But if you don’t watch, it acts like a wave and can go through both slits at the same time?

A bit like Schrödinger's cat, is it?

OristarA said: So how can a particle change its behavior depending on whether you watch it or not? The answer is simple – reality is a process that involves your consciousness.

There's nothing more complicated than a cat.

When I call my dog, he comes running.

When I call my cat, she just takes a message and promises to get back to me later.

The Copenhagen Interpretation of quantum mechanics states that when a system possesses different values of a dynamical variable simultaneously, each with some probability, measurement of any kind will force it to choose one and only one value of the variable. The alternate explanation is the Many Worlds Interpretation in which the universe is constantly splitting into more and more mutually unobservable universes and every possible outcome happens in one of them.

Brandon9000 wrote:

The Copenhagen Interpretation of quantum mechanics states that when a system possesses different values of a dynamical variable simultaneously, each with some probability, measurement of any kind will force it to choose one and only one value of the variable. The alternate explanation is the Many Worlds Interpretation in which the universe is constantly splitting into more and more mutually unobservable universes and every possible outcome happens in one of them.

Cool. What force drives them to split then?

Maxdonca said: For anyone who has taken an quantum mechanics, or even an optics course... this video is nonsense.

This article is non-scientific nonsense. There is nothing "consciouslness-affecting" about the "particle behavior stuff". The writer is spouting new-age spiritualistic garbage... and throwing in random science phrases to make it sound plausible.

There are some good scientific explanations of the double slit experiment out there.

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

http://www.youtube.com/watch?v=Iuv6hY6zsd0

In the basic version of this experiment, a coherent light source such as a laser beam illuminates a plate pierced by two parallel slits, and the light passing through the slits is observed on a screen behind the plate.[2][3] The wave nature of light causes the light waves passing through the two slits to interfere, producing bright and dark bands on the screen—a result that would not be expected if light consisted of classical particles.[2][4] However, the light is always found to be absorbed at the screen at discrete points, as individual particles (not waves), the interference pattern appearing via the varying density of these particle hits on the screen.[5] Furthermore, versions of the experiment that include detectors at the slits find that each detected photon passes through one slit (as would a classical particle), but not through both slits (as would a wave).[6][7][8][9][10] These results demonstrate the principle of wave–particle duality.

Quote:

Maxdonca said: For anyone who has taken an quantum mechanics, or even an optics course... this video is nonsense.

But Prof Zeilinger in the vid has got good street cred, so why does he bravely admit he can't explain the double-slit experiment mystery?

WIKI- Anton Zeilinger is an Austrian quantum physicist who in 2008 received the Inaugural Isaac Newton Medal of the Institute of Physics (UK) for "his pioneering conceptual and experimental contributions to the foundations of quantum physics.
Zeilinger is professor of physics at the University of Vienna and Senior Scientist at the Institute for Quantum Optics and Quantum Information IQOQI at the Austrian Academy of Sciences.
http://en.wikipedia.org/wiki/Anton_Zeilinger

This article is non-scientific nonsense. There is nothing "consciouslness-affecting" about the "particle behavior stuff". The writer is spouting new-age spiritualistic garbage... and throwing in random science phrases to make it sound plausible.

There are some good scientific explanations of the double slit experiment out there.

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

http://www.youtube.com/watch?v=Iuv6hY6zsd0

Our linear way of thinking about time is also inconsistent with another series of recent experiments. In 2002, scientists showed that particles of light “photons” knew – in advance – what their distant twins would do in the future. They tested the communication between pairs of photons. They let one photon finish its journey – it had to decide whether to be either a wave or a particle. Researchers stretched the distance the other photon took to reach its own detector. However, they could add a scrambler to prevent it from collapsing into a particle. Somehow, the first particle knew what the researcher was going to do before it happened – and across distances instantaneously as if there were no space or time between them. They decide not to become particles before their twin even encounters the scrambler. It doesn’t matter how we set up the experiment. Our mind and its knowledge is the only thing that determines how they behave. Experiments consistently confirm these observer-dependent effects.

Bizarre? Consider another experiment that was recently published in the prestigious scientific journal Science (Jacques et al, 315, 966, 2007). Scientists in France shot photons into an apparatus, and showed that what they did could retroactively change something that had already happened in the past. As the photons passed a fork in the apparatus, they had to decide whether to behave like particles or waves when they hit a beam splitter. Later on – well after the photons passed the fork – the experimenter could randomly switch a second beam splitter on and off. It turns out that what the observer decided at that point, determined what the particle actually did at the fork in the past. At that moment, the experimenter chose his past.

Oristar said:...Scientists in France shot photons into an apparatus, and showed that what they did could retroactively change something that had already happened in the past...