If the Universe is expanding, then why do galaxies collide?

[@josephvanwyk2088]

This is why I like watching Dr. Becky's videos. HONESTY. A lot of astrophysicist/scientist would arrogantly claim what we know is 100% accurate - yet so many things aren't. All it takes is someone to say: "we don't know what this is, but..." - and people empathise with the process of discovery. Some people are so arrogant, they chase anyone away that dares to question their ideology.

[@alexdevisscher6784]

Like those Fermilab vids. So pedantic! Dr. Becky does a much better job.

[@DrBecky]

I think it’s *SO* important to say when we don’t understand something. I’m so glad you picked up on this 🤗

[@frankdimeglio8216]

@@DrBecky WHY AND HOW what are OBJECTS MAY FALL AT THE SAME RATE IN FULL CONFORMITY WITH WHAT IS E=MC2: CLEARLY, this is a gigantic breakthrough in physics AND mathematics. WHAT IS E=MC2 IS dimensionally consistent. TIME is NECESSARILY possible/potential AND actual ON/IN BALANCE, AS ELECTROMAGNETISM/energy is CLEARLY AND NECESSARILY proven to be gravity (ON/IN BALANCE) !!! GREAT. WHAT IS GRAVITY is, ON BALANCE, an INTERACTION that cannot be shielded or blocked !!!! MAGNIFICENT ! Consider what is THE EARTH/ground ON BALANCE !!! Consider what is THE EYE ON BALANCE !!! Now, consider what is the TRANSLUCENT AND BLUE sky. CLEAR water comes from what is THE EYE. (THE EARTH is ALSO BLUE.) Fantastic. The stars AND PLANETS are POINTS in the night sky. BALANCE AND completeness go hand in hand. It ALL CLEARLY makes perfect sense ON BALANCE. INDEED, LOOK at what is the orange (AND setting) Sun !!! GREAT !!! Consistent WITH WHAT IS E=MC2 (AND WHAT IS TIME), “mass"/ENERGY involves BALANCED inertia/INERTIAL RESISTANCE consistent WITH/as what is BALANCED electromagnetic/gravitational force/ENERGY; AS ELECTROMAGNETISM/energy is CLEARLY AND NECESSARILY proven to be gravity (ON/IN BALANCE) !!! (BALANCE AND completeness go hand in hand !!!) Great. Gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE (ON BALANCE), AS TIME is NECESSARILY possible/potential AND actual ON/IN BALANCE; AS ELECTROMAGNETISM/energy is CLEARLY (AND NECESSARILY) proven to be gravity (ON/IN BALANCE) !!! This IS consistent with WHAT IS E=MC2 AND F=ma !!! (ACCORDINGLY, ON BALANCE, the rotation of WHAT IS THE MOON matches the revolution.) Indeed, inertia/INERTIAL RESISTANCE IS proportional to (or BALANCED with/as) GRAVITATIONAL force/ENERGY; AS TIME is NECESSARILY possible/potential AND actual ON/IN BALANCE; AS ELECTROMAGNETISM/energy is CLEARLY (AND NECESSARILY) proven to be gravity (ON/IN BALANCE) !!! This IS consistent with WHAT IS E=MC2 AND F=ma !!! GREAT. ❤️❤️❤️ I have mathematically unified physics. FACT. THINK. By Frank Martin DiMeglio

[@AMRosa10]

If he were still alive, I am sure that Douglas Adams would be kicking himself for not including a Galactic Collision Insurance Salesman in Hitchhiker's Guide!

[@TrickOrRetreat]

It's filed under --12340987@$#+44666 section D3470

[@klumaverik]

Hah

[@THXeleven38]

All insurance sales where made illegal, punishable with death.

[@RodelIturalde]

A very nice job. The chance of collision between any single planet/star in a galaxy and another galaxy in a galaxy collision is pretty much 0.

