Mandalore. Thanks for another awesome episode and for using my art in the thumbnail, Fraser, it's an honor! I really appreciated how you captured the feeling of the sad situation, where a federation communicates from orbit with entities living on an inescapable planet. Hopefully, a new system of transport, beyond our current imagination, will become available, and this federation will be able to set them free.
Thankyou so much for explaining the size of the universe again. With your help along with Paul Sutter I finally get it. At last it makes some sense to me. It just goes to show we are never too old to learn something new. I am only 77 by the way and I still want to know how and why this universe got started in the first place. Keep up the great work you are doing in providing others like myself with so much interesting and fascinating information.
Vote: ALERAAH. An excellent question! It's indeed true that the restricted 3-body problem (with one mass negligible compared to the others) doesn't have an _analytic_ solution: the only provable analytic solution is Euler-Lagrange with the 5 stationary points, and stable orbits exist only at L₄ and L₅ of the binary, aren't figure-8 (F8). It's unknown, AFAIK, whether or not a numeric solution exists. Considering the Roche potential of the binary, it's easy to spot an equipotential F8 orbit passing through L₁, but it is indeed unstable. It should be noted that a stable _one-period_ F8 orbit, or “free-return orbit,” has been used by the Apollo missions. Without a Moon orbital insertion burn, the free orbit closes back at the Earth after self-intersecting near the Moon. I don't know if the solution can be extended further (assuming exactly circular Moon orbit, for example), but I suspect that it can't It is remarkable, however, that a stable F8 orbit exists for 3 equal mass bodies (Chenciner and Montgomery 2000, ArXiv math/0011268), KAM-stability proof (Simó 2002, MR1884902), linear, stronger stability proofs by (Moore and Nauenberg 2006, ArXiv math/0511219), (Roberts 2007, DOI-10.1017/S0143385707000284) show that the solution remain stable within a certain mass difference margin. Animation: ua-cam.com/users/shortsNifhFOPk7h8. In fact, Simó found multiple regular KAM-stable solution of n-body problems, called “choreography solutions.” This is a whole area of research in chaotic dynamics. For example, a 3D solution for a “corkscrew orbit“ _(not_ F8!) of the restricted problem has been found (Oks 2015, DOI-10.1088/0004-637X/804/2/106, corr. in DOI-10.3847/0004-637X/823/1/69).
Hi Fraser! Your newsletter is so rich that I'm almost afraid to open it every week as I may not get a single other thing done that week if I do! You do FANTASTIC work. Just wondering whether questions are limited to those with a financial subscription, or whether anyone can submit one? Assuming the latter, I have two probably pretty lame ones: a) you know how when you look at a star, you're seeing the light as it was when it began its journey from that star and when you see it, it's that light finally hitting your eyeball on Earth however many light years later? I get that part, but what wrecks my head is that if you look at the same star the next night, why is more light coming? I mean surely its light hit your eye the previous evening, so game over? (This is kinda like the question I used to ask my parents as a kid: ie, if the Earth turns around during the night, how come our house isn't on the other side of the street in the morning?! My parents patiently explained that it was because the WHOLE PLANET turned around, not just our street, but as a kid I just couldn't grasp this) b) You know how the atoms in your right hand may have originated in a different supernova than the ones in your left? How does the fact that you're built from your mother and father's DNA affect this? This is another primary school level question, I know, so apologies for the overall lameness, but I can't get my head around that either! I think it's wondrous that we are made of materials blown off by stars at the end of their life cycle, but can't separate out the atoms coming direct from stars into either of my hands, from the atoms coming from your parents' combined DNA, if you see what I'm getting at? Again, if Qs are just for paying subscribers, I understand, but that wasn't clear from your EXCELLENT presentation above. Regards Katherine
If the universe is finite but non-spherical and instead a torus then this 'wrap-around' concept takes on a whole new meaning. A torus is kinda like a sphere multiplied by another sphere and gives rise to multiple radii within in, not all of which will cycle back around to where they began - at least not on a single cycle or period.
Q: Why do all the systems ( planets and galaxies ) rotate? Q; Do all systems rotate in the same direction? Q: Where does that energy come from? Q: Is the universe trying to balance E =E or G=G ? Q ; What percent clockwise & percent counter C.? Thank you
Hey Fraser, what do you think? Should scientific educators on social media and YT make an effort (quasi an oath) of always making a distinction between the Universe and the Observable Universe? I’ve seen many renowned content creators using Universe when they were clearly talking about the OU.
Coruscant! Wow, what a great answer! I could never wrap my head around this question until now. I didn't even know how to ask it. Thanks for taking that one on!
Hey Fraser is there any connection between the physical phenomena where for example they take the T shape spanner in the ISS and spin it, and it flips direction by itself, and the magnetic pole shift ?
Ok, I know I have heard you explain the CMB a few times, but today was the lightbulb moment. Maybe it was because of the way the question was phrased. Thanks and keep making these! [Coruscant]
2nd It is of utmost importance to distinguish what "type" of mag sail you are talking about...there are four "types": 1st is the Mag Sail by Zubrin and Andrews 2nd is the electric mag sail by Janhunnan 3rd is the Winglee static dipole bubble sail. (not considered viable) 4th is The Plasma Magnet John Slough NIAC phase I and II U of W.
Naboo is a fantastic question. Exoplanet studies is my fav subject right now, besides using gravitational lensing as a telescope! Tolliman mission is really exciting too.
@@LarryBonson I don't mean the theory itself. I mean that if the universe is infitite now it must have been infinite forever, even at the big bang. Nobody gets that right, everybody says it was a point. The "observable Universe" was small point but the whole universe was infinite. You cant jump from a point to infinite.
Your description of curious properties of this finite universe pretty much matches what would expect to experience if we existed on the event horizon of an ultra massive black hole.
I have a question about the CMB. If CMB represents a moment in time when the atoms separated enough for light to travel long distances, how long did this 'moment' last? After all, we have been observing the CMB for decades now.
