Light Speed Separation: How Long?

joruz1
Messages
3
Reaction score
0
If two objects move away from each other in opposite colinear directions at the speed of light. How long will it take for the light from one of the objects to reach the other?

I think the answer is never, but not sure.
 
Physics news on Phys.org
If you mean that each object is moving at exactly the speed of light, then your question starts out with a impossible situation, because nothing can travel at the speed of light (except light itself, of course). There is no way to answer this question in its literal form.

If each object is moving very slightly slower than the speed of light, then an answer is possible in principle, but you don't provide enough information to calculate it. The time it takes for light to travel from one object to the other depends on the speeds of both objects, and on how far apart they are when the first object emits the light.
 
Thread 'Can this experiment break Lorentz symmetry?'

Thread 'Can this experiment break Lorentz symmetry?'

1. The Big Idea: According to Einstein’s relativity, all motion is relative. You can’t tell if you’re moving at a constant velocity without looking outside. But what if there is a universal “rest frame” (like the old idea of the “ether”)? This experiment tries to find out by looking for tiny, directional differences in how objects move inside a sealed box. 2. How It Works: The Two-Stage Process Imagine a perfectly isolated spacecraft (our lab) moving through space at some unknown speed V...
View full post »

Thread 'Relativator (Circular Slide-Rule): Simulated with Desmos - Insight'

Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. The Relativator was sold by (as printed) Atomic Laboratories, Inc. 3086 Claremont Ave, Berkeley 5, California , which seems to be a division of Cenco Instruments (Central Scientific Company)... Source: https://www.physicsforums.com/insights/relativator-circular-slide-rule-simulated-with-desmos/ by @robphy
View full post »

Thread '1-Way Speed of Light'

Does the speed of light change in a gravitational field depending on whether the direction of travel is parallel to the field, or perpendicular to the field? And is it the same in both directions at each orientation? This question could be answered experimentally to some degree of accuracy. Experiment design: Place two identical clocks A and B on the circumference of a wheel at opposite ends of the diameter of length L. The wheel is positioned upright, i.e., perpendicular to the ground...
View full post »

Similar threads

B One-Way Speed of Light
2
Replies
93
Views
5K
I A question about the speed of light and electromagnetism
2
Replies
51
Views
4K
B Speed of separation of two masses
Replies
16
Views
2K
B Prove the velocity of a moving object is absolute in one IRF?
Replies
22
Views
1K
I Conventionality of the One-Way Speed of Light
Replies
5
Views
317
I One-Way Speed of Light: Is it Possible?
2
Replies
53
Views
6K
B Problem about postulate of the invariance of the speed of light
Replies
33
Views
3K
I Can the intersection point of two light beams exceed the speed of light?
Replies
9
Views
1K
B Measuring the speed of light on moving systems
Replies
13
Views
2K
I Why is Rømer's light speed measurement not one-way?
Replies
42
Views
3K

Hot Threads

Recent Insights

Back
Top