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Yesterday I tried to explain the significance of the 2022 Nobel prize in physics to my daughter, who is studying literature and has little physical or mathematical background.
The 2022 Nobel prize was awarded to Clauser, Aspect, and Zeilinger for their work on entanglement.
Entanglement is a correlation between objects. For example, a pair of gloves has a left hand and a right hand. Correlations give you information. If you find only one glove, you immediately know the other must be somewhere. So keep looking. You only do this because you know they come in pairs.
Nothing too surprising so far.
Now consider the surface of a road. There are black bitumen areas and white line markings. These properties of being black and white are intrinsic to the materials in the road… or so we thought.
Let's simplify this.
Consider we have one hundred white pebbles and one hundred black pebbles, and can mix them in any ratio to make a bag of one hundred pebbles.
If you only use the white pebbles, what is the probability of blindly picking a white pebble from the bag of pebbles?
100%
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If you have 100 white pebbles, you will always pick a white pebble
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Now if you make a bag of 50 white pebbles and 50 black pebbles, what is the probability of drawing a white pebble?
50%
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If you have 50 white pebbles and 50 black pebbles after you have drawn ALL the pebbles you will have 50 white pebbles and 50 black pebbles i.e. 50% is white
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Now if we have a bag of 75 white pebbles and 25 black pebbles, what is the probability of drawing a white pebble?
75%
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If you have 75 white pebbles and 25 black pebbles after you have drawn ALL the pebbles you will have 75 white pebbles and 25 black pebbles i.e. 75% is white
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Well the Nobel laureates found that probability to be nearly 85%
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That means after they drew ALL the pebbles they found 85 white pebbles and 15 black pebbles i.e. 85% is white
That is impossible.
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How could that be?
It must be because some property that we assume about the pebbles is wrong. Specifically, the property of being black or white is not intrinsic to the pebbles. The pebbles assume their property on measurement! This is the so-called collapse of the wavefunction.
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This answer is not clear. What means not intrinsic, assume and collapse of the wavefunction?
Pebbles can not assume something. Humans can assume something
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Entanglement is a sleight extension of this example. Now the probabilities are for observing a correlation between two measurements, like the probability that two white pebbles were drawn at different locations. In classical theory, such correlation probabilities are just an extension of the pebble example that behaves in exactly the same way.
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The example with the white and black pebbles has nothing to do with correlation and entanglement
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However, entanglement is a superposition of correlations that collapses into a specific correlation on measurement. Even if the two particles are widely separated, their properties are still connected by entanglement. This changes how the probabilities are calculated, such that the intuition gained from the pebbles doesn't work.
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Two pebbles and two elementary particles are physical completely different.
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Ultimately, this means our underlying reality is not one of intrinsic properties local to each particle.
That might sound weird, but that is why they awarded a Nobel prize for this work.
The bottom line is that quantum entanglement explains the 85% result, where classical thinking tells us it should be 75%.
Therefore, we have to reject the classical model of reality.
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The problem of explaining the result of drawing 85 white and 15 black, while you start with 75 white and 25 black is not clear. It sounds like magic.
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