Andrew, i'm on my last semester at undergrad physics and i just got to know your channel! I appreciate how you keep your content funny without lowering the level of the jokes that require advanced physics knowledge to understand. You're really putting a smile on my face during this lockdown! Thanks! I hope coronavirus will let me graduate one day
Sahil, tbh it's not the case anyways that Dr. Andrew would want to attract high schoolers through arbitrary black holes like a certain other guy. I really don't think that his view count would stop him from presenting math in his videos. UA-cam is probably not his long term ambition.
"The cross-section might be larger than the cross-sectional area of what you're hitting" This is the most impressive idea I learned in this video. Thanks.
Currently trying to teach myself particle physics. So happy someone finally explained this whole cross-section idea that these other videos keep throwing around without much explanation.
The analogy of the beam to the darts used in the Pi approximation was extremely intuitive and helpful. I'm about to start my undergrad so certainly a lot of this went over my head but that helped me grasp this topic. I love that way of approximating Pi, I recently wrote a program to do it in Java! Great video!
The topic of cross section is worth a video and indeed more, since it's where theory meets experiment! As such, it's not only a major player in high energy physics but it's also a fundamental in chemical kinetics.
OMG!!! thank you!!!!, I was just looking into cross sections, you saved my life!!. One quick question, how does this relate to probability of an interaction between small particles or atoms and how would you define a barn, Im still really confused in what does the barn unit mean
Just this December I started a project on Cross section and now you have this. I'm so freaking excited dude! I'm looking for part 2 boi! Keep it going dude!
I know this is a bit stupid, but it would be great if you added the timestamps in the video description. Recently, UA-cam started to show them (together with their names) in the video's "progress bar" if they appeared there.
Very nice explanation! I had a jerk reaction to close the ad when the formula for dOmega appeared ^^ Go for the maths in the next one, but maybe sandwich the computations between beginning warning and summary, such that even if we don't get the details, we'll get the general ideas. As if we could "collapse" the development if not needed. I really thought you would spend more time deriving stuff with dSigma/dOmega as we did in mechanics class and I remember being confused, but that's the difference between classes and videos, no exam to do at the end ^^
Yeah I wasn't sure how much I wanted to get into impact parameter stuff because, well, I never actually use it in any calculations. It's a very impractical variable to pretend to be able to control in nuclear/particle physics experiments from what I can tell.
Great video and excellent analogies! I'd say that you can do Part 2 in a similar way to part 1 in the sense that you can maybe refer people who don't want to got through the math to various parts in the video. I'd go for the full on math approach with relevant links/references where needed. The concepts will still be there even if we can't follow the math from time to time.
This would have helped so much in March while taking intro of engineering when I had to a volume flow rate lab and calculate the cross sectional area of bottles and pipes, my engineering professors was the typical engineering professor who just leaves you more confused when you ask for help...... I figured it out but man this would’ve helped
Pls, go nuts with the details in your next video. In currently struggling with scatering in my QM course and i have an exam in a couple weeks. This video has already cleared a couple missconceptions i had, and im sure next one will be as helpful if not more. Thank you for such an amazing content :)
Thank you this was very helpful! I recently got involved in particle physics research and there’s a lot I’m unfamiliar with, this topic being one of the biggest head scratchers
This is so amazing thank you! Your explanation is incredibly easy to follow and very well presented! I hope some day you become a professor and I hope someday I can hear one of your lectures!! For the next video don't hold back on the maths!
Hey first year undergrad here! gr8 explaining you did there. would like to see how the impact parameter relates to the differential cross-section in the next video
This was very informative (and a very good length so don’t worry about that)! You mentioned gold foil and talked about how objects don’t really hit each other; any chance you plan on going over the scattering of Rutherford‘s experiment? That was the one we talked about in my Modern Physics class and I always felt I was missing a few details.
Hey! I am a physics Undegrad and I'm trying to learn ForTRan. I love your videos, and in your PhD Vlog, you mentioned using FORTRAN. I think it will be GREAT if you could make a video on your work using fortran and maybe give a small tutorial, like you did with Python. HUGE REQUEST. Respect from India.
Nice video! One question: what classical mechanics textbook should I pick up? I’m a high school senior (last year high school), but I alredy took calculus.
