"Question your assumptions. Try it, it's fun!" You guys are great, thank you for all publishing these videos! You have reboosted my interest in natural science.
This is by far the best explanation I've seen yet! I've read all the articles about these phenomenon but videos like these are perfect for putting it all together. Thanks PBS!
+btdtpro scientific inquiry... Although anyone would theoretically be able to repeat the experiment, I doubt many would. Even then, results may not agree.
+nikitha nayaer I don't get how the fuck he got all of his shit right. I mean I literally would be willing to believe anything he told me. If he said the earth is flat I'd say sure if you say so einstein
@@deusexaethera Kinda. He was actually terrible at it. His wife worked out most of his math. He was a thought experimenter, and he didn't really get much right if you ask quantum mechanics. But the problem, in my opinion, started with Aristotle. He was wrong about a whole lot of things, like actual infinity, and the forces of chance and luck being quantifiable considerations. If you consider the Big Bang a continuation rather than a beginning, and consider the Universe's composition as being entirely comprised of "sound", or waves of frequency and vibration, it changes almost everything we currently hold true about classical Physics, but gets us closer to understanding why we know absolutely nothing about how quantum mechanics works. I always compare it to being given the paradoxical answer to a logical problem and having to guess at the question.
I just found this channel yesterday and today is a free day for me so i'm just gonna make a playlist of all these videos, get a huge ass bowl of popcorn, get a friend to come over and watch all these videos with me. Holy shit im excited
Does anyone else enjoy the very last bit of these videos lately almost as much as the rest of the content when Matt either dishes out an epic burn or in this case, reveals to us that he's actually really, really, really, ridiculously good looking?
+Deaf Keith hey Deaf, nice to meet you, essentially, if you know of the big bang theory and the expansion stuff, i can crudely explain what this video says. the universe, as we know it when it was a singularity (so far) was practically flat, we looked at the CMB and using trigonometry have deduced (so far) that the universe is 0.4% flat and can't be curved like a sphere. we know this because trigonometry on a flat surface when you draw a triangle with straight lines, the angles add up to 180, but when on a sphere, it's more than 180 showing there's extra space being used when opposed to a flat paper, it even adds up to less when using a hyperbolic plane ( 2:00 mark ) so using these observations and applying them to our universe tells us the difference between a triangle on a paper is a 0.4% positive amount more than it should be if it were flat. the bowling you saw was a basic analogy. saying the universe rolled a slow slow slow bowling ball down the centre of a lane at the speed of light for 1 light year and it only deviated by 0.4% there's a lot more info, but that is the basics with my rudimentary use of language. i'm sure youtube will add CC at some point.
+Deaf Keith if the universe didn't start out flat, or had any kind of "not flatness" that would have been amplified during inflation..... our observations tell us..... flat! until we can observe and prove otherwise!
Boy I wish I had continued my science studies because you really lost me in this episode. Trying to work out that cosmological constant equation in my head nearly caused me an aneurism lol. But I absolutely love these educational shows every week and they inspired me to sign up for a 101 cosmology course just to learn. Keep up the good work :)
In many of your videos, you do a great job of crediting and even showing images of the people who made various discoveries and breakthroughs. It's strange then that you haven't even mentioned Alan Guth, the man who gave us inflation. He deserves kudos for his brilliant concept.
I don't doubt his knowledge of cosmology but I wonder if he knows much about bowling. He says nothing about oil patterns or revs 😁 + imagine the light year long alley how long a pba tournament would take!
Man these are awesome! Excellent speaker, fitting music, and beautiful presentation!!
Рік тому
I looked at the animation at 5:00 frame by frame and figured out that the zoom factor is at least from Planck length to 0.6 light years, but probably a couple orders of magnitude more, because at the start, there are probably two 9× zooms per frame, it's hard to see. Good job on the accuracy!
Brazil desperately needs a Brazilian-Portuguese version of this channel to combat the fast growing scientific repulsion and willful ignorance the country is drowning itself into. Brazilians learned quick and simplistic challenges to Big Bang, Inflation and other astronomic theories; they attack things they don't even say, nor imply, as a way of self-affirmation. It is like they were taught that those theories are wrong, but they were never taught what those theories are or say.
Mr Aquiles I would definitely help get the scientific communication community from Brazil, such as podcasts and channels, to start a funding campaign if necessary.
Thales Teixeira eu não só conheço, como tive meus emails lidos no ar vária vezes, participei da gravação de 2 episódios, da pesquisa de vários outros, e ganhei de presente a caneca e a camiseta hahaha. Can we avoid speaking in Portuguese here? I really don't want to scare the English speakers away from the conversations.
+PBS Space Time Sir, got an important question thats bugging me 4 quite some time.. I thought Universe even today is expanding at exponential rates. So whats the difference between inflatory expansion and regular expansion if universe is expanding at exponential rates??..well what can be more faster than such an expansion?
+TheAfroOfDoom There's a short bio on Matt in the "about" section of the channel which includes: "He's now a professor at the City University of New York and an Associate at the American Museum of Natural History's Hayden Planetarium."
+Sachin Raj The coefficient on the exponent (the efolding time) is very different. Now it is like 20 billion years and back at then it was more like 10^-30 sec
hi its been 6 years hows everyone doing in 2023. for me its good learning some new things.Have IGCSE OL exam this year in may/june hoping for the best. And good luck on anything your guys doing. Ezran out!!!!!!!!!!!!!!!
2:28 I still haven't figured out that one. The CMB blobs are defined how fast sound waves could have traveled? I can see how the earth angle is measured (but I don't see how it comes to one degree), and I can see how a rough long side is estimated (by red shift), but I can't see how the rest of the trangle is measured.
+Tobias Ruck I don't buy it. earth is round, but the solar system and galaxy are flat? But dark matter is round but the universe is flat? They're making it up! Timecube!
bakuya99 Im a highschool sophomore im double stacking sciences (AP Physics 1 and Space Science) and literally space science has taught me nothing except for that space can kill you
Skytivity That's why i said public school education. I mean this type of science should have been taught to you and me actually. Hell i never learned anything really useful in science class in school. I had to learn evolution and this type of science on my own.
+Skytivity That's very sad. But the fact that you are here with the rest of us says a great deal about you and your scientific curiosity. In the end, we are all responsible for educating ourselves. Congratulations! You have a great life to look forward to.
Okay, our observable universe appears flat from one end to the other (93 billion light years). However, what if the actual universe is big. REALLY big. So big that, any area of 100 billion light years across might appear flat from horizon to horizon, but, like our Earth, it is actually spherical, only appearing to seem flat when viewed from any given location. Is that possible?
Thats why he includes the caveat "it's WITHIN 0.4% of perfect flatness". Meaning that as long as the universe is big enough to curve less then 0.4% over the course of 13 billion light years, then you are correct it could still be curved. Just so you know, that comes out to a minimum size of 25 TRILLION light years.
Everytime I watch an episode from you I get a bit closer to abandoning my current career path (Life sciences), relearning all the Calculus and Basic Physics I used to be good at 10 years ago and then taking up advanced physics. Maybe I'll just start with taking some classes at one of the universities close to me.
At 8:27, how did expansion slow down if it's speeding up now? Are we just talking about a slowing of the acceleration rate? In which case, expansion is still...actually slowing down overall?
What confuses me about this topic is why is the horizon problem such a problem? What about the big bang says that a universe cant start homogeneous in the first place? with out the need for any time to reach equilibrium. Thanks
Just in case you haven't ever had this answered....there is no problem with assuming the universe started out completely homogeneous. The issue is that's just that...an assumption. It offers no explanation for why or how this happened. Inflation provides an answer for how this homogeneity was accomplished, if not why, and scientists are always trying to explain what they see, not just observe it.
+Neceros Sure it is. Instilling people with the wish to find out for themselves is _exactly_ how to generate educated citizens. Problem is, the education system does a piss poor job of that, with most schools teaching rote memorization without coherent purpose. I didn't discover the joy of science until I was in my 20s, and when I did I was left wondering: "why didn't any of my school teachers turn me on to this?"
Ryan MacFarlane ME TOO. I couldn't find a job after college, so I stayed home and decided to read books + google is a real help. I never loved learning until then. It seems that my hate for teachers translated over to the 'education' I paid for.