[@5pecular]

@@RodelIturalde a 0.0001 chance means there will be a number of collisions if we are talking hundreds of billions of stars and planets

[@brandonshebester9574]

I asked this very question of you several months ago and you promptly answered me! I felt so honored! Now you do an actual video. I love it! I love you! Congratulations on your book et al

[@DavidBeaumont]

"Gnab Gib" was something I first heard from Hitch Hiker's Guide to the Galaxy (or maybe The Restaurant at the End of the Universe).. Douglas Adams would be proud😁

[@nicholashylton6857]

I'm pretty sure it was from, "The Restaurant at the End of the Universe."

[@realitycheck3363]

Is that why the Hubble Constant is around 42?

[@DavidBeaumont]

Hehe - this now has 42 likes :)

[@buxeessingh2571]

Don't forget Zaphod Beeblebrox's comment about Eccentrica Gallumbits.

[@thinboxdictator6720]

@@buxeessingh2571 "the best bang since the Big One" ?

[@slateramalgamated7620]

My favorite thing about these videos are the pictures of the physical observations of Hubble and the like. Such amazing artifacts

[@CarolinaSkyAstronomy]

Great video Dr. Becky. This ever expanding Universe is so amazing and weird and really HUGE. I don't think a lot of people really understand just how big the Universe is and we are standing on a very small rock going around a very small star in a very small solar system that is just a dot in our galaxy that is going to collide with our neighbor galaxy that is bigger than our galaxy and both of these galaxy's together are just a small dot in the Universe, it's crazy

[@michaelogden5958]

"Galactic Collision Insurance". Surely an actuarial conundrum. :-)

[@DavidBeaumont]

Or possibly an ecumenical matter?

[@michaelsommers2356]

For the low, low price of just 9.95 a month, you, too, can have the peace of mind that comes with knowing that you are insured against any losses caused by the destruction of the Earth due to galactic mergers or collisions.

[@TheMrAshley2010]

+++

[@TheMrAshley2010]

@@michaelsommers2356 - so, after paying $9.95/mo for 4 billion years ( the time frame she said), you will have 'invested' $477,600,000,000. That's a LOT of peace of mind!

[@michaelsommers2356]

@@TheMrAshley2010 If the Earth is destroyed by the collision/merger, where do I send the proceeds of your policy?

[@wildezaphod]

Who knew science and astronomy could be so understandable, interesting and fun, thank you Dr Becky, I love the out takes and you’re singing. Excellent blogs, well done you!

[@nivikb]

Sod worrying about the end of time, the universe and everything. I just love your little moments of madness at the end of each video.

[@zimmy1958]

Dr. Becky your videos are such a joy to watch. Thanks

[@andyc443]

Congratutions on the launch of your book🎉. I just finished it on audible, loved it. Can't wait to pick up the paper copy when I finish my trip at sea.

[@davidbrider]

...if the whole “being an astrophysicist” thing doesn’t work out, you’ve got a really good singing voice. 😊👍🏻 Great video, as always. Thanks for making these subjects really accessible.

[@jamesa6693]

David Brider I agree, but I think we’re all probably a little biased.

[@randyralls9658]

Astrophysics was a dead end. She is a youtuber.

[@ZiyanJunaideen]

I have watched quite a lot of your videos... for quite some time... But didn't subscribe... nor had any plans... until now... I think I liked the ending than the actual physics... Good job! Good luck!

[@perrydowd9285]

I propose, in honour of Star Trek, that any merged galaxies be deemed Galactic Federations.

[@peterprincic2830]

Hear, hear!

[@nameless5413]

i thought the crunch vs expansion was resolved some time ago. and had no idea balance is even considered an option. good yet again you have taught me something about the universe. good.

[@gerardbryant4840]

Brainy... Pretty... And she can sing, too... Another interesting, excellent, and enjoyable video.

[@timbeaton5045]

Guessing you gat a new camera fairly recently? Nice that the background looks a bit softer, and picture looks definitely better than a few weeks ago! Apart from that, excellent content. As ever. Just read your book, too!

