I like how John A. Wheeler puts it: Matter tells spacetime how to curve Spacetime tells matter how to move.

@KasiusKlej

3 жыл бұрын

"Keep curving left" said Saturn's moon to spacetime "so I can go straight as I always do." "You're going as an asteroid belt from now on" said spacetime to the moon.

@wulerhaufung9468

3 жыл бұрын

relationship goals

@juijani4445

3 жыл бұрын

@spaghettarius a Then what about a stationary object (0 acceleration) ? Oh and by matter, I also meant energy cause matter and energy are both in fact equivalent according to Einstein.

@juijani4445

3 жыл бұрын

@spaghettarius a But if I were to take an isolated system consisting of 2 massive objects of equal mass (say A and B) orbiting each other as in a binary system and then having an object of lower mass as compared to those other 2 (say C) right at the neutral point of A and B then wouldn't C curve spacetime even in an isolated system?

@juijani4445

3 жыл бұрын

Also, I get that concept where you have to dive into nuclear physics where some of the mass of the nucleons goes into the binding energy required to keep the nucleus stable so the total mass of the nucleus is less than the sum of the masses of all individual nucleons. Can be used as an analogy right?

_"So this is how the universe dies... with thunderous applause."_ --Queen Amidala, probably

Dr. Don Lincoln, thanks so much for the interesting video! Really grateful for explaining Dark energy once again :)

Thank you Dr. Lincoln! What a nice way to start my day!

I could listen daily to this stuff. Thanks for taking your valuable time for this, much appreciated.

I'm always glad when I see a new one of your videos in my feed.

Thanks for one of your best lessons so far.

Awesome as usual. Love it.

Delightful. Thank you.

Yet another excellent video Dr. Don. Gotta love these theoretical discussions. For me at home it's "Subatomic Stories Is Everything"! 😉😉👍👍

Yay my note got mentioned. Much love

Hi Dr. Lincoln! I just wanted to say thank you for taking the time and resources to answer my question on the hoopla of the Higgs Boson. Thank you for being a wonderful science communicator!

@jameseproctorpmp

3 жыл бұрын

Space is expanding faster than the speed of light from us anything beyond about 13.2b light years. We know that space expanded slower than 74 kilometers per second per mega parsec before about 4 or 5 billion years ago so it might be slightly further than 13.2b light years. Light travels at approximately 300,000 kilometers per second. We know a mega parsec is 3.26 million light years. If you calculate the speed of light and the expansion of space, the point where space is expanding faster than the speed of light is around the beginning of the universe so we can see the cosmic background radiation and many of the first galaxies. We are living in a great time because if we were alive one billion years from now, all of the early galaxies would be beyond the cosmic horizon. We also know that the universe itself has expanded at least to a radius of 46 billion light years from earth. At those most distant areas of the universe space is expanding over one million kilometers per second away from us which is more than 3x the speed of light.

The diagrams for this week's questions were super helpful!

THANK YOU PROFESSOR LINCOLN...!!!

thanks Dr Don!

amazing explanations with the math. it's very literal; matter of fact. always enjoy these :)

Your the best. You don't look down on less learned people. You try to bring them up to date, and that's very much to your credit. If my old Math teacher did the same. I'd be a genius by now. Your the True meaning of a teacher.

I liked the analogy to water freezing and how inflation could be the energy released as from the separation of the strong force. That felt so comforting... but sounded like that was over simplified or not well accepted. Thanks for the video!

What a great episode.

I just got a text from my buddy in the outer rims of the 2nd bar of Andromeda. They're calling the post merger "Andromaway"

@frederf3227

3 жыл бұрын

Andromaway, andromaway, andromaway, andromaway, andromaway, andromaway, andromaway, andromaway, EEEeeeeeEEEeeeeeeEooooOOooooooo a weeumbumbahwayyyyy.

@JMW80

3 жыл бұрын

LOL!😂

@fnamelname9077

3 жыл бұрын

@@frederf3227 I had NOOO idea what you were on about, until those eee's. And then I knew *instantly*. Hahahaha!

@GlossRabban

3 жыл бұрын

@@frederf3227 in the jungle, the mighty jungle.

