19 Subatomic Stories: How we know black holes exist

Black holes live up to their name. They emit no light and they’re usually very far away. This makes it hard to take pictures of them and, indeed, some people claimed that they might not exist. But that’s no longer true. In Episode 19 of Subatomic Stories, Fermilab’s Dr. Don Lincoln tells us how we are quite sure that black holes are real.
Fermilab physics 101:
www.fnal.gov/pub/science/part...
Fermilab home page:
fnal.gov
ALPHA-g footage - CERN
"The Thinker" photo - Douglas O'Brien from Canada
Thermometer vector- Vecteezy

[@nmccw3245]

Thanks for the weekly videos Don. They are very much appreciated.

[@discreet_boson]

Oh yeah, it's fermilab time

[@johngrey5806]

Spoken in a Randy the Macho Man Savage voice.

[@Nienormalny]

@@johngrey5806 Damn.. would love to see that :D

[@MuttFitness]

Oh yeah, snap into a Fermilab!

[@NicleT]

Dr. Lincoln, as always you present the best science channel of all. Thank you.

[@richtalk34]

I'm reading an excellent book on anti-gravity. I can't put it down.

[@paulellis2518]

Would you like to share the title?

[@richtalk34]

@@paulellis2518 Certainly. It's called "Falling For It."

[@paulellis2518]

@@richtalk34 thanks a lot!

[@dans4323]

😂🤣😂 Good one.

[@SquirrelASMR]

I am watching a fascinating documentary about a down syndrome squirrel. I made it... it's on my channel...

[@EddySunMusicProbe]

Thank Don for this nice and illuminating series! Thanks for the answers to the many questions too! Cheers, Eddy.

[@kylebowles9820]

Thanks for the back story Don that was awesome! The predictive power and precision of science persuaded me

[@scudder991]

Dr.Don, thanks for fully explaining what is meant by the concept "temperature of space".

[@sarahcampiche]

Thank you Doc for this amazing series!

[@SlowToe]

You are a wonderful Science communicator Don. This channel on KZbin will definitely inspire the next Generation of curious minds.

[@user-cv1jb9xv2p]

Thank you for giving your time and energy.

[@bobbourke1039]

Another great show, thank you. Now for a suggestion / request. I'd love to see "A day in the life" style show. A show where you show us what one of these experiments actually looks like at FERMILAB. The warts and all theory behind the experiment, the actual experiment and the hours of what the data looks like before those incredible brains make sense of it.

[@brothermine2292]

An intermediate black hole was recently observed, contrary to Don's claim. Unexpectedly, it was located outside a small galaxy, not at the center of a small galaxy. Astronomers always looked for intermediate black holes at the centers of small galaxies, since the centers of galaxies is where supermassive black holes have always been found and the well-established pattern is that the mass of a supermassive black hole is proportional (roughly speaking) to the mass of the galaxy around it. It should also be noted that a fourth type of black hole has been theorized: primordial black holes created at the big bang, small enough that most would have already evaporated if Hawking's theory about black hole evaporation is correct.

[@litigioussociety4249]

14:55 "It's both unpleasant, and lonely." 😄

[@ZeedijkMike]

Yes that one nearly made me piss my pants.

[@XxfishpastexX]

You put a smile on my face, Fermilab ;P

[@tresajessygeorge210]

THANK YOU PROFESSOR LINCOLN...!!! Waiting for the new updated physics...!!!

[@BobJones-dq9mx]

Another excellent tutorial!

[@hanssacosta1990]

Woww your videos are amazing man, I love them all❤️❤️🙏🙏✨✨

[@themcchuck8400]

Another good video. Thanks for keeping this series going! Question - Is relativity relative or absolute? What are the relativistic effects at the Lagrange points? Have the atomic clock experiments been tried with a weight suspended above them?

[@matteodelgallo1983]

Well, relativity is "absolute" as in we assume that it applies in the same way everywhere, because if physics itself changed depending on your location, then we could not know what it is like outside of the area, unless there is a universal way to describe how it changes, which would then be the deeper physical truth and therefore wouldn't change.

[@themcchuck8400]

@@matteodelgallo1983 You obviously failed to understand my question. I blame myself for not wording it more clearly. Do relativistic effects depend on the absolute energy levels, or the gradient?

[@FreshBeatles]

I LOVE THIS SERIES!!!!!!!!!!!!!!!

