Anti-gravity and the True Nature of Dark Energy | Space Time | PBS Digital Studios

[@ZetaFuzzMachine]

When this very video has uploaded, I was on my way to give up studying physics. 6 years later, I'm proudly announcing that my thesis will be on the thermodynamics of dark energy. Cheers Space Time! You guys are partly to blame!

[@Pao234_]

Wow, that's pretty bold. So... How'd it go?

[@pavel9652]

I know next to nothing about thermodynamics and dark energy, not to mention thermodynamics of dark energy, but chances are his thesis has very high entropy ;)

[@garethwillis]

Hmmm

[@garethwillis]

How can you write a thesis on the thermodynamics of something that nobody knows the answers to?

[@suruxstrawde8322]

@@garethwillis Humanity may have the edge of collective thought, but zeitgeists still hold back their sight lines. Looking for the impossible is conceptually the same as looking both forward and backward while searching for something. And we shouldn’t all be pointing in the same direction if we want to expect the unexpected.

[@doodelay]

I'm very, very impressed that you guys don't shy away from showing your audience the actual equations as well as taking the time to explain the specific values within them. Big props

[@ophidahlia1464]

I'm 5 years late commenting here (this channel is best experienced from start to finish), but for anyone who likes how Matt explains the math in a way that is accessible to laypeople while keeping the hand-waving away to a minimum will probably also like Dr Don Lincoln (a particle physicist) who runs the Fermilab KZbin channel. Don gets a little more into the math but he also spends more time taking you carefully through the equations. After I watch a topic on here I'll often go to find the same subject on Fermilab's channel, it can be very helpful to get two different styles of teaching on the same subject in the physics! I'd love to see them do a collab video sometime.

[@SackbotNinja03]

Many other KZbinrs also do this and they will always be the ones I watch because the other ones seem like “for dummies” type videos lmao. I need the deets

[@ben3364]

The pressure in my head is greater than the outside pressure...mind blown.

[@shyamalaparthasarathy5616]

How dld that. Much Matter weñt inside ?

[@ibrarkhan9878]

😂😂😂

[@jscotthatcher380]

they don't call it blood pressure for no reason. 😜

[@georgeflitzer7160]

Lol

[@doctauglyd9861]

Drill a hole in that beast

[@opsihota2118]

"Inspire enough smart kids to be scientists instead of bankers and it is well worth it". That really hit home, I actually switched fields from Aerospace to Finance.

[@michaelmeredith912]

Lol, I’m a Banker 🤦🏻‍♂️😄

[@theultimatereductionist7592]

@@michaelmeredith912 You should be paid minimum wage or not at all, as a banker. In fact, you should be forced to pay for playing banker, the way college students are forced to pay for working and studying hard to better the world.

[@colorpg152]

@@michaelmeredith912 do you ever feel guilty?

[@seditt5146]

@@theultimatereductionist7592 You must smoke crack if you believe that nonsense you typed.

[@fatstar111]

this is THE BEST SHOW EVER!!! So well explained and not basic science, really cutting edge stuff. All new science since I finished doing this stuff in Uni. keep it up guys!

[@Cythil]

+Paul Budden Yeah I like how it tries not to dumb thing down and present false analogies just to give people a hint about what is going on. So many times have I heard people just misunderstand the Higg's mechanism and it all down to a lot of science shows just explaining it poorly.

[@pernaboys]

+Cythil yep, because there are real scientists behind this channel, most of other youtube channels are just bunch of guys who don't know what are they doing and making videos for money here with false information

[@Yogii0000]

+somebody cough ASAP science

[@viermidebutura]

+Paul Budden i like it because it doesn't dumb down the science

[@PhilDrinkwaterUK]

Totally agree. It's fantastic!

[@LordTalax]

It's interesting how far we've come. When I was a kid everyone was sure that expansion would slow and a big crunch would come. Now we know expansion is accelerating.

[@manjsher3094]

It's like weather, just wait it will change. Given a few more years and were gonna go back to the big crunch idea. Just a thought. Today coffee good for you tomorrow bad.

[@avinashreji60]

@@manjsher3094 that’s because you have zero understanding of how science works, it’s called progress. I know you hate it

[@manjsher3094]

@@avinashreji60 mental genius

[@avinashreji60]

@@manjsher3094 Yeah go ahead and deflect

[@manjsher3094]

@@avinashreji60 done

[@mikeunleashed1]

9:25 this whole video summarised in a couple seconds.

[@alpsoysal3586]

+mikeunleashed1 We demand a "Because Math!" shirt.

[@Jep_productions]

+mikeunleashed1 Pretty much everything to do with space and time summed up in a couple seconds lol

[@ericvilas]

+Alp Soysal Every video has an "I need this on a shirt" moment.

[@ximecreature]

+Eric Vilas maybe but a "because Math!" t-shirt would spare me much time

[@DumA2034]

Thank you, he wouldnt stop moving and making faces, it was bothering me...

[@npip99]

This video was perfect. I love going over the equations, since I always feel a huge hole when I'm told "Because Math", without at least seeing the math (And most of the time you guys do throw the equation in the background, which eases my mind). In this case it was perfect to bring it in, because the most advanced it ever got was "Negative * Negative = Positive". I'd be happy to see even more math sometime, at any level of ability.

[@normanthornton9376]

Nick, Their is no positive nor negative states of existence in the universe, their is only the comparative states of mass and forces.. A bar magnet has to us a positive and a negative pole. They repel each other and we give then our designations of positivity or negativity but actually they are equal in mass and magnetic field properties and as that law of physics applies which states that opposites attract and equals repel. Both ends of a bar magnet have the same mass and magnetic field force. It is we who choose to call one positive and the other negative

[@MaryAnnNytowl]

@@normanthornton9376 no, they're not just equal. They're equal *and opposite.* We know that because of the measurements we can do on each end, and how they interact with each other.

[@normanthornton9376]

@@MaryAnnNytowl How much time is in a cubic square mile of space M.A. Bittle or how much space is taken up by an hours worth of time ? Ergo they are not equal. Each is a measurement of a specific entity one being space and the other being of a durative of measurement of momentum. A man walking might cover a one mile distance in fifteen minutes, a man in a car can cover fifteen miles in that same fifteen minutes and one of our jets can cover a hundred fifty miles in that same fifteen minute span of time. You have three different distances, one mile, fifteen miles and a hundred fifty miles all in the same span of time. Where is the equality? Their is no such phenomena as SPACE-TIME. Einstein had to add a curvature to his theory about Mercury to make it work, but it doesn't work for any other Planetary body. In my mind any physicist who believes in space-time has wasted four years of college. I'll bet you also believe in a big bang and black holes Here is my email address [e-mail]. If you want a real explanation of those events give me a shout out. .

[@TransRoofKorean]

@@normanthornton9376 lol

[@TransRoofKorean]

In all seriousness, just like Einstein thought of the cosmological constant as a placeholder for something we didn't yet understand, I think the same thing goes for dark energy and matter for that matter, as a way to help physicists sleep at night, to keep them from panicking when they realize that nineteen-twentieths of the universe they look in the general direction of and say "I see you" [a lie they tell themselves], "but I have no idea what you are" and then go back to experimenting with the one-twentieth they can actually interact with and measure (and half of those things we can't directly see, either, but only their interactions with other things -- I think Eric Weinstein *_might_* be the guy finally barking up the correct tree with his very-incomplete Geometric Unity, where he's essentially showing a third of our particles to be illusory). Speaking of Eric, he says that he immediately knows someone can't be taken seriously if they ever say "lol" -- fair enough, no one should take me seriously. But I had to "lol" at your implication that Einstein is the guy who wasted 4 years in college. I think that's an easy indicator of someone to not take seriously. We're still looking at the best explanation for the fabric of the stuff we're swimming around in, and it's pretty obvious from your conceit on a subject you barely understand that you aren't going to ever be adding anything to it.

[@rafagd]

13:46 - People seem to forget that the money invested doesn't go to alpha-cen along with the craft.

[@bizzee1]

+rafagd Agreed. Also, since the person thinks that sending probes to Alpha-cen is frivolous, their general argument is that we shouldn't spend money on frivolous things until we cure cancer. Well, entertainment, fine-dining and fashion are frivolous, so I guess we should shut down entertainment industries, eat nothing but plain oatmeal and wear nothing but gray T's and sweat-pants until we cure cancer and all other causes of premature death? Of course if we do that, we'd all want to slit our throats and cancer would no longer be much of a problem anymore. You gotta have some fun in life or premature death is going to be preferable.

