What Do We "SEE" in the OLDEST LIGHT in the Universe? Cosmic Microwave Background (CMB)

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Chapters:
0:00 - Speed of light and the past
1:24 - Cosmic Microwave Background
2:55 - What the early universe looked like
3:24 - What caused transparent universe
4:45 - Why is CMB not Gamma Rays?
5:51 - CMB - perfect Black Body
6:02 - What is a black body?
7:02 - Temperature of CMB
7:31 - Isotropy of the universe
8:15 - Why are there galaxies?
9:22 - Where did anisotropy come from?
10:14 - Evidence for cosmic inflation
11:14 - Why is the universe flat?
13:07 - Evidence for Big Bang
13:54 - Can we know anything prior to CMB?
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Outro artist of the week:
Oleksandr Koltsov, "Classic House 90s Rave Music"
Summary:
If we look as far out as possible, we would see a uniform glow of low level radiation in all directions. This is called the cosmic microwave background, or CMB. It is the oldest light in the universe. And it can tell us a lot about its early history.
Before the CMB, the universe was an opaque and featureless. About 380,000 years after the big bang, the universe cooled to around 3000 Kelvin, allowing electrons to combine with protons to form atoms. The universe then became transparent, because photons were free to travel from one end of the universe to the other, without being scattered by electrons.
Why is this light from the very early universe microwave light, instead of higher energy gamma rays? 3000 K was not energetic enough to be gamma rays. In the 13.7 billion years it took for the light to reach earth, space expanded, causing the wavelength of photons to increases to microwaves.
The CMB is the most perfect black body every measured. A black body absorbs all incoming electromagnetic radiation. But Black bodies also EMIT photons in the form of thermal radiation, called black body radiation.
The spectrum of photons emitted from black bodies matches the expected spectrum of an ideal black body for 2.726 Kelvin. So this is temperature of the universe’s background radiation.
The fact that the black body spectrum is almost perfect, suggests that the temperature is evenly distributed, suggesting that the universe was isotropic and homogeneous when the CMB was formed.
This means that the early universe was the same in all locations and in all directions, when the CMB was formed.
The isotropy and homogeneity resulted in a universe we see today where the average density of galaxies is the same throughout the universe and does not change much with distance or direction.
Why are there galaxies, solar systems, and planets at all? Although the universe was pretty isotropic, it was not perfectly so. It has a small anisotropy. Temperature of the CMB is 2.7 Kelvin +- 0.00003, a variation of 1 on 100,000. This anisotropy led to the seeds which have grown to the large-scale structure of the universe we see today.
The imperfections that led to the overall structure of the universe, are believed to stem from quantum fluctuations in the early universe. The fluctuations led to the fact that some places had a very slightly higher matter density than other places.
The fact that CMB is almost perfectly isotropic also supports the theory of cosmic inflation. If the universe expanded exponentially it would have stretched out space very fast evening out any significant imperfections.
The CMB also reveals that the curvature of the universe is probably flat. Curvature can be determined by gauging how much the CMB light has been deflected or “gravitationally lensed” while passing through the universe over the past 13.8 billion years.
If the universe was curved in any way, the temperature variations would appear distorted compared to the actual size that we observe with our telescopes.
In addition to flatness, the fact that there is a microwave background at all, is significant evidence that the Big Bang actually happened, because this leftover radiation is exactly what we would expect.
#CMB
#cosmicmicrowavebackground
You might ask, if we can’t see further back than 380,000 years after the big bang, is there an information barrier that prevents us from knowing anything about the universe prior to the CMB?
No because light is not the only thing that can carry information. Gravity waves may be able to tell us more in the future.

[@LordTetsuoShima]

Arvin is the type of teacher everyone wish they had in school

[@IncompleteTheory]

Take an actual class with Arvin including an exam and voila, it's just as hard as it was in school. Learning stuff and being able to calculate and reproduce it is always harder than just watching a cool YT vid. Nicely done as they are.

[@rds766]

I did but it was my history professor.

[@florh]

He certainly taught me a very valuable piece of information :-)

[@AJScraps]

The fact I have only Intro Astronomy from Uni and I understand everything he teaches is impressive of his pedagogical skill.

