The Biggest Ideas in the Universe | 1. Conservation

[@ohmultiverse]

Some people's personalities just...shine. Or rather, they shine through. One only has to watch Sean Carroll for a little while to know, to a high degree of certainty, that he is not only highly intelligent, but also that he has a wonderful wit, is a kind human being, is fundamentally optimistic, and is thoroughly unpretentious. Thanks so much for creating this series Dr. Carroll.

[@HawthorneHillNaturePreserve]

I couldn’t have said it better.

[@doublechin35]

Exactly how I picture him. Thank you !

[@jbug1979]

Totally agree. Jennifer is a lucky woman!

[@jonathanwalther]

D'accord! Kind words. I feel glad, I discovered his chanel. I have a minor in Physics and appreciate very much, he does not shy away to use and explain formulas.

[@hifibrony]

He was born to teach and is splendid at it.

[@seancarroll]

Leave questions here, over the next couple of days I'll pick some favorites and try to answer them in a separate video. (Not "ask me anything," but "ask me about stuff discussed in the video.")

[@IITandBeyond]

If time is the currency of life, why should a person specialise and miss out on observation?

[@jeffwatson9868]

Is conservation of momentum also a local notion like conservation of energy, in General Relativity?

[@arpansircar8858]

First, is this an accurate statement ? - Dark energy causes the acceleration of the space-time fabric which leads to the expansion of the universe. Second - Does the motion induced by dark energy obey the conservation of momentum ?

[@emanuelebinetti6499]

@@jeffwatson9868 Yes, in special relativity the momentum 4-vector is conserved, meaning the local change in time of its spacial density is compensated by the flow of momentum current in every other direction. You may as well think of the change in time of the momentum spacial density, as the flow of the momentum current in the "time" direction. This conservation is applied, in a given frame of reference, to each component of the 4-vector independently. You may think of the "time" component of the momentum as energy. General relativity does not change this.

[@notablycurious6261]

Is there a point at which physicists might come to a consensus about, physics as a field being complete ,meaning there will be no more improvements required.what should such a theory ought to explain to consider the field complete in your opinion.

[@integza]

I love this! Great idea! It's an honor to have you here on KZbin, Sir.

[@robertgoss4842]

Dr. Carroll: I just started your Biggest Ideas series, and I felt I must thank you for your hard work in producing these videos. The combination of your acumen and your relaxed, accessible presentation style, makes you a terrific educator. I look forward to many hours of learning pleasure in days ahead. Again, thanks a million!

[@ghislaindebusbecq8864]

As a non-native English speaker, I find Sean Caroll speaks one of the most understandable and agreable English I've heard from English people. Robert Eagle from Dr. Physics A channel is also very understandable and agreable. Why all English people are not physics specialists ?

[@ratedAD]

Sean, please keep doing this! You truly have a gift. Love your work and your passion for educating the uninitiated. I'm 36 and deeply regret not taking physics more seriously growing up. Your lectures and videos are such a source of intellectual nourishment for me. I am a regular listener of your Mindscape podcast and a Patreon supporter. Please keep producing more work that benefits people like me who are not trained in the math but are curious about the big questions nonetheless. Cheers! Please stay safe!

[@ThePathOfEudaimonia]

Hi! How has your voyage into physics been these last four years? Hopefully you are still on your self-directed path of learning!

[@CHXFIT95]

I love this guy. Taking this class seriously. You inspired me to learn physics a few years ago when you got onto JRE and I haven’t stopped learning since. Thanks Sean. Also plan on purchasing your books as soon as I have some extra money.

[@clausmarcuslund]

I think your channel is going to become just great - keep pushing, keep it moving!

[@3dlabs99]

9:58 Love that you put an arrow below the arrow - - wonderfully redundant :)

[@bensthoughts2]

You have no idea what a relief hearing about the spherical cow metaphor was to me just now. I have always fought with myself over the tendency to get hung up on the surrounding "whys, what if's, and buts" and the subsequent push past them to get work done. Always looking over my shoulder in some kind of dreadful way that leads to imposters syndrome. The spherical cow turns that dread and feeling of imposters syndrome into reasonable healthy caution. Thank you so much!!!