Next step would be a general physics textbook for first level classical mechanics (like high school physics, but maybe more calculus, depending on your high school) after that, for higher level but still undergrad, we used "Classical Dynamics of Particles and systems" by Marion and Thornton. You will need a bit more math than calc 1 for that, prerequisites are usually calc 1, 2, 3, and differential equations. But that doesn't mean you cant take a stab at it and learn as you go. Hopefully others will comment with better ideas.
May I please know your area of expertise? Cause a few days back I asked a question to a scientist at Fermilab but he said that he does particle physics...not nuclear physics😅 I don't want that to happen to you too whenever I ask you questions. BTW I am a 12th grader Science (Biology) student (that means I get Physics, Chemistry and Biology in my course + some side subjects) from India and I get this in my Physics course...just look at all the chapters (theory) for both class 11th and 12th, practicals are to be taught no more (quarantine times) + I get calculus too (just integrals and derivatives though and yeah...vectors too) [[[PDF LINK to all the chapters]]] www.google.com/url?sa=t&source=web&rct=j&url=www.ncert.nic.in/rightside/links/pdf/syllabus/syllabus/desm_s_Physics.pdf&ved=2ahUKEwiYh7DgweTpAhWLILcAHc1dAD0QFjAAegQIChAB&usg=AOvVaw2alaME5CRRmAP4cHwYwJTk
A Cross section is exactly what the Term says. It is the area That will scatter. If there is a probability going through without scattering the Cross section is smaller Then the Projected Disc - however Disc is something related with Short Range interaction. For coulomb Forces Cs can be big. Differential CS is Accounting for the propability beeing scatter to a certain angle (3d angle Element) . For Uniform scattering dcs=CS/4pi.
Andrew could you progess step by step mathematically and then do the heavy math stuff. Also could you point out the resources about how particle properties are found using particle accelerator
Please both do a super-complicated version and also a simple version so both parts are happy. Because I really wanna see something complicated, but I'm not sure if I'd be able to follow...
I have a question, maybe someone around or Andrew has an idea. You said in some long ago video something about "is going to be an experientialist" "is going to be a theorist". Now I fall very much into being really interested in theory when it comes to the courses and what I learning about. However I have found that I don't actually like sitting in front of a computer all day, I really miss my lab days, I make too many careless mistakes to compute things analytically. But I have almost only done theory courses in grad school because except of actually doing experiments, I really don't like experental courses. Now I need a master's thesis topic... And I don't know what to do. Where to go?
Hey what about Lorent invariant phase space any plan to make a video on that...if possible please mention that for cylindrical coordinator one also. Thanks again for the great video
Could you do a fundamentals of LaTex video. I started using it for my engineering classes but I would like to see how you use it and what do you recommend. Please. Thank you
Even as a physics major, I still don't have a good understanding of something like cross sections.....I mean, I don't understand almost anything about physics and yet I'm doing this.....That's what life is.....Anyway, thanks Andrew.
There's a link in the description of this video of his: ua-cam.com/video/sIpj_D3VfzE/v-deo.html Or just go here: www.wellesley.edu/lts/techsupport/latex/latexwin
Visually this reminded me of how in the image of the black hole at the center of m81 we can only see the "shadow" of the black hole, the area encompassed by a schwarzschild radius, and is bigger than the black hole itself. But then again how else do you observe a black hole, when all that's emitted is light from the disk, jets or gravitational waves.
Hi, thanks. It seems unclear how your N=Nb(1+t/tau) works, since N and Nb have different dimensions: 1/sm^3 and 1/sm^2 and you never assumed beam length to be 1 sm or so. Is there some secret or I get the idea wrong?
I have nothing to do with this video but wanted to comment somethin. I've written a free verse on online classes..please have a read Punctured heart, beaten lungs Half sickled throat Myriad tales in blooming mind Fluctuating mind The commanding voice amplified into a monody Second by second, brain growing pessimistic Those bleeding eyes awaiting liberation Once free hands, tied to the chains of imprisonment With only one question reverberating "When will this end?"
29:28 you mentioned in the single target case that flux is (nvb)*(Ab)*(v), but in the case of multi-target 'Ab' is not a part of the flux. That is the only thing that confused me. Can you explain that part?
