Is Gravity RANDOM Not Quantum?

[@lightfish6663]

We got Oppenheim and Oppenheimer, but Openheimest is still missing.

[@RossDmoch]

Gesundheit bruh 😂

[@PaulPaulPaulson]

I think Heisenberger has a higher probability. But the chances are greater than zero, so lets hope for all of them.

[@peterahl6807]

I think you have to trade an Oppenheimer while they're holding a demon core

[@imveryangryitsnotbutter]

@@peterahl6807 What? Oppenheimer is evolving!

[@Flesh_Wizard]

The Big Bang was the Oppenheimest thing ever

[@novigradian1284]

The intro was louder than the big bang lol

[@bierrollerful]

Matt making sure we're all awake for this lesson

[@JamesR624]

Yeah. I was watching with headphones and nearly fell out of my chair! Holy--!

[@MikeMutethia]

Haha ikr??

[@SuperMisterBam]

To be precise the intros sound is correct. Just the voice is a bit undertuned. :D Please let me not forget to tune the speakers down after the video.

[@syntaxusdogmata3333]

I read this, so turned it down just in time. 👍

[@summerlovesyou7586]

“Oh sweet 😊 time for a nice relaxi-“ BOOOM BOOODOOODOOO BOOOM BOOOOM 😱🤯🫥

[@nitrovent]

Gave me ptsd of the old Demolition Ranch intros

[@Snakeybloo]

What do you mean by this

[@ignaciomoreno9655]

😂😂😂😂😂 It's to check if we are awake.

[@tops1954]

0:28

[@Troonielicious]

Do you live in Ukraine?

[@spladam3845]

Audio guy making sure Space Time has your attention.

[@NokiaTablet-pl7vt]

The volume is also random

[@YossiSirote]

I think it is important to note that Oppenheim’s theory is testable. That is a great advantage compared to many other attempts. Hopefully within a decade or so it will be tested and we will know if this idea is correct or not.

[@Emerphish]

Would you mind sharing how it's testable? Sounds really interesting

[@annaclarafenyo8185]

It's testable and wrong. String theory is testable and correct. Although this is somewhat less crackpot than other stuff.

[@macroxela]

​@@annaclarafenyo8185 how is String theory testable? As far as I know, most of it is untestable or requires absurd amounts of energy beyond the scope of anything we have or will have in the near future.

[@annaclarafenyo8185]

@@macroxela So what. There is no rule that the theory has to be cheap to test. In any case, String Theory is testable because it's a proper theory, it predicts what happens near black holes, for instance. The theory this guy is proposing is also testable, but it looks inconsistent on the surface, and so it's very likely ruled out without any experiment.

[@macroxela]

@@annaclarafenyo8185 although you're technically correct, you're ignoring just how absurd the amount of energy we need to test them. And even then, it's not too clear whether such tests would actually prove String theory. There's literally an entire scientific debate about whether String theory is falsifiable or not.

[@TehPwnerer]

You gotta talk to your audio guy about levels and keeping them relatively consistent. Can barely hear you in the start, crank up the volume & then get my head blown off by the intro 🤯

[@Cyberlightning101]

It wont be the sound guy its just in the edit. Recording levels haven't been matched to the pre rendered intro.

[@Snakeybloo]

Turn on stable volume

[@musiqtee]

Program loudness -15 LUFS integrated and -1dBTP max, please…? If _this_ sounds alien, it’s way simpler than the content of any (all great!) PBS Space Time video - but to a mere sound engineer, maybe not a physicist…?😅

[@albertqhumperdinck]

Replying to boost this comment. This channel`s content is too good for these levels.

[@takeiteasyeh]

@@Snakeybloo was already on, made no difference (button probably only works for KZbin Premium harr)

[@MarshmallowRadiation]

This feels less like a revolutionary mind-bending theory-of-everything and more like a funny math trick to get things to work together that really shouldn't, with some strange logical side effects that don't seem likely to be physically real but still somehow could be. Which, given the history of physics, means that is is probably a major breakthrough. An "oops I thought the Planck constant would reduce to zero but I accidentally quantized the electromagnetic field" moment. A "let's balance out this equation with a positively-charged electron going in reverse like some kind of 'anti-matter'" moment.

[@pikotech1]

Have to agree with this. For all it's craziness, it feels like this theory might be on to something. Not that opinions matter in science if course, but I have to say I am hopeful!

[@dw620]

If gravity can be quantized, what size of quanta would be required to describe the changes in gravitational attraction between two dancing ants at opposite "sides" of the universe?

[@Houshalter]

The actual laws of the universe aren't likely to be just given to us. At some point we just have to accept the simplest model that explains our observations is the best we can do. The model won't be right. But if it's better and simpler, it's probably closer to the truth.

[@LB-vf2hm]

Yeah, exactly. It feels like a quick and dirty hack a la semiclassical gravity, but well -- So does all of quantum mechanics if you really look at it, and that's the best tested theory in modern science.

[@LB-vf2hm]

@@Houshalter to use a truism from engineering, "all models are wrong, but some of them are useful". Arguably, the incompleteness theorem outright forbids a "theory of everything", at least, one that can be represented mathematically. One way or another, we are guaranteed to be wrong. All science is capable of, impressive as it is, is pruning away wrong answers -- it can't prove "right" ones by any other means, so the best we can do is become *less* wrong.

[@K.F-R]

Douglas Adams and/or Terry Pratchett would be having so much fun with this.

[@patrickcannady2066]

Doug would absolutely take the piss.

[@minecraftcommandnerd1280]

Terry Pratchett would definitely be having a field day with this

[@yishaibasserabie5765]

Love this

[@djhakase]

"Many physicists tried for generations to understand the universe. Little did they know that the universe in its infinite wisdom would bestow this knowledge on to Charlene, a struggling kindergarten teacher in Wichita, Kansas. Little did Charlene know it either, as the sparkle in the corner of her vision passed without notice, as a small child flung a stuffed bear across the noisy classroom." Needs work but a random spacetime is a delightfully richer spacetime.

[@Nono-de3zi]

I love it. 35 years of studying and modeling biomolecular mechanisms led me to view all such as biased stochastic processes. How randomness can lead to apparent determinism is underestimated.

