Cosmology Lecture 1

[@Incognito-vc9wj]

It's nice to be able to learn without the distraction of grades.

[@kurtwester5861]

Big fax

[@borjadetorres7747]

Amen

[@michaelterrell5061]

EXACTLY. 8th grade sucks.

[@black_jack_meghav]

@@michaelterrell5061 i get ya bruv

[@michaelterrell5061]

@@black_jack_meghav It’s nice to know someone cares.

[@mahakalkrishnaji1289]

I am. 82 years old.. I watch this to expand my knowledge. Thank you sir.

[@tanmayprajapati7852]

r u alive?

[@tasos1112]

are you alive sir

[@guidofeliz8384]

I am 59 and study math on my own free time.

[@LithiumBattery0]

@@tanmayprajapati7852bruh wtf is the question dawg .

[@RinnO977]

I'm 19 and I do the same

[@PurnamadaPurnamidam]

Sitting in a small island in the Indian Ocean and learning from such a distant place without any fear is what KZbin should be. Thankyou Susskind sir you are one of a kind.

[@emilianotristan3900]

I'm also in a island

[@PurnamadaPurnamidam]

@@emilianotristan3900 Nice Emiliano but which country u r from?

[@TheOmnipotence]

Are you from Maldives or Sri Lanka

[@PurnamadaPurnamidam]

@@TheOmnipotence Mauritius

[@TheOmnipotence]

@@PurnamadaPurnamidam Oh wow. The only African country that's very highly developed. (Maybe Seychelles will be too this year)

[@andrewstang-green3107]

I love that we get to experience a higher education, even without the money we are so fortunate to have this information public. The world is truly waking up! Thank you!

[@Frosty-oj6hw]

And I would say ideally support this by buying his books, they support the series really well and put money in his pocket for this fantastic work.

[@SapienSafari]

agreed

[@michaeljorfi3552]

@John no

[@skeeterburke]

now all we need is to convince Elon Musk to take some flat earthers up to the ISS so they can see Earth's curvature for themselves #hisnameisYehoVAH #RONWYATTWASNOTAFRAUD

[@darcyh1241]

I love listening to lectures as well. Dr. Susskind is an excellent lecturer.

[@Brian.001]

Leonard is 83 now, and one of the absolute best presenters of science on KZbin.

[@petergreen5337]

❤❤

[@janeg8536]

Loved watching this! I am a senior in high school planning on majoring in astronomy and I can't wait to learn more about our universe! Update: I don’t remember making this comment lmao, it’s been a long time. But for those asking I did get my undergraduate degree in astrophysics and I am now a physics PhD student studying gravitational waves! Update again: As of March 2024, I have officially passed my thesis defense and now have my doctorate in physics! I spent my time studying how noise can impact the gravitational wave detectors.

[@joniaui6809]

Jane Glanzer The universe is dark

[@frontl1ner]

Jane Glanzer been 3 years since your comment how did it go?

[@alexrodriguez9520]

Jane Glanzer how beautiful is your conscious expanding

[@awkweird_panda]

Are you through with your major yet? Do Let us know.

[@empty2110]

Jane Glanzer legend has it she will never tell us

[@ottofrank3445]

No fancy stuff just a marker and a whiteboard and you learn the universe! That's the power of sir Susskind!

[@bakersmileyface]

This dude is a legend. I've read so many of his books. I didn't realise he did lectures online for free and now I'm gonna watch all of them. Thank you for posting this. I am not very clever and am not confident in going to university to study this because it's a lot of money and time even here in the UK. But I'm really interested in it so I'm grateful that I can take my time to learn for free like this.

[@MrFancyGamer]

bruh it’s been 6 years since i’ve done high school math and I understood most of this, this professor is incredibly clear and makes it super interesting as well

[@jaz.923]

I doubt that anyone is still looking at comments here, but I feel the need to express my profound admiration and respect for Dr. Susskind. He is the wisest, kindest, the most patient, and certainly the most interesting professor I have ever listened to. Stanford students are extremely fortunate. I wish you well. Dr. Susskind, and thank you so much.

[@Mehlsack93]

you never know do you

[@Mehlsack93]

also I agree

[@RodneyAllanPoe]

"The Hubble...thingy." Thank you for uploading these. Gold.