[@princeandras]

Hi Don, great content, as always. Me and my cats are a huge fan of your vids. I have a question related to black holes and the information paradox. I understand the problem is that Hawking radiation is random and thus cannot carry information. But what about the remnant of the black hole after the evaporation? When the evaporation reaches a point where the black hole collapses then it surely happens in a unique way, right? And that unique explosion could actually convey information about what was in the black hole and thus no paradox exists. Whats your view on this? Thanks, Bence

[@siddharthmukkanawar4510]

Thank you Sir for giving us knowledge, I am always fascinated by astrophysics and particle physics though I am an engineering student I would love y to work in this fields

[@goofygangster959]

Amazing episode as always.. thank you Doc for putting in all the effort for us mortals.. Physics as we know of it right now leads us to believe that the time exists because of gravity.. however in ancient indian physics books we've been given to understand that gravity is a curve, a bend in time and exists only cuz time exists.. Would be great if you could pls reflect upon the idea and some ramifications of the same. Thanks for the lovely stuff!! :)

[@preethiyogesh9821]

Can you please tell which ancient Indian physics book it is ? Just curious

[@KasiusKlej]

Was this book about Achilles and the turtle and the chicken and the egg, where they race, and the question was which one came first?

[@goofygangster959]

@@preethiyogesh9821 try vaisheshika sutras by rishi kanad or listen to sadhguru jaggi vasudev on KZbin abt yogic opinion on creation

[@preethiyogesh9821]

@Goofy Gangster thanks for sharing information ,please do mention other physics related ancient Indian books ,interested in finding out 🙏

[@macherlakomaraiah2358]

Thank you sir for answering my question

[@davesutherland1864]

At 9:22 you start to discuss theoretical vs. experimental physics considerations for Swapnil Kumar who currently appears to be studying engineering. I have another suggestion. It was about 40 years ago when I graduated, but I studied engineering physics. At the end of that course you could do further studies in various engineering disciplines, experimental or theoretical physics. I found it to be a great course for those who were not sure which way they wanted to go when starting university, and my classmates took a variety of paths. Considering that one that took the pure physics route won a noble price for her work, this certainly was not a path that result in limited opportunities for those that chose physics over engineering after undergrad work was complete.

[@SquirrelASMR]

I wish I could go back and do grad school, but I cant so it's so nice to have channels like these.

[@Cronos804]

I would like to see the math for why no energy is gained by fusion after iron. I do have a math degree but i lack the physics knowledge to even guess where to look.

[@drdon5205]

courses.lumenlearning.com/physics/chapter/32-5-fusion/ Iron is the most stable nucleus. Below iron, moving to a heavier element releases energy (e.g. fusion). Above iron, moving to a lighter element releases energy (fission). Look at figure 2 in the link.

[@YCCCm7]

Basically, iron and nickel are about tied for the highest atomic bonding strength, so it takes more energy to break them apart than you get out of the reaction. It becomes a pure deficit for energy returns, in addition to being harder to make happen in the first place.

[@blueredbrick]

Think of degenerate solutions to a set a equitions, continuous or discrete, does not change the concept. In chemistry degenerate solutions are common both litterallyI in experiments for example in isothermal reactons even when isolated from the environment. But also theretically, many molecules have or materials have degerate states..meaning.. yes, something changed but no energy was used to expelled from or in the system volume. Same goes for quit a handfull of particles near irons most common isotope. They are indifferent/degenerate in requiring energy or expelling energy to/from the surroundings. The optimum is at iron Like DrDon pointed out. And thus there is sort of an optimal energy drainage going on toward that iron region. But nickel will be also present but much just less so. But just like in more mundane stuff like atoms reacting etc there is a spread at least spanning several kT worth of energy when transitios/reaction are possible. Constantly switching between electonvolt and joules/mole and wavenumber and wavelenght euiqvalents to make sense..I prefer electronvolts actually in thinking about stuff happening step based, and joules are awesome for bb guns haha and more macro scale. Really it does not matter. it is the whole range that makes it interesting. In nanomaterials, when making particles with a certain size it is possible to get them from the ge- go almost exactly at e.g. 10 nanometer... but yeah, that just means the peak is at 10 and drop extremely fast either smaller particles or larger, still when examining there you will find the oddball 5 nanometer weirdo. Representing also a extreme outlie-er in "effective melting temperture". For example..god will melt with ease at ~200 if small enough. weird. not really. Cool, yeah. I come from a more nanomaterials background, so im never able to put my finger how to feel a chemist, experimentalist, psycisist or more generalally, scientist. After all, science is everything, including phsysics and why not phylosophy while were at it.. PhD anyone ? ;p I must be bored. Great video Dr Don.

[@dogcarman]

YCCCm7 Soooo... since the pressure and temperature is still quite high when iron starts forming, would it be more accurate so say that iron fusion happens but sucks up energy, so that the core basically cools down and looses pressure?

[@paulmichaelfreedman8334]

@@drdon5205 His question was WHY anything heavier than iron will fission with energy release, and lighter than iron will fuse with energy release. There's a QM rule somewhere explaining this, although I recently pondered this question myself but haven't looked it up yet although it know it has to do with the total binding energy (strong force interaction) within the hadron.

[@captaincruise8796]

That was an unexpectedly thorough explanation about the temperature of space. So I guess when physicists refer to the temperature of space, they just mean the (current) temperature of the cmb. The temperature of the photons black holes always absorb and thus they can’t leak energy until the cmb cools off some more. Thanks!

