The most fascinating questions are often the hardest to answer. How did the universe begin? How did life evolve? What is the nature of consciousness? These questions inspired our special package on “Impossible Questions,” which explores mysteries that are not just unsolved but potentially unsolvable.
Such questions are also the driving force behind the Vox podcast Unexplainable, which delves into scientific unknowns large and small, from the nature of dark matter to the science of human cells. The show, which debuted more than five years ago, also premiered as a video podcast on Netflix this summer. Over the years it has investigated mysteries such as whether plants can see, why humans cry, and what silence sounds like.
Scientific American spoke to Unexplainable host Noam Hassenfeld about dangerous unanswered questions, why bicycles are mysterious, and just how much we still don’t know about the universe.
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An edited transcript of the interview follows.
What’s the main idea behind the podcast?
Our show launched in early 2021, when the pandemic was going pretty intensely. There were lots of debates about how science works and how science should work. Something we really wanted to do was be honest that science is made by fallible scientists who have lives and make mistakes and are trying their best. And the most important thing is to be transparent about your mistakes and be open about what you don’t know.
There are some really big questions where we might not be close to answers. How big is the universe? How did life start? What’s the point of it all? At the fundamental level, they are all trying to make sense of our existence.
But I don’t think you need to get to the huge cosmic existential questions to have really juicy, unanswered ones. I’ve found that our audience really appreciates finding out things that they don’t know. Like, we don’t know how bicycles work. This is one of my favorite ones.
Wait, we don’t understand how bicycles work?
Yeah. This gets a little bit technical. It’s a question of which physical theory actually explains how bicycles stay up. At a fundamental level, I think there’s no very easy, simple way to explain why they do.
Wow! And that’s a pretty different kind of unanswerable question than, for instance, how the universe began.
It’s easy to assume that an unexplainable question is existential or cosmic. But we also do a lot of these really prosaic mysteries. So, why do we cry? Or should yogurt be its own state of matter? Or, you know, one of my favorites was an episode about the fact that some people can’t burp. These basic questions are unexplainable just as much as the cosmic, where-did-we-come-from questions. Understanding exactly why these questions are unanswered lets us figure out exactly what we still need to figure out, and it also just helps me stop taking the everyday world for granted.
“It’s very easy to go throughout your day and not confront that basic fact that almost everything everywhere is unknown.” —Noam Hassenfeld, Podcast Host
In the course of looking into these questions, have you come across a scientific mystery that seems to be not just currently unexplainable but unanswerable in theory?
I want to say, “Never say never,” because as I’m sure you know, many questions were once thought to be unsolvable, and then we figured them out, and we found ways to answer new questions we never even thought we would have.
But one that comes to mind is an episode we did on the question of whether the entire observable universe is inside a black hole. Is the universe just a black hole that is inside another universe that’s inside a black hole, that’s all black holes all the way down? At a certain level, that question is kind of unanswerable because you can’t get outside the black hole. The scientist I talked to suggested building a particle accelerator that would go around the moon. So it’s one of those things where maybe it’s possible to answer it, if we did the most ridiculous thing imaginable.
Are there some questions that should stay unexplained because trying to answer them would be too dangerous? The classic example might be the work that led to the atomic bomb. Should we have left those questions unanswered?
That’s really tough. I think there are questions where finding the answer can be dangerous, like with the atomic bomb, although that also gave us carbon-free energy. And then there are also questions that maybe we can solve only if we don’t do our research ethically. There are things that we’ve learned in the past through extremely unethical means. Someone once wrote into a Vox advice column asking, in the course of IVF, should I do everything I can to select the embryo that will have the least chance of disease? And then how far should I go? Should I select height and gender and eye color? You can see how it really spirals. I think having the impulse to solve things perfectly can both be impossible to meet and maybe lead you to a somewhat dangerous place.
Have you ever felt surprised about just how much we don’t know?
I still remember an episode we did talking to researchers about the idea of whether there might have been a technological species before humans, like millions of years ago. We think we have this full picture of the past—we have all these fossils; we know what was going on. But in fact, we’ve barely found anything. You know, we’ve mapped less than one third of the ocean floor. We don’t really know how smell works. Everything is just way more complicated than it seems. Ninety-five percent of the universe is made up of dark matter and dark energy, so we barely understand the vast majority of everything.
You don’t realize that what we know is like this little candle in the darkness. And when you’re right next to it, it can feel like a lot. But then you zoom out, and you realize that we just don’t really know that much. It’s very easy to go throughout your day and not confront that basic fact that almost everything everywhere is unknown.
Does that ever feel discouraging?
I don’t know. On the one hand, it makes me feel that much more grateful for what we actually have discovered. How we’ve been able to slowly build this enormous body of knowledge in the face of all the unknowns. It definitely makes me not take that for granted. And I get excited about how much more there is to understand. I know that when I die, we are still going to understand basically nothing that’s going on, but we are going to understand more than we do now. And there’s a lot of room for everyone who comes afterward to figure more stuff out.
When we started this show, we were like, are we going to run out of unexplainable things? And then very quickly we realized, definitely not. It kind of puts the magic back in the world a little bit. It makes you realize that this world is ridiculously complicated and that so many people are trying so hard to understand it. We’ve gotten so, so far, right? We have increased the mountain of knowledge to an absurd extent. And we still have so far to go.