Is what you see, really the way the world looks? As an Optical Physicist Dr. Greg Gbur studies that and more. We talk the latest in optical physics, the possibility of invisibility, coherence theory, meta materials and why movies are wrong about lasers. Then, we countdown the Top 5 Celebrities You Don’t Wanna Share a Name With.

Dr. Greg Gbur: 01:51ish

Pointless: 31:23ish

Top 5: 47:36ish

https://skullsinthestars.com/ (Dr. Greg Gbur’s Blog)

https://twitter.com/drskyskull (Dr. Greb Gbur’s Twitter)

https://yalebooks.yale.edu/book/9780300231298/falling-felines-and-fundamental-physics (Falling Felines and Fundamental Physics, Dr. Greg Gbur’s Book)

Interview with Optical Physicist Dr. Greg Gbur

Nick VinZant 0:11

Hey everybody, welcome to Profoundly Pointless. My name is Nick VinZant. Coming up in this episode, the latest in optical physics and celebrities, you don't want to share a name with,

Dr. Greg Gbur 0:24

I would say we can't completely say we look exactly the way we think we look. Because a lot of it depends on how our brain interprets stuff. There are predictions that we should be able to build computers that are really based on quantum physics, that can do things that are traditionally impossible.

Nick VinZant 0:46

Could there really be an invisibility cloak,

Dr. Greg Gbur 0:48

it may be in principle possible to do it, but in practice, we will probably never make one as good as people would like to see them. On the other hand,

Nick VinZant 1:01

I want to thank you so much for joining us. If you get a chance, like, download, subscribe, share, we really appreciate it really helps us out. So I don't really know very much about optical physics. But I was fascinated to find out just how big of an impact this has on nearly everything around us from light and how we communicate to the future of computers, the possibility of invisibility, even the idea of is the way that we see the world. really how it looks. Our first guest is a professor of optical physics at the University of North Carolina. This is Dr. Greg Gabor. What is optical physics? I don't I don't know what that is, honestly,

Dr. Greg Gbur 1:52

optical physics is really just understanding the physical nature of light and what it is and what it can do.

Nick VinZant 2:00

I don't know what light is, it's something I've never even thought of like it's it's, it's light. What do you mean what?

Dr. Greg Gbur 2:07

Well, yeah, that's a question that's really obsessed scientists and philosophers for centuries. Nowadays, we consider light to be a collection of massless particles that carry energy and momentum, but also have wave like properties. So if you've ever heard the quantum physics, discussion of wave particle duality, light fits that bill when you're looking at, when you're looking at light, your your eyes are collecting a bunch of light particles, which we call photons, that travel through space, behaving like a wave as they're traveling to your eye.

Nick VinZant 2:49

I have no idea what that means. Is, is, I guess my question would be like, Am I too dumb?Or have you guys not quite figured it out?

Dr. Greg Gbur 3:00

I would really say that we haven't quite figured it out yet. And part of the reason for that is when you get down to studying things on that small of a level, the rules that we're used to in our day to day life no longer apply. So the way things behave in our daily lives is very different from the way things behave on this atomic level or below for centuries, or 1000s of years. Nobody ever went any deeper than that. They said, well, light travels in straight lines from place to place and reflects off of shiny surfaces. And when it goes into something like water, it changes direction a little bit. And it took a lot of research for people to realize that light has wave like properties that it acts that it acts in some ways like water waves rippling on a pond or sound waves traveling through the air. And then for about 100 years from 1800 to 1900. People were convinced that light was exclusively behaved like a wave. And then in 1905, Albert Einstein said, Well, no, actually sometimes it acts like a wave. Sometimes it acts like a particle. And we still don't completely understand what that means.

Nick VinZant 4:17

us not completely knowing what it is, is does that have a big, everyday kind of application? Or is that more of an academic exercise?

Dr. Greg Gbur 4:28

more of an academic exercise. So the mathematics and the theoretical idea, understand our theoretical understanding of light is really good. We have computer simulations so we can simulate the behavior of light in all sorts of stuff. And that's made its way into computer games. For instance, there's so many computer games now that have built into their engines, realistic, light interactions, again on this sort of daily scale so you get very realistic lighting effects. The place where things get troubling is just trying to understand what exactly it means and how it fits into a bigger picture of how we should view the universe. But that's still an open question for really, almost every atomic particle or small particles on that sort of tiny atom sizes. We know we can very well describe mathematically what they'll do. But the rules that we've created to study this don't completely make sense.

