the concept of mass

[@kailkay]

Thank you for not mentioning Descartes too early in the video. Most professors and teachers have a habit of (all too often) putting Descartes before the course.

[@stormwatcheagle5448]

Get out.

[@KyleBaker]

Loved the delivery.

[@migBdk]

Ba dum tish

[@indetigersscifireview4360]

Ugh! What a dad joke.

[@thornkirinsdottir9032]

"one million years' dungeon" 😂

[@rakino4418]

My favourite Newton fun fact is that he wss appointed Warden of the Royal Mint, which was apparently meant to be mostly ceremonial but he took it super seriously and went undercover in bars and taverns to seek out counterfeiting operations, which he then attempted to prosecute.

[@cubedable]

Yeah, he was also involved in transition to coins with milled edges to prevent shaving

[@acollierastro]

Well I love this fact. Sounds like something Newton would do.

[@waprile2506]

that he managed to prosecute with terrifying effectiveness. Newton was every bit a genius as a Warden of the Mint and an investigator as he was a genius physicist.

[@descentplayer]

Wasn't he also into alchemy?

[@fixed-point]

​@@acollierastro You should read Neal Stephenson's Baroque Cycle series. Historical fiction which in a broad way revolves around how things like modern financial systems came to be. Newton is a recurring character. Fantastic books.

[@garak55]

The "I'm a medical doctor, I took one physics class, I understand relativity" bit made me cry laughing. As a physicist working in a hospital, I feel seen.

[@Broockle]

I did relativity in highschool. I know all the physics 🤣 Tho years of consuming physics content on youtube did make me aware of the difference between relative mass and rest mass at least.

[@garak55]

@i^2 Keep it Real 𝕿𝖍𝖊 𝖀𝖇𝖎𝖖𝖚𝖎𝖙𝖎𝖓𝖆𝖙𝖔𝖗 when they acquire a certain level of seniority, medical doctors are just never challenged anymore. They are mostly surrounded by nurses, students and doctors in training who would never contradict them. When you come with your physics background and tell them "no, light just doesn't work that way" sometimes they get mad. The opposite is also true with younger doctors who are scared of giving any opinion on any of the scientific output of our collaboration. Surgeons especially think they can just offload a bunch of biopsies on our lap and be done with it like we don't need a clinician input in our analysis. Even funnier when they demand first authorship while being completely unable to explain any of the plots on the publication lol

[@garak55]

​@i^2 Keep it Real 𝕿𝖍𝖊 𝖀𝖇𝖎𝖖𝖚𝖎𝖙𝖎𝖓𝖆𝖙𝖔𝖗 I don't know what to tell you. It's pretty well know that medical doctors tend to have giant egos. Ask literally any nurse lol I'm not a GR expert, I'm a laser guy. I never claimed to be an expert on relativity, I was citing the video from Angela. On the other hand, I know light, I know optics, I know laser-matter interaction. Over the course of my phd, I had to spend a lot of time explaining to very smart cardiologists that the heart is not transparent. They thought we could just "do endoscopy and solve cardiac arrythmia". So yeah, like I said, light doesn't work that way lol As for surgeons, I don't want them to do the histology (they couldn't if they wanted to) but when we're writing a paper in collaboration, they need to do science. Just cutting a piece of cancer that you would have removed anyway and putting it in a dish is not first authorship worthy, sorry. Doing the exact same thing they always do and learned at school is not new science. So when we ask for a clinician to write the clinical part of the paper/grant or to do some litterature research or come up with some biological reasoning for why we observe this or that and all they tell us is "I cut, you do the rest", it's kinda frustrating. Especially when they then complain that you don't publish enough to further their career. Nonetheless, I wish you a lot of success in your chosen field :) Doctors are a pain in the butt to deal with so i need to vent sometimes but the science is worth it. Good luck with your phd entrance exam!

[@Beer_Dad1975]

When I was starting out in my professional career & needed extra cash, I did part time IT work at a number of General Practice medical centers - I got to know quite a few of the GP's quite well - and had quite a few discussions about maths and physics with some of them because they knew I was a recent engineering graduate - they were mostly pretty ignorant on these subjects, even by my own standards of relative ignorance. My point is, MD's working in General Practice are most definitely not scientists.

[@Beer_Dad1975]

@Prodigious147 LOL, not at all, first of all I'm a New Zealander, not American, and second of all, I'm just pointing out to the uninformed that a GP is not a scientist, nor do they actually have any grounding in science, other than the obvious gross understanding required of human biology and pharmaceutical medicins. I personally had no expectations for someone trained in treating human ailments to understand much about physics or math, any more than I would say, a plumber, or a mechanic - but a lot of people do seem to think GP's are experts in all manner of things well outside their training.

[@peterk7931]

The best description of getting a degree I've ever heard is "Every year we lie to you a little less."

[@JasonFahy]

I teach chemistry and I feel this. "What we taught you last term was simplified; let's take another look at it." Repeat endlessly.

[@AB-et6nj]

What if I told you that your whole life will always be a lie

[@suomeaboo]

i like to call those simplified models taught in earlier years as "lies that lead to the truth"

[@jaidei4732]

I appreciate what you are saying here about teaching something wrong as a "teaching technique." I'm a retired Math & Physics teacher. There is nothing more frustrating than trying to "un-teach" something a student mis-learned years ago because it was "easier." I still had students telling me that you can't subtract a bigger number from a smaller number because that was what their elementary teacher taught them 10 years ago. People remember that first leaning episode more strongly than several later correct teachings. To those that teach, please, either teach concepts correctly the first time or just say "you'll learn about that later." I found when leaving it as a mystery to be learned in the future half of the students were curious enough to research it on there own; and those who didn't at least didn't have the wrong idea implanted. As a Physics undergrad I was also taught about rest mass and relativistic mass. That was totally unnecessary.

[@1005corvuscorax]

you said "I still had students telling me that you can't subtract a bigger number from a smaller number because that was what their elementary teacher taught them 10 years ago." So, correct me if I'm wrong, did these students not understand the concept of acceleration vs deceleration in mathematical terms?

[@vynneve]

You are telling me after TEN years, those students would claim something like 1 minus 8...had no answer?? They would have gone through years of basic arithmatic and stuff, I am not buying that at all lmao. I agree with the principle of course, but that example can't be true (maybe I'm misunderstanding it?)

[@viliml2763]

@@vynneve I'm happy for you. I'm happy that you are blissfully ignorant about how difficult it is to teach children who are in the bottom 20% by mathematical aptitude. Please never ask a math or physics teacher from a less-than-prestigious public school about that subject or you might regret it.

[@imacds]

When she learned arithmetic in elementary school, I tried to teach my little sister that 0/0 was an indeterminate form (using simple language). When asked about it at a family event a while later, she excitedly exclaimed that the answer was "calculus". 😂 As in, it required material learned in calculus class. Technically, it requires limits from pre-calc rather than calculus proper, but I like the fact I was successful in conveying the idea that you can do it later rather than the idea that you can't.

[@jeremymullens7167]

Oh man I hate that. I think we should start teaching integer math right when a kid does that. It’s not different than adding or subtracting normally it’s only your frame of reference changing and most kids have some concept of negative already. Minecraft is very popular and it uses negatives in its coordinate system. Every kid understands the concept of owing something. Positive and negative numbers could be a foundational thing but it’s not so I just teach my nephews the right way and they confuse their teachers. I will say common core math is largely a step in the right direction. It teaches good math sense and sets up foundations for algebra. The general issue I see is teachers with a strong background in math are moved away from early education.

[@OmnipotentNoodle]

7:00 When Descartes talks about "extension," he means extension into the physical world. Essentially, when something has the property of "extension," that just means it takes up space. This is especially important to the philosophy of Descartes, as he was a mind-body Dualist. This means he believed our conscious, thinky-thinky bits are a separate thing that exists in a different manner from physical, material stuff, like matter, which has the property of extension. He also asserts that extension is the ONLY property possessed by matter. When we experience matter through our senses, we can detect smells, and flavors, and how it reflects light, and what it sounds or feels like, but these aspects are only things that we "presuppose [as] extension," which is to say they are not properties inherent to a "bodily substance" i.e. matter. Essentially, the ONLY property matter possesses is that it takes up space (it is EXTENDED into the material plane), and everything else we perceive about this matter is simply our interpretation of this extension. All attributes that could possibly be ascribed to matter are only ever different expressions of its extension. Its a philosophy that's still relatively relevant today, surprisingly. If we think about olfactory sensors, for example,,,,, smell isn't a THING. Smells don't exist. Smells are our thinky-thinky bits interfacing with and creating an interpretation of matter through the SHAPE of a molecule (the shape of matter amounts to its extension). Even with sight, we are interfacing not with a REAL sensation, but rather the "shape" of the light (amplitude, frequency, wavelength). At least that's how I understand it from my philosophy course, please lmk if i got something wrong ^^ anyway its also kinda funny bc Descartes was EXTRAORDINARILY devoutly christian but was constantly playing with ideas that got christians angry at him lmfao. look up "descartes evil demon"

[@kyay10]

It saddens me when people get ostracized by their religion for things that, if thought about for a bit, actually can reinforce the "wisdom and creativity of God" more. I'm a religious person and I toy often with these philosophical ideas, and I find that it provides a modicum of "insight" to how a deity views the world They created. In a way, it's an escape from our human-centered approach to understanding the world, but there's still human elements to our understanding, of course. It's simply fascinating to me that there can exist formulations of how our world works that rely less on what we take for granted, and instead get at something more basic and fundemental (like things taking up some space out there).

