Relativity Definition and 998 Threads

I love physics and do it as a hobby. I also like to use AI to help me make new and exciting discoveries. I look forward to getting feedback for some of the papers I wrote. All feedback is welcome. All I ask is to please be friendly. I am looking forward to having some exciting conversations.

Hi, I had an exam and I completely messed up a problem. Especially one part which was necessary for the rest of the problem. Basically, I have a wormhole metric: $$(ds)^2 = -(dt)^2 + (dr)^2 + (r^2 + b^2)( (d\theta)^2 + sin^2 \theta (d\phi)^2 )$$ Where ##b=1## with an orbit only in the...

As our space rock hurtles through the infinite void. Acting under the assumption that the fabric of spacetime is a 4 dimensional space if one were to travel to a point on that fabric for a value of time that our 3 dimensional planet has already been to given that we're traveling "through" time...

Hello everyone! I’m a student with a deep interest in physics, and recently I developed a conceptual hypothesis that I haven’t seen addressed directly in scientific literature. It's something that ive personally searched at a lot of places for many years. Reddit, Stackexchange, YT videos but...

Hello everyone, I’m delighted to join this community! My name is Shan Gao, and I’m a philosopher of physics with a deep interest in the foundations of quantum mechanics. I’m currently a professor at Shanxi University in China, where I work at the Research Center for Philosophy of Science and...

Although the speed of light is a 'cosmic speed limit', and is always constant, this seems to be a paradox. Firstly, the units we use to measure it relate to the Earth. How can we measure a metre or a second without the Earth as a reference point? And if we do, what meaning does this have for the...

import pygame # Initialize Pygame pygame.init() # Get the screen resolution info = pygame.display.Info() WIDTH, HEIGHT = info.current_w, info.current_h # Set to the current screen size # Constants WHITE = (255, 255, 255) LIGHT_COLOR = (255, 255, 100) OBJECT_COLOR = (100, 255, 100)...

While searching the internet for milestones in physics, mainly for those that led to the standard model, I came to ask myself why general relativity cannot be modeled by a gauge theory. Searching for "Relativitätstheorie als Eichtheorie" brought up a dissertation from 1990 titled: "Die...

Hello! I’m a philosopher getting into philosophy of science, and I’ve found many physicists claiming that “block universe” theory is a necessary interpretation from relativity. From what I’ve learned, I’ve found that, while relativity challenges traditional notions of “presentism” , it doesn’t...

$$T = m \hspace{0.03 cm}C^2 \left( \dfrac{1}{\sqrt{1-\dfrac{v^2}{C^2}}} -1 \right) $$ $$ T = \dfrac{m \ v^2}{ \left( 1+\sqrt{1-\dfrac{v^2}{C^2}} \right) \sqrt{1-\dfrac{v^2}{C^2}}} $$

If time dilates differently for two observers in relative motion, how is this possible when both observers can claim that it is the other's time that is passing more slowly? Doesn't this create a contradiction? And how does the famous twin paradox explain or complicate this issue?

Two relativistic spaceships, A & B, are launched simultaneously from Earth towards Kepler 22b, 640 LY away. Ship A is a lighter ship, has no life support as all it carries is some powered-down androids, and it can accelerate at a constant 3g. Ship B is a more massive ship, it carries human crew...

I was always big with watches, and I just have stumbled on a few that are masterpieces. Unfortunately they cost $500,000. What do you think?

If the laws of physics say that nothing can move faster than the speed of light, how can we square it in Einsteins equation? It dosent make synce to me. How does Einsteins equation work can someone break it down for me and explain it in layman’s terms please. How can we warp spacetime just by...

I really like physics especially relativity and classical physics like Newton's laws. I have joined this forum to discuss and learn more about relativity, classical physics and the weird QM

Hi All Would it be possible to introduce some exercises in general relativity at the high school level? Exercises that would at least help to raise students' awareness of the aspects that will be studied in greater depth at university or in post-doctorate studies? If so, what examples of...

https://www.amazon.com/General-Relativity-Robert-M-Wald/dp/0226870332?tag=pfamazon01-20

I have attached a copy of my work as a pdf file. Please excuse my non-rigorous usage of notation. Thank you so much!

