Properties and interaction

[Joseph Flatt]

TL;DR Summary

How can the environment interact with a quantum object with no definite properties?

How can a quantum object interact with its environment before it has any definite properties? It seems like a ‘chicken and egg’ scenario to me. I can’t see how anything could interact with a quantum object which has only potential properties (what is there to interact with?), yet if I’ve understood things correctly, a quantum object gains definite properties only through interaction. Is it assumed that there are properties that quantum objects always have? Or (more likely), am I missing something obvious?

 

[DrChinese]

Summary:: How can the environment interact with a quantum object with no definite properties?

Great question. First, quantum objects have properties at all times. Those properties do not have definite values prior to measurement. For example: a free neutron may have a position of X+/-dx, Y+/-dy, Z+/-dz at time T+/-dt. A suitable measurement can either reduce the position uncertainty (the delta x, y, z, t) or increase it.

Second, quantum interactions are generally random and probabilistic. At the time/place of interactions, the values of some properties take shape. The values will obey the Heisenberg Uncertainty Principle, and the value may be tightly defined or it may be loosely defined (depending on the nature of the interaction/measurement). There is nothing that prevents an interaction between 2 particles from occurring just because their positions are uncertain. It just means there are more places that interaction could occur (places where the probability of finding them at the same time overlap).

 

[Joseph Flatt]

Great question. First, quantum objects have properties at all times. Those properties do not have definite values prior to measurement. For example: a free neutron may have a position of X+/-dx, Y+/-dy, Z+/-dz at time T+/-dt. A suitable measurement can either reduce the position uncertainty (the delta x, y, z, t) or increase it.

Second, quantum interactions are generally random and probabilistic. At the time/place of interactions, the values of some properties take shape. The values will obey the Heisenberg Uncertainty Principle, and the value may be tightly defined or it may be loosely defined (depending on the nature of the interaction/measurement). There is nothing that prevents an interaction between 2 particles from occurring just because their positions are uncertain. It just means there are more places that interaction could occur (places where the probability of finding them at the same time overlap).

Thanks, DrChinese. That makes things clearer. My mistake was equating ‘properties’ with ‘definite values’. Interaction requires the former but not the latter.

 

[Killtech]

Summary:: How can the environment interact with a quantum object with no definite properties?

How can a quantum object interact with its environment before it has any definite properties? It seems like a ‘chicken and egg’ scenario to me. I can’t see how anything could interact with a quantum object which has only potential properties (what is there to interact with?), yet if I’ve understood things correctly, a quantum object gains definite properties only through interaction. Is it assumed that there are properties that quantum objects always have? Or (more likely), am I missing something obvious?

Well, what properties a quantum system has or hasn't is really just interpretation.

If you think of the results of measurement as describing the properties of a quantum object, then yes you would be right.

But you could just as much assume something like the wave function to describe the actual properties of a quantum object. Then it would have definite properties and values at all times - but then measurement would be an inadequate method to retrieve them only giving very vague ideas about the original state. In fact, it would barely count as a measurement since its results would only tell you what it changed the state into with nothing more then an indication of what the state previously really was. But it would the the best thing we have, so yeah.

There are more interpretations around, if you don't like both answers above. There is no consensus answer to your question and no interpretation changes the ultimate results you get from the math anyway, so you can pick the one you can make the most sense of. Or the one most you find the most intriguing/exiting. The question really is what your mind can best work with as it is meaningless in terms how the world really works.

 

[Joseph Flatt]

There is no consensus answer to your question and no interpretation changes the ultimate results you get from the math anyway, so you can pick the one you can make the most sense of. Or the one most you find the most intriguing/exciting. The question really is what your mind can best work with as it is meaningless in terms how the world really works.

Well, if there‘s a ‘way the world works’ and I’m part of the world, presumably the world will be picking an interpretation for me anyway, so I don’t need to bother.