What If The Cosmological Constant Is NOT Constant?
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- Опубликовано: 10 окт 2024
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We know that the universe is getting bigger. And we know that the speed that the universe is getting bigger is also getting bigger. The standard assumption is that the acceleration rate is itself constant, which will surely result in ultimate heat death. But a recent survey of primordial sound waves frozen into the way galaxies are sprinkled through the universe reveals that this fate is now in question.
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Hosted by Matt O'Dowd
Written by Richard Dyer & Matt O'Dowd
Post Production by Leonardo Scholzer, Yago Ballarini & Stephanie Faria
Directed by Andrew Kornhaber
Associate Producer: Bahar Gholipour
Executive Producer: Andrew Kornhaber
Executive in Charge for PBS: Maribel Lopez
Director of Programming for PBS: Gabrielle Ewing
Assistant Director of Programming for PBS: John Campbell
Special Thanks: Adam Schwartz & Kurt Ritta
Spacetime is a production of Kornhaber Brown for PBS Digital Studios.
This program is produced by Kornhaber Brown, which is solely responsible for its content.
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It's pretty crazy thinking i used to watch children's shows on PBS on my big boxy TV as a kid, and now i watch grown-up stuff on PBS on my phone.
“Back in my day bread only cost a nickel!” lol teasing
@joshuasheets9236 lmao not quite, I'm only 27. I do remember gas being under a dollar when I was a child living in Kentucky though.
The world is getting smaller :D
Same.
Holy crap I got the ❤️ from PBS 😮
The only universal constant is how great your videos are 💯
And π
No you're great 😌❤️
Change in acceleration is called jerk. So we're looking for the ultimate jerk in the universe.
Who, you mean Carl?
Underrated comment
@@lexruptor 🦙🦙🦙
snap, crackle and pop are the next 3 derivatives. Learned that from Sean Caroll.
I want to see an episode of SpaceTime that wraps up the last sentence without saying "spacetime," and Matt starts to walk off-screen. Then at the last second he pokes his head back in and just says "spacetime"
My favorite game is trying to figure out when the spacetime name drop is going to occur.
That would be hilarious
Hey PBS, Spacetime here!
@@BierBart12Michael?
@@demondoggy1825yeah, I've gotten good at it. You can just feel the sentence structure or tone of voice indicating he's coming in for a "landing".
Pro: this may be a new phenomena in physics
Cons: it may give string theorists more material
Material is good. If it supports them, we might be getting closer to a deeper understanding. If it conflicts, the theories can be abandoned.
Without more material String theory is stuck in this limbo of "well yes that's all very interesting and it might resolve a problem or two, but how can we test If it's correct?"
@@TestTestGoi mean it will energize them and motivate them to waste more time
String theory needs to be relegated to the private sector.
@@TestTestGoYou missed the "Laugh at the joke" cue. Well, I'm pretty sure he was joking at least. 🤔
@@morscoronam3779 I'm pretty sure most in this comment section have lost the plot.
Thank you for all you do Matt.
The title is a question I’ve been wondering about since I first heard of it.
As long as y'all remain a YT constant, I'm happy enough.
Favourite youtube channel ever please never stop posting
When he said we get the complete data from DESI within a few years I realised PBS Space Time might not be around to tell me about the results and I cannot pretend to understand anything.
@@herrvich fr every night i wake up in a cold sweat from a nightmare about the demise of PBS Space Time 😞😞😞
It’s definitely among the very best of its type on RUclips.
This and History of the Universe channel
The (observable) universe is finite, so there's a finite amount of things to teach. I'm afraid Matt and PBS Space Time are fated to eventually stop posting one day.
11:02 Thank goodness, I was really sweating the “BIG RIP”, so RIP BIG RIP‼️
Wouldn't they very fact that inflation occurred, proves that the expansion constant has changed more than once (1. Initial inflation 2. Post inflation) and would it be a fair assumption to make that since it has changed that it maintains potential to change again for any number of reasons?
Yeah that always bugged me
I might be wrong, but I don't think that early-universe cosmic inflation is postulated to have been caused by the same phenomenon as the dark energy causing the current accelerating expansion.
So the first inflation could be caused by a separate solution from what causes regular inflation, the cosmological constant only aims to describe the current inflation rate, not whatever caused the first inflation.
So when we talk about a constant inflation acceleration rate, we mean the part of the inflation that is happening right now, not the first one.
Also the first inflation is mainly here as an explanation for a few different problems, and require an inflaton quantum field which would have been stuck in a local minimum energy density during the initial inflation, whereas we don't know what actually is the dark energy we encounter. It could be the same inflaton field or another one with an energy minimum at whatever dark energy is supposed to be at, but it could also be any other of the wild theories that have been thrown around.