I really enjoyed this video.

Heck yes for the Abbott and Flatland shoutout.

Thank you sir

what a pleasant break this is

9:49 interesting depiction of a moving jalaxy distorting spacetime with its jravity in that jif you showed us!

@Garryvision

3 жыл бұрын

Would you drink Gin whilst watching Gyrating Gifs? Steve Wilhite, the creator of the GIF format says it should be pronounced 'JIF'... I prefer the hard G, Graphics Interchange Format but hey, I didn't name it!

@aarav_sharma

3 жыл бұрын

Why are you Jay?

Thank God for Dr Lincoln and others like him.

I STRONGLY recommend Flatland; funny, insightfull and incredibly funny. I stumbled upon this little gem while studying for a Linear Algebra term at uni.. Well done prof.

Thank u sir

Great explanation of flat space

"These pretzels are making me thirsty!"

Sir u are the best

Thank you for taking the time to do these videos. Given that space is rigid and space is flat, and that the arc we see drawn by a thrown basketball is it travelling in a straight line through (predominantly) a curvature in time, is there any relation between "dark energy" and time? Could it be that the expansion constant is the rate at which time is added to space, and that if the universe were to shrink time would run backwards? On a separate note, I wonder if some quantum uncertainties could be related to these systems "stealing" energy from the expansion in order to prevent themselves from succumbing to it (or, maintaining gravity).

Thank you Dr. Lincoln for making these videos... I really like the way you explain things and bring a sense of humor into the discussion making the subject matter more approachable. I can see that you have a great passion for all things physics, but do you have a specific area that interests you the most?

@drdon5205

3 жыл бұрын

Where physics meets philosophy, and physics has actual and valuable answers.

@raymitchell9736

3 жыл бұрын

@@drdon5205 I see, you are currently making these videos with those questions... and I can see that has a huge appeal. I know you've covered unexplained physics, (love those videos BTW) Have you looked into other unexplained areas of natural phenomenon? - and I don't mean misinterpreted, but verified unexplained? I know this channel is not for that, but just curious if you have looked at it.

@drdon5205

3 жыл бұрын

@@raymitchell9736 Like what? Probably.

@raymitchell9736

3 жыл бұрын

@@drdon5205 There are many, so I will ask about one, if this is not be one you looked at, perhaps you can mention one... ~2007 I attended a talk at SRI that (and sorry, I can't recall details) presented some evidence for Lithosphere-Atmosphere-Ionosphere Coupling, the so-called "Earthquake Lights" people see as a precursor to major quakes. As I searched trying to find the details for this comment, I see there is a model: LAIC "can explain most of these events as a synergy between different ground surface, atmosphere and ionosphere processes and anomalous variations which are usually named as short-term earthquake precursors." And related? Might be the Mystery of the Brown Mountain lights in North Carolina.

@drdon5205

3 жыл бұрын

@@raymitchell9736 This is outside my expertise. I would Google just like you would.

I get the feeling from watching these videos that there are many more barriers to space travel than just propulsion/fuel or energy.

Lol, someone is in the room. Dr. Don is actually being held hostage

@ChargeOfGlory

3 жыл бұрын

timestamp? where in the video dod you notice?

@ChristopherCurtis

3 жыл бұрын

At 1:39 you can hear someone cracking the whip. He gives a worried sideways glance a couple seconds later.

@thethirdjegs

3 жыл бұрын

@@ChristopherCurtis Shoot. I heard another near the end of the vid. They both sound like a door instead of a whip.

@MarxistKnight

3 жыл бұрын

If you look carefully, he has arranged his books behind him so the first letter of each title reads “for the love of god, please send help!”

@hartunstart

3 жыл бұрын

Don't worry. He has dark energy in his pocket to make the room expand by surprise.

Interesting. And roger penrose has a good explanation too.

Great video, however I think it would help if you clarified that objects beyond the observable universe aren't *moving* away greater than the speed of light (i.e. v>c) at 12:53. It's simply that the expansion of space between us and them increases the distance such that to catch up with them the observer would need to travel faster than c. It's a simple but important distinction that took years to click in my undergraduate days!!