[@toughenupfluffy7294]

Determinism is NOT predetermiminism. Predretermrinism. Predaternimismus. (You know what I'm trying to say.)

[@michaelmicek]

​@@toughenupfluffy7294are you trying to say superdeterminism?

[@FirestormX9]

​@@michaelmicek perhaps he's trying to say Predator Missus

[@Krimmeldimmel]

Or he appeals to Kants distinction of determinism and predeterminism (which proves as effectively pointless though).

[@FirestormX9]

@@Krimmeldimmel but for real, joke's apart, why does everything appear deterministic when we look at the past?

[@mikelastname]

I've always thought I was clumsy, but actually, random gravity does a great job of explaining why I fall over at such incomprehensible times and places.

[@steveDC51]

Certainly explains my unfortunate relationship with gravity.

[@jamesalexander958]

Wouldn't many worlds solve this more elegantly? All particles would act classical from a single world and so would gravity

[@DemPilafian]

Just measure everything you do and that'll take away the uncertainty.

[@gordonstull1962]

Yeahhhhh always wondered if a steel rod about a mile high in the alignment with the force that pulls-straight inwardly into infinity would be like a ratio metric, linear Hall-effect sensor... Are we not becoming dragons or what😂😂😂

[@gogauze]

​@@DemPilafian that's the problem, though... that particular wavefunction distribution clearly favors a horizontal orientation. So, it frequently hurts when I measure it.

[@spidalack]

Seriously, your voice is super quiet and the theme almost made my ears explode

[@zavhytar9333]

Thanks for the heads up XD saved my ears

[@PandemoniumMeltDown]

Me: what the heck is that comment about. Me 0:28 :

[@Total_Entropy36]

splodey ears 😢

[@dontomaso11]

Rarely comment but was about to post that they need to get a sound engineer or something after getting completely blasted by the theme and then this was the top comment, so.. please fix your audio!

[@kristoffscuba5466]

The background audio is always too loud. Plebs like me are straining every brain cell to try and comprehend what’s being said and then some distracting acid loop comes out of nowhere smashing my concentration. Half the videos I abandon part way through because of it.

[@jajssblue]

2:07 I still wish we could have a video deep diving into how naive quantization of GR fails mathematically. Everyone just waves their hands and says that it causes non-sensical singularities in the equations.

[@Casperious32]

I'd like this a lot as well, I keep hearing "it doesn't work" but not much of why/how it doesn't work. At least, not mathematically

[@corsaircaruso471]

Same!

[@KingOfAllJackals]

**IF** I understand this video it’s the closest I’ve seen someone explain this. What’s on the right (the Tuv) is quantized. Mass, velocity, momentum only come in quantized buckets (the buckets are so tiny we don’t experience them). We apply some scalars (factors of gravitational constant, c, pi, etc) so it’s still quantized. Yet on the left hand side we have a smoothly continuous…vector? tensor? That smoothness means there no tiny “jumps” like you get in the quantum world. This might be a bad analogy but the right hand size is a shoe store that only sells whole US shoe sizes and on the left is a stream of customers that have **perfectly** sized shoes. There shouldn’t be a size 11.8447213 in the quantized store, just 11s or 12s but there it is. The analogy breaks down because **IF** I understand the rest of the video that 11.8447213 sizes shoe is really just a size 11 and 12 size shoe popping in and out of existence on your foot. Bad analogy because the average of a too small and a too big shoe is still an uncomfortable shoe not an ideal one.

[@MrMctastics]

Something something renormalization - Feynman

[@supermassiveblackhole8182]

​@@KingOfAllJackals that makes a lot of sense, thank you for explaining!

[@falxonPSN]

That last comment about Eve online being spreadsheets in space hit hard. I used to run a multi-hundred person corporation (and later alliance) and it literally became actual work.

[@recursiveslacker7730]

The eve online community legit went wild when Excel integration was announced

[@falxonPSN]

@@recursiveslacker7730 Sadly, that was right after I stopped. But even more sadly, I would have FLIPPED OUT if I was still playing. That would have been amazing.

[@TheRABIDdude]

I haven't played it but I know roughly what it's about. What are all those spreadsheets for? What work is involved in running a multi-hundred organisation?

[@nicholaslogan5185]

Yeah I used to write code to determine trades I was worth billions of isk 😅 then I realized I was literally just using my job skills to game.

[@UberMiguel603]

You can configure a custom spreadsheet to solve almost any problem which begins at small problems until you put them together to make major decisions.. every aspect of anything from mining to salvage to industry and now to fueling structures can be configured using spreadsheets​@@TheRABIDdude

[@MarcoLogan83]

It's incredible that after so many years this show can still deliver such amazing episodes. One of the best I remember, absolutely intriguing.

[@JKDVIPER]

This is a QUALITY SITE

[@llywyllngryffyn8053]

You don't have 'An' apple moving toward the Superposition Earth, you have a Superposition set of Apples moving toward a Superposition set of Earths. Collectively it functions like a Classical system.

[@unduloid]

0:28 Holy Hearing Damage, Batman!

[@somethingforsenro]

ok there are a lot of comments about the intro but this one is funnier than all of them

[@davidusa47]

I saw this JUST in time. Thanks, Robin!

[@mikemurrill01]

100% !! 😂

[@toad9724]

Ive determined the volume of the intro was randomly as loud as possible

[@maxisalamone]

Todays' intro was louder than THX lol

[@purple7filth]

Let your neighbors know it's science time 😅

[@unocoltrane2804]

reeeeeeeeeeEeeeeEEEEEEEEEEEEEEEEEEEEEEEEEEEE!

[@FirestormX9]

THX deep note was really cool for its time

[@btmillack21]

The Oppenheim theory is the single most promising advance in theoretical physics since the development of quantum field theory 50 years ago. It unifies gravity and quantum theory, it solves the measurement problem and - most of all - does that without introducing unmeasurable quantities like multiverses or objects visible at Planck scales only. It is great that there is still theoretical physics without a faith system behind it.

[@Czeckie]

this seems like it should be testable, is it practically testable?

