I am a physics teacher. Very much appreciate your thanks! And thank YOU for the video's that inspire me every time to walk into that room with distracted minds and kick ass!

@albirtarsha5370

3 жыл бұрын

As a former physics teacher I too felt gratitude for Dr. Lincoln's message. I especially appreciate his precision in language and leaving out the hype and hyperbole that pollutes most popular scientific literature. He brings such a clear and sober perspective.

@johnm.v709

3 жыл бұрын

Spin of Indivisible Particle : Watch... kzread.info/dash/bejne/oKKf2NGCeN3agNo.html

@johnm.v709

3 жыл бұрын

@@albirtarsha5370 Spin of Indivisible Particle : Watch... kzread.info/dash/bejne/oKKf2NGCeN3agNo.html

@cranjismcbasketball2118

3 жыл бұрын

Im just an Earth Science teacher.... ☹️

Thank you Dr Lincoln for the shout-out to the physics teachers. You made my day!

Don must be having a good day! His smile is more contagious than covid

@suvashshrestha1731

3 жыл бұрын

Yeah it is seen

As a Physics and Chemistry teacher that is very passionate about about science thank you for giving a shout out to Physics teachers! My hope is to inspire future generations of scientists and hopefully they pursue a career in physics and contribute to advancing the science. Fingers crossed.

I loved the way you just slipped in the bit about a preon being a point particle like a quark, but smaller. That's the sort of line you'd expect to see in a Douglas Adams novel :-)

Dr. Lincoln, I was shocked to find your face at the center of the universe.

@adamiozsa2967

3 жыл бұрын

I guess everyone one of us is at the center of it's own observable universe :p

@cevynotter9555

3 жыл бұрын

@@adamiozsa2967 Coooooool! :D

@randolphtimm6031

3 жыл бұрын

@@adamiozsa2967 That was a point.

I'd like to say something nice about another person at least once a day and today it is your turn: Don, you are an awesome human being!

@BenjaminCronce

3 жыл бұрын

If you're ever feeling down, @Anton Petrov will remind you that you're a wonderful person.

Congrats for having a great HS physics teacher - mine was so bad I had to become a physicist! He’d explode if I asked him a question he wasn’t expecting...or couldn’t answer.

@john-or9cf

3 жыл бұрын

@MichaelKingsfordGray Anonymous? Moi?

For a while now it's been bothering me that we could see the CMB from the opposite side of the universe, for precisely the reasons that you outlined. I wondered if it was due to inflation and now I know. Thanks for that. Now I can get on with obsessing over something else.

Hi Doc, I've read about something called the Axis of Evil and was led to understand that there was a hemispherical split in the CMB where one side was notably higher energy. Is this at a smaller scale than the topic of this video? Looking forward to your next video.

I read Guth's book about inflation many decades ago, and never really wrapped my head around it. In 5 minutes or so, I now have a much better of what idea of (what may have) happened. I chalk this up to two things: Mr Lincoln, you are a great educator and the power of the modern computer graphics to illustrate what a book could never manage.

Nice shoutout to the educators, classily done and a well worthy fist bump 👊🏻👍🏻

At around 4:50 you say the duration of expansion at > speed of light (inflation period) is between 10 to the -32 etc. What meaning does time have during this period? How does it relate to time as we experience it now?

11:20 We should rename _dark matter_ to _mystery matter_ and _dark energy_ to _enigmatic energy_ 😁

@nHans

3 жыл бұрын

Love the alliteration, but what happens when the mystery gets solved ... do we rename _mystery matter_ once again, or do we keep mocking physicists' choice of names because _mystery matter_ will no longer be mysterious? I do agree that the they shouldn't be named _'dark'_ anything. There are already unscrupulous mystics and opportunistic religious leaders scaring the less-informed public: "Scientists have confirmed that _dark energy_ exists, something that our religion has always warned against. Protect yourself from evil by doing what I tell you ..."

One needs not be the best teacher in the world, but if they can become somebody’s favorite teacher, that would be enough to change that one individual’s life forever. I would like to thank my university physics teacher Dr. Mario Freamat.

Thanks Dr . Lincoln as illuminating as ever.

Thank you Dr. Lincoln for another awesome episode In order to understand the differences between matter and anti-matter and matter-dominance, I remember hearing about CERN's experiments with anti-hydrogen. Considering we are talking about leptogenesis, did it take place when conditions in the universe were suitable to form atoms in the first place? If not, then why are we trying to find these differences in atoms and not the individual particle pairs? Is there any indication that these differences would manifest more strongly in atoms rather than the particles themselves.