Hi, Dr. Lincoln, always enjoy your videos. Just a thought. Does/would entropy assist DE in the eventual equilibrium of the universe or would disorder create a situation of an increased chance of galaxy collisions. I haven't thought this through so I wonder if it is as contradictory as it sounds.

Thank you for being so awesome! Could you elaborate on why gravity counteracts dark energy's expansion of space? Dark energy has often been described as 'creating more space' or 'stretching space' indicating that there's more distance to cover than there was before. This indicates additional space for quantum fields to exist, which means more zero point energy in the form of virtual particles & frequency harmonics. (Boy do I hope I'm using the right terminology. I'm thinking Casimir effect.) It just seems weird that dark energy causes more energy for other quantum fields too, even if it's tiny. Are there literally more locations for things to exist being created by dark energy's expansion of the universe in the intergalactic medium & beyond? Why does gravity's curvature of space prevent that?

Regarding to Jenaf37's question, I guess it would be worth connecting it to answer to ChangeGamer, raising up that objects _seem_ to be moving away from us, but they actually don't have such motion nor velocity. Meaning, they don't have the kinetic energy relevant to such a speed. Actually, some of these objects might have their "own" velocity vector directed (so moving) towards us. But this velocity is far too low compared to their apparent motion given by the expanding space between us and then! ;-) And maybe worth explaining this doesn't violate special therory of Relativity, as it is an "emerging speed", only due to the accumulated distance between these objects and us. This is the same point than if you have a turning light ray projecting on a giant screen far, far away. The light emitter doesn't turn faster than light, but spot on the screen will seem to move faster than light if the screen is far enough. But again, there is no information transmission, each spot being causally independant from each other, only correlated by the light source. This is the same for objects moving from us, simply moving at the sum of "elementary distances" between us and them, not moving faster than light by themselves.

Rather eclectic library you have behind you, doc!

@williamprior7831

3 жыл бұрын

Quick, we need to see if he's sending us messages

@DaBlondDude

3 жыл бұрын

It'd be fascinating to a list of the books

@tommywalker3942

3 жыл бұрын

@@DaBlondDude I read The Great Mortality based on seeing it in the background recently, remarkable read. Any more suggestions for a similar book?

@DaBlondDude

3 жыл бұрын

@@tommywalker3942 Well, he suggests a few himself in these talks and the bookshelf is easy enough to read (the parts we can see). One book I suggest for anyone is Bill Bryson's "A short history of nearly everything". Another I'm reading (again) right now is Ben Goldacre's "Bad science". Beyond that I'm a bookaholic and read all over the spectrum but you may enjoy a Facebook group I'm in called 'Doctor Anna's Book Club' (she's a scientist and science explainer) where a science based book is proposed monthly, and discussed

@DaBlondDude

3 жыл бұрын

@@tommywalker3942 oh yeah, FYI the current book in that group (yes, I quite often read more than one book at a time) is "Forces of nature" by Brian Cox and Andrew Cohen. Others were 'The Selfish Gene' by Richard Dawkins, The Elephant in the Brain, etc

I really like the fact that you focused your talk on the most likely prediction for the end of universe. I get totally bored watching videos discussing all those other alternatives (like big crunch for instance) that were now ruled out in favour of the explanation you presented.

Hi Dr. Lincoln, thank you for this amazing series. One of the things it made me reflect on is the question of death. How is death fit the basic law of energy conservation? That is, when someone dies, what happens to their life energy, where does it “go”? And would this law actually lean toward the existence of a soul, that may “encapsulate” such energy? I know this is a big “philosophical” question, but am curious to know how it's viewed from a purely physical perspective… Thanks

@KasiusKlej

3 жыл бұрын

When someone dies, most of his life energy goes to feed the worms, worms get plenty of calories. Then some of it goes to heat the air. Some of it goes to chemical reactions. And, depending on what you mean by life energy, some of it stays in bones for a long time. Soul is immaterial and therefore has no mass or energy, it exists as part of our universe though, or at least, since it's immaterial, somehow interacts with our world. The existence of soul should be evident not only to physicist, but everyone who can observe that there are creatures around with mind and soul.

