Is it correct to think that photons always try to move the photon and are always absorbed, but if their energy isn't correct they get re-emitted from the atom as the electron moves back to its original state? I don't see how a photon could check if it has the correct energy to excite the electron fully before deciding whether to be absorbed or carry on.
I'm still not perfectly sure what's going on. I understand the excited levels and energy gaps... But if the excited energy level is so high, why does it not just absorb more electrons... Shouldn't it be more EM dense? But low energy gaps would easily absorb the energy. So why isn't everything just opaque? Are photons just lazy and don't bother doing the heavy lifting if they know they're unable to? How can light be intelligent?
@SillyEddyPhotography It takes a lot of energy for electrons to jump energy levels. In fact, every successive energy level takes significantly more energy to get into. I am not sure why you thing energy levels absorb electrons but that's essentially it.
@Cabia2425 Microwaves can't go through a lot of things. Microwaves cannot go through lead or any of the heavier elements. In fact, that mesh you see in your microwave absorbs a lot of those microwaves.
@Cabia2425 Radiowaves are an even lower frequency (longer wavelength) than microwaves so they would be absorbed even more readily by elements. That's why if you went underground, the radio would not be clear and have lots of static. In contrast, gamma rays, which are the among the highest frequencies in the galaxy, go straight through the entire earth like it's no problem.
I think glass electrons get excited by photons and jump to higher orbitals but they soon return to their original orbitals, and while doing so they emit another photon in the right direction.
This also explains why light travels slower in glass. It is the delay introduced by that absorption and re-emission.
@strahd999 Indeed - thanks for your comment. There's a lot of physics (deliberately) left out in this video - I don't touch on reflection, refraction, or absorption/scattering at higher than visible energies. My aim was to put across the "zeroth order" effect behind why some materials transmit light and others block it: electron-photon interactions 'mediated' by the band structure of the solid in question.
Yeah this having enough energy explanation does not quite make sense.
Lets say if photons have enough energy to excite opaque object electrons and that is why they can't get through. With that logic x-rays do not have enough energy and they can go through opaque objects. This is absolutely wrong. Everyone knows x-rays have higher frequency, therefore, they have more energy.
@strahd999 Yes, but I'm specifically talking about visible light in the video! In that case there is a very well-defined threshold energy, set by the band gap of the solid, for the transmission of light. Below the band gap energy, photons do not excite cross-band-gap transitions. Google "Hyperphysics band theory".
At higher photon energies it's a question of photoabsorption cross-section and scattering - subjects, perhaps, for a completely separate video...
can somebody explain why the superconductor plate is orange to our eyes? Doesn't that mean that uv at the orange frequency is not passing through? The video made it seem that any frequency below the blue part of the spectrum had the correct energy to pass through the material. But what about orange?
I wish I had a physic teacher like you in middle school. I did nothing except reading the book the evening before the test and than just passed it. The classes were so demotivating boring xP but physics thought in such way is very interesting!
what i dont understand is that matter is mostly empty space - like lead is still mostly empty so surely photons wouldnt all get blocked by electron shells and absorbed
awesome clarification. Using this model what's the explanation for how gamma and xray radiation are able to pass through opaque materials with much more ease than, say, infrared or any visible wavelength? By this model those are both such high energy they should be able to excited far MORE electrons in far more materials than visible light and therefore more materials woudl be opaque to them.
How can some fotons have different amounts of energy if the speed of light is constant? I know they have different wavelengths but how can that make the fotons have a larger amount of energy?
@rsmvsblood energy doesn't relate to velocity when refering to quanta in the same way it does in massive objects like a car or train. The speed of the photon is fixed and the energy is proportional to the wavelength. look up planck's constant
@CiAnMaChInE if you don't understand - then the "explanation" is useless. if it doesn't even motivate you to explain it by yourself - then the "explanation" is rubbish.
omg i really really love this guy, i wish he was my teacher. But one question i have is when a photon does have enough energy to "excite" an electron what sort of thing is the result? does this have anything to do with some materials becoming brittle after being pounded by sun over long periods?
Aaah. And that's why ultra violet doesn't get through my window in the car (been told that is the case, but never understood why). UV light simply has too much energy to get through, it will indeed get those electrons up to next energy level. Funny. It's very backwards. The more energy you have, the smaller the chance of you getting through.
@Daedronus But that's a question of photoionisation cross-section and scattering. In the *visible* range, the key piece of physics is excitation across the band gap. This process has a threshold energy associated with it (namely, the band gap energy). Google "Hyperphysics band theory" for more information.
Note that, as I point out in a comment below, I leave out *a lot* of physics in this video (reflection, refraction...). Sixty Symbols videos are not designed to be complete tutorials.
@HKragh And taking it to the extreme here, what about gamma rays? I'd think that gamma ray photons (or whatever the correct term is) have enough energy to excite the electrons. Their energy would be absorbed and they wouldn't get through. Now I'm by no means very knowledgeable on the subject at all, but what if the gamma rays have so much energy that they can get through while still exciting electrons? Something UV and x-rays don't have enough energy to. Just thinking out loud here. :)
@Daedronus Yes,because E=hv, I don't know how to explain too, because I remember some glass is opaque to infra-red but transparent to visble light ...
Thanks! I was just wondering about it and you managed to make it clear (pun intended ;) ).