[@apollion888]

I'm watching these out of order and I must say that my already high opinion of you has gone up considerably. You were made for this. Well done, sir.

[@jimgraham6722]

Your time, expertise and effort in making this series is much appreciated.

[@seffundoos]

Thank you Sean. You are really leaving some wonderful things for today's generations and future ones alike. I especially like your take on the purpose of physicists and the way you have not been scared to delve into the world of the implications of quantum mechanics. There is no doubt that you will be the inspiration for countless physicists to come! Thanks again for the exceptional content.

[@kibavlood5826]

Sean i came from the Joe Rogan episode where you literally blew my mind when you said that even though you make a simulation that predicts everything the choices a human make inside is totally random and still is unpredictable. It went something along those lines. That and also Laplace's Demon. I was always interested in Science but my teachers and professors made a nightmare out of it. I gave up the interest and curiosity i once had but thanks to you i rekindled that curiosity. Also i love the way you explain stiff so easily and simple. Take care of yourself in this hard times. Love to learn something new from your videos.

[@rogermaioli]

What a splendid series, Sean! I've long followed and admired your work, and it's a pleasure to see it in this (relatively) new format, which I hadn't known prior to today. It's fully deserving of all the praise it got in the comments, and I wanted to add to it: it is encouraging to see a professional scholar trained in the sciences show such caution and humbleness when speaking of humanistic disciplines such as the history of science and the history of philosophy. There is a lot of misunderstanding, on the part of humanists, about what scientists do; and there is a lot of corresponding misunderstanding on the other side of the fence, with professional scientists saying out loud that things like the philosophy of science aren't worth their time. In times of such public distrust in expertise (whether the expertise of scientists who study viruses and the climate, or the expertise of humanists who study history and sociopolitical relations), it is important to promote mutual understanding and mutual support between the sciences and the humanities. Your attitude is a great example of how to do that.

[@michaeltoulch4187]

Your explanations and attitude remind me of Feynmans videos- such as when he discusses why ice is slippery and why grandma (I think it was grandma) fell on it. Like him you could explain these great concepts to a high school dropout or an advanced scholar. Incredible stuff Dr Carroll - looking forward to the next round.

[@lukeworldwide]

Thanks Sean so much for this series. I didn't get to study much maths and physics at school, so this level of conceptual explanation of these important concepts is fantastic for me.

[@jms547]

17:51 - you meant to say kinetic energy is just a scalar! I don't know if youtube still allow annotations so that you can put an onscreen correction. Alas I don't think so...

[@seancarroll]

Oops! Added a note at the top, but yes, KZbin no longer allows annotations.

[@WestOfEarth]

I feel like the fact that I caught this error too means I'm learning something, lol.

[@trewq398]

@@seancarroll why is that not allowed?

[@darrenoneill7495]

If I successfully corrected Sean Carroll I think I’d put that on my CV

[@roqsteady5290]

@@seancarroll Are all scalar values conserved?

[@djbabbotstown]

Just a great pleasure Seán. Wonderful style. Like listening to a friend who has found out something, a conversation.

[@WR7000]

Sean - I have just started reading your book on this topic, which led me to your channel. I'm a lifelong student of science and your presentation and writing style are as good as it gets in my view. I've always wondered what causes motion in the universe beyone the big bang with "force" being the answer. Even so, I'm still amazed how a sphere of pure matter with the mass of the sun but only 20 miles in diameter, can spin at 700 times per second or 44,000 RPM and where that came from. I now realize it came from a spinning super nova. I look forward to your other work and will be a grateful student.

[@irenehernandez7034]

I want to thank you for the positive information about not giving up. I am a student of Dr Jatila van der Veen. I love her and had a great time in Astro 101. I like how I said "survive and move forward," "know learn and understand." It was helpful top hear you amd will watch some of your other pod casts. Thank you

[@wasimshaikh1969]

Man u deserve a Nobel prize for your explainations👏👏 I wish my physics teacher was like him🤔

[@TheMemesofDestruction]

And I’ve come full circle back here. The Universe is balance. Thank you again Professor!