[@SpaceWizardAzrid]

i bet if descartes had access to some dmt we'd have all achieved enlightenment be now

[@KarlFredrik]

You are a born public speaker. I'm very impressed with your presentations. Not many people can structure a talk with such focus and present it in such a relaxed way for 1h+ without ever stuttering.

[@MisterRubbertoe]

Heh… I came here to say that I’m sold on what she’s telling us here in this vid - and it kinda blows my mind and makes me question myself, and how convincible I must be, cuz this isn’t anything I ever learned. 😏 Granted, I’m half past middle aged and went to a rural high school… heh but yeah, weird how I stayed engaged thru all of it either way. 🤷🏻‍♂️😏

[@userasdf]

Well there are like a ton of cuts...like any utuber but yes she is an amazing public speaker regardless.

[@mikaelbiilmann6826]

Agree. I also find it fascinating that she expresses herself as much through her nose as through her mouth. Hahaha, just an observation of the nasal American accent.

[@pfalango]

Amen.

[@3katsime]

@@redfernpixelgnomepitcher1377 what the hell are you talking about

[@sovietcranberry]

Tangential to the off topic discussion at 38:45, I love the mention that we did not know how stars worked until relativity. My best friend and I each have half of a series of books called "The Books Of Knowledge" (which is just a great title). It is an encyclopedia published around 1912, but had significant content-altering revisions over time. I believe I have the 1940's edition. Point is, that while perusing the book, I came across a fascinating question in a Q/A section of the book which goes as follows: "When will the sun run out of oxygen," to which the answer was some flavor of ¯\_(ツ)_/¯. The question implies a belief that the sun is literally just a space bonfire, so there is evidence of the general public wondering about how tf the sun did its shenanigans even significantly after the 1920's.

[@benb3928]

..ah nuance. It does run out of Oxygen. 🤡

[@bijova]

i wish i could save comments on tiktoks too

[@Meewee466]

Funny how we still dont REALLY understand stars or their luminosity

[@ICanDoThatToo2]

There's another brain worm that suggests you can't actually smush atoms together, the repulsive force is too strong. All fusion is due to quantum tunneling.

[@Tinil0]

@@benb3928 Technically it doesn't.

[@mehill00]

I’m a research physicist and once was talking with a physics teacher/instructor and he started talking about relativistic mass. Since he taught it a lot and I never thought about it the kids (we were at a cub scout event) nearby probably thought that he understood things better. I was just kind of stuttering saying, “uhh, nobody thinks about mass like that anymore…it’s the old way” and he smoothly stated “no, mass increases with velocity and that’s why the speed of light can’t be reached.” The pyramid thing really helps to explain the situation. Enjoyed the video!

[@howdyfriends7950]

39:51 i literally commented on one of reviewbrah's videos "wolfgang pauli lookin-ass" back in like 2015 when he was blowing up, i've only been watching your channel for two days but i'm consistently impressed how heavily you're focused on the real issues

[@Huntracony]

I think what some teachers forget is that you can just be honest about lying. You're not lying to conceal the truth, you're lying to make things easier to understand. Just tell them that.

[@edgarallenhoe3518]

That's what I was told in high school (and I think middle school as well, actually) about the model of atoms she showed. "This is technically wrong bc x, but it's good for understanding y."

[@marymegrant1130]

This presumes the teacher actually understands that what they are teaching is a simplification (lie).

[@shreychaudhary4477]

That's why our high school physics teacher always tells us when she's lying to us. It is honestly an amazing teaching strategy.

[@JasperRLZ]

my favorite Newton trivia is that there's that quote about understanding and appreciating the pre-existing research and scientific record: "If I have seen further, it is by standing on the shoulders of Giants", except, that's really not at all like Newton to do that. he was writing to Robert Hooke, one of Newton's many arch-rivals. Hooke was also somewhat short. Newton was just bragging about being taller lol

[@algorithmgeneratedanimegir1286]

While smart people tend to "know just how much they don't know," geniuses tend not to be humble at all. If you ever meet some one who I'd humble about their vast intellect, you can be sure they aren't geniuses. Why? Because geniuses lack social cues what they make up for in raw confidence. They are the smartest in the room... nay, region, and they know it. While people who are smart not only retain social awareness but have it enhanced by their intellect, which means they definitely don't believe what they are selling, but realize it's the best thing to say socially.

[@stephenspackman5573]

@@algorithmgeneratedanimegir1286 And your proposed mechanism that removes social awareness from geniuses would be…?

[@psychohist]

@@stephenspackman5573 The experience of being right all the time when everyone else is wrong. If you are never the person who is wrong from grades k-12, you don't learn how to deal with someone else being smarter than you. You just assume everyone else is stupid, or you think everyone else is also a genius but got taught wrong. Neither leads to being humble.

[@stephenspackman5573]

@@psychohist That honestly doesn't align with my experience, which is that smart people's personalities follow similar distributions to other people's. Some of them are nice, some of them are b*stards, some of them are sensitive, some of them are clueless. It may be true that being exceptional in some regard helps you succeed despite some other drawbacks-being smart, like being beautiful, or athletic, or rich, will let you get ahead _despite_ a terrible personality, and thereby exposes that terrible personality to more of the world, but I don't see evidence around me that goes beyond that. Unless you have very high standards in humility, and think that people should hide their talents as a matter of principle, of course.

[@garrettfuller5456]

@@stephenspackman5573 a genius which lacks social awareness is probably autistic to some significant extent. Geniuses that are not autistic (though I dare not say neurotypical) don’t often lack social awareness

[@robertgreen7593]

You were very kind about Brain Green docs. I watched one of his on String Theory and the only knowledge I gained from it was that strings are little multi-coloured circles that make wind-chime noises and float around your head.

[@stephanieparker1250]

Yes 😂

[@dixztube]

😂

[@mroutcast8515]

You could just keep it short and say he's charlatan 🤣🤣

[@yeepyorp]

My teachers in HS and basic undergrad chemistry mentioned probability clouds and mentioned that it's pretty complicated so we don't get into them and I learned so much about chemistry and other subjects just from teachers admitting that they're not giving the full background; I was that 3rd grader talking about Bose-Einstein condensate when my teacher talked about 3 states of matter (much to her chagrin) but knowing there was so much more out there really helped me get interested in science; I really hope more educators catch on to this because it made school so much more engaging for me.

[@GSBarlev]

My _least favorite_ physics professor revolved his whole teaching style around epistemology and basically saying: "Everything you've ever been taught is wrong. Nothing is truly knowable. There is no 'fundamental truth.' There's just math that works and mental models that help us remember that math." Looking back, he was the one professor who influenced me most profoundly, and I wish I'd taken more courses with him.

[@walaraubo]

@@GSBarlevI had a moment like that, in college for electrical engineering. I hadn’t questioned my circuit diagrams, I just solved my puzzles like I was told to do, until Emag, when we had to learn how everything was moving inside the wire. We were shown reflections, and calculating all of it, and it was like “oh, the circuit model is *okay*? I’ve spent the past 2.5 years working with low-res estimations of reality, perfect”

[@eucherenkov]

Your videos are amazing. I'm a philosophy student whose biggest disappointment in life is not being a physicist, and these videos are some of the best I've ever watched.

[@EthanHuntMath]

10/10. I was lucky enough to have a professor in my sophomore modern physics class as an undergrad who really hammered this point home. Love hearing you talk about that physics life, I kinda miss it sometimes but then I remember how miserable I remember everyone in grad school being and how they really aren't that much better off now.

[@kim15742]

What did you choose to do after graduating?

[@ce5983]

And what the grad students do?

[@ingframin]

You should seriously consider make instructional videos on KZbin. You have a natural ability to keep the audience engaged even when you explain a subject like this.

[@undeniablySomeGuy]

i wish she would make instructional videos on youtube explaining concepts such as the concept of mass, unfortunately we do not live in that world. i will await the day

[@UnforsakenXII]

Nice name, bro.

[@JewettMusic]

Like... How to make a particle accelerator.

[@johnaustin704]

I definitely agree!! Please give us more!!

[@PrettyVicious]

Maybe i would’ve been an astronomer, if so.

[@moleman1976]

Don't know how your channel came to my algorithm recommendations, but I've now watched three +1 hr videos in a row, so you've earned a subscription! I love the passion you put into your arguments, along with the clear frustration about the state of public understanding of modern physics! Looking forward to more!

[@teodorene344]

Thank you so much for this video. I never imagined the day would come when I would get representation in the media on this particular topic, and it's definitely validating.

[@swooper74]

My favorite thing about this channel is the way she takes some of the most complex concepts in science, hears "explain like I'm 5", and presents these topics with the kindness and patience a decent person would show to a literal 5 year old, instead of the sneering contempt most of the internet associates with that phrase. Thanks for explaining these complicated subjects like I'm actually five.

