Curved spacetime and measurement direction

  • I
  • Thread starter Hill
  • Start date
  • #1
Hill
708
564
TL;DR Summary
How are parallel directions for measurements of entangled particles defined in locations which are far from each other?
To be specific, let's say that two photons in EPR entangled state were sent to Alice and Bob separated by billions of light years. We know that if they measure their photon polarizations in the same direction, they certainly get the same result. My question is, what is the same direction in their case?
I assume that this is determined by the parallel transport in curved spacetime and depends on trajectories of the photons between their origin and Alice and Bob respectively. Is this assumption correct?
 
Physics news on Phys.org

FAQ: Curved spacetime and measurement direction

What is curved spacetime?

Curved spacetime is a concept from Einstein's General Theory of Relativity, which describes how mass and energy influence the geometry of space and time. Instead of being a flat, unchanging backdrop, spacetime can be curved by the presence of mass and energy, affecting the motion of objects and the flow of time.

How does curved spacetime affect measurements?

Curved spacetime affects measurements by altering distances and the passage of time. For example, the presence of a massive object like a planet or star can warp spacetime, causing nearby objects to move along curved paths. This curvature also affects the measurement of time, leading to phenomena such as time dilation where time passes differently depending on the gravitational field's strength.

What is the significance of measurement direction in curved spacetime?

Measurement direction in curved spacetime is significant because the curvature can cause different measurements depending on the path taken. For instance, the distance measured between two points can vary if you take different routes through a curved spacetime. This is due to the non-Euclidean geometry where straight lines (geodesics) are curved by the presence of mass and energy.

How do we measure distances and angles in curved spacetime?

In curved spacetime, distances and angles are measured using the metric tensor, which encodes information about the curvature. The metric tensor allows us to calculate the proper distance and proper time between events, taking into account the curvature of spacetime. This involves integrating along the path taken through spacetime, using the metric to account for the curvature.

Can curved spacetime be directly observed?

Curved spacetime itself cannot be directly observed, but its effects can be. For example, the bending of light around massive objects (gravitational lensing) and the precise orbits of planets are both consequences of curved spacetime. Additionally, experiments such as the observation of gravitational waves provide indirect evidence of spacetime curvature.

Similar threads

B A well defined thought experiment
2
Replies
55
Views
2K
I Uncover Traps in Spacetime Diagrams: Bob & Alice's Cases
Replies
33
Views
2K
I Request for Input: 2D Minkowski Spacetime Diagram Generator
Replies
6
Views
2K
I Parallel transport and entanglement
Replies
5
Views
1K
I Struggling with a special relativity "paradox"
2
Replies
47
Views
3K
A Entangled particles in curved spacetime
Replies
4
Views
1K
I Is the moment of the measurement well defined?
Replies
12
Views
1K
B Metric Line Element Use: Do's & Don'ts for Accelerated Dummies?
Replies
29
Views
2K
I Null Spacetime Intervals and Quantum Superposition
Replies
16
Views
2K
Speed of light measured in/by a parallel frame moving at c
Replies
2
Views
2K

Hot Threads

Recent Insights

Back
Top