The causality tag has no wiki summary.
18
votes
6answers
1k views
The speed of gravity?
Sorry for the layman question, but it's not my field.
Suppose this thought experiment is performed. Light takes 8 minutes to go from the surface of the Sun to Earth. Imagine the Sun is suddenly ...
23
votes
8answers
4k views
Why quantum entanglement is considered to be active link between particles?
From everything I've read about quantum mechanics and quantum entanglement phenomena it's unobvious for me, why quantum entanglement is considered to be active link. I.e. it's stated every time that ...
8
votes
4answers
678 views
In superluminal phase velocities, what is it that is traveling faster than light?
I understand that information cannot be transmitted at a velocity greater than speed of light. I think of this in terms of the radio broadcast: the station sends out carrier frequencies $\omega_c$ but ...
14
votes
2answers
660 views
Definitions: 'locality' vs 'causality'
I'm having trouble unambiguously interpreting many answers here due to the fact that the terms locality and causality are sometimes used interchangeably, while other times seem to mean very different ...
14
votes
5answers
1k views
The transactional interpretation of quantum mechanics
John Cramer’s transactional interpretation of quantum mechanics (TIQM) is billed as resolving the fuzzy agnosticism of the Copenhagen interpretation while avoiding the alleged ontological excesses of ...
7
votes
3answers
607 views
What are some scenarios where FTL information transfer would violate causality?
I've always heard people saying, "Faster than light information transfer can't happen because it would violate causality! Effects can precede their causes!"
However, I'm trying to think of a ...
9
votes
1answer
298 views
How is quantum mechanics compatible with the speed of light limit?
Consider a free electron in space. Let us suppose we measure its position to be at point A with a high degree of accuracy at time 0. If I recall my QM correctly, as time passes the wave function ...
4
votes
1answer
83 views
How soon that a force affect another object?
Imagine this scenario: I have 2 objects in vacuum without any force exerted upon them not even a possible gravitational force between them.
Now if one of them gets a gravitational or magnetic force, ...
11
votes
5answers
701 views
Is there such a thing as “Action at a distance”?
What ever happened to "action at a distance" in entangled quantum states, i.e. the Einstein-Rosen-Podolsky (EPR) paradox? I thought they argued that in principle one could communicate faster than ...
7
votes
9answers
824 views
Is causality a formalised concept in physics?
I have never seen a “causality operator” in physics. When people invoke the informal concept of causality aren’t they really talking about consistency (perhaps in a temporal context)?
For example, if ...
4
votes
2answers
337 views
the causality and the anti-particles
How can I quantitatively and qualitatively understand the fact that there is a relevence between the existence of anti-particles and the causality?
5
votes
1answer
176 views
Tachyonic antitelephone vs messaging through a wormhole
From the wikipedia article on tachyons:
Most physicists think that faster-than-light particles cannot exist because they are not consistent with the known laws of physics.[3][5] If such particles ...
0
votes
0answers
139 views
Hardy's Theorem
https://perimeterinstitute.ca/psi_portal/sites/perimeterinstitute.ca.psi_portal/files/hardyphysrevlett.68.2981.pdf
Some researchers in Bohmian Mechanics have hoped to make the theory Lorentz ...
4
votes
3answers
364 views
How does faster than light travel violate causality?
Let's say I have two planets that are one hundred thousand lightyears away from each other. I and my immortal friend on the other planet want to communicate, with a strong laser and a tachyon ...
3
votes
3answers
2k views
Example of space-like intervals in spacetime
From wikipedia:
When a space-like interval separates
two events, not enough time passes
between their occurrences for there to
exist a causal relationship crossing
the spatial distance ...
-1
votes
1answer
84 views
Grandfather Paradox [closed]
This question related to the Grandfather Paradox.
Assume that time travel to the past is a reality. What experiment/test could the time traveler perform in order to determine if he is in his own ...
