What are black holes?

[@zhadoomzx]

The name Schwarzschild is actually cooler than you might think... it is not pronounced with "child" at the end (Like Mr. Lincoln and many others do) but rather "Schild" which is german for shield. And since "schwarz" means black, his name literally translates into "Mr. Black Shield". What a crazy coincidence that his...

[@willemvandebeek]

+

[@madspetersen1708]

And Schwarz is pronounced Svarts

[@unduloid]

@@madspetersen1708 Nope, it isn't.

[@cornflake75]

It's pronounced more like "shwartz shill'd"

[@ExternusArmy]

@@cornflake75 schvarts is how it’s pronounced.

[@jovanweismiller7114]

You know, Dr Lincoln, I almost filed college physics 50 years ago, but I greatly enjoy your videos. Despite my ignorance, I learn something from every one.

[@michaelblacktree]

Always a pleasure to get another video from Dr Lincoln. 👍

[@oysteinsoreide4323]

Could you show numbers in the metric system please?

[@caioeduardo6660]

Yes they really should use metric.

[@misterphmpg8106]

Both

[@oysteinsoreide4323]

@@misterphmpg8106 yes, both is probably best. It's mostly USA that still use the imperial system. Most of the rest use the metric system.

[@deltalima6703]

Scrap miles and slugs and furlongs and stadia and all those ancient units. Better off without them.

[@nerdsofgotham]

Fermilab putting out top shelf educational content for anyone to watch and understand. What a wonderful time we live in.

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@andrashajdu]

Please use SI / metric system in science videos

[@flankman9385]

No.

[@andrashajdu]

@@flankman9385 😂😂😂

[@Dragrath1]

Note that the appearance of the singularity in the Einstein field equations is dependent on the choices of initial assumptions specifically it arises in the limiting case of the Schwarzschild or Kerr metrics which are particularly symmetric limiting cases assuming that the massive body is the only object in the universe. We thus know this is a limiting case as our universe doesn't just contain a single black hole so this doesn't mean it will be accurate at all distances all we can say with any confidence is that it holds remarkably well out to the distance of the photon sphere for supermassive black holes like the ones at the heart of our galaxy or M87. Interestingly recent work based on taking the limit of black holes going to one finds that hawking radiation does somehow escape likely via a mechanism linked to ER=EPR so clearly there is something special happens outside the Schwarzschild or Kerr metrics in regular unaltered general relativity. It doesn't tell us what it is but that there is something more and at the very least ER=EPR mechanisms appear to be a much more general thing that doesn't depend on the constraints of any additional extension to the theory of General Relativity. One potential theorem which may enlighten this discussion is the No big Crunch Theorem published by Matthew Kleban and Leonardo Senatore which at least in the case of very large Universes (in the limit of the size of the universe approaching infinity) that any arbitrarily non trivial universe can never have an universal inflection point in the direction of expansion which means that the Einstein field equations in order to be logically internally consistent (i.e. for information to be conserved) the metric tensor must always be fully asymmetric i.e. no terms within the metric tensor can ever be identically zero. iopscience.iop.org/article/10.1088/1475-7516/2016/10/022/meta One important consequence of this is that all initially expanding Universes must at large scales always expand forever that is to say that while the net effect of matter concentrating together may locally impede the expansion of space the resulting underdensities will always be enough to overcompensate this slowdown resulting in the overall expansion of the general unconstrained Einstein field equations always accelerating. Simulations show this is notably always true regardless of the initial choice of the cosmological constant and thus as such we can completely explain the acceleration of the observed expansion of the universe without needing any additional component of dark energy, its just the asymmetric off diagonal components to the metric tensor. We don't need to stop there however another consequence is that the lack of any global maximum on expansion means that the differential volume of the universe between any two time slices shares the same sign as those timeslices. If we recognize the speed of causality being finite and thus a finite volume which information on the universes initial conditions can propagate, as well as the need for said information to exist somewhere within any time slice of spacetime we can derive the associated gravitational path integration over time slices with a representative volume of that timeslice which can have interacted causally or the dot product of the path integration through the surface area of that timeslice which should correspond to the cosmological event horizon will always have an associated entropy based on the universes initial conditions. This means we get Hawking radiation by default within the unconstrained Einstein field equations whenever we explicitly enforce conservation of information. Note that this doesn't mean you can transmit information faster than light if anything it tells us the Einstein field equations exhibit informational symmetry which causes acausal correlations based on entanglements of past light cone interactions. That is to say General relativity if taken explicitly as Einstein derived with no prior assumptions is fundamentally superdeterministic and should always obey Bells inequality. Sadly this means Bells "free will" clause must always be violated else the metric tensor must be logically discontinuous i.e. information can not be conserved. Mathematically there is no way around this criterion it is a mathematical proof which applies to any system of differential equations organized like the Einstein field equations and can be shown to be a required symmetry of such a system under Noether's theorem. The mind trippy consequence don't stop there however as this nonlocality and causality together require there to be a minimum nonzero contribution to the metric tensor for every bit of information within the initial conditions of the universe in other words gravity self quantizes itself under the conservation of information. From a model perspective this tells us gravity at large scales must deviate from Newtonian gravity because these minimum contributions to the metric tensor don't dilute with distance and thus as the source proximity dependent effects drop off the nonlocal components begin to dominate. Those familiar with MOND may recognize some of these implications which suggests "dark matter" like dark energy may actually be some of the distant contributions of the metric tensor in this case the additional diagonal contributions to the metric tensor. However this only allows the quantization to consist of nonzero asymmetric terms meaning that quanta of spacetime must at least partly behave as Dirac spinors a.k.a. Fermions. All boson based models of quantized spacetime which assuming spacetime fluctuations themselves are the gravitational field means all bosons not based upon a separate quantum field are logically forbidden which may explain why efforts to find a gravitation have always failed. Perhaps this means the universe is built out of gravitinos? I don't know how to interpret the meaning of this but I do know that one mathematical consequence of this is that all quanta of the metric tensor must have a unique and distinguishable quantum state i.e. they must obey the Pauli exclusion principal. In other words the Cosmological principal was fundamentally wrong because it got the order of the Copernican principal wrong our local metric is unique but we are not special because every other place in the Universe is too. It also implies spacetime should become degenerate at some distance scale which given all our observations and a powerful enough supercomputer should be calculatable. And the best part of this is while it solves many mysteries in cosmology it effectively involves no new physics as it is just the properties which the set of all valid solutions to the exact nonlinear domain of the full unconstrained Einstein field equations must have in order to be internally self consistent. The con is of course we can't approximate the Universe at large scales as approximately the Friedmann Lemaitre Robertson Walker metric. But observations have already pretty convincingly cast doubt on that assumption best seen in Nathan Secrest et al 2021 which showed that the CMB dipole must contain a significant cosmological component meaning the CMB alone is enough to falsify the cosmological principal within the entire observable universe. iopscience.iop.org/article/10.3847/2041-8213/abdd40#apjlabdd40s4

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct 👆✍️

[@duckydude20]

i am glad we have people like you. from a software developer's perspective math does not makes sense for me. but this whole idea its so fascinating. quantum gravity and what not...