[@karltonkemerait5485]

Thank you sooo much!! I am 70 years old and have no formal background in either mathematics or physics but I enjoy reading about them and trying to get a handle on some general concepts and there is NOTHING more confusing than the myriad number of ways and definitions that seem to exist for similar concepts, in particular "energy". At least half my time is spent tracking down actual physicists to talk with them and have them clarify all of my misunderstandings and bad assumptions which are a result of sloppy use of language and educators trying to "dumb down" concepts and as a result teaching them incorrectly. Thanks for doing it right!!!

[@TheJohnblyth]

I still resent the Bohr model of the atom, after knowing about it for more than half a century. I feel that telling lies to children is a stop-gap, band-aid fix that covers a failure to understand the issues well enough to communicate them effectively. I feel that time dilation and length contraction are similarly poorly dealt with, leading to things like the Twins Paradox that really shouldn’t be pradoxical if the issues were properly laid out in the first place. Part of the problem is: of the people who are drawn to physics, only those who have a real affinity for mathematics at a high level of abstraction survive even fairly basic physics study and tend not to be great communicators to people who need more concrete examples, which turns out to be most people. Crude concrete examples are worse than abstraction, and I’m sure they kill the enthusiasm of a lot of children who might otherwise have brought more vitality-and better communication-to the subject. Yeah, this video hit a nerve. I’ve just recently discovered your channel, and so far I find it refreshing and enjoyable.

[@uXses]

So goddamn right, I think the Bohr model and finding out it's not accurate is a big reason of why I never liked chemistry.

[@jeanf6295]

The Bohr model as it was laid out back then was pretty neat : you take the planetary model of the atom with circular orbits (which does not work because accelerated charges radiate), and you assume than the angular momentum of those electron can only take some multiple of a constant value (that happen to be the Planck constant), and you get a set of discrete energy levels. If you further assume that the electron can jump from one level to the other by absorbing or emitting photons, you can predict a bunch of spectral lines, reproduce the Rydberg empirical formula, and tie the associated constant to the electron mass and charge, coulomb constant, and Planck constant.

[@lunam7249]

i agree with your time dialation....bohr atom i use sucessfully daily...it accomplishes most everything in "real life" engineering

[@denizersoz7012]

I think this all starts at simplification of Math. It is all very fixed and one-dimensional. Can we not teach kids probability and multi-dimensions from get go ? And then imagine what would those minds can come up with going forward !

[@lunam7249]

@@denizersoz7012 yes! your correct! however the elite are INTENTIONALLY dumbing down the education system....they just want dumb simple taxpayers, moved business to china, the usa has been imploded many years ago, the falling has been taking 40 years....gen z cant change a car flat tire....and me and you hope to teach "n-dimensional" dynamics? i have seen hope in 1/100 genz rebels, they dont cell phone, 1 minute /day internet....despize social media.....research tech on thier own! there is hope!

[@wargreymon2024]

This is gold, I didnt expect almost an hour lecture over the history and concept made clearer like never before. You inspire me!

[@andrewrush399]

As someone who has consumed a lot of popular physics and has concocted a lot of crackpot theories (which I have NOT emailed to physicists and never really thought were true, but just enjoyed coming up with them), it's both exciting and kind of crushing to be shown in such ab entertaining way that you actually have to do the math... with the right formula no less. Thanks for the videos. Subscribed

[@beansnrice321]

Love how reflective you are on these subjects. You stand out on a platform(youtube) that tends to promote more reflexive styles.

[@devongrey4135]

Fun fact: Sickle cell has been shown to be adaptive on a population level. Human with sickle cell trait (single recessive allele) are highly resistant to malaria. There is a high degree of correlation between environmental risk for malaria exposure, and prevalence of sickle cell in local populations.

[@c.r.parish5908]

One of the factors that drove the slave trade.

[@userasdf]

Thank you for mentioning this so I didn't have to. Evolution works surprisingly well. We have enough time for it to work out well. Theres of course a number of situations where it doesn't due to how things were set up before (and as she mentioned, it didn't select for things after an individual has kids) but for the most part it makes good sense. Sickle cell effects you even in your teenage years too.

[@Norbal.]

iirc there's another example of this same thing but with a disease more common in Europe

[@stuartdryer1352]

​@@Norbal.And more recently an example of a different gene encoding a protein called ApoL1, which in certain variants makes people relatively resistant to trypanosomes that cause severe neurological disease (African sleeping sickness), but which markedly increase risk for adult onset kidney disease.

[@yrazu05]

Biologist here. Evolution does not work by "correlations" but by "cause and effect." Organisms do not change by a 1 out of 1000 occurrence, that is anecdotal when it comes down to it. There are specific statistical models that drive this, which is why the p value of 0.05 is used to identify statistical significance. This is why the current "cancer debate" bothers me, as half brained doctors want to blame "genetics" to cause the vast majority of cancers. Less than 5% of all know cancers have a source of mutations, while the other 10% is found to have an organismal and environmental cause. Yes close to 85% of cancers we have no idea what is their cause, but more and more we have looked into evolutionary disease and how certain environmental factors drive this cause. I have met plenty of people who have never smoked in their lives, yet they develop lung cancer. Looking at data, the correlation of smoking is not a causation of cancer. Do not mistake "risk" for causation.

[@ModCounter]

"You know what holds the quarks together? Gluons...get it?" 46:10 Perfect delivery, I couldnt help but laugh out loud. Excellent Video once again, I learned a lot.

[@TeslaRifle]

Is an antigluon called a gluoff

[@d3nza482]

@@TeslaRifle Pullon. Though I'm more biased towards dissolvon.

[@natgrant1364]

@@d3nza482 Dissolvon. I like that. :) Though that also makes me now think of Solventon...

[@AkbarAli-bs4eq]

Yay and best wishes! A thousand subscribers here, a thousand subscribers there, and by this time next year you’ll be well beyond 100k Then again I don’t know how to math and you probably could (in your sleep) use the current rate of growth to do such extrapolations In any case you’re great and us fans all believe in you!

[@acollierastro]

That's really nice, thank you!

[@aryaanbasu6447]

this aged like fine wine

[@Denny_Boi]

I appreciate these video's so immensely. It's like I'm at a tea time at a seminar and having a casual chat with a physicist. It's very real and personable.

[@Hyo9000]

This video was very illuminating, thank you ❤ Btw regarding sickle cell disease: it’s believed that it’s been selected for since its appearance, because having 1 or both of the alleles of that gene as the SCD makes the subject resist malaria. And apparently the gene for SCD is recessive, so one can have 1 copy of it, not get the disease, and still not get decimated by malaria. :D

[@Waywardpaladin]

Because you still have phenotypically misshapen blood cells with one copy of the allele, but still enough healthy ones to not have it effect your health too significantly. It is why sickle cell is not selected for in areas without malaria because the heterozygous organism isn't as healthy as the homozygous dominant one.

[@judeaisling8913]

​@Waywardpaladin This is correct but (no offense) I think phrased somewhat awkwardly. All RBCs are diploid in humans and will all have the one sickling allele for beta-globin, and individual RBCs will vary in functional versus sickling Hb but generally sickling in heterozygotes only occurs under low oxygen conditions (such as when more oxygen dissolves into tissues during exercise or at high altitudes). The codominant phenotype under normal conditions is actually variable/patchy concentration of normal Hb, not sickling. This is because the allele is not causing the trait directly, the mutant protein subunit is, and alleles can be differentially regulated for stochastic or deterministic reasons. It's true that heterozygote advantage only exists for HbS in regions with diseases like malaria but it's worth keeping in mind that deleterious alleles are not magically cleansed from the population by evolution anyways and some combo of geographic isolation and drift can fix recessive alleles with deleterious phenotypes (e.g. Rh- maternal phenotypes predisposing infants to erthyroblastosis fetalis) in the absence of selective pressure. Hence stable extinction rates in the fossil record even after sexual reproduction gave an efficient way out of the Mullerian ratchet.

[@bowenmadden6122]

The...subject? Interesting word choice. Did you discover this experimentally-in a supervillainous underground lab chamber, perhaps? >:)

[@kevinwiley5325]

I love these videos. I just finished your newest String Theory video and then the Post Doc Exodus video and now I’m here. You’re extremely relatable and I’m happy to see someone in my age group discussing issues in modern academics and physics and is largely dominated by wealthy people in their 60’s+. Really looking forward to anything you talk about.

[@Sonex1542]

For me it's not the age thing... It's that she knows her shit and is really good at conveying it to others.

[@familykletch5156]

I really enjoyed how you walked through the history, including the asides with "yeah, this was ultimately found incorrect". Keep it up!

[@hatmonkey3103]

When I decided to make a career pivot to physics, I was recommended to read T M Helliwell to get a foundation in special relativity. For those interested, great book. All you need is trig (and some patience). Helliwell is very deliberate in always using "m" to mean mass (the only mass), and avoids mentioning "relativistic mass" until an appendix (F) of the same name, which in short, says its discussion is not preferred.

[@acollierastro]

This looks great, thanks for the rec

[@starseeing]

What field did you pivot from, if you don't mind my asking?

[@hatmonkey3103]

@@starseeing Electrical maintenance and repair.

[@MrMeltdown]

Would that be this book? "Modern Classical Mechanics" by T. M. Helliwell (Author), V. V. Sahakian (Author) or another? Thanks!

