the double slit experiment

[UpFromTheSkies]

The double slit experiment, as I understand it (I'm not a scientist), shows that photon behavior is affected by observation. To me, this seems to imply that either the photon is "aware" that it's being observed, or that we have some sort of strange "psychic" ability that can alter reality. Is this true? Cause it sounds like bullshit to me.

[gmilam]

Sounds like bullshit to me too. The double slit experiment, as I understand it (I'm not a scientist), shows that photon behavior is affected when we try to measure it. To me, this seems to imply that we can't measure it without fucking with it.

[rpenner]

This sounds like "quantum woo." Certain New Age cult leaders like to confuse quantum mechanics (mysterious because it is knowable but not intuitive) with spiritual authority (mysterious because it's just making up stories which our culture values over actually knowing things).

[FTLinmedium]

Cause it sounds like bullshit to me.

This is correct, sir.

Measurement requires interference. It has nothing to do with human observation.

[UpFromTheSkies]

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[UpFromTheSkies]

Sounds like bullshit to me too. The double slit experiment, as I understand it (I'm not a scientist), shows that photon behavior is affected when we try to measure it. To me, this seems to imply that we can't measure it without fucking with it.

But how does measuring it affect it? Aren't we just recording it with a camera?

[UpFromTheSkies]

This sounds like "quantum woo." Certain New Age cult leaders like to confuse quantum mechanics (mysterious because it is knowable but not intuitive) with spiritual authority (mysterious because it's just making up stories which our culture values over actually knowing things).

That's exactly what I thought when I heard about this. People like to make up mystical bullshit to try and explain things that we don't understand.

[FTLinmedium]

But how does measuring it affect it? Aren't we just recording it with a camera?

Not exactly. Think about it- what does a camera do?

You can't use a camera to watch a single photon- cameras record light by destroying it (rather, turning it into a charge, or chemical change in a substance)

Any means of "observing" is ultimately more like a process of touching.

[Farsight]

Check out the physicsworld articles Catching sight of the elusive wavefunction and The secret lives of photons revealed. This concerns weak measurement where photon behavior is not affected by observation. At least not much. Also see Jeff Lundeen's web pages. His semi-technical explanation includes this:

"With weak measurements, it’s possible to learn something about the wavefunction without completely destroying it. As the measurement becomes very weak, you learn very little about the wavefunction, but leave it largely unchanged. This is the technique that we’ve used in our experiment. We have developed a methodology for measuring the wavefunction directly, by repeating many weak measurements on a group of systems that have been prepared with identical wavefunctions. By repeating the measurements, the knowledge of the wavefunction accumulates to the point where high precision can be restored.

So what does this mean? We hope that the scientific community can now improve upon the Copenhagen Interpretation, and redefine the wavefunction so that it is no longer just a mathematical tool, but rather something that can be directly measured in the laboratory."

[gmilam]

But how does measuring it affect it? Aren't we just recording it with a camera?

Cameras don't work well when you're talking about sub-atomic particles.

http://en.wikipedia.org/wiki/Double-slit_experiment

The double-slit apparatus can be modified by adding particle detectors positioned at the slits. This enables the experimenter to find the position of a particle not when it impacts the screen, but rather, when it passes through the double-slit — did it go through only one of the slits, as a particle would be expected to do, or through both, as a wave would be expected to do? Many early experiments found that modification of the apparatus that can determine which slit a particle passes through reduces the visibility of interference at the screen, thereby illustrating the complementarity principle: that light (and electrons, etc.) can behave as either particles or waves, but not both at the same time. But an experiment performed in 1987 produced results that demonstrated that information could be obtained regarding which path a particle had taken, without destroying the interference altogether. This showed the effect of measurements that disturbed the particles in transit to a lesser degree and thereby influenced the interference pattern only to a comparable extent. And in 2012, researchers finally succeeded in correctly identifying the path each particle had taken without any adverse effects at all on the interference pattern generated by the particles.

[Crunchy Cat]

The double slit experiment, as I understand it (I'm not a scientist), shows that photon behavior is affected by observation.

Correct.

To me, this seems to imply that either the photon is "aware" that it's being observed, or that we have some sort of strange "psychic" ability that can alter reality. Is this true? Cause it sounds like bullshit to me.

It's not true of course. An observer in physics is any system that can accept information (it can be a block of wood, a piece of cheese, etc.). In the double slit experiment what is happening is that an observer requires information as to the photon's location and as a result the photon wave collapses into a single particle at an exact location.