The Sky in 350 Billion Years

[@physicsgirl]

Our sky won't look exactly like this in 350 billion years, because we won't have a sky. The sun will have swallowed Earth 342.5 Billion years prior in a spectacular all-you-can-eat planetary buffet.

[@beaumullins38]

Question, if lets say another planet is moving away from us faster than the speed of light, and the speed of light and time are similar, would they seem to be going backwards in time to us if we could observe them somehow?

[@lt_johnmcclane]

Yummy

[@deodatsingh4621]

I understand Galaxys are getting harder to see, but stars in our own galaxy are disappearing too? That mean our galaxy is getting bigger 🙄

[@utubeableact]

Why swallow?? Space is expanding. But the objects embedded in space, like planets, stars, and galaxies stay exactly the same size. Sun is also a star then why would it swallow all planets??

[@anandmistry4850]

Does this mean that the cosmic microwave background could just be the remnant of light from galaxies beyond our observable universe and this light has been redshifted so much that we can only observe it in the microwave / radio spectrum instead ?

[@herblison3374]

Physics Girl is a wonderful inspiration to young people everywhere to study science. As an MIT alum I interview high school students applying to MIT. Many of them mention Physics Girl as a favorite way to learn about cutting edge science. People like Diana are essential for the health of our world.

[@sorroplayz]

Thank you for this episode physics girl, growing up I loved everything about cosmology, but life took over and my passion fadded, over a year ago I came across your channel and you ignited my interest, thank you so much, The mental wellness that you spread to others is so important and understood by more than you can believe, we understand and thank you for helping everyone learn that bit more about life.

[@Willbolt_]

:)

[@ericparrish1515]

I'm offwhite

[@YummyPork]

Loved the analogies you used to describe this mind bending stuff. "Stickers on a slinky" and "Humans are like rhinestones on stretchy pants" are going to stick with me as much as "We are made of star stuff"

[@xLatinAssazzin]

Spiderman no way home the video game kzbin.info/www/bejne/b4fdcnhjec6fldk

[@Skeptical_Numbat]

The "We are made of Starstuff." was one of those amazing statements made by the late, truly great, *Dr Carl Sagan* back in the wonderful *_1980s_*_ Documentary_ *Cosmos.* I highly recommend watching both the *1980s* original (preferrably remastered) & the *2014* remake/sequel with *Neil deGrasse Tyson.* Both have amazing science facts, history & philosophy, and are simply wonderful to watch - especially with curious kids (like I was when the original came out, all those decades ago).

[@parksnewbornportraiture4989]

Rhinestones on stretchy pants. I love it!

[@guillaume5313]

@@xLatinAssazzin yes

[@JROD082384]

But her video is wrong and misleading.

[@kosys5338]

Diana is the perfect educator, she makes learning about the universe and the physics that rule it interesting and fun. It is always a pleasure to learn what she has to teach even though her teachings most often raise even more questions. Keep up the great work Physics girl.

[@thetruffleist1297]

Her and Scott man

[@godsbeautifulflatearth]

The Earth is Flat.

[@noobkingd706]

This video explains why i rarely see stars in my place, i only see 1-13 stars also + the sun lol

[@TD_JR]

First time visiting your channel - and I appreciate the effort spent in giving props to some relatively unknown names in the history of cosmology. I have a bit of an interest in history itself and often times, those who've contributed even the smallest achievements in history are overlooked by those who've expanded on their discoveries to finalize achievements we attribute to those who've crossed their t's and dotted their i's with the work of those that have come before them. Here's to you Henrietta Leavitt... you did good.

[@ericparrish1515]

That you Aurtouro?

[@-First-Last]

@ T D Did you read the title ?

[@TD_JR]

@@-First-Last Did you watch the video? I was commenting on some of the names mentioned in this video that people haven't heard of before and yet, have contributed much to astronomy and cosmology over the years.

[@liamclarke64]

My mind really starts to "blow up" when I consider the fact that we can't be at the center of the entire Universe - so what "shape" is it, and where are we in it? I understand that we must be at the center of the "observable" universe because we are the observers, so that is not what I am saying. I love this channel; it makes me try to think about the unthinkable :-)

[@k1ng401]

Haha I had just started asking “why are we in the centre of the observable universe? Bit of a coincidence…” and then I realised “duh” 😂

[@suncat530]

@@k1ng401 it's like asking "why are my eyes behind my field of vision" lol

[@liamclarke64]

@@k1ng401 That is exactly why I love these videos, because it made you think about that, and now you understand. I love it when my brain does that - a light bulb moment!!!

