Relativity

Hello all, this is my first time here, and i want an explanation for why the following is not possible: Imagine an elastic sheet. Now imagine yourself pinching that elastic sheet and then continually moving the pinch in a clockwise motion around a central point (pinch A). Consider how the sheet would stretch. Now pinch the sheet elsewhere but do not move the pinch yourself (pinch B). Eventually both spots where you have pinched will meet up, but pinch B would follow the clockwise motion of pinch A. Now, is it so hard to imagine that space itself is pinched by the nuclear forces of atoms, and that orbiting electrons perform the action of pinch A? This wo…

I think it is more reasonable to think that all time is constant. As in moves at the same rate at all times, although when viewed from differnet refference frames it can appear slower or faster. So what if all time was passing at a constant rate, but appeared different to another observer (as in faster or slower).I think it is similar to if I ride a bike past someone they appear to be accelerating in the opposite direction of me, but when looked at through a different perspective it is quite obvious that I am the only one accelerating. Thoughts?

Was watching some astronomy program which was talking about red shift and it got me wondering how much red/blue shift is possible. Now I don't have the knowledge to do the calculations but according to wikipedia, in order to get a yellowish light to appear orange or green (a change in wavelength of 10nm or so), the light source would have to be travelling at about 5200 km/s away or towards you. So first question: 1. If we discounted the limit of the speed of light, theoretically radio waves broadcast by some object traveling at a gazillion miles an hour towards earth might start microwaving us and at yet faster speeds become visible? Second question has a …

I want to calculate the Ricci tensor for a 5-D metric. For example , the randall sundrum metric. ds^2=dw^2+exp(-2A(w))*(-dt^2+dx^2+dy^2+dz^2) there is any computer program to calculate ricci tensor in 5d spacetime? In 4d , using grtensor for the metric: ds^2=exp(-2A(w))*(-dt^2+dx^2+dy^2+dz^2) but, all component are zero (figure) any suggestions?

we measure time by the earth rotation around its axis and the sun but if it stand still for five minutes (i don't know how to word this properly) i have stopped but time its self keeps moving not time as in days hours and minutes but true time so in the five minutes that i count some form of time has passed that i can not go back to what is this and how dose it move is there a speed to it? hope that made scene

Hi, Three questions: 1. Can a person in a sound proof air tight room with no windows tell the difference between 1 gee produced because: a. the room is on Earth b. the room is under constant acceleration c. the room is being subjected to centrifugal force? 2. Aren't all three due to bending space/time? 3. Aren't gravitons involved in all of the above? From the armchair, Rusty

LIGO (Laser Interferometer Gravitational-Wave Observatory) has been built and works perfectly fine. But why hasn't it detected any gravity waves? Isnt PSR B1913+16 the binary system, indirect evidence that gravity waves exist? So why not point ligo in that direction?

Hi, Setting aside how it gets up to this speed, what other problems do we have? Rusty

It is said that a spaceman traveling at high velocity, when viewed from earth’s time frame, will age slower then his twin on earth. (The earth twin when viewed from the space twin’s time frame should age slower than the space twin). Assuming that when he ages to 50 in his time frame a blast takes the space twins hand off. Assuming again that when he returns to earth the space twin has only aged to 25. What has happened to his lost hand?

Simple relativity questions. 1. What does speedometer of ideal car measure? 2. Can it show, for example, 10c, where c=299792458m/s? 3. Is SR correct? My answers: 1. ... 2. Yes. 3. Yes.

From what I understand Electrons orbit a nucleus, and the only way to stop it is for it to be at absolute zero. So if the electron is in constant motion, and unable to be stopped, wouldnt it be possible to someday harness that motion of the electron, to create a perpetual motion machine? and unlimited energy? So - What's the current reason for the inability to invent something that can harness the motion of the electron? (not the charge of the electron, or magnetic field, or whatever) If an electrons motion can be stopped other than the atom being at absolute zero, how? Even though the motion is very small, with the quintillions of atoms in a grain of sand, yo…

Hello. I will do my thesis in " metric perturbation in the brane worlds and use of gauss bonnet term...I'm beginning to study the theory. What is the difference between metric perturbation in the brane world and cosmological perturbation of brane world? cosmological perturbations affect my thesis? I do not consider string theory in my dissertation Any suggestions for my work? I thank

This is more of a verifying question...Two photons are flying next to each other (same direction) at c...relative to Photon A, is Photon B's velocity c?

