What does the universe expand into? Do we expand with it?

[@SabineHossenfelder]

Several people have pointed out to me that there is a fake account posting here (and possibly elsewhere) under my name. This account has been reported (by me and several other people). But since this may happen again please be advised that the "real" me has a checkmark after the name.

[@CAThompson]

Danke.

[@w0tch]

You know you could tell us if a failed quantum experiment led to a duplicate Sabine trying to appropriate your life 😅

[@rosalieroku3818]

I knew you were having doppelganger problems.

[@layton3503]

I think the universe expands into itself

[@CAThompson]

@@w0tch Dupe Sabine is pretty ersatz. There is a short story called 'The Copy', where a boy duplicates himself then finds his clone taking over his life.

[@jppcasey]

As I get older, I can confirm without any doubt that I am expanding.

[@georgemrwilde2384]

@Sand Fred Into dress.

[@stant7122]

Did you determine that internally or by observing yourself in the embedding space ie. mirror ?

[@vhyles]

Lmao 🤣🤣

[@paulembleton1733]

I’ve been contracting recently after expanding to fast.

[@fjames208]

To where

[@janoldland8265]

I'm just a 77 year old, who barely graduated high school. I've always enjoyed thinking and speculating about this subject. It's just SO fascinating. Thank you for your helping to understand space/time. I may never understand it all, but trying to is wonderful for the brain.👏👏

[@fivish]

Nothing here is fact, its all maths and speculation.

[@NiToNi2002]

@@fivish Not so. The expansion of the universe is based on observation, not maths. As a matter of fact, we can’t even agree on what rate it expands at, which we could if it was pure maths.

[@ithinkthonkthunk5333]

@@NiToNi2002 observations of phenomenon do not prove anything without experimentation. John King is correct - nothing here is fact...it’s all just pseudoscience.

[@dks6983]

77yr old eh? You got space, but less time..... some years later you will have no time and thus you wont even occupy any space. is that how Space and time are connected? MIND=BLOWN

[@bibidibabidi7236]

@@ithinkthonkthunk5333, incorrect. You do not always have to perform an experiment to prove something. Science is not always bounded within the human scale, in terms of time, space, energy, and other parameters. You do not have to experiment with internal solar activities to prove that it is powered by nuclear fusion. Observations can serve as proof, not every time, but they still can. The observation on the angle at which shadows of objects under the sun are casted would prove the sun's location in the sky, without necessarily looking at the sun itself. Most information in this video are facts, left for those clearly indicated by Sabine as speculations or the likes. The only thing 'pseudo' here is your belief that you understand anything about science. Perhaps, you should go back to watching conspiracy videos, where you may feel more intellectually comfortable.

[@guest_informant]

"Cylinders are internally flat." I might have to think about that for a few years.

[@eljcd]

It's not so hard. Take a sheet of paper. It's flat. Now roll it. You have a cilinder now. In one direction it curves, following a circunference. But in the perpendicular direction, follows a straith line,is still flat.

[@hexeddecimals]

It has to do with a measure called gaussian curvature. It takes the curvature of perpendicular lines and multiplies them together. A straight non-curved line has curvature 0, a line curved up has curvature 1, and a line curved down has curvature -1. In one direction the cylinder is curved positively yes, but in the perpendicular direction it is completely straight. 1×0 is 0, so the cylinder is "flat"

[@peterwexler5737]

Drink enough cylinders of beer, and you will understand.

[@peterd616]

There are a lot of ways to think about curvature, the curvature mentioned in this video is the intrinsic (or Gaussian) curvature. In another sense of curvature, it is true that cylinders curve (in one direction). However, the statements in the video about the internal angles of triangles are really caring about the intrinsic curvature. What makes this curvature intrinsic? Intrinsic properties are properties that don't care about the embedding. If that sounds a little complicated, what it means in terms of the curvature is that you cant bend a "flat" thing like a piece of paper into a "curved" thing like a sphere. It's very easy to bend a piece of paper into a cylinder (we've all made little telescopes out of paper before!) but impossible to bend it into a sphere. This is also the reason you cannot flatten an orange peel (without crushing it) - the orange peel has positive curvature, but a flat thing has zero curvature. There is actually a third type of intrinsic curvature - negative curvature. The example normally given is "saddle shaped", but I prefer to think of it as shaped like a pringles crisp. In negatively curved space, triangles have less than 180 degrees! This space is sometimes called "hyperbolic" space. To go back to the piece of paper analogy, if you laid the piece of paper down in front of you, in order to make a cylinder, you bend two opposite sides towards each other. In order to make a sphere, you would have to somehow bend all four sides at the same time, and if you try this you'll find it is impossible. In order to make a pringles shape, you have to bend two opposite sides together like a cylinder, and the two remaining sides downwards at the same time. This is also not possible. The paper will not cooperate. Stupid paper.

[@sleepingwarrior4618]

@@eljcd it isn't flat you fool.

[@antoniobragancamartins3165]

I love watching Sabine for the following reasons: I'm Brazilian and Portuguese, I'm not a physicist, I love physics, my native language is Portuguese and my second language is English, but I can understand Sabine speaking in English very well!

[@keithtinkler4073]

I believe her natural language is German

[@Finnec123]

"The part about my job that bothers me most is the need to work on something that is popular or to work with people who are popular. I have always had, and still have, trouble funding my research because I tend to be interested in topics that few of my colleagues find relevant. I almost left academia because of this several times, and I still feel every other year that academia just isn’t for me. If I can only get funding to work on research I don’t consider promising, then what’s the point?" - Sabine 2020, physicsworld, "ask me anything" We recognize her.

[@Sarahizahhsum]

I second that. I recognize her too. Very glad she's moved to yt. Maybe she'll get funding somehow through sponsors or such. I wish her the best! And am curious to see her conclusions! It'd also be nice if she'd be funded traditionally, but I'm super proud of her for getting on yt and thinking outside the box. I can tell she's a good lady.

[@6023barath]

This aspect of academia makes me question if I should go into it at all.

[@TrilobitesRTasty]

Sounds sorta like why I chose to pursue industry, instead of a academics after the masters. Forty years ago, I figured whether in industry or academics, I would have to put up with a lot of politics and b_____. So may as well choose the path that pays more.

[@KibyNykraft]

@@TrilobitesRTasty Industry has always paid. Of course a tech-ish related profession will although being important for society, ironically render a potentially narrow mind in the bigger more cosmological questions. If we think about the most innovative developers in the history of specific innovations, they usually had a good talent and more or less ok +degree of realism in both classical engineering and theoretical understanding of nature. The modern day scholar tend to be hyper theoretical in very speculative ways often involving abstracted maths used to just hide the limits or superstitions of their thinking. It is from these people we get diversions like virtual particles or time-aether-blob space concepts.

[@KibyNykraft]

(unfortunately, flat-earthing, babbling about little green men "from other solar systems", and the postmodernistic exaggeration of the Copenhagen interpretation that we see as a disease in mainstream physics now are all usually well paid activities, either by private or/and public money)

[@LutchoCressoni]

The reason people ask you even though there are other videos is because you make it interesting! Even being a physicist myself, I love the way you explain things.

[@eugenelamour1086]

As a physicist you should be annoyed by all these clownish thesis?

[@pseudonymousbeing987]

@@eugenelamour1086 What do you refer to?

