wait a minute. when the electron of a given atom absorbs a photon and the atom goes to an exited state it gains energy. how can you be cooling down the gas if you continuously ADD energy to it's atoms? Are these atoms all ending up at higher and higher states as they are cooled?
The photon energy is actually lower than is necessary to excite the atoms electrons, but when the atoms are moving towards the photon source the doppler effect causes the atoms electrons to essentially be fooled into being exciting. The atoms slow down 3:40. To be honest I'm not an expert either.
@anonymousbl00dlust The wavelengths supplied to the atoms are not used to excite the electrons. The atoms re-emits the photon which causes the atom to gain the momentum from the photon. If the momentum is against the original direction the atom is heading, it will slow it down.
@elflordbob1 Why would that be? I would imagine converting energy into matter would only occur at very high energies, even if it's an unknown form of matter. Though I suppose dark matter particles could be of very low mass...
A wonderful explanation of laser cooling. A suggestion that I have would be "Just what is a Bose-Einstein condensate, and how does having atoms violating the Pauli Exclusion Principle affect the behavior of matter. Don't let him get too rusty on the details, Brady! :D
so you shoot a photon that has a certain amount of energy into another moving particle that has energy and and the resulting energy is less because the energy difference is stored in the particle itself by exciting an electron? is that correct? if not where does the energy go? and isnt the particle eventually going to go back into its ground state and emit a photon and thus start moving again? i hope i can get some answers! thanks for the great videos!! keep it up!!
@bmbirdsong v=0 is just the vibrational quantum number. This isn't equal to T=0 or absolute zero. The reasons behind this are pretty complex, but it's due to anharmonic properties of molecular vibrations and fun things like that. Wikipedia is your friend on this. :)
If absolute zero is the absence of molecular motion, is there a corresponding opposite temperature? A point beyond which you can no longer add heat to a system? Would that be the temperature of gas molecules moving at the speed of light?
@bmbirdsong There's no such thing as an 'absence of molecular motion'. Molecules will still possess a zero-point energy, and can never reach absolute zero. On the other hand vibrational energy levels go from v=0 to v=∞, so there is no maximum temperature. Or put another way, to get something to the speed of light would require infinite energy. Thus unless you can get to ∞°C you won't get an atom/electron or any particle with mass to the speed of light.
Oh WOW!! I've wondered for so long how they get stuff into such tiny temperatures. and YES i did think laser alway heated up or burned up stuff :D Thanks for clearing the misconception.
I'm curious how the laser is being tuned and over what bandwidth, since I know precisely tuning them over large bands is difficult if it's not a dye laser - and they're messy. :P
I have also heard a new form of magnetometer has been developed using laser sensing of ?rubidium? clouds that is close to the SQUID. MIT have produced a TEC like element from superconductors that can reach extremely low temperatures by exploiting conduction barriers. That plus a SQUID = hand held heart / brain scanner?
Just subscribed today and already learned something I've wanted to know. How they cool with lasers. Of course I could have googled it but for some reason never did.
OK, so you reduce the momentum of the atom by hitting it with a photon, and drive the electron into a higher energy state. I presume then the electron then drops back releasing a photon that doesn't get absorbed. Otherwise you're just pumping energy in. No way will you cool it. I would have thought the new photon was exactly the right wave length to get absorbed. I don't understand.
The photon is absorbed by the atom and an electron goes to an excited state. The electron goes back to the ground state and a photon is emitted isotropically, that is all directions of emission are equally probable. On the average (the photon can be emitted in any direction) the atom loses momentum, and also a bit of its kinetic energy is taken away by the photon. Repeat the process ten thousand times and the atom slows down and nearly stops. A Nobel prize results for this idea.
That seems unlikely. You need a gas or at least a liquid for this to work. On a CPU, which is opaque, you could at best shoot lasers on it from the top etc., but not from all directions, and the laser wouldn't reach into the CPU very far (or at all).
i understand the mechanics of laser cooling, it's very interesting.
but i don't understand it thermodynamically. I find it hard to wrap my brain around the fact that you are ADDING energy to a system, and it is not heating like you'd intuitively expect - but it is instead COOLING.
My brain is left wondering... you can't obviously destroy the energy, so can someone please point to where it went? Does the room itself get hotter or something?
@roidroid Whenever the atom absorbs a photon and goes into an excited state it has to re-emit a photon in order to drop back into its ground electronic state, therefore the energy goes into the photon being re-emitted.
A laser beam has no entropy because the photons in a laser are in a single quantum state, S = k ln(W)=k ln(1) = 0. The gas of atoms is hot (say 800 K) and has a lot of entropy.
The absorption and re-emission of photons by the atom leads to the photon gas having a lot of entropy (disorder) and the selected atoms having less entropy (they cool). Overall, entropy is increased in the process which is the basic law of thermodynamics. The scattered photons take away the energy.
