Can The Crisis in Cosmology Be SOLVED With Cosmic Voids?

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Two of the greatest mysteries in cosmology are the nature of dark energy and the apparent conflict in our measurements of the expansion rate of the early versus the modern universe that even dark energy can’t account for. Could both of these be explained by looking to a part of the universe that we’ve largely ignored so far? Could cosmic voids be driving the universe?
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Written by Matt O'Dowd
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Spacetime is produced by Kornhaber Brown for PBS Digital Studios.
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[@flashrandom]

I cannot believe how much time and expertise is requested to create videos like this, that are simultaneously simple and detailed. Just a huge thank, and congratulations.

[@livinlicious]

Well, to be fair, these videos are summarized, but not simple. I know most people in my surrounding would not really understand 5% of most videos.

[@slyy4096]

Just need to pay for marketing. And buy comments like this

[@silviavalentine3812]

​​@@slyy4096 that's for channels that have exploded out of nowhere. PBS Spacetime has been doing episodes for almost a decade. And even before that, their predecessor PBS NOVA has been around since the early 2000s. Also I realized you may not be american so I'll give you a little background info. PBS (public broadcasting service) is a government service with the aims at educating the youth through television. It's been around since the 1970's and since then has developed a lot of different programs and shows.

[@br.m]

@@livinlicious When he said 69 I laughed like Beavis and Butthead. It's not something I am proud of but I'm not afraid to admit it.

[@turtlereptile]

The PBS Spacetime/Dr Becky cinematic universe is for sure the most meta cinematic universe. More crossover events!

[@unluckypants6459]

Idk why but I appreciated the Dr Becky shout out!😂

[@NimbleBard48]

Does Dr Becky shoutout PBS Space Time? I don't watch her videos as often as I should have so I either didn't notice or forgot if there were some shoutouts.

[@wild360]

Dr. Becky looks taken off guard in the thumbnails used in this video. 😂

[@annrobinette]

@@unluckypants6459 @turtlereptile yoooo I watch doctor becky all the time and PBS space Matt, the other one that’s top tier is “SEA” and “astrum”

[@greyed]

@@unluckypants6459 We got two! \o/

[@concrete_dog]

That animation at 11:40 is so amazing. Just the idea of cosmic bubbles breaks my mind.

[@kindlin]

I watched that a couple times, then tried to imagine what it actually looked like in 3D.

[@brianDude66613]

it always trips me out how much they look like neural networks in the brain.

[@kindlin]

@@PGP-zi2un The hypocrisy is mind-boggling.

[@concrete_dog]

@@PGP-zi2un what

[@DezzieYT]

Unrelated to the episode but I just love hearing how the channel's catch-phrase gets worked into the end of each. Just brings a smile to my face. 😊

[@michaeljames5936]

To be fair, it takes a special type of person, who arrives fresh-faced and keen at university, with a burning desire to turn his telescope away from all the good stuff, and study the empty bits.

[@trevorlang6895]

Always find it fascinating how our little star system is in a little bubble of unusually empty space, off a minor arm filament, in a small galaxy cluster, part of a relatively small super cluster, in the centre of a massive void bubble. We're really out in the boonies

[@edit4310]

Yeah, cool sad and spooky at the same time. Makes you think if life can form 'here' then SURELY it must be abundant in the universe? But then you look at the chances of our existence in the first place and it makes everything that much more magnificent. Maybe the solution to the Fermi Paradox is that we are in our own little corner.

[@captaineinsicht264]

We dont know if the universe is in a "massive void bubble" or if it just goes on infinetly

[@yallimsorry5983]

@@captaineinsicht264they’re talking about our local area of the universe

[@edibleapeman2]

Makes you wonder what life’s true goldilocks zone is. What if life can only form in the nucleus of a void bubble, in a star system on a galactic arm, around a star (or gas giant) where liquid water already exists?

[@fetmar]

🤨 Just a bunch of dirty monkeys on a rotten rock circling a no good star. *end neo noir sci fi soliloquy* 😂

[@rachel_rexxx]

This is easily my favorite KZbin channel

[@BytebroUK]

Just butting in to say that I _love_ that you are now citing Dr Becky's vids - she does really good stuff - always worth a watch, and splendidly accessible. The bloopers normally seem to indicate how much caffeine Dr B had or had not taken :)

[@Kyzyl_Tuva]

Dr Becky is awesome!!!

[@stefanfyhn4668]

He has cited Becky and Anton many times

[@Merrexz]

Speaking as a layman, this is the most sensible proposition I’ve seen to explain (away) dark energy yet. Really, really neat - I am looking forward to following the development of this hypothesis.

