Does nature have a minimal length?

Molecules are made of atoms. Atomic nuclei are made of neutrons and protons. And the neutrons and protons are made of quarks and gluons. Many physicists think that this is not the end of the story, but that quarks and gluons are made of even smaller things, for example the tiny vibrating strings that string theory is all about. But then what? Are strings made of smaller things again? Or is there a smallest scale beyond which nature just does not have any further structure? Does nature have a minimal length?
This is what I talk about in this video. I explain why many physicists think that nature indeed has a minimal length, which is the so-called Planck length, named after Max Planck.
In this paper you can find more arguments for why the Planck length plays a special role in nature:
Six easy roads to the Planck scale
Ronald J. Adler
arxiv.org/abs/1001.1205
Max Planck's paper from 1899 is here:
bibliothek.bbaw.de/bibliothek-...
You find a translation of the paragraph that I am referring to here:
backreaction.blogspot.com/2007...
You can help finance my videos by donating here:
www.paypal.com/cgi-bin/webscr...

[@ablebaker8664]

I'm almost certain my first apartment was smaller.

[@ZEZERBING]

Mine was so small, I had to go out side to change my mind!!🥁

[@Tore_Lund]

@@AbuMajeed3957 Nice, at least the first part, but if it changes the permittivity, the fine structure constant will change too, so you might not even need Einstein to create such boundary at the event horizon, even if 100% time dilation is enough to create such a boundary. Definitely you make an interesting proposition!

[@EmdrGreg]

We must have had the same landlord.

[@Tore_Lund]

@@AbuMajeed3957 Physics is beautiful, and you need to take your theory further, this is very interesting! The fine structure constant, is the relation between the 4 fundamental constants expressed as a single unitless number. However, it explains the relation of the magnitudes between Gravity, permittivity, planck's constant and c. So when you theorize that permittivity is variable, you are also indirectly suggesting that the universe breaks down at the event horizon, not only that relativistic effects influence permittivity. So you might find some pieces of math from Quantum electrodynamics useful?

[@Tore_Lund]

@@perpetualbystander4516 I wasn't really the one in this thread contemplating on life in a Planck size apartment, but the upside, is that you never need to clean such an apartment, as everything inside it will cease to exist.

[@harrybarrow6222]

Dr Hossenfelder, I graduated with a degree in Physics and Maths from Cambridge almost 60 years ago. I love your videos. They help me refresh and update my knowledge, and I love your clear and concise lecturing style. Please make many more videos.

[@SabineHossenfelder]

Happy to hear you find them useful!

[@cokemachine5510]

so you've been mentally stunted. sorry to hear that . lets see how bad the damage is . " what do you think about plasma and its influence in the universe ?"

[@charlesbrightman4237]

@@cokemachine5510 " what do you think about plasma and its influence in the universe ?" a. What is 'plasma' but very fast moving and interacting particles? b. How small can 'particles' be? c. How did particles come into existence or did they always exist and possibly will always exist? d. Did the forces of nature come into existence or did they always exist and possibly will always exist?

[@cokemachine5510]

@@charlesbrightman4237 Charles that would be the weeds . go with what you KNOW of the physical world , and those questions will be answered . What could be influencing particles to become plasma ? an electric field ? magnetic fields? what where some of the theories before consensus science ? do you Charles dare mention them ? be careful, here's where the derangement syndrome becomes apparent.

[@charlesbrightman4237]