[@neonftw9658]

@@IncompleteTheory your right but interesting teacher = int student

[@MrPakurfulo]

"that's coming up Right now!" *Music starts It makes me happy.

[@TrapKingz.]

What is the intro song?

[@ArvinAsh]

Dark Synth Retrowave by Oleksandr Koltsov

[@user-jt6ej7vh2p]

Same

[@SomeAustrianPainter]

@@TrapKingz. Sandstorm, by Darude

[@MrPakurfulo]

@@SomeAustrianPainter XD

[@circuitboardsushi]

Parallel lines have so much in common... It is a shame they will never meet.

[@greensombrero3641]

YES

[@didierfavre2356]

Could our universe be non euclidian? In that case, parallels have interesting properties.

[@circuitboardsushi]

@@didierfavre2356 Of course. It is only flat according to our best measurements.

[@xyzct]

They will meet in spherical geometry.

[@circuitboardsushi]

@@xyzct Current measurements don't indicate positive curvature.

[@nope69q]

Arvin Ash: universe is probably flat flat earthers: WRITE THAT DOWN

[@arahman3897]

😂😂

[@effectingcause5484]

@@arahman3897 lmao

[@joemarz2264]

So now I am a flat universer?

[@effectingcause5484]

@@joemarz2264 Yes please become a flat-universer lol,, yu flat Earthers are really quite mathematically capable of explaining some issues if yu actually apply those principles and that dual logic process to the more agreed upon problems in physics

[@lupus7194]

It looks like a map of the world. You can clearly see north and south America just to the left of the centre. Then to their right is a blue section like the Atlantic Ocean merging into Europe with Africa clearly below it and Asia further to the right. Looking to the left of N and S America, you can clearly see the Pacific Ocean then East Asia with Australia well below it.

[@hmmpausethink4976]

This is a highly under-rated channel! Thanks Arvin, for putting together a regular schedule to educate the world on the magic of the true frontier. It’s only when everyone is brought to the same level of knowledge & understanding that humankind will progress. Here’s hoping the popularity of your videos expand at the same speed as the universe.

[@ArvinAsh]

Thanks. I couldn't agree with you more.

[@Dybbouk]

I don't think it's under rated. It's great!!!

[@AnthonyGoodley]

I can't imagine why someone would feel the need to leave a dislike on an educational video. You are here for free being taught by Mr. Arvin Ash in his spare time. Like what could a person really have to disagree with here?

[@Reasonably-Sane]

Some people just want to watch the world burn.

[@xx_xxxxx_xx4800]

lol. you're right

[@effectingcause5484]

Mr Ash got some serious haters who have nothing better to do than to come on every video and just thumb down... I just don't get it, it is seriously stoopid. maybe they are ppl who don't believe in science, who knows?

[@jpe1]

In addition to what others have proposed, I will suggest that some of the dislikes on some videos are made by bots, in order to fool the bot detection algorithms. The bot-writers want their bots to be able to boost likes and views for the videos of their clients, and of course Google wants to detect and shut down those bots, so when Google started shutting down accounts that gave 👍 with no 👎 (and other factors, since some humans never leave a 👎 either) the bot-writers updated their bots to leave random 👎

[@effectingcause5484]

@@jpe1 I think yu might have the best explanation bcus I just can't see why somebody will dislike any part of this insightful video.

[@satyr1349]

Explained in such a wonderful balance between simple and terribly complex (for myself to understand). Brilliantly done, great video!

[@ronnieripz]

Thank you Arvin. Your explanations of complex things help me to understand things I otherwise couldn’t.

[@jenjuice432]

I experience a feeling of giddiness when I start watching these videos - a sort of self-contained sense of excitement, because I'm so damn curious as to what's going on with the universe and why and how we got here...that these little bits of information kind of satiate that thirst within me. Y'know what I mean or am I just a weirdo?

[@FabianReschke]

It's called curiosity ;)

[@mrandersong1]

We all have that thirst but curiosity killed the cat.. meaning, the universe at full scale can't be understood..