@roidroid This is one of the things that's bugging me.
The other one is. If you hit an atom with a photon of the right frequency, the energy of the photon is used to shift an electron of that atom to the higher orbit. If that's so, then where did the energy which slowed down the whole atom come from?
To me it seems that the atom should do exactly the opposite. It should absorb the photon when frequency is correct, without affecting atoms speed, and reflect it when it's not correct.
they tune the frequency slightly lower than an electronic transition.
therefore to atoms moving towards the light source, the frequency is Doppler shifted up to the correct energy for an electronic transition, thus the atom absorbs more photons coming towards it and loses momentum as it does so.
i think more correctly it does not absorb the photons, but scatter them. look it up on wikipedia
@IngeniousSheep the atom does absorb the photons, and later the spontaneous emission of these photons will contribute to cooling atoms, while induced emission of such photons does not help. Wiki page about "laser cooling" gives same explanation as seen in the "Doppler cooling" part.
I have always wondered how that works! Also, you folks are getting better and better at editing together videos that do a good job of leading the viewer into ideas. You are excellent.
No it is significant: this is where the kinetic energy of the atom is lost bit by bit so that the atom loses its kinetic energy. It recoils when it absorbs the photon and goes into an excited state; then it re-emits a photon which can go in any direction so on the average there is no recoil, and some of the kinetic energy is lost.
Also the entropy of the gas goes goes down as well as it cools, but the entropy (disorder) of the photons increases so all is well.
ok, so they've figured out how to stop, identify and seperate atoms. AWESOME! now we can figure out how to construct the atoms into the most accurate copies of anything we've ever made... atom by atom. Any one ever seen fifth element? Remember the table with glass shell she was regenerated in? Could we do this using this technology to collect all the atoms needed?
I think he said the energy of the photons when absorbed by the atoms turn into the "momentum" of their electrons, making the atoms change into an excited state. The professor said there's a recoil or "nudge" or "push" whenever this happens.
What I want to know is: how do photons -massless- hitting an atom have an effect on its kinetic energy? Why do the lithium atoms slow down when they become excited?
@Muonen White light is just a name for light we see as white. But it's really a mixture of loads of different wavelengths. Even if you mix those three wavelengths of light together, you've still got the same three separate wavelengths of light in there. The cone cells in our retinas actually absorb ranges of wavelengths of light. Some absorb red, some blue and some green. Those signals are processed in the brain and we see white.
so really with laser cooling you are only slowing down the gas particles by impacting them with high speed photons. now they slow down because they are being hit by an in coming particle that is moving in the opposite direction. so why doesnt it speed back up in the other direction? if you cancel motion in one direction wouldnt it pick up in the other?
Great vid - just left me wondering how the frequency of the laser is changed in order to slow the particles? I'm guessing that's the purpose of all the kit on the table, but I thought laser light was single-frequency, so how's it changed?
So how do they fine-tune the laser frequency as they hit the atoms?....if i understood the basic idea correctly, the laser frequency constantly has to undergo a change to match the atom's frequency to cool it...
@hyky68 If I understand it correctly, they're not manually matching the speed of every atom, rather starting at the highest speed match and gradually turning the wavelength down until the temperature reaches near zero.
I understand mostly everything going on here with the doppler effect and the shifts which occur, but why do the photons add on once the particle matches the frequency of the laser?
Of what kind is the energy the exited atoms give of? I guess it is light, too. But wouldn´t this light again give energy to the system... So I guess my question really is: How does the energy leave the system?
@mathiaspaul1987 Same question here. I guess if the atoms give energy of, they emit light at the same wavelength they had absorbed, so if the frequency had already been change by the time they return to their ground state, the light is kind of "tainted" in the container. Or does is the energy just spent on the momentum change? I'm just guessing really :P
What is the point of the first table? Why use mirrors to send the laser beam all over the place and then direct it into a fibre-optic cable? Why not just direct the original source into the cable?
@CRUK87 Exactly the question I was hoping to get an answer to from the video and was then going to ask in the comments since no explanation was given.
Nifty thing about this: because the nature of laser cooling is that the mass of the target atoms are directly related to their resonance, this technique can be used for (and has been adapted to) isotopic enrichment.
Why do they pay morons that catch balls 25 million a year and not you guys? At the end of the day you guys work on stuff that changes the world for the better and improves our knowledge of the universe. Day by day you grind away taking one step ever closer to the startrek age. At the end the day those professional ball catchers just catch balls. Go figure.
Because people are willing to pay $125 for one ticket to watch them. If every one stopped watching sports and attending them, then you would see that they wouldn't pay them that kind of money. But how many people would line up and pay $125 to watch a live experiment run by scientist? People pay money to be entertained. It is just the way the world works. It's a human thing.
