Are Virtual Particles A New Layer of Reality?

[@JasonBrightIndeed]

After a lot of these videos I'm starting to think that the Heisenberg Uncertainty Principle is the main antagonist in the series

[@yvesgomes]

It's breaking my brain, bad.

[@Quizzingisfun]

If only he didn't invent it...

[@davidroberts1689]

Heisenberg spent a lot of time doing the math just to get back at us.

[@paulmichaelfreedman8334]

Heisenberg, in any form, is a badass. Shares the top spot together with Entropy.

[@paulmichaelfreedman8334]

@@davidroberts1689 You're mistaken. This.......is not a meth crystal...it's a time crystal!

[@dmullins301TWM]

Matt, you and this channel are perfect together. As a layman and largely uneducated regarding these topics, PBS Spacetime has really made me appreciate both the wonderous nature of our universe and the many great people that have worked so hard to gain and share the knowledge. You guys are just amazing!

[@vladdangel]

How do real people sound like paid commenters so much on youtube? "I thoroughly enjoy this video, you are both an excellent creator and your videos are easy to understand." comes up so much and I don't want to believe you're just getting paid to post... although that's occams razor for you to just accept that you and all the others are.

[@stevenstark-com]

@@vladdangel Hey, if it's fake then good on the bot, I support our A.I. overlords!

[@dmullins301TWM]

Nope, fellas, I have degrees in both English and law, so proofreading prior to hitting "send" is a habit. I am horrible at math, but that doesn't prohibit me from being good at what I do besides that.

[@mickrussom]

as a layman. (translation, as an easily mesmerized and hypnotized moron sheeple who will believe anything framed as "true")

[@jeffvader811]

@@mickrussom A conspiracy theorist. (translation, an easily mesmerized and hypnotized moron under the impression that everyone else is an easily mesmerized and hypnotized moron)

[@atf300t]

QFT in a nutshell: The only things that really exist are quantum fields. Real particles are perturbations of those fields. Virtual particles represent potential perturbations of those fields. Virtual particles are useful to model interaction between real particles.

[@Zeegoku1007]

@@RubbittTheBruise Exactly !

[@pierfrancescopeperoni]

I would say that quantum fields don't exist either, being just models themselves. It seems that only information needs to exist, whether it is represented as something in space-time or not: any "physical reality" is probably only a representation of information, a "way" in which information is "stored".

[@piotrjuszczyk1]

Third sentences seems not good for me. Why potential? Maybe this peturbations are real.

[@thesoundsmith]

You got it. (Or at least, WE TWO agree...) The ONLY thing that actually exist are the q-fields. It's all we need to have all - this...

[@ikaros4203]

@@pierfrancescopeperoni This universal hard drive sucks, the past always disappears and forgotten :/

[@ougintoga7195]

I feel like a character in a video game trying to understand how the game was programmed

[@thesoundsmith]

That may be far more accurate than you think, except I see no reason for us to NOT have a significant degree of free will/self-determination. (A 5/D being could see the entire timeline like a book, but we created our decision-tree part Planck-clock by Planck-clock.)

[@cristianm7097]

@@thesoundsmith The dimensions might be "nested" such that a N+1 dimensional being can observe N-dimensional beings.

[@Machistmo]

You are

[@張於哥]

Yes you're right, we live in a simulation just like characters in video game, simulated by higher dimensional creatures. But some of us have consciousness that is directly connected to the body of that higher dimensional creature.

[@technomage6736]

Star Ocean: Til The End Of Time

[@Toddawaddles]

Sitting back and taking in that THIS is where we are when it comes to physics modeling is absolutely insane. What a time to be alive.

[@slkjvlkfsvnlsdfhgdght5447]

indeed. all of those statements like "born too late to explore X, too early to explore Y, just in time to explore Z" are just wrong

[@invin7215]

Watching Space Time sober: "What?! That hurts my brain!" Watching Space Time slightly inebriated: "Well of course. That makes sense."

[@hakan6705]

Invin And watching really intoxicated, Matt’s voice will make you sleep happily knowing he will take care of the universe.

[@pilotavery]

Yeah drunk didn't make me understand this more, LSD did though

[@ximecreature]

It actually has a name. It's called the "Ballmer Peak", a comical exaggeration of the famous Yerkes-Dodson principle. Keep it balanced !

[@reeeraaaw]

I'm in a constant superposition of brain hurt and understanding. My wave function collapses when he cracks a joke though

[@DialecticRed]

reminds me of when sometimes when I take my ADHD medication and get into a hyperfocus state I will spend like 8 hours on a project, feeling as though I can see the matrix numbers and everything suddenly has a refreshing clarity to it, and I work so quickly and don't stop for breaks, because I must finish what I started. But I will come back the next day, and it will all work... but I have absaloutly no idea how. And when I try to understand it I get a headache. It's like it was made by another person, much more qualified than myself. Unfortunately that hasn't happened in a long time, but I hope it happens again because it is nice when it does.

[@thejesuschrist]

Your videos always make me question reality. I love it! Thanks!

[@BattousaiHBr]

username checks out.

