread for that purpose. This thread is in the subforum "Sciences" and "Physics" where scientific fact and mainstream physics rule. You can repeat this how many times you want but it will still not be true, I have showed you the scientific answer. Everything is not known and some parts might be wrong but "Taken together, the only theory which coherently explains these phenomena relies on space expanding through a change in metric" does not mean that we are in the dark and not knowing anything. It does NOT mean that we don't know, it means that we have some evidence and some knowledge and when adding everything up these points towards an scientific explanation. The explanation might even turn out wrong later when more observations and discoveries turns up. But right now, at the present it is the summary of what we actually do know, it is the factually correct scientific explanation. No you have NOT, I clearly asked you for any reference or evidence at all in post #41 above, which you have not provided. All you have suggested is ONE model, that also happens to be your own private pet idea which clearly goes against mainstream science. I repeat: Back up your claim that the Universe is finite and has a gravitational center, at which the Earth is placed with a blast front advancing outward. Once again, You have supported NOTHING other than your own words. You may have meet your own requirements, but in my view all you have done is rambling. And yet you fail to provide any links to these "alternatives readily available on the web"... Questioning the scientific consensus is outside the scope of this thread and best fit in its own thread, in some other subforum. Back in post #30 I said: "If I tell you that something is accepted by the science community, all I need to do is support a link to where that is stated. If it is already accepted by the science community then I don't have to prove it for you again, there already exists evidence for the claim." Do you dispute my claim that what I have supported are the scientific consensus? I summary you are just babbling without any support at all.

A lightray going from the Earth to the Moon will be redshifted for an observer in a spaceship orbiting Earth relative an observer on Earths surface due to difference in gravity. And it will be blueshifted for an observer standing on the Moon relative the observer in the spaceship, but relative the observer on Earth it will be redshifted since the gravity well is deeper close to Earth than close to the Moon. In General Relativity there are three cinds of redshifts: Relativistic Doppler caused by a speed difference, Cosmological Redshift caused by expanding space and Gravitational Redshift due to differences in gravitational fields. When measuring redshifts from distant objects it's likely that all three effects are involved and stacked upon each other to some degree. Redshift In physics (especially the physics of astronomical objects), redshift happens when light seen coming from an object is proportionally shifted to appear more red. Here, the term "redder" refers to what happens when visible light is shifted toward the red end of the visible spectrum. More generally, where an observer detects electromagnetic radiation outside the visible spectrum, "redder" amounts to a technical shorthand for "increase in electromagnetic wavelength" — which also implies lower frequency and photon energy in accord with, respectively, the wave and quantum theories of light. Redshifts are attributable to three different physical effects. The first discovered was the Doppler effect, familiar in the changes in the apparent pitches of sirens and frequency of the sound waves emitted by speeding vehicles; an observed redshift due to the Doppler effect occurs whenever a light source moves away from an observer. Cosmological redshift is seen due to the expansion of the universe, and sufficiently distant light sources (generally more than a few million light years away) show redshift corresponding to the rate of increase of their distance from Earth. Finally, gravitational redshifts are a relativistic effect observed in electromagnetic radiation moving out of gravitational fields. Conversely, a decrease in wavelength is called blue shift and is generally seen when a light-emitting object moves toward an observer or when electromagnetic radiation moves into a gravitational field. http://en.wikipedia.org/wiki/Redshift