[@MEBVishwaS]

My question was not replied in this video. Can we observe radiation from a stationary charge when we are accelerated. If we can observe, then we should feel a retarding force due to loss of energy as radiation. Whether it is tested in lab.

[@stevenaspinwall2480]

This statement and queston contradicts it self let me explain why. You say stationary, but can it give off radiation. This means the object or particles are not stationary and are in fact moving at the speed of light because radiation is light. Having no movement would be zero kelvin. Something believe to be unreachable.

[@datapro007]

Fun stuff. Thanks Don.

[@scottfollett9988]

You showed the first picture of a black hole. It got me thinking. In your opinion, what are the most significant or important photos in physics?

[@ayushichhipa199]

Thank you for this amazing series professor!! Question 1: How the supermassive blackholes were formed in the beginning of the universe ? Question 2: Supermassive blackholes present at the centre of radio galaxies become active when they burp after eating matter from accretion disk, but this is not a continuous process, Why??

[@KohuGaly]

1. They seem to have grown from smaller black holes. This is evident from a fact that quazars (active galaxies with smaller central black holes) can only be seen in early universe. As for where the original "seed" black holes came from, that's the big question. They could've formed from mergers of early stars and their remnants, but if so, it's unclear how they could've grown so fast. 2. The "burp" in question was short on universal scale, but it was most definitely continuous and long process.

[@juzoli]

KohuGaly The leading theory these days is NOT smaller black holes, as we didn’t have enough time for so many mergers. Instead, it is likely that in the early eage of the universe, the densest parts of the universe has collapsed straight into black holes, skipping the star-phase. Less dense parts became stars. Dr Becky had an episode explaining all these hypotheses recently.

[@KohuGaly]

@@juzoli Yeah, probably.

[@ozzymandius666]

I suggest you start with differential equations, then learn linear algebra, then a bit of tensor calculus, then quantum mechanics and general relativity, then group theory, and the various GUT theories, then the *(%*&$^%#$# Grassman numbers and supersymmetry, and then there is...Edward Witten.

[@Dragrath1]

Question 1: This is currently an unsolved mystery which scientists have yet to resolve. Regardless we have evidence of quasars when the Universe was only half a billion years old so they had to grow very fast too fast for them to grow to their masses via accretion alone. They might have formed by direct collapse, over dense star clusters, extremely massive Pop III stars and or by frequent black hole merger events or other mechanisms we haven't even thought of yet. Question 2:The reason the process isn't continuous is due to multiple reasons first to accrete matter you need more material falling in on the black hole however the radiation and outflows of ejected material from the accretion disk has the potential to heat up the in falling material preventing it from infalling further or forming new stars via a process known as quenching. This is more of a thing in the later universe since the black holes have largely consumed all the gas and dust around them. In this case further accretion depends on something new falling in say a new supply of gas via a galaxy merger, a tidal disruption event etc. basically the answer is that after the quasar epoch ended black holes largely ran out of "food" when a new "meal" arrives they then begin to flare up again until they exhaust their new supply of material

[@Toocrash]

Thank you for the insight. On top of the momentary resistance of shrinkage, that results in the bouncing of inrushing not to be included matter, there is fusion due to increased pressure. Can't help but think about the inward kick given by the occurrence, it makes me relate it to the working of a hydrogen bomb, or the initiating moments of a nuclear bomb.

[@theultrapixel]

Hi Don! Do you think that we as a species have enough data and know enough phenomena to derive a theory of everything if only someone looked at things the right way, or do you think we are missing critical pieces of the puzzle that will keep an answer out of reach until we observe them? Where in between those two extremes do you think we are, and what are some of the more promising lines of investigation going on today to find the missing pieces and/or reinterpret the existing data?

[@ozzymandius666]

Can't speak for the Don, but I hope we make an awesome theory of everything, and then find an experimental result that makes us question it, and then make a better theory, and then find an experimental result that makes us question it, over and over again...forever! Its kinda like a Flat Earth thing, except we could just sail across the horizon to find a new, virgin land, forever!

[@MuttFitness]

If you want to get is a submarine and shrink down to donsurgery knside slmeone, is it easier to shrink the atoms or should you just use very tiny atoms?

[@Petrov3434]

Hi Don, can't figure out even where to send you a question. Hoping against hope I am asking you my question here - my apology if it is too pedestrian: Is cosmological constant and dark energy terms same/identical? It seems that "cosmological constant" term has fallen out of fashion and replaced by "dark energy". If your answer is yes or no -- could why kindly explain why? Many thanks in advance, Boris

[@ZeDlinG67]

I recently found an article on mirror matter (as a candidate for dark matter), and although I didn't came close to understanding it, it reminded me of supersymmetry's proposed cousin particles. Are they the same, or we could have a bunch more layers to the standard model?

