If the Universe is expanding, where is the centre?
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- čas přidán 14. 10. 2020
- The Universe doesn't have a centre and the Big Bang wasn't an explosion. Go to brilliant.org/DrBecky and sign up for free. The first 200 people that go to that link will get 20% off the annual premium subscription.
If you have any other analogies that help to picture what's going on with the expansion of the Universe or what happened in the Big Bang, let me know in the comments below!
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👩🏽💻 I'm Dr Becky Smethurst, an astrophysicist at the University of Oxford. I love making videos about science with an unnatural level of enthusiasm. I like to focus on how we know things, not just what we know. And especially, the things we still don't know. If you've ever wondered about something in space and couldn't find an answer online - you can ask me! My day job is to do research into how supermassive black holes can affect the galaxies that they live in. In particular, I look at whether the energy output from the disk of material orbiting around a growing supermassive black hole can stop a galaxy from forming stars.
drbecky.uk.com
rebeccasmethurst.co.uk - Věda a technologie
Just to clarify something I said at the end. If you take into account the expansion of the universe, then the galaxies on the edge of the observable universe which emitted their light 14 billion years ago will now be 46 billion light years away. Both are correct statements. It’s a difference between the “look back time” and the “proper distance” both of which are considered distance measures in cosmology 👍
back to that balloon analogy, consider that the balloon universe has pressure on both the inside and outside of the balloon. In the three dimensional universe, that pressure is analogous to the effect of gravitation over large distances (between galactic clusters) occurring in the context of finite yet unbounded spacetime. Yes, the observable universe is currently expanding. And yes, that expansion is currently accelerating. I expect that if you check the change in the rate of that acceleration over time, that curve should conform tightly to a part of a sin wave with a periodicity that is quite large. Perhaps trillions of years. My point is that I expect that there was no big bang, but rather that the universe has just always existed in a fluctuating state. Alternating between periods of expansion and periods of contraction that could be described as a wave function of the universe. This model renders moot the concepts of dark matter and dark energy, which (let's just face it) were only place holder concepts anyway. Like the cosmological constant.
@@MrCharlesdick " My point is that I expect that there was no big bang, but rather that the universe has just always existed in a fluctuating state."
But the evidence of the big bang has been observed. Like she said , it may not have been big or a bang, but it happened . I have heard of theories of alternating periods of expansion and contraction, but even in those theories, the periods of contraction and expansion were punctuated by "big bangs."
From that balloon analogy, there is no 'centre' because the 'centre' is not on the surface, and the surface is all there is. But us 3D giants can see that there *is* a centre, and is in the 'hollow' middle of the balloon. It's the interior point more or less the same distance away from every part of the balloon surface. So, in a sense, the centre is where *all* the balloon once was, originally, before you started blowing it up. Every time you puff into the balloon, all the surface moves away from the centre. The centre of the balloon is very much its 'Big Bang' and each puff into the balloon is a passage of some time. All the *space* inside the balloon is that surface universe's past, and, I suppose, all the rest of the space in the room is that balloon's potential future.
Which makes 'Big Bang' an even worse description; a balloon universe goes bang at the end of its time!:D
@@dougbarrett2049 " But us 3D giants can see that there is a centre, and is in the 'hollow' middle of the balloon. "
No , we 3d giants can see that the surface has no center. The center you are referring to is not a part of the surface, and it is not the center of the surface. The surface truly has no center.
Remember the surface is what is analogous to the universe and not the interior of the balloon.
There is no point that you can point to on the surface where all of the surface was in the beginning. The expansion of the surface truly happened all over the surface at the same time
I’m not sure we thank you enough for all the content you have painstakingly put out. I really thank you. As a 61 yr old progressive disabled vet, I consume huge volumes of news daily. Both you and Antov Petrov and historical and geological channels give me an escape into subjects that have fascinated me since 5th grade, about 50 years ago. Before social media, if I was lucky I would find and read about science once or twice a month. Many TV channels started out as science or history but changed to reality TV stations. You and Anton and Physics Girl never fail to produce content that I appreciate when putting out a video. So, thank you very much for all your hard work. It keeps demon politics away for a few hours.
Milky Way has a soft, chewy nougat center. I learned this early in life.
Mars is filled with fudge 🤔
The Snickers galaxy has a confusing amount of peanuts!
@@Archgeek0 And it hasn’t even been discovered yet 🤭
@@JanRautiainen What? The Snickers galaxy's rather well-known. It's one of those little satellite galaxies the Milky Way's been tearing apart. It's what they named the candy bar after.
LOL
It indeed does have a center. I see it every time I look in the mirror.
Dude.. really...she's trying to explain something serious and you are joking 😂😂
I need this sorta mentality rn
You are the center of the universe actually funnily enough because all atoms spin around consciousness
Mine is a compendium of all consciousnesses.
@@sureshuttumadathil9678 Well, you kinda enable and encourage it by providing a comment. But Zachary kind of makes a valid point. Dr. Becky pointed with her finger that a center could be here, or there, or there. We are all the center of the universe.
Not only does my cat beg to differ, it also knows EXACTLY where the centre of the universe resides ...
In its stomach!
I can see how that’s true 😂
"The Universe doesn't have a centre." 8 minutes in "Well, actually we just don't know."