Kryzia Mae Aranda Could you imagine where the world would be if a majority of western schools taught people to love learning? What would the world be like if kids _wanted_ to go to school because schools were places which fired their imaginations?
Hang on, blackholes have magnetic fields? If nothing can escape the event horizon, how does a magnetic field form outside of a blackhole? A magnetic field has to be causally connected to the source of the magnetism, but whatever-the-hell-is-inside-the-singularity can't radially affect the outside world. Does blackhole spin matter here? [Does this question even make sense?]
you are right, also another problem is that this accepted science is using inventive science as a tool to use theories to prove other theories as factual ? what happened to scientific method ? I don't trust any scientific claims that refuse to follow scientific method
Your question is a very good one. There are more details to consider but the following answer works for the classical case. Recall that from the point of view of a stationary observer outside the black hole material never enters the event horizon. This includes charged material which when spinning results in a magnetic field.
+Astronomianova I did not consider that, but that is a really interesting point! After thinking about it for a bit, I did come up with a question about it though: From our point of view, all the matter freezes as it approaches the event horizon, so if that is where a BH magnetic field comes from then if you sent in a large amount of charge onto just one side of a BH, that should give us an unbalanced magnetic field on one side of the BH, shouldn't it? Since we see the magnetic material all freeze on the one side of the event horizon, we'd see the magnetic field originate from that side instead of the center, which can be a significant distance. However, if the magnetic field did actually come from the singularity itself then we'd still see the magnetic field centered on the BH as normal. So which one would we actually measure from the outside?
Some charged (or uncharged) matter falling into a black hole would appear flattened as it approached the horizon and in fact would quickly become a layer just above the horizon. So the charge would be evenly distributed on the horizon--as if it were a conductor. This is again from the point of view of a stationary observer. I am not sure about the details for a charged spinning black hole but this is what occurs for a classical description of a Schwarzschild black hole. Also note that even if the charge were not evenly distributed or before it becomes so, the magnetic field would not emanate from the charge but would be closed loops above and around the swirling charge.
What about entropy? Thermodynamic "end of the universe" means that every region of the universe will have the same properties (pressure, temperature) everywhere. Does this not make infinite inflation impossible (every part of the 'verse strives after reaching maximum number of possible states, after all = max. enthropy = equilibrium)?
You might be interested in some of Roger Penrose's UA-cam videos. He thinks this death-of-universe equilibrium state could be the same as the pre Big Bang state, not that I completely followed his logic.
Why something like the schwarzschild radius does not apply on the early stages of the universe? Wouldn’t this extreme density create something like a black hole??
Part 2'- At 13:40 we are asked to change are thinking on the term "Beginning." My question, why the equivocation on the beginning of the standard model? Do we really want to define the beginning of the universe at the beginning of the Hubble expansion? If so then we are now in the unenviable position of having to change are initial state. Instead of no space, no time, no energy, no matter, no laws, we have space, time, laws of physics, a high-energy false vacuum,etc. That is a lot of EXISTING stuff before the BEGINNING. Of coarse theoretical physics often proceeds with thought experiments. And they are helpful. However, these same physicists don't always come bring these idea properly back into the real world. Hundreds of thousands of these thought experiments have been falsified when testing the inferences in the real world, why assume these don't need to be tested to be right. Which of the 200+ inferences about multiverse theory are right given that they are untestable.
You have done an awesome job explaining a lot of the space science to people like me, but I am still wait to see if any of this relates to dragons? or is it possible that you might just have an issue with dragons? Or did I just miss that video?
+Opal Dragon Dragons had Godlike powers before the moment of the Big Bang. Hopefully, with the new discover of gravitational waves, we'll soon set up a "gravity map" of the Universe, and we'll no doubt see that dragons started it all.
+Opal Dragon A dragon killed his father. He doesn't talk about it much, but it's a real issue with him. I don't expect much from him on that topic in future.
I think so. But isn't the speed of sound dependent on the medium? I think he meant to say speed of light, but that's the speed of causality first, and I can't think of a reason why the propagation of a wave would be limited to anything less than that, given an arbitrary medium.
I had an epiphany last night, when thinking about this before sleep. Bear with me, this will (probably) be a long post. You are mentioning that inflation happened in space. Not in spaceTIME. It was never mentioned here, what had inflation to do with actual spacetime curvature. Did it also involve TIME curvature? Or does it only work with space alone? So does that mean, that time went smoothly while space inflated? How is that possible? Is the time not interconnected with space no matter what? We live in a 4D spacetime after all. So this train of thought lead me to an idea - if the cosmic inflation also stretches time as fast as it stretches space, it could mean, that before inflation, time was "stopped". There was not enough "time" on the y-axis of the spacetime diagram of Space in that era. The spacetime diagram of Space itself, from that era, was just a point with no available space to move to on the X-axis, also there was no time to do anything, as the Y-axis was also a point. From the viewpoint of the Space-singularity of the era before inflation, not only space itself was infinitesmall, so was time. So the term "next moment" was not even a possible term, it was not defined. It was not possible for the Space to expand - to move spatially, because of the infinite curvature of space, it was also not possible for the Space to evolve - to progress to the next time interval because of the infinite time curvature. Is this idea at least marginally correct?
It is sad to see so many amazing questions not answered, you could try asking this question on physics help forum.com and you will get an answer 100%, I would like to know the answer too
I think you hit the nail on the head, my friend. We know that gravity has a direct bearing on time. Your feet age slightly more slowly than your head. Einstein hypothesized that time would stop incrementing at the speed of light, if this is true, than time must be instantaneous for any light travel. That is, when travelling the speed of light, any distance would be immediately transversed. We have some trouble thinking about this in the correct way, I think. If we observe a pilot launching and travelling at light speed to a distant star, 5 light years away, to us they would essentially vanish. To the traveller it would be a blink and he would be at his destination. To the distant station, it would be five years later than when the traveller left. Time does not speed up for someone travelling at light speed. Less time OCCURS. If you were to take a measurement of the cellular age of the person travelling light speed, their cells will have aged only seconds, not years. This seems to be paradoxical, and it is, but it's also the only reasonable way to make sense of the differing frames of reference, and how they can merely resolve when you arrive at a similar referential spacetime. That also means that in a massively dense black hole, time would increment excruciatingly slow to our frame of reference. One of our seconds might take a million years to elapse in such density. A year could take billions, even trillions of years in our reference of time. Yet our Universe (since the last Bang) is only about 14 Billion years old. In reality, we've already seen that the speed of light represents no real limit. We can observe the farthest remnants of the visible Universe moving away from us FASTER than the speed of light, which seems...impossible. Unless you consider Einstein correct, and that the speed of light also represents our theoretical 0 point with respect to time incrementing forward. That would mean that the Big Bang has already happened infinite times in the time it took me to write this response. We aren't retracting into a singularity in a crunch, we are expanding INTO it. Our 100 years of life and binary intellects make the infinite an impossibility to fully define. I suspect that IN a singularity large enough to swallow the infinite Universe the frame of reference for time would be infinite in much the same way that the speed of light makes the finite instantaneous. And as we accelerate towards it, we'll eventually, if Einstein is correct, be in a reversal of time, though to our frame of reference it would appear no different than moving forward. You ever get the feeling you've done this before and that our past is ahead of us? All finite things in an infinite Universe are infinite things in a state of perpetual finite change, energy changing state. You are made of 6 billion year old carbon atoms. Are you really you? Or are you just reverberations in an infinite spectrum of waves and frequencies observing other wavelengths and frequencies? in a narrow spectrum and calling it "reality"?
Could inflation explain also the matter-antimatter asymmetry? Inflation could be for some reason more powerful on antimatter than on matter: in this scenario antimatter could be in the same amount of matter, but outside our universe horizon.
+Beppi Menozzi No. Firstly inflation involves space itself, which should be independent of matter\antimatter. But inflation occurred before matter and antimatter could even out, when energies were high enough to convert particles and thus produce and destroy matter and antimatter.
Nope, there's also the theory that there is a bifurcated creation with one half of the matter of the universe being immediately repelled by the other "positive" half thereby causing a binary universe, It's possible. that would explain the lack of antimatter in out universe, and Time would travel in a similar Incrementally forward manner" in the alternate universe.