[@nidhi4079]

Exactlyyy, i absolutely ADORE him!!!

[@LordOfThePancakes]

I thought it was rather unprofessional to refer to such an important & complex instrument as “the thingy.” Slap on the face to all the good people who dedicated years to working day in and day out on the entire Hubble Telescope Project.

[@nickgilbert-o8w]

@@LordOfThePancakes It's joke at a brief lapse of memory. It's not that serious.

[@saketrivedi]

​@@LordOfThePancakeshe said because it is not constant but named as Hubble constant

[@ibazulic]

Professor Susskind is an amazing professor, his lectures on whatever subject I watched were amazingly detailed and very methodical. And this one is no exception. Thank you, Stanford, for these lectures! And thank you, prof. Susskind, for allowing recording of your great lectures.

[@BoooDave]

I tell anyone who will listen... Stanford has several very interesting lectures online for all to watch. I wish everyone did the same

[@zetacrucis681]

Ditto MIT OpenCourseware

[@johnb4314]

A pleasure to view. Prof Susskind is an excellent lecturer in addition to the significant contributions he has made in his field. Thanks for putting all his lectures up.

[@3lit3gn0m3]

Even though I'm not an equations kinda guy, I'm glad to have the privilege of watching this, especially free and from home.

[@RomanDmosski]

3lit3gn0m3 what kinda guy are you then?

[@3lit3gn0m3]

Christian Rosenkreutz Someone interested in anything to do with space. o_O I'm not being graded, so I enjoy picking out the few things I do understand. :D

[@ABlackGuy10]

3lit3gn0m3 iry whistle "oooooweeeee ooooooooo"

[@3lit3gn0m3]

nostradomis Eerie?

[@andrewmartin9469]

3lit3gn0m3 Forget that, what the hell is talking about? +nostradomis

[@VidelicetMoi]

To be honest, this class (because I despise "equations"-- class 1, 2, and 3) is way over my head; however, the manner in which it is presented is above par. I will watch again and again and again to grasp the instruction.

[@ibn3670]

Thanks "Stanford" do helping the world to get into "the knowledge culture"

[@brianruppert1071]

My late brother would have loved all this. He passed in 2005, so he missed out on the transformational introduction of college physics courses free on the internet. Remarkable development.

[@ritemolawbks8012]

I enjoy his lectures and can listen to him for hours. If only there wasn't a language barrier, I would have loved to have experienced the classroom lectures from Albert Einstein, Isaac Newton, and Galileo Galilei. The Q&A sessions would have been legendary.

[@liamroche1473]

Minor historical correction 2: Newton was born 5 years after the Tulip bubble of 1637. He did however get burnt badly by an investment in the South Sea company, whose share price rose meteorically and then collapsed in 1720.

[@anilsrivastava3635]

Dear Susskind, you are one of the greatest teacher of all.

[@niyagentleman8143]

yess! ^^

[@Leismar]

Yeah. Great speaking😊

[@adamwatson7669]

No, I am merely pointing to the observation that all galaxies are uniformly receding from us at a rate proportional to their distance. The velocities of peculiar galaxies has been accounted for, and there is no discrepancy. The CMB can only be explained as the event when the universe became transparent, and the anisotropies observed from COBE and WMAP (1 in 100,000) match very well with the large scale structure of the universe.

[@sleepful1917]

my favorite branch of physics, i was so happy when I saw that lenny has lectured on it

[@kylemcgrath84]

I love Suskin, anyone who routinely says " It's called ****, but I'm going to intermittently refer to it as something else" is awesome! I love being kept on my toes.

[@marcusvaughn7019]

I am amazed with all of you guys who comprehend, what is in my opinion, difficult math. I tested with a 132 IQ, but I could barely remember my times table. I excelled in many of my classes, but could never master math. It wasn't until I was in my late 20's when I learned that I am very dyslexic and finally understood what was going on. If math comes easy to you, count your blessings and push yourself to the maximum in school. I envy you folks.

[@lsbrother]

I think - without being absolutely sure - that most of his lectures over last few years have been not to students but are more of an evening class for anyone interested.

