Read about twin paradox | 34 Discussions | Page 1

  1. J

    I The Twin Paradox implies that the Universe as a whole is a special frame

    The Twin Paradox implies that the universe as a whole is a special frame of motion according to "Relativity Simply Explained" by Martin Gardner. I want to be sure than I haven't misunderstood something. I don't find the explanation completely clear. If the universe as a whole is a special and...
  2. George Plousos

    I A version of the twin paradox without accelerations

    Bob is standing on Earth and Alice is on a distant planet at a constant distance from Earth. Their watches are already synchronized in the following sense: Suppose Alice's planet is a light-year away from Earth. Bob emits a light signal to Alice at time t = 0 according to Bob's watch. When Alice...
  3. D

    B Why the stay-at-home twin is not considered to be accelerating?

    I am not a physicist. I need your kind help in removing my following doubt about twin paradox. What I have been able to understand about twin paradox is this- 1. Special relativity deals with non-accelerating (inertial) motion. 2. The travelling twin (A) moves at a high speed in relation to...
  4. J

    I Extended Twin Paradox (Triplet Paradox??)

    Suppose an observer (O) sees a traveler (T1) pass by at time t=0, moving a speed 3c/5. Five years later (according to O), T1 returns. If we assume that T1 traveled at 3c/5 for half the journey and instantaneously reversed direction, returning at the same speed, we can calculate that T1 aged only...
  5. W

    B Time dilation and Einstein's theorem

    Hello! Einstein's theorem is in the last sentence of the following quote (bold) [1]: "If at the points A and B of K there are stationary clocks which, viewed in the stationary system, are synchronous; and if the clock at A is moved with the velocity v along the line AB to B, then on its...
  6. m4r35n357

    I A twin "paradox" in General Relativity

    After making a couple of comments on this StackExchange question, and pointing yet again to this article, a thought occurred to me. I have been working on an Automatic Differentiation based ODE solver and equation analyzer, mentioned in this thread. Why not use it to solve equation (7) in the...
  7. B

    Twin Paradox from Moving Reference Frame- Return Journey

    Homework Statement a) Alice is observing a small ball of mass m in relativistic motion bouncing elastically back and forth between two parallel walls separated by a distance L with speed u. After each collision it reverses direction, thereby creating a clock. What does Alice observe as the...
  8. L

    I Twin paradox not including accelerations, it is wrong where?

    Hi people! (Sorry for my poor english). I found everywhere that twin paradox need aceleration to explain it. Let me change the twin paradox a little: Suppouse that in Earth and before the traveller twin start his trip, you take two photos with old Polaroid camera, one to each twin. As we...
  9. A

    B Special relativity and the flow of time?

    Pardon me if this has been asked before, but i'm confused with the implication that SR makes, that there is no objective moment of present. Do the science still believe that the time flows (i don't mean the arrow of time, but the phenomena of flowing/passing, eq. flowing of a river)? I mean, how...
  10. S

    I "Triplets" -- Twin Paradox

    Hello everyone, Reminder: The key of the explanation of the "twin paradox" resides in the acceleration. We know that the time runs slower for the twin in the spaceship (since it was accelerated)...
  11. R

    B Special relativity and expansion of the Universe, A paradox

    Consider two bodies A &B are moving apart with a velocity V due to the expansion of space. According to an observer in A the body B is moving away and an observer in B feels the body A is moving apart. Can some one answer in which body the time dilates and why?. ( I am specifying once again that...
  12. Andy_K

    I Twin Paradox - Observation at Turnaround Moment

    Dear All, I am doing the Special Relativity course at World Science U, and came across this question which I got wrong: When 100 nanoseconds have elapsed on traveling Gracie's watch, she immediately stops, turns around, and heads back toward George at the same speed of her outbound journey...
  13. Buckethead

    B Triplet paradox and a thought

    First off, let me just say I love this forum and all the people in it! The world is a better place because of all of you who take the time to post here and I thank you all! The most popular explanation to resolve the twin paradox seems to be the asymmetry that arises because the ship...
  14. m4r35n357

    B If anyone here doesn't yet get the twin "paradox" . . .

    Jim al Khalili did a (basic level) TV programme in the UK last night where he featured a smartphone app which works as a space-time "odometer". Now you can experiment on your own version of the legendary brain-teaser with your friends, no need to go to Alpha Centauri and back! Go for a walk...
  15. S

    I A _perfectly_ symmetric twin paradox cases

    Case 1) Two rockets (no Earth involved) have an exactly the same acceleration profile/flight-plan during round trip but they dispatched to opposite directions. At the start both rockets are docked to the same space station...both rockets have an identical engine operation plan during the round...
  16. Dimani4

    B Special Relativity: What Time is it?

