Your Daily Equation #15: The Planck Length - Why String Theory is Hard to Test

[@mikevaldez7684]

Fascinating conclusion tying in the difficulties of testing string theory due to the super large quantities that emerge out of the theory which the large hadron collider can not reproduce & therefore can not be observed......

[@elizabeth555johnson]

I appreciate how you leverage digital, social and old time media to put science in the daily dust. Never stop!

[@philochristos]

I had heard that the Planck units came from dimensional analysis, but this is the first time I've seen it demonstrated. Thank you.

[@TheTwick]

Thanks much, doc. When this world gets “back” to some semblance of order (‘normalcy”), we will all be a little smarter because of you.

[@frogz]

and i hope the good professor continues to enlighten us all after that happens

[@stefanysanchez2874]

Just wonderful, I been tryin to find out about "things that help you memorize" for a while now, and I think this has helped. Have you ever come across - Yiyevi Ponevi Approach - (should be on google have a look ) ? Ive heard some interesting things about it and my partner got amazing success with it.

[@chesingh16]

Agreed

[@2010sunshine]

I feel fortunate to be born in this era, when great scientists like Dr. Greene, riding on technology, can teach fundamentals to millions of novices like me.

[@ineskucharz1990]

No more comments on this wonderful series since 2021? I discovered it about a week ago and am doing my 2 daily equations every morning! as a layperson with very limited notions of maths, I truly enjoy the series. I wonder how many episodes there are? when I watched them all, I´ll start watching them all over again. Thank you so much, Brian Greene, for making us a little smarter!

[@kevinblackandwhite8273]

Seriously Dr. Green, I rarely comment on youtube content but I have to tell you that you are a legend!! The WSF is literally the most interesting academic content on the platform.. delivered with humour and proffesionalism. One couldn't expect any better 'education type' presentations. Untill you start teaching the world, at no charge, the nitty gritty mathematical side of all the concepts already discussed on your panels. Thank you. There is other great content put out by the Royal Institute, the cyber security guys like DefCon and BlackHat, the philosophy lectures by Harvard, Google Talks etc.. But the WSF takes the cake due to the diversity of subject matter actually discussed on the panels, and the quality, in-depth analysis of the subjects. So again, thank you sir! You are a legend!

[@SolidSiren]

I've liked Brian since the mid 90s so I understand your enthusiasm. However, if you think he is the best or only well presented excellent content regarding physics and maths on YT, you are missing out!! There are at least 15 extremely good channels and almost 50 very good channels for the beginner to intermediate learner of physics/cosmology/quantum theories. Many are perfect for those interested as a hobby, others offer more. If you'd like a list let me know.

[@SolidSiren]

You named a few but I think there are dozens as good or better! And there are modern as well as older taped lecture series on physics, QED, QCD, etc.

[@johnjobs3027]

I feel much better now , after my daily mental pushup with Dr Greene. Best of wishes for you and the family in the coming year from a big fan. 🎆🇨🇦

[@ozdergekko]

I love to watch the podium discussions of the WSF. But this is like having a privatissimum with one of the best physicists and best teachers available. Thank you so much!

[@jasongibbs6423]

One of the best explanations of natural units I have ever encountered! I have long struggled intuitively with the concept of natural units, and this video brought it into focus for me. The proverbial light bulb just clicked on; Thank you Dr. Greene!

[@fabiocaetanofigueiredo1353]

I am taking 101 classes with one of my Physics/Science idols... how cool is that?!? Professor Greene, I consider you and Professor Al-Khalili the absolute champions of transmitting complex scientific concepts with perfect didactics, in a way that any human on the street will understand. Thank you much for your work, Sir!

[@BitwiseMobile]

I'm getting flashbacks of differential equations! I actually loved that course - many people complained. What killed my career as an astrophysicist was linear algebra :P. What I loved about differential equations was the fact that algebra was all you really needed. I guess you need to know how to evaluate a definite integral, but that's super simple and could be taught to any algebra student - it's just evaluating the equation at the two points and taking the difference really.

[@luisfelipe7351]

thank you so much once againg professor, you are a true inspiration for to dive in the numbers and learn through mathmatics, columbia sure has an excelent teacher.

[@DanishGSM]

Thanks so much. I Hope you Will do this FOREVER AND EVERY DAY.