@hempseed57 I completely agree with professional athletes getting paid too much. No body should really need or make that money. We need to start putting money towards the progression of science and the world.
Calling baseball players morons is going too far though. Some aren't the brightest bulb on the tree, but it is a thinking mans sport, especially as a back catcher. It not as easy as everyone seems to think, but the amount of money they get is too much. :)
@hempseed57 I know it's sad really, if I could change the world I would reward inventors, scientists, researchers and doctors the most. Although these people are usually so nice that money is not a motivation for them and they do it to learn, extend human knowledge and better our world; Unlike douche bag footballers that are self obsessed and greedy. End of rant lol.
@hempseed57 they are paid 25million a year because they're followed by other 25 million morons that their existence is not based on "creation" of something but rather "exploitation"...
@hempseed57 I couldn't agree more. I've been saying something similar for decades. There needs to be a label for cool tech and helpful things that says something like "Made Possible Through Scientific Research" but cooler sounding. For a long long time I've said NASA should put their logo on things that are a result of the space program.
@hempseed57 I couldn't agree more. I've been saying something similar for decades. There needs to be a label for cool tech and helpful things that says something like "Made Possible Through Scientific Research" but cooler sounding. For a long long time I've said NASA should put their logo on things that are a result of the space program.
@hempseed57 I couldn't agree more. I've been saying something similar for decades. There needs to be a label for cool tech and helpful things that says something like "Made Possible Through Scientific Research" but cooler sounding. For a long long time I've said NASA should put their logo on things that are a result of the space program.
@hempseed57 I couldn't agree more. I've been saying something similar for decades. There needs to be a label for cool tech and helpful things that says something like "Made Possible Through Scientific Research" but cooler sounding. For a long long time I've said NASA should put their logo on things that are a result of the space program.
@hempseed57 That's what happens when you put bankers or certain families in control of everything. Apparently those bankers have a different moral. I agree that a good teacher should earn more money then a ball catcher. I guess that when you have too much well educated people that they are too hard to manipulate by the powers who are in control. George Carlin (R.I.P.) once made a show about that, it was on youtube, but even that video is removed, I guess he explained it too good.
@hempseed57 They aren't arbitrarily getting payed millions for catching a ball, the public demand their services (i.e. enjoy watching them play) and through their spending on TV subscriptions, tickets and companies products advertised at games are indirectly paying them those high wages. In short sports stars only get paid as much as they can make for their clubs and sponsors via peoples desire to see them play.
@UriaHammonRaviel Sadly scientists on the other hand are not valued as much by the general population (and perhaps not in a sshort supply as top flight sportspeople) so millions of people will not spend a good portion of their disposable income to watch and support the work of scientists. So by the actions of the population in general they are considered to be less valuable and will inevitably be paid less.
I never thought it would be possible to make laser cooling sound any more complex but that guy just did it.... Bravo! not so much complex as it was long but still hahaha. Great video.
wait a minute. when the electron of a given atom absorbs a photon and the atom goes to an exited state it gains energy. how can you be cooling down the gas if you continuously ADD energy to it's atoms? Are these atoms all ending up at higher and higher states as they are cooled?
anonymousbl00dlust 2 weeks ago
@anonymousbl00dlust
The photon energy is actually lower than is necessary to excite the atoms electrons, but when the atoms are moving towards the photon source the doppler effect causes the atoms electrons to essentially be fooled into being exciting. The atoms slow down 3:40. To be honest I'm not an expert either.
marmaladekamikaze 2 weeks ago
@anonymousbl00dlust The wavelengths supplied to the atoms are not used to excite the electrons. The atoms re-emits the photon which causes the atom to gain the momentum from the photon. If the momentum is against the original direction the atom is heading, it will slow it down.
Aviatorsmith 1 day ago
bad editing
striper1149 2 weeks ago
Sixty symbols is the Sexiest Channel on the Web!
kousoulides 3 weeks ago
So, where does the energy from the hot atoms go?
JoeJoeTater 1 month ago in playlist More videos from sixtysymbols
@JoeJoeTater
it gets converted to dark matter from what i understand
elflordbob1 3 weeks ago
@elflordbob1 Why would that be? I would imagine converting energy into matter would only occur at very high energies, even if it's an unknown form of matter. Though I suppose dark matter particles could be of very low mass...
JoeJoeTater 3 weeks ago
thanks youtube for always sucking on the educational video upload speed. ugh
QuantumChance 1 month ago
Guys, Kelvin doesn't have degrees! Still, nice video. :D
OlleLindestad 2 months ago
whys it soo quiet
vampacid 4 months ago
i wanned to see how it works....
itscloudyagain 4 months ago
I bet his first most enjoyable thing is running around his office.
td6drummer 6 months ago 13
A wonderful explanation of laser cooling. A suggestion that I have would be "Just what is a Bose-Einstein condensate, and how does having atoms violating the Pauli Exclusion Principle affect the behavior of matter. Don't let him get too rusty on the details, Brady! :D
rogerdotlee 6 months ago
so you shoot a photon that has a certain amount of energy into another moving particle that has energy and and the resulting energy is less because the energy difference is stored in the particle itself by exciting an electron? is that correct? if not where does the energy go? and isnt the particle eventually going to go back into its ground state and emit a photon and thus start moving again? i hope i can get some answers! thanks for the great videos!! keep it up!!