[@btmillack21]

@@Czeckie yes, the group around Oppenheim has developed a test which might be doable within the next years. It includes a double slit experiment with a heavy mass to one side

[@SErik004]

This is a bit of an exaggeration tbh. There are still tonnes of hurdles before the hypothesis becomes as mathematically sound as other quantum gravity programmes. (This coming from someone who works with Oppenheim on these works).

[@naedanger123]

@@SErik004True, but that doesn’t invalidate the theory being promising. I’ll be keeping a close eye on it myself.

[@SErik004]

@@naedanger123 Of course, stay up to date (and work on it too if that's your area). I just point out the claim that it's 'the single most promising advance in theoretical physics since the development of quantum field theory 50 years ago' is completely not true lol

[@rotatingmind]

Thanks for picking up Oppenheim's ideas. Here two suggestions for PBS Space Time episodes: "What if the graviton was not massless?" (with ideas of Claudia de Rham) "What if one of the neutrinos was massless?" (with ideas of Neil Turok et al)

[@hydewhyte4364]

In Relativity, Matter tells Space how to curve, and Space tells Matter how to move. The Heart of Gold told space to get knotted, and parked itself neatly within the inner steel perimeter of the Argabuthon Chamber of Law. Douglas Adams: Life, the Universe, and Everything

[@CrazyDontMeanWrong]

I'm sure by now y'all don't need another comment about the intro volume... But you're getting one. That friggin' HURT

[@R2Bl3nd]

It also clearly has been redownloaded and recompressed many times over, as if they don't have access to the original anymore. Lazy editing.

[@rajeevyelkur7568]

@@R2Bl3nd i am curious . How can you tell or detect that ?

[@R2Bl3nd]

@@rajeevyelkur7568 I know what audio comprehension artefacts sound like, and I have lots of relevant experience. The only thing that would reduce the audio quality this much would be if it was recompressed several times. Or if they chose an extremely low bitrate. It's much more likely that they didn't specifically choose a really low bitrate, but instead just transcoded the audio many times, somehow, most likely by just downloading the audio and re-uploading it. It's easy to upload audio in high quality to KZbin, you just have to upload in a container format that can store uncompressed audio directly. You simply need an uncompressed copy of the audio and then you can just drop it into the container, and so by the time it reaches anyone's ears, it has only been compressed exactly one time. But now let's say you were to download the audio off of KZbin. You can decompress the audio into an uncompressed format, which means that it still preserves only the one layer of compression that KZbin has applied, but now, if you were to upload it again, even in that uncompressed form, it would be compressed all over again, and audio compression is lossy meaning that it removes data and creates an imperfect copy in order to reduce the file size. But that's if you were doing everything right. What people typically do introduces compression many times to the same audio. If the original producer exported the audio in an uncompressed format, that should be the format they distribute the audio in. But let's say they compressed it, which is common to do although not advisable. Then they send a compressed version to the video editor. The person editing the video drops the audio into the timeline. Then when they go to render the video, often for some reason video editing software will compress all of the audio after the video has been rendered. And then of course when it's uploaded to KZbin, it gets compressed again. So the audio has been compressed at least three times by the time it reaches the ears of the people watching the video on KZbin. But often there are a few more steps involved, each one introducing another layer of compression. Let's say the audio was from a library of free music. Let's say that that was on KZbin. Usually when people download stuff off of KZbin, they don't just decompress the audio, they transcode it into another compressed format, like mp3. And now let's say they put it into the video editing software, then render the video, then upload it. Then sometime later, a future editor doesn't have access to the original source anymore so they download the video off of KZbin. And let's say they convert it to an MP3. Then they drop it into their video editing timeline. Just how many times would it have been compressed at that point? I've lost track. The point is that just one piece of audio can be compressed many times over for many different reasons, because of people not caring about transcoding or preserving the original quality or anything like that. Most people don't think about that kind of thing whatsoever. I have a lot of experience, like I said, with various audio compression techniques, and with trying to find the original sources of audio. I can tell when audio or video has gone through multiple stages of being decompressed and recompressed over and over. This has the hallmark signs to me.

[@Aaron_J619]

​@@rajeevyelkur7568he has robot ears

[@mastod0n1]

​@R2Bl3nd maybe but you can still easily balance audio in post. It is lazy editing, but not for the reasons you stated.

[@lookatdatcake245]

How funny, I just sat in on a talk by a fields medalist who explained how continuous brownian motion has a lot of parallels to gravitational fields

[@fredericapanon207]

Cool. IRL talk or something that we can find online?

[@fredericapanon207]

@@lookatdatcake245 interesting. Was that IRL? Or do you have some keywords for us to find out more info? Or the title of a research paper?

[@Chulpichochos]

Einstens first major paper was a model for Brownian motion that helped proves the existence of atoms, so actually kinda makes sense

[@andrewferguson6901]

It would not be the first time physical systems are self similar across scales

[@axle.student]

I was just thinking about the orbit of electrons around a proton. If there is some random noise in that orbit, vibration.

[@cineblazer]

As a machine learning researcher, stochasticity in gravity feels pretty intuitive to me. I'm a big fan of Oppenheim's theory!

[@lloyddomke9563]

Old school THX system REALLY let me know there was some dynamic range to the intro music. Going to peel my cat off the ceiling now.

[@firefly618]

Question. At 12:00 you have a superposition of two spacetime geometries, one for each of the two mass-energy distributions.* Why can't the falling apple also become a superposition of the two trajectories? That would seem the logical choice. If the superposition collapses into Earth N.1 (or, said more rigorously, the scientist finds herself in the same world as Earth N.1) then she would measure the trajectory as being the left-falling one, and vice versa. Since gravitational waves travel at the speed of causality, no information is disclosed that shouldn't be. * In reality there would be not two, but infinitely many spacetime geometries: a continuous distribution of spacetime geometries, much like each particle follows a continuous distribution of trajectories, the paths in Feynman's path integral.

