17 Subatomic Stories: What happens when you fall into a black hole? 

Just love the fact that all of these "subatomic stories" videos are mostly questions being answered. Really sets them apart from the more lecture-style physics content elsewhere on RU-vid (each has its place, of course).

"One does not simply walk into a Black Hole." -- Boromir

I've watched nearly all of Dr. Don's Subatomic Stories videos and I have to ask...who the hell is thumbing these videos down? I mean are the same people thumbing down each of the videos? Why "dislike" them in the first place? They are incredibly informative, and presented in a way that even non-physicists (like myself) can understand.

Hi Don, could you please do a video about the Planck length, time and energy?

Thanks don! Ive been more able to explain things to my grandparents (we have to keep busy right) when they started asking so many questions when we were watching the comet, because of your videos! I am not a physicist, but thanks to you i can convey the content of your videos to people insufficient confidence with the english language to watch them. Thanks!

I love it when Don uploads

This video shows again why Dr Don's videos are among my favourite sciencetainment videos: They're entertaining and delivering science facts at the same time. The important part is that these science facts are presented in an easily understandable way. Please keep up this great work!

HI DON! we love u -physics fans

Hi Don! You talked about the different observations for an object falling into a black hole. I’ve got a question that has been bugging me for quite some time, and I hope you can illuminate me. It’s kind of long. As commonly described, the distant observer should see the falling object fade to black and almost freeze in time. From this perspective, the object keeps falling forever. However, there is no forever. The black hole evaporates, shrinks over time, and will be gone at some point in the very distant future. I will assume that the falling object is a point with zero size. In theory, the distant observer should be able to see the object throughout the entire time it takes the black hole to evaporate completely, even if it is just a single red-shifted photon every couple of million years. Once the black hole shrinks below a certain size, the proper time of the falling object will speed up again relative to the observer’s time and it’s emitted light shifts out of the red. By the time the black hole is completely gone, the falling point object is again fully visible, and from the observer’s perspective, it never crossed the event horizon. Transforming this worldline to the falling object’s frame of reference should leave this topology intact, so they should agree: the object never fell past the horizon. There are no point objects, of course, but based on the argument above, I would predict the following for a real object falling into a real black hole: 1. As the object’s proper time slows down relative to the distant observer’s time, the Hawking radiation of the black hole is blue-shifted. Just for perspective: at some point, the falling object will experience one second while a million years pass for the distant observer. This means the object will be exposed to one million years worth of Hawking radiation within a single second. 2. As the falling object gets closer to the event horizon, the object will observe that the black hole shrinks away under it. As the black hole gets smaller and smaller, tidal forces become stronger and rip the object apart. 3. The falling object sees the back hole evaporate completely. At that time, the falling object is completely obliterated, fried by insane levels of radiation, and ripped to shreds by tidal forces. 4. The falling object (or the bits and pieces that remain of it) never cross the event horizon. This, of course, is not the story that is typically told of objects falling into black holes. Am I wrong about something? Where’s my mistake? Thanks for reading all of this.

I may have read somewhere that spaghettification could be prevented in the case of a super fast rotating black hole. If that's true, would that have other implications regarding black holes?

Enjoyed the whole video but especially the Q n A portion. Well done and cheers.

First off, I love your videos! I've learned so much already. I was wondering, do gravitational waves experience the same Doppler shift as electromagnetic waves in the vicinity of a black hole?

Speaking of spaghetti-fication, wouldn't there also be a similar effect in time? That is, would someone falling feet-first experience different time at their feet than their head? It seems like this must be so, which leads to more fun phenomenon like the extreme time distortion very near the event horizon blue-shifting the cosmic microwave background radiation to such an extent that it vaporizes any forthcoming human feet.

Hello! How would gravitational waves interact with black hole as they travel in space?

Love this channel Love the questions answers part too

Great video, Dr. Lincoln! I love your presentation style!

Before even watching this I'm going to put my bet on "nothing good".

Q: What happens when you fall into a black hole? A: Spagett!

Hi Don! Can you please make a video about some of experiments you mentioned when talked about special relativity. Thanks

Thanks for answering my question a few videos ago.

Quantum gravity vs gravity waves? Could gravity waves be interpreted as a wave/surge of gravitons?

