Sr Definition and 480 Threads

Hi, I found this 'paradox' which supposedly says that SR is incorrect, I have a hunch why it may be a flawed argument, but can't personally get the numbers right. Perhaps it's a fun exercise for some of you to destroy the argument. Here it is: So my hunch why this is incorrect:

My 10th grader is looking for a relativity book that is bit more advanced than the ones he has been reading, which are An Illustrated Guide to Relativity by Takeuichi, and General Relativity A to B by Gerach. He has completed AP Calculus BC, so he has a good handle on single variable calculus...

Hi. What is the total energy of a particle in a potential? Is it $$E=\gamma m_0 c^2+E_pot$$ or is it still $$E=\gamma m_0 c^2$$ where ##m_0## is a bigger mass than the particle would have in absence of the potential?

Howdy, Was wondering if you guys would mind critiquing, correcting, or adding any good insights to the following which was posted elsewhere by me, thanks! ________________ ... remember a ways back there was a finding that went viral about the speed of light not being constant? I forget the...

This question is a new (to me) wrinkle on the old Special Relativity spaceship pseudo-paradox gedankens. Suppose you observe two spaceships motionless relative to you, side-by-side a mile apart. First, a rifle is fired from one at a target on the other, the bullet hits the target. Now they...

Imagine there are two space ships, Ship A and Ship B. Ship A sees Ship B traveling at 0.865c towards him. (And of course vice versa) From Ship A's FOR there is a marker 9,000,000 km away which is at rest wrt Ship A. The marker, Ship A and the path of Ship B therefore form a straight line. When...

Homework Statement Two rockets A and B are moving away from the Earth in opposite directions at 0.85c and -0.75c respectively. How fast does A measure B to be travelling? Now I have worked out v = -0.85-0.75/(1- -0.85*-0.75) = -0.997. This is correct. Now I would like to work it out backwards...

Hi, When I started learning about GR I wondered if it emerged from SR (which the name suggests) or if the connection between the two is mere technical. GR describes the behaviour of the metric of space-time, which is locally Minkowskian and therefore SR applies. But is a curvature-based theory...

The second postulate of SR is telling us that light always travels at C in a vacuum(absent of gravity) measured by any observer independent of the source or inertial frame the observer is measuring the light from. However, light is made up of photons which do not travel like ping pong balls in...

Hello all, I'm just doing some practice for an upcoming exam and came upon this question in my notes: One experimental way to generate very high energy photons is to ”collide” a laser beam against an electron beam, the photons that recoil in the direction parallel to the electron beam will have...

The problem is a simple n-body problem: there is n charged particles - electrons, protons, or other particles; we have the initial parameters: a mass, charge, position, velocity, at a time t = 0. In a standard (classical) numerical computation of the n-body problem I can use any numerical...

The function ei(p.r – Et) is the central player in non-relativistic QM. Yet the expression (p.r – Et) is the Minkowski inner product of the space-time four-vector, (t,r), and the four-momentum (E,p) and as such is Lorentz invariant. According to Feynman, De Broglie realized the relativistic...

Has there ever been an experiment to support the principle assumption of relativity? For example an experiment where an atomic clock is sent on a probe to , let's say, Pluto. We on Earth get transmissions of the time on that ship and, after taking account of the light travel time delay, we...

The mass of a particle will increase as its velocity increases according to special relativity. This has been confirmed in countless experiments in which particle accelerators accelerate charged particles. What type of experiments have confirmed this for uncharged particles? Thanks in advance.

I think I have never seen a force equation for massless particles, I wonder if such thing exist or if not why not?

This is maybe more a maths question. In part 3 of his 1905 SR paper, how does Einstein solves the following PDE : to get : ?

No matter how much I shed light on it, there's always some dark corners of relativity into which I have trouble seeing. In a recent book I read, a starship with continuous acceleration approaches c to within many decimal places, creating a collosal time dilation - enough for the universe to age...