[@pcuimac]

People are dumb and know nothing. People don't know that money is created from nothing in banks.

[@RajSingh-qc6lq]

+pcuimac Money in and of itself is worthless yes, but that's not how money is used at all. Money represents a value of gold which can be considered the real currency. It's stupid as fuck to do it this way simply because or inflation in printing more money and such, but it's what we have.

[@Klarid]

+rafagd That's not even the real problem with their argument. They are horribly underestimating how difficult cancer is to cure. Throwing money at it speeds up research, yes, but there isn't a way to simply buy the cure.

[@rafagd]

Klarid That is also true.

[@TimmacTR]

1.Negative-gravity effect of dark energy comes from negative pressure 2.Conservation of energy no longer applies in expanding universe Double-mind-blow Mindblowception

[@prabhchahal4492]

+TimmacTR how can conservation of energy not apply?? then fucking god could exist as well arghhh :///

[@prabhchahal4492]

+TimmacTR i dont get what this video wants to say by this comment

[@TimmacTR]

Prabh Chahal I don't understand your question?

[@prabhchahal4492]

+TimmacTR i want to ask how cant conservation of energy apply? Then you could produce infinite energy and the universe wont need to die

[@prabhchahal4492]

+TimmacTR conservation of energy is like the supreme law of fucking everything. How could it not hold true. Thats like god telling a theist that i dont exist

[@genostellar]

I just realized that I wasn't subscribed to these guys yet. I wonder how that's possible. Subscribed now, before the universe collapses from the paradox.

[@titaniumoverlord6522]

That's very witty. Kudos my friend lol

[@neonblack211]

Thanks for reminding me

[@LuisAldamiz]

I keep coming back to this excellent video once and again each time I discuss gravity and dark energy. My mind seems to insist on forgetting the proper explanation: "because math"! Love it, very well explained.

[@sluggergirl2b142]

How are we supposed to get to the bottom of something that has antigravitational properties? 😜

[@pbsspacetime]

+Halo girl Oh, that's clever. Revision: "Let's get to the top of this whole dark energy thing!"

[@brettkriewaldt1657]

+PBS Space Time dont you mean the boundary? Or even cooler; Event Horizon!!

[@Psylent]

+PBS Space Time Halo Girl deserves a shirt for that clever remark

[@brocpage4204]

Phenomenal.

[@jabu1482]

Is the force experienced in the first expansion of the universe related to theirs current expansion of the universe? In other words, is there a theory of dark matter that can describe more properties than just what is guessed at in today's cosmology?

[@SilverAlex92]

I wasn't worthy enough for understanding the secrets inside this video.

[@LuisSierra42]

Just have to repeat it over and over

[@grandpasrobots4692]

you are probably worthy. its hard to understand the convoluted logic of this idiotic negative energy fantasy. Its almost as ignorant as dark matter

[@EKDupre]

And you accept that notion, and display it online for a laugh? Too bad. Putting effort in to be engaged makes you less relatable and doesn't give you as many youtube likes, but knowledge is power as they say.

[@SilverAlex92]

@@EKDupre Sorry I don't completely understand your comment. I'm a computer engineer, only got a couple of courses on physics in college. Studying astrophysics is just a hobby for me because I like understanding the universe we live in. But sometimes, like in this video, I don't completely understand the notions being explained so I just wanted to make a funny joke about that. Tho to be fair no one really completely understand dark matter, so I'm okay with being ignorant on this particular subject

[@LuisSierra42]

@@SilverAlex92 Ignore the trolls bro, a lot of people who are not career physicists cannot understand this complex stuff by just watching one YT video

[@732pizza]

Awesome animations, how long does an episode take to make? You can see the hard work paying off in this episode

[@claviceps_giles5177]

These videos are addicting and I'm really saddened that math was taught so atrociously to me in school. They never taught us what math actually is and what it can describe the way he does.

[@federicoesposito2943]

To study general relativity it takes very advanced math, way beyond what you could teach to teenagers

[@quinton1630]

Federico Esposito We used to treat learning a second language the same way. Just sayin ;)

[@tylersigi2965]

@@federicoesposito2943 yet in school you are taught to memorize and hate math.

[@grandpasrobots4692]

dont worry. this bozos math is just a snow job. hes delusional

[@pierfrancescopeperoni]

School sucks. Math is awesome.

[@alexandreandrianov5970]

All these concepts are easy to understand as long as you stay in the abstract world of math. Once you try to visualize or understand it intuitively it becomes very difficult as all physical analogies are incorrect. Our brains have evolved in a completely different sort of reality for millions of years. I am perfectly fine with negative pressure causing expansion as long as it makes sense mathematically.

[@paskwawi2007]

+Alexandre Andrianov Fallacy at best. Natue doesn't make what is possible in mathematics. Most people today believe in black holes, dark matter and dark energy with no proof whatsoever!! They can't even tell you what gravity is!! They are describing a effect.. that's it. Modern science is a joke.

[@alexandreandrianov5970]

Kinda ironic that you use the achievements of modern science to type this.

[@paskwawi2007]

Alexandre Andrianov Tesla invented all we use today. A man who was broken and stolen from. Your reply already tells me you are a defender of the status quo. Electric universe theory or ignorance. Ciao.

[@U_F_N_M]

+Alexandre Andrianov I am completely at peace with the knowledge that reality is generally unintuitive. Throughout history how many stupid things have humans done because they thought they had it all figured out?

[@SkyAce200]

+paskwawi2007 Tesla invented things, but not even a small fraction of what we use today. Satellites have in its programs a correction in its clocks to compensate the time difference due to what general relativity tell us about how time behaves... and thanks to satellites you can find the nearest McDonalds right now. Transistors are an achievement of quantum mechanics, basically the most abstract kind of physics out there, not even totally understood in a single theory... but thanks to quantum mechanics you are seating in front of your computer writing crap about modern science.

[@someguy3766]

10:21 *Chucks small cubed volume of the universe off screen* *Countless trillions of sentient being die* "So guys, this Dark Energy stuff..."

[@its5k806]

Lol

[@dashikibraxton5537]

😂😂😂😂😂🤣😂🤣😂😂😂😂😂🤣😂🤣

[@jackiewhitt4551]

Does ultra-microscopic life really count :)

[@coquio]

I don't know who I'm fooling here pretending I understand.

[@sinfuleldian9826]

Probably yourself

[@plrrt]

+Alfalfa Male feel ya. head just exploded. you're all invited to my funeral. :(

[@carlw]

Very simple AM. Simply stop pretending not to understand and allow yourself to start beginning to understand. Besides, if anyone has done at least hiss hook maths do physics and you just focus, it is understandable. Good luck on your mission should you choose to accept it.

[@carlw]

Also, and most importantly, if we don't have this then no land speeders. That's bad.

[@alexbatoian5534]

+Alfalfa Male watch it a few times and it will become clearer

[@markfennell1167]

you said this is not just some mathematical trick. But that is exactly what it is. Throwing in a new variables into the equation doesn’t necessarily mean that you have a physical reality

[@jeremyrainman]

I get very tired of people who complain about space exploration spending with arguments similar to: "We have social problem X, we must fix social problem X before doing special task Y! Anything else is immoral/wrong." This argument is like a parent telling their children, "Well, mom has diabetes, so we'll spend as much as we feel is necessary to make her happy, but we won't save for your college education." It is shortsighted and wrong. Humanity is a going-concern. We don't spend most of our life energy raising the next generation because the future isn't important. The future of humanity is *everything*. It is unfortunate that some people contract diseases and die. But there is no historical precedent for humanity ever being disease free. One might argue that humans actually live in symbiosis with disease and it could not be any other way. Human death from disease is unfortunate on an individual level, but from a species point of view, it is constructive, even a source of strength. Adopting a myopic view of human problems, expecting that human effort be spent to guarantee each individual get an equal shot at life is a waste of energy. If, on the other hand, humans spend their excess energy reaching for the stars... then we'll be doing something that we have no record of an intelligent species in the universe actually doing to this point. What's more important? attempting to make humanity perfect, it's home (earth) perfect, it's social systems perfect? Are those really more important than expending the knowledge and experience of the only self-aware beings known in the universe? Remember the quote... "Perfect is the enemy of the good." It's a no brainer. I may die of cancer. I may die of heart disease. I may die earlier than "my time" because of an unfortunate accident. But if I ever came back from the grave and saw fellow humans spending more time trying to prevent normal human deaths rather than pursuing their intellect, I would consider myself lucky to be dead.