I so wish I have had teachers like this. :((

Another fantastic episode. Would be great to see more videos on the earliest moments of the big bang.

Such a nice nod to the teacher. Well done!

My Physics teacher: John Kirkbride, Lansdowne College, London. Thank you.

Q: Shouldn't we observe a kind of energy bias in atomic bindings due to constant compensation of the grid expansion - or perhaps a footprint of the expansion is unnoticeable at such small scales ?

I couldn't ever thank you enough for such great content, Dr. Lincoln.

Thank you Dr. Lincoln. Listening to your videos, I don't know how, has a calming effect on my anxiety about all the problems I have to resolve for to achieve my goals.

Question: What are the most prominent alternatives to inflation theory?

@john-paulsilke893

3 жыл бұрын

A wizard floating on a cloud watching you all the time and having books full of contradictions written in his all knowing words.

@mikejones-vd3fg

3 жыл бұрын

I dont know of any alternatives but I heard from one of anton petrov's videos that a recent study suggests the expansion isnt uniform, so not like a perfect ball expanding but a bubbling mess. I dont know what that does to the current theory, but the universe could be more of a dynamic beast than we've imagined with even different constants in different parts of the universe. There was also a study that found the elctromagnetic force to be different in a far off galaxy, not sure of the details and its pretty new but thats pretty cool if true, having different physics in different parts of the universe? No need for parallel universe for funky stuff to happen.

@nmarbletoe8210

3 жыл бұрын

Penrose's CCC is very different although of course it has universal expansion (which is necessary as we are experiencing that now)

Even if we had enough antimatter for the particle beam, the antimatter would just annihilate when it touches air after it leaves the (presumedly vacuum) barrel and thus blowing up the gun, user, and everything around it in a nuclear blast. 1 gram of antimatter would produce about a 40 kiloton explosion.

@drdon5205

3 жыл бұрын

Yeah, well, there's that too.

@fabianfierro

3 жыл бұрын

nobody said that the weapon would be used inside an atmosphere

Ahhh, high school physics. Mr S. had us do the ballistic pendulum experiment with a rifle in the high school physics lab. He had it brought up by the P.E. teacher who used it for the high school's riflery class. This type of hands on experimentation led us all to be great experimentalists. Given modern mindsets and current events, I guess we will have to say good by to the experimentalists and be content with the promising new crop of 100% theoretical physicists.

My most influential physics teacher in high school would make fun of anyone that asked questions, until I eventually dropped out of school, hating physics, one of my favourite topics.

@brothermine2292

3 жыл бұрын

Unfortunately, many high school teachers don't understand their subjects well enough to be able to answer questions.

[Q] :Hi professor, How were quarks' electric charges discovered ? (since quarks can't be detected directly, if I'm correct). By the way, thanks a lot for your awesome content :)

Is there a way to calculate How much charge and spin is required (if even possible) to transform a black hole singularity to a naked singularity

@nmarbletoe8210

3 жыл бұрын

yes, the method is to ask MichaekLingsfordGray to do it . i think it's when black hole gets all of it's mass from the energy of the charge, but I might not understand it right

Another great talk. I look forward to your interesting explanations of the universe as we know, or think we know it. I have to admit that sometimes the ideas are so beyond me that I have to give up but generally I can at least get something from everything you discuss. Thanks.

I love the way you talk about physics.

The radius of the observable universe is 46.5 billion light years, not 14. Gotta love that superluminal expansion!

@randolphtimm6031

3 жыл бұрын

43.982297 😃

Is there any growing consensus towards Vacuum Energy being the prime-driver of the Universes expansion?

@albirtarsha5370

3 жыл бұрын

I think that is the central problem of the Vacuum Catastrophe.

@randolphtimm6031

3 жыл бұрын

@@albirtarsha5370 If E=Mc^2, and c^2 is in dimensions of length*acceleration, where does vacuum energy originate?

@albirtarsha5370

3 жыл бұрын

@@randolphtimm6031 I don't know the details but vacuum energy comes out of quantum field theory. E=Mc^2 is the mass-energy equivalent. So this vacuum energy should have a gravitational effect due to that equivalence. However, the calculated vacuum energy from QFT is way, way too big. Thus the "catastrophe".