[@jenjuice432]

@@mrandersong1 I don't think curiosity killed the cat is correct usage of the saying as it applies to your point - but in any case, I do agree that there's a lot that we as human with our feeble animal brains can't comprehend about the nature of the universe and reality as it objectively exists...but that's more along the lines of philosophical thought. The beautiful thing about humanity is that we utilize the scientific method to amass a large body of knowledge to get as close to understanding nature as we possibly can, and have developed advanced tools to 'see' or observe that which is beyond our scope of perception. With the data the scientific community collects, we render a working understanding of the intricacies of the universe. It may not be perfect but I believe we're slowly but surely peeling back many mysteries that were previously unfathomable not long ago. Props to all the great minds out there who spend countless hours crunching numbers and making sense of of this bizarre phenomenon we call life.

[@shaun906]

@@mrandersong1 unless we're in a simulation 😎

[@888PsyMike888]

I know what you mean and you're still a weirdo. 😁

[@MathAdam]

I'm never sure when it's coming up. Arvin Ash always tells me. And it's always right now.

[@Vatsek]

At least you are always on guard.

[@jeffrobinson1975]

The famous CMB picture is always hilarious to me because scientists literally always use it to demonstrate how remarkably homogenous it is, but using the ultra-enhanced version that makes it look totally heterogeneous at the microscale but don't explain that. Great explanation in this video though!

[@xXYourShadowDaniXx]

I also appreciate the explanation for WHY its mostly homogeneous, most videos never explain this statement. It makes way more sense knowing that those differences are microkelvin (ie almost insignificant) and not something like degrees celcius.

[@victoriay6246]

Agree with both. This video was a game changer on understanding the CMB.

[@chriskennedy2846]

I agree - I liked the video overall. However, the opening sequence requires further explanation. Arvin's channel is one of my favorite science channels but he (along with every other science video creator on the planet) never explains where the EM wave transmission along the pre-existing field lines fits into the stationary observer "seeing" light travel at exactly "c." This is important because the atoms in the car's headlights that produce light to begin with all carry electric fields that travel in step with the atoms (and therefore the car as well) before, during and after the light is produced. When the light is produced, the newly generated EM wave travels along the E field that was already in motion with the car. Someone should set up a computer model where, in addition to the car's driver, there are 3 observers. One in front of the car, one behind the car and one along side of the car as it drives down the road with headlights in the front and fog lights on the trunk aimed in the rear direction. Then track the motion of the car and the E fields that travel with it as light begins to propagate along the field lines in both the forward and backward directions. Good luck using length contraction and time dilation to satisfy all 3 observers. So how exactly did Einstein "show" that onlookers would see light go by at "c" ? Oh, yeah - now I remember, it was with an equation and a diagram of a moving frame with a silly triangular light path. Check any undergrad physics textbook and in the chapter on light, it will actually do a great job of describing light generation and propagation through a step-by-step description of an accelerating or level falling electron creating a kink in the existing E field that will move along with changing E and B fields. Then skip ahead a few chapters to relativity and you will find that all of that field stuff is magically forgotten.

[@WalterBislin]

@@chriskennedy2846 Did you take relativity of simultaneity into account?

[@chriskennedy2846]

@@WalterBislin How would that impact the computer model I suggested above?

[@brunolorenzo4574]

I just love how Arvin has it's own style like no one else on Earth.

[@wilsongomes3360]

This is what I call a masterpiece

[@hamoodykhalid3340]

quantum fluctuations is good topic to say it's coming up rrright now

[@jakublizon6375]

And now.

[@jakublizon6375]

And now too.

[@jakublizon6375]

Oh oh, now too! Okay I'll stop now lol. My apologies 😅

[@blindmoonbeaver1658]

I have to say that your videos are great. It very clear how much you are passionate about physics. You explain these complex physics concepts in such a simplicity that it feels like an beautiful and elegant work of art. I will always be looking forward for your upcoming videos.

[@ArvinAsh]

Thanks. Much appreciated.

[@xx_xxxxx_xx4800]

vsauce: hi. vsauce. Michael here! Arvin Ash: that's coming up right now!

[@SkywalkerSamadhi]

Anton Petrov: Hello Wonderful Person. Beau of the Fifth Column: Well, howdy there Internet people.. it's Beau again. Super Carlin Brothers: Hey Brother!! (I know those last two aren't science channels but I love a good KZbin intro 😊)

[@pierfrancescopeperoni]

The science asylum: hey, crazies.

