The Biggest Ideas in the Universe | 22. Cosmology

The Biggest Ideas in the Universe is a series of videos where I talk informally about some of the fundamental concepts that help us understand our natural world. Exceedingly casual, not overly polished, and meant for absolutely everybody.
This is Idea #22, " Cosmology." Perhaps more a field of study than an "idea," but it is made possible by an extremely powerful idea: that our universe is uniform and simple enough to be understandable. We go through the expansion of space, the thermal history of what makes up the universe, and a bit about dark matter and the cosmic microwave background.
My web page: www.preposterousuniverse.com/
My KZbin channel: / seancarroll
Mindscape podcast: www.preposterousuniverse.com/p...
The Biggest Ideas playlist: • The Biggest Ideas in t...
Blog posts for the series: www.preposterousuniverse.com/b...
Background image: www.spacetelescope.org/images...
#science #physics #ideas #universe #learning #cosmology #philosophy

[@vikingthedude]

I love how Sean is just a bust floating in space. Like a Boltzmann Bust

[@jkonrad]

Two years later and I still love coming back onto these. ❤

[@takefivepaullucido]

One of the greatest communicators and ambassador of physics and cosmology since Carl Sagan.

[@adamjacobrogers9155]

I find it very appropriate and appreciate that Prof. Sean can manipulate math models and equations to back up his topics and lectures. I love Neal Degrass Tyson as a speaker, representing the cosmos and being a great science communicator and advocate but he never busts out any math to back up his lectures which for me, is not as impressive as Prof. Sean's grasp of and display of the math that underpins and proves most or all of his videos topics and shows way more how and why we have the knowledge we have gained as a whole. And why the universe is the way it is. Bravo Sir.

[@eugenekochnieff]

Sean Carroll’s gently spoken manner plus his ability to explain this material is just the most wonderful way for us in the public to gain some insight into the beauty and wonder that is our universe. These videos are simply a gift to all.

[@gonzobatano5352]

It's just amazing how knowledgeable Sean Carroll is and how well he presents complex stuff in an understandable way.

[@saintburnsy2468]

I fell asleep listening to this and dreamed that my former First Sergeant was actually my high school PE teacher, and that he happened to be very well-versed in cosmology for some reason

[@josephhall5681]

Made up. It didn't even sound cool either...

[@JimmyKnax]

@@josephhall5681 hello there little troll, aren't you cute...

[@jessemontano762]

Lol.

[@kf7558]

Well Sean Carrol does have quite the soothing voice.

[@wademichalski768]

I fall asleep listening to these every night for a month Atleast lok

[@lilrobbie2k]

I read Sean's books. I listen to Sean's podcasts. I watch Sean's videos. I spend a lot of time with Sean... and I love it.

[@nurk_barry]

He’s awesome, his books are something special....

[@jeffbass1165]

Isn't it weird to have a friend who knows nothing about you? lol

[@Psnym]

You’re not alone ;)

[@jeffbass1165]

@@Psnym Wouldn't it be "he's not alone"?

[@Psnym]

Jeff Bass *we’re* not alone!

[@ruppinstein6952]

Sean..Your content will be counted as a treasure as this playlist matures ❤❤

[@Psnym]

Sean: Cosmological Principle... homogeneous and isotopic... Me: DUDE! Did you finally get a haircut?!

[@adhdasian1896]

Denis Goddard Lol, I laughed at this. jsk, he explained in an earlier video in the Biggest Ideas in the Universe series. The last 2 Big Ideas were recorded before he got it formalized(cut).

[@iggatron]

@@adhdasian1896 renormalized

[@stevenbauer6090]

@@Psnym The Cosmological constant is a well known fixture of the Universe.

[@stevenbauer6090]

Fascinating,Sean keep it coming.

[@HawthorneHillNaturePreserve]

Sean Carroll is a superhero! Sir, you are the professor I wish I had and the professor I am so honored to have access to and could listen to you forever. What a mind and educator. Even when I don’t completely follow all the complexities, I find I learn something each time I listen. Your passion is infectious!

[@lindahope9538]

Thanks Sean. I learn a little more every time I listen to your podcasts/lectures. Thanks for taking the time to educate and inform us. And thanks for referring to Schrödinger’s cat as awake or asleep. As a cat lover, that is so much easier to think about for me.