@albirtarsha5370

3 жыл бұрын

For more, Watch "The Vacuum Catastrophe" from PBS Spacetime kzread.info/dash/bejne/oGqeo7GPZ8XAY7w.html

@randolphtimm6031

3 жыл бұрын

@@albirtarsha5370 I see, Albir. I must confess to being quite ignorant. Amateur at best. I remember reading something on it but it's been quite a while ago and I remember virtually nothing. It seems to me that I connected it to the mass density of deep space somehow. Thanks.

I have heard of cosmic inflation for and would love an episode going into it more.

I really appreciate your thanks to Physics teachers. Over the years I have had just a handful of students who went on to pursue careers in Physics, and exactly one who listed me in his acknowledgements in his PhD thesis.

If the expansion is the same everywhere, shouldn't that mean that the universe is always "expanding faster than light" at some distance? Only the distance of that horizon from an observer should change.

@digolyan

3 жыл бұрын

Maybe what Don means is that EVERY point in the universe was moving away from every other point at more than the speed of light, during Inflation?

@nmarbletoe8210

3 жыл бұрын

@@digolyan That doesn't seem logical, unless there is a minimum distance... the early expansion is modeled as fast but not infinitely fast.

@cole2839

3 жыл бұрын

Yes, there are parts of the universe currently expanding away from us faster than the speed of light that we can never visit unless faster than light travel is created (not likely).

I don’t get why the explanation for “two points being similar” must be that they were once in contact. Isn’t it true that if their “creation” were driven by the very same laws of physics, they should look similar even if they never been close to each other? Like 2 shirts made in different factories are similar, even if they have nothing to do with each other. Of course it also needs further explanation and proof, but why is it ruled out in the first place?

@HansLemurson

3 жыл бұрын

The universe is surprisingly non-homogenous at the large scales. Galaxies are all vastly different from one another, and the distribution of matter is extremely clumpy. And yet the CMB is nearly completely uniform. Imagine if, to continue your example, every shirt in every factory on the planet came out virtually indistinguishable. You'd suspect some sort of past interaction between them, not just the "natural emergence of shirt-like forms from the basic laws of fashion".

@juzoli

3 жыл бұрын

@@HansLemurson Difference between the shape of galaxies is considered small scale. What counts as “large scale” is the big galaxy clusters, and the huge voids we can see here and there. But even on those scales, spacetime itself is found to be flat. That’s a measured fact. So if spacetime is curved beyond that, the “size” of that curvature is well over 100billion lightyears, much more than what we see. At least. But here, homogeneous means that if wherever we look, the AVERAGE density, temperature and other properties are the same in all ways. As opposed to a real explosion, we see big differences if we are looking at the direction of the explosion versus the opposite direction.

@jpe1

3 жыл бұрын

@@HansLemurson love your analogy to shirts, but I think the OP isn’t understanding the “look similar” phrase in this context. You nailed it when you said that the “CMB is nearly uniform” but for those who don’t understand what the CMB represents (or understand how remarkably uniform it is; most renderings of the CMB make it look rather non-homogeneous unless one notes that the temperature difference between the deepest blue and the brightest yellow is a small fraction of a percent of variation). If I may try my own explanation: Look at a sphere of the universe centered on the earth and one billion light years in diameter: it’s very non-uniform, with huge variations in temperature and density of matter, and we see this variation as bright spots of hot stars etc and dark spots of cold interstellar space, with variations of millions of degrees from hottest to coldest; same observations with the shell starting a 1 billion light years out from Earth and going to 2 billion, or 2 to 4, or 4 to 8, or 8 to the edge of what can be seen in visible light: all of those shells are very non-uniform, with huge clusters of galaxies and giant voids and in general lots of variation from place to place. None of this is surprising... But when we look at the outermost shell of the visible universe, which is only visible in microwave frequencies because it has been deeply red-shifted from the massive expansion of space over the 14+ billion years since those photos were emitted (thus it is called the Cosmic Microwave Background (CMB)) and is the glow from the time when the quark-gluon plasma of the early universe had cooled sufficiently for protons and neutrons to form, making space transparent to photons for the first time, *that* outermost observable shell is astonishingly uniform, varying in temperature by only a fraction of a percent from place to place. Absent a mechanism such as Guth’s hyperinflation there is no way for regions of space that were widely separated at the time to be so uniform in temperature.

@nmarbletoe8210

3 жыл бұрын

Due to the uncertainty principle, each independent point would get a "dice roll" of it's own for the initial conditions. Thus, the universe could be 10, or 100, or 10,000 times hotter in one direction than another. Instead, it's 1,100,000th hotter at most. . I'm making this up but it sounds right, eh?

