Making A Computer From Bubbles Stanford professor Manu Prakash explains how bubbles can be used as bits to make a computer. By directing the bubbles through etched pathways, they act like electrons traveling through circuits. In this system, however, the computer is powered by gravity and the bubble bits can carry things inside of them as they compute.

Making A Computer From Bubbles

Making A Computer From Bubbles

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Stanford professor Manu Prakash explains how bubbles can be used as bits to make a computer. By directing the bubbles through etched pathways, they act like electrons traveling through circuits. In this system, however, the computer is powered by gravity and the bubble bits can carry things inside of them as they compute.


Flora Lichtman is here with a Video Pick of the Week. And it's something about an everyday object?

FLORA LICHTMAN, BYLINE: An everyday item. The Video Pick of the Week this week is about - oh, that was really bad.


LICHTMAN: I tried to do a sound effect. Oh, live radio. Sorry. That was a very weak...


FLATOW: You need a fresh bottle.

LICHTMAN: I did shake it up before I came in. All right, anyway. Sorry. Forget it. Let's reverse.

FLATOW: A live - that's a - yeah.


LICHTMAN: It's about bubbles.

FLATOW: Want me to (makes noise)?


FLATOW: There you go.

LICHTMAN: We don't need this bottle of seltzer, this defective bottle of seltzer. OK.


LICHTMAN: So the Video Pick this week is about bubbles being used for something that really surprised me. I'll never look at seltzer the same way. This guy, Manu Prakash at Stanford, says that you can use bubbles to make a computer.

FLATOW: A computer out of bubbles.

LICHTMAN: A computer of bubbles.

FLATOW: Bubbles computing.

LICHTMAN: Bubbles can do computations...


LICHTMAN: ...I learned. This is like a real, make-your-hair-hurt kind of subject for me, anyway.


LICHTMAN: It took a lot of deep thinking to wrap my head around it. But here's how Manu walked me through it, so hopefully we can explain it. He says that the basic concept is this: To do any kind of computation - and Richard - and Feynman has talked about this, and he explained this to me, too, that you need a physical something...

FLATOW: Right. represent computation, so chalk on a chalkboard.


LICHTMAN: Yeah. Fingers...

FLATOW: ...digits.

LICHTMAN: That's the one I - we can use.


FLATOW: That's right.

LICHTMAN: And in computers, it's usually - it's electrons running through wires, right?

FLATOW: Right.

LICHTMAN: So if you take it - you could take an analog to that and say: Bubbles going through tubes could be used the same that electrons are use for computations in computers.

FLATOW: Right.

LICHTMAN: And the critical point here is that bubbles interact with each other through the environment. You need this to make - so it's not just bubbles going down a tube. But if two bubbles are near each other, their behavior changes. In other words, one bubble goes through a tube, and they're all going to go down the right path, let's say.

FLATOW: They're making a decision of that.

LICHTMAN: They make a decision when another bubble is present.

FLATOW: Right.

LICHTMAN: They go down the other path. And with that, you can make this AND-OR and NOT gate.

FLATOW: Computer logic.

This is...

The bubbles make that decision.


FLATOW: Very interesting. Talking about bubbles on SCIENCE FRIDAY, from NPR. And your video, which you made, shows the actual computer with the tiny, little bubbles running through these little pipes...

LICHTMAN: These little circuits.

FLATOW: Circuits.

LICHTMAN: Yeah, these tiny, little tubes.

FLATOW: And so if, like I guessed, because we live in the world of binary, of ones and zeroes, if you have a bubble, that's a one.

LICHTMAN: Correct.

FLATOW: If you don't have a bubble...

LICHTMAN: That is a zero.


LICHTMAN: So you can make these, sort of, basic building blocks of computers is what this researcher showed. And he actually has videos of these adorable little bubbles going through different tubes...

FLATOW: And I think...


LICHTMAN: ...a ring oscillator, if that means anything to you. You can see bubbles doing that and an AND gates, and stuff like that. So you can actually watch them going through.

FLATOW: On our Video Pick of the Week up on our website, the bubble computer. It's fascinating to watch the bubbles go through these little tubes. And they're all spaced out quite evenly in the tubes. And they go through little mazes and touch each other and push each other around, and...

LICHTMAN: And you might be thinking, you know, well, why? Bubbles, obviously, are a lot slower than electrons.

FLATOW: A little bit.


LICHTMAN: So you're not going to be doing like your iPhone, you know, Yelping from your bubble computer. And they're really big compared to electrons, but they have this added advantage that electrons don't have. They're, like, little, teeny-tiny test tubes. They can carry things with them. So the thing that excites Manu Prakash about his work is that you could actually have them physically transport things while they're doing a computation - so create as you compute. It's like a two-for-one deal.

FLATOW: Wow. Well, that's kind of interesting. And not only is that a - not only is the concept terrific, but the video, our Pick of the Week is beautifully shot with the bubbles. I mean, you have some great photos of - you know, you look at the bubbles on - was it a - is it a whisky shot glass that you have there or something?

LICHTMAN: It's a little glass.


FLATOW: And the bubbles - because you're using a - so closed up, watch them jump around.

LICHTMAN: It's one of my favorites, yeah.

FLATOW: You know, I love listening to it, but I was so distracted by just the bubbles jumping around on the glass.


LICHTMAN: Yeah. It is really beautiful. I - looking at bubbles through a macro lens, I felt like I could have done this for hours. They, like, stick to the glass.


LICHTMAN: And they went - and they move very quickly when they explode. So it is fun to watch. It was fun to shoot, too.

FLATOW: It's - maybe - we should do more of these tiny, little macros.

LICHTMAN: Yeah. If you have suggestions for tiny things you'd like to see - we were talking about maybe how the eye responds to when you turn the light on and off or...

FLATOW: Right.

LICHTMAN: You were saying there's something in your house that you wanted to macro.

FLATOW: My - when I water my orchids, I watched the water. Actually, a big bubble, a drop, will be on the roots, and I can watch it shrink over real time as the root sucks in the water, you know?

LICHTMAN: Well, that sounds like one for next week.


FLATOW: So maybe - you were talking about maybe cream and coffee swirling, there's a certain pattern that takes.

LICHTMAN: Yeah, yeah. I think, actually, there's research on that. I hope to look into that. But, yeah, I think the macro lens - I never get bored with that kind of stuff.

FLATOW: And there's bubbles - bubbles and beer, we've done stories on Guinness. It actually creates - the Guinness stout creates a whole, actually, convection current of bubbles going up and down.

LICHTMAN: Yeah. Those bubbles go down.



FLATOW: Richard Saracen, I think he was on our show years ago talking about - he actually studied this and made films out of it. So...

LICHTMAN: You know, this is sort of what I love. And also for this video this week, Manu Prakash said that he got this idea to make this bubble computer when he was in the subway. So he's sitting in the subway, and he's looking at the subway map - and you'll see if you look at the video - it looks very similar to the circuits he made.

FLATOW: Right. I thought about that.


LICHTMAN: He thought, you know, hey, he's studying fluids. He's at MIT. And he thought, hmm, I wonder if you could do this. So, you know, inspiration is everywhere.

FLATOW: And as they say in Great Britain, it's the tube, right, which is...


LICHTMAN: It's the tube. Very good.

FLATOW:'s the tube, right? It's the tube, which is what he made with his bubbles, the tube.

LICHTMAN: Yeah. Absolutely.

FLATOW: Thank you, Flora.

LICHTMAN: Thanks, Ira.

FLATOW: Our Video of the Week up there in our website, bubbles. It's really cute. If you just want to watch the bubbles, for nothing else, it's just a great watch on our website, at

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