[@WellMefisto]

"Hey, smart people! Joey here!" 🤔

[@oreowithurea5018]

Hey Vsauce!

[@NeonVisual]

If everything was at one point at the start of the big bang, wouldn't that make everything in the universe an entangled system?

[@ArvinAsh]

Interesting point. You may be right.

[@kurtn4819]

That would certainly support quantum interaction.

[@FobbitMike]

There exists a wave function of the universe.

[@hyperduality2838]

Entangled entropy or correlated information = syntropy! Time dilation is dual to length contraction -- Einstein, special relativity. A homogeneous universe implies that it is the same & equal for all observers or that the universe conforms to a principle of objective democracy. Objective democracy is dual to subjective democracy -- democracy is a dual concept. Science wins through consensus. Consensus = mutual agreement or objective democracy. Generalization (non-local) is dual to localization. Syntropy (prediction, projection) is dual to increasing entropy -- the 4th law of thermodynamics. Objective democracy is the scientific definition of democracy. The big bang is a Janus hole/point (two faces = duality) -- Julian Barbour, physicist. Topological holes cannot be shrunk down to zero. Homotopic equivalence = duality Injective is dual to surjective synthesizes bi-jective or isomorphism. "Always two there are" -- Yoda.

[@reessoft9416]

I don't think so. It took a while for the universe to cool down enough after the Big Bang for particles to form. As far as I'm aware quantum entanglement only affects a pair of particles. If there were no particles around at the moment of the Big Bang (just a seething sea of energy) then entanglement wouldn't make sense.

[@effectingcause5484]

Wow! This is the most detailed explanation of the cosmic background that I have ever heard.. I now actually understand with all intuition, why the background radiation is surrounding us from all angles. All I can say is thanks Mr Ash! Now it's time to for me to go into my deep thought processes.

[@korakys]

You just explained nearly a dozen concepts that could each have their own video. The information density here is extreme! I'm so glad that I was able to keep up with everything (without pausing) as that means of got a good grasp of the material now. I really liked the video Arvin.

[@andycopeland7051]

You took me down a wormhole dude. I learn much from you. This is so much better than drooling while scrolling down social media. Thank you for turning my mindless occupation into mind-expanding learning. You're doing great man please keep it up

[@oldmandoinghighkicksonlyin1368]

You always find a way to add to my understanding with analogies or metaphors I've never heard before.

[@KazimirQ7G]

Thank you so much for your content quality. I was positively surprised for the choice of using the metric system only and Kelvin-Celsius scale.

[@dr.jamesolack8504]

Thank you, Arvin. Always a pleasure to take in one of your new, well produced uploads. Sets my mind at ease. Rock on, brother! 👍🙏

[@jammandbz]

Subscribed after two videos. You teach this awesome stuff in a way I can understand

[@1984Phalanx]

I like to imagine our universe is a spent piece of nuclear fuel, cooling in a reactor larger than our comprehension. Our universe is just an atom to someone else.

[@edgaralvarezrojas63]

Thanks for the simple and understandble explanation of the complex phenomenums.

[@tim40gabby25]

Phenomena. Just saying :)

[@protoword10]

Best explanation of things we always wanted to know, but never have a good chance to inform ourself about these topics! My famous theme was about particles… I think this is best KZbin channel so far about explaining nature! THANK YOU Arvin

[@andrewwhite6]

Once again Arvin you just keep raising the bar! I have listened to some of the most talented scolars in the world try to explain this concept to to us mere mortals, just often leaving one more confused. In just 15 minutes you deliver succinctly. Too easy! Nice job thankyou!

[@bibinjose8853]

Frm Kottayam

[@aathaath8757]

From kollam😎

[@mraviteja22]

From andhrapradesh

[@shadowoffire4307]

Richard Feynman said once that "if you really want to master something, teach it" Arvin know this.

[@shadowoffire4307]

I choose Arvin ash video over a final match of fifa world cup football live match.

[@illustriouschin]

Let's take some time to "really" analyze this statement and learn why it is wrong.

[@TheWdupp]

Best explanation of the CMB I have come across so far!

[@stratpac]

Love this stuff!! Keep posting please.

[@asprywrites6327]

Sucking at math is the only thing keeping me from being a physics genius.

