What If Gravity is NOT Quantum?

[@mk1st]

That bit with the equations ending up with the Schwarzschild radius is like the universe is doing stand-up comedy and going “thank you, I’m here all week”

[@shipwreck9146]

It's always funny to me when stuff pops up where you wouldn't expect it to. Like, "oh wait, don't we already have that formula?" Or, "wait, the fine structure constant again?!?!?"

[@beamshooter]

Seriously, first time I saw this. As soon as that equation popped up, didn't think twice. I was like wait a minute... isn't that the... (matt says the rest for me)

[@benjaminshropshire2900]

The fact that it's just past the edge of possibility (rather than way past it or even say 7.3 times past it) seems extremely suggestive.

[@Merennulli]

To me, that coincidence strongly suggests the two are related somehow. The limit to measure something with the calculated properties of a graviton and the limit to which the curvature of spacetime matches the limit of causality feel conceptually very close to begin with. Though I'm sure people a lot smarter than me have already banged their heads against that obvious relationship for decades.

[@Z1g0l]

And adding "and you can do nothing about it".

[@evolancer211]

My favorite channel where I don't understand 90% of what's going on but still continue to watch lol

[@no_biggie_smalls]

At least you are honest. Most everyone else in the comments think they're Neil Degrasse

[@beamshooter]

The only way to really get a deep intuition is to dive into the maths. I reccomens the channel Physics Explained and ViaScience

[@danmurray1143]

You understand 10% of this!? You're a genius!!! I'm still trying to figure out what a kHz is.

[@jacobforbes1824]

99%

[@pavelborisov515]

Understand only 10% cos of the terrible sound audio compression

[@JoshWiniberg]

I love how in all this insanely complex science the one thing Matt chooses to clarify is "1khz - that's a thousand hertz". Thanks Matt, it all makes sense now!

[@daveziemann5111]

Yes!

[@DobromirManchev]

:D

[@mehdicirtensis]

I felt smart that he had to clarify this when I already knew it

[@shinigamidad]

It's his version of the "Everything is just according to keikaku" meme :)

[@JohnFitzpatrickx]

😂 lol. At that moment I was like, okay. I’m with you now. Lol

[@JackDespero]

The fact that from quantum definitions, such as the uncertainty principle and Planck's distance, one can derive a relativistic concept such as the Schwarzchild radius, seems to indicate to me that there might be something there that connect both.

[@bodycounter9386]

We have to be very careful here because our human brains are trained to highlight these kind of things and make correlations. Our universe does not have to work like this at all though. The main factor of stagnating advancements could actually be our brain itself because it always looks for symmetry, beauty and correlations.

[@Kronyx-k3r]

it only makes sense that something about the size of or smaller than a graviton would be pulled towards it too much to not become a black hole

[@ravenragnar]

This is what S tier quality content looks like KZbin. Promote more of THIS and less REACTIONS/PUNDITS/CLIP CHANNELS to the world. Signed the Internet.

[@isetmfriendsofire]

Won't happen. It's about what makes them money.

[@YogiMcCaw]

@@isetmfriendsofire And that will be society's downfall. It's simply not worth saving our civilization of if doesn't show a profit on the quarterly report. Don't you agree? All corporate law does.

[@schmidth]

Sad, but true ​@@YogiMcCaw

[@tuvoca825]

But you just listed the easy-to-make, emotional junk food of narcissists and lazy content creators. 😂 They want eyes, not masterpieces. Until a fool and his money develop discerning tastes... corporate economy's of scale will demand the product that suits their needs... not humanity and culture and intellectual growth. Eventually the wheels fall off because commoditization of people can inky destroy the ecology of the marketplace and produce spoiled little karens who understand only how to consume...😂🤣😆🤪🫣🤫🤔🤑

[@stordarth]

The fact that the graviton detector model maths spat out the Schwarzchild radius and so would prevent any confirmation of the existence of the graviton made me laugh more than it should have. The irony is amazing. "We did it! We made a graviton detector!" "Awesome! Where is it?" "In that Planck-sized black hole in the cor..."

[@adamwarlock1]

Yeah that was dramatic irony worthy of a crime thriller.

[@cezarcatalin1406]

But you need to read through the irony and observe the hint. When you have gravity manifesting on the plank length it is in the form of event horizons. So, what we really need to measure is the interaction of event horizons with gravitons. I guess we need to build a particle accelerator strong enough to produce nanoscale black holes.

[@bitterlemonboy]

Maybe the detector only turns into a black hole when it detects a graviton. That's still a detector.

[@frun]

As Susskind once said:"Quantum mechanics is always like that. You make an experiment to check whether something is happening and the experiment itself makes it happen".

[@pekkavirtanen5130]

@@cezarcatalin1406 if it's "Nanoscale black holes" then light can't fit in it?

[@Gnomaana]

This always confused me. Doesn’t Einstein’s theory mean that gravity is NOT a force but the curvature of Spacetime? If so, why would it act the same as the other “forces” and have any need to be quantized?

[@sofiarupil7746]

Because some physicists are stubborn and they want to be the new Einstein when in fact we already have a magnificent theory of gravity called General Relativity

[@pabloagustin8775]

Because you are right, not confused at all. Graviton is just a fantasy like the bigfoot

[@garethdean6382]

The issue is that relativity is not a theory of everything, its math doesn't work with quantum theories, so it explains gravity but ONLY gravity. Its success there doesn't man that it must be the final answer. I am locked out of my house. Einstein has the key to HIS house, it works 100% of the time, brilliant. I'd still like to know how to get into his house *without* the key, since it might help me get into all houses, including mine, especially since my key is on the kitchen table. His key is very nice, but a non-key solution would be best here.

[@ewanlee6337]

The electromagnetic force is also the curvature of the electromagnetic field so it’s not unusual.

[@darrennew8211]

The primary problem is this. You know how "the electron goes through both slits"? Where's its gravity while it's doing that? You need to quantize gravity so you can have quantum particles (and all the weird that goes with them) that have gravity.

[@TharunAshKetchum]

Matt I did the survey, just for you! To show my gratitude towards you. So kind of you for posting videos that helps me to increase my knowledge and intelligence time to time! I eagerly look forward to more videos from SpaceTime! ❤

[@TazTalksYouListen]

11:51 - Thank you for clearing up what a kilohertz was. Everything else in this video is easily understood, but without knowing what this strange kilohertz thing was, none of it would have made any sense whatsoever. So, thank you again.

[@liamroche1473]

🤣

[@orionred2489]

Remember the Carl Sagan Cosmos about the constellations? The French call it La Casserole...The Casserole.

[@davecool42]

The way the slowly zooming stars do a parallax scroll when Matt is moved around the frame is just perfect.

[@charlesheyen6151]

AND his hair is gorgeous! lol

[@istrumguitars]

Right so true. I’d love to see the star effect giving some illusion of movement over the still background too

[@BrightBlueJim]

This is the natural consequence of Matt being several thousand light-years tall.

[@chriswhite599]

I hope someday all of humanity understands how important these videos are. Incredible work by Matt and the rest of the team; truly a gift to humanity

[@amaliaantonopoulou2644]

THIS VIDEO AND ALL THE PHYSICS CHANNELS DO THEIR BEST AND THE KNOWLEDGE THEY OFFER IS VALUABLE BUT IT WILL TAKE A LOT OF TIME FOR THE YOUNG GENERATIONS TO UNDERSTAND THE REAL IMPORTANCE OF THESE VIDEOS BECAUSE THEY SPEND MOST OF THEIR TIME EVERY DAY WITH EVERY SILLY THING THEY SEE IN THEIR SMARTPHONES.

