Observers

A

arfa brane

call me arf
Valued Senior Member
There is nothing special about observers because:

* All particles in the universe can interact with each other.
* We are systems of particles.
* Observation is interaction.
* We suppose we can group together our system of particles (put parentheses around ourselves or other observers), or group things together in our world, but that's because we think we're special.
* Physics would be impossible if there were special observers.
?
 
arfa brane said:
There is nothing special about observers because:

* All particles in the universe can interact with each other.
* We are systems of particles.
* Observation is interaction.
* We suppose we can group together our system of particles (put parentheses around ourselves or other observers), or group things together in our world, but that's because we think we're special.
* Physics would be impossible if there were special observers.
?
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Just because some particle has interacted with some particle of which an observer is comprised is no guarantee that anything has been "observed", because most of our corporeal particles may be incapable of making an observation.

Observation, either by means of instrumentation or sensory apparatus, ALWAYS entails CHOOSING A DIRECTION in which to observe something. Our eyes choose a direction in which to observe photons because that's what observing is supposed to accomplish. Even saccades are important in this process, akin to some sort of sampling I suppose.

The double slit experiment is the best example of this it is possible to give. Choosing a slit to observe means that you have chosen a direction to observe, separated only slightly from the only other choice for observation in the experiment.
 
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danshawen said:
Just because some particle has interacted with some particle of which an observer is comprised is no guarantee that anything has been "observed", because most of our corporeal particles may be incapable of making an observation.

Observation, either by means of instrumentation or sensory apparatus, ALWAYS entails CHOOSING A DIRECTION in which to observe something.

The double slit experiment is the best example of this it is possible to give. Choosing a slit to observe means that you have chosen a direction to observe, separated only slightly from the only other choice for observation in the experiment.
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What though , if there is more observers than just you ?
 
DaveC426913 said:
Correct.

Only pop-sci readers and laypeople misinterpret what observer means in QM.
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Although historically there have been eminent QM theoreticians who wrestled with this. See for example Von Neumann-Wigner interpretation.

But certainly the modern view seems to have dismissed these speculations.

It seems to me a large part of the problem is the unfortunate use of the term "observer", probably historically imported from its use in Einstein's development of relativity. What is really meant is "measurement system", whether animate or otherwise. It is the interaction with a measurement system that determines the values subsequently measured, which may then be observed - if a conscious observer happens to be present.
 
exchemist said:
Although historically there have been eminent QM theoreticians who wrestled with this. See for example Von Neumann-Wigner interpretation.

But certainly the modern view seems to have dismissed these speculations.

It seems to me a large part of the problem is the unfortunate use of the term "observer", probably historically imported from its use in Einstein's development of relativity. What is really meant is "measurement system", whether animate or otherwise. It is the interaction with a measurement system that determines the values subsequently measured, which may then be observed - if a conscious observer happens to be present.
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How can values be measured with out an observer ?
 
Energy is something we can get information about, or observe, because:

1) We can observe a system doing work.
2) We get the information by measuring time and distance, this is actually what any measurement does.
3) Neither of the above.
 
arfa brane said:
Energy is something we can get information about, or observe, because:

1) We can observe a system doing work.
2) We get the information by measuring time and distance, this is actually what any measurement does.
3) Neither of the above.
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Primative
 
DaveC426913 said:
QM ticked along quite nicely before anybody came along to apply values to them.
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Er, well, physical reality ticked along. QM is a human construct that models that reality. It is possible in principle that there could be a conceptual defect in QM that implies a conscious observer, without this having a counterpart in reality. Most people nowadays don't think there is a defect of this sort, however - at least not so far as I understand.
 
arfa brane said:
* Observation is interaction.
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Need not be. We observe a supernova happening, without interacting with it. We observe an aircraft flying without interacting with it.

May be at QM level things would be different, but not at macro.level. the measurent can be done without as such interacting with the event System. In fact most of the time observation is post event.
 
The God said:
Need not be. We observe a supernova happening, without interacting with it. We observe an aircraft flying without interacting with it.
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I think you could be forgetting that our observation of objects we can't reach out and touch because they're too far away, is an interaction with the radiation from those objects.

Indeed, if EM radiation didn't interact with matter, you wouldn't be able to observe. Anything. At. All.

The universe would have different laws of physics too.
 
Back to the universe we know and love: we have observation. When you observe light from a distant object, it's because electrons in your retinal cells are collecting energy.

But is the energy being "observed", or do we only observe "information"--how bright the source is, its apparent diameter, colours etc.
Is energy observable, or is information about time and distance the actual observation?
 
arfa brane said:
I think you could be forgetting that our observation of objects we can't reach out and touch because they're too far away, is an interaction with the radiation from those objects.

Indeed, if EM radiation didn't interact with matter, you wouldn't be able to observe. Anything. At. All.

The universe would have different laws of physics too.
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I said "event system". We are as such not interacting with the event.
 
QuarkHead said:
How can you be sure? Do you have a proof of this bold assertion?
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Yes.

When I leave the living room with the light on, it is generally still on when I come back in.
When I leave the living room with the light off, it is general still off when I come back in.

Now, you may argue I have no proof what happened while I was not in the room - but - whatever may or may not have happened, something did preserve the state of the room while I was gone. In fact, were I to do a controlled experiment in a lab, with enough sensors and gadgets, I could determine that the state of (pretty much) every particle in the room was somehow preserved over the time that I was not observing it.

So, I can prove that the state before and after were in sync, and by inference, the state was preserved during that time - the only thing I can't prove is that a lot of extra stuff (like elves coming in, measuring everything, breaking it all down and reassembling it) did not happen.

Nonetheless, in some form or another, what I experience as reality was preserved across the duration.
 
DaveC426913 said:
Yes.

When I leave the living room with the light on, it is generally still on when I come back in.
When I leave the living room with the light off, it is general still off when I come back in.

Now, you may argue I have no proof what happened while I was not in the room - but - whatever may or may not have happened, something did preserve the state of the room while I was gone. In fact, were I to do a controlled experiment in a lab, with enough sensors and gadgets, I could determine that the state of (pretty much) every particle in the room was somehow preserved over the time that I was not observing it.

So, I can prove that the state before and after were in sync, and by inference, the state was preserved during that time - the only thing I can't prove is that a lot of extra stuff (like elves coming in, measuring everything, breaking it all down and reassembling it) did not happen.

Nonetheless, in some form or another, what I experience as reality was preserved across the duration.
Click to expand...

Or at least you can invoke the principle of parsimony and say there is no point in suggesting that nature is not continuous between these observations, as any such discontinuity is unobservable. :smile:
 
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