Cosmic background radiation begs to differ with her. North and South cosmic poles, including the earth's tilt, are reflected in CBR findings. They didn't believe it and sent a second satellite up to get more accurate info. It more accurately declared the same thing. What does this mean? The matrix has you.
I can confirm that my universe definitely has a centre.
I guess that’s just the mystery of space... there are many things that we can’t know at this point in time 🤷♀️
@@ashemgold We are far from the source and flow away with a river of galaxies around us , going in in straight line when light itself bends finds her on similar trajectory with the all knowing flatearthers ,cant contradict something impossible to understand .
Also 8 minutes in I am assured that I am the centre of the universe*. Which is very reassuring for my ego.
*for the observable universe
I prefer the loaf of raisin bread dough analogy myself. It expands as it rises, it's not a surface, the raisins don't stretch it rises, etc. More importantly, it tastes better than a balloon when finished.
Especially delicious bathed in Microwave background radiation. Yummy.
...then the cosmic whistler background, with the universe finally dying from the cosmic brown note
Doesn't the bread analogy imply that the universe " began" then everywhere at once ?? And when will science get beyond the material and think of what caused "the beginning"??
I was hoping to be the first to propose this alternative (too late!), and to mention we call it Spotted Dick here in the UK. Stop sniggering!
apple squat!
I always though there was a restaurant at the end of the universe
The other customers don't really say all that much, though.
We're nowhere near the end.
Yes, Milliway's. The prices are astronomically high but it doesn't matter because all you need to do to pay for the meal is deposit one penny in the inter-galactic bank at the beginning of time and the action of compound interest will more than pay for the extraordinarily expensive meal. I read it in a book somewhere....
@@ismailkraimi5796 At Milliway's you are often seated next to a party of young conservatives from Sirius B who sound an awful lot like a pack of dogs... Hmmmm I never could get the hang of Thursdays....
@Peter Mortensen c'est la vie
Hi Dr. Becky, I just discovered your channel yesterday and it is everything i was subconsiously looking for. I just ordered your book online and i hope to read it soon! thank you and keep up the enthousiasm!
Yep. I love her enthusiasm and depth of knowledge. Great CZcamsr
After watching videos like this, I need to lay down and let my brain cool off...😊
And accept that I still don't understand any of it.
"No matter where you go, there you are."
And that's the problem. You are a different manifestation of me that I cannot fully comprehend. "We are one consciousness experiencing itself subjectively" --- Bill Hicks.
'
"He'll be here all week, folks!"
TimberGeek has it in one... wherever you go, you will always be at the centre of the Unverse - the centre moves with you.
Is this reality or an illusion (I hear you ask)?
It is reality..... the reality of your perspective. There is no such thing as universal reality in this respect, just as there is no universal "present" when it comes to time.
To understand how this is so, you need a good understanding of General Relativity. CZcams can help lots there.
Hey... thats my email footer. Its a great one to ponder.
"You can run from yourself, but you won't get far."
I was scratching an itch above my ear right as you said “right there, above your ear.” Freaked me out a bit!
Fantastic video as usual. So glad I found this channel.
😂
Awesome explanation!! It’s funny that the physics of universal expansion has the unintended consequence of producing innumerable civilizations who self-centeredly think they are the center of the universe. Lol.
@@DrBecky The profile pic is an eye for a reason? :P
@@DrBecky you are standing on the outside in a multiple dimensional space,,, bubbles of energy think of the creation of the universe as a collision, imagine two bubbles that collide together the initial collision looks like a point from the inside, this creates matter/energy and two universes the initial over lap of the bubbles is cosmic inflation the continued overlap is the expansion of the universe we define this expansion as the speed of light. photons do not go anywhere they ride this expansion,(like a surfer on the ocean wave) from a photons point of view it has never moved. Gravity is the interference pattern created as inflation expansion energy travels through dense expansion energy (matter) this creates the force we call gravity constant acceleration. Dark energy, increased rate of expansion is the continued over lap of the two spheres imagine in your mind as the spheres over lap the volume constantly increases.. Dark matter,does not exist this is plasma and another universe that is created in the initial collision yes two universes out of phase with each other we see its effect on our universe.
The Question is not what is the speed of light but why does light go anywhere in the first place. The double slit experiment is not about the particle but the underlying energy field and dual space it exits in and rides on.