[@eugenelamour1086]

@@pseudonymousbeing987 Spooky action at a distance...what a joke. GRT and QM fundamentally disagree. One requires discontinuum and the other continuum. QM only works because you use a general Formula that needs a set of special factor for every occasion. And the space /time equation is a circular logic. E=mc2 violates math as it would need to be light velocity 1.41 times c. Because the derivative of velocity is V^2/2....Take a look at the Electron from Lesseirg Papers.Might be interesting.

[@RandomPerson-iw3mw]

@@eugenelamour1086 who are you

[@pseudonymousbeing987]

@@eugenelamour1086 Mainstream physicists believe all the currently accepted theories are the closest to the truth we have due to the theory's empirical grounding and accurate predictions. I am confused that you are surprised that a physicist agrees with modern physics. It doesn't matter that spooky action at a distance is spooky and weird. What matters is that we are very sure that it is real due to experimental evidence. Everyone really wants an explanation but they're not going to throw out data because it's counterintuitive. It doesn't matter that QM and GRT disagree in the way you think it does. It means that they're both missing something yes, but it's unlikely that they are outright wrong. They are simply accurate to an extent. Scientists know this. It is inevitable that incomplete explanations will contradict one another before they are refined (or even revolutionised). Special factors. Yeah so what? You are surprised that reality has certain parameters? Constants have been needed since before quantum physics. Space time equation? Equation *s* presumably? Circular logic? Haha is that one a little pun lol. I don't know what you're talking about with this bit but the jokes funny. That's the integral of velocity is it not? What's it got to do with anything? 1.41? What? Lesserieg papers? As of now I'm not inclined to look it up, you may yet convince me but sorry I can't really be bothered with big reading right now.

[@blinkingmanchannel]

Feynman would be proud of your efforts here. The physics is amazing, and I haven’t found a doorway into it until now. I’m probably not smart enough, given my teachers all seem to just turn their backs and start drawing equations. But you do a great job of showing what we’re trying to get at with the equations. The sphere inside a cube, plus the subsequent minute or so of explanation cleared a big chunk of confusion from my mind. (Well, I feel better anyway…) I have been trying to get to grips with curved spacetime… This at least helps me see what my question should have included but didn’t. Outstanding!❤

[@SabineHossenfelder]

Thank you from the entire team!

[@europaeuropa3673]

My knowledge just expanded although it didn't expand into anything.

[@kevindickson2178]

i think your knowledge expanded into my mind bc i'm pretty sure my mind shrunk.

[@guitarista666]

Are you saying your skull is empty? :>)

[@MarlonLuna]

Or, you could say... The knowledge DENSITY increased within the context of the volume of your mind 😉

[@Nola50]

😂

[@Nola50]

@@MarlonLuna 🤯

[@strawbarry7834]

I love these videos, but generally get lost about halfway through. It's like a switch in my head and my brain goes "Welp, I'm out." But what encourages me is that there are people like Einstein/Sabine who really *do* understand this stuff, which gives me hope for the human race. Just think, roughly 3 pounds of physical brain can approach understanding the reality of the universe. That is just...magnificent.

[@thomasashley-smith245]

Well… define “understand”? I don’t think even these greatest minds “understand” like we may think… they just look at the data and the evidence and in light of no alternative model, accept what it tells them…it’s just as hard to visualise or conceptualise as imagining infinity. Take for example that the universe is “not expanding into anything”… firstly I can’t “understand” that based on my empirical experience. But if I were to follow the math and after peer review found it sound, I would have no choice but to accept the evidence. Secondly when we think of the words “doesn’t expand into anything” we imagine “nothing”.. but it’s probably more like the concept of the question “what is south of the South Pole” - Since space time gives us the meaning of a thing, it is a nonsense to ask what does the universe expand into… Or summit like that….

[@GTSN38]

They don't understand anything, half or most of this is speculation. I don't understand either, but I'm not bs people into thinking I know something they don't.

[@deemika]

@@thomasashley-smith245 I agree with you 100%. Sabine is simply trying to explain something of which we still have limited knowledge of. As mankind learns more, it will change its explanation of this topic.

[@yupok318]

That's your brain sounding the bullsht alarm. When things don't seem to make sense it's because THEY DON'T!!! None of this nonsense is in any way scientific. It's all mystical, religious, gibberish. You are being baffled with bullshit.

[@dracs007]

@@thomasashley-smith245 using nonsensical analogies like what’s south of the South Pole is what these guys do to feed us nonsense. There is no data, no math that can definitely state that universe that is finite can expand without any sort of void outside its membrane( just a word I came up with the outer edges). Another one I love is how they say universe came from nothing, but if you ask them what this nothing is, they don’t know. I’m not a religious nut case who suggests God created us, but I will never accept this notion that emptiness is finite. If you really think about it with common sense, there are only two possibilities. 1) the universe is infinite. 2) our universe is not infinite but whatever gave rise to our universe is. To suggest there is only one universe and that one universe is also finite that expands into itself is not very different than suggesting God created the universe in 7 days.

[@carlbrenninkmeijer8925]

Thank you. The fact that so many view your videos explaining abstract "things" within one day, gives me confidence in the future.

[@edlaw99]

Sabine Hossenfelder opens doorways to understanding like no other instructor. Five Golden Stars for Dr. H!!

[@radiowallofsound]

Sabine I really admire the way you think and explain things out. We're very lucky to have someone like you spending time on making these contents, it is much appreciated!

[@thephuntastics2920]

At the same time she has no clue whatsoever.

[@radiowallofsound]

@@thephuntastics2920 that's a bold statement, I'd suggest you to be more specific, and I mean, very very specific.

[@d.jensen5153]

@@thephuntastics2920 Seems to me she understands - and can explain - General Relativity as well as anyone alive. Whether General Relativity is true and complete are separate matters. What do you have to offer? A she-wolf nursing some abandoned twins?

[@musicsubicandcebu1774]

"I could be bounded in a nutshell, and count myself a king of infinite space, were it not that I have bad dreams." (Hamlet II.ii)

[@agimasoschandir]

We are but finite guests hosted in the infinity of dreams (youTube comments)

[@1SpudderR]

Hmm? Somehow you can relieve the internal pressure.....in the Nut! Fart.....that will awaken you from a bad dream!

[@biancabonet]

Pinch yourself and rip the skin open and out will come the rationality.

[@dallasswoveland4466]

@@biancabonet It didn't work!!!

[@biancabonet]

@@dallasswoveland4466 I'm sad for you. Wake up and smell the roses!

[@ThatCrazyKid0007]

To simplify, a lot of it is convention. We could be expanding inside a higher dimensional construct, but since we by default cannot observe that construct we have no reason to think it's even there in the first place. So the convention is we don't expanding into anything, the distances between non-force bound objects just increases in a fixed universe construct we live in. I suppose that does sound a lot like shrinking, but that's not really what happens because force-bound matter reserves their dimensions so we aren't shrinking, but if you viewed our universe construct from a hypothetical outside (the mentioned embedded space) then yeah it would appear as if we were shrinking. However that would just be a perceived effect and not physical reality. It's because we are using the edges of a fixed universe as reference for measurement. It's similar to how we perceive the Moon with our eyes to determine its size. It appears smaller or bigger depending on what we use as a reference to see it and judge its size using our eyes, but the Moon never actually changes its dimensions. That's why GR is hard to wrap your head around at first because it throws absolute frames of reference out the window. The bit about do we expand with the universe is correct, at least in terms of General Relativity, since forces like gravity and the strong nuclear force hold us together and doesn't let particles drift apart from each other as the space underneath expands. General Relativity is not really intuitive so it's no wonder these conventions are confusing. One thing more important than conventions in a model though is the observations we have made. The most important one is the mentioned redshift of galaxies. It appears every galaxy outside our neighborhood is getting redshifted when we observe light coming from it and the dimmer it is (the farther away it is) the more redshifted it is. The only sound explanation for this phenomena that is consistent with our tested and proven models is the expansion of the universe, so that's why we believe this is what is physically happening. However there are other ideas such as that space doesn't expand at all and the universe is static, it's just that light "ages" with time and loses energy, so it makes sense things further away take longer to reach us and lose more energy on the way. The problem with this idea is that this process is not really explained by any model that we can test and since GR is so well tested in experiments, we tend to stick with the explanation within the GR model.