[@stephenbryant7873]

I had a major in the humanities, but took a Cosmology course in college. In retrospect, I value that one over any other and still have my notes, decades later. I know a lot has changed in the intervening decades, and have somewhat kept up with the field. I’m looking forward to this lecture with special interest.

[@samcochran6599]

Sean Carroll, the Bob Ross of science

[@AngryDuck79]

0:49 My new favourite phrase is "the universe is the ultimate spherical cow."

[@paulc96]

Many thanks again Professor Sean. I didn't get to see this until the Wed morning, but it was well worth waiting for, as always. And one of my personal favourite topics too. As an amateur astronomer, who happens to find himself living in a Universe, and wondering about that, I reckon that makes me an amateur Cosmologist as well !! Thank you.

[@chrertoffis]

"We're made of star stuff. We are a way for the cosmos to know itself" - Carl Sagan "Our universe is the ultimate spherical cow" - Sean Carroll

[@guyxmas7519]

LOL!

[@willnzsurf]

Ha. A Carl Sagan vid clip popped up on my youtube algorithm earlier today. Last night I watched a Freeman Dyson video & a Richard Feynman interview a couple days ago. I'm glad other people enjoying these as much as I am. Lol😹

[@thereallightwarrior906]

Universe? Uni-verse? Hardly! It’s a novel at least; an epic, Opera, Trilogy, or Film series. And uni? Only one? Certainly multi is more likely, or at least a duet? So there is no universe, it’s a multopera! A Deutrilogy? A novel Multepic? C’mon, folks! Think outside the bun!

[@crab-dogjones4659]

Thanks for taking the time to do this. I've really learned a lot.

[@maisboyfriend]

nice hippo

[@positivelycurvedpikachu]

yeah. it looks like a really really good hippo

[@dabol202]

Thank you Dr Carroll for that summary of the history of the universe based on temperature scale! Such a fantastic & understandable framework to connect all the major events! And the impact of dark matter on the temperature perturbations! Also fantastic!

[@ritemolawbks8012]

I taught this man everything he knows, and now I can't even get him to send me an autographed-copy of _The_ _Biggest_ _Ideas_ _in_ _the_ _Universe._ Back during his "Swiss Patent Clerk" days, I remember when he used to believe that Noether's Theorem had something to do with disproving the luminiferous aether and that "cosmology" was the study and application of beauty treatment. He was an okay student, and I'm very proud of him. I want that book now!

[@thereallightwarrior906]

Hmm, perhaps the limit as ego goes to infinity sets the boundary condition for book transmission?

[@kanabellhitoshi3143]

How have I not found this channel until now?! Brilliant content, sir! 😊👍

[@joeldobbs7396]

I left this on in the background while I was painting and now I have a strange urge to walk naked into my back yard and stare into the star strewn depths of an incomprehensibly vast and ancient universe, stare in breathless wonder and know with utter certainty that cosmology is so far beyond my ability to comprehend that I might as well be throwing twinkies into the sky to see if anything up there is close enough to poke with a stick. Ah well, plenty of content on KZbin that will make me feel like a genius after watching it for ten minutes, plenty plenty. Actually I very much enjoyed the video and I will likely watch it again with my entire brain engaged.

[@PugetSoundFlyer]

I love this series! Half of what he says goes way over my head. The other half goes way, way over my head.

[@benjaminbeard3736]

The fact that you can put those equations into words and vise versa off the top of your head speaks to your understanding of the subject matter. Pretty impressive. Thanks for the insights and not talking down to us. I find the mathamatics essential to understanding physics.

[@lindsayforbes7370]

Brilliant! The skill of the teacher has to be inversely proportional to the ability of the audience. I think I understood acoustic oscillations for the first time and where that CMB graph came from. What a privilege to have access to this great communicator. Making it simple is not easy. Many thanks

[@Junkitup]

Excellent comment

[@Junkitup]

Making it simple is not easy...... Copyright that

[@heinerdrathen2079]

Or as Steve Jobs puts it: Simplicity is the ultimate sophistication 😉

[@macaroane]

Inverse proportional would mean that teacher that has great knowledge of the subject and with a high pedagogical aptitude is unable to pass knowledge to a highly gifted student, but a teacher with low skills would be successful in bringing the same student to a high level of understanding the subject. But that is not quite right is it? The relation between teacher skill and student ability, in regards of successfully passing the knowledge can only be direct linear.