Now I just wonder: if an electron need a given amount of energy to be taken from one level to a next one, and a foton impact with more than that energy: can the electron still raise is energy level and the foton "survive" with the left energy (the difference)?
@martinsinnombre I believe that said photons have to be or, in fact, are of the same energy than the electrons that they excite.. this is pure assumption....
When the electron goes back to its original state it releases the energy to form a photon with a specific wavelength depending on the energy step it was in and the one it falls too.
When light is reflected it is because the emitted photons have exactly the same wavelength as the original photon..( might be wrong ), this is also why things are coloured and light heats objects. kinda explains why light slows down in substances as well.
they fall back down and release a photon in the process giving off light
i think this is the scattered light from an opaque object but the light given back off by falling electron will have a certain energy and so could give light off at a certain colour. not 100% but it kind of makes sense. so a white wall absorbs the photons and makes new photons in all colours, whereas a red wall absorbs photons and produces red photons (of the colour that the paint pigment chemical allows)
correct me, but i think your last explanations were mistakable. light does not travel through glass because it doesn't have enough energy, but because it doesn't have the exact right amount of energy (--> quantisation of energy). the way you explained it was mistakable, because it just explains why red light passes through red glass and blue light doesn't but not why blue light would pass through blue glass and red light wouldn't.
@LeifurEriksson But electrons in solids form *bands* of energy levels - they don't all (degenerately) reside in the same quantised levels one finds in the "parent" atom. Google "Hyperphysics energy bands" for more information.
@Moriarty2112 Good point, i didn't think of that. But still, a photon can have either too less (as you said) or too much (!) energy to get absorbed in a glass - that the exact amount of energy can vary is not that important. As i said, you explained very well, why blue light doesn't pass through red glass, but not every viewer will thereby be able to understand why red light can't pass through blue glass.
@LeifurEriksson Hi. The Sixty Symbols videos are not meant to be complete tutorials. I leave out huge amounts of physics in this video (reflection; refraction; adsorption due to defects; the fundamental origin of a band gap; the question of band structure in an amorphous solid such as glass..).
Our aim with Sixty Symbols is to address questions such as "Why is glass transparent" in as accessible a manner as possible. In < 10 mins we can't cover everything!
@Moriarty2112 Hey, thanks for this explanation. The visual with the balls reaching higher energy levels was helpful. If I might suggest a topic for another video, would you mind covering the physics behind how mirrors work? I watched Richard Feynman's Auckland University lecture on quantum electrodynamics where he explained the mathematics behind how reflective surfaces actually have a probability of reflecting in any direction, which may not always be the classical reflection angle.
@itsjareds Hi - thanks for the comment. Feynman's "QED: The Strange Theory of Light and Matter" is an excellent book that focuses on the partial reflection of glass and reflection in general. I'll see if Brady (the Sixty Symbols video maker) is interested in doing a video on reflection.
@TheAtheistFuture... exactly, for example Xrays! they are "light" too (electromagnetic waves) just not the wavelength we see, and they travel through lots of things.
I assume colored materials (for example, the red lense in those cheapo 3D glasses), are made of a material that just happens to only allow that color (red in this case) through, or allow colors around that range through easier, and block most of the rest? I mean, if you shine a light through a translucent and colored thing, it's going to "color" the light on the other side. But then, If you shine a light bright enough, it can sometimes seem to cut through completely...
So why is it that gamma rays and radio waves can get through some opaque substances even though they are on opposite ends of the electromagnetic spectrum with visible light in between?
@fb9ecd29081e0e3ab3b6 gamma waves are so incredibly small they can pass through a material without even touching any electrons, they just miss them completely. and radiowaves are so huge they just go around the object
@PompousPreacher So, you came onto a physics video to try to spread the good word? Science actually has a reason for glass being transparent besides the supernatural. Which the Prof. described in detail for us in the video.
Hmm ... I'm still a bit skeptical, Prof. Moriarty. The ions in glass are almost randomly arranged. Thus, there should be a wide range of electron energy levels that can be excited in the glass (due to the wide range of environments to which the ions are exposed). But glass is transparent from the infrared into the ultraviolet.
@dayne0987654321 The electron does gain the energy but doesn't get more massive. It uses a portion of the energy to be promoted from its ground state but thenvery quickly goes back to it, when it does this, it gives out the remainder of the energy in a particular wavelength. This demoting of electrons back to their ground state is therefore what gives anything colour.
@dadaniel2k11 good point! but also this would mean that those photons would be able to cross other materials with other levels of energy gaps. Maybe it's a way of creating vision to see through metal or beautifull women clothes.
what happens to the excited electrons afterwards? if they return to their original states, this means that they have to loose the energy gained from the photons, radiate away some photons themselves, right?
@kyle0106 In this case, there are no states between the ones he described. There may be additional states above that higher state, but none in between; you must have at least that minimum energy to kick an electron up. To your second question: yes; once you have enough energy, you cant help but kick electrons up into those states, so you get absorbed and die (that is, if you're a photon).
What about glass that allows blues and greens to filter through, but not reds? The bules and greens have a higher energy but are not absorbed. Could you say that only specific resonant energies are absorbed?