Can you do the derivation of the differential scattering cross section as a coordinate transformation from the impact parameter coordinates b, phi to the spherical coordinates theta, phi after scattering?
andrew- question- do you ever worry/ have concerns for your future after you get your PHD? It seems nowadays there are too many PHDS and too little jobs due to saturation and it seems as though companies don't really know the assets of a PHD and what they bring to the table. I just wanted to know your opinion on this as it's the elephant in the room for most PHDS.
@@josephbrennan370 unfortunately yeah. Over the past two decades or so, the amount of PHDs awarded has been up and to the right where as faculty positions available at institutions have been flat. Working your way up in academia is brutal.
Math heavy please next time! I've just taken a first course introducing scattering theory (first in 1D, then in 3D, then off lattices), and though I can calculate the cross sections, I really have no idea why the asymptotic coefficient of e^{ikr}/r, f(\theta, \phi), is dsigma/dOmega = |f|^2
Dude! Dude! 1:40 I think we are describing projection area this whole time. As a mechanical major, I think cross sectional area is -- area that you get by cutting a body with some other surface (usually a plane). And most of my thermal physics, fluid dynamics, engineering drawing courses would agree with me here.
Pretty sure a cross section is when Babish cuts a sandwich in half and shows the camera but ok
Grad students:- Ah sh*t. The jackson.
Future grad students:- Ah sh*t. The dotson. :)
By the way
This is amazing. Looking forward to the next part.
I'm an undergrad so I don't know anything about this , but the way you explain things is addictive
thank you!
Exactly, i'm not even a physics major but this is so entertaining.
When you need to understand well cross sections for a close nuclear physics exam and Andrew reads your mind and upload a lesson.
What else? Thanks
I like that as I progress through my undergrad, this type of video slowly starts to make more sense!
14:54 NO SIR DON’T ERASE YET! I HAVEN’T FINISHED MY NOTES!
Andrew, i'm on my last semester at undergrad physics and i just got to know your channel! I appreciate how you keep your content funny without lowering the level of the jokes that require advanced physics knowledge to understand. You're really putting a smile on my face during this lockdown! Thanks!
I hope coronavirus will let me graduate one day
I don't know if Im supposed to feel proud to even know this type of stuff.
- any physics student
bruv
Your beard gets 40x larger each video. I aspire to be like you.
Awesome work as always!
your hair screams physics.
?
I mean, you're not wrong!
it screams quarantine
Can do a video on the physics of a Flowbee. I think there's a lot we can learn here.
Andrew Dotson lmaoo
You are like a big brother who is already doing what I wanna do and getting me ready for things to come.
When I searched for cross sectional area looking for some explanatory video and find that Andrew have one doing so, bro thats happiness. Good video!
it would be a good exercise to estimate the average cross-sectional area of your beard
hold on let me measure the cross sectional area of the incident light first lol
In the next video, don't hold back on the math please!
His videos will hold back on views then.
Sahil, tbh it's not the case anyways that Dr. Andrew would want to attract high schoolers through arbitrary black holes like a certain other guy. I really don't think that his view count would stop him from presenting math in his videos. UA-cam is probably not his long term ambition.
"The cross-section might be larger than the cross-sectional area of what you're hitting"
This is the most impressive idea I learned in this video. Thanks.
I can feel how he's slowly descending into madness over the years of studying physics
Currently trying to teach myself particle physics. So happy someone finally explained this whole cross-section idea that these other videos keep throwing around without much explanation.
The analogy of the beam to the darts used in the Pi approximation was extremely intuitive and helpful. I'm about to start my undergrad so certainly a lot of this went over my head but that helped me grasp this topic. I love that way of approximating Pi, I recently wrote a program to do it in Java! Great video!
Just started my grad program in nuclear engineering with only a background in chemical engineering... Thank you Andrew. This was definitely needed.
The topic of cross section is worth a video and indeed more, since it's where theory meets experiment!
As such, it's not only a major player in high energy physics but it's also a fundamental in chemical kinetics.
It is? Can you refer me to some sources to read about that?