[@GameinTheSkin]

Dafuq man, you want to always be in covid realm. he would be delivering this on stage otherwise

[@frogz]

@@GameinTheSkin no, we want the amazing professor greene to remain this down to earth and accessable, both literally and metaphorically to the every day man and keep doing this because of how enjoyable the content he has been producing lately, as good as ANY big budget science program on television

[@gregparrott]

Thanks for describing how Planck length, mass and time were computed and the reason for doing so.

[@dominiqueschlogl8700]

Dear Prof. Greene, great series! I had expected things going more into that direction when you explain planck length (lp), sorry for the crude notation: E = hv = hc/£ Photoel. Effect E = Mc2 GTR E = pc GTR c = £×v hv = pc deBroglie hc/£ = pc h/p = £ p = h/£ dp = h/d£ dx×dp >= 0.5hbar Uncertainity principle dx/d£ >= 0.5/2TT = 1/4TT, £min for Emax: £min = 4TTx rs = 2GM/c2 GTR-Schwarzschild = 2GMc2/c4 GTR+deBroglie, Emax = 2Ghc/£/c4 = 2Gh/£/c3 Uncert. Pr. = 2Gh/4TT/x/c3 rs = x: x = (Gh/2TT/c3)^0.5 = (Ghbar/c3)^0.5 = lp Planck length more or less describes that energy with a shorter wavelength -> higher energy -> stronger gravitation ... will ultimatively create a black hole. Beyond its event horizon everything is unknown, until now. So there is a limit. Would you agree? Best regards

[@Inhuman0]

What a wonderful lesson. Thank you Mr Greene.

[@fredspencer4848]

I LOVED how Brian (I may call you by name?) got SO excited towards the end of this video - he was in "String Theory: country! Thank you Brian for your wondrous presentationS!

[@onderozenc4470]

Thank you for this inspiring lecture. By the same token, I wonder if we can get a reasonable quantity for Planck temperature corresponding to vacuum decays with the help of the Planck constant, Boltzmann constant and the speed of light ? I attempted to get one and I got something at the order of 10^31 Kelvin.

[@mak675]

Yes Planck temperature.......are we talking about......absolutely absolute temperature? I love it all ,this IS interesting vs. politics or celebrities. I'm not a smart man but like Einstein said I just stay on the questions longer *****

[@shakiralfateh7295]

Maybe I am getting too rusty with old age , however what I concluded from this session is the need to redifine our units of length, time , and mass, in such away as to bring them to a scale that for manipulation reasoning, whether connected to research progress in physics or purely to numerical handling of data, they present a much more convenient format. I also find that the choice made to use the product formula for the three universal constants ( C, h ,G) is not based on a "must to have " criteria, but on the logical requirements of their representative scales and their dimentional definitions. The end result of this exercise is basically to deal with numbers that are not only easier to digest, communicate, and represent but also to enable the highly sensitive calibrations of the instrumentation and systems critically required to conduct our ongoing investigative research. My comfort sinks to low levels when we include the infamous stand alone ZERO in our analysis, which seems to take the highlight at the ending part of this presentation. I come from the culture that stipulated the basic principles of Algebra (ALJABUR الجبر ) with a foundation that is an integral part of the meaning of the word itself, and that is the Equality that is imposed in the format of a two sided Equation. That basic priciple is visibly compromised when an operationally active Zero plays part in either or both sides of this demanding equality.

[@danielbachour9987]

Thanks Professor Brian!! Just amazing!! I now understand why supersymmetry and of course, string theory, have not been proven yet. I'm completely amazed with the work you have been doing professor! Always super pumped!! Thanks again!!

[@MGromov1]

Excellent. Thank you very much Prof. Greene.

[@juanvia8394]

Wow! I, as non initiated, appreciate this a lot!

[@Verschlungen]

PURE GOLD, your patient, Leave-No-one-Behind algebra steps @11:30-19:05. Exemplary! @10:48 you remark that one "can even converse with aliens about this." It would have been nice to mention that it was Planck himself who first said that, as he presented his "natural units" in "Ueber irreversible Strahlungsvorgänge," Annalen der Physik 4,1900, p. 121: "...for all time and all civilizations, even extraterrestrial or nonhuman." 123 years ago. A quibble: To Planck, what we call 'h' (his 'b') or h-bar was NOT (yet) "a constant of nature," like c and G, but something he had to invent.

[@gideonding01]

thank you for the note, Dr. Greene. very insightful.

