Special relativity Definition and 1000 Threads

I recently trying to learn General Relativity by first scraping the surface on ScienceClic's general relativity playlist, and then I stumbled upon a video where it said that we actually move through spacetime on a constant speed of c, and then I remember about time dilation because how speed on...

Hi, I´m trying to solve a special relativity problem, and I think I need some help. There are two inertial frames of reference, ##O## and ##O'##, the last one moving with relative velocity ##v## in the ##x## direction. There's a rod with length ##L'## fixed to frame ##O'##, such that front end...

I'm a female neurobiologist in my 60s with a lifelong passion for physics (but my math was not strong enough). I have a special interest in special relativity and a decent grasp of the basics. I can solve Lorenz calculations 'til the cows come home'. I don't need help with homework of any type...

> A particle of mass M at rest decays into two particles of masses m1 and m2 traveling in opposite directions at velocity v1 and v2 respectively. Express v2 in terms of v1, m1, m2, and M. Since both objects are from a single object that's why I took relativistic mass of both objects are same. I...

Summary:: Special relativity and Lorentz Transformations - I got this problem from a first-semester course at university. I have been struggling for a few days and decided to get some help. A rocket sets out from x = x' = 0 at t = t' = 0 and moves with speed u in the negative x'-direction, as...

I am reading pretty much everywhere that LET (Lorentz Ether Theory, or call it Neo-Lorentzian Relativity, or whatever theory that involves a preferred undetectable frame with some yet unknown properties that make all the moving objects with respect to this frame length contact and time dilate)...

I am new here, so pardon my ignorance. First of all, I am aware of the impossibility to distinguish experimentally between SR (Special Relativity) and LET (Lorentz Ether Theory). I know there is a PF policy article on LET and the Block Universe. I must admit though that LET is more appealing...

If a person was rotating on a verticle axis from head to toe like the Earth or quasar. If nothing can go faster than light, from the person's perspective looking at the stars traveling across the night sky, if you increase the rotation of the earth, stars further than a certain critical distance...

How to Judge original time and original length of special relativity

I am confused by the concept of space-time in special relativity, I have 3 spatial dimensions and 1 time dimensions. In Newtonian physics don't I also have 3 spatial dimensions and 1 time dimension? Then why call it space time in special relativity and not in Newtonian physics?

The way I was doing is that I list events 1. lightning hits x=0 this is (x_1=0,t_1) 2. lightning hits x=12 (x_2=12,t_2) 3. left lightning reaches "me" (x_3=9,t_3) 4. right lightning reaches "me" (x_4=9,t_4=t_3) t_4=t_3 since "I" see the lightning at the same time Then the...

Hello everyone, I have a hard time to conceptualize the case of a moving black hole. We know from SR that time slows down for moving objects; but time dilation at the event horizon is already equal (tends) to zero. It seems that it can create some sort of conflict for the black hole movement...

I saw a book that uses special relativity to solve the twin paradox, the inference process is roughly as follows. Suppose a spacecraft sets off from the Earth to travel to a distance black hole and then return to the earth. We divide this process into three stages, that is, the process of...

I believe this does not belong to the homework category. I hope I won't be mistaken. I am reading a book to self-study special relativity, the following is an example mentioned in the book. When clock C' and clock C1 meet at times t'=t1=0, both clocks read zero. The Observer in reference frame...

Hello everyone. I have just complete an experiment calculating the speed of a muon. I got it to 2.6E8 m/s, however I know that they are created at close to speed of light to be able to get down to Earth's surface in their short lifespan. This speed could not have been its initial speed, as it...

Dear readers, Maybe someone can enlighten me on the understanding of the proof given by the Michelson–Morley experiment on the special relativity. Just as introduction to detail the setting: There are 2 coordinate systems A and B. A stands still and B moves with the velocity v along one of...

Does time dilation in Special Relativity relate to the Doppler effect? If you move near the speed of light you experience time differently and the sound is stretched. Are these similar phenomenon?