[@_mortiam]

For the universe to have a center or a shape at all, it would have to have a boundary. Which it doesn't as of current knowledge.

[@gabor6259]

@@_mortiam It doesn't have to have a center or a boundary if it's the 3D surface of a 4D sphere.

[@nowammies9986]

I remember going to the Lick observatory in Mount Hamilton just outside of San Jose, with my university. I got to look through the main telescope and see a star that was light years away with my own eyes. It was such an eye opening experience, and I am so glad that places like this exist and that you get to share them here with us on the internet!!

[@colorgray3251]

You're so lucky!

[@colorgray3251]

Also thanks Dianna, you're awesome

[@Graeme_Lastname]

They're all light years away. ;)

[@dannyarcher6370]

Ummm. All stars are light years away...

[@Graeme_Lastname]

@@dannyarcher6370 You noticed?

[@spoorky7718]

Please keep doing space stuff! These are incredibly fascinating and entertaining!

[@DNTMEE]

To me, one of the most mind-bending things about light is that, as it travels through space, time does not exist for it. If it was somehow "aware" a photon of light would think it left the source which created it only an instant ago. Even if it has been traveling for billions of years. The instant it hit something and stopped, it would think it just left the source a moment ago. It would be very confused since it saw nothing in it's way just before it started on it's journey. From it's perspective something jumped out in front of it just as it left. I believe that is also the reason it can keep going and going. If no time passes for it, no energy is given up. Also, no matter how long it travels it will never get lonely.

[@tomwaller6893]

Wonderful, 72 years young and still learning. Blown away by this.

[@suzannestrickland1586]

Awesome sponsor! Thank you for helping remove the stigma of talking about mental health. It is definitely an important topic. I got to see the pre-release version of this video. Wanted to say that the additional visuals and examples were excellent. The things we learn about the universe are mind blowing. It has sparked some questions. I will have to write them down so I can send them for the next live stream.

[@Thebreakdownshow1]

Physics girl would be an excellent show title for kids. Superman, Wonder Woman and physics girls. It’s time we make science more friendly for kids. Keep up the great work you are an inspiration for me as a creator.

[@KCadbyRacing]

Agreed!!! 👍 Kids need to be shown there are other things to 'life' other than video games and social media...

[@Thebreakdownshow1]

@@KCadbyRacing growing up I had so much cool stuff I watched that got me intrigued towards science and critical thinking. I see that missing from the big organizations.

[@Thebreakdownshow1]

@@glauconeto what was your favourite show growing up?

[@KCadbyRacing]

@@Thebreakdownshow1 Kids interests (or lack of) starts in the home with the parents, that plus too much of todays daily input are all digital now. I grew up through the land-line only and b/w to color TV transition days = we were almost always outside doing/learning _real world stuff_ ...

[@user-pd9ju5dk5s]

But then Superman and Wonder Woman would be breaking physics while Physics girl wont?

[@herculydia]

Your hair looks Amazing. So healthy! Thank you for your opening comments and encouragement. I have felt so different and down and out of sorts with the huge ripple in our society and conflict reaching all our friends and family. Better now and so truly glad to see a new Physics Girl video to watch several times to grasp all the knowledge available. Thank you!!

[@d.castillo9495]

I'm still in awe of when I heard that the fastest human made object in space would take thousands of years just to reach the next star system in our own galaxy. When you talk about billions of years at the speed of light, forget about it.

[@vb2388]

JWST itself is taking a month’s time to reach around 1 million km.. The nearest star apart from Sun is 36 quadrillion km away from us.. So yes, definitely will take time…if my calculations are right…it would take JWST 90 million years to reach Proxima Centauri

[@godsbeautifulflatearth]

Who told you that..?

[@VORASTRA]

@@vb2388 your calculations ignore the fact that JWST sent the way it always slows down to the point where in L2 it has about 0 m/s speed

[@vb2388]

@@VORASTRA I took it as an average..rather what speeds JWST was travelling in every single point.. JWST definitely starts fast and slows down in the end as it reaches its destination..

[@Yora21]

The speed of light seems incredible fast here on Earth. But on galactic scales, it's incredibly slow.