Not a physicist, just a nerd
@@aaronb1195 I think that if the cause of expansion changed that means the potential for it to change again would be a logical conclusion. It allows for any particular constant to be present no matter what the current cause is.
@@celivalg Sure, I'm deliberately being slightly reductionist. Though if we are looking at if the cosmological constant has changed over time, I think it's useful to point out the universe has expanded in the past for 1 more more reasons, which means the rate has changed at least twice and there is nothing to suggest it couldn't again.
Thank you for explaining where the primordial sound waves came from. I think this is the first time I've understood that.
I'm hoping for the Big Crunch - endlessly repeating. This would mean the Universe would last forever in the cycles, a kind of immortality for the Universe, and also for us, as there may be an infinitesimal part of us all in it, always 🙂
Awful. Infinite holocausts? Infinite suffering? Repeating the same awful things over and over again ad infinitum? Truly an existential nightmare.
@@jbone13131313 There are always good things and bad things. Like puppies and misanthropic pessimists like you.
@@jbone13131313 Quantum mechanics likely means the passing of time is non-deterministic, meaning each new cycle of the universe would most likely be different from each other. This whole ordeal is highly hypothetical tho and such hard to argue about.
@@jbone13131313 cyclical cosmology doesn't have to imply that all of this happened before and will happen again.
If the cycling is infinite and the distribution of matter is randomly determined each time, then every possible arrangement of matter would happen an infinite number of times, including the current state of the universe. There will be another you, exactly the same reading this comment, an unfathomable distance into the future.
Infinities are weird.
The fact that people still think the “universe” originated from a single point then have to believe in physics breaking inflation, is just astounding.
Wow, the presented method for discovering those acoustic rings is astounding, epic, and would have required a ton of computation! I love it!
I only understood about 3% of this video, but what I did understand blew my mind.
Thursday is always a good time for PBS Space Time
His shirt kinda looks like UFO mushrooms
It does look like if I got too close that it would punch me with astonishing gusto.
Space penises.
If you get the reference good job.
I see it
Unidentified Fungus Object?
Reminds me of that one Boston Album with the Guitar UFO's
Change can change. Change is changing.
But war... War never changes.
I'd love to see a Spacetime exploration of the notion that matter is shrinking instead of the universe expanding. It's something I've often thought about but lack the "real physicist" cred to actually dig into.
I was positive you said, “THOLIAN Quintessence”, and I just knew those alien insect bastards were up to no good yet again.
Man any time we assume the possibility that some physics constant is not constant, I kinda give up believing what we can know about the universe by rewinding the laws of physics billions years into the past. Like bruh back then we had electroweak force , how do we know what else was different
More Science!
Current theories are always the best model we have for what is, was and will be, based on all the evidence humanity have been able to collect to date. Nothing more, nothing less.
A good scientist should always hold their beliefs tentatively. Always ready to be proven wrong, but also confident that the current scientific understanding is the best available at this time.
This built in self doubt is what seperates science from other ways of knowing things, and is why it is the superior tool in the search for truth.
Well we can never "know" anything at all in a post-Kantian world. Science just makes progressively more precise and predictive models that coincide with our observations, that's all.
Exactly!
Been waiting for this episode 😂🤍
I have been waiting for this exact topic from you since hearing rumblings about this crisis in cosmology for a few months now. Excellent, as always Matt, and PBS Spacet Time team. I always wanted to be a cosmologist but a different path in academia is unveiling itself to me. Through these videos I feel like I can still stay close to the current topics of cosmology on a level higher than just a basic one.
I find it incredibly humorous about aliens visiting the earth... and I like to share stuff with that nature on social media... I love the glow in the dark decals, I'm disappointed it's a limited run.
Despite I've read, watched and learned a lot, I'm still amazed by science and it's ability to predict things. Isn't it amazing, that we predicted those rings, then looked up for them and BANG - there they are! Same for CMB and a lot of other!
It’s somehow weird seeing that any doctor of astrophysics, let alone famous one selling hoodies and t-shirts like in a carnival 😄
If it’s a proper Big Crunch due to the reversal of dark energy, how many times have we done this? Imagine just looping back and forth for endless eons and not knowing.
Universe is not expanding. It can be seen with acoustic relativity/analog gravity.
I think a big bounce would be the best scenario, static universe and everything gets boring, expanding and you get the heat death or the big rip, reverse expanding and it crunches back down to a singularity, but if it is a cycle like the bounce, then new universes with new rules are made every once in a while
Big Crunch? Big Crunch!
Thank you Matt and PBS Space Time for continually producing quality content. I appreciate all the work that you do.
A brand new fresh Space Time! What is this, the big bang? - N
green name spotted (thanks)
Pbs is always 1.5 years behind .... lol but when it makes it to pbs... I love this movie in real time... buttery popcorn
The BAO rings on the CMB made a lot of sense because the CMB was mostly a sudden snapshot in time. For the BAO measured in galaxy distributions, I would have expected a 3D spherical shell rather than a 2D ring aligned with a redshift.
that would still leave 2D rings though, wouldn't it? In the sense that from any given point of view the "borders" of the sphere from that point of view would look denser.
