How does QFT address the problem of Locality in Quantum Entanglement?

Soumya_M
Messages
23
Reaction score
0
Quantum Entanglement allows spatially separated entangled particles to have impact on each other instantly (overcoming the allowed speed-limit of causal influence which is 'c'). How does Quantum Field Theory address this problem (protecting causality and chronology)?
 
Physics news on Phys.org
No information can be transported at speeds greater than c using entanglement. This is stated clearly in nearly every authoritative treatment of the subject, yet we still get loads of people asking this same question.

There is no conflict with SR.
 
Mentz114 said:
No information can be transported at speeds greater than c using entanglement.

What you said about information transfer is allright. But what about the "causal influence". I mean, when one of the entangled particles is measured, it has an "effect" on the other particle (instantly). The measurement of the first particle, "causes" this impact. So the two events (1. measurement of the first particle and 2. impact on the second particle) can be said to be causaly related (event '1.' being the cause and event '2.' its effect). So although there is no instant transfer of information, the "causal influence" does seem overcome the speed limit of 'c'. This is what begs explanation.
 
Faster-than-light 'causal influence' is certainly one possible explanation for the correlations found in the Aspect and subsequent experiments.

I'm not qualified to say any more so I'll leave it there.
 
Soumya_M said:
What you said about information transfer is allright. But what about the "causal influence". I mean, when one of the entangled particles is measured, it has an "effect" on the other particle (instantly). The measurement of the first particle, "causes" this impact. So the two events (1. measurement of the first particle and 2. impact on the second particle) can be said to be causaly related (event '1.' being the cause and event '2.' its effect). So although there is no instant transfer of information, the "causal influence" does seem overcome the speed limit of 'c'. This is what begs explanation.

Two points:

1) If you call the measurements A and B, which occurred first is frame dependent.

2) I prefer to think that there is no causality involved at all. There is a feature of reality that two measurements will have a particular relationship with each other. Neither caused the other (you can't talk about which came first). As soon as you see one measurement you know about the result of the other, but there is no causal influence, just correlation built into a non-local quantum state.
 
PAllen said:
If you call the measurements A and B, which occurred first is frame dependent.
True.
Doing the Aspect experiment involves some very precise time measurement, in order to set up a frame in which simultaneity is well defined.

There seems no doubt that something strange is happening, but maybe it's not appropriate for this sub-forum.
 

Thread 'I don't see how a black hole's event horizon can be crossed'

OK, so this has bugged me for a while about the equivalence principle and the black hole information paradox. If black holes "evaporate" via Hawking radiation, then they cannot exist forever. So, from my external perspective, watching the person fall in, they slow down, freeze, and redshift to "nothing," but never cross the event horizon. Does the equivalence principle say my perspective is valid? If it does, is it possible that that person really never crossed the event horizon? The...
View full post »

Thread 'Synchronizing clocks in an inertial frame if light is anisotropic'

ASSUMPTIONS 1. Two identical clocks A and B in the same inertial frame are stationary relative to each other a fixed distance L apart. Time passes at the same rate for both. 2. Both clocks are able to send/receive light signals and to write/read the send/receive times into signals. 3. The speed of light is anisotropic. METHOD 1. At time t[A1] and time t[B1], clock A sends a light signal to clock B. The clock B time is unknown to A. 2. Clock B receives the signal from A at time t[B2] and...
View full post »

Thread 'Is the variation of the metric ##\delta g_{\mu\nu}## a tensor?'

From $$0 = \delta(g^{\alpha\mu}g_{\mu\nu}) = g^{\alpha\mu} \delta g_{\mu\nu} + g_{\mu\nu} \delta g^{\alpha\mu}$$ we have $$g^{\alpha\mu} \delta g_{\mu\nu} = -g_{\mu\nu} \delta g^{\alpha\mu} \,\, . $$ Multiply both sides by ##g_{\alpha\beta}## to get $$\delta g_{\beta\nu} = -g_{\alpha\beta} g_{\mu\nu} \delta g^{\alpha\mu} \qquad(*)$$ (This is Dirac's eq. (26.9) in "GTR".) On the other hand, the variation ##\delta g^{\alpha\mu} = \bar{g}^{\alpha\mu} - g^{\alpha\mu}## should be a tensor...
View full post »

Similar threads

I How can Bohmian mechanics explain entanglement?
2
Replies
57
Views
3K
A Do entanglement networks encode a unique, local historical record?
Replies
2
Views
2K
I Is there a bad intuition or bad explanation in quantum entanglement?
Replies
48
Views
745
I The notion of locality in (Quantum) Physics should be clearly defined
4
Replies
175
Views
11K
I Vacuum entanglement: between what and what, exactly?
Replies
5
Views
2K
I How Does Local Measurement Affect an Entangled System?
2
Replies
54
Views
5K
A Understanding Barandes' microscopic theory of causality
3
Replies
109
Views
5K
A Why is Quantum Field Theory Local?
4
Replies
182
Views
14K
I How Do You Break Quantum Entanglement Bonds?
Replies
7
Views
6K
I Can entanglement swapping be explained without nonlocal influences?
Replies
32
Views
482

Hot Threads

Recent Insights

Back
Top