[@hatmonkey3103]

@@MrMeltdown T M Helliwell also has a book titled "Special Relativity" on the topic of ... special relativity. The cover has Einstein riding a bike in space. Hopefully this helps!

[@thehashbrowns6505]

Found this channel yesterday. OMG, you are fantastic! Thank you for the high quality, in depth, content.

[@bump_versino]

so i watched your string theory video, and now i'm binging your channel. As someone who read a lot of pop science as a kid and studied physics up until about 2nd year university, i'm probably who you are talking about when you talk about the "science interested public" in that string theory video, i'm excited to find a channel like this that ties together things that i sortof (don't) know in an engaging way with just the right amount of math. you're a great science communicator! this channel reminded me that physics is interesting and fun

[@rafaelalmada723]

The cool thing about these longitudinal vs transverse mass is that quasiparticles in condensed matter often have an apparent "mass" which can be broken down like this. It's weird, but it's great that it didn't just come out of nowhere.

[@acollierastro]

I noticed that when I was researching this video! It seems like the condensed matter people have lost their way....(joke)

[@TheOnlyAndreySotnikov]

In condensed matter, it is called “effective mass”, which is a clever trick to consolidate Bloch's functions.

[@rafaelalmada723]

@@TheOnlyAndreySotnikov I think they also show up as an inertial operator for magnetic skyrmions in topological insulators.

[@jinzodude]

I know it's a month later but small semantic point about evolution. Genetic mutations are random, selection pressures and environments not so much. If you have an accurate picture of a given environment and the selection pressures found in it, and the strength of those selection pressures, you can accurately predict the traits you would expect to see in a given population within that environment

[@jamesphillips2285]

(2 months later) I still think it is more accurate to say that evolution selects for what works; not what is optimal. Evolution is not able to "refactor" code, so you get workarounds like the vagus nerve: which takes a circuitous route through the body.

[@NME1012]

I came to the comments to make this comment (but found yours). I love this channel, but the evolution analogy was way off the mark and was fundamentally incorrect. Genetic mutations are random, but macroevolution is definitively nonrandom. Even the selection for a "negative" trait like sickle cell anemia is non-random, given that it increases resistance to malaria. It's not hard to imagine how this would be an evolutionary advantage in populations at malarial latitudes prior to modern medicine.

[@passtheyaoi]

@@NME1012 (image of a plane with a bunch of red dots near the edge of the wing, around the cockpit, and tail)

[@franki1990]

@@NME1012 IMO the analogy was well used if you consider 'evolution' and 'relativity' as two big categories and also popular concepts which are subject to a lot of interpretation and handling at the curricular level. We end up with fundamentally wrong nuclear beliefs as a result of such "teaching method" and that's what I think she's critizicing on this whole video.

[@janoschlenzi4757]

Great video! I've been investing some time myself to convince several people (even with a BS in Physics) that there's only one mass and that the latter does not change for moving bodies, no matter the velocity, since m is an invariant of the Lorentz group. It's surprising how people feel it hard to change ideas they've accepted as totally true.

[@davidrogers8030]

PS: most of the mass of plants comes from air rather than soil.

[@peterk7931]

"[N]ot an argument of syntax. This is an argument of semantics." What a precise way to frame the discussion.

[@derek2479]

I just found your channel. This and your other videos are great, I've got some catching up to do. Old engineer, not a physicist, but I still recall catching a glimpse of the wonder in quantum mechanics classes in grad school. Loved the shout-out to Reviewbrah at 39:52

[@BleakStarshine]

I found your channel today off of reddit and I really like how data driven your thinking is. Will be looking forward to your next video, keep up the good work. I really liked your glass video, the mass video, the flouride video and the spider video; I learned a lot. As a hopeful first gen academic I learnt a lot binge watching your channel today. I also enjoyed(?) your videos on SA and women in science. I sympathise and I thought the videos were illuminating on a bunch of figures that I had no idea about. Any who, good luck with the channel, will be looking forward to the next video.

[@feorge4972]

I imagine this kind of dumbing down plagues every field of science (mathematics, sociology, economics, whatever). really cool to see things like that disproven!

[@paris_mars]

I feel like math is kind of the other way around. You learn the elements of the thing first (limits and Riemann sums). Wrangle those into something more coherent (formal definition of a derivative). Then use that to derive 'tricks' that, after you've found them, you can just apply directly (rules for differentiation).

[@ryanh7167]

​@@paris_mars eh sort of. Then you get past your basic calculus sequence and get to real analysis and algebra and things become very involved again. It's definitely a thing with a lot of humps and valleys with an overall slope towards your mathematical maturity increasing.

[@paris_mars]

@@ryanh7167 Oh yeah, I didn't mean that calculus is the end point, I was just using it as an example. I picture the whole process as something like a sawtooth wave. Still, the tricks usually (not always) come after the definitions.

[@ryanh7167]

@@paris_mars I think that's a fair way to look at some things. Maybe I have simply yet to see the downward slope part of the way on my first two years of graduate school. So far it seems (to me, I also could just be dumb as a bag of rocks) like PhD course level mathematics tends to exhaust the tricks fairly quickly unless you're in very special cases.

[@chromatec-video]

Absolutely love the presentation and stubborn determination to correct common misconceptions.

[@mhoeij]

Every KZbin video longer than 1 hour that I have completely watched is on your channel. Brilliant content.

[@patrickendicott354]

When you pronounced ether with a short initial e, I thought, "Why is she doing that?" I have have always heard it pronounced with a long e. I love your show😊! I love your humour😂! I love your willingness to explain details for laypersons like me who want to do want to be more technically precise. And you always make the video easy to watch. Best wishes!

[@hoppy6437]

I feel that same way about how they taught fractions in grade school. They taught fractions were these special things with special rules, but then you get to Algebra and learn they are just division problems you haven't solved yet. Everything about them suddenly becomes crystal clear.

[@takanara7]

If you learn about quotient groups and stuff you'll see they are actually a subset of the field of real numbers. (rational numbers, which contain the integers and natural numbers, but exclude irrational numbers like the square root of two, which can't be expressed as a fraction (or 'ratio' thus 'rational'))

[@infectedrainbow]

@@takanara7 Sure, but just knowing that fractions are just division problems you haven't solved yet. Everything about them suddenly becomes crystal clear.

[@kered13]

I don't think "A division problem you haven't solve yet" is a good way to think about fractions. This implies that a fraction is somehow an incomplete or at least a poor representation of a rational number. Presumably this view implies that decimal notation is somehow the "true" representation of a fraction. But in reality it is the other way around, you can't even represent all rational numbers with a finite decimal, and in practice it is much easier to work with rational numbers in fraction form than in decimal form.

[@infectedrainbow]

@@kered13 Well then they should tell kids that instead of treating them like morons and misinforming them. Look where that got us.

[@idontwantahandlethough]

Right? It's no wonder the general populace thinks math is either boring or scary: their only experience of it is memorizing equations and formulas they don't understand, of course they feel that way! When you're taught in a way that allows you to see how _and why_ things work the way they do, it makes a heck of a lot more sense. And what's more, it might even be interesting :) (obviously that's harder when we're talking about young children, but even then I think it could be done. For example, "division problems you haven't solved yet" is a super clever way to put it that would probably benefit any kid that understand division but struggling with fractions! Lol I hadn't heard that before but I really like it 😂)

[@ghost567ish]

Babe wake up, a new acollierastro video just dropped!

[@firstlast5304]

Yes honey...

[@WiseOwl_1408]

A tired KZbin meme .

[@starseeing]

​@@WiseOwl_1408Aren't they all?

[@PinkiePi]

​@WiseOwl_1408 Oh good, I'm glad other people are bored with this comment that makes no contribution to the topic at hand. Like yeah, we're all excited for the video. That's why we watch it. And Angela is fantastic.

[@Jammys217]

Just started watching your videos and I'm really enjoying them! Though I want to note that there is an evolutionary advantage for sickle cell anemia, in that it provides some protection against malaria. Definitely a trade-off but apparently malaria is more deadly. Always thought that was an interesting fact.

[@artiem5262]

I have a piece of paper that says I studied a lot of this stuff (and passed those courses) a while ago -- in the 70's, like last century. Your presentations are superb -- especially weaving in the history of how these things came about. Applause!

[@toddashton3774]

I listen to many lectures on various subjects on physics. I find your presentations the most enjoyable.