[@duggydo]

I see you have reuploaded. My question on the 1st upload about escape velocity decreasing inside the radius of the Sun was answered with this video. Thanks 😉

[@drdon5205]

What was previously plotted was force. Mea culpa.

[@duggydo]

@@drdon5205 ah! That makes sense. No worries. You make some of the best physics videos out there. Always look forward to them. 👍🏻

[@marioluna2957]

Santa Lincoln rocks

[@youtubeurevil]

@DrDon I wish I had a physics teacher like you in my schooldays I would have learned something then . I devour all of your little lectures (never to late) they`re excellent please keep on posting !!! thanks eric

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆 ✍️

[@ricardodelzealandia6290]

What's a "miles per second"? Isn't that what the romans used?

[@waynecribbs8853]

Please use metric units, or at least provide both! Looking forward to part 2.

[@nneeerrrd]

Up!

[@KonekoEalain]

Just do the math.

[@michaelsommers2356]

If you really think that the system of units you use makes a difference, then you don't understand physics, or science, at all. I suppose you want particle physicists to stop using natural units, too (where _c = G = h-bar = 1),_ and you want astronomers to stop using parsecs and arcseconds and redshift and solar masses as units. It makes so much sense to give the distance to a distant galaxy in meters, or the mass of a supermassive black hole in kilograms.

[@waynecribbs8853]

@@michaelsommers2356 What a silly strawman argument you invented. I didn't say any of that. What I'm suggesting is that the video use the units that MOST of the world intuitively understands (metric), instead of only catering towards a US audience.

[@KonekoEalain]

@@waynecribbs8853 Do. Math.

[@Psychx_]

I always think about the inside of black holes as non-euclidean geometry. The thing may be bigger on the inside than its radius or observable "surface area" suggests.

[@KonekoEalain]

Can't wait for the next black hole video, thank you Don!

[@cribbsprojects]

Your presentations always give me a great understanding of the subject - with the least amount of effort on my part. Wonderful outreach teaching!

[@lucaitaly1975]

nice video but pls avoid those non standard imperial measure units... miles? inches? why?

[@piratk]

This version made a lot more sense!

[@giriprasadkotte9876]

Dr. Lincoln is the super star of physics communication

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆 ✍️ .

[@ilkoderez601]

I love it when Don pops up in my subscription feed!

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆 ✍️

[@ShannonMcDowell71]

I wonder if the characteristics of neutron stars could help us glean the nature of black holes. Neutron stars are rather extreme too, given their density and gravitational fields.

[@ChristopherCurtis]

I think there's a lot to learn in the nuances of what we think we understand. PBS Spacetime has an interesting video about stars made of strange quarks here: kzbin.info/www/bejne/q2W1f3qIrt-nZ5I It seems unlikely that stable things like this exist in the universe - or at least, not for very long - but if true there are likely many states that objects transition through as they "phase change" from one Type of object to another.

[@ShannonMcDowell71]

@@ChristopherCurtis Thank you for the comment and link, I'll check it out!

[@peterkelley6344]

@@ChristopherCurtis There is also Dr. Becky who just released a book on the current understanding of Black Holes.

[@XXveny]

Well, the heaviest neutron stars can really eventually turn into black holes once they are compressed enough.

[@vanikaghajanyan7760]

On the horizon, the parameter rG/r=1. Here, Schwarzschild's solution has a distinctive feature as g00(rG)=0, g11(rG)=, when r

[@vanikaghajanyan7760]

However, Schwarzschild's solution: e-λ=еν=1+A/r (the constant A can be defined from the result according to which in a weak gravitational field g00~1+2ф/c2, where ф=-GM/r -Newtonian potential) satisfies this requirement. So, A=-2GM/c2, and consequently, e- λ=eν=1-rG/r, where the gravitational radius of the celestial body rG=2GM/c2. Consequently: 2E0/rG=Fpl=c4/G=εpl/rpl=ħw2pl/с=4ф2pl/G=4FGpl , where: фplG=(-1/2)c2=(-1/2)[Għ/с]1/2wpl ; with indicating the mutual quantization of the mass (energy) of "rest" and space-time: m0/mpl=rG/2rpl=n, where n=0,1,2,3..., number of quanta.

[@vanikaghajanyan7760]

From this (generally, from Einstein's equations, where the constant c^4/G=F(pl), and without the need to involve the concept of curvature of space-time) one can obtain a quantum expression (as vibration field) for the gravitational potential: фG=(-1/2)[Għ/с]^1/2(w)=-(1/2)[w/w(pl)]c^2 : "Containing all information about the gravitational field." (Einstein).

[@vanikaghajanyan7760]

Moreover, the parameter r0=rG-rpl=(2n-1)rpl: defining the interval of the formation of the system, at n=0, when the gravity packing coefficient n/n'=0, и rG=r=0 (for example, the state of the universe before the Big Bang), turns out to be a quite definite quantity: r0=-rpl. In the area [(-rpl) - 0 - (+rpl)] there is an implementation of external forces, "distance": (-rpl)+(+rpl)=0 (≠2rpl).

[@vanikaghajanyan7760]

This is amenable to physical examination in laboratory conditions at present. A lead ball suspended on a strong chain from the ceiling of the laboratory can serve as a test body; at radius r=27,6 cm, ball mass is m=1т. According to the formula for the gravitational potential, the energy of quanta/photons of the field (photons are characterized by different parity and helicity, and it is not quite accurate to say that a photon has an integer spin equal to one) at a distance r from the center of gravity of the test body to the detector (practically on the surface of the ball) =66,3 keV. The flow: J=0,45*10-8 quanta/сm2c; this is a measurable flux for modern world-class gamma detectors.

[@vanikaghajanyan7760]

And to the question: where does the energy of the field (quanta) come from, it should be noted that, since the effect is ultrarelativistic, the source is a physical vacuum (see on the Kruskal diagram, regions V and VI, which are not even covered by global space-time). Without taking into account the vacuum, the ordinary Universe cannot be considered (thermodynamically) a closed system. A non-closed Universe can be represented as an oscillatory system, and if the time t is explicitly included in the differential equation of motion, then it is a non-autonomous system.