[@saltadmin7829]

I've watched a lot of descriptions on dark energy and the expansion of the Universe, and I can honestly say this presentation gave me the best visual understanding yet

[@davidh.4649]

Awesome video Dianna! As I watched this video I found myself thinking, you know, as good as Carl Sagan was, as good as Neil deGrasse Tyson was, I'd love to see Dianna do a season of Cosmos! You'd be great at it! The whole key to Cosmos is being able to explain highly technical things in layman's terms that people can relate to. You've already proven on your channel with lots of great videos that you can do that. And your geeky enthusiasm (I say that with admiration and affection 😁, I'm an engineer so I know what it is to be a geek) makes people want to listen to you. 😊

[@mysterymeat586]

Dunno. Her pretty face might be a distraction for us men.

[@Magnetar_Haunt]

@@mysterymeat586 There were definitely less odd ways to compliment her, lol.

[@mysterymeat586]

@@Magnetar_Haunt Yea, couldn't help myself.

[@whydidyouresign]

Neil still IS, man!!

[@DNTMEE]

Unless you bite the heads off of chickens, you're a _Nerd,_ not a Geek. Well, okay, that's what "Geek" originally referred to. Mostly side show performers who did things like being a human chicken guillotine. Over the years it morphed into just another term for a tech freak.

[@Sela2125]

I cannot properly describe my excitement whenever I see there's a new Physics Girl video. You have such a passion, not just for teaching, but teaching in a way that makes one happy to learn and wonder. You are, in my humble opinion, the Bill Nye for a new generation!

[@josephc6588]

I just discovered your KZbin channel and I’m hooked on your presentation and intelligence. I love science and you make it fun to learn. If possible can you talk about the 40” Refractor at the Yerkes Observatory and the other early telescope’s that made Cosmological or Astrophysics possible. The Hale Reflector I’m sure would be included on this special list.

[@davidvernon3119]

“Humans are like rhinestones on stretchy pants” absolutely the girliest explanation of the expanding universe I have ever heard! (and I love it)

[@__eachfire__3418]

I love your work physics girl. Thank you so much for creating all of your wonderful content.

[@geoffstrickler]

It finally clicked for me the the expansion of the universe, and grasping that space itself can expand faster than c, also explains the incredible expansion of the universe during “inflation”. It doesn’t necessarily require a different set of physics, although gravity could not have operated the way we understand it today.

[@randar1969]

yeah if you take the current speed 73.3 km/sec per Mpc (Mpc=3.3 million lightyears) you can roughly calculate when the space between two object is so fast the lightspeed is slower. Like she said nothing can move trough space faster then light but space can expand with 73.3km/sec each 3.3 million lightyears. The only reason Andromeda is heading towards us is because gravity brings them closer together at an speed that is greater then the expansion speed. But it looks like the expansion is going faster over time.

[@alwaysdisputin9930]

@Robert Evans Yes, we are travelling FTL & we are not & there's no contradiction because speed's relative. When going along a motorway, a car travels at eg 100 km/h & it is also stationary. If you throw a ball into the air inside the car, it'll just go up & down like you're stationary. Because you are. In that frame of reference. & in the frame of reference of a far galaxy, we are travelling FTL.

[@trstmeimadctr]

The Mt Wilson session director seems like one of those people that you would be fine listening to explain literally anything

[@vigilantcosmicpenguin8721]

He seems like the one person at a family reunion whose stories you'll always want to hear.

[@ianndurocher7925]

He sounds like someone who would send you get the dragonstone

[@wmellor87]

cool and relaxed in the pursuit of knowledge

[@hoppeltrottel7484]

Diablo III plot twist: Deckard Cain feigned his death and changed his name to become the Mt Wilson session director. "Hello my friend, stay a while and listen..."

[@MonesMuziekFabriek]

I LOVE how Dianna gives credit to women who should have been rewarded in the past

[@nate.r]

You seriously make some of the best videos on KZbin always 10/10 and jam packed with information. Props and thank you for your work

[@jazznik2]

I went to the Mt Wilson telescope years ago (took somewhat longer than an hour from LA). It's worthwhile for anyone interested in astronomy or cosmology. I also observed the "inversion effect" where you can see the smog of LA trapped at below around 4000 feet. The air above still remains very clear.

[@BenC20B]

You didn’t take a horse and cart did you?

[@alwaysdisputin9930]

@@BenC20B er that might've been me. What can I say? I felt like a bit of joyriding.

[@vigilantcosmicpenguin8721]

@@BenC20B They said "years ago," didn't specify how many. I assume they meant it happened in 1900.