@@DrBecky It is all information following a defined set of rules ,,Is it real ,,you are in the same system under the same rules so from this point of view it is real
think of the universe as digital ,think of when the information is first loaded from the hard-drive into RAM,,now imagine yourself standing in the ram seeing the first bit of information loading into the memory chips this looks like a point ,it has to start somewhere,big bang creation from a point,as the data continues to load it must load into other chips, universe expansion,the data does not know what ,where or how it is expanding ,think of the universe as a near infinitely compressed self-extracting file, that is decompressing,think of the process of the universe as a file unzipping ,this is why the universe becomes more complex as what we perceive
as time passes and explains entropy ,,which says the universe was the most complex at the beginning ,,(Like a MIDI file in music just the instructions) stars are a process to unzip the hydrogen file into elements ,now think of video games,all the stuff that happens in video games,,if you have too many people in the same location in an online video game and the sever cannot keep up the game slows down ,,,time slows down ,,now think of a black hole in the universe ,to something falling in time slows down ,,you cannot see a black hole because there is too much information in one spot and the universe cannot render it, my son would play a game where he could look around leaving his player body in the game recon and then come back to his body in the game ,,this seems to me to be an out of body experience in the real world ,,,the universe system can not determine if you are alive or dead so you are in universe game in limbo with no set location ,,, think of the problems computers have hardware and software ,,ram errors etc,,, memory that does not wipe clean ,,,that is not a ghost it is ram chip that still has data from a previous data write that did not erase properly ,,,,the universe may not be running on a advanced computer ,,,but at its base it must be digital and even with near perfect data correction coding there will still be some errors You and your dog are both watching TV ,,,for most people the dog and you have the same understanding of what makes the picture ,,,,absolutely no understanding ,,just that you can see the picture ,,,the universe can be the same way we may never know what goes on behind the image..
Excellent video, thank you. Taking a massive subject like that and making it understandable to those without a college education like myself is a talent in itself. Also nice Monty Python reference!
Thank you for your input. I'm no astrophysicist, but have always been a science minded person. I really enjoy your videos.
The diagram of the universe saying "NB: Not to scale" had me laughing!
You know it has to be said.....
Yeah, I kind of assumed that label isn’t needed 😂
Why will you "professionals" never admit that the universe has a center and it's chewy.
If it’s chewy in the centre, dies that mean it’s crunchy on the outside?
Her point is that we're the chewy centre, and it's expanding. ;)
I _knew_ Andromeda was made of nougat!
@@00Skyfox Nougat is silly and unscientific. Clearly it's caramel. Do your research!
If the galaxy is spiraling into the black hole, of which is the CENTER of it, how could it be expanding? Science like religion wants everybody to believe. When you believe, you are ignorant and can be lied to. Here is another lie. How many days in a year are there really? There are exactly 364 days in a year exactly every year. Why did they make us believe this lie? Find out why. "The Gnostic Truth, Awareness 13". czcams.com/video/NhY_7vSuq0A/video.html&ab_channel=AWikkedMoon
what a superb explainer you are. Thank you so much for providing these videos!!!
Brilliant! The best explanation I saw so far. Merci 🙏
The Centre of the Universe is where my cat sits. I know this because he told me this, quite forcefully, the other day.
All Hail the Masters!
Wouldn't you be the pet?
Obey the Cats!
I miss my 'center of the universe'.
;~(
My cat thinks I'm the center of the universe. She follows me everywhere.
@@stevelenores5637 That's a common error - she's waiting for the right moment to strike ... 8)
"The universe doesn't have a centre" and "We don't know where the centre is" is NOT the same statement
Confucius says: "Everywhere is the center and the center is no where." the more science I learn, the more it sounds like religion.
@@ironwillie7666 Unlike religion, we got Most Of The Evidence plus Peer Review on our team.
People of note like Georges Lemaitre were on the Venn diagram of religion and science, his insights colour our scientific understanding today. Point is, he was a Catholic with a decent science mind too. A clever man.
@@davidripley2916 Bahahaha, that is super ego centric to think you have "most of the evidence" and it was approved by like minded people. First no-one knows the total amount of evidence that there is. Right? So to assume you know most, is stretchy at best. Again you proved my point, science is no different than the catholic church with ALL the evidence in the bible and approved by their peers... Just saying.
@@ironwillie7666 I don't have anything ,my dude. Was referring to the global scientific consensus as it goes. Why do you think I said most of the evidence?
It's like achieving absolute zero, it ain't gonna happen.
There will always be some thing we missed. And when did religion save millions of lives( Pasteur, Jenner, Salk etc al)
Just saying! :)
@@davidripley2916 I believe you said "Most of the evidence" to exaggerate the strength of your position. To put science on a false pedestal above religion. Just like religion does to science. Why else would someone make outrageous statements?
This is the best explanation I've heard so far!
You made a difficult topic much more clear! I love those “haha moments”.
Haha moment...
...how funny!!!
😯 😄
The term is one of those aha moments....
@@Skepticfornow
Ahhh... ahah... hahahaha haha!!
@@Skepticfornow It was an auto correct that was too funny to replace. I believe I typed “ahha ” considering my tremors and the plethora of extraneous key strokes.
Difficult “for the brain to get its head around.” Priceless. Love your explanations.
Could also be because they can’t get their brain around it and don’t really have an actual answer
Well explained. Thank you!
Thank you for telling us about the balloon analogy. You did a great job! 😉🙏
"This is difficult for the brain to wrap its head around" :)
Love it.
Big is matter of comparison its relative so how much bigger can you get then the entire universe
Minneapolis. The center of the known Universe is Minneapolis. I heard it once on the Mary Tyler Moore show, and I've remembered it all these years later, because it's the kind of thing that it's great to have a definitive answer to.
Just like, what's the hottest temperature? it's 1 Gruhn. We decided in college that the temperature scale should have an upper bound, too, so on a scale from 0 to 1, where 1 is the Big Bang, the Gruhn scale almost always is near zero on Earth.
@@robertcowling4313 There's an Apple store in Minneapolis, confirming Rice's statement and yours.