[@juzoli]

Is it a reupload fixing some mistakes?

[@drdon5205]

Just one. But yes.

[@brothermine2292]

Fixes the error about escape velocity inside the sun. The earlier video said it decreases inside the sun, but it continues to increase as the objecr approaches the center. It's the gravitational pull that decreases, not the escape velocity.

[@juzoli]

@@brothermine2292 Yeah, I raised that question in the comment section of the original video too. They took real effort to fix it, not just a short text that they are aware. They actually reshoot the whole part if the video.

[@InfiltrateIndustries]

I expected Fermilab to do something else and convey it with some enthusiasm. Why isn’t this more engaging?

[@carlbrenninkmeijer8925]

Thank you. I had a colleague from Switzerland. He always entered the low level Tritium lab in a splendid mood and said "why not try the simplest first?"

[@rolandsv8]

This man is the first one i have heard who says that concentrating all that mass and real particles in infinitely small space of singularity is absurd

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@sadakotube]

this is a reupload isn't it? i have a deja vu that i watched this about 12+ hours or so ago. Edit: read the description. lol

[@immanuelburgstaller5944]

I like the humility of Mr Lincoln is explaining physics, without that aura of I have knowledge and I'm superior to you who don't have this knowledge. I agree with your points you listed concerning black holes. But I have two questions: - if all the mass of a black falls into the singularity, then what defines the width of it radius of its event horizon? in other words why do they all have different sizes? - have we ever consider that mostly the most gravitational bodies in space are almost spherical and the black hole is not an exception? Isn't it that this tell us much about what matter consist a black hole, and that there no something as singularity, but the whole body of a black is gravitationally strong as in any point you take in the black hole?

[@snappycattimesten]

Miles? Miles?? I like my units in rods and hogsheads.

[@nickmk11]

Excellent video. Please try to use metric as well for all of us outside the US. The “metric crowd”, as you call it, is 7.5 billion people!!!

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆 ✍️

[@radupaulalecu4119]

Can't wait the mind blowing clip!

[@BariScienceLab]

Hi, I made a video about the moon: kzbin.info/www/bejne/Z3KngHx4j6l7ick -- I would love to hear your feedback!

[@RubenLopezG]

How come gravity is considered the weakest force but then electromagnetism (and possibly other forces) are incapable of overcoming the pull of a black hole?

[@ScottLahteine]

A zillion gravities will be larger than a few electro-mageneties. A hundred weaklings can easily beat up one lone strongman.

[@RubenLopezG]

@@ScottLahteine in that case, if you have two black holes with the same (huge) charge, their charges would repel and overcome the mutual gravitational pull? 🤔

[@Mysoi123]

In the quantum realm, the mass of particles is too low to generate enough gravity therefore other forces dominated the realm, chemical bonds and structures are not held by gravity but electromagnetism. When we compared gravity to the other forces, we are comparing the average strength of gravity and electromagnetism between two particles.

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct 👆✍️

[@beeheart6529]

Do you know who designed that graphic of a black hole? It’s amazing.

[@spbalance]

It was visualized by the VFX studio Digital Negative during work on Interstellar. It's the result of feeding the relevant equations through an in-house developed simulation. It was deemed so accurate that it has sort of become the accepted standard visual representation in science. You should watch the movie.

[@beeheart6529]

Thank you so much!! How amazing.

[@fvckyoutubescensorshipandt2718]

The secret sauce of black holes is their "surface" or event horizon is very close to the center of all it's mass. That distance difference compared to most objects like stars and planets makes a huge difference when combined with the inverse square law. If Earth was a black hole a bit under 18mm across and you could get within 3 mm of the event horizon of course you are going to have a bad day. You just went from 1G at the surface about 4000 miles from the center to 12mm from the center, almost 600M times closer = gravity pull will be almost 3.6x10^17 times Earth's surface gravity, enough where your body size is enough to cause it to get ripped apart from tidal forces. Even 400 miles from it will still be 100 G's of sustained acceleration = that alone will kill you rather quickly, even if it didn't rapidly increase as you fell closer. The same math counterintuitively makes bigger black holes (ie a million suns in mass) kill you slower, since you can actually get inside the event horizon and survive a few more minutes, until you encounter either the same problems as a small one as you fall closer to the center or if the bh is really huge (ie 10B suns) you roast in quark-gluon plasma when you hit the inner horizon before being ripped apart by tidal forces.

[@dankellis1]

Wouldn't the increasing curvature of space and time around the singularity prevent density from becoming unbounded?

[@inyobill]

I should have looked through the comments before I posted mine. In my naive intuition (I deeply distrust my intuition in these questions), it seems plausible.

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct 👆✍️

[@XEinstein]

So I am well aware that we need a theory that combines GR with QM at the location of the singularity, but at the moment I'm wondering if we know for sure that at that scale gravity must be quantized? QM gives us the explanation why energy states of particles must be quantized, but is there anything that dictates the gravity must be quantized as well?

[@ramkitty]

There are scalar and functorial field theories math beyond me but my minimal familiarity summary had unitless field maps across space while fitting qft standard model. I don't know if that geometry would be considered quantized. The Higgs and non relativistic gravity are both scalar fields having no direction varying over time in space.

[@lukaspriyambodo]

A black hole is moving from point A to point B. What happens to the space around point A after the blackhole moves from point A to point B? Is it back to normal? Twisted? Or else?

[@kaitlyn__L]

LIGO and VIRGO detection results suggest space has an elasticity and settles-down again, but with regard to your question that’s just hoping their influence while minding their business is qualitatively similar as during a merger, since that’s all we can currently detect. To see smaller gravitational waves from less-energetic events, we’d need detectors with a much longer distance between them in space, various fractions of our solar system. There’s various hypothetical near-future-y proposals to do the first one in various lagrange points I believe. The ultimate maximum would I suppose go from one end of the Oort cloud to the other? Though if we could build that I suppose there’d be no reason not to build even longer ones in the interstellar medium, so perhaps there’s no limit except for how precisely we can align lasers in space and how well collimated our emitters are.

[@ranjith6902]

Enough if your ordinary theories.. we want more! 🤣🤣 Great Video Sir! We expect a lot! Kudos! 👍👍👍

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@WINGNUT307]

A good explanation of escape velocities. What's to stop an object inside the event horizon with a velocity near the speed of light away from the singularity, popping back out through the event horizon and going some way before falling back in?

[@goestovbhudi8716]

Spacetime inside the event horizon "folds in" on itself, and there is literally no way out.

