Observers

[QuarkHead]

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.

OK. So your assertion is that an observed system behaves in exactly the same way as an unobserved system?

Or to put it another way; if I determine the eigenstate of a system to have particular value at a particular time, I may assume this system always to have had that particular value in the past and always will.

 

[exchemist]

OK. So your assertion is that an observed system behaves in exactly the same way as an unobserved system?

Or to put it another way; if I determine the eigenstate of a system to have particular value at a particular time, I may assume this system always to have had that particular value in the past and always will.

No that's silly. He's talking about a light switch, not every physical system in the universe.

 

[Confused2]

Clocks seem to carry on just the same whether or not they are observed.

 

[gmilam]

OK. So your assertion is that an observed system behaves in exactly the same way as an unobserved system?

How would you know the state of an unobserved system without... (wait for it...) observing it?

 

[QuarkHead]

No that's silly. He's talking about a light switch, not every physical system in the universe.

No he is using an everyday analogy to give a "proof" of the general case
Take a peek at this....

QM ticked along quite nicely before anybody came along to apply values to them.

ipso facto I rest my case

 

[Confused2]

I think Quarkhead might have a cat.
https://en.wikipedia.org/wiki/Schrödinger's_cat

 

[DaveC426913]

OK. So your assertion is that an observed system behaves in exactly the same way as an unobserved system?

No. The initial assertion was:
Nature goes on with or without observations.
To which you responded: How can you be sure? Do you have a proof of this bold assertion?

I am simply pointing out that nature did go on while it while not being observed - as witnessed by the fact that, (under normal circumstances) everything was where it was expected to be* when it was subsequently observed.

It is an inescapable conclusion that, whatever reality existed in that room before I left was preserved (perhaps recorded and replayed, but still - preserved). i.e. "nature" - as I experienced it - did indeed "go on" without being observed.


* stuff may move, but it's not unexpected


It's possible to extrapolate to "an observed system behaves in exactly the same way as an unobserved system", but I'd have to think about that.

 

[Dinosaur]

The significance of a human observer has been exaggerated due to technical writers misunderstanding explanations provided by knowledgeable physicists

The Copenhagen interpretation of quantum reality makes a remark similar to the following

Quantum level entities cannot be said to have properties until/unless the quantum level entity has some effect on (or interaction with) a classical level entity or process.

 

[QuarkHead]

I am simply pointing out that nature did go on while it while not being observed

Oh dear - what does it mean for "nature to go on"?

It's possible to extrapolate to "an observed system behaves in exactly the same way as an unobserved system", but I'd have to think about that.

Yes you would. A quantum state (for example) remains indeterminate until measured.

 

[DaveC426913]

Oh dear - what does it mean for "nature to go on"?

Agree. It's not exactly a scientific term, but I didn't choose it.

Nonetheless, I can leverage that ambiguity. Essentially, in this context, I am determining it to mean anything I, as a human mortal, can detect. i.e. I know that what I experience as the natural world is preserved while I am not watching.

This is really a sidebar; it is not really germaine to the primary thread, I was just responding to the challenge of whether nature ticks along when we're not watching.

 

[arfa brane]

I said "event system". We are as such not interacting with the event.

With which event?

An event looks a lot like an interaction/observation, at least in SR it does. Events convey information too.

Note how a spacetime event is effectively a measurement of time and distance.
Note also how difficult it is to show that a measurement can be of anything else than time and distance.

 

[DaveC426913]

Note also how difficult it is to show that a measurement can be of anything else than time and distance.

Colour? Mass? Charge?

 

[arfa brane]

Colour? Mass? Charge?

I'm sorry Dave, you can't measure that either.

How do you measure mass, here on planet Earth? You weight it: you get information about a displacement, calibrated to standard kg, i.e. you actually measure a distance.
A balance scale lets you calibrate the weightings, at zero displacement two different masses are equally weighted.

See if you can do it another way.

 

[The God]

With which event?

An event looks a lot like an interaction/observation, at least in SR it does. Events convey information too.

Note how a spacetime event is effectively a measurement of time and distance.
Note also how difficult it is to show that a measurement can be of anything else than time and distance.

I said I do not have the proof, mainly because the issue of observation classically and QMly may be different.

Now take two modus of observations..

1. Monitoring the system by measuring the light signal transmitted/emitted by the observed system.

2. Monitoring the system by sending the light signal from observation device and recording thereof.

I feel, that methodology 1, will fall into a description where observation may not impact the system state. But in #2 it could.

 

[arfa brane]

Two years ago, the first experiment that verified the quantum Zeno effect applies to 'real' space measurements of atomic motion was performed at Cornell.

In quantum mechanics, the interaction mentioned is called "measurement" because its result can be interpreted in terms of classical mechanics.

Frequent measurement prohibits the transition. It can be a transition of a particle from one half-space to another (which could be used for atomic mirror in an atomic nanoscope[19]) as in the time of arrival problem,[20][21] a transition of a photon in a waveguide from one mode to another, and it can be a transition of an atom from one quantum state to another.

It can be a transition from the subspace without decoherent loss of a qubit to a state with a qubit lost in a quantum computer.[22][23] In this sense, for the qubit correction, it is sufficient to determine whether the decoherence has already occurred or not. All these can be considered as applications of the Zeno effect.[24]

By its nature, the effect appears only in systems with distinguishable quantum states, and hence is inapplicable to classical phenomena and macroscopic bodies.

--https://en.wikipedia.org/wiki/Quantum_Zeno_effect

Clearly measurement has a time component--wavefunctions don't "collapse" instantaneously.

 

[The God]

Ex1. Take for example BH BH merger (GW fame), the event had nothing to do with our observation / detection.

Ex2. Take any Supernova observation, no interaction with event whatsoever, it is the radiation emitted which we measure/observe. We cannot even send a probe light signal.

So the interaction is basically with the (light, sound, spacetime changes) only in case of measurement, not with the event as such.

 

[arfa brane]

'sigh'

Ex1. Take for example BH BH merger (GW fame), the event had nothing to do with our observation / detection.

Then how do we know such things happen? How do we explain the gravitational wave observatory and its observations?

Ex2. Take any Supernova observation, no interaction with event whatsoever, it is the radiation emitted which we measure/observe. We cannot even send a probe light signal.

Yes, we interact with the radiation emitted, this in fact is the "supernova event", which we can say absolutely nothing about until the light arrives.
What you seem to be saying is we can't interact with such an event if we aren't "there when it happens". But we do interact with it at a different time.

 

[The God]

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

We observed merging of BHs without any EM radiation of that event.

We observe someone honking without EM radiation. (Sound waves).

Detecting the EM radiation as emitted by an object (event) or detecting a sound wave as emitted by a trumpet, is not same as interacting with the event.

You have this habit of convenient improvisation without acknowledging. Take care.

 

[arfa brane]

We observed merging of BHs without any EM radiation of that event.

Incorrect. We did not directly observe gravitational waves, we observed two laser beams interacting with mirrors and detectors.

Detecting the EM radiation as emitted by an object (event) or detecting a sound wave as emitted by a trumpet, is not same as interacting with the event.

Detection is an event, you twit.

 

[The God]

Incorrect. We did not directly observe gravitational waves, we observed two laser beams interacting with mirrors and detectors.

Detection is an event, you twit.

Good for you kid, you are learning lot of things; Physics, maths and abuses too.

But I suggest go slow on abuses, and don't even try to teach your pop how to screw.