@@user-sl6gn1ss8p Absolutely. Though you wouldn't know if that redshift corresponded to the diameter or a slice through a spherical shell closer or further which would always be smaller. But yeah that's a good point, if they can show it's the largest then that ring would be all you need.
It is a 3D shell: that's why they find this correlation by measuring distances to the center - that is, distances in 3D, not the 2D image we see from Earth. The 2d rings are just a diagram (and are how it appears in the CMB, which is a frozen 2d surface of a 3d shell at the Hubble distance).
Oh. Wow. Fascinating... I think. I'm just gonna go ahead & take your word for it. Again.
"Its never aliens... Until it is."
My thoughts exactly. I find it highly unlikely we're the only intelligent life in the whole universe, but I don't think Earth has has any visitors yet. And if it has, can you blame them for seeing our town on the horizon, locking the doors, and turning around?
Matt seems like he needs to sneeze even more than usual! 😂
In 2011 Perlmutter, Riess and Schmidt received the Nobel Price for their work on the expansion of the universe. What was new about their findings compared to Hubble and the Hubble constant?
I love Cosmology: If we want to resolve a fundamental disagreement in observed values for two key measurements of the universe, we need this other variable that some models think is constant to be going down.
The good news: We think we've measured the variable, and it looks like it might not be constant after all. The bad news: It seems to be going up. *shrugs*
I know I could have made this happen if I had been in time to get a patch, but you gotta make the "quantum observer" logo as a cap. It would look so much more official than a t-shirt.
Or offer the patch again! Please!!
This is an illusion of the effects of curved space. We switch logic when we talk about distance in space. You can't look straight back into curved space! You get an illusion which sees only the tangents of distant objects.
Going back to before the current universe, all of the matter that is currently out there was crushed into a universe-containing black hole. Which would have, by definition, also have crushed space/time into something rather different from current. So when the matter became energy and somehow released itself from the black hole, space expanded along with it. Who's to say that crushed space doesn't expand differently over time, and as it heads toward its original, non-crushed size, the expansion slows to eventually stop when space's internal pressure has fully relaxed.
Did he say the assumption of constant acceleration could be wrong? What a jerk.
Awesome video, haven't heard about these DESI results before, they seem promising for setting a new credible direction in cosmology and will hopefully lead to more progress in our understanding of the evolution of our universe. Unfortunately the base DESI results + CMB BAO measurements are not even 3 sigma, which is nothing in the high standards for evidence in cosmology, but the other surveys might be a smoking gun for when DESI collects a lot more data that there's something more hiding here.
Strength/character of a field changing has precedent in things like the electroweak transition, so i wouldn't be surprised if dark energy isn't constant.
Frozen Galactic Primordial Soundwaves: title of your sex ta
I mean - awesome band name.
Gravitational lensing should show us standard candles farther than we could otherwise see them.
🚶The quest for understanding of Space and Time continues.
And, next time, "What if it's not cosmological?"
Aaah I love this channel. Never ever stop!!!!!
I am just hyped for the DESI results for the 3d model of the universe :0 I hope it comes soon I can't wait for years ;-;
I really hope this works out to be real, and the cosmological horizon is receding. Any effectively finite universe feels stifling, regardless of how big, given the infinity of mathematics.
No Heat Death? Honey, I cant join you, I have a bearded man to watch!
I literally nearly had a meltdown when there wasn’t a video on Saturday
What do you mean, no heat death? Do I have to start cleaning my apartment now?
6:16 dafuk I was wondering since forever why even on on my primitive astrophotos so many strange almost perfect circular star things. That is it !
Stability is only a requirement for being like our universe if our universe is stable.
Just imagine if we had contact with an alien civilization thats been around for hundreds of millions of years, perhaps billions? They would have direct observations of how the expansion might have changed over time.
I won't be surprised if it turns out that Space could and will fold at the end.
I think the accelerating expansion of the universe could be caused by the EM radiation emitted mostly by stars but also by nebula and even planets in smaller amounts. Solar sails and laser tweezers prove light can impart/alter velocity/momentum.
My money is still on spacetime traveling through wormholes to the Big Bang.
Fantastic content, can’t wait for every video
OMFG the title of this video was my shower thoughts a week ago!
... I really don't have a point, but I saw the title and I don't have anyone to tell other than strangers on youtube 😅 lol
“No heat death”
Lord Kelvin disappointed
...The twitter reply bots can't get us here, right? The coast is clear? We're sure? Okay, I'll say it. I'd buy Space Time merch with the little "not statistically significant" graphic that shows up at 14:00.
if it's due to forces and particles distributed throughout universe, then more than likely not constant, as those things get moved around and universe expands, so forces distributed over larger space.