[@badgermcbadger1968]

I don't know the answer do I'm putting a comment here in case someone replies

[@SteveOnTheInterweb]

You are back to the initial proposal then, the argument here was that spacetime had random fluctuations, so you would get a slight zig zag path, not a superposition of two straight lines. This would mean uncertainty in the particle' travel path/time and therefore its momentum or initial position relative to the Earth. I think still you are right, we can't escape a superposition of the particle, you can't say a left turn happens with a particular fluctuation (which would affect an observer equally), as you would need to know precise momentum and position of the particle at that point.

[@EnderLord99]

Because apparently that isn't "behaving sensibly" for some reason

[@freakinschweeet]

"Spreadsheets in Space.....I mean, EVE Online"......that was gold lol

[@induspherix]

Has anyone ever modded quickbooks for EVE? I thought SAP Enterprise could be a solid lead, but not the beancounter nerdcraft I was hoping for.

[@styleisaweapon]

@@induspherix probably would be a downgrade for hardcore eve corps

[@degraft3960]

Was about to write that, then decided to scroll down first. Pure gold 😅

[@itishappy]

@@induspherix Microsoft make an official Excel plugin.

[@induspherix]

@@styleisaweapon True data. Intuit's accessible/dummy-jank design philosophy would have been more compatible with warcraft gold farming and/or cryptoMMO operations 🗑

[@HunterHogan]

You know what makes me tenser? The video's soundtrack.

[@acasualviewer5861]

tensors make me tenser

[@sechran]

[Einstein] "God does *not* play dice with the universe!" [God Making Gravity] "Whoo! Yahtzee!"

[@a6hiji7]

Yeah, He only plays poker

[@feynmanschwingere_mc2270]

And yet out of randomness...order. Einstein was right.

[@merxj]

Well, randomness is an ingenious way to introduce phenomena that we don't understand into a model to make it more cohesive. We can use that to refine our predictions but it will always be just a model. We cannot know whether the underlying mechanisms are random by nature. I think it's more of a philosophical question we might never know the answer to.

[@tryptime]

@@feynmanschwingere_mc2270 the only thing in the universe that has order is time, and we don't even know for how long.

[@notmybestmoment]

i cant stop laughing at this

[@dbskyguy]

Nice shout-out to the Eve community, thanks! o7

[@sebastianozorro2138]

The intro jingle left an imprint on my eardrums

[@mrcool7140]

Get sponsor block and enjoy life again

[@ZoiusGM]

Your ears conserved that information well

[@Flesh_Wizard]

PBS Spacetime intro jumpscare

[@DarkAlgae]

In the apple thought experiment, the apple seems to be treated classically while the earth is capable of a quantum superposition. Why wouldn't the apple also be capable of quantum superposition and become entangled with the earth so that there becomes two apples falling towards two earths only one of which can be observed? Kinda like Schrodinger's cat: open the box and your observations become entangled with the quantum superposition of the dead/alive cat which is) entangled with the release/non-release of the poison which is entangled with the detection/non-detection of the geiger counter which is entangled with the decay/non-decay of the atom. I must be missing something because this seems intuitive and isn't addressed.

[@DarkAlgae]

Same with the mass between the slits - the mass seems to be treated as classical. If the mass, which we know mass is quantized, had a measurable position so we could tell which way the mass was pulled, how is that any different from putting any other kind of detector over the slits to determine which path was taken in which no interference pattern is observed?

[@Papierkorb2292]

I think a problem with this is that it would mean the information of the superposition would immediately travel outwards at the speed of light, because the apple would need to be entangled with the earth. For example, if we replace the apple with a person, it would mean that this person is suddenly in a super position of getting dragged towards one earth or the other because the person is entangled with the earth, which would imply that the person would also see the earth at one of the two positions, since from their view, the position of the earth is clear. This however would mean that no wave function collapse could be observed in the first place, because from our view, they would always immediately collapse when deciding which superpositions's gravity affects the world around it.

[@MrTuneslol]

I've actually never heard that aspect discussed before and I think it'd a valid point to take into account. Hmm. ​@@DarkAlgae

[@alucs6362]

@@DarkAlgae I think this is the obvious and historically the standard approach to quantization of the gravitational field field. There would be a superposition of the entire gravitational field, including gravitational waves and whatnot. I don't love that they didn't included it, but I *think* that the reason this isn't discussed here is because the background to the video is that this approach is riddled with mathematical problems that people have been trying to solve for a long time; as far as I understand it, postquantum gravity is a response to this issue which tries to avoid it by doing something else entirely.

[@alexanderreusens7633]

I'm stuck with the same issue here. If we treat the earth as a quantum object, and we can see/measure the trajectory of the apple, we've measured the position of the earth and the superposition has collapsed. If we don't measure the apple, the apple's trajectory becomes entangled with the earth's position. I just don't see what the contradiction would be in that case?

[@AxisAngles]

Fun sci-fi fiction idea: gravity is the "check" on quantum that keeps the universe from "falling apart" into endless quantum superpositions.

[@DancingRain]

Spreadsheets in Space! Yes! I think that's what I'll call it from now on when I'm doing 3D modeling in Gnumeric. (Calculate the points in the spreadsheet in 3D space, then copy into an .obj file)

[@ekkkkkknoes]

The audio levels in this video are all over the place, the intro music blew off my ears

[@Ole_Rasmussen]

The most incredible part is that I found a PBS Space Time explanation I actually understand

[@metroidragon]

0:28 Wow the intro logo is way louder than your voice.

[@systemG3000]

BILLY MAYS HERE WITH AN UPDATE ON THE FABRIC OF REALITY!

[@genuinetool]

Headphone listener here. Who do I sue for the prolapse I just experienced?

[@chlodnia]

Fix it fix it fix it

[@Epoch11]

I'm old so can you speak up and turn down the loud music🧐

[@DavidsonTroy]

@metroidragon Thanks for the warning. I was at 0:25 when I spotted it. 😊

[@EthanGodbehere]

PBS Space Time, I absolutely enjoy and appreciate your content! As a viewer, please make sure the intro at 0:24 is volume balance to the rest of the video!

[@AkerfeldtTveitan-yi4xm]

This channel makes me happy

[@natikauranen5151]

You're an NPC

[@AkerfeldtTveitan-yi4xm]

@@natikauranen5151 lmao why would that make me an npc?

