[Music] it'sing youring your prise to live please do it for me my name is violet I was born into a world you may not understand ultraviolet now I'm sure that when we say ultraviolet catastrophe that's exactly what most people are thinking of the very disastrous um movie from 2006 but when a scientist talks about ultraviolet catastrophe we're actually talking about a phenomenon that was observed from Real World data we've all seen what happens when you heat a piece of iron when you heat a piece of piece of iron it begins to glow red hot well it turns out as you heat an object the color changes the hotter it gets the higher the frequency of the admitted radiation and based on this as you increased temperature that frequency should go higher and higher until at the temperature that the Universe to the temperature of stars in the universe at which point at the temperature at which stars operate in the universe we should see the universe being flooded at those star temperatures not by visible light or infrared radiation but by ultraviolet if there is a direct Rel L linear relationship between temperature and frequency then at the temperature at which stars which are all over the Galaxy operate at they should be pumping out tons and tons of UV radiation so much U UV radiation that Life as we know it couldn't exist well Life as We Know It exists o we could have a really interesting philosophical discussion there if you really want to think about it go down some really dark neist paths there but at any rate assuming that Life as we know it in the universe does in fact exist how can we explain that Well turns out when we actually plot the raw data of temperature versus frequency what we see is we see a pullup instead of a continual linear build the problem with that is physicists couldn't explain it they couldn't explain why the relationship wasn't a linear one they couldn't explain why they saw this curve up that prevented an UltraViolet catastrophe a man named Maxwell plank came along and Maxwell plank decided that he would take this data and he would not really worry about explaining it he would mathematically fit the curve he would come up with the equation that matched the curve he was seeing between frequency and energy and he would make the mathematical equation fit as a curve by making a very interesting assumption he assumed that in instead of energy being infinitely divisible meaning you can always divide it one more time into a smaller quantity he assumed that energy must have a certain minimum size and when he assumed that energy must have a certain minimum size and then forced a mathematical formula to fit the curve or or came up with a math maical formula that fit the curve what he discovered was a relationship between energy and frequency where the frequency of light was equal to where the frequency of light and Hertz was equal to the energy of the light in Jewels times a constant and he said that that constant was 6626 * 10 to the 34 jewles per second so at this point he had a constant and he had mathematically solved the piece of experimental data by making a really big assumption that there was a minimum quantity of energy in existence however he couldn't find additional experimental proof or even explain why in the face of the universe energy had a minimum minimum quantity I mean why why in the world was there a minimum quantity of energy that's where a very famous patent clerk stepped in and helped them out but before we talk about the patent clerk why don't you write down Selma Blair well this famous patent clerk was of course Albert Einstein and he was working with another scientific phenomenon known as the photoelectric effect the photoelectric effect was an experiment where a piece of metal had a light shined on it and at low energy light nothing would happen when you shined low energy light on your piece of metal nothing happened however when you got to a certain minimum frequency what you observed when you got to a certain minimum frequency is that an electron would be ejected from the metal metal not only that but as you increased the frequency went farther through Roy G Biv here the electron would be ejected and it would move faster so based on this photoelectric effect there was no electron ejected when the low energy light was shined on it but as you shined a higher energy light on it the electron was ejected well Einstein said let's play around with my low energy light What If instead of just hitting it with a small amount of low energy light I go out to Gotham City and I get the bat signal everybody write down bat signal I get the bat signal on there I shine that big old spotlight on my piece of metal so I'm shining a lot or a high intensity low frequency light on my metal so I'm hitting it with a ton of light even when he did that no electron was ejected from the metal why because the frequency was too low so in intensity didn't seem to affect the eject ejecting of an electron all right Einstein decided to try something else with these high energies my greens and my purples here with these high energy lights the electron was ejected immediately right when the light struck the metal so Einstein said what if I take my low frequency Right light and I leave it on for hours at a time if I leave my low frequency light on for hours at a time does it eject an electron no turns out if the if you used a low frequency light even shining it on for hours didn't eject an electron so Einstein came up with a very important conclusion he concluded that light must not be a wave as people thought at the time but light must be a particle how does light being a particle explain this photoelectric effect it's like playing pool I have my pool ball here and in order to move that pool ball I have to hit it with a Q ball if I just tap my Q ball and it bumps into my red ball my red ball doesn't move right you have to hit the white ball in in pool hard enough with enough energy to actually move my red ball and that's what Einstein said was going on with the photoelectric effect that these light Photon that these light that light was functioning like a qall it was a bunch of little particles that were slamming into that Q ball and at these low energy lights your Q ball wasn't moving with enough energy to move the pool ball at these high energy lights these high frequency lights your qall was hitting it with a stronger Force hitting it with a high amount of energy the particle theory also explained the spotlight effect under with a low energy Spotlight instead of hitting it with a Q ball you're throwing a bunch of peas at it seriously get a handful of frozen peas and throw them at a pool ball and see if the pool ball moves it's not going to move right the little peas don't have enough energy even if you throw them really hard or even if you stood there and threw them all day long matter fact get a huge bag of dried peas and sit there and throw it at a pool ball for a couple hours that pool ball still won't move those pe's don't have enough enough energy so we can see just from playing pool and the photoelectric effects that light must be a particle not only that but the energy possessed by this particle of light must be explained by Plank's equation so our conclusions light must not only be able to be modeled as a wave but it must also be able to be modeled as a particle we refer to a particle of light as a photon the energy associated with one photon is called a Quantum of energy the energy of one photon is equal to Plank's constant time times the frequency of the photon you need to memorize ah I know I said it wash my mouth out with soap I'm so sorry but you need to memorize that constant you go to work at some location such as Google and Microsoft both of those company G companies give their incoming Engineers exams before they can get hired and if you ask for planks constant on that exam I guarantee you they going to take your paper and shred it up and say we know all we need to so you need to memorize that constant now if you have more than one Photon as and you have n photons then your energy is going to be equal to your number of photons times Plank's constant times your frequency and my guess is I'm nearly at my 10-minute limit so I going to stop and then on the next video we'll work some examples