[@xx_xxxxx_xx4800]

it's funny how the two things everybody says they suck at is math and geography but nobody says they're bad at being creative

[@LuisAldamiz]

@@xx_xxxxx_xx4800 - I'm good at geography but not so much at being creative, I'm still better creative than mathematician though.

[@asprywrites6327]

@@xx_xxxxx_xx4800 I call myself Aspry WRITES. I Hope I'm creative 🤣

[@maximan4363]

Aspry, school told me I sucked at mathematics & I spent 25 years in IT, programming, engineering & running the Internet backbone! I study quantum mechanics & quantum computing and I still struggle some times with the math! We all do - the thing is to accept it, keep learning, one step forward! I have worked with some absolute mathematical Geniuses who couldn't use a screwdriver - honest to god!!! God bless you & you just keep following your dreams!

[@xx_xxxxx_xx4800]

@@maximan4363wise words, king!

[@bjm6275]

Great video Arvin! Would not the point that the CMB nearly mimics a perfect black body with evenly distributed temperature suggest that the universe is a closed system? Also, does not the overall gravity also suggest this? It seems an infinite open system would not result in even distributed temperatures nor the strength gravity over vast distances. It would seem that although the universe is overwhelmingly vast and immeasurable it is also a finite closed system, where energy cannot be destroyed.

[@joepeach997]

So patient and clear, thank you Arvin.

[@danjelskerfving533]

You're a genuinely benevolent guy, it shows, Arvin - extremely uncommon nowadays!

[@franks.6547]

11:22 must be "flat in 3D" not 4D. The 4D curvature corresponds to the accelerated expansion of that flat 3D-space - or a 3-sphere that is at least several hundred times bigger than the observable universe. But congrats to that great video, Arvin!

[@LuisAldamiz]

An excellent lecture, Prof. Ash. Conclusion: the universe is an orange and used to be orange. ;p

[@viseshjaiswal1068]

Amazing, looking forward for the upcoming videos 🙌👍

[@RichardAugust]

Awesome and incredible informative as always!

[@razeezar]

Perhaps the laws of physics do deviate in different regions of space/time. e.g. what we interpret as 'Dark matter' could be such a deviation, but we are viewing it from the perspective of our own local 'rules' of physics in this region?

[@jpe1]

One of the fundamental assumptions made by physicists is that the rules are consistent everywhere and everywhen. There are at least two reasons for that assumption: there is no evidence against it, and if we don’t assume that the rules are the same, then we cannot draw any conclusions at all. It’s important to continue to look for evidence against that assumption (for example, Modified Newtonian Dynamics (MOND) posits the possibility that gravitational attraction changes at very small accelerations and very large distances; crudely oversimplified, it says “gravity is different far away”) because new insights can come from challenging assumptions, but there has to be evidence, and so far all the evidence says the rules don’t change.

[@AltMarc]

@@jpe1 "... there is no evidence against it...", that's my problem with Dark Matter accounting for 85% of all matter..., how wrong do we need to be?

[@jpe1]

@@AltMarc if I understand your comment correctly, you are saying that the fact of needing “dark matter” to account for 85% of the mass of the universe means that the rules of physics must change. That is indeed part of the motivation or MOND, but there are galaxies that are observed to rotate faster, and slower, than would be predicted with MOND, so by itself MOND is insufficient to explain observations. I know of no other proposals for alternative formulations of gravitational attraction that are consistent with all observations without invoking dark matter, thus (while it pains me to do so) dark matter seems to be the explanation that fits the data best.

[@AltMarc]

@@jpe1 example from some Spanisch University, the "time is slowing down" theory where they got ride of dark matter, but there is still a 4% discrepancy. (for me that's an improvement) I'm very reluctant to change the rules of physics, but perhaps we're search "dark matter" at the wrong place. I say, that the whole expansion theory is viewed from the wrong viewpoint aka from our viewpoint. We have greater "expansion" locally (our galaxy) than outside (same points as the "time slow down" th.), nothing would need to change if we would say: The universe stands still BUT everything inside SHRINKS. Every physics rules would be the same BUT instead of searching the "dark matter" outside in the universe, it could be inside of us and everything...

