Physical Definition and 1000 Threads

As I recall, Rovelli never published anything about DSR until August 2008, when he posted "A note on DSR" on arxiv (0808.3505). And he never took part in the discussion of whether GLAST spacecraft (now called Fermi) might or might not observe that high-energy photons are delayed. It...

This may be a stupid question or have a pretty obvious answer, but I can't seem to find one so I'll just go ahead and post :) I was looking at some empirical data for relationships defining (abstracted) values for ionization and recomination coefficients in gases as a function of electric...

Is it just me or do other people think the atkins physical chemistry book is absolutely detrimental for undergraduates? Unless one is sound in their physics, chemistry, and math and the student is using the book as a means to find out other perspectives on chemistry issues, atkins is not...

Like university researchers measuring the force of Ricky Hattons punch with a special bag, or when programs talk about the force of crashes and ballistic impacts like shells and so on. But force is the mass x the acceleration. That indicates how strong something had to be to accelerate that...

http://arxiv.org/abs/0905.2292 A new physical principle: Information Causality Authors: M. Pawlowski, T. Paterek, D. Kaszlikowski, V. Scarani, A. Winter, M. Zukowski (Submitted on 14 May 2009) Abstract: Quantum physics exhibits many remarkable features. For example, it gives...

I understand that reflected waves on a transmission line are a result of the constraints of Ohm's Law and Kirchhoff's Law at the transition points. However, I'm having trouble visualizing the physical cause for this. What is actually causing the electrons to flow in the opposite direction...

Apparently extensive music theory of European, Hellenistic and ancient world is beyond my current depth. However, it seems reasonable to expect that western musical notes have a substantive physical basis in addition to relative consistency and obvious physical parameters. Obvious...

Can anybody give example of a physical phenomenon which can be stated into a polynomial equation (cubic, quintic or whatever) and which has complex number solutions and those complex numbers have some physical interpretation? The reason for asking such question tagged in physics is that i...

Hi, I am interested in taking a complex analysis course. How useful is it to the physical sciences?

Homework Statement Hi guys, I have 3 questions on physical optics, I really don't know where to start or what equations to use. Sorry for the horrible drawings by the way http://yfrog.com/0dfigure1p 1) Coherent monochromatic light of wavelength, lambda, in air is incident on two narrow slits...

Physical Chemistry Help! Homework Statement Hello TT forum. Finals are coming up!...and i am having a hard time solving these stoooooopid physical chemistry problems. ..any help would be GREAT appreciated! These are the 4 problems i am having a hard time with. I put ======= to separate each...

I've recently purchased a book on Quantum Physics, and I'm trying to get the basics down. At this point in time, I'm reading up on how Planck proposed that oscillators can only oscillate at discrete energies as opposed to on any amount of energy (on a theoretical continuous spectrum). This came...

Firstly let me waste a bit of your time by explaining I have not done much with maths or physics for ages! So please forgive my stupidity. My question: What kind of physical force does the Earth's magnetic field exert on any object on earth? My calculations (very probably deeply flawed)...

I have read about how space-time is shaped by gravity - fine. Is there an underlying assumption that 3D space exists in the first place? (because that's where we live). If I were to place a 3D sphere of radius 1 billion miles into nothingness - would it hold up? I mean there is nothing to...

Hey. I currently have a copy of atkins physical chemistry, although it is fairly old (4th edition). I found it for $20 at a second hand bookshop and it isn't in the best of conditions, but it has done the job so far! Anyway, what I am wondering is, are the later editions (8th i think?) much...

Can you give me links on forums, where I can correct grammar of the article by one to one sentence (i am not native speaker)? Maybe it is not necessary to find peoples with physical knowledge. Any other suggestions?