RufolfRakete 6 months ago
"..and an electron comes in and BAFs me..."
TheChondriac 7 months ago
@bmbirdsong v=0 is just the vibrational quantum number. This isn't equal to T=0 or absolute zero. The reasons behind this are pretty complex, but it's due to anharmonic properties of molecular vibrations and fun things like that. Wikipedia is your friend on this. :)
thewiseowl 7 months ago
If absolute zero is the absence of molecular motion, is there a corresponding opposite temperature? A point beyond which you can no longer add heat to a system? Would that be the temperature of gas molecules moving at the speed of light?
bmbirdsong 8 months ago
@bmbirdsong There's no such thing as an 'absence of molecular motion'. Molecules will still possess a zero-point energy, and can never reach absolute zero. On the other hand vibrational energy levels go from v=0 to v=∞, so there is no maximum temperature. Or put another way, to get something to the speed of light would require infinite energy. Thus unless you can get to ∞°C you won't get an atom/electron or any particle with mass to the speed of light.
thewiseowl 8 months ago
@thewiseowl Wait, if v=0, isn't that absolute zero?
bmbirdsong 7 months ago
What atoms are he talking about? The air molecules that are in the laser's path?
kamikrazi123 8 months ago
"treacle" = molasses. Good information.
heyandy889 8 months ago
1:24 fantastic definition of heat
heyandy889 8 months ago
Comment removed
heyandy889 8 months ago
Now, what would be the first most enjoyable thing?
RoGeorgeRoGeorge 9 months ago 47
@RoGeorgeRoGeorge I assume its cannabis :p
SynysterCondom 6 months ago
@RoGeorgeRoGeorge Perhaps writing it all up by any chance?
cheers
nedladdy 1 month ago
Got any thermal discouragement redirection cubes?
leerman22 9 months ago 2
My physics teacher would SCREAM!
Degrees Kelvin! We get in serious trouble for that.... :P
adzer45 10 months ago 2
Oh WOW!! I've wondered for so long how they get stuff into such tiny temperatures. and YES i did think laser alway heated up or burned up stuff :D Thanks for clearing the misconception.
kheffah 10 months ago
I'm curious how the laser is being tuned and over what bandwidth, since I know precisely tuning them over large bands is difficult if it's not a dye laser - and they're messy. :P
I have also heard a new form of magnetometer has been developed using laser sensing of ?rubidium? clouds that is close to the SQUID. MIT have produced a TEC like element from superconductors that can reach extremely low temperatures by exploiting conduction barriers. That plus a SQUID = hand held heart / brain scanner?
lexichronicle2 11 months ago
Can someone tell me why atoms dont want to stop entirely? Or what prevents specifically? (Absolute zero)
ataraxic89 1 year ago
@ataraxic89
The third law of thermodynamics.
en(dot)wikipedia(dot)org/wiki/Third_law_of_thermodynamics
andrewyaoauatauabaea 11 months ago
@andrewyaoauatauabaea thank you
ataraxic89 11 months ago
Stupid question here; Brady, who are you and why do you make these videos?
M7ACCA 1 year ago
"Besides... its the second most enjoyable thing that I know" Class Quote.
And LFZ15 one thinks that was implied.
TheThomas169 1 year ago
Second most enjoyable? Psh, false. Unless it's really good sex, I guess.
LFZ15 1 year ago
@LFZ15 i think it's World of Warcraft
PerfectionKiIIs 1 year ago
Just subscribed today and already learned something I've wanted to know. How they cool with lasers. Of course I could have googled it but for some reason never did.
Keep up the videos!
letterpool 1 year ago
Ha, lovely conclusion : )
Mothdust666 1 year ago 25
Where does the energy from the heat go?
Are the atoms decreasing the wavelength of the laser as it passes through?
conoba 1 year ago
OK, so you reduce the momentum of the atom by hitting it with a photon, and drive the electron into a higher energy state. I presume then the electron then drops back releasing a photon that doesn't get absorbed. Otherwise you're just pumping energy in. No way will you cool it. I would have thought the new photon was exactly the right wave length to get absorbed. I don't understand.
gamesbok 1 year ago
@gamesbok
The photon is absorbed by the atom and an electron goes to an excited state. The electron goes back to the ground state and a photon is emitted isotropically, that is all directions of emission are equally probable. On the average (the photon can be emitted in any direction) the atom loses momentum, and also a bit of its kinetic energy is taken away by the photon. Repeat the process ten thousand times and the atom slows down and nearly stops. A Nobel prize results for this idea.