[@afonsodeportugal]

@@amaliaantonopoulou2644 Why are you screaming? Did you forget to take your medication again?

[@CasperEspresso]

I guess this is what sets people apart. Interest reveals depth.

[@krashd]

@@amaliaantonopoulou2644 Light the caps lock key?

[@lordgarion514]

It's VERY interesting, but a video saying we don't know, isn't overly important. We already knew that we don't know.

[@JosePineda-cy6om]

The more i become convinced Emergent Gravity proponents are onto something... gravity doesn't act at all like the other forces, most likely becouse it's not a fundamental force but rather an emergent one, like pressure

[@sewoh100]

I think as we begin to grasp the fundamentals of our universe, we'll realize so much more "fundamental phenomena" are really emergent from other, simpler things

[@melgross]

I agree. I’ve been saying this for decades. Einstein himself didn’t really believe gravity was a force. Even now, it’s sometimes described as a force under certain conditions, and as not under others.

[@Vorpal_Wit]

Gravity is definitely not a fundamental force. My guess/theory is that its an emergent property - an artifact of the expansion of the universe. This would explain both why it appears to be irrelevant at the quantum level, and why its indistinguishable from velocity. If it has any association with quantum physics at all, it will be because the expansion of the universe is found to be a quantum phenomena.

[@melgross]

@@Vorpal_Wit it’s interesting, but gravity depends on two factors, space and mass. Take either away and there’s no gravity. I compare it to a moire, where you need two (or more) sheets of lines of clear plastic, one over the other at some angle, to create it. If we think of one as mass and then other as space, then take one away, the moire disappears, showing it’s not fundamental as the lined sheets are. To me, this means that the search as to how to quantize gravity is useless, since it’s not a force to quantitze.

[@brad4268ify]

@ss agreed everyones way of thinking is wrong. for example when you jump out of a building. you are stationary and not moving its like being in a space ship and jumping off once the acceralation from the ship is gone your stationary in space.. you are not falling to the ground.. the earth is a spacehip moving through spacetimethe Earth is racing towards you and collects you like a bug on a windshield. there is NO gravity involved cause your not falling. I don"t Understand how you can detect something that doesn't Exist

[@edifiedx]

I want to thank Matt and the rest of the staff. This is my favorite channel of all time.

[@LandonKuhn]

And space!🎉

[@miketriesmotorsports6080]

Of all... Spacetime!

[@butHomeisNowhere___]

This is my favorite channel on the Citadel 👍

[@RetroSpectrum7]

​@@LandonKuhnhahaha you beat me to it!

[@Decimus-Magnus]

*Kanye:* OF ALL TIME!

[@tomblaise]

This gives me a good enough reason to live the next few trillion years. Who can be done with life when we still don’t know if gravity is quantized?

[@danmurray1143]

You don't get it yet. There is no gravity. There is no distance. All illusions. There was never a Big Bang Tom. We're still in the singularity!!

[@blacknoir2404]

it might be possible

[@815TypeSirius]

The largest structure mimick the smallest so the quantum field is a ansitropic and chaotic strands and nodes system. In short, its literally impossible for two things to be the same and you could never cut something exactly in half. Everything is asymmetrical. But humans are so stupid idk if they figure this out before I die lol.

[@flopsnail4750]

​@@danmurray1143but... Cake!

[@BunnyOfThunder]

This is basically my answer to "You wouldn't want to live forever because you'd get bored!" Nope. There's a lot of Universe, and it has mysteries.

[@SuperLoops]

15:05 I literally got chills when that equation appeared. is that as weird/spooky as it feels?

[@t9h3m]

Same, something about following the reasoning of the only method we've now got for measuring gravity waves ending up with a resounding "nope, that's actually *precisely* impossible" is pretty spooky.

[@PADARM]

It's incredibly ironic. Trying to quantize General Relativity leads us directly to a General Relativity law 😂

[@lemonke8132]

knowing math it's probably not a coincidence

[@matthews1256]

Why must everything be "literally" these days? Can't you just say "I got the chills"? The English language is being raped....

[@morimur36]

​@@matthews1256This is, quite literally, ridiculous.

[@Nonamelol.]

It’s crazy how literally the most recorded/observed universal force still remains a mystery.

[@omarmassad3041]

Of course "it's crazy" ! Because the [Universal Force] you are talking about is simply [Allah Force] God Almighty, and as mentioned in Surat Al-Hajj in the Holy Qur'an: "Do you not see that Allah has subjected to you whatever is on the earth and the ships which run through the sea by His command? And He restrains the sky from falling upon the earth, unless by His permission. Indeed Allah, to the people, is Kind and Merciful." God has bestowed upon us the gift of contemplation so that we may contemplate His creation and how He controls this great universe in a way that exceeds the ability of any creature and in a way that is unimaginable. "The Great" is one of the most beautiful names of God.

[@EnlightenedMinarchist]

Lol. Thats only true if you assume gravity is a force and not a geometric property of space-time.

[@joeycracknl]

​@@omarmassad3041😂

[@markz9739]

um....@@omarmassad3041

[@recursiveslacker7730]

@@omarmassad3041there’s a bit of an issue with lack of peer review there.

[@ShaneSchofield52]

You know, some years ago when I first started watching these Space Time episodes I had assumed myself pretty knowledgeable on the topic for somebody without a formal education, only to find myself rewatching episodes again and again to grasp ideas... Nowadays, I acknowledge the fact I have absolutely no knowledge on the topic and yet somewhat bizarrely only require one playthrough to understand what is being taught. That is to say, Matt has a fantastic way with words that has managed to educate a Dunning-Kruger effected simpleton like myself.

[@kiegal4499]

Same here mate!

[@plr985]

Add me to this club

[@psyopsvictimBr]

Now I just need two playthroughs

[@itsaxZOMBIE]

Me too! I think it has to do with memory and retention… i fully understand as it is being explained, but a week from now it’s gone.

[@humanbean3]

im a dumb smart person too hello

[@Ruprict2001]

I always wondered: why would it be quantum if gravity is just curvature of space?

[@naaaalex]

Because if it is not, we are just left with an infinite curvature at the center of black holes. Yet at very small scales the interaction of forces (which are quantizied) and gravity has to happen and prevent this infinite curvature. If this is so then it means the gravity also has to be quantizied at least at the Planck's scale which is the common assumption in string theory and quantum loop gravity. Physicists really don't like infinites and making these infinites disappear is also one of the strong theoretical engines that led to the progressive unification of forces within more and more general theories.

[@ObjectsInMotion]

"Why would EM be quantum if light is just a wave?" Gravity is just the curvature of space, and space itself could(and probably is) quantized.

[@ailblentyn]

According to GR, even a single electron must curve spacetime a tiny bit. And since an electron is a quantum object, its curvature of spacetime would have a quantum nature. That’s my understanding.

[@dbutler1986]

I also don't understand. I don't understand why gravity is regarded as a fundamental force at all. If it's the shape of spacetime that causes matter to move, it seems to me it's a property of spacetime rather than a separate field/force like electromagnetism etc., and gravity is a wave in the medium of spacetime rather than a wave in some field; and even if spacetime is quantized, then gravity would be quantized by association, not because it is carried by a boson of some kind. I'm sure I'm missing something. Also, how were weak and strong forces shown to be quantum without the positive/negative trick?

[@bigbigbigbigbigman]

@ObjectsInMotion Prove it lmao

[@matthewgootman5990]

Survey completed 💯 Also - been watching since high school. Now a fourth year physics and math major. Thank you for inspiring me. Matt is the greatest.

