1. Inflationary Cosmology: Is Our Universe Part of a Multiverse? Part I

MIT 8.286 The Early Universe, Fall 2013
View the complete course: ocw.mit.edu/8-286F13
Instructor: Alan Guth
Professor Alan Guth talks about the Big Bang, cosmic inflation, evidence for inflation, Cosmic Microwave Background (CMB), dark energy, and whether or not our universe is part of a multiverse.
License: Creative Commons BY-NC-SA
More information at ocw.mit.edu/terms
More courses at ocw.mit.edu

[@NoActuallyGo-KCUF-Yourself]

How cool is it that today, I can turn on my computer, go to KZbin and watch Alan Guth speak on cosmology? Like, MIT OCW is cool enough, but that is *Alan Guth* himself talking about *his* theory. What a time to be alive.

[@nonokayakjack]

This is ridiculous fantasy just like the fake theory that we came from apes. How can people believe this crap? We where made by a big man in the sky in 6 days. We even see his son every now and then. When we die, if we're good, we go to a big amusement park in the sky. God!.....oops.

[@sourabhkhandelwal1568]

@@nonokayakjack because men did not come from apes, humans and ape shares the same ancestors, that is if you trace back the ancestors of us and the apes, you will eventually find a common ancestor. Evolution is like a branch and not a ladder and all the life system that has existed on the Earth can be imagined as a giant tree with a great diversity of different life forms all ultimately having the same origin(the root of the tree). Evolution is a fact and it's evidences are everywhere around us. Sorry to break it to you but if you can not understand it then it means that you simply do not have the intelligence to do that.

[@user-fo8lz6om7l]

I was literally on my way to make this exact comment, tears in my eyes im so excited.

[@imaseeker100]

@@sourabhkhandelwal1568 fucking windbag. so who is our common ancestor?

[@98danielray]

@@sourabhkhandelwal1568 the guy is trolling

[@mrtpsoroush]

Holy smokes ! undergraduate Inflationary cosmology taught by Alan Guth !!!

[@justiceretrohunter2]

mrtp i said the same thing, i was like "Damn, this is the real deal."

[@bautistakeithcharles3302]

Yeah and for free. Doesn’t get any better than that.

[@timblizzard4226]

Sweet deal huh?

[@jacobvandijk6525]

Holy smoke, you obviously have not seen this one: kzbin.info/www/bejne/jHnLhnaXq8R9qM0

[@jacobvandijk6525]

Who is right? kzbin.info/www/bejne/jHnLhnaXq8R9qM0

[@inkedolympia23]

I actually get to learn from Alan Guth as opposed to just watching him in snippets in documentaries... Whhaaaaaaaattt!?!? This is AMAZING! One of the many reasons why MIT OCW is one of the best things the Internet has to offer.

[@emerichfiala7238]

Inked Olympia Agree totally.

[@roop-a-loop]

and he writes in comic sans lol

[@jacobvandijk6525]

Who is right? kzbin.info/www/bejne/jHnLhnaXq8R9qM0

[@ElliottCC]

Absolutely!

[@aaronooi8409]

i know right!!!

[@wagsman9999]

Well, it took me a few weeks to get through these (the math is not trivial, but doable if you have some familiarity with calculus and differential equations). I must give a big thanks to MIT for providing this series. Professor Guth is passionate about the subject, obviously knows the material better than most, and is a great lecturer. I was a bit sad when the series came to an end.

[@fluentpiffle]

Mathematics does not ‘prove’ anything. It is only a human-invented method of measurement. As such, it can only comply with whatever we pretend to ourselves is worthy of measuring..

[@Julian-tf8nj]

A BIG THANKS to MIT and the *awesome* Alan Guth for this excellent course! :)

[@fluentpiffle]

Mathematics does not ‘prove’ anything. It is only a human-invented method of measurement. As such, it can only comply with whatever we pretend to ourselves is worthy of measuring..

[@guillermomartin8353]

MIT OCW I LOVE YOU SO MUCH.