@belshel4997

3 жыл бұрын

I'm interested in what may happen at the very moment of death regarding the physical energy level. Worms follow much later... Also, if you believe in the existence of a soul (which personally I'm uncertain about), then it probably would have some sort of energy, I believe.

@KasiusKlej

3 жыл бұрын

@@belshel4997 No, believe the physics, it wouldn't have any sort of energy. Soul is like a property. Man has a soul, I know it, I have seen men, and I have seen a creature without it, a beast, as well, so I know what a soul is. It is like a character, each man has a character. Or like a mind, everyone has his own mind. All this properties are immaterial. That is also why some say that soul is eternal, because it is not made of material, but that is incorrect, soul is quite mortal, I think, still, different people append different mythology to what a soul is.

@belshel4997

3 жыл бұрын

@@KasiusKlej Many people believe in many things, of course. However, I'd rather keep things strictly physical (rather than metaphisical). The "soul" is by no means the nucleus of my question, I mentioned it almost as a way of a metaphor, and at any rate only as a reflection of some energy form. Hopefully Dr. Lincoln will give us his educated answer.

Woah! To think on your answer of how the Hubble constant says that at 4285 mega-parsecs, things are moving away from us at the speed of light, gives some very interesting notions of what we experience in our reality. The mind bending part, is then, by definition, according to those observers WE are moving away from them at the speed of light. Am I thinking of this the wrong way? And taking this one step further, even if we are moving away from another observer at the speed of light, WE do not feel the effects of moving at light speed. Fascinating!

@michaelsommers2356

3 жыл бұрын

As stated in the video, istant galaxies are not moving away from us. Rather, they are being separated from us by the expansion of space. That is not at all the same thing as moving.

@drdon5205

3 жыл бұрын

@@michaelsommers2356 True, but it looks a lot alike.

@michaelsommers2356

3 жыл бұрын

@@drdon5205 Yes, but it seems to confuse people to say that distant galaxies are moving away faster than the speed of light. We need better vocabulary.

thanks Don, now I have existential crisis in the morning as well

Can you do a video on the cosmological constant problem? Or at least give a summary of it & how you think it can/will be resolved?

I love your show. It is so nice to take a small break from politics!

Thanks Doctor Lincoln a fine show as ever. i have a question. if one drops something in Liquid, some of the Liquid breaks from the surface , eventually returning. to a molecule in this escaping Liquid it could seem like all of Space and time were expandig, to be suddenly overwhelmed by another force, gravity. my question how do we know that Our experience is not an artefact of some deeper reality like the Liquid With something dropped in it.

Plz explain d new definition of KG(planck's constant related definition)

I am a great fan of this video series. I have a question, due to quantam behaviour a pair of virtual particals can appear randomly and disappear.. what is a probability for big bang to occur out of nowhere? Is there a tiny tiny possibility if waiting for long enough ?

Dr Don, I'm not your best student... but I really enjoy the class!

Hi Dr. Lincoln. As space-time "stretches" or expands, how do we explain the fact that its permeability to EM fields does not change? I would think that with "stretching" permeability should decrease, hence the speed of light increase. Thanks.

Regarding dark energy and multiverse. You mentionned a possible lava lamp scenario for possible universes colliding. Could a universe collision explain both the energy require for the inflation model and, alike a lava bubble that got energy in the lamp expanding/rising to then cool off, explain why our universe is expanding?

Hi, can you make a video re. the concept around the convention of "the unmeasurable one-way speed of light" as presented in the recent Veritasium video? Thanks and best wishes, Annie

I liked your comment about dark energy vs mass energy. What would a contour map (concentric cylinders) of this ratio look like when mapped onto a galaxy. Is dark energy considered for the galaxy models that describe galaxy rotation?

Hi, Dr Don Lincoln, I am a great fan of your videos and the information you provide us through them I just wanted to ask that I have prepared a model of expansion of universe which looks pretty weird as I am only a high school student. I just wanted to verify if my model for expansion of universe is right or not. How can I do that ?