[@rayxu1163]

Hi sir I really appreciate the series so far. I just wonder if deeper into the series we can get slightly more complicated calculations and mathematics. Most videos you can find on youtube are either too general or straight up lectures. Hope to see more from you sir!

[@numankaraaslan]

This is already burning my brain man :)

[@rayxu1163]

@@numankaraaslan well you should expect even more later :)

My biggest issue with the stuff on KZbin isn't the lectures per se, but that you really need a book and problems to solve in order to get much from those lectures. It's really hard to actually learn anything that sticks without something to do with it.

[@p0ma147]

This man ages faster than anyone I know... And provides the most value! He's like a blue star.

[@mak675]

Symmetry × symmetry = 0........dude, I lost you about 5 sec. after you began to draw......but I watched it all,and I know how the constants are derived. Thank you so much.....because I am curious about these topics and when I watch you I have a take away.......a bit of an idea I didn't know before. A gift from your talent.......

[@me3677]

Hahahahahahaha, just ran across this video. I am not a math student, I've listened to Brian and have understood quite a lot of what he was saying when he dumbs it down for me in other videos..in fact he got me into quantum physics. I am 54f and did not go to college, this shows me how far he has had to lower his intellect to speak to me...just want to say thank you soooo much as I do enjoy what is graspable for me..but this turned my brain to mush. 🤷‍♀️

[@farhantajwarahmed3340]

It's literally exploding my brains...XDXD! Never thought that such simple algebra would result in so fundamental and significant insights of the "reality". Indeed, THE MOST COMPLEX FORM IS IN SIMPLICITY! Thanks sir, hats off!

[@kdkittehmama9490]

Thank you for this video. Can you do an episode on symmetry, conservation, and Noether's theorem?

[@mskEduTech]

You are absolute Brilliant in explaining anything in Physics. I have been watching your videos for many years. It's always a pleasure to watch all your videos. Just wanted to ask one question that "whether special relativity doesn't apply at Planck length that is at 10(-34) meter"?

[@donnahaynes8766]

This was fun and much easier to follow than Schrodinger's equation. I learned dimensional analysis in university (mechanical engineering) so I followed this one pretty well. I did have to take notes (as I did copiously in university) just because you scrolled rather quickly on your Ipad. The Schrodinger's episode I had to watch several times and still have questions about some of the assumptions. I will get there but is was fun to have an episode that I actually understood. Thank you for all of these classes. You are so generous with your time and knowledge. Thank you a 10 to the 6th times! (don't have patience to see if I can put exponents in a youtube comment :)

[@JimEllison88]

Which program was you using to draw your equations? It looks amazing.

[@mijastiwari6663]

I don't understand why you equated the product of natural units to the desired dimension. Moreover, we didn't consider any number which is devoid of dimensions and can still be the part of the equation. Thank you Prof. for your description.

[@Amethyst_Friend]

Thanks Brian!

[@stevehideg3543]

This illustrates that all we can do is compare things. All of these fundamental numbers are defined by comparing things to other things.

[@isf9460]

Brilliant! Regarding question: If Planck length and Planck time are the smallest length and shortes time, does this imply that space and time are discrete? We can't "get" from one Planck position to other adjecent Planck position "little by little", we can only "jump" from one to another. Also, it can, at the minimum, take one Planck time to do so; we can't cover "little by little" space in "little by little" time. Since nobody is clear if space/time is discrete/continuous, what an I missing here?

[@nmarbletoe8210]

seems like either it is discrete, or measuring it is discrete.

[@rickmorrisrigar]

Thank You, Professor Greene, Now I can go lay down before my head EXPLODES 😁

[@petergreen5337]

Thank you for your clear explanation

[@furious4546]

Doctor Greene, I'm sorry LHC experiments have not yet verified theory that you have invested time and energy into. On the other hand, I learn so much from your videos. Thank you.

[@nmarbletoe8210]

didn't string theory predict the viscosity of the quark gluon plasma at LHC?

[@bitmap1638]

Thank you very much. I have learned what the alpha, beta, and gamma symbols are, and where the unit of a second came from. If I re-watched this several more times... that's about as far as I would get.

[@techteampxla2950]

Dear Dr.G first thank you for this video , amazingly clear ! What if we did the same calculations of time using a different star ⭐️ planet system and start breaking that formula down ? Would it be the same ?