@@AgusMastex Hirschfelder et al., "The Molecular Theory of Gases and Liquids”, Wiley, (1964)
Thank you for making a mini series on this!! I’ve asked this question so many times, but it helps when many people explain it.
I cannot thank you enough for your video! It is so clear, deep, and kind all throughout!!! Can't wait to watch part 2!!!
Perfectly timed video, as always. I'm just listening to Nuclear and Elementary particles physics for the first time and those popped of immediately
OMG!!! thank you!!!!, I was just looking into cross sections, you saved my life!!. One quick question, how does this relate to probability of an interaction between small particles or atoms and how would you define a barn, Im still really confused in what does the barn unit mean
Just this December I started a project on Cross section and now you have this. I'm so freaking excited dude! I'm looking for part 2 boi! Keep it going dude!
Pretty relaxing to have that as background while working
This was incredibly helpful. I am doing a particle physics internship right now and was struggling a lot with this concept. Thank you!!!
I know this is a bit stupid, but it would be great if you added the timestamps in the video description. Recently, UA-cam started to show them (together with their names) in the video's "progress bar" if they appeared there.
Definitely go down the rabbit hole. We love to see insane level math.
Dude I don’t know why but these videos are super motivating to study for the MCAT so thanks!
Wow. This video was definitely worth the wait Dr.Dotson!!
Very nice explanation!
I had a jerk reaction to close the ad when the formula for dOmega appeared ^^
Go for the maths in the next one, but maybe sandwich the computations between beginning warning and summary, such that even if we don't get the details, we'll get the general ideas. As if we could "collapse" the development if not needed.
I really thought you would spend more time deriving stuff with dSigma/dOmega as we did in mechanics class and I remember being confused, but that's the difference between classes and videos, no exam to do at the end ^^
Yeah I wasn't sure how much I wanted to get into impact parameter stuff because, well, I never actually use it in any calculations. It's a very impractical variable to pretend to be able to control in nuclear/particle physics experiments from what I can tell.
Omg I've made introductional videos about cross section too. But they're in Italian 🙈🙈❤
i m feeing happy to subscribed you...
I was always waiting for this type of video for understanding cross section
Great video and excellent analogies! I'd say that you can do Part 2 in a similar way to part 1 in the sense that you can maybe refer people who don't want to got through the math to various parts in the video. I'd go for the full on math approach with relevant links/references where needed. The concepts will still be there even if we can't follow the math from time to time.
Yeah I think that's what I'll end up doing
Most clearly described the idea behind the scattering cross section . Nice bro !
thanks a lot!
This would have helped so much in March while taking intro of engineering when I had to a volume flow rate lab and calculate the cross sectional area of bottles and pipes, my engineering professors was the typical engineering professor who just leaves you more confused when you ask for help...... I figured it out but man this would’ve helped
Pls, go nuts with the details in your next video. In currently struggling with scatering in my QM course and i have an exam in a couple weeks. This video has already cleared a couple missconceptions i had, and im sure next one will be as helpful if not more. Thank you for such an amazing content :)
here to support my physics boi
:)
:(
thanks a lot for giving such an explanation. This and the tensor lectures are helping me greatly.
That's cool. Good to see derivations textbooks just omit.
Thank you this was very helpful! I recently got involved in particle physics research and there’s a lot I’m unfamiliar with, this topic being one of the biggest head scratchers
can't wait for part 2 !! keep up the great work andrew😊
This is so amazing thank you! Your explanation is incredibly easy to follow and very well presented! I hope some day you become a professor and I hope someday I can hear one of your lectures!!
For the next video don't hold back on the maths!
Hey first year undergrad here!
gr8 explaining you did there.
would like to see how the impact parameter relates to the differential cross-section in the next video
This was very informative (and a very good length so don’t worry about that)! You mentioned gold foil and talked about how objects don’t really hit each other; any chance you plan on going over the scattering of Rutherford‘s experiment? That was the one we talked about in my Modern Physics class and I always felt I was missing a few details.
This is legit because I JUST did a Monte Carlo scattering simulation!
do you play brawl stars?
@@sahilbaori9052 Hmm, that definitely follows from what I just said
Hey! I am a physics Undegrad and I'm trying to learn ForTRan. I love your videos, and in your PhD Vlog, you mentioned using FORTRAN. I think it will be GREAT if you could make a video on your work using fortran and maybe give a small tutorial, like you did with Python. HUGE REQUEST. Respect from India.
