Unexplainable - What happened before the big bang?

Episode Date: September 16, 2026

It's a question that seems impossible to grapple with, but scientists won't take no for an answer. In this collaboration with Scientific American, we take on the big bang and a whole bunch of seemingly impossible questions. Guests: Rachel Feltman, host of the Science Quickly podcast; Sarah Scoles, senior contributor at Scientific American For show transcripts, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unxtranscripts⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠For more, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unexplainable⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠And please email us! ⁠⁠⁠[e-mail]⁠⁠⁠We read every email.Support Unexplainable (and get ad-free episodes) by becoming a Vox Member today: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/members⁠⁠⁠⁠⁠⁠⁠⁠Thank you! Learn more about your ad choices. Visit podcastchoices.com/adchoices

New from Nespresso. Blend wellness into your coffee routine with the coffee plus range, infused with functional benefits. Choose the coffee you love with added B vitamins, like coffee plus B12 to help support immune function, and coffee plus B6 to keep your day moving. Or go with the flow and choose ginseng delight. Our new double espresso with ginseng extract. Whatever lies ahead, don't change your morning. Let your morning change you.

Discover coffee plus on nispresso.com. Hear that? It's your money calling. It wants a promotion. Elevate your savings with the Scotia high-interest savings account. Always earn high regular interest rates that grow the more you save and invest. Conditions apply. Visit scotiabank.com slash h-I-SA to learn more. Scotia Bank. You're richer than you think.

Rachel Feltman. Hi. Welcome to the show. Thank you. So you host Scientific Americans podcast, Science Quickly. Yeah. And I wanted to talk to you because Scientific American has this special issue out called Impossible Questions. It's out in print.

It's out online as of yesterday. And when I found out about it, it was like someone put the bat signal up in the sky. Like someone somewhere is talking about what scientists don't know. And I wanted to talk to you all about it. But before we get into it, for anyone who isn't familiar with Scientific American, Can you just set the stage a little bit? Yeah. So, Scientific American is the oldest continuously published magazine in the United States.

Okay. Yeah, yeah, we're old, but we've got a lot of life left in us. The magazine was founded in 1845. Wow. Yeah. Okay. We have a lot of people say, you know, like my grandfather had a subscription to Scientific American, and then my dad did, and now I do, and we love it.

Yeah, one of the last people, I interviewed for the show, Hank Green. I was asking him how he got into science in the first place. And the first thing he said was when I was a kid, my parents got me a subscription to Scientific American. Yeah, we love to hear that. All right. So we're planning to do two episodes on this Scientific American issue. Yeah.

We're doing one today, one on Monday. And I wanted to kick it off with something we haven't really done too much on our show. Because we talk about unanswered questions all the time. But we don't always zoom out and talk about why they're all unanswered. And the impossible questions issue, it inspired me to make a sort of, I don't know, taxonomy of unanswered questions. It's definitely not exhaustive. I'm sure some questions aren't going to fit in perfectly here. But I came up with four big categories that helped me wrap my head around why questions are unanswered. So I figured.

I could run them by you. Yeah. That sounds good? That sounds great. Okay, so the first kind of bucket I came up with is really the clearest, which are the questions that we're trying to answer but just need more research. Like, the research is hard and we're doing it and we're not there yet. So we still kind of fundamentally don't know exactly why things smell a certain way. Yeah.

And, you know, I think about a question we talk about a lot, which is like, do aliens exist? And like we're working on it. Like we're looking and we just need more time. Yeah. You know, I love that bucket because I think a lot of people sort of assume all of the questions that scientists would bother working on are in that bucket, which of course is not the case. But one that comes to mind is how acetaminophen works. Yeah.

So Tylenol is a big one. but then in a very different category of a very common drug, like most, if not all, antidepressants. Yeah. There is this thing where there are drugs that we know work well enough. We use them quite often. They provide immense benefit to many people, but we don't actually know definitively what the mechanism is by which they are working,

which is pretty mind-blowing and does seem like a question that, surely must be answerable if we just get more information. Intuitively, you might think, okay, unanswered questions are unanswered because they're so big or they're so far away. And even things that we're so physically close to are still hard to answer. Like, it's not just, is there an alien out there? Or is there, you know, a mysterious planet in the furthest reaches of our solar system? It's like, what's up with our nose? Totally. Yeah, and not to like climb on my soapbox too much, but, you know, a big category of those and answered questions are ones that, you know, mainstream science has simply not dedicated

resources to. So reproductive health and, you know, endometriosis, things that are very present, very close, and we have this big knowledge gap, which thankfully, you know, we are starting to see get resolved. But yeah, you know, I think. think there are so many questions like that where it probably isn't that the question is so insurmountable, but someone does have to put the resources toward trying to answer it, which has not always been the case. Okay, so that is actually a perfect segue into my next bucket. Oh, good.