The center of the universe is my ex-wife. Just ask her.
@@jamestodd4877 Now this I believe !!
I loved this video thanksbi learn a lot from it
You're content is awesome and you have a great singing voice! Thank you :)
of course it is difficult to "wrap your head around that fact" - since wrapping around something indicates there is a centre.
I love your enthusiasm, the sher joy of what your talking about is intoxicating, reminds me so much of brain cox there is so much passion behind it.
Thank you for precisely pointing out the limitations of the standard analogies.
So well explained. Thanks.
Wow, never thought about the universe like that, thanks, great vid.x
One of the problems with describing the universe is using the word "smaller", which often shows up in descriptions of the universe at the "big bang". But telling someone something was "smaller" is one reason why the images people have of this event (or more technically, these events) trend toward the typical chemical explosive bombs used to picture "the big bang".
A better way to describe the (relative to us) early universe is that the universe was _more dense_ , so incredibly dense that even objects like protons could not exist. What we know today as normal matter could not exist because the energy density was too high.
It is this key concept that has to be stressed: the universe was _different_ before the state in which we find it today. What we observe today could not exist until the universe underwent a change of state.
The challenges of pedagogy surrounding much of modern physics ought not be discounted. Popular presentations of concepts in fields of study like cosmology will lead to misconceptions if time is not taken to work though the many ways in which people can and will misunderstand what is being explained.
Before Big Bang Universe had size of 1 Universe. Now it is much bigger with size 1 Universe.
It was always infinite in size, it was just a smaller infinity... 😉😄
Like the way the Set of all Odd Numbers is smaller than the Set of all Integers, which is smaller than the Set of all Rational numbers, even though all three are still infinite sets... 😁
Yeah, "hotter and denser" may be a better way to say it to people.
I don‘t see how this could help: obviously a bomb is more dense before exploding than afterwards (the same stuff in a different volume) so this also breaks down to „smaller“ and „bigger“ 🤷🏼♂️.
@@mirador698 yes and no -- as I said, the currently favoured theory is that, after the end of the Inflation Epoch (defined as being between T+10⁻³⁵s and T+10⁻³⁴s where T=0 is defined as the "beginning" of time in the Universe's current incarnation), the Universe has always been functionally infinite in size, but for smaller versions of infinity in the past, and larger versions in the future. There's no point in trying to apply common sense to it, it's not something that's readily amenable to our common senses / understanding.
The most comprehensive explanation of big bang and the expanding universe. I think it's also because you explained it together.
Dr. Becky did a great job keeping it simple
Thanks for the singing at the end, I'm having that song at my funeral.
I've thought about this lots but struggled to wrap my head around it. This helped me a bunch.
You can never wrap your head around anything, that does not have a center. It's simply not possible. I mean, where would you even start?
@@realitycheck3363 with your imagination, in EXACTLY the same way many scientist's do when they run a thought experiment in their minds eye....but you are not completely wrong, it can be difficult for people to grasp some of these ideas, you see, humans live a in a 4 dimensional world, and many of us seem to have enough trouble even with that !
@@psycronizer Imagination? This is more like a wild fantasy. Whatever happened to Occam's Razor?!? Sure, of course every point of the universe was once all at the center. But that does not translate to, suddenly every point in the universe is still the center? That's just...silly!! At which size of expansion, did every point suddenly reverted back to being the very center itself?
When the universe was still expanding in the beginning, and it was the size of our solar system, was every point in it still the center of the universe? Really? Because I would argue, at that point, it only had one center. Somewhere around the sun, if I had to guess. True, or not?
Let's say now, uhmmm, when it got to be the size of our galaxy. I would wager that the one and only center of the universe at that point in time, would have had to be in the vicinity of Sagittarius A. Would your guess, at this point be, every single point, everywhere?!? Because that would sound pretty silly, right?
So at which size would you say, that suddenly our universe lost the obvious center it had, all the time up that point, and suddenly every single point suddenly became the center? And exactly what weird spooky action happened at that exact moment, to cause the obvious center, all the way up to that point, to suddenly jump from the center itself, to every single point in the universe itself?!?
I mean, I might not be the brightest bulb in the Christmas Tree, but I know that the current theory makes about as much sense, as to ask what's the difference between a canarie!!! It just makes no sense, no matter how smart you want it to sound.
@@realitycheck3363 well, Occam's razor simply doesn't apply, because the universe does not lend itself to a simple explanation of it's nature.I guess one of the main issues is that many people tend to try and visualize the universe as some sort of expanding fixed volume, or the bread with raisins in it type deal, which is also a wild over simplification only meant to give people an idea of inflation. Trying to see the universe, at any point in time, as a volume of some fixed value, at some fixed time, are also hopelessly wrong, in pretty much the same way as Heisenberg's uncertainty principal. Like trying to pin down an electron, granularity just does not exist. You can talk about probability, but that's as good as our understanding gets. Look at it this way, if you imagine the universe as some fixed thing, and then you say, the center is...THERE !!..well by the time you've said it the universe has moved on and your determination is not valid anymore, not that it ever was, anyway. Trying to think of the universe, regardless of it's age, as some sort of volume with a time attached to it is simply incorrect, we can't even talk about volumes as such because there are no formal ideas about boundaries , between the universe and the idea of outside the universe. Basically, human ideas just don't WORK for trying to conceptualize this , thing. I know that's hard to swallow, but there it is. People just have to accept that there are things out there that are simply too much for our tiny little limited finite minds,. Most of us can't even grasp the size of our planet, let alone a light year, so imagine how far beyond our comprehension things like the Planck scale, or infinite inflation , or even the idea of a Neutrino going through the Earth seventeen times before finally hitting another particle and hardly noticing it, those things are simple compared to the nature of reality, and yet people seem to think they have a good handle on it, they have no idea.