[@klaustrumputin-trudeau4142]

What if space itself is not a nothing but a something that is faster than light or any other force or particle?

[@pedrolmlkzk]

You complicated too much the explanation and so it became too hard for people to understand

[@fzigunov]

"To simplify, (...)" and then writes an essay longer than the original video script. Lol

[@gravoc857]

@@pedrolmlkzk I understood it just fine.

[@pedrolmlkzk]

@@gravoc857 good for you!

[@Jadranas]

Just because the curvature can be measured and defined entirely within space-time, does not mean that there is no embedding space. The 2-d ant could measure 3 right angles on the sphere and conclude that the sphere is curved, but still, there is embedding space in which that sphere is "dipped".

[@MeppyMan]

I was going to get an early night. But this is one of my favourite topics.

[@BOBANDVEG]

Comic books call the area outside of the expanding universe "manifestacia"

[@randomblueguy]

@@user-fe9fj4vw4y Why do you feel the need to scam others? Nobody is going to fall for that, it’s clear that this is not actually Sabine.

[@_John_P]

@@user-fe9fj4vw4y

[@jus_sanguinis]

Every time she says "curvature", I hear "Gorbachev". ))

[@MyStarPeopleExperiences]

@@BOBANDVEG You have a fake account posing as Dr Hossenfelder. Many have reported you.

[@daveangels]

7:01 damn and here I thought I found the reason I'm taking up a bigger volume with age

[@Scootphoria]

You're an anomaly ;)

[@thesoundsmith]

You're expanding into yourself...

[@1curiocat]

Yeah, I noticed that my clothes were shrinking relative to me. At first I thought it was my washing machine, but it turns out it was my fridge

[@sparkey4293]

Maybe Sabin can help with that shrinking trick used. I’m having a similar problem with my clothes with a slight variation my clothes are shrinking in the x and z axis the y axis is still holding steady.

[@MrScrofulous]

That would make a great cafe name ...."Einstein's Kitchen".....where universal expansion is not a choice. You can't blame me, blame Einstein.

[@Flashfox_Prime]

Now for a compliment - I discovered your channel after an episode of PBS' Space Time (which I have been following for years). Since then, I have also been following your podcasts and really enjoy how you explain complicated matters in understandable ways for us non-physicists. I look forward to every podcast :-)

[@ChimeraActual]

You have blossomed in the past year! Love you. Are there respected cosmologists who aren't satisfied by this explanation? That is, are there competing explanations? Competing questions? A non-cosmologist can't rule out that this may be the wrong solution fork or simply begs the question.

[@Ambienfinity]

I've been trying to get my head round this concept for years -- brilliant explanation, I finally get it.

[@somendrasharma4907]

Really? Explain it to me maybe? What I understood was that they too don't know... Leonard's mom here says that we can have that 10 dimensional embedded space right? We are just not able to understand it. Also there can be a higher dimension....so what is that dimension and is all this sentient? I mean, is there a grand design? Also, can there beings or conscious things (don't need to be biological) existing in these higher dimensions? So many questions still?

[@soapvar]

@@somendrasharma4907 get some nice DMT, they'll explain when you get there

[@damonedwards1544]

I've been wondering for a long time if the universe was expanding or if the scale things operated on was shrinking. Nice to see smarter people have also thought of this.

[@agimasoschandir]

Lorentz contraction

[@steveinkent9843]

You're correct.

[@rajshikhargupta6024]

Dr. Sabine Hossenfelder, I am just binge-watching your videos because they are soo good. I know that as a Ph.D. student I am not supposed to waste so much time on youtube but I really cannot help it... they are just soo good. Thanks for making these.

[@ryoung1111]

You need to correct the part about "R < 2pi R" [sic] at 3:30-both in the VO, and in the graphic.

[@DoctorHomunculous]

Do atoms and/or gravitationally-bound structures "feel" the expansion of space? ie. does the nuclear force fight against the expansion? And one more question: Does the time dimension also expand?

[@Flomes]

Yes to the first question. Since the expansion is accelerating, some think that one day galaxies won't be able to contain the stars, then solar systems won't be able to keep the planets orbiting and in the end molecules/atoms won't be possible.

[@beurksman]

Yes everything experiences the expansion of space but not time. Every other force is so much stronger that it is basically negligible except for gravity at very long distances.

[@DoctorHomunculous]

Thanks for the answers! Sabine's viewers are the best :)

[@juzoli]

@@Flomes It is more than “some think”. This concept is widely accepted by scientific community, and it depends on the rate of expansion.

[@juzoli]

@@user-fe9fj4vw4y Gtfo with your fake spam account.

[@ProofOfDragons]

Dr, Hossenfelder - you should host an “ask me anything “ episode to your patreon supporters :)

[@chrisgriffith1573]

Frankly, I am not in a position to be a "patron" and see no benefit to fans like myself at all. Favoritism based on money is often required, but also is bad for many individuals, being exclusionary in nature.

[@SabineHossenfelder]

I am considering it but at the moment I don't have the time. Need to finish my next book.

[@sundar6568]

@@chrisgriffith1573 +++

[@axl1002]

Try OnlyFans ;)

[@PetraKann]

@@SabineHossenfelder Dont be afraid

[@infidelcastro5129]

Strangely, since it began, the Universe has always had a volume of precisely 1 Universe.

[@adbuuk]

Love your no-nonsense approach to physic.

[@1492tomato]

So interesting!! My mathematical ability ends at basic algebra. This was one of the most understandable explanations of general relativity I've ever seen. Thank you!!

[@KibyNykraft]

Just search for "corrected Einstein's mathematics" or "corrected equations physics Mathis" etc, and you'll see that it's not quite that simple. The more advanced the mathematics, the smarter and more skeptical the mind is needed for keeping focus on what is useful and science mathematics ,and what isn't or only partially or contradictorily is.

[@azmard4865]

@@KibyNykraft your comment burns my desire to excel at maths for the sake of understanding nature 😮

[@frankdimeglio8216]

Hossenfelder is not a genius.

[@mikemondano3624]

Some birds do math more complicated than that, and honeybees solve a problem quickly that humans have not figured out how to solve yet.

[@KibyNykraft]

@@mikemondano3624 All natural species except humans have neither superstitions nor mathematics among the purely mind-based activities not having a direct relation to adaptation itself or to scientific plausability. That should give us a hint that nature is physical and not divine and mathematical

[@wdhewson]

I've been searching for three decades to understand general relativity. And must continue the search.

[@DrDeuteron]

what's the hold up?