@@cokemachine5510 Find some entity to do my gravity test and possibly have the literal Theory Of Everything: (Reusable code from my files): Here is the test for the 'gravity' portion of my TOE idea. I do not have the necessary resources to do the test but maybe you or someone else reading this does, will do the test, then tell the world what is found out either way. a. Imagine a 12 hour clock. b. Put a magnetic field across from the 3 to 9 o'clock positions. c. Put an electric field across from the 6 to 12 o'clock positions. (The magnetic field and electric field would be 90 degrees to each other and should be polarized so as to complement each other.) d. Shoot a high powered laser through the center of the clock at 90 degrees to the em fields. e. Do this with the em fields on and off. (The em fields could be varied in size, strength, density and depth. The intent would be to energy frequency match the laser and em fields for optimal results.) f. Look for any gravitational / anti-gravitational effects. (Including the utilization of ferro cells so as to be able to actually see the energy field movements.) (And note: if done right, it's possible a mini gravitational black hole might form. Be ready for it. In addition, it's possible a neutrino might be formed before the black hole stage, the neutrino being a substance with a very high gravitational modality with very low 'em' modalities.) (An alternative to the above would be to shoot 3 high powered lasers, or a single high powered laser split into 3 beams, each adjustable to achieve the above set up, all focused upon a single point in space.) 'If' effects are noted, 'then' further research could be done. 'If' effects are not noted, 'then' my latest TOE idea is wrong. But still, we would know what 'gravity' was not, which is still something in the scientific world. Science still wins either way and moves forward. Revised TOE: 3/25/2017a. My Current TOE: THE SETUP: 1. Modern science currently recognizes four forces of nature: The strong nuclear force, the weak nuclear force, gravity, and electromagnetism. 2. In school we are taught that with magnetism, opposite polarities attract and like polarities repel. But inside the arc of a large horseshoe magnet it's the other way around, like polarities attract and opposite polarities repel. (I have proved this to myself with magnets and anybody with a large horseshoe magnet and two smaller bar magnets can easily prove this to yourself too. It occurs at the outer end of the inner arc of the horseshoe magnet.). 3. Charged particles have an associated magnetic field with them. 4. Protons and electrons are charged particles and have their associated magnetic fields with them. 5. Photons also have both an electric and a magnetic component to them. FOUR FORCES OF NATURE DOWN INTO TWO: 6. When an electron is in close proximity to the nucleus, it would basically generate a 360 degree spherical magnetic field. 7. Like charged protons would stick together inside of this magnetic field, while simultaneously repelling opposite charged electrons inside this magnetic field, while simultaneously attracting the opposite charged electrons across the inner portion of the electron's moving magnetic field. 8. There are probably no such thing as "gluons" in actual reality. 9. The strong nuclear force and the weak nuclear force are probably derivatives of the electro-magnetic field interactions between electrons and protons. 10. The nucleus is probably an electro-magnetic field boundary. 11. Quarks also supposedly have a charge to them and then would also most likely have electro-magnetic fields associated with them, possibly a different arrangement for each of the six different type of quarks. 12. The interactions between the quarks EM forces are how and why protons and neutrons formulate as well as how and why protons and neutrons stay inside of the nucleus and do not just pass through as neutrinos do. THE GEM FORCE INTERACTIONS AND QUANTA: 13. Personally, I currently believe that the directional force in photons is "gravity". It's the force that makes the sine wave of EM energy go from a wide (maximum extension) to a point (minimum extension) of a moving photon and acts 90 degrees to the EM forces which act 90 degrees to each other. When the EM gets to maximum extension, "gravity" flips and EM goes to minimum, then "gravity" flips and goes back to maximum, etc, etc. A stationary photon would pulse from it's maximum extension to a point possibly even too small to detect, then back to maximum, etc, etc. 14. I also believe that a pulsating, swirling singularity (which is basically a pulsating, swirling 'gem' photon) is the energy unit in this universe. 15. When these pulsating, swirling energy units interact with other energy units, they tangle together and can interlock at times. Various shapes (strings, spheres, whatever) might be formed, which then create sub-atomic material, atoms, molecules, and everything in existence in this universe. 16. When the energy units unite and interlock together they would tend to stabilize and vibrate. 17. I believe there is probably a Photonic Theory Of The Atomic Structure. 18. Everything is basically "light" (photons) in a universe entirely filled with "light" (photons). THE MAGNETIC FORCE SPECIFICALLY: 19. When the electron with it's associated magnetic field goes around the proton with it's associated magnetic field, internal and external energy oscillations are set up. 20. When more than one atom is involved, and these energy frequencies align, they add together, specifically the magnetic field frequency. 21. I currently believe that this is where a line of flux originates from, aligned magnetic field frequencies. NOTES: 22. The Earth can be looked at as being a massive singular interacting photon with it's magnetic field, electrical surface field, and gravity, all three photonic forces all being 90 degrees from each other. 23. The flat spiral galaxy can be looked at as being a massive singular interacting photon with it's magnetic fields on each side of the plane of matter, the electrical field along the plane of matter, and gravity being directed towards the galactic center's black hole where the gravitational forces would meet, all three photonic forces all being 90 degrees from each other. 24. As below in the singularity, as above in the galaxy and probably universe as well. 25. I believe there are only two forces of nature, Gravity and EM, (GEM). Due to the stability of the GEM with the energy unit, this is also why the forces of nature haven't evolved by now. Of which with the current theory of understanding, how come the forces of nature haven't evolved by now since the original conditions acting upon the singularity aren't acting upon them like they originally were, billions of years have supposedly elapsed, in a universe that continues to expand and cool, with energy that could not be created nor destroyed would be getting less and less dense? My theory would seem to make more sense if in fact it is really true. I really wonder if it is in fact really true. 26. And the universe would be expanding due to these pulsating and interacting energy units and would also allow galaxies to collide, of which, how could galaxies ever collide if they are all speeding away from each other like is currently taught? DISCLAIMER: 27. As I as well as all of humanity truly do not know what we do not know, the above certainly could be wrong. It would have to be proved or disproved to know for more certainty.

[@4mb127]

"It may or may not come with a discretization." Probably the most important point for me here.

[@jppatterson7142]

@Al Garnier What does a "continuous variable" mean? Like the discrete-input of a funtion could be any value in a sequence of 1, 2, 3, 4....n ?

[@myothersoul1953]

@Al Garnier Are you saying binary numbers can approximate real numbers. And numbers can be used to create models of things?

[@clmasse]

@@jppatterson7142 "Continuous variable" means nothing, and that have been a big problem in mathematics. Now we know that continuity applies to functions only. The set of real numbers is dense and complete, but it is not sure this strong properties are needed. Saying after Galileo that the book of the Universe is written in the mathematical language with physical quantities having a numerical values bypasses many fundamental issues. This issues resurface at the Planck scale.

[@myothersoul1953]

@@clmasse Physical qualities and quantities are assigned numbers, that is what measurement does. Those numbers can be fed into mathematical models of the physical things. The measurements are not the same as the things they measure and the models are not the same as what they model. Do not mistake the map for the territory.

[@obsidianjane2267]

@@clmasse Unless the universe is fractal. Just as real numbers are continuous and complete, so may the scale as far down (or up) as you care (can to the limits of your technology) to look.

[@edzejandehaan9265]

Thanks, as a layman I had inndeed always pictured the Planck length as a kind of pixel. You made me understand that this is not the right way to think about this. I greatly admire your capacity for explaining complicated matters in a way that it makes sense even to people who haven't studied physics.

[@iramkumar78]

true that

[@diegog1853]

No joke, I am starting studying minimal lenght and quantum gravity for my master thesis. I had your video in one monitor and in the other a review of the topic called: "Minimal Length Scale Scenarios for Quantum Gravity" I never realized the video and the review were made by the same person until the video ended. That is crazy, I definetely have a lot of respect for you and your work.