@abhiramvartak4149

3 жыл бұрын

@spaghettarius* ohk, thanks

Love the series, love learning. That's why I love the series, especially the questions. I have one for you.... Why is the CMB always depicted as an oval? I would think it would be more like a sphere or at least a football. Thanks for your answer

@cloudpoint0

3 жыл бұрын

The CMB should be shown as a sphere viewed from the inside. This projection can’t be depicted well in a flat image so they compress the image in a certain way to let you see the CMB in all directions without too much distortion in certain parts. The tops and bottoms of a sphere become exaggerated in a flat projection so they are compressed more. Like in this Earth Mollweide projection: thumbor.forbes.com/thumbor/960x0/https%3A%2F%2Fblogs-images.forbes.com%2Fstartswithabang%2Ffiles%2F2016%2F02%2FMollweide-projection-1200x601.jpg They could show the CMB as a flat image like below but things look odd at the top and bottom edges: thumbor.forbes.com/thumbor/960x0/https%3A%2F%2Fblogs-images.forbes.com%2Fstartswithabang%2Ffiles%2F2016%2F02%2Fplanck13-002a-1200x600.jpg

@michaelsommers2356

3 жыл бұрын

It's know as the Mollweide projection. See en.wikipedia.org/wiki/Mollweide_projection

@educatedguest1510

6 ай бұрын

The only serious explanation of CMB in the article Medium: The Universe is Not Cooling Down!

Electrons: *Particles or Waves?* Someone asked a question on Sabine's video presentation of pilot wave theory a couple weeks ago basically what is the use of particles when you have QFT. I had responded saying that I had thought it was because when you run the double slit experiment on individual electrons you get a definite ping on the screen as opposed to a smooth probability distribution of the interference pattern of a wave like you see with a single photon. This went down a whole rabbit hole that I don't know if it was ever actually answered. Dr Lincoln, can you please explain how individual electrons run through a double slit experiment show up as definite pings that when accumulated over a bunch of them show the well known probability distribution of the double slit experiment?

I think Jenaf 37 meant faster than light expansion during inflation, which is a statement I`ve seen a few times and wondered about.

awesome viewing ! I enjoy it so much . Yes , i agree with you so . The universe will end one time , beacause it had existed since a long time . when it will end , there will be nothing in the universe , no the Sun , the earth , the water , the air , the stars , the Aliens , the galaxies , etc. , I think .

Can gravitational lensing by a large cluster moving at a high translational velocity be shown to accelerate, or shift the frequency of the light on the trailing side of the lens?

I would very much interested what happening inside an atom when it is accelerating. As I see a movement of an object can only be interpreted in a frame of reference. A frame of reference are created by matter itself. If there is no reference the speed is meaning less... It means if we bombard space time section with high mass particle the frame of reference could be manipulated. See frame dragging. Could it work in microscopic scales if the energy concentration/mass is high enough?

I have a question. Have we considered the possibility that space, like a spring, expands and retracts. We could be in the period during which the "spring" is expanding from its contracted position (big bang), so it is expanding with an acceleration, but eventually will reach its "rest" position and start decelerating and eventually start contracting. So, like a spring that has been contracted, it expands for a period of time, then retracts for another period, then expands, etc.

The part about how flat spacetime is showed with the reason being "it's easier", always "annoys" me about explanations. To me a simplified (thus wrong) explanation is exactly why I get confused. :) Has done so since I was in secondary school and I took way longer studying as I was looking for books with in-depth explanations so I could actually grasp that simplified, totally general idea.

During typical phase transitions we observe on Earth, like liquid to solid, temperature remains constant while releasing energy. Is this also true for higher phase transitions? Does this effect occur going from plasma to gas? From quark-gluon plasma to plasma? Is that what you were referring to when you mentioned the decoupling of the strong force, or is that something different?

Thanks for a great series. Why doesn’t neutrons decay in a neutron star? Best regards, Erik

@cloudpoint0

3 жыл бұрын

Neutrons need to emit an electron to decay (and an antineutrino). The very high gravity or pressure of neutron stars prevents the electron emission from happening.

@drdon5205

3 жыл бұрын

@@cloudpoint0 nuclear binding energy comes into play too.

