special relativity

It is easy to show that two inertial observers in relative motion do not agree on the conservation of linear momentum when they observe emission of one photon. The thought experiment: An LED flashlight in an intergalactic space emits one photon (wave packet) with the momentum P. The recoil...

The relativity of simultaneity is a consequence of Einstein's special theory of relativity. In the Newtonian conception of space and time, time is both absolute and independent of space. In Newtonian physics, for example, whether two events happen at the same time is an objective question...

In the classic Light Clock Thought Experiment the clock is shown standing perpendicular (at a right angle) to the plane of the clock’s travel. What however if the same clock was tilted forward at an angle (say 45 degrees) as shown in the image below? The light “blip” (red line) reflected from...

Okay, this is a simple question for anybody who knows the ins and outs of special relativity, but I'm finding different answers everywhere I look. Let's assume for the sake of argument that it's possible for a spaceship to travel at lightspeed (or as close to lightspeed as allows calculations...

Reciprocity of length contraction is a logical consequence of Special Relativity. The higher the speed and Lorentz factor, the easier to recognize the dubiousness of this SR prediction. Let us start with these premises: A distance of 100 light years, e.g. from our planetary system to a target...

--- An electron and a positron at rest can annihilate into two photons, each with a frequency corresponding to mass/energy of one electron (or positron). In order to refute SR, we simply ask what happens in this situation: Electron and positron annihilate while both moving at (relativistic)...

The relative motion of the observer and observed can alter the nature of the sound recorded where the observer is. At the extreme, is the sonic boom, If Doppler is a poor analogy, in what ways?

If a spaceship traveled at 1/10th the speed of light for 40 years, how much time would have passed on Earth during that same time? Thanks

Some very spiffy work out of the National Institute of Standards and Technology: Scientists there have measured the special relativistic time dilation of high precision optical clocks at the impressively slow speed of about 20 miles per hour. They have also used the same high precision clocks to...

Have the contributions of Poincare and Lorentz been slighted by historians of science and physics? I have read some material recently about the development of SR that have made me wonder about this. Any opinions?

When an observer moves, that observer's present is tilted with respect to another observer. In all normal situations the effect is negligible, and the observers will agree in which order things happen. The most obvious exception is when an observer is travelling close to the speed of light...

Some Hodge-Podge thought for your Comments. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX PRAGMATIC FAILURE OF...

What would it take to dethrone special relativity? To render it irrelevant to serious science, except for the historians? And, more interestingly, are there any ideas of what its replacement would look like? I know how I would answer, if someone asked me the same question, about Evolution by...

This thread has been created to allow the poster GMB to debate his claims with willing forum members, without disturbing other threads. The title has been taken straight from one of GMB's posts: I will not quote the messages that GMB posted prior to his suspension, but to get the discussion...

One of the key aspects of SRT appears to be the issue of relative time. yet no evidence that materially supports such a notion appears to exist. It is true we have time dilation [definitely]/length contraction [possibly] as this has been evidenced by experiments many times however evidence for...

HI guys, The question that I was pondering upon is: "If we have two or more observers [ RF's ] at relative v is t=0 for light events simultaneous for both [all] of them?" I was under the impression that t=0 is relative and not absolute, according to SRT but I have reason to believe I am...

For your perusal: General relativity applied to an expanding universe supports two obvious sorts of curvature horizon: cosmological horizons and gravitational horizons. It might be nice if we could topologically transform one into the other, and treat both according to the same basic...

Consider two identical rocket ships separated by a distance of 1 km. At t=0 the ships are at rest with respect to each other, and are pointed in opposite directions which are perpendicular to their displacement (so if one is at x=0 and the other at x=1, they are pointed in the y and -y...

(I can here the moans from around the world :-) It seems to me that Relativity is claiming that observing the reality of one rest frame, from the reality of another rest frame, creates a new and different reality of the observed reality. To explain what I mean I will use the light clock...

I recently read an article written by Steve Bryant "relativity challenge" and wondered what others thought of it...I noticed a lot of hostility towards it...even though, to me it made a lot of sense, by disproving a lot of the trash that SR and GR predicts. I have not included a link as:- I...

I am curious how fast the earth is moving, I am not asking about its rotation around the sun or the rotation on the earth's axis. I am curious if you were to observe the solar system in space at a single point and not affected by gravity or any force and you were to watch the solar system pass...

Hi, all--just a lurker here, but I've been looking for a place to ask a question that's been bugging me for a while, and given that there seem to be a number of physics experts here, it seemed to be an appropriate forum. On to the question, but first I want to mention that it's going to be a...

I don’t understand why, in some Relativity experiments, a clock slowing down is interpreted as being time per se slowing down (time dilation). We use clocks to measure time, but clocks aren’t time. What has a clock slowing down got to do with time slowing down? All clocks are mechanical and...

Several threads have shown a need for something like this. Introduction: The purpose here is to produce a simple introduction to special relativity in a way that can be understood, with some work, by folk who have only high-school maths and basic Newtonian physics. Given this, there will be...

I was going over Special Relativity in my head the other night, and just as it was starting to make sense to me, I came across a mental conundrum that has me stumped. I was thinking about the twins paradox, where one twin goes out into space, traveling at relativistic speeds for a while, then...

Okay, I'm trying to get to grips with relativity and I have just about come to terms with the twin paradox. This states that two twins could exist and one gets into a spaceship and fliues away from the earth then back again incredibly fast and as a result of relitivity the travelling twin would...

I thought today was an appropriate day to post this request, since this is the 100th anniversary of Einstein's paper "On the Electrodynamics of Moving Bodies" in which he introduces Special Relativity. (Wiki link) I've read various layman explanations of special and general relativity. I've...

Consider two concepts: "simultaneous", and "stationary". They mean the same thing, but with the roles of time and space swapped. "Simultaneous" means "same time, different places". "Stationary" means "Same place at different times". Ok. Let's say you and I are out in space, drifting past each...

hey, isn't the twin on the rocket getting older relative to his twin on Earth (since to the twin on the rocket the Earth looks like it's travelling close to the speed of light)? In this analogy it's always the twin on the rocket who stays the same age (or ages only slightly) and his earthly twin...

scenario Let's imagine a super-massive wheel as big as a galaxy (or even bigger if necessary), with fixed spokes/radials joining the circumference to the center. Now, let's consider 3 points within that wheel upon a single radial. One point on the circumference(z), one point at center(x), and...