[@chrispyfrenchfries]

+jeremyrainman Amen.

[@adrin181]

this is a great comment

[@Cowh1470]

Its my dream to lobby for additional federal funds for scientific research of any kind. I've got one year left in my masters program, I've always loved science but don't have the right brain for it. so I figure I should contribute the only way I can with the skills I have gotten.

[@sidneypickering9060]

go ahead

[@MikiMaki76]

+jeremyrainman I like science, we are a technological species, yet one cannot deny that, despite our vast scientific knowledge, the vast majority of people on earth still struggle every day for a living, and a lot of them starve. your opinion comes from the fact you are not among them.

[@CarlosAvilla]

Wont it be awesome when we come back to these videos in the future and say "hahahaha how stupid were we, it was obvious all along that ______________ and that's why _________________ "

[@konooleh]

Was a little bit awkward watching this video with a sister, who works in a bank, and hearing your last words about bankers lol

[@alexandrugheorghe5610]

+KONO career refresh

[@garethdean6382]

+KONO She's not used to it by now? KZbin's pretty much universally against bankers.

[@IlicSorrentino]

Bankers sucks

[@stylis666]

+Ilic Sorrentino You're just jealous that the guy's sister finished highschool.

[@konooleh]

Gareth Dean Until recently she didn't even realise there are people in space lol. That's what banking do with your brains, I guess.

[@nelfig]

probably one of the best short video explanation about this topic.

[@MyFrenchfries]

If you fall into a black hole right now, that what is closer to the singularity, will fall faster that than what is further. However, space before and after you, is falling in with you. So from each General Relativistic perspective of "you", because there would be no inertial frame to orient yourself (you could see), it would seem, like you are standing still, with all matter in your personal observable universe expanding in all directions, in an accelerating manner, as all of "you" gets ripped to individual sub atomic particles. What if that has already happened, what if the Hubble Horizon is just our personal event horizon, as seen from the "inside", and Dark Energy, is just due to extreme tidal effects?

[@CoalOres]

deep shit man

[@alejandroochoa559]

+CoalOres Deeper than diamond? Could it be... BEDROCK?!

[@cermoer]

+Marcel Hattingh That correctly exact !

[@Digitalneo1]

+Marcel Hattingh I have this depressing theory about what happens when you reach the event horizon of a black-hole. Its possible that you are only experiencing spaghettification at the rate of the black-hole's evaporation; where it's mass is reducing, allowing time to flow more perceptibly to you. Keep in mind your perception would only begin after an immense duration of time has passed in the universe. The black-hole would be much later into its life-span. Its kind of a terrifying thought, because you would experience being pulled apart over eons, not seconds.

[@BjornDov]

+Marcel Hattingh I would love to see this answered in the next vid :) vote up guys )

[@_N_O_X_O_N_]

You can't leave us just like that! I'm going to write a physics exam tomorrow and the whole point of our study is the law of energy conservation - in order to handle the mass defect in nuclear physics for instance. And now you throw it away just like that! :O I can't deal with that!

[@stevecrothers6585]

General Relativity violates the usual conservation of energy and momentum for a closed system. It is therefore in conflict with experimental evidence on a fundamental basis. It is therefore false. Explanation is here: Crothers, S. J., ‘Flaws in Black Hole Theory and General Relativity’, for the Proceedings of the XXIXth International Workshop on High Energy Physics, Protvino, Russia, 26-28 June 2013, vixra.org/pdf/1308.0073v1.pdf and here: Crothers, S. J., General Relativity: In Acknowledgement Of Professor Gerardus ‘t Hooft, Nobel Laureate, 4 August, 2014, vixra.org/pdf/1409.0072v9.pdf

[@DhruvaDevOnline]

wow ... smoked a blunt watched this and got my mind blown!!! I love this show!

[@MjolnirR52]

Dhruva Dev hahahahhaa same here brotha! :D

[@jamiecoleshill2182]

I cant count how many people, physicist at that, have told me I am wrong regarding the Conservation of Energy not applying in a GR based Universe. I was quite happy to hear you mention this point...

[@brian8507]

So ur saying that an accerating universe is conserving energy? How

[@slowberryvtuberclips]

Pizza and PBS Space Time, awesome evening in perspective.

[@EllenRipley1979]

+Slow Berry (SlowB) I know what you mean :D

[@jasonzark96]

I was supposed to eat my pizza while watching shield but this notification changed my plans

[@nevertrusasmurf]

+Slow Berry (SlowB) I'm eating pizza right now

[@alexandrugheorghe5610]

+nevertrusasmurf Just finished, at once with the video haha.

[@ILikeEpicurus]

Cannot wait until the last part in this awesome series and then have a SpaceTimeMarathon with more pizza!

[@phineasandferbrocks4]

When will the results of the challenge question be out? May not have participated, but am curious about the answer!

[@TheStaticUnit]

I think next week, he said we had two weeks (last week) to submit an answer

[@pbsspacetime]

+Aryan poonacha The challenge answer is going to be out in 2 weeks from now (three weeks total). We had a slight schedule change.

[@phineasandferbrocks4]

PBS Space Time Thanks, good to know!

[@dantebroggi3734]

+PBS Space Time How much energy is produced in the universe (by dark energy constant) in 1 second/year/milenium/time _t_?

[@garethdean6382]

+Dante Broggi You need to be more specific, the universe is a big place, and do you want the entire, possibly infinite universe? Its current density is 7 × 10−30 g/cm3 and the expansion it crates also small. Doing a rough back-of-the-envelope calculation I estimate the dark energy in a volume of space the size of our solar system would increase by the amount needed to boil a cup of water every few million years.

[@markfudge5642]

Up till now I have just been keeping my head above water. I am now lost.

[@charlesdavis7087]

+Mark Fudge No, you're not lost. These so-called theoretical physicists are lost. What they are talking about is theoretical stuff. "String theory," gravity waves, dark energy, dark matter, etc., etc. This is not physics. This is theory. The real problem in Einstein's great equation is in relationship to the equal sign ( = ). What Heisenburg was trying to say was that the observer is effecting the situation. ( what is = to what )? (Consciousness is effecting the equation.) In short, scientists have to seemingly leave out the hidden factor called 'consciousness'. Because they can't measure it or verify its actual existence; they simply leave it out of the equation. ( = ) Wrong! Consciousness proceeded light and it speed (Big Bang). Consciousness is the one omnipresent constant upon the whole of the universe. In the equation E = m c 2, "c 2" really should stand for the constant of Consciousness squared (matter). Consciousness is the cause of light and its speed, not the other way round. Not until they understand will they be able to move faster than the speed of light and be simultaneously present in multiple places (and times) at the same time. Thus: faster than light travel. At least, that's part of the way I see it. CVD

[@woofydawg1]

+Charles Davis Please learn what theory means, in a scientific sense

[@armanghannadian1489]

+Charles Davis atomic theory of matter: that things are made up of atoms is "theory" as well

[@LouSaydus]

the only difference from scientific theory and scientific law is time. They are both backed by good mathematics, experimentation and replicability. Scientific law has just had more time to ensure it is correct, or at least more accurate than most theory.

[@alucardwhitehair]

Actually, laws and theories are completely different areas of scientific understanding. Laws just state natural phenomenon while Theories explain or describe their mechanics. For example, we know without a doubt that cells and atoms exist but Atomic theory and Cell theory are still theories. The Teory is the highest level of scientific classification.

[@tharealmikezee3165]

I love this channel. I gotta get some PBS over-the-air bcuz I'm really into radio. I tell ya...I hated math; I failed miserably. I remember I had such a hard time multiplying & dividing, adding & subtracting FRACTIONS. Okay? So then one day I'm sitting in Music Theory 101. Sitting there writing out accurate rhythms correctly on stave paper. And, then it hit me: what was I doing? Adding, subtracting, multiplying, dividing fractions. Music is math too. It's just based more on intuitive feelings instead of concrete rational ideas. Altho it's governed by math like everything else. SO I wish I would've done better at the basic level bcuz as I started learning about quantum physics...I LOVE IT. Always have.