Mustafa. E, E, Doc Smith wrote a series (mid 70s to mid 80s) called 'Family d'Alembert'. The main characters were human but born and raised on a high gravity planet. One of of my favourite series in SciFi.
Question: From my understanding the higgs boson does something (possibly creates a field) that gives everything its mass. If it decays in less than a fraction of a second, how can it do anything?
Hey Frasier! I like to explain the grapefruit size universe question like this. The part of the universe we can see (observe) once occupied a minute size... imagine the earth suddenly went through the same kind of expansion, Delaware would eventually be the size of the observable universe... obviously, earth and the solar system or even our galaxy was considerably larger than Delaware, but it would be outside the viewable space to that future observer.
Hey Fraser, great show as always. Question for you... has there been, or are there any planned, earth orbital stations that uses a polar or sun synchronous orbit? All of them so far are equatorial with varying degrees of inclination based on launch location (40-50 degrees for all of the ones I can think of like Mir, Skylab, ISS, Tiangong). A sun synchronous orbit would have some power and observation benefits wouldn't they?
Dagobah is for sure my favorite for this episode! We already have gravitational wave astronomy but it's still a newborn field basically, and the idea explored here will probably be in the center of developments in it in the future. Maybe very far in the future, but still.
Could you use the measurement of the gradual Red Shift of the CMB to get a clue as to the size of our universe? You would have to adjust for travel time and all, but if the CMB comes from the “Edge” of creation, the rate of redshift might give us some clues to extrapolate our current “size”.
I'm trying to understand what you mean about the size of the Universe just after the big bang. Previously I had pictured the Universe as only the size of a orange, just after the big bang; and then there was inflation which expanded the universe faster than light. To me the faster than light expansion seemed to explain why some of the Universe is currently not observable. So does your explanation include inflation as well? Are you saying that the universe essentially already existed before the big bang? And that the universe may have been empty before the big bang, which filled it with matter and energy? (In the observable portion).
As above so below. If the quantum wave turns to a particle when observed and comes into reality from superposition. is there an observing making the universe arrive from superposition?
I’m not a scientist so I hope you don’t find my explanation to my question too rudimentary. I was watching a show on Space-time & how gravity curves this space-time making space-time go slightly slower towards the centre of the mass of an object. I also remember hearing somewhere that gravity isn’t a force that is easily explained. My question is, could gravity simply be the curving of space-time simply pushing objects towards the centre of each other’s mass rather than an attraction of two objects towards one another? Which raises another question, is a black hole so massive that not only light cannot escape but space-time itself? Is a black hole so massive that time no longer moves forward? Does my question make sense?
As a thought experiment/question, what are the chances that black holes may not even be “holes” at all. What if the matter/object is just so dense that it doesn’t allow light to escape it’s gravitational influence, and that behind the event horizon is just an incredibly dense physical object?
Recently, plasma science has lately come into my purview and, being an electronics engineer myself, I'm blown away by the special rules that plasma obeys (electromagnetism, double-layers, dark-, glow-, and arc modes, z-pinches, etc.). But I have been shocked at how astophysics articles hardly (if ever) mention any of these things. Yet at first glance, plasma and electromagnetism seem to be good candidates for considering of possibly playing a major role in forming the massive structures we can observe in space and some of the electrical activity that occurs. And knowing electromagnetism is 1000 trillion trillion trillion times (10^39) more powerful than gravity, do you see plasma science coming into or being more and more included in astronomy and cosmology in the future? Like, maybe gravity & plasma together to help explain some of the mysteries and anomalous observations? (I'm so new at plasma, I'm not even sure I'm asking the right questions). Anyway, I'm a huge fan of Universe Today and you! Thanks for all you do!
How did you miss the word “minimum” so many times? Alternatively, how do you define “observable universe” that gives you a different answer for size of the observable universe? Hella hubris
Love show! Here's a Therory! A singularity in a Donut! A VAST Universe with a blender singularity in the middle. Goes in one end and recreated on the other. Explains alot........ Thus the Donut none stop sound of creation. And or destruction.... Norcal...
The universe was always infinite in size, just not always infinite in density. Remember Space and Time are inextricable aspects of the same thing, so space can't expand or time pass in isolation of the other. I think the problem is this requires an infinite amount of imagination to grasp.
Hay again Fraser are "the escape velocity of a black hole bigger then the speed of light" and "space around a black hole is curved back on itself" the same?
Mustafar is definitely my favorite subject! Re: Naboo. Shouldn't we call the "habitable zone" the "liquid water zone," instead? Because what would sometimes be considered uninhabitable could, through something like Enceladus does, have liquid water. As for Bespin, thank you for clarifying that, since many seem not to understand it. But... "flippening?" 😂😂 That's a technical term, right? 😂😂 Thanks, Fraser, for all you do! ❤❤
Thanks Fraser! To me it seems the dense hot early universe was like a state of matter that went through a phase change, sort of like water, that expands many many times when it changes state to a gas. How that happened everywhere at once I don't know, but maybe a foam of bubbles formed formed first during "inflation", they all expanded in size until they crashed into each other leaving filaments of residue left over? Maybe gravitational wave detectors could be used to look for these bubble collisions? I'm so psyched you addressed my question!
Question I would love to know if body fluids and gases as an astronauts can impact your motion in zero g environment? Could you blow hard enough to spin 360 backflip for example or even blood pumping in your heart effect motion?
But then what was the significance of the Big Bang if there was always more Universe further then the observable Universe? It is also often said that the time itself was created in the Big Bang, so there is no point to ask what was before it as there was no before. If there was always more Universe, then the time was not created?
CMB, what if you took an image at the CMB wavelength then another image at a fractionally shorter wavelength and repeat. You would end up with a video, what would this video show?
The singularity that created our universe must have been like a black hole, could it be processes going on in black holes, only extremely slowly? So the black holes we see is actually "exploding" like the big bang did, only very slowly?