[@robertforbes7666]

Expand Globally... Collide Locally!

[@TrickOrRetreat]

That actually makes sense 😋

[@Mugofbrown]

That could be a good slogan for the UK right now; look after your community but keep reaching out to other countries. Some politician will owe you royalties.

[@PCMcGee1]

I like the out-takes, always the best part.

[@lyness1217]

Your skin looks so clear and radiant in this video

[@sh4d0wm4ch1n3]

Great video! I have had to explain this to a friend or two, I am quite sure I was not as eloquent. :) I love your videos, I hope you enjoy making them as much as I enjoy watching them!

[@drescherjm]

Dr. Becky, Thank You!!! This is one concept I have tried to understand for several years.

[@young_werther2779]

Great video. Just a quick reminder that newest calculations of the mass of the Milky Way based on Hubble and Gaia telescopes suggest that the mass of the Milky Way is indeed bigger than that of the Andromeda Galaxy. So the Milky Way may very well be the most massive object in the local group.

[@mcenglish4654]

Yes I had read something similar- a University of Western Australia led study in 2018 suggested Andromeda had a lot less dark matter than expected and the two were probably about equal in mass although Andromeda has more visible stars

[@JaySityLL]

you are extremely intellegent i have watched you;re 12 videos a hundred million times, like you are really a good teacher.... i need to want to repay you for work'

[@trespire]

2:35 How refreshing to hear "we don't know" . This is how we make progress, by not knowing. This is how great minds think going back millenia to the ancient Greeks and beyond. You just got a new subscriber.

[@AAA-cw3dy]

Very interesting, thanks for the video

[@sankerpg]

Brilliant explanation. Thanks Dr.Becky

[@LisaBowers]

Subscribing to this channel was one of the _best_ things I've ever done. Your videos are always so fascinating. Thank you, Dr Becky!! 🌟

[@brucemibus9523]

Well explained, thanks Dr Becky. Cheers from Oz

[@bedewalker744]

“Galactic merger insurance” I live for these quotes 😂😂

[@Drummerx04]

5:50 unfortunately, these are not familiar sights for most people in western countries. The light pollution is such that I have never seen a true night sky in my entire life, and apparently during some blackouts in the past in large cities, emergency calls were made by city people concerned by the many bright lights in the sky... they had presumably never seen more than a few stars on any given night.

[@Moistronomy]

Fascinating stuff adorably presented as usual. Thanks Dr. Rebecca

[@ClodiusP]

"Oh my Universe..!"

[@GamesBond.007]

@Dr. Becky How in the name of the universe did you get a phd at oxford ? You cant just say Andromeda attracts the Milky Way because it has 4 billion stars, and ours only has 1 billion so that means Andromeda has 4 times more mass and 4 times more attraction bla bla...you cant just add up all these stars and pretend that they act like one gianormous star with the mass of 4 billion stars. Its like having a herd of 400 sheep and thinking you have one sheep that weights 100 tons. And then you begin to think, how am I gonna cut this big ass sheep, when I'm such a little gal ? With a 4 ton scissor ? And then you wonder why things dont add up in your universe. Because the way that you are adding them is WRONG.

[@gordongipson2538]

Thank you, Been wondering about this longer than a day 👍

[@davidsharlot6794]

I might get that rate expansion is higher the further things are away one day. It combines with looking into the past because light is fairly slow and gives me a headache. Clarity must be marvelous.

[@johnf3326]

Nice to watch, nice to listen, easy to understand 👍

[@sulevturnpuu5491]

Wasnt Milky Way recently re-evaluated to be about the size of Andromeda, if not bigger?

[@buxeessingh2571]

_Astronomy_, 14 February 2018.

[@irrelevant_noob]

@@buxeessingh2571 and @Sulev that's about the mass, not the "size" from the "number of stars" perspective, though. :-B

[@terryendicott2939]

I had to expand my understanding to comprehend the gravity of the situation. Is this a contradiction?

[@Chad_Dabal]

Hehe

[@YouTubalcaine]

No, this is Patrick.