Thanks for the explanation of why two gamma rays are needed. If it was just one, it would have to have zero velocity in the reference frame of the midway point of the collision, which isn't allowed for photons. Kind of mind-blowing.

I stopped watching this channel a few months ago b/c I felt like the speaker was talking down to me, or making fun of me, but in this video his tone is much more compassionate and understanding. Thank you.

This has just become a mini-pbs spacetime series.

@ashkebora7262

3 жыл бұрын

They've always covered the same or similar topics.

@thethirdjegs

3 жыл бұрын

@@ashkebora7262 what i meant was, this "show", sub-atomic series, a format adopted for pandemic conditions, has too many planned episodes with increasingly difficult topics - that it may become as complicated as pbs spacetime videos, just way shorter. 😁. No complaints, just pondering how fun it would be by then.

@militantpacifist4087

3 жыл бұрын

Always has been.

@tru7hhimself

3 жыл бұрын

@@thethirdjegs increasingly difficult topics means increasingly fun topics. there's more enjoyment to be had when learning something new.

@gyozakeynsianism

3 жыл бұрын

I prefer Dr. Don.

Appreciate the shoutout! Sub tuum, boys and best wishes for the upcoming exams! λ

Another fantastic video! Thanks!

Could you possibly make a video discussing AdS / CFT?

How come that galaxies move faster away the farther they are away from us? Why do galaxies not move at the same speed away from us?

@thomascoolidge2161

3 жыл бұрын

Because expansion is everywhere.. the galaxies arent moving so much as the space between us and them is increasing. The more space between objects the more expansion can happen. So it appears like galaxies are moving faster the further they are. Think of space like a highway where every few miles someone is adding a few inches.. If you look a few miles away you see it moving away at a few inches.. you look millions of miles away and you see it moving away at millions of inches.

@methemeticien

3 жыл бұрын

@@thomascoolidge2161 I like the balloon analogy....when you inflate it, the farther areas will move away faster..

@nmarbletoe8210

3 жыл бұрын

@@methemeticien me too... and a rubber band works the same way in 1 dimension... put marks for galaxies and stretch...

Why do electrons act as if they are massless (i.e have same velocities) when passing through a graphene sheet?

@shivamsharma-cw5wk

3 жыл бұрын

U came after seeing big bang theory🤣🤣🤣

@virajkapani6159

3 жыл бұрын

@@shivamsharma-cw5wk In what context are you speaking? I have received the same response many a times.

@shivamsharma-cw5wk

3 жыл бұрын

@@virajkapani6159 so there is this episode in the big bang theory show where sheldon tries to understand the same thing "why electrons act massless when passing through graphene sheet." Not even scientists know why such happens but i do have my own theory( it can obviosly be wrong) that when you look closely at molecular structure of graphene, it kinda looks like a hexagonal structure that is stacked. but what holds it together is weak force or z boson. So when electon passes through such structure, it has no valency to help it pass through which means no electromagnetic force. Weak force on the other hand, acts as a support to break the atomic tension and let electron pass.

@virajkapani6159

3 жыл бұрын

@@shivamsharma-cw5wk You are certainly wrong. It is not the weak force that holds the structure of graphene but it is the electrostatic force i.e Van der Walls bonding. And I do not get your point by valency of electron. And considering weak force interactions is highly unlikely given the fact that the weak force acts on left handed , half integer spin fermions and here when we consider electrons in the same quantum system or being massless i.e acting as gauge bosons , hence, it might not apply.

@virajkapani6159

3 жыл бұрын

@MichaelKingsfordGray They don't? They don't what? Can you elaborate?

Heh, I'm glad you guys noticed the metric conversion thing - and more coffee is always a good thing. Thanks for another great epsiode.

Dr. Lincoln , You are my hero.

In case someone was wondering: The German term for dark matter is dunkle Materie

@michaelm1

3 жыл бұрын

I was, thank you.

@Bassotronics

3 жыл бұрын

Slam Dunkle

Hi Don! I have a question: Why is there a limit to density/gravity to which matter then collapses into a black hole?

@kshitishp3662

3 жыл бұрын

The limit specifies the minimum amount of pressure req. To overcome all the degeneracy pressures so that what you are left with is just a singularity

@ARCANEmateCLAN

3 жыл бұрын

Kshitish is right. Due to the Pauli Exclusion Principle, there is a limit to which you can compress matter before the finite number of quantum states of fermions become saturated and the matter becomes degenerate. Beyond this point, to compress matter further the fermions would have to start occupying the same states. Ergo there is a limit before the matter collapses into either a new state (e.g. white dwarf to neutron star) or into a black hole.