The Event Horizon of a Black Hole is not a real physical object, it is a mathematical calculated boundary in space, of where the escape velocity is equal to the speed of light in Newton mechanics and in Einstein relativity where spacetime is so curved that the future of infalling objects is towards the center. 1. General Relativity thrumps Newton mechanics, once at the Event Horizon or below it is no longer possible to escape even shortly to a small distance. To do so would require moving faster than the speed of light. 2. The Event Horizon is formed by the gravity of the Black Hole, further out there is a Photon Sphere consisting of orbiting lightrays, which also is caused by the Black Holes gravity. 3. An Black Hole is constantly trapping lightrays inside its Event Horizon and it doesn't matter whether two lightrays are parallel or not, if one or both pass the Event Horizon then they are caught inside. Also lightrays don't have the possibility to push each other towards a Black Hole. 4. A photon might be able to hover at the exact radius of the Event Horizon for a very short while, if it is going straight out from the center, but as soon as the Black Hole consumes anything the Event Horizon will grow surpassing the photon and it will be lost inside. 5. According to Newton mechanics and General Relativity once a Black Hole has formed it will only continue to grow, but with Quantum mechanics there are other possibilities. I don't think Hawking radiation is confirmed yet, but even so, a normal sized Black Hole would absorb far more cosmic microwave background radiation than it emits. I think you might be mixing up parallel lightrays with the particle-antiparticle radiation mentioned in the Hawking radiation process. Here are some Links with further reading: http://en.wikipedia.org/wiki/Event_horizon http://en.wikipedia.org/wiki/Black_hole http://en.wikipedia.org/wiki/Hawking_radiation http://en.wikipedia.org/wiki/Photon_sphere

Earth is not enclosed inside a huge container where stuff are affected by friction against the bottom or the walls.

As I understand relativity, you can not single out one specific effect and consider how that would impact reality, every effect of relativity needs to be transferred when switching frames. When relativity is applied properly a physical event is either possible or impossible equally in all frames. If it's possible in one frame then it's possible in all frames and similar if it's impossible in one frame then it's impossible in all frames. The laws of nature applies to all frames so Sisyphus can slide into his "pancake" car and accelerate for a trip in any distant observer's view. Different observers might disagree on his size, mass, speed, acceleration, how long time the trip took and when the trip did happen, but they will all agree on that he actually made the trip and which roads he choosed during the travel.

