Black Holes Do Not Exist, claims Mersini-Houghton

Thank you!

Regards,

JJD

Abhas,

Very interesting. Unfortunately there is the politics of physics, but there is also the physics of politics. Given the field seems to be circling around a particular model, which is seeming to be inexorably collapsing in on itself and only those already at the center of attention are going to attract attention, those further away from the center need to function accordingly and take the broader view of what truly is valid observational phenomena and what are the increasingly baroque theories drawn from it and the various subconscious assumptions long buried in the conceptual tools and framework.

One would think that in the not too distant future, there will be sufficient dissident voices in cosmology, physics and the related fields, to start a blank slate symposium, in which literally every idea, from spacetime to multiverses can be objectively held up and examined, no matter how much credibility they hold and not have participants reputation and credibility be threatened for skeptically examining the canon.

As someone with both the knowledge and history to sense what a circus it has become, it might be one of those back of the mind ideas to test among colleagues and see if there might not be some as yet unspoken agreement on such a move.

Regards,

John M

Perhaps John,

It is time for the Alternative Cosmology Group to convene another Crisis in Cosmology Conference. CCC-2 was very much like what you describe.

All the Best,

Jonathan

Jonathan,

It will start getting more attention, the more the establishment fusses over multiverses.

If I recall correctly the first one was out in Seattle, about four years ago? I submitted my observations about time as an argument against spacetime being physical, but didn't get any response. I'm pretty much resigned to being on the crackpot fringe, but it's an interesting topic to follow and comment on.

Regards,

John M

Abhs, ECOs are still thought to have a central singularity. Jack Butler commented:

"Perhaps "singularities" are artifacts of the math used to describe black holes rather than actual phenomena. ALL models must fail at some point, unless they are perfectly accurate, which is not possible for a model (it would be the thing, and not a model of it), Therefore all models must create artifacts at their ultimate limits. The math implies a "singularity" in which point "all the laws of physics break down." To me it seems more likely the mathematics breaks down than that the universe produces an impossible phenomenon."

Butler might be not quite correct in so far as there is certainly no reason for a breakdown of pre-Cantor/Dedekind mathematics, while there are many examples of reasonably using fictitious singularities. May I ask who were the foremost ones who naively took every arbitrarily created model for corresponding to reality. Maybe, while holes according to the Schwarzschild solutions were among the most prominent cases. I agree with Him (einstein) on that stupidity is potentially endless.

John M,

Did you manage making your arguments against spacetime accessible to me?

Eckard

Eckard,

I recall we came to some agreement on the nature of space, that it is not reducible to geometry, but I'm not sure you offered any comments on my ramblings about time. Here is a brief synopsis, drawn from an earlier discussion:

"That as individual beings, we experience change as a sequence of events and so think of time as the point of the present moving from past to future, yet the underlaying reality is that change is forming and dissolving these events, such that it is they which go future to past.

Not only is narrative and causal logic based on this sequencing effect and therefore history and civilization, but physics codifies it by reducing time to measures of duration between events. Now duration does not exist outside the present, but is simply the state of the present, as these markers form and dissolve.

There are various philosophical debates around this issue, such as free will vs. determinism, yet if we look at it as future becoming past, it makes more sense, as probability precedes actuality. Given that information can only travel at the speed of light, all input into any event can only arrive with the occurance of that event and cannot be fully predicted prior to it. As well as the manifesting energy quickly dispersing after the event, necessarily to inform further events.

Meanwhile physicists are either convinced the future already exists on some blocktime dimension and is as determined as the past, or that the probabilities never collapse and reality branches out into multiworlds with every quantum probability.

The science does recognize that clocks can beat at different rates in different physical conditions, but than assembles spacetime to explain why. If we were to think of time as simply a measure of action, it would be no mystery why clocks beat at different rates, because they are different actions and every action is its own clock.

As an effect of action, this would make time more like temperature, than space. Time is to temperature, what frequency is to amplitude. It is just that while amplitude en mass expresses as temperature, frequency en mass expresses as noise and thus from a physicist's point of view, chaos and disorder. Therefore to measure time, only one oscillation is isolated and its frequency measured. Yet the overall effect of change is still cumulative of all such actions, like temperature.

With time as an effect of action, we don't have to reject the present as a state of simultaneity, nor dismiss its inherent asymmetry, since the inertia of action is not bipolar.

Regards,

John M

Actually John,

The first Crisis in Cosmology Conference was in Portugal, and CCC-2 was in Port Angeles, which is near Seattle. I'll leave the nature of time question aside for now, because I have way too much to add. Some of it is supportive of your views, but most of it is not germane to the topic of this thread. However; I would recommend you examine the work of Reginald Cahill on Process Physics, which features a dynamical view of time, to look for points of agreement and differences - because that illustrates how changing our view of time influences physical law.

All the Best,

Jonathan

Jonathan,

Thank you for the suggestion. I googled up some references and it certainly looks promising.

"The key idea is that a truly bootstrapped model of reality must self-consistently bootstrap logic itself, as well as the laws of physics. Further, only by constraining our modelling to such a complete bootstrap do we believe we can arrive at complete comprehension of the nature of reality."

Although;

"Aside from 3-space and objectification, another emergent effect expected of HPS is the experience of a "contingent present moment" as distinct from a "recordable past" and an "unknowable future"--that is the irreversible time of our experience. In this regard, Cahill and Klinger inform us that "(experiential) time is only predicted in this model if there is an emergent ordered sequencing of events at the level of universality, i.e. above the details which are purely incidental to any particular realisation." Since, as we have seen above, there is only suggestive evidence of a fractal nature of the 3-space generated and therefore inconclusive evidence of SOC to afford appeal to universality, it really cannot be concluded that the HPS model has generated definitive evidence of irreversible time emerging."

It does seem that he is still trying to impose a top down universal vector on what he is actually describing as that bottom up process by which potential becomes actual, then residual.

Also he seems to still see space as emergent, which isn't necessary, since it can still be defined as the non-physical and thus negating need for cause, "universal" properties of infinity and equilibrium, distinct from the matter and energy filling it.

So time can truly be described as being bootstrapped into existence and space doesn't need to be.

As for time not really being part of this particular thread, I would argue the direction of time for mass and structure is falling inward and to the past, while energy is radiating outward and on to new forms, ie. the future. The result being an aspect of that convection cycle of expanding energy and contracting mass, that I think the particular observation on which this thread is based, is eventually pointed toward.

Regards,

John M

John M,

I did perhaps mistake you as having "submitted [to CCC-2 ?] observations about time as an argument against spacetime being physical". Nonetheless thank you for the new synopsis of your probable-actual-residual idea.

Eckard

Eckard,

Thank you.

I seems obvious when formulated like that, but that's just not how our minds function, as we distill out sequences of thoughts and then try to rationalize some order from them. For one thing, we much prefer thinking of the past as we experienced it, not as the physical residue and ethereal imaginings that it has become. The fact is that information is not all saved. It is constantly being erased in order for the energy to create new form.

Something to consider is that in ancient Egypt, geometry and religion arose as opposite sides of the same coin, as efforts to describe and explain cosmic order. While those initial impulses then went quite different directions, I see the same impulse in current physics, where it is decreed that the mathematical descriptions of relativity are inseparable from the explanation of physical spacetime and anyone questioning this is beyond the pale.

Such is life.

Regards,

John M

ARE BLACK HOLES REALLY SO WEIRD?

Black Holes have a certain aura about them. They are associated, in the minds of the general populace, with a certain mystique or ultra-mystery about them - terrifying objects that gobble up everything within range - the ultimate devourer, doomsday machine, berserker and weapon of mass destruction (if you could figure out how to manipulate one of course) all rolled into one. But Black Holes have other aspects about them that are equally fascinating, and not really all that weird, though some bits are weirder than others. But you don't have to be a geek to come to terms with these concepts.