[@brianhannay2218]

12:56 the subtitles say inaudible, but he says "Alpha Centauri"

[@pyrexpat4130]

Shit I'm glad u caught that what would we have done without you

[@SuperPawuk]

the IQ of australia dropped somewhat when this guy left

[@Mark-Ozi]

Nah, went up

[@hairohukosu433]

@@Mark-Ozi try not to cut yourself with that edge

[@Mark-Ozi]

@@hairohukosu433 A bit to subtle for you was it?

[@hairohukosu433]

@@Mark-Ozi ok look Im very dumb and I have no idea what you wanted to say there so Ill just go on with my life, cheers

[@Mark-Ozi]

@@hairohukosu433 Good luck

[@Wihnu99]

And this is the reason why I want to be physicist!

[@robertschlesinger1342]

Very interesting and worthwhile video.

[@cernunnos_lives]

Great explanation of negative pressure (in lens of an expanding universe).

[@kosatochca]

Isn't there is also a negative pressure in tree trunks? I heard something like this from Jared but I forgot what video it was

[@markthebldr6834]

Yes. I too, like how he explained the things.

[@KibyNykraft]

@@markthebldr6834 It looks like a popular magazine story that typically lowdegree graduates and the youngest scholars like ,without much pondering or skeptical evaluation . Make no mistake, the subject is exiting. A couple of questions : 1 What is expanding and how? If space is empty, it cannot expand. All of standard physics model theory as well as Bohr, Mickelson-Morley (Einstein "in a way") builds on a literally empty space with physical matter in it. If cosmos does expand like from or by a cosmic inflation/dark energy effect, space is however literally aetherial. There is more than just a small contradiction there. If space is literally empty, there is no expansion, only internal infinities of dynamics. Only special relativity ("SR"/"STR") and magnetism. Gravity and other forces ,energies are there anyways. 2 "Flattens out"? There is no evidence of that. Flattens out into what ? Relative to what? 😅 If space is a vacuum, fluctuative or not, what is outside of our universe? If it is however a UNIverse ,there is no possibility of that. If we have a local blob cosmos in a multiverse ,inflative or not, we have a local cosmos being an aether (a word from greek yritha, an expression in monad-pythagorean cosmology and geometry). 3 Did you read all the work of Miles Mathis? Do that . His name and dot com. 4 Any force pulling against an expansion from the inside of a universe , if einsteinian gravitational , pulls on the outer objects. Are we talking about expansion of baryonic matter movement or expansion of space, or both? How/why? Much of mainstream explanation now just looks like compromises . I guess it secures subsidies to make it look fancy.

[@KibyNykraft]

American melodrama style but some interesting points here : milesmathis.com/inflat.html

[@KibyNykraft]

As well as www.nevyns-lab.com/mathis/mirror/milesmathis.com/hubb.html

[@ardechirpakfar6823]

I'm so enjoying these videos! But you lost be when talking about particles pressure. As 80% of the mass is Dark matter and these particles do not interact like baryonic atoms that are repulsed from each other by electromagnetism, what means the speed and pressure of the particles???

[@AuthenticDarren]

Great video (and videos), It might even make the idea I've always had for this accelerating axpansion of the Universe seem even sillier than before. It's such a simple and seemingly obvious idea that I find it strange that I've never seen it mentioned or even just simply explained away before. Well here it is: Could the accelerating expansion of the Universe be due the unimaginably colossal expanse of nothingness beyond the limits of the Universe? So continually dragging the matter of the Universe into it like a vacuum cleaner? I thought I'd still better mention this even though I'm starting to appreciate more the ideas behind dark energy more after watching this video.

[@physicself]

Says it's "really, really hard to describe intuitively and may not, in fact, be possible" that negative pressure results from a constant energy density, then proceeds to explain it in a completely understandable and intuitive way... good on you, PBS Spacetime!!

[@kibromfesseha9960]

You lost me once you started talking about relativistic pressure doing the opposite thing that regular pressure.does.

[@pbsspacetime]

+Kibrom Fesseha Yup, and you're not alone. This is one of the hardest concepts in cosmology to grasp intuitively, and may be impossible. That's why I say "because math", although by itself that's not good enough. We will need to rigorously test the predictions of the mathematics.

[@kibromfesseha9960]

PBS Space Time At the end of this video you said that Conservation of Energy doesn't apply...Do the other laws of Thermodynamics not apply either for some reason or does Dark Energy only make CoE not apply?

[@nbartlett6538]

+Warren Knox Probably the universe is infinite, so it's just expanding into itself. Like Hilbert's hotel: it has infinite occupied rooms but can still accommodate infinitely *more* guests, simply by moving each guest in room N into room 2N.

[@2phalanges]

into

[@nts3208]

It's simple, negative pressure means expansion because that pressure is constant throughout the universe, so there is no difference between any two regions of the universe. Thus, there is nowhere for that pressure to equalize to. The relativistic effects of that pressure though is shown through math to have an anti-gravity expansion effect. There is no simile or metaphor that is adequate to explain this. All you need to know is that it happens and the math shows it happens. I guess I didn't say anything new.. so just ignore me. Accepting it without the need of understanding is very tough, but that's your best bet.

[@savcob6291]

How are we supposed to get to the bottom of something that is flat ?

[@levi12howell]

So perpetual motion devices are mathematically possible after all!! I always hated conservation of energy anyway Newton

[@dylanwebb2]

+Levi Howell Someone call Lisa Simpson!

[@realmetatron]

+Levi Howell No, a flat universe has zero total energy. This is well known in cosmology, so I think the statement in this video is incorrect.

[@falleithani5411]

+Levi Howell Technically yes, but only on truly massive scales in intergalactic space, and even in that context it may not be possible to harness that motion to perform any other kind of work. While we're still inside a galaxy, conservation of energy applies.

[@falleithani5411]

+Ilavenya I'm pretty sure that comes down to how one defines energy. But on an elementary level, galaxies are getting farther apart at faster and faster rates, despite continuously accelerating in the opposite direction via gravity. That is literally perpetual motion.

[@realmetatron]

Fal Leithani Energy is defined quite rigorously. The motion you speak of is not motion through spacetime, it is just the expansion of that which carries the galaxies with it. Still, the total energy of a flat universe is zero, because the positive energies of the matter, radiation and their gravitational energy density are equal to the negative dark energy.

[@georgerevell5643]

So fascinating! This helped me understand so much of my seeming paradoxes of the expansion of the universe.

[@willlastnameguy8329]

My only question is...huh?

[@miek127]

The answer is: 32

[@brachechs4911]

@@miek127 42*

[@efini_fc4276]

@@brachechs4911 yes, now it is, but not 4 months ago it wasn't. You are correct though.

[@JayDillon-mm6yv]

That's a metaquestion.

[@MDBowron]