6:14 Schwarzchild's real pronunciation is *fartsheild?*

Physicists always say "It's never aliens." But in Star Trek DS9, it is. They constructed the wormhole, It is not a black hole. Love your series. THANK YOU

What happens when subatomic particles like electron, or even much fundamental like quark undergoes Spaghettification ? Thanks in advance

Here's a thought experiment for you: Suppose Gravity is not a field or a force, but only curved space-time caused by the mere presence of matter. Would that mean that: Gravity has no energy, but only is a reflection of kinetic energy that is already contained in the particles moving through Gravity? Gravity is not quantizable? No singularity at the "center" of a black hole, because there is no "center"; the event horizon surface IS the "center" of the black hole? The mass of a black hole is entirely contained at the event horizon surface, and thus when time stops at the surface, the movement of matter towards the geometric center also stops? There is no existence or "reality" deeper/below the event horizon surface, and thus the event horizon surface of a black hole is essentially an "edge" of the universe?

Sir, my question. A person falling into a black hole, if he turns and look back at the us standing far away, he would see oru time run faster and faster. So if his time stop relative to us, he shouldn't move any further. So he stays there forever, seeing the whole future of the universe. But he is also falling, so he sees our time run faster. I don't know where I'm going with this 😂. But the question is, what if we send a photon to a black hole and watch it fall. What will happen? Will it slow down?? That should be impossible, right? ???

Love these. Is there any equivalence between the redshift of light climbing out of a gravity well, and the redshift due to spacial expansion?

Hi Don, am loving your video series. I was wondering if a white hole/black hole pair is just a theoretical construct or is this something we may be able to use to travel great distances given that 2 joined black holes would take us nowhere? Thanks again for making physics accessible for us mere mortals

Don Sir Why does light take the shortest path . That's how geodesics and all come ,right?

" a meter or 2 in height" HAHAHAHA

Are you going to do a video on white holes to end the black hole series? I've always been curious, especially with the loop quantum gravity prediction that the white hole actually exists in the FUTURE of the black hole: Ashtekar, Olmedo & Singh "Quantum Transfiguration of Kruskal Black Holes." Several videos talk about white holes, but nobody mentions this cool new idea. But either way, keep the videos coming! The whole family loves them!

Thank you for confirming my thoughts on the possibility (even theoretical) of traversing a wormhole. This is exactly how I envision it.

What happened to Kip Thorne's paper which he wrote after working on the movie 'Interstellar'? What was the paper about BTW?

Sir, can you explain solutions of scarf 2 potentials.... briefly?

Great discussion as always! OK, so I will ask again: when are you going to discuss the temperature within a Black Hole? Given that it's very close to absolute zero, could that affect the gravitational forces? Thanks Doc...............Stay safe......👍👍😉😉😷😷

Would a gravitational wave that has passed through an object (e.g. a planet) in the line of sight to the generation point contain information about the object it crossed?

Could you please explain the flipping of the signs (+---) becomes (-+++) of the metric inside a black hole and what that would physically signify. And would this flipping be observable(experimentally) if someone were to be inside a black hole (hypothetically). Thank you

Awesome video!

Hello! What is the frequency of gravitational waves (the highest the lowest measured)?

Hi Don, Could you help explain why we define gravity as the curvature of spacetime if objecta experience tidal forces? Thanks

Hey fermilab can you guys make a video of scarf 2 potentials?

Can you explain how exactly 2 black holes merging loose mass when they emit gravitational waves? Also, would gravitational wave go through a black hole? Or would gravitational wave shift black hole by a tiny amount making it a new start for another weaker wave?

I love it when Don flashes a fake smile!

Thank you Sir

Sir if we know that gravity becomes stronger as we approach black hole , and the much stronger at Event Horizon, then will the quantum phenomenons will still remain the same or what kind of difference will be expected, especially inside a black hole.

is it possible to extend the lifespan of short life particle on earth on the more g planet by using to spacetime curve concept so we can find its properties

From the outside perspective, how long would it take for the clock to pass beyond the event horizon, regardless of if we can see it or not?

could you do a video on the exclusion principle?

did length contradiction applied for falling observer at all?

What does it mean when a black hole has charge, and how does it get this charge? Are these charges big enough that nearby electrons and protons, or even quarks inside protons, are affected by the black hole differently?

Hey Don, I’m a big fan of yours and of Astrophysics, and I just love this new format. Quick question: If I got it right, a beam of light sent outwards by a space probe just as it crosses the event horizon of a black hole won’t ever make it back to the space station that’s orbiting the black hole at a safe distance. What if another massive object (let’s say a neutron star) smashes directly into the black hole? (there is no orbiting, for the sake of argument, but a direct collision) Will the objects on the other side of the black hole feel the increase in its mass? If yes, why? Isn’t the event horizon valid also for gravity or causality?