The aura of the Black Hole, even if not quite as dramatic as a doomsday device, is hardly less within the astronomical community, to quantum physicists, or relativists (scientists who special in general and/or special relativity). Though there's little doubt today of their actual existence, a logical consequence of Einstein's theories of relativity, Einstein himself refused to give credence to them. The well-ordered universe just wouldn't actually create such monstrosities he believed. He wasn't alone in that point of view, and as their theoretical certainty became ever stronger, scientists tried to find ever more unique ways to prevent them from forming - to no avail.

But are Black Holes really as strange and mysterious and deserving of their aura and status as unique astronomical objects?

Black Holes may have no hair, which is to say they lack the individuality of whatever formed them so if you've 'seen' one Black Hole you've 'seen' them all. Translated, a Black Hole made out of rusted automobiles will 'look' the same as one made out of star-stuff, as one made out of pure gold, silver and diamonds. But Black Holes do have (or could have) certain properties. All Black Holes most certainly have mass and therefore gravity; they certainly have size (a volume, an area, a circumference, etc.); they certainly have a shape (spherical). Black Holes (against all intuitive prediction) have a temperature (Hawking radiation). They can have spin (rotation), and they may have an overall electric charge. So what's unique about that?

The property we most associate with Black Holes is gravity, a function of mass - the more mass, the more gravity. Associated with that concept is escape velocity - how fast do you need to go to escape an object's gravity well never to return.

Now our moon has gravity and an associated escape velocity. Planet Earth has greater gravity and therefore a higher escape velocity (about seven miles per second). Planet Jupiter has an even greater gravitational field and thus you need even more oomph to escape. Our sun is another notch higher up, and so it goes. Keeping in mind that gravity is related not to something's size, but to its mass, a White Dwarf star, while smaller than our sun, has greater gravity and therefore escape velocity. Then comes Neutron Stars (pulsars) and you really need some rocket power to get away from those babies!

However, there is a limit to velocity, escape or otherwise. That limit is the speed of light, or about 186,000 miles per second (roughly 300,000 kilometres/second). So what happens when there is so much mass, or so much gravity, that the escape velocity exceeds that of 186,000 miles per second? The quick answer is nothing - you can't escape; nothing can escape - not even light. That's pretty straight forward and you don't even need a course in relativity to figure it out! The absence of light is darkness, so any object that has an escape velocity greater than that of light will be dark - in other words, a Black Hole. The only difference twixt a Black Hole and any other macro object is that a Black Hole's escape velocity exceeds that of light. That's it; end of differences.

If you can't see a Black Hole, how could you know they actually (as opposed to theoretically) exist? Simple - Black Holes have gravity, and the gravity of Black Holes can influence matter we can see. So, if you see a star going too and fro in orbit around something you can't see, then that something is probably a Black Hole. Matter (interstellar dust and gas) spiralling into, but just prior to entering a Black Hole can also give off a tell-tale electromagnetic signature.

Because of such intense gravity, individuality is squeezed out. Planet Earth has highs (mountain peaks) and lows (ocean troughs) and a slight equatorial bulge, but if it's size were reduced (while retaining mass) to the extent that her gravity created a greater-than-light escape velocity, then Planet Earth would become a perfect sphere of super dense crushed matter. No peaks, no troughs, no bulge - no personality, or no hair!

Now objects tend to have a surface - an inside and an outside. In the case of Planet Earth, let's call beneath the crust Earth's inside; above the crust Earth's exterior. The same goes for Black Holes. The inside centre of a Black Hole is called a singularity. The 'surface' of a Black Hole is called the event horizon - it's the purely mathematical line where the escape velocity goes from faster than light speed (event horizon and below) to a permitted escape velocity (event horizon and above). Earth's usually quoted escape velocity is given to be at Earth's solid surface or sea level. But even sat 100 miles above, there's still as escape velocity, it's just less than 100 miles further down. In like style, a Black Hole's escape velocity decreases from the singularity outwards, but doesn't become permissible (less than light speed) until the altitude of the event horizon is reached. Thus one can not see anything, any events that are below this mathematical event horizon because anything below can't get out, including light. Finally, the distance between the singularity and the event horizon varies depending on the mass of the Black Hole.

It's what's below the event horizon that's really of interest given that it can't be seen; no information escapes to inform us or give us any real clues of the conditions beneath. One has to rely on physics' theoretical equations to predict conditions - conditions that really can't be verified by any direct observation.

Unfortunately, these equations, the equations of general relativity, break down when one approaches the singularity. That's because in order to come to terms with what a singularity is like, one has to merge general relativity (gravity) with quantum physics (because the singularity is thought to be of a size within the realm of quantum phenomena), or produce a theory of quantum gravity. Alas, that has yet to be accomplished. So, understanding the physics inside a Black Hole is one of Mother Nature's final frontiers!

For example, taken to their logical conclusions, physics' equations (general relativity) dictate that a singularity must have zero volume and infinite density. Physicists are well aware that whenever 'infinities' pop up in their musings, something's wrong and they need to go back to the drawing board (blackboard?) and refine things to a greater or lesser extent. Hopefully, a theory of quantum gravity will do that, but for the here and now, you'll find texts which state that a singularity has zero volume and infinite density. That's clearly a nonsense, for if one had infinity density, one must have infinite gravity as the greater the density an object has, the greater its gravitational attraction. Now even though gravity dilutes as it spreads throughout space and away from the object of its affection, any dilution of infinity is still infinity. Since Black Holes and associated singularities are thought to be common in the observable universe, there should be at least one that's had time since the Big Bang to project its gravitational influence onto us - say the massive Black Hole singularity at the centre of our Milky Way Galaxy, less than 50,000 light years away. Quite obviously we're not being subjected to an infinite gravitational attraction towards our galactic centre, which tends to put the kibosh on, and confirms the breakdown as to what the equations predict for a Black Hole's singularity.

So, if a Black Hole's singularity doesn't have zero volume and therefore infinite density, then it must clearly have a finite volume and a finite density which has implications for the origin of our Universe since conventional wisdom associates the Big Bang event with a singularity (and if there were to ever be a Big Crunch event, that would have to end up as a singularity).

The logic goes something like this. A singularity must have a finite density because having an infinite density is ridiculous. A singularity must have a finite volume because any object that has mass can't be dimensionless - that too would be ridiculous - and Black Holes certainly have mass since they have gravity. If the Black Hole continues to grow, then the singularity continues to add mass to it, and its density increases. But, eventually the density reaches some sort of maximum possible - it's finite after all and can't become infinite. So as matter continues to be added to the singularity, the volume or size of the singularity must grow - and grow - and grow - and grow. Eventually, the volume of the singularity must be such that it falls outside of the realm of quantum physics. Translated, in other words, not only is a singularity of greater than zero volume, it may not even be tiny. It could be massive - stellar sized; even galactic sized! That then does away with the absurdity that our entire universe started out as something less than atomic sized something akin to a tiny pinprick!

Now the other interesting thing is that gravity probably isn't really a force like electromagnetism or the strong and weak nuclear forces and shouldn't be lumped in with them (which physics texts do). Rather, gravity, according to general relativity, is rather a manifestation of space-time geometry. As the saying goes, 'matter (gravity) tells space-time how to bend; bent space-time tells matter how to move'. That movement we interpret as gravity.

So, space-time near, around or in a Black Hole is about as bent, or warped, as you can get, or conversely, the local geometry is so extreme or curved that not even light can get beyond the Black Hole's event horizon. The geometry creates a sort of well, so deep and so steep, that the velocity needed to escape is greater than special relativity allows. [Special relativity covers the speed of light; general relativity deals with gravity and space-time.]

What does the extreme warping of space-time mean - apart from making the Black Hole, black? Well, presumably if you distort space-time sufficiently, then you, in theory, can make short-cuts through space and/or time.

