Double Slit Experiment

[atanu]

In short: When scientists (instruments of course) watch a particle pass through two slits, the particle goes through one slit or the other. If a person doesn't watch it, it acts like a wave and can go through both slits simultaneously.

How is this explained by physicists?

(I did not see this subject through search, although I might have missed it.)

 

[metis]

Photons have both a particle and wave manifestation, sometimes being both at the same time. It is the wave function that may explain the answer, however the bigger question is why does there seem to be some interaction between the photons and the viewer?

 

[George-ananda]

How is this explained by physicists?

One physicist (and advaitan) Amit Goswami says the experiment shows downward causation; consciousness effects matter. Here is how the physicist explains it:

The current worldview has it that everything is made of matter, and everything can be reduced to the elementary particles of matter, the basic constituents — building blocks — of matter. And cause arises from the interactions of these basic building blocks or elementary particles; elementary particles make atoms, atoms make molecules, molecules make cells, and cells make brain. But all the way, the ultimate cause is always the interactions between the elementary particles. This is the belief — all cause moves from the elementary particles. This is what we call "upward causation." So in this view, what human beings — you and I think of as our free will does not really exist. It is only an epiphenomenon or secondary phenomenon, secondary to the causal power of matter. And any causal power that we seem to be able to exert on matter is just an illusion. This is the current paradigm.

Now, the opposite view is that everything starts with consciousness. That is, consciousness is the ground of all being. In this view, consciousness imposes "downward causation." In other words, our free will is real. When we act in the world we really are acting with causal power. This view does not deny that matter also has causal potency — it does not deny that there is causal power from elementary particles upward, so there is upward causation — but in addition it insists that there is also downward causation. It shows up in our creativity and acts of free will, or when we make moral decisions. In those occasions we are actually witnessing downward causation by consciousness.

 

[fantome profane]

One thing to keep in mind is that it is impossible to observe a particle without physically interacting with it. So it is not exactly true to say that simply observing a particle affects the way it acts. It is more actuate to say that physically interacting with a particle affects it. Looking at it that way it is not that strange.

 

[viole]

One physicist (and advaitan) Amit Goswami says the experiment shows downward causation; consciousness effects matter. Here is how the physicist explains it:

The current worldview has it that everything is made of matter, and everything can be reduced to the elementary particles of matter, the basic constituents — building blocks — of matter. And cause arises from the interactions of these basic building blocks or elementary particles; elementary particles make atoms, atoms make molecules, molecules make cells, and cells make brain. But all the way, the ultimate cause is always the interactions between the elementary particles. This is the belief — all cause moves from the elementary particles. This is what we call "upward causation." So in this view, what human beings — you and I think of as our free will does not really exist. It is only an epiphenomenon or secondary phenomenon, secondary to the causal power of matter. And any causal power that we seem to be able to exert on matter is just an illusion. This is the current paradigm.

Now, the opposite view is that everything starts with consciousness. That is, consciousness is the ground of all being. In this view, consciousness imposes "downward causation." In other words, our free will is real. When we act in the world we really are acting with causal power. This view does not deny that matter also has causal potency — it does not deny that there is causal power from elementary particles upward, so there is upward causation — but in addition it insists that there is also downward causation. It shows up in our creativity and acts of free will, or when we make moral decisions. In those occasions we are actually witnessing downward causation by consciousness.

Not necessarily.

It can be that the observation splits the one observing consciousness in two, both in a superposition of states.

One observes the particle following one path, the other observes it going the other way. They both exist, in a way.

You make the assumption that consciousness affects physics, whereas it could be the other way round.

Ciao

- viole

 

[bobhikes]

In short: When scientists (instruments of course) watch a particle pass through two slits, the particle goes through one slit or the other. If a person doesn't watch it, it acts like a wave and can go through both slits simultaneously.

How is this explained by physicists?

(I did not see this subject through search, although I might have missed it.)

Its explained in quantum physics.

 

[atanu]

Its explained in quantum physics.

Ha ha. The best answer.