@TheErraticTheory going by what he said I'd say all of the electrons in the object have been moved to the excited area causeing a blockage and bouncing the left over light back
@TheErraticTheory maybe there are some electrons in an atom that have a low energy gap, like the inner ones, but the probability to a photon reach them is very small. Actually i'm not sure, maybe a photon cant reach an electron that isnt on valence level at all. An other possibility is that two or more photons collides with an electron at the same time, but i'm also not sure about that. Did you find the answer to your question? 'cause i'm also curious, thanks.
Could an electron with a very high wavelength be able to "promote" an electron AND also conserve enough energy to get through matter ? Is this why light can be "colored" by pieces of glass ?
Well it would have to be a lower wavelength ( = higher freqency = higher energy) but I think you'd find it would be outside of the visible range, and if it was that high frequency it would probably just knock the electron out of the atom.
You get coloured light from the impurities in the glass, the electrons in them absorb the light, get promoted to a higher level, then fall back down, giving off some light of a new wavelength, giving off coloured light.
@emmallica Oh, how I wish it were a beautiful Les Paul. It's a cheap (£100) copy with a B string that steadfastly refuses to stay in tune - microtonal bends knock it out of tune. (Actually, nanotonal bends would probably knock it out of tune!).
It's in the Sixty Symbols video on Fourier Analysis (along with a wah pedal....)
@pabloenis While I do believe in God, just saying that "God made it that way" to answer all mysteries is incredibly irresponsible, and would leave us with the technology of the stone age. There are physical, factual answers and reasons to everything, whether they're above our current understanding or not. A perfect being wouldn't allow inconsistencies.
@RSwtfboom God made the physical and factual answers and reasons to everything. God keeps down our current understanding. God can't be put on a scale from perfect to non-perfect, he's just God and he is awesome!
@pabloenis If God wants to keep our current understanding down and not allow us the free will to discover new things, why do we have the horrible parts of technology today such as nuclear weapons? If God was keeping us down and babying us, there'd be no point to life/afterlife. If there's an afterlife doesn't that mean that the normal life is just a prooving ground?
@pabloenis god didn't do anything, man did, including god, should read the bible and see he's not awesome at all, and i'd suggest refrain from this kind of crap in a science video.
So thankful for these videos and Periodic and all the rest. It's wonderful to learn about chemistry and physics in such a meaningful way. Wish I'd had interesting instructors like these through out my chem, physics and math classes at uni.
@kotofu remember how there are certain energy levels in an atom as explained? An electron will only 'move up' to an excited state if a certain photon of light has the exact energy needed to move it to a certain energy level. gamma rays have such a large amount of energy that the electrons in most atoms can't absorb it, so the gamma photons simply pass through. Infrared has a lower energy than visible light, therefore this photon energy can be absorbed by electrons in glass, hence it doesnt pass.
how do you explain the fact that infrared cannot pass through glass then? Infrared's photon must has an even lower amount of energy, thus why is infrared not passing through everything? Why is gamma, the one with the highest level of energy passing through EVERYTHING?
Nice video, can we have a video explaining why light moves slower through the glass? It has to interact with glass somehow regardless the lack of energy to excite the electrons to the next energy level. I've heard explanations that say the photons are constantly absorbed and retransmitted, but if absorption is impossible then what happens?
One question though, is it possible for all the electrons to go to a high energy level and if so, what happens then? do the electrons go back to the low energy level automatically in the form of heat or some other release of energy?
Oh I get it... No wait I don't.
FreeFromWar 12 hours ago
Photons man... they just cant get it up..
BossWolfen 19 hours ago
And what happens with the electrons after they get excited to the next level?
kberzok 1 day ago
i love how phil moriarty explains stuff , his rather clear for some1 who dont understand anything
REMOTiEify 1 day ago
omg, is he moriarity?
alfader1 1 day ago
lip syncing is way off
ADML101 2 days ago
don't know what got me here... but cool!
ForceCrystal 2 days ago
Professor Moriarty now thats a cool name
pietzeekoe 2 days ago
what happens to a mirror?
astroboomboy 2 days ago
Is it correct to think that photons always try to move the photon and are always absorbed, but if their energy isn't correct they get re-emitted from the atom as the electron moves back to its original state? I don't see how a photon could check if it has the correct energy to excite the electron fully before deciding whether to be absorbed or carry on.
JBroMCMXCI 2 days ago
3D graphics were invented for this exact reason. So grown men do not have to crawl around the office playing with balls.
CenarionCult 2 days ago
This has been flagged as spam show
@CenarionCult you're right - men learned to sit while they're playing with balls. evolution...
partonace 2 days ago
oh god that bookshelf is gonna blow. its more packed than the professor's desktop use to be.
AvoidDrunkDialing 2 days ago
I'm still not perfectly sure what's going on. I understand the excited levels and energy gaps... But if the excited energy level is so high, why does it not just absorb more electrons... Shouldn't it be more EM dense? But low energy gaps would easily absorb the energy. So why isn't everything just opaque? Are photons just lazy and don't bother doing the heavy lifting if they know they're unable to? How can light be intelligent?
SillyEddyPhotography 3 days ago
@SillyEddyPhotography It takes a lot of energy for electrons to jump energy levels. In fact, every successive energy level takes significantly more energy to get into. I am not sure why you thing energy levels absorb electrons but that's essentially it.