In the. solution attached I'm not too sure why in frame K, we apply the doppler effect twice. Also, since the photon is moving away from the source, shouldn't the signs be switched? Thanks

Hello! I am a creator who loves the fascinating world of science. I enjoy exploring science from a unique angle, which often leads to new and creative ideas. While some of these ideas can be speculative and challenging to prove, I make sure they align with scientific principles and logical...

I am looking for instructions from you to find out a good university to enroll to a PhD program in Astrophysics and particle physics or a similar study. I have completed my 4 year BSc(Hons) Special in Theoretical Physics with a grade of second class upper division in Sri lanka. My specialized...

I can't figure out how to prove this using only those two identities? I mean in general, I could prove it easy when using relativistic equations, and showing that if ## v = c##, the denominator becomes 0, and if ## v>c##, the denominator becomes an imaginary number (a negative square root)...

Sagan describes this on page 207 of his book (1995 reprint hardback edition). In the context of the page he is discussing accelerating at 1g for half the journey and decelerating the other half for trips to Barnard's Star, the center of the Milky Way and the Andromeda galaxy. Then he talks about...

In relativity theory, it's a common habit to use a quadruplet x=(x_0, x_1, x_2, x_3) with x_0=ict (or with c=1, x_0=it ) instead of (t,x_1,x_2,x_3)\in \mathbb R^4, and to use the formal Euclidean metric \|x\|^2=\sum_{i=0}^3x_i^2 instead of the Minkowski pseudo-metric -t^2 + \sum_{i=1}^3x_i^2...

Relativity always talks in terms of observer but fail to explain common sense problems like this. The fact that no one can measure anything faster than light does not preclude to objects moving towards each other at a higher velocity than an external observer can measure. Move the observer to...

David J. Griffiths Introduction to Electrodynamics page 460: Lorentz force equation invariance leads to different Lorentz force values in different inertial frames. Is this a problem for conservation of momentum? More specifically conservation of angular momentum?

I’ve been self studying some of the concepts related to General Relativity, by trying to model Geodesics and calculate distances on curved surfaces. I found that I seem to understand some of the concepts related to the math, but not others as when I try to make some calculations I find that my...

Hello, I'm an old fart, that used to self study GR and tensor calculus. I have a BS ECE from UCD, and a MS EE from Stanford. I've since retired from my electrical engineering career which was mostly at the old HP's Stanford Park Division, and I find myself once again pondering these things. I...

I am trying to understand the solution to exercise 12.71 in the document linked below which accompanies Griffith's book on electrodynamics. The problem states that we are to use the Larmor formula and relativity to derive the Lienard formula. $$Larmor \ {} formula: P = \frac{\mu_0q^2a^2}{6\pi c}...

Relativistic motion and time dilation has been of interest to me for a long time, and whilst I am asking this for realism in writing a piece of fiction, I am curious as to how this interaction would work. Let's say there's a large dyson ring built around earth, which is spun up such that the...

Given a test charge moving along a current carrying wire, I'm familiar with the relativity explanation of the magnetic field at the rest frame of the wire and the electric field In the moving particle frame (where the wire is electrically charged). My question is how relativity kicks in in the...

For this problem, My solution to part (a) is ##u'_x = 0.3c##, however, I'm confused by (b) and (c). By definition in (b) and (c), the proper velocity of the proton is the speed of the proton in the proton-frame (frame where proton is at rest). So would the answer for (b) and (c) not both be...

I was surprised this morning when I got off on a tangent regarding the amount of energy available in the laboratory frame just at threshold. It reveals an interesting relativistic effect. Consider a reaction (I'm thinking in terms of nuclei and/or particles) ##1 + 2 \to 3 + 4 + \cdots## with...