[@neonblack211]

yes

[@JasonWalsh-b4n]

I AGREE. IT IS VERY NICE TO LEARN WITHOUT THE DISTRACTION OF GRADES.👍

[@kspangsege]

"If only Newton had been a little smarter" - LOL!!!

[@vanderdole02]

luckily we still have Huijghens :)

[@michaelterrell5061]

@@vanderdole02 What’s that?

[@jenromeave4793]

@@michaelterrell5061 HAHAHAH

[@jenromeave4793]

@@vanderdole02 Do you mean Huygens as in Christiaan Huygens?

[@michaelterrell5061]

@@jenromeave4793 What did I say something wrong?

[@DirtyZiggy]

6:30 - We cannot see in all directions while standing on any one spot on earth. The fact of the matter is that we cannot observe what is below us.

[@DirtyZiggy]

@@iron_labrador Not at all, you never can see below us while standing on this planet. Its just how it is....

[@DirtyZiggy]

@@iron_labrador Yes

[@kuckaf01]

Thank you from those of us who can not afford to attend college.

[@vukasinspasic6099]

Can't regret enough of pursuing a petroleum engineering career. This and few other related fields are my true love and interest.

[@CelticXAngel88]

These are ideal for those who either cannot afford college, who are lifelong scholars or who just cannot decide on just one major.

[@Badroucl]

Adding a subtitle when a student asks something would be useful for the completeness of the lecture It was an erudite lecture, thank you.

[@MegaLESM]

26:21 "I don't know what happened to my Universe, I had my Universe here, but..."

[@toomanydrugsinmysys5414]

Could have sworn it was right here, eh maybe I was just delusional. I’ll grt another one

[@anneneville6255]

It was swallowed by a black hole 🕳 :p

[@sunitalymon1925]

Then he simply drew it back. Dot dot dot 😂😂😂😂

[@FreakinKatGaming]

What's sad is No the fact that knowledge is easily obtained and can be found with curiosity and searching. The sad and frustrating part is, so few of us actually search and seek to learn more and more than the normal.

[@Aiden057]

Thank you Dr. Suskind and Stanford for this and all the videos you make available to us who watch here on youtube.

[@pvgaming1740]

How much indian Future cosmogist are watching the whole series. Thank you so much sir for making this video. Take my respectful blessings in yours charan

[@CERTIFIEDBABEWRANGLER]

Look ma, I'm in Stanford

[@TheGat2012]

The hubble constant as derived by about 25:00 requires that "a" is only a function of time and not a function of position or mass density or anything else. Has any work been done to explore the possibility of expansion being a function of mass? maybe expansion is not the same at the center of a galaxy as it is in the space between galaxies?

[@KaliFissure]

Isomorphic in general, but with an extreme variation in energy and mass densities. Sin(cos(u/2)cos(v/2),cos(u/2)sin(v/2),sin(u)/2) 0

[@EdSmiley]

"I don't know what happened to my universe." Suskind has a dry sense of humor.

[@xinzeng-iq7zv]

i am watching these lectures for the sheer thirst of knowledge

[@alphaenemy]

What a great find. A free Cosmology course? Thank you Stanford!

[@DAFANNIN]

Science is about the focus of your mind on the beauty of what you find in the very large, the very small and the very fast. There is a universe of fine detail in all of the scales. We live in an unprecedented age of knowledge. Never in the history of man has our perception spanned such an explosion of reality. It is entirely possible to be left behind in our old ideas and facts. It is vital that we be on the cutting edge of understanding. We are not immortal.

[@mietschj]

This made me realise I should be studying for my physics final next week...

[@Awesomemaro]

how did it go😅

[@abcde_fz]

OMG I got one right... After the joke about "What's the first thing we do when we set up a problem in physics, (or solve a problem), and it's not 'sharpening your pencil'?" He said "Set up your coordinates". I had guessed "Know your boundaries", so, I'm going to give myself one point for that one. Kinda' half right, anyway. I'm so happy I finally got one HALF right... :-)

[@jimkeller3868]

Have great respect for Prof. Susskind. I do not resonate with this particular form of teaching however. I usually like if some sort of overview is given first: what are the problems we are trying to solve? What is the direction that we are heading? It seems to me that rather than provide context, he keeps building small components without explaining why. It would be like explaining a combustion engine by starting with "this is a spark plug" "this is a piston ring" ..... He even says it at 39:19

[@Edruezzi]

The topic is cosmology. He said that at the beginning. The KZbin title says it.