Stephen Hawking has theorized in the zero-energy universe, which is based on the idea of the law of energy conservation, that the total of all energy in the universe equals to zero. What he gives as an example is a person wanting to turn a flat piece of land into a hill by digging earth/dirt out of a hole. The hill in its totality represents positive energy or matter, the hole being the inverse or negative version in volume of the hill represents negative energy or space. Hawking theorized that negative energy may be gravity which increases negatively in proportion to the amount of mass of positive energy or matter, the heavier something is the more gravity it produces. But I personally have a different idea. Current astrophysicists theorize that there is a substance called dark energy, which is said to be a repulsive force, that is increasing the expansion of the universe. They also have a theory of dark matter, or matter that is invisible and acts a binding agent or gravity to keep galaxies from falling apart. There is also the postulation, or idea, of most of the volume of an atom or particle being empty space, and this reminds me of the idea that only 5 percent of the universe is meant to have ordinary matter, the next 23 or so percent being dark matter, and the rest being dark energy. Now I theorize that given the ratio of matter to space in a particle or atom, it seems awfully similar with the idea of most of the majority of the universe being dark substances. Now if Hawking is correct that space is negative energy and negative energy allows gravity, how can we reconcile these opposing theories? Well what if space, negative energy, was dark energy and dark matter? If space is expanding, then space fits with dark energy being a repulsive force, but I don’t believe all the negative energy is repulsing in only one direction. Dark energy surrounds galaxies, and thus in expanding outwards, would also press upon galaxies and thus physical objects like matter or positive energy, this pressure leading to a multiplied or ‘dense’ although ‘dense’ is not really the right word, but an increased or maximized form of dark energy compression, which could behave like a congealed form of dark energy, and thus be mistaken to be dark matter. This repulsive force or dark energy upon these physical objects of positive energy would thus become the force of gravity. The maximized negative energy would increase the repulsive force, and thus increase the force but decreasing the pressure (as there is no physical matter) against the physical matter object, and this could be what we feel as gravity. The multiplying decrease of pressure being negative energy, would thus feel less the further away from the postive energy object, but would increase the closer you came to the physical positive energy object, which causes the increase of gravity and thus creates acceleration of nearby objects towards the positive energy matter. I also theorize that since space is within an atom or a particle for that matter, the fact that this space is negative energy or dark energy may explain something. What if the particle was basically a type of positive energy matter force-field around a body of negative energy. The negative energy or space pushes the positive energy/matter outwards so it doesn’t collapse from outside pressing negative energy or dark energy into a singularity, and thus causing that matter to collapse into a miniature black hole or something similar. The fact that the particle remains in a spherical shape is because the positive energy is pushed back and forth between the external dark energy and the internal dark energy, which is why a particle resembles a sphere when observed in a scanning tunnelling electron microscope. But isn’t a particle also a wave? How does that work into this theory? The equal force from the internal dark energy and the equal force from external dark energy makes the positive energy matter become the spherical shape, but if this particle was say in a more dense or less strong surrounding dark energy, the particle could expand and spread into a field flowing in all directions until reaching the force of dark energy, thus becoming a wave of probability. I believe that when this wave is disturbed by either increased dark energy forces or that enacting upon a nearby positive energy matter body, or is observed the wave can then collapse into a particle. Because the wave is spreading everywhere, the collapse of the wavefunction would appear to be random, and thus be made out of a field of uncertainty, but to me its like recording old analog TV static on a VCR and then hitting pause, trying to position where that next piece of static will be. It happens so fast and there are so many probabilities affecting it that it appears random. Now I want to talk about another topic that may be related: String theory and M-theory. Superstring theory theorizes (hence the name) that particles are made out of small slithers of waving positive energy/matter string. Now strings can appear as single strands like a piece of string, or can appear as a loop of string. Now according to M-theory built upon superstring theory strings can expand into sheets called membranes or branes for short, which to me could form into physical shapes, like perhaps a sphere. It has also been suggested in particle-wave duality that all matter or positive energy is made of vibrations. Now just as particles can expand into waves, I see a correlation between the string and the particle, and the membrane as a wave, call it a string/particle-membrane/wave duality or string-membrane duality. The particle is simply the membrane of a string spread evenly around the negative energy thus forming the matter/positive energy force-field. They say that strings vibrating in different ways can create different particles. Now here’s where something else comes in: The Higgs Boson. The Higgs Boson is the particle of the Higgs Field which creates mass of particles. Remember when a motorboat would travel through a large lake or sea and there would be drag created by say a skiier holding onto a rope connected to the boat? Well I believe that as particles move through this Higgs Field, they create a drag which causes the appearance of mass. Now there have been detected two particles of the same size but each with very different masses. Now how can this be? Well there would be a reason for the particle to drag through the Higgs Field, and this is energy density. Suppose the string or vibration that made up the same size but incredibly light particle was a very long extended vibration, like say the frequency of a radio wave. The same size but incredibly heavier particle would have a very high narrow vibration, like say the frequency of a gamma ray. The increase in frequency leads to an increase in energy density, and how that particle’s charge through relation with the photon, and spin with the Higgs Field and dark energy, leads to the different interactions of various particles. It’s all the same positive energy, just different packets of it with different frequencies and different sizes. Now the collapse of these waves into particles to me also has another application. If you don’t know, there is an intense debate between trying to link quantum mechanics (which is how particles interact and behave as bits of energy) and general relativity (which is about how gravity affects large objects like moons, planets, stars and galaxies). Now quantum mechanics says that when a wave is being observed, it collapses into a particular spot and hence becomes a particle. Now General Relativity says that objects with mass or postive energy, basically, warp the space and time (as time is also a measure of distance and distance a measure of the time taken to cross that distance) thus causing nearby objects to fall into the warp of space time and thus become attracted to the physical matter object. What if this wave affected by dark energy or a nearby mass of positive energy, was the same as the positive energy or planet or physical object affecting the negative energy containing the space time? Thus this would link the effect of General Relativity warping space time (what I call macro negative energy mixed with the Higgs Field), the same time how space time and Higgs Field and negative energy (micro negative energy and Higgs Field) causes the collapse of wavefunctions into particles? Thus this would link General Relativity and Quantum Mechanics regarding the Collapse of the Wavefunction, the former being simply a larger version of the latter, one happening on a macro scale, the other on a micro scale. I hope that explains things, and I hope it has helped you answer those questions. Now if I’m wrong or right, please let me know. I’d like to know. Peace.

[@JoshuaHillerup]

Wait, that smoothness of spacetime is only an approximation on a large scale. Doesn't that mean the negative pressure of dark energy should work differently on the smaller galactic scale?

[@nakanoyuko]

no

[@matisle119]

Yes

[@the.brokenhand]

Instead of bankers

[@dontquestionmyname5490]

i asked most of students in my class, about 85% of them want to be bussinessman or bank related jobs... no physicist or astronomer.

[@williamglover8108]

Don’t blame them. Society does not sufficiently value scientists. Spend 25 years of your life in education, and maybe you’ll get a job, maybe, that lets you continue doing science. But it will pay a fraction of what you would earn in finance/business.

[@jojolafrite90]

They got it.

[@jojolafrite90]

That sucks so much... :( Though, I'm not even surprised. That's what our dear leaders want.

[@mikechambers9129]

Matt, This is the single most lucid and useful 15 minutes on Dark Energy that I've seen. You may well be the best Explainer of physics since Feynman!

[@Premed1981]

You say at 11:30 that the law of conservation of energy no longer applies to an expanding universe. Does that also mean that the 2nd law of thermodynamics does not apply? Because this contradicts what you said a few episodes ago about "Heat Death is coming". Maybe it's not so inevitable after all?

[@facundorodriguez3315]

now they have the beta version of the second law of thermodynamics. Apparently it runs in all the universes, and is more stable than the previous version: "Entropy ALMOST always increases"

[@4798alexander4798]

is the universe behaving its way "because math", or is math behaving its way "because universe". got me thinking

[@ObsceneVegetableMatter]

+4798alexander4798 Math is a concept and does not "behave". So i guess "because universe" would be the least incorrect answer.

[@sinfuleldian9826]

I have a philosophy final exam next week, and teachers predicted this exact subject that possibly we'll be asked to write about. I'm thinking of it a long time ago, i think it's "because math," you see, the way Einstein predicted black holes, and gravity waves were purely "because of math," and gravity waves were recently discovered proving that Einstein, and more importantly, math, is once again correct, legitimate, solid, and pure evidence, and proof of how the universe work. It's always because of math, friend.

[@pcuimac]

Because universe is the correct answer. Math has been developed by brains that went through evolution. Our math fits the universe, because our brains addapted to reality (not D. Trumps). ;) There is no realm of ideas that exists independent of the universe. But there may be other universes we can't cross over into, connected only to us by theoretical models who explain ours.

[@garethdean6382]

+4798alexander4798 Well we can easily math ourselves up stuff that doesn't exist in the universe, so I'm guessing math is in charge here.

[@pcuimac]

+Gareth Dean What does "in charge" mean? Does a universe come into existence, because you bring up some math that describes it? I guess not. ;)

[@skroot7975]

Inflation inspires me to become a banker.

[@garethdean6382]

+Skroot Science or finance, inflation gets you either way.

[@enginkazanci4727]

Sir your closing line is epic, I think you know that only a few will really understand BUT you have increased that number by at least one 🙏

[@InkEyes]

If energy can be created out of nothing like how you were saying toward the end of the video (11:20) in an expanding universe, then we can't 100% be sure that the future of the universe will be a dark, cold and dead infinity spread out. What if the acceleration becomes so much and the amount of dark energy increases so much that some new phenomenon occurs?

[@commode7x]

+InkEyes Maybe instead of the universe being cold and dead, the acceleration could cause existing stars and planets, with active fusion and living civilizations to be torn apart by expansion waves, ripping through portions of their solar systems, annihilating their section of the universe at the quark level as their few survivors of the event look on with horror as the universe itself rips itself apart before their very eyes.

[@CaedenV]

+InkEyes The issue here being that Dark Energy is ... well... dark. We cannot directly see it. It does not directly interact with the physical 'stuff' of the universe. It is an energy in the universe that we measure precisely because of expansion. It does not produce heat or matter, it just produces more space-time. Too much space-time and not enough matter is the literal definition of heat death.