@@psycronizer Scientists can tell you in great detail, and with utter conviction, that "so many billions of a second after the Big Bang, the universe was the size of a tennis-ball, and so many seconds later, it was so big...", etc etc.
Now I don't care what's outside this homogeneous and isotropic expanding sphere, that is not important. The fact is that it fills a sphere shaped volume, and that means by definition that it must have a center.
My question thus, is that when it was , let's say the size of the sun, it had a center. And that center remained at the same spot by the time it was the size of our solar-system. It could only "lose its center"as it were, when all sides of it expanded beyond the horizon of our visible universe. But that does not mean, that now suddenly "The center is now here, and there, and everywhere!!". I mean, that just makes no sense! I think your last sentence is the only valid statement. We simply don't know.
But claiming that the center is just at every single point in the universe, is just...silly, really. At least, that's my humble opinion.
As it is hard to wrap your brain around the entire universe expanding uniformly from our position within the universe, I find it easier to picture it as everything in the universe shrinking while the universe stays static.
Although I am not good at math I am good at understanding what you are presenting. My mind is constantly multitasking all the new things in life that need to be grasped from the birth of humanity to the why's of creation.I really learn a lot from you because you summarize concepts that I do not have the time to fathom, This makes you special in my reality and I thank you greatly.
If "we" aren't creating more space-time 'fabric' and just "stretching" it, how far can space be expanded before space-time 'rips'?
dark energy implies we are actually creating more space-time and are not stretching it.
I would go look up "the big rip" theory for the end of the universe...
An astrophysics expert told me the speed of light is the speed of time. It was the basis of her thesis for her PHD.
I think perhaps dark energy stretches. Becky's colored balooning galaxies became much lighter as spaces moved in between, at least in 2d. If some thing's are fixed points, then they start to look a little silly if free-will implied malleability of fixed points. But then we're back to, do we see on 2d or 3d?
In 2d we need colors shadows or light to differentiate the plane from the angle, which takes time, in which we always chose 1d single plane, or can we choose two faces at a single time instance? Is the door open cannot be in between y,n.
But standing in the threshold
can be confusing to m, in the room, or not in the room.
@ZINDAO dark energy isn't a thing that you can control or something. The term "energy" could lead you to think it's some form of energy but in actuality it's completely different. The universe is expanding and accelerating which means the rate of expansion increases too. Scientist's theorize dark energy is the one behind this expansion. In a video by *Kurzgesagt* about dark energy it was said that new space is created everywhere because of dark energy. But dr becky disagrees with me. Anyway im pretty much a noob and my degree has nothing to do with astrophysics so don't take my word for it.
I already have a deep love for astronomy and the cosmos, but man I wish you were my teacher in high school (or college)! Love learning more here!
I think Van Halen had a song about that...
@@commentatron I’m not too familiar with Van Halen (I know, shocker), which song are you thinking of? :)
And she's easy on the eyes!
thanks for this video. I've always struggled with this idea from astrophysics. Bag that balloon analogy!!
Thanks for sharing dr Becky 🌌
Just excellent. You are passing on your love of astronomy to others in a way for everyone to grasp! :-)
5:41 _"There's nothing to do with 'higher dimensions' or anything like that that's driving the expansion"_
Dr Becky, subtly making String Theory fans cry.. 🤔😉😂
I never liked String theory - Bosonic string theory was quite new when I was studying Physics (Leeds Uni, 1981-1985), and during my last year, 'superstring' was beginning to emerge - It all just sounded 'contrived' to me at the time... the maths worked if you assumed enough dimensions... but it seemed VERY far from being an elegant solution.
Dr. Becky is the center of my Universe, my love expanding with each new video
Thank you for keeping it clean. Not adding another dramatic music.!
There is a problem here! With us expanding like this I have noticed that my CLOTHES are not expanding at the same rate I am! On another note, if we had a very fast space ship I can see it would be VERY easy to get utterly lost out there!
@Boodysaspie I was trying but you two were not just faster but far wittier.
Gee Doesn't That Rip Your Nightie .
This has always puzzled me. Yours is the first explanation that helped make this complex concept understandable. Thank you!
I am so happy that I have stumbled upon your channel. I really appreciate the perspective you share with us. Its nice to have some new food for thought! Love ur content! 🥰🥰🥰😁😁😁😁💚💙
a refreshing down to earth, clear, no nonsense style.
I think there are misconceptions on both sides. I think it really depends on the shape of the universe, if there is one. If the universe is sphere then it would indeed have a center. But this is something we will likely never know.
I was just thinking this
But the sphere doesn't have to be 3D. If it's a 4D sphere, it might actually have a centre OUTSIDE of our space, in the same way a balloon doesn't have its centre on its surface.