[@liamroche1473]

Minor historical correction: Alexander Friedman is reported to have died in 1925 from typhoid, not in WW1. Susskind may have been thinking of Karl Schwarzschild, who died during WW1, but of an autoimmune disease while serving the Russian front.

[@bhavyajoshi3362]

The way he is he is explaining the things is really good and awesome to understand the point. looking forward to see the whole series. :D

[@rraajj_j]

bhavya joshi You indian I indian Doing different dfrnt

[@TravelTheGalaxy]

I am so very grateful for the information and knowledge Stanford and this professor are willing to provide. I would still love to learn about the deep history of where this all comes from. I know there is an eventual disconnect between belief and science but that is where my heart and mind pull me toward and I wish I could find somewhere that would bridge the two together.

[@nmarbletoe8210]

belief is said to be subjective and science objective. but, how to define objective? maybe it's basicaly the sum of all subjective views

[@Ukdroneshots]

I left school with no grades. I feel unchallanged in life. No college would accept me and lessions like this are what keep me going!

[@dracomalfoy5010]

So bro how are u doing now?

[@Awesomemaro]

brooooo where are u now?

[@Deuterium2H]

@Plautus. IMHO your arguments (and knowledge) are coming from "popularized" science books or blogs that have no actual mathematics or physics content. It does not appear you understand some of the most fundamental basics of physical theory. You even misunderstand Olber's "Paradox", which has in fact been resolved. I would strongly suggest you take some actual mathematical classes, and calculus based physics courses...and then move on to higher level principles (Calculus of Variations, etc.)

[@jceeross6763]

I just love these lectures so much thank you

[@adamwatson7669]

We can't manipulate time. It's directionality is set. We can easily manipulate coordinate systems. For example I could PM you a proof that Newton's force law is still valid under change of rotation. It seems that not only do you misunderstand abstraction in physics, you also misunderstand mathematics, which is exclusively general.

[@AGMRockstar]

I hope to go to stanford when i go to collage I am 14.

[@ymmi8542]

Did you end up going?

[@krazypotatofiend6933]

College* Also 2020 now, youre 21 or 22 or hell even 20, what's up?

[@pari_0152]

Same here 😮

[@yashahuja9027]

Lol

[@Awesomemaro]

did u make it bro

[@sciencefirst7880]

It's interesting to see the progress that's been made in ten years.

[@omersalman571]

I am an MSc Student from out of the USA and have watched 2 times this lecture video in 2021 and I need to watch it again but I am not sure why I will watch it again, to understand more or to listen to these articulate expressions :) thank you soo much for these wonderful lecture videos

[@user-cx5ni7me6l]

Thank you and thanks to everyone who made this video possible.

[@RedSquirrelEater]

This was my favorite course that he's done so far. I also liked the GR course, but this one was more enlightening.

[@adamwatson7669]

Perhaps I should have expressed the more subtle aspect of expansion. The galaxies are receding from us because they began receding from us. In other words, the universe expands only when averaged over a very large scale. You appear to indulge in emotional arguments rather than deal with the specifics of the argument. You're going to have to rectify your approach, otherwise we aren't going to get anywhere!

[@Purrebark]

You've gotta stop moving around so much. The students are gonna get a soar neck 56:46

[@XxxclarityxxX]

+Super Bork xD

[@stephenphilbin3919]

+Super Bork For most people, the motion is not a problem because they have vertebrae in their neck to allow for this sort of thing.

[@selimhassairi]

I do this a lot too, I understand him x) Really, you should give it a try, it helps you to keep focused, it also gives you a pace

[@jimkeller3868]

His motion has nothing to do with it. It's the fact that the camera is following him with each motion.

[@81atanas]

you are unbelievable...