[@PlanetXMysteries-pj9nm]

"Your videos always leave me in awe and eager to learn more about the mysteries of the universe. Thank you for fueling my curiosity. "

[@PowderedToastMan477]

I will never be not amazed by people who REALLY understand math. You people are gifted beyond believe.

[@derangius]

You are only one good math teacher away from the same. My math inspiration came from a video game that actually made what I was trying to calculate perfectly visual (Kerbal Space Program) Bad unthinking teachers that teach for the money will make math seem impossible because they are either incapable or unwilling to make it relatable.

[@Blackstar-ti4py]

We humans are not, they are tho 😂

[@PURGE-3000]

You have to learn it. Hard work. Nobody naturally understands it. It’s hard work and dedication

[@facts9144]

Study and work as hard as people who do and you will too

[@danilanaumov4081]

It's not really a gift, it's abstract thinking. Math doesn't exist in reality, these people just can imagine things better.

[@jordanschriver4228]

1:36 I think you've got the strong and weak nuclear forces switched up there.

[@doormat1]

I was thinking the same thing and I was surprised. No one else had noticed it until I saw your comment. The strong force is the force that holds together atomic nuclei and the weak force is responsible for radioactive decay and the pictures that they showed were exact opposite of that and i was like why didn't they notice it? More than that, why haven't they responded to it?

[@blshouse]

Mistakes are nessissary. They allow for the testing of the quantum nature of knowledge and its force carrier education.

[@kjv35]

looks like nothing mediated your education on how to spell "necessary" @@blshouse

[@blshouse]

@@kjv35 Missed takes are necessary. They allow for the testing of the quantum nature of knowledge and its force carrier education.

[@serotoninsyndrome]

Came to the comments section to see if anyone else was talking about this lol

[@recurse]

I'd love to see you explore this question more - what would be the implications if gravity simply is not quantum?

[@annoloki]

Um... we would feel the effects of gravity of everything in the universe, pulling us "outwards". The effect would be immeasurably small, and completely counteracted by far greater forces pulling things together, but it would be there nonetheless.

[@recurse]

@@annoloki I think that would be way more interesting if explained at more length by a sexy Australian man, thank you 😃

[@Takyodor2]

@@recurse Did you just _assume_ that the person who just answered you _isn't_ a sexy Australian man?! 🤨

[@recurse]

@@Takyodor2 I assumed they were a 780 pound Japanese Macaque, but it makes like difference when you can't see or hear them 🙄

[@Takyodor2]

@@recurse I'm going with sexy Australian, but each to their own 😆

[@meekerdb]

Matt discusses the near insurmountable problems of detecting the graviton (if gravity is quantum). But the question was what if gravity was NOT quantum. What if it's entropic gravity as contemplated by Sakharov and Padmanabhan? That's the question I expected to be addressed. How could we test those theories.

[@genoproducto]

Thank you PBS Spacetime and Matt for teaching us. ❤

[@henrythegreatamerican8136]

I need to stick to easier topics like "What if the tooth fairy really exists"

[@jedgould5531]

Matt? Oh, you mean Floating Matt? jaja

[@dw620]

🐜 I still want to know how we quantize gravity to describe the scale of effect on each other of dancing ants at opposite ends of the universe... 🐜

[@ronniabati]

Wow! That’s uncertainty principle calculation for gravity beings us right back to general relativity 😮

[@TheBrightmanFan]

amazing right? like if the universe is trying to tell us something

[@kiteinthesky9324]

Relativity probably already explains quantized gravity, or relativity is a predictable result of quantum mechanics. Like an emergent force.

[@Sinnistering]

If gravity ends up not being quantum, then I fully believe quantization will end up just being a more concrete example of some abstract quality that gravity also follows, similarly to how particles are just a convenient understanding of the excitations in fields. That said, the argument that "a graviton detector will turn into a black hole" is extremely compelling to me for non-quantized gravity, but it depends on how well-done that thought experiment was and whether there are any subtle assumptions lying in there that we can pick apart. (Maybe it's just because you guys and Dr. Becky posted at the same time, but I can't help but think of the issue with finding dark matter as particles too. Though that line of thinking has been pretty ravaged by bad PopSci and regurgitations, I feel like, so it's hard to approach as a layman who wants to be rigorous.)

[@gray12566]

You know one thing that Matt said in an earlier video that I'm going to keep with me for the rest of my life. There really aren't any singularities. A singularity points to a gap in our understanding. Solving the singularity leads to new knowledge.

[@NatePrawdzik]

It's always seemed a little strange to me. To use an analogy: Gravity is a measurement of the bending of space (space flowing around mass) like light around an object could be measured by the shadow being cast. But you'll never find the particles that make up a shadow.

[@endlesswar7480]

Yes, I do like this comment!

[@JetskiDex]

That’s just excellent!

[@ObjectsInMotion]

That is untrue, you can find the particles that make up a shadow. Not in every day life, but the absence of particles in a medium act just like particles do. For example, holes in a semiconductor are like electron “shadows”, but they act just like positrons. Particles are not physical in the way people think, they’re excitations in a field. All this is to say, just because gravity is “just” the bending of spacetime, doesn’t mean it doesn’t make sense to think of it as also being made of particles.

[@gretchenchristophel1169]

Yes....only the Shadow knows. 😉

[@condor237]

It’s just as weird as things not having mass until they interact with a Higgs boson

[@to-rome]

It'd be cool a video about negative masses and why they are not considered. Thanks Matt for the cool video!

[@ELECTR0HERMIT]

I read online a negative mass sphere drawn to ordinary mass would accelerate to infinite speed

[@liamroche1473]

If negative masses existed, it would likely be possible for a combination of particles to spontaneously appear without breaching energy conservation (eg some mass as a mix of particles and antiparticles, and some negative mass as a combination of particles and antiparticles (the idea of the mix is to ensure all conservation laws are respected). It's doesn't have to add up exactly - some kinetic energy will make it balance. As this is not happening it seems negative mass does not exist.

[@davidhand9721]

There _is_ a PBS SpaceTime episode on negative mass. It isn't taken seriously because it doesn't make any sense on multiple levels. Others have mentioned the stupidity that happens when you try to give gravitational equations negative masses, but it gets stupid under just conservation of momentum. Angular momentum, as well. In quantum field theory, all particles' masses are generated by psi•psi* terms where psi is a field, so it can only generate particles with real positive masses, as well.

[@liamroche1473]

@@davidhand9721 To be complete, it generates zero mass particles without problems.

[@iggswanna1248]

Its "Dr" Matt

[@xan0075]

Question: What if we assume gravitons are real? Can you make a video(if you haven't already) about what would that mean for quantum mechanics? Can we use hypothetical scenarios with gravitons to explain the universe with precision? Also, I love your show. You're the best!

[@niks660097]

there is no globally accepted maths for quantum gravity, and every single one doesn't explain all observations, everyone is waiting for experimental physicists to give them some weird anomalies so that they can find a path..

[@Rynas]

Error at 3:45. His name is Niels Bohr and not Neils Bohr....

[@knutholt3486]

Niels is a Scandinavian name (Danish) pronounced "nils", with a short i like in "bit". By the way, the Danish language is nearly the same as Norwegian and Swedish, but with an incredibly soft and blurred pronunciation. Everything said in Danish has a certain uncertainty that the listerner must take into account when listening to it. That also holds for Danish listeners. The phonetic opaqueness of this Scandinavian dialect makes guessing based on insuficient bits of information a great part of Danish culture. I am not joking. It has been studied scientifically by linguists. I wonder if the Danish man Niels Bohr's thinking was influenced by this cultural impact, because what he claimed about QM is far from clear. The Copenhagen Interpretation is as messy as it can be.