Let's have an analogy. Say you take a balloon and mark out a North and South Pole on the surface. The distance between the two is either half the circumference of the balloon (if you go via the surface or normal space), or the diameter (if you tunnel through, call that hyperspace). Now squeeze the balloon such that the North and South Poles are forced close together; maybe even touching. While this doesn't help reduce the travelling distance if you stay on the surface (normal space), the tunnelling (hyperspace) distance in the now warped balloon is vastly reduced. If it took you a year say to tunnel from North to South in the standard balloon, then post warping it might take you only a week (or less). In fact, if the Poles were squeezed into direct contact, then you could travel via normal space from one to the other instantaneously - no need for hyperspace. Of course if you actually wished to travel from some other point on the balloon's surface to some other point, the squeezing might not do you much good. In fact, the East - West distance has increased! So, the odds that the warping will be just right for your travel needs could be highly problematical. A local Black Hole warping that favours you travelling to Sirius quick smart is of little consequence if you wish to actually go to Alpha Centauri. But then as some old wise sage said, 'life wasn't meant to be easy'!

Now since space and time are intractably connected, points in time, like points in space, can be squeezed closer together. So the North and South Pole bits could easily have been a past and a future. Actually, because it's really space-time, you probably have a combination of both. You don't travel from 2000 AD Adelaide to 2000 AD Sydney in the wink of an eye; nor from 2000 AD Adelaide to 3000 AD Adelaide in that same wink, rather from (say) 2000 AD Adelaide to 3000 AD Sydney in an eye blink.

I've seen speculation that a Black Hole could warp space-time so greatly that it could 'pinch' itself off from our Universe and disappear entirely. Of course if it did so it could no longer have any influence within our cosmos. However, if something as massive as the Black Hole at the centre of our Milky Way Galaxy isn't enough to pinch space-time sufficiently to disappear, then perhaps it just doesn't happen - or maybe it takes the mass of an entire universe to do it. Say one universe's Big Crunch's mother of all Black Holes plus singularity warps space-time so much that it becomes another universe's Big Bang!

Now the common perception about Black Holes is that nothing gets out past the event horizon once it finds itself beneath it. That's not quite the case. In theory, as discovered by cosmologist/physicist Stephen Hawking, radiation can escape - sort of - and this radiation is now called Hawking radiation. Macro objects, objects we associate with classical physics, can not get from inside an event horizon to outside an event horizon without travelling faster than the speed of light, which unfortunately, should you find yourself below and event horizon, is the ultimate cosmic speed limit. There's no 'get out of jail' card. Travelling faster than light speed is not allowed.

But, any elementary particles, in the micro size realm and subject to quantum phenomena, can escape - again in theory; this hasn't be verified by direct observation (which is currently in the too hard basket). It you are a fundamental particle, just below the event horizon, you might, just might, due to quantum fluctuations or jitters / the vacuum energy / the Heisenberg Uncertainty Principle, quantum tunnel your way, the tiniest fraction of a distance imaginable, past the mathematical event horizon boundary, to outside and potential freedom. Of course most particles might get sucked right back in again, but a tiny fraction gets away, carrying with it energy (thus the Black Hole has a temperature) and therefore mass, so the Black Hole loses a bit of mass and shrinks a bit. This quantum tunnelling, crossing an energy barrier without having in theory sufficient energy to do so, is sort of like how a radioactive atom goes 'poof' and decays to a more stable state. Something in the nucleus, not having enough energy to break out, nevertheless quantum tunnels its way out - 'poof'.

Very much like a human being, from the very moment a Black Hole is born, say out of the gravitational collapse of a super-massive star that's run out of nuclear fuel and stellar puff, it will start to die, to evaporate via Hawking radiation. However, in a Universe still very much dominated by matter and energy (including the all pervasive cosmic microwave background radiation), way more stuff finds its way into a Black Hole than gets out - by many orders of magnitude. For every bit (particle) that escapes, millions of bits (particles) get trapped inside. But (and here I assume an ever expanding Universe that never results in a Big Crunch), what happens when all the available matter and energy (all those particle bits) has been consumed and Black Holes can't grow any more (and here I assume that individual Black Holes are so far apart and expanding away from each other that they don't consume each other). Then, evaporation - Hawking radiation output - exceeds input, and slowly, ever so slowly, and I do mean extremely slowly (as in measured over trillions of years), Black Holes get smaller and smaller until there's nothing left. But our now ever more vastly expanded and immensely larger than it currently is Universe is filled (albeit to a much rarefied extent) with just particles - particles adrift in the eternal cold of near absolute zero temperature (zero degrees Kelvin, the absolute theoretical minimum temperature possible).

However, the ultimate death of Black Holes has posed a significant problem to some physicists, causing quite a bit of controversy in the process.

What happens to the information content that a Black Hole can gobble up? Say you toss a book, or a CD, or a fully loaded human brain into a Black Hole. Is the information contained in that book (or whatever) lost to the Universe forever? [Perhaps given the state of information overload we suffer from that might be a blessing!]

You can not have macro stuff spew out of a Black Hole without violating basic physics. Macro stuff, say in the form of a book or a CD or a human, stuff full of information, falls in - that identical macro stuff, stuff full of information, does not, can not, come back out again. It is not only an improbable event, but an impossible one and a violation of the law of physics. But we have seen that in theory at least, Hawking radiation can get back out, because radiation isn't macro, its micro, or in the realm of the quantum.

Note that it wasn't Hawking radiation that was tossed into the Black Hole in the first place, but a book or CD or a human being or a whatever macro object, so escaping Hawking radiation isn't that book or that CD or that whatever, but a bit of this and a bit of that and there's no way of distinguishing the this from the that. Though there is apparently no way to reassemble the bits into all its separate meaningful messages; one-on-one, all the bits are nevertheless there.

If you were somehow able to reassemble bits of Hawking radiation emitted from all the bits and pieces which the Black Hole swallowed - which can escape - into a meaningful message(s), how would you know that message was something part and parcel of some information that went down the Black Hole gurgler in the first place? You're more likely to have assembled one letter from one book, another letter from another book, yet a third letter from a third book, etc. The information (say sentence) you have assembled never entered the Black Hole in that form at all!

Still, a Black Hole, in theory, eventually spews out all the information it absorbed over its existence, ultimately via Hawking radiation. Some scientists insist there is, there must be, a way to reassemble the bits into all its separate meaningful messages; one-on-one.

So therein lies the controversy - macro stuff does go in; macro stuff does come out. Macro stuff ultimately escapes as micro stuff - Hawking radiation. Some scientists will say you can't in theory reassemble and separate out the signal from the noise; others say you can, in fact it must be possible.

As indicated above, some physicists make a big deal over the loss of information via a Black Hole relative to any other way - probably because of the non-reversibility factor already described. Methinks personally it's a non-event. Why? The fundamental question this all boils down to be that information - in any form - is a composite of elementary particles. A book, or a CD, or Morse code ink drops, or a human brain is a composite of particles. An electron, all on its own, isn't telling you very much (for that matter, either is any individual letter in a book - by itself). Loss of information seems to be another example of dust-to-dust, ashes-to-ashes; only it's a more fundamental case of elementary particles to elementary particles. It's how the Universe began and its how the Universe will end up if the current observational astronomical trends continue into the indefinite future.

There's one other solution to the 'is information lost forever or is it not' paradox. It's considered a possibility that a Black Hole, because is so distorts time and space - in the extreme - ultimately buds off from our Universe and starts or enters another universe, or a baby universe (part of a Multiverse). In such a case, any information is budded off with it and lost to our Universe forever. Of course our loss is the other universe's gain; maybe a Black Hole(s) in some other universe has dumped its information load (or overload) onto our Universe!

There's one further spin-off from the Black Holes make baby universes idea. In a Multiverse, different universes may have different laws of physics. There's no reason why the laws of physics in our Universe need be identical in another universe. Thus, there might be some universes where the local physics favour the formation of Black Holes, and some universes where local physics can't make Black Holes. Those universes that can easily make Black Holes will 'breed' and produce baby universes. Those universes that can't readily make Black Holes will 'breed' less. Those universes that can't produce Black Holes will be sterile. Do you see the connection with Darwinian ideas? Some universes are more 'fit' to reproduce than others!