[@william41017]

But I thought you invented QM

[@pronounjow]

Hey Jesus!

[@godwho5365]

I see you everywhere

[@godwho5365]

@Ix Suomi Jesus Christ

[@Toddis]

Its the simulation making the program more efficient, this way the computer doesn't have to render particles when they aren't being observed, freeing up those cycles for things that are.

[@Axodus]

This is why I love the internet, I can come to learn things about the quantum field and virtual particles whereas if the internet didn't exist I'd probably be reading literature.

[@jamestodd51]

@12 34 indeed

[@agentxyz]

except that ultimately cat videos have brought everyone here

[@1Plebeian]

ew.

[@vogelvogeltje]

@@1Plebeian ew you

[@andreascj73]

"Try increasing your screen resolution ..." Best comment today.

[@davecool42]

“But even that description is way too physical, and Australian.” 😂😂

[@madnessbydesignVria]

That cracked me up too...

[@RoboBoddicker]

They said the same thing about Olivia Newton John....

[@jahellen]

@@RoboBoddicker I will never forgive you for posting that joke before I did.

[@madnessbydesignVria]

Copydot, Well played, Sir. Well played... :)

[@maskedman6664]

When in doubt...just dive into a KZbin hole

[@LeoStaley]

Tell us more about lattice field theory.

[@kendomyers]

Lettuce field theory is better. Its where they grow salads. Waka waka

[@evalsoftserver]

I am developing a Phase Field theory for explaining and unifying Quantum and RELATIVISTIC PHYSICS

[@mosemusica]

If the math of virtual particles accurately describes scientific observation, it seems they are quite real to me even if they aren't used in other types of QFT. Maybe there is another layer here that we have yet to understand that these virtual particles are signaling. I love the ideas of David Bohm and his implicate order - I wonder how this concept of virtual particles relates with that?

[@schmetterling4477]

It doesn't.

[@wangtoriojackson4315]

They asked me what I know about Virtual Particle Physics, and I told them a have a virtual degree in Particle Physics!

[@LuisSierra42]

Amazing

[@TheFlipside]

I'm genuinely proud of myself for successfully following the whole video

[@neilbedwell7763]

teach me sensei

[@MrMichaelFire]

Flips_Bad .. That was because it was very simple and non-mathematical.

[@marcustrevor1883]

@@MrMichaelFire To actually truly follow the video you must know the maths behind it though.

[@UniversalJunkie]

Excellent!

[@nehajbabbar6043]

Okay PBS spacetime blows my mind yet again

[@Tacticslion]

9:10 - "I'm SO EXCITED to be a particle!" 9:20 - "Meh."

[@vishalmishra4408]

In Quantum Field Theory (QFT) the primary construct is a field and therefore not just virtual but even real particles are just a perturbation in it's unique quantum field (e.g. electron field). Since we call the real ones *particles* so the virtual ones are also called *particles* although some properties of real particles can be missing.

[@plasmacrab_7473]

I seriously can't find it possible for people to actually understand this, let alone discover it... yet I keep watching. This channel is amazing.

[@trulucy]

I found you two weeks ago PBS Space Time and this channel is great. Very, very interesting subjects. Some things I’ve wondered about and some I didn’t know I should wonder about but I have learned so much even when I don’t understand it all. Thanks!

[@AnarchoAmericium]

“Every particle is an unnecessary defect in a smooth and featureless field.” - Brian Skinner, Samuel Beckett’s Guide to Particles and Antiparticles

[@Verpal]

In a smooth and featureless field, the idea of smooth and featureless field would not exist.

[@freediugh416]

@@Verpal of course it can

[@animistchannel2983]

I would have to modify that description to: "Every particle is a necessary deformation of a constantly reverberating field." That would at least describe reality as it actually exists and functions.

[@freediugh416]

@@animistchannel2983 didn't the video say it is not reverberating constantly though? And why would it be a "necessary deformation"?

[@Verpal]

@@freediugh416 I was trying to make fun of the fact that organism capable of conferring meaning does not exist in a smooth and featureless field...... but nvm.

[@Sheehan1]

There is poetic beauty in the mathematics. But I’m ugly, can’t do maths and I hate poetry.. But I love the show lads!

[@MrCHINBAG]

You are sexually attracted to the presenter?

[@aaaaaaaa6685]

MrCHINBAG idk about him but I definitely am. No homo 👌

[@GSPV33]

Don't speak of yourself so badly. Treat yourself like you would a loved one you're responsible for caring for.

[@agimasoschandir]

That you hate poetry is poor, 'Tis a pity math is not your fit, But cheer up laddie and have another drink, for Ugly is virtual to the eye of the observer You must admit

[@matheusbarbosa700]

@@agimasoschandir hahaha nice rap

[@merinsan]

I just got a new understanding of Hawking radiation. I always thought it was due to virtual particles. Thanks Matt!

[@voidisyinyangvoidisyinyang885]

You might want to check out what Roger Penrose has to say about Hawking radiation.

