# Search results

• Users: Snip3r
• In Special and General Relativity
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1. ### Ray of light through an elevator

Yeah..I thought the light is flashed from the elevator itself. But thanks for clarifying
2. ### Ray of light through an elevator

No, the beam is not going to end up lower. If the elevator is moving at constant speed then it means it is at rest per se.
3. ### Why does light Ray bend in accelerating elevator but not...

Thank you all. I think I kinda get it now. Thanks again
4. ### Why does light Ray bend in accelerating elevator but not...

Yeah I believe this is the case. But not sure if it is as simple as this because a ball will have an upward velocity from the elevator which is not the same as in the case of a photon An inertial observer will not see any curvature. It will be a straight line for him. It is the non-inertial...
5. ### Why does light Ray bend in accelerating elevator but not...

Thank you. I now understand (logically) light emitted from an elevator hits wall at the same height in that elevator and not everyone in other elevators can expect it to hit their own walls at the same height from their floor. Otherwise there will be infinite reference frames where light strikes...
6. ### Why does light Ray bend in accelerating elevator but not...

This where I have trouble understanding why the guy in downward elevator can't expect the light to hit the wall at the same height from his floor. Because when the light was fired by the upward elevator, both were at same level and the photon just fired horizontally to both elevators at that...
7. ### Why does light Ray bend in accelerating elevator but not...

Sorry to start this again but Let's say another elevator/earth moving down at constant velocity and the moment light is flashed, all are side by side at the same level. Now the guy in the downward elevator will expect it to hit the wall at the same height from his floor as it was fired but it...
8. ### Why does light Ray bend in accelerating elevator but not...

Wow. That was clear as crystal. Thank you.
9. ### Why does light Ray bend in accelerating elevator but not...

I am not sure if I understand that. Let me clarify my assumptions. Let's say I am in an accelerating elevator (upwards) with a meter stick on two sides of them standing upright and i flash a light from the top of one to the other. I will observe the light to hit the other some where below the...
10. ### Why does light Ray bend in accelerating elevator but not...

Are you saying that the path of the accelerating elevator itself is bent from inertial standpoint?
11. ### Why does light Ray bend in accelerating elevator but not...

This may be a basic question but why does light ray bend in accelerating elevator but not in one with constant velocity. I know a frame of reference with constant velocity is indistinguishable from a stationary one from the inside but I feel like like somehow the light seems to know whether it's...
12. ### Are all events in eternal memory of spacetime?

consider A and B particles synchronizing clocks. Immediately after that B flies off at high velocity at the same time A flashes light perpendicular to B's motion. It hits some target c. Now in A's frame the event happened after t_{a}=perpendicular distance/c. But in B's frame it happened after...
13. ### Trip around universe

if i were to leave Earth travel in as straight a line as possible with constant velocity eventually i would return to earth. is mine a valid inertial frame?
14. ### A question on Special Relativity

thats a brilliant question (atleast for me) i had a similar doubt in this thread https://www.physicsforums.com/showthread.php?t=566430 however i dint understand ghwellsjr's sol given over there. bobc2's explanation looked ok
15. ### Block universe theory

bobc2, this is almost like what i asked for in my previous thread https://www.physicsforums.com/showthread.php?t=566430 but i have a doubt if there is only one time axis for all the observers they would age the same after separating and re-uniting isn't it?you can easily prove this by...
16. ### Interaction in 4-D spacetime

thats spooky!but on this i would say we can never ask the question "why" in this model because you will always answer "because that's the 4-d object in the path you just traversed" also does spacetime diagram really depict what's happening in the 4-d world. i mean if there is only one time...
17. ### Interaction in 4-D spacetime

As time is considered the 4th dimension can we say the 3-d world to be floating(advancing forward in time) in the 4D. If so is every inertial frame has is own velocity rate(moving in the time dimension) in the 4-D. When you have 3-D world if you want to bring 2 objects in contact you can bring...
18. ### Speed of light becomes Infinity and Zero

Δt' is NOT the time measured in S'. It is measured in S as the time taken between consecutive ticks for a clock placed in S'.
19. ### Speed of light becomes Infinity and Zero

ok let's restrict ourselves to frame S and don't jump to S' when we discuss.Let S(stationary) and S' (say velocity=0.8c) have identical light clocks and time between consecutive ticks is 1 second(meaning in any inertial frame, the frame ages by 1 second for each tick in a clock placed in that...
20. ### Speed of light becomes Infinity and Zero

an apparent misunderstanding between us. can you explain your stand?
21. ### Speed of light becomes Infinity and Zero

no you don't get me. Consider this a stationary observer S and a moving observer S' having identical light clocks. Now let S measure the time Δt between 2 consecutive ticks of the clock in S. Now how does he see the same clock to tick in S' (time difference between 2 ticks in S' as seen from...
22. ### Speed of light becomes Infinity and Zero

i never denied a person at rest ages slowly when seen by a person in motion. i just took one of the 2 cases. may be i should have mentioned Δt' is the time taken for the event in S' according to the S clock.
23. ### Speed of light becomes Infinity and Zero

yes... but i mentioned B is my FoR
24. ### Speed of light becomes Infinity and Zero

why not?what i meant is this (an example) consider A moving at 0.86c and B is stationary. Now B has to wait for 2 years in order to have A 1 year old but he himself ages 1 year in 1 year (of course B is FoR) sorry about that!dint know
25. ### Speed of light becomes Infinity and Zero

by convention Δt is the measure of change in time and t is of time at an instant. when a moving clock S' reads t' and stationary S reads t then t'=t\sqrt{1-V^{2}/C^{2}}(of course FoR is S) If an event takes Δt in S it would appear to take longer when happens in S'(seen from S) hence if Δt' is...
26. ### Age of Universe relative to what?