Hinduspy 2 days ago
Could you explain the specific materials of glass that would prevent photons to pass through? Or is all the explanation in the video itself?
Alyxm 4 days ago
OK, so is that why Microwaves can go through pretty much everything? Because it does not have enough energy to promote a electron?
Cabia2425 4 days ago
@Cabia2425 Microwaves can't go through a lot of things. Microwaves cannot go through lead or any of the heavier elements. In fact, that mesh you see in your microwave absorbs a lot of those microwaves.
Hinduspy 2 days ago
@Hinduspy then can radio waves do it?
Cabia2425 2 days ago
@Cabia2425 Radiowaves are an even lower frequency (longer wavelength) than microwaves so they would be absorbed even more readily by elements. That's why if you went underground, the radio would not be clear and have lots of static. In contrast, gamma rays, which are the among the highest frequencies in the galaxy, go straight through the entire earth like it's no problem.
Hinduspy 1 day ago
@Hinduspy very interesting, thanks for the explanation!
Cabia2425 1 day ago
I think glass electrons get excited by photons and jump to higher orbitals but they soon return to their original orbitals, and while doing so they emit another photon in the right direction.
This also explains why light travels slower in glass. It is the delay introduced by that absorption and re-emission.
strahd999 4 days ago
@strahd999 Indeed - thanks for your comment. There's a lot of physics (deliberately) left out in this video - I don't touch on reflection, refraction, or absorption/scattering at higher than visible energies. My aim was to put across the "zeroth order" effect behind why some materials transmit light and others block it: electron-photon interactions 'mediated' by the band structure of the solid in question.
Best wishes,
Philip
Moriarty2112 4 days ago
Yeah this having enough energy explanation does not quite make sense.
Lets say if photons have enough energy to excite opaque object electrons and that is why they can't get through. With that logic x-rays do not have enough energy and they can go through opaque objects. This is absolutely wrong. Everyone knows x-rays have higher frequency, therefore, they have more energy.
strahd999 4 days ago
@strahd999 Yes, but I'm specifically talking about visible light in the video! In that case there is a very well-defined threshold energy, set by the band gap of the solid, for the transmission of light. Below the band gap energy, photons do not excite cross-band-gap transitions. Google "Hyperphysics band theory".
At higher photon energies it's a question of photoabsorption cross-section and scattering - subjects, perhaps, for a completely separate video...
Philip (speaking in video)
Moriarty2112 4 days ago
@Moriarty2112 Thank you Dr. Moriarty for your reply.
strahd999 2 days ago
thx for uploading. I didnt know this before
GahSoonChan 5 days ago
can somebody explain why the superconductor plate is orange to our eyes? Doesn't that mean that uv at the orange frequency is not passing through? The video made it seem that any frequency below the blue part of the spectrum had the correct energy to pass through the material. But what about orange?
FearMonstro 6 days ago
so does glass block ultraviolet light?
Diosukekun 6 days ago
@Diosukekun yes, that's why dslr cameras use "uv" filters which are infact only glass
numex106 6 days ago
I wish I had a physic teacher like you in middle school. I did nothing except reading the book the evening before the test and than just passed it. The classes were so demotivating boring xP but physics thought in such way is very interesting!
cheesandpinuts 1 week ago
what i dont understand is that matter is mostly empty space - like lead is still mostly empty so surely photons wouldnt all get blocked by electron shells and absorbed
spaceghost1313 1 week ago
ok so is there any to make it harder or easier for light to move an eletron
xITSDUCKYx 1 week ago
We've a monochromator, but it's all rusty and the calibration is off by 50nm... if you sneeze on it, it picks up an extra +-5nm -_-
IsaacRemnant 1 week ago in playlist Uploaded videos
is this guy Scottish or Jamaican? look at his electrons; Jamaican colors, mon!
kowalityjesus 1 week ago
awesome clarification. Using this model what's the explanation for how gamma and xray radiation are able to pass through opaque materials with much more ease than, say, infrared or any visible wavelength? By this model those are both such high energy they should be able to excited far MORE electrons in far more materials than visible light and therefore more materials woudl be opaque to them.
SpenserF 1 week ago 2
i love how he gets really excited speaking about how the foton dies... :/
NiamOfAsuras 1 week ago
How can some fotons have different amounts of energy if the speed of light is constant? I know they have different wavelengths but how can that make the fotons have a larger amount of energy?
rsmvsblood 1 week ago
@rsmvsblood energy doesn't relate to velocity when refering to quanta in the same way it does in massive objects like a car or train. The speed of the photon is fixed and the energy is proportional to the wavelength. look up planck's constant
SpenserF 1 week ago
Comment removed
PieEaterV2 1 week ago
I wish you'd given him the 10 minutes...
PieEaterV2 1 week ago
@PieEaterV2 lol. seriously
PaDoCoKeFo 1 week ago in playlist Brain Candy
I wish you'd given him the 10 minutes...
PieEaterV2 1 week ago
Dick Tits.
Pwnage195 1 week ago in playlist Brain Candy
I dont understand any of these things but u still enjoy watching them :P
CiAnMaChInE 1 week ago in playlist Brain Candy 16
@CiAnMaChInE ahahahah me too! I wish I was good at science/ Wish i had a good science teacher!