[@lucast.6474]

I remember discussing these things loads in Uni. There are many interesting discussion to have about whether a virtual hole particle is a valid thing and whether a lack of something qualifies as much in being a thing as presence of something. Or whether it makes more sense to say that an infinite, weighted amount of interactions are happening or a particle just goes undefined for a while and emerges in a random state

[@wesleycook916]

Love the burn on the end of the video!! Great delivery! Love to watch all the way to the end to see what crazy comment you answer!

[@Recordatio]

It's really great to see how strange the universe is and really strange to see how great it is.

[@SatyaVenugopal]

Missed chance to have a paradox in the title: Are Virtual Particles Real? =P

[@Asdrubale88]

Il Re è nudo. The king is naked.

[@beri4138]

It's not a paradox it's just a pun

[@blacktimhoward4322]

Glad they didn't

[@andrewmartin2321]

layperson: Do they exist? scientists: Kind of, but probably not while we aren’t looking at them.

[@ThePdeHav]

Harry Stapp’s Transactional Interpretation is really helpful when thinking about VPs

[@Binyamin.Tsadik]

Really cool idea that started with Fourier analysis: All signals can be thought of as a superposition of waves. So this superposition of particles forming a single signal is not that far fetched.

[@jessstuart7495]

Are individual scattering events a superposition of weighted (by probability) all possible interactions? Or, does QFT only predict the "average scattering" over lots of events ? Is QFT a "stationary process"? Time Average = Ensemble Average???

[@antoniusnies-komponistpian2172]

Oh hi you're here :D

[@MichaelOrtega]

Virtual Particles don’t virtually exist

[@zeta1ret]

...virtually speaking of course.

[@Mike-rt2vp]

Did a software guy named these particles?

[@sasshole8121]

They exist period.

[@zacharyhutchison4006]

Plot twist: All particles are virtual, we're living in a simulation.

[@davidpatterson9770]

instantaneous energy pulled from the void to complete the calculation... SIMULATION???

[@quahntasy]

Brain.exe stopped working. Quantum meets inception.

[@DaKILLaGod]

thats beacuse updates broke it :-D

[@mrpedrobraga]

The best part of the video is the end, where he always manage to say "spacetime".

[@richardoh419]

This video is amazing, thorough, and precise. Easily one of my favorites! Thank you for making these trustworthy and precise videos time and time again! There are so many other online sources that make exaggerated or plainly ignorant claims and thereby misinform the public. Spacetime, you are the best!

[@lewdcharizard9902]

13:13 Are Virtual Particles A New Layer of Reality? nope.

[@puskajussi37]

Why is the PBS theme/logo/thing playing faster in the end? Time dialation? And yeah, I noticed.

[@at-least-you-tried]

sounds like its just the pitch, might be a rendering problem

[@SrmthfgRockLee]

coz its cooler different and less damaging to ears and they should fkin make this to all their themes like the starting is so bad.. he talks so small. . volume and i increase a lot then get blown headache i usualy listen 1% music all day and i have to increase this a lot for his voice then start next video and gotta decrease just for intros so annoying

[@at-least-you-tried]

@@SrmthfgRockLee why is the intro the same though

[@gizatsby]

How much you wanna bet they did it just to mess with us

[@imboblol8238]

It's wierd and yeah maybe it's an AI or ghost lol

[@DeGebraaideHaan]

No, but virtual girlfriends are.

[@BattousaiHBr]

virtual waifus*

[@oscarrosenwald4001]

This is an interesting analogy. As virtual particles, virtual girlfriends can explain a lot of my admittedly messy behaviour.

[@empireempire3545]

2D > 3D

[@calebmauer1751]

Like Krieger's girlfriend Mitsuko.

[@nathanielgoshorn407]

We know the bond between a couple can exist. The more we try to detect it in space time, the more confusing and impossible it seems to be tho.

[@NiksCro96]

my engineering diploma is made out of virtual particles.

[@theterribleanimator1793]

so you have a theoretical degree in theoretical engineering?

[@ntl5983]

It only exists when you look at it.

[@Scorch428]

so is my girlfriend!

[@euanlankybombamccombie6015]

@@Scorch428 my wife collapses when she,s being measured

[@jannmutube]

---- > That is not scientific.

[@justpaulo]

I had to go back and see the animation of the binary stars. And there it was ! Not the black hole, but the slip of the pen. So amazing that some PBS Space Time viewers actually spotted that !

[@vinayk7]

_Long long ago ...while watching TV_ *Narrator*>According to Heisenberg's uncertainty principle the space is never empty,there are constantly getting created and distroyed these pairs so called "virtual particles".So when that happens near event horizon of a black hole something remarkable happens .. - Hawkin-radiation. Me>Wow I love astrophysics! *3rd Nov 2018* 😡

[@mephistovonfaust]

Particles popping in and out of reality would defininetely go against the law of conservation of quantum information and thus would not be possible.

[@NiffirgkcaJ]

@@mephistovonfaust it said virtual particles, not real particles so it wouldn't violate the law of conservation of energy, there's also another type of quantum field theory that can have the same outcome without making virtual particles.

[@douglasoak7964]

Steady state uncertainty of vacuum space sounds like an excellent way to save computational energy. If measured spend energy Else don't spend energy and maintain probabilities.