[@lll-set-propyl]

​@@AkerfeldtTveitan-yi4xmcuz it's always the same generic comment everywhere

[@ryanpeterson6897]

Now we know what proceeded the big bang: Matt's dulcet voice

[@loachroach130]

The real question is, can this be tested?

[@alexandertimmermans7187]

If it fits, it sits

[@joshuacook9376]

It can! It's tricky, but well within the realm of possibility.

[@letsdragthecave2017]

Easy, just get an apple and two superpositioned earths.

[@pcarter1989]

I have autism, Greg. Can you test me? 🤨

[@trevorallen3212]

I have idea of testing this but, it be too long to write to explain it here.

[@1urie1]

0:07 Longsword Theory of Gravity? Oh...

[@si.ari.06]

I don't know what he's saying

[@si.ari.06]

Long sought?

[@SSMLivingPictures]

​@@si.ari.06 I think so, but its up to interpretation 😅

[@illustriouschin]

Why does every single video have someone time stamping a few seconds in?

[@SSMLivingPictures]

@@illustriouschin Just in case we have 6 second memories

[@tarferi]

I have just finished binge watching every single video of this channel and I can say one thing for certain; I can hear Matts' voice in my dreams, quietly whispering the tales of quantum ... Space Time.

[@tarferi]

Roughly 94 hours for those interested.

[@moumous87]

Watched this on Sabine’s channel long ago. IIRC this theory is testable.

[@czerskip]

Your explanation of the incompatibility between gravity and the quantum world is the clearest and most understandable I've heard so far! 👏💚

[@Carewolf]

Unfortunately it was nonsense. The first case could easily happen and is similar to the result of this new model. The second was pointless, and the whole point of it was to prove it was pointless.

[@ripdimebag42]

Much like how Usain Bolt was born to be the fastest man on earth, a guy named Jonathan Oppenheim was born to be a physicist, lol.

[@jbear3478]

I knew a dentist who was a Dr Mohler😂

[@nathansponder8021]

Nominative determinism.

[@kenneth2519]

John physics

[@DJWESG1]

I tried to think of someone but could only think of Micheal knight

[@MattHudsonAtx]

Ironically, James Watt discovered electrical power but it was not useful until an invention by his commiserate, Bob Transformer

[@dividead100]

Sound levels are really screwed up on this one.

[@Flesh_Wizard]

In space, everyone can hear this video's intro

[@happyputt9709]

Eardrums are over rated

[@Snakeybloo]

Turn on stable volume

[@FuburLuck]

​@@Snakeybloo stable volume doesn't fix the issue.

[@eSKAone-]

They are random

[@yanntal954]

Recent work showed that you can actually have an extremal black hole by just adding a lot of charge to it. Apparently the event horizon can disappear and it also shouldn't reveal a naked singularity either! So what happens? Does the black hole just go kaboom? What does it even mean? I really hope you cover it!

[@theAEDan]

Something I thought last night. The experiment to determine if things fall at the same rate in a vacuum. Technically, since all objects create gravity, wouldn’t larger actions fall faster or at least appear to do so just based on the fact their stronger gravitational pull vs smaller objects would pull the object they’re falling towards more than the smaller objects gravity would?

[@PaulPaulPaulson]

A new spacetime video just as I sit down on my ceiling with a drink and a snack. Perfect timing.

[@100ghostgaming9]

ceiling

[@cholten99]

A drink and a snack you say? Have you been watching Isaac Arthur? 😉

[@physics_hacker]

@@cholten99 my thought too! also why sitting on the ceiling lol

[@induspherix]

I might have said you don't get the gravity of the situation, but as it turns out gravity would have called me out for telling everyone that I know gravity.

[@philtrubey7480]

@@PaulPaulPaulson did you end up on the ceiling after listening to the intro with headphones on?

[@chazzcannon3614]

In 2001, Oppenheim smuggled a siege catapult into the old city of Quebec as protest during the Summit of Americas. It was used to lob teddy bears.

[@maladaptedmalarkey]

This one truly scrambled my brain meats, and not because of the aggressive audio opener.

[@DesertFernweh]

19:30, I didnt think anyone still played that. COOL!

[@fractal_aura]

It goes between like 15k-30k people online every day, it's tons of fun

[@SloppyGoat]

Superposition does not really mean that things are actually in multiple places at once. It means that we don't know where they are, and we can only calculate a general idea of where we might be able to find a particle.

[@theslay66]

Those examples with the apple falling really bother me. To me it doesn't make sense that you could have something like the earth being in a state of superposition, but the apple falling toward it being perfectly localized. Both should be entangled, and measuring the position of one should also give us the position of the other. Same thing with the mass measuring by which slit the particle is going through, you wouldn't be able to see if it moved right of left unless you actually measure it.

[@bierrollerful]

I, for one, would welcome a universe where space time is in superposition. More Space Time is more good!

[@braindamage7311]

Why is this not a problem with electrostatics? A charges particle being at two places at one? The force points to the average position of the particle, the particle repulses itself and when measured the force radically changes?

[@philtrubey7480]

The reason I like this theory is that it is testable! On a benchtop too! No super high energies required. It ALSO could solve our dark matter problem, or rather it could explain galactic rotation curves. Still more work to be done on the theory, but it’s looking good.

[@davidpflepsen954]

That hurt my brain again! Wait, you play Eve-Online??!!!! Awesome!

[@SterbiusMcGurbius]

Bruh had my car speaker bumping on that intro

[@MahraiZiller]

That’s Jon! I know him. We used to do field kitchens and stuff together at environmental activist gigs, a few years back. Guy’s a legend. And he’s also just a really nice guy.

[@williamthompson5988]

11:06 Maybe it's because it's a simplified example, but I fail to see how that thought experiment disproves semi-classical gravity. It's based on an impossible foundation (a massively macroscopic object having 2 super positions) and then fixes the impossibility. Even if the Earth could be put into a superposition of states, both super positions would quickly fall into agreement and stay perfectly in agreement forever.

[@suburbandad574]

Came here to take issue with it also. If anything I thought it was a setup for a dark matter/energy hypothetical.