[@ElectricalExistence]

this is just a desperate attempt to keep their BS tax dollar stealing scam going.

[@dl5244]

and I love it when hypothesis and research that contradict the "consensus" and "the $CIENCE" are discussed openly

[@Ligeia_Swann]

It's often a good sign when you see same mechanics at different scales : like the link between blackhole and whirlpools. It might be the case also for bubbles of water and cosmic void, but to be believable it should really be more thoroughly checked Thanks for the amazing vid for new year!!

[@JonathanScarlet]

I tend to imagine whirlpools as black holes myself, so I'm glad I'm not wrong on that association.

[@CrimsonTemplar2]

I love it when Dr. Becky gets a shout-out.

[@proton8689]

The hypothesis is that dark energy could just be a product of the voids is so amazing simple yet feels so obvious that I unironically want it to be true. It feels like the least outlandish or sci-fi solution, the Occam's razor.

[@livinlicious]

It definitely is more straight forward than inventing new energies for which we have no explanation. To this day we literally call it dark energy because we have 0 idea what it is. We know what it is supposed to do. We don't know how it does that. By what mechanism. Why it exists. How it will develop over time or developed over time. We have no idea. It's one of the dirtiest ideas in cosmology and still it's the only one we came up with. That should be way more shocking than it is. Yet it's treated as if it's just the way it is. Calling a cat a dog, doesn't make it a dog. It's just a cat and you are stupid.

[@bpz8175]

Until you take into account that we already (and still, even assuming the void hypothesis is correct) need exponential expansion of an unknown source to explain the era of cosmic inflation. If anything, it becomes even more outlandish (albeit not more sci-fi) since the voids would have to account for the majority of all "energy" in the universe and disproportionately even more so in the early universe to counteract the density. And not only has this finding been contradicted, but the paper itself is almost entirely based on fluid dynamics with little justification for why an underdense region would even have a surface pressure in the first place. It smells like MOND, simple and attractive idea that fails closer examination. That one was also a favorite because it wasn't outlandish and sci-fi.

[@geoffbrom7844]

@bpz8175 @proton8696 I had the exact same thoughts, could gravity really be strong enough expand space 10^78 times in 10^-32 seconds?

[@johnmcmahon5162]

Agree there’s an appealing elegance to this proposal. Hope it stands up to scrutiny.

[@BainesMkII]

I vaguely remember Sabine Hossenfelder doing a video some time back where she mentioned the argument for Dark Energy had been built on the assumption that the universe was uniform at a scale that we'd long known wasn't actually true.

[@carnsoaks1]

As a science daydreamer I always wondered about the baselines of Time and Space in a region devoid of galaxies and the clusters. I thought it must be fascinating how the Universe acts when its empty of everything apart from light and neutrinos.

[@greensteve9307]

I love that you linked Dr Becky! I have been following you both for years. Great to see cooperation not competition.

[@Breakemoff2]

Dear whoever edits/does music for these, PLEASE make the outro quieter! I love listening to these before bed and the last 15 seconds is so much louder than the enter episode. THANK YOU! Sincerely, An overworked mom who just wants to peacefully learn and fall asleep to science

[@hektor6766]

I speculated on this in a comment on an earlier episode of Space Time, calling for the observation across a void in comparison to along a cluster. But I didn't know we were smack dab in the middle of such a (relative, perhaps) void.

[@epgui]

Wow, I knew Dr Becky was awesome, but this is a big endorsement! =D

[@cashewABCD]

Impressive, every episode uncovers more ideas, more concepts. Exciting times deciding the nature of REALITY. :)

[@christopherkopperman8108]

Love this video. This theory feels like something. We've all had the sense of hearing something and it feels substantive. That is what this is. Dark energy, dark matter, multiverse, etc. They all feel like artifacts in equations simply to make them work until we know what is really going on. They have never felt like a glimpse at reality.

[@edibleapeman2]

Galactic superclusters are just the rims of cosmic void bubbles. Got it. Thanks for the mindscrew today.

[@COSMOPHILE_1729]

Nahhh man!! Im really lookin forward to watch more on this cosmological problem stuffs! This supercluster research might be a checkpoint for something even bigger

[@annrobinette]

PBS space time with Matt (this channel) (dr.Becky), (astrum)and (SEA )Are the best astrophysics video and Becky is an astrophysicist!!

[@atlantisvelforening]

Why / how can such bubbles, such cosmic voids, expand space itself, instead of just pushing into each other?