MrOldprof 1 year ago
love watching these vids!
Ghostdog162 1 year ago 3
So....what the most enjoyable thing he knows then?
captwasabi 1 year ago
@captwasabi the most enjoyable thing he knows = orgasm
toprepublic 1 year ago 2
@captwasabi you will find that out when you reach puberty.
multipena2 1 year ago
could you cool a computer CPU using laser cooling?
xXmatthdXx 1 year ago
@xXmatthdXx
That seems unlikely. You need a gas or at least a liquid for this to work. On a CPU, which is opaque, you could at best shoot lasers on it from the top etc., but not from all directions, and the laser wouldn't reach into the CPU very far (or at all).
whoppix 1 year ago
@whoppix thanks
xXmatthdXx 1 year ago
i understand the mechanics of laser cooling, it's very interesting.
but i don't understand it thermodynamically. I find it hard to wrap my brain around the fact that you are ADDING energy to a system, and it is not heating like you'd intuitively expect - but it is instead COOLING.
My brain is left wondering... you can't obviously destroy the energy, so can someone please point to where it went? Does the room itself get hotter or something?
roidroid 1 year ago
@roidroid Whenever the atom absorbs a photon and goes into an excited state it has to re-emit a photon in order to drop back into its ground electronic state, therefore the energy goes into the photon being re-emitted.
pluggo 1 year ago
@roidroid
A laser beam has no entropy because the photons in a laser are in a single quantum state, S = k ln(W)=k ln(1) = 0. The gas of atoms is hot (say 800 K) and has a lot of entropy.
The absorption and re-emission of photons by the atom leads to the photon gas having a lot of entropy (disorder) and the selected atoms having less entropy (they cool). Overall, entropy is increased in the process which is the basic law of thermodynamics. The scattered photons take away the energy.
MrOldprof 1 year ago
@roidroid This is one of the things that's bugging me.
The other one is. If you hit an atom with a photon of the right frequency, the energy of the photon is used to shift an electron of that atom to the higher orbit. If that's so, then where did the energy which slowed down the whole atom come from?
To me it seems that the atom should do exactly the opposite. It should absorb the photon when frequency is correct, without affecting atoms speed, and reflect it when it's not correct.
dbrckovic 1 year ago
they tune the frequency slightly lower than an electronic transition.
therefore to atoms moving towards the light source, the frequency is Doppler shifted up to the correct energy for an electronic transition, thus the atom absorbs more photons coming towards it and loses momentum as it does so.
i think more correctly it does not absorb the photons, but scatter them. look it up on wikipedia
IngeniousSheep 1 year ago
@IngeniousSheep the atom does absorb the photons, and later the spontaneous emission of these photons will contribute to cooling atoms, while induced emission of such photons does not help. Wiki page about "laser cooling" gives same explanation as seen in the "Doppler cooling" part.
mywtfmp3 1 year ago
Great running around your office demonstration of atoms.
johnmacward 1 year ago
3: 50 etc "A photon comes in and baffs me" don't know why but LOL.
chrisofnottingham 1 year ago
thank you very much. I was wondering about BEC and laser cooling. This answered my questions
homousios 1 year ago
god i would love to go to that place
oscar2hot4u 1 year ago
Such a good idea. The next step in supercooling...cool.
Bobajobimus 1 year ago
I have some questions:
1. If its in space or somewhere with 0 gravity, does its time to cooling off increase or no?
2. If you made a sphere of lasers would it go faster, or the time is the same even if you use just 2 mirror pointing at each other back and forth?
3. So it's affected by the Doppler effect? And what would happen if you...put your hand of an object on the middle where its cooled off?
Very interesting video btw. ^.^
blackjackel2 1 year ago
Hahaaaaaaaaaaa ... Second most enjoyable thing :D
tsk tsk ... naughty professor :P
LogInfinity 1 year ago
I have always wondered how that works! Also, you folks are getting better and better at editing together videos that do a good job of leading the viewer into ideas. You are excellent.
maekern 1 year ago
Do you expect me to talk?
No, Mr. Bond. I expect you to die.
30LayersOfKevlar 1 year ago
very interesting lasers!
jamieball 1 year ago
I can see the comments...
McPrfctday 1 year ago
@ByakuyaZERO
No it is significant: this is where the kinetic energy of the atom is lost bit by bit so that the atom loses its kinetic energy. It recoils when it absorbs the photon and goes into an excited state; then it re-emits a photon which can go in any direction so on the average there is no recoil, and some of the kinetic energy is lost.
Also the entropy of the gas goes goes down as well as it cools, but the entropy (disorder) of the photons increases so all is well.