Hi Don! Thanks for this great series! I have a question about the two distant places being "the same": If the explanation to that is inflation, than I would expect all places between them (which actually means all of the seen universe) to look the same in that sense (I mean, if I zoom in a picture of a mountain to a single rock until the edges of the picture are in the rock, all the inside of the image is now showing this rock, and it seems logical it's made from the same material). But according to the cosmic microwave background picture - that's not the case. Maybe I'm confusing unrelated staff... What am I missing?

Thanks for the videos

If dark energy has consistent density, does that make the big rip false?

@drdon5205

3 жыл бұрын

Yes. However, it is possible that dark energy could be changing with time. The data doesn't favor that, but neither does it exclude it definitively.

@user-bo2ob2kl5c

3 жыл бұрын

@super pershing if the carrier of that energy is distributed spatially, you can calculate its density. if the energy is stored on a rubber band, you can calculate the density by dividing the energy by its volume.

@abhiramvartak4149

3 жыл бұрын

@super pershing that's partially right, but we just don't know enough about dark energy. It can be a complete type of energy and if yes then it won't have density. But if we consider it as a fluid state matter made of bizarre properties, then it can have density. As the second possibility is believed to be more accurate than the first one ( as far as I have read ) we cannot neglect the probability of dark energy having density.

@nmarbletoe8210

3 жыл бұрын

@@user-bo2ob2kl5c Yes, I agree there can be a density of kinetic energy, assuming there are objects moving in a volume. . This is almost the same thing as temperature. . Perhaps there is a mystery about a situation where if there are no objects!? . Since the universe has objects, I guess that question is philosophical rather than physical... perhaps a universe without objects could not have an "energy density" ...

What's so unique that photons dosnt interact with higgs field...? Thx Dr. DON

@nmarbletoe8210

3 жыл бұрын

Photons don't have the type of "charge" that the higgs field does. Weak hypercharge...? . In other words I don't know but I heard words once lol

The Great Mortality in your bookshelf. I feel compelled to read this now. Thanks for the subliminal recommendation.

Loved the references to wave particle duality. The ANU ran Wheeler’s delayed choice experiment a few years back. I didn’t really understand how the apparatus worked but I’ve always found it fascinating. I would love to see a Sub Story on this at some point. And a g-2 experiment update. I’m literally foaming at the mouth. It’s seems to be taking a while... but that may just be a shift in time. We’re literally running blind. Terrible puns I know. 😔

Hey doc , I recently read a lot about the expansion of universe and the dark energy and had a question if the density of dark energy can be variable ?

@drdon5205

3 жыл бұрын

It could, but current measurements favor constant.

@plexiglasscorn

3 жыл бұрын

I was wondering same about dark matter, since it shows baryons are a minority and dark matter is sort of an elephant in the room. Are orbits of stars with galaxies with large amounts of dark matter showing increase of gravitational pull, decrease or are they constant over time?

@drdon5205

3 жыл бұрын

@@plexiglasscorn On current observational timescales, the dark matter appears to be unchanging. Over cosmic timescales, the clumpiness increases.

@plexiglasscorn

3 жыл бұрын

@@drdon5205 are there any old galaxies that significantly lack dark matter? By old I mean the way we see them now (close)

@donlincoln1961

3 жыл бұрын

I don't know. But older means more red shifted. I would Google it.

Is it possible that light repels dark matter and therefore dark matter doesn't exist in presence of light?

@lukeali1580

3 жыл бұрын

Hmmmm. Great thinking, but wouldn’t that mean pointing light into space will effect how galaxies interact with each other?

I like to hear from Don weekly.

Realy very punctual Fermilab, i love the fact of punctuality of it and fact that if u write a email to Dr Don Lincoln there is 70 percent change of being replied if the question is useful and related to physics

@drdon5205

3 жыл бұрын

73%

Well, mole of hydrogen weighs 2 grams since there are two atoms in the molecule. But that doesn't change the conclusion :-)

@drdon5205

3 жыл бұрын

Atomic hydrogen, then. Molecules are so.....chemical....

@plexiglasscorn

3 жыл бұрын

I’m surprised there are no chemists here to correct for average number of heavy hydrogen molecules.

"When the universe expanded faster than light", then why didn't it time travel? :|

@KasiusKlej

3 жыл бұрын

Universe is time traveling all the time.