[@owen7185]

Alan Guth, deadset legend. Some people are born to educate, he's one of them. I enjoy these lectures mostly because of the way he presents them

[@samikshyasahoo102]

My mind is blown. I am a 9th class student from a small town of India watching this MIT lectures by just clicking on my phone

[@abdullahlaith2629]

I'm 15 and watching this, I really love Astrophysics and Cosmology. I hope one day I could study it in MIT though, highly doubt I will :(

[@loserface9556]

i believe in you stranger

[@wecare838]

I hope you do. However, remember it doesnt have to be undergraduate only though, where tuition fees are large, acceptance rate is low etc. You can crack the jee advance and study in iit or nit and then after your bachelors you can apply in mit in your chosen fields. There you have experience, so your chance of getting in is higher plus they most likely would pay you stipends as you do research(and/or get an internship, which often pays well) where the essence of mit comes alive. Or you can, after bachelors do your masters in a non ivy league university, say for instance, texas a&m and then apply for phd in mit. Then your chance of acceptance goes even higher, you will be paid(cause you're doing research now, bringing new knowledge into the world and your hard work is compensated by the remuneration) and you actually get to experience the world class research experience, professors labs latest techniques that mit is famous for, up close. So remember its not a one shot chance, new opportunities actually come up as you climb up the ladder. Best of luck. You can do it :)

[@wecare838]

I call it Indian intuition😅 at least someone from the Indian Subcontinent.

[@khansaahmad2558]

Hey! believe in yourself, you will do it! It's amazing that you are doing it when you are 15, just don't stop........ keep on working, falling, standing and you'll soon achieve your dreams!

[@abdullahlaith2629]

@@khansaahmad2558 Haha! This came in time! I just took my first SAT test- probably did poorly. I was sad and then got a notification for this comment. I will register for May and retake the test ;).

[@dynamixthunder724]

love from a indian village student❤️

[@shivanshjha938]

From which village you are? And in which class you are studying or what are you pursuing?

[@Justaguy10723]

all the best bhai do good

[@krishnachandradas8386]

No documentary can teach this in so much depth.

[@Messier31NGC224]

Thank you for publishing this online!! What an amazing resource

[@gilbertengler9064]

Many many thanks dr. Alan Guth, you are one of my favorite physicists! So clear explained.

[@meetghelani5222]

This is pure gold, thanks to professor lewin's lecture's recommendation that i got to know this gem of a human that professor Alan Guth is!

[@philrudski9084]

Thank you for making this series of informative videos. Thank you Alan and MIT OCW.

[@krzysiekmargo797]

That's a great performance here by Alan but DAMN.. Full respect for those who chaptered subtitles in this vid. gr8 work!

[@tomneedham1937]

Many moons ago - 1981 perhaps? - Shortly after Prof. Guth proposed his Inflationary hypothesis, Prof. Guth passed through my hometown and gave a lecture on Inflation at our local Planetarium. The room at the Planetarium is big enough to hold approx. 200 people. If my memory is correct - and I have no reason to doubt it - there were maybe 25 people in the audience listening to Prof. Guth. Go figure!! That's the bad news. The good news is my small library of books has a copy of Prof. Guth's book "The Inflationary Universe", personally signed by him, purchased at that lecture. Was his presence in my hometown a quantum fluctuation? Regardless of the Uncertainty Principle, I knew there was certainty in my need to have attended that lecture!

[@shirleymason7697]

TOM NEEDHAM ........would you be surprised to hear that I recently had to explain to a local woman the difference between our solar system and the Milky Way? This woman had a career and college undergrad degree.

[@mylittleelectron6606]

I was surprised to hear him say it's a small class. Taking a course on inflationary cosmology taught by Alan Guth is like hearing your instructor for general relativity is Albert Einstein!

[@nmarkose]

Alan Guth is amazing at describing a very complex subject!

[@fluentpiffle]

Mathematics does not ‘prove’ anything. It is only a human-invented method of measurement. As such, it can only comply with whatever we pretend to ourselves is worthy of measuring..

[@peterlue1156]

Thank you for this Dr. Guth!

[@palvindarchhokar9821]

What a great lecture, so freaking mind blown.

[@user-ej3lw6up2j]

this is why i like you tube.

[@cheesechizel594]

his crew needs professional film/audio/lighting equipment - these lectures deserve it - thanks for making them available

[@paullogeman9189]

A clear, concise and meticulous presentation on a complex topic.

[@jurgenblick5491]

He is so clear. It is easy to follow him.

[@lmelin1959]

A very interesting lecture, thank you Mr Guth.