[@pedrohenriquemorais4979]

+InkEyes Or our universe will collide or run over another universe, so much shit can happen in the future.

[@andrewfrank7222]

The survivors of the Abrahamic religious world war will have to invent some measure of time travel and let us know.

[@luciferangelica]

Andrew Frank let's not. let's, instead, abandon abrahamic religion

[@muchograndeyolatengo]

What if the universe is expanding into an outside low pressure zone?

[@dannydetonator]

You mean you farted?

[@ruatsangawhite7261]

Well that could be possible...but it could also mean there is something else outside the universe... something existing outside the universe before the big bang

[@d3neu]

Obviously beyong earths atmospheric space contains less gravity compared to earth's . But gravity from planets or blackholes vortex / spin holds different density.

[@miketaylor4979]

If the whole universe is spinning around its centre would this not create dark energy?

[@baxtermason6909]

...don't look at me...I'm just a knuckle-dragging engineer...;-)

[@zephilandevol]

I’m not sure how that would create dark energy. But if the whole universe is spinning, then that violates the copernican principle because then there would be a special point. and not only that but general relativity from what I read is machian. For there to be some force that’s felt when the universe spins, it has to be spinning relative to something. But spinning relative to itself? That doesn’t make any sense

[@Faizanmohammed]

​@@zephilandevol yep that thing makes no sense

[@bazookaboss332]

Ok, this is the first video I understand... a quarter of. Finally!

[@zatar123]

11:36 if the law of conservation of energy does not apply in an expanding universe, and we are in an expanding universe. Dosen't that mean that over unity machines are theoretically possible?

[@madguz19]

This dude is so smart I almost understand what's he's talking about.

[@stuntman290]

madguz19 you’re actually quite smart yourself for noticing that too 🧠🌍

[@bigsmall246]

@Deep Moticons which society brainwashes people to think they're dumb?

[@alextoulan3635]

Could this energy gained be coming from matter/energy entering our universe from outside of it?

[@mockingbbirdkilla1771]

Nah dude. Its from the ether. Or higher/lower dimensions. Probably.

[@mykofreder1682]

The reality is space time is expanding and you can write equations about it but it may just be an unknow state of space time that is and has to be accepted. If the Universe were once a dense plasma it would have to been like the interior of a black hole and have no future. This primordial black hole was torn apart by this expanding space time that grabbed ahold of every particle and accelerated it to a speed to overcome the gravity of the largest and probably densest black hole imaginable. It flashed over into atoms once the density became low enough (the poorly named big bang) and it continued to pull these atoms apart at a speed high enough so it would not reform into a black hole. When the density became tolerable for universe type things like stars and galaxies it slowed down and is currently expanding at a speed we cannot perceive locally, but the fact is the local space around us is either stretching or adding more empty space all the time and carrying us farther from item who's gravitational effects cannot overcome it. There may be math behind it but nothing more interesting than a very dense plasma (without expansion) or near zero density fundamental particles (with a single initial expansion rate fast enough to tear a black hole apart) would exist if this precise recipe of expansion was not followed, it does not appear to be luck or chance.

[@ruatsangawhite7261]

That's highly hypothetical,yet very well be possible... but I don't think they are favoring in possible forces from outside universe in the equations

[@mockingbbirdkilla1771]

@@ruatsangawhite7261 Well, no one really has quantum mechanics figured out either. There is definitely a way to go faster than light without using massive amounts of energy. We just don't know the cheat codes to this universe yet.

[@ramlydiosa]

Hey PBS That part where the negative pressure produces a positive pressure effect (correct me if Im wrong) goes like this: 1. A positive pressure will only happen when the outside of where this pressure is coming from is lower 2. From point 1, then it means that the more mass there is on one portion, the higher it will expand (higher pressure) than those which has less mass (lower pressure) even if the overall energy of both of these regions is the same (meaning, higher will expand but not very quick and the region with lower pressure also expands on the same rate as the one with the higher pressure). But the universe as we see it is flat. If one region with more matter expands faster than that of less mass, then we will see "bubbles" or portions that are above the flat plane because it expands faster than those around it. 3. So because of number 2, we have to add a constant so that the expansion vs contraction will be equalized/negated. This is Einstein's constant. 4. Going back to the original equation where theres a negative 4 in there, If we add it to the mathematical equation, it would seem like the einstein constant will need to be positive so that it should cancel the negative sign in the 4pi G there. 5. We are then presented with an equation that says "gravity is a pulling force hence negative and dark energy is a pushing force hence should be positive." But the nature of the whole equation itself says that the force of the dark energy should come in from itself. So that cosmological enistein constant is actually an effect of dark energy's own density and pressure 6. To simplify the equation, we need to assume that matter has very very minimal effect (hence we assume that matter will be diluted in the future and we are left with more and more empty space) 7. From the equation, we are to decide whether the expanding factor of dark energy is because of it's density or because of it's pressure. In this regard, density should be positive because since the universe is flat (again) then a positive density is needed otherwise, if the density is negative, we will have a curved space. Meaning, dark energy + matter is helping together to flatten the universe. Hence, it should be positive (like mass is positive) 8. We are left then with the "pressure" that should cause the space to expand. Is this pressure positive or negative? 9. Going back to the equation earlier, the only way that we would have a POSITIVE answer after the negative sign (to describe a force that is opposite gravity) then this pressure should be NEGATIVE. 10. We do not know how that should work but algebra is algebra. In the equation, to cancel the negative sign, you have to make P a negative sign. BECAUSE MATH! -even if that means that a negative pressure, in reality, should be an inward pressure and not an outward one. So we just made assumptions that since the universe is expanding, and a negative pressure should be an inward force (which is counter intuitive) we just say "oh well, I dunno... the eqaution shows it should be, so it is. BECAUSE MATH" . OMG!!!!

[@lorenbooker9486]

If dark energy and gravity caused by ordinary matter are opposites that are fighting each other then shouldn't there be a region of space around a galaxy where the two are in equilibrium? And if such a region existed would that mean that in that region neither gravity or dark energy exist at all? And if that were to happen, could we even travel past that region?

[@garethdean6382]

+Loren Booker A balance doesn't mean an absence. The air pressure inside your body and outside it balance, but that does not mean either exist and you're in empty space. The balancing point does exist, but both gravity and dark energy are there.

[@lorenbooker9486]

I can understand the logic there. I may just be overthinking this but has anyone ever discussed what happens at that point where the two are in equilibrium? Surely there's some cool physics there.

[@garethdean6382]

Loren Booker As far as I'm aware of not much attention has been paid to the subject mostly because dark energy itself is still such a new concept. We're only just now getting a handle on how dark energy behaves when it dominates and anything involving gravity tends to be quite tricky. Perhaps in the coming years...

[@sheepwshotguns42]

please someone help me with this, this has eaten at me for years! what if instead of it being a force, dark energy is a byproduct of something else? what if at the smallest levels of space and energy, at planck levels, there is a virtual particle that comes in and out of existence, a borrowed energy that has a knowable minimum value? the uncertainty principle says we cannot know the momentum energy and the position at the same time, so what if this set energy creates space itself as it moves? we cannot know its location because the location itself is coming into being. once the space is created it no longer exists as the virtual particle. this byproduct, this generation of space, would create a negative pressure throughout the universe. could this be a viable explanation to dark energy?

[@saeedbaig4249]

That idea's addressed in this Veritasium video (i recommend watching the whole thing, but you can just watch from 0:00- 1:22 and then from 6:20-7:07). Basically, when you try to actually calculate the energy density of space based on the idea of virtual particles, your prediction is thousands of orders of magnitude off of what the experimentally-observed energy density of space actually is. That's kind of a problem for the whole dark energy=virtual particles idea.

[@sterlingavellino8139]

Ron Walsh People thought of that. They tried to calculate the total energy of Dark Energy using that. They were off. By a lot. Like, a lot a lot.

[@ericeaton2386]

Wait, you didn't actually link to the video, the timestamps just take you to this pbs video. I'd be really interested in seeing the veritasium video, do you have the name of it?

[@funkyplasmaman]

dark energy is just space/time outside the presence of local matter and no different from gravity which is space/time in the presence of local matter

[@janey6921]

I fell asleep watching KZbin and woke up here. Someone explain.

