31 Subatomic Stories: Why are extra dimensions possible? 

No matter what happens in my day, I can't help but smile when I see you doc, I guess it's because physics is everything and that matters :)

Those Koala puns were unBearable

Dr Lincoln: after discussing hypothetical models of physics, can you also cover some of the famous failed ideas, and why they has failed? These would be very educational both as case study, and also because time to time I see some of these resurfacing in some arguments.

Dr. Lincoln and Fermilab, thank you for making all this wonderful and often esoteric information about the fundamental nature of our universe so accessible to even folks like me who aren't knowledgeable about either math or physics! It really is a joy to watch these videos and get informed about these fascinating topics!

I like how you answer the tough questions, to the point and intellectually honest.

Hi Dr. Lincoln, thanks for another great episode. Instead of just extra spatial dimensions, what would it be like if there are extra temporal dimensions? What would an extra temporal dimension even mean and are there any theories which talk about them?

You remind me of Jack Horkheimer and I always half expect you to end your videos with "Keep looking up!" Your videos are great and I really find it a treat to get to hear from someone really at the heart of new research.

Knowledge isn't a destination, wisdom is applied knowledge, the journey is everything - thanks for taking us forward with each episode - you are the best!!!

Your a brilliant commentator, one who I have always enjoyed receiving educational dialogue, within your presentations.

Some great insights about science communication, thanks Don. More public lecturers could benefit from taking this on board.

I hope this series keeps going forever

Always a pleasure - thanks, Dr. Don!

Thank you very much Don, from Uruguay, time before and after Don Lincoln, unique explanations

"Likeability is imporant". Don, man, you got it all XD.

Amazing, amazing video! Thanks for the clarity!

Fermilab is a national treasure, we are very fortunate to have all our national laboratories. Dr. Lincoln ably represents them, in my never humble opinion.

Great video, cleared up a lot of misconceptions

Your points about science communication were great!

11:00 Thank you! This is such an important point even - especially - in school. When you have the sort of teachers where students leave school and say they hate physics (maths, ...). The proudest moment I think I ever had was when some (high-school) students, after the year was done, came to me and told me they liked coming to my physics class (and this was not the "physics nerds" but "normal" students). I hope I made an impact on their lives that they won't be parents that tell their children that "they also hated physics in school and it does not matter if their child is good at it".

I Appreciate your series!

this is what ive been looking for all my life

Idk why the algorithm hasn't been putting this on my feed! Sub/notified/shared, great content.

What exactly is spin? And what does it mean 1/2 spin, 1 spin, 2 spin

Hi Don.. didnt know u had a ted talk.. checking that out now 😁 Just did on 2 of them.. great stuff, Don.. engaging and full of rich, understandable info.. certainly not easy to do in front of a lot of people and on a big show.. congrats!! Totally delayed but well deserved.. thanks.for bringing science closer to the general public!! 👏

Fantastic science communicator ❤️

this is the best explanation of gravity and extra dimensions!!!

you're the best Don! love your videos!

Great video as always. 👍

"whisper at a rock concert" - I *love* this analogy. Thank you for the concept upgrade!

Please keep these videos going

It would be very nice if gravity had something to do with the weak force Usually the forces cancel from a distant viewer. But since electrons are usually orbitating an atom about 1% speed of light. The relativistic time would make electrons be pulled by other atom protons and vise versa, creating a universal pull. This could be why gravity is so weak. I know the weak force has a short range and many other thing, i just found the idea cool.

I’ve heard it in documentaries that the small dimensions are spacial dimensions, and that there are 8 or 9 spacial dimensions and one temporal dimension. I’ve always wondered why these were classified this way, and time isn’t treated just like another dimension. Thanks, love the show!

Thanks Doc.

This was a nice start! I hope you can say more about this particular subject, and the effects of those extra dimensions interacting with the cosmic inflation, meaning space time results. If there is possible to us to have "space time bubbles", we can also have some, at least, minimal rules variations inside those bubbles, is not true?

I've been loving this series. Could you give us some insight about the hypothesis of spacetime (or one of its characteristics, like possible curvatures) arising from quantum entanglement? What are the things this hypothesis could explain?

Thank you so much for another fantastic video. Really appreciate you giving some insight into the reason why extra dimensions are being considered for the unification of the forces. One thing that has always perplexed me about black holes. I have heard that if you could look backwards as you fall into a black hole, you will see time speed up behind you as you fall into the compressed time/space interface before the event horizon. If that is the case, wouldn't someone from the outside just see you slow down and then stop altogether before you fall in? How does a black hole actually move in space, if directly around it is a slither of space/time that has effected stopped in some kind of weird time stasis? Obviously I am mistaken but I cannot see the way out, it is like I am stuck in that field right now! OMG!