[@christiangodin5147]

I am really impressed by your clear and professional presentation. I have the impression that I understand GR much more than e.g yesterday. Thank you very much indeed.

[@platonicdescartes]

Dropping a like at 1sec into the video, I was waiting for this topic. One of my favorite fields in all of science. And I know Dr Carroll will do it justice, having owned and read his fantastic book, " Spacetime and Geometry: An Introduction to General Relativity".

[@schelsullivan]

Sean you have been very very productive lately. I think that about 60% of my online listening is content of yours.

[@snajaaffrey5656]

Exciting!!!

[@b.g.5869]

Prove it.

[@owaisahmad7841]

Same for me.

[@wizard1404]

sundial is only possible on a flat earth. They have lied to us.

[@gilbertengler9064]

Absolutely fantastic summary! Congratulations. Never stop giving these lectures.

[@delbertwinters6791]

I appreciate Sean Carroll so much, I’m happy Joe Rogan had him on and introduced me to one of my favorite teachers. (Even though I’ve never taken an actual class, I learn so much from his videos)

[@ryanrutledge922]

I always knew that doing SOME exercise was infinitely more than none . Now I have mathematical proof . Thank you prof . Carroll . ♥️ from 🇨🇦

[@valrossen]

Amazing episode! So satisfying when all the subjects from all the other videos come together and creates something new (knowledge), but still familiar (our universe!)

[@pizzacrusher4632]

This one may be my favorite one yet!!! I actually feel like I understood everything he was saying. (As he said, cosmology is for simple minded people with short attention spans, hahaha!!!! :) ).

[@TheEtAdmirer]

Professor Carroll. You said maybe someone watching this will figure it out and if they do don't forget where they learned it. I have not forgot and I will not forget. So you have to honor the request that you made.

[@kagannasuhbeyoglu]

"The Best Content" Amazing series going on Thank you so much Prof.Carroll

[@ProfessorBeautiful]

"We're gonna predict it, we're gonna get it wrong, and we're gonna fix it". 1:31:05 Classic!

[@jeffk8019]

What an absolutely wonderful lecture. er, I mean Video.

[@rsm3t]

"Lecture in disguise"

[@get2113]

Brilliant, very lucid and balanced exposition.

[@thereallightwarrior906]

The universe must be energy, because it doesn’t matter

[@h3rotor783]

Thank you very much for taking the time to produce these outstanding videos.

[@WildWestPros]

Perfect for falling sleep at night! Thanks

[@ProfessorBeautiful]

Carroll's Theorem: All parallelograms tilt to the right.

[@beenaplumber8379]

That way they look like Tennessee.

[@InsuranceglobeNet]

@@beenaplumber8379 uuhb bb ubbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbububybbbbbbbbbybubbbbbbbbnbnbbbbbnbnrnnnnnnnnnn

[@InsuranceglobeNet]

@@beenaplumber8379 uuhb bb ubbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbububybbbbbbbbbybubbbbbbbbnbnbbbbbnbnrnnnnnnnnnn

[@dennisskehan9336]

Both you and they are right

[@alifarah8303]

Thank you so much for this amazing series. Are you going to make videos about "String Theory" and/or "Loop Quantum Gravity"?

[@lower_case_t]

21:00 I've heard you say a couple of times already that you don't like the balloon analogy, because space does not expand "into something". But, if you're living on the 2-dimesional surface of the balloon, it does not expand into another area either as the balloon grows. If you compare the radius of the balloon to our distance in time from the big bang (so you could call the entire thing "arearadius" or "areatime", just as we speak of "spacetime", the area is growing as the radius increases, just as our space grows as time progresses. I think that is a valid analogy, and by taking away one space dimension we get a three-dimensional "areatime" that we can at least comprehend with brains that are hardwired for imagining 3-dimensional constructs. I like that analogy especially for pointing out how little sense it makes to ask what was "before the big bang": In a balloon-like areatime this would be equivalent to asking, what's "inside the center"

[@nmarbletoe8210]

good point i like the balloon analogy also. flatland but not flat

[@hamsandwichindahouse]

As someone whose loved physics my entire life yet never pursued an education or career in that direction it’s greatly appreciated you take the time to educate us. Shows how passionate you are for this. Thank you.

[@nurk_barry]

Fantastic stuff Sean...thank you!

[@martinds4895]

I miss this series, they were really good

[@aslamicadikafutra588]

Thanks Sean for the making of this videos!