[@cygfreas6934]

great video!! you will be pleased to know my ib physics teacher in high school was sure to teach us that things do Not get more massive at higher velocities As I recall though he didn't mention the E naught equation, though its been awhile

[@griffing2523]

Fun fact: heterozygotes for the sickle cell allele are less susceptible to malaria, and the allele is enriched in malaria stricken regions. Certainly a steep evolutionary tradeoff, the immune system (including the immune system in a broader evolutionary context) is brutal. Neutral evolution and persistence of almost neutral deleterious alleles, especially lifetime traits that become harmful post reproductive age and experience damped selective pressure, is definitely super common. Interesting though that in this case, it is somewhat of a Red Queen situation, where population-level variation can maintain the species better than homogeneity. And while yes we certainly aren't evolving to get any smarter, parasites do tend to evolve in a specific way. If a pathogen is able to infect more people, or have an increased rate of transmission, then that strain will become more common. If a pathogen becomes too virulent, however, it loses some ability to spread from host to host (host dies or host can't move). Therefore, it will be outcompeted by strains that cause less host damage (at least, in the short term). Yes, rare genetic events occur by chance all the time that can do something completely unpredictable, such as recombination in a double infected cell (this is how we get pandemic-causing strains of influenza every century or so). But it is still true that pathogens tend to become attenuated to their host over time - especially following a shift in host range (like zoonotic leaps). Evolution is a certainly not a guided process, it's probability and statistics. But we understand broader trends, and are very successful at applying that understanding. For example, live attenuated vaccines are engineered via repeated passage. That is, you take a pathogen, infect a cell line with that pathogen, let it replicate, then collect it and do that again and again and again. You might passage it through a variety of cell lines, maybe even at a different temperature so it evolves to be more efficient at Not the human body temperature, depends on the pathogen. The live attenuated polio vaccine is still used in some places. Things don't evolve to be better, but when random variation in a population makes a thing more successful at making more of itself, more of that version of the thing will exist. Sorry i had to microbio info dump for a second, I love your content!!!

[@mmlvx]

I don't know what y'all were expecting, but this is NOT the Roman Catholic "mass" I grew up with. Very weird take on transubstantiation. (Sorry, just trying to give you more "comments Bingo" material. ;-)

[@acollierastro]

I wish I had thought of this joke.

[@KingBobXVI]

This was a very fun video, thanks for adding a ton of the history behind the discovery of all that led up to general relativity - standing on the shoulders of giants indeed. Also, I really like your presentation style, you answered the question "what if Jenny Nicholson had an advanced physics degree and did math and science videos" which I now regret not having asked before, but appreciate having an answer to.

[@mrjuno1]

Here to say I was the perfect audience for your talk. MIT in the late 1960s required every undergraduate to take four semesters of physics 8.01 8.02 8.03 8.04 (many freshman who took AP Physics in high school got credit for 8.01). One of the three courses was closely based on Feynman volume 1. Soon after graduating I turned to teaching general science and high school physics (which provided not just a paycheck but also a Vietnam era draft exemption). So in the space of a few years I not only learned that mass increases with velocity, I taught it too!

[@dannystrinden5277]

This was great. I sincerely appreciate the work you are doing, and I think it adds a lot of value to the world. At least for me personally, I have gotten a lot out of your videos. I really love physics, but haven't had very much opportunity to engage with it since I left university, except through videos like yours. You are *really* good at this - like one of the best physics content producers on KZbin good. I'm on board.

[@mmlvx]

Thanks for explaining what a "hadron" is. I had assumed Hadron was a famous scientist I'd never heard of (like maybe James Webb). And I guess I assumed there must be a small Hadron collider somewhere, maybe in Australia. I probably didn't even think that much about it though, tbh. (Hmmm.... what else am I stupefyingly wrong about? Never mind, we'd be here centuries.)

[@ictogon]

Large Hadron would be an amazing name

[@denim_ak]

She has a great video on how James Webb is actually not a scientist at all

[@senefelder]

James Webb was not a scientist

[@mmlvx]

@@senefelder - So I discovered, by watching the video! Good stuff.

[@artiem5262]

...You've set me on a (philosophical) Quest to identify the proper home for the Small Hadron Collider (sHC)... Well, the SSC was (to be) Texas-based (and Texas sized)... So if the sHC is US based, then Rhode Island, the smallest state? Maybe in the Hebrides? This is going to require much thought, much wine, and travel...

[@DavieboyLondon56]

Thanks for all the great compelling and entertaining videos. You have a real gift of communication!

[@sirsteadyeddie3478]

currently going going down a rabbit hole of all your videos

[@AnuragShrivastav-7058]

Love it. I am hooked. The concepts with the historical facts just flow so smoothly. Never realised its a 1 hr video. Looking for more.

[@silphv]

This reminds me a lot of how calculus is taught. I can clearly remember how the prof started with a pretty intuitive description of what calculus is going to do, from getting slope from two points with ∆y/∆x or area by filling a curve with approximating rectangles and summing their areas, and leading us right up to "but what if we could make the delta so small... infinitesimally small..." and it was like oh cool, yeah calculus, what a natural extension to what we already know, and then hold on there, now we have to learn limits for a while because actually you just cannot understand what calculus *really* is until you learn limits (which challenge intuition a lot more than infinitesimals), and why? because the real meaning of calculus is written with epsilon and delta and the language of limits. Except it doesn't have to be that way. It's another case of historical baggage, because at one time, the definition of calculus using infinitesimals, while very appealing to the intuition, was not mathematically rigorous. And making sure math was rigorous was the big new thing. Using infinitesimals in your equations was like using a 🌭 in your equations, you could get away with shuffling it around using some subset of algebra for a little while but ultimately it's just a picture of a hotdog and we're not too clear on what happens if you ilke, take its square root or something. So we get the fundamental calc equations written in limit language using epsilon and delta, and infinitesimals get to be a fun little way to introduce calculus that for some reason perfectly explains what it is you're doing but isn't the right way because math. Since then infinitesimals were shown to be rigorous and we got surreals and nonstandard analysis and all that. And so everybody started teaching calculus with infinitesimals like they should and everyone was happy and nobody felt like it was even more correcter to use the limits definition and teach it that way to new calculus students for eternity just because that was the way you had to do it in 1960. Maybe someday, I know there's some amount of push for it, I had a copy of a calculus textbook that taught with infiitesimals and it was much clearer. I found an article* just now talking about this and the benefits to teaching this way, including "making dy/dx an actual quotient rather than code language for limℎ→0𝑓(𝑥+ℎ)−𝑓(𝑥)ℎ" ... yes, the mysterious dy and dx, no no, don't try to math those, they're not variables, they're just like... notation. Like the integral sign. They tell you you're doing calculus. (So they're 🌭. Got it. Well done guys.) * link.springer.com/article/10.1007/s11858-020-01194-2

[@boneappletee6416]

This is super interesting, thank you!

[@drdca8263]

Ok but defining the setup for non-standard analysis is, kinda complicated? Like, you have to talk about like, the transfer principle and such, and you have to be clear about the distinction between first order and second order statements, and etc. ? Like, if you are teaching real analysis, is it really easier for them to learn about non-standard models of the real numbers than for them to learn epsilon delta definitions?

[@silphv]

@@drdca8263 No, I didn't mean that, non-standard analysis is not a first-year subject for sure. I'm not saying it should be taught before calculus (also wasn't saying anything at all about real analysis, but fwiw I think it's safe to say you need to learn reals before you can learn extensions to the reals, yeah). I only mentioned it because its development followed the development of the hyperreals and the formal treatment of infinitesimals, so I namedropped it for some reason, that's all. Infinitesimals were used to reason about a number of things in math long before they were formalized, calculus being one of them, so reasoning about intro calculus with infinitesimals really doesn't require getting deep into them (let alone non-standard analysis, which was invented much later). For example, dy/dx has infinitely small operands but they're "similar infinities" (students can easily see how ∆x and ∆y would be getting smaller proportionally) so it's not shocking when the quotient is a perfectly boring real number. The argument is just that it would be easier (in the intro calc courses especially) to keep reasoning about them that way instead of doing a hard detour into limits, and since infinitesimals have been well-defined for over half a century, there's no longer a good reason not to. So, to define the fundamental theorem of calculus with infinitesimals, you don't actually need all the advanced theory that came from formalizing them, it works fine with just a limited application of infinitesimals. If you're wondering what the big issue was that it needed to be redefined, the most credible reason came down to a fear that, if calc's definition includes this thing we don't fully understand, it's possible that some part of it or any later maths derived from it could be found to be inconsistent, which would have been a bit of a math disaster. (This also was around when the entire foundations of math was being questioned and eventually reformulated in terms of set theory, as it really did have some inconsintencies lurking in its foundations.) Of course, besides that valid reason for redefining it, there was also just a lot of good old-fashioned prejudice against new ideas that made the discourse pretty ugly, and _that_ is probably what has stuck around long after the legitimate reason became obsolete. (I personally remember feeling confused when we got to the formal definitions of derivatives and integrals... it always felt a lot more roundabout than the intuitive way it was described at the start of the course, and I didn't know why it should be that way. Later I learned it was because that formal definition _was_ roundabout, it was literally a workaround made for historical reasons. And it's a fine definition, it just might not be the easiest one for students first learning it.) From en.wikipedia.org/wiki/Infinitesimal : > When Newton and Leibniz invented the calculus, they made use of infinitesimals, Newton's fluxions and Leibniz' differential. The use of infinitesimals was attacked as incorrect by Bishop Berkeley in his work The Analyst.[7] Mathematicians, scientists, and engineers continued to use infinitesimals to produce correct results. In the second half of the nineteenth century, the calculus was reformulated by Augustin-Louis Cauchy, Bernard Bolzano, Karl Weierstrass, Cantor, Dedekind, and others using the (ε, δ)-definition of limit and set theory. ...which they did because infinitesimals weren't well-defined enough, which was true. Although those dudes were mainly totally against the concept and even mocked it, meanwhile others actually worked on developing it until it could be well-defined. Cantor, Dedekind, Russel, etc were great mathematicians. Just another example of how very smart people still get entrenched in their ideas of what's right or valid and then get petty about it. This is just funny: > Infinitesimals were the subject of political and religious controversies in 17th century Europe, including a ban on infinitesimals issued by clerics in Rome in 1632.[6] And eventually: > Infinitesimals regained popularity in the 20th century with Abraham Robinson's development of nonstandard analysis and the hyperreal numbers, which, after centuries of controversy, showed that a formal treatment of infinitesimal calculus was possible.