Kind of both. If you mash matter and energy so closely you'll get an escape velocity that is higher than the speed of light. It's like a star that you can't see because even the light can't get away.
the cosmic horizon is, i believe exactly what we would see if we were in s black hole, but that doesn't mean we are in one. the universe, however is mathematical singularity like a black holeis a singularity; a place where the msths stops working; matt o'dowd has done videos on these topics and concepts if you have time to dig through the PBS spacetime catalog.that's a lot of ground/space to cover, though; there's a good chance i got specific wording wrong, so my question for next QA is, are you able to clarify, raiser?
My simple minded question based on the first viewer question is this: If the universe at one time was the size tiny the size of a grapefruit, what is on the outside of the grapefruit? If the universe keep growing and expanding in volume it is pushing forth into whatever is on the other side of that grapefruit. When does whatever is on the other side of the grapefruit exert force and push back onto the universe?
[Tatooine] Atoms are shrinking and the speed of light is slowing down. If you take two points in the early universe and scale it to the current two points you get a view that subtracts out the expansion. This visualization makes it easier to see how the universe energy turns into matter and the matter condenses. The "Shrinking" theory is not useful from the science point of view since it does not make any different predictions, but it is a way to think about expansion.
Bespin. Is there any evidence of how much the magnetic pole axis changes when it flips? The north pole is wondering at an historically high rate recently. I assume the south pole is too, but i never hear about that. I assume even large movements, while still relatively close to the planet rotation axis, aren't enough of a change to show up in new lava cooling. (Any slight change in orientation of the locked-in magnetic field would be demoted by slight rotations of the cooled lava.) After a flip in the Atlantic rift lava, can we tell how far a new south pole was from the previous north pole?
The universe must be infinite. It's possible that our physical universe is "contained" in some way, but there must be something infinite beyond that. Nothing else would make any sense.
In the digital world it's an infinite universe. There is never a border as you can always go through it or know what's beyond it even if it crashes you know it extends forever. The only limit is te numbers that can be inputed to some extent. But it's still infinite. So the real world must be infinite too
@@soaringstars314 My reasoning is simply that "absolute nothing" cannot exist in a universe with something/anything in it. It's a binary choice. It's 0 or 1, and our universe is clearly a 1. "Nothing" means no possibilities, and that includes the possibility of something arising out of that nothingness.
Could we observe the light from stars/galaxies behind a black-hole merge rippling during the merge if we had a telescope aimed at the right spot at the right time? If not with current technology, how much better would our telescopes need to be?
Could FRBs be us listening to the tidal friction between two large masses like magnetars close to colliding? Similar to the high pitched noise we hear when placing pressure and dragging our fingers along something like a glass surface? By the time they reach us could something like that be perceived in radio frequencies?
@@MCsCreations the hole point about asteroid mining is, that their are a lot of asteroid, that are qutie close to earth orbit. (in terms of deltaV) so bringing mass from Asteroids is in a way easier, than from earth. The viability of asteroid mining pretty much stops for asteroids that are further away, than the surface of the moon. because if you need actually that much mass, you might as well start mining there. So why the hell would you mine comets?
If the underlying fabric of spacetime is maleable but we still live in a minkowski R4(x,y,z,t) universe how could one measure the strain on R2(d',d'') sub-universal envoloping dimensions?
What can gravitational wave astronomy tell us about the universe that light can't, given that both light and gravitational waves travel at the same speed? What are some examples of things we expect to find out? Also, are gravitational waves slowed down by passing through matter? Thanks! 👋
For the sake of this question, we are going to ignore the effects of direct gravitational attraction, radiation , magnetism and spaghettification. If one were to do a space walk within 100 miles of a soon to be merging pair of neutron stars or black holes, what would the effect of being that close to a powerful source of gravity waves? Would it shake you around? Would it tear you apart? Would you even notice? I've wondered this ever since they were first detected.
@@frasercain Ah! That's answered a few questions. Not sure I can fully comprehend everything but I think I have an answer to my confusion about infinitely dense. Thanks!
Tattooine -- I asked Paul Sutter this exact question and he very politely showed me how wrong my premise was. And then he ate cheese. Please invite him [back] to your channel!
A simulated reality is interesting in that if you were to simulate a reality within the simulated reality the energy required for the second simulation is already within the first simulation. This implies that the second simulation was known before the first simulation was created. Does this mean the idea is impossible or does this indicate 'chronodelocalization'?
It seems to me that the cost per unit mass to get fuel into space has a limit beyond which a heavier payload becomes more expensive. Is there is a reusable fuel system where the spent fuel is saved and can be regenerated using a process that requires a minimal additional mass to be transported from Earth?
Question: Some time ago there was a Falcon 9 of which the hydraulics were broken and couldn't steer with it's grid fins but it somehow managed to make a good landing in the water because the control system started compensating with the RCS thrusters. My question is, with a control system like the Falcon 9 has, does it matter for the space craft where it lands? I mean, could it land on Mars or the moon without modification?
Thank you Fraser, I love the question and answer show. By the way, the Universe is so infinite that it goes beyond my brain. Keep up the great stuff, Is always off the hook!!!!!! 6:05
Fraiser, I watch your question & answer videos all the time. They are informative and always interesting, keep up the good work. I have a question about the solar panels used on the Mars rovers. They slowly collect dust until they become nonfunctional. Has anyone considered a way of cleaning them? Maybe a wiper, rotate the panel then vibrate it or a static pulse of some sort. Thanks.
Regarding the first question: What really made the idea of the "grapefruit --> infinite in a Planck moment" idea click for me was seeing approx. 5 seconds some B-roll footage from another other science channel here on UA-cam... And i wish I knew where to find it to show you so I'll have to explain it instead... Let's start with a ruler (📏) with equal markings all the way down - we can use millimeters but the units are arbitrary. Now imagine it goes from 0 to infinity. Now, let's pretend we had a dial/slider to change the spacing between of each of these infinite markings. We could set the (equal) spacing to one Planck unit, one grapefruit, one meter, 10km, 1 million miles, 100 AU, etc. The smaller your spacing, the more dense the markings on the ruler will be, and vice versa. Now, if you haven't already, imagine (visually) what would happen if you set the spacing to 0.... All of the infinite marks would all be in the same spot. "0" looks different than any other number and looks point-like whereas any other number is positive, resulting in infinite length. Play with the idea. We were using a ruler which was 1D and counted from 0 to infinity, however, the "grapefruit to infinity" would happen from an origin point and go in 3-dimensions, akin to a sun radiating. I hope that made it click for at least one person.😅
Hello Fraser, consider that a Jupiter-like gaseous planet is spewed out of your solar system. How long until he becomes a giant ball of "ice" drifting through deep space?