[@npgabriel]

Plus, we probably wouldn’t even be able to detect it, as I imagine that the chance of every atom in the earth being in a different enough position for it to be measurable that we’re falling towards nothing would be pretty tiny.

[@RoboBoddicker]

It's supposed to be a hypothetical microscopic quantum "Earth" I think

[@poltuu]

To me, option 2 seems pretty coherent : as you said, the diferent states would be attracted to the semi-classical center of gravity, hence, for big enough objects, it would make "no sense", but IMO it could also be viewed as one of the explanation why those objects ARE at their center of mass : the semi classical center of mass pulls them in. Obviously, for particules, the force is negligeable, and for big enough objects, well, they stop being quantum.

[@alexgrover7693]

Thank you for actually explaining what it looks like when you try to combine relativity and quantum mechanics. Most people just say "they're incompatible" and don't explain why.

[@AlexTrusk91]

11:00 doesn't seem odd. If it happens all the time, it perfectly balances out to what we observe daily

[@Carewolf]

Yeap, two super positioned earths wouldn't happen, because the center of every earth would be attracted to their common center :D

[@fadran11]

Astrophysicists: We finally figured out the three body problem! Anything can be calculated now! Quantum Scientists [thirteen seconds later]: So as it turns out gravity is *random*

[@CTimmerman]

Because of virtual particles, or causing virtual particles? Both?

[@fadran11]

Both, dear@@CTimmerman , until proven otherwise

[@TadashiKitsune]

Randomness would certainly explain why the three-body problem is such a mess, huh?

[@DrDeuteron]

that's DARK.

[@Nat-oj2uc]

It doesn't turn out it's as always quantum physicists trying to force their bs on gr

[@Kwauhn.]

This theory makes a lot of sense. If you think about it, matter and spacetime being self-referential has always implied that the randomness of QM would extend to GR in some way. You can't have a smooth and continuous gravitational field if the matter generating it is fundamentally random. Idk if it's entirely the right picture, but like Matt said, it's on the right track. That relationship between gravity and matter, which is quantum by nature, is pretty undeniable.

[@ARabidPie]

It also follows that if space can vibrate as in a gravitational wave, then it should exhibit other properties related to vibration. What's the fundamental vibrational frequency of space its self for example? Does space exhibit standing waves? Is there a gravitational wave equivalent to the microwave background? I think this also lends more support to multiverse theory. If there's imprecision to space itself and not just the stuff inside it, and all superimposed versions are equally valid per Heisenberg and that it can't observe itself, can we really say there's just the singular universe?

[@willowZzzzzz]

But why? If you're looking at a 'dent' in spacetime to see where a Q particle is, you're measuring it. Indirectly, but it's information. If we're asking why there's a general dent for all possible wave function possibilities, and that's the problem with unification, maybe assuming it's all just vibrating a bit is one explanation. Or we just don't fully get gravity yet. I dunno, my head hurts watching this stuff.

[@Kwauhn.]

@@ARabidPie I mean, the gravitational wave background is definitely a thing, we just don't have the instruments to map it out yet. I'd assume the fundamental frequency would be proportional in some way to that of the contributing quantum fields. And about the implications for a multiverse, I don't think this theory adds anything to the conversation since the issue still comes down to the measurement problem.

[@Kwauhn.]

@@willowZzzzzz The problem with unification is finding a mathematical framework that can replicate experimental data in all cases. This GUT wouldn't create infinities or paradoxes that you get by just jamming the two theories together, and it should be testable too. If anything, this theory is an attempt at providing some answers for unification. The presence of randomness in gravitational waves is a potential solution, not a hurdle. That said, you're right that it's probably not the full answer, if at all.

[@Nat-oj2uc]

Yeah prove that gravity is quantum first Einstein. No one can

[@ThePrimaFacie]

How I can some what understand the concepts shown to me by this channel is really the biggest mystery of this Space Time. Or its just the writers, animators, and presenters that do an incredible job. Thanks for the vids

[@derekbender]

Spreadsheets in SPAAACE

[@SmoothMike]

The semiclassical earth part: "our two earths would both be falling towards nothing. This seems odd, so this thought experiment rules out this semiclassical gravity." Idk seems less odd than a lot of accepted quantum stuff. Doesnt sound crazy to me that things have a slight gravitational pull towards the expected position of their quantum selves.

[@willikappler1401]

I was thinking about dark matter: stuff gets pulled to a position where we don't observe anything...

[@evangonzalez2245]

Yeah, that's my pet theory for dark matter. It's just the gravitional pull of our neighboring universes

[@BenAlternate-zf9nr]

Yeah, it would take something pretty extreme to separate the two quantum Earth superpositions by any measurable amount. I could buy that weird stuff might happen in that case.

[@badgermcbadger1968]

Except momentum cancels out in that case

[@nitswaa1935]

@@badgermcbadger1968 Could you elaborate? I was also confused why this was so quickly ruled out.

[@ianbarnhart7659]

I'm not an astrophysicist, or any type of physicist, but something struck me during the explanation of semiclassical gravity. If a hypothetical quantized Earth in superposition with itself would appear, to an Earthling, to be moving towards an invisible mass, then couldn't that explain how there appears to be a whole ton of invisible mass in the universe, identified and measured only by it's weird gravitational impacts? If one "zoomed out" even further, the thought experiment no longer seems so invalid. If we consider our entire universe to be one of a few superimposed possibilities, then it might explain why the greater universe appears to have so much more mass than we expect. It's almost horrifying to consider the possibility that any super-universal observer could collapse our entire experience into a single result, but it has that kind of odd elegance we see as the solution to many physics problems.

[@ariochiv]

Since space-time is supposedly a bubbling sea of randomly fluctuating quantum fields, it seems only natural that it would be gravitationally noisy.

[@Currywurst4444]

It's not randomly bubbling, when you look at the wave function quantum mechanics is still deterministic there are just very many interactions. This theory introduces a true randomness for gravity that has no underlying mechanics.

[@curtisblake261]

The random noise explanation opens up so many possibilities. Of course such a new idea will open up all kind of rabbit holes and dead ends. Exploring all the possibilities is what scientists are meant to do, Thank you for the in-depth analysis.

