What is reality?
Updated: Dec 12, 2021
Dreamworlds are notoriously fickle. They exist solely in our minds, and thus aren’t grounded in any objective reality. In a very real sense, the act of observing something in a dream DOES change it because the dream and observer are one in the same. But what if the universe behaves in the same way? What if our mercurial dreams are really trying to reveal the deep, unsettling truth of reality? Do our observations create reality itself? Episode art by Nemi Fadda. Follow her on Instagram.
Last night I dreamed I was stuck in a bizarro world version of a place I once lived. As I tried to navigate the roads I once knew so well, they twisted and contorted like rything snakes. Buildings sawm and fused before me, melting into and then growing out of the landscape. I tried to consult my trusty iPhone for directions, but each time I said “Hey Siri,” the words came out as tongue-twisting nonsense. When I tried to type an address into the phone, the letters swirled into strange ciphers. The simple act of observing anything in this strange dreamworld changed it. Eventually I awoke, confused and bleary eyed, head aching from being whipped back into sharp reality.
Dreamworlds are notoriously fickle. They exist solely in our minds, and thus aren’t grounded in any objective reality. In a very real sense, the act of observing something in a dream DOES change it, because the dream and observer are one in the same. But what if the universe behaves in the same way? What if our mercurial dreams are really trying to reveal the deep, unsettling truth of reality? Do our observations create reality itself?
Study quantum physics for just a few minutes and it’s easy to delve into mind-bending cannabinoid metaphysics like that. An article published on MIT’s Technology Review site last week really jumped on the metaphysics trampoline with the title, “A quantum experiment suggests there’s no such thing as objective reality.”
The experiment itself is fascinating, but headlines like that are straight-up dangerous. There clearly is an objective reality for us at the human scale. Suggesting otherwise can lead to all kinds of harmful magical thinking. And it already has. Quantum weirdness has inspired irrational hucksterism since Niels Bohr, Werner Heisenberg, Erwin Schödinger, Albert Einstein, and of course Max Planck first started exploring it in the 20s and 30s. Today it fuels vast empires led by grifter gurus espousing bizarre beliefs supposedly backed-up by hard science. And it’s easy to see how. Let’s take a look at just a few of the weird things that seem to happen at the quantum level.
The double slit experiment is the most famous example of quantum weirdness. It really freaked everyone out, and sparked a famous debate between Niels Bohr and Einstein that lasted decades. Here’s how it works. Imagine a photon source—a kind of light bulb that emits photons. Put a board with two slits in it in front of that photon source. Shine that photon source and see what happens on the other side. You’d expect to see two bars of light, but instead you see a zebra pattern. This is a diffraction pattern, which happens when two waves interact. You can see this pattern form if you make two adjacent waves in a bathtub or your sink. Okay, cool, so it seems like light is a wave, right? But other experiments show that light behaves like a particle. So which is it, a wave or particle? Light is both simultaneously and what you see depends on the experiment you’re running. This is weird already, but things get weirder.
When you do the double-slit experiment with electrons, you get the same results. Okay, but electricity can get away with being unintuitive and magical. It’s lightning bolts and crackling Tesla coils and glowing light bulbs and it can kill you without a sound in an instant if you’re not careful. It wants to be both a particle and a wave? Go right ahead.
But you get the same diffraction pattern when you do the double-slit experiment with atoms and even molecules. That’s right, even large molecules like Buckminsterfullerene can behave like waves when they traverse the seeming mystical apparatus of two slits cut in a piece of cardboard.
You might see this and rightly think, “What the hell is going on?!” You’d probably add a camera (or some sort of measuring device) to watch what comes out the other side of the slits before it hits the screen. When you do, the diffraction pattern GOES AWAY. Instead, you see two distinct bars of light (or spots where the atoms hit the screen.) The light or electrons or atoms or molecules act like particles when you watch what they’re doing.
This would suggest that photons, electrons, or even atoms are neither particles nor waves until you observe them. Physicists call this a state of “superposition”—basically being undefinable—and it’s at the core of quantum physics. When you or an instrument observes the particles, they “collapse” into either a particle or a wave depending on how you measure them.