[@naveenjames7]

Hi Don, What is your viewpoint about Tachyons?

[@haangul3393]

Really amazing

[@luudest]

4.40 In which orientation do we look on the black hole? Why is the upper right of the picture dimmer?

[@tabularasa0606]

Gravitational lensing, the what you see at the top is actually the accretion disk that is behind the black hole. With the light bent around the BH.

[@Dragrath1]

Technically we have finally gotten convincing evidence for an intermediate mass black hole and there are other unverified sources which increasingly seem to hint that intermediate mass black holes do exist. Many of these candidates are surprisingly in the outskirts of their host galaxies which according to models should actually be expected in the case of direct collapse black holes thanks to galactic mergers easily displacing them and the low cross sectional area of interaction for an intermediate mass black hole not yet sufficient for run away accretion if not in the right place at the right time since they are unlikely to come close enough to any stars to actually become active and any that did become active would have already grown into supermassive black holes in the early universe. The one strong candidate that seems highly likely to be one of these black holes is as these models predict in the outskirts of its host galaxy as are the majority of other known candidates the major exception being the still contentious claim for a few thousand solar mass object in orbit around Sagittarius A* though a few alternative explanations exist for that object. Interestingly if direct collapse models hold up there might even be up to a dozen or so of these black holes lurking in the halo or disk of the Milky Way. And there is even potentially a hyper velocity star which traces a trajectory back into the disk of the Milky Way suggesting a black hole in excess of a thousand solar masses. Of course as with everything in science this is just a model which may or may not be true. Only further evidence will allow us to better resolve this question but I think it is still too soon to say they don't exist.

[@clancyjames585]

Remind which intermediate black hole you're referring to? There have been so many hints that have been disputed up until now. Do you have a link to the paper?

[@tobilsch8433]

hi don, i have a question about a earlier video. you talked about object very close to a black hole at the event horizon, where gravitation is very strong. the light of this object needs a lot of energy in order to leave the vicinity of the event horizon. therefore only blue light (shorter wavelength) would leave it. this makes sense. but what i dont understand is, why a observer would see this object as red and not blue?? the only thing i imagine is, as the blue light leaves the vicinity of the black hole, the wavelength gets stretched, and redshifts. but im not sure about it. thanks

[@cloudpoint0]

You nailed it in your final sentence.

[@glennstasse5698]

I’m opening restaurants at CERN and Fermilab and calling them “The Accretion Disk”. Super hot Buffet style food on a rotating central platform. Free spaghetti with entree!

[@ozzymandius666]

Calamari fried in proton/anti-proton beams? I'm in!

[@drdon5205]

That would explain my steadily increasing mass.

[@patrickaycock3655]

Pastafarians would like that.

[@theultrapixel]

Hi Don! Is there any difference from the point of view of the rest of the universe between a virtual electron/positron pair appearing & annihilating near an event horizon (neither going in) vs a pair appearing and both falling in before they annihilate? Sorry for double questions if that's not polite!

[@ozzymandius666]

The only way to observe an electron/positron pair appearing is to pump enough energy into the vacuum to make them real.So the answer to your question is "no."

[@RealMajor66]

I think Sheldon Cooper would be quite upset if he saw this video 😀 Love your videos btw, my favorite series on KZbin.

[@SquirrelASMR]

Well I get upset everytime big bang theory is on tv so sheldon can suck it

[@Brahmdagh]

So, specification occurs at a particular distance from the singularity. And in Supermassives that distance falls within the event horrizon?

[@devoutsalsa]

Plot twist -- "subatomic stories" videos about black holes lead to a theory of everything

[@benrichardson7306]

I'm in! You go first. :)

[@althomas6045]

what a great guy. thanks doc.

[@germanhiguera7067]

Hi Don, one Question? As a high end physicist, are you able to solve mathematical problems such as a simple fourier transformation or laplace to a really reaaaaally hard integer without using symbolab or something like that

[@drdon5205]

Some. And smart physicists can do much better.

[@hric.martin]

Hi Don, what's your opinion about what's happening to the things beyond Schwarzschild radius? How do you imagine the interior of a black hole? Like matter being squeezed up to Planck density as written here arxiv.org/pdf/1401.6562.pdf or if you have some cool scientific hunch. Or if you simply think "we'll see". Or something inbetween? Thank you.

[@ozzymandius666]

Hmmm, starts with just below the horizon, jumps straight to the Planck crazy stuff at the center. You must be a real charmer!

[@LordPhobos6502]

Does spaghettification also happen near Neutron stars and White dwarf stars?

[@drdon5205]

No. The gravitational field doesn't change rapidly enough.

[@simran4222]

Hi Don! if a single photon is bombarded at a microscopic black hole before it evaporates, will we get a stable (or rotating) black hole with increased mass & an accretion disk, which will devour the particle accelerator (& the planet ) OR the photon trapped will be emitted as Hawking Radiation instantly OR what ?