Now that's weird! There's one other bit of weirdness I like about Black Holes, and that is that what's inside them may well be a new form of matter. Ordinary matter goes into a Black Hole, but the conditions inside them are so extreme that there's some sort of phase transition (like when ice goes to water goes to steam or vice-versa) and while it's still matter, it's matter but not as we know it. The theoretical evidence for that idea is that if you have a matter star, and an antimatter star, and you introduce them to each other, what you get is one almighty Ka-Boom! But, if your matter star compresses into a Black Hole, and your antimatter star compresses into a Black Hole, and you combine the two, what you get is just a larger Black Hole!

Some more weirdness: It's suggested that information going into a Black Hole is actually 'stored' in the event horizon, that two dimensional 'surface' marking the point of no return that surrounds the Black Hole's singularity - whatever that actually is. The event horizon concept isn't difficult to envision - Earth's crust and oceans are a two dimensional surface surrounding the spherical three dimensional planet.

Now as more and more stuff enters a Black Hole, the event horizon expands accordingly - obviously - just like our crust (area) would get bigger if Earth's volume increased. The event horizon is also the area where Hawking radiation is emitted from.

Now say you are inside a Black Hole's event horizon - that's the wrong side to be on, but this is just a thought experiment and I'll assume you haven't been crushed into a tiny pinprick of stuff, stuff that could equally be rusted automobiles or stuff formally made from gold, silver and diamonds. There's lots of trapped radiation (photons) in there with you because light can enter a Black Hole. Those photons can struggle up, losing energy with each unit of distance gained, to reach the event horizon, but no farther. Their energy has exhausted itself. I gather they can just barely touch and 'reflect' off the underside of the event horizon and come back down again (in a direction towards the singularity), picking up the energy again that they expended in their futile gesture of escape. So, you, being also beneath the event horizon can see the event horizon from the inside via these trapped photons. You can also see beyond the event horizon via new photons entering the Black Hole from outside the event horizon - photons that will join their trapped or prisoner kin. It's like a half-way mirror. If you are inside a Black Hole, you can see out, because light can pass through the Black Hole's event horizon to you, but people on the good side or outside of the event horizon can't see you because light reflecting off you can't make it past that event horizon barrier.

One further question, could we actually be living within a Black Hole, or translated, is our Universe actually a Black Hole? Now one could (and people have) suggested that one could consider the entire Universe as being the inside of a Black Hole - after all, nothing can escape from the Universe. Well, if you can't escape from inside a Black Hole, and assuming there's no escape from our Universe (you are trapped in this Universe, like it or lump it), then a rose by any other name...

However, our Universe doesn't exactly mirror a real Black Hole unless there is an outside to our Universe - a beyond the boundary or horizon that allows stuff to get into our Universe, our Universe ultimately trapping it.

So, Black Holes residing inside a Black Hole Universe, which maybe residing inside...

Russian dolls within Russian dolls within Russian dolls within Russian dolls.

Saving the best for last, could you become a Black Hole? Well, the short answer is presumably, 'yes'. The reasoning goes as follows. If you travel at ever increasing velocities, under special relativity, your mass gets correspondingly greater and greater, and your length gets shorter and shorter. Translated, your density gets greater and greater; your own gravity gets higher and higher. At light speed (impossible to achieve), your mass would be infinite; your volume zero; your density and gravity infinite. Well, that's not on. But, before even approaching that limit, your mass would be theoretically great enough; your volume low enough, your density and gravity great enough, that you'd warp space-time sufficiently enough to turn into a Black Hole! As noted above, what actually comprises a Black Hole is irrelevant. Any stuff will do - gold, silver and diamonds; rusted automobiles; or flesh-and-blood (i.e. - you).

Here are a few further recommended readings:

Begelman, Mitchell & Rees, Martin; Gravity's Fatal Attraction: Black Holes in the Universe; [2nd Edition]; Cambridge University Press, Cambridge; 2010:

Susskind, Leonard; The Black Hole War: My Battle With Stephen Hawking to Make the World Safe for Quantum Mechanics; Back Bay Books, New York; 2008:

Thorne, Kip S.; Black Holes & Time Warps: Einstein's Outrageous Legacy; W.W. Norton & Company, New York; 1994:

CAN BLACK HOLES EVAPORATE?

While there is a constant transfer of matter and radiant electromagnetic energy (photons) between bodies throughout the cosmos, there are sinks, ultimate final resting places where matter/energy can retire to and be removed from the rest of the cosmos. These cosmic sinks are Black Holes. But is that retirement permanent, or can stuff re-enter the cosmic workforce? Can Black Holes evaporate? The theoretical short answer is "yes"; the long answer is "no".

Black Holes are astrophysical objects that are so massive, that have gravity so high, that their escape velocity (some seven miles per second on Earth) exceeds the ultimate cosmic speed limit - the speed of light (186,000 miles per second). Since nothing can travel faster than the speed of light, nothing (matter and/or energy) once inside a Black Hole can ever get out again - or so the seemingly ironclad logic went.

However, that's all according to classical physics. A physicist by the name of Jacob Bekenstein came up with the idea of applying quantum physics to Black Holes (upon a suggestion by his mentor John Wheeler - who incidentally coined the phrase "Black Hole"), and once that was done, well lo and behold, Black Holes apparently exhibited entropy, and therefore had a temperature and therefore must radiate and therefore can vomit out stuff. His ideas were mulled over and over again and finally agreed to and expanded on by the celebrated astrophysicist/cosmologist Stephen Hawking. That stuff that a Black Hole can regurgitate now goes under the name of Hawking radiation, or to give credit where credit is due it is technically Bekenstein-Hawking radiation. However, it's usually just called Hawking radiation so I'll stick with that convention.

Of course if Black Holes have a temperature, then they must follow the same laws of thermodynamics as any other object with temperature. One key point in thermodynamics is that energy exchanges between objects are at least partly determined by one object's temperature compared to another object's temperature. The temperature of a hot cup of coffee will stay hot longer the higher the temperature of the environment that surrounds that hot cup of coffee. A Black Hole's temperature must be compared to whatever temperature surrounds the Black Hole when considering the fate of the Black Hole. So how does a Black Hole get temperature?

In retrospect, how this happens is obvious (as are all great ideas when applying hindsight).

There is no such thing as the perfect vacuum. That could only be achieved at a temperature of absolute zero where and when everything is 100% frozen stiff. Alas, such a state violates one of the most fundamental principles of quantum physics - the Heisenberg Uncertainty Principle - where it is impossible to know both the momentum and position of anything with 100% precision. If something were at absolute zero, frozen stiff and standing still, you'd know both the momentum (which would be zero) and position (at a standstill) of that something with absolute precision.

Since there is always a minimum state of energy anywhere in the Universe (something above absolute zero), and since energy and mass are equivalent (Einstein's famous formula/equation), then that energy state, the false not-quite-absolute-zero vacuum, the vacuum energy*, can generate mass - virtual particles. However, the particles come in matter-antimatter pairs, which usually immediately annihilate and return to their former pure energy state. BUT, and there is always, a BUT - there's an exception to the rule - that normal state of affairs can be thwarted.

The vacuum energy, that which can generate particle-antiparticle pairs, exists everywhere where existence has any meaning. Part of that existence is an area called the event horizon**, which is a concept related to the concept we call Black Holes. All Black Holes have an event horizon which surrounds them.

The event horizon surrounding a Black Hole is that somewhat fuzzy region that separates the region (below the event horizon) from which gravity rules over the speed of light, and that region (above the event horizon) where gravity's escape velocity can't quite dominate that speed of light velocity. I say its "fuzzy" since it's not razor sharp, albeit nearly so.

The vacuum energy is part and parcel of the space surrounding the event horizon, above, below and spot-on. Now, what if that vacuum energy generates a pair of virtual particles, one each popping into existence above the event horizon; one below the event horizon. Then, the particles will be unable to annihilate and recombine into pure energy. One will stay within the Black Hole. The other, being above the event horizon, can be dealt a 'get out of jail' card. And thus, slowly, ever so slowly, but ever so surely, the Black Hole loses mass, thus energy, and evaporates.