Nick VinZant 5:36

Like how does this kind of translate into my everyday life,

Dr. Greg Gbur 5:40

most of the study of light that's relevant to everyday life life these days is the wave properties of light. So there are things like, like fiber optic cables, for instance, that are sort of forming the bulk of our communication system with the Internet, and telephone communications, and so forth. All of that requires an understanding of the wave properties of light, largely because we're squeezing the light through these tiny optical fibers. And you really do need the mathematics of the wave properties of light to describe what it's doing. So from a practical sense, a lot of the optical engineering that's being done takes advantage of a good knowledge of the wave properties of light, those quantum particle properties of light. Those are things that really still are not, I would say, in everyday usage. A lot of that individual quantum photon stuff is still in the realm of physics research, as opposed to applications.

Nick VinZant 6:51

I never, I guess I never put that two and two together and thought that fiber optic cables meant that we were sending messages by light. I never, like I just assumed we were it was like electricity or something. I didn't know that what we were actually doing. That's so interesting. And I'm okay, to kind of put things in perspective, like, on a scale of one to 10. One, we know nothing, like we don't even know where this light is coming from or anything. And 10 we got this thing locked down, we got all the answers to every question you can think of? Where do you think that we would be at with light right now?

Dr. Greg Gbur 7:29

Um, I would cautiously maybe say around an eight. We understand the physics of light, we can control light to an incredible extent now we have technology, we know how to produce it, detect it manipulate it. But there are these sort of fundamental unanswered questions that potentially could lead to some surprises in the future. So. And in fact, I like to characterize at the beginning of this new century, around the year 2000, people started working with the concept of what are called metamaterials materials that are not found in nature, but that you can in principle construct in a laboratory. And these metamaterials can have very unusual effects that you don't see in nature, and that people previously thought were impossible. And I like to describe the history of optical physics is that we've spent hundreds of years if not 1000s, if you want to go back to the ancient Greeks, we can go 1000s, but we've at least spent hundreds of years asking, What can light do? Like what are the limitations? What are what can we do with light? What Can't we do with light? And since the beginning of the 21st century, the question is changed a bit? We're now a lot of people are more asking, how can we make light do whatever we want it to do? The idea of a metamaterial really started in the in the late 90s. And the the ideas is that most of the time, when we're trying to do optics, we're working with natural materials like glass. And the optical properties of those materials are really dictated by the natural chemical composition of the material and its natural structure. And then people started saying, Well, what happens if we change that structure on a really small scale on a scale comparable to 10s or hundreds of atoms? Well, it turns out that if you can do that, if you can manipulate the structure of that material on that scale, you can you can make that material have very different optical properties and do very strange things. And that's sort of the birth of this idea. metamaterials is wow, if we, we if we can manipulate the structure of the material on this really small scale, we can do all sorts of things that we previously thought were not possible. However, in general, for for visible light that we can see with our eyes, we still don't know how to very efficiently make metamaterials and it and fabricate them efficiently so that we could use them for commercial devices.

Nick VinZant 10:34

You mentioned the light that we can see with their eyes like what percentage of light can I actually see,

Dr. Greg Gbur 10:39

I don't know about percentages. But visible light is a really small part of the total electromagnetic spectrum. So electromagnetic waves that I was talking about visible light that goes from our reds to our violets. That's what we call the visible range that our eyes are sensitive to. And then on the on the red end of the scale, you go through infrared light, and you go through microwaves, which are another or another type of electromagnetic radiation. And you go all the way down to the low end of the spectrum are radio waves. And if you go on the other end of the spectrum, after violet light, you have ultraviolet light, and then it goes, then the energy of the individual photons goes up and you have x rays or higher energy, all the way up to gamma rays, which you get out of nuclear reactions are very high energy, photons.

Nick VinZant 11:48

Okay, this is probably getting into a little bit of a different kind of subject. But what, you know, the human body in the brain is very, very adept at kind of doing the things that we need to do, why wouldn't we be able to see that? Like, what would be the reason that the, our evolutionary history said, Nah, don't worry about that stuff? You don't need to see that?