[@TheyCallMeNewb]

Wow. Now that's what erudition must sew in the host: a generous empathy and indulgence of previously made errors that went unnoticed by otherwise dedicated experts simply living in irreconcilably disparate climates to our own. Remarkable.

[@thomaslarsen2759]

Dude, I am 62 years old... wish back in the day I had you (if I could go back in time and you stayed the same young age your are now) as a professor. You rock! Make things understandable to most. Love the Quantum info too!! Please do more. - Tom from Skokie, IL

[@thenorseman8964]

You, Dr. Carroll, are a worthy candidate to be this newest generations' "Great Explainer." Please accept this humble gift of an imaginary Spherical Feynman to sit proudly next to your Cow.

[@rzezzy1]

Is he in a vacuum? That might be a problem

[@trefod]

@@TheDavidlloydjones Hahahaha! That was awesome.

[@robertgoss4842]

Wow. Very well said!

[@suddhasattasaha4793]

I believe 'momentum' is a measure of the effect of motion that we observe around us. This is a more intuitive way of understanding the physical meaning of momentum. Great work Sean ! 😊😊

[@kensharp3059]

I liked the video...especially the spherical cow discussion. I'm going to keep listening to the series.

[@intrograted792]

Here's an unnecessary comment, but anyway... Sean, I don't subscribe to many worlds, I don't like some of your politics, you have a rather (passively) antagonistic relationship with a public intellectual I greatly admire - all things that in this day and age could be a turn off to engaging with someone BUT you really are the best, and perhaps most honest, public educator of difficult physics topics around right now. Thank-you for this series and your contribution to public science education.

[@s4pjans]

I can listen to you for hours! great talks, sensible and understandable

[@dtce]

It’s some 20 years ago I learned Newtonian mechanics and conservative of momentum. Physics still fascinates me despite I have left the field for more than 10 years by now. Thanks for the series. I wish this existed when I started out in my physics training. Maybe I will show this to my children one day. My eldest is 7.

[@nahlaeltaher5325]

Very fun and informative. Dr. Carroll never seizes to amaze me.

[@HarrisD214]

I’ve only watched the first episode but I loved it and can’t wait to watch the rest you’ve released. Thank you so much for taking the time to make these.

[@greyskelton9117]

Great video! Thanks for taking the time to make and share

[@zenSutherland]

I was introduced to you via Wondrium and now am telling everyone about spherical cows! Seriously, your explanations, while i mostly grasp the coattails of, give me the greatest hope for understanding at least a tiny part of the quantum world. And with a touch of humor. I THANK YOU!

[@tmhood]

10:00 I like how you draw an arrow to show which way the arrow is going.

[@mrlithium69]

Thank you for doing your part explaining complex topics and making your mark on the internet. In the information age, this will live on forever and in the future you may even be regarded as a modern Aristotle-type thinker from the 21st century. Cogito, ergo sum.

[@steliosp1770]

Dr. Caroll, thank you so much for your podcast, books and your KZbin channel. Love your work and thank you for being such an incredible communicator of science. All the very best to you and your family.

[@chronosarcanos]

So many referentes you do on the podcast are explained here, spherical cow etc. Love the video.

[@Slarti]

I reckon you could write a book from these talks. You are so good at explaining these concepts that I think if it was in book form you could reach a wider audience.

[@Thelonious2Monk]

The idea of the spherical cow and its implications (as you have explained) should be explained in the first lecture in every middle and high school. In my experience students do not see the connection between the simplified physics they learn in class and the real physics they experience on a daily basis. This makes it hard for them to really appreciate the importance of the subject of physics to their life. Thanks for talking about it.

[@bwkerst]

One spherical cow bonus from me too! I learned some things. Fills the gap between PBS spacetime and what I learned at highschool.

[@briandimattia629]

Isnt spacetime great? So glad I found that and this along with others. Science is wonderful

[@Lightning_Lance]

Loved it. The spherical cow philosophy is now my favorite explanation as to why math/physics is so unexpectedly succesful in describing the world around us.

[@furthercuriosity4330]

I got pretty late to watch this stuffs, but I don't want my appreciation to get late for you. Thank you so much for all of this.

[@simos11]

Another great video. I started watching the The Biggest Ideas in the Universe and I can't stop!!!