Outside of our horizon is probably the smartest thing anyone has ever said here. The Universe is just really big... bitches. like Really Really big. like really really really really really really really really big. ;)
Is t=0 an asymptote rather than a point? (Similar to the mathematics of trying to divide by zero, or taking the logarithm of zero?) If you graphed the timeline of the universe on a logarithmic scale, would the universe appear infinitely old? What if actual time ISN'T linear (let alone one dimensional)?
How can a 3D space - the observable universe - have a shape that is "flat" or "curved"? I hear this a lot, but I don't understand how this would work. It seems that when you look out into space you see a 3D field, not curvature.
You should watch the Curved Spacetime playlist. Someone correct me if I'm spouting nonsense, but here goes: if you draw two straight lines that are exactly parallel to eachother, their distance from eachother will stay the same no matter how long the lines are. But if the space where you're drawing is curved, the lines will eventually intersect or separate from eachother. To give an analogy: you and a friend start walking exactly north from different points on the equator (so parallel to eachother) and you will intersect at the north pole even though you were both walking in a straight line. The surface of the Earth is "flat" in two dimensions, but curved in three dimensions.
snagari but that should only mean that the paths where never truly parallel to begin with. Also, with that explanation you could never observe anything but a flat universe since if the universe was shaped in a weird way, light itself would also follow this weird geometry and thus make the universe appear flat anyways.
Imagine you are a very small ant on the top of a sphere. You will think your 2d "universe" is flat but you can still find out that you live on the top of a 3d sphere: draw a triangle, it will have more than 180° as the sum of its angles. If you are an ant on the top of a cylinder, your triangle will always have exactly 180° (->flat). With our universe it's the same situation with the ant and the cylinder, only that our cylinder has 4 dimensions,so the top (our world) has 3 dimensions.
It's hard to imagine, as we're talking about the basic rules of geometry for space. Of course the universe isn't flat in the 2D sense. We have height, width, and depth. If the universe was flat like paper, we'd just not see one of these three dimensions. But what if one of these dimensions was warped? What if by travelling forward, you actually also move left a little bit? Imagine if there was no way out of that. Like when you drive down the street -- to you it looks like you're driving in a straight line. But to someone watching from space, you're driving around a giant sphere! This is actually exactly what inflation suggests. It *looks* like moving forward in space is just going in a straight line. But we think it's just because the universe is a REALLY BIG sphere (or some other curved surface). If you zoomed out far enough it would be just like a car going around the Earth :)
*'Talent Is an Asset' by Sparks; Lyrics from a truly great 1974 song about Albert Einstein* ''Albert is smart, he's a genius , Watch Albert putter, an obvious genius, Someday he will reassess the world and he'll still have time for lots of girls. When he grows up, he'll remember us, When he grows up we are sure that he'll remember us, We made sure that Albert wore his mac, We kept all the strangers off his back. Everything's relative (Go away Albert's mother said to me), We're Albert's relatives, and he don't need any non-relatives. Talent is an asset, you've got to understand that, Talent is an asset and little Albert has it, Talent is an asset and Albert surely has it. One day he'll sever his apron strings, All of the while he'll be scribbling his genius things, Look at Albert isn't he a sight, Growing, growing at the speed of light. Every things relative, (Go away), Talent is relative (go away), That's hypothetical (go away), We are his relatives (go away), That's parenthetical (go away), Spare your superlatives (go away), Where's the receptacle (go away), There's the receptacle (go away) Leave Albert's study room (go away), Leave Albert's happy home (go away), Leave Albert's neighborhood (go away), Leave Albert's city too (go away), Leave Albert's comfy seat (go away), Leave Albert's country (go away), Leave Albert's continent (go away), Leave Albert's hemisphere (go away) Leave Albert's planet too (go away), Leave Albert's universe (go away)....!''
At 5:17 or so, you mentioned that the 'entire observable universe' was so scrunched up that they were all causally connected. Wouldn't this apply to the whole universe, and not just the observable one? Or are we assuming on the basis of observation that is based only on the observable universe? That is we may hypothesize it is the the case with un-observable universe, but because there are no practical means of measuring that, we can't make a fair judgement.
My mind can't comprehend that the universe is larger than the observable universe. Like, what do we exist in??? What IS the universe? Where are you we?!
+TheJaredtheJaredlong The answer is really simple, actually. In terms of comprehending that there is more universe outside the observable universe...well, it's kinda like trying to view things over the horizon of the earth. You don't know if there even *is* anything there, because you can't see it, but you can reasonably assume there is, because there are things right up to that point. Unfortunately, unlike the Earth, we can't just gain altitude to see more -- or, at least, we don't know how to move in the fourth spatial dimension to do so (if we view the surface of the earth as a flat (2D) plane, we observe the universe as a 3D sphere....and would need an additional spatial dimension to 'gain altitude' as it were and see more. This assumes that this fourth spatial dimension is relational to our 3D space as the 3rd dimension is to our 2D plane). And as for the "Where are you we" part, my best guess is you are asking 'where in the universe are we'. We can *see* the observable universe, but we can't see beyond the horizon point. We have absolutely, positively no idea where in the 'total' universe we are (and, as of yet, no possible way to find out), nor do we know how big it actually is (again, as of yet, no way to actually find out). Following from that, we know we are in the center of our own observable universe (moving to another galaxy would shift the center of the observable universe to that new location). We know that we are in part of what we presume is a larger universe. And that's about the best we can do. Knowing all of that, what do we exist in? The universe. We exist on one planet that is a tiny speck when compared to our galaxy is just a tiny mote of dust. Our galaxy that, when compared to the size of the amount of the universe we can actually see, is just a speck of dust itself. And beyond that, we have no idea what portion of the 'total' universe is taken up by the observable universe that we see. If all of that makes you feel small, good. Because all of us are. Take heart, though, because you and me (and everyone around us) is actually made up of the same matter that went into creating the entirety of, at least, the observable universe. We are made of the universe, and are as much a part of the universe as is every star in the sky and every planet around every one of those stars. Also, if you read everything in this post up until this point, congratulations. You're worthy of the matter that makes you up. May the universe be with you. :D Edited because....why is it that no matter what you do, there's always at least one comma in the wrong place?
+TheJaredtheJaredlong "Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space." -- Douglas Adams
+TheJaredtheJaredlong the universe is just more of the same stuff as the observable universe, with the exception, that light of those parts hasn't reached us yet (and due to expansion probably never will), so that we can't observe it. It's pretty much like watching the water if you are in a boat on the ocean. You can just see a small part of the ocean, but the rest is (on average) more or less exactly the same, just a lot more of it which you just can't see, because it's so big..
But if inflation didn't start, then when did the universe have time to interact with other parts that now aren't causally connected? If inflation expanded space faster than the speed of light, then nothing could interact with other parts of the universe.
+Ciroluiro It seems like more to the point, everywhere in the universe was everywhere else also at the big bang. Everything in the Universe was all one big point which radically expanded.
+Ciroluiro Consider a tiny piece of an inflating space -- so small that, for the moment, it *is* causally connected. Now let it slow down to normal Hubble expansion; as it slows down, it's still inflating, so it becomes causally disconnected.
***** When was that moment if it was always expanding? Even if they are close, if the expansion is faster than light, the photons wouldn't be able to get anywhere.
+pbsspacetime Love your videos!! Is there any present theories on what actually caused the phase transition from 'inflationary' to 'Hubble expansion'? Cheers
Can you do a video on the cyclic model of the universe (e.g. Penrose's theory) as an alternative to the inflationary model? As of now, I'm not entirely sure how seriously I have to take this alternative.
"Questioning your assumptions. Try it; it's fun!" But once you start, you can't stop. And when you start questioning literally everything, you begin to exist in a perpetual state of mindfuck, truly understanding nothing and everything simultaneously. Everything, even your own understanding of life and the universe, begins to exist in this quasi-state of reality, where even reality itself is just an assumption which may or may not be real. Yet, if reality itself is not real, then the word "real" has lost all meaning, so perhaps the true invalid assumption is in our limited understanding of assumptions. Perhaps the most incorrect assumption we can make is one that causes us to avoid making assumptions. Or maybe I just enjoy screwing with the minds of fellow smart youtube people.