If you could travel back in time at same rate time is moving. Forward. Plus space. Moving already. If your moving at light spreed going against Galactic rotation
Some experiments show sound to have affects of negative mass
That's pretty simple, it would become zero, and the other tensers would determine the characteristics of the effect of gravity.
BOA's are so cool...
First I heard of them
Is this a joke please ?
This is my favorite channel
Welp here we go. String Theory kept cramming in more dimensions and now we are stuffing in more fields. God: Okay, how many dimensions do you need?
Love you matt
I don't see those Baryonic acoustic waves in the CMB when I look at it, and I've looked a lot. If people are seeing that, it's probably like seeing faces in a cloud where you just see what you imagine seeing.
Really insightful!
Anthropic arguments aren't arguments.
I don't understand much of this but I do know that if your ship is going through a 'Baryon Sweep' you had better not be still on it.
Proposal to pronounce B.A.O.s as Bao like the Asian food buns. Steamed rice buns are circular like B.A.O.s, so I think it's fitting. :)
Grrrr… Now I’m hungry…
From a bit of googling and asking my wife who studied mandarin, the pronunciation of bao is pao in mandarin and in the rest of the world since it seems to originate from portuguese and is only pronounced bao in the US. So it would only lead to arguments any time the B.A.O.s are mentioned.
@@ajmalboodhun6875 Uh... Everything I'm looking up shows that it's pronounced how one would expect. It's also how I've heard it pronounced from my Chinese family members. So ¯\_(ツ)_/¯
I had a crazy idea some time ago that if the universe had some curvature, then the cosmological constant could be proportional to the curvature of the universe. This may explain the inflation in the early universe, and then the slow expansion in the later universe, which would gradually decrease.
Lol......
I like my Cosmological Constant to be Constant.
This is so cool
In Alien news...While having a colonoscopy today, I suggested to the staff attending me, that they were aliens. Cleverly, they now have no need to kidnap humans for probing, we show up voluntarily. No one laughed, they just increased my medication and looked at each other like someone was on to them! (This is a true story!)
Well that shat in my oatmeal 😂
We are just here for a blink of an eye. What if we came into existence just now, and leave existence just soon?
A random boltzmann brain.
Why are we not still experiencing the inflation of the early universe? Doesn't this imply that the forces causing expansion definitely did and maybe are changing?
Yeah, doesnt the big bang inflation show that it's not constant?
We are still experiencing it.
One idea is that inflation was a phase change, a one-time discontinuity, somewhat like how water can change from steam to liquid to ice. This video is suggesting a smoother change over time.
Needed this right now. I had hit the end of RUclips.
If anything happens, Desmond is my constant.
In as much as we cannot see the entire universe, as far as we know, the universe is still being created.
Not seeing past the CMB does not mean that there's nothing on the other side. What we think of as the beginning of the universe could just as easily be a local event in a much larger, much older, universe. Eternity is, after all, a very long time.
Matt: any comment on the recent astronomical evidence published (in the journal Particles) in support of the Tired Light hypothesis, demonstrating that the universe is not actually expanding...?
Ah great to see scientists flirting with the universe!
Why do I want the universe to end in a Big Crunch and not in a Cold Death or Big Rip? It’s not as if I’m going to be around.
Because it's comforting to know that there's a possibility for new life even if we are long gone. Plus, it would also kinda explain where the Big Bang came from. I'm also team Big Crunch in a very unscientific way. 😄
Because we take solace in the little possibility that we may, one day, have a chance to redo our lives. Every one makes mistakes and everyone has regrets. Even if dark energy reverses and there´s a big crunch there would be absolutely no gurantee of the chance of a retry, but if there´s one thing the brain´s great at it´s clinging to the littlest bit of hope.
I couldn't care less lol. Sometimes I wish it would end righ........
BAO BAO!
Why don’t they give Spacetime its own TV show? 😮
If Dark Energy is a fabric that gets condensed into a black hole during gravitational collapse and continues to consume all matter into the black hole. The Dark Energy would be above -1 and the centripetal force would return the universe into a big crunch.
such a great show.
slowly evaporating "space-condensate" .. I feel closer to space and time already
I've been thinking about the expanding universe speed accelerating. Assume the universe is spherical. Outside of the universe is nothing, void, a vacuum. The surface of the sphere feels a pulling force from the vacuum outside. The vacuum force is constant per area, but the surface area increases as the universe expands. Total force pulling the edges of the universe continues to increase.
Just a wild guess. I'm usually wrong.
150 MILLIONS OF YEARS THAT THE WAY IT IS
Yay!
Nifty.
It'll be quite the achievement to finally put to rest Einstein's "greatest blunder"