Although if it indeed is a 4D object, it's probably a torus, because a sphere has elliptic geometry on its surface, while a torus (or, more accurately, a Clifford torus) has Euclidean geometry, and from our observations space is Euclidean.
@@Adam-zt4cn Are you really sure that space is Euclidian from our observations? I think we need more data & studies. Maybe we should also survey even bigger volumes of spacetime to see if it is curved only a tiny bit
@@gammarayneutrino8413 Well, this is one of those problems that can only be solved by waiting few decades for better equipment.
Depending on how you look at it, I guess the centre is based on your perspective... and you can’t really take away your perspective to see which way which galaxies expand to. Some interesting stuff!
I mean, that's the exact wrong way to look at it. That is the, I guess, intuitive way to think of it, but it's wrong.
OMG perfect video...I've been commenting all over StarTalk about this trying to wrap my head around it. Exactly what I've been looking for. Like and Subbed!
I started thinking more about plants growing to help wrap my head around it until just now seeing this video. As plants grow, the whole plant itself is getting bigger so any two or three points are always getting further from each other, but not from a central point. But it does make me wonder about what you said near the end, maybe we need to zoom out. It so odd to imagine everything just popping into existence and then expanding but not from a central point. Yea I'm starting to go backwards again haha....wouldn't it have to have come from a central point if everything fit into an infinitesimal small point and then grew? That's why I'm liking the idea that we just can't see the bigger picture.
I love you, Dr. Becky. I was just thinking of this question the other day. Oh, and you sung the Galaxy Song! Eric Idle's masterpiece. You rock. Now, do a show about 'voids'. They always fascinate me. I'm a nascent sci-fi writer and I'm cramming a lot of info into my head to prepare!!
She's doing a good job explaining things in a simplified way. Saves up lot of time for us.
I believe Henry of minutephysics called "big bang" "everywhere stretch" in one of his videos ages and ages ago
You right. One of the legends of yt science community.
7 years ago! czcams.com/video/q3MWRvLndzs/video.html
You are a great speaker wish we had more teachers like you.
Thanks for video keep going 🤠 greeting from Morocco
Missing a coordinate: WHEN is the center.
Now
The halfway point between the beginning and end if it has such things
What if we dont add space but time. All places are now but time is growing inbetween🙂.
There is none.
0. We know that one.
You're such an excellent teacher. Even when I know the subject or question in your video title well enough to explain it to others already, I still learn from your videos.
I have aleays enjoyed your enthusiasm, presentation style, and wealth of knowledge. Thank you from this creature in a complex universe.
Thank you.
The rate of expansion appears different in different areas. Perhaps this is because of the nature of the universal core and the time it takes for us to observe changes to it.
A core would also likely be massless and possibly lack any emission of light.
The fact that we imagine that the expansion of the Universe is a stretching is why everyone wants a centre to the Universe. The thing is everything is moving away equally and in every direction at the same time.
I once asked a science teacher in high school back in the mid-80s "If the universe is expanding what is it expanding into?" He gave me a confused look and said he didn't know. An honest answer from someone who was a high school science teacher in the mid-80s and not an astrophysicist.
Love Dr Becky.
According to most people these days, especially people who are constantly taking selfies... THEY are the centre of the universe!!!
"I am a sort of aperture through which the universe appears." -Alan Watts
While the universe not having a 'center' is fairly perceivable under this description... I think what people are trying (and struggling) to comprehend is the "starting point." The brain naturally assumes that the 'Big Bang' must have started somewhere, and I think people just find it easy to try and label that 'starting point' as the 'center' of the universe. In other words, when the scientists say all matter was pressed down into an inconceivably small point before suddenly expanding outwards... people are presuming there must be a location, somewhere, where that infinitesimally small 'singularity' of matter started out, before 'exploding' into it's expanding state... and therefore, it's difficult for them to conceptualize why we're unable to pinpoint that particular location.
If there was a beginning point of origin of the "Big Bang" how can that not have been the center of the forthcoming "expansion?" Here's another thing... if 1 can be divided by 2, and that number is divided by 2, and that number is divided by 2... on and on and on... this paradox implies an infinite regression toward an unattainable center. Could not the opposite be implied for an infinite universe?
@@tubecoatue Infinite? Yes. "Tunderbolts Project" channel on CZcams. I thought I'd take a look at some comments before I finished watching this video and I came across your comment. Aren't you lucky? Well on to finish watching the video and I'll leave a main comment. All the best.
Hi! First, you’re amazing. I just discovered your show on you tube. Space and physics fascinate me. It makes my head hurt but it fascinates me. Your balloon analogy helped a lot. I get that we don’t know the size and shape of the universe and the universe is constantly moving so I get that we can’t calculate the center. What I, and many lay-people, have trouble with is common sense tells us everything has a middle. Thought?
I enjoy your videos very much. Can you please in one of them explain the flat universe?
Wait so it’s all the center?
Always has been.
That clears up one query of mine. I often wondered how we knew the universe was expanding, as galaxies would expand at the same percentage rate, as would solar systems, tape measures, the wavelength of radiation, indeed atoms themselves. Ok, so gravity negates the cosmological expansion within galaxies.
