Sr Definition and 477 Threads

Is there anyone here who could help me understand the state of physicists understanding just prior to 1905 and Einstein's SR paper? I keep running into length contraction, considerations of simultaneity and its non-universal nature, Lorentz transformations, time dilation and other concepts that...

In his 1905 paper introducing special relativity, Einstein calls attention to the asymmetry in the classical treatment of the relative motion of a magnet and a conductor: In a previous post, it was explained to me that, when the conductor is moving, the electromotive force has "in itself ...

Does putting the concept of acceleration in SR make it equivalent to GR? I see a lot of sources (including many posts in this forum) which seem to say that SR can handle acceleration fine, but not gravity. However, an acceleration IS gravity by the equivalence principle, so what's the...

1. http://forum.allaboutcircuits.com/image_cache/httpwww.cs.nyu.educoursesfall00V22.0436001lecturesfigssrlatch.png Using this image, how would you get the second input if the second input has to come from the output of the nor gates?

Can the metric of special relativity be derived from requiring the infinitesimal line segment, dτ, to be invariant in space and time? If we parameterize a line segment by the variable τ marked off along the line (that exists in space and time dimensions) is the length in τ of that line segment...

Recently learned about Special Relativity, so my brain is running perpetual circles around itself asking questions. So, I figured I would come here and ask where could I find out more information about the Lorentz Factor being undefined at a luminal velocity? Or more basically, where do I...

Hi, Are there any free online reliable resources to learn SR and GR? Thanks.

I am trying to understand if SR can explain a real, measurable velocity time dilation as seen in experiments/observations like GPS satellite or Bailey et. al. Let us say we have twins sitting in their identical, individual spaceships in space, close to each other, and far away from any large...

As I understand it from what I have read the gravitational time dilation concept was arrived at through the equivalence principle. That the differential dilation at different locations in an accelerating system were derived from SR and included in GR by EP. But I have never encountered the...

This is the frirst SR problem in his book. I think the question is flawed. The solution assumes a speed of 3.00 E8 m/s to calculate Δt=333us since it traveled 100km. Next, 333us and 2.2us is used to solve for velocity using the time dilation formula. Velocity is reported to be .999978c.This...

If both the inputs in SR latch are zero and there was no previous output then what would be the output? If both the NOR gates are different then depending which one is faster the output will be accordingly, but what if both are identical?

Hi, I have a question that's been bugging me. For simplicity, assume everything is inertial. Let's say I take off in a spaceship from Earth towards a distant galaxy at .99999999C - so basically, the trip will be very fast, and let's say in one week time in my reference frame, it will appear...

I'm wondering if causality is enough to derive the Minkowski metric and the Lorentz transformations. It seems to me that in order to ensure that some set of events maintain a causal relationship to each other under a transformation to a moving frame of reference, that there must be some...

Einstein's "Zur Elektrodynamik bewegter Körper" ("On the Electrodynamics of Moving Bodies") was published September 26. It reconciles Maxwell's equations for electricity and magnetism with the laws of mechanics by introducing major changes to mechanics close to the speed of light. This later...

I would be thrilled reading your points of view on following: Special Relativity. (With that I mean: SR, not kind of an ether or LET interpretaion): In a frame two events are observed simultaneous because they are simultaneous in that frame, even if not observed. And those two events are...

This post is a continuation of my post https://www.physicsforums.com/showpost.php?p=4041285&postcount=10 and https://www.physicsforums.com/showthread.php?t=629655&page=2 PeterDonis and Harrylin are correct I better start a new thread for this. I repeat my post here. [/B] Thanks for...

I often hear from laymen who study some SR that if sth reaches the speed of light,it completely turns into energy! Where did this crazy idea came from? Any way,mass increase in SR seems really mysterious to me E.g. when mass tends to infinity as velocity tends to c Can someone clarify...

Hi, I'm reading the section about "How the fields transform" in Griffiths' Intro to Electrodynamics book, but I'm a little confused and want to understand this fully. He starts off with the example of a parallel plate capacitor where each plate has charge density \sigma _0. So in the rest...

I'm currently completing a special relativity assignment, and whenever coordinates are referred to they're represented as (x1, ct1) = (25m, 25m) or (6m, 2m). There are no units given (other than the 'm', and I highly doubt they're using minutes for ct). If someone could clear this up for me I'd...

I know that lorentz transformations are the same in matter and vacuum My question is,when light is propagating in matter,it certainly has a speed smaller than c Does this mean that we should treat it differently from light in vacuum? I mean in a vacuum,we say that time doesn't pass for light...

It was about 20 years ago but since I've started studying physics independently I keep reminiscing about what my high school physics teacher taught me even though it doesn't have any utility. One thing he said was that Einstein showed his theory of SR to a physicist and the latter responded...

Superluminal Neutrino Breaks SR and GR...? I have reading a lot of articles and editorials about apparent neutrinos that went faster than the speed of light by 60 nanoseconds, I read some that say yes and no, so I'm a bit confused. So is it true?? Are there neutrinos that went faster than the...

Hello. I am independently studying modern physics. I have a basic special relativity question. Consider a completely inelastic collision Of course, objects are moving at a constant velocity before and after the collision with respect to a stationary observer. Let's call him Rick. Suppose that...

I read basic stuff about relativity (time dilitation etc.) in a HS textbook. I want to do some relativistic dynamics and go up to Einsteins field equations (GR). For GR I will definitely need tensor analysis. However, what is the math involved in the SR that I need to get to classic...

Consider the following "classical" example: ^{}_{} A system Σ' moves away from a system Σ with relative velocity v in the direction of z'z axis (their origins concur at time t=t'=0). A charge q is located in the origin of Σ' and moves along with it, while an observer sits at (0,yo,0) in Σ. The...

