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This is Part 3 of the XL Series on UNITY.
In my mind, the most earth-shattering experiments in the history of science were performed by physicists studying quantum mechanics in the 20th century. These experiments are usually referred to as “double slit experiments.”
What is quantum mechanics?
Quantum mechanics is essentially the study of the totally bizarre way in which matter, energy, and perhaps even forces like gravity operate at the micro-level.
It’s “bizarre” because the way stuff works down there is essentially the opposite way stuff works up here, where we can see, hear, smell, taste, and feel the things we’re looking at.
Why should you care about what you can’t see, hear, smell, taste or feel?
Understanding the basic principles of quantum mechanics can open our eyes to a whole new way of experiencing how much more interconnected and unified our universe is than we could have possibly imagined.
The last century of science has established quantum mechanics as “the most rigorously tested theory” of how reality works, despite the fact — and because of the fact that it flies in the face of common sense. Many modern technologies, including flash drives, GPS, LCD screens, and MRIs depend on some of the strangest features of quantum mechanics being accurate.
When something is strange but true, it means we need to rethink the way we think about the world.
Rosh (ראש) Hashana, literally the “Head of the Year,” begins this Friday night at sunset. It’s called the “Head” and not merely “the beginning,” because the idea is to hit refresh on our mindset.
Let’s see how some of the principles that emerge from the quantum revolution can revolutionize our mindsets and our lives for the better.
In 2004, a really bad movie (which you do not need to watch) came out, called “What the Bleep Do We Know.”
It’s a bad movie because a) it’s just bad, and b) because it seamlessly mixes real science with woo-woo, new age, quack ideas.
This said, the movie’s animation of the double slit experiment is really easy to follow, and helpful for grasping the experiments’ contributions to our understanding of the universe. I’m going to explain it in writing below, but if you want to watch the 5-minute video first, definitely go for it, and keep reading afterwards to make sure you got the main ideas and how they can change your life.
Let’s go through it step by step.
Light is a wave, right?
It certainly is. We can prove that light is a wave because it acts like a wave.
How exactly do waves act?
Good question. One of the unique features of waves is that waves that cross paths with each other interfere with one another.
What does this mean?
Ok, so every wave has a crest (the bump that surfers surf on), and a trough (the hollow at the bottom of the crest that surfers fall into when they wipe out). If the crest of one wave crosses paths with the trough of another wave of equal size, they’ll appear to temporarily cancel each other out, and then keep moving in opposite directions on the other side. If, however, the crest of one wave meets the crest of another wave, they add up to become a super-crest that is twice as big as either of the two waves, before they continue along their merry ways at their original smaller size. The same, but opposite is true with two troughs that coincide: a trough + a trough = super-trough.
Here’s another animation for you to see wave interference in action:
Colorado State University College of Natural Science’s (CNS) Little Shop of Physics on YouTube
Now, let’s say you have two sets of circular waves — two points of origin of ripples on a pond — interacting with one another. What you would see is a pretty beautiful pattern of those interferences. In some places you would have crests bumping into crests and becoming super-crests, in other places, crests bumping into troughs and therefore flatting each other out, and yet in others, troughs crossing with troughs and dipping down into super-troughs:
Now, imagine you set up a rock barrier near the coast with two gaps in it, and were to watch what happens to the waves that collide into it. What you would see are two new series of circular waves that originate from those two gaps.
As those new circular waves begin to intersect, they would interact by interfering with one another in this same way:
If you look carefully at the right side of the animation, you would see that all along the “coast,” you’d see this oscillating pattern of crest, trough, crest, trough, crest, trough, which results from the interference of those waves.
Now the question is: Does light do this too? Does light act like other waves?
Yes, it absolutely does. You can set up a barrier with two slits in it and shine light on the other side and literally see what happens.
Thomas Young did just this, way back in 1801. The “ripple effects” of his discovery are still reverberating today. This is the pattern he saw on the other side — precisely what we would expect to see from waves.
I can’t see you, reader, but I know you don’t look shocked yet.
Ok, stay with me here. Shock value guaranteed for those with patience.
Although light clearly performs like a wave since only waves produce this pattern, light can also be reduced into particles.
Um…what’s a particle?
By “particle” of light, we mean a discrete unit of light.
Walls are made of bricks. 6-packs are made of cans. Matter is made of molecules.
Light is made of photons, and you can actually shoot one photon at a time at our two slits.
What’s mind-blowing is that even when you fire one photon at a time, without giving the photons a chance to interact with any other photons, you still get the same interference pattern.
*Give me another minute. If your mind is not blown by the time I’m done, I’m either doing a bad job of explaining it, or you’re multitasking.
Our intuitions tell us, based on the world we experience everyday, that if you shoot one thousand bullets — one at a time — at a barrier with two openings in it — most wouldn’t make it through, some would go through the left opening, and some would go through the right opening. This would produce a pattern on the other side that would look something like this:
You might be thinking, “That’s for bullets, but photons are special. They can act like particles and waves.” Perhaps you vaguely remember this from high school science or premed in college. Maybe if we shoot a whole lot of photons at once they would interact like waves!