[@ignacioniveiro5471]

I think it's evident all matter is concentrated in a point within the black home, but it's also evident it cannot be a dimensionless point. It has to have some volume, so matter must have a maximum level of compression. I guess it must be when everything is made of truly fundamental particles each next to the other, as they cannot overlap (since they are fundamental).

[@tybeedave]

it is no longer matter after it traverses the event horizon, it is pure energy (photons) which can occupy the same space.

[@ignacioniveiro5471]

@@tybeedave by what mechanism would matter convert to pure energy in the singularity without the necessary presence of antimatter? A number of symmetries would be broken!

[@tybeedave]

@@ignacioniveiro5471 symmetries are made to be broken. lol just kidding. seriously, i was always taught that when mass accelerated to the speed of light, it becomes energy. recent published work show how time is flattened with acceleration. upon reaching c, it becomes 2 dimensional and timeless. it is then energy. in a matter/antimatter decay the photons are released from confinement. when an electron is in a high enough energy environment and are next to timeless near the event horizon, there are plenty of positrons available. protons have a positive charge, 2/3 of quarks are positive. it takes no genius to see that positrons must be in their ingredients at their creation. say u don't see that in any textbook? welcome to new physics :)

[@tybeedave]

the conversion of mass to energy occurs at the event horizon, not at the singularity

[@dimitrispapadimitriou5622]

Again, at 6:10, No, the singularity of a Schwarzschild black hole is Not a " point at the center of the black hole where all the infalling matter is compressed there "( or anything like that..). Once again: Schwarzschild singularities are spacelike, they're not " points in space " or places. They occur after some specific amount of proper time and the reason is that spacetime geometry is dynamical ( time dependent) in the interior, even if it's approximately static from the outside.. The curvature singularity is the catastrophic finale that happens, unavoidably , as the timelike coordinate "r" goes to zero. Actually, it's very easy to see this with the curvature scalar, that blows up at r=0. So, the collapsed matter is not " concentrated " anywhere, actually. What GR predicts is that any object that has some finite size ( i.e. that is not a "test particle"), is finally torn apart by immensely strong tidal forces. Not only its remains do not compressed at a single point, but , instead, they become eventually causally isolated from each other, as they approach their final moment at r=0. The end occurs when every tiny isolated piece/ remain of the infalling object is destroyed completely and the overall net volume vanishes .

[@deltalima6703]

Its kind of tricky to be fair. Schwarzchild coordinates start at zero on the event horizon and give a few erroneous ideas of what happens there but they are simple. Penrose coordinates give much more detail, display the space and time swap, and extend within the event horizon. Might be called kruskal-szekeres cordinates, been several years since i looked at this. Curvature is fairly obvious though, everyone gets that. People are not dumb, they know newtons stuff is only an approxamation, and only useful for things that are slow and small, but not too small. Newton himself knew it needed a "force at a distance with no medium" and could not be the final answer.

[@dimitrispapadimitriou5622]

@@deltalima6703 No, Schwarzschild coordinates Do Not " start at zero on the event horizon". The so called " coordinate singularity" at the horizon ( r=2m ) is only an artefact of this specific coordinate system. Nothing funny happens there.. The true " curvature singularity" is at r=0. In the "Eddington/ Finkelstein" coordinates ( or other coordinates ) the horizon is perfectly regular. Generically, the coordinates do not have an intuitive physical interpretation in General Relativity. You can choose whatever coordinate system you find convenient, assuming that you're doing the math correctly. The " r " coordinate ( that is sometimes called " the area radius" ) is Not a physical distance from a geometrical center, not even outside the horizon! By the way, these are very old news! We're talking here about standard textbook GR stuff. I'm not sure what's going on with all these popularized videos that , supposedly, are intended to " clarify some misunderstandings" and they end up repeating the same misconceptions again and again..

[@giovanniguaitini7454]

There is something about "escape velocity" that confuses me: it is always assumed that the object has an initial velocity at time zero and no force from that moment on. But like in a scifi movie, according to classical mechanics, if we were able to apply a constant force superior to the gravity at the starting point, we could escape at any speed, even very slow, right? So, theoretically, neglecting the feasibility of course, even inside the event horizon we could escape if a constant force superior to the gravity there could be applied, we don't really need to go faster than light.....of course this must not be true, but why? Is there something specific to general relativity?

[@trescatorce9497]

as you apply a constant force, you also get an acceleration proportional to the applied force, and inversely proportional to the mass of your vehicle (Newton's 2nd Law, no relativity is necessary). To overcome the gravity of the black hole, an infinite force or a tiny force applied over infinite time are needed. In GR, time is just another dimension, and time is "stretched", for lack of a better word, in a strong gravitational field. So here is the mess= the time needed to apply the tiny force gets stretched, and then you need infinite time to escape velocity. No way out. On the plus side, zero and infinity are mathematical constructs.

[@misterphmpg8106]

It is much simpler: either your reach the escape velocity to escape or you don’t reach the escape velocity and you simply don’t escape. It doesn’t matter how you reach the escape velocity or how long you need to accelerate to get that speed. If you constantly accelerate then you will always at some point in time reach the escape velocity and hence you will always escape. Except if the escape velocity is the Speed of light. There is no way to accelerate an object with mass to the speed of light. Period. That is nothing new. So what is your question or problem?

[@giovanniguaitini7454]

Of course my initial statement is wrong, general relativity applies here, but let us put aside general relativity for a moment and imagine this: i am on the surface of the earth and apply a constant force of 9.9 m/S2. Since earth gravity on the surface is roughly 9.8 m/S2 , do we agree that i will eventually escape to space and leave the solar system? It is like going on an elevator.... So, when i think about relativity, I know that there is an upper limit to speed, not to force. Inside the event horizon, there must be a finite force in any point, very big but finite. If I had a propulsor even slightly stronger than gravity, with classical mechanics I could still escape at a tiny speed. Probably, as someone pointed out, with relativity it is the curvature of space and stretching of time that prevents the object from escaping.

[@denmaroca2584]

Yes. The path any object takes in spacetime is determined by the curvature of the space it is moving through. A net force provides an acceleration in a particular direction and that can change the path. However, within the event horizon the curvature of spacetime is so extreme all possible paths (called geodesics in GR) end at the singularity. It doesn't matter what direction you were initially moving in or what direction you accelerate in, you will still end up at the singularity. Another way to think about it is that the singularity is in the future of any object within the event horizon. And it's not an indefinite future either!

[@imnottushiro9539]

I get your point. You would be right considering Netwon´s law of Gravitation. But Newton#s law does not apply to this case.