[@wmellor87]

I felt for those poor people living their short lives under that layer of pollution

[@thylacinenv]

Is the edge of the universe smooth or does it resemble the outer edge of a sea urchin where dense galaxies with a greater concentration of energy drive and contributes to the expansion of space itself? Is this possible without dark energy? I really wish Henrietta could have known just how much we admire her stunning contribution these days, she was an astonishing woman.

[@RobbieRosati]

The edge of the observable universe is very smooth actually. We've measured the lumps of the earliest things we can see, and they're only around 0.001% of the average value. On big scales, the universe is not very lumpy at all, there are about the same amount of matter per volume everywhere. And the further you go back in time, the less lumpy it is.

[@GlenBradley]

We have no idea what the actual "edge of the universe" looks like nor do we even have any real data from which to speculate on. The edge of the OBSERVABLE universe is incredibly smooth, because it's all but the inside of the Big Bang, ie the cosmic microwave background radiation from the hot plasma soup that came immediately after the Big Bang. Once your observations get out to around 14 billion light years away, you are looking 14 billion years into the past, and therefore the Big Bang. We cannot see anything past 14 billion light years away because past that there is no universe to look at, nevertheless the ACTUAL universe may be 60 billion light years ... or 600 billion light years across. We are limited in our observations by the speed of light.

[@maartenvd2653]

I think there is no edge in a real sense: the earth is on the edge as seen from the edge as determined from the earth viewpoint.

[@thylacinenv]

@@maartenvd2653 Thankyou for putting my brain cells into panic mode, it's a mind boggling concept..

[@Nighthawkinlight]

Not enough science is done with pipe smoke these days.

[@alwaysdisputin9930]

David Tong says: "There are many places in the universe where solitons form, smoke rings in air..." kzbin.info/www/bejne/e5XIo5mqbsmel8k

[@johnkemas7344]

I wish I had instructors like you in high school and college!! Keep up the great work! Your smile and enthusiasm are infectious!! You are now my co-favorite physicist, the other being Dr. Tamatha Skov, a solar physicist and and an amateur radio operator. You two are both well educated, informed and very intelligent. I am an amateur radio operator and have spent my career as a devoted science person.

[@donsheffler]

This was great. My family and I hiked all the way up Mt Wilson about a dozen years ago - what a climb! - but had no idea that this was such a distinguished famous observatory.

[@christopherbarber9351]

Thank you for your work! I hope you'll continue taking care of yourself -- you and your work are very valuable to us viewers.

[@DrewBritten]

Mind blown! This episode was so fascinating and so mind bending at the same time. Thanks for seeking out the brilliant women scientists of the world who have succeeded despite all the obstructions in their path. I just ordered a copy of Dr Mack's book, and can't wait for it to arrive! Also, thank you for taking time to step away from KZbin for your own health. Your content is always worth the wait, even the less polished early videos.

[@GlennRiccobono]

"A Roomba exploded" sounds like a future video, Dianna... 😎👍 Happy holidays!

[@Flesh_Wizard]

Tsar Roomba lol

[@RideAlongAdventures]

I’ve watched this dozens of times. I keep hoping my brain will grasp even the smallest part of this. Until then, I’m left with this incredible, exciting awe. Thanks for sharing this in such an inspiring way. Also, hope your feeling better. I/we miss you!

[@quantonica5348]

I don't always sit through the sponsor part but I did in this case , it's comforting to know you are taking care of your mental health and well being. I can wait a while for a new video with the knowledge you are coming back with your happiness and enthusiasm fully charged with excitment for all things Physics.

[@ericvanvlandren8987]

Dianna, I love your videos so much. I’m glad you take breaks for yourself. I’m sure you know (but it is always important to hear) that you have thousands and thousands of people who support you and care about you - thanks to your channel. You’re the best. Happy Solstice.

[@u6106l]

Excellent episode! Thanks for your efforts to bring science to the masses.

[@Tralin]

Always love these videos! Caught one thing though: "I hope that sometime down the road our ancestors are blown away by what we don't know yet." I think you mean "descendants" :P

[@alwaysdisputin9930]

the spawn of our loins' spawn of their loins' spawn of their loins yeah 'descendants' is better

[@Tralin]

@@alwaysdisputin9930 Actually. I changed my mind. I'm with you.

[@DrRiq]

@@Tralin what? he agreed with you already. you didn't need to change your mind

[@Tralin]

@@DrRiq I was making a joke, bud.

[@DrRiq]

@@Tralin ...