[@ResurrectingJiriki]

You're not supposed to understand. Likely Sabine doesn't understand either It's a non sensical theory to 'distract' you from a real theory, real science and real understanding. If everyone knew how Stonehenge worked, the druids could not use their knowledge to 'influence' (manipulate) the people around them. Also, you might find out that the sun is not some hydrogen bomb going off in space but an electric phenomena which could lead you 'back' to catastrophism which would make you see the impending 'next end of the world'

[@BigManUndead]

@@ResurrectingJiriki What on this objectively spherical Earth are you talking about bud?

[@ResurrectingJiriki]

@@BigManUndead What was not clear? It seemed to me that what I said is pretty straightforward? Unlike Einsteins' theories

[@BigManUndead]

@@ResurrectingJiriki "the sun is not some hydrogen bomb going off in space but an electric phenomena which could lead you 'back' to catastrophism which would make you see the impending 'next end of the world'" This part was not clear

[@mr.johnson460]

A video explaining what happened before the beginning would be great!

[@drpeemac]

I am not astro physicist but this video has answered my inner random thoughts which i didnt know what to search for. Very good

[@TheMisterSvensson]

I would need a deeper explanation to how we can conclude we're not shrinking. I came up with the idea a couple of years ago, but held it to myself. Just recently I found out I'm not the only one thinking about it.

[@robwest5142]

That's exactly why I'm here. I've been unable to shake it for 20 years.

[@robertsavage8270]

look up Hubbles law, it proves the universe is expanding, but into what? think about it, the farther you look into the universe the farther back in time you are seeing. so, the universe must be expanding into the past.

[@robertsavage8270]

@@robwest5142 look up Hubbles law, it proves the universe is expanding, but into what? think about it, the farther you look into the universe the farther back in time you are seeing. so, the universe must be expanding into the past.

[@TheMisterSvensson]

@@robertsavage8270 I see no clear contradiction. I would imagine it looking just like that if we shrunk at a faster and faster rate. I guess I need a more concrete description to how the shrinking universe can't be the explanation. I know it sounds like I'm shifting the burden of proof, but I'm not pushing seriously for my view, I'm just curious; is there a clear refutation for the idea? Or maybe I just miss something the Hubble thing explanation.🤷‍♂️ I will look deeper in to it.

[@juan_ta]

As Sabine said, there is no problem with the idea of us shrinking. It is a matter of choosing an appropriate coordinate system.

[@williamburts5495]

In truth, we don't know because we are always inside the box and can't observe if anything is outside of it.

[@malcolmcrossley2618]

Thank you so much Sabine, your insights and explanations have been testing my understanding of the universe in the most amazing way. I watch each of your videos intently and stop, watch, rewind and proceed until I am satisfied that I have unpacked and understood what you have said. I feel like I have my own personal lecturer. Thank you so much for your time and efforts in bringing these most amazing and interesting topics to the world in a wonderful and fun way.

[@robertsavage8270]

The answer about what space is expanding into is so easy you have missed it. This much seems true. Everywhere you look into the sky, you are looking into the past! The farther you look, the farther in the past you see. Therefore, an expanding universe is actually expanding into the past.

[@GlobalChessBoard]

I really enjoy Sabine explaining in a very interesting way. One thing that is confusing me that scientists are using the language “ It just happens that way” or “ That is the way it is” which is very analogous to the religious philosophers that also says the same, at some point of the argument.

[@anatomicallymodernhuman5175]

To be honest, I am expanding. You just robbed me of my favorite explanation for it.

[@Aanthanur]

For an explanation by a gravitationally bound entity, this was relatively good.

[@markfabre7682]

I have thoroughly enjoyed your talks, not only on physics, but also philosophy. While in college in the early 1970's at LSU, I was fortunate to meet Dr. William Hamilton and Dr. David Blair to assist in a small way on what became known as Allegro, a forerunner of LIGO. Whenever I think about the universe expanding, I wonder, could it be expanding because it is rotating? (Centrifugal force?) If so, I can imagine children playing Snap the Whip... gravity holding on until overcome by centrifugal force and the universe flies apart. Is there a rotational component to the model of the entire universe?

[@3opaH]

In that case, wouldn't the universe expand in just one direction- perpendicular to the axis of rotation?

[@markfabre7682]

@@3opaH If rotated in 3-dimensional space that would be true, but in 4-dimensional spacetime?

[@charlesdavis7940]

Sabine work has really helped me on my journey to understand physics. Great production values, info I can trust, and delivered in a way that a noob like me can mostly understand. Nice work. Thank you.

[@Rising_Pho3nix_23]

"When you move forward in time, you move sidewards in space. That's just weird. And that's why we don't use that" lol

[@fjames208]

Lol true

[@lrimunlmorin7947]

But it's true though ,aren't we always moving?

[@Rising_Pho3nix_23]

@@lrimunlmorin7947 we are moving forward in time, yes. At least in our local understanding of time

[@JivanPal]

@@lrimunlmorin7947 yes, it's true depending on your frame of reference, but as mentioned, the particular frame of reference you choose to work in doesn't matter when it comes to what the theory predicts, so we just choose to use the frame of reference that's most convenient to work with.

[@PyroMancer2k]

I like the idea were are shrinking instead. It made me think of a video on how high energy particles traveling at the speed of light could travel deeper into the atmosphere than their life time should allow as they should decay in a curtain amount of time and when you look at the speed of light that only allows for a curtain distance but they were traveling much further. The solution was that when traveling at the speed of light from the particles perspective since time was moving slower the distance to the destination got shorter. This means in turn if you were traveling at light speed and slowed down it would seem like your destination was starting to get further away. Since time and space are relative this example of high energy particles would seem to indicate that to a curtain extent distance is relative too. I know there are some flaws with the perspective of the universe seems like it appears to be expanding because we are slowing down after the big bang but it is an interest change of perspective.

[@calguy3838]

I'd like to see her do one about Einstein's theory that time is money.

[@joansparky4439]

not any time, 'life time worked for others' is money.

[@travisdunlap4526]

One question I still have: Does this universe expansion generate a "force". So while its true that are particles are not expanding apart due to gravity (or other forces), are those forces being countered by the expansion somewhat, leading to a weaker overall attraction between the particles? Also, as the universe's expansion continues to increase in rate, is the "force" of the expansion increasing as well?

[@jonka1]

I'm not qualified to give a proper a proper answer to you but I suspect that nothing is affected by the moving apart of discrete and self contained systems. I like your last question about increasing rate. My mind has been inclined to suspect that the increasing rate of expansion MIGHT be explained by a high rate of spin of this entire universe. I have asked several youtubers for their opinions but so far have had zero response.

[@everythingisalllies2141]

the belief that the universe is expanding is pseudoscience. a BS claim. It's not expanding anywhere. The other nonsense claims are from Einstein and for the quackery called Quantum.

[@calguy3838]

Her explanation of "It doesn't expand into anything" sounds much more like, "The answer to that question is beyond our capacity to observe, and so is unknowable."

[@PrivateSi]

To be pedantic, the problem is Sabine kind of asserted the universe does not expand into anything. A multiverse may be far from definite reality, and impossible to confirm but that also means its impossible to deny. Also, the idea of matter shrinking was a bit of straw man on the 'shrinking universe' denial assertion front. It is possible everything is being pulled inwards, with objects nearer The Greatest Attractor, further away from us, moving away faster. Laterally matter would be pulled into filaments that form blobs that form galaxy clusters... The Big Suck!