+Acid It's best if we don't know everything. It gives us something to 'think' about. Once everything is learnt, there is no longer a reason or need to actually think at all.
Not to cause an existential crisis, but both of your comments seem to be communicating the same idea: knowledge is one of, if not the only, fundamental reasons for existence. Or at least, one of the fundamental reasons to desire/enjoy existence. Which makes sense, I suppose, since there is certainly an innate satisfaction gained in learning new things and in understanding things completely. Not sure what that has to do with anything, just thought it interesting that you both said basically the same thing in that regard.
When we talk about the eaerly iniverse being small, 6:31 "You could hold in your hand" I get confused. I thought that a flat universe implies an infanite size (just with parts that are outside of causial relationships because it's expanding faster than even light can catch up). Are we just saying that the OBSERVABLE universe was condensed to hand-sized? What does that mean about the parts of the universe beyond what we can observe?
What stopped inflation? Or, to rephrase, why did inflation stop when it did? Why didn't it continue until quarks were as far apart as galaxies are today?
This video makes me feel both so smart and so dumb at the same time. I hope you dont judge me if all I take away from this is that the universe is a dam fine bowler.
+Jason Tesch Mathematics are the absolute truth. If Einstein's mathematical models are right, it is impossible for him to be wrong. This is why Einstein will never be disproved, his math is firm.
Maybe Einstein is always right because he observed the mechanics of the universe and collapsed the wave function (of infinite equation possibilities) around the math that he predicted. The actual act of Einstein conceptualizing the universe (with his math) forced the universe down that path. He "predicted" the Schrodinger's box equation and saw that the cat was dead before opening it, now every time we try to look in the same box we see the same thing he saw- a dead cat. The reality is that he never predicted the outcome -he just collapsed the available universes down to accommodate his observed equation. That, or he's just really good at math...
***** A theory still has scientific basis and is widely accepted. A theory is pretty much a law in science. You're probably thinking about a hypothesis, which is a complete guess.
Okay, I have a question. And forgive me if it is a stupid one, it is 1:30am here currently. So if the universe IS actually flat, and it would take (if you could pause time) 92 billion years travelling at c to "drive" across the entire observable universe...what would happen if instead of driving around the x and y coordinates of the observable universe (so to speak) we simply drove...up??? Would we reach the "edge" of the universe faster than if we were travelling outward along the "flat" observable universe? Aha, be gentle with your response, I think I am missing something simple, but I am curious! :)
+High-Density-Awesome you are imagining it wrong. The universe is not flat in terms as "flat as a paper". What was said here, is that 4D spacetime is mostly flat. When you go "up" you still move in one of the 3 dimensions. You would have to move somehow in the fifth dimension to get to the edge faster, I even think, that an entity living in 5th dimension would be on the edge of the universe in no time, if it wishes to do so, if that makes any sense. Also, what does "up" mean? My "up" is different from your "up", we live on a planet, not on a sheet of paper.
Hey Matt ever consider doing an episode about wormholes and their possiible use for interstellar or intergalactic travel or even time travel? Hope to see one in the near future.
+Ron Corless There's very little true scientific research involved there, I'm afraid. That's pretty much purely the realm of Science Fiction, because we have no way to test or observe any such concepts, even at an extremely abstract level.
it is so exciting to find such an advanced course on the subject on UA-cam in such "simple" terms
This isn't advanced. It's a very simple introduction. If you want advanced but understandable, try googling Susskind and Cosmology.
To Matt and everyone at PBS Digital Studios:
Simply, thank you.
Sincerely,
Everyone
I'm too dumb to understand this..... They lost me with the math.
EVEEERYONE
So... how did inflation flatten the universe?
"Question your assumptions. Try it, it's fun!"
You guys are great, thank you for all publishing these videos! You have reboosted my interest in natural science.
Every video makes me question my assumptions of what I understand about reality 😄
You gotta love how Matt O'dowd explains things.
"And we know how far away they are... they're really, really far."
That part cracked me up 😂😂
This is by far the best explanation I've seen yet! I've read all the articles about these phenomenon but videos like these are perfect for putting it all together. Thanks PBS!
"That's a science thing, questioning your assumptions-- try it, it's fun", I love it.
eat shit
+E.P. James MacAdams Top quality comment right here.
+Srikanth Gurumurthy I believe he meant to say, "I like to eat shit."
E.P. James MacAdams Hahahahahaha, You have a point. I assume shit tastes bad, but I haven't stopped to question that assumption.
+btdtpro scientific inquiry... Although anyone would theoretically be able to repeat the experiment, I doubt many would. Even then, results may not agree.
4:53 Was completely hypnotized by the background for the entire 1½ minute... I did not hear a word he said.
lol same thing happened to me. I going to have to watch that part with my eyes shut or understand what he said through osmosis
This has officially become my favourite channel on UA-cam, keep up the great work!
Questioning one's assumptions. Something more people should do these days.
I believe this is what separates the smart from the genius, in a more general less literal sense of the term
I love how these videos don't pull any punches. they give you the cold hard science unsoftened, sometimes I can't follow and I like that!
You need a T-shirt that just says "Einstein is right, even when he's wrong."
Wrongness is, like everything else, relative
+Stop throwing fridges at me Not everything is relative lol
I was making a joke about relativity. Don't ruin my moment now
+Eric Vilas insert not even wrong pun here
thats not how science works, dont make it into a religion
"I only do Magnum." Haha! This guy is fantastic.
"Einstein is right even when he is wrong" that's our boy Einstein
+nikitha nayaer I don't get how the fuck he got all of his shit right. I mean I literally would be willing to believe anything he told me. If he said the earth is flat I'd say sure if you say so einstein
i think it's because his hard work and effort .He could't even enjoy his family life because of that
Any good scientific theory should predict things that make its originator uncomfortable.
@@alexbatoian5534: Because Einstein used math.
@@deusexaethera Kinda. He was actually terrible at it. His wife worked out most of his math. He was a thought experimenter, and he didn't really get much right if you ask quantum mechanics. But the problem, in my opinion, started with Aristotle. He was wrong about a whole lot of things, like actual infinity, and the forces of chance and luck being quantifiable considerations. If you consider the Big Bang a continuation rather than a beginning, and consider the Universe's composition as being entirely comprised of "sound", or waves of frequency and vibration, it changes almost everything we currently hold true about classical Physics, but gets us closer to understanding why we know absolutely nothing about how quantum mechanics works. I always compare it to being given the paradoxical answer to a logical problem and having to guess at the question.
I just found this channel yesterday and today is a free day for me so i'm just gonna make a playlist of all these videos, get a huge ass bowl of popcorn, get a friend to come over and watch all these videos with me. Holy shit im excited
i zoned out from like 4:54 to 6:24 because of the graphic and had to rewind and watch again.
Exactly what happened to me
I zone out for the entirety of every single episode. I'm not exaggerating at all--god's honest truth.
it happens to me soooo often, I love to be able to rewatch these videos and find something new all over again :)
Each episode I'm literally blown away by the revelations you bring. It's almost like watching a very good sci-fi series..
Silver 1 Yes, I'm currently typing through my severed right hand lol..
TimmacTR That's because it is Sci Fi. Illuminati deception.
It is sci-fi.
It is science fiction but it pays well and provides nice toys to play with like the LHC.
Literally blown away?
Does anyone else enjoy the very last bit of these videos lately almost as much as the rest of the content when Matt either dishes out an epic burn or in this case, reveals to us that he's actually really, really, really, ridiculously good looking?
@@eclipse369. Or to you lol
hi its been 6 years how are you doing
I am Deaf. This looks awesome. Please put captions on :(
+پرنو پی that was rude
+Deaf Keith
hey Deaf, nice to meet you, essentially, if you know of the big bang theory and the expansion stuff, i can crudely explain what this video says.
the universe, as we know it when it was a singularity (so far) was practically flat, we looked at the CMB and using trigonometry have deduced (so far) that the universe is 0.4% flat and can't be curved like a sphere.
we know this because trigonometry on a flat surface when you draw a triangle with straight lines, the angles add up to 180, but when on a sphere, it's more than 180 showing there's extra space being used when opposed to a flat paper, it even adds up to less when using a hyperbolic plane ( 2:00 mark ) so using these observations and applying them to our universe tells us the difference between a triangle on a paper is a 0.4% positive amount more than it should be if it were flat.
the bowling you saw was a basic analogy. saying the universe rolled a slow slow slow bowling ball down the centre of a lane at the speed of light for 1 light year and it only deviated by 0.4%
there's a lot more info, but that is the basics with my rudimentary use of language.
i'm sure youtube will add CC at some point.