TheJasmineee 1 week ago
This has been flagged as spam show
@CiAnMaChInE if you don't understand - then the "explanation" is useless. if it doesn't even motivate you to explain it by yourself - then the "explanation" is rubbish.
partonace 2 days ago
@CiAnMaChInE I just pressed mute and enjoyed watching him dancing around the room with colored balls.
AreaQNH870 1 day ago
The glass as a liquid thing was something my school taught...
danrulz98 1 week ago
what happens if two or more photons hit the electron?
TheInfiniteQuestions 1 week ago
Prof Moriarty is sooo very handsome :) And his accent! Perfect!
adunakhyr 1 week ago
I like when he says through...
TheRemingtonChase 1 week ago
Give the man his 10 minutes!
xxmtgxx 1 week ago
omg i really really love this guy, i wish he was my teacher. But one question i have is when a photon does have enough energy to "excite" an electron what sort of thing is the result? does this have anything to do with some materials becoming brittle after being pounded by sun over long periods?
chocolaterainlololo 2 weeks ago
Aaah. And that's why ultra violet doesn't get through my window in the car (been told that is the case, but never understood why). UV light simply has too much energy to get through, it will indeed get those electrons up to next energy level. Funny. It's very backwards. The more energy you have, the smaller the chance of you getting through.
HKragh 2 weeks ago
so if we heat the glas, light can't shine through it? :S
SulaFreaks 2 weeks ago
so if we find out how to change the height of the adoms... we can make X-RAY GLASSES
gizmorage 2 weeks ago in playlist Brain Candy
i'm studiing quantum physics for the moment and just saw that last week :D
But where is the electron between the two levels of energy?...
alexandre220011 2 weeks ago
I don't think it's about having "enough" energy to excite a electron.
I think it's about having the correct energy.
For example glass is transparent to visible light, opaque to deep UV and then again transparent to x-rays (all 3 are photons of increasing energy).
Daedronus 2 weeks ago 31
@Daedronus But that's a question of photoionisation cross-section and scattering. In the *visible* range, the key piece of physics is excitation across the band gap. This process has a threshold energy associated with it (namely, the band gap energy). Google "Hyperphysics band theory" for more information.
Note that, as I point out in a comment below, I leave out *a lot* of physics in this video (reflection, refraction...). Sixty Symbols videos are not designed to be complete tutorials.
Moriarty2112 2 weeks ago
@Daedronus I just read somewhere else, that glass is indeed opaque to x-rays. So much confusing info on the matter. Who to trust :)
HKragh 2 weeks ago
@HKragh And taking it to the extreme here, what about gamma rays? I'd think that gamma ray photons (or whatever the correct term is) have enough energy to excite the electrons. Their energy would be absorbed and they wouldn't get through. Now I'm by no means very knowledgeable on the subject at all, but what if the gamma rays have so much energy that they can get through while still exciting electrons? Something UV and x-rays don't have enough energy to. Just thinking out loud here. :)
DannyNHansen 2 weeks ago
@Daedronus I've been thinking the same thing...
murdakah 1 week ago
@Daedronus You sure about that? Light is visible radiation and the photon is the quanta of light. UV and X-Rays are not visible ... are they?
adamx20 1 week ago
@Daedronus you know what, nevermind. I forgot EMR.
adamx20 1 week ago
@Daedronus transparency to us is based purely on the visible spectrum so w.r.t. that... it is about having enough energy or not...
PinkCammy 1 week ago
@Daedronus Yes,because E=hv, I don't know how to explain too, because I remember some glass is opaque to infra-red but transparent to visble light ...
Can anyone help?
GuaidaoKID 1 day ago in playlist Brain Candy
@Daedronus
Thanks! I was just wondering about it and you managed to make it clear (pun intended ;) ).
Now I just wonder: if an electron need a given amount of energy to be taken from one level to a next one, and a foton impact with more than that energy: can the electron still raise is energy level and the foton "survive" with the left energy (the difference)?
martinsinnombre 1 day ago
@martinsinnombre I believe that said photons have to be or, in fact, are of the same energy than the electrons that they excite.. this is pure assumption....
kberzok 1 day ago
that so cool!
ILikeWeatherGuy 2 weeks ago
@ TheErraticTheory.
When the electron goes back to its original state it releases the energy to form a photon with a specific wavelength depending on the energy step it was in and the one it falls too.
When light is reflected it is because the emitted photons have exactly the same wavelength as the original photon..( might be wrong ), this is also why things are coloured and light heats objects. kinda explains why light slows down in substances as well.
MrJooog 2 weeks ago
dick titts trololololol (1:23)
Emselone 2 weeks ago
Comment removed
Emselone 2 weeks ago
So what happened to the excited electrons? Are they staying excited forever?
ToastySun 2 weeks ago
they fall back down and release a photon in the process giving off light
i think this is the scattered light from an opaque object but the light given back off by falling electron will have a certain energy and so could give light off at a certain colour. not 100% but it kind of makes sense. so a white wall absorbs the photons and makes new photons in all colours, whereas a red wall absorbs photons and produces red photons (of the colour that the paint pigment chemical allows)
TechState 2 weeks ago
what happens to the absorbed energi
PremiumZero 2 weeks ago
@PremiumZero I think it heats up the glass.
ashwinnarayanVlog 2 weeks ago
correct me, but i think your last explanations were mistakable. light does not travel through glass because it doesn't have enough energy, but because it doesn't have the exact right amount of energy (--> quantisation of energy). the way you explained it was mistakable, because it just explains why red light passes through red glass and blue light doesn't but not why blue light would pass through blue glass and red light wouldn't.