[@alphagt62]

This is so, there are a great many things that are beyond a human’s ability to know. But this subject about our universe, is deeper than just saying it expands into nothing. Space is more than nothing, it is a field of tensors, magnetic fields, the Higgs field, gravitational fields, dark energy, etc. all of these fields are what make up space. This creates the 4 dimensions we enjoy. Outside of our universe, these fields do not exist, and therefore, there are no dimensions. And you simply cannot go where there are no dimensions. She did mention that if there are 10 dimensions, then perhaps our 4 dimensions are inside of that. But, there is zero evidence to support that theory. It happens to be one of those things that humans will never know.

[@calguy3838]

@@PrivateSi "To be pedantic, the problem is Sabine kind of asserted the universe does not expand into anything." Exactly. Unless I misunderstood (which is very possible), I think, based on her explanation, it's more intellectually honest to summarize by saying "We don't know and cannot know what, if anything, it expands into."

[@Neoplasie1900]

@@calguy3838 You might want to call it "Outside the realm of natural sciences" as that is what it is. For a scientifically minded person, these two statements are more or less equivalent. As I understood the argument it is more about delinking to fact of an expanding universe from the assumption that there necessarily is something to expand into. And so it is reasonable to assume - based on our current understanding - that the universe expands "into nothing" instead of "into something". Ultimately though, it's nothing we can answer using natural sciences and we probably never will.

[@calguy3838]

@@Neoplasie1900 I think people like me, who do not have a deep background in science, have difficulty conceptualizing space as a "thing."

[@57pickles]

I like to listen to Sabine whenever I think I’m getting too smart.

[@Yewbzee]

From time to time the KZbin algorithm thinks it's time for me to have another go at trying to grasp some of Einstein's concepts. I always oblige and press play hoping that maybe this is the one where the penny finally drops. Alas I was disappointed again. Great video though. I'm looking forward to somebody doing a video "Understanding spacetime for 4 year olds".

[@paulheartsongs]

You write well for a 4 year old he he

[@HCBailly]

Preface: I only have a very basic level of education in physics, so I have a couple questions. 1) What does it mean for the universe to expand? For example, filling a balloon with water will cause it to expand, increasing the volume and surface area. However, since we can't see the entire universe, I'd think we couldn't know that it was expanding, which leads me to my next question. 2) How do we know the universe is expanding? As you said, we can see that the space between galaxies is expanding, but I don't understand why that means the entire universe is expanding. Using the water balloon example, let's say that two pebbles of differing sizes are also inside of it. If we shake up the balloon, the pebbles will probably move around, possibly away from each other, but the balloon itself isn't expanding, since the surface area remains constant. I'd think there could be any number of reasons why two galaxies would be moving away from each other, besides the universe itself is expanding. Thanks. I enjoy your videos.

[@thelonious-dx9vi]

You mean the *circumference* of the circle will be less than 2pi R...yes? In other words, because the radius line inscribes a geodesic arc, that makes it longer...?

[@SabineHossenfelder]

Yes, sorry. The is an "R" too much in the illustration. I added a note on this in the info.

[@thelonious-dx9vi]

Thanks Sabine. I didn't mean to nitpick. Just trying to understand. Cheers.

[@jasongann8535]

@@SabineHossenfelder fake account

[@Bitchslapper316]

I wish my brain could expand so I can understand this.

[@brendawilliams8062]

Me too. Like from 101128 to 1011279. My journey for the maze takes more road trips than the ancient American Indians.

[@sonjak8265]

You are not missing anything. Pure rubbish created by people whose livelihood depends on making up things they do not know much about.

[@brendawilliams8062]

Seems that between 123... and. 375. And27. Is a fingerbalm. No

[@brendawilliams8062]

@@greggoog7559 I have a hobby. It is fun

[@larrybeckham6652]

It will. This disorientation you feel as you struggle to understand it is your brain forming new connection and even growing new neurons. Unfortunately this expansion does not accelerate at human time scales.

[@SMJSmoK]

You're the only KZbin host who knows how to pronounce Einstein's name correctly :-D

[@cobaltno51]

it was almost jarring to hear the corroect pronounciation :D

[@bangbangthatawefulsound3396]

her name suggests that she is from germany, or she knows because she works in frankfurt am main/germany ...

[@FlushGorgon]

Too bad she can't pronounce anything else correctly.

[@johngavin1175]

@@FlushGorgon Your hearing must be off.

[@keithmcgarrigle8921]

The Question is easy, in the beginning there was an absolute vacuum? (Infinite space) The temperature was absolute 0 kelvin? If you want to use the Hildenburg principle there would be more energy in the vacuum? The Bose Einstein condensate could form. (Particals coming in and out of existance), but the particals due to the low temperature could not disappear? Then Matter and Antimater in the form of Neutrons being neutral , and Anti neutrons also being neutral to be produced? This might explain why Protons and Electrons have equal and oposite charges? If one or more of Matter, or Antimatter Neutrons decays it could start out a chain reaction causing heat energy? The reason heat always goes to cold? Antiprotons would be trapped in Stars as energy? Matter then will be produced in greater abundance? That is why the Sun is spiting our Protons in the soar wind not Antiprotons? The vacuum of space is now not obsolete? The energy difference is matter? Just a thought to make us think?

[@Jack2200]

When I hear of an interpretation that "doesn't make physical sense", I immediately like it. It's so consistent with quantum physics that it must be true. ;)

[@sngscratcher5231]

Agreed. I think it doesn't make physical sense because the material universe isn't actually physical. It's something else that we're only just beginning to understand. "Everything we call real is made of things that cannot be regarded as real." ~ Niels Bohr.

[@ralphclark]

I'm afraid that doesn't work as a filter for deciding what's true. It's equivalent to saying that you just can't know anything.

[@okrasmugglers1635]

@@sngscratcher5231 That is the elemental duality of the corporeal and the physical, where "physical" is somewhat akin to the metaphorical world of poetical language, using the wholly unreal language of mathematical constructs.

[@Scientificus]

Fantastic video, Sabine. As a quick aside to (8:20-8:30), comoving coordinates that expand with the universe are used all the time in computational cosmology, as the basic framework of simulations of dark matter haloes and galaxies in a cosmological context. (I'm sure you know this.)

[@KF1]

is bare space quantifiable? Can we measure that kind of thing? Curious, if the universe is expanding, does this mean that there is new space coming into existence, or would the quanta of space be spreading apart?

[@stargazer7644]

Considering how redshift works, I tend to look at it as if new space is being created everywhere constantly.

[@mikebrough3434]

I can follow the physics and the maths and logically accept that the universe doesn't/can't expand INTO anything but when I try to construct a mental visual model, I just can't imagine it.

[@ThomasLecoq-bd7qj]

That is the problem that I perceive, that it is impossible to imagine nothing, no space, no time, no things, nothing. Vacuum implies containment, a boundary. But the void into which the universe grows is not a vacuum, and it can be infinite, which is a concept that no one can really visualize. It is a reality in nature, yet only an intellectual construct in humans.

[@adashofbitter]

"I figured maybe people just don't understand... so let me make it really simple... Imagine you're an ant, crawling on a sphere, measuring angles...." and... I'm lost.