@dankuchar6821

3 жыл бұрын

Because nothing traveled through space faster than light, space just expanded faster than light, according to the hyperinflation theory. Personally, I think there are other explanations that are more valid then hyperinflation. But there are many cosmologists who like hyperinflation. However, there are many that don't agree with the idea. It is an ongoing debate.

@KasiusKlej

3 жыл бұрын

@@dankuchar6821 It's been observed that distances between galaxies increase. Yet nobody likes the idea of inflation. It leads to discoveries of natural constants that are not constant and such nonsense. It's a bad idea, but it explains some of the facts.

Thanks Don. Great video as always. My question is how did the idea of inflation meld with the earlier calculations about the age of the universe and the rate of expansion? My current understanding is that earlier scientists observed the present rate of expansion and extrapolated back to calculate the time when the visible universe was very small. Wouldn't the introduction of inflation force a dramatic disagreement with these earlier results, since the "very small" period was before inflation and the current, moderate expansion rate (ignoring acceleration due to dark energy) is after?

Hello Don and a massive thankyou for all your fine physics content! Can a wave function be collapsed by another wave function/virtual particle or must it be an actual particle?

@cloudpoint0

3 жыл бұрын

We don’t know what causes a wave function to collapse if indeed it ever collapses rather than just merges into the wave functions that make up the surrounding environment (decoherence). It looks like when two fields interact, the point of interaction is what we call a particle. This likely doesn’t affect any wave function, just our perception of the interacting fields. Virtual particles don’t exist as objects - they are just continuous disturbances or jitter within the fields. If two wave functions touch they just merge into a composite and more complicated wave function. Don’t mix up fields and wave functions - different concepts. Fields have a certain abstract physical meaning and their waves transport energy from place to place. Wave functions are purely mathematical descriptions of a wave in a probability dimension and do not have any direct physical meaning.

Wow so early

Hi Don, will you talk about cellular automata theories for the universe, such as Stephen Wolfram's theory? I feel like this is where the future of theoretical physics is headed.

Really enjoying this series! I wonder if you can shed light on something I've never fully grasped, which is the curving of space and how it's "shaped". I get the idea, extrapolating from the concept of curved 2d surfaces eg a sphere. We can only see these are curved by viewing them from "outside" of the 2d surface ie from the 3rd dimension; this surely implies that for space to be curved or "have a shape" it has to be within a higher spacial dimension within which that shape can occur, just like a 2d surface is within 3d space? Is that right or is there a different explanation? And what if that higher spacial dimension is also curved within an even higher dimension - what implications would that have?!!

THANK YOU...PROFESSOR LINCOLN...!!!

Dr. Lincoln, great episode! 2 questions. 1) Why isn't 'scale' considered a dimension? 2) from a certain perspective wouldn't 100% entropy look identical to 0%entropy? Thank you for the amazing videos, and your dedication to enlightening the physics curious!

@albirtarsha5370

3 жыл бұрын

#1 scale is a property of dimension like graphing in Algebra. It is your ruler when drawing the axis. #2 Entropy is not on a scale of 0%-100%. Wikibooks says, "The SI unit for Entropy (S) is Joules per Kelvin (J/K). A more positive value of entropy means a reaction is more likely to happen spontaneously."

@coderider6629

3 жыл бұрын

@@albirtarsha5370 Entropy is a state of thermal equilibrium. It matters not what the units are, percentage in a relative value. If you have a 3cm cube with 100 joules of energy, in a vacuum, it is at thermal equilibrium; therefore at 100% entropy. If you expand that cube to 9cm, it is no longer in equilibrium; therefore no longer at 100% (25% I believe, but I could be wrong). As to scale, as you said all dimensions have a property we call scale. But if you have a singularity, it has no dimensions, but it still has scale. I do not believe it to be a property, but a dimension, and the first dimension that emerged from the initial state. We don't even get the 3 spatial dimensions until the strong force emerges (which implies singularities don't exist). I don't mind being wrong, it is how I learn.

@albirtarsha5370

3 жыл бұрын

@@coderider6629 Oh yeah, thanks. I kind forgot how entropy works. I don't understand the scale part though. A singularity is like a mathematical discontinuity. Typically when you are at a singularity you are no longer in the domain of a model. So I don't know what you mean that a singularity can have scale.

@coderider6629

3 жыл бұрын

@@albirtarsha5370 to me a singularity is a breakdown in the maths and don't actually exist, tho, if they do exist, then they would have a scale of zero or one depending on how you do your counting, potentially even a volume of 1E3 of whatever, say planck distance =1.62×10^-35m.