LeifurEriksson 2 weeks ago in playlist Brain Candy
@LeifurEriksson But electrons in solids form *bands* of energy levels - they don't all (degenerately) reside in the same quantised levels one finds in the "parent" atom. Google "Hyperphysics energy bands" for more information.
Best wishes,
Philip (speaking in video)
Moriarty2112 2 weeks ago
@Moriarty2112 Good point, i didn't think of that. But still, a photon can have either too less (as you said) or too much (!) energy to get absorbed in a glass - that the exact amount of energy can vary is not that important. As i said, you explained very well, why blue light doesn't pass through red glass, but not every viewer will thereby be able to understand why red light can't pass through blue glass.
LeifurEriksson 2 weeks ago in playlist Brain Candy
@LeifurEriksson Hi. The Sixty Symbols videos are not meant to be complete tutorials. I leave out huge amounts of physics in this video (reflection; refraction; adsorption due to defects; the fundamental origin of a band gap; the question of band structure in an amorphous solid such as glass..).
Our aim with Sixty Symbols is to address questions such as "Why is glass transparent" in as accessible a manner as possible. In < 10 mins we can't cover everything!
All the best,
Philip
Moriarty2112 2 weeks ago
@Moriarty2112 Hey, thanks for this explanation. The visual with the balls reaching higher energy levels was helpful. If I might suggest a topic for another video, would you mind covering the physics behind how mirrors work? I watched Richard Feynman's Auckland University lecture on quantum electrodynamics where he explained the mathematics behind how reflective surfaces actually have a probability of reflecting in any direction, which may not always be the classical reflection angle.
Thanks!
itsjareds 2 weeks ago
@itsjareds Hi - thanks for the comment. Feynman's "QED: The Strange Theory of Light and Matter" is an excellent book that focuses on the partial reflection of glass and reflection in general. I'll see if Brady (the Sixty Symbols video maker) is interested in doing a video on reflection.
All the best,
Philip
Moriarty2112 2 weeks ago
So, if we could see non visible light that wasn't absorbed by brick, we could see through walls?
TheAtheistFuture 2 weeks ago
@TheAtheistFuture... exactly, for example Xrays! they are "light" too (electromagnetic waves) just not the wavelength we see, and they travel through lots of things.
TechState 2 weeks ago
@TechState Cool
TheAtheistFuture 2 weeks ago
How is it that it cannot be in the space between energy levels. I thought that was a problem with Bohrs theory?
guitarandrums 2 weeks ago in playlist Brain Candy
It's a network solid.
guitarandrums 2 weeks ago in playlist Brain Candy
he's james moriarty's son!
bodna03 2 weeks ago
:P
alchemic85 2 weeks ago
I assume colored materials (for example, the red lense in those cheapo 3D glasses), are made of a material that just happens to only allow that color (red in this case) through, or allow colors around that range through easier, and block most of the rest? I mean, if you shine a light through a translucent and colored thing, it's going to "color" the light on the other side. But then, If you shine a light bright enough, it can sometimes seem to cut through completely...
I'm a little confused.
alecjahn 2 weeks ago
what about the photons that can't pass trew?
brendendw 2 weeks ago in playlist Brain Candy
So why is it that gamma rays and radio waves can get through some opaque substances even though they are on opposite ends of the electromagnetic spectrum with visible light in between?
fb9ecd29081e0e3ab3b6 2 weeks ago
@fb9ecd29081e0e3ab3b6 gamma waves are so incredibly small they can pass through a material without even touching any electrons, they just miss them completely. and radiowaves are so huge they just go around the object
ReturnOfTheBone 2 weeks ago
Why is glass transparent? Simple. God did it. Who are we to question God? Mystery solved!!!
PompousPreacher 2 weeks ago
@PompousPreacher So, you came onto a physics video to try to spread the good word? Science actually has a reason for glass being transparent besides the supernatural. Which the Prof. described in detail for us in the video.
MrSuednym 2 weeks ago
Comment removed
PompousPreacher 2 weeks ago
@PompousPreacher I don't believe in glass.
Abramisen 2 weeks ago
i feel so ashamed of having an unintelligable comment as the top rated one, who watches these videos?
Rannyfash 2 weeks ago
Hmm ... I'm still a bit skeptical, Prof. Moriarty. The ions in glass are almost randomly arranged. Thus, there should be a wide range of electron energy levels that can be excited in the glass (due to the wide range of environments to which the ions are exposed). But glass is transparent from the infrared into the ultraviolet.
KevinByrne2 2 weeks ago
I'll never look at windows the same. O_o
metaldorksforever666 3 weeks ago
@metaldorksforever666 through* :P
XavierCrow 2 weeks ago
@XavierCrow I'm not looking through them always, sometimes just at them (I'm awesome like that).
metaldorksforever666 2 weeks ago
@metaldorksforever666 XD Show me your ways. I will follow you!
XavierCrow 2 weeks ago
Soooo..... we can meassure the energy levels through the colour of the material?