[@Lucius_Chiaraviglio]

Whatever a black hole consumes is competing with Hawking radiation losses, and what matters is which one predominates over the long haul, so a single photon would just delay the completion of evaporation by a short time.

[@rJaune]

Great episode! Do all massless particles expand as the Universe expands, or only light? And why?

[@Anaesify]

The photon, gluon, and Z boson are the only massless particles, and the gluon and Z boson are "force carrying particles" to massive particles; they are constrained by the masses they are paired to. So the photon (light) is the only one that is free to expand.

[@simonmartinez91]

would a black hole made of anti matter be any different than one made of regular matter? would any of them behave different if they suck the opposite kind of matter that made them?

[@danlalonde5751]

Hey Dr Lincoln, Why does gravity effect light, when light is massless; and what is gravity's effect on red-shift?

[@asdfdfggfd]

Before you move on from black holes, could you do an episode about about the hypothetical quantum mass that possibly resides at core of black holes?

[@davidgreenwitch]

Hi, another week, another question. If a black hole makes us loose information how does it work with entangled particles? Say I have two photons entangled so knowing one's polarization I also know the other one's. But if that one falls into a black hole, shouldn't these properties get "lost"? To me it sounds like I could have additional information about the interiours of a black hole that way. Is that possible?

[@cloudpoint0]

Entangled particles should remain entangled in the situation you describe. You have no information about the BH interior though, just like you would have no information about the environment of any entangled partner that is far away. Entanglement does not convey information between partners. It’s just a known correlation.

[@ebenolivier2762]

You just described how Hawking came up with his idea for Hawking radiation. 😊 And the last part of what you are saying is called the black hole information paradox. Fascinating material to read up on. Kip Thorne, Leonard Susskind and Hawking all had bets about the resolution to this over the last couple of decades.

[@davidgreenwitch]

@@cloudpoint0 What I mean is, consider I would create a black hole only consisting of these entangled particles. I then would have knowledge of these properties, too. (Except in case their polarisation, spin or what ever would get lost) But I understood black holes won't have these kind of properties, which leads me to the assumption that it can get lost. But how, aince they are entangled?

[@davidgreenwitch]

@@ebenolivier2762 Isn't Hawking radiation something different? Like the emission from the black hole? What I meant to ask was the conflict of a) knowing properties for sure since particles are entangled and b) the definition that a black hole doesn't have any of these properties (any more)

[@ebenolivier2762]

davidgreenwitch Hawking radiation is indeed an emission (radiation) from the black hole. You are delving into very deep and technical territory with your very good questions. 😊 For a very long time the information loss in a black hole could not be reconciled with quantum theory. The holographic principle by Susskind and t'Hooft seems to resolve this, but then there was the firewall problem...

[@Ambienfinity]

HI Don, the physics of black holes was explored in the movie Interstellar, where time dilation meant that the main characters in orbit of 'Gargantua' experienced extreme time dilation on one world and return to their more distant ship with years of messages from Earth awaiting them, after just a few hours. I know the physicist Kip Thorne was involved, and has some fascinating ideas about time and gravity -- is the storyline feasible or was it just Science Fiction hokum? Keep up the great work, I'm a big fan -- more about Higgs boson please when you're next able!? Thanks, Nigel.

[@drdon5205]

It's a mix. Time dilation is a real thing. Going inside a black hole and seeing bookshelves in the past, not so much.

[@Ambienfinity]

@@drdon5205 Ah, I see you're familiar with that part of the movie. Yes, let's not even get into bootstrap paradox. Thank you Don.

[@constpegasus]

Thank you Mr Lincoln.

[@noahway13]

0:52 You can't make energy by fusing elements heavier than I am.

[@n3v3rg01ngback]

Professor Cornell went into this in some detail in a 1994 paper, “Blackhole Sun: Won’t you come?”

[@TrekCZ]

Spaghettification is easy to understand for photographers, it is similar as when you take a photo with strobe or other artificial light, if you are near light source falloff is great - e.g. nose exposure is serveral stops higher than ears, if you are far away from the light source exposure falloff is small. It was explained less understandably - massive black hole has Schwarzschild radius far away thus smaller falloff. I was confused why even Schwarzschild radius was used for Spaghettification explanation.

[@thedeemon]

Yes, both intensity of light and curvature of space are proportional to 1/R^2, good analogy.

[@ayushichhipa6025]

Sir, most space-time diagrams for black holes are formed using geodesics, but according to second law of thermodynamics, doesn't these break causality ?

[@stevenaspinwall2480]

Help! We know space time is expanding and also speeding up. But does this also infer that the higgs feild, which permeates all of spacetime, is also expanding?

[@chronology2.0]

Isn't it that case that with a supernova the outer layers of the star 'bounce off' the inner layers due to a density difference when the gravitational collapse takes place, instead of them 'boiling off' due to the heat or am I wrong with that statement?