+Deaf Keith if the universe didn't start out flat, or had any kind of "not flatness" that would have been amplified during inflation..... our observations tell us..... flat! until we can observe and prove otherwise!
+Deaf Keith
Keith, this thing HAS captions. Just click on cc in the toolbar of the video player.
+Deaf Keith I think it usually takes a few days for them to add the captions. But they do add them. :) lml/
Boy I wish I had continued my science studies because you really lost me in this episode. Trying to work out that cosmological constant equation in my head nearly caused me an aneurism lol. But I absolutely love these educational shows every week and they inspired me to sign up for a 101 cosmology course just to learn. Keep up the good work :)
In many of your videos, you do a great job of crediting and even showing images of the people who made various discoveries and breakthroughs. It's strange then that you haven't even mentioned Alan Guth, the man who gave us inflation. He deserves kudos for his brilliant concept.
"Nice bowling Universe!"
Matt O'Dowd-2016
I would totally buy a "Nice Bowling, Universe" t-shirt
Me too!
I don't doubt his knowledge of cosmology but I wonder if he knows much about bowling.
He says nothing about oil patterns or revs 😁
+ imagine the light year long alley how long a pba tournament would take!
Question your assumptions... Try it, it's fun.
This should be made into a youtube comment section mantra.
Why?
AK636 Don't wanna participate?
I guess I'm not talking to you...
***** Wholeheartedly agree...
+Sean Tripp But why? I don't know anything for sure, tell me ;)
AK636 You're welcome...
Man these are awesome!
Excellent speaker, fitting music, and beautiful presentation!!
I looked at the animation at 5:00 frame by frame and figured out that the zoom factor is at least from Planck length to 0.6 light years, but probably a couple orders of magnitude more, because at the start, there are probably two 9× zooms per frame, it's hard to see. Good job on the accuracy!
Brazil desperately needs a Brazilian-Portuguese version of this channel to combat the fast growing scientific repulsion and willful ignorance the country is drowning itself into. Brazilians learned quick and simplistic challenges to Big Bang, Inflation and other astronomic theories; they attack things they don't even say, nor imply, as a way of self-affirmation. It is like they were taught that those theories are wrong, but they were never taught what those theories are or say.
agreed
Mr Aquiles I would definitely help get the scientific communication community from Brazil, such as podcasts and channels, to start a funding campaign if necessary.
+Lucas Balaminut It's not just Brazil. I live in Turkey , and this country is also mostly anti-science. Most countries are anti-science.
+Lucas Balaminut Você conhece o podcast do Scicast? Tente contato com esse pessoal, eles são muito feras, e possuem uma boa base de ouvintes.
Thales Teixeira eu não só conheço, como tive meus emails lidos no ar vária vezes, participei da gravação de 2 episódios, da pesquisa de vários outros, e ganhei de presente a caneca e a camiseta hahaha. Can we avoid speaking in Portuguese here? I really don't want to scare the English speakers away from the conversations.
This is easily my favourite channel on UA-cam. Keep up the good work.
Please make a "Nice Bowling, Universe!" shirt. I would never take it off.
same, lol
There isn't a single PBS Space Time video I've watched that I actually understood. Yet another one to the list.
"Magnum" made my day!
My college astronomy professor.
+OMJUWARA Don't forget, homework is due tomorrow.
+PBS Space Time Prof. Matt be like Like and Subscribe for Extra Credit!!
+PBS Space Time Sir, got an important question thats bugging me 4 quite some time.. I thought Universe even today is expanding at exponential rates. So whats the difference between inflatory expansion and regular expansion if universe is expanding at exponential rates??..well what can be more faster than such an expansion?
+TheAfroOfDoom There's a short bio on Matt in the "about" section of the channel which includes: "He's now a professor at the City University of New York and an Associate at the American Museum of Natural History's Hayden Planetarium."
+Sachin Raj The coefficient on the exponent (the efolding time) is very different. Now it is like 20 billion years and back at then it was more like 10^-30 sec
This guy is the best
I want a "Nice bowling, Universe!" T-shirt.
I support this!
+Away to Patch~
"Questioning assumptions-try it, it's fun!"
+Away to Patch~ Yes please
Yeah, nice quote material in this one.
"Einstein is right, even when he's wrong."
hi its been 6 years hows everyone doing in 2023. for me its good learning some new things.Have IGCSE OL exam this year in may/june hoping for the best. And good luck on anything your guys doing. Ezran out!!!!!!!!!!!!!!!
2:28 I still haven't figured out that one. The CMB blobs are defined how fast sound waves could have traveled? I can see how the earth angle is measured (but I don't see how it comes to one degree), and I can see how a rough long side is estimated (by red shift), but I can't see how the rest of the trangle is measured.
Flat universe conspiracy? :O
THE GOVERNMENTS LYING ALL THE PICTURES OF ROUND UNIVERSE ARE FAKE #Flatlargescalecosmologicalstructrues
HAHAHA YOU THINK THE GOVERNMENT IS REAL #WatchoutfortheSUPERgovernment
LMAO you guys are fucking stupid xD
+Tobias Ruck I don't buy it. earth is round, but the solar system and galaxy are flat? But dark matter is round but the universe is flat? They're making it up! Timecube!
Phlat
Awesome channel, awesome presenter. Thanks...
I've learned more from this channel than I've actually learned from class...
+Skytivity what sort of class could even teach you 5% of this?
+Prabh Chahal Public school education...
bakuya99 Im a highschool sophomore im double stacking sciences (AP Physics 1 and Space Science) and literally space science has taught me nothing except for that space can kill you
Skytivity That's why i said public school education. I mean this type of science should have been taught to you and me actually. Hell i never learned anything really useful in science class in school. I had to learn evolution and this type of science on my own.
+Skytivity That's very sad. But the fact that you are here with the rest of us says a great deal about you and your scientific curiosity.
In the end, we are all responsible for educating ourselves. Congratulations! You have a great life to look forward to.
thanks to the people that makes this possible! :)
really enjoy watching this while having a break for a meal.
"Is the universe flat? No the universe is actually weird" lol xD
That expanding grid should be a gif. I could watch it for an unhealthy length of time...
Okay, our observable universe appears flat from one end to the other (93 billion light years). However, what if the actual universe is big. REALLY big. So big that, any area of 100 billion light years across might appear flat from horizon to horizon, but, like our Earth, it is actually spherical, only appearing to seem flat when viewed from any given location. Is that possible?
That's a good wisdom.
+Tom Reeves yes
+Tom Reeves It is indeed possible; the video mentions this beginning at 5:47.
Thats why he includes the caveat "it's WITHIN 0.4% of perfect flatness". Meaning that as long as the universe is big enough to curve less then 0.4% over the course of 13 billion light years, then you are correct it could still be curved. Just so you know, that comes out to a minimum size of 25 TRILLION light years.
Now prove it mathematically
A few weeks ago you did a video deciding if Venus or mars were better places to live on. could you do one about Jupiter's moons
Everytime I watch an episode from you I get a bit closer to abandoning my current career path (Life sciences), relearning all the Calculus and Basic Physics I used to be good at 10 years ago and then taking up advanced physics. Maybe I'll just start with taking some classes at one of the universities close to me.
At 8:27, how did expansion slow down if it's speeding up now? Are we just talking about a slowing of the acceleration rate? In which case, expansion is still...actually slowing down overall?
okay i figured this out......your a normal size peter dinklage clone
you're*
*Peter Dinklage, as proper nouns should be capitalized, and ellipses have 3 periods, not 5
How did those 2 replies get any likes
@@snotfeetmossteeth1141 We are on a smart person channel 🤓
how come that this channel doesn't yet have all the subcribers?
What confuses me about this topic is why is the horizon problem such a problem? What about the big bang says that a universe cant start homogeneous in the first place? with out the need for any time to reach equilibrium.
Thanks
I'm wondering exactly the same thing, and I'm surprised noone answered yet.