[@lehpares]

Was about time. We missed you

[@SuperKamiGuruu]

This topic weighs on my mind

[@pikotech1]

Randomly 😂

[@induspherix]

I feel vindicated now, knowing that the variable burdens on my mind may have been subject to change according to the whims of a theoretical Rando.

[@LuisAldamiz]

You treat atoms that are measuring each other all the time as if they weren't. All interactions are measurements, the position of every single atom of Earth is very precisely located all the time. Quantum effects only happen when you detach particles from their environment somehow (as in a particle collider, not in a compact mass where electromagnetic friction, chemistry, etc. is happening all the time).

[@dantefernandez2455]

GOSH DARNIT Y'ALL WOKE MA DOG!

[@CorwynGC]

the "translate to english" at the bottom really sells it.

[@suleyk4063]

I have learned so much from this channel. I would absolutely love some longer form lectures as well that really get into it or cover everything from the surface to the core.

[@rucker69]

Fascinating and easy to follow. We'll have to see how this develops but it's really exciting. btw that "spreadsheets in space" joke was spot on.

[@onepieceatatime]

The difference in volume of the video proper and the theme music is way too random!!

[@jakobr_]

Honestly I don’t see what the problem is with the semiclassical gravity idea. I think it makes a lot of sense. When there are quantum fluctuations in position, gravity acts to smooth those out and bring them back to “normal”. On the large scale we’d never notice gravity doing something weird unless every single particle suddenly jumped a significant distance all in one direction which is both unbelievably unlikely and also just a potential consequence of normal quantum stuff anyways.

[@irri4662]

I 2 like it 😊

[@CaptainKlugsch]

Thought the same thing!

[@josephlunderville3195]

There must be examination of whether this could explain dark matter

[@Rotten42164]

@@josephlunderville3195 Oppenheim announced later that this theory explained galaxy rotations which would mean no dark matter. So far I think that is as far as he has got with it. Interstingly this theory came to similar conclusion to Mond Gravity, but this is not a Mond theory as Oppenheim says repeatedly in his lecture I watched.

[@jojolafrite90]

The problem to me is that it implies apparently ONE space-time, ONE pre-written timeline, no free will, and one universe that exists by itself and that is basically just a movie that plays and can't vary from the one timeline it has to "be", and everything would be determined by advance since the first hypothetical instant. He did say it implied one universe. I don't like it.

[@DavidRexGlenn]

Whoever is the sound engineer for this show, needs to actually watch it as a viewer. The main segment sound is too low

[@Snakeybloo]

Just turn on stable volume

[@Snakeybloo]

Just turn on stable volume

[@gravestone4840]

@DavidRexGlenn Install any of the free equalizer apps out there. They let you turn volume up past your phone maximum and adjust the sound to your liking. Make a "too loud" and "too quiet" preset and youre good for any situation. Hope this helps in the future. To be fair to the sound engineer, there's no good way to account for every speaker type. They don't know if you're watching on a phone or TV or computer, they probably went for a medium that was roughly best for all types of sound systems.

[@zachb1706]

Yeah it was mixed weirdly. I turned the audio up to hear him, then got blasted by the intro 😂

[@m00nbeams42]

for true!! still looking for my eardrums

[@Practicalinvestments]

Going back to school in a week and a half so this is the perfect time to binge PBS space time and get in that ‘sciency’ state of mind

[@jasoncornish2904]

The apple falling towards earth analogy works for a single apple but breaks down when a second apple let alone millions of apples are considered. Have we not already observed that all objects fall towards the same center of mass? If the randomness theory held true would we not see objects falling towards multiple random centers of mass?

[@garrettbenedek1036]

The intro. You know what you did

[@luudest]

11:45 Is this a many world?

[@rlstine4982]

Is it randomness or an illusion of randomness because at these scales we lack instruments of sufficient precision to figure it out?

[@castonyoung7514]

If it were to just be an illusion then it would likely mean that all other quantum randomness is an illusion, and the uncertainty principle is just a human limitation.

[@FirestormX9]

Why is everything in hindsight not random but determinable?

[@EShirako]

Volume normalization might be VERY NICE BECAUSE IT'S HARD TO hear sometimes, and then it gets quiet at other times and then OH GOD (FontSize:32) THE INTRO MUSIC!

[@ambu.6707]

extremely good video, very intuitive. understanding quantum stuff got a lot easier for me when i was able to demystify wave particle duality / wave function collapse by realizing that particles dont actually “exist” as discrete objects but are rather quantized fluctuations of energy that can be modeled probabilistically and interact with one another. understanding measurement to be inherently limited to a single (certain, quantized) point of correspondence between energetic fluctuations in quantum fields, both wave particle duality and wave function collapse are illustrated clearly to be inherent to our limited perception - as we cannot observe quantum fields but only moments of correspondence between the quantized energy states we perceive as discrete particles. what interests me is 1. whether the privileging of this perception of discrete particles from which classical physics emerges appear to be deterministic due to the law of large numbers? and 2. whether the possible apparent randomness / probabilistic behavior of quantum behavior (including post-quantum gravity) is truly random (not deterministic) or if the apparent probabilistic behavior of quantum mechanics emerges from fundamentally unobservable yet deterministic laws that govern the behavior of fluctuations within quantum fields outside of these moments of correspondence a-la the hidden variable hypothesis? (lao tzu did say that the dao that can be spoken of is not the true dao - only half joking here, as the more i learn about abd demystify the woo around quantum mechanics, the more intuitive it feels, and the more i find common points of reference with daoist cosmology and philosophy) in any case, while i may not understand post-quantum gravity perfectly, as this video (for ease of understanding ) seems to have demonstrated the “particle seeking” behavior of quantum field fluctuations with fairly broad strokes, modeling the earth and the apple as discrete objects rather than an unthinkably complex array of fluctuations and interactions within and between various quantum fields, post-quantum gravity seems like a very promising theory that not only resolves issues with theories of quantum gravity, it may also hint toward the mechanism of interaction between fluctuations in quantum fields / wave functions beyond our hitherto limited capacity for observation and measurement, and the privileging of wave-particle dualism, wave function collapse, and particle correspondence as a result of the epistemological legacy of classical models of physics, a peeling back the veil in a sense, inciting informed scrutiny toward the limitations of extant theoretical models and experimental methodology. apologies if i may be slightly off-base in my understanding. i hope that im at least on the right track here.