[@ailijic]

I am not sure I understand your statement. The pure randomness of the vacuum space means there is no gradient of energy. You need a gradient to extract useful work, as far as we know. See the PBS videos on entropy and Maxwell's demon.

[@mcmaho17]

@@ailijic He is supposing the universe is a simulation. The energy being saved having to do with whatever other worldly processing system runs the computation, not something to do with saving energy in the hypothetically simulated vacuum space itself.

[@Ke6wli]

@@mcmaho17 It might not necessarily be a simulation in the sense that some sentient being created it. It could be that whatever process at the deepest levels (way down under the Planck length scale) that determines particle behaviors might be equivalent to running some sort of self organizing program similar to a cellular automation. We will probably never know though because the Planck length seems to be as deep as we can ever expect to see.

[@exoplanets]

Ok.. my brain *exploded* half way

[@Shadowrunner340]

But it was still there...

[@MelindaGreen]

That means you're starting to get it.

[@Jiraiya-Sama482]

It’s ok mate I had to rewatch the intro!

[@ploppyploppy]

You did well to get half way. I was about 2 sentences in. I wish I could understand this - I love maths and physics but there are just too many things I can't grasp. Thank heavens there are people who can.

[@wyllomygreene7700]

think of each virtual particle as a stack of task cards - each VP is not an object, really, so much as a set group of possible paths

[@davencharity]

Tell me this, Matt: If a quantum tree falls in a vacuum, and nobody is around to measure it, does it still have any energy?

[@masterofblight]

@@pluggthis this explanation has no potential.

[@JorgetePanete]

@torus dfgdfgdfh is*

[@agimasoschandir]

Out of all the possibilities you had to pick that tree in that vacuum, tut! I suppose it would be in a superposition

[@rastrisfrustreslosgomez544]

lol it would be is a superposition of all the ways it could possibly fall with a real energy fluctuating over a closed-loop in phase space :P

[@dROUDebateMeCowards]

Yes and no at the same time.

[@andreylebedenko1260]

@17:05 Aha! Yep, I've increased my screen resolution and now can definitely see the singularity right there!

[@thesoundsmith]

That's a pixel, not a voxel...

[@Spencer-wc6ew]

This made me think back to learning integration in Calc 2. Would saying virtual particles are the rectangles used in integration be a good analogy? We use rectangles to approximate the area under a curve. When we make infinite rectangles, it gives an exact answer. In a sense, the rectangles aren't used in the end but are required to reach that end.

[@schmetterling4477]

No, not really. These things are the result of a kind of Tayler series approximation of the path integral.

[@chuckrittersdorf]

My undying love to you my friends at Space Time. My week would be in smithereens without you!

[@billpintura6097]

Smithereens = Virtual Particles

[@thstroyur]

A few addenda: *Perturbation theory, yes, but that's not the whole story (grab Griffith's QM textbook, you won't see mention of virtual particles (VPs) in his examples); the _true_ origin of VPs is in the iterative solution of the Heisenberg eq for the evolution op using the _free_ solutions as input - which leads to the Dyson series, which we rewrite as Feynman diagrams (FDs) *The vid gives the impression FDs tell you what happens with the particles post-interaction. _They do not_ - you put the legs as input, figure the VP lines that make for a legal diagram, and _then_ you calculate its contribution *There's a subtle difference between how zero-point energy and the 'random particle-popping vaccum' relate that's not portrayed here: like mentioned above, we use free particles to approximate the interacting-particle picture - and this includes the vacuum as well. So, if you could solve the problem exactly and describe the vacuum in terms of these solutions, there would be no popping in-and-out of existence, _by definition_ - but there still would be some zero-point energy...

[@nakanoyuko]

incorrect..

[@JaredJohnsonRocketMan]

Griffith's book doesn't talk at about QFT!!! I recommend Zee's on QFT.

[@INAVACL]

I can imagine if we see quantum stuff like we saw math 100 years ago and how "difficult" it would been to do certain math calculations... and that in 100years we will have a quatum calculator on our phones p:

[@xtramoist9999]

*our brains Or maybe we'll just have 8D shapes represent our pure energy state of consciousness. Or maybe we'll wake up in bed, unplugged from our "simulation"

[@mephistovonfaust]

Probably not... You'd need a quantum cpu in your phone and thus far, we aren't able to cool it without liquid nitrogen and even then only have a couple of qbits. If we are one day able to do so, it won't be in a hundred years.

[@NoSubsWithContent]

@@mephistovonfaust a lot can change in a hundred years bud, we went from slavery to nearly harnessing the power of stars in that amount of time.

[@parthsarda2793]

Energy in vacuum is one of the most weird yet interesting thing to get the reason behind. It reminds me of the proverb, 'everything is just tge result of nothing'.

[@lepidoptera9337]

So, tell me, how much energy did you receive from the vacuum today?

[@johnblankenhorn9730]

This is the best description of virtual particles! Thank you!

[@beretperson]

The more I learn the less I understand, it's frustrating.

[@MrCHINBAG]

Theoretical physics is like this.

[@MeatPops]

Knowledge of one's ignorance is actually a good thing. A more apt declaration might be: "The more I learn, the less my preconceived notions of reality serve me."