[@HeadCannon1776]

The I and the E are quantum entangled.

[@Rynas]

​@@knutholt3486 I am in my comment stating the obvious fact, that his name is spelled/type wrong. I am not going into the pronounciation at all. I know ALL TO MUCH about how english speaking people tend to get that name wrong: The fact is, that I am danish and my name is Niels Peter + more than half my family is english speaking (scottish and new zealandish) - and for 50+ years my aunts still pronounce my name as Neils (which makes my ears cringe)

[@knutholt3486]

@@Rynas Well, I guess the Danish pronouciatian imply the phenomenon called "stød" in Danish that to an English listener may make it sound like "neils". The phenomenon is a slight and rapid restriction of the vocal cords. Swedish and Norwegian do not have that phenomenon, but instead tune differences. By the way, also English is a phonetically rather blurred language and with a crazy spelling standard, so giving all this you cannot expect otherwise. I remember my first English class at school when the teacher told that the words are not spelled quite like they are pronounced and said that each word you must learn it two times, as it is spelled and as it is pronounced. I immediately decided that this garbish I will not make any effort to learn. But over the time I learnt English well enough just from the sideline without much work. So after som years I got good marks also in English. But still I do not take English orthography really seriously, and I use rolled tongue tip R rather than the horrible retroflex approximant used in America and parts of England. But otherwise I use American pronounciation. Thus I manage to doctor up English to a reasonable level of clearity.

[@_abdul]

This is definitely going in my "Most Mind Bogg-Ling stuff I watched in 2023" list. Love it.

[@johnburke568]

Not

[@brubrusuryoutube]

matt im a neuroscience researcher now, i started watching the channel when i was 13 or 14 when the other host was still there. I am super excited about your documentary and i think itll be the only documentary ill pay for directly... when is it coming out? (the documentary analyzing how our brain constructs reality and the biases that arise in our conception of physics as a result) thanks for pbs space time for being an S tier channel for years now... you guided my intellectual development in ways i probably will never be able to truly appreciate

[@Spoth8417]

The best part is when, in the middle of this very complex subject, Matt says, "...one kHz, that's 1000 hertz." Thanks Matt 😂

[@HoD999x]

1 kb is 1024 bytes

[@feandil666]

@@HoD999x no, 1KB is 1000 bytes, what you're talking about is a 1KiB (en.wikipedia.org/wiki/Binary_prefix#kibi)

[@UODZU-P]

@@feandil666 Quoted from the wikipedia article: Note: in information technology, especially for measurements of memory capacity in bits or bytes, it is still common to use the decimal prefixes "kilo" (with symbol "k" or "K"), "mega" ("M"), "giga" ("G"), etc, to mean the closest binary prefixes "kibi" so congrats on being pedantically correct. the worst kind of correct.

[@EeeEee-bm5gx]

​@@UODZU-Phe's very pedantic, granted, but riddle you this: who is even more pedantic with no sense of fun or self-awareness? 😂

[@dougr8646]

Hey man, they're called minor attracted people now

[@mathieudespriee6646]

Amazing video. The appearance of the schwarzschild radius blew my mind. The relationship between Heisenberg, planck length, and black-holes is crazy. Did we stumble on a kind of circular reasoning? Or are we facing a fundamental relationship?

[@VorpalGun]

What are the alternative theories of everything that doesn't rely on gravity being quantum (if it is indeed not)? I feel like that was missing from this video.

[@SashaRomeroMusic]

I second this. It seems to me that if gravity isn’t quantum, the only options for understanding physics is either we need a new way of thinking of the unification of physics, or physics includes fundamental paradoxes and inconsistencies, which would be absolutely wild for science.

[@angelmendez-rivera351]

The alternatives are basically knows as "gravitization of quantum fields." Instead of quantizing gravity, we gravitize quanta.

[@nl5h]

@@SashaRomeroMusic do we need a unified theory?

[@Vastin]

I'm not sure we have any particularly good contenders honestly. The problem with gravity being non-quantizable is that it immediately re-introduces the concept of infinities and div/0 and a bunch of other paradoxes that quantization generally prevents - which is why most physicists are convinced that it has to be quantizable at some level, because reality basically shouldn't work otherwise. :D That's not to say there's not another possible non-quantum theory, but it would likewise have to sidestep those same problems, which is a fairly high hurdle.

[@ObjectsInMotion]

To put it short: there are none.

[@wojciechszmyt3360]

Amazing episode! Thank you, I've learnt so much about cosmology from your show 😀

[@duetwithme766]

So what happens when you consider the possibility of black hole analogues for the other force carrying particles at sizes beyond the planck length?

[@billwerth2]

The equation for gravity, includes the mass of two objects and the distance between them. These objects are normally moving over a period of time. One could say, gravity is just a function of the movement of an object over time through space. Or space time. Maybe gravity isn't a force at all, but just a measure of how space time is affected by masses moving through it.

[@IronFairy]

Looks to me like the programmers who coded the gravity didn't really talk with the people who coded all the other forces.

[@kaitlyn__L]

“You did everything with floats? But we did it all with ints! Ugh great, now I can’t just increment or decrement everything!“ And… black holes are a glitch from bodging them together somehow? I know a decent amount about how computers work on the circuit level for each module (register, accumulator, adder, what have you) but the wider structures in programming elude me so the metaphor breaks down there… (much like quantum gravity itself!)

[@AndrewBlucher]

Thanks for the explanation of Freeman Dyson's analysis. I wasn't aware of it before. Loved the idea that a 10^37 improvement in sensitivity was "challenging, but ... not impossible"!

[@mrgadget1485]

Physicists are extremely careful in choosing the words they use - that kind of sentence is very typical example of that.

[@Duiker36]

FYI, Freeman is his first name and Dyson is his surname.

[@AndrewBlucher]

@@Duiker36 Lol, I better fix that!

[@Kohl293]

That Schwarzschild radius equation is the biggest middle finger in physics since the vacuum catastrophe

[@Jay-nj1rq]

Haha right (please explain, I have no idea what you’re referencing and want to know) 😬

[@Kohl293]

@@Jay-nj1rq This channel made some videos on it. Essentially, empty space has energy that contributes to dark energy. We tried doing the math (on the quantum physics side), but we predicted that a teacup of vacuum has enough energy to boil the oceans. Like 10^120 times off what it should be. Widely cited as the worst prediction in all of physics.

[@arielperez797]

imagine the opposite of gravity is time? time wants to go forward but gravity does the opposite and wants to go backwards. they kind of cancel each other out. thats why gravity is weak and only goes into itself and time is slow and goes outs into the future only.

[@BobbieGWhiz]

I completely understood 1×10 to the -37th of this video.

[@pdxmusl1510]

😂

[@howardlandman6121]

Unified semi-classical theories have been available at least since David Apsel in 1978-81, or maybe even Kaluza-Klein in the 1920s. Maybe we should try quantizing those. Also, if you put the (Newtonian) gravitational potential into the Schrödinger equation, then the shifts in quantum phase frequency with energy look eerily similar to gravitational time dilation (in fact they're identical to first order); following that idea leads to some interesting perspectives.