For this problem, I don't understand what it means by the notation of a "stationary" observer. I thought there was no such thing as absolute rest. Does someone please know whether it means stationary with respect to the object? Thanks!

How did you find PF?: Google search I encountered a problem in the equations for Einstein's Special Theory of Relativity back when I was in high school in 1964. With the invention of the internet, I tried to discuss this with scientists in sci.physics.relativity, but most of the responses...

I used in another username to ask questions from this book, its second edition. I made a google search and didn't find any instructor's SM for the second edition, but it seems numerade website has complete solutions for questions from its first edition. Did he add more problems to the second...

Hi, I'm looking at this relativistic rocket equation on Wikipedia. Something doesn't make sense here, and I can't find a derivation for this equation in the linked source, so I'm trying to derive it myself with limited success...

Hello, I have been interested in physics and math since I was a student. Now I am just retired and have time to dedicate myself to deepening the study of these subjects. Above all, I would like to know better the theoretical foundations of quantum physics and relativity. I have been a teacher...

About the electromagnetic 4-vector ##A^\mu=(\Phi/c,\mathbf{A})##. If it is indeed a four-vector, then its squared length ##A_\mu A^\mu=\Phi^2/c^2-\mathbf{A}^2## should be a Lorentz invariant. What is the physical significance of ##\Phi^2/c^2-\mathbf{A}^2##? Thanks for any help.

Hi, I'm a new member, interested in physics and relativity and new ways to think about our world. Cheers Chris

A spaceship travels at the speed of light from the sun to the earth and back, infinite acceleration and deceleration. Sunlight takes about 8 minutes to reach earth. On the trip to earth, the sun seems to be frozen. On the trip back, sun activity appears to resume and is seen at 2x speed. The...

Ok for the interferometer let the arm lengths be ##L##, speed of light relative to the aether be ##c## and the speed of the setup relative to the aether be ##v##. By calculation you can show that the distance between the two 'heads' of the beams of light is ##\frac{v^2L}{c^2}##, and using the...

Other ways of wording this finding about the extended SC (Schwarzschild) spacetime: - in the local frame of a free faller, radial distance is given r coordinate difference - in either Fermi-normal coordinates, or Riemann-Normal coordinates built from a free faller at an event, coordinate...

Hello everyone, So I think maybe what confused me with the symmetry of time dilation was not understanding relativity of simultaneity. After looking into it if you have two clocks P and Q that synchronize when they meet and if ##\gamma## is 2 then from P's reference frame P equaling 10 and Q...

Reading Einstein Relativity. The trains experiences lightening strikes differently to the embankment. So the two events are experienced differently from the two reference points because they have different distances to the events. Light from the events taking different times to reach each...

Hello everyone, I've been thinking about 2nd postulate of relativity, it seems that and the Michaelson-Morley experiment seems to imply that there is no ether, but I was thinking about a special situation that doesn't seem to go against that postulate. I think my question is basic so hopefully...

I have seen many attempts to rationalise the 'Twins Paradox', but none of the seem satisfactory. They usually use acceleration or asymmetric differences in inertial frame, or other aspects of special relativity that tend to obfuscate the problem/explanation. So proposing an experiment that...

Consider a distant observer traveling at .867 c ( 𝛾=2 ) relative to the solar system along the line that is collinear with the sun's axis of rotation. As the clockwork solar system spins beneath him, the distant observer peers through his powerful telescope at Big Ben in London. After taking...

When reading about the one way speed of light, I think it's fair to say that most potential methods to obtain this fail because it is said to be impossible to have two non co-located clocks in synch. My question is really about terminology. Normally, two things can be said to be in synch if...

I'd like to perform an experiment that will build intuition for Special Relativity in the real world. While I do believe that it occurs in the real world, I'd like to be able to prove it for myself, and I feel that such an experiment would help others on this forum as well. Is there an...