DarkMind95 3 weeks ago
I donno why but at because of his accent at 0:46 I wanted him to say "you get complete rubbish"
TheCyphen 3 weeks ago in playlist Brain Candy
if a photon is absorbed by an electron, does the electron not gain energy thus becoming more massive as well?
dayne0987654321 3 weeks ago
@dayne0987654321 The electron does gain the energy but doesn't get more massive. It uses a portion of the energy to be promoted from its ground state but thenvery quickly goes back to it, when it does this, it gives out the remainder of the energy in a particular wavelength. This demoting of electrons back to their ground state is therefore what gives anything colour.
MrCliffybiro 3 weeks ago
@MrCliffybiro ohhh, that makes more sense, thanks for clearing that up for me
dayne0987654321 2 weeks ago
so if the photon would have more power the glass wouldnt be transparent anymore? o.O
dadaniel2k11 3 weeks ago in playlist Brain Candy
@dadaniel2k11 good point! but also this would mean that those photons would be able to cross other materials with other levels of energy gaps. Maybe it's a way of creating vision to see through metal or beautifull women clothes.
supelis 3 weeks ago
what happens to the excited electrons afterwards? if they return to their original states, this means that they have to loose the energy gained from the photons, radiate away some photons themselves, right?
ktoksoz 3 weeks ago
Is there really a University where I can go and be taught by Professor Moriarty? Special subjects, experimental physics and world domination.
chromebul 3 weeks ago
is this also the reason why we see materials that have different colours?
B2theYBroWny 3 weeks ago
So does glass have the energy levels in between the ground (lower) and the roof (higher)?
Or is it just those two?
And so the second part explained that if you do have enough energy then the light doesn't get through?
kyle0106 3 weeks ago
@kyle0106 In this case, there are no states between the ones he described. There may be additional states above that higher state, but none in between; you must have at least that minimum energy to kick an electron up. To your second question: yes; once you have enough energy, you cant help but kick electrons up into those states, so you get absorbed and die (that is, if you're a photon).
alextheape 3 weeks ago
why is there a Sociology textbook on his shelf?
turkishdisco2 3 weeks ago
What about glass that allows blues and greens to filter through, but not reds? The bules and greens have a higher energy but are not absorbed. Could you say that only specific resonant energies are absorbed?
CHAS1422 3 weeks ago
The light is getting true.
inj3cti0n 3 weeks ago
what about the reflected light?
TheErraticTheory 3 weeks ago 20
@TheErraticTheory going by what he said I'd say all of the electrons in the object have been moved to the excited area causeing a blockage and bouncing the left over light back
browndyke 2 weeks ago
@TheErraticTheory maybe there are some electrons in an atom that have a low energy gap, like the inner ones, but the probability to a photon reach them is very small. Actually i'm not sure, maybe a photon cant reach an electron that isnt on valence level at all. An other possibility is that two or more photons collides with an electron at the same time, but i'm also not sure about that. Did you find the answer to your question? 'cause i'm also curious, thanks.
TheInfiniteQuestions 1 week ago
Glass is transparent because it's glass.
zimtower 3 weeks ago
Why is glass transparent?
Because you touch yourself at night!
puolalainen44 4 weeks ago
@puolalainen44 No, it's a punishment from God for the existence of gays.
PompousPreacher 2 weeks ago
@PompousPreacher You're going to hell for this blasphemy. And for touching yourself at night.
puolalainen44 2 weeks ago
Is the foton light?
resworp 4 weeks ago
@resworp A "photon" is a particle of light.
MorphinMan33 4 weeks ago in playlist Brain Candy
Could an electron with a very high wavelength be able to "promote" an electron AND also conserve enough energy to get through matter ? Is this why light can be "colored" by pieces of glass ?
ZeJ0K3R95 4 weeks ago in playlist Liked videos
@ZeJ0K3R95
Well it would have to be a lower wavelength ( = higher freqency = higher energy) but I think you'd find it would be outside of the visible range, and if it was that high frequency it would probably just knock the electron out of the atom.
You get coloured light from the impurities in the glass, the electrons in them absorb the light, get promoted to a higher level, then fall back down, giving off some light of a new wavelength, giving off coloured light.
fightthepurple 4 weeks ago
@fightthepurple Oops, I forgot that lower wavelentgh = higher energy :(. But anyway, thanks for your answer.
ZeJ0K3R95 3 weeks ago
Listen to the man, he has a beard.
AirborneB6 1 month ago in playlist Brain Candy
WHY DO YOU TREAT THAT BEAUTIFUL WHITE LES PAUL STUDIO IN THE BACK SO BADLY, PUT IT IN ITS CASE! GREAT EXPLANATION
emmallica 1 month ago in playlist Brain Candy
@emmallica Oh, how I wish it were a beautiful Les Paul. It's a cheap (£100) copy with a B string that steadfastly refuses to stay in tune - microtonal bends knock it out of tune. (Actually, nanotonal bends would probably knock it out of tune!).
It's in the Sixty Symbols video on Fourier Analysis (along with a wah pedal....)
All the very best,
Philip
Moriarty2112 1 month ago
I'm so happy to be able to understand this :D
darkilustrisimus 1 month ago 47
Watching this makes me realise how stupid I am, I should probably take some time to learn about science.