Dr. Greg Gbur 12:04

Yeah, that's a really that's a really good question. An interesting one. And I don't want to I don't want to speculate too much on evolution. But my understanding, and my guess would be is that most of the materials that we that most of the most matter that we see, in the real world, is most clearly visible in that in that range of visible light. Well, two things, first of all, things are probably most visible in that visible light range. So it's sort of the ideal range of colors are the ideal range of wavelengths, since we're talking about light waves, for us to see. And the other part of it is the sun. The sun gives off radiation over a large range of wavelengths. But it's really the peak is centered in that sort of yellow region. And it gives off infrared radiation as well, as well as ultraviolet, but it gives off far less of that.

Nick VinZant 13:11

But okay, this would be like, my dumb guy. Question, right? So if we only see these certain wavelengths, is there chances that there are just things out there? Like there's a Blimey be super dramatic to make a point, there's some giant animal that's can only be seen in ultraviolet light floating around in the sky. And it, there's 1000s of them, and we just don't see it, right. Like, I'm being dramatic. But I think you really get my question, right? Are there just all kinds of things, potentially big things that are just,

Dr. Greg Gbur 13:43

we just don't see it? Funny thing is, since I'm actually writing a book on the subject of invisibility right now been delving into the science fiction, and there are a lot of science fiction stories that are predicated on that idea. There's a classic story by Ambrose bierce, called the damned thing which is about a monster that is colored outside the visible spectrum. And there's another there's a novel called the sinister barrier, which is a very bleak novel, which is exactly this premise that the Earth has actually been controlled by these invisible beings, probably since our beginning our existence and then some scientists managed to see into like the infrared and realize that there are these creatures all over. Though the reality is and this goes back to what I was saying about the structure of matter, is that ordinary materials pretty much everything that we see in nature, is at least somewhat visible in the visible light spectrum. And that has to do with the structure of atoms themselves that pretty much every atom And combinations of atoms are at least partly visible or, or significantly visible in that visible light range. And I don't know that there has ever been found any material that somehow there, I don't think there's any material that I've ever heard of that is completely invisible in that range. It's just outside of normal, it would be outside of chemistry as we know it.

Nick VinZant 15:28

So you're saying there's a chance?

Dr. Greg Gbur 15:32

I've learned? I've learned not to say never, because I can get myself in trouble by saying that too.

Nick VinZant 15:39

Are you ready for some harder slash listeners submitted questions? Since you mentioned it? We'll start with this one. could could there really be an invisibility cloak? Like, could something like that exist? Could we make that someday?

Dr. Greg Gbur 15:54

I'm still I'm still at the level of saying that. It may be in principle possible to do it. But in practice, we will probably never make one as good as people would like to see them. On the other hand, ever there there have been a number of fundamental physical limitations that people have noticed about the idea of making an invisibility cloak. And very recently, in fact, I think it was in late 2019, early 2020. Some researchers came out and said at least one of those major limitations that we thought was kind of a hard physical limitation could be, in principle overcome. So I'm a little more I'm a little more on the side of well, maybe it could happen, though, the technical challenges and making it work are still pretty big. I would think.

Nick VinZant 16:59

This leads us into our next question, best depiction of invisibility. Harry Potter's cloak, Wonder Woman's plane, or the Invisible Man.

Dr. Greg Gbur 17:10

Oh, mmm. That's an interesting question. I would throw out Harry Potter's cloak just because it's magic, Wonder Woman's invisible plane, maybe a good depiction, because I could imagine that, at least all the depictions I've seen have really shown it is just a very transparent craft. That would be very hard to see, which seems plausible. The Invisible Man is sort of an interesting one. Because the, in the original story, the premise is that a person chemically makes themselves completely transparent, and completely invisible, I should say. And that doesn't really seem possible to completely change your chemical composition, and still be alive. But a few years ago, there was some chemists that came out and said, we've made this we have this, we came up with this chemical that will turn a a dead specimen almost completely transparent. And then in a press release, they said, We'd like to try using this and a lesser dose on some living creatures to see if we can get it to work. So I don't know if they've ever succeeded. But people are still trying it. It's it's kind of fascinating how, especially these days, no matter how ridiculous an idea seems, and science fiction, there's probably somebody out there that said, I should give this a try. Maybe this will work.