[@agimasoschandir]

The ant only travels on the surface, which can go forward or backward on the surface, left or right, but not up and down. In effect, it is a flatlander or 2D creature, but with a 3D body. Restricting its exploration space to the surface of the sphere which, let's say the sphere was large enough that the curvature wasn't obvious to the ant, how would this (also intelligent) ant determine that indeed it was a sphere? By measuring the angles traced on that surface

[@homer_nods]

The ant is a bright ant and attended most of her spherical trigonometry lectures 😉

[@nicholasandrzejkiewicz]

Are you lost or are you just tuning out?

[@Chrisbajs]

7:42 I nearly spat out my coffee. HAHAAHA!

[@zombiebiker5581]

I love listening to you explain things,also I love the way you pronounce “Einstein “ awesome

[@edholohan]

EYE IN SCHTEIN

[@moonzestate]

What's so awesome with her pronunciation of Einstein? I see this comment a lot. The whole Europe pronounce it in the same way as she does. Are you from USA?

[@zombiebiker5581]

@@moonzestate Hello there, no I'm English, I just like the way she says it, it's my opinion and if you see this comment a lot obviously people like the way she says it, what is wrong with that? And the whole of Europe don't pronounce it this way, I work with up to 500 people from everywhere and a lot from Europe. And I do like the way she pronounces Einstein, but that's just me, just cheers me up. I love different accents and the way people talk. Hope that explains it and no offence given or taken.

[@zombiebiker5581]

@@moonzestate No problems, I find little things in life make me smile, and a little friendly debating is good. Have a happy ,stress free day.

[@moonzestate]

@@zombiebiker5581 My bad, I meant the majority of non-English speaking people in Europe pronounce it "ine - shtine". In my experience, only the American and British pronunciation of Einstein is "stine" instead of "SHtine". All Slavic languages pronounce it like Germans originally do. The same goes for French, Italian, Dutch, Greek, Hungarian, etc.

[@davidalevitt]

Hi Sabine! I'm excited to be a new Member here, and to discover more of your work and this excellent video. It fits perfectly with an article presented at an international physics conference this September, clarifying how spacetime curvature explains gravity. I'm hoping the "priority reply to comments" member perk (and the germane answer to a frequently-requested topic) mean you'll see this comment soon and we can have a conversation about it. The core idea is, modern mobile accelerometers provide an excellent way to measure, explain and prove Einstein's spacetime curvature causes gravity. It's kind of perfect -- as you point out, the theory lets you pick the reference coordinate system. We can use the coordinates of the accelerometer sensor, and of course any observer looking at the display of the sensor's Proper Acceleration on an iPhone will see the same value. The accelerometer confirms what Einstein suspected on his famous elevator ride: that objects in free fall near a mass are NOT accelerating, that the apparent pull of terrestrial gravity is a Fictitious Force, and that the surface of the earth accelerates outward at 1 g -- without its radius in meters increasing. For observers on earth's surface, this creates the illusion that nearby free falling objects all accelerate downward at the same rate. The main idea is captured in a simple poster from the conference: (Since I'm not sure how my big poster will render on KZbin comments, perhaps you can message me directly via @davidalevitt) I'm happy to share a short article that provides more detail. Here's a link to the conference abstract: indico.cern.ch/event/1229551/contributions/5526956/

[@theishiopian68]

I love the shrinking idea, even if its not a great theory. Its hilarious.

[@thomasschon]

If you construct a warp drive that folds the space in front of you, are both you and space traveling through embedding space while skipping time in timespace then?

[@srobertweiser]

I can remember my grandmother shrinking over time, but my gut keeps expanding. I don't know what the hell to think.

[@JP-vs1ys]

It is both impressive and daunting to listen to someone as smart as Sabine speak about the theories of someone who is *possibly* even smarter. Helpful, but still hard for an average mind to fully appreciate.

[@majorrgeek]

"the universe doesn't expand into anything" is not a good answer - scientifically speaking we still don't know - remember knowledge is not truth

[@burieddreamer]

One might argue that we can never know, bound to the universe as we and our tools are.

[@TeaParty1776]

Testing occurs in reality, not in mystical or subjective realms. Reality doesnt expand or contract. It just is. And thats difficult for mystics to accept.

[@EricManzane]

this video shows why time is relative, although it says that is barely 11 minutes long, it feels like a 2 hours magistral class. Awesome job

[@jacknemo8021]

Whether you're calling it expansion or stretching it must expand into somewhere or something. This is intuitive. Merely saying it is intrinsically unobservable so it must be nothing or not real is like your pet hiding its head behind a curtain and thinking you can't see it because it can't see you. The universe was birthed by an explosion, this has not yet stopped exploding; just because the blast wave is really far away doesn't mean it's over. So not being blocked by something an explosion is a sphere, and they expand until they run out of energy. So therefore the universe is a sphere, it is expanding into something, it will eventually stop (heat death). Whether it has expanded far enough for gravity to ever contract the interior mass is a matter of debate.

[@mattoita]

Can you provide a clear definition of "explosion"? Not even the standard Big Bang theory might agree with you depending on what you mean. The universe certainly didn't "explode" in the same sense as a firework does. Let me add, from a geometrical point of view, what the video says about the irrelevance of an embedding space is clear and sound. It is not saying an embedding space doesn't "exist" (whatever existence means); it is saying we don't need to postulate one, to talk about space-time curvature according to Einstein's theory. If you disagree with this, you merely didn't pay attention to the triangle internal angles test and the circumference length test. Other observations and theories, however, might include thoughts about an embedding space in order to explain further stuff! E.g. theories of quantum gravity like string theory do postulate an embedding space with several extra dimensions, because they NEED it for the theory to be consistent. General relativity doesn't need it.

[@jacknemo8021]

@@mattoita explode: to get really big, really fast. The universe is still exploding. You live inside an explosion.

[@mattoita]

@@jacknemo8021 And what is "big", then? The universe is the whole, how can I compare its size? I agree metaphorically it can be called an explosion. But when doing physics, refrain from misleading metaphors

[@jacknemo8021]

@@mattoita it isn't a metaphor. It is a literal explosion. It is still exploding. The expanding shell of the blast wave has moved far beyond us, but it's still expanding. You lack imagination my friend. That is why no one will remember your name.

[@mattoita]

@@jacknemo8021 Are you going to just keep rewriting the same thing ("it is an explosion"), or do you actually want to address what I wrote? Namely, the video under which you're commenting does not exclude the existence of an embedding space. It merely states it is not even necessary to postulate one to explain expansion. Do you understand that point of the video? Anyway, concerning your last statement, "the expanding shell of the blast wave has moved far beyond us". Mmh, strange. If the outer shell is far beyond us, that would mean there is something "left behind" the shell, that is the inside, which I would assume is the universe we observe "here". So you seem to believe that the universe is one giant ball with some outer boundaries, which are expanding outwards (towards what?), hence you absolutely NEED to think of an embedding space. BUT this is not what astrophysics means when it observes "expansion"; in fact your definition of expanding universe has nothing to do with lengths getting wider. You are just saying that the outer boundaries of the universe are expanding. How would this idea explain the overall redshift of the surrounding galaxies? (just to name one evidence of space-time expansion) You would need to also say that the "inside" of the universe is expanding, but then again why speak about a "shell" then, if everything is expanding? Very confusing, please elaborate.

[@georgestuart8656]

And, I continue, is there a limit where gravity is sufficiently strong to prevent expansion and where gravity fails to prevent expansion through weakness? A state not unanalogous to microgravity in Earth orbit. Truly fascinating stuff. I love your extremely dry delivery.