[@nickhowatson4745]

well, the expansion of spacetime is an intrinsic expansion and not geometric. The "expansion" of spacetime is simply the increase in the scale of the spatial part of the universe's spacetime metric tensor which governs the size and geometry of spacetime itself.

[@nickhowatson4745]

also remember that gravitationally bound structures have "dropped out" of the expansion and no longer effected by it. it is only the vast empty space (voids) in between these structures thats expanding.

[@atlantisvelforening]

@@nickhowatson4745 Thanks a lot for the explanation 😊

[@nickhowatson4745]

​@@atlantisvelforening Also the concentration of Dark Energy remains constant and doesn't dilute as spacetime expands unlike the behavior of anything else in the universe which becomes more diluted the more spread out it becomes or the more spacetime expands.

[@rcourtri2]

This episode raises some interesting questions about how much can we really know about the distribution of matter in the universe, given multiple observational problems: (1) The Zone of Galactic Obscuration (We can't see parts of the universe due to gas and dust within the Milky Way, rendering some dim, distant objects undetectable); (2) Our methods of estimating distances get less reliable with distance--We ain't measuring, we're guessing, and the reliability of measures of distance, volume, and density becomes highly questionable beyond the Virgo Supercluster; (3) The limited value of CMB observations. We're sometimes pretending that the CMB gives us a "picture" of the very early universe, but about all that we can glean from CMB observation is that the distribution of matter and the temperature of the universe was once highly uniform.

[@rcourtri2]

@@nadsenoj8719 Would "informed estimates with very significant margins of error" be better terminology? Assuming that triangulation from parallax is a measurement, our upper limit of measurement is only about 400 light years. Other methods (generally involving some standard-candle type estimates or, for very distant galaxies, calculations involving redshift and the Hubble-Lemaitre Law) are not measurements but a kind of educated guesswork, and different methods will produce different estimates. Those differences are significant at intergalactic distances, enough to alter our thinking about the rate of expansion in the universe and the nature and strength of dark energy.

[@jasonrubik]

For issue #1, just wait half of a galactic year

[@rebeccamaracle2878]

Love the Dr. Becky shoutouts... she's awesome!

[@jacksonstarky8288]

This is a very interesting hypothesis, and as someone over 50, I hope I live to see the crisis in cosmology resolved... and the Riemann Hypothesis proven. 🙂

[@DavidFrostbite]

I love the bubble analogy for dark energy! It already sounds like a fun fact in some future textbook.

[@Kyzyl_Tuva]

Fantastic video!! Very helpful.

[@sheepwshotguns42]

wow, a channel with 3 million+ subs that doesn't make me lose faith in humanity.

[@mho...]

well it took them a long time to accumulate these numbers.... no viral videos here, just science fans!

[@tomorowsnobodys]

PBS rules

[@sheepwshotguns42]

@@tomorowsnobodys im telling you, this is a public service and a half

[@fremtidenkommer]

If spacetime is quantum foamy, could "bubbles" at a quantum scale give rise to dark energy?

[@nickhowatson4745]

if spacetime was "foamy" it should be measurable as it would cause excess scattering of photons at X-ray and Gamma Ray energies but so far all experiments and observations looking for the effect have failed to find any. these results confidently rule out a "foamy" spacetime. Spacetime appears to be completely smooth all the way down to the Planck Length.

[@OpenMicRejects]

Perfect title to fill the Spacetime void experienced through the holidays!

[@flatline8580]

Thanks, Matt.

[@jimmyzhao2673]

1:50 I love hearing how even one of Einstein's 'blunders' is worthy of a Nobel Prize.

[@YandiBanyu]

Can't wait to see the next video on this topic!

[@mpart_woodlathe-stuff]

Wow, the Laniakea supercluster at depicted at 6:30 reminds me of the human brain's limbic system. (FWIW, I was trained in that stuff once upon a time).

[@UsernameXOXO]

It also looks like some metallic chemical reactions, or certain fungal growths. I'm assuming it's just a very common naturally occurring fiber/filament arrangement.

[@dark808bb8]

I love the idea of cosmic voids as bubbles. Makes perfect sense

[@Jar.in.a.Bottle]

Aren't Femi Bubble expansions fairly much the same thing as Cosmic Void expansions, just on smaller scales for Fermi Bubbles? If so, then the two would surely be combining local and non-local forces to re-enforce the same type of overall Dark Energy like effect. I'm sure this has already been accounted for if there was a need to do so, thought I'd ask anyway. Thanks Matt.