[@mastafaforga]

Would the core of a black hole be absolute zero, or close? What form does the energy take after being absorbed by a black hole? If particles vibrate, but the gravity is too strong for any oscillation to be in the direction away from the center of the black hole, then wouldn't subatomic motion cease when they reach the center? If so, would that mean energy is being destroyed, and not by hawking radiation, but by the energy's inability to resist the gravity? Would gluons, quarks, electrons, etc... merge into a single massive unmoving particle? Wouldn't that break quantum mechanics, and if so how would the mass still exist?

[@user-ef5me8hm7o]

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[@Robinson8491]

Nice subject fermilab, keep m coming

[@SerendipitousProvidence]

This is really well-known, huh? My classmates were whispering and giggling about black holes in the back. It struck odd to me since they were jocks, not the ones to shoot a breeze about nerdy stuff.

[@sadakotube]

or likely referring to a different form of black hole.

[@a.m.6996]

That wasn’t the black hole shown in this video

[@TerryBollinger]

7:17 "an object of infinite density ... doesn't make any sense." One way to keep GR intact while avoiding singularities is to assume spacetime is a collective behavior of matter. This constrains GR from generating details smaller than the densest possible state of matter, quark-gluon plasmas.

[@XXveny]

Yea... infinite density is just some fairy-tale that could explain how singularity was infinitely small point from which big bang emerged. Surely this "singularity" was just a extremely dense black hole with perfectly finite density. The real question is, whether size, shape, space or time-space were relevant things in stage of "universe" (or proto-universe). See, if volume of object is zero (which does not make sense, i know), the density of object must be infinite. Everything higher than zero, means finite density. So, even if you somehow compressed whole universe into object that would as big as one atom, its density would still be perfectly finite. Huge, but finite.

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@jerrygundecker743]

Dr. Lincoln have you done a video about what the JWST is orbiting?

[@PetraKann]

Excellent presentation

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct 👆✍️

[@konnor9577]

What is the Gravity at the hypothetical surface of the black hole (at the exact point in its radius where light can't escape... event horizon)?

[@Pottery4Life]

Don, do you know how unfair it is for us to automatically try to convert to SI on the fly?

[@deltalima6703]

Ikr. Just say 0.1c if you cant do in m/s for gods sake. Lol

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct 👆✍️

[@Krebssssssss]

I’m gonna start a petition for Dr. Lincoln to bring back the mustache.

[@jackjohnson6884]

Sometimes, they are mostly dangerous to other black holes and yellow holes then white holes too

[@thomasstrawser8095]

I wish we could get weekly videos.

[@kasuha]

Another I think important or at least interesting fact is, if Sun was replaced by equally massive black hole, we wouldn't even be able to see it with naked eye from Earth, or, in case it had accretion disk, like a bright dot at best. Definitely not any of those cool effects we get to see on various black hole animations except when using really good telescope. With 2 miles in diameter, it would be 1500 times smaller than Mercury.

[@klikkolee]

I have been thinking about the fermions of the standard model. They come in groups of 3, with most properties being the same within a group, but mass increasing from one member to the next. This to me screams that we're looking at the first 3 members of an infinite series. That is, if up quark were renamed to U1, the charm quark to U2, and the top quark to U3, then there would be a U4 quark with greater mass than U3, a U5 quark with greater mass than U4, etc. ad infinitum. Same for the down-type quarks and the leptons. However, in the material I've seen on neutrino oscillations, including on this channel, the oscillation of neutrinos seems very firmly grounded in there being only the electron, muon, and tau neutrinos. Given that neutrinos seem to be paired with corresponding charged leptons, that strongly implies that the electron, muon, and tau are the only charged leptons. Are there any other physical phenomenon which implies that there are only 3 generations of leptons? Are there any mathematical symmetries which point to there only being 3? And is there anything similar pointing to there only being 3 generations of quarks?

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@BlackHole-qw9qg]

The 3 generations of quarks and leptons are actually one of the greatest unsolved mystery in particle physics

[@brothermine2292]

In the Star Trek universe, black holes probably do suck in orbiting spaceships, because even planets do. An early Star Trek episode established that orbits quickly decay if a spaceship's engine is turned off, and the Star Trek franchise has been stuck with that major goof ever since then.

[@Psychx_]

Pro tip: Read German '-schild' in "Schwarzschild" as '-shield' - this matches the intended pronounciation better.

[@PhilipSmolen]

Is this a repost? I'd swear I saw the same thing on this channel 3 days ago. I was hoping this was part 2.

[@victorreis8110]

I really want to know more about this “space and time switches”! what source should i go to?

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆 ✍️

[@shawns0762]

For some reason people don't know that Einstein said that singularities cannot exist. In the 1939 journal "Annals of Mathematics" he wrote "the essential result of this investigation is a clear understanding as to why the Schwarzchild singularities (Schwarzchild was the first to raise the issue of General relativity predicting singularities) do not appear in physical reality. Although the theory given here treats only clusters whose particles move along circular paths it does seem to be subject to reasonable doubt that more general cases will have analogous results. The Schwarzchild singularities do not appear for the reason that matter cannot be concentrated arbitrarily. And this is due to the fact that otherwise the constituting particles would reach the velocity of light." We have all heard the phrase "mass becomes infinite at the speed of light". This phenomenon is illustrated in a common relativity graph with velocity (from stationary to the speed of light) on the horizontal line and dilation (sometimes called gamma or y) on the vertical line. Mass that is dilated is smeared through spacetime relative to an outside observer. Even mass that exists at 75% light speed is partially dilated. Wherever you have an astronomical quantity of mass, dilation will occur because high mass means high momentum. Einstein is known to have repeatedly spoken about this. Nobody believed in singularities when he was alive for this reason. There is no place in the universe where mass is more concentrated than at the center of a galaxy. 99.8% of the mass in our solar system is in the sun. 99.9% of the mass in an atom is in the nucleus. If these norms are true for galaxies than we can infer that there is 100's of trillions of solar masses at the center of common spiral galaxies. There is no way to know this through observation, there is far too much interference, dilation and gravitational lensing. If we attribute a radius to these numbers than we can calculate that relativistic velocities exist in these regions. According to Einstein's math the mass at the center of our own galaxy is dilated. In some sublime way that mass is all around us because as the graph shows we are still connected to it. A fundamental question is "why can't we see light from the galactic center?" The modern answer is because gravitational forces there are so strong that not even light can escape (even though the mass of the photon is 0) Einstein's answer would be because the mass there is partially or completely dilated relative to an Earth bound observer (not onto itself).

[@narfwhals7843]

Einstein also said Gravitational Waves cannot exist. Einstein was wrong about things. That doesn't mean singularities _must_ exist. But Penrose showed that they are a necessary consequence of General Relativity.