[@lucassimon4348]

New here this is amazing to think about! Hope you feel better soon ❤

[@turkfiles]

I’m responding rather late considering when you made this video. With your travels to the Mount Wilson Observatory in mind, I would like to bring up the Palomar Mountain Observatory in San Diego County which is run by Caltech. (FYI, I am aware of the rivalry between MIT and Caltech:-). There is a book called “The Perfect Machine” which chronicles the building of the Palomar Observatory. However, it does cover a tremendous amount of the history about Mt. Wilson which is where the beginning of the idea of building something larger than Mount Wilson occurred. Hubble is mentioned throughout the entire book. I do recall reading about the woman photographic interpreter who’s incredible insight came across the variable stars which allowed Hubble to turn the world of cosmology upside down. I’m sorry if someone else has already commented on this. I just didn’t have the time to go through 2.1 thousand comments. Please keep making these videos because I love them! 👍🏻

[@ericparrish1515]

You got a crew then. Your leaders get along? Common goals.

[@Let_The_James_Begin]

I'd love to learn how time dilation figures into universe expansion and the cosmological horizon. It might turn my brain into oobleck but I still want to know.

[@johnchessant3012]

A very strange mathematical fact: If the universe expanded at a constant rate, then it would actually be possible for light currently emitted by a distant star to reach us, though it would take a long time. (basically, the fraction of the total distance the light travels per second decreases over time, but slowly enough that the sum still diverges -- see the Wiki page on the "ant on the rubber rope" puzzle.) But this is not true if the expansion is accelerating!

[@YoutubeHandlesSuckBalls]

No. There would still be a point beyond which we were unable to see objects. Because each light year stretches the same amount, something 2 light years is moving away twice as fast because you add up each segment, which means objects further away recede faster. However slow the expansion, even if constant, there would be a point moving away faster than the speed of light and so no light from objects further than that would ever be able to reach us. The acceleration of the expansion merely exacerbates this and will lead to the 'event horizon' becoming closer over time.

[@super_hero2]

​@@KZbinHandlesSuckBalls I think you misunderstand what John said, when he says "the universe expanded at a constant rate" he meant that every year, the distance between 2 objects in space increase by the same amount. So year 1 add 1 light year, year 2 add 1 more light year, year 3 add another 1 light year and so on. Which is different from what you meant by "each light year stretches the same amount..." which is not constant amount every year because the added space also adds more space. In John scenario, light will eventually reach us, in your scenario it might not reach us.

[@MorganHJackson]

Awesome video, this explained a complex concept really well. I'm also really glad to hear you take time off for yourself. Your own health is the most important thing, it's so good to hear you can take time to look after that.

[@asherplatts6253]

I'm excited to watch this episode. The thing that keeps blowing my mind is that the distant light we can see is from when the universe was smaller, but it's bigger now, so we are seeing a 3-D image of a smaller universe that is now bigger than it looks. Which I can't quite wrap my head around without employing the weird curves of a 4-D sphere that "turns" backward on a time axis as you increase distance from a center point.

[@humblyright]

Such enthusiasm, knowledge, and passion for science & life. You are an inspiration Dianna and you have the support, love and prayers of millions of people around the world. We miss you, get better soon.

[@bdgrandin]

This is a all very interesting. Weird question. Has the expansion effect where a far enough galaxy's light will no longer reach us been observed? Have we observed a galaxy’ disappearing from our view due to the expansion between us and it becoming faster than light can travel from it to us? Are there recorded examples of this occurring. I would think if the theory is true we should be able to see it. That discovery and proof would be great to share and show people.

[@garykoponen7244]

They mentioned that galaxies on the edge of the observable universe would fade out. It seems to me that when a point in spacetime coincided with expansion that they would blink out.

[@Demonrifts]

We've only really been able to look at the edge of the observable universe for a few decades now. On a cosmological timescale, that is less than an eyeblink. Factor in that there are billions of galaxies, the likelihood that we would notice one of them suddenly fade out is abysmally low. I wouldn't expect that that will ever be something we witness.

[@CrazyTechy]

Great astronomy stuff, and you’re fun to watch. The number of galaxies and the expanding universe is mind blowing. I’m an elect engineer with a computer background.

[@Roberto-REME]

Outstanding video: very informative, lots of learning, fun, interesting and excellent narration. You're the Best Dianna.

[@requiemglassworks9254]

I love how excited you get about the sombrero galaxy at 2:00, that put a smile on my face! Exploding rumba galaxy sounds better!