[@whatitis4872]

I think Seans most impressive understanding to me is his stuff on the direction of time its a concept that i find very seductive yet ive never been able to wrap my mind around. Its in part though not wholly based on the fact that im not well versed at thermodynamics.

[@farooqueparvez2767]

wonderful ideas are sprinkling at us from such a great mind of our time........

[@Amir-vw6rk]

Another good lecture on cosmology is by prof. Leonard Susskind in stanford university

[@whatitis4872]

Yeah Lenny is Amazing so is Sean; though Seans lecture here is less mathematical and for a wider audience. Heres one that while has math doesn't use too much technical stuff kzbin.info/www/bejne/qZLJXmSFj9eJnpY theres 3 parts to it.

[@rickharold7884]

Awesome. Love these lectures.

[@pizzacrusher4632]

so wonderful! thank you again!!!!

[@reddenitup]

An excellent speaker and so so sharp. Your intelligence fascinates me sir.

[@a.rodimtsev9446]

This was really a good video. Thank you so much.

[@jasonlee4830]

Thank you Sean Carroll!!

[@LearnedSome]

Wonderful! Thank you!!

[@PhilosophyProf14]

Really well done. Thanks!

[@iczemi]

Your vlogs are fascinating.

[@laurendoe168]

22:02 I like to think that EVERY point is the "center" of the Universe. Under this perspective, the Big Bang happened everywhere. Also, under this perspective, each person can be said to be "The Center of the Universe."

[@StumpyMason_]

I hope we all get theoretical physics degrees at the end of this series.

[@hhaavvvvii]

Only if you do the associated mathematics.

[@nafnist]

Physicists are lame anyway, they are practically mathematicians. No real urge to understand, and make sense of the fundamental stuff in this world. All they want is to calculate.

[@mrdr9534]

@@nafnist ? What exactly do You mean by "understand" ? And what group of people (if any) do You think are in pursuit of "understanding and making sense of the fundamental stuff in this world" ? Best regard.

[@nafnist]

@@mrdr9534 Shut up and calculate

[@psychoticchemist]

nafnist There is no way to deeply understand the universe without the calculations. The quantification of the universe and its concepts is the only way to break through the biased lens of human perception and get a real glimpse at objective reality. I have a feeling you simply can’t handle the math and so you lash out against it altogether, like a child throwing a tantrum. Nice.

[@waaridhborpujari7237]

I had been waiting for this video for a long time… Glad to see it. 😇

[@whatitis4872]

yeah man i love good precise explanation that dont skimp on the math

[@ProfessorBeautiful]

This connection between dark matter and the scale deviations of the CMB.... a dynamite explanation. 1:46:38

[@ReluctantStallion]

Amazing content. Much appreciated.

[@whatitis4872]

Yeah man i love cosmology and math

[@SG-kj2uy]

I’m just waiting for a new series of lectures, Seannnnnnn

[@l.rongardner2150]

AMAZING STUFF!!! I just found a multiverse in my bowl of quinoa. Will miracles never cease, including the miracle that miracles don't violate the law of cause and effect, and that people take seriously Sean Carroll's cosmological crappola.

[@macbuff81]

The exact math is a bit beyond me, but your accompanying narration does provide a nice overview and context to the underlying connections and principles

[@matthew944]

It's like your shirt is becoming one with the deep field 😂 I'm so glad I found this channel! The way you explain the Universe is very mind opening, and I really enjoy your lectures on time.

[@nicholaswallingford3613]

Leavitt wasn't using parallax to measure distances to Cepheid variables. She was cataloging stars in the Large Magellanic Cloud, and observed the relationship in the Cepheid variables there. Since all the stars in the Large Magellanic Cloud are all roughly the same distance away, she observed the relationship between period and APPARENT luminosity.

[@joeflosion]

16:45 Sean Carroll is a cat guy confirmed. Damn do I hope to bump into you at a Flyers or Phillies or Sixers, hell even a Wildcats basketball game one day. I'd say God Bless, but since I know your deal, I'll just say I hope you have a great day Sean. Thank you for teaching me so much over the last few years. You've made a bigger impact in my life than you can ever imagine.

[@rohitrohan6512]

just amazing ❤️

[@euclidofalexandria3786]

overlaps---> gaps and symmetries, eqn to predict symmetry breaking outcome, even for spontaneous symm breaking, outcome can already be know, like kicking an acorn, or a [ine cone, and knowing which way each vertex will point before even kicking it. like called cards and dice, translated into book words, translated into heard convos in public domain while flipping pages in a boiok synched.