[@gangguo1162]

a great scientist and lecturer

[@jo-anseipp8073]

Many thanks MIT.

[@albertosamaniego2476]

the man, the genius, the legend... Prof. Alan Guth

[@mcxzsa]

Thank you, dear professor

[@williamcory4689]

Please bring back Walter Lewin's videos. Those lectures were a big reason I grew a love for physics. Punish Walter Lewin. Don't punish all the people across the world who want to learn.

[@reichhardbuerger1492]

Yes, his lectures were great and it is a pity not to find them anymore (on youtube at least). On the other hand: what would a victim of his acts feel if the guy, who forced her to humilitate herself, stay here on youtube, beeing a celebrated lecturer..? I really do understand both sites here, personally would still like to be able to watch his lectures. But I can understand that this just wouldn´t be approbriate - and would be seen as such... I guess, it was a difficult decision - and I think there would be more people protesting him staying on yt on that MIT brand than missing his lectures...

[@williamcory4689]

You are right. I understand I am extremely biased because of how I feel about those lectures. Hopefully someday we get video of equal or even better lectures than Walter Lewin's about the subject.

[@LnLwLDD]

Reichhard Buerger I just read the story when the lead accuser came out publicly. It sounds like she got upset when she found out he was flirting about with other girls. I don't understand how when only an online interaction you can be intimidated into discussing sexual fantasies and then sending naked pictures of yourself to the man. She said she started "cutting herself again" after 7 months of this activity. Dealing with mentally ill people, like the initial victim, I could see them pulling the video so they don't get sued. It just sounds fishy but I understand the universities stance. From her description it sounds as I said above though, regardless it's inappropriate activity for an instructor. Even though she was just taking non-credit online courses at her leisure it was through the university making it not a personal matter. I don't blame victims but I'm not seeing how she or any woman was victimized unless they each felt they were special because of the attention he gave online? Oh well, regardless not a good idea for a professor to do.

[@kw1ksh0t]

His lectures were just classical mechanics though. It's not like they removed an extremely important resource such as this one. They removed lectures about the most basic and accessible physics for which there are many more (better) lectures, it's not really a significant loss

[@brainstormingsharing1309]

Absolutely well done and definitely keep it up!!! 👍👍👍👍👍

[@wagsman9999]

Earth is an "significant lump" - love this!

[@imaseeker100]

freekin' awesome teacher too.

[@malolangovindarajan5858]

Just awesome, very useful

[@EvoArtsLLC]

@Roland Gerard to increase knowledge you must speculate. I think it's a great thought experiment and disapproving it out proving it is the act of science therefore teaches the discipline.

[@goldfishi5776]

I applaud your institution for remaining open to comments. Certain other institutions are afraid of criticism. Imagine a system of science without dissent.

[@vizman8585]

Dissent is fine as long as it's based on science and not mythology.

[@gixxerboy555]

So...as we come to the point....the stars are our parents...?Much respekt for this Dr.Alan Guth...wow

[@LIFEDELAYSDEATH]

Enjoyed lecture..

[@MrKayojc]

Thanks by wonderful video!

[@LuciFeric137]

Professor Guth is an excellent lecturer.

[@fluentpiffle]

Mathematics does not ‘prove’ anything. It is only a human-invented method of measurement. As such, it can only comply with whatever we pretend to ourselves is worthy of measuring..

[@nathanokun8801]

The "Dark Energy" large values for short wavelengths is exactly analog to the "Ultraviolet Catastrophe" that occurred with light physics in the late 1800s and was solved by Planck by creating the original equations for Quantum Mechanics to create the "Black-Body Curve" formula for light relative to temperature. It seems that we need a Quantum Mechanics equivalent to solve Dark Energy. "The more things change, the more they stay the same."

[@perrydubreuil1514]

Thank you so much for this

[@austenbaker4618]

THANK YOU MIT!!!

[@Vikermajit]

Awesome explation. Tqvm, sir.

[@janphilipzen5448]

thank you for this

[@Mericosmos]

Now i wish that i paid more attention to my English language course

[@apburner1]

Energy: a property of objects which can be transferred to other objects or converted into different forms. Negative energy: a property of objects which cannot be transferred to other objects or converted into different forms?

[@barbjephson]

Pulsating universe is the expanding and cooling of the universe.