Here's the general picture. Black Holes can only radiate from the event horizon region which, in a very large Black Hole is going to be very cold because it's not radiating very much, so initially only things like the mass-less photon escapes. Assuming there's no incoming to replace the loss, the Black Hole shrinks, and as it gets smaller it warms up slightly (that's what things that shrink tend to do) and can radiate particles with small mass - say neutrinos. When the Black Hole is tiny, it's very warm, in a relative sense, and it can go out with a 'bang', maybe emitting an electron or positron which is way more massive. When there's no more Black Hole, the vacuum energy still produces at random virtual particle pairs, but there's no more event horizon from which to separate those virtual particle pairs and thus its all back to normal - the two annihilate and return to their vacuum energy state. That's where the popular accounts end. End of story. The ultimate fate of Black Holes will be to evaporate via Hawking radiation, even if it does take trillions of years.

Alas, the written texts forget to mention that radiation emission (and other forms of emitted stuff) is a two-way street, not a one-way street. Black Holes can acquire stuff, as well as radiate stuff. If deposits exceed withdrawals, then Black Holes will always have a positive 'stuff' balance and thus won't fully evaporate. Now this is perhaps why Hawking radiation hasn't been observed. The tiny amount of Hawking radiation (outgoing) will be swamped by the greater, many orders of magnitude greater, amounts of incoming radiation and other stuff impacting the Black Hole.

Forget Black Holes (and their massive gravity) for a moment and concentrate on Planet Earth. Even at night, you see lots of suns - stars. You see them because they are radiating photons - particles of electromagnetic energy of which visible light is a small part. In fact you only detect a tiny fraction of visual photons because your visual detection devices (eyes) aren't that efficient. Optical telescopes pick up a lot more of them, but they're still just as real. You are also being hit by photons in the infrared, the ultraviolet, in radio wavelengths, X-ray photons, gamma-ray photons, etc. Though Earth's atmosphere shields us from some of these photons (ultraviolet photons are far greater in number at the top of our atmosphere than at the bottom), you still get impacted by multi-billions of them; Planet Earth many orders of magnitude more. Some of the photons get reflected back into space; these don't add to Earth's energy/mass balance. Overall, there are roughly one billion photons for each and every fundamental particle with mass, like electrons and neutrinos.

Now in addition Earth (and you too) gets hit with cosmic rays, neutrinos, and cosmic dust. Even if you luck out, Planet Earth gets impacted by meteors and other outer space debris, sometimes debris large enough to not only hit the surface but do considerable damage. Planet Earth's mass increases by many tons a day, all due to Earth's sweeping up of the interplanetary dust and small rocks that intersect Earth's orbit. The trillions of neutrinos that hit us are so ghostly that nearly all pass right through you and the entire planet as well despite them having a tiny amount of mass, so as far as our planet is concerned, they are of little significance.

Now what about a Black Hole? Clearly a Black Hole isn't isolated from the rest of the cosmos and objects therein. If you were just outside the event horizon you'd 'see' photons (of all wavelengths) because you'd see stars and galaxies, etc. just like you can locally. Neutrinos would still pass right through you on their way to their doom once passing through the event horizon. The Universe is full of interstellar and intergalactic atoms and molecules and dust and of course lots of larger stuff a Black Hole can snack on. Black Holes will sweep up stuff just like Earth does, only more so since it has more gravity with which to grab hold of stuff with, and also because once caught there's no escape for the cosmic fish. Unlike Earth, everything that crosses that event horizon, that hits the Black Hole, won't be reflected back (like photons). Neutrinos that can pass through light-years worth of solid lead without even 'breathing hard' will be imprisoned when they try that trick in a Black Hole's inner sanctum. And of course atoms, molecules, interstellar dust, the big chunks will also get imprisoned.

But we can imagine an idealized cosmos where all Black Holes have swallowed up all existing radiated particles (photons), all the atoms, molecules, the dust and all the bigger stuff - all those stars and planets; asteroids and comets; even all that mysterious 'dark matter'. So you have a cosmos of just Black Holes and the vacuum energy (well maybe a few bits and pieces escaped, but so few to be of no consequence). Of course there is one further logical extension. Black Holes can swallow other Black Holes. Black Holes can merge to form bigger Black Holes. The final product is that the cosmos consists of one Black Hole - the Mother of all Black Holes - plus the vacuum energy! So you end up with one Black Hole left standing with nothing left to eat.

Okay, so the only scenario now possible is that this Mother of all Black Holes evaporates via Hawking radiation. It might take trillions upon trillions upon trillions of years, but evaporate it does. Since matter and energy can neither be created nor destroyed, once the Mother of Black Holes has finally gone 'poof', the Universe is right back where it started from - full of stuff from photons to fundamental particles which them undergo chemistry to form atoms and molecules and stars and planets and perhaps life - and new Black Holes!

Perhaps this is a new and improved version of a cyclic/oscillating universe! - But then again, maybe not. There's a fly in that ointment (but I had you going for a while back there!). That "idealized cosmos" was only a 'what if' thought experiment.

Firstly, it's actually very, very unlikely all the Black Holes in the Universe will ever merge together as long as the Universe keeps expanding. Since the galaxies are getting farther and farther away from each other due to that expansion, the collection of Black Holes contained within each galaxy keep getting further and further apart from other clusters of Black Holes contained within other galaxies. It's like the passengers in one car get more and more remote from the passengers in another car when each car is going at different velocities and heading in different directions.

Now the collection of all Black Holes in any one galaxy could well coalesce into one super Black Hole galaxy. You have a galaxy that instead of containing billions and billions of stars and debris and particles now consists of just one Black Hole - the car only has one occupant. You have a pure Black Hole galaxy, or a galactic sized Black Hole.

One might end up with a Universe composed of just these pure Black Hole galaxies, all spreading farther and farther apart over time.

But secondly, there's another fly in the ointment. All the space that separates these pure Black Hole galaxies from each other isn't a perfect vacuum, quite apart from the vacuum energy. All the radiating stars and stuff may have been gobbled up within each galaxy, but all of interplanetary space, all of interstellar space, and all of intergalactic space, isn't pure vacuum. There's still the 'it's everywhere, it's everywhere' Cosmic Microwave Background Radiation (CMBR).

So what's this CMBR? If you have a massive hot explosion (like the Big Bang event is alleged to have been), and all that heat energy expands and expands, then you'd expect the temperature of the area occupied by that energy to drop, the temperature ever decreasing as the volume that finite amount of energy occupies increases. As the energy expands it gets diluted and thus cools, but can never reach an absolute zero temperature for reasons already noted. And that's just what we find on a universal scale. There's a fine microwave energy "hiss" representing a temperature a few degrees above absolute zero that's absolutely everywhere in the cosmos. That's the diluted heat energy of the very hot Big Bang - well it has been a long time since the Big Bang event (13.7 billion years worth of time) and that energy is now spread throughout a lot of cosmic volume. That microwave "hiss", called the CMBR, was predicted way before it was discovered. There's no doubt that it exists.

Since the CMBR is just photons with very long wavelengths, Black Holes could suck up the CMBR photons as easily as light photons. Removal of CMRB photons, already representing a temperature just slightly about the theoretical minimum - absolute zero - would mean the Universe gets even colder, which it would anyway since the Universe is ever expanding and thus available electromagnetic energy (photons) is ever diluting. Combining the two effects and the Universe is a chilly place indeed and will get even colder.

However, it's probably not possible for Black Holes collectively to swallow up all of the CMBR since there will come a point of diminishing returns. What happens when the temperature of Black Holes equals the temperature of the Universe at large - the CMBR? The answer is thermal equilibrium like when your hot cup of coffee cools off to room temperature. Input into Black Holes from the CMBR will equal output via Hawking radiation. For every photon emitted via Hawking radiation, a CMBR photon gets sucked in. What does that mean? It means a Black Hole can not evaporate.

What about very tiny (micro) Black Holes that are relatively 'hot'? Might they go 'poof' before thermal equilibrium is achieved? Will the contents of the Black Hole evaporate into the surrounding cosmos before they can equate to the surrounding temperature? The analogy might be like a hot drop of water could evaporate into the cold atmosphere before the liquid water drop can attain the temperature of its surrounding environment.

