timo

Please give some additional information when linking to some news. You should really know by now that posting links without any additional information, a short description of the content and some starting point for a discussion (like your opinion about it) violates the forum rules.

Small remark: I haven´t read it up, but I am almost sure it should read: If there were hidden variables, then the inequalities would hold. Not the other way round as you wrote it (note the difference!).

W is the number of microstates associated to a macrostate. In the example of your colored balls, W for the unmixed case is the number of ways you can arrange the balls to be seperated by color and W for the mixed case is the number of ways you can arrange the balls to be mixed.

At some point you should ask yourself what light or a photon actually is. For what light is, I cannot really give you a good answer so let´s stick to the photons and start from the very basics: There is something called the "electromagnetic field". Being a field, that means that it is a function that has a certain value (not nessecarily a real- or complex-valued one, it can also be vectors, tensors or even anything else) on every point of space(-time). To some extend, this field is all there is if you ignore that you want field equations, interaction of this field with matter/other fields and at some point also quantization of the field. Think of it as the surface of the ocean. If you assign a water-height to every point of the ocean-surface, you have completely described it. Field equations would be something like the time-evolution of waves, interaction with other matter would be the wind blowing on and creating waves, .... let´s ignore quantization . The height-field of the water is a function f: R² x R -> R ("x R" for time). You can easily compose it as a sum of different functions: f = f1 + f2 + ... .This can be handy, e.g. if you are a surfer. As a surfer, you are not interested in the height of the water at any point, but in the waves rolling towards the beach. So you would compose the field of functions which each represent some object that makes sense for your application (surfing): An object you intuitively call a wave. If you´re rather interested in the moon causing tides, you´d probably take different functions to make up the height-field f. So the choice of these f_i is pretty much arbitrary as they are just some helper-functions that simplify calculations (timing in the case of surfing). To get the connection to photons: They are basically such basic components of the electromagnetic field and therefore their choice is arbitrary to some degree and depends on what you are actually interested in. So the shape of a photon is exactly the shape that you assign to it, the most common choice being a plane wave (for being an eigenstate to the momentum operator).

Given that the visible matter evidently does form structures on different scales (solar systems, galxies, clusters, superclusters), I would acutally EXPECT dark matter to also form any kind of structures. Afaik, computer simulations for the distribution of dark matter have been done and do show structure formation. Dunno which model assumptions went into the models, though. Wim de Boer gave some possible explanation for the distribution of dark matter (which is basically a computer simulation of a cloud of gas gravitationally attracted by a galaxy, as far as I can see that). Maybe his talks (which all seem to be the same one augmented to the time he had) might be interesting for you: http://www-ekp.physik.uni-karlsruhe.de/~deboer/ Lemme add the personal comment that I´ve heard the talk twice. First time I was absolutely impressed that someone has actually "seen" dark matter. Second time I was a bit more sceptical for some details which hopefully are minor. One would be the question why dark matter distribution is the cause of some dark matter being attracted by an already-existing galaxy - why doesn´t the structure formation of dm and ordinary matter happen at the same time?. Perhaps the other charged matter attracted it more? I cannot answer the question but structure formation is a topic where I would trust simulations much more than intuition.

There are hacks to do that. But given it is hacks, I wonder about the legal status of what you are planning to do.

There´s a much easier way to check the sanity of experiments: Make it a demand that the person submitting the experiment actually did the experiment before. Just add the lab report and a results report. Rather than a collection of great ideas what one COULD do, I think a place for people to publish the results of their experiments they HAVE DONE causes a lot less headaches and bad content.

Which was a stupid idea from the very beginning on. If I want to look up definition, I take a dictionary. Perhaps an online-dictionary like ... well ... you can guess it (hint: The one that all not completely crappy articles are copied-pasted from). I do understand that. My point was not "that would fit good to WiSci" but rather "thart would at least be a non-redundant use for the WiSci infrastructure". WiSci is, taking out the biology articles which I cannot judge, a junkyard at best. The best thing WiSci ever brought up so far is that letter about some creationist video. While I dislike the idea of the letter, dislike the "we enlightened scientists step down from our high throne to point out your mistakes"-attitude coupled to the fact that all writers are pupils and also have some doubts about actual content, it is at least something original and in theory a great team-project. The letter is "almost finished" for several weeks now, I think. You are not worse in contributing to WiSci than anyone else - probably even better because you at least try to write something instead of copying articles about quantum field theory from wikipedia and asking someone (in the sense of "anyone, please") to please adjust it to the standards of WiSci. But let´s even assume WiSci was an ok site: Why not just create pages like you´d expect them to be in a suitable namespace of WiSci? You can still copy&paste them somewhere else if that project grows so much much that the wikipedia software can´t handle it anymore . As a general comment, which I am absolutely serious about and what you should see as a friendly advice (as opposed to above rantish style...): SFN has quite a record of abandoned projects. Especially on the internet, the main reason for projects to die off is setting non-tiny goals and making great plans of how it should be/work. Bashing WiSci once more: I am pretty sure that the amount of thoughts that went into the style guidelines, definition of a scientific point of view and arrangement of the namespaces by far exceeds the amount of thoughts put into the scientific articles. Don´t plan. Do.