Hi Dr. Lincoln, Regarding your final question answer: I've always wondered about what exactly scientists mean when they say that at high temperatures, the forces merge into one force. Do we just mean that they have the same strength and range as each other? Because if they were truly one force, wouldn't this one force react the same as itself to temperature changes? So it seems that the one unified force would already have to be made of component forces with differing reactions to temperature changes in order for it to be split. Is my reasoning sound? I adore your videos. Thanks.

@drdon5205

3 жыл бұрын

It's like how electricity and magnetism are the same thing, but look different. The connections only become apparent at high energies.

@stevenjones8575

3 жыл бұрын

​@@drdon5205 Thank you for the response. Apologies; while I understand the electricity and magnetism analogy, it still isn't clicking for me. Forgive my layman's errors, but my understanding is that electricity and magnetism are the same thing that manifest as one or the other depending on the observer's frame of reference. So rather than electricity and magnetism having different properties from each other in an absolute sense, you could merely change reference frames to make the same interaction appear as one or the other. So special relatively ties these together neatly in my head. And while the electromagnetic force's varying manifestations are just a matter of perspective/frame of reference, I don't see how the same can be true for high/low energies. The strength and range of the weak force is actually changed by the energies, rather than it just being a matter of perspective; is that accurate? I just don't see how a force can split in an absolute sense due to lower energies unless it were already composed of component forces. Thanks again; I promise I'm not trying to be obtuse, but rather understand.

@drdon5205

3 жыл бұрын

@@stevenjones8575 Hi. Briefly, consider the following. The weak force and electromagnetism are the same at high energy. They both involve the exchange of massless, spin-1, objects. Then, as the energy drops, the Higgs field becomes non-zero, giving mass to W & Z bosons, and not to photons. At that point, the weak and EM force become different, while being the same at higher energies. The questions you are asking are good ones and it takes some work to appreciate the answers.

@stevenjones8575

3 жыл бұрын

​@@drdon5205 I see. It seems I need to better understand the Higgs field before I can really understand what's going on. (The question in my mind now is "Why do some of this one force's force-carrying particles gain mass at lower energies while others do not? Does that not imply that there were already 3 force carrying particles with some property that causes them to react differently to the Higgs field?") But it's not fair for me to expect a doctorate program for free from KZread comments, haha. Thank you for your time and your responses. It gives me direction on where to further look if I want more detailed answers.

@drdon5205

3 жыл бұрын

@@stevenjones8575 They >>DO

Hi Don, when we talk about the possible scenarios for the end of the universe such as heat death and big rip, on the time scale of billions of years isn't the most likely scenario that our distant descendents will have progressed to a level whether they are able to manipulate the universe and control its destiny? This assuming we don't destroy ourselves or reach a fundamental limit to our ability to progress our understanding of the universe.

@drdon5205

3 жыл бұрын

Beats me. We don't know enough about dark energy to find out if it is manipulable.

Surprised you didn't mention the possibility of non-constant dark energy and the big rip as an end of the universe. Maybe a future episode.

This is the way the universe ends ,not with a bang but a whimper .

Flatland is a great read. Highly recommended .

Does expansion of the universe have effects like time dilation or lenth contraction between the receding objects.

1. is there any chance that there might be some series of big bang had already been happened before our known one? 2. can we predicted from the rate of expansion of space that its follow the sinusoidal curve or say a periodic curve,?

It would probably be more accurate to say that the _visible_ universe expands at the speed of light. If the entirety of the universe (both visible and non visible) is infinite and physics are consistent throughout, then it must expand at infinite velocity as points with infinite distance (megaparsecs) between them will have an infinite separation velocity. If the non-visible universe is finite but has consistent physics throughout then, I believe, we currently lack sufficient information to determine it's size expansion rate. If physics differ between the visible and non-visible parts of the universe, or vary throughout the non-visible universe, then it would become even less likely we'll ever know the overall size or expansion rate of the universe.

Don, could phase transitions occur during the expansion of the universe and liberate energy to create new matter?