Just in case you haven't ever had this answered....there is no problem with assuming the universe started out completely homogeneous. The issue is that's just that...an assumption. It offers no explanation for why or how this happened. Inflation provides an answer for how this homogeneity was accomplished, if not why, and scientists are always trying to explain what they see, not just observe it.
Excellent. This is the FIRST time I could understand flatness of the universe. Thank you.
You are by far my favourite UA-cam channel! Keep up the good work!
hi its been 6 years how are you doing
No one in highschool teaches you that you can use simple triangles to learn about structures 46 billion light years away.
Yes, they want us to find it out on our own.
+Kryzia Mae Aranda That's not how you make educated citizens.
+Neceros Sure it is. Instilling people with the wish to find out for themselves is _exactly_ how to generate educated citizens. Problem is, the education system does a piss poor job of that, with most schools teaching rote memorization without coherent purpose.
I didn't discover the joy of science until I was in my 20s, and when I did I was left wondering: "why didn't any of my school teachers turn me on to this?"
Ryan MacFarlane ME TOO. I couldn't find a job after college, so I stayed home and decided to read books + google is a real help. I never loved learning until then. It seems that my hate for teachers translated over to the 'education' I paid for.
Kryzia Mae Aranda Could you imagine where the world would be if a majority of western schools taught people to love learning? What would the world be like if kids _wanted_ to go to school because schools were places which fired their imaginations?
Thanks for sneaking my answer in, even if you chickened out on trying to pronounce my name :-P
Hang on, blackholes have magnetic fields? If nothing can escape the event horizon, how does a magnetic field form outside of a blackhole?
A magnetic field has to be causally connected to the source of the magnetism, but whatever-the-hell-is-inside-the-singularity can't radially affect the outside world. Does blackhole spin matter here? [Does this question even make sense?]
you are right, also another problem is that this accepted science is using inventive science as a tool to use theories to prove other theories as factual ? what happened to scientific method ? I don't trust any scientific claims that refuse to follow scientific method
+Robert Yeahright The ops question is completely valid (and I'm kinda curious too). Your response to it is complete rubish.
Your question is a very good one. There are more details to consider but the following answer works for the classical case. Recall that from the point of view of a stationary observer outside the black hole material never enters the event horizon. This includes charged material which when spinning results in a magnetic field.
+Astronomianova I did not consider that, but that is a really interesting point! After thinking about it for a bit, I did come up with a question about it though:
From our point of view, all the matter freezes as it approaches the event horizon, so if that is where a BH magnetic field comes from then if you sent in a large amount of charge onto just one side of a BH, that should give us an unbalanced magnetic field on one side of the BH, shouldn't it? Since we see the magnetic material all freeze on the one side of the event horizon, we'd see the magnetic field originate from that side instead of the center, which can be a significant distance.
However, if the magnetic field did actually come from the singularity itself then we'd still see the magnetic field centered on the BH as normal. So which one would we actually measure from the outside?
Some charged (or uncharged) matter falling into a black hole would appear flattened as it approached the horizon and in fact would quickly become a layer just above the horizon. So the charge would be evenly distributed on the horizon--as if it were a conductor. This is again from the point of view of a stationary observer. I am not sure about the details for a charged spinning black hole but this is what occurs for a classical description of a Schwarzschild black hole. Also note that even if the charge were not evenly distributed or before it becomes so, the magnetic field would not emanate from the charge but would be closed loops above and around the swirling charge.
He smiles while he explains these stuffs, in fact, there's nothing as pleasurable to explain it.
well done as usual.
its also awesome to not see trolling comments, but so far good conversation.
Nice magnum!
What about entropy? Thermodynamic "end of the universe" means that every region of the universe will have the same properties (pressure, temperature) everywhere.
Does this not make infinite inflation impossible (every part of the 'verse strives after reaching maximum number of possible states, after all = max. enthropy = equilibrium)?
You might be interested in some of Roger Penrose's UA-cam videos. He thinks this death-of-universe equilibrium state could be the same as the pre Big Bang state, not that I completely followed his logic.
Why something like the schwarzschild radius does not apply on the early stages of the universe? Wouldn’t this extreme density create something like a black hole??
+Santy Arcusa it would be a superblackhole actually, but don't question science dogma u heretic.
I feel like there's a lot more comedy and lighthearted jokes (and maybe a little bit of sarcasm?) in this video than in previous ones... I like it!
I finally understand this whole concept of flat Universe. Thank you, thank you, thank you!!!
You're brilliant at explaining these insane ideas.
Part 2'- At 13:40 we are asked to change are thinking on the term "Beginning." My question, why the equivocation on the beginning of the standard model? Do we really want to define the beginning of the universe at the beginning of the Hubble expansion? If so then we are now in the unenviable position of having to change are initial state. Instead of no space, no time, no energy, no matter, no laws, we have space, time, laws of physics, a high-energy false vacuum,etc. That is a lot of EXISTING stuff before the BEGINNING.
Of coarse theoretical physics often proceeds with thought experiments. And they are helpful. However, these same physicists don't always come bring these idea properly back into the real world. Hundreds of thousands of these thought experiments have been falsified when testing the inferences in the real world, why assume these don't need to be tested to be right. Which of the 200+ inferences about multiverse theory are right given that they are untestable.
You have done an awesome job explaining a lot of the space science to people like me, but I am still wait to see if any of this relates to dragons? or is it possible that you might just have an issue with dragons? Or did I just miss that video?
+Opal Dragon Dragons had Godlike powers before the moment of the Big Bang. Hopefully, with the new discover of gravitational waves, we'll soon set up a "gravity map" of the Universe, and we'll no doubt see that dragons started it all.
+Avery McChessney wat
+Opal Dragon A dragon killed his father. He doesn't talk about it much, but it's a real issue with him. I don't expect much from him on that topic in future.
Gareth Dean well the only explanation to that is that his father must of been a knight cause dragons would only chew in self defense!
Opal Dragon
Oh no, the dragon hit him on the interstate, crossed the centerline apparently. Happens to all of us, dragons, humans and possums alike.
Did you say SOUND waves at the 2:30 mark???
I think so. But isn't the speed of sound dependent on the medium? I think he meant to say speed of light, but that's the speed of causality first, and I can't think of a reason why the propagation of a wave would be limited to anything less than that, given an arbitrary medium.
I have no scientific background, but I don't think that sound waves have anything to do with this. I think he meant to say the speed of light.
Sometimes when I take a nap I listen to one of your videos . I dont understand all this but sure can sleep to it .
At 2:23 a distance is described as "how far sound waves could have traveled"... why sound waves? I thought the CMB was microwaves (aka light speed).
I had an epiphany last night, when thinking about this before sleep. Bear with me, this will (probably) be a long post.
You are mentioning that inflation happened in space. Not in spaceTIME. It was never mentioned here, what had inflation to do with actual spacetime curvature. Did it also involve TIME curvature? Or does it only work with space alone?
So does that mean, that time went smoothly while space inflated? How is that possible? Is the time not interconnected with space no matter what? We live in a 4D spacetime after all.
So this train of thought lead me to an idea - if the cosmic inflation also stretches time as fast as it stretches space, it could mean, that before inflation, time was "stopped". There was not enough "time" on the y-axis of the spacetime diagram of Space in that era. The spacetime diagram of Space itself, from that era, was just a point with no available space to move to on the X-axis, also there was no time to do anything, as the Y-axis was also a point.
From the viewpoint of the Space-singularity of the era before inflation, not only space itself was infinitesmall, so was time. So the term "next moment" was not even a possible term, it was not defined. It was not possible for the Space to expand - to move spatially, because of the infinite curvature of space, it was also not possible for the Space to evolve - to progress to the next time interval because of the infinite time curvature.
Is this idea at least marginally correct?