Hi, Can u point out physical interpretation of the complex permittivity? (ie. what can u expect from a material with \epsilon' = x and \epsilon'' = y ? what happens if y is very large etc. \epsilon = \epsilon' -j \epsilon'' thanks Krindik

Homework Statement You are given a meter stick and asked to drill a hole in it so that when pivoted about the hole the period of the pendulum will be a minimum. Where should you drill the hole Homework Equations T=2*pi*sqrt(I/mgd) The Attempt at a Solution So I use parallel...

The boiling points of three compounds are: CH3OH, 65C; CH3Cl, –24C; CH3Br, 4C Discuss the relative strengths of the intermolecular forces in liquid samples of these three compounds. what should I include in my discussion?

Homework Statement This isn't a homework problem, just something I've been trying to conceptualize for a while. Can anyone exemplify with a physical analog the concept of eigenstates? For example, I know that eigenvalues of variables with continuous spectra do not exist in the physical...

When we talk about the creation of the physical universe, does that include time and space? In other words were time and space themselves created along with the physical universe?

Hi. I am new to this forum and was wondering if anyone can answer my question. What caused the physical laws we have? Have these laws always been in existence? Is it true we may never know what the universe was lke before the BB? Can a theory such as the multi-universe theory be proven...

Homework Statement Indicate how entropy of the system changes for each of the physical processes shown below. Entropy increases, entropy decreases, entropy does not change. 1. Purification 2. Mixing 3. Freezing 4. Evaporation 5. Separation Homework Equations Entropy...

Hi, I'm trying to remind myself of exactly what, physically, is the difference between V and A couplings. Now, a vector coupling is of the form \bar{\psi}\gamma^\mu\psi, and axial coupling of the form \bar{\psi}\gamma^\mu\gamma^5\psi. Thinking in terms of a chiral fermion expanded as: f...

I am thinking about ways to model physical systems. An example of the type of problem I want to look at would be the response of sound waves to a series of resonators. Here is a java applet of a ripple tank, which is along the lines of what I am thinking of. http://www.falstad.com/ripple/...

What is the physical or statistical meaning of the following integral \int^{a}_{o} g(\vartheta) d(\vartheta) = \int^{\infty}_{a} g(\vartheta) d(\vartheta) where g(\vartheta) is a Gaussian in \vartheta describing the transition frequency fluctuation in a gaseous system (assume two-level and...

Hey, i am new to the forums and i have a question. I wouldn't consider this to be home work, because it is worth 10% of my first year score grade in physics. So it is a course work. I have to do a 10 min presentation on a material of my choice. I chose to do space shuttle tiles. So i was...

Homework Statement http://img5.imageshack.us/img5/348/snake.gif The figure above shows a piece of flexible wire lying on a frictionless table top. The wire can slide around and change its shape freely, but it cannot move perpendicular to the table. Part I If a current were to begin to...

Homework Statement In spherical polar coordinates, a vector F is given by F=(r*costheta*cosphi)rhat + (r*costheta*sinphi)thetahat + (r*sintheta*cosphi)phihat Check the validity of the divergence theorem for this vector and the volume that is one octant of a sphere radius b. Homework...

Hi, I think I can relate the mathematical operation (+) to a physical entity. Let's say we know for mass it makes sense to say (m1) + (m2) = (m1 + m2) and that has an physical meaning. But what is the physics behind multiplication (x)? Let's say we accept a/b as a x 1/b and let's say we...

Homework Statement How would you know wheather its a chemical change or physical change Homework Equations The Attempt at a Solution

In quantum mechanics, magnetic moment is equal to g factor times (gyromagnetic ratio x angular momentum). For orbital angular momentum, g=1, for electron spin angular momentum, g=2, for proton, it is 3.56. Is there any physical significance for this factor? why scientist introduce this factor...

Homework Statement a student carried out a photoelectric experiment by shining visible light on a clean piece of cesium metal. She determined the kinetic energy of ejected electrons by applying a retarding voltage such that the current due to the electrons read exactly 0. The condition was...