Well, your professor is correct then, since the ONLY theory we have that is able to explain all our observations of the Universe depends on a metric expansion of space. There are currently no serious alternatives considered among the scientific community, so it is the "alfa" model of the Universe. The Big Bang The Big Bang is the prevailing cosmological theory of the early development of the universe. Cosmologists use the term Big Bang to refer to the idea that the universe was originally extremely hot and dense at some finite time in the past and has since cooled by expanding to the present diluted state and continues to expand today. The theory is supported by the most comprehensive and accurate explanations from current scientific evidence and observation. http://en.wikipedia.org/wiki/Big_Bang Observational evidence Theoretical cosmologists developing models of the universe have drawn upon a small number of reasonable assumptions in their work. These workings have led to models in which the metric expansion of space is a likely feature of the universe. Chief among the underlying principles that result in models including metric expansion as a feature are: - the Cosmological Principle which demands that the universe looks the same way in all directions (isotropic) and has roughly the same smooth mixture of material (homogeneous). - the Copernican Principle which demands that no place in the universe is preferred (that is, the universe has no "starting point"). Scientists have tested carefully whether these assumptions are valid and borne out by observation. Observational cosmologists have discovered evidence - very strong in some cases - that supports these assumptions, and as a result, metric expansion of space is considered by cosmologists to be an observed feature on the basis that although we cannot see it directly, scientists have tested the properties of the universe and observation provides compelling confirmation. Sources of this confidence and confirmation include: - Hubble demonstrated that all galaxies and distant astronomical objects were moving away from us, as predicted by a universal expansion. Using the redshift of their electromagnetic spectra to determine the distance and speed of remote objects in space, he showed that all objects are moving away from us, and that their speed is proportional to their distance, a feature of metric expansion. Further studies have since shown the expansion to be extremely isotropic and homogeneous, that is, it does not seem to have a special point as a "center", but appears universal and independent of any fixed central point. - In studies of large-scale structure of the cosmos taken from redshift surveys a so-called "End of Greatness" was discovered at the largest scales of the universe. Until these scales were surveyed, the universe appeared "lumpy" with clumps of galaxy clusters and superclusters and filaments which were anything but isotropic and homogeneous. This lumpiness disappears into a smooth distribution of galaxies at the largest scales. - The isotropic distribution across the sky of distant gamma-ray bursts and supernovae is another confirmation of the Cosmological Principle. - The Copernican Principle was not truly tested on a cosmological scale until measurements of the effects of the cosmic microwave background radiation on the dynamics of distant astrophysical systems were made. A group of astronomers at the European Southern Observatory noticed, by measuring the temperature of a distant intergalactic cloud in thermal equilibrium with the cosmic microwave background, that the radiation from the Big Bang was demonstrably warmer at earlier times. Uniform cooling of the cosmic microwave background over billions of years is explainable only if the universe is experiencing a metric expansion. Taken together, the only theory which coherently explains these phenomena relies on space expanding through a change in metric. Interestingly, it was not until the discovery in the year 2000 of direct observational evidence for the changing temperature of the cosmic microwave background that more bizarre constructions could be ruled out. Until that time, it was based purely on an assumption that the universe did not behave as one with the Milky Way sitting at the middle of a fixed-metric with a universal explosion of galaxies in all directions (as seen in, for example, an early model proposed by Milne). Yet before this evidence, many rejected the Milne viewpoint based on the Mediocrity principle. Additionally, scientists are confident that the theories which rely on the metric expansion of space are correct because they have passed the rigorous standards of the scientific method. In particular, when physics calculations are performed based upon the current theories (including metric expansion), they appear to give results and predictions which, in general, agree extremely closely with both astrophysical and particle physics observations. The spatial and temporal universality of physical laws was until very recently taken as a fundamental philosophical assumption that is now tested to the observational limits of time and space. This evidence is taken very seriously because the level of detail and the sheer quantity of measurements which the theories predict can be shown to precisely and accurately match visible reality. The level of precision is difficult to quantify, but is on the order of the precision seen in the physical constants that govern the physics of the universe. http://en.wikipedia.org/wiki/Metric_expansion_of_space While space is not totally empty it is still very close to a vacuum, which means that there are very very little matter in the voids outside galaxies. It follows that very little matter also has a very small impact and can thus be neglected. Even something as big and massive as a vandering star that happens to get to close, would simply be dragged along and forced to join the galaxy and its rotation, without the galaxy slowing down any measurable level. Outer space (often simply called space) is the void that exists beyond any celestial body including the Earth. It is not completely empty (i.e. a perfect vacuum), but contains a low density of particles, predominantly hydrogen plasma, as well as electromagnetic radiation, magnetic fields, and neutrinos. Intergalactic space is the physical space between galaxies. Generally free of dust and debris, intergalactic space is very close to a total vacuum. The space between galaxy clusters, called the voids, is probably nearly empty. Some theories put the average density of the Universe as the equivalent of one hydrogen atom per cubic meter. The density of the universe, however, is clearly not uniform; it ranges from relatively high density in galaxies (including very high density in structures within galaxies, such as planets, stars, and black holes) to conditions in vast voids that have much lower density than the universe's average. Surrounding and stretching between galaxies, there is a rarefied plasma that is thought to possess a cosmic filamentary structure and that is slightly denser than the average density in the universe. This material is called the intergalactic medium (IGM) and is mostly ionized hydrogen; i.e. a plasma consisting of equal numbers of electrons and protons. The IGM is thought to exist at a density of 10 to 100 times the average density of the universe (10 to 100 hydrogen atoms per cubic meter). It reaches densities as high as 1000 times the average density of the universe in rich clusters of galaxies. http://en.wikipedia.org/wiki/Outer_space

While special relativity constrains objects in the universe from moving faster than the speed of light with respect to each other, there is no such theoretical constraint when space itself is expanding. It is thus possible for two very distant objects to be moving away from each other at a speed greater than the speed of light (meaning that one cannot be observed from the other). The size of the observable universe could thus be smaller than the entire universe. It is also possible for a distance to exceed the speed of light times the age of the universe, which means that light from one part of space generated near the beginning of the Universe might still be arriving at distant locations (hence the cosmic microwave background radiation). These details are a frequent source of confusion among amateurs and even professional physicists. http://en.wikipedia.org/wiki/Metric_expansion_of_space