[@cacogenicist]

How can we have these very large-scale structure -- i.e. galactic superclusters, and the larger-scale galactic threads? Is there an increasing amount of space between the galactic clusters within the galactic threads? An increasing amount of space between the galaxies/locally bound galactic groups withing the clusters? Are galactic threads a product of objects within the threads being gravitationally bound, or are they just remnants of gravitationally bound structures in the very early universe?

[@sissichen8715]

Really learned a lot!!! Thank you so much professor Susskind!

[@Mike-uo2gg]

It's all backwards and wrong. The universe is not stagnant its moving its not moving in the same direction every where nore is it moving in the same direction outward or inwards its not contracting we are still expanding and accelerating. Look at the Eons channel check out the Great Attractor.

[@Onegod40-v4h]

Which book can I take along with this course?

[@qwadratix]

26:22 Quote:(Only a physicist) I don't know what happened to my Universe, I had my Universe over here but err.....

[@derpyorandom]

I'm in 5th grade and listened this in my sleep

[@ridhipalia4789]

What a lecture! Kudos sir! Such a knowledgeable one!

[@doggee09]

Which class ur?

[@Mike-uo2gg]

With this logic the big crunch is impossible the universe is accelerating so it can't crunch. With means there will be a time when we drift far enough away from every galaxy there will be no more stars. We don't know what the darkness of space is how it's created or if it can be stretched to the point of ripping apart as the expansion accelerates. If the reversal is possible at some point we will notice the expansion decelerate and stop. We don't know of the universe is finite or infinite. We don't know if we can over come the distance and movements of other galaxies to visit them. Our best chance will be when our galaxy collides with our nearest galaxy this will also reek havoc on our solar systems planets and or stars could collide destroying both galaxies or we will get lucky and we will merge smoothly with gravity helping keep things a safe distance ... but thats not how gravity works it draws in matter it does not deflect it like a magnet. I think there is a low likelihood of a smooth merging. More likely would be mutual destruction and the matter will create a new larger galaxy. Inorder to have a chance of serving we need to be able to leave the galaxy for awhile until things calm down a bit. We currently can't leave our solar system. Our sun's magnetic field protects us from other starts going supernova and plasma waves from hitting us as our probe got close to the barrier it reported a plasma field that would surely destroy our delicate DNA. So we need a spaceship that provides us with a magnetic field to protect us from all the radiation outside our solar magnetic field. Our sun is tiny compared to what we have seen out there on our own galaxy.

[@nickhyland4527]

These lectures are fantastic. Thank you so much!

[@ioiome9420]

I don't get it, the second part of the lesson is not correct. When discussing the two points/galassies, there are two scenarios possible. Either (i) the two points are within the same grid unit cell (which is not the case prof. Susskind makes, I guess) and therefore one cannot assume that ro is constant, or (ii) the two points are in different unit cells, meaning the sphere covers parts of different unit cells and within different parts (not whole) it is not given that the density ro is proportional to a³. Mass could be, and is, distributed not uniformly within the unit cell

[@literaway7714]

If you can find a center of the universe it automatically means that universe is limited

[@nmarbletoe8210]

every point is a center

[@lucyoriginales]

Do particles manage a volume? Shouldn’t it all be particle shaped?

[@trunkten5452]

Now I can proudly say that I am studying in Stanford University

[@mickeyj440]

LOL

[@Edruezzi]

Nope. You haven't registered.

[@Edruezzi]

Nope. You haven't registered.

[@tabascoraremaster1]

Can Leonard Susskind please calculate the effect of the Earth it's rotation that broke it's record with some milli-seconds ?

[@RinnO977]

Came here from Instagram.

[@nurlatifahmohdnor8939]