In a slightly different way, but the next category I was thinking of, which is easy to miss sometimes, is questions that we really could be answering, but we might not want to be. And there might actually be a good reason why we wouldn't want to. Like, these are sort of moral, ethical, should questions where the best way to answer it would be to test some dangerous substance on people or to withhold something from them. But one thing that occurs to me in this realm, and this is why I bring this up after the endometriosis thing, is I think a lot about the fact that we know so little about what medications are actually safe for people who are pregnant. Absolutely, yes.

And it might be hard to design an experiment for that because it would be very difficult to say, hey, you're pregnant, take this pill, we don't know how it's going to react. Yeah, no, this is something that I've been thinking about a lot lately because I had my first kid not long ago. And it's such a problem, but one that, like you said, there isn't a great solution for, at least in the current paradigm for like our best way of studying drugs. And drug companies got scared off of testing stuff on people, like people who might just even have a remote possibility of being pregnant. Sure, yeah. And what we've ended up with is a world where we actually just don't know a lot of impacts of medication in general on women.

Yeah, no, I definitely think that's true. And it's so thorny to even talk about. You know, on the one hand, I think anybody with any kind of moral compass can see that the way that a lot of science. was conducted in the 19th and a lot of the 20th century was not good in that respect that, you know, a lot of unethical decisions were made. But, you know, I think it's good that that scared us, but we aren't great at figuring out the nuance there. And it just, it leads to this place where it's like, we're somehow okay with the fact that we just don't know how so many of these drugs work on women? Yeah, exactly. It's very strange. It is very strange. So the next

group of questions I've been thinking about is the questions we didn't know were unanswered because we didn't even know we could ask them. Yeah. Like we didn't have the tech or we didn't have the observation or we didn't have the right theory to even get to a place where we could ask that question. So, you know, an example I think of is how microscopes let us ask questions about microbes. And then that let us ask questions about the microbiome. And then we get to a place where we can ask questions about the impact of the microbiome on our mental health. You know, a couple hundred years ago, you couldn't sit around and be like, what is the impact of all the little bacteria in our gut on our mental health? Like, that wouldn't mean anything.

Yeah, you know, one that I think works well for this bucket is the question of what the longest-lived animal is. Is this the Greenland shark? So, yeah, for listeners who don't know, and I think it was 2016, researchers looked at proteins from the eye lens of a bunch of Greenland sharks. Almost like an organic living carbon footprint in the back of their eye and do an organic version of carbon. dating like we would do with some ancient artifact. Then they found an average lifespan of 272 years. The largest shark that they looked at was 392 years old plus or minus another like 100 or so years.

It's like a shark that like overlapped with Shakespeare or something. Yeah, yeah. And so that's the longest lived vertebrate. The oldest invertebrate is a clam nicknamed Ming because she was born in 1499 during the Ming dynasty. Clam shells are deposited in layers like tree rings. So if you count the layers, you can figure out how old the clam is. And they didn't discover Ming's age until they returned to the lab and examined its shell under a microscope. It's not that we never would have asked, you know, how old is the oldest thing, but it was just like a philosophical question. Yeah, we wouldn't have had a way to actually get an answer.

Yeah, except, you know, maybe like looking at historical records that are like, wow, my family's been watching this one clam for centuries and it's cursed with life. So yeah, I like how that one would have absolutely like boggled the mind of scientists. So that's pretty cool. Okay, the last bucket might be the biggest bucket. And this is more of the classic big unanswered questions that people might think of when you say, oh, what are the biggest unanswered questions in science? The way I'm thinking about this bucket is like there's some insurmountable barrier or at least seemingly insurmountable barrier between us and the answer, like, how did life start or what happened before the Big Bang? Something that seems like we could never get past. Yeah, there are so many questions

like this. And there are several, in fact, in this print issue of Scientific American. These are sometimes the most fun. Yeah, yeah. Well, so what came up for the Big Bang is a really fun one, because the word before is no longer accurate, actually, because the Big Bang wasn't just the start of space. It was the start of space type. So it was also the start of time. So what does it mean for something to have happened before the Big Bang? At the same time, though,

you never know what kind of new tech or new theory is going to come around and give us a way in, like with the microscope and the microbiome. And I don't know, sometimes just kind of wrestling with these questions, I feel like it could take us to some pretty fun places. So I actually want to try that with the Big Bang question. Even though it seems totally impossible, there are some very interesting theories of what could have happened before the Big Bang. And we're going to get into it after the break. Yeah. Support for Unexplainable comes from Granola.