[@schmetterling4477]

In other words... you are working the night shift somewhere. :-)

[@MattiasGyllenvarg]

Thanks, the pixelation vs blur analogy was very informative.

[@ThomasJr]

*What I love about Sabine is how accessible she makes topics for the users of this channel. Wikipedia and other channels make it so complicated and fuzzy, but Sabine is here to prove that these things can be explained as to be within the reach of simple mortals. Other scientists don't care about being understood by laypeople, actually, many strive to make things harder and more out of reach.*

[@nosarcasm1]

Good morning! Like your videos much, cause of the sharp scepticism and good physical based arguments for your opinions!

[@synon9m]

*skepticism

[@TheDavidfallon]

"I name this distance Delta X." Then smashes an infinitely small bottle of champagne against it.

[@franb6789]

I like Sabine because she thinks out of the box. She also jumps right into the topic without a lot of nonsense at the beginning.

[@rorycoker6601]

Sabine is about the only person other than BBC announcers that I have heard pronounce "kilometer" correctly. It rhymes with "centimeter," not with "speedometer." As for the talk, excellent, accurate and concise as usual.

[@stefanguels]

I'm pleased to be finally confronted with some formulas and their explanation. Something most pop science channels avoid like the devil fears holy water... So we're NOT a joke to Sabine.

[@lxathu]

(In case you're interested, here's another brave-heart: kzbin.infovideos )

[@mal2ksc]

Stephen Hawking wrote that when writing _A Brief History of Time,_ he was advised by his editor that every equation cut his audience in half. He included one (E=mc²) anyhow.

[@user-sl6gn1ss8p]

@@mal2ksc a true scientist would write 33 equations and prove their editor wrong if any sale was made u.u Also, include a chapter on exponentials dedicated to said editor.

[@AlanCanon2222]

@@mal2ksc Yes, he didn't do too badly for himself regarding book sales, did he? I worked at a large bookstore at the time and we sold those books at the rate of cubic meters per month.

[@althetutor]

Your comment reminds me of a video I watched a few years ago that discussed, among other things, the belief that the sciences have gotten harder. If memory serves, the presenter stated that the sciences didn't become harder, but the students going into science were less prepared (on average) than previous generations. He then used himself as an example, saying that he quit majoring in science because of his math troubles, but gets to continue celebrating his love of science by making videos. There's a good chance that this might be the backstory for a lot of pop science channels. Edit: I found the video in question, and my memory seems to have been slightly off. kzbin.info/www/bejne/oX-8e2p8Z794jpI

[@AlanCanon2222]

This is a perfect level of explanation for someone like me who studied physics decades ago. I loved the subject but was not good at Integral calculus. Nevertheless, I have continued to study over the years so that at least I don't forget what I've learned. The explanation of the Planck Length given by Professor Hossenfelder is so simple: probing smaller distances requires higher energy densities. I get that, since I remember the relationship of energy to wavelength through Planck's Constant, as well as the uncertainty principle. And the second part, that there is an upper limit on energy density, beyond which you have a black hole whose interior cannot be probed, and from which no information can be returned, also makes sense. So Dr Hossenfelder has taken a very mysterious thing to me, the minimal nature of the Planck Length, and broken it into two pieces or elements which I do have at least some intuitive understanding of, and she's done it in mere minutes. Brilliant. Thank you, Dr Hossenfelder. p.s. I was glad for her discussion of discretization, because I had thought of that too, but knew that must be the wrong view, because of something I read in the Feynman Lectures.

[@AlienScientist]

4:12 - Confirmed

[@mikicerise6250]

Fantastic. I've been waiting for a bit of explanation of Planck length for awhile now. I'm also used to thinking of it as 'discretized'.

[@andyiswonderful]

Since I started following you just a few months ago, it looks like your subscribers have more than doubled. Now at 55.5K. Bravo!

[@Cavistus729]

Recently, whenever I've read about exciting new science, I come to visit your channel to remind myself that exciting science requires equally exciting evidence to back it up. Thank you for reminding me to not get caught up in my biases.

[@CaptainAhorn]

Cavistus Not if it’s aliens!

[@billsugden3734]

@@CaptainAhorn Come oonnnn! It's never Aliens, every bad SF movie you've seen tells you it's never Aliens, until it is!

[@haraldlapins8652]

Dr. Hossenfelder... Thank you for your videos. They are a perfect example of how to teach. Your descriptions of things are clear and informative. Perfect for laymen (such as myself) . I just hope that next 16 orders of magnitude doesn't reveal me to be a computer simulation. That would be major bummer. :)

[@davidacus956]

This video dispelled a few misconceptions I had about Planck length, so thanks for that!

[@stevoofd]

I love that you put references in the description of the video, that way viewers who are intrigued are guided right to the source to delve deeper in their curious quest.

[@Wrongald]

I thought this was interesting... and then I noticed that I had watched it before... and "Liked" it... In one ear and out the other.

[@luceroalvarado9244]

same

[@linchen008]

Join the club ...

[@ts4gv]

2:53 you sing a melody here. "as you almost certainly know" solfege: Sol-Sol-Sol-Sol-Sol-La-Ti-Do brilliant.

[@khatack]

xD

[@misternobody6798]

Very good ear you got.

[@luceroalvarado9244]

flexing your perfect pitch?

[@ts4gv]

@@luceroalvarado9244 Nah i don’t have that. it’s just really interesting haha

[@xanthirudha]

Before watching i just screamed Planck's constant, please keep doing this series

[@Roberto-REME]

Excellent video Prof. Sabine. Very well narrated and expertly explained. Well done.

[@mountainhobo]

"it may or may not come with a discretization" -- I would love to hear an episode on the potential discretization of spacetime.