[@hotrodsonulondon7111]

Thanks Dr Becky, love you and your video 😍. This is so interesting, you made my day. Take care 💖.

[@jonpaul857]

I very much enjoy listening to you describe the universe. Kudos to you!

[@kidmohair8151]

the dark energy/matter theory reminds me of the idea that was current in the 19th century that space was filled with 'something' that they called interstellar medium or ether, occaisionally aether... what goes around etc

[@RedRocket4000]

Yes and No what they thought the ether would do and what it could be made up of was wrong. So initially it was proved that it was mostly vacuum as it acted like a vacuum and contained very little. But forget Dark things for a second. Quantum Ideas require Quantum fields everywhere and you see discussion of zero point energy so by this Space is full of Quantum fields. Space is also full of all sorts of energy passing though it plus the curvature of SpaceTime from Gravity. So Ether to describe all this stuff we now know is in what we thought of vacuum might be a good name in that the people arguing there had to be something out there turned out to be right over those who thought only vacuum was there. We have no evidence of Dark anything being anywhere directly so don't consider it present yet. We have evidence of Dark might be somewhere just not found it yet.

[@krrobinson1260]

Thank you Dr Becky! Once again you blew my mind away! (Sounds like a great song title from the 60's) Anyway, it would seem to me to be absolutely incredible if gravity and the expansion balances out! And in the end everyone in the universe just parks like in a drive-in movie! How cool is that? Love your vlogs, and take care. Your friend, Kim.

[@toolzshed]

Great video! yay for the outtakes too!

[@emilebrandes1569]

Bought your book and enjoyed it, simple and easy to follow, but at my local bookshop. I try to avoid amazon, a monopoly that devours local and much-loved shops. Thanks a lot. Emile

[@DrBecky]

Thanks Emile! Glad you enjoyed it 🤗

[@emilebrandes1569]

@Smee Self Amazon is a monopoly warehouse, not a local shop

[@MarceldeJong]

“Oh my universe” that’s gorgeous

[@checkmilu]

Why in the world that I click the like button before even watching the video? 😅 what a lovely scientist 😍

[@garymcloud8738]

QUESTION: We can see the Universe is expanding because of red shift. If the universe was still and we were moving through it, everything behind us would be red-shifted. That would enable us to intermingle with Andromeda, and other galaxies can also, After the big bang things could move around and change directions. BTW, Why is the model of the universe all traveling in one direction? Wouldn't it be totally and completely omni-directional?

[@m98de]

I love your outtakes!

[@paulsmith8289]

I often wondered whether red-shift of distant objects was due to something happening to the light during its journey rather than dark energy. I recently found out theres a name for it, it's called the Tired Light theory. It has been ruled out in preference to actual expansion but how about making a video on it Becky?

[@chrispriest9819]

There are at least three reasons why light is red-shifted. 1. Cosmological red-shift where the wavelength is stretched, gets redder, by the same amount as the expansion of the Universe since the light was emitted. 2. Gravitational red-shift where the light loses energy, gets redder, climbing out of a gravitational well, like from a neutron star or black hole or the Earth. 3. Velocity red-shift, a bit like the Doppler effect with sound. If you could examine the light from an accretion disk around a quasar, you may be able to see all three effects at the same time.

[@DarkJK]

I was under the impression that the the universe tends to go for the “expand forever” deal. Or so other cosmo people keep saying.

[@RedRocket4000]

Still see a decent amount of stuff on Big Bang Cycles so there must be less than total consensus.

[@irrelevant_noob]

@@RedRocket4000 but is "no consensus" really enough? People claim that there's no consensus on evolution, or the globe, or even the nature of reality... Still, the accelerating expansion of the Universe even won the Nobel in 2011, i don't think there's any more doubt that the Crunch/Bounce are incorrect. Granted, they're quite interesting to think about, even if they won't actually happen -- that's my guess as to why they're still around. :-)

[@Mugofbrown]

I woke up this morning, looked at the news (same sh#t, different day) then came here for a bit of sanity. Cheers Dr Becky.