[@shawns0762]

@@narfwhals7843 Relativity does not predict singularities when you factor in dilation. It doesn't matter what anybody said. We all learned that mass will dilate when it approaches the speed of light in high school, that's it in a nutshell.

[@narfwhals7843]

@@nemlehetkurvopica2454 we don't 100% know that singularities aren't real. We just don't like them. But we have no right to demand their non existence. The singularity at r=0 is real in general Relativity. The coordinate singularity is not. We can _hope_ a unified theory won't have singularities anywhere, but we can't enforce it.

[@shawns0762]

The greatest mystery in science is the abnormally high rotation rates of stars in spiral galaxies (the reason for the theory of dark matter). It was recently discovered that low mass galaxies (like NGC 1052-DF2) have normal star rotation rates. This is what relativity would predict because there is an insufficient quantity of mass at the center to achieve relativistic velocities. This is virtual proof that dilation is the governing phenomenon in galactic centers, there can be no other realistic explanation for this fact. The missing mass is dilated mass.

[@shawns0762]

@@nemlehetkurvopica2454 Anyone who understands relativity knows that relativistic mass is BS, the phrase "mass becomes infinite at the speed of light" doesn't mean that increases at the speed of light.

[@CsendesMark]

so, the first version of the video was incorrect with the "inside the Sun" part? I can clearly hear the change in the sound of the video 3:27

[@narfwhals7843]

Yes. They made a mistake and corrected it.

[@user-ef5me8hm7o]

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[@rogeriorogerio1007]

Why is time dilation never addressed in those videos? Would be nice to cross an event horizon and witness the universe history unfold completely.

[@ZubairAhmed-yw5zg]

Yea!! Exactly, what if time maybe slows too much that it's negligible, inside a black hole!!?

[@hartunstart]

Indeed, I like to think whatever falls into a black hole, actually falls into the future and that's why it never comes back. But maybe, from there you can't have a very good visibility to the external universe - and not so much time to enjoy the show.

[@ZubairAhmed-yw5zg]

@@hartunstart yea , maybe all the objects will be in a standstill until the eventual death of a black hole(if it was has one), and they get released in that time

[@filonin2]

A consequence of seeing the entire universe's history unfold in fast motion is that the radiation is all blueshifted and you are fried by gamma rays that once were the CMB.

[@kaitlyn__L]

@@filonin2 So we just need to go there in a spaceship with enough shielding and realtime Gamma ray imaging!

[@RGAstrofotografia]

Could you show and explain the graphic for tidal force, like this of scape velocity, in the next video? Thanks!

[@user-ef5me8hm7o]

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[@keepcalm7453]

Dear Sir, about using a little bit more math in your content, you could have gone a little more into math in this video where correction regarding escape velocity from inside the sun has been made.... Love Fermilab content..💝🙏🙏💝

[@brothermine2292]

Unfortunately, our comments on the earlier version of this video appear to be lost.

[@Eldjarn86]

This gramps is Wendigoon for science! Been watching for 2-3 years

[@mikegargan967]

Love all your videos, you have fantastic content. However, is there any way you could try to remove some of the mouth clicks? Your other videos don't have much, but this one in particular had so many mouth clicks that I couldn't finish the video.

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@davefoc]

The idea that there is a maximum possible density of matter is interesting and just based on gut feel it seems that it is true. I was wondering about this today with regard to light. I was an electrical engineer and we are usually told that there is no maximum concentration of light. And for an engineer who is mostly concerned with the practical consequences of knowledge that is close enough to true that it is true for our purposes. But at the extreme it seems that it probably isn't true. One thought is that at the extreme light and matter are not distinguishable and might be the same thing?

[@narfwhals7843]

Light and matter aren't the same thing as such. But they share some properties. One of these properties is energy. And energy curves spacetime. So light gravitates. And this means that you can make black holes from light. So the maximum density of light would be when it forms a black hole.

[@davefoc]

@@narfwhals7843 "Light and matter aren't the same thing as such." 🙂 I was aware of this idea. I was thinking about what a singularity might be like and the concept of a maximum density.. The thought occurred to me that at maximum density the material that makes up the singularity is homogeneous. and it doesn't matter whether that material started as matter or light. Everything is just squished together in a homogenous lump.

[@narfwhals7843]

@@davefoc " and it doesn't matter whether that material started as matter or light." That is almost definitely true. But that's already true once a black hole forms. At least from the outside, it doesn't matter what material made up the black hole. They all look the same from the outside. The "No Hair Theorem" that the only characteristics a black hole has are it's mass-energy, electric charge, and angular momentum. It does not tell us where those came from. But to know what happens near the singularity we're going to need a theory of quantum gravity.

[@user-ef5me8hm7o]

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[@arwah97]

Is this a reupload? Funny I rewatched this just yesterday but from an earlier upload.. de ja vu?

[@daliamahooud7541]

Please l need an urgent answer -We say that all electromagnetic waves are the same speed in one medium despite their different wave lengths and frequencies -And (n=c/v) ( n is Absolute index of refraction) Is different when we change the color of light ( its wavelength) -Why can it happen whereas (v) is constant

[@narfwhals7843]

Electromagnetic waves _don't_ have the same speed in a medium independent of wave length. Different wavelengths have different speeds(at least apparently). That is how a prism works. The origin of the apparent speed of light in a medium is a bit more complicated (kzbin.info/www/bejne/eYbNpWZsiKlmnpo ) but it is different for different wavelengths and different media.

[@user-ef5me8hm7o]

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[@hiru92]

love to see extraordinary facts video 🙃

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@raymitchell9736]

Oooh Yeah! A mini series on Black holes... I'm already sucked into watching them... no escape for me LOL

[@themcchuck8400]

Simple assumptions that fix almost everything. Notice that this changes no equations, but places limits. 1. The total energy at every point is a constant. 2. There is no such thing as negative energy. 3. Spacetime is a field of potential energy whose domain is motion. Everything else follows. There are no infinities. There are no singularities. Black holes are hollow shells of maximal density with *nothing* inside, because there is no available energy. It's all being used.

[@Jimmy-B-]

But I thought you cant escape just inside the event horizon. The graph at 4:20 shows that you can right up to the singularity?

[@narfwhals7843]

At the horizon the escape velocity becomes the speed of light. So to escape you'd have to move faster than light, which you can't. So it's impossible to escape. That being said, the escape velocity analogy simply loses its merit when you look at the details, so don't put too much thought into how it's wrong. That's not what it's really about.