But experiment has shown that the fine structure constant and other 'atomic properties ' have remained constant over the life of the observable universe. Is this because something balances out or negates expansion on the atomic scale?
Or is it that we measure everything from the atomic scale and it's expansion hides everything up to the scale of galaxies?
so, what is it expanding into/and what is causing the speed up?
One thing that always drives me crazy but you explain the reason why well.
Thanks for that great video! I have a question though. I think I manage to understand why the big bang happened everywhere and not only at a given point. However, if the universe is finite and with borders, doesn't it make it having a center by definition? If it is finite, with border, there must be a point which is at equal distance from the every points of the border (if the universe is a 3D sphere). I totally see why there would be no center on an infinite universe or a finite univers without border, but I really can't understand a finite universe with borders having no center. Can someone please point out what I am missing? Thanks!
Just late night thought from my side: Sure it could have a geometric center but that wouldn't mean anything special or that something important exists there since nothing moves in relation to it. We like having a point of view and relating everything to that point but that doesn't really work with the universe especially when we only probably see a tiny little bubble of the whole thing.
Thinking on a limb here. If the reversed process, shrinking space in the same way that it expands i.e everywhere at the same time, happens. It kind of gives you an idea (in my mind) that a center doesn't exist. It doesn't shrink into a predetermined point, rather slowly finds it, bit by bit. After the process has finished it might be were we put out what we thought was the center when we started but statistically it is very unlikely to be that point. What my brain has come up with during me thinking and writing this is that, sure we can put out a center one moment but what would say that that should be the same spot where we in a few moments later, when the universe has expanded some more, is the center for us now. Even if the universe is finite the mere prospect that it is expanding makes it impossible to have a center in my mind. Even a geometric one, maybe.
You haven't missed anything.
@@BenjaminPersson thats the key. we use to think expansion from the beggining like a ball growing in size, but it could rapidly take the form of a disc, or a potato. with more energy and matter in one side that another. maybe the universe is not simetric at all and doesn´t have a real center. but several central points
@@elpelagabriel1755Any object can't have more than one centre point, that's why it's called a point. If there are multiple centre points as you suggest, you can interconnect them all and find the centre point of the 'centre points', which is eventually the centre point. You get my point? 😄
They say the universe is 93 billion light years in diameter??? If so then something with a diameter would have edges and a center . Also if the universe is expanding why haven't. the constellations changed in the last 150,000 years?
I guess you can say that the observable universe has a center, and that center is us
Yeah, everyone is the center of their own universe.
That's what I thought.
Well, if you put it that way, the centre depends on your perspective!
Another life form similar to us with similar technology in a different part of the universe would be able to see areas of the universe we can't see and we are seeing areas they can't see. And there are over lapping areas that can be seen by both.
Mind is blown thinking about this...
thank you so much. I am totally relearning what the big bang is. so in the start of the big bang was energy and mass extremely close but for an infinite space? and if the universe is expanding uniformly(meaning galaxies arent really getting closer to each other), did most of the galaxy creation start early on in the universe?
Was the universe infinitely big when it was smaller then an atom at the moment of Big Bang?
This question doesn't make sense because space itself, as we experience and understand it, doesn't exist outside the universe. Space is a feature of the universe. It is space itself that expanded, or, there became more of it. Asking how big the universe is from outside the universe where space itself doesn't exist just doesn't make sense, like the question of what the universe is expanding 'into'. The universe, from that perspective, may still be infinitely small and has never changed size, just become more densely occupied with space.
In order to find a center, you need to know the object being measured in its entirety.
We can only see so far out,so until we can see the Universe as a whole it's a moot point
It would be like asking a land locked provincial person in ancient times to find the center of the Earth.
They wouldn't have the information needed at that point and it would be all speculation.
In fact, finding a center to the Universe would only be possible if viewed separately from the observer.
But that brings up the idea of whether the Universe is contained in an environment or void and can you get far enough outside of the Universe to view it as a whole?
I learnt something new here!
The galaxy song is awesome!!
" The universe is a place where the centre is know where and the circumference is everywhere ."
Hi Dr Becky,
I know you have heard from me before, but I would like to thank you again for being such an inspiration.
Keep up the good work!
Thanks 🤗
@@DrBecky big is a matter of comparison its relative so how much bigger can you get then the entire universe
But big is different to inspirations!
Every inspiration is the same, I don't think it's something we compare.
@@nousernamejoshua1556 just know that she is an inspiration to me!
@@ChiB2004
Right, I should have tagged Osmosis! 😉
thanks
That's the best use of 'Not to scale' I've ever seen.
Is there a finite amount of matter in the universe? Also can each particle which exists have a location which can be described in some coordinate frame? To me it seems like both of these are true and they lead to the conclusion that there is a center. Just take the mean of their positions.
If there is finite matter, then there should be an edge where stuff hasn't expanded into yet. It seems to be the case that in our current location and time, stuff has expanded out enough to all look uniform but that doesn't mean there is no center, it just means that it is impossible for us to eve locate the center since we would have to go faster than the speed of light to explore the regions we cannot see.
I am not a physicist so if what I said is wrong I am happy to have someone more knowledgeable explain it to me.