[@NicodemusParadiso]

Hey there, love your videos! I usually watch with subtitles on and noticed a few transcription errors in this video, some of which might make some people grumpy. 1:40 Quant gravity -> quantum gravity 3:28 the mid 192 -> the mid 1920s 4:49 one AIS of -> one axis of 5:33 field so bour and rosenell -> field so Bohr and Rosenfeld 7:32 principle but war and Rosenfeld -> principle but Bohr and Rosenfeld 8:42 B and Rosenfeld -> Bohr and Rosenfeld 9:11 B and Rosenfeld -> Bohr and Rosenfeld 10:41 the two Lio facilities -> the two LIGO facilities 11:06 gravitational W of detector -> gravitational wave detector 11:30 a ping 5 m 630 NM red -> a piddling 5 mW 630 nm red 11:47 10^ of -1 Jew per cubic M -> 10^-11 joules per cubic meter 12:00 3x 10^-48 Jew per Cub M -> 3x 10^-48 joules per cubic meter 12:20 10 37 -> 10^37 12:29 10 ^ of 37 -> 10^37 15:16 for the SQA Shield radius -> for the Schwarzschild radius 15:27 black coal -> black hole 16:49 vein as the B Rosenfeld -> vein as the Bohr-Rosenfeld

[@KatjaTgirl]

Thanks for putting in the effort! Some of these are hilarious...Jew per cubic meter... lol

[@WmJared]

thank you please @PBS see this and bless you @nicodemusAllenTonar

[@themagiccookie2614]

I love the fact I just begin theorising and mindstroming as soon as we started the questioning!

[@mcampbell6651]

Thank you for covering this subject. I have thought gravity may not be quantified but was always told you’re wrong campbell

[@paulbrannan4119]

I'm still confused: what is the answer to the question "what if gravity is not quantum?" In other words, what are the implications for physics if gravity really is non-quantum? Would that be in any way paradoxical? (btw, loved the episode as always -- it's amazing how much awesomeness you fit into one of these little videos)

[@tellmemoreplease9231]

Good question.... The real paradox would be if two quantum particle (that occupy a different time slice) come in close proximity? Would one particle know the future event about to effect both??? I know that sounds kind of sloppy, but you know what I mean?

[@Merennulli]

Gravity doesn't need to be quantum. But everything else is so it's the obvious first thing to try. We need SOME new explanation for gravity, though, because our current theory breaks down at quantum scales. I was assuming he was going to explain what non-quantum ideas existed, but I guess not. I don't actually know if they do exist myself.

[@drachefly]

@@Merennulli Also, if quantum mechanics is correct and complete but gravity isn't, then you'd end up with mass being attracted to places things… could have been? So if gravity isn't quantum yet that doesn't happen, then you need to augment quantum mechanics with an actual collapse mechanism that actually happens rather than just using it as a good approximation. And that would be MESSY.

[@Merennulli]

@@drachefly Whether gravity is quantum or not, the attraction between masses is between the average of the probability distribution. You're just applying a Feynman diagram to gravitational attraction either way. If gravity is a quantum field, then it just makes the factors quantized, it doesn't change the result. That quantization adds granularity to it, but that granularity is so small the detector for it would become a black hole (the equation he gave in this episode).

[@drachefly]

@@Merennulli But when do you cut off the quantum treatment? If you position a large mass based on quantum-generated information, gravitational attraction is not going to be based on the CM position of the widely separated wavefunction parts - it's going to be based on the outcome we've observed. Gravity is inside a quantum world; it can't just be not quantum at all.

[@jaker721]

This is so unbelievably fascinating. Thank you for making this. I really wanna see quantum gravity figured out before I die

[@iankrasnow5383]

That might require extreme life extension to be developed before you die. I'd be happy with seeing fusion power become part of our energy mix.

[@professorlegacy]

I always try to come up with one takeaway from these very complex, wonderful videos. For this one: "Nature prohibits us from figuring out if gravity is a function of discrete bits of information called gravitons by forcing the production of a black hole if we try to measure something at the miniscule size needed to do so. Therefore, the best way to observe gravitons would be indirectly, but we aren't there yet." My 7-year-old brain's takeaway is "We'd better get cracking on this because being able to turn gravity on and off would be dope. Also, let's make some tiny black holes!"

[@charleswagner2984]

We are probably making millions of neutron sized black holes that evaporate before detection in the large hadron collider every hour of runs. Not to worry though. They are as useless as a toothache because we can't get anything from them. They decay very quickly, like the higgs.

[@leizero]

I'm a big fan of Freeman Dyson's book "Origins of Life" as someone belonging to a field of science. I had no idea he also had such a big contribution in the field of physics. The man's a legend.

[@numbersix8919]

I read his autobiography. It's not very long. It's inspiring. He was always his own man.

[@mitsuracer87]

Amazing vacuums.

[@zacharywong483]

Fantastic explanations and visuals, as always!

[@WindsorMason]

Gravity pulled us all here

[@defeatSpace]

Or did it?

[@barkoz]

We simply followed the warp of space-time

[@69ing_Chipmunks]

Came here to make this comment. Well played sir, well played.😂

[@genghisgalahad8465]

Gravity doesn't pull. It just is.

[@tamikuru7936]

Pretty sure that electric potentials are more important for my brain than gravity 😂

[@tomsunhaus6475]

Every once in a while a presenter hits a superlative level of communication. I believe this video is an example of that. After doing so many videos, to achieve such excellence is amazing. Keep up the good work.

[@agett12]

Us: what's gravity really? Universe: Shhh don't worry about it

[@philharmer198]

Its a challenge to understand , for some of us . This Universe . Not you it seems , but many , many , many do .

[@OnAChairSitting]

@@philharmer198 Take , your meds .

[@imoutodaisuki]

​@@OnAChairSittingyo. U too . TakE your m.eds .

[@OnAChairSitting]

@imoutodaisuki Okay little buddy

[@philharmer198]

@@OnAChairSitting why ? What's the reason ? What do you disagree with me about ?

[@СергейБыков-ж1в]

Why in the fragment with four forces you have strong force for decay and weak force for holding nucleus together? Shouldn't it be vice versa?

[@plato1234plato]

Someone made a boo boo

[@dan7291able]

I ALWAYS thought we were looking for something that wasnt there too when it came to the Graviton, its a great idea to think about sure, that it MUST exist, but with everything he explained on how nigh impossible it would be EVEN if we DID find it, it just really always felt like, the answer lies elsewhere most likely, just always felt like Gravity is more of a MACRO thing not a micro thing Great video once again

[@thenovicenovelist]

Sorry if these questions are very dumb, but I'm genuinely curious about this: 1) Is this the reason why scientists are looking for a "Theory of Everything" that can combine General Relativity and Quantum Mechanics? 2) Is there a chance that anti-matter particles could be connected/related to negative mass?

[@pdxmusl1510]

1. We want a theory of everything because we want understanding..we know there are states that are unexplainable by our current theories. Relatively & QM do not play noce together. We could understand those states with a theory of everything. And they may lead us to new physics that could have real world applications in the future. Some calculations are really hard. A theory of everything may simplify some of the slog. 2. Not likely. It wasn't ruled out at the time... but We are just recently testing antimatter and how it interacts with gravity. The first studies suggest it behaves similarly. Although there are some proposals that antimatter may get its mass by a different mechanism.

[@moosemoomintoog230]

If we can't test for things we think gravity is, can we test for things we think it isn't to rule them out? Could we test for gravity being a function of the interaction between spacetime and higgs?