Some introduction books on Lagrangian and Hamiltonian mechanics use classical mechanics as the theoretical framework, and when it come to special relativity it goes back to the basics and force language again. I would like to ask for some recommendations on good books that introduces Lagrangian...

I'd like to get some help on checking my understanding of special relativity, specifically I'm trying to clarify the idea of coordinates. Any comment is really appreciated! The spacetime is an affine space ##M^4##, which is associated with a 4 dimensional real vector space ##\mathbb{R}^4##...

Why is time = ct and not t in special relativity? I just started reading the book I was recommended. Maybe I missed it but as stated in the title why is time = ct and not t in special relativity? I understand they want distance/space = time. Just how do they go about doing that mathematically...

Hello everyone, I am preparing to write an exam project in college about special relativity, however i am missing the critical experiment to prove that it is true. I thought about using the life time of muons, but i don't have a scintillator to detect them, so unless a standard geiger counter...

I made an exercise whose question is like that: A spacecraft moves with speed v at the axis x. There are two target at the axis x, in which the distance between them is L at the ground frame. Suppose that the spacecraft shoot the target simultaneously when it passes by the target. A|so...

I recently had a discussion with my brother, about what it means to "move through time". His opinion is, that physicists cannot take this literally. His opinion is, that time is just an expression for change that takes place at different rates for different observers depending on their speed...

I drew the Minkowski diagram, but I'm not sure if this is correct. From what I drew the angle between x and ct ##\approx 0## then the event is "inside" the light ray and will eventually reach A.

I am an amateur in physics and I have a question. How does speed of an object affect time?

I want to learn special relativity.I have read a tiny bit of 2nd edition of Spacetime Physics: Introduction to Special Relativity and am liking it. Is it a good book? I also want problems to solve. I tried Special Relativity: For the Enthusiastic Beginner but found it to difficult. Does anyone...

i am having some hard time thinking about this problem: It is basically this: Imagine a bulb and a receptor distant L from each other (at the same axis x) inside a room, the roof of the room is at a height d from the bulb and receptor. Now you are at a train moving horizontally, parallel to...

I builded the translated lorentz transform, at t=0 t'=-22.5 and x'(x=0)=67.5 after that I just didn't the question

While learning about Special Relativity I learned that we use the Transformation matrix to alter the space .This matrix differs for Contravariant and Covariant vectors.Why does it happen?,Why one kind of matrix (Jacobian) for basis vectors and other kind(Inverse Jacobian) for gradient...

Assume that space is a three-dimensional torus ( a 3D donut) . If there is a clock traveling at a CONSTANT speed in a direction parallel to the torus (inside out of the hole) and one clock that is still. Which clock ticks faster and why? I know that the clock rotating will tick slower, but I...

I have seen the "Hafele-Keating with the plane as reference frame?" thread (https://www.physicsforums.com/threads/hafele-keating-with-the-plane-as-reference-frame.767913/ ), but the replies do not seem to explain (to me anyway) what when taking a plane as a reference frame, balances the slowing...

A particle is moving along the x-axis. It is uniformly accelerated in the sense that the acceleration measured in its instantaneous rest frame is always g, a constant. Find x and t as functions of the proper time τ assuming the particle passes through x0 at time t = 0 with zero velocity.I n...

I'm reading a book called "Reality is not what it seems: the journey to quantum gravity" by Carlo Rovelli and I'm struggling to understand this diagram that is part of the chapter about special relativity. https://i.stack.imgur.com/JgBDJ.jpg Before this image Rovelli writes: "It's not...

While I am working through proving the homework statement, I encountered a problem. The problem is as follows: From the energy equation above, one can see that the minimum value of ##p## is ##m_T##. However, how does one explain why when ##p=m_T##, ##\sqrt{m^2_B+m^2_T}>m_A##?