[@Breakemoff2]

Can you lower the volume on the outro? I love listening to these before bed and the outro always gives me a jump scare. 🤞🤞🤞

[@crawkn]

"It's not silly to wonder about this stuff" should be the physicist's mantra.

[@tomkaneko6359]

I’ve been pondering this idea independently for awhile myself. I really think there is something in it. Also in reference to your previous video about “negative mass”, I wondered if within these cosmic bubbles/voids, gravitational waves from retreating galaxies might sum to create virtual “negative mass” in its centres. Thereby expanding space further (for a while, not indefinitely).

[@SebastianKrabs]

The only Cosmic Voids I know of are the ones in my life when PBS Space Time doesn't upload.

[@tylerjmast]

Wow that's very compelling on an intuitive level. The surface tension/negative pressure bit.

[@TheLacedaemonian300]

I like this cosmic void explanation. It makes sense. I think they're onto something.

[@jacks3042]

I just get so excited when I know Matt's wrapping up and he's about to say SPACETIME but he did a pump fake on me this time and it threw me off, he wasnt quite done. Brilliant stuff Matt. Keeping us on our toes

[@Chill_Mode_JD]

Woo hoo it’s space timeeeeeeeee

[@Lukesab3r]

Another awesome episode!!

[@geoffbrom7844]

Inflation just caused by being in a cosmic void is fascinating but how does it explain the early hyper inflation?

[@garethdean6382]

It can't; the two phenomena are on massively different scales. Like trying to use rain to explain a tidal wave.

[@gmork1090]

An endless cycle of universes being born within universes. Likely at the end of certain comically giant black holes expansion and evaporating cycle. As they grow they pull other pocket universes apart. So much speculation, it could be just about anything since the math checks out on many of these hypotheses in spite of them being impossible in actual physics.

[@mohitsoni3275]

Thanks for taking us through thought provoking journeys in such eloquently presented videos.

[@TheGuyCalledX]

Sabine brought up papers on this years ago on her channel, and it's very convincing imo. The assumption that we are in an average part of the universe simply isn't true. The universe has structures much larger than we originally thought, and that is affecting our measurements when trying to determine the cosmological expansion constant.

[@Dragrath1]

Yep this approach can even naturally explain why they consistently get the answer they do and it all comes down to the mistake of implicitly assuming a model in data analysis as in general the distance redshift relationship is only exactly true if the cosmological principal is valid as otherwise asymmetries in the distribution of matter and other forms of energy mean that the rate of expansion is locally going to vary thus becoming a second independent variable along with distance which effects the observed cosmological redshift. Lambda CDM gets rid of this term by using the cosmological principal to set it to zero everywhere which means that they will attribute all such redshift to distance alone. However as a consequence the measured Hubble rate becomes dependent on what data they use ergo you get something similar to the Hubble tension because they have forcefully constrained a dependent variable everywhere to simplify the math.

[@TheShawnMower]

Always question our assumptions! Exciting

[@jdhenge]

I wonder if even the observable universe isn't average. Might we be an ultra low density region being gravitationally attracted to very dense regions beyond the cosmological event horizon. If this were the case we may not even live within an open universe. Or perhaps certain regions of the universe are open, and other regions are closed

[@shasan2393]

Any link or keyword i can search to find that specific video?

[@allanburns1190]

Let’s goooooo new video

[@PhilipMurphy8Extra]

Happy 2024 PBS Space Time, Science is always interesting

[@agr.9410]

Great video as always! Would modeling the fractal geometry of Laniakea help us refine our cosmic distance ladder models? (Like measuring the fractal dimension of Laniakea, for example.) I'm no astrophysicist, but I can't help but wonder how an approach where we model the "roughness" of the universe could change how we think about cosmology.

[@chemiczny_bogdan3467]

Exactly, if the Hubble constant isn't all that constant, that has enormous implications for our understanding of the universe at a range of length scales.