We now know two things distort space time: relative speed [we call it time dilation and length contraction] and gravity. Gravity IS the 'curvature' of space and time. "Mass tells spacetime how to curve; spacetime tells mass how to move." [John Wheeler, I think.]

I would like to show you how to use Schwarz inequality to prove some important general theorems and solve problems about vectors in Minkowski spacetime. Okay, Schwarz inequality states that \left| U^{k}V^{k}\right| \leq \sqrt{(U^{i})^{2}(V^{j})^{2}}. \ \ i,j,k =1,2,3 \ \ \ (1) And, the...

This is just a random thought, may be totally wrong. Euclidean geometry was originally described as a constructive theory in which the axioms state the existence (and implied uniqueness) of certain geometrical figures. These constructions are the ones that can be done with two concrete tools: a...

Does SR enable the passage of time. Rietdjik(1967)-Putnam(1968)-Penrose-Maxwell and others, claim that SR proves Eternalism. That is; the world is an eternal (a-temporal) 4-dimensional spacetime manifold in which all events exist and the notion of a moving Now (a global hyper-surface of...

Muons time dilation from the Earth's frame (and length contraction of Earth's atmosphere from muon's frame) is the usual explanation of the fact that muons reach the Earth when they shouldn't just by their rest half-life. My question is if the explanation based on differential aging(different...

Hi. In GR , covariant differentiation is used because the basis vectors are not constant. But , what about in SR ? If the basis vectors are not Cartesian then they are not constant. Does covariant differentiation exist in SR ? And are for example spherical polar basis vectors which are not...

Homework Statement The question is what's the relationship between SR and EWR and if the column will fail by buckling or crushing. I know my last statement in the link below is miles out. https://www.physicsforums.com/threads/column-buckling-answer-confirmation.564927/page-3#post-5244310...

I recently quizzed physicists in my workplace with the following question: The speed c in the second postulate refers to: a) the one-way speed of light b) the round-trip speed of light c) Both d) Neither I was surprised at the variety of answers. What do you say?

Homework Statement Suppose a frame S' is related to S by a boost in the y direction by v. Imagine a wall is at rest in the S' frame along the line y'=-x'. Consider a particle moving in the x'y' plane that strikes the surface and is reflected by the usual law of reflection θ'i=θ'r. Find the...

Dear PF Forum, Before I go further, I'm stuck and need clarification. Two postulates of SR 2. the velocity of light is the same for all inertial observers. Okay..., this one I can understand, at least can grasp. 1. the laws of physics are the same in all inertial frames of reference; What laws...

In the context of a photon entaglement experiment, let the observer be in the frame of reference of photon "a". Photon "a" starts its travel to Alice with a relative speed to her = C. If SR holds, photon "b" cannot be moved at all in the opposite direction, when "a" arrives at Alice. And vice...

People jog, thereby expending energy, and lose weight because of it. As modern people who understand mass energy equivalence, we know (or can presume) that during the process of running, the body derives its kinetic energy by breaking down ATP in the cells. When this breakdown occurs, the total...

As I understand it, the formula ##E=\gamma m_0 c^2## gives the total energy of a body in any inertial frame. However, the formula ##E=\sqrt{ (m_0 c^2)^2 + (pc)^2}##, which is also supposed to give the total energy of a body (in any inertial frame), does not equal to the first formula. Why is...

Hi all,I have been struggling mightily through Purcell's book on Electricity and Magnetism, but chapter 5, which deals with the SR explanation of magnetism has me somewhat confused. Suppose we take the following scenario: In the Lab frame, F, electron 2 (e2) is moving towards the right...

I saw a thread that asked the same basic question as I'm asking, but the explanation was beyond my current knowledge. Please consider answering my question as if you were being interviewed for a Discovery Channel special and had to make it comprehensible for a general audience. Thanks! For me...

I seem to be missing something fundamental about length contraction in SR. I would be grateful if someone can point out the error in the following logic. Suppose I have a method to measure lengths of objects in the following manner: I place a mirror at the right end of the object, send a light...