In another thread it was said: (my bold) In Rindler coordinates a "Rindler horizon" forms at a fixed distance below the Rindler observer (accelerating uniformly "vertically upwards" and Born-rigidly in flat spacetime, in the absence of gravity). This horizon has many of the properties of a...

Whats the physical reason for a diagonalized matrix with the eigenvalues of the system as the values? Reading from wiki, it seems that its something to do with the Schrodinger Eqn, but I don't follow that. If someone could explain the point of it to me in plain English (or as close as it...

Hello everybody! I've a question concerning the physical forces that would occur when a huge object (let's say a metal space ship) collides with an asteroid or a small moon (cold and without atmosphere). Is there any chance that the friction that would occur could melt the ship? Or would the...

The question (or puzzle) that I want to pose essentially belongs to classical (not quantum) physics. Nevertheless, there is a reason why I post it here on the forum for quantum physics, as I will explain at the end of this post. As a simple example, consider the following Hamiltonian...

Hey guyz... Im still kind of stuck on a couple of stuff...i still got a these movies left to PROVE! that it obeys the laws and fundamentals of physics... 1)Apollo 13 2)The terminator 3)October Sky 4)The Day after tommorw HELP!please this is an ISU..its worth 15% of my mark...i need it...

Can anyone explain the physical meaning of "spin" in QM? I'm a physics master student and I've completed several quantum mechanics (or related) courses and i have no problem working with Pauli spin matrices, angular momentum L, spin momentum S and total momentum J for nuclear or atomic...

If I failed this courses should I write a supplementary in about 10 days or should I retake it and put myself behind a full year of studies in my program?

What is the physical significance of the laplacian operator? The laplacian operator is the divergence of the gradient. I understand the intuitive meanings of both. The gradient when dotted against a unit vector gives the rate of change in that direction. The divergence is the flow in or out...

I have a rigid, massless strut of length 11m. A mass of 55kg is located on the free end, and another mass of 55kg is located at the midpoint. I'm having some trouble calculating the moment of inertia I for this physical pendulum. I = \int r^{2} dm (for continuous objects) I = \sum m D...

Homework Statement A physical pendulum is made of a cord of length S with no mass and a bar attached to the cord, of length L and mass m. We apart it from the vertical with an angle of \theta °. We then release it. 1)Find the center of mass' velocity of the pendulum when it reaches the...

I'm looking for a simple physical explanation of the lowest energy level in atoms, so I can provide a brief explanation to interested laypeople (not to mention just to help myself understand better). Does anybody want to take a crack at it? Or am I asking for the impossible? Since electron...

HI, I have my exam in 2 days and I am wayyyy behind this course I'm am only looking for a pass since I cannot get it down...I was just wondering if anyone had any advice on how to tackle it all? Should I do problems from every chapter and try and get through it? Or is there a better method you...

i would like to ask a que regarding physical optic,so let's nt beating abt the bush, QUE:A laser beam is incident on a 1.50 x 10^4 grove per inch diffraction grating.The wavelength of the light produced by the laser is 6.30nm and the interference pattern is observed on a screen 2.00m from the...

I had always thought of this as sort of a pseudo-problem. After all, I would think, why shouldn't the dynamical laws be symmetric wrt time-reversal. As John Baez stated in a review of H. D. Zeh's The Physical Basis of the Direction of Time (which I haven't read)...

I'm looking for a simple physical explanation of the discrete energy level in atoms, so I can provide a brief explanation to interested laypeople (not to mention just to help myself understand better). Does anybody want to take a crack at it? Or am I asking for the impossible?

Consider that high quality experiments furnish data that relate proper time intervals to coordinate time intervals for different values of the relative velocity (life time dilationf moving mesons). An inteligent computer program could find out the best function of the relative speed which...

I'm looking for a simple physical explanation of gravitational time dilation, so I can provide a brief explanation to interested laypeople (not to mention just to help myself understand better). Does anybody want to take a crack at it? Or am I asking for the impossible?