What does "size" mean in the context of the universe? By what ruler is it measured?... the speed of light? If so, maybe the universe hasn't changed size. Maybe another way of looking at it is the speed of light decreasing instead of space changing size.
Hey Fraser, I have question which is, Big Bang happened 13.8 Billion years ago, How come we see 46 billion light years away on each side? And may be during observing universe can we miss seeing some Galaxies which are dim and destroyed?
Tatooine. As I understand it, the laws of physics must have been very different at the time of the big bang, because to have all of that mass in the same place under our physics would inevitably result in a supermassive black hole with all of the universe's mass inside of it. What are the best theories around when the change in physical laws happened during the big bang and why did they change?
I have a question. We all know that the Universe is expanding, but some astronomers still think the expansion may one day stop and the Universe may start contracting. If that were to happen, what would be the first signs that the Universe had begun contracting?
Is it possible… Black holes have infinite mass and infinite density. Observibly though they occupy a finite location in space. Could it be that mass breaks down at a level we haven’t even been able to measure yet? If so, doesn’t that sound like the perfect enviroment for a big bang?
Only you can answer that question. The universe itself by itself doesn't have an inherent meaning. However, your life can very well have a meaning, but that meaning is personal. Live, enjoy life, and find your very personal meaning :)
@@fabzter - questions like this, "meaning" are like who created god, what is outside the universe, etc etc etc, it never ends, questions that only produce new questions
Mandalore: That question also states another fact. Can there be a planet where the escape velocity is so big that life on that planet could never leave the planet ? That also means there are planets where we shouldn't go, because we couldn't return.
You have stated in the far future, observers will not be able to see anything beyond the local group. The rest of the once observable universe will be beyond observation due to expansion of the universe. So, have we seen anything disappear due to expansion, never to be seen again?
@@ikariameriks Yes, but the universe is expanding faster than the speed of light. Meaning things that are observable now, at the edges of the observable universe will someday disappear. Universe Today has done an episode on this. Just asking for clarification.
At which point would we be able to tell the difference between our Universe simulation models having the wrong physics versus not matching observations due to large-scale influence of alien civilizations?
Seems like communication to earth from an interstellar probe would be problematic eventually. Would it make sense to send a relay probe every few years or so to relay the leading probe’s data?
How do they keep track of all the wiring, pipes, always adding experiments to panels. So many manuals on procedures involving more than 1 set of systems on the iss. Looks like a spider web of stuff all over the walls. Thanks
If the CMB was once high energetic / high frequency radiation and then got “streched” to today’s microwave frequency, there must have been a time when it passed through wavelengths of the visible spectrum. Was the light intensity at this time high enough that the background of space was blue, green, and then red insted of black? Or was the intensity already so low that we could not have detected this light with our eyes?
The CMB started out as a hot 'orange' glow of about 2700 Kelvin (like a hot piece of metal, or the hot surface of a small star), 380,000 years after the big bang.
Mangalore. But gravity isn’t the only problem. You said clouds on Venus are so thick it like molasses or treacle. Assuming Earth temperature, but Venus atmosphere - would this make it impossible to take off into space? How much extra atmosphere makes it impossible to leave a planet?
Best channels: Fraser Cain, SEA, PBS Spacetime, and SFIA. Those are my 'go to' favs.
Mandalore. Thanks for another awesome episode and for using my art in the thumbnail, Fraser, it's an honor! I really appreciated how you captured the feeling of the sad situation, where a federation communicates from orbit with entities living on an inescapable planet. Hopefully, a new system of transport, beyond our current imagination, will become available, and this federation will be able to set them free.
Fraser I really loved your explanation of the infinite universe being beyond the observable universe. I understand this now! Thanks!!
Yeah. Fraser gets it. Was a good answer.
So that means before the big bang when the universe was infinitely small, there was another universe around it? Naboo.
I didn’t catch which planet was the question identifier, but…
I just loved that word, “flippening” 😂
Me too 17:25 in the Bespin Chapter. Interesting that the Closed Captions changed it to "flipping".
Thankyou so much for explaining the size of the universe again. With your help along with Paul Sutter I finally get it. At last it makes some sense to me. It just goes to show we are never too old to learn something new. I am only 77 by the way and I still want to know how and why this universe got started in the first place. Keep up the great work you are doing in providing others like myself with so much interesting and fascinating information.
Vote: ALERAAH. An excellent question!
It's indeed true that the restricted 3-body problem (with one mass negligible compared to the others) doesn't have an _analytic_ solution: the only provable analytic solution is Euler-Lagrange with the 5 stationary points, and stable orbits exist only at L₄ and L₅ of the binary, aren't figure-8 (F8). It's unknown, AFAIK, whether or not a numeric solution exists. Considering the Roche potential of the binary, it's easy to spot an equipotential F8 orbit passing through L₁, but it is indeed unstable.
It should be noted that a stable _one-period_ F8 orbit, or “free-return orbit,” has been used by the Apollo missions. Without a Moon orbital insertion burn, the free orbit closes back at the Earth after self-intersecting near the Moon. I don't know if the solution can be extended further (assuming exactly circular Moon orbit, for example), but I suspect that it can't
It is remarkable, however, that a stable F8 orbit exists for 3 equal mass bodies (Chenciner and Montgomery 2000, ArXiv math/0011268), KAM-stability proof (Simó 2002, MR1884902), linear, stronger stability proofs by (Moore and Nauenberg 2006, ArXiv math/0511219), (Roberts 2007, DOI-10.1017/S0143385707000284) show that the solution remain stable within a certain mass difference margin. Animation: ua-cam.com/users/shortsNifhFOPk7h8. In fact, Simó found multiple regular KAM-stable solution of n-body problems, called “choreography solutions.”