[@saadibnasaadhusain]

Are you going to post the 8.962 General Relativity lectures?

[@mustafa1912]

was it brady haran at 01:00:50. hell of a lesson great great lecture.

[@narendraparmar1631]

thanks MIT

[@EvoArtsLLC]

If you can accept a 1 dimensional ribbon becomes multidimensional object, you can then theorize that its a natural shape or structure that repeats by going through all of the diminsional shapes and then degrading. To measure this you would need to rationalize that a laser can become a 2d wave and through mirrors you can craft 3d then 4d then 5d etc... after it hits it's highest dimension it unravels the steps in order of creation then repeats.

[@stevewalker9743]

I would like to see an explanation of i) where dark matter (and d. energy) fit into calculations of mass density, ii) how GR predicts all of these things (with, of course modifications like inflation) yet science can't make it work for outer radii of spinning galaxies, iii) how we can pin down the "age" of the universe when time itself is fluid (is it the "age" from our reference only?). Having said that, it's all pretty fascinating stuff. I saw Guth speak in the 80s at the U of Utah.

[@fluentpiffle]

Mathematics does not ‘prove’ anything. It is only a human-invented method of measurement. As such, it can only comply with whatever we pretend to ourselves is worthy of measuring..

[@ultrafeel-tv]

Where does the space come from into which the big bang supposedly expanded into...?

[@robertojordao1060]

See what globalization made in my life: I'm a brazilian guy who learned english from internet and now I'm using this knowledge to lear a theory that I became aware of while I was listen to a podcast (Joe Rogan). What a crazy world!

[@jaralara6429]

Roberto Jordão I totally see what you mean! But I think the phenomenon you are talking about is best described as the information highway. Globalization sounds like an economic and geopolitical concept to most people

[@robertojordao1060]

@@jaralara6429 Thank you! You see, there are still so many things to learn haha

[@anushka.singh.02]

So, can we just assume by the fact that the inflation "material" was flat as per Euclidean geometry, the idea of the multiverse suggests that there might be other universes thriving in those flats and one goes to the next dimension they might see those Euclidean flats of universes??

[@kw1ksh0t]

At 42:09 the caption saying "[? lab manuals ?]" I think he says "allowed range" here

[@andrewpaul8732]

We know that in many years black holes will evaporate and leave only empty space but can space itself deteriorate? And in an unbelievable long time all that will be left is time itself and then It creates space. Which then inflates and so on. Or is space here now and it's here for good.

[@ronthomas8331]

25:00 does this means that as the universe ages it gets heavier because of more negative gravitational energy because of gravitational repulsion.

[@kyojurorengoku1099]

I am 17 now I am not even in college but I don't like other subjects I don't like accounts or economics i like cosmology even if i am weak in maths space just pikes my interest too much i just didn't get enough marks to select science stream but when I found this video i was like actually too much interested in ti tomorrow is my English final exam and here I am watching this it's 😊

[@stevewalker9743]

Ha....disregard i) below! You answered it. Still wonder about objective time and how GR adjusts to DM and DE.

[@ramankumar-kk9sl]

good live long alan sir

[@mdabunayeem8067]

The legend himself!

[@lepidoptera9337]

Yes, the multiverse is a legend. :-)

[@jlpl3291]

1:03:00...why aren't short wavelengths in the vacuum fluctuations bounded by the energy of a quantum in the same was as the solution to the Ultraviolet Catastrophe?

[@hemsingh6785]

Can someone tell me if universe is expanding then actual density of universe must be decreasing... Means value of omega is decreasing isn't it

[@ricardouchida9226]

If inflation lasted until 10^-35 secs, what was driving the expansion of the universe from then onwards, given the inflation energy in the so called pocket universe has decayed? Alan mentioned a universe the size of a marble, how does the standard BB model explain subsequent expansion?

[@fluentpiffle]

Mathematics does not ‘prove’ anything. It is only a human-invented method of measurement. As such, it can only comply with whatever we pretend to ourselves is worthy of measuring..

[@guillermorocha6661]

It feels like the big guy who runs the show just throws more stuff in, as we look deeper into physics. It would be funny if we discovered it all boils down to "likely to exists" but in reality, nothing confirmed.