[@rogersledz6793]

Thank you so much for uploading this video. It is helping me get through the pandemic!

[@teacherhomieg]

Excellent video! Great summary and explanations.

[@phxJohn2010]

Thank you. Ive long wondered about this.

[@mk1st]

"We're the ones moving towards Andromeda". Perhaps they'll build a wall.

[@RodelIturalde]

Ye, they might think of us Milkywayians as Trump think of Mexicans.

[@shaizeeshows1850]

@@RodelIturalde I don’t think politics is something that can be applied to galaxies that don’t think nor care about collisions, explosions, or anything else. And I’m sure the universe cares far less about Mexicans or Americans for that matter than Trump.

[@DustyWall]

As the estimation of the expansion of the universe narrows in on that perfectly balanced outcome, I'm increasingly convinced that there may be a fundamental property of the universe that dictates that it'd be so, and maybe that'll lead to a breakthrough in cosmology.

[@AusTxMale]

Many times I have heard it said that while we know dark energy and dark matter exist, we don't really know what they are. So my question about them is what do we know that it isn't? Surely scientists have eliminated some early theories about the composition of these forces. What has been hypothesized and subsequently disproved about the makeup of dark energy and/or dark matter so far?

[@g0balot]

Good work on LBC tonight. I didn't hear the intro but couldn't mistake your voice :)

[@DrBecky]

Thanks! Always scary talking to LBC in case they make me talk politics too 😂

[@mgwiredog]

Thank you for the clear explanation. I was contemplating this very question about a month ago. Greatly appreciated!

[@AnonymousSourcesConfidential]

Sitting on my porch right now and this question came to mind, so here I am also.

[@EmergentUniverse]

Hi Dr. Becky, Thank you for another great video! It would be interesting if you would consider an alternative where spacetime is implemented by a universe sized cloud of very low energy photons, neutrinos, and maybe gravitons. Then some of what is attributed to Doppler redshift may be due to a very low level drag from this spacetime superfluid. I'd like to see scientists consider more of these alternatives, given that there are so many major issues in physics, cosmology, and astronomy.

[@mrderp3816]

J Mark Morris this has been considered! If such a fluid existed, it would have mass due to the energy it takes from the photons. The repercussions of this are beyond the scope of a KZbin comment but I'm sure you can see where this is going with regards to dark matter :)

[@besotoxicomusic]

That last sentence before the hair. I love you.

[@jadney]

I'm familiar with the critical density question, and that has been one of the big questions for decades, but I thought that this had all been settled now that, in the last decade or so, it's been determined that the most distant galaxies are accelerating away from us. We live in a universe that's not only expanding, but it's also expanding at an accelerating rate. Doesn't that answer the question? Answer: At large enough distances the force of gravity due to the average density is not enough to overcome the expansion force. So the average density must be less than the critical density. I always thought that one of the most interesting things about this question was the fact that we could calculate the critical density, but no matter how good our measurements got, their error bars always straddled the critical density. Apparently the actual density is less than the critical density, but not by much.

[@arthurcamargo8416]

Very entertaining and informative! I have watched a few videos on your channel and you seem to be subscription worthy! (That means very little to you, I'm sure, or to your followers, but I am very picky when it comes to channels!) Yay!

[@damnsurfer522]

I actually read something about 2 months ago talking about our galaxy may actually be larger then Andromeda. Don't know if this is something that may or not be true but thought it was interesting.

[@galadrielle3680]

Dr. B....THE HEART NEBULA!!!!! I just saw a picture on it, and you HAVE to talk about it! It's SOOOO COOL!!! Pretty please? With sugar on top?

[@richardsylvanus2717]

Cool video Becky!

[@IAmAlgolei]

_AAAH!_ Had the tv on in the background while watching Dr. Becky on the laptop, and suddenly the same voice was coming from two different sources. Dr. Becky was on BBC News talking about UK "space force".