Question: Some say, we can get information about the time „before“ the microwave background through gravitational waves. Are there any experiments regarding this and when do we expect some results?

Hello professor!! Inside a black hole there is all energy, does it mean that interchanging of space-time coordinates with time-space coordinates within event horizon is true ?

Hey Don! Hope u notice my questions! : ) Q1). When we say a wormhole tunnel has 2 black holes at its 2 ends, do we mean a black hole at one side , and INITIALLY, a white hole at the other , that has turned into a black hole over infinite time period, thanks to Penrose Diagrams? Won't the black hole at the first end turn into white hole, its mathematical opposite? Q2). is hawking radiation possible when a body crosses the event horizon in such a system, without its quantum info being "encoded" there/ becoming a part of accretion disk , as it must supposedly travel infinitely between the two ends of the wormhole ? won't the singularity act as a barrier? Q3).When we say microscopic black holes formed in particle accelerators evaporate , even if no matter has fallen in , what can be the source of the hawking radiation then? is it the singularity evaporating? will the singularity be dense enough to hold an accretion disk if matter falls in?

Hi Don.. when i think of a hole, i think of a flat 2 dimension with a hole opening a 3rd dimension 'inside'.. in a black hole, is it like a hole in a 3 dimensional space? is it considered like a 4th dimension?

Question: Have we performed a spectroscopy on 2010TK7 (our trojan moon)? And if not, what are we likely going to find in it?

Is it possible to visual demonstrate how time and space switch roles inside a black hole. I can visualise how space is time like (you can only move forwards to the singularity) but how is time space like

You have the earth spinning backwards at 10:40. I see this a lot. The NJ Transit ticket vending machines also have a graphic that does this. What's going on?

Dr. Lincoln, thanks very much, i really enjoyed it. I am a biologist and while COVID has kept us from getting to the bench to make our own data, I have enjoyed watching your videos here and on the Great Courses to get my science fix. I have been re-reading lately some of the great science fiction by Larry Niven, and having watched this most recent video of yours it made me think of the following silly thought experiment. If you took multiple masses of neutron star (say maybe five or six) and put them in flat space in mutual orbit in a Klemperer rossette, you could have them rotate in a circle (like ring around a rosie) with the centre of mass (and 'center of the gravitational field" in the empty space in the middle. If you made your pieces of neutron star large enough, could you bend spacetime in the center of the rosette so much that it became closed off from the universe even though it had zero mass? Not really a black hole, but not 'normal space time' either. I think this would work as your previous videos have pointed out that the Schwartzchild radius is actually quite small. To make this even sillier, you could avoid spaghettification. if you initially put the masses of the mutually orbiting neutronium masses below the amount necessary to close off spacetime, you could find and 'go' to the center of the gravity field. Once you're in the middle of the field, your gravitational potential energy should be zero and strong gravity wont harm you. I understand that gradients of gravity might be a problem. Now final silliness, what if you put a nice piece of Brie at the center of the gravitational field, and then afterwards added neutronium to each of the orbiting masses so that now spacetime was so bent that light could not get out. What happens to the cheese after it is shut off from the universe? What happens if 1000 years later I remove some of the neutronium from the orbit masses, so space is now bent less and light can get back into that region of space. Once you remove the neutronium 1000 years later, can i eat the cheese?

Question: Is there a way to get rid of the Event Horizon of a Black Hole and see the singularity if it gets hit by very strong gravitational waves or if it gets sucked up by a bigger Black Hole?

I had been wondering for a while how close or rather if you would ever feel the contraction of space due to gravitational waves, excellent explanation, I was shocked by the answer!

Great video!!! I have a weird fascination about objects that are so far away from us on Earth that their light simply cant reach us in our visible light spectrum. I have been thinking about this alot and when you mentioned the clock that is falling into the black hole changes color as it goes deeper and deeper until it reaches the event horizon and "dissapears". Could it be that a black hole simply takes whatever is falling into it and moves it to a place that we cant see because its simply too far away for us to actually see tbe otber side? Maybe its a stupid question but its been on my mind for quite some time. Take care.

Question : am I correct in assuming that spaghettification is much less severe for supermassive black holes since the bending of space-time is more gradual there? Could one envisage to actually survive this (at least for a while longer)?