MrOldprof 1 year ago
Great!
Any HQ images? :)
CsendesMark 1 year ago
ok, so they've figured out how to stop, identify and seperate atoms. AWESOME! now we can figure out how to construct the atoms into the most accurate copies of anything we've ever made... atom by atom. Any one ever seen fifth element? Remember the table with glass shell she was regenerated in? Could we do this using this technology to collect all the atoms needed?
joncl1 1 year ago
You've trapped your lions in their cages, but I wonder if their behaviour's as negotiable in the wild.
BoStevoD 1 year ago
Where would this be applied to help us? I pretty interesting stuff!
ProfesserPlum 1 year ago
When can I get one of these for my fridge? I HATE waiting for my beer to cool down...
squalea 1 year ago
It took them way too long to explain something so simple. The guy repeating himself over and over didn't help any.
jiberish001 1 year ago
Is that on the door a photo o the chilean tsunami?
cthulhex 1 year ago
What is the first most enjoyable thing that the Prof. knows?
3doog 1 year ago 3
@3doog Beer
myrdale 1 year ago
Very good video. I understand what your saying. But where does the heat actually go?
myrdale 1 year ago
@myrdale "heat loss"
nom3d 1 year ago
@nom3d That is obvious. The question was, where is the heat lost too. It does not simply go away.
myrdale 1 year ago
Comment removed
nom3d 1 year ago
@myrdale the incoming photon gets reflected with a higher impulse respectively higher frequence. so it takes away the energy
krem91 1 year ago
@krem91 Ahh that makes sense! I'd thought it was absorbed, which didn't make sense too me. Thankyou kindly!
myrdale 1 year ago
@RupertsCrystals
I think he said the energy of the photons when absorbed by the atoms turn into the "momentum" of their electrons, making the atoms change into an excited state. The professor said there's a recoil or "nudge" or "push" whenever this happens.
What I want to know is: how do photons -massless- hitting an atom have an effect on its kinetic energy? Why do the lithium atoms slow down when they become excited?
Lavabug 1 year ago
A year ago (watch?v=Mgyp94TZdqQ) you said in six months you would get to 100 Nano K did you get there?
pauldve 1 year ago
What could possibly be more enjoyable than this?
Is it possible to add red, green and blue laser of specific wavelenghts (e.g 751+552+819 nm) and get white light with a measurable wavelength?
Thanks again!
Muonen 1 year ago
@Muonen White light is just a name for light we see as white. But it's really a mixture of loads of different wavelengths. Even if you mix those three wavelengths of light together, you've still got the same three separate wavelengths of light in there. The cone cells in our retinas actually absorb ranges of wavelengths of light. Some absorb red, some blue and some green. Those signals are processed in the brain and we see white.
Nyphur 1 year ago
.000001 K? o_o that's unfathomable
gayglue 1 year ago
This changed my mind about lasers. I undermined the capabilities of lasers.
gabrielfinol 1 year ago
so really with laser cooling you are only slowing down the gas particles by impacting them with high speed photons. now they slow down because they are being hit by an in coming particle that is moving in the opposite direction. so why doesnt it speed back up in the other direction? if you cancel motion in one direction wouldnt it pick up in the other?
eaturfeet653 1 year ago
Amazing video once again!
elouv 1 year ago
very interesting
Frenzal88 1 year ago
Great vid - just left me wondering how the frequency of the laser is changed in order to slow the particles? I'm guessing that's the purpose of all the kit on the table, but I thought laser light was single-frequency, so how's it changed?
000Ru000 1 year ago
Really cool! Also, good atom acting. And dare we ask what the most enjoyable thing he knows is? :o
smbhax 1 year ago
can i reach 0K somehow?
uut0 1 year ago
@sixtysymbols And what is the professors first most enjoyable thing that he knows?^^ (at the end)
Softyx07 1 year ago
@RupertsCrystals
what i was thinking
gonegonego 1 year ago
I've been waiting for this video, I knew it would come out sooner or later.
absolutely great.
FormulaTrek 1 year ago
So how do they fine-tune the laser frequency as they hit the atoms?....if i understood the basic idea correctly, the laser frequency constantly has to undergo a change to match the atom's frequency to cool it...
hyky68 1 year ago
@hyky68 If I understand it correctly, they're not manually matching the speed of every atom, rather starting at the highest speed match and gradually turning the wavelength down until the temperature reaches near zero.
Nimphious 1 year ago
What's the first most enjoyable thing you know? haha
jonz94 1 year ago 2
Very good job editing.
I was able to easily understand what they were talking about. If you remove 1 key scene from this video, it doesn't make any sense.Well done Brady!
cabrita309 1 year ago 54
@cabrita309 Thanks... I like this comment! ;)
sixtysymbols 1 year ago 27
Lasers are cool!!!