Even so, I still imagine that in the current matter and radiation dominated Universe, incoming would still exceed outgoing.

Of course if you could take a Black Hole, isolate and shield it from the rest of the cosmos and all that it contains, so all you have is the Black Hole and its internal energy (including the all pervading vacuum energy therein). An isolated Black Hole would be in a setting equivalent to putting it into an absolute zero temperature environment. If that's the case then outgoing would exceed incoming since there could be no incoming, and therefore that Black Hole would then radiate and slowly evaporate and eventually go 'poof'. BUT, and there's always a BUT, I can not envision any scenario where a Black Hole can exist in such a theoretical isolation. So, Professor Hawking is quite correct - in theory. In practice, in the here and now, input exceeds Hawking radiation output, and even in the unimaginably far distant future equilibrium will be established where input equals output.

*If it helps to conceive of the concept of the vacuum energy, here's an analogy. Think of the invisible but energetic atmosphere as the vacuum energy. Part of that atmosphere consists of invisible water vapour. But, all of a sudden, and for reasons that must have been mysterious to the ancients, part of the atmosphere undergoes a phase change into something you can see; into something solid - like a particle. You get mist/fog (clouds), rain drops, snow, sleet, hail, etc. Then, equally mysterious, those solid bits eventually undergo another phase change (evaporation standing in for annihilation) back to invisible water vapour in the equally invisible atmosphere. And so you have the invisible vacuum energy that generates particle-antiparticle pairs which annihilate back into the vacuum energy.

**The surface area of the event horizon is the same for both incoming and outgoing so there is no need to take that (non) variable under consideration.

ASTRONOMICAL BLACK HOLES REVISITED

I've noted in earlier essays that someone crossing over the Event Horizon of a cosmic Black Hole does so from a personal perspective of one second per second - normal time. An outside observer would see that same crossover event as one frozen in time for all eternity. That implies a paradox in that something cannot happen at one second per second and yet take an infinite amount of time to happen. The paradox might be resolvable if it were only the image of the happening frozen in time. Alas, that too has issues.

I've read several times some scientific author suggest that to an external observer, someone (or something) that's on a bullseye path toward an astronomical Black Hole, well someone will not only be travelling at a time rate slower and slower by the external observer's clock as they (let's call that person a pilot) approach the Event Horizon, but in fact at contact with the Event Horizon, the pilot's time, again as recorded by the external observer, will have stopped. In other words, the external observer will never witness the pilot's crossover from outside the Black Hole's Event Horizon to inside the Black Hole's Event Horizon. The pilot will appear to be frozen in time at the Event Horizon, as witnessed by the external observer for all eternity, yet as far as the pilot is concerned, everything is normal in terms of time flowing at one second per second. The pilot, from the pilot's perspective, crosses the Event Horizon as easily as driving to the local supermarket.

Now that's a major paradox. The pilot can't be crossing the Event Horizon at one second per second, while at the same time being frozen in time while crossing, which is the case according to our external observer. Of course the paradox is bullshit. To an external observer, time only comes to a screeching halt from their point of view for someone external to them if they witness that someone travelling at the speed of light. Firstly, that's a physical impossibility. There's no reason to believe that our cosmically Black Hole bound pilot is crossing the Event Horizon at light speed. There's no absolute requirement that our pilot is crossing the Event Horizon at the speed of light. The pilot in fact might have fired retro-rockets to slow down just prior to crossing the Event Horizon in order to better savour the moment (just like crossing the equator for the first time)! So, in actual reality, our external observer will see the pilot cross the Event Horizon, albeit at a way slower rate than the pilot will because the pilot is travelling, hence doing the Event Horizon cross-over, though at less than the speed of light but still at some subluminal velocity relative to the external observer. Any velocity incurs some slowing of time when viewed by an external observer; the faster the velocity, the greater the slowdown. IMHO, some 'experts' need to go back and redo Physics 101.

Only here's the expert's explanation which explains why there is no paradox.

Space is a thing and mass (hence gravity) can warp space, twist space around its little finger. The most extreme form or amount of gravity is contained within a cosmic Black Hole from which not even light can escape - hence the blackness of the Black Hole. Because space is a thing, the Black Hole or the super ultra intense gravity of a Black Hole can suck in space (as well as matter). Okay, so a Black Hole can gobble up space.

Issues arising #1: IMHO, space is not a thing but a concept. Gravity therefore cannot interact with space. Gravity is a thing; matter is a thing; light is a thing, so interactions between gravity and matter and light (representing energy which is just matter in another form) are not an issue.

Issues arising #2: presumably that means that anything that has gravity (like you) will suck in some amount of space since even the tiniest amount of gravity will warp space to some degree.

Meantime, back to the expert: Space (as a thing), gets sucked towards a cosmic Black Hole at less that the speed of light, but speeds up as space gets closer and closer to the point of no return (the Event Horizon). When space crosses the Event Horizon, it is travelling at the speed of light. Once inside the Event Horizon, space falls down the gravity gurgler at a speed greater than that of light, which is okay since space, albeit a thing doesn't have any mass. Anything with mass cannot travel at superluminal velocities since anything with mass can't cross the speed of light boundary from subluminal to become superluminal.

Any physical object crossing the Event Horizon will be giving off and/or reflecting light (or any other form of electromagnetic energy) at the speed of light. But the Event Horizon is that exact boundary between space being sucked in at less than light speed and being sucked in at greater than light speed so light being given off at the Event Horizon is escaping at the same velocity that it is being sucked in. It's like you running on a treadmill at the exact same velocity but opposite direction to that of the treadmill. To an external observer you are running yet standing still, and would appear so for all eternity.

We have to assume that the material object itself can't be crossing the Event Horizon at the speed of light (that's not allowed), nor will it travel at or beyond the speed of light once inside the cosmic Black Hole and dropping down it's gravity gurgler. Though the material object crosses the Event Horizon at less than light speed, the visual image of that object will travel at light speed, but light at the Event Horizon is like the runner on the treadmill. It's a balancing act in that the image from the object is escaping from the Black Hole's Event Horizon outward bound at the exact same rate as it is being sucked into and past the Event Horizon by space itself.

Issues arising #3: IMHO, the Event Horizon must be extremely thin, since the Event Horizon by definition is that boundary where a velocity just a tiny, tiny, tiny (add some more 'tiny' here) fraction under the speed of light becomes just a tiny, tiny, tiny (add some more 'tiny' here) fraction above the speed of light. Or, the Event Horizon is that boundary that marks the speed of light exactly (and any tiny, tiny, tiny deviation either side is no longer the speed of light). The Event Horizon must in fact be the shortest allowable thickness that's allowed by quantum physics, which is the Planck Length (which is so small in length, or thickness, not even the most powerful of microscopes could resolve it).

The implications revolve around the fact that any image, like that of our pilot in their spacecraft, is going to be massively larger than the thickness of the Event Horizon. In actual practice our outside observer will more decidedly not see the image frozen at the Event Horizon for all eternity. Part of the image will have to be above the Event Horizon and thus be able to escape away from the Black Hole. Part of the image will be below the Event Horizon and sucked into the cosmic Black Hole never to be seen again. Any remaining image is one Planck Length thick - invisible to the human eye and the most powerful of microscopes. Even that tiny remnant won't last long due to ever present quantum fluctuations. The Event Horizon has the tiniest of jitters but it's enough to disrupt the remaining bit of image from remaining for very long. The upshot is that the frozen image of the pilot and the craft as witnessed by the external observer will be fleeting at best.

Issues arising #4: When it comes to those astronomical Black Holes, we are all external observers. If our expert is correct, and images are frozen for all time at the Event Horizon by objects consisting of matter and energy that cross the Event Horizon, then absolutely anything and everything that has crossed over the Event Horizon since the creation of any specific cosmic Black Hole - since the year dot probably - well their images collectively should still be, well, visible. Each individual image would be piled on top of the next one top of the next on top of the next and so on. Somehow I very much doubt that's the case. It should be bleeding obvious through our astronomical telescopes. And so, I repeat that IMHO, some 'experts' need to go back and redo Physics 101.