An electromagnetic field, as a plane wave, has a known space-time dependence: E = E_0⋅cos(ωt-kx). In a transparent medium it is the same except for involving the refraction indices n. Now, let us look at the field in a moving reference frame - that with v = c/n. What solution is for the wave in such a frame? Isn't it a E' = E'_0⋅cos(ω't') ? Merged post follows: Consecutive posts mergedI meant E' = E'_0⋅cos(k'x').

I am looking for exact specifications for tandem vandegraff accelerator. this would include measurements, materials, everything. I need this information to completely understand how they work, but I am unable to find it anywhere. a 3D model of it with noted materials and parts would be the best. anyone have anything like this?

The space twin would appear to carry an effect of time dilution when he returns to earth as it is said he would return younger than his earth twin. What happens to length contraction? I have not heard that he would return smaller.

I have this doubt. Let us assume an observer independently accelerating from 0 to the speed of light. If an other observer starts accelerating consequently, let us say after a particular time they reach the same speed, let us say 0.95C. Would they observe a time dilation with respect to each other? My idea is yes since with respect to a stationary observer they have a velocity v each. So they have a time dilation with respect to each other though the magnitude is the same. If a cup breaks in one of their frames, the other sees a time dilation. If cup breaks in the other frame, the other observer sees the time dilation. Another doubt. If we place a ruler of so…

Here is what I believe to be truth: 1)The Speed of light is constant in any reference frame 2)Nothing can go faster than the speed of light (Including light) Let us say that there is a space ship with a headlight which is flying away from the earth at light speed. It then turns on its headlights and the light goes zooming away from the space ship at.. once again.. lightspeed. In reference to the earth, wouldn't the light be moving away at twice the speed of light?

we can see only three mutually perpendicular st line in space at a pt. if time was another dimension either we have to imagine it only or we must shrink the angles. but what is the reason of shrinking the angle? infact what is the significance of another dimension? pls explain.

Can this transformation can be written as the composition of an homotethy with a pure shearing ? Merged post follows: Consecutive posts merged(i made a mistake with verbs in the last post). I had a 2nd question : if one computes the norm of the changed basis vectors it founds [math]\gamma\sqrt{1+\beta^2}[/math] ? Merged post follows: Consecutive posts mergedIm dumb... it was just the metric (or i coord) to get 1. Anyhow i couldnt find the definition of a shear matrix : can it be symmetric w/out 1s on the diagonal ?

I have another question about relativity combined with thermodynamics: Let assume that we have a Box of Volume Vo. Inside the box there is photons (photon gas). The gas has internal energy Eo, pressure Po and the box is accelerated to a velocity near to the speed of light. What will happen to the internal energy and the pressure of the gas?

If we consider 2 Lorentz transformation along x and y : Lx gammax -betax*gammax 0 -betax*gammax gammax 0 0 0 1 Ly gammay 0 -betay*gammay 0 1 0 -betay*gammay 0 gammay Why is L_x*L_y not equal to L_y*L_x ? --------------------- BTW is it to confond with Lorenz, with his Goose (?)

Hi Guys, Just wondering does anyone have a list of the major experiments that have been performed with regard to light speed and movement of sensors. How has light speed constancy been proven through experimentation in this regard. Has someone shone light pulses at a sensor moving forward and backwards towards the light and measured the length of the pulses? If anyone has a list of references it would be great.

Imagine an airplane that will start at point A and travel to point B and return to point A. Also that a wind is traveling in the direction of A to B. Say the plane travels 100mph the whole way, and the wind is traveling at 50mph. On the first segment of its trip it will travel at 150mph (wind speed added to initial velocity), and on the way back it will travel 50mph (wind speed subtracted from initial velocity). So the speed of the wind will be inconsequential because it's speed will be increased and decreased by the same speed of the wind. Therefore it does not matter if there is wind or not the plane will always return to it's starting point in the same amount of time. …

If a sphere was rotating about it’s axis at relativistic speeds what would happen from the perspective of an observer looking at the sphere with the axis of rotation parallel to them (directly up and down). What would happen from the prospective of an observer looking straight down on the sphere (such that the axis appeared to be a point)?