[@hyperduality2838]

The laws of physics are the same and equal for all observers -- objective democracy! Entangled entropy or correlated information = syntropy! Time dilation is dual to length contraction -- Einstein, special relativity. A homogeneous universe implies that it is the same & equal for all observers or that the universe conforms to a principle of objective democracy. Objective democracy is dual to subjective democracy -- democracy is a dual concept. Science wins through consensus. Consensus = mutual agreement or objective democracy. Generalization (non-local) is dual to localization. Syntropy (prediction, projection) is dual to increasing entropy -- the 4th law of thermodynamics. Objective democracy is the scientific definition of democracy. The big bang is a Janus hole/point (two faces = duality) -- Julian Barbour, physicist. Topological holes cannot be shrunk down to zero. Homotopic equivalence = duality Injective is dual to surjective synthesizes bi-jective or isomorphism. "Always two there are" -- Yoda.

[@psanjay6847]

Thx bro like from kerala kochi

[@testuser5373]

Malayalii..😀

[@Regularsshorts]

Hey I'm from kottayam!

[@testuser5373]

From Thiruvalla..😀

[@johnn.3887]

Hey Arvin, thanks! You read my mind - CMB has been my latest interest and you answered my questions perfectly. Thanks!

[@starryodyssey]

Another magnificent episode! Thanks Arvin.

[@Regularsshorts]

"When there's life,there's hope." -Stephen Hawkings I don't know people are saying famous quotes,so do I.

[@omarcusmafait7202]

there is only one Stephen Hawking ;)

[@xspotbox4400]

What is hope, where does it come from? Hawking was a joke, in my opinion.

[@itszain6317]

Meaningless quote

[@mjzudba5268]

@@xspotbox4400 hope /həʊp/ Learn to pronounce noun noun: hope; plural noun: hopes 1. a feeling of expectation and desire for a particular thing to happen. "he looked through her belongings in the hope of coming across some information" Similar: aspiration desire wish expectation ambition aim plan dream daydream pipe dream longing yearning craving hankering a person or thing that may help or save someone. "their only hope is surgery" Similar: optimism grounds for hope promise light at the end of the tunnel Opposite: pessimism grounds for believing that something good may happen. "he does see some hope for the future" Similar: hopefulness optimism expectation expectancy confidence faith trust belief conviction assurance 2. ARCHAIC a feeling of trust. "our private friendship, upon hope and affiance whereof, I presume to be your petitioner" verb verb: hope; 3rd person present: hopes; past tense: hoped; past participle: hoped; gerund or present participle: hoping want something to happen or be the case. "he's hoping for an offer of compensation" Similar: expect anticipate look for wait for be hopeful of pin one's hopes on want wish for dream of hope against hope for Opposite: despair of intend if possible to do something. "we're hoping to address all these issues" Similar: aim intend be looking have the/every intention have in mind plan aspire Phrases hope against hope cling to a mere possibility. "they were hoping against hope that he would find a way out" hope for the best hope for a favourable outcome. "I'll just wait at home and hope for the best" hope springs eternal it is human nature always to find fresh cause for optimism. in the hope of with the expectation of and desire for. "they are carrying out surveillance of the area in the hope of catching the culprits" not a hope no chance at all. "he hasn't got a hope in hell of winning next year" some hope used to convey that there is very little chance that something will happen. "he predicted a new world order in which nations would learn to live happily with their neighbours. Some hope!" Origin late Old English hopa (noun), hopian (verb), of Germanic origin; related to Dutch hoop (noun), hopen (verb), and German hoffen (verb).

[@xspotbox4400]

@@mjzudba5268 Yes, thank you for clearing that term for the rest of us.

[@physicsisawesome4205]

Physics is incredible 'cause i'ts the king of all knowledge

[@xx_xxxxx_xx4800]

then comes mathematics and then philosophy

[@Paladin1873]

@@xx_xxxxx_xx4800 Physics is one form of philosophy explained by math.

[@xx_xxxxx_xx4800]

@@Paladin1873 i think you're wrong. you forget philosophy of logic, philosophy of mathematics, philosophy of science, metaphysics and epistemology

[@Paladin1873]

@@xx_xxxxx_xx4800 I edited my response to be more specific.