    This question based on the site located here: http://galileo.phys.virginia.edu/classes/252/srelwhat.html The question is: If the object (spaceship) moving close to the velocity of light and I'm as a static object. The time goes slower in the object moving with constant velocity (inertial frame)...
  17. K

    I Twin paradox

    Definitions: Astronaut is A Person on Earth is B A travels to a star far away at near light speed, A would see B's time dilate. B would also see A's time dilate Twin paradox revived: What would happen if A returns to B at a very slow speed? Then both frames of reference would see each others'...
  18. robphy

    Insights Relativity on Rotated Graph Paper - Comments

    robphy submitted a new PF Insights post Relativity on Rotated Graph Paper Continue reading the Original PF Insights Post.
  19. P

    I Does the 1 Second after the Big Bang = 1 second now?

    When I read that conditions were such and such 1 to .05 seconds after the big bang, is that duration somehow longer than 1/2 second is now (maybe because of the difference in density or like the twin paradox?)?
  20. J

    B Twin Paradox visualized

    I decided to work a bit on my Java program created to visualize the Twin Paradox. It shows two diagrams. One from the perspective of the stay at home/earth twin on the left side and the travelling twin on the right side/diagram. The accelerations are considered to be near instantaneous, hence...
  21. F

    B Is special relativity incomplete?

    I feel a difficulty in understanding SP at fundamental level which is somewhat related with twin paradox. Let me take a thought scenario: in empty space or vacuum two boxes(A and B) with their own light sources attached are separated from each other at a far distance r initially. If they are...
  22. C

    I Twin Paradox Resolution -- Inertial frames

    Thinking and reading about the twin paradox recently, I encounter a lot of explanations and resolutions that don't make sense to me. At its most basic, the issue is- when two bodies are in different frames of reference, why shouldn't relativistic effects affect both equally, negating time...
  23. I

    I GR Twin Paradox

    Hi, I just saw a video about the twin paradox, explained by using GR. I was wondering whether I understood the video correctly. The video states that when the rocket twin is first accelerating away from earth, his clock and his earth twin's clock are different, but, roughly the same because of...
  24. E

    Signal time in Twin Paradox: Fast clocks? Redshift/blueshift

    NOTE: This is NOT a homework problem. I created this one myself based on some problems I have seen, with specific numbers used to make calculation clean and easy. Tl/dr version: in a round trip to a star, will the "moving clock" run slower on the way there but faster on the way back due to the...
  25. Y

    Question regarding a twin paradox related example

    Since I am new to the forum here, I apologize in advance that in case similar example has been explained in another thread. If so, please kindly refer me to the appropriate place to read further. In my example, there will be four reference objects, earth, E, distant star, S, spaceship A, and...
  26. N

    Question Regarding the Twin Paradox

    Homework Statement In the twin paradox suppose the twins are named Dick and Jane. And they both are 20 years old.Dick takes off on a voyage at a speed of 0.8c to a star 20 light years away.Lets say that both the twins send each other signals once a year while Dick is away.How many signals does...
  27. Stephanus

    Twin paradox and asymmetry

    Dear PF Forum, Can someone make it clear for me? Perhaps I should ask a very simple question. Concerning just one direction. The distance between earth and Star T is 100 lys. The clock is synchronized for A and B And as PeterDonis pointed out at my previous thread. Which I believe 87% is an...
  28. Stephanus

    Twin Paradox and symmetry

    Dear PF Forum, Sorry if I ask (again) about twin paradox, after so many question about this topic here. Supposed T is a star 100 ly from earth. If B travels to T from earth A. Is the symmetry broken? B. If B watches A's clock at Earth and A watches B's clock at T, do they see the other clock...
  29. C

    Twin Paradox - Question on Space Time Diagram Analysis Resolution

    I started a thread previously (https://www.physicsforums.com/threads/time-dilation-happens-on-moving-frame-but-which-one.814622/) around this concept but it got closed by one of the staff after helpfully pointing me to...
  30. blue_leaf77

    Twin Paradox (again(again(again )))

    When you see the title of this thread, I'm sure you will either be bored or excited because this is one of those famous 'paradoxes' in SR. So I read the book by Schutz on the part of explanation behind the twin paradox. There he gave an example of two sisters Diana and Artemis involved in the...
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