Nick VinZant 18:46

It's always the thing, like you never know, maybe you actually turns out to be really easy, right? Like, all we had to do is connect the wire. Boom, that's it. That's it. Mmm. Do things really look the way that I think they do? Or is that just our brains interpretation of it?

Dr. Greg Gbur 19:04

It's an interesting question. And I don't have the best answer for it. But it is one at one way I can look at this. Because this is something that personally drives me crazy is you may notice that depending on what sort of camera lens you use, you can look very different in photographs. Because a wide angle camera will give you one look and a narrow angle camera will give you a different look. And, of course, my self conscious self at times looks at certain photos and he goes oh, that's horrible. And then I'm like, I don't look like that. It's like Well, I'm using a wide angle, phone lens really close to my head. So my head looks huge. So to some extent, yeah, perception and our visual system. We can't I would say we can't completely say we look exactly the way we think we look because a lot of it Depends on how our brain interprets stuff. This is sort of a weird question that I asked myself at times is, how do I know that the colors that I'm seeing are the same colors that everyone else is seeing?

Nick VinZant 20:14

But we have a test, right? We have something that could say, No, this is red. Do we do well?

Dr. Greg Gbur 20:23

Well, that's what I mean is that physically, we know what red is, we can talk about it in terms of the wavelengths of light and the combinations of colors. But I'm really thinking about, is that picture in my brain of what red is? Or any other color? Would that agree? If I could magically jump into somebody else's head? Would would our brains interpret that the same way? It's one of those things that like, I like to think about it for about 30 seconds, and then like,

Nick VinZant 20:56

I can, like, it's Wednesday, me, and I can't throw my whole brain for a loop about the nature of reality in my existence. This is just too much for me. Um, this is way above my head. What is quantum noise and coherence theory?

Dr. Greg Gbur 21:13

Let me start with coherence theory, because that's one of my specialties. So what it really comes down to is, when you're looking at a light source, like an ordinary light bulb, you're seeing what looks like a steady stream of light, or you look at the sun or a star, you're seeing a steady stream of light looks pretty constant, you know, barring power outages, or fluctuations of power, or whatever. But really, what you're seeing is a light wave that is fluctuating really, really fast, much, much faster than you can see with your eye. And in fact, much faster than we can detect with, with most detectors. And coherence theory is a subset of optics that is all about asking, How do the random fluctuations of light affect how it behaves? It's an essence. It's really analogous to statistical mechanics or thermodynamics in physics. So statistical mechanics is all about, you have a box that's got that's filled with gas. If you look at that box of gas, you know, on average, it doesn't look like anything's happening in there. But they're all these. They're all these atoms bouncing around, or all these molecules bouncing around. And then the question comes, how does that how does that though? How does all of those motions have all of those different atoms and molecules? risk? What How do all of those combined into the behavior that I'm seeing at a particular time? And coherence theory is basically the optics version of that it's saying, okay, when I look at a light source, I'm actually seeing all the, what I'm really seeing is, is the average of a bunch of random fluctuations of light. And how do I, how do I study the physics of that? How do I relate what I might, how do I relate what I'm seeing to the random fluctuations or the other way around?

Nick VinZant 23:24

Then makes sense to me, right? Like light is actually going like every direction and all the time. But somehow my somehow I piece it together is like, Oh, it's coming from that light bulb? Yeah. Is that kind of

Dr. Greg Gbur 23:37

a little bit? Yeah, you can think of two is that when you're looking at a light bulb, or the sun, you're really looking at the output of a bunch of atoms, a large number of atoms that are all radiating independently. They're all doing their own thing. It's like a bunch of people in a room randomly shouting words out. And when all those people randomly shout out words, on average, you're gonna hear something. And the question then is, what do you hear? What is the AV? What is the average sound made by all of those noisy people?

Nick VinZant 24:15

Let me follow that. Let me follow that up with a brilliant question of best use of lasers in a movie.