This is a whole area of research in chaotic dynamics. For example, a 3D solution for a “corkscrew orbit“ _(not_ F8!) of the restricted problem has been found (Oks 2015, DOI-10.1088/0004-637X/804/2/106, corr. in DOI-10.3847/0004-637X/823/1/69).
Hi Fraser! Your newsletter is so rich that I'm almost afraid to open it every week as I may not get a single other thing done that week if I do! You do FANTASTIC work.
Just wondering whether questions are limited to those with a financial subscription, or whether anyone can submit one? Assuming the latter, I have two probably pretty lame ones:
a) you know how when you look at a star, you're seeing the light as it was when it began its journey from that star and when you see it, it's that light finally hitting your eyeball on Earth however many light years later? I get that part, but what wrecks my head is that if you look at the same star the next night, why is more light coming? I mean surely its light hit your eye the previous evening, so game over? (This is kinda like the question I used to ask my parents as a kid: ie, if the Earth turns around during the night, how come our house isn't on the other side of the street in the morning?! My parents patiently explained that it was because the WHOLE PLANET turned around, not just our street, but as a kid I just couldn't grasp this)
b) You know how the atoms in your right hand may have originated in a different supernova than the ones in your left? How does the fact that you're built from your mother and father's DNA affect this? This is another primary school level question, I know, so apologies for the overall lameness, but I can't get my head around that either! I think it's wondrous that we are made of materials blown off by stars at the end of their life cycle, but can't separate out the atoms coming direct from stars into either of my hands, from the atoms coming from your parents' combined DNA, if you see what I'm getting at?
Again, if Qs are just for paying subscribers, I understand, but that wasn't clear from your EXCELLENT presentation above.
Regards
Katherine
Mandalor. Really interesting question and I enjoyed your answer. I typically listen on the podcast so never find the chance to vote.
Question:
Are there any finite non-wrapping geometries possible for the universe?
Your question leaves me flat.
If the universe is finite but non-spherical and instead a torus then this 'wrap-around' concept takes on a whole new meaning. A torus is kinda like a sphere multiplied by another sphere and gives rise to multiple radii within in, not all of which will cycle back around to where they began - at least not on a single cycle or period.
Q: Why do all the systems ( planets and galaxies ) rotate?
Q; Do all systems rotate in the same direction?
Q: Where does that energy come from?
Q: Is the universe trying to balance E =E or G=G ?
Q ; What percent clockwise & percent counter C.?
Thank you
That is such a great idea by using key words to short hand what chapter you liked the most. I can see other creators using that
Hey Fraser, what do you think? Should scientific educators on social media and YT make an effort (quasi an oath) of always making a distinction between the Universe and the Observable Universe? I’ve seen many renowned content creators using Universe when they were clearly talking about the OU.
Mustafar!
Thanks a bunch for all the answers, Fraser! 😊
Stay safe there with your family! 🖖😊
Coruscant! Wow, what a great answer! I could never wrap my head around this question until now. I didn't even know how to ask it. Thanks for taking that one on!
Hey Fraser
is there any connection between the physical phenomena where for example they take the T shape spanner in the ISS and spin it, and it flips direction by itself,
and the magnetic pole shift ?
Ok, I know I have heard you explain the CMB a few times, but today was the lightbulb moment. Maybe it was because of the way the question was phrased. Thanks and keep making these!
[Coruscant]
2nd It is of utmost importance to distinguish what "type" of mag sail you are talking about...there are four "types":
1st is the Mag Sail by Zubrin and Andrews
2nd is the electric mag sail by Janhunnan
3rd is the Winglee static dipole bubble sail. (not considered viable)
4th is The Plasma Magnet John Slough NIAC phase I and II U of W.
Naboo is a fantastic question. Exoplanet studies is my fav subject right now, besides using gravitational lensing as a telescope! Tolliman mission is really exciting too.
First UA-cam Blogger who gets that Big Bang thing right 👍
How do you get a theory right without conformation.
@@LarryBonson I don't mean the theory itself. I mean that if the universe is infitite now it must have been infinite forever, even at the big bang. Nobody gets that right, everybody says it was a point. The "observable Universe" was small point but the whole universe was infinite. You cant jump from a point to infinite.
Your description of curious properties of this finite universe pretty much matches what would expect to experience if we existed on the event horizon of an ultra massive black hole.
I have a question about the CMB. If CMB represents a moment in time when the atoms separated enough for light to travel long distances, how long did this 'moment' last? After all, we have been observing the CMB for decades now.
Mustafa. E, E, Doc Smith wrote a series (mid 70s to mid 80s) called 'Family d'Alembert'. The main characters were human but born and raised on a high gravity planet. One of of my favourite series in SciFi.
Question: From my understanding the higgs boson does something (possibly creates a field) that gives everything its mass. If it decays in less than a fraction of a second, how can it do anything?
Hey Frasier! I like to explain the grapefruit size universe question like this.
The part of the universe we can see (observe) once occupied a minute size... imagine the earth suddenly went through the same kind of expansion, Delaware would eventually be the size of the observable universe... obviously, earth and the solar system or even our galaxy was considerably larger than Delaware, but it would be outside the viewable space to that future observer.
Hey Fraser, great show as always. Question for you... has there been, or are there any planned, earth orbital stations that uses a polar or sun synchronous orbit? All of them so far are equatorial with varying degrees of inclination based on launch location (40-50 degrees for all of the ones I can think of like Mir, Skylab, ISS, Tiangong). A sun synchronous orbit would have some power and observation benefits wouldn't they?
Strong explanations this week Fraser. Keep eating those Wheaties!
Thanks!