[@toughenupfluffy7294]

Neither does gravity ever counteract dark matter (expansion is accelerating), nor does it fail due to weakness (it's a matter of perspective).

[@LouisGedo]

7:43 🤣 Love this editing, Sabine!

[@juanfermin1841]

Thank you, know i'm more confused about that general relativity stuff.

[@bubba132]

There may be no observable "outside," but it can't be scientific to say there's nothing out there. If there's no evidence, we should remain uncommitted. Simplicity may rule out positing an undetectable void, but let's not fall prey to the aesthetic appeal of simplicity!

[@Raging.Geekazoid]

Exactly! Relativity is a scientific theory. It shouldn't be treated like a religion.

[@chucktx5957]

Academia’s favorite expression of total ignorance is “We’re not entirely sure.” Guess it sounds better to them than “I have no f*cking idea.”, but actually pretty equal.

[@display7715]

This is extremely counterintuitive but physics by definition isn't intuitive. It's not that there may be no "observable universe", the fact is that our universe can be described as a Reinman manifold. And a Reinman manifold has the property of not needing anything to expand into. That's just a fact.

[@bubba132]

@@display7715 If you're merely saying Reinman manifolds don't require anything more, then we aren't disagreeing. Reinman manifolds don't need anything to expand into, but we aren't arguing about what Reinman manifolds need. The question is about whether anything more exists. It sounds like you think not, but "can be described," is a weak sort of fact to hang your hat on. This amounts to a more technical version of the simplicity argument - we don't need it to explain what we know about physics, so it must not exist. Sabine's work explicitly condemns that sort of argument (although you are free to think reality must logically be simple all you want).

[@Raging.Geekazoid]

@@chucktx5957 Either of those answers would be better than Sabine's answer in this video and what physicists have been saying lately about other issues. There's way too much dogma and groupthink in modern physics.

[@Crunch104]

Embedding space! Thank you for your clear and concise explanations! Learn so much from this channel as someone that has no background studying this. Your teaching style enables people like me to grasp these complicated concepts. Even when you shrink and sound like a mouse. :)

[@johanswart5562]

Thanks Sabine. I really appreciate your insight and the clarity of your explanations. These are complex topics that you somehow manage to explain in a more understandable way. I love watching your material!!

[@anubispatron]

Insight, I'm still confused AF. So many terms like 10 dimensions, WTF is that, 4 dimensions is insane enough to warp my mind, don't throw 6 more. The more an more I learn about this, the less convinced I become we have any answers.

[@cifey]

@@anubispatron I feel like the universe itself must be much simpler than the math used to describe. How could something so complex come to exist with out any form of selection?

[@anubispatron]

@@cifey It honestly feels like they are making the craziest sounding garbage up to fill in the missing knowledge. Its ok to say I don't know, at least its honest, and sounds far more plausible then these 10 dimension sci-fi excuses.

[@fu6817]

@@anubispatron It's all bullshit to get funding for next year.

[@karl.weaver]

Yes, we do expand-my stomach is testament to this theory, thank you Sabine for years of going over my head! ❤

[@DanKoerner]

When Frau Farbissina tells me the Universe is expanding, I believe it!

[@don476]

I would like to know how the average person can appreciate what you teach and learn from it, without understanding what you actually say?

[@celebratedrazorworks]

Love your taste in subject matter! I swear that every time I follow a line of logic and search for explanations that will help my process I ultimately end up here listening to your data driven approach. In this case amidst my reasoning over the question of embedding space dilation(ty for the term) I of course had to posit the distinct difference of whether the space between is lengthening or are galactic systems receding from each other? I understand the time dimension complicates any attempt to make a real differentiation, in fact I'm fairly certain most systems make just as much sense in either dimension of time.. I think. Anyway, yeah I guess it doesn't matter although it disturbs me greatly that I cannot perceive everything inside our embedding space from an outside perspective. It's possible that we are all but a mirage of extreme circumstances born of space dust and pure light. Thank you for the insight.

[@robertahrens5906]

Yeah what he said

[@Gremriel]

I can never get enough of Einsjtein.

[@marcelob.5300]

You missed your classic "That's what we'll talk about today" :-D

[@SabineHossenfelder]

Back next week. With a new haircut!

[@MadDog-tp4rx]

@@SabineHossenfelder New haircut? You know, if your hairdresser screws up, he'll be a goner! ;)

[@homer_nods]

@@SabineHossenfelder enjoy 😊

[@plainflavour]

Clarity on the subject at last; now I understand! The term, 'the expanding universe' suggests a balloon being blown up, while the universe is not like this at all. What is happening, is that the distances between things have been increasing, which is significantly different from 'the universe expanding'. For decades, us laymen have been confused, not by a crazy universe, but by a confusing description of it.

[@tonysmith4109]

You have a wonderful ability to explain extremely complex ideas in an understandable way. Thanks, Sabine

[@thegreathadoken6808]

"Albert, today is all about you" Every day is always about good-old Crazy Haired Al.

[@Tamagumo]

What does that mean

[@Tom_Quixote]

Yes, that guy again.

[@nuneke0]

6:56 A sound statement would be: "We don't know and can't tell". Not that it is definitively NOT expanding into something!

[@mirador698]

It is scientific to choose the theory with the least assumptions and „expanding into something“ has „there is a ‚something‘“ as an assumption. Therefore it is scientifically sound to chose the theory which doesn’t need this assumption.

[@RubenMoor]

"the embedding space is unobservable by construction"

[@nuneke0]

@@mirador698 "Don't know / can't tell" implies no assumptions! It may leave room for assumptions but does not provide any. Instead it would be a honest concession of the limitations of our potential knowledge.

[@mirador698]

@@nuneke0 "may leave room for assumptions" is exactly the problem. There is no such room. Ockham's Razor cuts those possibilities off. Otherwise this logic would lead to "We know nothing" for almost everything (except math).

[@nuneke0]

​@@mirador698 Ockham's Razor is a problem-solving principle not a natural law. Even math can't prove everything. Known "unproveables" exist! The same applies here. Refusing to think "outside the box" per definition, when it comes to the universe as a whole, isn't helpful.

[@gtjacobs]

"The curvature of spacetime can be defined and measured entirely inside of spacetime". Thank you, Dr. Riemann!

[@holographicman]

You are awesome Sabine! 👍☀️

[@trebushett2079]

Well, Sabina, you've really done it this time - it is now as clear as mud. And judging by the comments, most people 'expand' into this category.

[@dt6653]

This stuff goes right over my head. Needs to be dumbed down more. The edge of the balloon looks like it's expanding into something.

[@PazLeBon]

maybe we are actually the bright ones haha

[@someguyfromafrica5158]

Hi Sabine. If the big bang started in a 4D coordinate system with all particles flung outwards at the speed of light then those particles would represent a bubble with a 3D surface flattened in the radial direction. Expansion, as observed, should be a natural consequence of this. The radial distance could be used as a universal clock. Also, if I'm not mistaken the circumference of such a bubble is very close to today's estimates of the size of the universe. One can also note that it may be the natural state of things for particles to travel at the speed of light in the 4D coordinate system. Increased spatial travel reduces time travel and vice versa. The angle between directions of movement in 4D would map to relative velocity in 3D.