Hi, is there any general formula to find out the final velocity w, happened by a boost in x direction forst and then to y direction? I could find the boost matrices for both and I know it's not purely another boost, rather a boost and a rotation, but I am really confused which formula to use...

Alright I'm a noob to all this but I have been reading a really good book that talks about special relativity and had a question. Considering that light does not pass through time, it travels between any two points in zero time, correct? Does that mean that from the perspective of the light...

Is it possible to read and understand General and Special relativity on your own (by studying from the right textbooks),without a degree in physics? I know the basic stuff in calculus ,algebra ,geometry and Newtonian physics etc ...how will i know whether i am upto it?

In SR, we may choose any inertial observer and his reference frame at which he is at rest, and other observers are movin wrt to him. All the moving observers 'slice' spacetime in a different way than the observer at rest, at different angles relative to his simultaneity surfaces. This is all...

The seems to be a link between SR and a magnetic field Feynman mentions it in his "Lectures in Physics". The problem is the explanation is not finished. Feynman's assumes electrons travel at relativistic speeds while they are known to travel at very slow speeds. It seems to me we...

In QM, the energy operator is proportional to the time derivative E ~ d/dt So higher energy particles have higher frequencies, i.e. their wave functions change more often per time than when at rest But in SR, higher energy particles seem to exist in slow motion, appearing to age little How...

I made this pic to illustrate my problem. A spaceship (labeled B) departs from a space station (labeled A) at 80% the speed of light (0.8c). A applies the time dilation principle and calculates that B's clocks are running slower than his. Some time later a smaller craft (labeled C) detaches...

Here's my problem. We know the magnetic force is just F=q(v x B). If we have a stationary charged particle in a magnetic field, it will not feel a force. If we change to a moving frame, the particle now has a velocity, but the idea that it feels a force by changing frames is ridiculous so...

So I'm taking AP-C: E&M for my last high school semester and wanted to take some time to read up with a rigorous special relativity book. I've already taken the equivalent of Calculus 1-3 at a university level and I've read Kleppner and Kolenkow's Mechanics book up to the chapters on Special...

"I've looked this up and came up to similar questions but haven't seen it been explained very clear yet. Excuse me if such questions were already posted here. There are two different kinds of simultaneity it seems to me:Let's take the event of two lightning bolts striking earth. Observer A is...

Just wondering if you are observing someone from a far out distance and they are in a gravitational field going at a high speed would the time dilation from their speed add on to the gravitational time dilation?

So I have seen time dilation written as all three of the following: t=τγ, Δt=Δτγ, dt=dτγ. I'm assuming this not to be the case, but just wanted to clarify that the third (differential) notation does not imply that t=∫τγ? That really wouldn't make sense (to me at least), so I'm assuming that...

This is something I've wondered for a long time. In discussing time dilation in SR, you often hear something along the lines of, "If you looked into a spaceship traveling near the speed of light, you'd see the astronaut inside moving in slow motion, the hands on their watch ticking slowly..."...

I am trying to reconcile the definition of contravariant and covariant components of a vector between Special Relativity and General Relativity. In GR I understand the difference is defined by the way that the vector components transform under a change in coordinate systems. In SR it seems...

The Lorentz's transform: ##x' = k(x - vt), t' = k(t - vx)\ k = \gamma,\ and\ c = 1## I. The speed composition derivation: ##w' = dx'/dt' = \frac{dx - vdt}{dt - vdx}## and we divide everything by dt, and: ##w' = \frac{dx/dt - v}{1 - vdx/dt}## now we assume the dx/dt is some speed u, and the...

Thought experiment: Alice, Bob, and the planet Zolan. Alice is floating in space 10 light seconds from the planet Zolan (Z) with a radio emitter and detector. She and planet Z are in the same rest frame. Bob has the same devices as Alice but is on planet Z. Bob then accelerates from...

Hello, i am new here. I have been studying SR en GR for a while on a hobby level, and i keep pondering on the following : Consider the following situation : A train with a person on it leaves the station. SR says that while moving with constant velocity, the trainguy cannot tell...