We have all been in meetings that end with let's circle back, and then nobody actually circles back, and instead things get lost, everyone heads in different directions, and somehow you end up in yet another meeting. But Granola helps keep everyone on track, so meetings actually lead to something productive. Granola is an AI-powered notepad that makes your meeting notes useful. It captures what happens in your meetings

and turns it into clean, structured notes with decisions and action items pulled out and made easy to find. And Granola aims to make it easy for you by fitting seamlessly into the way you already work. So no complicated setup, no configuration, no added friction. Its goal is to turn messy meeting conversations into clear, organized notes that are easy to search and reference and act on, even weeks later. You can try it, totally free. Head to granola.a.ai slash unexplainable. That's granola.coma.ai slash unexplainable.

to get your time back. Go to granola.a.com slash unexplainable and try it on your next call. When you're a mid-sized business, you need every competitive advantage you can get. Like an AI solution that works for you, not against you. SAP Grow is built with AI embedded at its core, working across every system. And it's ready to go from day one so you can hit the ground running. Bring it with SAP Grow. AI Cloud ERP for any size business.

New from Nespresso. Blend wellness into your coffee routine with a coffee plus range, infused with functional benefits. Choose the coffee you love with added B vitamins, like coffee plus B12 to help support immune function, and coffee plus B6 to keep your day moving. Or go with the flow and choose ginseng delight. Our new double espresso with ginseng extract. Whatever lies ahead, don't change your morning. Let your morning change you.

Discover coffee plus on nispresso.com. start with who you are and what you do? My name is Sarah Schools, and I am a senior contributor at Scientific American. All right, so you wrote this great piece for the Scientific American Impossible Questions series, and it's all about what happened before the Big Bang. Yeah. How did you even start thinking about this question? Yeah, I mean, if we go all the way back to when I was a kid, I grew up super religious,

but I was always an annoying kid who was like, well, if God created the universe, who created God? And then what came before that? And then when I went to college and became not religious anymore, it turned out I was still interested in the same questions. The big impossible questions? Exactly. Still annoying. And my roommate and I would sit in our room and be like, well, if space is expanding, what is it expanding into? And if the Big Bang was the beginning, what happened before that?

And now I'm a science journalist, and I thought, you know, there's probably some people thinking about this question professionally, and I could just bother them instead of my Sunday school teachers like I used to. Oh, my God. This is such a great entrance into this question. I guess how is it even possible that someone could try to answer a question like this? Isn't it by definition impossible? Yeah, I think, I mean, it depends on how you think about it. The Big Bang is definitely a hard boundary. We can't even like see or gather. data from the time right after it, let alone see right back to it. And so if you can't even see there, you definitely can't see before there. So I think the way that scientists think about it is maybe there are some imprints left on the universe that we can see that provide some clues for what happened before. Okay. So what did the scientists you talked to tell you about this question? Did they have theories for what might have happened before the Big Bang? Yeah. So the first theory is

called the no boundary proposal, which is based on this idea that if you look at the modern universe and you say, how did it get like this? You can rewind back and say like what initial conditions would I have needed to go from the past to the present. And then you can kind of go backwards and backwards and backwards forever, but that doesn't make sense because as far as we know, the Big Bang created time. And so there cannot be before the Big Bang because there was no time before the Big Bang. So if this isn't making sense, that's how it's supposed to be. Because this this proposal came from the fact that like, if you do that, it doesn't make sense. Like, it sounds like gobbledy cook. So in the 80s, Stephen Hawking and another physicist named James

Hartle were like, this doesn't make sense. So let's try to think about it without the universe having a beginning. Let's let go of time, our concept of time in that way. And let's think of the universe as a four-dimensional space time. sphere. The way that scientists told me to think about it because like that's not something our brains don't encounter four-dimensional space-time spheres. Not often. Not often. So they said think of it like the globe. Like if the universe in space and time is a globe, then the beginning of the universe, the Big Bang, is the North Pole. And so asking what happened before the Big Bang is kind of like asking what is north of the North Pole? Like, nothing. Oh, interesting. That's almost like a Zen

koan or something. Yes, exactly. So that's not an answer to the question. That's just sort of like rejecting the question? Yeah, sort of. Yeah, it's a very fancy way of rejecting the question. Okay. Are there any ideas of what happened before the Big Bang that are not kind of rejecting it, that are actually taking it seriously? Yeah, one that I found interesting is this one called the big bounce. The big bounce. The big bounce. Yeah. So as far as scientists know, as far as we can see right now, you know, the universe is

expanding at an accelerating rate. But in this cyclic universe theory, there's the idea that at some point it starts contracting. And this is not the big crunch? This is not the big crunch because it doesn't shrink all the way to nothing. And it's not like a violent contraction. It kind of contracts slowly. and not all the way down and then starts expanding again. And so the Big Bang would kind of be that transition.

So wait, wait. This is saying that the universe expands and contracts, and the moment it switches from contracting to expanding, it looks like what we think of as the Big Bang. Correct. But there's just stuff that's been in there the whole time. There's stuff that's been there forever. Yeah, that's my...