*points finger at WiSci* That´s a much better use for WiSci than writing articles about Astronomy dating back to the ancient ages of the Inca or the SI-unit Gramm. Mainly because there´s the hope that people will write about stuff they have some knowledge about (like having performed that actual experiment).

You need to think more out of the box, Bascule.

[math] \forall \, \epsilon<0 \dots [/math]

Indeed:

I´ve get the same prob. Here´s the log from my Java Console, in case someone can make some sense of it:

You really need to be much more careful about your units or formulations: - MeV is not a unit of force - Mass and force do not have the same unit. - "total" is the same as "sum", not the same as "maximum". - The radius is a quantity and doesn´t have any points.

Yes, a new, working theory of gravity that does not need dark matter sounds nice (I´ll stick do dark matter, I know almost nothing about the attempts to explain dark energy). But there´s one thing that you should keep in mind: -> Dark matter is nothing but matter which we can only observe due to its gravitational interaction. What good reason do we have to suppose that there is no matter like that? There´s a lot of possible candiates for dark matter and the reasons why some are more or less ruled out are probably manifold. Some might be disfavoured by current cosmological models. Cosmological models depend on our current understanding of gravity and for the case of explaining dark matter also on our current understanding of particle physics or even guesses of what a possible extension of our current model of particle physics might be. The issue with our current understanding of particle physics is that most people actually expect it to fail for some extreme conditions - conditions that appear at some time in the history of the universe. I don´t know how prone cosmological constraints on dark matter are to that failure of particle physics. In fact, some candidates for dark matter directly come from extensions of our current model of particle physics. You might put "altering our current model of gravity" on the same level as "altering our current model of particle physics", but there is two reasons that make altering the latter seem favourable to me: 1) As I already stated, we actually expect our current model to fail at some point. In other words, we suppose that it´s just an approximation of what a model of particle physics should look like. But there is no real reason to assume a failure of our model for gravity. 2) Dark matter is often supposed to be some new type of yet-unknown matter. In the last ~30 years we have discovered/proven a lot of new particles that were not known before and don´t play any role in everyday-phyics at all because they only appear in very extreme situations and/or have very little interaction with other matter. It does not seem too unlikely that there´s the "dark matter" particle and we just don´t know it, yet. As a last point I would like to note that to my knowledge, there simply is no promising model to replace General Relativity. I don´t know much about MOND, but let alone from the name I would assume that it is not compatible to Special Relativity. The incompatibility of Newtonian Gravity with SR was the reason to come up with GR, after all. Summary: Of course a perfectly working model of gravity which does not need dark matter to explain our observations would be great. But besides that our current model of gravity does seem to work great, I don´t see any promising candidates for an alternative. No one knows what the future will bring, but at the current state I tend to favour dark matter approaches over modified gravitational models. EDIT: While I tried to be objective in above, I should be as fair as to mention that I am heavily biased on that topic for multiple reasons. You should probably keep that in mind when considering what I said.

Reduce the number of links in the left column. "Staff", "Contact Us" and "Contact a Moderator" could as well be the same link. "Forum FAQ" and "SFN Ettiquette" could be merged. "So you´ve got a new theory" could as well be a sticky in the speculations forum. I wonder if someone ever seriously used the "Members List" button. I tend to do a search for the name when I´m looking up someone rather than browsing 150 pages of names.

Some unsorted thoughts to what I consider a good lecture(rer): - Making clear what-for the current stuff is done. That might be a special problem of mine, because I have the tendency to immediately forget stuff I do not consider important (e.g. I usually tend to forget the names of people introduced to me within a few seconds if they are not interesting for me at the time of introduction). Two examples: * Sadly, it is a habit to justify dealing with some theory/concept/technique by saying "it´s needed for QM which you will learn next year". That tells me (the student) absolutely nothing other than "be a good boy and learn it because I tell you to". I think it would be nice to always have a good reason at hand to justify why the current topic is important/interesting. * As a special case, take pertubation theory. Ususally, introductions to it start by directly jumping in and Taylor-expand the hamiltonian and then getting to whatever results. For me as a student, this signals that the whole thing is just an approximation usefull for special cases and that there´s no physics to be learned there *turns brain off*. What no one ever bothered to say is the importance of pertubation theory due to being sufficient to get informations on the underlying physics (physics we do not know by yet and still try to explore) and especially because we simply cannot treat many-particle qm systems up to today other than with pertubation theory (or other ways like DFT which also is an approximation). Admittedly, the more advanced the lecure is, the more difficult the "what it is good for"-part might become and the problem with explaining it is not limited to lectures. When I asked a solid state physicist why they are growing single crystals and make measurements on them, I almost always get the answer "because they have interesting magnetic properties" ... without a "... like the XYZ which ... ". - There´s the tendency to show some theorem or calculation rule in the lecture and then let the students proof them as a homework. Oh how I hate that. If the proof really interests me, then I can look it up myself. Other than that, I usually don´t need the proof at all. I need to know the calculation rule and need to know its validity range and where it´s due to apply. Much better to let the students practice using that rule on (ideally even physical meaningful) examples. I read that "proof it as a homework" as "I am to lazy to think about good examples". People should do calculations in their homework to get used to the topic, not spend their time with proof they will have forgotten a week later, anyways. - Lecture and homework imho should be as easy as possible (but of course as complex as nessecary) and be a good base to start own investigations on, even if it might mean to overstep some possible difficulties (but they should be mentioned, of course). Iirc, I found your lecture notes quite good considering that point. - A lecturer I had had the very nice habit that at the beginning of each lesson he would make a short repeat of what was done in the previous lecture in a sketchy way perhaps using some other notation or way of explanation. I really liked that and it´s one of the few of my lecture notes that I sometimes take a look into today.

