ASK Me Physics: What does observation mean in youngs double slit experiment.
i have periods where i am very busy, so sorry for how late this is.
Now this is about "youngs double slit experiment." This is an extremely well documented and repeated experiment.
Now for anyone thats doesnt know what this experiment is about you can find a link here (which was linked to me when asked this question.)
I find that this explains it much better than i couple through writing.
Anyway, so i was asked why observing the electron causes it to change what it does and what observation means in this case.
So what we have to understand is that an electron and other small particles on this scale do not behave as we would consider normal. They are not waves and they are not particles, they are in effect both at the same time. This might seem strange and confusing but im barely scratching the ice how complicated this can get.
The fact is that these particles are in fact a superposition of states. This means that there are many many states this particle can be in each, are possible but have varying degrees of likeliness (probability changes). So when we say it moves as a wave it does but the wave also corresponds to the probability of its states.
Looking at that video we can see that there is constructive and destructive interference, this applies to the probability. so with constructive interference there is a higher probability of the particle being there and lower for destructive.
So we have a collection of states moving and behaving like a wave. This creates what is known as a "wavefunction". This wavefunction describes this particle. However, if we do something to this particle for example observe the particle then the wavefunction collapses and a value is produced eg its position. Once the wavefunction is collapsed we know where its going and its velocity etc. In other words, it acts like a particle, not a wave.
I speak like this is all true but quantum mechanics are still heavy disputed so take it all with a pinch of salt.
The idea is that this wave of probabilities moves as a wave. There is no specific point that this electron or photon is positioned. It moves as a probability of its existence being in different places. However once we measure it, it exists in a spot. We have removed all the other probabilities of its existence and we know for sure where it is. It cannot therefore move as a wave anymore.
So momentum and position measurements do this to a particle. however every single form of observing a particle will give us an idea of its momentum or position. eg light uses photons and photos interact with particles and the wave they interact gives us information. So the fact of the universe is that we cant "see" the particle in anyway without collapsing its wavefunction and defining its position or momentum.
Thank you very much for this explanation.
For this couple of weeks I was still searching through internet to understand what is really going on with this electron during act of observation And it looks like the more I know about quantum mechanics the less I understand. But on the other hand some time ago I was told something like if you think you understand quantum mechanics, you probably don't understand quantum mechanics. So it's good enough for me that at least I do understand equations describing behavior of electron :)
For now I more or less understand that to make any measurements of electron we use photons that somehow interact with wave of probabilities, making only one of these probabilities a measured state of electron.
My question could be in fact phrased as: is intelligence or consciousness anyhow connected with collapsing of wave?
And after your answer and several other articles I read recently I am sure the answer is no... unfortunately.
BTW, my question and all "research" I made later was inspired by SF story "Divining Light" by Ted Kosmatka.
well the idea of intelligence and consciousness in the universe is a huge area of study and wonder. Nothing can be discarded in that area until we have a been understanding. When you think about it the idea of sentient beings in the universe is weird. It does make sense or reason. It is in fact why some physics hold the idea of a god.
In fact life seems to counteract the laws of entropy, though new research suggested that life is the most efficient form of entropy, so as to get to a state of lowest entropy quicker there has to be strange cases of increasing entropy (life). There is also the Anthropic principle which has interesting conclusions on life.
Once again thanks for detailed explanation, and for your thougths about consciousness of the universe :) There is a lot of SF novels that explores that ideas. I think I should read a little bit more about scientifics theories behind that, so that I have some knowledge base while reading.
BTW. I really have no idea, why your answers are not upvoted. In my opinion they are very, very interesting and valueable.
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