That's my understanding. And the scientist I spoke to about it said, you know, there is some stuff from the previous universe that gets carried along into ours. But I guess like it's not a previous universe. It just looks like a previous universe. Yeah, which I guess is also sort of rejecting the question because then you have to ask how did all of this get started, what was before the first big expansion and big bounce.

So it is also not totally answering the question. Does this scientist have a answer? to that question or? No, I think that's asking too much. Okay. I mean, it is asking a lot. But both of those ideas are still kind of saying there's no big fundamental before and after here. Like, the first one says there's just no before.

Like, it doesn't mean anything. And the second one is kind of saying there's no real big bang. Or it's not like as bangy as we thought. But are there any ideas out there that are like what's before is super different from what happened after, like different from what we can see now? Yeah. So there's this one idea called a sort of mirror universe. The scientist I spoke to said to picture it like two ice cream cones kind of pointy end to pointy end. Our universe, you know, is expanding, making this cone in one direction.

Time is going forward. stuff is made of matter and then on the other side and the other ice cream cone it's going the other way the universe is running backwards time flows backwards stuff is made of

antimatter instead of matter and all of the directions are reverse so it's a literal mirror of what is going on here and the Big Bang is where those two things are or is it flowing touching I get what does it mean for time to

flow backwards. I think this is one of those things, again, where our human brains, because we live in a universe where time does flow forward, and as far as we know, it only flows forward for us, it just, like, doesn't make sense for time to go backwards. But the idea here is that, like, everything in the mirror universe is flipped. Yes. And then I guess, am I wrong in assuming that this still? begs the question of what happened before that?

Like, how did these mirror images of each other get there? Exactly. Who made the ice group codes. Yeah, so I think once again, we come back to the fact that the question is perhaps impossible because these are ways of answering it in a way that just calls the question again at a different point in the universe's history. Hmm. What are the chances that any of these theories is right? I think even most of the people who have come up with or work on these theories would say

the chances are probably not high that any one of them is correct. I think, yeah, one of them actually said that to me, he said something like, we're just trying to throw spaghetti against the wall and see what sticks and just keep throwing ideas out there for what could make sense based on what we see in the universe today. And in some ways, there's not necessarily definitive ways that we could, whether any of them was the correct explanation because you can't see before the Big Bang. And so that's frustrating to me in my inner child. So do you think it is ever going to be possible to get to a final answer on what happened

before the Big Bang? Yeah, I'm wary of saying never in science because you never know what sorts of tools scientists are going to come up with. But to me, sitting here in my chair in 2026, it doesn't seem to me like it's something we could ever find out. definitively. I think there's fundamental barriers to data gathering in the universe, and I also think there's probably fundamental barriers to how our brains can think about it. Like, maybe before isn't a concept that the universe abides by, or, you know, I think we're stuck in our own

reality that really has very little to do perhaps with the fundamental laws of the universe, and I don't know if our puny brains can figure that out. But... Is there something about the fact that you? that this feels unanswerable that is more exciting to you? Like, if you could answer this, would you want to? Yeah, I mean, I think that I think I would like to have the answer, but it is sort of reassuring to me in a weird way that there are things that, like, are probably beyond us

and that we get to wonder about and people get to come up with crazy ideas, like the universe is a four-dimensional space-time football or whatever. And I think it kind of opens up a different version of maybe awe, I guess, like not necessarily religious awe, but just, you know, cosmic awe. Like, the universe is so strange, and we have so little of it figured out. And I do think that's exciting. There's so much out there that we haven't discovered. And then beyond that, there's stuff we probably never will.

And I think that's great. The universe should be able to keep its secrets, if it wants. too. This was the first episode of our two-part series with Scientific American. If you want to read more about this and other impossible questions, go check out their special issue. You can find it in print or on their site at Scientific American.com. You should check out their excellent podcast, science quickly. And stay tuned for the second episode next week. This episode was produced by me, noam Hassanfeld. It was edited by Meredith Hoddonaut, who runs the show. Fact-checking from Melissa Hirsch, mixing and sound design by Christian Ayala, music from me, our video editor is

Jacob Reynolds, our animator is Kareem Karea, our editorial director is Joanna Salataraff, and Baird Pinkerton slung the guitar strap over her shoulder and headed back into the passageway. She tried to retrace her steps, but before she knew it, she was lost, alone in the darkness. Special thanks to Clara Moskowitz, and thanks, as always, to Brian Reznik for co-creating the show with me and Bird. If you have thoughts about the show, we would love to hear from you. You can email us at Unexplanable at Vox.com. We read all the emails. Or if you'd like to support the show, join Vox. Become a member. Just go to Vox.com slash members. And if you signed up because of us, let us know. Unexplainable is part of the Vox Media Podcast Network. And we'll be back next time

with the second episode of our series with Scientific American.