[@BlueFrenzy]

If space is discrete, then forces doesn't have infinite range. When the force is weak enough to not be able to move a particle one unit, then, it stops right there. It could really repaint the whole universe.

[@garyhamilton2104]

@@BlueFrenzy Is there nobody making the assumption to do some hypotheticals? Like, why not assume the p is a real constraint and investigate now. Why do we have to prove the p is legit before we do the math around it.

[@timh.7283]

I have just subscribed and binge-watched a dozen Sabine videos. As a result, brain-seepage is oozing from both ears and I am collecting it in paper cups. Within a few hours I anticipate squatting naked in my garden having regressed to a hunter-gatherer state. Damn physicists!!!

[@hanks.9833]

Excellent video! 👍👏 Many of my questions about the Planck length answered, thank you. Perhaps the correct final theory will also chart a clever way to experimental verification.

[@DavidSmith-hw2jx]

Super! Very accessible explanation of so many things related to Planck length and I love the Black Hole limit derivation. Thank you!

[@trucid2]

Thanks for adding that bit at the end about having to extrapolate 15 orders of magnitude. These topics are often discussed in a matter of fact way, as if all of this is settled science. It obviously isn't or they wouldn't still be smashing atoms together in particle accelerators.

[@Ithirahad]

@@johnlawrence2757 If an entity _does_ anything that has effects on larger scales, then by virtue of that doing, the entity must be observable, right? An "orbital teapot" like entity at tinier scales that never interacts isn't very useful to consider, is it? It'd be unfalsifiable.

[@bobaldo2339]

@@johnlawrence2757 Kind of. I'd say that, too, is "a little hand-wavy".

[@normalvector4564]

I'm really inspired by the way you discuss complicated things. I can feel the humble scientific person in you. I wish you the best for your channel.

[@jero528]

Thanks for all your hard work and efforts to clarify, there are none others like yours !!!!

[@robertschlesinger1342]

Excellent video on why there is a minimum length, the Planck Length, and the basics of the theory behind the length.

[@daveseddon5227]

I may not know what you are talking about but you make it so very interesting. 😕🙃 Love your videos, your presentation technique and your sense of humour!

[@RWin-fp5jn]

Videos like these are so important to have! They go directly to the heart of physics, which is all about the quest for the tangible physical fundaments upon which all other theories should rest. And Sabine clearly shows just how little we still know about the smallest scales or the physical reality behind them. In the past century, we tried to circumvent our lack of knowledge of the fundamental level by developing mathematical approximations, like Quantum Physics (QP) and Einstein’s GR. These works fine, but increasingly it became clear they cannot explain the underlying reality of physics. The last decades we tried adding complex math stuff to QP and GR, but this approach proved ineffective. Therefore, logic suggests something must be wrong with our core assumptions and believes, most of which originated in the 1920-1930’s. Yes, Einstein actually made a few errors… The first thing we must recognise is that energy is fundamentally related (or ‘inverse equivalent’) to SPACE and not to Mass. As such; Einstein’s discovery of the mathematical correct formula of E=MC2 may be his greatest achievement, but his interpretation of this being an ‘equivalence’ relation is his greatest blunder, causing confusion to this very day! Regarding the relation between energy and space: Sabine already makes a very powerful point explaining we need ever more energy when exploring ever smaller spatial scales. We see the same inverse relation also on the scale of our Big Bang universe singularity; It started as a highly energetic spatial singularity, yet upon spatial expansion of our universe, the energy of the central singularity diminished accordingly. This process is an equilibrium if we recognise that energy inside a spatial singularity has the role of grid, similar (yet orthogonal) to the role of space in our ST continuum. Another instance of this orthogonal relation between space and energy is Heisenberg’s uncertainty principle: dx*dp >4pi h. The 4pi factor relates to how singularities typically bend ST fieldlines and next ‘loop’ or ‘wrap’ them into double spiral arms with equal distances between them, expressed in energy integers (or ‘quanta’) of windings. As such, the 4 pi polar notation is the most fundamental geometric physical ‘constant’ in our universe. The actual Planck length, Planck Energy, G nor C are neither true constants nor are they very relevant in comparison. A consequence of the inverse relation between energy and space is an equally inverse relation between Mass and Time. This becomes clear when an object approaches the event horizon of a singularity: the time clock starts to pass slower, whereas the inverse ‘mass clock’ starts to ‘pass’ faster. But what about E=MC2 ? It is simply the movement equation inside a singularity. Looking at our ST movement formula: Space (distance) = Clock (s) * Speed (m/s), we can replace space with energy and time with mass. This leads to E=M*E/M or E=M*[Nm/kg=m2/s2=C2] or E=MC2. The symmetries are endless: Spatial locality e.g. has its symmetric counterpart in ‘energetic’ locality which we call ‘quantum entanglement’. Einstein simply never realised we live in a ‘dual’ continuum setup. If he only had, we could have saved us a century of stagnation and failure….

[@hellocat5689]

Just finished your book. Loved it and love your videos!

[@turingrecognizable]

One thing I appreciate about Sabine's videos is that she always includes the "but" when explaining enigmatic physical concepts to laymen like myself; e.g., The Planck length is the shortest length that can be measured, but... She is quick to acknowledge the limitations of our collective human understanding, providing us with even greater insight to the true state of human knowledge than those who make sensational claims without context. For me, it is akin to dealing with a straight shooter as opposed to a car salesman and displays a level of humility that I find to be admirable.

[@pennyrobinson9772]

"...but that quarks and gluons are made of even smaller things." Great fleas have little fleas Upon their backs to bite 'em And little fleas have lesser fleas And so, ad infinitum.

