All models are wrong, but some are useful.

If you ever read about quantum mechanics (QM), it is very likely that you felt confused or just dumb. After all, QM are counterintuitive or so we are told by most experts in the field, including science communicators. “If you feel confused,” they often say, “you are on the right path.” However, I think the model is counterintuitive mainly because, until very recently, scientists could not phantom the idea that particles are so fast that they go back in time. Recent experimental data shows, however, that light is sometimes “faster than light.”

When we allow ourselves to explore the idea of time as something particles can transit in both directions, QM suddenly becomes very easy to explain, at least as a model. I am sharing a toolkit so you can explain to others how our limited perception of time actually explains some defining phenomena of QM.

Flatland

Flatland is an incredibly useful resource to add more complexity to our reality, particularly if you are explaining this in a bar or a library, which is why Carl Sagan made use of it back in the day. Once the world is flat, we will add quantum complexity to it.

To create flatland, you will need to get rid of one of our spatial dimensions and be left with a plane. Then, you will add two-dimensional people to it. I often use an object people are familiar with: a fish thank. If you place flatland right on the water surface, the fish tank will provide a clear separation of layers and will allow others to easily understand what happens in the surrounding environment.

Time works live gravity

We intuitively understand time moves only in one direction. In a way, this is very similar to the effect gravity has in our world. Most things fall down, and in flatland things always go from the top to the bottom. Our gravity is their time. An advantage of this model is that we can see time as our regular third dimension (up and down), and we understand how things can indeed move up and down without it being “counterintuitive.” We also know that things do interact in this third dimension, despite whether they interact with flatland or not.

Explain what object “falling in time” look like in flatland and the limits of perception

Flatlanders will not always perceive the interaction in the third dimension, yet that does mean it does not happen above or below flatland. However, more critical is that flatlanders cannot distinguish between objects falling down or going up because to them the phenomenon looks exactly the same. They can only see what crosses their plane while it crosses it.

If you have them around, grab a glass of water and any object and help it cross the surface, explaining what it would look like in a plane. First move it downwards, then in the other direction. Explain how from a flatlander perspective, both directions would look the same. All objects “behave” like this and flatlanders have a whole science about it, akin to our own general relativity.

Now, for a change, tell your friend to picture a bubble floating, filmed against a white wall. We use bubbles because most people played with them as kids and they can understand their unpredictability and fragility. This nature mirrors the “randomness” and ephemerality of small particles like photons and electrons. Ask them if they could tell, just by looking at the it, whether the video is being played normally or backwards. It is likely that they cannot, this is the same problem flatlanders have when detecting whether objects are falling or going up. However, they assume all objects are simply falling into the water. Similarly, we assume nothing can go back in time. However,

Use bubbles as an “exception” to gravity

Bubbles are special because they bounce in water (we added a bit of syrup and glycerin to make sure it happens). In other words, they go in both directions while in the plane, and they do so quickly. As I said before, bubbles are the quantum particles of flatland. More importantly, recent experimental data strongly suggests that photons indeed bounce in time, they are the shaky bubbles of our timeline. Why are bubbles so baffling to flatlanders? They are completely unpredictable! A soap bubble can:

1. Stay the same diameter (because it is on the surface), or
2. Get bigger and smaller (because it is “bouncing” ), or
3. Change between the two configurations above (because the air disturbed it, for example), or 
4. Disappear (because it popped or was lifted entirely).

Explain the double slit experiment analogy with bubbles

In our world, light behaves like a wave if we do not disturb it, but when we try to measure it, it behaves like a particle. Something similar happens with bubbles. If they measure them indirectly, let’s say by taking consecutive pictures of the plane while the bubble is there, they will see changes in diameter over time that do not look predictable as every other object. If you graph these changes in diameter, you will get a distribution of probability (just like the interference pattern of light waves). We can also get more creative and say they can somehow measure the share of their own plane, literally seeing the waves the bubble would create.

From our view, we can tell how big a bubble is, however, flat scientists can only think of these diameters as a wave of probability. A bubble can be big or small and flatlanders cannot really know about this because they do not know how “deep” the bubble is. They also know this wave-like nature does not last long, as bubbles tend to do something if they are actively bouncing. This is how they generate random numbers.

When flat scientists try to measure the bubble directly, that stops its weird nature as the bubble suddenly behaves like a 2D object. In reality, they popped the bubble and they are left with the rim, which to them is not really different from the bubble. We do something similar when we detect photons, we physically interact with them. However, indirect observation does not alter their “natural” state. You can think of their measuring devices as a needle.

Optional: use mosquitos to explain quantum entanglement

You can use surface tension to explain how mosquitoes can rest on the water. A flatlander would see each foot as an independent object and think of them as such. However, when they disturb one of the feet, all of them are lifted at once. They think of them as “entangled” objects. Truth is, these objects are indeed connected in the third dimension, the one flatlanders cannot perceive. Given entanglement is about the position of the particle, maybe you can say different mosquitos “open” their legs in different angles, and by measuring one foot relative to their two axes, they can know how the other feet “will move” / “moved”. 

Summary

• We are flatlanders. We routinely perceive four dimensions (three spatial and one temporal) under the assumption that time is unidirectional, because that is the preferred direction to the macroscopic eye. However, time going constantly forward is more of a human perception than a definitive reality. Both general relativity and quantum mechanics allow for time loops under some conditions or models.
• Scientists often describe particles as waves of probability. One possible explanation is that particles are constantly bouncing through time—moving both forward and backward. Because of this, they appear in our present more than once, resulting in what we call “superposition.”
• The “collapse” of the wave function is the result of disallowing particles movement in a time-backward direction as they become “attached” to equipment that is “falling” in time.
• Entangled particles are partitioned in space but remain entangled in a past/future times, which is why the measurement triggers the same reaction in both particles independent of distance. This is very easy to understand when visualizing time as a vertical axis in flatland.