[@Plutokta]

Welcome to physics! By the time you get your PHD, you won't understand anything anymore. Don't panic, it's normal. Just shut up and calculate!

[@linklegends22]

"As our circle of knowledge expands, so does the circumference of darkness surrounding it" - Albert Einstein

[@cedricleeakadominic]

Ah yes, it's the uncertainty principle in effect

[@devinfaux6987]

Question: I've wondered why the word "excitation" is used to describe how a quantum field behaves as a particle. Would it be accurate or inaccurate to say that it could also be called a "wave" or "ripple" in the field? And why?

[@cloudpoint0]

The word "excitation" refers to a change in the quantum states (probabilities) that are associated with a collection of points in space, a specific quantum field. When a change happens, a range of points in a quantum field changes, never just one point. An excitation might be thought of as the general location where the peak probability is at any moment. Other fields can react to the excitation. An excitation can be stationary or spatially moving in the quantum field. It must be moving if it is massless or it wouldn’t exist, since no mass (temporal movement) and no spatial movement means no states are changing. The words "wave" or "ripple" both refer to how an excitation lives within a quantum field, in a sort of repeating way. These two words suggest that some physical movement of the quantum field is happening although this isn’t happening - just probabilities are changing up and down. Particles don’t exist as dot-like things in quantum fields. A particle is just a name for a wave or ripple of the minimum energy quanta allowed in that quantum field. But you do observe dot-like things if you attempt to classically interact with a quantum field (i.e. interpret its probabilities as one outcome). Usually this will be where the excitation is but it could be anywhere within some limits.

[@dudeguy763]

If virtual particles are just mathematical devices then what is hawking radiation?

[@AnonymOus-ss9jj]

@@OnlyLyricsMatter Presumably (less we are all screwed) all of the laws of physics can be described by mathematics, that does not mean all mathematics describe the universe. Approximations though do not count, as they are inherently incorrect. If virtual particles are just approximations then I wouldn't call them real.

[@AnonymOus-ss9jj]

@@OnlyLyricsMatter Okay, fine.

[@Codeman20]

2:52 y’all just showed how 2 universe’s will not ever touch each other.. But that lightning in between is where our focus should expand.😁

[@johnvosarogo1785]

Finally a non-dumbed down/sensational explanation of zero point energy. Thanks for this

[@toasteroven6761]

You should do a video on some more 'FTL' proposals like the 'Musha Junp Drive' by Dr Takaaki Musha. So far, if possible, it's the most feasible 'FTL' drive yet! The Musha Drive also deals with the zero-point field as said here. :)

[@smergthedargon8974]

_This idea popped into my head, and I was just wondering what people though. Or, more accurately, why it's wrong, 'cause I'm just some loser; doubt I'm first to think of this._ What if gravity works somewhat like the Casimir Effect, but instead of plates being extremely close together, mass causes a disruption in certain "frequencies" of gravity's quantum field? i.e. if you're not experiencing any significant gravity, your atoms are being hit by nigh-infinite virtual gravitons from all directions, but, as you enter a gravitational field, the ratio of gravitons hitting you from one side becomes greater and greater, causing greater and greater acceleration as you're hit with more virtual "towards mass" gravitons than "away from mass" gravitons? Maybe another way of putting it is bit like how the channel explained how black holes interfere with quantum fields, resulting in the tiny positive energy difference at their horizons (at least, IIRC) that leads to Hawking Radiation. Could gravity be a result of mass causing less severe "dips" in a field, leading to a sort of energy difference? I had a way of expressing the idea in terms of this last night, but forgot it when I went to sleep. There're probably other, better ways I could convey my idea, but, like I said, I'm just some rando in the KZbin comments hoping someone smart sees my idea and can tell me why I'm wrong. Maybe Matt-senpai himself will notice me. ...probably gonna keep posting this 'til one of the resident smartbois does.

[@theterribleanimator1793]

@@Julian-by7on if we can't just reload the last save.

[@felipearmwrestler4852]

That has been thought already, decades ago. I dont remeber exactly the name of the theory, but in this class Richard Feynman himself talks about it: kzbin.info/www/bejne/Z4TVea2JfNNgf5o

[@roblaquiere8220]

Particle based Gravity is an interesting idea, but ultimately there are issues that haven't been understood yet. First off is our inability to create experiments in nano-gravity environments... anywhere in our solar system has gravity 3000 times greater than the predicted value at which a change from Newton's formulation would occur. The idea is that after a certain tiny threshold of gravity, gravity will pull with a force proportional to 1/R as opposed to the usual 1/R^2. I imagine this is because of the quantized nature of gravity and the fact there is a minimum energy that gravitons can exist at. Any gravitons reaching you after a particular distance or weakness would be guaranteed to have a minimum energy, and you can only acquire acceleration from the gravitons in discrete quantities from that point on. Testing this would be impossible currently. This idea doesn't suggest that gravitons radiate towards massive bodies, they still radiate away from massive bodies. Your idea has the gravitons coming in from very far away, whereas in labs gravitation radiates from massive sources... Gravitational waves observed in LIGO propagated towards us from a massive object, not away from us and towards the massive object. The speed it took for the gravity waves to reach us was precisely the speed of light. If gravity falls into massive bodies as opposed to radiating away from them, then that conflicts with the results of the LIGO experiment. We can be almost certain that gravity travels away from massive bodies at the speed of light.