[@bobaldo2339]

It is all turtles all the way down. And there is a Buddha sitting on the back every one.

[@soaringvulture]

Or, alternatively, Great fleas have little fleas So small you cannot see 'em And little fleas have lesser fleas And so on, ad nauseam.

[@timelschner8451]

As always, precise and fun to watch. Thanks alot.

[@user-pb1py3gb4w]

As a layperson, I love watching this channel. The videos are fun, straight to the point, without unnecessary "noise". 10/10

[@sunnycareboo8924]

Hi Sabine, if you 1. assume zero energy hypothesis 2. calculate the amount of grav energy change in the observable universe due to FLRW metric in present day 3. Use that with heisenberg uncertainty relation 4. you get a number for dt that is approximately planck time. Repeat this for change of momentum / per radius (dp/dr) at boundary of observable universe, and you get a number on the order of the planck length. Really really interesting stuff!

[@donmcarthur]

"Needs a Haircut." LOL, thanks for the laugh with that.

[@intrograted792]

Your hair looks good how it is!

[@christianweiss6369]

It's a contribution to string theory

[@MauriceApophis]

Lol! @Intrograted: Here's some serious advice: NEVER argue with a woman who says she needs a haircut... ;)

[@intrograted792]

@@MauriceApophis ha ha. But I too am a woman who needs a hair cut... (no kidding, and mine does *not* look good how it is!) By your own logic, you shouldn't argue with me. 😆

[@MauriceApophis]

@@intrograted792 ... :D I certainly will not argue with you! ;)

[@805atnorafertsera6]

A man walks in to tiny bar. Welcome to H-bar Mr Plank, nice to have you here but just remember: we don't split anything here Sir

[@brucewilliams6292]

Thank you for the excellent video. I appreciate your not "dumbing down" the science. Even if I don't follow everything, I like to try and follow along.

[@sigurjonmyrdal3873]

Your lectures are extremely clear and interesting. I like your style.

[@erenkad7154]

Have a nice Sunday Sabine!

[@SabineHossenfelder]

Thanks, you too!

[@zathrasyes1287]

Well, the Planck-length might be the smallest, in principle, observable distance. But, does that mean, that this is the "smallest length". Could it be, that nature is, in essence, still continuous?

[@DrJ3RK8]

I was hoping you would do a video on this. Thank you!

[@jeffmorris9893]

Wow. A Planck:Alien connection. And one that's pretty easy to understand - a universal ruler. That's cool af!

[@JiveDadson]

Every time she says "minimal" my brain goes, "Shouldn't that be 'minimum'?"

[@michaelcarpenter3846]

"If you stuff to much energy into a small volume, you will create a Sabine Hossenfelder."

[@tsaszymborska7389]

I was thinking almost the same thing. Maybe first aliens happen and if you put even more energy in you get the black hole.

[@805atnorafertsera6]

Sh-bar....

[@mikel4879]

Michael Carpenter / And after you do that do you find a black hole at that size ?

[@tomjohn8733]

Interesting, always enjoy furthering my understanding of things, thank you Sabine!

[@kazimir8086]

That was... mind-blowing. Love the way of presentation.

[@AdamAlbilya1]

Is time comprised of any smallest "frames" units? E.g. Planck time? If so, how is it compatible with relativity? I.e. consider e.g. the twins "paradox" in which twin B returned younger than twin A, meaning after each Planck time unit - or any other natural unit contender - a smaller time unit passes for the other twin. Same goes for an atomic clocks, when clock A ticks 1 Planck unit, what did clock B ticked relative to it? Since it converges to zero, is it falty to conclude that spacetime is continuous?

[@HavocLoods]

IIRC, planck time is the time it takes for a photon to travel 1 planck length. Planck length in this case is about .75m. see "Ed, Edd & Eddy" for reference.

[@thephuntastics2920]

The only time is now. The univers consits of an infinite amount of “now“s . But the now you see, is more an more a collection of different now moments. Example, when you look at the sun, what you see is now. But the now is a collection of all the now moments from now to 8 hours ago . So what exactly is now. When you look at distant stars, you may look at stars that may not even exist anymore. In wich case you may look at a now thats a collection of now and all the nows since billions of years. Time is a concept applied by the mind. That becomes obvious on high doses of psychedelics. Once you have spent entire lifetimes or in extreme cases, an eternity, in other realities or infinity , once you have seen warping to and out of realities and the fractal abstract structure of space that contains all the nows in the same space, like a hologram, the concept of time can be understood. It is what our mind is for.

[@AdamAlbilya1]

8 minutes* ago (i.e. ~500 seconds). As for my question, I think you didn't understand it. It also applies for space, could there be some smallest discrete units of space? If so, when space of one contracts relative to another, then any unit of those units is now measured to be smaller relative to the outside observer. Now I'm asking, considering that no matter what "smallest units" one might offer, the traveler's units (e.g. those composing it), will be measured to be lower, thus converging towards zero. With that in mind we conclude that there is no discrete unit?

[@tomdumb6937]

The word/concept you are looking for is "chronon"

[@Laroac]

@@AdamAlbilya1 You are misunderstanding something. Twin A and Twin B experience are both equally valid, there isn't somethi g that it HAS to be relativ to, it is just how we perceive thing. Each thing is absolute within its own refrence frame.

[@bdf2718]

The minimal length is the short Planck. Hence the saying "As thick as two short Plancks."

[@GRosa]

🤣

[@pigman6954]

exactly the type of video i was looking for, thanks!

[@alchemist6098]

Love this podcast. I’ve shared it with some of my colleagues at work.....nourishing sweet food for the mind that loves physical science.

[@82spiders]

Thank you Dr. Hossenfelder. Always a pleasure to have my tiny brain stretched.