[@DrBecky]

Nice one! Is that the bbc click thing on virgin galactic?

[@jamesdoumakis3420]

Dark matter is gravity ,the star clusters also create the trampoline effect at a large scale as in the cluster as a whole as well as a localized effect depending on the ''weight'' or density of the localized star cluster or pair of stars . Multi-verse would explain the expansion of the universe based on the trampoline effect crossing between universes when you consider the shape of them where they touch or meet ,also creating a trampoline effect surrounding the entire universe pulling everything within a universe outward . The bigger the the universes get the more pronounced the trampoline effect becomes , thus accelerating the expansion . This halo of gravity between universes would have tremendous gravitational force if you can imagine a cluster of soap bubbles next to each other floating in the air. The point where they meet would form a crease wherever they touch creating a trampoline effect around the whole bubble or universe .The oval shape (egg shape, the strongest structural shape in nature) protects each universe from breaking through or crossing into its neighbor universe. Yet the seem between them creates gravity , or dark matter. They collide because of local gravity between two is stronger than the expansion pull at that spot in time and space.

[@NorthernChev]

I remember as a child, back in the early Seventies seeing publications of "the amount of matter in the Universe" and I can vividly remember thinking, although there IS a finite amount of matter in the known-visible universe, these calculations just couldn't be right. It seemed awfully small. And, as it turns out, that hunch had merit, as modern calculations through the years have been refined over and over.

[@heronvontremonia9975]

i think it´s the growth of quantum complexety in the space between galaxys were it's not (or less) inhibited by the "measurement by" (interaction with) the stuff in the galaxys, that makes the universe expand..

[@IvanIvan1974]

Today I asked a random person if he knows about dark energy. He indicates me the way to the food store where I can find energy drinks.

[@ricardoabh3242]

IvanIvan1974 mmm so what was the brand? Lol

[@furkanavc8680]

he was a nice person

[@sMASHsound]

Quite a helpful guy.

[@lyrimetacurl0]

Monster Dark Energy

[@Jablicek]

Your videos ae a lovely blend of thought-provoking and very sweet. :)

[@Dragrath1]

Hmm from what I've heard in recent years is that if counting Baryonic matter Andromeda is the more massive of the galaxies but by observing the pull of gravity on nearby galaxies the Milky Way seems to have more "invisible" "mass" in the form of what ever "dark matter" is than Andromeda does somewhat leveling the playing field .... Is that no longer thought to be the case?

[@mcnultyssobercompanion6372]

Excellent topic for a vid-explanation because, on the surface, this can all seem like a major discrepancy. It's initially counter-intuitive, like when people are confused about the dozens-and-dozens-of-billions-of-lightyears-size of the observable universe, given it's age of "only" just over 13 billion years. I continue to wish I was an astronomer, while simultaneously coming to terms with the fact I could never do the math. :) Luckily there are astronomy vids on KZbin. This was another lovely one that's left me a bit smarter than I was 10 minutes ago.

[@gaetanovindigni8824]

Exchanging images with astronomers in another galaxy would be an interesting day.

[@charlesbrightman4237]

"IF" the universe is expanding, 'then' it is more probable that the net effect of solar winds, particles and energy pushing outward from galaxies, continuously, over a prolonged period of time, and other galaxies doing the same, would tend to push galaxies away from each other. And from our singular perspective here on this Earth, galaxies further away from us would appear to be moving away from us faster and faster, and they would be too. BUT, NOT because 'space' is expanding, but just the net effect of all those interacting and additive forces acting upon those far away galaxies. And then also, as galaxies moved about, the net effect of interacting energies, while not only causing the cosmic web to form, could also allow galaxies to collide. Of which, how could galaxies ever collide 'if' 'space' itself were expanding? Plus, how would we even see 'em' from far away galaxies 'if' 'space' itself were expanding if 'space' expanded at a greater rate than a certain 'em' frequency? The 'em' would disappear. And what exactly is 'space' and how could it actually 'expand'? And then consider also, we exist in a spiral shaped galaxy. The galaxy shrank in size as it became spiral shaped. From our perspective here on this Earth, it would appear the rest of the universe would be expanding, but it wouldn't really be. It would just be a relative appearance as our galaxy shrunk in size.