The expansion of the universe and therefore also the increase of distances between stars with >c is (using mainstream cosmology/GR) not related to the speed of light at all. Both "speeds" are conceptually totally different. You might have heard about the "rubber-sheet analogy". The universe is considered a band of rubber that is expanded. Therefore, the distance between two points you might have marked on that sheet/band increase. There is actually no fundamental limit on how fast "the sheet is expanded". Velocity in the sense of lightspeed is something different. It´s a local property, which technically means that it locally puts constraints on the directions you can move in spacetime (no need to worry if you don´t understand that sentence, let´s go back to the rubber sheet...). In the rubber-sheet analogy, it is usually visualized by a small animal (small because it´s a local property, as I said - the expansion of the universe shall not notably expand the distance between the creature´s legs) sitting on that rubber sheet and moving along. Since it´s only a normal little ... say spider, it can only move with some maximum velocity, for example c. Since the expansion rate of the rubber sheet is unconstrained, the poor spider can have bad luck and ending up moving slower than the points around it move away from it. Stupid story made short: "The universe expands" does not mean that the stars in the universe travel to already-existing space with overlightspeed. It means that the distances between points increase really fast due to some other weird mechanism (which ultimately is the field equations of GR).

Actually, I wondered about the agressive behavior of many of the players in the tournament. There were a lot of occasions were some rumble broke out (notably the games Portugal<->Holland and Germany<->Argentinia) which made me wonder a bit. Those guys are professionals, some of them earning millions a year (ok, perhaps not the ones involved - but they still are professionals making a good living from their job). I really wonder how those people can act so unprofessional starting fights - they harm their whole team by getting a red/yellow card.

I don´t know for sure but I doubt the validity of that statement. I think scientific breakthroughs "hang in the air" quite long before the point which historically will be considered "the breakthrough" is there. Who is the lonely guy sitting in his appartement all night working out quantum mechanics, for example? Afaik there is none, because it´s been a whole comunity working on it an bringing it step by step to today´s form. Even relativity, which is very tightly bound to the name Einstein, was not invented by Einstein out of nothing. At least the fact that two of the most important tools in (special-)relativity are the "Minkowsky space" and the "Lorentz transformations" makes me think so. Besides: Relativity hang in the air, because it was less a "challenge the conventional wisdom" than an attempt to explain the well-known inconsistencies in available theories. Or let´s take a more up-to-date example: Suppose next week Martin writes a paper where he manages to derive the complete Standard Model of particle physics as a low-energy approximation of Loop Quantum Gravity and also shows that LQG is free of inconsistencies up to arbitrary energies. Let´s furthermore suppose he also manages to make some predictions of where the Standard Model and LQG will give different results and that the LQG results are indeed measured at the Large Hadron Collider in Geneva. Even when you ignore the fact that such a big shot is not likely to be achieved by a single person and that there´s thousands of other people involved in the LHC experiment alone: You probably saw the large amount of LQG papers Martin regularly posts here for discussion. Would Martin fit to your picture of an "individual who questions the status quo and challenges the conventional wisdom"? I am pretty sure in fifty years, that´s what people would think because no one would remember the names of today´s "LQG pioneers" anymore.

Allez les bleus!

Mowgli, I don´t really understand what point you´re trying to make but I think the setup would be much clearer to you if you drew a spacetime-diagram of the system. I´ve done some sketchy version of it from what I understood in your 1st post (see image below). Note that I have tried to keep the distances between the intervals equal but that neither the gamma nor the actual coordinates are calculated out. My proposal to you would be drawing a similar diagram according to your proposed setup and calculate the coordinates of the interesting events. Then, you can transfer them to another frame of reference (like that of the spaceship) using the normal lorentz matrices and see what the diagram looks like in that frame. I assume that would clear most of your questions/irriations.

Also, I think that it might raise the quality of the posts if people realize that they cannot go and edit what they wrote after having had some careful thoughts about it but instead have to do some thinking before they post.

You think the reason is that the mods want to get more PMs ?