Great video, loved it. Always nice to recap cross section stuff :D
Looking forward to the next video, I will watch it tomorrow :D
Great video!!! These videos are getting better and better
Such a good lesson, Andrew. Thanks.
Nice video! One question: what classical mechanics textbook should I pick up? I’m a high school senior (last year high school), but I alredy took calculus.
Next step would be a general physics textbook for first level classical mechanics (like high school physics, but maybe more calculus, depending on your high school) after that, for higher level but still undergrad, we used "Classical Dynamics of Particles and systems" by Marion and Thornton. You will need a bit more math than calc 1 for that, prerequisites are usually calc 1, 2, 3, and differential equations. But that doesn't mean you cant take a stab at it and learn as you go. Hopefully others will comment with better ideas.
Demtröder, Experimentalphysik 1 is a very good book imo, it's german though
Taylors classical mechanics is really good imo
May I please know your area of expertise? Cause a few days back I asked a question to a scientist at Fermilab but he said that he does particle physics...not nuclear physics😅
I don't want that to happen to you too whenever I ask you questions. BTW I am a 12th grader Science (Biology) student (that means I get Physics, Chemistry and Biology in my course + some side subjects) from India and I get this in my Physics course...just look at all the chapters (theory) for both class 11th and 12th, practicals are to be taught no more (quarantine times) + I get calculus too (just integrals and derivatives though and yeah...vectors too) [[[PDF LINK to all the chapters]]]
www.google.com/url?sa=t&source=web&rct=j&url=www.ncert.nic.in/rightside/links/pdf/syllabus/syllabus/desm_s_Physics.pdf&ved=2ahUKEwiYh7DgweTpAhWLILcAHc1dAD0QFjAAegQIChAB&usg=AOvVaw2alaME5CRRmAP4cHwYwJTk
Perfect timing! Just starting my REU this summer this is will be helpful!
Oh where at?
Andrew Dotson Boston University, I was fortunate the program was able to transition online despite what is currently going on in the world right now.
A Cross section is exactly what the Term says. It is the area That will scatter. If there is a probability going through without scattering the Cross section is smaller Then the Projected Disc - however Disc is something related with Short Range interaction. For coulomb Forces Cs can be big. Differential CS is Accounting for the propability beeing scatter to a certain angle (3d angle Element) . For Uniform scattering dcs=CS/4pi.
Great video. I understood very little, but the way you explain is great!
Andrew could you progess step by step mathematically and then do the heavy math stuff. Also could you point out the resources about how particle properties are found using particle accelerator
I don't understand a word he's saying in any of his videos, but he's so freakin' handsome that I'm hooked.
This was really well-explained and really cool! Can't wait for the next video
I can see that this boi will become a physicist that everyone will bow down to
Thanks Andrew, you made my time storming the radio tower to take it back from team rocket much more educational
Please both do a super-complicated version and also a simple version so both parts are happy. Because I really wanna see something complicated, but I'm not sure if I'd be able to follow...
You are a good teacher sir, this is like dirty talk to me
I have a question, maybe someone around or Andrew has an idea. You said in some long ago video something about "is going to be an experientialist" "is going to be a theorist". Now I fall very much into being really interested in theory when it comes to the courses and what I learning about. However I have found that I don't actually like sitting in front of a computer all day, I really miss my lab days, I make too many careless mistakes to compute things analytically. But I have almost only done theory courses in grad school because except of actually doing experiments, I really don't like experental courses. Now I need a master's thesis topic... And I don't know what to do. Where to go?
If you are doing any lecturing (like SI), could you record it? Sounds like that would a fun video
Hey what about Lorent invariant phase space any plan to make a video on that...if possible please mention that for cylindrical coordinator one also.
Thanks again for the great video
Could you do a fundamentals of LaTex video. I started using it for my engineering classes but I would like to see how you use it and what do you recommend.
Please. Thank you
Even as a physics major, I still don't have a good understanding of something like cross sections.....I mean, I don't understand almost anything about physics and yet I'm doing this.....That's what life is.....Anyway, thanks Andrew.
i was confused about scattering matrix in a course in quantum field theory , this seems promising
Could you include bibliography in the description?
