Is this a good definition of entanglement

  • Context: Graduate 
  • Thread starter Thread starter g.lemaitre
  • Start date Start date
  • Tags Tags
    Definition Entanglement
Click For Summary

Discussion Overview

The discussion centers on the definition of quantum entanglement, exploring various interpretations and nuances of the concept. Participants critique existing definitions, particularly from Wikipedia, and propose their own formulations while addressing the implications of those definitions.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant expresses dissatisfaction with the Wikipedia definition of entanglement and proposes their own, stating that objects are entangled if changing the property of one instantaneously changes the property of another, regardless of spatial separation.
  • Another participant adds that observing an object leads to entanglement with it, suggesting a relationship between measurement and entanglement.
  • A critique is raised regarding the phrase "changing the property of an object," which implies a pre-existing value that can be altered, potentially leading to misunderstandings about causality in entanglement.
  • A revised definition is suggested, stating that two objects are entangled if their quantum states cannot be described separately, though this is acknowledged as potentially misleading because it implies a separateness that may not exist in quantum mechanics.
  • Another participant proposes a definition specific to electrons, stating that two electrons are entangled if setting the properties of one sets the properties of the other, while also questioning the accuracy of the claim that everything in the universe is entangled, linking it to the influence of temperature and kinetic energy.

Areas of Agreement / Disagreement

Participants express differing views on the definitions of entanglement, with no consensus reached on a single definition. There is acknowledgment of the complexities and potential pitfalls in phrasing definitions, indicating ongoing debate and exploration of the concept.

Contextual Notes

Participants highlight limitations in existing definitions and the challenges of conveying the nature of entanglement without implying incorrect assumptions about separateness and causality.

g.lemaitre
Messages
267
Reaction score
2
I don't like the way Wiki describes entanglement. Here is my own definition. Tell me if it is in essence correct. If I have left out an important detail please let me know

objects are entangled if and only if by changing the property of one object one instantaneously changes the property of another object. Objects need not be next to each other in space.
 
Last edited:
Physics news on Phys.org
I guess I should add that by observing something you become entangled with it.
 
g.lemaitre said:
objects are entangled if and only if by changing the property of one object one instantaneously changes the property of another object. Objects need not be next to each other in space.

"Changing the property of an object" is just asking for trouble; that wording implies that the property had a pre-existing value that was changed by the act of measurement.

"By changing... one instantaneously changes..." suggests that there's some causality at work, and that's also going to get you in trouble in a number of ways.

But with that said, I have to admit that I share your distaste for the wikipedia non-definition. How about:
Two objects are entangled if their quantum states cannot be described separately, even though the individual objects may be spatially separated.
That's still not right, because it suggests that we have separate objects that we've somehow tied together, instead of a single quantum system that happens to be measured at different locations... But this defect may be inherent in the "entanglement" metaphor; you can't speak of entangling A and B without suggesting that they're "really" independent entities, and the entanglement is something that happened to them, like fish swimming into a net.
 
How about this definition. You seem to think that object A and B are the same object if they are entangled. For the moment, we'll stick with just the objects electrons. We know what it means when we say two electrons.

Two electrons are entangled iff by setting the properties of one you set the properties of the other. By measuring an electron you become entangled with it.

Also, how accurate is it to say that everything in the universe is entangled. After all, the properties of the objects in the universe are affected by temperature and temperature is set by a collection of objects, their mean kinetic energy. An object can only be affected by another object if it is entangled with it.
 

Similar threads

  • · Replies 41 ·
2
Replies
41
Views
6K
  • · Replies 58 ·
2
Replies
58
Views
5K
  • · Replies 22 ·
Replies
22
Views
3K
  • · Replies 8 ·
Replies
8
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 41 ·
2
Replies
41
Views
7K
  • · Replies 112 ·
4
Replies
112
Views
11K
  • · Replies 59 ·
2
Replies
59
Views
6K
  • · Replies 19 ·
Replies
19
Views
4K
  • · Replies 87 ·
3
Replies
87
Views
9K