[@peterlue9274]

If the universe was expanding galaxies would be moving away from each other ON AVERAGE. However, ON AVERAGE, they are not. This is a PROPAGANDA post.

[@lordgarion514]

Charles Brightman No, all that has been observed and tested. What's coming out of stars is a tiny tiny fraction of the energy needed to push galaxies. Where are you getting your information? I got a strange feeling it's not from any real scientists.

[@charlesbrightman4237]

@@lordgarion514 Even a very small force, but continuous, over a prolonged period of time, should be able to move galaxies if nothing stopped it from doing so. The interacting forces between galaxies would also most probably be how the cosmic web forms. a. How exactly do galaxies form and how exactly do galaxies become spiral shaped? The current narrative is that matter, via gravity, attracts other matter. Our spiral shaped galaxy would be collapsing in upon itself, thereby giving us a relative perspective of an expanding universe. b. Why is it ONLY 'space' expanding is the explanation? Why couldn't 'time' be slowing down giving us a relative perspective of space expanding? Or maybe both being true, space expanding and time slowing down, hence we perceive a universe expanding faster and faster. c. My information: From my own sources and critical thinking skills of which it appears many so called 'smart' scientists seem to be lacking.

[@astrobat81z45]

@Dr. Becky we know that gravity move at speed of light in vacuum,but does the gravity moves at different speed through different medium like athmosphere or planets?

[@DavidBeaumont]

Good question! My guess is that (unlike light) it doesn't slow down because its a ripple in the stuff the universe is made from, not a ripple of something in the universe.

[@xk1390]

From PBS Spacetime I understood that it was already established that there isn't enough mass and gravity to counter the expansion of space.

[@Petertronic]

I was hearing clips of your voice replayed during the night on 5 Live. Great to hear you on Sarah Brett's show 😊👍

[@DrBecky]

Cool! I didn’t realise they’d keep replaying the chat that’s amazing 🤗hopefully they played it this morning too! 👍 glad you caught it

[@Petertronic]

They played a snippet during some of the news bulletins, where you describe the teeny bit of light from the atmosphere that allowed water detection. Very cool stuff! 🌌

[@Spineburger]

It's nice to watch a video where someone isn't just saying "bruh" over and over.

[@besotoxicomusic]

The cooler galaxies chill in the supervoids.

[@edmonddyogi6411]

At 9:37 you talk about a dark night sky because of continuing expansion (assuming the universe does not have enough mass). But wouldn't we (if there are still humans at that point) still be able to see the stars in our local galaxy at night? We wouldn't be able to see other galaxies but local stars should still be visible in the night sky, right?

[@DrBecky]

Yeah the Milky Way would stay bound - perhaps I was a bit over dramatic at that point 😂

[@primoroy]

Maybe, just maybe expansion and gravity are disconnected at the galactic group scale? Kinda like a cloud of gas molecules in a vacuum expand with virtually no limit, but the individual molecules and their constituent atoms are tightly bound and will not separate in the same vacuum?

[@tonygibbs9272]

I've made this comment on a couple of your videos , in a nutshell , I propose the action of colliding galaxies could explain the positive acceleration discovered as being the multiple universes eventually colliding perhaps being the cause of the big bang of a new one ... Colliding universes being a larger version of colliding galaxies ...just say'n

[@vrendus522]

Dark matter and dark energy are relatively related to what we perceive as normal matter. If DM and DE are products of the big bang, then their position is relative to what we call as normal matter. This is all that you need to know. Like your top, looks kind of lacy. Take care xo

[@aitchpea6011]

