The special theory of relativity describes the motion and dynamics of objects moving at significant fractions of the speed of light.

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Possible Answer To The Double-Slit Experiment [closed]

I think I might have figured the double-slit experiment out. I am not going to explain it here, Google it if you don't know it. If I am wrong please tell me why: Matter are relative to observers ...
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How does a frame of reference work in relativity? [duplicate]

I am struggling to understand what frame of reference means in relativity. Imagine the twin scenario. Twin A is at rest, while twin B travels somewhere and back at near the speed of light. If one ...
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Why does the speed of light totally prevent instantaneous information exchange?

Based on the classical light-cone approach it's easy to see you can't transmit information faster than $c$ but why does the speed of light (as far as I know) treat information transmission in this way ...
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Does coordinate time have physical meaning?

I have always been a little confused by the meaning of the "$t$" which appears in spacetime intervals or metrics in general relativity. I concluded that $t$ was just a mathematical thing which allow ...
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Michelson-Morley experiment revisited under the light of special relativity

Taking into account the composition of speeds in special relativity, lets suppose that a Michelson-Morley interferometer is moving at a speed of $\vec{v}$: the speed of Earth relative to the local ...
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Do charges attractions cause time dilation? [duplicate]

I was pondering whether charges will cause time dilatation? Let me explain more, well we know that gravity causes time-dilatation because of gravitational acceleration which is equal to: $$a = ...
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Time Dilation Back to Original Frame is Inconsistent?

I am watching someone jog at nearly the speed of light, and they snap their fingers. In my frame (A), it takes $\Delta t$ seconds. Using $\Delta \bar{t}=\frac{\Delta t}{\gamma}$ to bring you from ...
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What is the slowest possible speed?

According to special relativity, nothing can go faster than the speed of light, and nothing can be distinguished to be in a state of absolute rest. So it makes me wonder: is there a slowest ...
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28 views

What would an relativistically expanding sphere look like for an external observer?

Consider a reflecting sphere, whose radius is increasing at constant rate V close to light speed. What would the collision look like for a remote observer stationary relative to the centre of the ...
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173 views

Why is the speed of light in vacuum constant? [duplicate]

Are there any proof of the speed of light in vacuum being constant? All I hear is that light in vacuum travels at a constant speed because that's an observation and that it fits in a coherent theory ...
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Calculating time dilation for photon traveling towards a moving spaceship

Suppose a spaceship is moving away from the Earth at $0.5c$. When the spaceship is one light-year away from Earth, an observer on Earth sends a photon toward the spaceship. According to the observer ...
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Non-reciprocal time dilation

Is this report describing Absolute Lorentz Transformation legitimate or pseudoscience? The reporting sounds like the kinds of things I see in newbie's questions on the twin paradox, or crackpot ...
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What does the temperature of the early universe tell me?

I am re-reading Weinberg's book "The First Three Minutes". In the Introduction he makes this statement: "At about one-hundreth of a second, the earliest time about which we can speak with any ...
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Does the stationary object deform more than the moving one after a collision?

Given two identical clay disks on an air track, one is stationary and another is moving at "high" speed. After colliding, does the stationary disk deform more than the moving one? If it matters, the ...
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Why can you treat coordinates as vector in flat spacetime?

In a manifold there is a distinction between points and vectors, but in flat spacetime this seems to disappear. For example in Minkowski spacetime you can define a coordinate 4-vector ...
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Special Relativity - travelling close to light speed

When we say something travels close to the speed of light, what is its speed relative to? For example, we have 4 highly advanced spacecraft at rest beside each other, labelled A, B, C and D. We ...
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Is there an equivalent of Rindler coordinates for an object in centripetal motion?

Rindler coordinates are a parametrization of (a subset of) Minkowski space that are "natural" for an object experiencing constant acceleration - more specifically, an object experiencing constant ...
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Temporal properties of a photon

Naively, one can attempt to consider the (impossible) light-speed inertial frame. From there you arrive at nonsense conclusions like 'the universe is flattened in the direction of travel' which must ...
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77 views

Why is the relative velocity of B with respect to A negative of the relative velocity of A with respect to B?

I'm trying to figure out how to derive the transformation matrix for the Lorentz boost. Consider two inertial frames A and B, and let B move at a constant velocity V with respect to A. All the ...
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Is it possible extend Schrodinger theory in relativistic contexts with naive consideration?

Preamble Let's consider a generic sinusoidal wave $\Psi (\mathbf{r},t) = A e^{i(\mathbf{k} \cdot \mathbf{r} - \omega t + \phi)}$ and let's insert it into Schroedinger equation (please note that $ ...
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Is measurement of energy also relative? [duplicate]

From SR we know that the measurement of space and time are relative to the specific reference frame of the observer. What about measuring energy content? When an object is accelerated to a near ...
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77 views

Solving relative velocity without Lorentz transform [closed]

A train with proper length $L$ moves at speed $\frac{5c}{13}$ with respect to the ground. A ball is thrown from the back of the train to the front. The speed of the ball with respect to the ...
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Using the speed of light in a vacuum or in that medium

To clarify, is the speed limit of the universe the speed of light in a vacuum, or the speed of light in that particular medium, i.e. if the speed of light in a particular medium were only 17 m/s, ...
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Complex numbers in quantum mechanics and in special relativity

Is there a physical relation between the use of complex numbers for the wavefunction in (non-relativistic) quantum mechanics and in special relativity (as formulated in the setting of Minkowski ...
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Lorentz algebra and its generators

