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Current time:0:00Total duration:7:58

Video transcript

so let's think a little bit about ways and the classical notion of what a wave is it's a disturbance traveling through a medium disturbance traveling traveling through through a medium so what do you mean by a disturbance and what do we mean by a medium well we could come up with some fairly simple examples let's say that I have a let's have a little puddle here so that's my little puddle and let's say I were to drop a stone in that puddle so this is my stone it gets dropped in the puddle and we've all seen what happens right when it goes into the water that pushes that water down pushes the water around it out then that water comes back up and then you have this traveling disturbance you have this traveling disturbance these these kind of rings start to radiate outward from from where from where I actually from where I actually dropped dropped the pebble and you can actually see them you can actually see them move outwards you can see the crests of those waves move outwards so we're talking about a disturbance well this is that disturbance we the the pond was completely flat but then we agitated we pushed it down and push the water out words and then that pushed the water next to it up and down up and down and it traveled outwards from the point of that initial disturbance so we have this disturbance traveling through the medium what's the medium here well the medium here is the water and the disturbance the initial disturbance was the rock disturbing that water but then that water disturbed the water around it which disturbed the water around it so that disturbance kept traveling through the medium and we can give other examples of this if I take a let's say if I were to take a really long string and hold it right there and that's my hand so in the sting the string is let's say it's just attached to something so let's say it's a really long string and right now there's there's some slack in it it's attached to a wall and let's say that I were to start moving my hand up and down so I move my hand up and down what's going to happen well if I just did let's just think about if I just did it once if I just did it once what I'm going to have is this lump of string move from the left to the right so that's what it's going to look like at first then a few seconds later it's going to look like it's going to look like this it's going to look something like this and you're going to have this disturbance which is this this this wave this lump that I just generated it is going to move it is going to move to the right what's the medium the medium in this case is the string it is the string and what just happened there well when I jerk it when I jerk the string up I'm disturbing those string molecules right next to my hand and they're pulling on the string molecules next to them pulling on the string molecules next to them and so you then you have this travelling lump so once again these are both examples of waves disturbances traveling through through a medium now I can give other through a medium I can give other examples sound waves what caused the sound waves well you have a bunch of set you have a bunch of air particles all bouncing around it actually surprisingly fast surprisingly fast speeds but if you disturb them if you caused something to say compress a bunch of air particles right here so these air particles get ultra compressed some type of clap happens so these get ultra compressed well then they're going to bounce on the ones next to them and so once again you have this disturbance traveling through the medium in this case the medium is the air the medium is the air so now we've seen some classical notions of ways let's think about something a little bit more mysterious and that is the notion of light we do believe light has what light definitely has wave-like properties way light can interfere with each other and we could do a whole other videos on on light if I were to take if I were to take some if I were to take a barrier like that with too small Sinnott with two small slits in it and if I were to shine some light if I were to shine some light one way to think about is these slits are the only place where the disturbing the the disturbance gets through and then it would cause the light to propagate from each of them like that and maybe I'm just drawing the crests of the waves but it also come out from here and so you can see where the two crests where the two crests meet they're going to constructively constructively enhance each other they're going to constructively interfere and if you were to put some type of detector if you were to put some type of a detector right over here you would see you would see the bright points of the light and you would see the dark points of the light so light definitely behaves like a wave I'm just showing even just one example of light being a bit behaving like a wave but if it is a wave well that means it needs to be or if we use our classical logic you would say well that means it's a disturbance traveling through a medium but what is that medium you know we have light coming from our Sun we call it sunlight we have we have light coming I keep wanting to make it a actually our Sun is white we tend to draw it as a yellowish color but that's just because of its what happens as it goes through the atmosphere so you have the Sun you have the earth this is not drawn to scale and somehow that light is able to reach us over 93 million miles over 93 million miles what's it what's it going through is it a disturbance traveling through a medium well for a long time people said well it must be has these wave-like properties it's it's it seems to be traveling it with it with a velocity the speed of light so there must be a medium that it is traveling through and people theorize what this medium is they called it the luminiferous ether let me write that down it's a fun word it's a good name for a band luminiferous lumen lumen in I'm not spelling it Lou man if for us ether and it was this idea that maybe in even in the vacuum of space even in the vacuum of space you have this this substance this luminous luminiferous ether that the light is traveling through that it's somehow to disturb its a disturbance in that luminiferous luminiferous ether now what we're going to do in future videos is we're going to test that we're gonna see if that's actually the case because what's interesting about if there is a luminiferous ether well we're not going to be stationary relative to that luminiferous ether in fact we're orbiting we're orbiting around the Sun the Sun is orbiting around the center of the galaxy there's no way that we're going to be we're going to be stationary relative to that luminiferous ether so if we're not stationary relative to that luminiferous ether we should be able to detect how light behaves if it's going kind of in the direction of ether or if it's going against the direction of the relative movement of the ether relative to us so anyway I'll leave you there this mystery of science you know waves disturbance through a medium we saw that with the water with the air with the string but what about light is there a luminiferous ether but a question mark there