[@Jenniferab32]

Lmfao

[@fernandoxavier6392]

Antisleep properties of dark energy.

[@googlekullancs564]

@@fernandoxavier6392 🤣

[@rayoflight62]

From where the energy comes? Maybe from nowhere. The law of conservation applies to a Newtonian universe; in a relativistic universe it can be provided from the curvature. The more the Universe expands, the more is filled with Dark Energy. Wow. You left me speechless...

[@przemysawszymusik1516]

Is it possible that the concervation of energy still works in expanding universe? If vacuum has constant energy and the more vacuum the more energy maby its comming from matter. Think of it that way: the universe is cooling since it began. Cooling means emiting photons. Photons lose energy when they travel through expanding space (they become redshifted) So maby thats the energy sorce for expansion. And why the expansion is accelerating? Maby its just like in Hawking radiation of black holes - the black hole emits more energy expanencialy. If in the future all matter will end in black holes and then gets emited as photons then after infinite time these photons will lose all energy (wavelengh = infinity) which means they will stop existing. In that universe there will be only vacuum. And since you have just vacuum its immpossible to tell if the universe is expanding or not. And that point in time could happen sooner than in infinity. If energy is not infinitly devisible but insted comes in packets (probably true)

[@OMGanger]

+Przemysław Szymusik I see what youre saying. Perhaps the energy gained by an expanding universe is mechanical energy lost by particles. If im not mistaken, however, the density of matter in the universe is too low to account for the negative energy.

[@przemysawszymusik1516]

+Sebastian This is just a wild gues. Im not a physicist. But the matter density is too low right now. In the past universe was more matter dominated. The energy from matter decay adds up. Think of it as a melting smowman analogy. At the beginnig snowman is big and there is little wotar around it. But the more it melts it gets smaller and our system becomes water dominated and gets more and more surface

[@AlcyonEldara]

+Przemysław Szymusik : nope. Let's say that the total amount of Energy is E. given enough time, since the Universe expands forever and faster, it will create more energy than E.

[@sigbjrn4535]

+Przemysław Szymusik scienceblogs.com/startswithabang/2011/12/02/dark-energy-accelerated-expans/

[@ChongFrisbee]

I also wandered about this. The missing energy from red shifting and appearing energy, plus my personal desire to live in a constant total energy universe. I would also appreciate more discussion on this topic.

[@robfunkhouser3793]

Could a black hole absorb dark energy? Being that dark energy is at a pressure constant throughout the universe?

[@sukritmanikandan3184]

Whe don't precisely know what dark energy really even *is*, so until then your answer is.... idk

[@ruatsangawhite7261]

Could it even interact with it...well anyways no one knows...atleast not now

[@leifharmsen]

"Anti gravity" is like saying "anti low air pressure" rather than saying "air pressure". 'Dark energy" is just gravity and gravity is just differences in time speed, a time speed gradient. Empty space is at the top of the time speed gradient, black holes at the bottom. Gravity pushes from empty space EVERY BIT AS MUCH as it pulls from masses. Empty space pushes because of the squeeze of time, black holes pull because they have all the time in the world. Mass falls from where time is short because it goes so fast (empty space) to where time plentiful because it crawls (eventually a black hole). That's an explanation of gravity that doesn't require some mysterious seperate "dark matter" that nobody can find to behave as it does. Gravitational potential energy is just the workings of matter accelerated to the faster speed of time at higher altitudes. That acceleration takes energy which is why it takes work to lift things up (ie. push things toward empty space).

[@channelbree]

Mind blown.

[@oguretsagressive]

Not all, every black hole originated sometime. And besides, if you would've used your idea to calculate the expansion rate, your calculations would diverge from observation. Try it ;)

[@jonathanjones770]

How have you confirmed all of this?

[@frede1905]

Oh wow, I knew that the pressure due to dark energy was minus the energy density. But I didn't really know why. Now that you explained why (by the fact that it requires energy to expand space), it made so much sense!

[@Xenro66]

Hmm, so if an expanding (and relativistic) universe can forever destroy or create energy, that begs the question "how much energy can the universe destroy or create?" I'm guessing it's infinite, however, I don't know. But one thing I do know is that if the conservation of energy doesn't apply...... *PERPETUAL MOTION, BITCHES!* :D

[@garethdean6382]

+Xenro66 It is infinite, but it follows rules. You can't just pull energy out of nowhere and in fact energy is created in the most useless manner. Perpetual motion indeed, but it's everything away from everything else into a cold, dark, empty future.

[@Xenro66]

Gareth Dean Oh well... The idea was fun while it lasted :(

[@MrTripcore]

+Xenro66 The conservation of energy still applies to an expanding universe because the peak energy of the big bang has not yet been reached.

[@MrTripcore]

+Gareth Dean "You can't just pull energy out of nowhere" That's debatable when it comes to the very first big bang event. Just sayin'.

[@garethdean6382]

Tripcore That's true, but again, debatable. 'From nowhere' is the last ditch option. Science seeks a cause,, a reason, an origin; some law that gives rise to things.

[@GameKraken]

Odds are Matt won't see this but here goes: If dark energy has an anti-gravity property as described, could it be a substitute for negative mass/energy, what is pretty much required for a functional alcubierre drive? Or am I missing something?

[@bullbobby92]

Gaming Kraken well you’re commenting on a 3yo vid so you’re probably right

[@souravsaha4747]

how can we proof that law of conservation of energy doesnt works in the mighty universe

[@lonestarr1490]

I guess the best way would be to produce dark energy in a laboratory and out of nothing ... somehow.

[@smrtfasizmu6161]

It is way more difficult to prove that it applies. If it doesn't apply than just find a case in which it doesn't apply. I am more worried about psychics since without the law of conservation of energy entire psychics is broken.

[@OpieJohansen]

"A negatively curved, hyperbolic, hyper-plane!" What a great combination of words...don't know what it means, but it is too awesome! PBS Space Time is uber-good!!

[@Ashadow700]

Uhhhhhhhh...... the law of conservation of energy no longer applies?.... uhh... I don't like this... I don't change.... energy should stay the same, this makes be scared....

[@GulfsideMinistries]

One person's modus ponens is another's modus tollens.

[@anSealgair]

A key to understanding physics is to leave assumptions at the door. Let them go, bye bye assumptions....

[@ragnkja]

Red- and blue-shift of photons doesn't conserve energy either, and since distant objects tend to be redshifted, that means quite a lot of radiation energy is lost in the expansion of the Universe.

[@IIIIIawesIIIII]

Nillie But the energy is transforming into space, or time, or mass or order or not? I mean, information can not be forever lost, or created out of nothing, or can it? Because that sentence really shocked me as well... :P like "wtf, magic is real?!?!" Can you really turn nothing into something without at least creating a negative of itself that compensates for it? Is this whole existence just a malevolent pseudo-order with fake rules that are valid just whenever it wishes to? I mean, turning space into energy - sure, space is not nothing! But NOTHING? I'm seriously worried :0

[@ragnkja]

IIIIIawesIIIII I agree that it is a bit harder to accept the idea that energy can be created than that it can be lost, but apparently both are possible in our Universe if your system is large enough.

[@scottvelez3154]

Aliens probably use dark energy as fuel for their spaceships, while we don't even know what dark energy is.

[@sinfuleldian9826]

+Scott Velez We'll get there, eventually.

[@mellowfellow6816]

+Scott Velez They probably use it to brush their teeth.

[@TheCopelandr]

+Melo Boy I laughed so hard at this

[@delawarecop]

+Scott Velez Those same aliens probably use atheists brains as toilet paper - hence why alien abductions exist:)

[@painstruck01]

+delawarecop they use Christian brains in lieu of FRIENDS reruns.

[@claytonportell5922]

Inspire enough smart kids to become scientists instead of bankers, lol. I went to college for physics and now I'm a banker. I did the exact opposite lol.

[@harshapathare9380]

I am 12 yr i understood verry well

[@Tadesan]

Man, fuck you.

[@dannyoman7219]

Stretch ya mouth with ya little fingers sideways and say my daddy is a banker and he banks all day

[@calvinphelps8786]

Must’ve had negative pressure in your life...

[@TheEdge92]

@@calvinphelps8786 x;DDD HAHAH

[@marsauloro7]

Last 3 minutes of your speech is devine. Less bankers more cosmic lovers

[@fotaras710]

What if the universe is not expanding, but actually compressing on itself negatively

[@PatatjesDora]

Isn't that still expanding?