Please correct if wrong. that the Higgs field takes in speed and gives mass. A space field could give speed and reduce mass. Here’s the key tho, the ratio of exchange happens different, going in we get 1:31 but going out might only need a 1:1. This would explain a lot I believe, probably wrong tho lol

What 'traction' does the expansion of space have on matter? For example, if you were somehow to attach a rope between two objects diverging because of the expansion of space, what tension (as a function of distance and mass) would you expect the rope to be under? Is it the Higgs field coupling the masses to expanding spacetime, or are they simply following geodesics and the force in the rope is actually accelerating the masses to keep them at a relative distance?

Hi Don if it is not known what is dark energy and even if it exists (did i get it right from previous videos) how come we can calculate its influence in places like vicinity of the Earth? (I recall that for distance galaxies it is light frequency shift, but how can it be traced back to like planets)

@drdon5205

3 жыл бұрын

We're pretty sure dark energy exists. We're just not sure what it is.

Hi Don, I am still puzzle with the expansion and the speed of Light. Is Light going faster in an expanded universe or is it an absolute absolute constant ?

Is dark matter only found around ordinary matter or could there be swathes of dark matter in the intergalactic space invisible to us? As the space is expanding due to dark energy, could it be that inside the black holes dark energy is formed which is the fuel behind space’s expansion? Brilliant channel. Thank u!

Hi Sir. Interesting video. If the objects at a distance more than 4285 megaparsecs move away from us with the speed greater than that of light, then the light coming from them will not reach us. Is this the reason behind why we can see only a part of universe i.e observable universe but not the entire one? If not so then why can't we see entire universe?

How on-the-table still is the idea of a cyclic universe, with big crunch followed by big bounce and so on forever? Does inflation appear in any way similar to the big bounce which followed the previous crunch as far as our current low-energy theories can tell?

Hi Dr Don ... if galaxy is not moving and is stretching with space then how can we say all superclusters will merge into The Great Attracter or Lanekia Supercluster... saw it in some other video

@cloudpoint0

3 жыл бұрын

Superclusters aren’t gravitationally bound so expansion of the universe should carry the galaxy clusters within them apart. The Great Attracter might slow this expansion locally a bit. I’m not sure if any visible galaxy is close enough to be pulled into whatever is at the heart of The Great Attracter faster than space is expanding, maybe a few are. Individual galaxy clusters are gravitationally bound so the galaxies within them should merge over very long times.

another question about this "flat 3D space" that physicists mean. Why do they represent that with cubes and not tetrahedrons? It's also confusing when people like Dr. Neil DeGrasse Tyson and Dr. Michio Kaku explain how dimensions come to be. Their version tends to be: First you have a singularity, let's say a dot, because it has no dimensions, then when you add a dot and draw a line, you get 1 dimension draw 2 more dots and connect them again and you have a square, which is 2 dimensions draw 4 more dots and connect those again and you have a cube, which is 3 dimensions. Why do they have to "simplify" that, so that kids know what they are talking about? (i'm just assuming now) Why not, in levels of freedom? First you have a singularity, let's represent that with a dot, because it has no dimensions Add a dot, draw a line between them and you have 1 dimension or a line. (can be a curved line too for all I care, maybe at that point it's close to a black hole???) add one more dot and connect them with lines, and you have a triangle or a 2 dimensional thing add one more dot, and connect all the dots again, and you have a tetrahedron or a 3 dimensional thing Isn't that a bit easier to explain, in their version of dimensions, people will get confused because they will think that if we want to go to 4 dimensions, that they have to draw at least 8 more dots, while in my explaination it's still just one more dot. My dots actually represent those levels of freedom. I also doubt this one more dot is time, otherwise why the hell are physicists talking about spacetime if there is an actual separate dimension of time??? For me, before the big bang, spacetime was already there.

Hi Don, what happens to the CMB? Will it be different for observers in galaxies and for observers in space? Does it go just fainter or the wavelength icreases to infinity?

@drdon5205

3 жыл бұрын

It's the same for everyone, although there is a tiny difference for each galaxy due to their motion WRT the CMB. Long term, it gets fainter and the wavelength gets longer.

Could there be something outside the visible leading to the accelerated expansion of universe. Maybe like the gravity from non visible universe?