[@sebastianbruyns2837]

Was there a real need to blow out my eardrums with that intro jingle?

[@talshafir10]

Came looking for jokes about the loud intro, Wasn’t disappointed

[@timokreuzer381]

19th century physics: Understanding nature to be able to make predictions. 20th century physics: Creating math that nobody understands to be able to make predictions. 21st century physics: Making up random stuff to avoid facing the fact that nobody understands anything.

[@garethdean6382]

The entire history of Sociology&Economics: Making up random nonsense that occasionally happens to work.

[@gordonstull1962]

Hermann Weyl taught me something about theoretical physics... It was about, what is meant by push & the electromagnetic spectrum versus the pull that absorbs the electromagnetic function. Your breakdown of the complexities of the force that pushes & bends outwardly are short lived... Simply because the force that pulls-straight inwardly into infinity is everywhere all the time in size & time... Thank you for your sacrifice to the discipline of quantum particle flow and quantum fluid flows respectively!

[@Nihil-2005]

EVE player here - I'm not sure if we just got complimented as a community, or if that was nerd-grade shade. Either way, caught me off guard - well played! 😅

[@UODZU-P]

Normalizing audio should be an automated process of video production... just saying

[@ZedOhZed]

I'll never understand why the uncertainty principle is assumed to be a fundamental property of particles, as opposed to being a limit to what can be known about particles. They will say "it's just a consequence of the math" as if God himself wrote the equation on a stone tablet and personally delivered it to Schrödinger.

[@CliffSedge-nu5fv]

You can do the math your self and prove it to yourself. No gods required.

[@ZedOhZed]

@@CliffSedge-nu5fv I'm not saying the math is wrong. The equations of QM obviously describe reality with incredible accuracy. I'm saying that the Copenhagen interpretation is absurd, and people believe in it with religious fervor. They conflate the equation with reality. The Schrödinger equation *describes* reality in the same way a poet describes a scene. The description may be perfectly accurate, but the description itself is not the thing being described.

[@johnduncan5117]

Yeah I really don't understand it either. It's almost as if they want to make it all sound so weird and cool. They're forgetting the difference between phenomena and noumena.

[@ZedOhZed]

@@johnduncan5117 Thanks for introducing me to the word noumenon. It succinctly describes what I was getting at.

[@johnduncan5117]

@@ZedOhZed haha I'm glad you found it interesting. I'm a philosophy grad who was always interested in physics. I often find it interesting that there is a distinct lack of understanding among scientists that since they are limited to grappling with what we can perceive (or indirectly perceive), there are limits built into what we can ever understand. As we get better at measuring and analysing, we uncover more. But we are fundamentally restricted to perceptual structures that our own senses and minds can comprehend. And beyond this, all objects by their natures will only ever be revealed through phenomena to us. Whatever we are using to measure them provokes an external interaction with our senses or apparatus. In the case of quantum mechanics, we say that particles behave like waves until there's an interaction. What we really mean is that this is what we perceive. Whatever is really going on remains a mystery, but I little reason to doubt that fundamentally causality remains total.

[@bernieburton6520]

I seriously doubt quantum gravity is a thing. We already know gravity is the warping of the very fabric of space time itself. It's not a field or force. It's just the curvature of space time.

[@ewanlee6337]

We don’t know that, it’s just the most intuitive explanation for our observations. Kinda like the interpretations of quantum mechanics.

[@Cosmalano]

@@ewanlee6337you should think more about what KNOWING means

[@CTimmerman]

Then gravity is just energy moving through Higgs marbles.

[@terraneko8999]

well we know that gravity is a thing and that the quantum world is a thing and that both dont fit together, so there must be some connection in any way, be it emergent gravity, gravitons or something else

[@Cosmalano]

Gravity is a force yes, a fundamental force. When people say gravity isnt a force, theyre being confusing either because they’re confused or they think that being confusing makes them sound smart. What theyre trying to say is that weight is a reference frame dependent force, such as the force you feel pushing you outward when you turn in a car or the one pulling you into your seat when you accelerate in a car. Weight disappears in freefall. Gravity on the other hand is an interaction everything experiences, specifically because everything is in spacetime, and the whole point of general relativity is that the components of the spacetime metric are gravitational potentials. That’s the point of the equivalence principle, and thats why gravity can be explained by the geometry of spacetime. We already have quantum mechanical descriptions of GR, the question is not about that and hasn’t been for decades. The question is, what is going on at high energies in quantum gravity, thats what quantum mechanics still cant answer. Thankfully black hole physics has told us that the theory should be holographic, but beyond that we don’t know still. That’s why stuff like this video feels pretty pointless to me. Even if it turns out for some reason that the low energy description of gravity theyre considering actually doesnt preserve unitarity by coupling to all these quantum mechanical sources of curvature and then just scrambling the information, that information cant be destroyed, so in the complete holographic picture of quantum gravity you would still have it. Part of, if not the entire point of holography is to say that the things you think of as local observables are actually non-local, so trying to make arguments about how the information exists locally seems like a pointless question at this point. Plus I’m pretty sure I’m being too charitable, I dont think this line of work has to do with holography, and is instead just an attempt to muddy the waters with an overworked “but maybe, right?”

[@zavar8667]

I don't understand why violating the uncertainty principle is problematic, yet destroying quantum information is okay.

[@spiritusterra5688]

I've had a theory for a while now, that gravity might be a phase shift in the position wavefunction, towards the source of the gravity. It might also explain the weakness of gravity compared to the other forces, because of the decay in the magnitude of a wavefunction as distance increases.

[@Anonymous-df8it]

But what if the source is itself in a superposition?

[@spiritusterra5688]

@@Anonymous-df8it I don't know, but perhaps the math might give a clue. I'm thinking that the situation you described would cause the shifted object to be in a superposition, with the overall variation relating to distance. Though, again, I am not sure.