[@Kretion666]

G, You doing great! I watch most of Arvin's videos!! I hope more ppl get themself educated by watching your videos, You explain stuff simple yet accurate enough that it's scientifically sound! I double check most things you bring up as i love everything space- related, and you are reasonably accurate on EVERY topic and that i think is one of the best qualities of this channel!

[@full__tilt]

Arvin Ash explains things in the most eloquent way. Amazing content! 🙏

[@ikrishna06]

Imagination is more important than the knowledge -ᴇɪɴꜱᴛᴇɪɴ

[@chuckintexas]

But at SOME point you DO have to move from imagining to KNOWING, and from _THERE_ to _UNDERSTANDING_ , and THEN on through to _WISDOM_ . So far we seem _STUCK_ at- _IMAGINING WITH NUMBERS_ .

[@cosmicwakes6443]

If photons were more energetic in the past than presently, what happened to that energy?

[@Reasonably-Sane]

The expanding space-time stretched the wavelengths of the photons, spreading out the energy like butter scraped over too much bread. Because photons always travel at the speed of light through a vacuum, their wavelengths expanded as a result of the photons being locked into that speed, within a space-time that was stretching at an ever increasing rate. In other words, they had to expand to match the expansion of space-time in order to keep moving at the speed of light, because that is the only speed possible for a photon traveling through the vacuum of space.

[@LuisAldamiz]

AFAIK it's still there but more spread out: their energy/frequency depends on the fabric of space (space-time to be precise) and, as this one expands, they have to distribute their energy in a larger length, what leads to smaller energy in the quantum. Notice that this does not only happens because of Universal expansion but also because of individual motion of the sources in ways identical to the Doppler effect (which originally applied to sound waves, not light waves): when two galaxies converge, the photons actually gain energy, because the space is shrinking ever so slightly as they travel it.

[@yziib3578]

The law about the conservation of energy is dependent on time symmetry. All conservation Law are depended on a symmetry, Noether theorem. The energy/frequency of a CMB photon is lower because of the stretching of space-time and this stretching means that time is not symmetrical, so the energy conservation law does not apply. The energy of a photon disappears.

[@tim40gabby25]

@@Reasonably-Sane drawing a line on a balloon then inflating it works as an analogy too :)

[@ahmetakgun7709]

@@LuisAldamiz so, our cosmic light rays strecthed themselves thin to reach the ever increasing expansion speed of the universe. Doesn't this mean that the universe we are in is a finite, bordered, closed system?

[@moorara]

The quality of contents on your channel recently has been improved greatly. Thanks. I crave for longer videos with more advanced and complex materials.

[@ambrosioromero1539]

Remarkably clear 👌

[@endsinvention1390]

Congrats on 500k. Awesome videos

[@juan_zapata]

Thank you Arvin this is amazing

[@hanssacosta1990]

Wowwwww amazing video next level explanations ❤️❤️❤️❤️❤️ , thanks Arvin loved itttt

[@johnp1]

Best CMB explaination I've seen. Good video.

[@paulmarkham9689]

Thank you so much. Love your videos!

[@arnesaknussemm2427]

This is an excellent presentation. Thank you.

[@theRationalElement]

Best video ever on CMB!

[@robertspies4695]

Excellent job Arvin.

[@Josh-ify]

Just want to say, thanks for making Sunday mornings that much more interesting! Really been enjoying the routine of a second cup of coffee and a physics video these last few months

[@ArvinAsh]

That's great to hear! Hope you're getting something out of it.

[@Josh-ify]

@@ArvinAsh Yes sir! There have been several things your videos have gotten through to me that I had struggled with

[@laurencejohnston2191]

Excellent video as always

[@rajachan8588]

Brilliant, as always, Arvin 🙏

[@amedeofilippi6336]

Excellent video indeed!

[@poppa1050]

Well Done. Classic 👍🏾

[@entyropy3262]

Really well done. 👍

[@tberrardy]

Great video!

[@waltermanson999]

Oh My ! AMAZING !!!!

[@captainhadd0ck]

Excellent - my new favourite channel. 👌

[@philippepanayotov9632]

Amazing presentation

[@DonSolaris]

Totally dig the new look with the beanie! It's so gangsta!

[@anukritishrivastava30]

Very nice content!

[@gypsycruiser]

Pure Genius Arvin ! Very informative video !