[@vladimirrogozhin7797]

Many thanks! A very important topic for deep open global brainstorming. I recall Bertrand Russell's philosophical thought: “What people really want is not knowledge, but confidence.” Complete uncertainty in the basics of knowledge: The "Big Bang"... the "singularity".. . "inflation"... "collapse"... "multiverse"... "dark matter"... "antimatter"... "dark energy"...."local hole"..."empty bubbles"... Fundamental science has "rested" on the understanding of space and matter (ontological structure), the nature of "laws of nature", the nature of "fundamental constants", the nature of phenomena of time, information, consciousness. It's time to realize that quantum theory and general relativity are phenomenological (parametric, operationalist. "effective") theories without ontological justification (ontological basification). John A. Wheeler, “unsung model of science”: "We are no longer satisfied with understanding only particles, force fields, geometry, or even time and space. Today we require physics to have some understanding of existence itself." To understand EXISTENCE itself means to "grasp" (understand) the nature of the primordial TENSION of the Cosmos, to understand the nature of space and time. And for this it is necessary to "grasp" the original generative structure of matter - "La Structure Mère" (ontological SuperStructure). That is, to build a model of the metaphysical triad "being-nothing/otherbeing-becoming". The paradigm of the Universe as an eternal holistic generating process ("PARADIGM OF UNDERSTANDING") gives a new look at matter. MATTER is that from which all meanings, forms and structures are born. Space is an ideal entity, an ideal limit for the states of matter. The ontological structure of space (absolute, ontological, existential) is rigidly connected with the absolute forms of the existence of matter (absolute states). And there are three and only three of these states: absolute rest (linear state, absolute Continuum, ideal image, form - "cube", "Cartesian box") + absolute movement (vortex, cyclic, absolute Discretuum, ideal image, form - "sphere") and their synthesis - absolute becoming (wave, absolute wave, absolute Dis-Continuum, ideal image, form - "cylinder"). What is especially important: each absolute form of the existence of matter has its own ONTOLOGICAL PATH (bivector of the absolute state). Accordingly, SPACE (absolute, ontological, existential) has three ontological dimensions / 9 gnoseological dimensions. But we must "dig" deeper into ontology in order to “grasp” the MetaNoumenon - ONTOLOGICAL (structural, cosmic) MEMORY, “soul of matter”, its measure. Ontological (structural, cosmic) memory is that "NOTHING" that holds, preserves, develops and directs matter (enteleschia, nous, Aristotle's "mind-prime mover"). To understand SPACE and TIME we must move from the physicalist concept, the simple ideality of “SPACE-TIME” to the ontological concept of “SPACE-MATTER/MEMORY-TIME”. That is, to generating processes with memory. More than a quarter of a century ago, the mathematician and philosopher Vasily Nalimov set the super-task of building a "super-unified field theory that describes both physical and semantic manifestations of the World" - the creation of a model of the "Self" -Aware Universe" (V. Nalimov, 1996). In the same direction, the ideas of the Nobel laureate in physics Brian Josephson (which are not very noticed by mainstream science), set out in the essay "On the Fundamentality of Meaning" (2018). Brian Josephson: “Physicists' immersion in search of their 'theories of everything' has led them to an oversimplified picture of the natural world. To a picture that can work very well in situations used to test physical theories. But this picture is completely incapable of clarifying and helping to deal with such problems as observation, the meaning of the observed and the processes of thought.” Fundamental science requires a Big Ontological Revolution in the metaphysical / ontological basis. Physics must move from the stage "Phenomenological physics" to the stage "Ontological physics". The paradigm of the Universe as a WHOLE must come to the aid of the “part paradigm” that dominates science. The New Information Revolution is also pushing for this. J.A. Wheeler: "To my mind there must be, at the bottom of it all, not an equation, but an utterly simple idea. And to me that idea, when we discover it, will be so compelling, so inevitable, that we will say to one another, 'Oh, how beautiful.' How could it have been otherwise?'". Pierre Teilhard de Chardin: "The true physics is that which will, one day, achieve the inclusion of man in his wholeness in a coherent picture of the world." A.N. Whitehead: "A precise language must await a completed metaphysical knowledge."

[@alexandruoprica3953]

It feels like you can always be roughly at the center of a void if you allow for going as far out as you need to to find the outer surface of that void, even if locally you seem to be on one of these filaments of structure. This makes this explanation of always seeing this outward pull/negative pressure no matter where you are, intuitive. But the Huble constant you observe would fluctuate depending on where you are in the universe

[@padders1068]

Great work Sir! Thanks for sharing even if my brain is struggling to absorb these concepts! 🙂😎🤓

[@toosas]

I love this explanation, lets see if we can prove it! much better than some unexplained undetectable energy

[@gabewrsewell]

agreed! this would be fantastic, i’ve always imagined in 50 years dark matter and dark energy will be this embarrassing phase in cosmology history, like a phase you went through in high school

[@SlipperyTeeth]

Unless I misunderstood the explanation, it's still about energy isn't it? It's the energy of spacetime that induces the negative pressure of voids.