I can't thank you and your team enough for all the things I have learnt from your simple explanations.

this one was super fun!

Thanks Don

As a chemist (people almost as cool as physicists) I spend a lot of time in front of people freezing things and blowing things up in the name of education. Thanks for the book and science communication recommendadions. Always looking for ways to share a love for science.

Does this man have a podcast? I need this in my life

Great episode, as always! My understanding about energy is that it can depend on the observer speed (like kinetic energy). If this is the case, does that mean that the space-time curvature is also observer dependent? Thanks!

Hi Dr Don, I truly love your videos and your awesome taste for puns. I was wondering, we have been looking (and still are) for extra dimensions of space to explain the weakness of gravity. But could it be possible that the other forces are working in less than 3 dimensions at the quantum scale? I am not sure if this would apply to the EM force since it spread to all direction infinitely... but since the weak and the strong force only apply to very short distances, maybe everything is 2D at their scale?

Brian Greene Theories explained. I like how Don Lincoln evaded talking about string theory speculation. :)

Dr. Lincoln, could you perhaps address the question in one of your future videos whether all atoms will eventually decay into elementary particles? There are so many different factors to take into account from entropy to possible recombination (not the epoch) to the expansion of the universe to the unimaginably long time that it would take for most of the elements to decay that I am not able to come up with a definite answer myself. Much appreciated! (I actually posted this in the comments of the previous video but I missed the critical window of opportunity of a few days, so I'm posting it again.)

Hello Dr. Lincoln! Thank you for all. Why we keep on listing 4 forces, and we don't include in the list also that one derived by Black Energy?

Thanks for the video! Would love to hear your opinion and/or explanation of ads-cft correspondence. Juan Maldacena is a genius but I have a tough time following his explanations

Gravity as a force itself is incredibly weak indeed, but it can interact over virtually infinite distances - Shapley attractor, dipole repeller, etc and all that "big" stuff!

As usual, very interesting video Dr. Don! Doesn't the gravitational force depend on whether or not a given planet has an atmosphere? Is the force of gravity the same throughout the universe? Thanks.......

Hello. Thanks for great videos! My question is: are there any theories, that describe laws of nature on fixed grid, something like cellular automata or more complex structures with local interactions?

Hey there Mr. Fermilab, I recently learned about the delayed choice quantum eraser experiment and I can't help but wonder: What would happen if I were to tie the choice of containing the wich-way-information to the outcome. Similar to the grandfather paradox. So basically when the particle appears as a particle it would take the way to obscur the wich way information and if it appears as a wave it would take the way to contain it?

6:08...We have now two *_koalafied_* 🐨 scientists with a cool sense of humor that are great science communicators-Dr Don Lincoln and Max Tegmark. 🐻 🍯 🤣

Hello Don, great video as always! Would it be conceivable that a theory of everything just can't exist and there would be some sort of threshold at which relativity / quantum theory takes over (at both sides of the threshold, respectively)

Cheers Doc Interesting you picked the correct (Dutch) pronunciation of my username, good intuition!

Thank you for making complicated topics so accessible to novices like me. I wish I had this as a resource when I was growing up. Also, doesn't gravity already act in four dimensions where other fundamental forces act in three?

Hi Don, are the circles of the theoretical 4th dimension related to the 4 dimensional holographic spacetime that Juan Martín Maldacena published a paper about? Will you do an episode about the holographic principle like PBS Spacetime did?

Don, what is your position about radical interpretations in particle physics, like it-form-qubit or amplitudeology?

Nice videos!! How many extra dementions do we need to make gravity comparable to the other forces??

Followup question about quantum gravity and graviton: As I understand, we have the curvature of spacetime caused by mass (or mass is caused by the curvature?), and we have particles with mass, and since particles are quantized, mass is also quantized. Do I assume correctly, that quantum gravity (assuming it exists) is basically the description of how a single elementary particle exactly curves spacetime? And in this sense, graviton is just the smallest quantum of this effect of how a smallest particles curves spacetime. Because in this case, the warp in spacetime must also be quantized, if mass is quantized. With this, we can talk about graviton without defining it as a literal force.