[@Jamie-Russell-CME]

"damn tiny" :)

[@trucid2]

For all we know the so called elementary particles could be hiding 15 orders of magnitude of internal complexity.

[@RalphDratman]

@Lemon Party, I wish you hadn't mentioned that. The idea that my understanding of physics might be even more (fifteen orders of magnitude more) inadequate than I thought shrivels my self-image down to the Planck length itself.

[@stormtrooper9404]

Ralph Dratman Than imagine how the physicists feel about that themself? 😂

[@naughti_penguin2340]

And thats why I love science.

[@havenbastion]

You misspelled infinite levels.

[@MyStarPeopleExperiences]

Love the "it's a little hand wavy" descriptor. Nice.

[@michaelkelly6583]

Thank you Sabine. Profoundly interesting.

[@brendanwilson5745]

I love these presentations. So clear for the non-physicist. I listened to her book, ‘Lost in Math.’ If one gets only one book on physics, that should be it. I only wish she had narrated it. Next time I hope she does.

[@ricardoalves3475]

What a good day to post a video - 0202 2020! It's a palindrome! If the twos were ones what would it say in binary code?

[@ricardoalves3475]

In ASCII 01011010 seems to be Z (capital z)

[@ricardoalves3475]

I determine Z to be the minimal length of Nature!

[@francoisdreesen9684]

1010 that would be number 10 in decimal.

[@Merilix2]

It would be awesome to see you sometimes on the UWL Channel in German with Prof. Gaßner & Co. I really like your clear distinction between what models can tell us and what not, clear distinction between facts and interpretation and so on.

[@Harkmagic]

Finally, a good explanation of why the Plank Length may actually be a minimum length. All other sources I've simply state it as fact with no explanation. I do wonder if it doesn't simply represent a fundamental limit of what can be measure rather than a fundamental limit of what lengths can exist in nature.

[@pawemarsza9515]

That depends on your definition of word "length"

[@OpenWorldRichard]

Yes, An important point: "It may or may not come with a discretization". The distinction between space being quantised and there being an inability to resolve the Planck length distance through measurement is crucial. When considering the Spacetime curvature side of the Einstein equations there seems to be no limitation which sets a scale at which these tensors apply. The Mass / Energy side of the equation has size constraints in the sense that we know that there are observed limits on the smallness of the mass of an entity such as a proton, neutron and an electron. I also take issue with the idea that you get a black hole if you compress matter into a small enough space. This is OK in theory but in real situations there are limits to the ability to compress matter and the most dense object is the neutron. If you take the density of the neutron and calculate the size of a black hole that would result, it is 3.4 solar masses. Therefore, given that it is impossible to compress matter beyond the density of a neutron, it is impossible to get a black hole smaller than 3.4 solar masses. This is confirmed by observation. So for me the Planck length is an interesting calculation with no practical value and space and time are continuous and not discrete. www.academia.edu/5009126/The_evolution_of_the_universe www.academia.edu/5038836/The_Unification_of_Physics www.academia.edu/5927513/The_Spacetime_Wave_Theory Richard

[@tannerfaust433]

Not at all clear that you can’t have matter denser than a neutron. The interior of a neutron Star may have quark states of matter or possibly something more exotic.

[@OpenWorldRichard]

@@tannerfaust433 However, the density of a neutron star and the density of a neutron are about the same. My point is that until we discover black holes smaller than 3.4 solar masses, we have good reason to believe that 3.4 solar masses is a lower limit on black hole size as the calculation based on Schwarzschild radius would suggest. Richard

[@tannerfaust433]

@@OpenWorldRichard the center of a neutron Star is not necessarily the same density. Depends on the Equation of State...which is unknown.

[@OpenWorldRichard]

@@tannerfaust433 Agreed, but my point here is that the presenter is using the idea of a very small black hole of immense density as an explanation relating to the Planck length which is proposed as a concept in fundamental physics. My point is that it is unwise to assume that such small black holes can be created when nothing smaller than 3.4 solar masses has ever been observed. Richard

[@JamanWerSonst]

0:25 Sabine Hossenfelder - Needs a haircut lol

[@cjheaford]

This is a great explanation. I’m glad I found your channel.

[@dennisdonovan4837]

Great video Sabine (as always - that’s why I subscribe) … If enough interest is shown … would you consider doing a video on the “digital vs analog” debate concerning the fundamental property of our universe with reference to what you presented in this video? (I’m sure you would add some insight and, as a result - value - to the discussion)

[@michaeldebellis4202]

What digital vs. analog debate are you referring to? In my experience discussions about digital vs. analog are about representing and processing information, I wasn’t aware there is also a debate about some fundamental property of the universe.

[@Li.Siyuan]

I love somebody who can pronounce Schwarzschild, Einstein and Planck correctly. I'm so fed up with people, mostly Americans in the case of 'Plonck' mispronouncing them 😊

[@matthiasreichshof9896]

Your gap between liking or disliking someone, because of his pronouncation is ridiculous.

[@HAL-nt6vy]

While incorrectly punctuating repeatedly in your comment, you must resist this urge to be smarmily pedantic. Your lack of amiability will cost you. Please consider an upgrade.

[@_BLACKSTAR_]

Does it really matter if you understand what they mean?

[@hakonsoreide]

So, you're saying that when "Plonck" mispronounces people, you are fed up mostly with Americans? Or was that perhaps not what you intended to say?

[@ixglocTV]

@@matthiasreichshof9896 You forgot to say "or her", leaving a gap for dislike to some.

[@frenstcht]

Best explanation of this that I've ever experienced. Thanks!

[@brooksiefan]

A lovely introduction to a most fascinating subject.