[@WaveyaAddict]

That's up there with: GIVEN Quantum energy = Planck's constant * frequency AND Classical wavelength = velocity ÷ frequency AND DeBroglie's wave-particle wavelength = Planck's constant ÷ momentum AND momentum = mass * velocity AND velocity at the speed of light E=mc²!

[@the-goat]

Does the fact that the LHC has not yet seen any sign of Super Symmetry rule out any aspect of String Theory? If so, to what extent can we physically probe the areas that remain untested? How soon will it be that we reach the point beyond which there can be no more answers with our current technological capabilities? What alternatives are there to cosmic-scale particle colliders if we are to avoid the problem of creating black holes when the energies become sufficient to probe the Planck length?

[@Gringohuevon]

Best episode so far!

[@harshpratapsingh310]

Way of explanation is quite amazing:)

[@paulsimmons9512]

Compared to eternity the largest we can calculate is smaller than the smallest we think can exist. So, the Planck scale is huge beyond all understanding compared to how small our universe is in the mist of the eternity of unending space. You don't even need algebra to come to that supposition. Throw the Planck scale out and give me the Nobel Prize.

[@tedbates1236]

Thank you. I kind of got the idea. Now I am going to listen to it a second time.

[@Goldslate73]

Thank you so very much professor... 🙃🙂 (I'm smiling like an electron) Because this video... Is Whirringly amazing.

[@Valdagast]

Is there also a Planck entropy?

[@RenaldoRamai]

This was excellent. Thank you so much.

[@mydayswithoutyou]

It would be great to hear your thoughts about the LHC. How bad is it that we haven't seen anything so far (except the Higgs boson)? What can we realistically hope to learn from future experiments? Please, let's find an equation that gives you a good excuse to discuss about these issues! Thanks, thanks, thanks!

[@ranapratap9230]

Planck mass , time and length are so small but Planck temperature is so big!

[@tommyp3611]

Bloody great video.

[@marciliosantos898]

Great work. Thanks a lot. Science is great!

[@markheller197]

I’m glowing with understanding. Thank You More on dimension

[@martijn130370]

exceptional again. Never knew the simple mechanism of dimension analysis was behind this

[@Anthos147]

Hello! How do you describe this property of a system of apparent magnitude.. For the linear transformation of a system, we can think of a conservation of energy(to remain in a system of electrochemical resonance).Thank you!

[@georgegrubbs2966]

I liked this episode. Nicely done.

[@TheMateusrex]

Another fantastic video.

[@jonathanarellano2018]

Thank you this video came at a time when ive been asking myself about this information.

[@localtitans4166]

Thank u sir.. thanks a lot

[@stevemartin4757]

Consider a particle with a reduced compton wavelength which is comparable to it's Schwarzschild radius.. from this we define the Planck length as the scale at which quantum mechanics and general relativity intersect...

[@onderozenc4470]

I think in CERN experiment, we had 10 to 3 M(P) Higgs bosons decaying to super symmetric quark anti-quark pairs. As to the 10^19 M(p) Higgs bosons decaying to the iso-spin symmetric string pairs, we can only predict them as Mr.Hawkings` prediction for W and Z Higgs bosons with vacuum decay in super massive black holes. What about the Planch temperature for this process ?

[@santoshjha108]

Thanks professor Greene.

[@adki231]

Very nice explained!But why do we use the term "Planck" to define them? And a second one: is there anything special to the possible combinations of ratios between h,G and C?

[@kamaldey3893]

Thank you very much Sir.

[@saboabbas123]

I understood most of it but not all. I speak Spanish and English but not math. I'll keep listening. I enjoy the challenge.

[@mydroid2791]

So why is Plank mass so large but the Plank length and time units seem so small. My understanding from reading some of your books Dr. Greene was that these Plank units were minimum scales and below that things became "stringy". Is this not correct, or just not correct for mass units, or am I missing something?

[@AmandeepSingh-bj9dm]

Please make a video on pioletwave theory. Thanks for this awesome video.

[@SaraKANZI]

it was really great thank you

[@bikramjitpanigrahiartist3812]

could you please make a video on the general relativity .

[@prabirkumardash653]

Thank you sir. One of the mysteries of the multiverse is solved

[@robertsparkman8516]

Thanks! Maxwell perhaps? I gather there's an interesting story behind the equations. Would Einstein's Field equations be possible, maybe over a week. Love all your doing, again, thanks!