[@tareqsaleh5690]

I have a question since light is a collection of fotons and when it reflect on object how it takes information about it in which forn taking into consideration that foton has no mass how a massless object carry something and it stay without a mass?!

[@roanbrand7358]

Hi Don. Do you know what the probability is of LIGO detecting the merger of 2 supermassive black holes? Or maybe after a future upgrade?

[@drdon5205]

Zero. It's outside the facility's capabilities.

[@roanbrand7358]

@@drdon5205 Thanks! What is the reason? Are the orbiting frequencies too low for those? Or are they extremely unlikely events over the distances we can detect?

[@drdon5205]

@@roanbrand7358 The frequencies are too low.

[@VelvetCondoms]

Next week, can you talk about the generations of matter? How sure are physicists that there isn't a generation below the up/down/electron generation, or one above the top/bottom generation? How do we know?

[@drdon5205]

Not the next one, but 5 or 6 from now.

[@ajaysasikumar6931]

Thank a lot Dr.Don, my ambition was to become a Theorist, but I changed the decision and taking Expirimental Physics but I was confused. Btw can you recommend a good book on *particle* *physics* .

[@drdon5205]

Understanding the Universe

[@CCRLH85]

I have a couple questions concerning observational physics and black holes. With all the talk about the possibility (though slim) of "Planet 9" actually being a small black hole, what type of experiments could be performed by a New Horizons sized craft if we sent it to explore a black hole in our own star system? Are there any unanswered questions that such a voyage could answer for us?

[@dan7291able]

Hey there Don, big fan, long time listener first time caller Wouldnt supermassive black holes logically have come from millions of years of eating other black holes? I imagine the black holes at the center just gobbling up smaller black holes constantly throughout millennia ? Maybe there are no "intermediate black holes" because they never have time to get bigger than they all are before merging with a Supermassive? Thanks if you answer! big fan, learned a lot from you

[@altauba]

Does sphaleron process carryout in the black hole?

[@Anaesify]

Do you have a pet theory for what you think happens to matter at "the singularity"? Mine is that it's not a singularity at all, but all of the energy and matter crushed down into a gluon-quark plasma sphere the size of the planck length (LQC scaling actually), where quantum effects are the driving force of activity, but I love how everyone who thinks about black holes for long develops one :D

[@IntraFinesse]

Kip Thorne says its converted into the warping of spacetime, that there is no matter inside a black hole.

[@scottmuck]

Wait, what!?!? Behind the doc's shoulder is a book I'm currently in the middle of on the French Revolution ("Citizens") .

[@arcade5765]

is it good?

[@scottmuck]

arcade Quite. Excellent reading for anyone interested in French history.

[@arcade5765]

@@scottmuck Ok, I've been meaning to educate myself about the French Revolution for a while now. Gonna check it out

[@timmykenny717]

Wasnt there just a video about a lab tour? Why did it get taken down..

[@Anghelnicolae]

Is it possible that while falling into a black hole, because time moves faster outside of it, you could see the black hole evaporating behind you?

[@CCRLH85]

As far as spaghettification occurring inside of the event horizon of a supermassive black hole, wouldn't that only happen if the mass inside the event horizon was rather close to being a point mass? I remember from previous videos that you (and most physicists) don't think that a true singularity exists beyond the event horizon. That being the case, wouldn't it be more likely that you'd go (for lack of a better term) *splat* upon impacting whatever form of matter exists inside rather than being stretched?

[@logancarpenter2558]

Solar mass black holes will spaghettify matter near the event horizon because the force of gravity is greater then the chemical bonds holding the atoms together. This isn't true for supermassive black holes because the event horizon is sufficiently far from the singularity. However, as matter approaches the singularity the force from gravity will increase and eventually be stronger than the chemical bonds - ripping apart every single atom from its neighbors (spaghettification). And to be fair each atom goes splat when it impacts the singularity.

[@Tomas.Malina]

There is no need for a singularity in order for the spaghettification to appear. If the "thing" inside the BH is sufficiently small enough, it will create a sufficient gravitational gradient in order for the spahettification to occur (at a certain distance form the "thing"). You would be flattened (go *splat*) only if the radius of the "thing" were large enough so that the gradient is not that prominent. However, it can be assumed that since the density of solar-mass black holes is so large that spaghettification occurs at the event horizon, there is no reason for the supermassive BHs to have a lower density - so the spaghettification will almost certainly occur, only beyond the event horizon and you won't be able to see it from the outside.

[@divyanshugreninja6692]

Sir Don I respect you very much and I am great fan of yours from India, being a middle school student , I am able to understand these but I have a question , that if two black holes merge together let us say they both are stellar black holes .................... Does sphaggetification occurs for them too , if one has a mass of 7 solar units and one of 5 solar units then , the bigger stellar black hole will attract the smaller , will the smaller black hole experience sphaggetification when it will merge with the other black hole ??