DKshad0w 1 year ago
Damn, what an ending! talk about a cliffhanger. Hopefully they won't leave us hanging forever.
PBDPBD 1 year ago
I want him to be my professor.
Mocktails 1 year ago 2
Always enjoy learning something brand new, off to read-up a little on Doppler-cooling, which I guess is the whole point, so cheers.
... and Professor Roger is of course correct, nothing beats a really good sneeze.
defjam99b 1 year ago
Awesome explanation!! i had no idea that lasers could do that!! cool!
engelteir 1 year ago
Love the way he explains cooling, thank you!
TheTVLicence 1 year ago
So... would a shark with laser beams actually freeze the water around it?
BeanTVYWG 1 year ago
@BeanTVYWG lasers are still lasers and generally they will increase something temperature
Ralphgtx280 1 year ago
what is the number one most enjoyable thing?
ExcellentScore 1 year ago 4
wow two people actually clicked the thumbs down icon - "goddamnint i am not like be edumacated!"
LaMaisondeCasaHouse 1 year ago 2
and the first enjoyable thing he know will be what :S ? i always thought that discovering something is the most enjoyable thing for scientists !
SuperJoeOD 1 year ago
The old dude explaining the gas particles is EPIC, thumbs up if you agree xD
rekinu5 1 year ago 7
That is the single coolest (heh) looking set of equipment I have ever seen.
DevilMudger 1 year ago 3
Cool!! lol
gabrielfinol 1 year ago
Second most enjoyable thing you know eh?
bugmenever 1 year ago 3
@bugmenever yes i wonder whats his first most enjoyable thing lol
pboyski 1 year ago
I understand mostly everything going on here with the doppler effect and the shifts which occur, but why do the photons add on once the particle matches the frequency of the laser?
Reed12223 1 year ago
wonderful
RevDevilin 1 year ago
What is the most enjoyable thing?
bugilt 1 year ago
Of what kind is the energy the exited atoms give of? I guess it is light, too. But wouldn´t this light again give energy to the system... So I guess my question really is: How does the energy leave the system?
mathiaspaul1987 1 year ago
@mathiaspaul1987 Same question here. I guess if the atoms give energy of, they emit light at the same wavelength they had absorbed, so if the frequency had already been change by the time they return to their ground state, the light is kind of "tainted" in the container. Or does is the energy just spent on the momentum change? I'm just guessing really :P
mr0myster 1 year ago
@mr0myster Oh, and excuse my god awful English. It's too late of an hour to think in foreign languages :P
mr0myster 1 year ago
Isn't "Kelvin absolute" kind of a redundancy?
mr0myster 1 year ago
@mr0myster not when emphasising a point
ManusCelerDei 1 year ago
@mr0myster Yes!
Also it is improper to state "degrees kelvin"
Both rules are often broken.
It is sufficient to state "zero kelvin" without the absolute or the degrees.
bobster451 1 year ago
Thank you for the upload. Looking forward for more videos.
olekstom 1 year ago
What is the point of the first table? Why use mirrors to send the laser beam all over the place and then direct it into a fibre-optic cable? Why not just direct the original source into the cable?
CRUK87 1 year ago 4
@CRUK87 i would guess its more efficient to split the beem with mirrors than with a fibre cable
Serpico261 1 year ago
@CRUK87 Exactly the question I was hoping to get an answer to from the video and was then going to ask in the comments since no explanation was given.
Ph0Xy 1 year ago
@CRUK87 probably because.. the mirrors are altering the wave pattern by splitting and interference at the quantum level. :s
unknotmiguel 1 year ago
Nifty thing about this: because the nature of laser cooling is that the mass of the target atoms are directly related to their resonance, this technique can be used for (and has been adapted to) isotopic enrichment.
Fordi 1 year ago
"running this way...and that way, and going at....argh can't do this" =P
clementcoolguy 1 year ago 2
I'm going to watch Real Genius now
culwin 1 year ago
What is the first most enjoyable thing?
frankbass1 1 year ago 39
@frankbass1
Fucking.
lovingboarding 1 year ago
@lovingboarding Well everyone knows the focus of your life...
DeltaPhi79 1 year ago
@frankbass1 Quark cheese.
DeoMachina 1 year ago
@frankbass1 DMT
comface 1 year ago
@frankbass1 Sex
MoGaDeX 1 year ago
@frankbass1 You stole the words out of my mouth!
yellowmetalcyborg 1 year ago
@frankbass1 Frosted yoghurt!
x2thay 1 year ago
Why do they pay morons that catch balls 25 million a year and not you guys? At the end of the day you guys work on stuff that changes the world for the better and improves our knowledge of the universe. Day by day you grind away taking one step ever closer to the startrek age. At the end the day those professional ball catchers just catch balls. Go figure.
hempseed57 1 year ago 60
@hempseed57 Hey - nice comment and I totally agree and thumbs up!!!
jeebersjumpincryst 1 year ago
@hempseed57
Because people are willing to pay $125 for one ticket to watch them. If every one stopped watching sports and attending them, then you would see that they wouldn't pay them that kind of money. But how many people would line up and pay $125 to watch a live experiment run by scientist? People pay money to be entertained. It is just the way the world works. It's a human thing.
cabrita309 1 year ago
@hempseed57 I completely agree with professional athletes getting paid too much. No body should really need or make that money. We need to start putting money towards the progression of science and the world.