Dr. Greg Gbur 24:21

I'm still going with gold finger using a laser beam to slice James Bond and half is still probably my favorite, though I also should give a shout out to the movie real genius because that movie, Val Kilmer way back when it's all about graduate students, basically studying optics and trying to make a really big laser. And it is depressingly accurate. Clearly the writers of that movie knew something about grad school and about lasers and physics.

Nick VinZant 24:54

Like if we, okay, science fiction kind of stuff, if we somehow invent laser blaster Like, what's that? What would that really look like? What movie would you say like, Oh, that's, that might actually be what that would look like.

Dr. Greg Gbur 25:08

So far, I'm not sure any movie is really captured it well. And part of that is, is that lasers can be incredibly dangerous, but their danger comes from dumping a lot of energy in a location at one time. So you know, you can burn a hole through something. But what lasers don't have, which you see it a lot of movies is they don't have a kick to them. Like if somebody gets shot with a gun, the bullet makes an impact and knocks them backwards. And in a lot of movies involving laser blasters, and so forth, you'll see the people get knocked backwards by the blast. But a real laser doesn't do that. Because the the photons, the light particles don't have any mass. So they don't have a lot of kick to them in comparison with a gun. So if you shot someone with a laser gun, you might burn a hole in them, but you wouldn't knock them flying.

Nick VinZant 26:11

So you would just be shot and you'd still just be standing there with a hole in your chest. Yep, but you still be standing in exactly the same place. Pretty much um,

Dr. Greg Gbur 26:20

I should say that light does carry momentum, momentum being that kind of oomph of motion that when one you know billiard ball hits another, it knocks it away, because the one ball transfers the momentum to the other. Light does have momentum, it does have a little bit of a kick to it. But it's a very small amount of kick pretty much negligible on a day to day basis. Which is why when you go out on a hot day, you know you don't open your front door and get blasted back into your house. On a sunny day.

Nick VinZant 26:48

Will we ever be able to travel past the speed of light or get anywhere close to it?

Dr. Greg Gbur 26:53

Everything that we know about physics right now says that we won't get past the speed of light and that that is a fundamental barrier. And everything that we know about Einstein's relativity in the speed of light suggests that it would be pretty close to impossible to get a spacecraft even close to that speed like I once mistakenly put when I was a starting Professor I once mistakenly put as a homework problem for students. I said, Okay, calculate the well like the fraction of the speed of light that the space shuttle went. And it's just this ridiculously tiny number. Our fastest craft have not even gotten close to the speed of light yet. However, again, I can say there's there's, we know, we know a lot about physics in the universe. But there's still plenty of things that we don't really understand things like dark matter and dark energy that make up a ridiculous fraction of the universe that we can't even see. So maybe somebody will figure something out in the future.

Nick VinZant 28:12

Imagine you're going to like meet the your idol. And you've got to wow them with one light fact. What are you going with?

Dr. Greg Gbur 28:21

Okay, I've got a good one. So it takes roughly about two square meters of sunlight, properly focused to melt rock. Wow,

Nick VinZant 28:36

you can even even from here on Earth 93 million miles away. Like it's still

Dr. Greg Gbur 28:44

you know, there's now you can find videos online of these places, I believe they call they're caught. It's called a solar furnace where this is exactly what they have is they've basically designed a big, probably a mirror to concentrate a lot of sunlight into a little spot and they can plop, plop an actual piece and they can plop a piece of metal in there and melt the metal easily and actually just melt stone. And you know, so when you're out sunbathing, you can think about how you know there the sunlight that you're encountering is is pretty intense. Really.

Nick VinZant 29:23

Last question, Where do you what do you think the future holds?

Dr. Greg Gbur 29:28

Well, in my own areas, it seems like the big things that are starting starting to come around is some quantum technology of using quantum physics to do calculations and to do cryptography. So, because because individual atoms the physics of individual atoms is so radically different than what we experience on a day to day scale, there are predictions that we should be able to build computers that are really based on quantum physics that can do things that would, that are traditionally impossible, like solve mathematical problems that would otherwise be impossible to solve or break codes that would be impossible to solve. And there are already commercial devices that claim to use quantum technology for quantum computing. I'm not exactly sure how effective they are not. But that that would be one guest for where your we might see things going is a lot more of a push to adapt quantum physics into our technology.