# What does oberserve mean

1. Jul 16, 2011

### idknothing

What does "oberserve" mean

This is probably a really dumb question but here it goes:

Okay really its just what the title says, when quantum mechanics describes that particles behave like waves when not observed and particles when observed, does it mean when light is on them, or literally when a living being is watching?

2. Jul 17, 2011

### xts

Re: What does "oberserve" mean

You are asking one of those open, everlasting questions about QM interpretation, being more metaphysical (thus open...) than physical.

Copenhagen: (uncle Bohr spanks you with his hairy, hairy paw) you behave like Elephant's child! Shut up, and calculate!
Common-sense realism: observation - something irreversible happens (e.g. a grain of AgBr in photo film is hit by a photon)
Consciousness based interpretation: observation takes place when some conscious creature sees experiment results
Subjectivistsic and solipsistic approaches: when I (ond only I, not you, nor your cat) see the result
Many Worlds: observation? there is nothing like observation! wavefunction never collapses!

Choice between those is a matter of metaphysical taste. All of them lead to the same practical results.

EDITED (CORRECTION) >>>
That's not true that all lead to the same practical results. Only common-sense realism, or even further simplifications are feasible. If you analyse e.g. double slit experiment, you stop analysis at the moment when your particle hits the screen (film, detector, etc.) No one ever tried to compute mixed wavefunction of the excited and not-excited detector (nor of dead and alive cat) and follow quantum computations up to a human observer. We just believe that it would lead to the same final result.
<<<

Last edited: Jul 17, 2011
3. Jul 17, 2011

### harrylin

4. Jul 17, 2011

### Delta Kilo

Re: What does "oberserve" mean

Quantum observation (or measurement) happens when quantum system interacts with macroscopic system, potentially causing macroscopically noticeable effects. Macroscopic system is assumed to be composed of huge number of interacting microscopic systems (atoms/molecules/...), but due to sheer complexity and lack of information about initial state of each atom, it cannot be described quantum-mechanically but only classicaly.

5. Jul 17, 2011

### xts

Re: What does "oberserve" mean

If you say the same in a bit different words:
particles behave like waves when propagating and like particles when interacting with others''
you'll be more precise and then you may avoid metaphysical dillemas.

6. Jul 17, 2011

### HydroHyper

Re: What does "oberserve" mean

Observation is the inspection of information that is accumulated by different states of consciousness, which differentiates on who the observer is for obvious enough reasons. To me this is still edgy considering consciousness appears to have no definite location, and to have an insubstantial quality.

applying observation in Quantium Theory (Quantum Consciousness) is more of a philosophy on why it effects the partical proccesses since these are reasonably still unkown things like is the brain receiving it or creating it and if it does receive it does consciousness have a physical state of its own in which it projects on to particals when they are being observed?

and since this is a physics forum I'll just sum this up nicely with this last statement.

For now the only physical accounts for observation are the mesurments in what your observing and the state of your neurological function.

7. Jul 17, 2011

### Hurkyl

Staff Emeritus
Re: What does "oberserve" mean

As used in quantum physics, "observation" means "anything that behaves the way quantum mechanics says observations behave", nothing more, nothing less.

Of course, the choice of word was meant to be suggestive, that a quantum mechanical observation occurs somehow in the process of a human physically looking an empirical result. (although it could happen at other times too)

8. Jul 17, 2011

### Naty1

Re: What does "oberserve" mean

It means that when a quantum wave is disturbed, and observation ALWAYS disturbs a quantum phenomena in some way, the observed wave becomes quantized...becomes confined in space.

In your example, it makes no difference if a "live being" is observing the reflected light or not; the light, electromagnetic radiation, impinging on a quantum particle, say an electron, will disturb it by imparting some energy to the particle. That's why we cannot observe round electron orbits, used in the simplest introductory models, about a nucleus. Any measurement attempt disturbs the electron cloud (wave). The shorter the wavelength of light, for better resolution, the more energy is transferred to the particle under observation and the more it becomes disturbed (energized) by ANY apparatus.