[@enlongchiou]

String oscillate between Planck, proton scale produce strong force, oscillate between proton, Atoms scale produce electromagnetic force, oscillate between strong force, electromagnetic force create weak force.

[@bartvenken7138]

What is the reasoning behind multiplicating c, h and G? I mean, I understand what's being calculated, but I don't get why that particular step is made ...

[@CowboyNaitsi-CN]

Professor, I want to know whether it is possible or not to perform the experiment for proving string theory.

[@sarmadnajim4839]

Thanks , very informative

[@improvemyenglish]

Thank you for your videos. Equations I would like to see are sound waves in water and the motion of water molecules. What properties would a theoretical aether have so that light waves travel thru it like sound waves in water?

[@mskEduTech]

Just wanted to ask one question that "whether special relativity doesn't apply at Planck length that is at 10(-34) meter"?

[@lookmath4582]

Prof Brian, with all due respect. What on earth are the predictions of string theory? Should not it first resolve some remaining problems like the cosmological constant problem or black hole issues?

[@nmarbletoe8210]

what do you think of the fuzzball reserach?

[@HansPetterBekeng]

The Fabric of the Cosmos: Space, Time, and the Texture of Reality is in my opinion STILL the best book ever written on the topic. As such, you are perhaps the best explainer in the field, something these videos also are testaments to. I was kinda excited when that other guy teamed up with Leonard Mlodinov for his last book, having read Feyman's Rainbow and knowing Mlodinov is a good storyteller, but boy I'm sorry to say but that book sucked even more than his previous ones. In a nutshell it wasn't that grand at all, which the Fabric of the Cosmos certainly is. As a layman enthusiast I've always been a huge fan of your work in the public as an explainer of things and a promoter of string theory and science, to the point where now as I'm fifty years old in my mind you've "always" been in the public space since back in the 80's when we watched "Beyond 2000" on the Discovery Channel, even if I know it was in the 90's you came on the scene. Anyway, thank you so much for all your work in the public space explaining all these physics you do to all us commoners. And for anyone thinking to learn the secrets of the Universe and reality, the Fabric of the Cosmos is - by far - the best book for you out there.

[@petertomshany]

Wonderful video. This series is really perfect for my position on the knowledge-ignorance axis. I do have a weird question. If our current measurement of time uses radioactive decay, governed by the weak force, how is time not an emergent effect of mass, such as gravity is an emergent effect of the geometry of space?

[@luithedude3300]

Isn't G measured as newton time meter squared divided by kg²? And isn't Planck's constant measured as Joule-seconds? I'm confused

[@Dr10Jeeps]

Fascinating!

[@naimulhaq9626]

What is the meaning of 'zero is the super symmetric number'? How do we read reality from this?

[@petkucius]

Magnificent stuff.

[@mirijason]

I suggest renaming c=299792458m/s the Planck speed as 1) it is the planck speed 2) it avoids many confusion I've been asked as to why is the speed of light special? Well it is not, the Planck speed is ;)

[@BenKrisfield]

I enjoyed that. Thanks

[@anilsharma-ev2my]

What is specific density at PLANK scale ??

[@shouvikmondal1977]

Hey what happen if we one day find out the GRAND UNIFIED THEORY ? Will it close the physics chapter or will it open some new idea's? Shouvik Mondal from INDIA.

[@suhass2166]

Well sir I've got the answer to my question about string theory..hope it'll also be proved very soon...thnk you for your answer🙏😊

[@milarovas4363]

great video

[@PauloRenatoRodriguesprr]

Marvelous!

[@_John_Sean_Walker]

Thank you sir.

[@PauloRenatoRodriguesprr]

Really wondrous!!!!!!

[@hussammustafa5267]

I was telling my girlfriend before this video came out earlier today that, in order to find some number, all you do it bang together the constants within the problem until you get out the units you want, I used the example of Hubble's constant to find the age and size of the universe and the constants in Maxwell's equations to find the speed of light. I really love dimensional analysis, we did this exact example in my modern physics class last semester. Thank you professor :)

[@curaticac5391]

Bet the gf cared only about the banging idea.

[@AmandeepSingh-bj9dm]

Please make a video on pioletwave theory.

[@kaushikdas8034]

Take up formula for black hole entropy..and thnx for this daily equation sir.. Thnk u