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    I Silly question on the relativity of simultaneity

    Something that I consider very silly, yet I try to solve relates to the relativity of simultaneity. According to SR , two evevnts taking place in different positions along the line of relative motion of two inertial observers are not simultaneous in both frames. Now, I wanted to see how this...
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    Certificate in creating virtual labs?

    Hello, I want to learn how to create virtual labs (html5, java and on) for physics education purposes. I could work on my own, but I am more interested in getting a solid background from experts. Is there any online course in which I could enroll? Thank you
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    How is physics knowledge used in everyday life?

    I am a rather bad case for answering this as my work is mainly focused on designing educational scenarios on STEM and doing teacher training. So I do Physics more or less most of my time :-p To draw the students' attention to Physics I try to find something that intrigues them and then forge...
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    Other PhD advice

    thank you
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    Other PhD advice

    Thank you very much. It seems to be exactly what I am looking for. Do you happen to know if similar opportunities exist in Europe?
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    Other PhD advice

    Hello. I am a Physicist with MSc in Experimental Particle Physics and for the last 3 years I work in the field of Science Education as a teacher trainer, and developer of inquiry based, ICT enhanced educational content in the field of Physics for K12 students in the RnD department of a school in...
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    Sound Loudness vs Pitch Misconception

    Hello everybody. I am involved in a project aiming to address Physics Misconceptions regarding Sound through the creation of virtual musical instruments. One of the major student misconceptions I have found in bibliography is the fact that students perceive sound pitch and loudness as being the...
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    I Is the top quark stable in the absence of the Higgs field?

    This means that in a Higgsless universe you would not have 3 neutrino flavors also?
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    Torque Intuition

    Perhaps there is another way to depict it but you need to know some physics first. Assume that you have a spinning wheel rotating at constant angular velocity (ω). Now, if you start acting on it with a tangential force, then it starts speeding up. Its angular velocity increases with time...
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    On the concept of mass

    The relativistic increase in mass is due to the fact that at high speeds (u->c) the mechanics you use are relativistic. The term invariant mass is the correct one - a question: how would you define mass in a proper textbook format? E.g I would say that mass is the energy of an object observed...
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    High energy neutrino telescopes

    By "do that" you mean increase the effective area in such a way that you could observe astrophysical signals? First things first: When one tries to do neutrino physics without accelerators or reactors, (or geoneutrinos =>just saying for completeness) the possible signals come from the...
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    High energy neutrino telescopes

    Not quite to me, even though we should agree that this is just a matter of terminology. E.g SNO, or Super Kamiokande cannot be referred to as neutrino telescopes since they cannot observe astrophysical sources of neutrinos ( it is just solar neutrinos and atmospherics ). A neutrino telescope...
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    High energy neutrino telescopes

    Hello, I am opening this thread so as to discuss if possible what you believe is the science case of building a neutrino telescope. Being a fanatic in the field , I would like to hear opinions from whoever wants to say about whether it is important to build such a detector and why. Thank you!
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    Threshold, proton-proton-collision

    Sorry, but the Kaon reaction you write doesn't conserve electric charge
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    Is there a limit to how much energy can be stored in a photon?

    About the GZK cutoff, yes it exists (or so we believe) which prohibits us from observing protons more energetic than 6*10^19 eV (taken that the interaction length of the proton in the CMB is lower than the proton source- earth distance). Of course, there might be a way for a (e.g)10^25eV proton...
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    Is there a limit to how much energy can be stored in a photon?

    Well, about high energy gammas, the most energetic ones are produced in violent phenomena in the cosmos. (e.g in AGN's , GRBs etc). There are also photons produced in the p+γ(CMB)->π0 +p, π0->γγ The maximum energy gained by photons this way is of order ~10^19 eV. The gammas however...
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    Intuitive, real-world explanation of displacement current?

    Hello, the problem that one has to see in order to intuitively comprehend displacement currents is the charging of a capacitor. When one starts charging it current flows towards the high voltage plate, but it cannot proceed towards the low voltage one. In order the 'charging' to make sense, the...
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    Ampere's Law physical significance

    physwizard, woopydalan sorry ,messed up the names:P Woopydalan, the fundamental 'observation' is that the magnetic field appears when we have charges with nonzero velocity and that it 'circles' the charges' trajectory. The circles grow sparser as distance from the moving charges increase...
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    Ampere's Law physical significance

    Dear physwizard, you questions were: - I am confused as to the physical significance of the dot product of B and ds. Why would we evaluate this scalar product. My textbook has it on here without any motivation for it. - was saying a physical significance, because I don't understand math as...
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    Ampere's Law physical significance

    First of all you need to understand that Ampere's law is Biot-Savart's law applied in problems where there is an underlying symmetry => thus the physics is the same , yet the math is more beautiful and elegant leading to well phrased physics results. There is a heuristic way to present the...
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    Magnetic field and force

    Hello, Philip the nr.3 example is the BEST one could refer to in order to explain the magnetic force concept:)
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    Uncertainty of experiment relative or absolute

    A quick and dirty way to understand what you ask is to see if the uncertainty has units. If yes it is absolute (e.g in Mikey's example 10+/- 1 sec , the error=1 is measured in seconds=>absolute). Else, if you measure the error/mean this is the relative uncertainty -> it is dimensionless
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    Can neutrinos cause Cherenkov radiation?

    The by products of neutrino interactions (charged leptons) emit Cherenkov radiation when they have speed > speed of light in the medium they propagate. NOW, if you want to discuss Cherenkov radiation in vacuo of apparent superluminal neutrinos (such as those proposed by OPERA some months ago)...
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    Speed of light and snell's law

    David, Yes!
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    A confusion in work and potential energy

    Take the interpretation I gave you and consider that the work one needs to do in order to move a positive charge from infinity to some distance from the source (for two same charged particles) is positive. Else it is negative
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    A confusion in work and potential energy

    Sure! Suppose that you have a source particle at x=0 You have your test particle in x=>00 and you want to move it from there to x=R from the source
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    Direction of friction in rolling.

    Well, the point is that you talk about 'static' friction here. It doesn't quite work the way the 'sliding'(?) friction does. Meaning that since the body goes up it loses kinetic (rotational and translational) energy and gains potential energy. Translational energy is lost by the gravitational...
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    What is a neutron? (if not an electron inside a proton)

    Well, if you consider the neutron as an electron-proton bound state then you have two problems: 1) The energy of the beta decay is of order 1 MeV, whereas the energy of an electron emitted by tunneling would be E~hbar/1fm which will correspond to ~200 MeV 2) The spin of the neutron is 1/2...
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    Speed of light and snell's law

    The color has to do with frequency and therefore energy from what I get (E=hf) The wavelength has to do with momentum (p=h/λ) When we change medium, speed changes and momentum changes so that by E=pc energy is conserved!
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    A confusion in work and potential energy

    From the definition I know, when the work is done by the field spontaneously then it is positive, else if we do it it is negative. Therefore for to same charged particles to approach, work is negative (we give our own muscles' energy) and this energy is absorbed by the field as the potential...