[@shipwreck9146]

@@gabewrsewell I think it'll turn out that dark matter is actually a form of matter that only interacts gravitationally. There's a lot of evidence to support its existence. But dark energy just doesn't seem correct. The only evidence for its existence is "universal expansion is accelerating," but that could have such a huge range of possible explanations, I think it's wrong to even give it a name at this point. Until we know the solution, we should name it "The universal acceleration problem."

[@DefnitelyNotFred]

​@@gabewrsewellyeah, it always seemed to me to be our time with the "Ether" stick. We don't know, we just give it a name and pretend we do

[@toosas]

@@SlipperyTeeth yes but the important thing is we can account for it and understand the origin of it while currently it's just a mystery what this dark energy is and why it exists

[@steve9007]

Wow my mind was just blown away by that theory. This could explain a lot. Those animations were great too.

[@arrowinmygluteusmaximus]

Few questions: Isn't the current assumption that the majority of the energy of the universe is dark energy? How could the relativly small amount of matter (or more specifically the attraction between it) cause such a discrepancy. To me it feels like; we calculated that there's an invisible ocean hiding somewhere. And then later going, we found it; the missing water was in that glass in kitchen. Second question: Don't we need dark energy for the initial inflation of the universe?

[@garethdean6382]

The issue with the first question is that the *effect* of something isn't always in proportion to its content.For example, if I find a spring in a desert, then the water must come from somewhere. IF the whole desert is sand then there must be a massive water table beneath it, an underground ocean. If I later find that the desert is largely over solid rock and the spring over a fissure, then the amount of water needed goes from an ocean to trickle. Dark energy's expansive effect would be a small side effect of a vast thing. A comparatively small effect may require space itself to have energy. But because it's so subtle this also means that a massive >50% of the universe thing is not the only explanation. The same is (or was) true of dark matter vs MOND; a subtle effect requiring either a pentupling of the matter in the universe or a small tweak to gravity. (Unfortunately small tweaks seem to not be enough in THAT case.) Inflation is possibly a related property to dark energy; space being in a 'false vacuum' of high energy and expanding.However the energy density involved is so high that it doesn't say much about the strength of dark energy in our universe. The physics at that time didn't even allow photons to exist and the changes from then to now were drastic. As such we don't know that we need current dark energy for inflation. There may be some deep connection somewhere we'll stumble upon, or the two might be totally unrelated. At present inflation is hypothesized, something is needed to explain how our universe looks, but we don't actually know what it *is*, what fields and effects might be responsible.

[@tetronym4549]

The way I understood it was that we originally calculated a huge ocean, only to find that there's no water in it other than the surface/the waves.

[@Pauly421]

Wow the 3d animation is on point guys! Loved the zooming down to the dirt from space.

[@tru7hhimself]

have people considered not only bumpyness on larger scales, but also on smaller scales? could the discrepancy between the observed and calculated values for vacuum energy be explained by a sort of bumpiness of space at very small distances and the energy being distributed along fractal surfaces? iirc CDT and asymptotic safety (have we have videos of those already?) propose a fractal nature of spacetime.

[@EarlLarrabee]

The time field theory explanation for this states that the behavior of time itself changes dependent on scale...the fine structure constant literally defines the upper boundaries of the 4 time fields and gives you a unitless number at the end. If gravity is nothing more than time dilation dependent on mass (which is 97.5 contained energy bound together by the 3 universal forces) than the interaction of gravity and space itself (which is the chaotic time field existing in between plan units...wouldn't mass itself create time dilation that we measure as inconstant expansion rates of the universe? How else can vacuum energy be so powerful and yet the cosmological constant lamba be off by a factor of 1x10^122?

[@ChrissiX]

Thank you so much for this channel. I wouldn't even hazard a guess out how much of this I actually understand. But, you still don't seem to dumb things down. Perfect!

[@ChrissiX]

By "you" I mean everyone involved. I want to give credit to the whole team .

[@talideon]

Surely people have realised by now that both dark energy and the expansion rate is the universe can be figured out by discovering where all those missing socks end up?

[@deathwarmedover]

Quantum Sock Theory is invariably linked to Missing Lid in Washing Machine Field Effects.

[@TheWoblinGoblin]

give this man a Mobel prize!

[@waddakno9644]

Bro… everyone knows aliens steal them in your sleep! Like cats, they loveee the smell of feets 👀

[@Ilix42]

Follow the money; check all the second hand sock stores.

[@NovaRedBaron]

The missing socks eventually re-pair and clump together to form dark matter thus helping to slow down the expansion of the universe.

[@nickbowd]

The study of the absence of things is so fascinating.

