What Makes Something See-Through? | Neil deGrasse Tyson Explains...

foreign check I got another one for you okay okay it's transparency okay all right I like all right I like the concept it's very important um in a democracy and uh yeah yes yes yes that's not that's more figurative invocation of the term normally established you have a healthy uh media you know BS yes yes yes yes yes yes so unless it's behind closed doors then it's not transparent yes by Design because it would have National Security implications they tell us yeah they call that that's then um then that's when I'm I'm like really no is it really am I is your government protecting you right are you really protecting me are you really going Men In Black on me or no they don't want you to know about the aliens right right okay I just want a general discussion about transparency because I think it's fascinating Okay so if we're in the same room and I see you uh you know there's a day when said well there's nothing there so that's why I can see you except of course there's air there of course all right so it's not that there's nothing between me and you blocking The View air is blocking the view except that air happens to be transparent to the light that we are detecting okay okay it is transparent air all right so now when we build domiciles homes and whatever you want to be able to look outside you could just cut a hole in the wall and look outside because air is transparent but we don't we want to protect ourselves from the elements so instead of having air in the opening on the side of the world that is itself transparent to visible light okay and that's what we call Windows yes which are variations on sio2 silicon dioxide okay silicons unless you grew up you know not privileged you know and then it was then it was it was polyethylene I think you you didn't have to be privileged to have glass windows I think that's not oh excuse me Mr rich guy excuse me excuse me black Trump what's that go I'm so poor I don't have a pot to piss in or a window that's the one I heard all right so so that's transparent right okay the Sun is peaks in the energy that it sends to Earth it peaks in the red orange yellow green blue violet part of the spectrum the visible light part of the spectrum and within that it Peaks right at the green yellow boundary okay so the sun gives more green yellow light than any other kind of light that's out there all right that's part of why we say the sun is yellow except it's also giving just as much green and no one says the sun is green right so but it's the mixture of all of those gives us the color of the sun which is basically white all right my point is how does sunlight reach us here on Earth because the atmosphere is transparent okay but occasionally a cloud Moves In clouds are not transparent to visible light so they block the sun right this sounds all very basic and simple agreed I'm I'm right now I'm with you on every step okay so now now what else is transparent all right you are in your home you have glass in the windows you have walls I do like you have a roof and a floor okay that's true and then your cell phone rings well is your cell phone using visible light no no it isn't no it's using microwaves right I have a really crappy carrier so my cell phone doesn't it's not wrecking it's not working okay so the microwaves the microwaves have no hesitation penetrating your walls with or without the window okay you could you could use your cell phone in a windowless bathroom so two microwaves which are part of the electromagnetic spectrum your home is transparent nice so if you had microwave vision your home basically disappears you might see the the door frames you know depending on how it's framed out you might see some metal wiring and things but overall the house disappears in the same way when you look out a window you're not looking at glass the glass disappears to you right and and you know it does when people walk into that stuff in in stores actually I'm looking out my window right now and I'm like maybe I need to clean these because this glass is not disappearing this is straight up safety glass that I'm looking at right now it's safe to go no one is walking through this class so uh yeah so you know what safety glass is it's glass that breaks into a zillion tiny pieces I didn't know that I thought it was glass that didn't break like you know basically no no no well that could be a variant on safety glass but in cars where they say safety glass right when the car windshield breaks it completely shatters into tiny little bits of glass so the question is how does it make me feel safe no no but you ask how deep into you can a tiny piece of glass go like the depth of the tiny piece of glass whereas if the windshield broke in these huge shards yeah it could penetrate you and and get into your heart break your jugular or whatever the worst you need is a bag of Band-Aids at the end of the broken glass of safety glass that's all it's designed to be completely shattered all right all right that version of that variety of safety glass is designed for that that's it all right so but that's not what we're talking about we're talking about the fact that two microwaves your home is transparent right your home is also transparent to largely to radio waves now if you're old school some of our listeners are old school and know what radio is Radio is you'd go into a tunnel if you were listening to FM the FM signal would drop out if you're listening to am it would stay yes okay am has greater penetration through the surroundings of tunnels than FM does all right so it's all a matter of who is transparent to whom now let's say you let's tune our eyes to so you have uh there's red orange yellow green blue violet below red we have infrared okay and Below infrared we had microwaves so microwaves get through stuff okay right but microwaves have a hard time getting through metal okay the metal interacts with them it prevents that I learned that the hard way in my oven but it's a story in your microwave oven you have a metal so this the door is made of glass right okay microwave goes right through the glass but it's not pure it's not only glass your door has this mesh on the inside right okay and the wavelength of microwaves is like a few millimeters up to maybe a couple of centimeters in that zone wow so that mesh has holes that are smaller than the size of the microwave so they can't come through so I can see in but the waves bounce back you can see him because you're not you're not using microwaves to see anything which goes through the holes right but then the visual is way smaller than those holes so I'm not getting a radiator because the waves can't get through the holes so they bounce back into the microwave back into the microwave correct okay correct so now let's look at infrared which is brilliant what a simple yes science and engineering this is what we these are the foundations of civilization right I can't believe I got a sign seven what oh no now let's go to infrared so now let's look around us in infrared you'll see things that are infrared is a good measure of temperature because things will glow if they're glow we know this from Predator things we know it from Predator from Predator yes that's how we know about infrared okay we didn't pay attention in school but