[@chrissonofpear3657]

This is a new one on me, although I have looked at concepts on vacuum engineering before...

[@NickRoman]

@@roblaquiere8220 , why couldn't we think of space as aether and the gravitational waves are just that, waves. If some material falls toward something, the material behind it will fall into its place and so on forever moving away from where the "hole" appeared, just as waterfalls travel upstream over time. The idea makes sense to me: there is pressure that is most consistent in the most pure "vacuum" and thus undetectable, similar to how I assume water is most still and consistently dense at the bottom of the ocean. So, maybe massive bodies are actually a drain. The experiment proving that aether does not exist just proved that light is not a wave in an ocean of aether, right? But what about space itself? Maybe what we call particles are bubbles of non-space and we just have everything backwards. Um, but what was that idea supposed to solve again? --consistency with existence of black hole, why things come together due to gravity, why speed of light for gravity (or light)(because it functions like the speed of sound--there's a maximum)?

[@joshuakahky6891]

Perturbation theory seems very useful for quantifying unknowns in our own theories, but it doesn't really seem to be in the "heart" of the history of physics. It seems more like we're just adding bits and bobs into our equations until they fit the observations, instead of finding a "truer," more complete theory of particle interactions. To me, it seems lazy. Could you maybe expand on how this provides a more in-depth look into the actual mechanics of our Universe, instead of just being a band-aid for a deeper problem in our theories?

[@rhamph]

My understanding is the "truer" form is a continuum approach. Take your wave and make it infinitely detailed, infinitely large, in all 4 dimensions. Sadly we don't have a way to calculate that so instead we attempt to simplify it and still get useful predictions out; that gives us virtual particles, lattice theory, etc.

[@godiamcrazydude]

Whether it's lazy or not doesn't matter, it works... And you absolutely must apply observations to fix our theories, the other option is just not have any working theories. It's the best that we have now.

[@r7diego]

I understand that the real calculations are too complex, perturbation make it simple. Example: if you try to launch a rocket to Mars you should calculate the gravitational influnce from the sun, the moon and all the planets on the solar system, the calculation would be too complex. However, bacause the influence from other planets and even the sun is small, you can ignore it to simplify the calculation. Furthermore: if you use relativity equations to make your calculations it will be very complex, almost imposible, so you can ignore gravity and use Newton laws to make it easyer. This is how i undestend "perturbation", from Brian's Green book, a simplification. Sorry for my bad english

[@lezhilo772]

Perturbation theory is NOT a theory for “quantizing unknowns”, whatever that means. It is not the theory of particle interactions, it does not add bits and bobs into our equations to fit observations. All of laws that govern the interaction are already there when we wrote down the equations that govern the quantum fields. Perturbation theory comes AFTER we have written down our equations of motion(of the quantum field). Specifically perturbation theory comes up when we try to solve these equations. We need a method to actually solve them. These equations are pretty much impossible to solve by hand, and even with computers are still extremely difficult. Perturbation theory provides a way of simplifying that calculation. More precisely perturbation theory provides a systematic framework of making approximations: identifying big quantities that we need to calculate and ignoring small quantities that contribute little. It is a very intuitive method, developed by brilliant minds that sought to find visualizable ways to make approximations, which is probably why most people mistake perturbation theory for describing actual physical processes. It’s like when observatories do weather forecasts. We do know the equations of motion of our weather system(Navier-Stokes equations, with inputs from thermodynamics and non-inertial effects and so on), and in principle if we can solve this equation, we can predict with absolute certainty whether it will rain or be sunny tomorrow, the exact temperature of every part of the atmosphere, even the exact speed and location of every breeze. But alas when it comes to solving these equations, the Navier-Stokes equations are perhaps even harder than QFT calculations. In order to provide even a tiny bit of useful information, we must apply approximations. A common approximation is to instead of looking at our atmosphere as infinitely infinitesimally small volume elements of gases(like the equations tell us to), we cheat and look at finite, but still quite small boxes of gases and do our calculations discretely. That way computers actually have a hope of solving these equations. Of course they aren’t going to be 100% correct, which is why weather forecasts aren’t absolutely correct, but they give us a pretty good idea of what will happen next. Clearly you don’t say that boxes of gases with finite volume is an underlying physical reality(if you want more accurate results you can make those boxes smaller, but it will take longer for the computer to calculate). Perturbation theory is the same: it is a useful tool of simplifying our calculations, and it is very intuitive(far more intuitive then boxes of air), but in the end it is still just an approximation.

[@timseguine2]

Perturbation theory is just a way of writing and solving equations that reduces unsolvable mathematical problems into an infinite sequence of much simpler problems. It doesn't result in an answer, but a method for generating an arbitrarily precise answer. Tell me how many significant digits you need, and I can tell you how many terms you need. This is mathematically essentially the same as an "exact" answer because this is roughly speaking the same as one of the several equivalent standard definitions of the real numbers used by mathematicians. And the same basic idea cuts through almost all of real and complex analysis at or above undergraduate mathematics.