Don. Richard. Carl. What do these have in common? Hint - they all further ignite our curiosity for those of us who would like to know, but don’t.

Don is great that you been there. Ok, how has the trip? did have fancy colors and lights?

Hello! Great video as always! I would like to ask a couple of questions that interest me: 1) Gravity appeared after the Big Bang, or did it exist before? 2) If matter spread throughout the universe evenly after the big bang / inflation (Or how more correctly space expanded evenly), then how then could the first stars / planets form? Or has matter spread unevenly?

@thedeemon

3 жыл бұрын

We can't say anything meaningful about "before". The universe seems pretty uniform on large scale, on average, but there are small local deviations, these led to stars and galaxies formations.

@kenlogsdon7095

3 жыл бұрын

You can see those small local deviations that led to higher concentrations of matter by simply looking at the CMB.

@chriszachtian

3 жыл бұрын

Gravity appeared, according to german wikipedia, somewhen between 10^-43 and 10^-33 s: de.m.wikipedia.org/wiki/Urknall, so its the question when you say "THIS is the big bang". Many physicists feel that there is some unified force at the very beginning, from which gravity shall have spread off.

I love these

Few Questions:- 1. Some kind of energy or force is responsible for how we see the universe as it is working ??? 2. Does inflation theory has some mathematics included or just a theory?? I know that my first question seems illogical, but I think that there should be some reason behind this. So please answer.

There's a question I have that I have never received a satisfactory answer to and this episode reminds me of it. But I doubt that this is the proper place for the question. Sad, but I'll live with it.

I have a question about research in particle physics. In numerous CERN articles I read the terms statistical significance and standard deviations, I would like to know what they man and how the value is calculated. Thank you.

hi Sir DON, this episode was best, i watched half and couldn't wait to watch half after 2 nights. my todays curiosity how did super massive black holes and super massive stars formed in early universe, though that much matter wasn't available, which is available today ?

Hi Sir. Could you please explain about the quantum teleportation or super conductivity?

Hi Don.. good one in the photo with Alan Guth 😁.. was wondering what kind of contributions you made to science? Maybe the one u are most proud of in a video?

Damn that last part made me smile, shout out to Paul Sasse for being my first classroom contact with physics after avoiding it because I was afraid my enjoyment of the theories would die with the math, that Astro class showed me how much fun I have learning the math when I think of it the right way and it was mostly due to thinking like a caveman astronomer and building up with Mr. Sasse.

Thank you to my high-school teacher, Úlfar Harri (don't know if I should give full name so I won't). He really fed my spark for science and math until it became an unstoppable fire and I know I'm not the only one who feels that way.

Hi Sir. Can we get 3 or 4 photons of lesser energy than gamma ray photon when electron and positron annihilate thereby conserving energy and momentum?

Brilliant tribute to Mr Lamden.

This is a great video and a very interesting topic! The expansion of the universe, if the topology is a multi-dimensional closed space, say a hypersphere, would the horizon we see on one "side" of the universe actually be the other "side" of the universe as well? Therefore the two points that are in contact at the beginning _are_ still the same points today... the space "in between" that we have now actually expanded inside-out as the higher dimension is flowing "down" and intersecting our 3-D "plane" (Disclaimers: (A) I hadn't finishing my morning coffee when I watched and wrote this comment, (B) I am not a physicists, but I like to dabble and watch this stuff)

@thedeemon

3 жыл бұрын

That would depend on the radius of such sphere. If the radius is just right then those two points can indeed be the same one.

@raymitchell9736

3 жыл бұрын

@@thedeemon Yeah... or maybe not, maybe hyperspheres don't work that way?? Anyway the morning coffee is kicking in and what made sense then isn't so clear now... LOL 😁 don't worry, I'll leave it to the commenters to eviscerate my original post 😜🤪 As usually happens within one hour of posting... The way I look at this experience is that I will learn something interesting by asking questions and interacting!

after thinking about the electron - positron annihilation a bit, i am wondering what determines the products of any particle turning into others. is it just that any product from fields that interact with the one(s) in question is allowed and that the probability of producing another particle depends on how close energies of educts and products match? is entropy a real factor here (after all entropy increases when a positron and electron annihilate to form two photons)? but if so then wouldn't most subatomic reactions favour decays into photons (which conveniently can have all sorts of energies) rather than anything else whenever such a reaction is allowed?

@dankuchar6821

3 жыл бұрын

I honestly don't know a short way to explain the probabilities of one particle decaying into another, or the probability of a certain particle interactions. I guess the simplest way is stated is that particles drop to lower energy states, and there are different probabilities based on the initial conditions of the initial particles. It took me a year of nuclear physics to understand it. I don't have a way to explain it simply. I'll think about it and see if I can come with a good analogy.