[@joshuaphillips4604]

Finally started watching after putting this on watch later list. I know what I'm binge watching this weekend.

[@johngoodwin9606]

Such a great presentation. I'm reading the book chapter after the video and it is helping "make it stick". Have been listening to the MindScape videos too.

[@ddeibler1826]

This is beautiful. Im but a lowly wannabe scientist. My hero was Thomas Edison. I checked out books from my school library about him and others. Thats all I wanted to be. Now I watch this and follow your podcast and i am amazed. You became the scientist I always wanted to be, Thank you so much for sharing this with we mere mortals!!!!

[@dem8568]

Woop woop! I'm reading the book along with the videos. Very well done!

[@72fishing]

Great work sean, thank you for taking time to make these podcasts. And for educating this generation and hopefully future generations to come, thanks from Ireland ☘

[@tcbbct509]

After I get home from working at the hospital your videos really help me get my mind off of what's going on. Thank you Sean. Not that it's really relevant to this particular video but Im sort of starting to understand the concept of a superposition and that's all you bud!

[@skipbellon2755]

The Spherical Listener. Being late to the show and coming to the realization that there are more than 20 more of these episodes, allows me to strip my mind down to the basics. When I'm done watching them all, I will add the stripped pieces back.

[@zoeystone8780]

It'a absolutely a joy to listen to you Dr. Carroll! You are a delightful teacher of a vastly amazing subject: Physics. Once I grasp the basic concepts, I hope to study your personal theoretical work in physics too. Thank you for making this freely available!!!🙏 💕

[@TheNorbles]

Awesome video! Very entertaining and educational. Loving hearing the stories of the history and philosophy behind the ideas, also love the enthusiasm for the subject!

[@andrelagerburg7817]

About inelastic collision (17:10). Isn't silly putty the stuff that you can use as a bouncing ball (elastic!), but when leaving to rest flows out? You have to save it a box when storing it. In contrast to 'normal' materials, it relaxes over time, but not in the short amount of time it bounces. Or . . . am I totally wrong. Do I mean some other stuff (that I am sure of, exists).

[@gaznawiali]

I liked your careful attitude to the history of science. I think it was very respectful and modest.

[@Grinsekatze113]

Pro tip: I don't know what you are using for video editing but somewhere you should be able to adjust the colours. Lower the green values, maybe cyan. That's an easy way to clean up the edges and even the light scatter. Greetings from Germany, keep it up!

[@DoggoWillink]

Very happy to have found Sean’s channel. Usually I need to watch channels that have less information (colloquial sense) and have about 1037490174x more ads so see him.

[@billlyons7024]

Your videos are a bright spot in this crisis. Thanks for making them.

[@MoreChazImages]

Great start, you kept it interesting - just like your books - and a spherical cow bonus, wow!

[@Bill_Garthright]

Yes, this was fascinating! The last time I had a physics class, I was in high school,... and that was more than 50 years ago. So what I don't know about physics would fill a whole library - a very _large_ library. But this was absolutely fascinating. As you say, it's a great start to the series!

[@smjain11]

Sean this is really so good. Don't have enough words for your selfless contribution in tough times. Kudos

[@tecnoblix]

This is a great series! Since you are already home and in front of your computer you might as well learn 'ya some stuff. His history of Conservation really brings to mind the importance of language, and how we are constantly constricted and limited by the words we use to describe our reality. Many words have a religious or spiritual connotation forcing many to infer those properties into scientific understanding. So frustrating. I suggest reading The Sacred Mushroom and the Cross by John Allegro to get a better understanding of how important the meaning of our words is.

[@cwmbran-city]

During the demon of all shitstorms, this series has been immense.

[@KieranGarland]

Great idea for a series. Thanks for sharing.

[@Tomyb15]

I have a question: What's the relationship between conservation of energy and conservation of momentum? That is to say, how are they related to each other? For example, I notice that one way to get kinetic energy from momentum is to integrate with respect to velocity, but what does that even mean? How is that interpreted? The best I can do is that changes in energy (with respect to velocity) are caused ny momentum, but I don't think that's quite it and it isn't satisfying at all.