Dagobah is for sure my favorite for this episode! We already have gravitational wave astronomy but it's still a newborn field basically, and the idea explored here will probably be in the center of developments in it in the future. Maybe very far in the future, but still.
Could you use the measurement of the gradual Red Shift of the CMB to get a clue as to the size of our universe? You would have to adjust for travel time and all, but if the CMB comes from the “Edge” of creation, the rate of redshift might give us some clues to extrapolate our current “size”.
I'm trying to understand what you mean about the size of the Universe just after the big bang. Previously I had pictured the Universe as only the size of a orange, just after the big bang; and then there was inflation which expanded the universe faster than light. To me the faster than light expansion seemed to explain why some of the Universe is currently not observable. So does your explanation include inflation as well? Are you saying that the universe essentially already existed before the big bang? And that the universe may have been empty before the big bang, which filled it with matter and energy? (In the observable portion).
As above so below. If the quantum wave turns to a particle when observed and comes into reality from superposition. is there an observing making the universe arrive from superposition?
I’m not a scientist so I hope you don’t find my explanation to my question too rudimentary.
I was watching a show on Space-time & how gravity curves this space-time making space-time go slightly slower towards the centre of the mass of an object. I also remember hearing somewhere that gravity isn’t a force that is easily explained. My question is, could gravity simply be the curving of space-time simply pushing objects towards the centre of each other’s mass rather than an attraction of two objects towards one another? Which raises another question, is a black hole so massive that not only light cannot escape but space-time itself? Is a black hole so massive that time no longer moves forward? Does my question make sense?
As a thought experiment/question, what are the chances that black holes may not even be “holes” at all. What if the matter/object is just so dense that it doesn’t allow light to escape it’s gravitational influence, and that behind the event horizon is just an incredibly dense physical object?
I have a question: What is that background music? It's so relaxing.
Thanks! Just bought the book. His Mars series was great! Your review promises more greatness to come!
Recently, plasma science has lately come into my purview and, being an electronics engineer myself, I'm blown away by the special rules that plasma obeys (electromagnetism, double-layers, dark-, glow-, and arc modes, z-pinches, etc.). But I have been shocked at how astophysics articles hardly (if ever) mention any of these things. Yet at first glance, plasma and electromagnetism seem to be good candidates for considering of possibly playing a major role in forming the massive structures we can observe in space and some of the electrical activity that occurs. And knowing electromagnetism is 1000 trillion trillion trillion times (10^39) more powerful than gravity, do you see plasma science coming into or being more and more included in astronomy and cosmology in the future? Like, maybe gravity & plasma together to help explain some of the mysteries and anomalous observations? (I'm so new at plasma, I'm not even sure I'm asking the right questions). Anyway, I'm a huge fan of Universe Today and you! Thanks for all you do!
Love your videos and I have a refueling question. How do they refuel the space station?
Thanks for all you do!
Nice video.
Question: Why does Venus spin so slowly on its axis, especially compared to all the other planets?
Fav Q&A Mandalor
Very thought provoking - Good demonstration of the Rocket equation...
It truly stumps me to try to figure out how mankind truly thinks we know the size limit of the universe.
Keep trying, you'll get it
How did you miss the word “minimum” so many times? Alternatively, how do you define “observable universe” that gives you a different answer for size of the observable universe?
Hella hubris
Tatooine | Thank you for your great videos!
Love show! Here's a Therory! A singularity in a Donut! A VAST Universe with a blender singularity in the middle. Goes in one end and recreated on the other. Explains alot........
Thus the Donut none stop sound of creation. And or destruction....
Norcal...
Yep... horn torus... dark energy and spacetime squishing in and out
The universe was always infinite in size, just not always infinite in density. Remember Space and Time are inextricable aspects of the same thing, so space can't expand or time pass in isolation of the other. I think the problem is this requires an infinite amount of imagination to grasp.
Agreed, its just a shell game
Hay again Fraser
are "the escape velocity of a black hole bigger then the speed of light" and "space around a black hole is curved back on itself" the same?
While watching I had the exact same thought, about the possibility of a planet swapping stars in a figure 8 orbit.
Mustafar is definitely my favorite subject!
Re: Naboo. Shouldn't we call the "habitable zone" the "liquid water zone," instead? Because what would sometimes be considered uninhabitable could, through something like Enceladus does, have liquid water.
As for Bespin, thank you for clarifying that, since many seem not to understand it. But... "flippening?" 😂😂 That's a technical term, right? 😂😂
Thanks, Fraser, for all you do!
❤❤
Thanks Fraser! To me it seems the dense hot early universe was like a state of matter that went through a phase change, sort of like water, that expands many many times when it changes state to a gas. How that happened everywhere at once I don't know, but maybe a foam of bubbles formed formed first during "inflation", they all expanded in size until they crashed into each other leaving filaments of residue left over? Maybe gravitational wave detectors could be used to look for these bubble collisions? I'm so psyched you addressed my question!
Question
I would love to know if body fluids and gases as an astronauts can impact your motion in zero g environment? Could you blow hard enough to spin 360 backflip for example or even blood pumping in your heart effect motion?
But then what was the significance of the Big Bang if there was always more Universe further then the observable Universe? It is also often said that the time itself was created in the Big Bang, so there is no point to ask what was before it as there was no before. If there was always more Universe, then the time was not created?
What percentage of the visible galaxies are duplicates due to spatial lensing? Is it possible to determine?
Hi, my question is about time.
Is there no present?
Do we live in the past, as calculated by an event + speed of light, even a thought is delayed?
CMB, what if you took an image at the CMB wavelength then another image at a fractionally shorter wavelength and repeat. You would end up with a video, what would this video show?
The singularity that created our universe must have been like a black hole, could it be processes going on in black holes, only extremely slowly? So the black holes we see is actually "exploding" like the big bang did, only very slowly?
If a star has so much gravity light can’t escape does that make it a black hole or is that what the black hole is?