This state of superposition can be taken to the extreme. And Erwin Schrödinger’s famous thought experiment goes there. In 1935 he imagined a devilish experiment. Stick a cat in a box with a poison flask linked to a radioactive atom. If an instrument detects radioactivity, the flask breaks and the cat dies. Anyone outside of the box doesn’t know if the atom has decayed, or if the cat is alive or dead, until they open the box. You can say, then, that the cat is dead and alive at the same time until someone opens the box.
Schrödinger admitted this was a ridiculous thought experiment, but he used it to illustrate the concept of quantum superposition.
In 1961, physicist Eugene Wigner took Schrödinger’s cat experiment even further into crazyville. (This is the same Eugene Wigner who discovered Wigner energy, the cause of the Windscale nuclear disaster physicist John McCone and I discussed last episode, by the way.) Wigner imagined watching the Shcrödinger’s cat experiment from outside the lab. To Wigner, outside of the lab, the cat is both dead and alive in a state of superposition. In fact, the act of opening the box and taking a measurement is also in a state of superposition. Wigner can’t tell whether his friend in the lab has opened the box. Even if his friend has opened the box and found the cat alive, to Wigner the lab is in a state of superposition. This creates a paradox. To Wigner’s friend, the cat is alive. To Wigner, the cat is still dead and alive. The two are experiencing different realities.
When you’re dealing with cats and labs, this sounds ridiculous. There is no apparent paradox—Wigner simply doesn’t know what’s going on inside the lab. But things get wacky when you perform the experiment with photons.
Imagine a photon in a state of superposition. Nobody knows what properties the photon has until they measure it. A scientist in the lab performs the measurement. Outside the lab, another scientist can run an experiment that shows the photon is still in superposition. It seems the two scientist are experiencing different realities.
That’s what Massimiliano Proietti at Heriot-Watt University in Edinburgh and fellow researchers did. They used six entangled photons to perform Wigner’s experiment dozens of times with two different labs. Entanglement is another insanity of quantum physics. To briefly explain, it happens when two particles are either created at the same time, or interact in a way that they end up sharing physical properties. But these are quantum particles in a superposition state—like electrons that are neither waves nor particles simultaneously. When you separate those two particles and measure one of them, the other will collapse simultaneously. Einstein called this “spooky action at a distance” and it really stuck in his craw. The notion that the universe could be so seemingly magical made him very anxious. He thought that there must be something else going on that we simply aren’t aware of. But that’s another story.
Proietti’s experiment confirmed Wigner’s crazy results: Scientists apparently experienced different realities—some definitely seeing collapsed photons while others observed the photons in a superposition. Proietti says that this calls into question the objective nature of facts. What does that mean?
Well, an objective fact is a fact regardless of who knows it. Universal facts exist and observers can agree on them. This assumes that observers can make whatever observations they want. It also assumes that their choices do not influence the choices other observers make.
Proietti’s experiment calls these assumptions into question. At least on a quantum level.
Something bizarre is going on with the universe. Or the universe at quantum scales works in ways that are unintuitive to US. Because the world we interact with doesn’t work that way. Things exist and continue to exist even if we’re not there to observe them. If a tree falls in a forest and no one is around to hear it, it DOES make a sound.
This is all terribly confusing and frustrating, so I asked world-famous physicist Sean Carroll—on Twitter, because he’s too busy to chat. He quickly shot down the article’s click-baity headline, “A quantum experiment suggests there’s no such thing as objective reality.”
“This headline is very wrong; quantum mechanics is perfectly compatible with objective reality. Reality is modeled by a wave function, but we should have understood that for years now,” he wrote.
He went on to explain the experiment results in a more straightforward way:
“One observer has branched, so one version of them sees one result, the other sees the other. The other observer hasn’t branched, so they think the first observer is in a superposition. That’s all.”
Carroll is a proponent of the Many-worlds interpretation of quantum mechanics. It states that all possible alternate histories and futures are real, and that each is its own “world” or “universe.” Everything that could possibly have happened in our past, but did not, has occurred in the past of some other universe or universes.
So to Carroll, the second observer in Wigner or Proietti’s experiments just think the first observer is in a superposition, not that they actually are.