[@Imaginose]

The examples you spoke of about the Universe expanding are used to show how things further away are moving away faster, which was helpful at least for me.

[@RKarmaKill]

Sean Carroll is not a salesman. Respect. Hate my salesman job

[@smith5796]

Although he does love a good sales pitch.

[@michaelcornish2299]

Class, loved this video great discussion of dark matter.

[@CodepageNet]

Fantastic! i like your calm way of of presenting. I hope you dont mind if i also use this particular video for meditation :-) (and i've also started studying maths and physics, it's a huge pleasure to be able to at least somewhat follow videos like this.)

[@luchochemmesvilches6163]

Oh my. If studying stars is this messy, some galaxies must be Messier.

[@infinitumneo840]

This is a truly great series because of so many interesting topics. Are Axions a possible source of dark matter in the early universe?

[@caseylynch4001]

Great stuff!

[@grahamdlawton]

Doc, great video and I loved the humor and irony…….. cosmology is easy and cosmologists only need a short attention span. However, the video is 1h 59 min long! Looking forward to finishing the series - thanks for all the good stuff.

[@loren-emmerich]

excelllent video, matter is what we and the stars are!

[@protoword10]

As usually, thank you sir!

[@johnp1]

Sean.. I promise to mention you when I receive the Nobel price for my work on the Inflationary theory. I plan to start working on it as soon as I retire from my current job in a few years. Thanks for another inspiring lecture.

[@TheMemesofDestruction]

1:56:10 - Thank you Professor! ^.^

[@henleycheung3615]

fantastic ideas, thanks

[@tha_saliq3339]

The universe is amazing

[@daapdary]

At 44:55, Sean writes: log(eˣ) = x From the context, the log's base is e (not 10) so it means: logₑ(eˣ) = x or ln(eˣ) = x Apparently, physicists assume *log* is a _natural_ logarithm (base e). However, engineers, calculators, and general convention all assume that *log* is a _common_ logarithm (base 10). That's a problem, isn't it? :-) Decades ago, I was taught that *log* has base 10 and *ln* has base e. The international standard *ISO 80000-2* (section 12 "Exponential and logarithmic functions") describes this notation: logₐ x : log to the base a of argument x. ln x = logₑ x (natural logarithm). lg x = log₁₀ x (decimal logarithm). lb x = log₂ x (binary logarithm). log x is used when the base does not need to be specified. log x shall not be used in place of ln x, lg x, lb x, or logₑ x, log₁₀ x, log₂ x. I recently adopted this standard a few weeks ago, which makes me the first person ever to do it! :-)

[@markcalvo9327]

I am very grateful that you've taken the time (significant amount) to do all these and answer questions is very commendable to say the least. I wish I had an opportunity to meet and learn from, no, exchange ideas with you. I sent you a invite on Linkedin.

[@mrfinesse]

Thanks professor. You talk about the observable universe and assessing a finite size on it. However you talk about infinite universe when you talk about a flat/negatively curved universe. You also mention that "we know how much stuff is in the universe". You also talk about "scaling infinite numbers - and the result being infinite". All these statements seems to be in conflict with each other (to a rookie - such as myself).

[@p_square]

Prof. Sean Carroll isn't there going to be any video on Relativity? By the way, love your videos

[@Valdagast]

Look up the Gravity episode. Lots of stuff about general relativity there.

[@whatitis4872]

As someone here said Susskinds Lectures on relativity are really good. Ive watched all of em multiple times. The ones on cosmology too. In this channel theres some stuff kzbin.info/www/bejne/qZLJXmSFj9eJnpY And Sean has a real good introductory to advanced book thats used in many universities to introduce the subject. Also recomend PBS spacetime. you need many sources to learn relativity. Its not easy subject.

[@jdgagnon8077]

22:20 ish, and forgive my ignorance here, but I understand that you are making the relativity point here, but if we were to be looking at the universe in its entirety, doesn't there by definition HAVE to be a center if everything is expanding at a constant rate as a whole. I may be missing something here, would love to be informed on this. Thanks for these videos, this series has been AMAZING!