It is sad to see so many amazing questions not answered, you could try asking this question on physics help forum.com and you will get an answer 100%, I would like to know the answer too
What you say here is exactly what is believed. Time started at the big bang/inflation. But the exact beginning is still a mystery
I think you hit the nail on the head, my friend. We know that gravity has a direct bearing on time. Your feet age slightly more slowly than your head. Einstein hypothesized that time would stop incrementing at the speed of light, if this is true, than time must be instantaneous for any light travel. That is, when travelling the speed of light, any distance would be immediately transversed. We have some trouble thinking about this in the correct way, I think. If we observe a pilot launching and travelling at light speed to a distant star, 5 light years away, to us they would essentially vanish. To the traveller it would be a blink and he would be at his destination. To the distant station, it would be five years later than when the traveller left. Time does not speed up for someone travelling at light speed. Less time OCCURS. If you were to take a measurement of the cellular age of the person travelling light speed, their cells will have aged only seconds, not years. This seems to be paradoxical, and it is, but it's also the only reasonable way to make sense of the differing frames of reference, and how they can merely resolve when you arrive at a similar referential spacetime. That also means that in a massively dense black hole, time would increment excruciatingly slow to our frame of reference. One of our seconds might take a million years to elapse in such density. A year could take billions, even trillions of years in our reference of time. Yet our Universe (since the last Bang) is only about 14 Billion years old. In reality, we've already seen that the speed of light represents no real limit. We can observe the farthest remnants of the visible Universe moving away from us FASTER than the speed of light, which seems...impossible. Unless you consider Einstein correct, and that the speed of light also represents our theoretical 0 point with respect to time incrementing forward. That would mean that the Big Bang has already happened infinite times in the time it took me to write this response. We aren't retracting into a singularity in a crunch, we are expanding INTO it. Our 100 years of life and binary intellects make the infinite an impossibility to fully define. I suspect that IN a singularity large enough to swallow the infinite Universe the frame of reference for time would be infinite in much the same way that the speed of light makes the finite instantaneous. And as we accelerate towards it, we'll eventually, if Einstein is correct, be in a reversal of time, though to our frame of reference it would appear no different than moving forward. You ever get the feeling you've done this before and that our past is ahead of us?
All finite things in an infinite Universe are infinite things in a state of perpetual finite change, energy changing state. You are made of 6 billion year old carbon atoms. Are you really you? Or are you just reverberations in an infinite spectrum of waves and frequencies observing other wavelengths and frequencies? in a narrow spectrum and calling it "reality"?
It is not...
@@알렉스박-y2i can you elaborate on that?
I wish this much effort was put into humanity truly coming together to reach the stars. Humans would be unstoppable if we just came together as one.
The US wouldn't have even landed on the moon if it weren't for the competition with Russia during the Cold War.
Could inflation explain also the matter-antimatter asymmetry? Inflation could be for some reason more powerful on antimatter than on matter: in this scenario antimatter could be in the same amount of matter, but outside our universe horizon.
+Beppi Menozzi No. Firstly inflation involves space itself, which should be independent of matter\antimatter. But inflation occurred before matter and antimatter could even out, when energies were high enough to convert particles and thus produce and destroy matter and antimatter.
(Y)
Nope, there's also the theory that there is a bifurcated creation with one half of the matter of the universe being immediately repelled by the other "positive" half thereby causing a binary universe, It's possible. that would explain the lack of antimatter in out universe, and Time would travel in a similar Incrementally forward manner" in the alternate universe.
Aeoster
But ten why is not antimatter repelled when we create it in our universe? That is a curious theory, do you have\ any links to it?
Outside of our horizon is probably the smartest thing anyone has ever said here. The Universe is just really big... bitches. like Really Really big. like really really really really really really really really big. ;)
Is t=0 an asymptote rather than a point? (Similar to the mathematics of trying to divide by zero, or taking the logarithm of zero?)
If you graphed the timeline of the universe on a logarithmic scale, would the universe appear infinitely old? What if actual time ISN'T linear (let alone one dimensional)?
I got a headace from the constant movement of the Grid in the background at 4:54-6:20 and 7:40-8:50.
13:38 "einstein is right, even when he's wrong" 😅
How can a 3D space - the observable universe - have a shape that is "flat" or "curved"? I hear this a lot, but I don't understand how this would work. It seems that when you look out into space you see a 3D field, not curvature.
You should watch the Curved Spacetime playlist. Someone correct me if I'm spouting nonsense, but here goes: if you draw two straight lines that are exactly parallel to eachother, their distance from eachother will stay the same no matter how long the lines are. But if the space where you're drawing is curved, the lines will eventually intersect or separate from eachother.
To give an analogy: you and a friend start walking exactly north from different points on the equator (so parallel to eachother) and you will intersect at the north pole even though you were both walking in a straight line. The surface of the Earth is "flat" in two dimensions, but curved in three dimensions.
snagari but that should only mean that the paths where never truly parallel to begin with. Also, with that explanation you could never observe anything but a flat universe since if the universe was shaped in a weird way, light itself would also follow this weird geometry and thus make the universe appear flat anyways.
True. I don't know what the answer to that is. :)
Imagine you are a very small ant on the top of a sphere. You will think your 2d "universe" is flat but you can still find out that you live on the top of a 3d sphere: draw a triangle, it will have more than 180° as the sum of its angles. If you are an ant on the top of a cylinder, your triangle will always have exactly 180° (->flat). With our universe it's the same situation with the ant and the cylinder, only that our cylinder has 4 dimensions,so the top (our world) has 3 dimensions.
It's hard to imagine, as we're talking about the basic rules of geometry for space.
Of course the universe isn't flat in the 2D sense. We have height, width, and depth. If the universe was flat like paper, we'd just not see one of these three dimensions.
But what if one of these dimensions was warped? What if by travelling forward, you actually also move left a little bit? Imagine if there was no way out of that. Like when you drive down the street -- to you it looks like you're driving in a straight line. But to someone watching from space, you're driving around a giant sphere!
This is actually exactly what inflation suggests. It *looks* like moving forward in space is just going in a straight line. But we think it's just because the universe is a REALLY BIG sphere (or some other curved surface). If you zoomed out far enough it would be just like a car going around the Earth :)
*'Talent Is an Asset'
by Sparks; Lyrics from a truly great 1974 song about Albert Einstein*
''Albert is smart, he's a genius
, Watch Albert putter, an obvious genius, Someday he will reassess the world and he'll still have time for lots of girls.
When he grows up, he'll remember us, When he grows up we are sure that he'll remember us, We made sure that Albert wore his mac, We kept all the strangers off his back.
Everything's relative (Go away Albert's mother said to me), We're Albert's relatives, and he don't need any non-relatives.
Talent is an asset, you've got to understand that, Talent is an asset and little Albert has it, Talent is an asset and Albert surely has it.
One day he'll sever his apron strings, All of the while he'll be scribbling his genius things, Look at Albert isn't he a sight, Growing, growing at the speed of light.
Every things relative, (Go away), Talent is relative (go away), That's hypothetical (go away), We are his relatives (go away),
That's parenthetical (go away), Spare your superlatives (go away), Where's the receptacle (go away), There's the receptacle (go away)
Leave Albert's study room (go away), Leave Albert's happy home (go away), Leave Albert's neighborhood (go away), Leave Albert's city too (go away),
Leave Albert's comfy seat (go away), Leave Albert's country (go away), Leave Albert's continent (go away), Leave Albert's hemisphere (go away)
Leave Albert's planet too (go away), Leave Albert's universe (go away)....!''
Awesome visuals and video editing on the space curvature measurement with CMB
At 5:17 or so, you mentioned that the 'entire observable universe' was so scrunched up that they were all causally connected.
Wouldn't this apply to the whole universe, and not just the observable one? Or are we assuming on the basis of observation that is based only on the observable universe? That is we may hypothesize it is the the case with un-observable universe, but because there are no practical means of measuring that, we can't make a fair judgement.
My mind can't comprehend that the universe is larger than the observable universe. Like, what do we exist in??? What IS the universe? Where are you we?!
+TheJaredtheJaredlong Where are you we?! I really don't get what you're asking.
+TheJaredtheJaredlong The answer is really simple, actually.
In terms of comprehending that there is more universe outside the observable universe...well, it's kinda like trying to view things over the horizon of the earth. You don't know if there even *is* anything there, because you can't see it, but you can reasonably assume there is, because there are things right up to that point. Unfortunately, unlike the Earth, we can't just gain altitude to see more -- or, at least, we don't know how to move in the fourth spatial dimension to do so (if we view the surface of the earth as a flat (2D) plane, we observe the universe as a 3D sphere....and would need an additional spatial dimension to 'gain altitude' as it were and see more. This assumes that this fourth spatial dimension is relational to our 3D space as the 3rd dimension is to our 2D plane).