[@muffntheB]

literally half of this vid answers that question, try watching it, he even writes out the formula for you

[@mohitbansal9935]

This is more meditation than education. Thanks Sean 👏

[@luizgrocco]

Great video professor, I'm proud we are popularizing science through KZbin and other medias nowadays, keep up the good work!

[@mementomori8991]

Sean, you the best, forever. Another one.

[@Jason-bg7jc]

Awesome video, Sean. Thanks for making these! Can't wait for more!

[@DaZugZug]

In looking forward to watching all these videos. Thanks a lot for these.

[@sportsrevisited9699]

23:17 i don't understand how a jump is made to conclude the "universe is not alive"? no where in Leplace's demon can it be derived that the universe is not alive simply because it is being described as a clock. a clock is merely a system, biological system is also a clock as any system is, meaning they follow rules or the cease to be. it is logical to imagine the universe could be alive for the reason it begat life and still be consistent with Leplace's demon. you ask the question "how do we understand ourselves as living beings in a universe that is not alive?".....there just is no basis for concluding the universe is not alive.

[@edherwick6995]

Great. Very enjoyable...well done.

[@manvendrasomvanshi2515]

I think you should have mentioned symmetries and how they are connected to conservation laws (Noether's theorem). I personally think that Noether's theorem is one of the most beautiful things that exist in physics. I know that historically it came very late, but still I it should have been mentioned.

[@bpcinstitute]

Yes, please talk about conservation and symetry!

[@davidgregorygodwin]

Thinking about symmetries helps me through these principles. Noether's theorem helps keep books balanced when converting various forms of energy from one form to another in an effort to conserve the total amount of energy. Is this accurate, how are the two different?

[@manvendrasomvanshi2515]

@@davidgregorygodwin Noether's theorem states that for every symmetry of a Lagrangian there must exist some conserved quantity. ( A Lagrangian formalism is basically a way to summarize a law in one equation and it helps us understand the law.) A symmetry in the Lagrangian means that if I transform some quantity in the Lagrangian then the Lagrangian itself does not change. For example if I translate my coordinate system by some arbitrary amount then the Lagrangian is unchanged. Then according to Noether's theorem there must be some conserved quantity. In this case the conserved quantity is momentum. Another example is rotation. The Lagrangian is also symmetric under a rotation of coordinates. This time the conserved quantity is angular momentum.

[@fizikus2512]

To take lessons from Sean Carroll!!! I cannot belive. Fascinating.. Thanks very much..

[@adrian.tabirca]

Amazing. I wish I had you as a physics teacher in my middle and high school.

[@DaKoopaKing]

Loved it but it was too short! I would've loved to hear about Noether's theorem and how conservation connects to higher level physics.

[@jeannieh3661]

Ok Bowser AKA King Koopa. Just kidding great comment I just wanted an excuse to say "King Koopa" lol💙😇🐼💯

[@iainmackenzieUK]

For the attention of GCSE students, (17:30) Kinetic energy is a scalar. This is why we can "just add it together " :) (Momentum IS a vector)

[@YashMRSawant]

I don't want to be history enthusiasts here but as far as force is concerned, force is a quantity that is very consistent with concept of energy and momentum. How come Newton developed those laws without having the better understanding of concepts such as momentum and energy @14:30. I am sorry if am being so naive.

15:00 You can easily hand someone some momentum - it's called "a push".

[@Trucmuch]

You missed the point. Of course, you can change momentum, that's how physic works. What he was explaining is momentum is not a thing. You don't hand someone momentum, you give them a push and *then* their momentum change.

[@Gunandrunandgun]

​@@Trucmuch And this is called "a woosh".

[@jbchina9202]

Bravo, sean. Estoy leyendo tu libro y esto lo complementa, thank you y saludos

[@Broken_robot1986]

Great video, explaining concepts with as much history as possible, using history to explain them is just the best. Thank you! You should consider guest host to take over in case you run out of time with too many projects.

[@mitchellhayman381]

Physicists are the greatest people in the world. This knowledge is fantastic

[@coecovideo]

like this new format thanks Sean

[@DavidleViseur]

Absolutely brilliant, deeply thoughtful and lucid in so many ways!