[@MNbenMN]

Not every geometry needs to have a center, expansion or not. For example, there is no center point on the surface on a sphere, nor in a flat torus. Since the expansion is not an acceleration through space, there is no way to locally detect is as motion. If you were to define the universe in a more Newtonian way, then you might end up using a static background grid of space to plot out motion of galaxies and find an apparent center, but that grid is not physically real. You could just define a center into existence wherever you like just by choosing that grid. If you are taking into account that the space itself is expanding, and that the expansion looks the same no matter where you start looking, that apparent center goes away.

[@jdgagnon8077]

Ben Marolt thank you!

[@whatitis4872]

If you know the most basic cosmology 2d spacetime model youd not ask this question. You draw an x t coordinate axis. the x=constant lines are worldlines of galaxies (wlg )if you draw a t=0 vector it points between two of these (wlg) and the length of this vector is a(t) as t changes the distance changes equally between any two wlg that started at same distance and theres no spatial center to this. If you have an infinite forest of trees wheres the center. Nowhere. Wheres the center of an infinite plane Nowhere the is none or evrywhere every point can be center.

[@0meg0n]

I love your stuff ~ pity about the multiverser..Everett Song

[@Valdagast]

The length of an episode (in seconds) is given by kx+m, where is 161, x is the episode number and m is 2579 (least squares method).

[@Valdagast]

@@wavydaveyparker I mean, it will give you an average value, but it doesn't fit the curve perfectly. The actual curve looks more like an x^3 curve when you look at it - up, saddlepoint and then continues up. But I don't know how to tell Excel to calculate that. :o) Also: This is for ordinary episodes, not Q&A episodes.

[@Valdagast]

@@wavydaveyparker No, you put in the episode number for _x_, and out pops the episode length. Actually, I managed to get a polynomial. t(s) = 1,81x^3-65,15x^2+808,31x+1124,4, where t (s) is episode length in seconds and x is episode number.

[@mimidhof2179]

Great content, made to be understood... thank you so much to share your love about the Universe and life.

[@JohnDlugosz]

opening: I think it's not a matter of "must be right", but rather ask, "above what scale does the universe become uniform?" and also compare that with the size of the universe (much much greater).

[@JohnDlugosz]

1:20:00 I don't like the term "make fun of", and I don't see why anybody whose ever been on the receiving end of a bully would. I always replace it with "ridicule", to promote a more accurate connotation. But, in the case of _recombination_ , I would have to go with "make light of". (Note: That's a pun, if you don't realize)

[@FractalMachine]

it's an interesting thought, that there are people alive today, who have been born before we knew (even scientists) that there are other galaxies in the universe.

[@jamesmorrris7580]

Hubble gives me hope in humanity he started out a lawyer and became a scientist

[@susmarcon]

I am reminded of a little Einsteinian anecdote I once read, that went something like this: Assistant: “Doctor Einstein, I notice your examination paper has the exact same questions as last years test. Einstein: Yes that is true. But the answers have changed. Fairies and goblins might exist. God and dark matter might exist. I believe Steven Hawking at one time thought that an event horizon might exist. But electricity, magnetism and gravity do exist. Occam's Razor is the principle that, "non sunt multiplicanda entia praeter necessitatem" [i.e., "don't multiply the agents in a theory beyond what's necessary."] If two competing theories explain a single phenomenon, and they both generally reach the same conclusion, and they are both equally persuasive and convincing, and they both explain the problem or situation satisfactorily, the logician should always pick the less complex one. The one with the fewer number of moving parts, so to speak, is most likely to be correct. “Space News from the Electric Universe” provides the counterweight to a variety of views held by the mainstream. The E.U. maintain that electricity is in fact the primal force in the universe. Their view allows many of these questions to be resolved through the known mechanisms of plasma physics and electricity. Happy hunting.

[@naimulhaq9626]

For someone who knows cosmology, I am surprised he didn't mention the most crucial part 'negative cosmological constant', which besides phases of matter, brings a variety of properties to the cosmos.

[@life42theuniverse]

7:50 Sorry for the correction, the gaia mission and the billion stars is correct, but this is only about 1% of Milkyway. There is some evidence that the local group en.wikipedia.org/wiki/Local_Group may be a collapsing space... at least that the mass within the space is blue rather than red shifted.

[@seymoronion8371]

@@michaelsommers2356 Give it time

[@llaauuddrruupp]

These videos sustain me.

[@whatitis4872]

Yeah man Sean is not only knowledge but entertainment so keeps you from loosing mind during Covid and you learn something!!