[@dadgonewild381]

Another of your vids I'll add to my favorites. There was always something missing when I tried to grasp virtual particles. Now I get it. I can 'work' with this view of virtual particles. Thx.

[@psmoyer63]

This video is the best compact explanation of the whole of QFT ever made.

[@WestOfEarth]

Also, my question remains: As the Universe dies, does zero point energy 'stop' a final entropic death?

[@thesoundsmith]

Ask me when we get there... (Buddhist joke, I think.)

[@ryancier]

Never thought I'd be learning astronomy from Keith Urban

[@winter_skywalker]

I love how every episode ends with the word, Spacetime.

[@jpe1]

Chart at 2:02 got mis-labeled. At the bottom, instead of “electron neutrino” thrice, it should read, from left to right, “electron neutrino” “muon neutrino” and “tau neutrino”.

[@T33K3SS3LCH3N]

I believe it was Noam Chomsky who had the idea that the unique ability of the human brain is recursion. To apply a function to itself and infinitum. From simple things like chaining together sentences ("She said that he said that they thought that ...") to the ability to think on meta levels, like thinking about thinking. Maybe that's the great filter that blocks the leap from smart animals to a scientific species.

[@James-mi5qt]

*But can the universe run "Crysis"?*

[@mathieupare3233]

No

[@shadow105720]

So far we only know of one running program called Earth. Pretty boring. Maybe we can install something more fun.

[@jozsefkalmar7054]

@@shadow105720 Sure, but the minigames called "Missile Crisis", "Economic Crisis" etc. are amazing

[@CyberRager]

missed an opportunity to dress as Carl Sagan...........

[@JorgetePanete]

you used more than three dots

[@Yora21]

Next year, please!

[@Pseudo___]

..........................................................

[@VikingTeddy]

I think i speak for most of us when I say: Huh?

[@handlebarfox2366]

this is like defining a string's vibration by adding up all the possible modes of vibration

[@doncox3951]

This throwing stick idea of yours has boomeranged on us

[@joehinojosa8314]

I once had a girlfriend who was made up of "virtual particles". She left me. 💔

[@MiltonRoe]

Guessing you were perturbed

[@douglasoak7964]

Virtual particles sound like packets of information.

[@billpintura6097]

Good argument I/O of packets! They are still data and at least binary that requires space to transfer and store so they are real particles.

[@garethdean6382]

The problem there is that any interaction can be broken down into infinite packets. Which is problematic and nonsensical.

[@muskyelondragon]

I have been arguing with people about this for years. "Virtual particals" do not exist, they are a mathematical trick or device. If they actually existed they would gravitate. You would be amazed at the number of scientists I have had this argument with. Some just won't let it go.

[@fuxpremier]

Do you work with physicists arguing particles outside of their mass-shell actually exist? O_o

[@MrMrsirr]

Wait there are actual scientists that think virtual particles are real? I'm not sure how I feel about that. I was having a good lol at the people in the comments like "You have no evidence of virtual particles >:O"

[@Ni999]

Please tell me about the W boson.

[@nmarbletoe8210]

what does real mean anyway

[@agimasoschandir]

Maybe they were virtual scientists :)

[@dfpv97]

Actually, if I'm not mistaken, what Plank described as quantized was the atoms (as harmonic oscillators) in the ideal material of which the black body would be made of, not the elecromagnetic excitations, which he treated classically. It's still a very important step towards the development of Quantum Mechanics, no doubt about it, but the story doesn't quite go as usually presented. Just a side note, I'm not saying the video was wrong or anything. Besides that, I love PBS videos. Awesome work!!

[@AliHSyed]

"It's too physical... And Australian" - I LOL'D irl 🤣

[@feynstein1004]

Virtual particles sound like modern gods. We can never prove that they exist but we still believe in them because they make reality simpler :P

[@garethdean6382]

Better: The people who have anything to do with them don't believe in them and the man on the street believes in them because they sound cool.

[@feynstein1004]

+Gareth Dean Lmao dude. Btw why are you always so late with the replies? Very busy, I presume?

[@StanTheObserver-lo8rx]

What happens when you send virtual particles through a double slit?.. hmm?

[@chrissonofpear3657]

That's a rather good question, I think. I assume there is no similarity to photon creation in a Casimir cavity?

[@MikeRosoftJH]

You don't; virtual particles don't have a well-defined position or trajectory.

[@Lyle-xc9pg]

Humans developed so far possibly because of psychedelic mushrooms

[@frun]

What if Energy-momentum relation is not conserved, because of nonlinear dispersion? 5:25 Virtual particles are not obliged to travel in spacetime, they can move through space. Matt did not mention, that at some point perturbation series no longer approximates the solution and diverges.

[@lepidoptera9337]

Virtual particles don't travel, at all. They are stuck in books and articles about quantum field theory. ;-)

[@Mr.Nichan]

This video is great for giving an extra level of explanation than most popular science videos give.