Calling baseball players morons is going too far though. Some aren't the brightest bulb on the tree, but it is a thinking mans sport, especially as a back catcher. It not as easy as everyone seems to think, but the amount of money they get is too much. :)
03iloveeureka03 1 year ago
@hempseed57 I know it's sad really, if I could change the world I would reward inventors, scientists, researchers and doctors the most. Although these people are usually so nice that money is not a motivation for them and they do it to learn, extend human knowledge and better our world; Unlike douche bag footballers that are self obsessed and greedy. End of rant lol.
GlobalWTF 1 year ago
@hempseed57 they are paid 25million a year because they're followed by other 25 million morons that their existence is not based on "creation" of something but rather "exploitation"...
nom3d 1 year ago
@hempseed57 I couldn't agree more. I've been saying something similar for decades. There needs to be a label for cool tech and helpful things that says something like "Made Possible Through Scientific Research" but cooler sounding. For a long long time I've said NASA should put their logo on things that are a result of the space program.
garbagelasagna 1 year ago
This has been flagged as spam show
@hempseed57 I couldn't agree more. I've been saying something similar for decades. There needs to be a label for cool tech and helpful things that says something like "Made Possible Through Scientific Research" but cooler sounding. For a long long time I've said NASA should put their logo on things that are a result of the space program.
garbagelasagna 1 year ago
This has been flagged as spam show
@hempseed57 I couldn't agree more. I've been saying something similar for decades. There needs to be a label for cool tech and helpful things that says something like "Made Possible Through Scientific Research" but cooler sounding. For a long long time I've said NASA should put their logo on things that are a result of the space program.
garbagelasagna 1 year ago
This has been flagged as spam show
@hempseed57 I couldn't agree more. I've been saying something similar for decades. There needs to be a label for cool tech and helpful things that says something like "Made Possible Through Scientific Research" but cooler sounding. For a long long time I've said NASA should put their logo on things that are a result of the space program.
garbagelasagna 1 year ago
@hempseed57 That's what happens when you put bankers or certain families in control of everything. Apparently those bankers have a different moral. I agree that a good teacher should earn more money then a ball catcher. I guess that when you have too much well educated people that they are too hard to manipulate by the powers who are in control. George Carlin (R.I.P.) once made a show about that, it was on youtube, but even that video is removed, I guess he explained it too good.
insAneTunA 1 year ago
@hempseed57 They aren't arbitrarily getting payed millions for catching a ball, the public demand their services (i.e. enjoy watching them play) and through their spending on TV subscriptions, tickets and companies products advertised at games are indirectly paying them those high wages. In short sports stars only get paid as much as they can make for their clubs and sponsors via peoples desire to see them play.
UriaHammonRaviel 1 year ago
@UriaHammonRaviel Sadly scientists on the other hand are not valued as much by the general population (and perhaps not in a sshort supply as top flight sportspeople) so millions of people will not spend a good portion of their disposable income to watch and support the work of scientists. So by the actions of the population in general they are considered to be less valuable and will inevitably be paid less.
UriaHammonRaviel 1 year ago
@UriaHammonRaviel
that make it more honorable.
because the people that do it, they do it by the heart.
tenisplayer 1 year ago
i want a laser cooling system for my pc =3
emocelot 1 year ago
giving energy to lose energy?
hu, warmth is giving energy away and cold is absorbing it. ah i see :P
Shockszzbyyous 1 year ago
the laser cooling table looks bitchin
Splooshiba 1 year ago
I never thought it would be possible to make laser cooling sound any more complex but that guy just did it.... Bravo! not so much complex as it was long but still hahaha. Great video.
DrDoe1 1 year ago
The second most? D=
Zeldakitteh 1 year ago
Great explanation by the professor. I always wondered how this exactly worked, now I know =D.
And I wonder what the professor's most enjoyable thing in life is =p.
FaintSnow 1 year ago
so whats the 1st most enjoyable thing that you know professor :P?
eleph4nt 1 year ago 3
Laser cooling is awesome. You can call it laser compression. You're using an electric field to counter the motion of another electric field.
It works, and it still has stuff to tell us.
525047 1 year ago
Oh, my favourite technique. Wrote a short extract on it. :)
SubTachyon 1 year ago