[@akospapanitz8390]

As far as I know that's the everyday work of theoretical scientists. Making models that could work and trying to prove or rule them out. I thing they made a video that taps on the topic

[@ontoverse]

If spacetime is quantized, yes, at least in principle. But quantized spacetime is as difficult to prove as gravity being quantized itself-- indeed if true, they would in some sense be the same. Spacetime is then the field in which the graviton would be a local standing wave, so measuring a quanta of spacetime is exactly measuring the graviton. A Higgs-interaction may solve dark matter (self-gravitating spacetime), but doesn't address gravitation or gravity itself. The mass contributed by the Higgs mechanism is so small as to be negligible when dealing with macroscopic objects. A vast majority of the gravitating mass in macroscopic objects results from the strong force and gluons are (probably) massless. A gravitostrong unification, mirroring the electroweak unification, would likely settle the quantization question-- but all attempts at finding such a unification have failed.

[@jsytac]

Not Quantum Gravity, but Quantum Spacetime!! One theory is that Mass slows time, which in turn bends Spacetime, which gives us the gravitational effect. So if Spacetime is warped by the slowing of time, rather than directly by mass itself, could it be time that is the quantum property, and as gravity is a consequence (not a cause), gravity is quanta due to its dependency on time.

[@handhdhd6522]

Quantum gravity is synonymous with quantizing spacetime. Both space and time are quantized. Maybe on the planck length/time scale.

[@jsytac]

@@handhdhd6522 but if gravity is the consequence, perhaps we should look for a quantum unit of time.

[@handhdhd6522]

@@jsytac there is a quanta of time, Planck time…

[@physikus1123]

It's strange that gravity is at the same time the "least quantisable" force of nature, but yet it's so fundamentally connected with light, whitch itself has been quantised. Great video!

[@peoplez129]

@@Fantredath Time isn't a force. It's a concept, not anything tangible. You don't need time to exist for actions to take place. People mistakenly think of time like it's what allows for actions to occur in the first place, like some guiding hand. But that's energy and velocity's job.

[@peoplez129]

@@Fantredath That's because everything involving time is just a reference in relation between something else. This is why photons are said to be outside of time, because when they're traveling through space on their own with nothing to encounter, no action is occurring. It may be moving at a fixed velocity, but it is essentially frozen in time. It's only when it encounters something that anything occurs or changes. Which means it needs to interact with matter in order for any time passage to occur, because we inherently tie the passage time to actions/change. Of course that's not entirely true, it's only a concept, because even light travelling through space has a reference point of time, and that is how long it takes for it to get to where it's headed, but we still only derive that passage of time from relation to other sets of objects, like the planet revolving around the sun. Since "time" is still occurring for everything else, that's the reference point, but time is still only ever a concept, not anything tangible. Even if you were to use a blackhole for time travel, you could only ever travel forward, not backward, and that's only because the nature of the blackhole changes the relation between other reference points. At that point it's not really time travel at all though, it's more like putting yourself in a stasis capsule. The main takeaway though is you don't need time to be tangible for things to occur. Time is merely our observation of interactions that we measure.

[@feynmanschwingere_mc2270]

@@Fantredath Einstein did more to elucidate the nature of time than anybody. We know time is NECESSARY but we don't know if it's "real." Frank Wilzchek's work on Time Crystals may shine some light (pun intenended) on this topic. You should Google it. Fascinating work.

[@feynmanschwingere_mc2270]

@@peoplez129 It depends. Photons, from their perspective, don't experience time. But that's based on the MODELS we use. See, time is a relational phenomenon. In quantum mechanics, particles make no distinction between "forward" moving and "backward" moving through time. However, WITHOUT time, all things would happen instantaneously. So surely time must have some relational meaning that is fundamental to all other phenomenon. I suspect the same "uncertainty principle" that limits how much knowledge we can extract from a system equally applies to time. How do we measure that which all else is measured by? It's a paradox.

[@DmitryAvenicci]

It is not connected with light - it's just the light, having no mass, travels at the highest speed space-time allows. And even then perfect vacuum is impossible so light travels a tad bit slower than c.

[@FoobRMann]

Has the idea that gravity isn't a force at all been rejected?

[@KennethLudwig]

I was reading an article by Ethan Seigel today where he was answering a question about if gravitational waves had wave and particle duality. He responded that we just don't know but that if we could figure out a way to do the double slit experiment with gravitational waves we could find out if gravity is quantum or not.

[@alphalunamare]

He clearly is a bit of a dip stick. Gravitational Waves are an effect not a thing.

[@gabesperber9958]

Very interesting! So, to do the experiment we'd need a way to "block" gravity to construct slits, or perhaps use something that already exists and distorts gravity like the gravitational lensing caused by galaxies that we can observe in space. I wonder how big would our 'sensor' need to be to measure see the interference pattern? Could we use the ones we have already for measuring the gravitational waves?

[@Syncoda]

Fantastic video as always! I am sorry to point it out and I only say it because I am Danish and super proud of Niels Bohrs achivements. You spelled his name as “Neils” but the correct way is “Niels”. Just thought I’d let you know. Fantastic video and Matt is fantastic at making it somewhat understandable.

[@binbots]

General relativity and quantum mechanics will never be combined until we realize that they take place at different moments in time. Because causality has a speed limit (c) every point in space where you observe it from will be the closest to the present moment. When we look out into the universe, we see the past which is made of particles (GR). When we try to look at smaller and smaller sizes and distances, we are actually looking closer and closer to the present moment (QM). The wave property of particles appears when we start looking into the future of that particle. It is a probability wave because the future is probabilistic. Wave function collapse happens when we bring a particle into the present/past. GR is making measurements in the predictable past. QM is trying to make measurements of the probabilistic future.

[@inthefade]

I think Wolfram's physics model that is computationally irreducible is going to give us the answer for how to quantise gravity.

[@jeancalude5021]

At timecode 1:38, I think you misslabelled the strong and the weak force. Besides, great video as usual :D

[@StrayVagabond]

I had this idea a long time ago that the "fabric" of space time has a preferred state, and that objects with mass disturb this state and gravity would then be the force of that fabric resting the change caused by that object. Like, for a really bad analogy, Imagine a field of rubber bands stretching across x y and z. Then you place an object among them, it would stretch those bands more around it, affecting a force against that object, pinning anything ON that object to it.

[@kirtg1]

i've always envisioned space-time and it's elasticity as Jell-O. When a mass like a planet moves through space-time and pushes the Jell-O out of the way, which wants to return to its original position this causing the pressure of gravity on the Earth.

[@GreatBigBore]

If gravitons exist, then what do we need curved space for? Honest question. I see that other people have asked about the "gravity is not a force" that we thought we learned from Einstein, but I couldn't find any answers in the ensuing conversations. Near the end Matt seemed to be saying that the notion of gravitons is kind of an open question, subject to potential future experimental confirmation, but that's the first I've ever heard that. Everyone always just glibly says that scientists want to unify the four forces, as though it's already known that gravity is a force (sorry Einstein!). Please, someone explain it to me like I'm 5.

[@TheBrightmanFan]

that's why graviton doesn't exist

[@william41017]

In classical mechanics the EM force is described by field lines that charged particles fallow. But this didn't stop physicist from quantizing it. Maybe the same could be done with gravity

[@jarirepo1172]

There are some explanations in the comments already. If I understood them correctly, it is assumed that gravitons create the field that shows up as curvature of space.