[@vaterchenfrost7481]

Thank you for pointing out several possible general biases in measurements. It is a very interesting topic in itself. One further example of such a possible bias is the interpretation of the universe's age. If one calculates the speed of a universe's expansion on its observable edges, it is near the speed of light. So we should not be able to observe anything farther from the past than what's considered to be the age of the universe, even if it were out there. So if we make our estimate about the age around what we observe on the edges, we might be wrong because we are simply unable to see anything older because it is moving away from us with its surrounding space at a pace faster than the speed of light.

[@nickgardner6340]

7:50 nice

[@paulcooper8818]

I've never been a fan of Dark Energy so this Cosmic Voids solution appeals to my gut instinct. I remember sometime back that a team was starting a new survey to eliminate a bias they believed gave the false impression of DE.

[@Malins2000]

All the best wishes for a New Year for PBS Space Time Team! :D

[@snowdogs5432]

"Assume a spherical universe of uniform mass and density..." and suddenly this joke from old school years is incredibly relevant to our model of the universe!

[@denizkacan8007]

I knew it would be a problem! lol

[@thelittlehooer]

At 7:54 I appreciated your restraint in not saying nice.

[@garypalmer997]

If dark energy dissolves, would that allow the universe to collapse on itself, or would all the matter be too far apart b that time for it to happen

[@garethdean6382]

Currently it seems the universe doesn't have enough matter density to trigger a 'big crunch'.

[@DeepeningTheListening]

@@garethdean6382 Only if you assume that dark energy is constant over time. If it dissolves, there can be a big crunch.

[@denizkacan8007]

Probably will depend on at what stage of the universe the dark energy will dissolve.

[@garethdean6382]

Well not quite, the universe is still expanding even without dark energy. What's required is for it to start collapsing, which require a certain minimum density of mass. That's why the big crunch wasn't certain even before the 90s, when we discovered dark energy.We didn't know if the universe had enough matter to collapse.

[@JohanHidding]

Hi, the little bit of movie at 11:45 got credited to Stuart MacLean, but it's actually mine! Still nice to see my adhesion model visualizations are going strong!

[@viralarchitect]

That's a pretty intuitive solution for dark matter. I'd love to learn more and see if we can test it further.

[@TheRealSkeletor]

Dark energy, not dark matter.

[@matthew164]

That makes alot of sence, i hope more research is done here

[@Numba003]

Thank you guys for another excellent video on the current research. The fact that we're even able to grapple with scales this large with reasonable plausibility is astounding. It's so hard to know things with certainty at such scales though too. Extraordinary stuff. God be with you out there everybody. ✝️ :)

[@gregzer]

Yeees finally i have another oh so soothing pbs space time video to fall asleep to

[@livinlicious]

Making the geometry of the universe self creating it's own expansion is way more convincing than inventing a new phantom energy. I would even argue that this works also for dark matter on smaller scales. The inward gravitational pull of a Galaxy creates void around it, which can me thought of as a bubble skin that holds it together. Sure dark matter has a few other ideas attached.

[@pendra_txt]

It's very occam's razor-y

[@spyresoblazx]

Any structural or MOND theory of dark matter is pretty much dead after we've seen galactic haloes collide and pass through each other without electromagnetic friction

[@garethdean6382]

A big problem with galactic structure is that the percentage of dark matter in a galaxy varies a great deal,rather than being near identical as one might expect. Some dim galaxies seem to be more than 99%, while some seem to have none at all.This generally requires a more complicated explanation.

[@livinlicious]

@@garethdean6382 It would really depend on the "lumpyness" again. If those that consist of large amounts of "dark matter" just have a different geometry in terms of void areas, it might be part of the solution as well. No matter what, this approach seems still less than ideal for Dark Matter, but very convincing for dark energy. I feel it has always been a mistake to make these 2 phenomenon "dark", when they seem to be separate. Or maybe not, maybe its all the same. In the end, everything must have a same source, the fundamental attributes of spacetime must create all of these effects.

[@slanglabadang]

The universe being foam on a large scale feels so elegant for some reason

[@aidanpeairs1967]

I love seeing new theories in the discrepancy of the expansion of the universe, it felt like what could be incorrect math or observations were being explained by outlandishly high values of dark matter and energy

[@blainelanders2361]

Wow! That was a good one! The animations were awesome. I love hearing about the latest theories!

[@Mikaact4]

What if the The big rip happens 💀

[@artificercreator]

Good one, good work

[@arrowinmygluteusmaximus]

I wonder how much brighter our night sky would be if we weren't in a void.