Hi there, I find your videos very educational to the extent that I am considering to pursue physics. My question is does the angle at which the light bends near a mass depend upon the frequency of the light.

I read a study about electrons fatigue made by Padaroy and Esmolar and I think it could have influences on black hole gravitational pull.

Assuming there would be an hypothetical way of producing gravitational waves stronger than is currently possible from a merger of black holes, what would the effect be on a person? Would it feel intermittent pulls-pushes as the wave traverses it?

If a falling object accelerates toward a gravitational field at a constant rate per unit of time is it possible to simply add an acceleration force to an object(through an engine of some sort.) and maintain the objects position ahead of the gravity wave pulling the object in?

Let's clear up some misunderstandings in some of the responses below about what _you_ experience when you fall into a black hole. First, from your perspective you just fall through the event horizon. But everything that happens inside the horizon, stays inside the horizon, as the _event_ horizon breaks the causal connection from events inside to events outside, hence its name. So the outside universe will never see anything happen to you past (and on) the horizon, which is why nobody will ever see you cross the horizon. Second, the extreme blue-shift and peek into the complete future of the universe only happens when you, from your perspective, manage to stand still at the horizon, which is ... hard. Third, the strength of the tidal forces at the horizon depends on the massiveness of the black hole. A very, very massive black hole, has negligible tidal forces at the horizon; these will only become strong enough to rip you apart when you get closer to the singularity inside - which is inevitable. The advantage of falling into a big hole is that your agony won't be observed in the outside universe...

Hi Don, love your videos. Q: If nothing can escape beyond the event horizon of a black hole, then wouldn't that include the alleged graviton particle? If so, then do black holes demonstrate that gravity, as we perceive it, is an emergent property of the warping of spacetime?

Hi, If Hawking radiation predicts blackholes emitting radiation due to quantum effects near a black hole event horizon, the would it be reasonable to expect gravitons to be emmited as well if those existed? Bending of space time itself need gravitons so would hawking radiation mean more forces than expected for a particular size? Also if gravitons are like photons and gravity can bend light, then can gravity can bend itself? or is that too recursive? Are there currently any active efforts to measure Hawking radiation?

On the topic of the delay between gravitational waves and light, I suspect that the gravitational waves just took the shortest path to us while light was bent ever so slightly around regular stars and possibly even high gravity objects (gravitational lensing) and had more distance to go. Hence the delay.

is it likely that singularities have a size greater than 0 because the acceleration of the expansion of the universe depends on how much the space-time is bended on some location, if so, is possible that at some region the black hole stops collapsing because the gravitational acceleration and the acceleration of the expansion of the universe add to 0?

Hi Don.. does the black hole has a bottom? What happens to everything that falls in there?

Dr. Don! Could you do an episode on theoretical particles that have not been proven to exist yet? Like the graviton, sterile neutrinos, magnetic monopole, axion, X17 particle, etc.? Maybe you can give your best guess on whether or not you think they are real, and if we can ever prove they exist?

hi Sir Don, this episodes question Why does a moving charge create magnetic field, as per quantum mechanics (why we have to explain using relativity)

Hi Don, Does the wave function of a particle still apply inside a black hole?

Question : Can you talk about pilot wave theory and and make a video about it and what are the new discoveries in this theory today in 2020 ? If you see my comment please reply me

I hope to warp around with an Alcubierre drive, so don’t mind giving up wormholes. But! If two black holes were somehow joined together as an ER bridge, could the area immediately outside the event horizons be (a) compressed and (b) navigable? Also, surely a black hole-white hole combo clears up the entry problem. Side question, since we’ve seen two black holes merge, and relativity is time reversible, should we expect to see two white holes blow apart? If they did, would the ripples in spacetime move inward? Would LIGO/VIRGO be able to tell the difference?

What are your thoughts on Planck Stars?

If for an external observer matter stops right at the event horizon: how can Black Holes actually grow - shoudn't all infalling matter be more or less stuck at the event horizon and never actually enter it in a ending amount of time? Espacially how does it work for a Black Hole Merger ?

Great video! Has anyone theorized what happens inside the 2 black holes during the merger? Do the singularities head straight for each other, or do they spiral in, can singularities merge?