a quick question why can't 1-way speed of light be measured?
27. ### Speed of light becomes Infinity and Zero

how can time run slow and become infinity?time ceases at light speed. btw your equation is wrong https://www.physicsforums.com/showthread.php?t=511170
28. ### One clock on Earth, one on Mars

but even in my revised scenario if sun is taken as FoR Mars clock will start to tick faster than Earth's isn't it?
29. ### One clock on Earth, one on Mars

but as you said, if we take sun as the FoR the Mars clock will start to tick faster (than Earth clock) as soon as it reaches mars...isn't it? i am confused :confused:
30. ### One clock on Earth, one on Mars

are you accepting the Mars clock will continue to tick slow and never catches up with earth's?what's your stand?
31. ### One clock on Earth, one on Mars

yes you are correct the problem becomes trivial when sun is chosen as the frame yes! precisely... you got me! but what i also assumed is all these happen in a duration within which the path traced by the Earth is almost a straight line so no acceleration and qualifies as inertial frame so...
32. ### One clock on Earth, one on Mars

yes you are correct i forgot the elementary aspect GMm/r^{2}=mV^{2}/r velocity depends on r and m cancels out but imagine this what if Mars had some kind of propulsion mechanism which keeps it velocity below the velocity of earth?now what happens in Earth's FoR? and previous diagram holds
33. ### One clock on Earth, one on Mars

i had this in mind. as Mars revolves slowly in Earth FoR i considered clock B as coming back to earth.and what is the below comment i don't get how
34. ### One clock on Earth, one on Mars

no, the clock is not actually looked at. the time on a clock, given its velocity is calculated using equations.
35. ### One clock on Earth, one on Mars

but if my FoR is earth, does Mars clock continue to run slow? For a moment consider this assume Earth and Mars are in the same orbit (not concentric circles, just to avoid confusion and i think this has no effect)and Earth as FoR. Now when clock B is instantaneously transported to Mars it shows...
36. ### One clock on Earth, one on Mars

is this the time on Earth clock or Mars clock? If earth, the clock on Mars will show less than 1 second else Earth clock shows more than 1 second
37. ### Concept of time dilation

try this. get on to the top of a tall building and flash a light downwards. According to you the light ray must be deviated and should not hit the target (because Earth is moving around sun, 30 Km/s which is moving around the galaxy, 220 Km/s which is in turn moving at a very high speed from...
38. ### Concept of time dilation

i meant this. but i don't understand why do you think a laser won't work
39. ### Relative time

bobc2 thanks. i understood this from your STD if A' is an event in A, B' in B and A' is simultaneous with B' in A then it doesn't mean B' is simultaneous with A' in B. however i find it hard to visualize may be its because it is hard to imagine 4-D. is there a way by which you could draw an...
40. ### Concept of time dilation

beautiful :) this is misleading. no matter whatever the light source is, it will behave as if you are at rest when in constant velocity
41. ### Concept of time dilation

no it will hit the mirror. what you said was the idea behind MMX experiment however it failed
42. ### Relative time

why not local time?i m talking considering A as my frame and called its time local. Consider this 2 objects A and B meet at a point and synchronized to read 0. Now A and B continue to move as they did earlier(let relative velocity be 0.86c for convenience). Now if i am in A and 10 years passed...
43. ### Relative time

When 2 objects A,B are moving wrt to each other (lets say @0.86c)then from frame A if local time is 10 years then time at B is 5 years. What does this mean?is it any event happening now in A(10 years) is simultaneous with the events happened in B when its clock ticked 5 years?
44. ### A variation of Twin paradox

@ghwellsjr and DaleSpam thanks :)
45. ### A variation of Twin paradox

yes it was. But you said when something like that was done, rod will expand. I am now talking about that.
46. ### A variation of Twin paradox

if an electron shrinks when accelerated then is it not right to say even if simultaneous acceleration is applied to all particles of the rod, every subatomic particle shrinks resulting in the net reduction of rod's length?
47. ### A variation of Twin paradox

ok great. But you were explaining for a rod if instantaneous acceleration is applied to all the particles simultaneously it expands else shrinks(in rest frame)but when you consider something as electron the acceleration can only be instantaneous still it shrinks. how can this be explained?
48. ### A variation of Twin paradox

i am not sure but i think even a single elementary particle like electron shrinks as it moves. how can you explain that?or do you think this is getting too much and stepping into quantum mechanics?
49. ### Galileo's pendulum could show that time is relative

let me keep it simple. if you are stationary in outer space and there is no massive body around a pendulum won't swing what's your comment on that?time doesn't exist there? NO,as altitude increases time moves faster
50. ### Galileo's pendulum could show that time is relative

do you really think pendulum will swing in outer space?