[@jimkarasek4046]

I’m 66 years old. Even though I get lost in some of the details you talk about , the overall concepts really get me interested in never stop learning.

[@agargamer6759]

I watched the video already familiar with the cosmology side of things, and I was struck by the human experience that you captured here. What were these people like? What was going through their heads as they made discoveries that we still talk about?

[@montanateri6889]

I love your shows. And I love the clear joy that shines from you in imparting knowledge. In discovery. In science. You rock!

[@marcuswelseh9000]

Despite the economic crisis,this is still a good time to invest in stock and Crypto trade🥰

[@martins2375]

The rich spend less and invest more..

[@gratisgratis7275]

Investing in these economic crisis will be one of the best thing to do..

[@ryanscribner9285]

@@gratisgratis7275 You're right! I think stock and Crypto are the best😊

[@dimitratzina6919]

As stock's are good but crypto is better?

[@davisonmichigan4039]

I wanted to trade crypto but got confused by the fluctuation in price..

[@kasualbeauty309]

This kinda describes some of my dreams where I’m climbing stairs that never end the end seems near but when I go towards it it gets further away. Same with hallways or when I’m trying to reach someone important during crisis or catastrophe. It’s quite daunting

[@patrickcrowe5106]

THANK YOU!! You and Dr. Mack have cleared up a great mystery for me, with one sentence; "Nothing says that the 'space' can't be expanding faster than the speed of light." It's amazing to me how easily you smart physicist-type people can explain these topics!

[@tommckinney1489]

The key to understanding the stars "blinking out" is that the galaxies themselves aren't moving, but the space between them is expanding faster than the speed of light. So a photon of light emitted by a star will never get to us. This has always been a great mystery to me but your video cleared it up. I hope I have summarized it correctly, please correct me if I'm wrong.

[@otterspotter]

I'm really grateful that you broach the subject. As someone with a severe mental health disorder, I have the hardest time with this. You make it easy.

[@otterspotter]

You make it so plausible and nice to just be me. Thank you, physics girl. You are stand out awesome. Thank you.

[@MrJdsenior]

All those galaxies are not moving away from us. We are in fact moving away from each other. In other words, if you pick a point halfway between any two equally distant objects they would be moving away from that point at the very same rate. Also, the observable universe is unique to your position. For the voyager probes and us the observable universe is shifted about 21.5 light hours...not too large an amount compared to 13.7 billion light years, but still, a very slightly different universe. For a being living at the very edge of our observable universe, the universe we have in common is the intersection of the two observer centric spheres. And when they look at the same galaxy close to them, in our direction, they see it in a MUCH more recent configuration...and that is a mind game proof that their time and our time are billions of years different.

[@JjVa20]

I love how she says "Goosebumps!" with the biggest smile on her face 😊

[@v3nt1main]

My dad once told me (when I was around 8 or 9) that it's the lights here on earth that is causing the thing of why we can't see the stars but after I watched this, I was kind of scared but like I watched 3 of your videos and I liked it and i really love your channel! It helps me learn about these kind of stuff that I never learned in my life!

[@demonicmaleficentviciously140]

So cool! Ive hiked chantry flats so many times, I didnt know the Hubble was up there!

[@lbeanie692]

10:00 I'm so glad she added that arrow.

[@Mike504]

Merry Christmas (or your equivalent) and love to Dianna and all.

[@bldallas]

Just mind blowing. I’ve a retired civil engineer (P.E.), with a very solid grasp on Statics, Structural Engineering, Trig, etc.; When I was an EIT, we didn’t have computers 🤓. But space has always boggled my mind. I can “prove” the the forces, bending moments, stresses, strains, measurements, etc, in my universe (pun intended), but this stuff boggles my brain.

[@ronniescrazyadventures2478]

Thanks for flipping my understanding of the universe on my head Diana! I love this work.

[@shaileshrana7165]

I love your work, Physics Girl. Thank you so much for doing this.

[@cyrus05w]

At 4:10 with knowing what's going on currently seeing this part of the video is a little saddening I do hope things get better as they have been. Random comment but I hopes and again thank you for all of the content as well as all the support you guys have been giving and giving to us as the viewers , I'm new.