Hi Dr. Don, Could the asymetry of matter and anti matter in the early universe be linked to the universes preference of "handedness"? Or would that have been a factor in the high energy state of the universe at that time?

Hi Dr. Lincoln, I was wondering if scientists have thought of any experiments to test for LQG or string theory? Thank you

Hello, Dr. Lincoln, I'm a loyal viewer and a fan of TED. As such, your TED Talk caught my attention. For whatever reason, I was unable to find the video in their archive. Would you be so kind as to provide a link? Thank you.

Hi Don.. is it possible to test the existance of those extra dimensions gravity spreads to? What else do they contain besides the (possible) placeholder for gravity?

Dr. Lincoln, my question is based on what you mentioned in this video. If we assume that gravity is transmitted via gravitons, how do they appear? Who emits them, and does the emitter lose mass? And if the minimal energy is defined by Planck's constant, what happens if the energy of a graviton is much smaller than that?

If the solution to the Hierarchy problem is in fact the existence of looping pocket dimensions, then how would that affect the gravitational constant and the inverse relationship between space and gravity? What is the estimated sizes of these pocket dimensions since large ones can be ruled out after GW170817?

Hi sir.... is the energy level of the different forces permanent in extreme temperatures or does it change?

Hi Dr. Lincoln, knowing that the spacetime dimension is curved under the General Theory of Relativity, does it directly imply there's more dimension that the 4D spacetime itself? just like 1D loop which actually 2D, or 2D ball surface where actually there hidden 3rd dimension of radius. If so true, then the gravity itself that create the extra dimension.

I've been waiting for an opportunity to ask this question for some time: Could the bending of spacetime by concentrations of mass (such as a planet) be explained by a displacement (rarefaction) of the fields in the standard model? For instance, it seems to me that an excitation of a particular field associated with a fermion excludes (by the Pauli exclusion principle) all other fermions of that field from occupying the same quantum state. Is there perhaps something else like that at work that might help explain gravity or the bending of spacetime?

Can you please help and explain the visualization of general theory of relativity? The curved space is understandable, but what about the time dimension? What exactly happens? Also, the Avatamsaka Sutra describes enlightenment as an awareness of the "interpretation of space time continuum"

If the Higgs Mechanism is responsible for giving matter its mass, do we still need a quantized model of gravity? If mass is what bends spacetime, and gravity is matter travelling along those bends, does that mean that gravity is an emergent inertial force and not fundamental to the standard model? I love your videos and explanations!

Instead of protons, can quarks, leptons and bosons be accelerated and smashed into bits to find smaller particles?

Could you do an explanation of the exclusion principle?

Any thoughts on the X17 particle? Does it exist? Does it demonstrate a new force? Also, why isn’t the Higgs interaction/mechanism considered the fifth force of nature?

Did you hear about the Koala that opened up a space themed restaurant? It was named Mars, Soup, & Eels .

Hi Don , if gravity can escape to other dimensions ,what stops the other forces from doing the same?

Dr. Lincoln, who made the opening and closing music AND animation. Thanks.

Thanks

Any thoughts on the 3rd dimensional upper limit GeV being the plank length of the 4th dimension? Graviton at 7.5e+21?

Dr. Lincoln, would having gravity in other dimensions also mean the other forces of nature would have to exist there also but just weaker ?

Hi Dr Don, if quarks move inside protons and neutrons at nearly the speed of light then a) where do they get the energy to do so and b) do they ever accidentally bump into one another?

While three of the forces clumping in ~5 order of magnitude and the other one being another 35 off does moot some interesting questions, is there any other reason to expect them to be of similar magnitude? Do we have any understanding on why any of them take on the values they do? Unsatisfying as it would be, could the values just randomly be what they are for no reason? On the other side: would the anthropic principle allow us to observe a universe that has a more uniform distribution?

Hi Don. We often say "this nucleus contains so many neutrons and so many protons" . Is it better to think the nucleus contains so many up and down quarks of certain color charges, held in particular possible lowest energy configurations by gluons, weak bosons and photons, which we observe as "nuclear shells", and is a proton just the simplest and most stable one of these ?

Hello Sir, Im so curious about science but also about how many T-shirt you own? Another video, another T-shirt😉 Love your videos, best teacher ever

I have a question about the extra dimensions or more specific on your example with the spreading of a force in one, two and three dimensions. Due to the spreading over a sphere a force is inversely proportional to the second power of the distance in three dimensions. So if you go from a three dimesional space to a four dimensional space the force should be inversely proportional to the third power of the distance. But Newtionian gravity is inversely proportional to the second power of the distance, so this fourth dimension can not be just a larger Euclidian vector space. You mentioned other dimensions as tiny loops. How does the math work out so that gravity keeps a law of inverse second power of distance but just gets much weaker with extra dimensions?