[@Ecelamie]

Consider the curious link between the Schwarzschild limit, which defines the event horizons of black holes, and the Compton wavelength, crucial for understanding quantum mechanics. What if these seemingly disparate scales, a geometric limit and a dynamic one, are connected by a process known as dissipative entropy, as explored in Prigogine's work, along with non-local long-range correlations? Taking Rényi entropy, which was discussed in a previous PBS video, as a form of dissipative entropy, we might find intriguing possibilities. One hypothesis around Rényi entropy involves the processing of imaginary spacetime topologies within black holes and their connections to black hole simulacra. This concept could serve as a bridge between gravity and quantum mechanics, suggesting that the expansive scale of black holes and the minute scale of quantum particles are both products of the same cosmic processes that shape the diagrams of matter-spacetime. The synthesis of these concepts could lead to a novel understanding of quantum gravity, where the universe's behavior is governed by principles that seamlessly integrate quantum entanglement, gravitational fields, and entropic dynamics. This unified behavior would reflect a cosmos where quantum and gravitational phenomena are different expressions of a deeper, entropic-driven reality. This perspective could offer a bridge between gravity and quantum mechanics, suggesting that both the geometric scale (Schwarzschild limit) and the quantum scale (Compton wavelength) are products of a cosmic process that shapes matter-spacetime topologies. I wonder if someone, inspired by Weirstrass' understanding of limits, as not static by dynamic, i.e. generated, produced, so if someone could derive the Schwarzschild radius and the Compton ray from dissipative entropy. Dissipative entropy goes beyond mere chaos; it's about the self-organization of the universe, influencing quantum states and spacetime's curvature alike. Imagine long-range correlations, akin to those observed in non-equilibrium systems like black holes, functioning like quantum entanglement but on a cosmic scale. Such correlations could elucidate the profound connections across different scales, pushing us closer to a unified theory of quantum gravity where the behavior of particles at the microscale and the structure of spacetime at the macroscale are derived from the same entropic underpinnings. The 'extremes' represented by the Schwarzschild limit and the Compton wavelength might be more closely related than we think, potentially linked through cosmic processes similar to wormholes (that may be the epitome of long-range correlations). This perspective implies that gravitational phenomena, from the macroscopic to the quantum level, are emergent properties arising from the same entropic interactions within the fabric of spacetime, challenging the traditional view of gravity as a purely classical force. Central to this discussion is the concept of nonlocality, which lies at the heart of quantum entanglement. By extending nonlocality to include gravitational interactions, we propose a mechanism by which quantum characteristics can impact and be impacted by the broader cosmic structure. This suggests that the universe is governed by entropic dynamics that effortlessly integrate the quantum and gravitational domains, pointing to the intrinsic quantum nature of all forces, including gravity.

[@jackwright7879]

What if the Graviton is indistinguishable from a Planck Length blackhole? The Graviton's whole deal is mass, right? A maximally small singularity sounds a lot like a quanta of gravity. Maybe I'm just delirious from having Space Time on in the background all week.

[@موسى_7]

I hope Matt reads this

[@no-one_no1406]

Wasn't the only one thinking this apparently! Nice!

[@lordgarion514]

No, mass is the "whole deal" of the Higgs Boson. The graviton, which probably doesn't exist, is the thing they think might transfer the "pull" of gravity across distances But Einstein stated gravity was the result of things following the curvature of space. If gravity is actually the curvature of space, and tests/observations say it certainly appears as if space is curving.

[@cereal-killer4455]

No gravity is not mass, a graviton is not a particle of mass, gravity is a variable of spacetime, so a plank length black hole would not be a graviton

[@cereal-killer4455]

@@موسى_7why? Michael bay can come up with a better theory than this, it is fundamentally wrong and funny to claim a graviton is a particle with mass

[@leekirk7323]

Great video, as always. Just wondering if there are any promising theories based on unifying the quantum forces with a non-quantum gravity?

[@JohnnyFontane528]

😂 non-quantum gravity. Can you hear yourself right now?! Someone didn’t pay attention in class

[@go-away-5555]

@@JohnnyFontane528are you trying to say gravity is quantized? (As far as we know, it's not) or are you laughing at the tautology of saying non-quantized gravity. I honestly don't get what joke you're trying to make. And when it comes to finding a GUT it's important to specify whether it will be from a quantization of gravity or a normalization of QM with non-quantized gravity. Non-quantized gravity does not have to mean GR, it can be an alternative theory that is still not quantized.

[@JohnnyFontane528]

@@go-away-5555 “(As far as we know, it’s not)”. That’s your problem, right there. There is no “we”. It’s YOU. You and your outdated modalities. No offense but you’ve got to start thinking outside your little 3d box

[@7orx]

Could it be that gravity is the "great decider" of quantum uncertainty? If a quantum superposition gets so "large" that it would create a superposition in the spacetime curvature, this automatically forces the wave function to collapse and stop the superposition?

[@castonyoung7514]

That's exactly what the people behind the 16:56 experiment want to disprove, and they seem pretty cocky about it. Honestly, they didn't seem very objective from what I remember.

[@lemonke8132]

but how could you have a discrete difference between when a spacetime superposition appears vs when it doesn't?

[@Anonymous-df8it]

You would still need a quantum of spacetime curvature. If you just left it continuous, then the curvature of a single electron would render it classical

[@7orx]

@@Anonymous-df8it maybe to explain a bit more what I mean: the effect of The curvature could not be impacting another particle by more than some value, maybe plank length

[@oxigenie]

If I understand correctly, this is exactly what is said in the Penrose interpretation of quantum mechanics: a quantum state remains in superposition until the difference of space-time curvature attains a significant level.

[@klausfrezza917]

The best explanation of gravity waves I have ever seen. Congratulations. Finally someone does not mention the fantastic curvature of space-time. Time and space being non material have no place in physics. It was Minkowski who led astray Einstein, who already believed in the Ether but later corrected himself. Great explanation.

[@godfreynjiiri8550]

These videos made me finally understand the concept behind "sounding smart." After watching plenty, I can parrot physics concepts pretty accurately but still understand nothing.😢

[@miki537]

You're not alone brother. It's still cool to be able to witness those amazing theories, even if we can hardly follow.

[@Playerofakind]

Learning physics takes a lot of time and practice, there are a lot of free resources you can use to get a conceptual understanding of it

[@sdm6054]

Neil Degrass Tyson made an entire career off of doing exactly this, sounding smart while understanding nothing.

[@AndrewBlucher]

Most Physicists are in the same boat; they can "do the math (or Physics)" but the meaning eludes them. This is where the brilliance of Einstein shone.

[@margodphd]

I'm on the opposite spectrum. I understand a fuckload but ask me to explain it like Dr Matt here, and I would probably need several boards, hours and audience hostage 😂 I've started two years ago, during some boring university function I ran into a young dude with unbelievable charisma that did some works for CERN and he introduced me to magic of physics. As I'm a dumb med person, my math education stopped with rude introduction to calculus. I highly recommend starting from scratch. Learning the basic concepts,re-learning the basics of basic math from resources like khan academy and organic chemistry tutor (amazing videos on even basic subjects up to calculus) + physics ninja and several others here on yt. It takes time,yea, but when something clicks finally, it's incredibly rewarding. I know I'll never be good good, I'll merely be able to benefit from the research of the greats but even that,in the age of easy satisfaction,is incredibly rewarding. Terrence Tao I am not and I will not, in million years be...and that's ok. You might also not have the talent, and that's a ok too. As long as you have the drive and determination, these things are within your grasp. You know, understanding is really the area under the time(effort) graph. As long as these values are nonzero, it'll increase.

[@asdasfghgf]

I'd love to know what breaks down with Liouville quantum field theory, a two-dimensional model of quantum gravity, when it's moved to 3 dimensions

[@NewMessage]

Graviton laser? I always wondered if that's what a 'tractor beam' was.

[@Ithirahad]

It would presumably be a device made up of some complex configuration of singularities. Once formed, I don't think you could move it except maybe by gravity tractoring it with an immense diffuse mass. Although electrically charged black holes theoretically exist, so maybe...?