I'm reading Maggiore's book A Modern Introduction to Quantum Field Theory and I'm getting a bit confused when he writes about Lorentz algebra: $$K^i = J^{i0},$$ ...
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A question based on the paper 'ON THE ELECTRODYNAMICS OF MOVING BODIES' [duplicate]

Light is emitting from a source. Velocity of photon is always constant 'C' w.r.t stationary system. Say the source is moving at velocity 'V'. Then what is the velocity of photon at the instant of time ...
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The relativistic effects of angular velocity

Imagine I have a circular disk in a vacuum. I apply a constant force, so a constant torque on the disk. My first question is: does this disk have a angular velocity speed limit? I believe it does, ...
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Time-reversed twin paradox

This started with wondering about the nature of certain physical quantities under time-reversal - chiefly, that acceleration retains its magnitude and direction at a given time regardless of the ...
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Is this even possible to understand this proof? [closed]

Can someone explain what kind of sorcellery is this proof about Maxwell's equations: http://proofs.wiki/Maxwell%27s_equations_predict_that_the_speed_of_light_is_constant. Is this a joke?
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Time dilation simple derivation

In a special theory of relativity we have a phenomenon known as time dilation. There is a simple explanation of this, with a thought experiment with a train and a flash light: We flash a light in a ...
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Validity of Maxwell's equations with no aether or relativity?

In From Paradox to Reality: Our Basic Concepts of the Physical World by Fritz Rohrlich page 55 it states that [...] just doing away with the ether would not have resolved all problems. The ...
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Can I fix a point in Minkowski space to give it a vector space structure?

I looked up the term Minkowski space on Wikipedia. It said There is an alternative definition of Minkowski space as an affine space which views Minkowski space as a homogenous space of the ...
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60 views

Kleppner derivation of Lorentz transformation

I am reading Kleppner.(Lorentz transformations) He said,we take the most general transformation relating the coordinates of a given event in the two systems to be of the form $$x'=Ax +Bt, y'=y, z'=z, ...
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Can two distinct events occur at precisely the same moment in time?

I am writing a simulation and am having difficulty resolving the order in which two distinct forces occur. The simulation will give different results if the forces are applied to the state in ...
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Compatibility of twin paradox with the time-dependent Hubble constant

The universe is currently expanding with a speed of about 70 km/sec/Mpc which is today's Hubble constant. As this expression includes two length units, it is also possible to use the unit: $sec^{-1}$, ...
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60 views

Is the speed of photon always $c_0$? [duplicate]

The propagation of light in medium is sometimes interpreted as the photons moving with $c_0$ (the speed of light in vacuum), occasionally absorbed by particles and released again by transition, ...
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How do we know that time dilation applies to objects other than light?

Here is a traditional derivation of time dilation: There's a train with a lamp in the ceiling, moving at velocity v with respect to an observer. In the frame of the observer, the path taken by the ...
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How do you explain special relativity to a 3 year old child? [closed]

I've been on multiple threads that attempt to explain this celebrated theory, but I have come across some rather complex threads that is very good if you are a physicist, but no one even attempts to ...
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Is time depending on the observer in string theory?

I heard that in the theory of relativity the time of an action is depending on the observer. But in string theory, is the time also depending on the observer? Are strings acting according to the ...
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A sees B's clock running slow and B sees A's clock running slow? [duplicate]

This paradox is very common it seems, in which A sees B's clock running slow and B sees A's clock running slow. Here is the question a little more concretely. Let's say B flies by A's spaceship. If ...
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Subluminal speed when going in a circle around someone

Some time ago I thought about such situation: There are two people in the room. Both have synchronized watches on their wirsts. Then the person A starts running around person B with the speed of ...
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Is energy content of a system different dependending on the observer?

For the sake of simplicity, let's imagine that the entire Universe is empty except for a single lump of (classical) matter with mass $m$. In its center of momentum frame, it is clear that the total ...
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How do I transform onto a relativistic rotating frame of reference?

In classical mechanics, the usual formula to translate the evolution of a quantity as seen from an inertial frame of reference to a rotational frame is: $$\frac{d \textbf{A} }{dt} \vert_{Inertial} = ...
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What is “special” and what is “general” in Relativity?

Initially I thought in special relativity the velocity was constant, whereas general relativity allowed treatment of accelerated frames as well. But now I have heard that SR is only valid locally?
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Entanglement and simultaneity

According to the special theory of relativity, distant simultaneity depends on the observer's reference frame. And, according to the quantum theory, in the case of two entangled particles, a measure ...
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If I kept getting closer and closer to the speed of light, what would be the gravitational effects appearing like to an observer? [duplicate]

Now, with special relativity applied to the scenario of me getting closer and closer to light speed, my mass would increase with respect to the observer, and also my length would contract in the ...
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46 views

Mass of photon, is it possible? [duplicate]

$P=E/C$ In relativistic mechanics a Photon is defined as. $P=hf/C$ Replacing "P" $ mc=hf/C$ $M=h/CT$ What does it mean, did they have mass?
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Synchrotron radiation and special relativity

My questions below are for all those who assume the point-like electron of special relativity, that strange entity with no inner structure (!), but with intrinsic (?) rest energy, magnetic moment and ...
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Is imaginary time a fifth dimension? [duplicate]

I've read that by introducing the concept of imaginary time, the dimension of time can be treated like a spatial dimension mathematically. Assuming, without imaginary time, one considers the universe ...
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Turning off point for 1g acceleration

Let's say I am on a ship accelerating with 1g. I want to keep the engine running for half a year ( to an observer from my point of origin ) but due to time dilation it would have to be sooner than ...