[@spinor]

I don't know how you could hear "but what if we could make the delta so small... infinitesimally small..." and not become extremely uncomfortable. Intuitively, if you make the ∆x smaller, it just becomes a smaller ∆x. That doesn't change just because you give it some name like "infinitesimally small". So I have to strongly disagree with the claim that limits challenge intuition more than infinitesimals, because I would have certainly objected to this kind of approach had I been taught this way.

[@MetalGearSamus]

Thanks for taking the time to clarify all this. As someone with an undergraduate in physics and who has just started teaching high school science, I can say there is a huge gap between understanding physics and understanding physics pedagogy. A lot of these 'lies' don't need to be told if students are given the tools to help understand the real complexity of reality. If you need to introduce misconceptions to 'simplify' the model, then you need to rethink how you are teaching that concept.

[@sophiehuiberts]

Your videos are so good! Informative, inspiring, and also fun. Keep it up :)

[@Randy14512]

This is part of the reason when I am talking about E=mc² I give the caviat that it is a shortened version of E²=(mc²)²+p²c². Now, normally, it comes up for me when describing the mass deficit in nuclear physics so I then show how the reference frame changes so little. Therefore, the momentum is negligible in the calculations. Then when writing it out to show that you can use the energy release to determine the mass deficit, I will write it as E=(m1-m2)c² but in this case, there is an intrinsic change mass.

[@disneybunny45]

I just found your channel and i love it. I love the long meandering story/lessons you tell!!!

[@ColeenLeevis]

This unearthed a lot of buried physics knowledge I forgot about from almost 10 years ago. Maybe you'll find it reassuring that one of the things I remembered is that my undergraduate (lower division, even) physics class that covered special relativity made sure we knew that E=mc^2, as written, only applies to non-relativistic, massive particles. I think we then talked about the more rigorous E_0 definition, but that part I don't quite remember.

[@firehawk128]

I'm loving your content and your energy. Please keep it up. :)

[@vynneve]

I've never ever heard of relativistic mass being taught as a literal thing, as in "this object *literally* gains more mass when moving fast" that's absurd. It's just a way of representing the situation, **as if** it had that mass, but of course it doesn't. It is outdated of course, usually just frame it in terms of inertia now. But there is nothing wrong with using relativistic mass as a mathematical tool. Honestly it's main issue people like Brian Greene explaining this in such a bad way, and skipping over details so important that no one actually understands what it's about anymore.

[@scottsanford1451]

I love you! Every video has me in stitches. The way you land all those nuanced punches on chosen ignorance is amazing. You're a Warrior. (epic battle cry) FOR SCIENCE!!!!

[@shitpostfella5528]

Just wanted to say (as an avid physics enjoyer, but not a student), that this 34:40 was the best explanation/calculation of time dilation and space contraction I've seen. I love your videos!

[@Lincoln_Bio]

Newtonian gravity is taught so badly in schools, I remember my physics teacher telling us to multiply mass by 9.8 to get the weight on Earth, and I said "9.8 what?" and he said "Don't worry about it." Well I worried about it, and it made me think physics was dumb, until I started learning physics for fun later in life and realised actually it's kind of awesome & I probably should have been a physicist, d'oh. (Instead I did chemistry, found I was fascinated by particle physics but excruciatingly bored by hydrocarbons and dropped out) Perhaps there's an alternate universe me doing interesting research because that teacher had just said "It's the rate of acceleration in metres per second per second, but you don't need to know that for the exam" or something. Bit of a microcosm of the focus on passing tests over actual understanding that put off me education in general tbh. It's interesting to learn of the issues with relativity in higher education, there seems to be this pattern in science education of teaching kids wrong, revealing a slightly less wrong version with a smarmy flourish that they have to learn all over again a couple of years later, and repeat until grad school, rather than building a proper foundation.

[@jamesphillips2285]

In post-secondary electronics I started using units to check my algebra. If you get the wrong units: they are either equivalent, or you messed up somewhere.

[@eddiewiller]

GREAT video! I felt like it was specifically for me because I definitely fell into the camp of sorta-kinda-maybe thought relativistic mass was a thing until I watched that exact Don Lincoln video you referenced and then was still sorta confused after that. And I completely agree with you about the lies we tell to children. It doesn't make teaching much more complicated to caveat the things we say in a way that doesn't make it a lie. But the fact that you DID include a caveat makes it so that some day in the future when the kid is presented with more in-depth information that contradicts the lie, it's not a betrayal. It's just expanding on that caveat. Like I still remember how BETRAYED I felt in GenChem when my professor told us that ionic bonds and covalent bonds are not actually different phenomena. We've just divided a single phenomena into two regions based on electronegativity difference simply because compounds with electronegativity differences in excess of where we draw the line tend to have certain properties while compounds with electronegativity differences below that arbitrary line tend to have other properties. But compounds that are kind of close to that line can be blurry as to which side they belong on. Like that's why we say silicon dioxide (literally the most common compound in the Earth) makes covalent bonds (because the electronegativity difference between silicon and oxygen is not high enough to cross the arbitrary line we drew that divides ionic and covalent bonds), but it's NOT a molecular solid as we generally expect covalently bonded compounds to make. It makes crystals like ionic compounds. And just the other day I was subbing in an AP chemistry class in a local high school, and they were doing a practice AP test that asked them which would have a higher melting point: CO2 or SiO2, and a lot of them were confused because the answer didn't say anything about molar mass. Instead it mentioned that because SiO2 formed a matrix solid, it has a much higher melting point than CO2. And I wasn't sure what to do! Do I double down on the lie and just say something like, "you just need to know that SiO2 is a matrix solid because it's the most common substance on Earth." Or do I potentially damage their trust in their teacher and tell them she's been lying to them all along? I ended up deciding to explain the lie but with emphasis that the lie is useful to believe because it makes it very easy to predict behaviors and properties in lots of situations. It's just that in some few situations, it is helpful to know that it is a lie. But even knowing it is a lie doesn't mean you are going to know SiO2 is a matrix compound. That's still just something you have to know. But WHY it's a matrix compound instead of a molecular one is easier to understand because it's close to the line we've drawn to divide ionic from covalent bonds, so having a mix of covalent and ionic properties isn't all that surprising. But man, I had SO MUCH anxiety the whole time while I was explaining that thinking, "You're going to ruin their trust in their teacher forever!" But it just wouldn't be a problem if we just included the proper caveats in the first place. That same chemistry professor that first told me that ionic and covalent bonds aren't actually different did a good job of caveating other stuff like the Bohr model and some of the other quantum stuff you mentioned in this video that is relevant to chemistry (binding energies, etc). And I felt like knowing those caveats were there made it easier when I took Modern Physics to incorporate the spooky weirdness that that class got into.

[@ryanh7167]

As someone who is very much not a physicist but occasionally deals with acoustic physics for his electrical engineering work, I'd say my biggest gripe also is with the kind of strange and dogmatic behavior around causal determinism. Don't get me wrong, causal determinism is a fantastic modeling convention and seems to work really really well in many problem formulations and physical experiments, but it's always felt very handwavey to me that so many physicists just kind pretend that aleatory uncertainty is just this fundamentally unconscionable and that all random processes are fundamentally observable if we've got the "right sensors" to arbitrary degrees of precision.

[@jontobin5942]

Thank you. This is absolutely a misconception I had and I'm now irritated that I was knowingly taught the wrong information because I turned around and unknowingly spread that misinformation to other people.

[@paulcaron-wm4tk]

Oh! Angela! I read that book when I was in fourth grade and I have never been able to remember what it was: Faraday’s book on the candle. Thanks so much for reminding me. I’m going to get it from the library and read it again. (I am 74 years old now)

[@biggiemac42]

I was fortunate enough to learn it as "E = gamma m c^2" in my freshman year special relativity course, mostly never got stuck in that relativistic mass swamp. E_0 is just when gamma is 1. Good video.

[@noneofyourbusiness4133]

Fun fact: newtonain dynamics is just a special case where the speed of light is infinity so all “relativistic” forces are canceled out… or I heard this at least

[@kered13]

This is correct. If you assume that the speed of light is constant, you can derive the Lorentz transform and all of special relativity. But this leaves the value of the constant c unspecified. If you pick c=infinity (or more formally, the limit as c goes to infinity) then Newtonian physics and Galilean relativity fall out. So we we can view Newtonian physics as a special case of Special Relativity where c=infinity.