A VOYAGE TO THE BOTTOM OF A BLACK HOLE

Suicide missions are hardly unknown happenings, so presumably it wouldn't be too hard to find a volunteer to take a long walk off a short pier and dive into the heart of a Black Hole. Well, let's trade in the walk and the pier for a spaceship, with our suicidal pilot crew-member willing to boldly go. What might she expect? For that matter what might a chickenhearted outside observer expect to see?

Space isn't really the final frontier; rather the inside of a Black Hole that's inside of space really is the final frontier. Only the insanely suicidal need boldly go and explore, as it's unlikely that the innards of a Black Hole will become a popular tourist attraction for many a millennia to come - if ever.

Okay, we have a depressed, suicidal, boldly going spaceship pilot, and she's determined to go out in a blaze of glory and make her mark in the history books. No ordinary suicide for this woman! It's across the event horizon threshold and down the hatch of a Black Hole. I need point out here and explain that technical term 'event horizon' - it's just that location that divides the ability to return home safely from the point of no return, ever.

Countdown: Five, four, three, two, one - we have lift-off on the maiden voyage to boldly go and see what's to be seen from the inside of a Black Hole.

As far as our suicidal pilot is concerned, everything from launch to crossing the event horizon is as normal as taking the cross-town bus to work. Time will tick by at one second per second; her mass will register normal; length ditto. However, due to Einstein's concepts in all things being relative, an external observer will see our boldly going pilot's reality slightly differently.

An external observer, say relaxing back on Earth with a super powerful telescope, follows ionization trail of the boldly going voyager's spaceship to the nearest Black Hole. Basically, what this person sees is that as the suicidal voyager blasts off from Earth, picks up speed, her ship and contents (including herself) start to shrink in length, increase in mass, and her rate-of-change (time) ticks by more slowly compared to Mr. Stay-At-Home's own. Okay, that's in keeping with Einstein's relativity proclamations.

But for some inexplicable reason, I've read several times some scientific author suggest that to an external observer, the suicidal pilot will not only be travelling slower and slower by the external observer's clock as she approaches the event horizon, but in fact at contact with the event horizon her time, again as recorded by the external observer, will have stopped. In other words, the external observer will never witness the pilot's crossover from outside the Black Hole's event horizon to inside the Black Hole's event horizon. The pilot will appear to be frozen in time at the event horizon, yet as far as the pilot is concerned, everything is normal in terms of time flowing at one second per second.

Now that's a major paradox. The pilot can't be crossing the event horizon at one second per second, while at the same time being frozen in time at the time of crossing, according to our stay-at-home observer. Of course the paradox is bullshit. To an external observer, time only comes to a screeching halt for someone external to them if they witness that someone travelling at the speed of light. Firstly, that's a physical impossibility. There's no reason to believe that our suicidal pilot is crossing the event horizon at light speed. There's no absolute requirement that our suicidal pilot is crossing the event horizon at the speed of light. She in fact might have fired her retro-rockets to slow down just prior to crossing the event horizon in order to better savour the moment! So, in actual reality, our observer will see the pilot cross the event horizon, albeit at a way slower rate than the pilot herself because the pilot is travelling, hence doing the event horizon cross-over at less than the speed of light. IMHO, some 'experts' need to go back and redo Physics 101.

In any event, once the external observer observes our boldly going suicidal voyager cross the event horizon, the show is over for him. Nothing that's part and parcel of the voyager, not her ship's reflected or emitted light, not her radio signals nor information signalling of any kind, will recross the event horizon in the outward bound direction and heading back to Earth. Our external observer can pack away his telescope and get back to more interesting pursuits, like watching daytime television. But that's not quite the end of the story.

And so it's now over to the (never-to-be-revealed) recorded flight log of the voyager on her one-way trip to the Black Hole's never-never land. Up to and including the crossover from the safe side of the event horizon to the 'abandon hope all who enter here' side of the event horizon, all is logged as 100% normalcy. Nothing shrinks, nothing grows in weight (increases in mass), and time does its one second per second thing as it always has done. It's as easy as a trip from your home driveway to the supermarket parking lot, only once in the grip of the supermarket parking lot, forever in the grip of the supermarket parking lot. It's a one-way 'enter' gate without a corresponding 'exit' sign.

Since we have no idea what the inside of a Black Hole actually is, since theoretical physics, quantum and relativity physics, break down into a mathematical mess, what our intrepid voyager will actually observe or experience is anybody's guesstimate. There does appear to be one consensus however. Gravity rules, OK? Almost by definition there's a hell of a lot of gravity to contend with once inside the supermarket parking lot - oops, sorry, inside the event horizon.

Now here on Earth, when standing up, gravity is pulling at your feet ever so slightly greater than it is tugging at your head - because your feet are slightly closer to Earth's centre of mass. Earth's gravity however is so weak that you don't know or can't feel the difference, but tests or experiments with extremely accurate atomic clocks show that this is true. Rate of change - time - is affected by gravity, so a clock atop a tall building runs slightly faster than an identical clock in the building's basement. Now the gravity of a Black Hole is many, many, many orders of magnitude stronger than it is here on Terra Firma. So, it is speculated that if you are inside a Black Hole, say in free-fall, and say in a vertical position, then the gravity pulling on your feet will be not only vastly greater than if you were on Earth, but also the differential between feet and head will be orders of magnitude greater. Translated, gravity inside a Black Hole is going to stretch you out like a piece of taffy. Like in one of those fun house mirrors, you will be very, very, very tall and very, very, very thin. Ultimately you will be akin to a piece of string or spaghetti, but by that time you'll be very, very, very dead as the human body wasn't designed to be viable under such a state of affairs. Okay, that's the consensus.

Now for the speculation: Let us suppose that our suicidal voyager survives her voyage (curses, foiled again) and gets to play tourist. What will she see or will she see anything at all? Well, yes, she will - see that is. The event horizon is like a one-way mirror. Light can pass through the event horizon into the interior of the Black Hole, but light cannot pass from the interior of the Black Hole through the event horizon to be witnessed by an outside observer. Okay, let there be light, and there was light. Light is energy, so there's energy inside a Black Hole. It's also been shown that a Black Hole has entropy, or in other words a temperature. That too is energy.

There's matter (mass) inside a Black Hole - obviously, since there's gravity. Now the big unknown is what kind of matter is that matter? We don't know. Outside of a Black Hole matter exists in four states - solid, liquid, gas and plasma. The transition from one state of matter to another is called a phase change, as in ice to water to steam. One speculation is that the matter inside a Black Hole undergoes a phase change to something even more solid and denser than, well a dense solid.

We sort of observe this in a Neutron Star, a star extremely massive with extreme gravity, but just short of enough gravity to form an event horizon and turn into a Black Hole. Why is it called a Neutron Star? Well, the gravity is so great that the bits and pieces of the atom, electrons, neutrons and protons are squashed together into one big glob. The positive protons fuse with the negative electrons - these electric charges thus cancelling out - to make neutrons, hence join with the already neutral neutrons, so everything forms into just one huge glob of neutron soup, or a Neutron Star. Rapidly spinning Neutron Stars are also known as Pulsars.

Now if atoms lose all sense of identity, there is no atomic structure, no isotopes, no molecules, no elements, no compounds, no electrons and no protons, then I'd have to define that as a phase transition, but one we don't witness on Earth. Given the even more extreme gravity inside a Black Hole, would that same phase transition to a neutron soup hold sway, or might there be another beyond that found in Neutron Stars?

Neutrons are not fundamental particles. A glob of neutron soup is ultimately a glob of quark soup, as quark trios comprise the identity we call a neutron. Neutrons are actually composite particles. However, as quarks are fundamental particles, it's unlikely they can be crushed or fused together. Electrons too are fundamental, but it is well known - to particle physicists at least - that an isolated neutron will in fairly quick-smart order decay to a proton, an electron and an anti-neutrino. Reactions are reversible so it is straightforward to create a neutron if the ingredients are brought together with sufficient energy.