Kind of both. If you mash matter and energy so closely you'll get an escape velocity that is higher than the speed of light. It's like a star that you can't see because even the light can't get away.
the cosmic horizon is, i believe exactly what we would see if we were in s black hole, but that doesn't mean we are in one. the universe, however is mathematical singularity like a black holeis a singularity; a place where the msths stops working; matt o'dowd has done videos on these topics and concepts if you have time to dig through the PBS spacetime catalog.that's a lot of ground/space to cover, though; there's a good chance i got specific wording wrong, so my question for next QA is, are you able to clarify, raiser?
Possible Question : How does cold new early dark energy (NEDE) differ from the dark energy we have now, and does it resolve the H0 and S8 tensions?
My simple minded question based on the first viewer question is this: If the universe at one time was the size tiny the size of a grapefruit, what is on the outside of the grapefruit? If the universe keep growing and expanding in volume it is pushing forth into whatever is on the other side of that grapefruit. When does whatever is on the other side of the grapefruit exert force and push back onto the universe?
Is dark energy in empty space only? How does some space know to expand while other space knows not to? Or so it seems, right?
[Tatooine] Atoms are shrinking and the speed of light is slowing down. If you take two points in the early universe and scale it to the current two points you get a view that subtracts out the expansion. This visualization makes it easier to see how the universe energy turns into matter and the matter condenses. The "Shrinking" theory is not useful from the science point of view since it does not make any different predictions, but it is a way to think about expansion.
Bespin. Is there any evidence of how much the magnetic pole axis changes when it flips? The north pole is wondering at an historically high rate recently. I assume the south pole is too, but i never hear about that. I assume even large movements, while still relatively close to the planet rotation axis, aren't enough of a change to show up in new lava cooling. (Any slight change in orientation of the locked-in magnetic field would be demoted by slight rotations of the cooled lava.) After a flip in the Atlantic rift lava, can we tell how far a new south pole was from the previous north pole?
The universe must be infinite. It's possible that our physical universe is "contained" in some way, but there must be something infinite beyond that. Nothing else would make any sense.
In the digital world it's an infinite universe. There is never a border as you can always go through it or know what's beyond it even if it crashes you know it extends forever. The only limit is te numbers that can be inputed to some extent. But it's still infinite. So the real world must be infinite too
@@soaringstars314 My reasoning is simply that "absolute nothing" cannot exist in a universe with something/anything in it. It's a binary choice. It's 0 or 1, and our universe is clearly a 1.
"Nothing" means no possibilities, and that includes the possibility of something arising out of that nothingness.
@@Jacob-Vivimord ah ok although it can apply to both looped and infinite if that's what you're talking about
Could we observe the light from stars/galaxies behind a black-hole merge rippling during the merge if we had a telescope aimed at the right spot at the right time? If not with current technology, how much better would our telescopes need to be?
Could FRBs be us listening to the tidal friction between two large masses like magnetars close to colliding? Similar to the high pitched noise we hear when placing pressure and dragging our fingers along something like a glass surface? By the time they reach us could something like that be perceived in radio frequencies?
Is the ' 3 body problem ' un-solvable ? If not, can multiple body interactions be solved perhaps with quantum computing ?
Just imagine, there must be stars where you were the last human to observe it/them.
Re Mustafar I think for orbital refuelling to really make sense, you need to combine it with asteroid mining.
And comet mining as well.
@@MCsCreations Y do you mock me?
@MusikCassette I'm not! I'm agreeing with you.
@@MCsCreations the hole point about asteroid mining is, that their are a lot of asteroid, that are qutie close to earth orbit. (in terms of deltaV) so bringing mass from Asteroids is in a way easier, than from earth. The viability of asteroid mining pretty much stops for asteroids that are further away, than the surface of the moon. because if you need actually that much mass, you might as well start mining there. So why the hell would you mine comets?
@MusikCassette For fuel. Things like methane. Or even water to brake it into O2 and H2.
Could we repurpose the ISS for refueling? Or is that orbit to low?
If the underlying fabric of spacetime is maleable but we still live in a minkowski R4(x,y,z,t) universe how could one measure the strain on R2(d',d'') sub-universal envoloping dimensions?
What can gravitational wave astronomy tell us about the universe that light can't, given that both light and gravitational waves travel at the same speed? What are some examples of things we expect to find out?
Also, are gravitational waves slowed down by passing through matter? Thanks! 👋
For the sake of this question, we are going to ignore the effects of direct gravitational attraction, radiation , magnetism and spaghettification.
If one were to do a space walk within 100 miles of a soon to be merging pair of neutron stars or black holes, what would the effect of being that close to a powerful source of gravity waves? Would it shake you around? Would it tear you apart? Would you even notice? I've wondered this ever since they were first detected.
Can you link the video where Dr. Sutter explained it to you, please?
Here you go. ua-cam.com/video/x2A4yYeurGk/v-deo.html
@@frasercain You rule! I didn't even see this until today! Thanks, brother.
@@frasercain Ah! That's answered a few questions. Not sure I can fully comprehend everything but I think I have an answer to my confusion about infinitely dense. Thanks!
hi ow likely do you reckon before we discover something big learnt that would change the world ?
Tattooine -- I asked Paul Sutter this exact question and he very politely showed me how wrong my premise was. And then he ate cheese. Please invite him [back] to your channel!
A simulated reality is interesting in that if you were to simulate a reality within the simulated reality the energy required for the second simulation is already within the first simulation.
This implies that the second simulation was known before the first simulation was created. Does this mean the idea is impossible or does this indicate 'chronodelocalization'?
It seems to me that the cost per unit mass to get fuel into space has a limit beyond which a heavier payload becomes more expensive. Is there is a reusable fuel system where the spent fuel is saved and can be regenerated using a process that requires a minimal additional mass to be transported from Earth?
Question: Some time ago there was a Falcon 9 of which the hydraulics were broken and couldn't steer with it's grid fins but it somehow managed to make a good landing in the water because the control system started compensating with the RCS thrusters. My question is, with a control system like the Falcon 9 has, does it matter for the space craft where it lands? I mean, could it land on Mars or the moon without modification?