[@StrawEgg]

Hi! This is a really fun video just by the format of how you do things alone (and it's on something I always wanted to know if there was a more rigid definition!), so I just wanted to say it's awesome what you're doing for youtube science. Came from the one video on string theory and isaac (not Newton), so I thought I'd check it out. I'm still watching it, but I'm pausing to make a comment because the argument you showed between Descartes and Newton really caught me by surprise since I read about it before, and as far as I remember it goes something like this: First, the thing about putting one's hand into space was not really Descartes, but in fact Archytas! It's a common misconception since the wikipedia is kinda badly worded, but Descartes' conception is not about a specific scenario, in an edge case, but about the property of extension in practice: He says that the fundamental property of bodies, of matter, of actual things (not inside the mind) is extension, which is basically: (1) it has to occupy some space, (2) other bodies cannot occupy the same space. By a negative proof, if there is an entity that doesn't occupy any space at all (~1) it doesn't really exist for us, since it can't interact with anything, make itself shown/known. This also goes for the other property, since if there were bodies that could occupy the same space (~2), they would be phasing through each other, and again, not interacting: for example, if you hit a billiard ball, and it phases right through another, this other one doesn't really exist. With definitions (1) and (2), he can connect matter to mind: A body that doesn't obey "the law of extension" would interact with nothing, be it in touch, sight, sound (for a more modern analogy, photons would go right through it, not bouncing back - there would be no difference between it and a vacuum), and for Descartes, it would essentially not exist. And so, (3) bodies must be perceptible to the mind. This is the kind of thinking behind his famous phrase, "I think, therefore I am." If there is a given entity which for us presents no difference between it existing or not, we can discard it, and assume it doesn't exist. Beyond matter, and into thought, Descartes would go on to discard every knowledge whose existence could be faked by some form of illusion (optical or otherwise), only arriving at the single certainty that, whether what he perceives is an illusion or not, it's a certainty that he is perceiving, and therefore that he exists. Bodies can't be proven to exist, but if they do, they need to have the property of extension, of being able to be grasped by the senses, and so by thought. Mind can be proven to exist, but only as an entirely formal truth (I am), without any content to it (all can be doubted as illusory), and thus bodyless, unextended. There are many reproaches to Descartes' thought at its most radical on the basis of Atheism. Since he doubted the existence of everything not given to find a deeper truth, it would also be necessary to think, "what if God is an illusion?" at some point. Also, even assuming matter does exist, bodies must, can only really exist if they had extension, if they were susceptible to being perceived in some way, which therefore casts doubt onto an imperceptible God. Finally, (and this is the argument I think Newton is really trying to make) there is the fact that Descartes' philosophy is inevitably subject-centric. It's not hard to classify his philosophical branch as the one that you go for if you answer that if a tree falls in the forest and no one is around to hear it, it doesn't make a sound: argument (3) says bodies have to be perceptible to the mind, and if you equate that to extension, you essentially admit that things might stop existing the moment you stop looking at them, and begin existing again when you return to looking... which was easy to link up to Atheism when at the time it was considered a narcissistic position, whereas the religious one evoked images of community, of things existing independently of perception thanks to God's will, etc. Except, of course, this argument is a misrepresentation of Descartes! Although in his thought it's true that (3) bodies have to be perceptible to the mind, that's just an emergent property and not at all the definition of extension: again, it is only that (1) it has to occupy some space, and (2) other bodies cannot occupy the same space. Basically, it exists if you can interact with it; but it does not at all exist ONLY while it is currently being interacted with. Descartes is both less and more radical than that: less, because he admits the possible existence of matter outside, and completely independent of the mind; more, because in the question of the forest, he would say that even if he did hear or see a tree fall, what's to say it wasn't just an illusion? We're talking about entirely different philosophical levels here, of knowledge (epistemology) and existence (ontology), which Newton confuses severely.

[@ingeteloo3065]

such a banger comment

[@franciscodanieldiazgonzale2096]

One of the best comments I have ever read on social media. I never read Descartes in my history of philosophy studies. Congratulations, sincerely, and thank you.

[@franciscodanieldiazgonzale2096]

It would be great if you can remember the sources where you learned about Descartes. I do not doubt about their quality or accuracy, I want to learn myself!

[@narfwhals7843]

This was a very interesting video. I'm personally really struggling with the concept of mass and how it relates to rest frames, especially in the context of quantum field theory. You give Hawking's definition as "resistance to acceleration", which i think we have to take to mean acceleration from a given force via F=ma. But this is _exactly_ the thing that changes with velocity. A moving object will experience less acceleration from a constant force than a stationary one because of relativistic momentum increase. And that is exactly what all these "it's great for teaching!" folk are on about. Yay, we get to keep using f=ma and p=mv! I think this should read "resistance to acceleration _from rest_ ". And this ties mass directly to a rest frame automatically. It also immediately tells you that you can't have massive objects moving at the speed of light _by definition_ . But how the Higgs mechanism ties a field to a rest frame is a complete mystery to me at this point. So far my conclusion is the following definition of mass: "the term in the equation that makes it act like we expect from a classical mass"...

[@astronomerperson]

As a science educator trying to take this idea on in my PhD, thank you for this video! So often things are over simplified for seemingly no good reason and creates long lasting misconceptions. Cheers.

[@PHHE1]

The fact that this was basically a one hour ramble for 10 minutes of content, and it was still comprehensible, disproves the 'for teaching' argument very Hardcore

[@3tangents]

As a disabled person with an immune disorder, thank you for talking about the pandemic still going as an obviously true fact. The more we frame it this way the sooner we can get back to living in reality together.

[@wavydaveyparker]

This is brilliant. Newton was a weird guy! Now that's really funny. 😄 You don't expect me to watch and listen to all this fascinating stuff in its entirety do you? I only have the attention span of a goldfish...🐠 This is brilliant. I think Descartes was probably just trying to raise the issue surrounding absolute space, with Newton, but he didn't want to give him the time of day. You don't expect me to watch and listen to all this fascinating stuff in its entirety do you? I only have the... Anyhow, there is one other thing I've already noticed, and apologise if this sounds odd, but apart from obviously being very intelligent and humorous. You do have a tendency to keep going. Are you related to Inertia, by any chance? Thanks

[@MathCrazyProfessor]

I really enjoyed the video, thank you for your work. I am not sure but I believe that sickle cell does have an evolutionary benefit. I remember reading that people with sickle cell are less likely to die from malaria.

[@rsm3t]

That misses the point, which is that a debilitating disease nevertheless allows people to live fairly normal lifespans and pass the affliction on to the next generation. And males with sickle-cell often have low sperm counts and motility. Taken as a whole, the reproductive advantage is meager, but it's enough for the gene to flourish. Maybe Huntington's disease would work better as an example, as it develops later in life and so neither hinders nor enhances reproductive success significantly, except when carriers or potential carriers voluntarily abstain.

[@LuisAldamiz]

Yes: knots are speed, sea miles per hour to be precise (not land miles, sea miles are bigger, like 1.8 km). 60 knots however is a very high speed for a ship AFAIK, especially in 18th century.

[@seabecks]

Thank you for this video! I’m an engineer now and all I took away related to relativity when I studied basic physics in undergrad was that nothing goes faster than the speed of light. Adding the nought makes it make sense to me.

[@DanielStaniforth]

My biggest takeaway is that you absolutely DO get more massive when you go faster. Crackpots unite! It's interesting to think about the whole lying to children idea and your Pluto video. Sometimes I think it's okay to dumb down in order to give a broader picture of the universe, . I think this drops away when thinking about topics that are no longer for children.

[@G5rry]

Yes. When she talked about the model of the atom in the video, she mentioned that it can be useful. But in the case of E = MC2, it just confuses things (as is evidenced by the many confused physicists).

[@JohnShmidtt]

Nice video! But it left me confused on one point. Why does the thermal energy (which I think is just a disordered form of kinetic energy) count towards an object's mass, while the overall kinetic energy of the object does not. Does this have to do with frame of reference? Like, do fast moving things appear heavier from some static "center of mass" frame? If so, how is this different from relativistic mass?

[@lunam7249]

E = total combined energies, heat, atomic interactions , velocity squared , mass

[@Mankepanke]

@@lunam7249 so why is larger E meaning it interacts more with the apparent "gravity field" and cause it to have higher inertia?

[@JohnShmidtt]

To put the question more succinctly: do things appear more massive as they move faster when viewed from some static frame? If so, it seems a little arbitrary to say that relativistic mass is fictitious. It seems more appropriate to say that the mass of an object depends on your frame of reference. To drive the point home, consider a planet orbiting a star. If we calculate the mass of the planet on its own, according to the video (if I understand correctly) we are not supposed to include its velocity. However, if we want to calculate the mass of the planet+star system we do include the kinetic energy of the planet. So the question is, from this frame(the star's frame), which mass do we use to calculate the orbit of the planet? If the answer is the relativistic mass of the planet, then it seems appropriate to look at the mas as genuinely reference frame dependent.

[@lunam7249]

@@JohnShmidtt only object moving around 0.25c or faster begin a "relativistic" mass increase.....like, protons , electrons, nuclear collisions in a nuclear collider ect... planets and stars have velocities much slower than this...delta mass = 1/ [sqrt(v/c)]....nothing exciting happens until at least 0.1c.....

[@juliavixen176]

@@lunam7249 The "velocity squared" doesn't count towards the "E total combined energies", because it's always zero from anything's own inertial reference frame. The (mc²)² = E²-(pc)² version of this makes it clear that the extra velocity in the linear momentum gets subtracted from the extra velocity in the kinetic energy. So it all cancels out and the total mass remains constant. Remember, E=mv²/2 and p=mv classically. The stress-energy tensor makes this really clear. The 4-velocity in spacetime never changes. What you're calling "kinetic energy" or "linear momentum" is just an arbitrary chosen coordinate transformation into 3D space.