[@crushedz]

Does space expanding mean that every point in space is generating space exponentially?Is metric expansion of space the creation/generation of space at every point thereafter too?Is the expansion of the Universe really the metric expansion of space?Is there a force associated with the expansion[/generation?] of space that propels galaxies?

[@fluentpiffle]

Space is not expanding.. Mathematics does not ‘prove’ anything. It is only a human-invented method of measurement. As such, it can only comply with whatever we pretend to ourselves is worthy of measuring..

[@maresfillies6041]

Science at it's best. :3 I love Science. That's why I'm a double major computer science and electrical engineering. For Science!!

[@tekin491]

1:00:09 En dikkat çekici karanlık enerji adayı = Vakum enerjisi 1:01:17 Karanlık enerji, neden daha önceden değil de 5 milyar yıl önce etkin olmaya başladı

[@StaticBlaster]

I love learning these things. I have an insatiable appetite for learning these complex topics in physics. On the other hand, religious dogma bores the hell out of me. Science is way more interesting and exciting than superstition.

[@binkyloo8]

At 15:25 what does he mean by 16Gev as related to a proton? How does this related to energy at time of BB

[@UteChewb]

kT is a measure of the temperature / energy of particle in a system. k is Boltzmann's constant and T in kelvin. So, Energy = kT , since k is 1.38e-23 J/K or more appropriately here, 8.617e-5 eV/K then 16 GeV = 1.6.e10 eV = k T. And T = 1.6e10 / 8.617e-5 .... the temperature will be *huge*. Something like a hundred million million degrees kelvin.

[@robertbizzarro8586]

It's rather marvelous. 😆

[@sameertomar5099]

Alan guth wow

[@kosmos6400]

Hey uhh, a class I uhh actually wouldn't skip uhh! Thanks uhh :)

[@shirleymason7697]

Kosmos .....naughty, naughty.

[@wnderer4365]

thank you very much for this, i can't believe i can now study about inflation from the father of inflation himself....

[@fluentpiffle]

Mathematics does not ‘prove’ anything. It is only a human-invented method of measurement. As such, it can only comply with whatever we pretend to ourselves is worthy of measuring..

[@aryangod2003]

Is this for undergraduate physics and astronomy majors? Material seems very simplified.

[@fluentpiffle]

Mathematics does not ‘prove’ anything. It is only a human-invented method of measurement. As such, it can only comply with whatever we pretend to ourselves is worthy of measuring..

[@kevalmeshram1075]

how half part or hotter can be calculated ??? we only see one side of the sphere !

[@mcarrasco45]

una pena que no este traducido al español................saludos al Sr Guth

[@ManyHeavens42]

Yes,!

[@goldfishi5776]

Very seldom do I see a lecture that walks through exactly how the data developed the theories we’ve applied.

[@aplcc323]

The Big Bangless Theory, I like it!

[@mcxzsa]

Genius

[@mcxzsa]

Thank you for lecturing us to be normal at all

[@GermanSnipe14]

What year is this course (freshman sophomore junior senior)?

[@mitocw]

Since the course prerequisites are 18.03 Differential Equations & 8.02 Physics II: Electricity and Magnetism, it would be likely a sophomore or higher course.

[@davidwilkie9551]

Directly on topic, "of course" the Inflationary aspect is a Reciproction-recirculation Quantum Tunnelling inclusion-exclusion timing-phase positioning Multiverse, because temporal wave-packaging is perfectly interpenetrating In-form-ation, for inside-outside holographic time-timing sync-duration, loop quantization presence.., ie superposition in Superspin here-now-forever holography. There is no new news only new angles, the inherent word meaning of "Universe" is the self-defining Reciproction-recirculation fact of Eternity-now Interval Conception. "Precision is not Accuracy", so no matter how exactly the duration of the local Era is measured, the Accurate interpretation of e-Pi-i sync-duration continuity connectivity in the Eternity-now Black-body Interval is an absolute Zero Kelvin difference of No-thing Singularity positioning eternally, that is the absolutely Logical Statement of Mathematical Modulation Mechanism Singularity inside-outside holographic presence, or Quantum Tunnelling bubble-mode of the Universe. The basic concept of "Classical Big Bang Cosmology" is an impossibility, and only an impractical "Player" could believe it by looking without seeing real-time probabilistic Actuality. Dr Eric Learner's book The Big Bang Never Happened. BBT is a kind of insult to Experimentalist's Practical-Actual Intelligence. Even Wheeler's One Electron Theory is basically the recognition of Quantum Tunnelling inclusion-exclusion timing-phase positioning Chemistry.