One thing that has troubled me for a while is that whole question of HOW we know the Universe is expanding and that expansion is accelerating. The light from distant galaxies is redshifted more than that of closer galaxies. I would take that to mean that the more distant galaxies were travelling faster when the light left them than the closer ones were. Since more distant equals further back in time, I always thought that should mean that expansion is actually slowing down. Recently somebody told me that the redshift was due to the expansion of space, but how can one tell how much of the redshift is due to expansion and how much due to doppler shift? Obviously I don't think the astrophysicists and such are wrong, I would just like to know why they are right :-)

[@warrengibson7898]

Around 7:00 you say Andromeda exerts a bigger pull on the Milky Way. In fact, they exert equal and opposite forces on each other.

[@Gaetano.94]

My grandson loves you. He loved when you were in Spiderman 1 and 2.

[@garrettromero4497]

I am vastly uneducated but I will soon start school to become an Astrophysicist. Sometimes I like to imagine, as a sort of cool SiFi concept, that Dark Matter/Dark Energy and Gravity are 5th and 6th dimensions where you have length, width, depth, time, push, and pull. I'm certain that is not the case though. 😅

[@bearalohalani]

Dear Dr. Becky - A couple of questions for you: When galaxies collide (hmm - sounds like the title of an sf movie), do their supermassive black holes eventually merge/eat each other? (I'm thinking they do.) Do we have tools to measure (or at least estimate) the gravitational pull of various sizes black holes? When they merge, is 1bh + 1bh = 2bh or >2bh? It occurs to me that we probably haven't ever seen such a merger, so any answer would be highly speculative, but give it a go anyway! 🤔 I really enjoy your videos and have more questions for another time. 😉Thank you! Susan Baer

[@vicsusinetti3482]

So where do we think the actual geographical location of the big bang took place? You have stated that some galaxies are going away from us and others are heading our way so one would presume that it wasn't (big bang) anywhere near the Milky Way. Luv your vids.

[@Grimlock1979]

I am surprised by that last reveal. I have always heard the universe will expand forever. If the acceleration is speeding up, that would make sense. But now, it is possible that it will balance out? Interesting.

[@danbigtasty9164]

Oh my universe I'm sorry but I looked at your nails when I looked for a ring lol ;D Xxx And seriously I was wondering if you like music! Lol your forever singing! Xxx

[@stephengonzalez5578]

Sounds like Dark Matter is elastic and will pull the universe back on it's self like a rubberband returning back to shape. TY for the video two thumbs up!

[@Sakkura1]

AFAIK it's actually unknown whether Andromeda is bigger (as in, more massive) than the Milky Way. The error bars overlap. Unless there's some newer article I haven't read, of course.

[@Mosern1977]

The hard part is actually estimating the size of the Milky Way. It is harder to stand inside a forest and trying to figure out how big the forest is, than looking down on a forest from an airplane. In any case, the "collision" will be pretty uneventful.

[@gmork1090]

@@Mosern1977 We'll be lucky if five stars actually collide. The thing to worry about is all the wandering black holes that the new galaxy will have floating around.

[@defies4626]

There's newer articles out now. Andromeda has more stars, but vastly less dust than the Milky Way. We might actually be heavier than it by a small amount from what we understand.

[@5675492]

@@gmork1090 No worries. In 2 billion years the earth will be so hot the oceans will have long evaporated along with perhaps all life.

[@Ice_Karma]

Your singing voice sounds really good-maybe you should do a collab with A Capalla Science??

[@beachboardfan9544]

What are the leading theories of what DE is or even where it comes from?

[@jasonmushersee]

good vlog. hope in my lifetime cern nails down this speeding up question because it seems like a mysterious pull on matter

[@SoloBSD]

Yeah! I had that question too.

[@sosheeanand3537]

This question was bothering me for a long time and thanks for explaining. Further is there any other collision between two galaxies occurred in past ?

[@RydarkVoyager]

LUV your thumbnail, BTW. You're one starry eyed gal. Fun video.

[@jamesdevine620]

hey brady.... a star is born