#733: The Truth About The Quantum Threat with Brandon Black

**SPEAKER_1** (0:07)
You've had a dynamic where money's become freer than free. When you talk about a Fed just gone nuts, all the central banks going nuts. So it's all acting like safe haven.

**SPEAKER_2** (0:18)
I believe that in a world where central bankers are tripping over themselves to devalue their currency, Bitcoin wins. In the world of fiat currencies, Bitcoin is the victor.

**SPEAKER_1** (0:29)
I mean, that's part of the bold case for Bitcoin.

**SPEAKER_2** (0:31)
If you're not paying attention, you probably should be.

**Marty Bent** (0:36)
Brandon, welcome to the show, sir.

**Brandon Black** (0:39)
Thanks. Good to see you, man.

**Marty Bent** (0:41)
Good to see you. I'm very happy to get you on to talk about quantum, the risk, the perceived risk, the perceived reality. What is the reality? Maybe that's where we'll start. And I'll reiterate what I was saying right before I hit record, which is it's hard as somebody who's not a quantum physicist, is not a cryptographer, to really get a grasp of what the true reality with advances at quantum computing are, and specifically how they relate to Bitcoin's security in the short, medium, and long term. And I've watched you on the front lines of sort of debating the merits of the advancements in quantum physics. Over the last year, I actually listened to your podcast that you did with Gordy last year. I thought that was really good, and that helped me get a better understanding of your perspective. But I think starting with this question of how can you be confident on one side of the other? How can you be confident that it's not as big of a risk quantum computing is to Bitcoin today? And then conversely, like, why do you think people are saying we need to rush to become quantum resistant or as confident as they are right now?

**Brandon Black** (2:02)
Yeah, I mean, I think the thing that gives me confidence, and I said on Guardiola, I think I still stand by it. You know, I can't I have an emotional confidence that we're 50 to 100 to forever years from a quantum computer breaking a meaningful cryptographic system. But that's not scientific. That's that's a gut feeling. Looking more kind of in a scientific lens at it. We live in a world constrained by the reality of physically building things. And it's hard to physically build things. That doesn't make any particular physical building challenge impossible. But the I think the quantum field is full of these, you know, we'll call it if this is possible, then all we have to do is build it kind of perspectives. And they totally just deny the realities of the difficulty in building physical things that manipulate tiny subatomic particles. Or in the case of neutral atoms, you know, individual atoms being manipulated by laser tweezers, I think they're called, or optical tweezers. Like these are incredibly difficult things to build and especially difficult to scale, right? Let's say you can build the first optical tweezer and manipulate one atom. Okay, now you want to build a grid of thousands of atoms and manipulate all of them with different tweezers at the same time. Think about how that difficulty scales. And so maybe it's possible, which is the thing I have to acknowledge when I'm being reasonable as opposed to emotional about this. But the difficulties are dramatically underplayed. And that's what the evidence shows. I think that's what people kind of don't acknowledge as the reality.
When they look at quantum, they're like, oh, all we have to do now is scale it up. But we've been working on quantum as a species for 40 years or something, as long as I've been alive.
And every time they go to scale it up, they hit new difficulties that they weren't expecting. That's the evidence we have is that it's been over and over and over and over for decades that scaling up is hard. That doesn't mean it's impossible. But the hardness is what gives me that confidence, is that based on the evidence we have seen for decades, repeatedly and consistently, they may find a way to scale it up, but it's going to be clawed out by individual small improvements over years and years and years. And at some point, they might hit on a technology that will work. And when they do, we'll see that technology go from five logical qubits in coherence for a while to 10 in coherence for a similar length of time to 20 to 40, etc. We'll see doublings, like we saw with transistors, of the same technology progressing through a scaling roadmap. And then we'll be able to say, oh, now it's doubled three times. It took 2.5 years each time to double the number of logical qubits in this technology. Okay, so at that rate, we'll get to a cryptographically relevant computer in Y years. But until we see a roadmap like that, that's the successful scaling in one technology, the evidence is it's going to be just hard-fought, tiny wins, new technologies. There's just no evidence that it's going to come any time in the next decade, or really any time in the next 20 years. So that's where my confidence comes from. On the flip side, since you asked the other side of the question too, I think the other side gets their confidence from the, let's say, the impressiveness of the wins they do get. These are incredibly difficult, mathematically challenging algorithms and designs, and the folks working on them are some of the most brilliant people in the world. And they go through the fundamental physics of our world, they go down to the very smallest subatomic particles, they figure out how things work, and then they say, oh my God, I figured out that we can do this in this easier way, or in this faster way, or in this new method of manipulating subatomic particles. And those discoveries are absolutely amazing, and they're the cutting edge of humans understanding our own world. Like, there's nothing more impressive than that. And so it's a reality that these are the most brilliant people doing incredible work to understand our world, and people get really excited about that. And so that's where they get their confidence, is that the most brilliant people are working on that problem, but that doesn't change, like, there's still the separation between the... It's probably literally possible, which is their perspective. I don't think it is, but in their world, it's probably possible. And these fundamental understandings of the universe give them confidence that it's going to be solved in the real world in physical devices.