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@a.randomjack6661]

I think planets with complex life forms on them are a lot weirder than black holes, and a whole lot less common. But, that's just an opinion eh 🖖

[@Blackmark52]

"a lot weirder than black holes" Yeah, like 7.754 billion times weirder.

[@isenhertor]

black holes are so strong, i think they sent me back in time... or its a re-upload

[@sadakotube]

lol same here

[@alistair981]

I knew it, i thought i was crazy, and something went wrong with my brain.

[@XXveny]

What if we tied something to a rope, send it behind event horizon and then try to pull it back? Would it be possible? If we, theoretically, had limitless power AND the rope remained a regular object made of molecules? Or, different example: Does escape velocity apply to object pulled from Earth? What if we on Earth tied object to a rope, sent the other end of this rope to ISS (or Moon) and try to pull the object on Earth up to the orbit (or Moon). Is there some way how to calculate the force needed for such task?

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@JohnJohansen2]

Does scientists at Fermi Lab really use the Imperial system for measuring at their daily work? 😳

[@user-ef5me8hm7o]

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[@rubensr.desousaoliveira2149]

Great video thanks my friend

[@al1383]

Scientists says "matter attracts matter". Yet they can't say why or how exactly. What causes an atom to attract another atom? And how does gravity travel so far? IMO, which is just as good as anyone else's, cause no one truly knows;). IMO, gravity is caused by two things. Matter (not matter itself, but what happens when matter is present in space) and the constant expansion of the universe. With the expansion of the universe. We've seen galaxies traveling away from each other equally in all directions. Meaning the universe is expanding/growing everywhere. Even here on the surface of earth. As for matter, mass comes in different density. Black holes being the most dense object possible. A black hole is literally outside of the universe. BHs are so dense, the fabric of space doesn't exist inside a BH. The fabric of space, that is being displaced because of the density of BHs, is now accumulated around the BH. The fabric of space wants its space back, and is trying to get it back. This fabric is most abundant right at the surface of the BH. The fabric of space lessens the further away from the BH you are. So the fabric of the universe is now in multiples at the surface of a BH. Because this universe is constantly expanding, and we now have multiples of the universe at the surface, it causes this expansion to multiply. We get an extremely strong pressure towards the BH. It causes the fabric of the universe to intensify, in trying to get its space back (the space taken up by thr BH). This pressure is gravity. Matter's density and the size of that matter (how much of the fabric of space the matter displaces) is what determines the strength of gravity. As an example, the portion of our planet's center, the part that is dense enough to displace the fabric of the universe, may only be a few miles across. This is why we have minimal gravity. As for the sun, the sun's layers have different densities. So the amount of the fabric of the universe that is displaced drops drastically at certain locations in space, away from the sun. THIS is where objects/planets get trapped and are forced to orbit around the sun. The theory "Matter attracts matter" is half right. Matter does attract matter. But not because of the atoms in matter or anything else. Matter attracts matter because of the fabric of the universe it displaces. When an object is trying to "escape the sun's gravity, by traveling at 26 miles a second". The object is actually trying to travel faster than the expansion of the universe, in that particular spot. This explanation of gravity also explains how gravity can reach out so far across space. It's not the matter attracting other matter, at enormous distances, across space. It's the multiples of the fabric of the universe that extends so far from objects. And when two objects multiples of the expansion of the universe come into contact with each other, their courses are altered so that they travel towards each other. But, because matter isn't attracting matter. The objects won't collide head on with each other. Shouldn't they though? If matter attracts matter? Because it's their multiples of the expansion of the universe that causes them to come together, they won't collide. One will orbit around the other. Since the universe is a negative pressure, multiples of the universe is even more of a negative. So naturally an object will travel along the most negative. Lookup the different layers of our sun. Then look how the planets line up at the same distance as the layers are thick....

[@davidtetard5781]

I have a question about anti-matter. Is it possible that some galaxies that we see are actually anti-matter? They might be isolated enough so that they do not clash with other matter galaxies to annihilate. How do we detect anti-matter at that distance and know they are normal matter?

[@narfwhals7843]

They can't reasonably be isolated enough. Space is not really "empty". There is diffuse gas all over the place. The galaxy would run into this gas constantly and we would see a specific, dim x-ray glow. We do not observe this.

[@user-ef5me8hm7o]

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[@ecsyntric]

my understanding is that this so called “mass” of a black hole is just for classification. there actually is no matter inside a black hole. it is all turned into energy which warps spacetime. so basically when we say a black hole has 100 solar masses M - we mean to say the black hole has energy equivalent to Mc^2

[@narfwhals7843]

In contemporary physics mass _always_ means energy equivalent to mc^2. Mass always is energy. You can't convert matter to energy. Energy is a property of stuff. You can convert matter to radiation with the same energy, in accordance with mc^2.

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@kuukeli]

thank you for the video

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct 👆✍️

[@theosib]

If only we had a way to focus gravity waves and image them. Since they can pass through a black hole, it might be possible to work out what's inside of a black hole just based on gravity waves that passed through one.

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@mckim1sg41l1]

schouldn't be the red ring of the black hole in the end be brighter on the right side, where material ist streaming towards us ?

[@user-ef5me8hm7o]

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[@pomodorino1766]

Is this a re-upload?

[@drdon5205]

Yes. There was an error in the previous one.

[@pomodorino1766]

@@drdon5205 Thanks!

[@NetsanetSorri]

Any known connection between black holes and the Higgs field so far?

[@fdk7014]

Reupload?

[@phil.1]

Do mass/particles that passed the event horizon fall towards a black hole singularity faster than light? Then does that mean that the particle reverse its age? What if a black hole acts as sink that cleans and resets a particle’s internal clock/life back to zero.

[@Blackmark52]

"Do mass/particles that passed the event horizon fall towards a black hole singularity faster than light?" Relativity still says that nothing travels faster than light. And escape velocity only ever goes the other direction. I would assume a particle passing the event horizon toward the black hole would already be travelling at terminal velocity.

[@cloudpoint0]

Yes (probably) they fall faster than light relative to the space outside but they just go with the flow inside* so they are not really moving locally. Their aging would slow relative to the rest of the universe but not reverse. However, I think particles no longer exist once they enter a block hole - they become energy waves of some kind that get stretched into oblivion and no longer exist. * I said "inside" loosely above as black holes are not believed to have a conventional inside, they are not 3D spheres; rather they are 4D objects that have an extra time dimension. They are events in time, not physical objects.

[@filonin2]

@@Blackmark52 No such thing as terminal velocity in space.

[@Blackmark52]

@@filonin2 "No such thing as terminal velocity in space." How about the speed of light? It iseems to me that I've seen a video explaining why it's a limit and gravity is mentioned in the equation.