To be honest, I truly don’t know. The brightest minds in the known universe have been trying to come to grips with quantum physics for 100 years and they still aren’t sure what’s going on. I, as a podcaster of middling intelligence, can’t claim to know. Or even begin to know.
However I do know there is such a thing as objective reality on the human scale. If there weren’t, much of the technology we use wouldn’t work. If the constants governing the physical world morphed and changed with our observations, then our tech would behave like the iPhone in my dream. Its behaviour would be bizarre and unpredictable. Nothing would be repeatable or verifiable and science itself wouldn’t work. We wouldn’t be able to agree on anything and logic itself would break down. And yes, I am aware that this is a slippery slope argument. So it goes.
But that’s an important realization. While things on the quantum level fizz and pop into and out of existence, or change when they’re observed, or become spookily entangled, the things in our world don’t. The spooky action at a distance we see with two entangled quantum particles doesn’t make telepathy real, or give wishful thinking the power to directly change the universe. This kind of magical thinking may be fun, and it may motivate you to get moving in life, but it’s not real.
If we’re going to survive as a species we’ll need to abandon magical beliefs, even if quantum weirdness hints that there’s something mystical going on with the universe. We can’t wish away the effects of climate change, or hope that some deeper grand order of nature will prevent nuclear apocalypse. These are human problems and we need to face them head on.
But I digress. The point is: don’t let quantum weirdness lead you astray. I’ve been immersed in this world for about two weeks now and I feel like I never woke up from that bizarre dream. My mind has been adrift in a dense fog of confusion, dizzy and delusional from near lethal doses of probability equations and quantum wave function calculations. Well, not really. I can’t do any of that math. But still, this stuff is really difficult to grasp, even for people who do it for a living. We have a long way to go before we’ll be able to wrap our minds around what the results of these quantum experiments really mean. And humans, as we are now, may never be able to grasp the deep weirdness at the very base of reality. We may need to leave that up to our AI descendants.
Well that’s it for this episode. I really did do a ton of reading about quantum mechanics for this one, but I only scratched the surface. I didn’t even mention Robert Hooke, Christiaan Huygens and Leonhard Euler, the very early scientists who started thinking about this stuff way back in the 17th and 18th centuries. And Max Planck, who is considered the father of quantum mechanics. Or the quantum mechanics Avengers, who assembled for the fifth Solvay Conference back in 1927 to unravel the mysteries of the universe. Its members included Planck, Schrödinger, Einstein, Marie Curie, Niels Bohr, Werner Heisenberg, John von Neumann, Wolfgang Pauli, Louis de Broglie, Paul Dirac, Arthur Compton, and Max Born. Twenty-nine of the greatest scientists the world had ever seen gathered to scribble incomprehensible formulae on giant chalkboards, argue about quantum weirdness, and inspire a new generation of scientists.
If you want to learn more about quantum mechanics, check out the show PBS Spacetime, available on YouTube. The show covers a lot of what I discussed here, including the double slit experiment, quantum entanglement, quantum field theory, the many worlds interpretation, and more. Host and astrophysicist Matt O’Dowd explains the trickiest scientific concepts clearly and concisely, and producer Kornhaber Brown brings it all to life with stunning animations.
You should also check out the YouTube channel Answers with Joe. Joe breaks down complex scientific concepts into quick and amusing videos.
Oh, and definitely take a look at Sean Carroll’s upcoming book Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime due for release in September.
Finally, if you’re into solving science and math problems, go visit Brilliant.org. Brilliant offers online courses in everything from basic algebra to quantum computing. They also deliver daily math and science problems to tease your brain and help build a daily learning habit.
But maybe, just maybe the dream world is the real world and the waking world is the one we make up… Perhaps what we call our subconscious is able to see the universe and all its quantum weirdness. Our dreams are mercurial and flowing. In sleep reality swims and swirls before our eyes like particles in superposition. Could our dreams reveal the true nature of reality? Could our waking hours just be a distraction from that reality? Could the mind be the final frontier of science, could it hold the true secrets of the universe?
Woah… what was in that brownie man… I need to lie down.