[@ds27315]

Hardly brighter at all, I think - though it depends what you mean by 'not in a void'. It's not possible to see anything with the naked eye beyond the Local Group even in the most perfectly dark night sky with peak visibility, and on the scale of the Local Group we're not really in that much of a void. The night sky might be a bit brighter if we were in a denser region, sure, mostly just from a greater number of faintly visible galaxies, but I don't think there'd be any more truly 'bright' stuff to see (and if there were I think we'd be in trouble)

[@Vasharan]

The farthest visible object to the naked eye is widely considered to be the Andromeda galaxy, which is 2.5 million light years away. The KBC Void mentioned in this video is 2 *Billion* light years across, or about a thousand times larger than the distance between us and the farthest object we can see without a telescope. So if the empty space were filled instead, the difference in night sky luminosity would be pretty close to nil, any stars/galaxies we're missing out on seeing are 500 to a thousand times too far away for us to see, anyway.

[@AntCBCV]

The majority of the stars we see with our naked eye are from within our galaxy. Our sky would likely not change much if we were in a different part of the universe.

[@rudyberkvens-be]

We’re not in a void.

[@Jondiceful]

True or not, there's something beautifully simple and elegant about this bubble model or cosmic voids. I am also very interested in this description of the Dark energy decreasing and ultimately evaporating over the distant future of the universe. I'm curious to know how that changes the forecast for the heat death of the universe.

[@ParadoxProblems]

As I learn more and more about physics, I become more and more annoyed that so many of the "great mysteries physics" boil down to, "well, 3 people made a simplifying assumption 30-50 years ago and no one thought it had any effects"

[@garethdean6382]

That's generally how a lot works; especially given how computer power changes over time.Quite often people knew there'd be effects, but couldn't model them and specifically noted the shortcomings. But a decade of no big issues and the assumptions get baked in. It's a chronic issue to this day, where you'll see the news spout about,say, population crashes, so long as everything keeps going exactly the way it is right now. I like to think it's just the logical way our knowledge grows. At first we assume (or even think) that the situation is simple, only later do we see the complexities and shades of gray.

[@alexiordache760]

Please make a long video about voids and dark matter. Those animations of the filaments are really and eye opener.

[@etdr]

Could the fact that our supercluster is in the middle of a void explain why it hasn't been harvested by advanced grabby aliens yet?

[@pembrokerise]

In that case, let's hope we continue to be a region grabby aliens classify as "not really worth the effort."

[@garethdean6382]

It's not THAT much of a void, only around 80% of the universe's bulk density. And there's a lot of galaxies in here with us. It doesn't reduce the odds too much.

[@theMightywooosh]

Welcome back and Happy New Year!

[@houjous5131]

The last bit @ ~ 13:00 about the "back reaction" makes total sense in the way that we already proved that to be true on the "small" scale by using the gravity of other planets to launch our "deep" space satellites farther faster. And can be articulated similarly to the string theory.

[@jessecail8182]

SPACE BUBBLES! I think this should end up in some merch.

[@desmonddesjarlais2697]

I swear this guy could sneak in a demon summoning to the math segments and id never know.

[@ASLUHLUHC3]

Hahaha

[@lucienskinner-savallisch5399]

Gotta love parsimonious explanations and theories

[@malaclypse4059]

Matt loves Becky!! Matt loves Becky!!!

[@rickhobson3211]

It's amazing to me too how often bubbles and foams keep appearing in physics!

[@nellym46664]

Bubbles are the crabs of physics IYKWIM.

[@radekc5325]

For an intuitive explanation for why dark energy produces an expanding push: dark energy means vacuum has energy, and expansion of the universe produces more vacuum. Just like a rock "pushes" against your hand because it "wants" to gain kinetic energy (by falling down), vacuum pushes for expansion because it "wants" to gain more vacuum energy.

[@quixotic7460]

We need a Matt / Dr. Becky collab asap!

[@steamedwatermelon2165]

One object in space to another: I don't feel like going anywhere. The space between them: LET'S GOOOO!

[@mickwilson99]

Good stuff, Matt, and very glad to see you're comparing notes with Dr Becky, the other absolute best cosmology commentator on KZbin!

[@davidsault9698]

There is a good feeling to the cosmic voids expanding bubbles explanation for the Hubble Tension, indicating a Universe more complex in its interactions than assumed in the simpler past.

[@twotheabyss5966]

Nicely wrapped up with the signature "Space Time" ending

Happy new year PBS Space Time