Ok, so to test your theory, let’s do the opposite and shoot one photon at a time. This way, no photon could interact or interfere with any other photon. By the time the next one is shot, the first one already hit the wall.
And yet, even if you fire off one photon a day at the double slit, you would still get this pattern:
This means that the photons appear to be interfering with one another like waves, even when they’re fired one-by-one like particles.
In case you think that this is a unique feature of light, this experiment was done in the 1920s with electrons, and later with relatively large multi-atom carbon molecules. The results were the same. They all demonstrated wave behavior — even when fired one-by-one. They continued to interfere like waves.
There is no coherent explanation whatsoever for this phenomena using science that existed before the 20th century.
Here is the trippy but true explanation of quantum mechanics:
On the micro-level, these particles can only be understood as traveling in all possible paths at once. In the quantum world, all possibilities are equally real. The particles, fired one by one, can be therefore understood to be interacting and interfering with the “waveform” of their own possibilities. It’s as if every photon fired is going through the left slit, the right slit, both slits and no slits at the same time, which ends up presenting like a wave with the alternating light-dark pattern characteristic of waves (called a “diffraction pattern”).
If it’s still not hitting you, please stay with me for one more step, and then we’ll take stock of what we’ve learned along the way.
Let’s say you were to set up a sensor next to each slit to detect which slit each photon is going through. Keep in mind that quantum mechanics postulates that in order to get a diffraction pattern, particles must do that wacky thing that they conceptually travel through all paths at once. This twist to the double slit experiment is trying to “catch” quantum mechanics as it does its “magic trick,” as if to say, “Aha! I saw you go through this slit! I know now that you’re a particle — you can’t interfere with any wave now!”
In principle, this should in no way affect the particle just like a security camera doesn’t make a thief steal — it just catches the thief in the act.
Here’s the thing though…
As soon as you set up a system to detect which slit the particle does through, the particle stops behaving like a wave, and starts behaving like a particle.
How could we know? Because the pattern on the other side immediately reverts to this:
The same pattern we would expect from bullets. Not waves.
It turns out that in the wild world of quantum mechanics, you see what you’re looking for. Not merely psychologically — physically as well.
What might this all mean??? And what does it have to do with me and my life, Judaism, and Rosh Hashana?!
Until quantum mechanics, the world was understood through classical mechanics, also known as Newtonian mechanics, named for Sir Isaac Newton, the father of modern science. In classical mechanics, the universe, and everything in it is a cause-and-effect machine. A wheel spins, which turns a gear, which rotates a shaft, which turns another wheel, which spins a cog, that spins another cog, etc. etc…
In a world like this, everything in the past and present is explainable, and everything in the future is theoretically predictable. This would have to include human behavior, since humans are just cogs in the machine like everything else. In such a world, from a scientific point of view, there would be no room whatsoever for free will. How could there be? Every action is a reaction to some other action all the way back to the beginning of time. Practically speaking, in this world, if someone would “make me angry” I’d have every right to be angry and bite the next person’s head off, since I’m just reacting to my buttons being pushed. Don’t blame me. Blame the guy who ticked me off.
Quantum mechanics throws a quantum wrench of uncertainty into the Newtonian machine.
On some fundamental level, there is a pervasive uncertainty and inexplicability throughout the entire universe. There is no way to know how any given particle is going to act. We can only see the overall shape of the wave of how many particles have behaved in concert.
This uncertainty is of most significance to the most complex piece of matter in the cosmos: the human brain.
The human brain is not merely a wrinkled lump of grey matter. It is comprised of nearly a hundred billion neurons that communicate using electrons that are subject to quantum uncertainty. They are also interconnected through a hundred trillion synapses that use neurotransmitters molecules that are also subject to quantum uncertainty.
The brain doesn’t look like the predetermined inside of a clock. The brain is brimming with possibilities.
As we approach Rosh Hashana, that days that define our coming year, the first thing we need to know and believe is that our lives are not machines.
Machines are doomed to run their course, while we as human beings are destined to author our own lives.
We can make choices that can change the course of our own futures and the futures of all those around us.
Quantum mechanics teaches us to see all the possibilities before us as equally real and interconnected with one another.
What, then, causes the possibilities in our futures to “collapse” into a single present reality?
The way we see our lives, and what we are looking for.
Just like if you’re looking for a particle you’ll see a particle, if you’re looking to see a certain outcome, you will prime your brain to see it. More than this, you may even somehow cause it to happen.
Free will starts in the in the mind. The mind starts in the mind’s eye. The world reacts to what our mind’s eye is looking for.
It is for this reason that we have the time honored tradition of holding up mundane fruits and vegetables on the nights of Rosh Hashana and seeing in them blessings for the future.
We’re training our minds to see the good in order to enable the good to come to be.
Everything in God’s world is interconnected.
Everything is ultimately One.
Even what we see is causally connected to what we’re looking for.
Let’s make sure to look for the good.
Shana Tova uMetuka!
Have a good and sweet year!