[@ArvinAsh]

Glad it helped

[@Nick-zu9sn]

Great AA, just a fantastic conceptual explanation.

[@russiankid112233]

your content is A+ grade sir. thank you

[@ivanmoreno6956]

FELICITACIONES ARVIN por este programa y por todos los demas programas. Extraordinariamente claros y profundos todos. Un gran saludo desde la ciudad de Concepcion, en el sur de Chile. 👍👍👍👍👍👍

[@ArvinAsh]

Gracias. Me alegro que estés disfrutando viendo los videos.

[@the420aditya]

Wonderful video.

[@dynamicflashy]

Excellent video

[@user-fd6dx9mm3l]

Thank you

[@bilpersonal]

I just don't understand why my heart smile when I see Arvin's new video.

[@jeffwads]

Your best video yet.

[@harshal8956]

Great explanation

[@aarondelbosque1574]

great video! I've always wondered what perspective the picture of the CMB is taken from to better visualize what I'm viewing (which from your video I now believe is minute changes in temperature and quantum fluctuations from the beginning of the universe that led to drastic changes in matter density) please never become so big that you no longer interact with your audience 🥺 your dedication to the viewer is what sets you apart

[@anishashee8511]

Excellent explanation👍 🤩

[@johnshepherd6925]

Omg you've made an upgrade to your channel! Love the license plate on the car 👍🤣

[@geraltderivedroite]

Brillant video Arvin, very understandable clear and so interesting topic. Who knows in 25 years where our knowledges on cosmology will stand, maybe we ll finally know if universe has an origin... How we went from the void to something

[@tresajessygeorge210]

THANK YOU DR.ARVIN ASH...!!!

[@hareeshpentela5948]

Wow! Amazing! ❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️❤️

[@glieseseventen4921]

Arvin, this is one of the most profound and informative videos I've seen. You've explained the times after creation so well. I've understood what I had wondered for a decade. Thank you!

[@ArvinAsh]

Thank you. Glad it was helpful!

[@dr.jamesolack8504]

@Gliese SevenTen.......your use of the word “creation” is unfounded.

[@glieseseventen4921]

@@dr.jamesolack8504 the term "big bang" is unfounded. It wasn't big as it started from an infinitesimally small point, and there was no bang. We in this spacetime came into being at t=0 and creation is as good a word as any.

[@dr.jamesolack8504]

@@glieseseventen4921 I never used the term “Big Bang”. And “creation” denotes that the universe was made. It was not. “creation” is NOT as good a word as any as it can not be proven to have been “created”

[@glieseseventen4921]

@@dr.jamesolack8504 the term create can mean "cause to be created." There WAS a cause, a reason. Either a white hole spat us out, or another universe collapsed and we came into being. The word creation denotes causality.

[@veritasman]

this man is awesome !!!

[@mhschmidt01]

Thank you Arvin. Back in the 1950s as I was reading George Gamow authored books & other authors I seem to remember that the theory then was that the universe was curved. That meant theoretically that if you traveled from earth in a straight line that you would eventually come right back to earth at a much later time. This assumes that the earth was stationary for that period of time. From what I learned from you is that the universe is not curved.

[@ArvinAsh]

Correct. That's what the evidence seems to say. But I think you are correct that early on, maybe late 70s to even early 80s the prevailing thought may have been different.

[@illuminateknowledge9751]

Amazing presentation skills. Really fun to watch the video and learn 📖😇❤️

[@quadri567]

Amazing

[@aseemsharan]

14:20 So heartwarming to see that you had entioned about our upcoming expected achievement of detecting Gravitational wave Background 2 years back in June 2021. And on 28th June 2023 we actually succeeded in detecting the first Gravitational wave Background.

[@faizurrehmanansari139]

Amezing, fantastic, beautiful, incredible love to watch physics videos ❤️

[@seanmcdonough8815]

Arvin nails it again!

[@surendrakverma555]

Excellent 🙏🙏🙏🙏🙏

[@theklaus7436]

As usual a brilliant show. I have learned so much from you and your college 🎸😊 so exciting for me all these knew possible way to measure further back. Perhaps

[@geocrisanda]

Superb

[@Tiffany_Turbo]

Came for the science, stayed for the dope soundtrack that makes every episode feel like Mass Effect.