ItzDan3055 1 month ago
4:23. thats how tony stark made his new ark reactor
DATWEIRDGUY1 1 month ago in playlist Brain Candy
Well, this is all nice...but how do magnets work?
Clearly some magic must be involved when examined carefully.
immortalis1001 1 month ago
You forgot to mention that god made it that way. God makes also electrons and light. God can travel faster than light! :)
pabloenis 1 month ago
@pabloenis neutrinos can too!
SoMuchWin19 1 month ago
@pabloenis This is no place for religion so GTFO.
TheBmr12626 1 month ago in playlist Brain Candy
@TheBmr12626 And trolling? ;)
pabloenis 4 weeks ago
@pabloenis Nope.
TheBmr12626 4 weeks ago
@pabloenis While I do believe in God, just saying that "God made it that way" to answer all mysteries is incredibly irresponsible, and would leave us with the technology of the stone age. There are physical, factual answers and reasons to everything, whether they're above our current understanding or not. A perfect being wouldn't allow inconsistencies.
RSwtfboom 1 month ago
@RSwtfboom God made the physical and factual answers and reasons to everything. God keeps down our current understanding. God can't be put on a scale from perfect to non-perfect, he's just God and he is awesome!
pabloenis 4 weeks ago
@pabloenis but.... god didn't make glass... man did.
Buddyb309 4 weeks ago
@pabloenis If God wants to keep our current understanding down and not allow us the free will to discover new things, why do we have the horrible parts of technology today such as nuclear weapons? If God was keeping us down and babying us, there'd be no point to life/afterlife. If there's an afterlife doesn't that mean that the normal life is just a prooving ground?
RSwtfboom 4 weeks ago
@pabloenis god didn't do anything, man did, including god, should read the bible and see he's not awesome at all, and i'd suggest refrain from this kind of crap in a science video.
linkuei83 3 weeks ago
@pabloenis Are you serious or just trolling? Stop talking about philosophical concepts in a video dedicated to science.
ZeJ0K3R95 4 weeks ago
@ZeJ0K3R95 problem? :D
pabloenis 4 weeks ago
@pabloenis Yep, that's what I was thinking...
ZeJ0K3R95 4 weeks ago
Prof. Moriarty?! Hmm, Call mister Holmes.
mynameismatt2010 1 month ago 2
So thankful for these videos and Periodic and all the rest. It's wonderful to learn about chemistry and physics in such a meaningful way. Wish I'd had interesting instructors like these through out my chem, physics and math classes at uni.
DrBones666 1 month ago
Has this got to do with the waveength and frequency?
Which means that high energy protons has higher frequency in the wave but ones with longer waves lengths has less energy?
ppoem123 1 month ago in playlist Brain Candy
@ppoem123
Yes,
short wavelength = high frequency = high photon energy
long wavelength = low frequency = low photon energy
johnmartins 1 month ago
Photon coming out through glass: "The energy gaps were Too Damn High!"
MurkMenthaa 1 month ago
@kotofu remember how there are certain energy levels in an atom as explained? An electron will only 'move up' to an excited state if a certain photon of light has the exact energy needed to move it to a certain energy level. gamma rays have such a large amount of energy that the electrons in most atoms can't absorb it, so the gamma photons simply pass through. Infrared has a lower energy than visible light, therefore this photon energy can be absorbed by electrons in glass, hence it doesnt pass.
Filoboi123 1 month ago
how do you explain the fact that infrared cannot pass through glass then? Infrared's photon must has an even lower amount of energy, thus why is infrared not passing through everything? Why is gamma, the one with the highest level of energy passing through EVERYTHING?
kotofu 1 month ago
Nice video, can we have a video explaining why light moves slower through the glass? It has to interact with glass somehow regardless the lack of energy to excite the electrons to the next energy level. I've heard explanations that say the photons are constantly absorbed and retransmitted, but if absorption is impossible then what happens?
upisoft2 1 month ago
Moriarty? Like Colin Moriarty? I hated that guy (Colin, not the Prof).
MrMLabi 1 month ago
@MrMLabi Ah, perhaps it's that arch idiot and sidekick to Hercules Grytpype Thynne, Count Jim Moriarty?
wordreet 1 month ago
is this how 3d glasses work (i mean the new ones not the red/blue etc) if not you guys should do one on how it exactly it works because its amazeing.
coldlogic1 1 month ago
Whaaaaaaaaaaaaat????
999Seriously 1 month ago in playlist Brain Candy
OMG That is an AMAZING Irish accent
Thatguy7109 1 month ago in playlist Brain Candy
TL; DR
When it comes to glass, photons can't get it up.
Plecter 1 month ago in playlist Brain Candy
soo, a really brigth light makes glass opaque
GuyPlusStuff 1 month ago in playlist Brain Candy
he simply cant get it up
Rannyfash 1 month ago 60
@Rannyfash zing!
brodiebalonie 3 weeks ago in playlist Brain Candy
Love how he had to hold up the glass when he's wearing glasses.
What color would glass be if it weren't transparent?
Leadman1989 1 month ago in playlist Brain Candy
One question though, is it possible for all the electrons to go to a high energy level and if so, what happens then? do the electrons go back to the low energy level automatically in the form of heat or some other release of energy?
DutchDread 1 month ago in playlist Brain Candy