[@sureshcg8213]

Your videos are epic

[@JEE322]

What new discoveries can ensure the discoverer a noble prize?

[@thedeemon]

Figuring out dark matter and/or dark energy.

[@plexiglasscorn]

Needs experimental proof, max 3 credited people and tons of grad students involved uncredited (so much for motivation) and near infinite deep pockets at energies that are order of magnitude larger than our luckiest dreams. Hawking didn’t get it btw. Einstein didn’t get it for his theory of relativity but for photoelectric effect. But experiments confirming his theory of the gravity bending waves won him world wide celebrity status.

[@treasurecave431]

So does that mean stars orbiting a black hole close enough would be caught in the time dilation effect? Like in interstellar?

[@user-gm5xx8wr6m]

Yes, gravitational time dilation

[@stanislavvladimirsky8462]

Can we use black holes as a kind of ultimate heat sinks, dumping excess heat into them?

[@john-or9cf]

Stanislav Vladimirsky Don’t give AOC any ideas...

[@mynameisnotyours]

@@john-or9cf Pushing "trash" into a "black community"? She'd hate it.

[@maxwellsequation4887]

And make the trash can bigger till it's too big

[@ozzymandius666]

By the time we need to, that heat will be a resource to help us keep our brains running.

[@dremonX]

Sure, you put the heat inside penne, throw it into black hole and the heat is gone as soon as pasta turns into spaghetti

[@Erik-rp1hi]

I would prefer to be the Experimental physicist. I've always like building things and the challenges to make them work and to improve on the original design. The ITER project is right down my alley.

[@gunaysoni6792]

Why is there no noticeable red shifting in the blackhole images? (Matter closer to the blackhole should appear redder)

[@tufonkin2707]

Is a gravitational wave from BHs merge is catastrophic to nearby stars as it carries so much energy?

[@ozzymandius666]

It appears not.

[@Hfil66]

From what I keep hearing about super-massive black holes in the centre of every black hole, I begin to wonder if galaxies can best be thought of as accretion disks for super-massive black holes?

[@teavea10]

You touched on an interest in and study of big theological and philosophical questions about the universe. What are some of your early religious and philosophical views and how have they changed?

[@lordkekz4]

Great episode! My question: When something (e.g. a person) falls into a black hole, crossing the event horizon, would they even survive that? The part of your body inside the black hole couldn't effect the part of the body still outside, so wouldn't it slice you up? Or rather, if you were held in place by a rocket, the lower part would just dissappear into the black hole, if you then fell in completely the two parts of your body would have separated! Sorry for making you read this...

[@drdon5205]

Correct.

[@Tomas.Malina]

That's the case only for the solar-mass black holes. If you were falling into a supermassive black hole, you wouldn't really notice crossing the event horizon - you wouldn't get spaghettified or sliced up. Event horizon is not a physical thing, nothing special happens there, it is "only" a point beyong which we cannot see from the outside. The closer you would get to the black hole, the smaller radius it would appear to have. Only an observer outside would be able to tell you when you crossed it.

[@lordkekz4]

@@Tomas.Malina > The closer you would get to the black hole, the smaller radius it would appear to have. So the event horizon would seem to shrink as you fall in? Black holes get crazier every time you learn more about them xD

[@Tomas.Malina]

@@lordkekz4 yes. That is because if you look from the outside, the event horizon is a place beyond which nothing (matter or light) can escape to reach you. If you were falling into the black hole, light from beyond the horizon would be able to reach you - the more you'd fall in, the more into the BH you'd be able to see. The event horizon is a radius from which light can escape to infinity, to a place with zero gravitational potential, if we use the correct terminology. The closer you are to a BH, the lower potential you have. At a certain point, even if you would send a particle out with the speed of light, it wouldn't have enough energy to overcome the potential difference. However, if you were halfway into the BH, the particle (or light) would not need to reach the zero potential, but would only need to reach you. Therefore, more particles farther into the BH are able to reach you and you are able to see them.

[@divyanshugreninja6692]

8:58 , sir don said that matter when have a temperature of 2.7 Kelvin would emit radiation in the form of radio waves , so sir if we have a object which has a temperature of about -270.45°C which is equal to 2.7 K , then it would also be emmiting radio waves ??

[@Tomas.Malina]

That is exactly what will happen. Every object emits thermal radiation (black-body radiation, described by Planck's law). Depending on the temperature, the frequency of the radiation changes - for cold objects the emitted frequency is low and increases as the object gets hotter (so called Wien's displacement law). To be more accurate, the emitted radiation is a spectrum of frequencies - for an object that has the temperature of 2.7 K, the peak wavelength of the emitted radiation is at 1.1 mm, but many other wavelengts are emitted as well - starting at approximately 0.25 mm and going to approximately 10 mm. The most of the emitted energy is what we call radio waves (1-10mm), some of it is infrared (0.25-1mm).

