timo

There´s a typo at position 5180, it must be a 3 there.

I didn´t live in the days of the ancient greeks, an I´m not really fit when it comes to history of science, but I think that´s true. In fact, from everyday experience it seems only "logical" that you can divide matter arbitrarily if you only had a sufficiently sharp knife.

It´s a bound state of elementary particles called "quarks". Neutrons are part of every atom´s nucleus (except for nomal hydrogen). Without their presence, nuclei wouldn´t be stable. The "usually masses without charges have an equal number of protons and electrons"-part is true for structures the size of an atom or greater. Particles like the proton and the electron are only about 1/100000 the size of a typical atomic diameter. At those scales, there are a lot of particles which are not as widely known as the "classics" proton, electron and neutron. They are -just like the proton and the neutron- bound states of above-mentioned quarks. The quarks do have electric charge and the charge of the bound state will depend on which quarks you combine (ie. the neutron-combination gives charge 0). Besides those bound-quark states, there´s also elementary particles being massive and neutral. The Z-Boson, for example, outweights the neutron by a factor 100 and is neutral, too. Summary: Your statement above is true for size-scales greater or equal than those used in chemistry (-> atomic scale). Below, things become quite different. Yes.

The point was that you said two times are a fraction of wavelength apart. But since time is measured in seconds and wavelength has the unit meters this could have been a hint already that something is wrong or at least incomplete with the statement. The 15 meters where just an arbitrary choice for a distance. I simply stumbled over that statement because it made me think you have plotted three different waves. EDIT: But on 2nd thought I think I know what you meant: Between t1 and t2 the wave has travelled that distance - I simply didn´t understand it initially.

I think you can assume constant velocity for the wave. Take a look at the points (0,0), (3,0) and (6,0). Oh, and btw: You were a bit hasty/confused with your assumptions, I think (or you´re simply a lazy writer): Two times are 15 meters apart? ... and this reply was supposed to be an EDIT ...

I think you can assume constant velocity for the wave. Take a look at the points (0,0), (3,0) and (6,0).

Figuring that out is part of the problem; the blind mathematican wasn´t told that number, either. [hide] 13 is the only number of windows from which the seeing mathematican couldn´t tell the ages; the blind one just has to put a little faith in the skill of his colleague. [/hide]

The relativeness of the term "high temperature" possibly plays an important role. Afaik, in the case of superconductors "high temperature" means "even as high as around -100°C". For the example of electricity-conducting wires you therefore have to ask yourself if the decreased loss of energy due to friction outweights the energy required for the cooling - it probably doesn´t.

The former is true: All experiments you´d do in a rocket moving with a constant velocity relative to earth would yield the same results as the same experiment being done on earth. For both experiments you have to measure in their respective frame of reference (frame of rest). The kind of magnetic fields you speak of are not experienced inside the rocket. In this context, you can think of electromagnetic fields (E-field + B-field) of moving charges being "what an electric field (only E-field) looks like when it´s Lorentz-transformed". And of course, some experiments like "how much time does it take for a stone to fall down to the floor" do give different results and will be pretty boring to do inside the rocket. But that´s because gravity isn´t accounted for in SR.

I´d have questions regarding two of the three sentences quoted in the OP but since the author possibly isn´t among us I´ll strip it down to an answer to what I think is written in these sentences: Physics doesn´t depend on whether you measure distances in meters, miles or diameters of a unit-apple. When you switch to a different unit-system, all equations remain (structurally) the same. Only the values (constants/variables/parameters/number of apple diameters) change.

Perhaps it would help if someone of you would post what the "center of gravity" is ...

The only definition of a black hole that I´d know of is that a black hole is a certain spacetime structure. The strucutre of spacetime is absolute. It might look differently depending from your point of view but it is always the same object. So if the object you were talking about does not form a black hole in its frame of rest, the spacetime structure it creates will not be a black hole. This will be true in any coordiante system (frame of reference), then. The sloppy, incomplete but possibly more satisfying answer would be something like: The Scharzschild Radius gets length-contracted, too.

You can find the nomination by In My Memory including a few links here: http://www.scienceforums.net/forums/showthread.php?t=17190&page=2

I do not know which knowledge was available in Rutherford´s time. What excluded the possibility of having a small hard core of electrons and some positive charges floating around, for example? Even if there was a reason to exclude it, it doesn´t solve the question whether the charge-sign of the hard core can be determined from the Rutherford experiment. But since Swansont mentioned it: The electron probably also was an important discovery. The "Millikan Experiment" played an important role, I think.

I am still not sure on it. Imho, a negatively charged core would have mostly the same effect - it also scatters alpha particles. I think the question is whether you can determine the charge-sign from the angular distribution and/or absorbtion rate of the alphas. If you know the calculation showing that the different trajectories for equally-charged and oppsitely-charged cases result in a measurably different angular distribution for the scattered alphas, please post it here.

Purely equation-wise it´s because of F = ma = G*M*m/r² => a = G*M/r². Then, he multiplied the left-hand side of the equation with a and the right-hand one with GM/r².

Interference would reduce the tidal waves to small fluctuations being rode by surfers. What if people publishing their ultimate theory of everything in internet forums / websites had basic knowledge about modern physics?

I don´t think that many physicists actually work in string theory. Of course it depends on what you call "many" but if you compare the percentage of physics-board visitors interested in (asking and replying to questions about it) string theory and the percentage of physicists dealing with it, then I think the former percentage is much bigger.

Above two answers are related to the "Rutherford Experiment" which demonstrated that an Atom has a small charged hard core - possibly even that this core is positively charged, but I´m not sure about that. A step ahead of this is the proof that matter is actually made of atoms. I think that Brownian Motion was an important dicovery for the atom-model to come to a breakthrough. So http://en.wikipedia.org/wiki/Brownian_motion might be another interesting read for you.

Calculate out the (...)² as (...)*(...) by hand and see why .

Yes. You made an error in above step. The denominator in the second term actually is cos²(x).

It is not really an answer to my question. I can see myself that it´s an energy squared. The problem is that I don´t know which energy squared. The total enery is p+m therefore the total energy squared is p²+2pm+m², not p²+m².

It´s pretty interesting that this link not only redirects me to http://www.google.de but it also gives me a german page as the first result.

2sin(x)+cos(x) has the same periodicity as sin(x) and cos(x) anyways so you can in fact identify all maxima and minima.