A tale of two big bangs Whenever you hear or read about cosmology, there is one distinction you should have in the back of your mind - otherwise, matters might get a bit confusing: The term "big bang" has two slightly different meanings, and the answer to questions like "Did the big bang really happen" depends crucially on which of the two big bangs you are talking about. Did the big bang really happen? If you are talking about the big bang phase, the hot early universe as described by well-known physical theories (or, if you include inflation, by extrapolation from those theories), then there is good evidence that, yes, nearly 14 billion years ago, the cosmos developed in just the way described by the cosmological models (the main exhibits are the original abundances of light elements as deduced from astronomical observation, the distribution of far-away galaxies and the existence and properties of the so-called cosmic background radiation). Whether or not there really was a big bang singularity is a totally different question. Most cosmologists would be very surprised if it turned out that our universe really did have an infinitely dense, infinitely hot, infinitely curved beginning. Commonly, the fact that a model predicts infinite values for some physical quantity indicates that the model is too simple and fails to include some crucial aspect of the real world. Thus, while some cosmologists do not have a problem with assuming that our universe began in a singular state, most are convinced that the big bang singularity is an artefact - to be replaced by a more accurate description once quantum gravity research has made suitable progress. To be replaced with what? Nobody knows for sure. In some models, we can go infinitely far into the past (one example is presented in the spotlight text Avoiding the big bang). In others, the big bang is replaced by a beginning of the universe which avoids all infinities, but in which time itself is rather different from what we are used to (some more information about this can be found in the spotlight text Searching for the quantum beginning of the universe). http://www.einstein-online.info/spotlights/big_bangs/?set_language=en Galactic spiral arms Originally, astronomers had the idea that the arms of a spiral galaxy were material. However, if this were the case, then the arms would become more and more tightly wound, since the matter nearer to the center of the galaxy rotates faster than the matter at the edge of the galaxy. The arms would become indistinguishable from the rest of the galaxy after only a few orbits. This is called the winding problem. Lin and Shu proposed in 1964 that the arms were not material in nature, but instead made up of areas of greater density, similar to a traffic jam on a highway. The cars move through the traffic jam: the density of cars increases in the middle of it. The traffic jam itself, however, does not move (or not a great deal, in comparison to the cars). In the galaxy, stars, gas, dust, and other components move through the density waves, are compressed, and then move out of them. More specifically, the density wave theory argues that the "gravitational attraction between stars at different radii" prevents the so-called winding problem, and actually maintains the spiral pattern http://en.wikipedia.org/wiki/Density_wave_theory

I don't think anything will ever be totally beyond doubt and my personal view of the world is not written in stone, I constantly revise and modify it when I learn something new so that it continues to reflect my current knowledge. A lot of people might disagree but what I have posted here is not my own personal pet theories, it is the mainstream view established by the scientific community and as such it is backed up with a lot of evidence, made from prime observations by state of the art technological equipment according to our best knowledge. Even people that disagree need to listen, learn and understand because any alternative models must be able to explain the observations we make.

It is established knowledge by the scientific consensus that alternate models that doesn't include metric expansion can't explain all observed phenomenas. It is also established by the scientific community that we don't know the total size or shape of the Universe, that the Universe don't have any gravitational center, that the Big Bang was not a traditional explosion with a blast front moving through space or that the Earth is not placed in a central specially favored position. I have supported evidence that all this, (above), are the mainstream view according to the scientific community. (Together with explanations and references thereof.) You have supported nothing... You can disagree all you want but without any reference or links to reputable resources like Wikipedia, all you have is your word, which is not worth much on the internet. You seem to try to discredit Wikipedia, but even if some details might be wrong or missing, the articles themself has refererences to named reliable professional scientists and their individual work in much more detail. If there exists any slightly creditable alternative model at all, it can usually be found in there too. The mainstream models and any other accepted model is constantly tested in accordance with the scientific method and as such they get revised or scrapped with new observational evidence. The only models that survive are those that can withstand the rigorous scrutiny from other scientists and valid repetable tests. Therefor the current mainstream models approved by the scientific consensus have a much higher probability to be correct than any wild guesses pulled straight out of the air by unknown random strangers on the internet. So far you have failed to provide any evidence at all for your "medieval" model. I gave you all the evidence you need with references, if you don't want to read and learn it's your choice. I forgive you but I won't waste time trying to convince you against your belief. Feel free to post a link to any reputable source that claims otherwise. ---------- Back up your claim that the Universe is finite and has a gravitational center, at which the Earth is placed with a blast front advancing outward.