[@divyanshugreninja6692]

@@Tomas.Malina thanks , I wanted to be sure that if radio waves would also be emmited from an ice ??

[@swake0019]

Dear Don, would you please explain why fusion stops with iron and it is not possible to make energy from there on with heavier elements? Thanks for you very informative series that even a novice like me can mostly understand :-)

[@ajayvallecha6236]

What is your opinion on the mystery about what came first Super massive Black holes or Galaxies?

[@samuelrodrigues2939]

Hi Don.. if light cant scape blackholes, what are those ray bursts that seem to eject from the center of some blackholes?

[@samuelrodrigues2939]

And physics is awesome.. and also want my son to take a look in experimental physics.. he likes to watch an educative cartoon 'fiksiki' (made by Russians and translated.. awesome! Highly recommended) and reproduce their ideas.. sounds like a profile? 😁

[@drdon5205]

The bursts of energy you're talking about are caused by energy falling towards the black hole that then create magnetic fields which then guides some of that matter towards the poles and outwards. The result is two jets of matter that shoots outwards, made by matter that never got in the black hole.

[@duggydo]

Since the expansion of space is increasing the wavelength of radiation and reducing the temperature, where does that energy go?

[@thedeemon]

Lost. www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/

[@nerobernardino88]

@@thedeemon I wouldn't say lost but added into entrophy.

[@cloudpoint0]

Energy is an observer-dependent measurement. If you were to travel at the same velocity and in the same direction that a red-shifted galaxy sending you light is apparently moving, voila, the light would no longer be red-shifted, you’d see it at its original frequency. The lost energy would still be there. We only see energy as being lost because we are measuring from a different reference frame than the emitting galaxy. As long as you acknowledge that you answering from your own reference frame (your only option really), you can just say the energy is lost.

[@duggydo]

@@cloudpoint0 What about the energy from places that are moving away faster than light due to expansion of space? Is it negative energy now?

[@MuttFitness]

@@duggydo you'll never see that light, so why would you describe it as lost?

[@paineoftheworld]

Good video. I would like to thank you. For what it's worth, I agree that it's not a good argument to drawn into.

[@samuelrodrigues2939]

Hi Don.. just curious what ur findings were in ur other minors.. i question myself a lot on those questions but never had the discipline to dive deep on them.. such as theology, i dont know about the scientif part, but some things are (to me) undeniable and some unbelievable things happened to some people (and i dont think they are lying) as some also happened to me when i was a child

[@WillyIlluminatoz]

For outsider observers, we that pass event horizon of BH may be dead, but from our frame of reference, we still alive and safely entered the event horizon. I have read a theory that explain it like that.

[@fontainenick]

Suppose we had a superconducting, super strong wire. Could we use it to lower a camera past the event horizon of a supermassive black hole for imagery?

[@TvL2386]

Since the gravity is so strong not even light can escape, I assume it is impossible to create a wire strong enough to resist being ripped apart. Edit: I'm curious though what would happen if it and the camera were infused with unbreakable stats

[@Alexagrigorieff]

Information over a wire is carried by electromagnetic wave (photons). It will take infinite time (for the outside observer) for the photons to cross the event horizon.

[@KohuGaly]

Yes, but we wouldn't be able to pull the camera back out and neither could the signal travel up the wire.

[@Vodouch1]

"Nothing can escape" just means you have to have speed greater than "c" to escape on your own. I dont see reason why you could not. On the other hand you would see just few fotons on the way down and lot of nothing. Vsauce kzbin.info/www/bejne/aaGkn4WBeZmll7s

[@juijani4445]

Let me guess, a video on the newly discovered (well, it's been a while now but still) "tetraquark" next week?

[@clancyjames585]

Upvote this comment please!

[@quickphysicsvids239]

Isn't the temperature of space also to do with the temperature which an object, when left in space will tend towards? I believe it's the same temperature but it's a slightly more intuitive perspectove on it.

[@cloudpoint0]

Yes, in a universe without stars or hotter things to radiate more energy on to the object the temperature should be that of the CMB. Without the CMB and all else I'd expect the temperature to as near as possible to 0 K.

[@jayblake682]

How do I know black holes exist? Because Rush described it on “A Farewell to Kings”. That’s all the proof I need.

[@jacobgonzales28]

Would spaghettification be counteracted if the change in gravitational force on the person falling into a black hole is met with the closer section of them having time slowed down... so they feet would actually experience that increased gravity for a shorter amount of time?

[@narfwhals7843]

Time dilation is actually the reason for the gravitational force in the first place. The difference between time at your head and your feet is what pushes you towards the ground. Near a large mass that difference is much bigger across your feet than it is across your head so your feet are being pulled more strongly and so are being pulled away from your head(assuming your feet are pointing "down"). Time slowing down _causes_ spaghettification.