According to this link here https://en.wikipedia.org/wiki/Relativistic_mechanics#Force , we can inverse the relation of force in terms of velocity and acceleration: $$ \mathbf{F} = \frac{m\gamma^3}{c^2}(\mathbf{v} \cdot \mathbf{a})\mathbf{v} + m\gamma\mathbf{a} $$ to get: $$ \mathbf{a} =...

If there is a spaceship traveling at 0.999c, the time to reach a star 100 lyr away would be approx 100 yr (assuming no accel and decel). But on the spaceship, It would be 100 yr * sqrt(1-0.999^2) = 4.5yr. Why do we take 100 yr as the time seen on Earth and not the time on the spaceship?

Summary:: Require confirmation regarding answers to a question posed by the book "Basic Relativity" by Richard A. Mould. Here is a problem which I encountered while going through Basic Relativity by Richard A. Mould- I'd like to receive a confirmation regarding the answers I've come up with to...

From the michelson-morley experiment, if a clock were to measure the time period of light hitting the mirror and returning back, it would be 2L/c, where L is the distance between the laser nd the mirror. For a moving observer, the time period would have a factor of *gamma*, the boost factor...

I came across an interesting question in the Hartle's textbook, "An Introduction to Eisntein's General Relativity". The question is as follows: Explain why a photograph of an object moving uniformly with a speed approaching the speed of light, parallel to the plane of the film appears not...

For a observer on Earth, a rocket takes Mike from Earth to Pluto with a speed of 0.82 c for 33.72 yr. Find the space-time interval for the two events such as Mike leaving the Earth and reaching Pluto considering Pluto is at rest relative to Earth for the observer on Earth. I confess that i am...

Is mass relative? does the faster you go change your mass? Because according to the Energy calculations E = ymc^2 at speed and mc^2 and since the speed of light is constant, does that mean that mass changes? [Thread edited by a Mentor to remove personal speculation]

Hi All, I've been doing some reading on the above but having some problems understanding certain parts of it (maybe it's wrong from Wikipedia!) To simplify it for me I will first pose a simple scenario where we are not factoring in speed yet, then go from there. Say we have two planets A and B...

[Moderator's note: Spin-off posts from previous thread have been included in this new thread. Also, the OP's re-post of the scenario for discussion has been moved to this top post for clarity.] Yes. Physically, scales measure a force (and indirectly the energy) in their frame. Consider the...

Hi, I've a doubt about the application of the principle of relativity as follows. Assume as principle of relativity the following statement: It is impossible by any experiment performed inside a "closed" laboratory to say whether we are moving at constant velocity or staying at rest. Consider...

What are the best books for a second exposure to Special Relativity? I can find plenty of threads on introductory books …

Time when the left beam hits the left wall in the ground frame ##vt_1-x = c t_1## ##t_1 = \frac{x}{c+v}## Time when the right beam hits the right wall in the ground frame ##ct_2 = vt_2 + y## ##t_2 = \frac{y}{c-v}##Setting the times equal to each other with the constraint x+y=L to find x and...

Velocity is a 4-vector which has 3 space dimensions and 1 time dimension. It's space parts will be directed at the 3 space directions and time parts will be directed at the time dimension (But it is inverse. So, will it point at the inverse direction?). How can someone Visualize it? How they...

Why momenergy has magnitude equal to the mass? > The mom-energy of a particle is a 4-vector: Its magnitude is proportional to its mass, it points in the direction of the particle's spacetime displacement, and it is reckoned using the proper time for that displacement. How are these properties...

Hey dear physics community :) I ask myself what exactly happens to forces between materia when the materia hits near lightspeed. I know, that for an objective bystander watching let's say elon in his rocket with 99,99999% the speed of light, that the time goes slower, the mass of the rocket...

Assumptions 1. General Relativity is the modern and most complete widely accepted theory of gravitation, formulated in a background independent, geometric way. 2. General Relativity is formulated in a manner consistent with Special Relativity and I could imagine that it might be possible to...