[@cloudpoint0]

​@@Blackmark52 The speed of light in a local space vacuum can never be reached (or exceeded) by an object with mass but such an object can always go a little faster (i.e. accelerate). It doesn't necessarily reach some constant velocity limit and coast thereafter.

[@XDRONIN]

Question, Gravity is (as I understand it) the curvature of Time&Space, and so, is Time&Space so extremely curved inside a black hole is that the reason Light can't escape a Black hole? Is Time&Space being infinitely expanded inside a Black hole, somehow?

[@juzoli]

Not exactly, but something like that. Ignoring the inside of the black hole (which we don’t know), at the surface the space-time is curved in a way, that no direction leads out from the black hole. All 360 degrees are pointing to the inside.

[@IOwnThisHandle]

Why do you write it like "Time&Space"? You know that's not right

[@XDRONIN]

@@IOwnThisHandle 1. for simple emphasis. Yes, I could write Time and Space, however... 2. they are one thing, so, I think it's more technically accurate, and you're right, it's not good grammar but... 3. there isn't a law against writing it like this. 😁😁 And if there is. Feel free to call the grammar police on me.

[@XDRONIN]

@@juzoli All 360 degrees are pointing to the inside? Do you mean all directions are being curved towards the inside?

[@juzoli]

@@XDRONIN Yes, these are the same things.

[@thescreamingellens9616]

Dr. Lincoln, I have a question. I am not if it a good one or not, but let me set it up and then ask: 1. We know that GR results in a singularity where the black hole ‘is’ 2. We also know that any single objects in the universe with sufficient mass reaches hydrostatic equilibrium as becomes a sphere. 3. Based on QM, we think the smallest length possible is the Plank Length. So here is my question: what happens if you assume (using GR) the black hole to actually be a sphere with diameter = Plank Length? Does that yield anything useful? Has it been considered and determined to be a meaningless question? Thnx

[@CUBOSH]

this idea that the "internal" escape velocity kinda tapers off in star got me thinking i wonder if there are similar scenarios in particle physics (strong/weak forces) where some particles are black-hole-like at close proximity

[@Psychx_]

At tiny distances, the uncertainty of location and momentum, aswell as quantum effects do also play huge roles. I don't think that there is a "particle trajectory" in the classical sense. As for gravitational interactions at these scales, science has no good model yet - in the math everything collapses to black holes or other nonsensical things happen.

[@kricketflyd111]

I was reading Omni magazine 50 years ago and it had the same description. So what is up with the new astrological images showing no expansion in the far away galaxy clusters?

[@peterholmes2089]

I'm going to sleep much better at night now knowing a black hole is not going to gobble me up.

[@oisnowy5368]

Given that the time dilation around (and perhaps in) a black hole becomes huge... will that even leave enough time for things to reach at the proposed singularity?

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆 ✍️

[@aniketsengupta7011]

Can you make a video on supermassive blackholes. Black hole and neutron star mergers

[@user-ef5me8hm7o]

Hey mate!👆Thanks for watching Tell expert Andrei jikh that you were referred by me for the right strategy on your new project to participate on it. Msg direct👆✍️

[@Gwallacec2]

What is the theoretical escape velocity of a black hole if you could travel faster than light?

[@maybepoet8148]

Depends on the mass of black hole

[@juzoli]

If you could travel faster than light, there would be no black hole.

[@ChristopherCurtis]

Not a physicist, but we simply don't know. Given the relativity equations, once the velocity is equal to the speed of light we have to divide by 0 to complete the (relativistic) calculations. If we ignore the 0 point, we have to take the square root of a negative number, so the answer is "imaginary" (or "complex") given that it includes an "i" (or "j") velocity component and we (or, I) don't know what that means in the real world.

[@dylanhunt5368]

Might consider that light can't escape black holes because black holes digest all the energy from light into itself and morphs it. As it would with anything that would be so close. There would be no escpae velocity because whatever would try to escpae would already cease to exist as a structure.

[@kitmoore9969]

As long as its escape velocity exceeds your "faster than light", it will remain a black hole.

[@VortekStarling]

Can you solve this problem? To explain how 2 laser beams going in opposite directions from the middle of a moving train car to clocks at each end could appear to be moving at the same constant speed in both directions to an observer on the ground, Einstein suggested that the clock at the rear would show a time ahead of the time on the front clock from the observer's perspective, although they would both be moving at the same rate due to moving at the same relative speed. Both clocks would be behind the observer's clock, due to time dilation, but the front clock would be behind it by more than the rear clock, in Einstein's mind. The question is how did the two clocks come to vary from the observer's clock by different amounts in the first place. Einstein never explained that, because he couldn't. It's the same Lorentz Transformation factor for the entire train car and the entire car accelerated at the same time and rate so how did the two clocks come to vary by different amounts simply by being at different ends of the train car? You can't answer it because nobody can, because Einstein's theory is clearly flawed.

[@ZubairAhmed-yw5zg]

what if time maybe slows too much that it's negligible, inside a black hole? Can we say that time would stop inside it, or maybe collapse or something?

[@xyzpdq1122]

Yes. When you are right before the event horizon, time essentially stops for you, and you see the rest of reality flash by very quickly. (Time dilation.). If you’ve seen the film Interstellar, this is why the crew feels like they’re on the ocean planet near the black hole for a few hours, but their crew mate on the ship has aged 10+ years.

[@jimsmindonline]

The question I have; What happens with very small black holes? What is the smallest black hole that can theoretically exist? I've heard Hawking radiation increases the smaller they are? Is there a point at which they rapidly 'evaporate' or can they get very small and still exist for a conceivable time? (eg How long would the earth last if it was compressed into that 9mm black hole?)

[@michaelblacktree]

I think this was covered in a PBS Spacetime video. IIRC the theory is that the black hole would eventually explode. But at that point, the mass would be so small the explosion wouldn't be very big (in astronomical terms).

[@davidklang8174]

There's interesting theoretical work being done on primordial black holes (looking at them as dark matter candidates). Really, REALLY small black holes could form from anisotropies in the very early universe. The smallest ones, though, would evaporate quite rapidly unless they can accrete efficiently (challenging when the event horizon is so tiny). These theories invoke extra dimensions which give larger horizons than the mass permits in 4D.

[@nmarbletoe8210]

The smallest BH would be 10^-5 grams. At this size a single photon should evaporate the hole almost instantly -- but that photon would have enough energy to be a black hole itself! This is a conundrum, which may remain unsolved until we have a unification theory.

[@gastonneal724]

I don't know if the correct description would be "heavy" stars. Since heavy usually is a characterization of weight.