[@ZMacZ]

20:45 Common misunderstanding, light emitted, once emitted will stay travelling at c. Even if an object would move away at 10x c, once the photon leaves it and has a course that will bring it to us in x years, it would still travel at c. The object itself and it's speed have no bearing on the light reaching us, once emitted from the source. And like said, a speed differential may exceed c, for up to 2c, and even then the object itself does not have to exceed c. Let's say we travel at 0.1 c from the Big Bang, and we see an object travel at 0.95 c away from the center of the Big Bang in the opposite direction, the speed differential would 1.05 c, but the object itself would still only be at 0.95 c and thus not exceed the speed of light. But even with this speed differential any light emitted from that source would still reach us, since we only travel at 0.1 c and once emitted the photon would still travel at c towards us.

[@TheNightowl001]

I got into an argument with a "classically" trained friend of mine once, when I tried to explain (incorrectly) that things "could" move faster than light. My explanation was that if we look at something traveling away from us at 51% the speed of light and something moving away from us in exactly the opposite direction at 51% of the speed of light, they would be moving away from each other at greater than the speed of light. Karl, my friend, of course argued that "No! NOTHING can move faster than light!" I didn't know how to explain it any better (to be honest, this was probably 40 years ago and I was barely out of high school), but NOW I know how to explain it! Thank you for this!

[@reggiebald2830]

I was fortunate to grow up with the San Gabriel mountains as my backyard (Pasadena)! Mt. Wilson Observatory @ 14!

[@jimjames1920]

Your videos are important and useful for folks not in this field ! Both fun and interesting. There is a saying in golf that applies "Just because you can play golf doesn't mean you can teach golf ! You are a great teacher and explainer. That is your special valuable skill for astrophysics. Never sell it short !

[@rayoflight62]

Very, very well explained. I read Weinberg book "The first three minutes" when I was a student; at the time, it took me an entire week to grasp all the concepts which you and Dr. Mack explained clearly in few minutes. Thank you...

[@mercenairy1]

I LOVE YOU PHYSICS GIRL...YOU MAKE PHYSICS FUN!!! NEVER A DULL MOMENT... IM A HUGE FAN (200 POUNDS..LOL) THANK YOU FOR SHARING ALL THE AMAZING THINGS...AND HAPPY NEW YEAR

[@elmol5610]

Hello Physics Girl, please keep up the good videos. Just one observation, at the end of this video you talked about how you wonder how our ancestors will be blown away by the things we yet don't know. I think you meant to say our future generations. (ancestors refers to generations that lived in the past). Yes, I do like your videos and I do pay attention at your teachings.

[@KonwTheTrut]

Omg I cannot wait to read her book. Always been fascinated with the after after. Thanks for the recommend.

[@sptrob]

Physics girl ! The first videos you published connected visually with your great character and persona you exhibit. I now see you have changed internally and reflective. Life is always changing just like the universe. Why are we here when it will always be here?

[@darylpeterson9115]

This is way above my education level but I love it. Thats for sharing your knowledge. I'm hooked

[@marancibia1971]

Dianna, I love your videos. Your passion for physics is contagious. Greetings from Chile.

[@kapilchhabria1727]

knowing what Dianna is going through right now, its both heartening and depressing to watch this now...

[@charliestone8397]

There is a play called "silent sky" about Henrietta Levitt. It's a pretty good play.

[@chrisandlane]

I was wathing the lift-off of the Webb telescope live and couldnt help but think of you. Happy holidays and happy new year!

[@anastaciochapa5198]

I think the universe is expanding into an infinite void, essentially a perfect vacuum. Theoretically the universe should expand and accelerate forever. At some point in time everything in the universe will be traveling faster than the speed of light, at which point time equals zero.

[@jeng3000]

Around 9:50, summed up: We and these furthest galaxies aren't really "moving" away from each other necessarily, it's just that the space between us is increasing very quickly, too fast for light MIND EFFECTIVELY BLOWN

[@trepplee]

I could sit and listen to you for days n not get tired!!!! Love ur vids! Amazing stuff!

[@GermanShepherdDaphne]

I wonder if dark matter is on one side of the universe and matter on the other? Think about it. Because dark matter is basically repulsed by matter. This is causing our universe to stretch.

[@russellvellos9678]

Your hair looks gorgeous and I admire your very obvious love for teaching the universe to people like me who are fascinated by it but don’t really have a good understanding of it.

[@eireland9521]

"We are just stickers on a slinky." The pale blue dot wasn't existential at all compared to what Diana has been teaching us lately. Oh please , talk nerdy to me Physics girl. This is truly wonderful stuff on the internet and should be shared with as many people as possible.