The video I needed but not the one I deserved
Hey Andrew, I know this isn't related but what LaTeX editor do you use? I'm trying to find one but I'm having a hard time.
There's a link in the description of this video of his: ua-cam.com/video/sIpj_D3VfzE/v-deo.html
Or just go here:
www.wellesley.edu/lts/techsupport/latex/latexwin
Visually this reminded me of how in the image of the black hole at the center of m81 we can only see the "shadow" of the black hole, the area encompassed by a schwarzschild radius, and is bigger than the black hole itself. But then again how else do you observe a black hole, when all that's emitted is light from the disk, jets or gravitational waves.
Such a handsome physicist.. with incredible knowledge,,👏
I have no idea what you're talking about. But still watched the entire video.
For the next one please don’t hold back on the math. Also would love if you talked about recoil mass techniques
Bro, I found your content by accident and all I've being saying is "What." But still subscribed.
Great video as usual. Please go down the rabbit hole for the next video. We need you at all guns blazing.
The only CS tutorial I can understand
Hello Grizzly Adams. You are really smart for a guy who wrestles bears. 🐻
Get a load of THIS guy
Hi, thanks. It seems unclear how your N=Nb(1+t/tau) works, since N and Nb have different dimensions: 1/sm^3 and 1/sm^2 and you never assumed beam length to be 1 sm or so. Is there some secret or I get the idea wrong?
I have nothing to do with this video but wanted to comment somethin. I've written a free verse on online classes..please have a read
Punctured heart, beaten lungs
Half sickled throat
Myriad tales in blooming mind
Fluctuating mind
The commanding voice amplified into a monody
Second by second, brain growing pessimistic
Those bleeding eyes awaiting liberation
Once free hands, tied to the chains of imprisonment
With only one question reverberating "When will this end?"
Your videos make me wanna major for physics
edit: im a pure math guy
Do it.
29:28 you mentioned in the single target case that flux is (nvb)*(Ab)*(v), but in the case of multi-target 'Ab' is not a part of the flux. That is the only thing that confused me.
Can you explain that part?
Can you do the derivation of the differential scattering cross section as a coordinate transformation from the impact parameter coordinates b, phi to the spherical coordinates theta, phi after scattering?
I am gonna pretend that is a perfect shadow of a ball if you let me pretend I know what you're talking about XD, but thanks for this cool video!
Imperial Porter decanted into vessel? Check. First sip down me neck? Check. Ok, let's do this.
andrew- question- do you ever worry/ have concerns for your future after you get your PHD? It seems nowadays there are too many PHDS and too little jobs due to saturation and it seems as though companies don't really know the assets of a PHD and what they bring to the table. I just wanted to know your opinion on this as it's the elephant in the room for most PHDS.
I think it's going to be more of a waiting game. Doing post docs until I can get a faculty position
Is that true? Is there really a saturation of PHDs?
@@josephbrennan370 unfortunately yeah. Over the past two decades or so, the amount of PHDs awarded has been up and to the right where as faculty positions available at institutions have been flat. Working your way up in academia is brutal.
Math heavy please next time! I've just taken a first course introducing scattering theory (first in 1D, then in 3D, then off lattices), and though I can calculate the cross sections, I really have no idea why the asymptotic coefficient of e^{ikr}/r, f(\theta, \phi), is dsigma/dOmega = |f|^2
Great Video Andrew!
Dude! Dude!
1:40 I think we are describing projection area this whole time.
As a mechanical major, I think cross sectional area is -- area that you get by cutting a body with some other surface (usually a plane). And most of my thermal physics, fluid dynamics, engineering drawing courses would agree with me here.
Could you derive to the exact solutions of the incompressible two dimensional navier stokes eqaution?
I don't care if I don't understand the math. I just want to watch another video by Andrew
It’s be pretty nice if you made a video talking about self learning physics from scratch
great work...really helpful ...
I haven't opened it yet but I'm already excited. *heavy breathing*
Go for the s-matrices!!
Very helpful video!
It was very helpfull sir
I love you sir💝💝💝