gerön (Gk) = an old man Page 83 MAXIMUM (age in years) 1 Marion's tortoise : 152 years or more 2 Human : Perhaps 120 3 Box turtle : Over 100 4 Alligator : Possibly 100 5 River mussel : 60-100 (some sorts) 6 Elephant (Indian) : 77 7 Sturgeon : Certainly over 70 8 Eagle owl : 68 9 Condor : 65 10 Halibut : 60-65 11 Cockatoo : At least 60 12 Silurus (a catfish) : 60 13 Giant salamander : Over 50 14 Whale : Probably not much over 50 15 Carp : 50 16 Goose : 50 17 Ostrich : 50 18 Horse : 40-42 19 Chimpanzee : 40 20 Clam : 40 21 Giant clam : Not known, but may be no longer than for small clams. 22 Goldfish : 40 23 Lion : 40 24 Large toad : 36 25 Newt : 35 26 Polar bear : 33 27 Cow* : Over 30 28 Pigeon : Over 30 29 Cat : Over 30 30 Most snakes : 20-30 31 Chaffinch : 29 32 Dog (depends on breed) : 26? 33 Sheep Over : 20 34 Gila monster : 20 35 Giant spider : 11-20 36 Queen ant : 16-19 37 Horseshoe bat : 16-18 in the wild 38 Rabbit : 15-18 39 Frog : 12-16 40 Gray squirrel : 15 41 Guinea pig : 10-12? 42 Earthworm : 10 43 Large beetle : Up to 10 years as adults (larval life may be very long). 44 Guppy : 5-6 45 Queen bee : 5 or more 46 Mouse : 3 1/4 47 Mayfly : 1 week or more Cow* No "usual" life given because many are eaten while still relatively young.

[@harrailiaskou725]

the more we know the more we know we don't know,actually...

[@thekkl]

harra iliaskou You know it's been a good day if you have more questions today than you had yesterday.

[@harrailiaskou725]

***** i totally agree with you! :)

[@fiddlesticksbessette398]

YOU WONT LEARN NOTHING IF THE ONE'S THAT'S TEACHING YOU DONT KNOW THEMSELF'S.'' SOME WERE BRAIN WASHED ABOUT 12 YEAR'S AGO.AND BE CAREFUL WHAT YOU HEAR,AND READ THESE DAY'S,AND I DONT CARE WHAT SCHOOL'S,OR COLLEDGE YOU WENT TO...EVEN YOUR PARENT'S WERE NOT TOLD THE TRUTH ABOUT SOME THING'S...LIES,JUST GO ON AND ON,AND ON.BE CAREFUL WHAT YOU TELL PPL,OR BELEIVE''BECAUSE IF ALL YOU KNOW IS WHAT PEOPLE TELL YOU,AND THEY JUST HAPPEN TO BE A DEAN,OR PROFESSOR,YOU JUST MIGHT BELIEVE IT MORE THEN IF YOU HEARD SOME ONE ON THE STREET TELL US.BUT TRUTH IS TRUTH,AND LIE'S,ARE LIES,NO MATTER WHO THEY CLAIM TO BE...FIND OUT WHO IS IN THE KNOW.DONT BELIEVE A LIE FOR 50 YEAR'S.CHECK THING'S OUT YOURSELF..

[@Denosophem]

What about the ones that just blimp out of testable existing but is still visible with the human eye?

[@Blackburrd]

Teaching students in Kenya using these lectures

[@starshiptrouter]

Thank you for posting this. I really appreciate it. (Note: That while Newton was a believer, he also would have known that the usage of thousand year periods in the creation cycle didn't literally mean 6,000 precise years but rather 6 creative periods. This is number symbolism and can be found by scouring through metaphysical books stores until your energy doesn't make it to zero and you collapse. But you will find it...also by a logical deduction of the old and new testaments...not a trivial task.)

[@seditt5146]

This is simply nonsense created by religion apologist attempting to integrate modern knowledge into subpar belief systems. Best to toss out literal stone age beliefs and catch up with reality.

[@starshiptrouter]

@@seditt5146 Have you studied number symbolism? "Religion without science is blind and science without religion is lame." -Albert Einstein

[@A_Dopamine_Molecule]

Might wanna start out by learning how to spell college.... Seriously though, good luck :)

[@scotttrent4721]

Mike Ehrmantraut is a man of many talents

[@tangytanger1ne]

Waltuh

[@geoforn]

44:00 If we want to think of A as something which doesn't depend on where you R then it had better B.

[@adamwatson7669]

The big bang made several important predictions, One such prediction was that no galaxy should contain less than 25% helium. This would be curious without primordial nucleosynthesis to explain the fusion of hydrogen into helium. You should note that stellar fusion always fuses helium into heavier elements.