[@mrgadget1485]

If gravity turns out to be quantum in nature, then gravitons should be bosons - therefore useful to produce a "laser", at least on paper ;)

[@pdxmusl1510]

Not sure what it is in startrek, but we already do this with lasers and sound.

[@PeterMoore-q5k]

Is it all that surprising that detecting a graviton (the smallest possible unit of gravity), if it exists, would be impossible since you'd need something smaller than the smallest possible thing to see it? Maybe at the end of the day everything fundamentally boils down to black holes?

[@alexandrerobert4100]

Thank you for the video. I love this content so much. Some maths today and also a strong question. If we can't detect a single graviton, do we really need to struggle to extract that theory from our beloved space-time? That's kind of fundamental. What about a non-serious video about muon-mediated cold fusion :) ? Or a video about spin echoes, Larmor procession and NMR ? I'm now working with it. Going for the patreon !!

[@theredlabcoat]

I love that this video is trending right now. Never thought I'd see a video on quantum gravity on that list

[@davidasher22]

Is it possible that gravity is actually a macroscopic phenomenon. Like the opposite of quantum? Something that can only be fully understood by zooming way out?

[@dritemolawzbks8574]

It could be. At the moment, we're impatiently waiting for the next Sir Isaac Newton or Albert Einstein to be the next genius of theoretical physicist to explain quantum gravity.

[@jajssblue]

I love any GR + quantum episode from Spacetime!

[@Nefville]

PBS Space Time is so good I got lost learning new things in the comments, so much so now I have to watch the video again. Its an immersive experience and PBS viewers are some of the most knowledgeable on the platform.

[@blackshard641]

Felt attracted to the general vicinity of this video by some unseen force.

[@arlogodfrey1508]

I do believe the reason higher-dimensional mathematics is so complex is because we've rooted the definition of orthogonality in perpendicularity, with no regard to implicit reducibility of composite numbers.

[@superguyx5468]

I can’t comprehend this higher dimensional comment

[@jasonjacoby]

I imagine trying to find a particle of gravity would be like trying to find a particle of time. I bet that when we solve this one, we will have some very interesting peripheral discoveries that render the stock market obsolete, and that's another issue. 😅

[@aeimcinternetional]

What about a 'particle of any change" (time=change)‽😇

[@jasonjacoby]

@@aeimcinternetional I hope not, because then we will have entropy weapons 😆

[@annoloki]

A "particle" is just a packet of behaviours interacting in a way that is self-perpetuating... like a tornado could be thought of as a particle of weather... it acts like a thing, it moves like a thing, but it is constantly pulling in new air and throwing out old air... the behaviour persists beyond the time any of its constituents are partaking in said behaviour. Yet, look closely and you'll see it is not an object, it has no boundary, no edge... the behaviour "drops off" as you get further out, it's not like a boat, where one side of the line, you're on the boat, and the other side, you're gonna get wet. Same when you look closely at any of our physics "particles". We think of them as "things" because our brains like doing that, but all things are simply labels in language of how interactions of other "things" would occur. All of science is interaction, yet all of our thinking is things in their non-interacting state, and so, we struggle.

[@ehta2413]

@@annoloki That is one of the more elegant comparisons I've seen floating around the internet. It's one the larger problems in both classical and quantum physics that they try to explain something that is an actual phenomenon as an object, so that we can go around modelling it. Time and gravity are more likely dimensions rather than pure phenomenon's so trying to explain them as a particles or waves is more or less doomed, and yes we can still measure them and even theoretically send signals via both mediums by making medium itself contract or expand, but it still doesn't mean that it would require waves or particles.

[@PADARM]

FINALLY someone said it!!

[@TheBrightmanFan]

For real, by now it should be obvious! but they had to invent ridiculous theories like string theory

[@MCsCreations]

Well... To be honest I'm not surprised... But perhaps there's other ways to make both theories work together, who knows.

[@beamshooter]

My idea is that curvature simply operates on quantum wave-functions in a continuous way. I.e. massive bodies fall towards each other because the curvature localizes all their constituent wave-functions towards the center of mass.

[@nickknowles8402]

I appreciate the more in depth analysis even tho I have no idea what you're talking about

[@mmicoski]

Measuring one graviton would be a massive event 😂

[@bozo5632]

It would just be a small thing.

[@Eh-ot4vz]

I see what you did there

[@istvansipos9940]

we would understand the gravity of the situation. And also the situation of gravity.

[@Elliot_97]

That’s an interesting link between quantum physics and general relativity! Where can I learn more about this wacky coincidence that a device capable of measuring a graviton collapses into a black hole?

[@ontoverse]

Susskind talks about this in some of his classes on cosmology (available online) but depending on how much high-level mathematical physics you know, or at least you're willing to gloss over if you don't really understand it, you might not have fun listening in. He even takes it one step further and says "ok, let it become a black hole. It's still a detector, ie all black holes are detectors, What can we do with that?" That's one line of thinking that leads to Susskind's "entangled black holes" discussions. He doesn't have any answers, but does motivate why a unified theory _ought_ to give answers to some carefully constructed questions about the structure of the universe.

[@marius165]

If gravitons indeed existed and were emitted by mass, wouldn't that mean that mass would have to be diminishing over time, equivalent to the energy emitted through gravitons?

[@pakarpintu4917]

you are genius

[@kamirostorino9416]

hawking radiation may be somehow connected perhaps

[@pdxmusl1510]

Nope. In the same way that quarks have there respective charges. they don't change.

[@marius165]

@@pdxmusl1510 but quarks are not generated by something else

[@pakarpintu4917]

@@marius165 maybe quarks construct by prions

[@amarured]

Makes itself known by being logical conclusions and by hinting at itself at every corner. Literally REFUSES to elaborate any further. Based Graviton.

[@amanie7450]

My favourite theory is that the existence of space time is due to a single quantum point reaching a mass so great that it explodes into space time (i.e a black hole reaching a max mass for its point), and gravity is the force pulling the mass back together, while the force of the initial explosion is the dark energy that is pushing everything apart. It would make sense for the expansion to slow down only for the minuscule period of time that the particles were close and massive enough to fight against the force of the initial ‘break’ in quantum physics, and then continue to speed up once the supper massive particles started to spread out enough that their gravitational effect on each other slowed Edit: could it be that gravity si the result of mass occupying time and space, rather than time as it would in a quantum particle

[@IllusiveMan343]

It’s an emergent property. Nobody would look for anti-photons in a shadow. We’ve been over thinking for 100 years - it happens.

[@sdm6054]

What strikes me as amazing is that scientists have been speaking of gravity as a fundamental force even though there is zero experimental evidence of quantized gravity.

[@IllusiveMan343]

@@sdm6054 as one I am legitimately disappointed that they’ve spent as much time attempting to falsify a theory for which there isn’t even indirect evidence of quantum gravity.

[@drrhobert]

3:40 Bohr's first name is misspelled: It should be NIELS not Neils.

[@Nebuch]

When I fall into the delusion that the universe is conspiring against us, I believe that a major reform is needed in our perspective on the matter.

[@diohnysius]

What if every particle in the universe are actually the same distance away from each other on a different spatial dimension? Like how two points on a 3D plane can be right next to each other on the Xand Y axis, but miles away from each other on the Z axis. What if time "slows down" when moving between many particles with very close X,Y, and Z axis because light/causality travels on a different axis?

[@jackmermigas9465]

And throw in that photons don't experience any time until they are absorbed by something!

[@sarahp13]

I think about this a lot in terms of entanglement - like each entangled particle actually causes a fold in the fabric of the universe we can’t see and the particles are actually touching in another dimension - like two magnets cinching fabric together