[@terenzo50]

One of my favourite one panel cartoons depicts an obvious Albert Einstein standing before a large blackboard upon which two equations have been crossed out, the first E=ma2 and the second E=mb2. And he's utterly lost in thought. (I've no idea how to superscript the 2.)

[@yourguard4]

Try pressing "2", while holding the key next to the right of the space bar (probably labled "Alt Gr") 😉

[@valentinorban209]

This is hands down the best video I've stumbled upon this year. Can't agree more on the teaching mentality.

[@post-modernneo-marxist8102]

So I believe that what Descartes is saying in the quote mentioned in the video at 7:25 which Newton disagreed with is that any thing (substance) which exists in the physical sense (i.e. in the way that , for example, a rock or a tree or a car does) has physical existence solely because it is extended in space (i.e. it takes up empty space and has a position relative to other things.) To give a plausible example which may persuade someone of this, something which is blue is only able to be blue because of the fact that its extension in space allows it to reflect light which when absorbed by human eyes is seen as blue. Likewise for any other property which a physical thing might have. This is in contrast to what he calls thinking substance, which if I’m not mistaken is the only other type of substance he believed to exist, which exists but is non-physical has its existence in virtue if its consisting of thought.

[@post-modernneo-marxist8102]

Newton’s disagreement at 7:56 , to the extent that I understand it, (there’s a reason Descartes is discussed equally as often for his philosophical and his mathematical contributions whereas Newton is not) is that Descartes’ position leads to Atheism which isn’t as silly of an objection as it might sound because Descartes was also deeply religious. The reason Newton believes this seems to be that by Descartes’ conception the property of extendedness in space has existed eternally and could not have been preceded by a state where extendedness didn’t exist which would make it more fundamental of a property that something can have than the property of being originally created by God. Furthermore, because the concept of extendedness as Descartes used it can be understood entirely without reference to God, (i.e. an atheist could agree with everything that Descartes says about extension and its importance as that which determines whether a thing has a physical existence without having to compromise their atheism) half of the two types of things which exist can be fully explained without god.

[@jameshart2622]

I find that this very often causes serious confusion with general relativity as well. People ask the sensible (as far as they have been educated) question "What happens when a particle is moving so fast it's mass becomes to large enough it collapses into a black hole?" In terms of the actual theory, this is nonsense. Every particle is stationary in it's own reference frame, and collapsing into a black hole is definitely not something a particle at rest can do. It's also not something that can be relative. Whether some matter has collapsed into a black hole is something all accessible observers will agree on. (Observers inside the collapsing black hole may or may not agree; that's been an interesting sore spot in the theory for a while. Since they are unavailable for comment after the fact, physicists have uncomfortably decided it doesn't matter.) This misconception comes from the belief that mass actually increases due to motion, _and_ that gravity is due to mass. Neither of those statements are actually true, but that's not always been comminicated clearly. (For the record, the resolution to the paradox is that firstly, particles only have their intrinsic mass as argued in this video. Secondly, general relativity has gravity couple to the energy-momentum. Not even just the energy; the energy _and_ momentum. A particle moving very fast has a lot of both, which means that gravitational effects from the energy can be cancelled out by the almost-as-large effects from the momentum. I don't know all the details, because General Relativity, but given that General Relativity simplifies to Special Relativity in the absence of large gravitational fields (which are reference-frame-invariant), this is clearly what has to happen.)

[@juliavixen176]

I wrote some other (longer) comments on this video about this exact thing. Kinetic energy and momentum are functions of velocity... which is relative, and zero in an object's own inertial frame. The 4-velocity is invariant, and it's an arbitrary coordinate system choice you make to call part of the 4-velocity momentum (movement in 3-space) or kinetic energy (movement in time). Anyway, only energy internal to the object (or arbitrarily chosen hypervolume of spacetime) is what counts for gravity. You're always moving at the same speed through 4D spacetime, with different amounts of that speed in the time direction or a space direction.

[@jameshart2622]

@@juliavixen176 Sounds about right. I know just enough about general relativity to be dangerous, so it's good to get confirmation.

[@rdbom4252]

I think what might possibly have happened is that in the olden days immediately following SR, 'm' used to mean relativistic mass = m_0(1-v^2/c^2)^{-1/2}, so E really did equal mc^2 But over time physicists, or at least particle physicists, found that they almost never really wanted to refer to relativistic mass and they almost always wanted to rest mass. They were like "Writing this '0' subscript all the time really sucks. We're just going to write m instead of m_0. Einstein can sue me." Fast forward to today and all physicists (or at least particle physicists) now only use 'm' to mean rest mass, EXCEPT in E=mc^2 where they understand it in its old sense of relativistic mass. But if you only think of m as rest mass then it's true that E=mc^2 looks really funny, and I can see why you want to change it to E_0=mc^2. But IMHO this is just about conventions.

[@davidrogers8030]

So, based on what you're saying, would I be right in guessing that 'there's just one mass' ?

[@reddannywambalam]

This channel has been a pretty interesting find for me. I was a Physics major in Undergrad. I did A LOT of internships, NASA, SSRL, LISA (very very different I know. Lot's of intern spots and not so many precocious undergrads willing to work for near-nothing. I came from relative privilege so accepting token salary to get in the door was on the table.) And... i didn't love it. I ground my way through the math and the mediocre professors. Loved the grad students and good professors... but I didn't love the science work I was seeing. And when I was in the NASA internship I really got to see what was on the PhD path. I didn't like what I saw, long years of obscurity and marginalization. I choose to jump to software. I look back at some of the study and work fondly. But the institution and the ... grind I couldn't justify. Love your videos, please keep it up.

[@benoitranque7791]

These videos are amazing, I giggled at your enthusiasm for the various equations

[@manso306]

That covid example wasn't very good, if I understand it correctly. "No one is guiding evolution" isn't true. Monitor the virus and try to limit its spread, and you exert an evolutionary pressure for variants that avoid detection. One way we detect it is by the symptoms it causes. It's not guaranteed to happen, but with each person carrying billions (trillions?) of viruses, it's likely I'd wager. (I'm no epidemiologist though.)

[@quintrankid8045]

There are other pressures as well. Depending on how the virus is spread, if it kills it's host, that particular population probably has fewer opportunities to reproduce and spread.

[@maclypse]

Agreed. I get simplified models, but we shouldn't teach half-lies for "pedagogic reasons"; it's causes no end of trouble. The first problem is unlearning what you learned every time you step up to a higher level of learning, and this should be avoided as much as possible. The second is people who never advance to higher level of learning and carry a lie with them for a life time. Both are bad. Sure there's room for simplified models, but there's no reason to teach "E=mc2" when you can teach "E=mc2+pc2 but for now we will focus on the mc2 part which is a special case". And man, the amount of shit I have had to deal with because teachers has said "don't worry about that now" and "just learn the formula" instead of just fucking telling me the truth and let me know why, for now, we will use the simplified case or just use the formula... Maybe this is how some people learn effectively, but for me it has ruined my science education. I am very disappointed. And oh, Newton was a total cook. He spent his later years dong ALCHEMY. Man's a poster boy for Autism Spectrum Disorder; I recognise much of that weirdness in myself.

[@SisypheanRoller]

Let's hope future generations don't think you're a cook for doing weird shit that's allowed today.

[@maclypse]

@@SisypheanRoller Oh, alchemy is still allowed today; it's still weird though. ;) Granted, the line between chemistry and alchemy was much blurrier in those days, but it's curious: being a religious scientist in those days was normal, but few scientists would delve into the occult with such fervor. He was odd though, unmarried for life, no friends, and described by his peers as mean, vindictive, anti-social, etc. So yea. He definitely seems to have been a cook. Reminds me of myself. We won't have to travel into the future to state the obvious; I'm pretty cooky too.

[@CaptainD0dge]

I don’t believe that teaching incorrectly is ever helpful. Take electricity’s comparison with water flow. That is very unhelpful when one is truing to understand what electricity actually is.

[@narfwhals7843]

But it is very helpful when one is just trying to _use_ electricity without understanding what it actually is.

[@amos9274]

I don't think so. That would be like saying ohms law is unhelpful because there is no resistance at quantum scale. I find water flow a very good analogy to electricity as every macroscopic and low frequency concept in electronics has an analogue in water flow and its behaviour can thus be easily imagined by people unfamiliar with the concept.

[@GH-oi2jf]

Practical electricity is rather far removed from a modern physical understanding of the subject. If you had to teach the physics of electricity to people training to be electricians, there would not be many licensed electricians.

[@skarphld]

That was brilliant. An explanation that was accessible even to a crackpot non-mathematical armchair physicist such as myself. (And I was actually taught, explicitly, that mass increases with velocity.) Don't worry. I won't be emailing you my "revolutionary" theory of everything. At least, not until I clear up a few things in a seance with Paul Dirac.

[@Genethagenius]

Thank you! Took your advice & taking some remedial math & physics to take them at a higher level. Grateful I can always return to these videos.