[@silviawalker9759]

One is free to make inquires. I am learning however. That if I listen and pay attention. Eventually questions in my head will show up in the Lecture. Took a while for me to get it. dr. Serwaa, FMU.

[@DAFANNIN]

A gas does have weight. Pick up a container of liquid nitrogen or a welders tank of Oxygen and you can weigh the difference between full and empty with bathroom scales. Hydrogen gas when it is not extremely cold will not collapse under its own weight to form stars. The least bit of ionization and you might have one proton stuck to one electron in a cubic meter of space or maybe not.

[@adamwatson7669]

It isn't expanding into anything. That's a profound misunderstanding. It's expanding in the sense that if you pick 2 points at one time, and then measure their distance at some other time, they'll be further apart. Hubble's redshift measurements show an expanding universe, and we run the observation backward in time to come to the singularity. Further evidence lies in the CMB, abundance of helium, large scale homogeneity, time dilation in nova light curves....I could go on.

[@jasonbutler9362]

@20:00 if D is the actual distance in meters the delta x would have to be in units of seconds^2 as acceleration is in m/s2. What is the physical significance of a coordinate system in units of seconds^2 ?

[@MortimerYoung]

This lecture series is above my head but it's great to sleep to

[@TheSebascasta]

shouldnt the mass equation be based on a spherical volume?, seems like its asuming the universe is a box.

[@thorsteinssonh]

if it was isotropic but not homogeneous, yes it could be shell-like, but I like more the possible situation that it was more dense near the observer and less dense far away, or vice versa. This would maybe highlight to the observer that he is very special, all the stars and galaxies wanting to be near the observer, or... all the galaxies hating to be near the observer.

[@adamwatson7669]

No other cosmology can explain the multiplicity of astronomical observations we have obtained. These include the existence of the CMB, or the abundance of helium, or the Hubble law. The anisotropies do not "only make sense in a geocentric universe". That would be another profound misunderstanding of the facts.

[@GustinoDante]

Where can I go to find the theories and accepted scientific evidence that the universe will continue expanding despite our severe lack of knowledge of dark matter and dark energy? Also is there a place in the equations to account for virtual particles that lost their annihilation partner and others such as neutrinos that by themselves are negligible but when extrapolated over the the expanse of the universe could contribute significant mass?

[@imnotlettingyouseemyname]

Presumably, you can continue to watch these videos. I learned all about where that information came from when I took Cosmology and Relativity in college.

[@neonblack211]

The one logic gap I was able to get accross is how you choose a coordinate system such that all the points are galaxies, I don't see what allows us to do that, does that mean we are constantly thinking about a universe where all the particles are uniform and the same distance between them all,, but then if you added time It doesn't seem obvious to me that it would hold that structure under newtons laws........

[@rendikhwuanki2053]

Waiting for this guy to be appreciated as one of the most brilliant minds of modern times. Father of String theory ❤️

[@T8ersalad]

I playback at 1.5x speed and turn on Subtitles, only then am I able to capture the essence of what he is explaining in his lecture videos.

[@hagridishungry]

0:45 Why does he sound like Neil deGrasse Tyson?

[@Reaction1s]

@24:07 when is the rotation that cancels[engineeringly insig @ large; but observable] built into the grid? The grid needs to function large and small.

[@Reaction1s]

If you build the observed expansion in, and we observe rotation in things below cosmology, then, the grid needs to be insignificant but rep'd @ the largest scale.

[@Reaction1s]

...and if the necessit is a 3d-paradigm, then wouldn't the ground be the grid itself?

[@Reaction1s]

What if a lensed quasar image is more closely related to rainbows, then an ultimate bending by local G.

[@Reaction1s]

No, deform /-=¥

[@Reaction1s]

So if If's in fact, then the original dist is ? , and a constant of distance becomes legth, and question of circumvention becomes standard.

[@fertilizerspike]

I'm not talking about Arp's "contention", I'm talking about his observational astronomy, which showed quite clearly that "redshift" is no reliable indicator of either velocity or distance. He showed countless objects with vastly different "redshift" in direct physical contact, mooting your belief system. I'm well familiar with the collection of fables you imagine to be modern cosmology. It's based on less evidence than belief in deities. At least deity worshippers are proud of their faith.