Dr. Don PLEASE HELP! I was explaining nuclear decay to a friend and going over the different types. And I said that beta emission makes sense because the neutron is a bit heavier than the proton so emitting a n electron with momentum is where the mass goes. But then I was trying to explain positron emission and I had to stop. I didnt know how to balance the energetic equation. Because the neutron is heavier so there is more energy and then there is the positron and its momentum and then the neutrino and it's tiny momentum. Does this extra energy come from a w boson Or something? If so where did that energy come from? Did a positron electron pair form some how and the electron gets captured? That makes a lot more sense.

Hi Don. How can I reproduce the double slit experiment at home?

Do gravitational waves propagate as a sphere or in a 2d plane? In all those images it seems 2d (same as a ripple on the water), which makes sense... but then this mean that we can only measure gravitation waves with mergers that happen parallel with earth? If yes this means there are a lot of gravitation waves and mergers but we can measure only a small fraction of them?

It is important, Dr. Don, that you are explaining the true essence of a wormhole to the public, including science fiction makers who have misunderstood and misrepresented the wormhole as a means of transportation, which is indeed silly. Sci-fi should not significantly misrepresent science.

Can you explain the idea of naked singularities? I find this idea confusing because surely you can't have a singularity without strong gravity, and then you would get an event horizon, correct?

Is observing a black hole falling into a black hole any different? The animations make it seem like things move fast in that case. Is this always the case or do masses have to be similar for that?

Hi Don! I absolutely love your videos and this series. I'm having difficulty understanding a specific aspect of relativity, and I wonder if you could help? It seems to me, that if we put a double-slit experiment that fires photons from the back of a ship to the front, and the ship is heading directly towards me, it seems as if the shorter distance the photons travel (length contraction!), and the increased energy (blue shift!), due to the relative motion should both cause the pattern that forms on the far wall of the spaceship to disagree (from my point of view) with an identical experiment performed stationary relative to me here on earth. Do they indeed disagree? What am I missing?

When talking about hadrons as particles that take up a volume, you’ve used animations that simplify their internal structure as balls orbiting one another, perhaps joined with squiggly lines. But what can we say about the internal structure or geometry of hadrons? How are quarks packed into something like a proton?

I have a question about spaghettification. How does it tear the falling observer into pieces if the increase in gravitation is continuous? Is it because on the microscopical level the strong nuclear force overcomes gravitation so we rip the clock apart at the atomic level?

What are the relativistic effects at the Lagrange points? Related: What happens to a clock when you position a heavy weight above it?

I take exception to the visible universe and the gravitationally accessible universe being the same, even though the speed of gravity is the same as the speed of light, because if you look far enough to see the cosmic microwave background, your vision is blocked by plasma that hasn't completed recombination to neutral gas, whereas gravitational waves can go through the plasma (for the same reason that they are hard to detect).

Hi Don, can you please explain how time and length switch places inside a black hole. How length only goes forward and time can go both ways, to the future or to the past.

If all things starts from singularity then is their any relation between gravitational wave & electromagnetic waves

Might be you can shed some light past the event horizon of my brain. I often read/hear that a black hole leads to a place call time-space rather than space time, where all directions leads to the same time (aka the singularity). Activating booster would only leads to speed up your clock reaching the singularity even faster. If I somehow avoid spaghettification by being gluten intolerant, would the clock stand still once I reach the center of the blackhole? Is there an arrow of time past the event horizon?

No one ever talks about the fact that the universe would pass away by the time you actually pass the event horizon, enough time might have even passed for the black hole to have dissipated.

Dear Don. I know it's not good manners to re-post a question previously left unanswered. But please, could you find it possible to elaborate on now can a black hole form at all within the time frame of our universe, if relativistically speaking, the matter would be taking forever to drop into such highly curved space-time as is suggested for those objects by the same theory? How can we see those object at all in our universe? How can we see any object falling into it for that reason? And secondly, what do you think the matter is within those objects (because we still have to assume there is some real physics going on within)? This question arises from the assumption that any object can be turned into a black hole, but for some it is so small that no known matter can accommodate that.

What is the force carrier for gravitational waves?

Hi, Don! So GR says gravity manifests in spacetime bending, and the force is sort-of fictional - we just travel the straightest possible geodesics. On the other hand, we expect that in the quantum gravity the force should be mediated by gravitons. Since the GR is imprecise theory - do we expect that in the quantum theory with the force mediated by gravitons there will be no spacetime bending caused by gravity, or do these 2 effect will work simultaneously? Thanks.

Can neutrinos accumulate into planet or star like objects? Could theses neutrino objects get large enough for neutrinos to fuse into heavier particles?