And as for the "Where are you we" part, my best guess is you are asking 'where in the universe are we'. We can *see* the observable universe, but we can't see beyond the horizon point. We have absolutely, positively no idea where in the 'total' universe we are (and, as of yet, no possible way to find out), nor do we know how big it actually is (again, as of yet, no way to actually find out). Following from that, we know we are in the center of our own observable universe (moving to another galaxy would shift the center of the observable universe to that new location). We know that we are in part of what we presume is a larger universe. And that's about the best we can do.
Knowing all of that, what do we exist in? The universe. We exist on one planet that is a tiny speck when compared to our galaxy is just a tiny mote of dust. Our galaxy that, when compared to the size of the amount of the universe we can actually see, is just a speck of dust itself. And beyond that, we have no idea what portion of the 'total' universe is taken up by the observable universe that we see.
If all of that makes you feel small, good. Because all of us are. Take heart, though, because you and me (and everyone around us) is actually made up of the same matter that went into creating the entirety of, at least, the observable universe. We are made of the universe, and are as much a part of the universe as is every star in the sky and every planet around every one of those stars.
Also, if you read everything in this post up until this point, congratulations. You're worthy of the matter that makes you up. May the universe be with you. :D
Edited because....why is it that no matter what you do, there's always at least one comma in the wrong place?
+TheJaredtheJaredlong
"Space is big. Really big. You just won't believe how vastly, hugely,
mind-bogglingly big it is. I mean, you may think it's a long way down
the road to the chemist, but that's just peanuts to space."
-- Douglas Adams
+TheJaredtheJaredlong
the universe is just more of the same stuff as the observable universe, with the exception, that light of those parts hasn't reached us yet (and due to expansion probably never will), so that we can't observe it. It's pretty much like watching the water if you are in a boat on the ocean. You can just see a small part of the ocean, but the rest is (on average) more or less exactly the same, just a lot more of it which you just can't see, because it's so big..
But if inflation didn't start, then when did the universe have time to interact with other parts that now aren't causally connected? If inflation expanded space faster than the speed of light, then nothing could interact with other parts of the universe.
+Ciroluiro It seems like more to the point, everywhere in the universe was everywhere else also at the big bang. Everything in the Universe was all one big point which radically expanded.
+Ciroluiro Consider a tiny piece of an inflating space -- so small that, for the moment, it *is* causally connected. Now let it slow down to normal Hubble expansion; as it slows down, it's still inflating, so it becomes causally disconnected.
+Ciroluiro Big Bang and inflation didnt expand space, they created space.
***** When was that moment if it was always expanding? Even if they are close, if the expansion is faster than light, the photons wouldn't be able to get anywhere.
thunda Interesting. But isn't expanding space basically creating space?
That face was totally Le Tigre, not Magnum.
this channel really helped me on astronomy and cosmology. I really want to be an astrophysics so it can be my whole carear!!!
+pbsspacetime
Love your videos!!
Is there any present theories on what actually caused the phase transition from 'inflationary' to 'Hubble expansion'?
Cheers
Those graphics doe....
"Einstein is right... even when he is wrong" amazing man this Einstein.
Actually he was right when he admitted he was wrong. Today's scientists who believe his error wasn't an error are not in the same class as Einstein
4 pi G? Not 8 pi G?
Small mistakes
8:33, what do you mean by regular expansion? Isn't the expansion of the universe accelerating now aswell?
Can you do a video on the cyclic model of the universe (e.g. Penrose's theory) as an alternative to the inflationary model? As of now, I'm not entirely sure how seriously I have to take this alternative.
Einstein is right, even when he's wrong :)
"Questioning your assumptions. Try it; it's fun!" But once you start, you can't stop. And when you start questioning literally everything, you begin to exist in a perpetual state of mindfuck, truly understanding nothing and everything simultaneously. Everything, even your own understanding of life and the universe, begins to exist in this quasi-state of reality, where even reality itself is just an assumption which may or may not be real. Yet, if reality itself is not real, then the word "real" has lost all meaning, so perhaps the true invalid assumption is in our limited understanding of assumptions. Perhaps the most incorrect assumption we can make is one that causes us to avoid making assumptions. Or maybe I just enjoy screwing with the minds of fellow smart youtube people.
+Acid It's best if we don't know everything. It gives us something to 'think' about. Once everything is learnt, there is no longer a reason or need to actually think at all.
Not to cause an existential crisis, but both of your comments seem to be communicating the same idea: knowledge is one of, if not the only, fundamental reasons for existence. Or at least, one of the fundamental reasons to desire/enjoy existence. Which makes sense, I suppose, since there is certainly an innate satisfaction gained in learning new things and in understanding things completely. Not sure what that has to do with anything, just thought it interesting that you both said basically the same thing in that regard.
Joe Stanley I was gonna up vote your comment but then I read the last line
those cubes in the background were so distracting.
Around 2:25 the host talks about sound waves. But why does it matter how long it takes sound waves to travel that distance?
this has to be the best channel on youtube :-)
I almost died when he said "nice bowling universe" haha
OMG i want that nasa shirt
nice shirt
When we talk about the eaerly iniverse being small, 6:31 "You could hold in your hand" I get confused. I thought that a flat universe implies an infanite size (just with parts that are outside of causial relationships because it's expanding faster than even light can catch up). Are we just saying that the OBSERVABLE universe was condensed to hand-sized? What does that mean about the parts of the universe beyond what we can observe?
why should the angle on our side be equal to one? Does it depend on which points you pick?? or will it always be 1°?
What stopped inflation? Or, to rephrase, why did inflation stop when it did? Why didn't it continue until quarks were as far apart as galaxies are today?
+breotan cheese
+Ivo Domani - Wait, what? What does the moon have to do with this? :P
+breotan after stoping the inflation, the Moon settled here to protect us forever. Amen
Suddenly it all makes sense.
:D
This video makes me feel both so smart and so dumb at the same time. I hope you dont judge me if all I take away from this is that the universe is a dam fine bowler.
I guess Einstein can't be wrong even if he wants to be wrong.
+Jason Tesch Mathematics are the absolute truth. If Einstein's mathematical models are right, it is impossible for him to be wrong. This is why Einstein will never be disproved, his math is firm.
Maybe Einstein is always right because he observed the mechanics of the universe and collapsed the wave function (of infinite equation possibilities) around the math that he predicted. The actual act of Einstein conceptualizing the universe (with his math) forced the universe down that path. He "predicted" the Schrodinger's box equation and saw that the cat was dead before opening it, now every time we try to look in the same box we see the same thing he saw- a dead cat. The reality is that he never predicted the outcome -he just collapsed the available universes down to accommodate his observed equation.
That, or he's just really good at math...
***** A theory still has scientific basis and is widely accepted. A theory is pretty much a law in science. You're probably thinking about a hypothesis, which is a complete guess.
Okay, I have a question. And forgive me if it is a stupid one, it is 1:30am here currently. So if the universe IS actually flat, and it would take (if you could pause time) 92 billion years travelling at c to "drive" across the entire observable universe...what would happen if instead of driving around the x and y coordinates of the observable universe (so to speak) we simply drove...up??? Would we reach the "edge" of the universe faster than if we were travelling outward along the "flat" observable universe? Aha, be gentle with your response, I think I am missing something simple, but I am curious! :)
+High-Density-Awesome you are imagining it wrong. The universe is not flat in terms as "flat as a paper".
What was said here, is that 4D spacetime is mostly flat. When you go "up" you still move in one of the 3 dimensions. You would have to move somehow in the fifth dimension to get to the edge faster, I even think, that an entity living in 5th dimension would be on the edge of the universe in no time, if it wishes to do so, if that makes any sense.
Also, what does "up" mean? My "up" is different from your "up", we live on a planet, not on a sheet of paper.
Hey Matt ever consider doing an episode about wormholes and their possiible use for interstellar or intergalactic travel or even time travel? Hope to see one in the near future.
+Ron Corless There's very little true scientific research involved there, I'm afraid. That's pretty much purely the realm of Science Fiction, because we have no way to test or observe any such concepts, even at an extremely abstract level.