[@manoo422]

Oh wow, new hair coming up, cant wait!

[@SabineHossenfelder]

Ha :p

[@manoo422]

@@SabineHossenfelder :-))) ❤️

[@christophergreenDP]

@@SabineHossenfelder Your NYC fans (me) think your hair looks great as it is Sabine!

[@wonderbucket1242]

But, I once saw a plank with a length of 3 meters.

[@codex8797]

Bro my plank is 7 inches long

[@EclecticPuppet]

You forgot to include c 😂.

[@Thomas-gk42]

Thank you for the clear depiction of this so interesting stuff. "That's not difficult to calculate, so let's do it", Sabine lets us participate in her knowledge, without any arrogance. Happy about that channel

[@GoldSrc_]

I just found your channel, amazing content, subscribed.

[@SimonSozzi7258]

You're having a hard time not singing. It's cute. 😅

[@grandpaobvious]

She's a serious scientist. Have some respect.

[@insightfool]

....and fail...

[@tomhummel2641]

@@grandpaobvious, she has made videos where she's singing. I think that's what the humorous comment is about.

[@scoooterbob2321]

@@grandpaobvious Yes, she has several talented and entertaining music videos! She's an artist, have some respect!!

[@TheGreatSteve]

I can fully sympathise with "needs a haircut". My barbers is now an ice cream shop.

[@whitekiltwhitekilt1611]

Hello there Sabine. Excellent presentation, interesting topic. I like when Sabine says “u all know”, I didn’t know. My bad.

[@Chris.Davies]

A better analogy - or at least possibly better - is to imagine that if a hydrogen atom were blown up to be the size of our entire galaxy -- so it's over 100,000 lightyears across, then a Planck Length would be roughly the same size as the Paramecium many of us studied in school. en.wikipedia.org/wiki/Paramecium They are just on the limit of what can be seen by the naked eye. Now, if THAT doesn't impress upon a person how small the Planck Length is, then I don't know what could.

[@insylem]

2:35 "That's not difficult to calculate" 3:04 Goes way past my skill level

[@jman8128]

Thank you for the classes. It drag me back to the reality of the world, to make serious thinkings, other than watching porns day after day.

[@kenelliott8944]

So glad to know that I'm not the only one that's constantly going back and digging into the porn supply between episodes!!!

[@jman8128]

@@kenelliott8944 Hugs.

[@ps200306]

I approve this week's blue background. I also approve the tenfold increase in subscribers to this channel in the last six months, and the surpassing of the 50k mark. Here's hoping that it will take off like crazy in 2020. Doc Hossenfelder deserves a wide audience.

[@frankmullins4379]

Thank you for your assessment...cheers

[@pawelnowak9440]

1oo years and no progress in phisics

[@tofu-munchingCoalition.ofChaos]

QCD is from 1973 So at best 47 years of no advancements in new theoretical physics supported by enough evidence. There is plenty of progress in empirical physics. (There are many advancements in pure theoretical physics, which might later be "proven" as correct. For theoretical advancements of real physical understanding it is difficult to pinpoint the year - the year of the theoretical development or the year where enough experimental evidence was gathered which is a continuous process). Perhaps Penrose gave such an advancement in 1996 with his interpretation of QM. Inflation is in a strange state of acceptance. What about that? Perhaps an existing theory of dark matter is correct. What about that? Perhaps what you wanted to say is not "no progress in physics" (QCD is not such a big step from gauge theory) but "no revolution in physics" (classical -> quantum and relativity). I'm not sure if a revolution is even possible. Progress sure. But we might more or less have discovered the guiding principles which might need only a few corrections.

[@erik-ic3tp]

@@tofu-munchingCoalition.ofChaos, so no new Newton or Einstein then?

[@tofu-munchingCoalition.ofChaos]

@@erik-ic3tp I think there are phycisists (and mathematicians) capable of doing something comparable. But the time is not right. Newton had the experimental work of Galilei (Galilei invariance, What a force is) and Kepler (Kepler's laws) to build up upon. Einstein hat the experimental work of Michelson and Morley (invariance of the speed of light) and the theoretical work of Planck (quantisation of action in black body radiation) and Riemann (curvature on manifolds, idea that this could be an explanation of gravity) to build up upon. Without Newton and Einstein the ideas would likely have been put forward from a group of physicists and it would have taken perhaps a few years longer. Evidence of that is that Leibniz, Hilbert, Poincaré,... had very similar ideas like many other scientists. The time for those discoveries was right. It is exceptional that one scientist alone had so many contribution. But the discoveries would have been made soon. Another evidence is Quantum physics. It took many ideas of different phycisists to develop. Not a single genius. In both cases (Newton and Einstein) the only thing one had to do, is to take those observations (from other scientists) seriously and run with it. Mathematics takes care of the rest. This is the point which is difficult. Take the right things seriously, having the mathematical ideas or knowledge and making it precise with mathematical precision. At the moment the experimental data is not useful to do that. We have no clear indications of a physical law. Instead we have evidence that something is not understood but many possibilities (additions or changes in physical laws) to fix it. There is no clear path. At least to me. And you can see it in the theoretical scientific literature. At the time of Einstein and Newton it all circulated more or less very closely around a specific solution. Today the theoretical physics models are all over the place. Build on very different ideas. Addressing different observational deviations from the two standard models. I think we have to wait until experiments stumble upon clear evidence for a new *basic* physical law. And perhaps someone has already developed the consequences and guessed the right law. So bottom line: I think the *circumstances are not right* for the geniuses to do the work. The *geniuses are waiting* for the spark of evidence pointing towards the right direction.