[@LolUGotBusted]

A couple questions arise. 1) Does the density of the early universe affect the passage of time and is that accounted for (or does it even need to be) when calculating its age and expansion? and 2) In the case of two observers in overlapping observable universes, could one observer communicate the inaccessible information to the other observer, or would it mean that the first observer crosses into the event horizon of unobservability upon accessing?

[@LolUGotBusted]

@@UncommonSense-wm5fd Two observers, occupying two locations inside a shared observable universe, each with access to a slice the other doesn't have but occupying inside the same Universe (this is the aforementioned overlap). Except one can see farther one way and the other can see farther the other way because they aren't in different universes and therefore can exchange information according to a Penrose diagram? How is the speed of light too slow? If they are in the same Universe where, say, you and I are, in two different locations, where I can see farther and maybe I'm deciding to communicate with you? Is this communication here between us, at sub-light speed, is not fast enough?? Is that what you're saying? I mean if they were not in a shared universe what question would I even be asking like seriously? Just to reiterate these two same universe enjoyers are not physically located in the exact same place, you know, being two different observers and all. I kinda need them to be some distance apart for them to have some access the other doesn't in an Einsteinian thought experiment?

[@normhill6985]

Best explanation I've heard so far.THANKYOU.

[@muthukumaranl]

Thank you for this wholesome piece...even though i knew a little bit about the subject i still found it infotaining with those historical context that you so nicely placed it in...

[@ZMacZ]

16:46 Light vs. the start of the Universe, means speed times time, expressed both in years and lightspeed, meaning lightyears. We can actually tell that the size of the Universe is larger than we can actually see, simply by knowing it comes from all sides, but us not being the center means that some light is still travelling to us. Also on top of that there's what we see of the Universe, which is then equally old information. If the distance is 1 million light years, it depicts the situation of the Universe as it was a million years ago, which in turn means that depending on which side you extrapolate we can also figure out where something would be today, which then also adds to the maximum distance we know to exist in the Universe. One thing is for certain, we have not yet reached the limit of the Universe and with that a new information may actually be gathered and that is that not all of the matter within is aged the same way, and that we may yet be in a newer or older part of this formation. This in turn would then also express that there's yet much more Universe 'filler' than we know. In fact at 17:07, when you take into account that the furthest we have seen in the Universe is 13.5 billion years ago, that that happened 13.5 billion years ago at that distance, means that 13.5 billion LY, 13.5 billion years ago, there was a galaxy HD1 or gn-Z11 at that distance. So 13.5 billion LY away, 13.5 billion years ago, means 13.5 billion LY+ travel over 13.77 trillion years at the speed of that galaxy in comparison to ours..

[@themeliadonpepe6713]

i love her members only jacket, she rocks.

[@b.s.adventures9421]

I like your sharing that sponsor. Mental health is very important for well being. Great video as usual too.

[@stevenmitchell26]

By the way, I absolutely love physics girl! ❤️ Not only does she make it easy to understand the universe and physics but she is very easy to look at which makes me pay much closer attention to her than I would a long haired scraggly bearded guy with glasses! Thank you for making science fun and attractive again physics girl! ❤️❤️❤️🥰

[@hughbarton5743]

And thanks as well, Dr. Mack! Very lucid explanation...nice job!

[@steve5x565]

This channel should be automatically sent to every flerfers inbox. Such an amazing passion for knowledge and an awesome ability to absorb that knowledge and pass it on. 🥰

[@nutier]

Awesome video ! I enjoy it so much . Thank you for sharing . How many habitable planets in the universe ?

[@bronlokis]

oh wow, the slinky analogy is perfect!!

[@sargenmi]

What a great video, thanks and Merry Xmas 🎅🎄💝

[@uncleweirdbeard86]

I have bipolar disorder and have started developing anxiety these past few years. I think I might check out better help and see if Medicaid covers it because I often cant even motivate myself to go in. I have always loved science and as a kid, before I was even in school I wanted to learn everything there is to know. Sadly I developed memory issues due to some of the meds I have been on, but that hasnt drowned the flame that burns in me to learn. I love channels like this, and now that I know you yourself have mental heath issues it has inspired me a bit. I want to learn all I can so I can teach others before I forget what I have learned or who I am. I wish all of you the best in your journey to learn and live. And I hope to inspire you to keep pushing no matter how tough the obstacles in your way. My moto in life has always been that, if 110% isnt enough, give it 210%