I struggled in adv alg 2 with trig my jr year. Some of it may have been me not applyling myslef this year. I passed with a C- (77%). How bad is that? And for my senior year I am going to take adv precalculus. People say its a review of alg 2. Is that true? I think the thing i struggle with most...

suppose we have a moving frame and a rest frame..we know time dilution and length contraction had occurred in moving frame wrt rest frame,this is to make sure that speed of light is same in any frame..but this is not the case..consider measurement of speed of light in moving frame wrt rest frame...

I recently studied the data which claims to be evidence of the need for an infinite amount of energy to accelerate a body to the speed of light. This consisted of accelerating particles at different energy levels and then graphing the resultant speeds attained by the accelerated particles. The...

So from my understanding SR loosely tells us that time is not constant and that depending on our motion relative to another observer will dictate our differences in rate of time. I was wondering what SR tells us about the expanding universe. In cosmology we're taught that the universe is...

Picture yourself accelerating to 3/4 the speed of light, taking your girlfriend with you, and leaving your best mate behind, back on Earth (with no speed!). At this speed you stop accelerating and continue to travel through space at 0.75c. From this position, you see light traveling at the...

I was having this debate with a friend, and I wanted to know if I was correct. My friend was saying that SR is an approximation for GR (albeit a very good one) with the specific conditions of only inertial reference frames, and I was saying that SR is exactly accurate with GR, and so is directly...

Does SR actually imply that FTL travel would allow for violations of causality? Here is some reasoning to suggest that it does not: (I would be surprised if there were no holes in the reasoning. My desire to find these holes is what motivated me to post this here.) Consider the following...

Assume a spherically symmetric transparent objects relative to the observer high-speed motion, what the observer will see? 1, a discus (one dimension of contraction) 2, a olive football (two- dimensional of contraction ) 3, a narrowing of the sphere (three-dimensional at the same time...

I'm having a hard time wrapping my head around some of the basic concepts. Imagine a spaceship moving at a certain velocity relative to you. To you, his time is slower than yours. He guy in the spaceship doesn't know his time is slowed down. If his time is slower than yours, it means that he...

Standard treatments (e.g., Rindler) of the foundations of Special Relativity invoke use of a "rigid rod" or "rigid scale" by an observer to construct his inertial frame -- by (somewhat fictionally) transporting the rod (and also cloning copies of a standard clock at every point in the frame)...

I'm not sure if this is the correct place for this as it is not about relativity as a topic in physics but the history of Einstien's theories. Both SR and GR were verified (or, more properly, not falsified) by experiment relatively (pun intended, I guess) soon after the theories were...

I have just a very general question regarding the idea of vacuum energy. It seems that it exists it would have to occur such that it would be the same in every reference frame to satisfy the principle of relativity, yes? Would that suggest it would be part of a stress-energy tensor which is...

Hello all, Special relativity tells that space and time should be seen as a single four dimensional space time. Even the metric for SR has four components, x1, x2, x3, and x4 = ict. The Lorentz transform tells us how to convert these coordinates from this to another providing that we are...

What happens if two objects travel at speed 1/2c in opposite directions? Like suppose two ships left the ISS in opposite directions, each going speed 1/2c. Wouldn't either of the ships determine that the other is moving away at the speed of light? Could they see each other? What if...

What is the difference between both theories? From what I've heard, GR replaces SR as the more correct theory, but if that is so, then why do we still refer to SR and GR separately, rather than just refer to GR? (Don't have much of the physics background, so I would appreciate it if people...

I posted this thought experiment in a previous thread before 4 months or so, but I would like to reiterate it now: A frame of reference (FOR) has double slits moves relative to a ground FOR. Let`s make an arrangement so that when the 2 ends of FORs coincide, 2 small slits of moving FOR are...

I'm a beginner at electronics, so please bear with me... I have a 3V signal that is triggered under a certain condition and stays on for less than a second (I have no control over this). This is connected to a DAQ that can only sample at very slow rates (Also, no control over this). I'm...

I like to try and derive little things by myself if I think it is manageable. One such thing is the addition of velocities. I gave it a stab, got an answer, and it turned out to be wrong. So tell me where my logic messes up. There's a spaceship moving at velocity u1. A man in the spaceship...

I wanted to understand something about Inertial frames especially as they are talked about in SR. It appears that the laws of physics should hold the same in them. Now I understand that inertial frames only involve things moving relative to each other and moving in constant speed so you can...

In SR. Anything FTL or superluminal can affect causality because there would be some frame where things move backward in time. Since SR is equivalent to Lorentz Ether Theory. And LET is about additional dynamics that occurs in the backdrop of Newtonian absolute space and time. Then how can you...

Two cars are stationary and next to each other and not moving relative to each other. According to SR their clocks should be synchronized. Am I correct in saying that? Also by saying this am I correct in saying that they agree on the time of events? Now what would happen if one car starts...

For instance you have time dilation in special relativity which is said to be due to something moving faster than something else relative to it. You also have the time dilation in GR where time speeds up the further away you go from a body such as the Sun, Earth, etc. Now could it really...

I am new to understanding the concepts in SR and GR, and one of the main concepts i am having difficulty with is the speed limit. I don't understand why things can't already be moving at the speed of light in certain frames of reference. For instance, from the Earth's frame of reference, isn't...

If you are traveling very very fast in a space ship, are there any visual effects produced by general relativity that you wouldn't see from just special relativity? Assuming we don't get close to large gravity wells like black holes. Does the acceleration of the ship produce any visual...

Suppose I have a disk that is 100,000 km in diameter. I attempt to rotate it at 1 revolution per second. Am I unsuccessful because the material on the outside edge would have to travel faster then light or am I successful because length contraction at the outside edge reduces the...