[@AxelPatapov]

Me: telling myself I'm growing as a person as long as I keep watching and learning something from your videos.

[@fredwinslow744]

What an amazing approachable lecture On a topic that unless someone maintained math physics and other acumen would potentially be in an accessible for the didactic approach teaching often takes I think about these things all the time life does not allow me to return to first principles and what a wonderful alternative to still feel like you can understand concepts when a good teacher appears Having done high school and university level physics only I can tell this series of videos is going to be extremely enjoyable inspiring and possibly very educational Apart from my own enjoyment I am certain there will be people who will be motivated in either direction to the didactics and first principles or to be inspired and some other way Thank you for this

[@robertford1960]

Nice lecture. Thanks. On the very last part regarding the meeting between Aristotle and Ibn Sina, another fairly specific advantage of the conserved-momentum/friction point of view would be that Aristotle would no longer have had to rely on his hopeless air-currents theory of arrows. Instead he could have just said that air just doesn’t generate much friction, which would be easy to show empirically. I like to think that Aristotle, who was a genius, would have leapt at this insight!

[@karlwilkinsopn]

genius of physics

[@tharofleshcolouredeyes2301]

I succumbed to my strong urge of psychically giving a thumbs up at the end of the video, your excitement is really infectious Sean, looking forward to more of these :)

[@TheAlchemistZero1]

What is space? The seemingly infinite black void/vacuum that we have named 'space', what is it comprised of? If space is infinite in three dimensions, how can it have a shape? Does "Equal and opposite" apply to our universe? If so, what is the equal and opposite of our universe? If the speed of light is limited, why is entanglement instantaneous? What kind of debris (if any), would a blackhole leave behind after it dies?

[@arturos_ideas]

The original, unmoved mover! What a super bright mind, that Aristotle.

[@2false637]

Here’s a question: How does conservation of momentum hold in the context of quantum mechanics?

[@primus4cameron]

22:46 ...as he said, with a subtly sly smile.

[@alansilverman8500]

Still conserved - just look at the solutions of the Schrodinger equation for the hydrogen atom...different eigenstates correspond to different values of momentum.

[@rad858]

@@alansilverman8500 No they don't, they correspond to different values of energy and angular momentum. But it's true that momentum is conserved in QM. Emmy Noether's work put these conservation laws on a precise mathematical footing in classical mechanics and classical field theory, and her theorems carry over very neatly into QM and QFT.

[@Lucky_starfishI]

2 False quarantine

[@johnm.v709]

Watch "spin of indivisible particle" on youtube...

[@dbzdak]

In Herbert Butterfield's book The Origins of Modern Science, he also emphasizes that this change from seeing "resting" as the natural state of things to seeing motion as the natural state was a huge turning point in science. See especially the first essay in that book.

[@fakepivot]

love this new format!!

[@wrongtimeweeder1076]

@0:38 Why is it so difficult to draw the left bracket exactly opposite to the right one?

[@indream6318]

Im so happy!!! Thank you for all you do and for starting here with Conservation of momentum. When Neil deGrasse was asked about the most counterintuitive, peculiar law of physics and I was wondering what will he say, that would feel more stranger to me than that. Whatever he said was not as impressive for me as to why things just keep moving unless any of its energy is exchanged and why moving through a vacuum is free. It just seems like a key to something. Well, just a minute into the video, excited to learn something! Thank you again!

[@arc6fire]

hey, i was wondering why a neutron with zero charge can turn into an electron/proton(20.30 in video)? it kinda didn't make sense in the context of conservation as they have different charges?

[@felipemonteiro5877]

Excelent content as usual, Sean! Thank you! I learned a lot, and look forward to the next ones!

[@ErnestGWilsonII]

First let me say thank you very much for taking the time to make these videos and share them with all of us. I couldn't help but notice you went from Galileo to Isaac Newton and skipped over Johannes Kepler. Thank you very much for the explanation on BCE and CE as this is much preferred over BC and AD. I am of course subscribed with notifications turned on and thumbs up.

[@SpaceCadet4Jesus]

@08:20 Are you suggesting mereological nihilism (the study of wholes and parts-how things are composed of parts)??