[@tofu-munchingCoalition.ofChaos]

@@erik-ic3tp But on the other hand, it could be that there is no new basic law. No new revolution like Einstein, Newton or quantum physics. Perhaps only a few minor changes are enough. Nobody knows. Here one question is important: *What makes Newton and Einstein and the quantum physics revolution so special.* In _my opinion_ it is the change in mathematics (and therefore a drastic change in intuition). Before Newton physics was not described by differential equations. Before Einstein the mathematics of measurements was very simple (point evaluations of functions). Since Einstein measurements are observer dependent (connections, ...) and static time and space are replaced by a different mathematical construct (spacetime). Before the quantum revolution everything was based on finite dimensional spaces. In quantum physics the basic mathematical objects are infinite dimensional Hilbert spaces and unbounded self-adjoint operators. Both contributed in many ways to physics. But so did other (not so well known) phycisists. And there are many phycisists who discovered basic fundamental laws. The only think I think stands out is the revolution in the mathematical machinery. But I could be wrong. This is only my impression. Bottom line: It could be that the mathematical machinery (+) is there and there is no such major evolution. Twisting a little bit (in the right direction) might be enough. (+) One could something say something about mathematics here. But I chose not to do. So much text already.

[@agnimitratalapatra4112]

Your every video cleans my mind from vagueness; why do I so late to subscribe your channel 💐

[@theodoresweger4948]

Very good as usual. Just got throught dealing with the mole..

[@mrroneill99]

Fascinating! Why do physicists worry about extrapolating distances to zero, producing a singularly, when the Planck length may be the limit?! Thanks for your exceptional videos. ❤️👏🇮🇪☘️

[@jimgolab536]

Great video! I had never learned that the Planck Length had any connection to GR; I thought it was simple dimensional analysis and could not see why people extrapolated this to actual physics. Now I know. Fascinating.

[@thstroyur]

Well, it still _is_ simple dimensional analysis - you can flavor it with some hand-wavey physics, and then call for an extrapolation, that's all. Here's the catch, though: what do you make of the Planck mass?

[@thegnosticatheist]

You take a topic that is taught commonly in schools in a way that is dogmatic and at least to some extend misleading but you turn it into very sensible and easy to digest explanation that strips out all the voodoo parts. I love it!

[@paulwalsh2344]

Sabine Hossenfelder, I love how you are so honest about embracing uncertainty. I don't mean Heisenberg's uncertainty, simply the uncertainty in science. That science is only as certain as the hypotheses and the data that support them. That science doesn't know everything... YET... understanding that the scientific method is the ONLY way to possibly know much about anything. You don't need to demonstrate some supposed authority or sensational hypothetical claim. You videos just show what is, with all the appropriate caveats required.

[@philochristos]

That is such an interesting thing to think about. I was trying to get to the bottom of whether space was quantized a few months ago, and I found two studies that suggested it wasn't. One of the studies had to do with images from the Hubble space telescope, and I can't remember what the second one had to do with. I wish I could find it.

[@blueckaym]

Nice video! For me personally the feeling I get that QM is working with the fundamental elements of the Universe (at least some of them) is that we've established that practically all of them exhibit wave-like behaviour, but most of them are extremely stable. Perhaps even indefinitely stable. Which makes me think that unlike a classical wave which loses its energy as entropy into the environment, quantum waves have these "areas" of stability and they can't lose gradually** their energy despite vibrating constantly. (excluding travelling thru expanding SpaceTime, though I'm not sure if & how massive particles get stretched by expanding SpaceTime?) ** Actually, there are examples of how objects can lose gradually part of their energy. For example how hot atoms (which is basically every matter above MBR) radiate waves until they lose their temperature and reach close to the absolute zero (ie equalize with their environment, of which the MBR is currently the bottom). But this thing is that even supercooled at least half the atoms with their electrons, quarks & gluons are still stable.

[@gordonsparkes4831]

Dear Dr Hossenfelder, I don't know if you take requests, but if so, here's one - what is the principle of "least action", what is a Langrangian, and where do they get us? Kind regards, and thank you for so much well-presented and orthodoxy-challenging information!

[@ambraabate]

very clear and sound contents. thank you

[@robsierra516]

Thanks so much for sharing, I like these videos 😊

[@_SpamMe]

Ah. I always assumed a minimal length would mean some sort of discretization. But a level of blur makes (instinctively anyway) much more sense. Thanks.

[@lukabc31]

what if ether has no minimal descrete blocks? Why should it have at all? It is a fluid which is a perfect carrier of any peturbations.. So not need to be splitting it into infinity.. You will not create a wave with infinitely small wave length anyway. So we should be fine with scales relevant for us where protons and electrons are and we should understand how they are formed. Then we would see it is not any made up virtual gluons but toroidal field with it center which can have different shape and parameters based on how the toroid is ballanced and overlaid with other shells etc.. Frequency management is the right path to discover secrets of matter manifestation, not cutting space into infinitisemal bits.

[@michaelrexrode3759]

I love the Professor Doctor's pronunciation of diameter. I shall adopt it for myself.

[@amlecciones]

In college around, 2002, I made a paper about the superstring theory and the Planck length for my philosophy class :P Still a very interesting subject that has lots to go.

[@hasanshirazi9535]

Great insight. Thanks. Does this mean that even if we get a quantum gravity theory, we will not be able to understand what actually happens at the "singularity" of a black hole, or what happened at the "singularity" of Big Bang?

[@pghislain]

You talk about the length of structures of elementary particules. So Heisenberg + Shwartchild redius drive us to the Plank length. So can we quantizies the lenght between 2 objects ? So using unbreakable minimal lenght, the movement equations must be rewritten at that level. Then we can multiply to get the elementary weird effects expressed, may be, in our physical scale....