[@fotaras710]

@@PatatjesDora well technically yes, but actually no

[@userjames2009]

The universe IS shaped weird due to the lack of matter. We just think it is normal. 4D Minkowski spacetime is supposed to be symmetric; space is supposed to be 2D and time is supposed to be 2D. Quantum physics works fine in 2D space. The weirdness is that the universe is made of bits of quantum loop gravity spin foam having 3D space and 1D time due to the lack of matter needed to balance the symmetry of the space & time dimensions. When there IS enough mass in an area to produce 2D space, you get a 2D space black hole that only has surface area, where all the mass is contained in the very high density high entropy 2D surface, and no 3D internal volume at all underneath the 2D surface.

[@pleasesubscribe415]

Brilliant

[@pleasesubscribe415]

Pray with me: Our Lord the Sun of God who art on heaven, HOLLOW be thy name. Thy emptiness come, thy will be done, In the earth as it is in space. From nothingness to nothingness. From emptiness to somethingness. Nothing is nothing. Everything is something. As above, so below. Holy hollowness. Particles spawn into existence by the will of thy Quantum. From darkness our Lord create light. Particles of emptiness radiate upon your face. Wave-Particle duality, hollow empty holy Trinity. Flat inflating universe expanding effortless into emptiness timelessness nothingness Multidimensional omnipotent eternal infinite Nothingness. Forever and ever inflating Infinite temporal duration Creation of nothing Space-time continuum. Nothing lasts forever and ever. Hollow empty fluctuations of Quantum. We feel the pulse of omnipotent strength. The radiant eternal hollow will of the creator The black hollow hole of hollow stretched time, the infinite eternal vortex of nihil Hollow dark energy Hollow dark matter entangled in thermodynamic chaos of cosmos. Crystalized quantums of infinite nothingness Reconstruction from deconstruction. From darkness create light. Enter another flat sphere Complete the emptiness.

[@FruitOfTheSpirit]

Cybernetic Heat Information That is very interesting, I've never heard spacetime described that way. Wouldn't your explanation imply that the 2D space blackhole also has 2D time -- meaning any conscious life that fell in could theoretically travel backwards in time up to the point of entry into black hole, and even "sideways" in 2D spacetime to various other timelines wherein said individual reached his or her present location through a different set of past choices made?

[@blackhawkX02]

Dark energy is a real physical thing? then what exactly is the definition of energy?

[@michaelsommers2356]

In a sense, energy is an accounting trick. Read the fourth chapter of the first volume of the Feynman lectures; it's online somewhere.

[@CancelYoutube026]

Cushion Craft (1963) already had THE flying car, I don't know why people still searching for Anti-gravity, and why highways are still build.

[@McGhostluvin]

Maybe the universe just naturally wants to be flat. If mass/gravity condenses and warps space, perhaps dark energy is nothing more than space "recoiling" to maintain its flatness. That would explain why DE seems to create expansion within our universe. Maybe it's the universe just trying to be as flat as possible (not trying to personify the universe)

[@nitpoon7982]

as usual it's a bunch of computer Imaging and maybes and probably and what ifs when in reality they don't even have a real picture of the Earth all they keep showing is a perfect Blue Marble but Neil Degrassi says it's not a sphere it's a pear shape either way NASA is a bunch of b*******

[@StiloNautica]

+McGhostluvin is the universe a he or a she ? :-)

[@McGhostluvin]

+StiloNautica Ima go with an IT

[@vailias]

+McGhostluvin This isn't a bad line of thought. If you flip the idea of "mass warps space" into "warped space creates mass" then it should make even more sense. Spacetime unwarping toward an even density would give the expansion effect, and any additional recoil, as you mention, would be effectively an anti-gravity effect. Also it would fit with an overall entropic behavior.

[@McGhostluvin]

+vailias right!? I love the visuals for these videos. They often bring me to ask questions I wouldn't normally have thought of. Really brings these ideas and theories to life. I love these videos

[@sunahura]

People who dont believe in space budgets, should stop using cell phones.

[@user-tn7jr9bt5t]

whynot that i am opposing space budgets butjust why?

[@jonwatson6918]

It's interesting that in the past month or so I've come across some three or four views that dark energy doesn't actually exist. It's neither been proven nor observed. I suspect in 5 years or so we'll have to re-evaluate what we know of physics.

[@likesrush]

The cosmological constant. I've fixed many chemistry experiments in high school by postulating that very thing, thus proving that whatever my results, they are explainable to be a perfectly correct answer, thus deserving of A+ grades on those experiments, even though my answers were wrong.

[@MAl-xz7lc]

PUSH AND PULLING EFFECT.. IF WE ONLY KNEW HOW TO FIGURE IT OUT.. We WILL HAVE ENDLESS FREE ENERGY 👈🤓..

[@perfectwhine742]

3:04 I'm totally wet

[@originallycalm8288]

The universe expands until everything is completely and evenly nothing. Then dark energy, negative pressure get so high... Big Bang again?

[@charliefields7692]

Elastic force seems like the perfect way to define negative energy. I love the analogy of rubber bands pulling inward that was used to define negative pressure. It’s almost like because positive force pulls outward while negative force pulls inward, infinite expansion can be created. If the relativistic effect of negative energy mathematically has to be opposite to positive energy, then wouldn’t the volume of positive energy in a given space dictate the velocity of expansion in that given space?

[@joshuapenner2164]

Everything thing he just said solidifies the existence of a Creator. How can anyone say this organized, uniform, and fairly stable universe came out of an extremely volatile state? I am a Christian but this statement isn't biased. This statement is based on science.

[@FruitOfTheSpirit]

Cosmological constant is fine-tuned to one part in 10^120. If smaller, universe collapses immediately after big bang due to super strong attractive force. If larger, no clumping of galaxies possible due to immensely powerful repulsion. I read an interview with a PhD physicist who said the odds of this level of precision by blind chance are comparable to going into outer space, throwing a dart toward the earth, and hitting a randomly-placed bullseye *smaller than the size of a single solitary atom.* You're throwing a tantrum about conceptions of beauty...how about the beauty in that life should be impossible, but it isn't, because we have a Creator who loves us. (Note I'm not throwing a religious text at you but am citing established science that necessitates a universe finely-tuned for life). That's beauty friend.

[@FruitOfTheSpirit]

Of course we can only measure things when we exist. Does that really need to be stated? It has no bearing whatsoever on the assertion that, based on verifiable scientific observation, we should not exist but for our universe having been designed to be hospitable to life. Where there is design, there is a Designer by definition.

[@princejellyfish3945]

Chris I No, you're calling it a design, which yes by definition means there must be a designer. Your only argument is semantics. And if you believe there is a creator who 'loves' us(love: a human, chemical reaction) and all this was designed because this world is absolutely perfect then what make exactly makes this world perfect? There are infinite other possible perfect universes that we don't exist in.

[@kirkjohnson2924]

Actually the Bible states nothing that would rule out life in the universe. In fact the Bible has a few texts that seem to be pretty good indications of life in the universe.

[@kirkjohnson2924]

Also pretty hard to believe everything came from chance. What happening randomly could possibly create information? If I jammed my hands on a keyboard randomly I probably couldn't even write a child's book much less a functional computer program that could replicate itself... No disrespect to people who may see this but I had a miracle worked in my life and I just wished people would be open to the truth because the other side of this life is either infinite happiness or being thrown into fire turned to ashes and gone forever. Peace ✌️

[@शिवभारत-भ5थ]

Most clear episode doubt clearing

[@madincraft4418]

This is the future of PBS.

[@David-wc8ze]

I listen to these at night. They are fun and informative

[@ManyHeavens42]

We all got it, you either push your pull , Don't ever stand behind me, I've seen it Done , Even to me .May the force be with you! Wait you can do Both ? Same Power .

[@cridr]

the answer to the last question in the last minute is gold ! great work !

[@roryblake7311]

Aging has already been reversed. I'm working on anti-gravity, now! 😇

[@patientestant]

Why study physics? I doubt I will ever understand this enough to contribute to these fields of study. What is the point or purpose? To transcend earth and play in the cosmos! It is still amazing in our imagination! Thank you for the videos.

[@p.kristofiak45]

One of the best posts for me

[@RupertFoulmouth]

I love these videos!!!! You make me feel smart without forcing me to actually learn anything.

[@josh_7123]

kinda happy that i understood this

[@mustaphabiyabi4701]

wonderful explantation !