then we saw the alien monster up in the tree and it was making that gurgling sound like and it was looking at Arnold Schwarzenegger you know and uh and we saw him you know damn you remember the sound effects too damn man if if it bleeds we can kill it right which is brilliant yeah but that's it that's that's a that's the most brilliant line in the movie so he was wrong [Music] if it bleeds we can nuke it yes exactly because that's so that's how it died it nuked itself so it didn't bleed to death he blew up after they're going jungle okay because he lost first and the pressure is a bad loser let me just tell you that right now I ain't never lost no game and been like that I'm nuke in this whole place this whole place is going on mushroom clouds and all screw you humans that has nothing to do with what I'm trying to say I know I'm sorry you're going off on a predator tangent all right so but you're correct Predator has Vision uh has infrared vision by the way so too did Terminator interestingly also played by that same guy so all right so infrared I look around and I see things glowing then I try to look out the window and I can't it's opaque it is opaque and you can test this yourself you ready okay so put someone on one side of the window and have them turn on a flashlight and the other side they can see the flashlight now have someone turn on a like a glowing oh like a like an iron like an iron you know a red high and have him go on the other side of the window and ask if you feel the heat of the iron you do not feel it at all oh that's so cool because glass is like an insulator glass prevents the transmission of heat yes wow okay so glass transparent glass is opaque to infrared light light yes yes nice okay well let's keep going um how about uh radio waves but like radio waves are what you get when you go beyond microwaves they have excellent penetration depth through everything basically that's why it works as communication otherwise you say I'll call you at 300 310 but get out in the street and face the radio tower when we're talking that if you know that's not what it is wherever you are we can find you and we can communicate with you right so so I'm just trying to have people broadly think about the fact that when you say something is transparent technically you should be specifying transparent for what wavelength of light right for what wavelength correct by the way you know what else is opaque to Wood glass blocks UV glass blocks UV glass out of the box will absorb 97 percent of UV that hits it and I've done this experiment using in a laboratory okay out of the box it's a UV filter when you buy special sunglasses that say UV board protections right they're getting you from the 90s if it's they're made of glass they'd get you from the 97 it gets for free up to like 99 okay wow now there are physicists when they were testing atomic bombs and they had high energy radiation there what they would do is they would dip behind the windshield of the jeep that drove them out there oh it would still be bright visually bright but the high energy radiation would be blocked by the transparent glass so glass blocks infrared on one side of the visible spectrum and ultraviolet on the other side of the Spectrum which is beyond Violet and it transmits by definition what we call visible light and that's what makes glass quite a fascinating thing in our in our in our culture and in our civilization so that's that's why Wonder Woman never gets a tan um riding around the glass ship a plane I forgot about that place it's some flying thing it's a flying thing but it's a parent's flying thing yeah because we call it a plane but the truth is we we can't see it so we don't know what it is to be honest right right because it's invisible so in Harry Potter they had the invisibility cloak oh that thing is cool okay so here's what you do is since you are in the way between me and what's behind you okay I can't all of a sudden make you transparent but you if you but we we have research such as what they had in Harry Potter whereas you put on this invisibility cloak and what happens is the light from behind you hits the back of your cloak and is channeled around the front and then comes straight back out from the front of you wow this is a very complicated Optical Pathways that the light has to take if that then my pathway goes to your chest around you and to the wall behind you and I don't even know you're standing there because I don't know the light took that Securities route because it comes straight to my eye wow so I can make you transparent if the light behind you is brought around to the front of you this was also shown in a James Bond film I forgot which he can make his his Aston Martin disappear but really you're just bending the light to the front so you're bending the light around it that's correct correct and it means you should still be able to shoot it the bullet's not gonna say hey where'd the car go I don't know what to do that's funny the bullet still has its trajectory and it's going to be right to the Target um so just that was just a little I thought I'd spend a couple of minutes talking about transparency I liked it yes and of course the the uh counselors and and therapists have have you have up taken the word all right are you transparent with your spouse are you transparent okay and that's somebody who's trying to that's somebody who's trying to end your marriage and let you know right if I tell you to be transparent with your spouse they are trying to end your marriage is what they're doing every good marriage is built on a healthy lie and people should know this it's just Chuck's advice it's a healthy lie that that saves every marriage okay okay thank you Chuck for your expert uh 24 years and I would never I tell her that she looks just like the day I met her that is what I tell her girl you look just like the day I've met you oh look at you look just like the day I met yeah now I am lying through my teeth I'm lying is what I'm doing this is everything you see that Geico commercial did you see the Geico commercial with Abraham Lincoln and Mary Todd Lincoln and um you know it's an old video footage because we didn't have video back then right in Lincoln's day so but it's it's it's old D old time right you know black and white all right sepia tone right so he says um was uh Lincoln lie that was that was the setup right right and so Abe Lincoln is just there in his office and Mary Todd come in comes in with a new dress and she said does this make me look fat Abe Lincoln says oh uh he doesn't answer and she runs out of the room see honesty that was the time to lie is that what you're saying that's it this has been yet another star talk explainer this one on the transparency of all that's around us Neil deGrasse Tyson here your personal astrophysicist Chuck your personal comedian can I call him my personal comedian yeah I was gonna say not theirs nothing until next time keep looking up foreign [Music]

Channel: StarTalk

Views: 217,449

Keywords: startalk, star talk, startalk radio, neil degrasse tyson, neil tyson, science, space, astrophysics, astronomy, podcast, space podcast, science podcast, astronomy podcast, niel degrasse tyson, physics, transparency, invisibility, waves

Id: UBy7FjnGB40

Length: 18min 34sec (1114 seconds)

Published: Tue Apr 25 2023