@aarav_sharma

3 жыл бұрын

I will put my bet on universe sized black hole...... but it is highly unlikely because the expansion is same in every direction and speed depends on the emptiness of the space also it cannot explain the ever increasing acceleration

Dr. Don. Is the escape velocity from a singularity actually infinite, or is it a figure that just happens to be faster than the speed of light?

9:50 Is there a kind of space elasticity? The mass curves the space, but which force/thing relaxes it after being bent?

@cloudpoint0

3 жыл бұрын

You can use space elasticity as a metaphor but it is really the coordinates of universe’s gravitation field that curve when there is mass present and then relax when the mass is gone while space does nothing and is nothing.

@MilosMalinic

3 жыл бұрын

​@@cloudpoint0 Then, why are we talking about space instead of gravitation field?

@cloudpoint0

3 жыл бұрын

@@MilosMalinic We are taught that mass warps spacetime, and the curvature of spacetime around mass explains gravity - so that an object in orbit around Earth, for example, is actually going in a straight line through curved spacetime. Mass does not curve just space or curve just time separately, in my understanding. Just spacetime can be curved although the time dimension within spacetime usually does all or most of the curving, away from black holes anyway. Time in spacetime is actually a special kind of spatial dimension, it’s not true time (it is even shown backwards in spacetime plots). Maybe spacetime should have been called the “joint space-time-gravitation field”. Spacetime really just explains how gravity varies in the presence of uneven distributions of energy, like mass. Spacetime is an imaginary thing, a human idea. It’s like the grid of longitudes and latitudes that we place around the Earth so that we can measure positions of things on Earth. Spacetime is a grid that we place around the universe. The interesting thing about the spacetime grid is we must consider it to be warped or curved in places for gravitational pulls (straight line paths) to work out in the way that we observe them to behave in the real world. There is no force doing this to the grid. Nothing is varying - the grid is static (there’s no true time dimension to let it vary). It’s just the way the geometry needs to work to be correct.

Can Dark Mater interaction with gravity be related to the Many-Worlds interpretation? IE: There is more "stuff" that we can see because gravity extends to multiple dimensions and worlds, bending to conform with everything it interacts with?

Hi Dr. Lincoln, Is it true that at the distance of the Schwarzshild radius from the center of a black hole the passage of time is "still" compared to ours?

Is there any difference between redshift caused by relative motion and redshift caused by the expansion of space-time?

We can observe all other endings of the Universe happening gradually except the phase transition ending when the entire fabric of the Universe ( space time) is torn apart almost instantaneously ! One moment everything exists, the next moment nothing exists !

Hello Dr Lincoln, A question about dark energy in small volumes: I think I understand that dark energy is weaker than gravity to have a net impact in small volumes such as the solar system or even the galaxy. However, is there a way measure the gross expansionary impact of dark energy in small volumes?

Somebody is clapping at 1:40. Is Don in trouble? Did he forget to take out the trash?

Are there currently any experiments that are attempting to "find" the graviton? If so, how likely are they to succeed?

Although they wouldn't have a particular reason to search for them, will far future astronomers have other sources of indirect evidence that other galaxies once existed? If we apply similar methods to the universe we see today, does anything interesting happen (such as giving information about things which may once have been near but then inflated beyond that which will ever be visible way back at the very beginning of time)?

Hello, how do we know the "current" rate of the Universe's expansion, given that for objects further away, we are looking back further in time?

Could you comment on the Roger Penrose's proposal, that in the end of the universe there will be the same conditions as there were in the beginning (Big Bang), and thus everything might re-start ?

Is strange matter the optimal state of matter? Could a blob of strange matter keep from decaying into other particles if it were concentrated enough?

So, if H0= 70 km/s / megaparsec = 2.268529*10^(-18) Hz (Hertz) = 2.268529*10^(-18) sec^(-1) then the universe stretches at dimensionless ratio or factor of 1 + 2.268529*10^(-18) each second. So, if X0 is the original length of a piece of space, then at time, t, seconds later, this piece of space will have length X(t) = X0*exp( (1 + 2.268529*10^(-18))*t). From this video, I infer the dimensionless expansion ratio is 1 dimensional: length. Not volume. I assume volume, V(t), would go as V(t)=V(0)*exp( 3*(1 + 2.268529*10^(-18))*t)