 

[crossfire]

One thing to keep in mind is that it is impossible to observe a particle without physically interacting with it. So it is not exactly true to say that simply observing a particle affects the way it acts. It is more actuate to say that physically interacting with a particle affects it. Looking at it that way it is not that strange.

Yep. A photon is a virtual particle that manifests in order to transfer energy. A photon gets all of its properties from the wave--it has no mass or charge of its own.

 

[psychoslice]

One thing to keep in mind is that it is impossible to observe a particle without physically interacting with it. So it is not exactly true to say that simply observing a particle affects the way it acts. It is more actuate to say that physically interacting with a particle affects it. Looking at it that way it is not that strange.

I like that way of seeing it, interesting.

 

[Runewolf1973]

Not necessarily.

It can be that the observation splits the one observing consciousness in two, both in a superposition of states.

One observes the particle following one path, the other observes it going the other way. They both exist, in a way.

You make the assumption that consciousness affects physics, whereas it could be the other way round.

Ciao

- viole

Hmm... I wonder if it's kinda like when you watch the spokes on a wheel spinning really fast in one direction, but it may appear to us to be spinning the opposite direction at times. It is like an illusion or trick of the mind.

 

[crossfire]

One thing I find quite interesting is that they have been able to do the double slit experiment with something as large as bucky-balls, a molecule with 60 atoms of carbon!

Buckminsterfullerene - Wikipedia, the free encyclopedia

Wave

 

[atanu]

"If you can explain this using common sense and logic, do let me know, because there is a Nobel Prize for you."

The Double-slit Experiment : Ri Channel

http://abyss.uoregon.edu/~js/21st_century_science/lectures/lec13.html

 

[atanu]

One thing to keep in mind is that it is impossible to observe a particle without physically interacting with it. So it is not exactly true to say that simply observing a particle affects the way it acts. It is more actuate to say that physically interacting with a particle affects it. Looking at it that way it is not that strange.

Thoughtful answer. I have a doubt however. The, question, IMO, remains as to how the particle/s know of the observation. Physical interaction is common, with or without the observer. And observer could be human eyes observing the experiment or video cameras positioned at the slits. In both cases, where the observer is present, the pattern of recording suggests that the photon acted a s a particle, otherwise as wave.

Thanks

 

[Rick O'Shez]

How is this explained by physicists?

Both wave and particle. Wierd!

 

[atanu]

What I really like about this is the recognition that the observation, of a wave form or of a particle, is not the reality behind the observation.


"Wave-particle duality does not mean that a photon or subatomic particle is both a wave and particle simultaneously, but that it could manifest either a wave or a particle aspect depending on circumstances."

"Central to the Copenhagen Interpretation is the principle known as complementarity. That the wave and particle nature of objects can be regarded as complementary aspects of a single reality, like the two sides of a coin."

Copenhagen Interpretation

 

[atanu]

Both wave and particle. Wierd!

More weird is of course the fact that the mere act of putting video cameras on the slits make the photons act like particles.

 

[crossfire]

Thoughtful answer. I have a doubt however. The, question, IMO, remains as to how the particle/s know of the observation. Physical interaction is common, with or without the observer. And observer could be human eyes observing the experiment or video cameras positioned at the slits. In both cases, where the observer is present, the pattern of recording suggests that the photon acted a s a particle, otherwise as wave.

Thanks

When you observe a photon, you are, by definition on the quantum level, interacting with it.

 

[atanu]

When you observe a photon, you are, by definition on the quantum level, interacting with it.

I do not understand it.

 

[George-ananda]

When you observe a photon, you are, by definition on the quantum level, interacting with it.

But the mystery is that you are not interacting with the photon in any way that should effect it in the classical view of the universe. Why should observation matter?

 

[Avi1001]

When you look at an Escher drawing are you, as the observer, influencing the outcome ?

When a blind man describes an elephant by touching it in different places, is he influencing the outcome ?

The observer is seeing embedded reality from different perspectives.

Quantum computing is perhaps the best potential application for this phenomenon. It is still in its infancy:

http://en.wikipedia.org/wiki/Quantum_computer