[@justthefacts8872]

Great lecture. His intonation reminds me of Katharine Hepburn.

[@user-cn2qr3se6y]

Univers began 13,82 billion years ago. I can't understand for what "clock" is that time? Let's imagine that two "clocks" was burn exact at that time us the univers and now one of that "clock" appears to be at my hand and another somewhere in the field with huge gravity. That to clocks will show absolutely different time and both are right.

[@user-cr8ml8tf2l]

اللهم لك الحمد على هاذه النعم.

[@TheBigBangggggg]

Alan Guth: just another human being having solved the problems of other human beings who have not the faintest idea either. But it pays.

[@fluentpiffle]

Mathematics does not ‘prove’ anything. It is only a human-invented method of measurement. As such, it can only comply with whatever we pretend to ourselves is worthy of measuring.. Truth does not care about the ‘money’.. spaceandmotion

[@TheBigBangggggg]

@@fluentpiffle Observations (so far) show there is only one universe. String Theory (I call it String Speculation because nothing of the theory can be proven) is only an intellectual fantasy based on math. But math isn't reality ;-)

[@fluentpiffle]

@@TheBigBangggggg "Observations (so far) show there is only one universe. String Theory (I call it String Speculation because nothing of the theory can be proven) is only an intellectual fantasy based on math. But math isn't reality ;-)" - You understand that 'observation' has many flaws to it, and even after 'observation' there comes the next phase, that of interpretation? The object of interpretation is that we correlate as accurately as we can with the nature of reality. That is the motivation behind genuine 'science', and being told how to do these things has no bearing on the actual nature of that which exists. Currently, genuine 'scientific method' is being largely ignored for political and financial purposes, and liberally showered upon the masses of 'believers' and 'followers' that frequent social media platforms such as this one.

[@wntu4]

I can't wrap my head around what he says at 5:00 . If there was nothing before the big bang and there was no single point for it (The egg) then how does it happen everywhere, uniformly when that everywhere didn't exist? Seems like the old 'chicken and the egg' conundrum.

[@lepidoptera9337]

When did anybody say that there was nothing before the big bang? :-)

[@noshitripathi9524]

What if the inflation and big bang theory would act as indirect recursion??

[@cenelind]

Ok, cool. Now it finally makes sense to me why anyone would think there was a big bang. They Don't. Its a misnomer. Awesome Lecture.

[@3dk4yProductionz]

God created "The Big Bang"

[@norbertblackrain2379]

1:04:14 "There is no shortest wave lenght" .... Would not the Planck Length define a shortest possible wave lenght?

[@norbertblackrain2379]

Dammed i typed the question to fast ....

[@Russ442100]

If you shorten a wavelength by 50% then again 50% you can do this forever: the wavelength will always get 50% shorter while there is always 50% remaining= no shortest wavelength.

[@norbertblackrain2379]

Mathematical that is correct but in physics not . You could make the same argument about energy quanta or charges. But there is a lower limit to energy quanta - H bar and to charges.

[@user-is3tz8gp2x]

I think we need an instrument(International Organization) to control global climate in the perspect of Orbital Mechanics. (including small debris and lanched projectile). I think that there are many forest fires than before

[@sherlockholmeslives.1605]

I think that he knows his stuff.

[@heroncortizo1993]

Is there a possibility that Dark matter and Dark energy be the gravity with negative pressure?

[@Oners82]

Not dark matter, that has positive gravitational energy.

[@mightymartianca]

Dark energy is what is causing the expansion to speed up. Some theories suggest that that was the same energy drove the inflation, but in general I don't think most cosmologists believe that inflation was caused by dark energy.

[@ninadnaval1807]

@@mightymartianca Why dont the cosmologist think so?

[@haveltherock1169]

This is quite possibly the weirdest rabbit hole I’ve gone down today

[@manish__kumar]

Any one give the answer ... -> If dark energy is the vacuum energy or energy of nothingness then what about the DARK METTER is dark matter really exist or it is also the matter of nothing or vacuum dark matter..