[@vichodeivis1219]

The universe was made by a crappy programmer. He copied a random script from the not-internet, hammered it a little, and instead of making it good, it deletes the results he doesn't want because it was simpler.

[@godiamcrazydude]

@Alex Spray Actually, the universe doesn't have a problem with energy. Rather it doesn't really like energy gradients.

[@Mekratrig]

Unfortunately, anyone can upload buggy code to Github.

[@jackmack1061]

@@sertandoom4693 Yeah, that is the idea. I actually design RPG campaigns for fun and have detailed about 15 milieu so far and one of them works as you say. I need the players to realize they are in a false world for that campaign to reach its 'correct' conclusion. And for the haters, yes I know it sounds like the matrix but the concept was fleshed out before those movies existed. If there is a RW inspiration it is the Sleeping Dragon series of books from the 80s.

[@judbakilam]

@@jackmack1061 If you are 100 % sure there is no God then your knowledge in physics/mathematics and history is infantile or shallow at best. Do more reading mate and be aware of your surrounding.

[@jackmack1061]

sk0sHsk0sHIt may be that we are an unexpected emergent property of a simulated universe. The programmer may be unaware of our existence. I would doubt that, though. Why need our ability to intellectually deconstruct the universe we perceive have a purpose? Maybe there is no purpose; just a few simple rules and a very large calculator.

[@RSEFX]

His delivery has improved tremendously. I found it impossible to listen to him during his near frantic presentation a while back. Cheers for that.

[@nicolaiveliki1409]

Matt:"like a boomerang" me thinks:"totally Australian explanation" Matt (seconds later):" the explanation is too Australian" me thinks:"information *does* travel backwards in time in a decipherable manner"

[@alexmijo]

my favorite video of yours, studied some particle physics (not majoring in it though) and never really knew what was going on with virtual particles

[@fidrewe99]

Maybe the best non-technical explanation of virtual particles I've seen so far. Still needs a lot of disgestion. The question remains, what makes up the difference between a particle and a virtual particle, if both are excitations of modes in a quantum field?

[@holding3587]

best explanation ever i really didint know what is the meaning of virtual particle now i have learned every thing

[@jeanpaul145]

The phrase "in order to remain uncertain" @ 9:31 made me laugh and think to myself "Wubba lubba dub dub!"

[@cyberpunk-rsr]

It didn't make sense to me either Matt. Good job on changing the thinking boy!

[@picco_only]

The shorter the video the more i keen to watch

[@redthrow9827]

Enjoying the videos, thank you!

[@cultibotics]

There is such an advantage in the use of spread spectrum radio transmissions that it's likely any civilization making use of radio would quickly adopt it, making their transmissions disappear into background noise.

[@irinaratushinskaja7900]

Excellent job, science dudes! Yet would you give a non-virtual explanation for the Casimir effect, virtually pretty please? It is often explained by some virtual particles "not having space to virtually exist".

[@mathematicalninja2756]

They can't, quantum waves exist outside reality.

[@garethdean6382]

This is a macroscopic equivalent: upload.wikimedia.org/wikipedia/commons/9/9d/Water_wave_analogue_of_Casimir_effect.ogv The difficulty of explanation is that the effect DOES depend on things not having space to exist between the plates; waves. In the video linked you can see there are more and larger waves outside the plates than between them, it being impossible to fit a two inch wave in a one inch gap. But people will see this and go 'But the waves are virtual particles!' No they are not, they're used to MODEL the waves. But a lot of people just refuse to understand the difference.

[@HRyottGlayzer]

a video explaining LZ or SuperCDMS or the upcoming XLZD would be cool

[@ShionWinkler]

I've always wondered if the "Great Filter" is Mitochondria, at some point a single cell "ate" a bacteria and instead of digesting it, they started living together as a new type of cell. Mitochondria is what makes energy for our cells, and in turn our cells protect the Mitochondria, but how unlikely is it that a random cell would eat a bacteria and decide this thing could be helpful and start a symbiotic relations ship with it, one that potentially led to multi-cellular organisms being possible.

[@stae24]

nah

[@himanshupatil7593]

pov: you don't understand anything but you feel at the top of the world knowing these stuff.

[@enterprisesoftwarearchitect]

@Matt @PBSSpacetime what would be sexier than an episode about the speculated connection between entangled Black Holes and wormholes

[@enterprisesoftwarearchitect]

I mean, the ER = EPR conjecture - it has all the stuff you love, Bell Pairs, Planck scale, wormholes, FTL travel, and quantum information!

[@Eris123451]

The trinery star system thing made me laugh my socks off.

[@_texas_pete_beats_the_meat4500]

A little snarky towards the end; must be that good ol' Australian, sarcastic sense of humor my Aussie friends keep talking about!

[@Scorch428]

He's just on his period.

[@_texas_pete_beats_the_meat4500]

@@Scorch428 Lol! Fookin' brilliant 😝

[@dariuspfitzner1712]

Love your work, don't stop.

[@Rome101yoav]

I'll have to see this five or six times before I get a grip on what's going on

[@APXSTUDIO]

Lol me too after that I 90% understand