Hi Don! Is it possibly that the number of dimensions in our world is not a whole number? Like defining the dimension (roughness) of a 3d fractal. Maybe that value is different on the subatomic scales than on cosmic scales. Could it be the reason why some forces are strong on one scale, but weak on the other scale?

Is there any experiment with gravity pulling different single atoms?

Dr. Lincoln, How do we reconcile the inverse square law which describes gravity propagation with other dimensions when the inverse square law itself is a 3D artifact? Doesn't the square law seal the deal? Can you 'radiate' in eight dimensions?

1:50 I wonder if you multiply the relative force by the distance over which that force is reduced by 50% whether you would get figures that are very similar...?

This is late but in regards to the hunt for a larger more general theory have you looked at Wolframs computational model or hypergraph system? Having looked at it I was particularly struck by the continuum limit formalism where with a sufficiently large array of relations and possible ways that system can evolve it naturally results in the set of relations producing a framework of "space" and the possible ways the system could evolve producing an analogous framework of branches representing the ways the system can evolve. Ultimately what strikes me of this model is that both of these turn out to be represented by Einstein's field equations in this continuum limit. The GR component is familiar but the QM part representing the Feynman path integral amazingly appears to follow its own coupled set of Einstein's field equations where the wavefunction becomes a "probabilistic" branch space of all possible states/outcomes with the possible measurable outcomes being projections of the wavefunction in a way reminiscent of Flat land. If this were to be the case I can't help but ponder whether it is possible that gravity could possibly be leaking out between other parallel branches. As cosmological tests of extra dimensions gravity could leak into often rely on the assumption that these extra dimensions will effectively slow down gravity's speed or propagation I have to wonder how the larger analog to the speed of light for branch space would impact such a result. As the analogous counterpart to the Ricci tensor is complex Hermitian there would logically be both dilution into and out of these branch states. Thinking about the distribution of matter including the mysterious dark matter this suggests the possibility that leakage into our dimensions could be an explanation for not only the weakness of gravity but the existence of dark matter. The halo nature then of dark matter then could beprobabilistic

Hi! I want to ask a question, sorry if I will be a little bit long. Scientists say matter and antimatter annihilate each other if they touch. But how can this "touch" happen for the first hand? Atoms normally never touch each other, they just connect, but the nucleis keep distance. As far as I know it needs a big ammount of energy to push atoms so close together, that the nuclei actually touch (that's what going in the middle of stars, they unite and form helium atoms) So how can a proton and an antiproton annihilate each other if they repel each other?

Could each of the three spatial dimension be made up of three small extra spatial dimensions, such as planck volumes? Maybe gravity inside planck volumes or other small extra three spatial dimensions for each spatial dimension, while other forces do not? Basically wondering if planck volumes (three spatial dimensions) extend out into each of the three spatial dimensions

On the subject of extra dimensions: could the value of various fields (like the electron field) be thought of as extra, compact dimensions? After all, the value of the electron field at a location in space is orthogonal to spatial dimensions.

Hey Don, you have mentioned in one of your previous videos that Gravity is the effect due the curveture in the Space-time. If that is so, then how come Graviton particles mediates/transfer the force of gravity?

Hey Don. I'm always confuse from this kind discussions about gravity been a Force when it should be simply the consequence of the curvature of space and time flowing. Why we keep considering gravity a Force?

i learned and laughed, thank you.

Dear sir don , In Samar's question you didn't told whether the energy is conserved or not but I am here to ask that if earth pushes or bends the fabric of spacetime then there should be a reaction force acting on the earth by the spacetime which should be equal to the gravitational force of the earth 🌎🌎🌎 , and why dont we feel that ?

If you have two particles near each other, time moves faster on the opposite sides of each particle since they are further from the center of mass. Would time moving faster on the outer edges causing a basic pressure to move the particles together and look like gravity?

What if Quantum foam works something akin to tiny hooks in spacetime and forces from energy/mass pull on the Quantum foam which in turn pulls in spacetime?

Do electrons pass through single neutrons?

Hi Dr. Don. Why do radioactive elements decay at predictable rates? What is stopping the atoms in a sample from together and agreeing to all decay at once, just to mess with the scientists?