1) Before the Recombination, thought to have occurred about 377,000 years after the Big Bang, the Universe was to "foggy" to let light through but after it became transparent. The Cosmic Microwave Background Radiation that we can observe today is the remnant of this first free light traversing the Universe. 2) We have observed six star forming galaxies created about 500 million years after the Big Bang. Link: http://en.wikipedia.org/wiki/Timeline_big_bang

The Big Bang was NOT an regular explosion of matter inside space, it was more like an explosion of space between matter. While it is correct that we only can observe a certain limited size of the Universe, due to time since the Big Bang and the speed of light, the total Universe is likely much much bigger than we can currently see. The Big Bang The Big Bang is not an explosion of matter moving outward to fill an empty universe. Instead, space itself expands with time everywhere and increases the physical distance between two comoving points. Because the FLRW metric assumes a uniform distribution of mass and energy, it applies to our Universe only on large scales—local concentrations of matter such as our galaxy are gravitationally bound and as such do not experience the large-scale expansion of space. http://en.wikipedia.org/wiki/Big_Bang MISCONCEPTIONS about the BIG BANG The key to avoiding the misunderstandings is not to take the term “big bang” too literally. The big bang was not a bomb that went off in the center of the universe and hurled matter outward into a preexisting void. Rather it was an explosion of space itself that happened everywhere, similar to the way the expansion of the surface of a balloon happens everywhere on the surface. http://www.mso.anu.edu.au/~charley/papers/LineweaverDavisSciAm.pdf Universe Current interpretations of astronomical observations indicate that the age of the Universe is 13.75 ±0.17 billion years, and that the diameter of the observable universe is at least 93 billion light years, or 8.80 × 1026 metres. Since we cannot observe space beyond the limitations of light (or any electromagnetic radiation), it is uncertain whether the size of the Universe is finite or infinite. http://en.wikipedia.org/wiki/Universe Observable universe Both popular and professional research articles in cosmology often use the term "Universe" to mean "observable universe". This can be justified on the grounds that we can never know anything by direct experimentation about any part of the Universe that is causally disconnected from us, although many credible theories require a total Universe much larger than the observable universe. No evidence exists to suggest that the boundary of the observable universe corresponds precisely to the physical boundary of the universe (if such a boundary exists); this is exceedingly unlikely in that it would imply that Earth is exactly at the center of the Universe, in violation of the Copernican principle. It is likely that the galaxies within our visible universe represent only a minuscule fraction of the galaxies in the Universe. According to the theory of cosmic inflation and its founder, Alan Guth, the lower bound for the diameter of the entire Universe could be at least in the range of 1023 to 1026 times as large as the observable universe. http://en.wikipedia.org/wiki/Observable_universe

So the claims of other alternative coherent models turns out to only be your own unsupported personal opinion, which in fact is also proved to be false. Copernican principle In physical cosmology, the Copernican principle, named after Nicolaus Copernicus, states that the Earth is not in a central, specially favored position. More recently, the principle has been generalized to the relativistic concept that humans are not privileged observers of the universe. Confirmation Measurements of the effects of the cosmic microwave background radiation in the dynamics of distant astrophysical systems in 2000 proved the Copernican principle on a cosmological scale. The radiation that pervades the universe was demonstrably warmer at earlier times. Uniform cooling of the cosmic microwave background over billions of years is explainable only if the universe is experiencing a metric expansion. http://en.wikipedia.org/wiki/Copernican_principle