Is it possible to watch or listen to this without the background music somewhere?
Yes, subscribe to the podcast version.
@@frasercain Thank you, exactly what I needed!
Corellia . Great question and answer!
Question. Could you explain (hot interstellar gas).
Thank you Fraser, I love the question and answer show. By the way, the Universe is so infinite that it goes beyond my brain. Keep up the great stuff, Is always off the hook!!!!!! 6:05
Ministry of the Future was a great listen! Loved it. Going to dig into Red Mars soon.
Fraiser, I watch your question & answer videos all the time. They are informative and always interesting, keep up the good work. I have a question about the solar panels used on the Mars rovers. They slowly collect dust until they become nonfunctional. Has anyone considered a way of cleaning them? Maybe a wiper, rotate the panel then vibrate it or a static pulse of some sort. Thanks.
Regarding the first question:
What really made the idea of the "grapefruit --> infinite in a Planck moment" idea click for me was seeing approx. 5 seconds some B-roll footage from another other science channel here on UA-cam... And i wish I knew where to find it to show you so I'll have to explain it instead...
Let's start with a ruler (📏) with equal markings all the way down - we can use millimeters but the units are arbitrary.
Now imagine it goes from 0 to infinity.
Now, let's pretend we had a dial/slider to change the spacing between of each of these infinite markings. We could set the (equal) spacing to one Planck unit, one grapefruit, one meter, 10km, 1 million miles, 100 AU, etc. The smaller your spacing, the more dense the markings on the ruler will be, and vice versa. Now, if you haven't already, imagine (visually) what would happen if you set the spacing to 0.... All of the infinite marks would all be in the same spot.
"0" looks different than any other number and looks point-like whereas any other number is positive, resulting in infinite length.
Play with the idea.
We were using a ruler which was 1D and counted from 0 to infinity, however, the "grapefruit to infinity" would happen from an origin point and go in 3-dimensions, akin to a sun radiating.
I hope that made it click for at least one person.😅
Hello Fraser, consider that a Jupiter-like gaseous planet is spewed out of your solar system. How long until he becomes a giant ball of "ice" drifting through deep space?
if all materials have a resonance point, does the sum what we call reality have a resonance point to?
What does "size" mean in the context of the universe? By what ruler is it measured?... the speed of light? If so, maybe the universe hasn't changed size. Maybe another way of looking at it is the speed of light decreasing instead of space changing size.
Hey Fraser,
I have question which is, Big Bang happened 13.8 Billion years ago, How come we see 46 billion light years away on each side? And may be during observing universe can we miss seeing some Galaxies which are dim and destroyed?
Tatooine. As I understand it, the laws of physics must have been very different at the time of the big bang, because to have all of that mass in the same place under our physics would inevitably result in a supermassive black hole with all of the universe's mass inside of it. What are the best theories around when the change in physical laws happened during the big bang and why did they change?
I have a question. We all know that the Universe is expanding, but some astronomers still think the expansion may one day stop and the Universe may start contracting. If that were to happen, what would be the first signs that the Universe had begun contracting?
Is it possible… Black holes have infinite mass and infinite density. Observibly though they occupy a finite location in space. Could it be that mass breaks down at a level we haven’t even been able to measure yet? If so, doesn’t that sound like the perfect enviroment for a big bang?
Mandalore! I feel bad for those squished creatures.
Why is detecting gravitational waves important?
I have a question: What’s the meaning of all this? The meaning of existence. That is all thank you 😊
Only you can answer that question. The universe itself by itself doesn't have an inherent meaning. However, your life can very well have a meaning, but that meaning is personal. Live, enjoy life, and find your very personal meaning :)
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Easy, beer, pizza and a relaxing sunday in the garden
@@fabzter - questions like this, "meaning" are like who created god, what is outside the universe, etc etc etc, it never ends, questions that only produce new questions
The meaning of life question can only be answered individually since we all have to find our own purpose 😊.
Mandalore: That question also states another fact. Can there be a planet where the escape velocity is so big that life on that planet could never leave the planet ? That also means there are planets where we shouldn't go, because we couldn't return.
Oh, well. I wrote too early, you already brought up that point. 😀
You have stated in the far future, observers will not be able to see anything beyond the local group. The rest of the once observable universe will be beyond observation due to expansion of the universe. So, have we seen anything disappear due to expansion, never to be seen again?
Not yet. The CMB is the farthest that can be seen... and we can see it.
Our observable universe is still expanding not contracting
@@ikariameriks Yes, but the universe is expanding faster than the speed of light. Meaning things that are observable now, at the edges of the observable universe will someday disappear. Universe Today has done an episode on this. Just asking for clarification.
At which point would we be able to tell the difference between our Universe simulation models having the wrong physics versus not matching observations due to large-scale influence of alien civilizations?
Seems like communication to earth from an interstellar probe would be problematic eventually. Would it make sense to send a relay probe every few years or so to relay the leading probe’s data?
I talked to Avi Loeb about this a few years ago. You just need a really big radio telescope on Earth to detect the signal.
How do they keep track of all the wiring, pipes, always adding experiments to panels. So many manuals on procedures involving more than 1 set of systems on the iss. Looks like a spider web of stuff all over the walls. Thanks
If the CMB was once high energetic / high frequency radiation and then got “streched” to today’s microwave frequency, there must have been a time when it passed through wavelengths of the visible spectrum. Was the light intensity at this time high enough that the background of space was blue, green, and then red insted of black? Or was the intensity already so low that we could not have detected this light with our eyes?
The CMB started out as a hot 'orange' glow of about 2700 Kelvin (like a hot piece of metal, or the hot surface of a small star), 380,000 years after the big bang.
Mangalore. But gravity isn’t the only problem.
You said clouds on Venus are so thick it like molasses or treacle. Assuming Earth temperature, but Venus atmosphere - would this make it impossible to take off into space? How much extra atmosphere makes it impossible to leave a planet?
Thank you Fraser.