Many world interpretations for building a powerful computer — What are we: Particle or Wave?

In my previous blog, we talked about some of the basic theoretical requirements to build a quantum computer. I would like to start introducing the mathematics behind its design in the upcoming blogs. I understand for this we need some background in quantum mechanics, so I will try to explain some of the concepts in a simplified manner.

In the last blog “the interference section”, I mentioned about the fundamental structure of the universe is like a wave-like form which is probably hard to imagine and with that reference, I gave an example of electromagnetic radio waves carrying information and us being a receiver who decodes it to create the reality in physical form. I would like to expand more on that statement and discuss in detail an experiment that can prove that statement.

An idea was conceived by a genius mind Thomas Young in 1803 which can prove the notion that we are made of either particles or wave-like or both, but due to a lack of experimental confirmation from the victorian era scientists, it was forgotten. It lay dormant for two centuries until Wheeler and Thibodeaux proposed an experiment that re-produced Young’s original idea with success. We can go through the experiment again below and understand the concept of why reality is different than we think.

Understanding Bullets and Waves Behaviour

Imagine that you have a wall with two narrow slits and a sandbox after it. A machine gun is set up right in front of the wall and since we have a machine gun and not something else, you might expect that we are going to shoot in the direction of this wall having two slits.

The gun is fired multiple rounds and we can see the bullets pass through the slits which will have equal chances to pass through. Those bullets which pass through the slits are going to reach the yellow sandbox and get stuck there.

After the experiment, we can retrieve the bullets from the sandbox and count them. When counting the bullets, we can draw a graph. The x-axis here corresponds to the position of the bullet in the box, it’s how far it went from the line of symmetry of the whole set. The y-axis will correspond to the number of bullets found in this position.

If we repeat the experiment with a single slit at a time, we see predictable behaviour which is pretty straightforward to understand

Now let's use something completely different, the screen with two slips is now going to be placed in the water. Instead of a machine gun, we are going to have some source of water waves and an oscillating bobber. which will oscillate with some frequency and produce waves. These waves will pass through the slits and will reach the detector.

To detect those final waves, we are going to place many smaller bobbers along the line parallel to the screen at some distance. These bobbers will swing due to the secondary waves and produce some work for us to measure. We probably remember from school that waves don’t transmit matter, but they do transmit energy.

We will start the experiment with only one slit open at a time and see the result which is again predictable.

The graph above shows the power produced by each bobber. The bobbers which are closer to the slit, produce more power, while those far away slit. It is absolutely normal since the energy of the wave is distributed along the whole wavefront. The power which we are measuring is also called the intensity of the wave. From physics, we know that the intensity of the wave is proportional to its squared amplitude.

Now, when we have the graphs of intensities with the left and the right slits being opened separately, can we predict the resulting graph for the two slits opened simultaneously? Below is the experiment result, when the waves pass through the slit and it collides with each after passing the slit forming another set of waves or cancelling each other. In the end, the intensity (power) of the wave is found all over the detector.

So that means the resulting graph of the wave intensity with two slits open is not equal to the sum of the graphs with the left and the right slits opened separately which is the case with the bullet are equal.

Understanding Fundamental Particle Behaviour

We have just seen with the above experiment gives us quite different results for bullets and waves. When we perform it with the particles, like bullets, the resulting graph with both slits opened is just the sum of the graphs with each slit opened separately. When they perform this experiment with the waves, there are no particles to count. Instead of the particles, we measure the characteristic of the wave called intensity. The resulting graph for this intensity with both slits opened is not at all the sum of the intensities with the slits opened separately.

We will now make use of the quantum particles like photons and electrons which are fundamental building blocks for an atom. We will continue with the setup, as we had with the bullets, but instead of a machine gun, we now have the source of photons, which can fire photons one by one. We have a special detector behind the slit which will detect the photons and we can count the hits by counting the number of spots formed on the detector.

At the start of the experiment, we will just fire the photon's particle and see the result in the detector at the end. This means that we are not observing the process of how the photons pass the slits and reach the detector. At the end of the experiment, we see a result something like we have observed in the above wave experiment using water.

This is strange, because we belive the photons are something like a bullet. In order to see why it behaves like waves, we have now placed a camera like an observer in front of the slit which will record the entire process to see how the photons are passed through the detector. We rerun the experiment and see the result at the end along with the recording. And the thing which is observed is pure bullet like behaviour which depicts the photons are like particles. There is no wave like character.

Repeating the experiment with electrons with and without a camera (an observer), we see these two different results.

What’s going on here? It’s as though the electrons or photons “know” whether you’re watching them or not. The very act of observing this setup — of asking “which slit did each electron pass through?” — changes the outcome of the experiment. If you measure which slit the quantum passes through, it behaves as though it passes through one and only one slit: it acts like a classical particle (like a bullet). If you don’t measure which slit the quantum passes through, it behaves as a wave, acting like it passed through both slits simultaneously and producing an interference pattern.

Are we at one place or everywhere?

Since we know we are made up of these fundamental particles, that means as a complex being we are unable to experience this wave nature which technically means being everywhere. We are always in a constant state of observation through various senses and that makes us solid physical beings and observe one event or moment at any point in time.

At this point, the whole problem gets very difficult to get your mind around. But don’t get too worried about this. As Richard Feynman, Nobel Laureate and the truly brilliant man said: “I think I can safely say that nobody understands quantum mechanics.” Most people working in this field just get used to the concept and get on with their lives, or become philosophers.

And as for reality?

I think Professor Feynman has the last word on that one, too: “ … the paradox is only a conflict between reality and your feeling of what reality ought to be.”

In the next few blogs, we will start going into more technical, look into some mathematics, learn how we can start building algorithms in the quantum computer and might as well do programming. That also means we will start running our code in the 5th dimension and use the true power of parallel computing.

See you in the next blogs ….

Also published in my tech quantum blog: https://www.tech-quantum.com/many-world-interpretations-for-building-a-powerful-computer-is-wave-the-reality/