There is no edge. Just as the surface of the Earth doesn't have an edge you can fall off.
@@frankshailes3205 the earth exists in 3 dimensions, and there is a pretty well defined edge where the sphere of the earth ends and space begins.
Using the method I described it's very easy to define the center of the earth in 3 dimensions. It's just the center of mass.
So my question still remains why can't we just define the center of mass of the universe? (assuming finite mass)
@@petrosidius But the /surface/ itself has no centre, there's no point on earth's landmasses from which everything originates. The balloon surface analogy is showing a 4-dimensional thing in 3 dimensions. The "centre" of the universe would be in a fifth dimension really. The universe is finite but unbounded. If you travel long enough, you'll get back to where you started.
Thank you for this. I have tried to imagine/explain the universe as an expanding bubble for a while, and it really helps to visualize what’s happening/happened. The drawback is as you greatly explained. Correct me if I’m wrong, but you can look in any 3D direction and observe the background radiation given off by the Big Bang. What I visualize is looking toward the center of the balloon. In this distorted representation of the universe there would be a center, but it’s pointing through time, not the 3 dimensions we inhabit. In other words, there is a time center of the universe. This makes me think, could we not observe the universe in its entirety if we can see far enough back in time? Could you go on to explain how the limit of the observable universe is established? Thanks ahead of time. I’m genuinely curious.
Yes…exactly so (see my input a year later in Aug22) You have it spot on. It is hard to explain this to people because they only visualise an explosion of light in a big dark void…which is totally wrong. It is in reality a 4D sphere…time is the radius, space can only be visualised as a surface..but as a model it works beautifully. Time is not different to space…just at right angles to it. It is all the same medium or fabric…and is why it is called Space-time, not space and time.
Hi Becky, how can you have gas pressure without a container?
When I rolled in here I was prepared to refute your assertion that the universe does not have a center. You took the wind from my sails with your excellent presentation. Your analogies of the balloon and explosions helps me understand the universe more.
One crazy thought that may be related is the inter-relationship of the universe and one-sided objects. Everyone here could make one in a minute or two and hold it in their hand- a true one sided object with no tricks involved. We are talking shapes and it seems a round universe may not be true and we may never know what shape the universe may be since we will never be able to observe or map it all. All the weird shapes in field of Topology may give us some ideas of what possible shapes the universe could be.
Your explanation of expanding space at the beginning and the '3d' balloon analogy is the best I've heard thus far. Your explanation of the observable universe being earth centered vs the entire universe having no defineable center is perfectly pragmatic. Many thanks.
The center of the universe is in your heart ❤
I've started a new habbit. With my morning coffee I watch one of your videos . A lie two or three of them. I will catch up soon. You make it so nice to learn new things. Peace love & stardust. TomCat
PS I now feal a good grasp of todays topic and it was fun to do
Similar to the analogy of the balloon, i also like the raisin bread in the oven one where each raisin are getting more spaced as the bread is growing but still perfectly still relative to the size of the bread.
It must be difficult to date a cosmologist...they always need their space.
They have a fixation with Uranus.
@gunther giesl 😁
A slight error: the observable universe is about 93 billion light years in diameter (thus its radius is ~46.5 Gly, not 14 Gly. It's a common mistake made even by scientists sometimes. The universe has been expanding for almost 13.8 billion years so the light itself is traveling the expanse ...
completely right!
And everything we can see has an age less than 13.8 billion years
Completely wrong, we can see 13.8 billion ly in every direction. An observer at the edge of our observable universe would perceive us at the edge and could not see past us.
The radius of the observable universe is, indeed, 46.5 Gly. If the universe began 13.8 billion years ago, and space did not expand, then the edge of the observable universe would be 13.8 billion light years away. However, the universe has been expanding for that entire time (including some pretty intense expansion early on), which pushes the edge of the observable universe further away.
To understand this, let's imagine that, at the moment of the Big Bang, a photon was emitted 750,000 light years away from us. Let's also assume that it doesn't run into anything, and just careens toward our eyeballs at the speed of light. 500,000 years later, the universe suddenly doubles in size. The photon's origin is now 1,500,000 light years away from us, and the photon still has another 500,000 light years to go before it reaches us. 500,000 years later, the photon reaches us, and the universe suddenly doubles in size again. The photon's origin is now 3,000,000 light years away, even though it was only 750,000 light years away when the photon was emitted.
This is a case of the most powerful force in the universe: compound interest. In the example, the size of the universe was increasing at a constant rate of 100% every half billion years, and was compounded every half billion years. In reality, the rate of expansion has changed over time, and it's compounded continuously. Either way, you end up with some pretty big numbers.
She is wrong to say there is no center, of course there is! We just don’t know where it is. We don’t know where our observable universe is in relation to the actual universe, so we may never know where the center is, but it doesn’t mean there is no center. And I do not buy into an infinite universe, in nature, nothing is infinite. And if the universe is expanding, how can an infinite object be expanding? If it’s already infinite, how can it get bigger? The very fact that it’s expanding proves it’s not infinite. And any object that is finite, has a center.
i question..... thanks for answering....
Thanks, great explanation! Wondering if the questions marks in your later graphics are where dark energy resides
No. Dark energy is needed essentially everywhere to drive the universe apart.