[@ellayararwhyaych4711]

Yeah, you are mistaken. The universe has no boundary, since it doesn't expand into anything, thus no radial distance. Also, baryonic matter cannot travel at the speed of light.

[@Alexander31616]

Could you think of it as if we exist on the inside of a sphere, and as time passes the sphere expands? This way you don't have to consider the outside of the sphere, as you can only look inwards to a space that is always expanding.

[@RaZziaN1]

yeah but this way u still have another dimension - nothing changes

[@isaacbruner65]

@@dr.merchant the universe doesn't need anything to expand into if it's infinite. The universe would simply be everywhere, and when it expands it would still be everywhere, but now galaxies would be further apart.

[@juan_ta]

Do you mean inside as opposed to "on the surface"? Then @RaZziaN1 is right.

[@riverdung2000]

I do believe we will find eventually, that currents thoughts regarding the expansion of space are entirely wrong.

[@agimasoschandir]

Or, it might be it isn't even thoughts that are regarding such things

[@peppermintgal4302]

I wouldnt bet on that. Sure, we might find we are wrong, but all evidence indicates otherwise. After all, distances between us and distant galaxies are increasing rapidly, and those galaxies are departing from eachother very fast, as well. Space is not static, and it can't be kinetic motion, because it is, if you look far enough out, apparently superluminal, and therefore, space is the primary candidate for why this is occurring.

[@riverdung2000]

@@peppermintgal4302 where is the proof of superluminal? You are accepting the big bag model also apparently. That could be wrong too. There can be a model that works. I have that model. Lol

[@JCO2002]

Watching this on my verandah in Jamaica. Almost smacked my monitor when that giant ant went walking by.

[@CAThompson]

We've got huge ants in Sydney. I do not want to get closely acquainted with them.

[@locutusdborg126]

YOU MUST BE BRITISH, just like Ian Fleming Brits love Jamaica. Watch the show Death in Paradise. It is about a British detective on a fictional island similar to Saint Lucia. I think it is on Amazon.

[@JCO2002]

@@locutusdborg126 Canadian, actually, but been here for 11 years. We've had some rain the last few days, which moved the ants around, and I've been bitten repeatedly as a result. Had been dealing with them about 15 minutes before I saw that big one appear on my monitor. Seriously almost smacked it. I respectfully ask that Sabine not do that again.

[@locutusdborg126]

@@JCO2002 lol.

[@ebbanjenkins5960]

Watching this in Scotland..we dinnae have verandahs ken..jus stand at the doorway with my tab waiting fae the dreek ta pass oot fa twa minutes o sun than in afore the hailstanes knock me deid..the spiders in ma 🛀 kilt the beasties

[@hypnometal]

But in this case, doesn’t this posit a scenario in which neither the Big Chill nor the Big Crunch will occur? If galaxies now are held together with their own internal gravity, doesn’t that suggest that they can now persist indefinitely?

[@jafstraycat]

And here I always thought it expanded into space... just empty space. And, in doing so, it adds the time element thereby giving us an expanded universe of spacetime.

[@mikemondano3624]

Since both space and time did not exist before the Big Bang, it would be weird to think the universe expanded "into" something.

[@mutantryeff]

I expand with the universe and it requires larger pants sizes to be regularly purchased.

[@Gunni1972]

I am pretty sure in political terms, you don't "expand", you "develop".

[@Scroticus_Maximus]

Or could it be that your clothes are shrinking?

[@ItsVideos]

You must be buying your pants from a different universe.

[@Alan62651]

Sabine, what is your perspective on Halton Arp's challenge to traditional redshift interpretation? Do you think it affects the whole idea of expansion/contraction?

[@DinoAlberini]

It’s like asking a geographer about his perspective on the flat earth.

[@MICHAELsill-ve4id]

I can say for a fact that while watching Sabrine's vids my mind has expanded greatly. I'm now pulling a permit to build an annex on my head.

[@christ2906]

“what lies outside the universe?” Or, if the beginning of the universe was finite, then why can’t the universe , however large... be finite ? Or, how can the universe be infinite if the beginning was finite , 13.7 billion years ago ? Did the universe get infinite immediately? Or, is space always infinite, but “matter” was created and is expanding in the already infinite space ?

[@nazann]

I think no one knows the answers to those questions unfortunately. Also, thinking of 'outside the universe' only pushes the question back because where then is this outside space located?

[@NorbertHarrer]

Please somebody correct me if I am wrong. But I think nobody knows if the universe is infinite. All we know is the observable universe. And the beginning of the universe was just as finite or infinite as it is right know. Everything was already there. Just compressed to zero spacial length. Just imagine the 3-dimensional space as the surface of the balloon or sphere like in the video. At the beginning everything on the surface was at the same place. As the balloon expands, the distances between points on the surface get further and further away from each other. Even though, the balloon metaphor helps imagining things. It's also misleading. Because it suggests that there is an inside and outside of the balloon. But or 3-dimensional space is only 'like' the surface of the balloon. There is nothing outside of it.

[@pedrolmlkzk]

We dont know if in the beggining the univer was finite or infinite nor if it is infinite today The big bang theory only explains how the universe we can observe today came to be, there is no proof that the universe didn't exist before then We dont actually know, it is too big to be observed with photons

[@ankeunruh7364]

(1) we can't know. (2) the universe may be finite. But a photon is always faster than any observer / device can travel. (3) As Dr. Hossenfelder said, you can mathematically describe a space with 10 dimensions, that is independent of the four-dimensional spacetime. I cannot imagine this, but maybe you? (4) No.

[@waynedarronwalls6468]

The Universe, in itself, is finite, space however, is infinite. The Universe is the matter by which everything is composed, space is the fabric of the Universe. Think of it like this, when, in the far, far, far future, after a timescale which we cannot even begin to consider having any kind of grasp thereof, all the matter in the Universe has disappeared, all the stars have been extinguished, all the black holes have finally dissolved, every single speck of matter has vanished out of existence, there will be nothing but the void of space.

[@dscham1507]

Finding out you are on a sphere: "Flat-earthers hate this trick."

[@Ghostrider-ul7xn]

Flat earthers : atleast the universe is Flat.

[@natmol1595]

In your mind 🤘👁☚

[@leha1908]

Sorry but your wrong, We're on a "Oblate Spheroid". Which has a couple of "flatish" parts on it at the poles. The distance between the poles is shorter than the diameter at the equator, this is what confuses the "Flat-sters" (Flat-Earthers). Because there's a couple of places that look really flat. Where as a Sphere has an equal diameter in any direction.

[@leha1908]

@@Ghostrider-ul7xn But is it ? It could be such a massively huge Spheroid that the part of the universe we can see appears to be flat. Imagine a curve of one Nano meter per one trillion,trillion,trillion,trillion,trillion,trillion,trillion,trillion,trillion,trillion light years . Could we even measure such a curve?

[@Ghostrider-ul7xn]

@@leha1908 The exact shape is still a matter of debate but all the experimental data suggests its Flat with a 0.4% margin of error. The model that we use is Friedman -Robertson - walker model and the observational data best fits the properties explained through this model.

[@EK-gr9gd]

For the German speaking audience: There are two great playlist :"Einführung in Vektor und Tensorrechnung" Universität Wien Physik.

[@jimgolab536]

Have you looked at eigenchris channel?

[@CharlesDParker]

Introduction to vector and tensor calculus "Universität Wien Physik. ??

[@datapro007]

I enjoy listening to Sabine even though I am clueless.