Hi Dr.Don. I have a question, why don't we build particle collider between matter and anti matter and see what particles it produce.

Could you make a video showing the books you have behind ? At least the ones you like most.

As time passes after the initial event and the momentum of the expansion continues matter etc must become more diffuse and its gravitational pull must decrease so the expansion of the universe must speed up?

Do you have an opinion on Sir Roger Penrose's theory of Conformal Cyclic Cosmology as an alternative to inflation?

@narfwhals7843

3 жыл бұрын

It isn't really an alternative, it just puts inflation before the big bang instead of after. The end of an eon can be arbitrarily long so everything has time to interact.

@Raxiel497

3 жыл бұрын

@@narfwhals7843 it's an alternative explanation though (although I grant it's much more than just an alternative to inflation)

@11:03 For the metric crowd, 5 gallons is between 18.9 and 22.7 litres, depending on whether that gallon is imperial or US customary.

To answer someone's question, you mentioned that need to use higher energy waves to see smaller and smaller things - since we simply capture the information contained in the light we use to see with our retinas, is there a way to "convert" what we see using higher energy waves to visible light so that we can see it?

@drdon5205

3 жыл бұрын

Sure. X-rays, for example.

@nHans

3 жыл бұрын

Yes, we do convert high-energy waves to visible light so that we can see it. One example is common x-rays used to detect bone fractures and weapons in luggage. X-rays are high-energy waves that cannot be seen directly with our eyes. But by using special films and/or CCD tuned for x-rays, we can see the insides of our bodies and luggage. We also convert low-energy waves to visible light. Common examples are: • Night-vision goggles, which convert infrared radiation into visible ghostly-green light • Microwave detectors, which have been used to produce the famous Cosmic Microwave Background (CMB) image of the universe.

@TheLazyRonin

3 жыл бұрын

@@drdon5205 @Niranjan Hanasoge Thank you so much for your response! Ah of course, but I wanted to know more about the mechanism through which this happens as well as the ability to see very small things like atoms and particles

I'm not too good with numbers...though, 40L seems closer to 10 gal in my estimation than to the 5 gallons that you assert !

@drdon5205

3 жыл бұрын

If you look in the description, you'll note that the video was posted with a pre-mea culpa. It was too late to rerecord, given that it didn't change the big point.

@AdamShaiken

3 жыл бұрын

@@drdon5205 Obviously, I missed that. Thank you for pointing me there and for the level headed response.

@drdon5205

3 жыл бұрын

@@AdamShaiken Yeah...mistakes happen. Thanks for pointing it out.

Hi Don, Is it possible the gravitational waves was the kick off for our Big Bang ? And and when all black holes in future collided into one will cause another Big Bang .... cyclic event ?

For someone at the edge of our observable universe, are we at the edge of theirs? Is the direction of where the galaxies move different for observers in different points within the ObsUni?

@thedeemon

3 жыл бұрын

Yes, we're at their edge. Everyone sees themselves "in the center", since all large distances get multiplied by the same constant in this expansion, from any point it looks like all points recede from you.

Could nanoscale lithographic devices be used for quantum gravity experiments? Or are the effects too small even at those scales?

My serious question for you: Can any significant physics insights worth researching come from discoveries of new solutions of nonlinear (partial) differential equations? i.e. Can us professional mathematicians (we specialize in math, not physics) - specifically differential algebraists - be of any practical help to physicists?

@nmarbletoe8210

3 жыл бұрын

I hear that Einstein's equations are only solved exactly for a small number of cases

@whatelseison8970

3 жыл бұрын

@@nmarbletoe8210 That would be a pretty clear corollary to that being true of Newton's theory of gravity. The N-body problem is certainly no easier in GR.

Some Points are smaller than other Points. That clears up a lot! :)

Whatever happens doc, don't loose your mischievous smile!

I would like to see a video on *Hawking Points*

Hi Don, I'm wondering how correct it would be to say that a quantum field is equivalent to the wave function of probability of the particle affecting it. Also, a better metaphor for the big bang would be ice expansion in a bottle but obviously hot and at Universal scale

@cloudpoint0

3 жыл бұрын

Quantum field theory doesn't recognize the existence of particles (that's old QM thinking). In QFT just fields exist and they can be disturbed in regular and persistent ways. Intersecting waves can be predicted using the wave function.