Since a Neutron Star is just one coin short of a Black Hole dollar, the inside of a Black Hole could well be akin to a Neutron Star, only slightly more massive. One thing is certain IMHO, the interior will not be matter crushed down to the infinitely small (i.e. - zero volume); the interior will not be infinitely dense.

What lies at the heart of a Black Hole? The traditional answer is a 'singularity' - a point of (near) infinite density and (close to) zero volume, matter crushed down to the final, ultimate limit - or maybe not.

Start with a hunk of matter. Keep on keeping on adding more and more and more matter (mass) to it. Your original hunk grows larger, ever denser; its gravity swells in proportion. Finally it's just a fraction away from achieving Black Hole status - meaning its gravity is so strong not even light can escape from its grasp. It's that Neutron Star entity.

So you are a thimbleful of salt away from crossing the not-quite-yet a Black Hole to an actual Black Hole boundary. You can (barely) still see your now super-sized hunk of Neutron Star stuff. Now toss in that final thimbleful of stuff onto the hunk. No light now reaches you - you've crossed the threshold or boundary and have got a Black Hole. But do you doubt that lurking on the other side of the not-quite-yet a Black Hole to an actual Black Hole boundary, though unseen, you still have that super-sized hunk of stuff, not a singularity, but a really real solid 3-D hunk of stuff? Or, in other words, if the escape velocity of your hunk is 185,999 miles per second, no Black Hole and no singularity, but if it climbs to 186,001 miles per second you have a Black Hole and your hunk morphs into a singularity? A two mile a second difference makes that much difference? I don't think so.

The other issue though is this really going to be a one-way trip for our boldly going voyager, dead or alive? One of the 64,000 $64,000 questions: Can you pour stuff down a Black Hole indefinitely, or does the Black Hole have a finite capacity and ultimately or eventually will have to spew stuff out the 'other side' (i.e. - producing a White Hole) as you keep pouring in more and more and more? I'd wager the conservation relationships and principles of physics and chemistry hold sway here. What goes in ultimately comes out. That doesn't mean there's not a temporary holding vessel. Or, in more human terms, you fill what's empty; you empty what's full, but in-between those two there's storage in the stomach and the intestines; the lungs and the bladder.

Let's adopt that point of view that what goes in, ultimately has to come out.

And so, our intrepid voyager might well exit elsewhere, maybe even elsewhen. The exit could be deemed the opposite of a Black Hole, or a White Hole; the passageway from Black Hole entrance to White Hole exit is that staple of sci-fi, albeit based in the realm of theoretical physics, the Wormhole. That the exit could be elsewhen is based on the theoretical 'fact' that a wormhole could be manipulated in such a manner as to allow for time travel. If that's too far out for you, then a Wormhole elsewhere shouldn't be. The apt analogy is with an apple. Mr. Worm can crawl around the outside of the apple to get from one side to the other, or Mr. Worm could take a short-cut and worm his way through the apple to get to the other side, or elsewhere.

Now the question arises, is there any observational evidence that White Holes and associated exits exist? Astronomers and cosmologists would argue in the negative, but I'm not convinced. What would be the signature of a White Hole? Well, it would be roughly stellar-sized, not planetary or galactic. It would be vomiting out one heck of a lot of stuff including lots of energy. Does the cosmos contain such beasties? Obvious candidates are quasars - quasi-stellar objects. Quasars are roughly stellar in size, but violently emitting the froth and bubble of nearly an entire galaxy worth of stuff and energy. The other high-energy astrophysical anomaly is gamma ray bursts. They occur way out back of beyond, in the outer fringes of the cosmos, which is all to the good for if a gamma ray burst happened in our stellar neck of the woods, the results would be akin to Kentucky Fried Humans! Still, we don't know enough squat about them to be able to predict exactly where and when one will happen. So, astronomers who are into studying these cosmic critters are akin to sleeping fireman who never knows when they will be rudely awakened to respond to that rare five-alarm event.

So, in short, we have Black Holes that are your ultimate in garbage disposals; Quasars and gamma ray bursts that are your ultimate in, IMHO, recycling that garbage back into useful cosmic stuff - matter and energy. In other words, they are the exit to the Black Hole's entrance.

No matter. Either our boldly going voyager has snuffed it going into a Black Hole; is forever trapped in a Black Hole; or has been turned into a Kentucky Fried Human and vomited back out again via a White Hole quasar or gamma ray burst to become as one with the cosmos. We all started out as star-stuff - and so shall we (or what's left of our remains) all ultimately return to become star-stuff again a millennia of millennia from now.

A FEW RANDOM THOUGHTS ABOUT COSMIC BLACK HOLES

Every now and again a thought about this or that occurs to me which I then scribble down for posterity. Here are a few that relate to the concept of the astronomical object known as a Frozen Star but way more commonly referred to as a Black Hole.

# Space is not the final frontier. The ultimate challenge is to 'boldly go' past the event horizon of a Black Hole and see what's to be seen.

# One of the 64,000 $64,000 questions: Can you pour stuff down a Black Hole indefinitely, or does the Black Hole have a finite capacity and ultimately or eventually will have to spew stuff out the 'other side' (i.e. - thus producing a White Hole) as you keep pouring in more and more and more? I'd wager the conservation relationships and principles of physics and chemistry hold sway here. What goes in ultimately comes out. That doesn't mean there's not a temporary holding vessel. Or, in more human terms, you fill what's empty; you empty what's full, but in-between those two there's storage in the stomach and the intestines; the lungs and the bladder.

# A Black Hole has a finite amount of mass therefore a finite amount of gravity and therefore a finite escape velocity, even if the value of same is in excess of the speed of light - the ultimate cosmic speed limit. Somehow this makes these astrophysical objects really special. However, there's nothing different in principle vis-à-vis the Earth having a finite amount of mass, gravity and escape velocity. If Planet Earth isn't all that special for having those three properties, why should a Black Hole be?

# If an electron acquired enough mass (say by being accelerated to near light speed), would it become a Black Hole, and if so, would the 'inside' still be an electron, which after all, is considered a fundamental particle?

# Black Holes would make excellent, in fact perfect, thermos (vacuum) flasks. Pour into a Black Hole the contents of a star, say like the Sun. All that heat is then trapped and I do mean trapped!

# It's impossible IMHO to have stuff of infinite density and occupying zero volume so whatever is inside a Black Hole has finite density and occupies a finite volume.

# What lies at the heart of a Black Hole? The traditional answer is a 'singularity' - a point of (near) infinite density and (close to) zero volume, matter crushed down to the final, ultimate limit - or maybe not.

Start with a hunk of matter. Keep on keeping on adding more and more and more matter (mass) to it. Your original hunk grows larger, ever denser; its gravity swells in proportion. Finally it's just a fraction away from achieving Black Hole status - meaning its gravity is so strong not even light can escape from its grasp.

So you are a thimbleful of salt away from crossing the not-quite-yet a Black Hole to an actual Black Hole boundary. You can (barely) still see your now super-sized hunk of stuff. Now toss in that final thimbleful of stuff onto the hunk. No light now reaches you - you've crossed the threshold or boundary and have got a Black Hole. But do you doubt that lurking on the other side of the not-quite-yet a Black Hole to an actual Black Hole boundary, though unseen, you still have that super-sized hunk of stuff, not a singularity, but a really real solid 3-D hunk of stuff? Or, in other words, if the escape velocity of your hunk is 185,999 miles per second, no Black Hole and no singularity, but if it climbs to 186,001 miles per second you have a Black Hole and your hunk morphs into a singularity? A two mile a second difference makes that much difference? I don't think so.

# In our Universe there are two kinds of astronomical objects. There are cosmic faucets like stars and anything else that gives off or reflects electromagnetic (EM) waves. That's the cosmic "In Tray". Then there are cosmic sinks and drains that absorb electromagnetic waves - Black Holes, the cosmic "Out Tray".

It would seem to me that over the course of 13.7 billion years, an awful lot of EM (light, IR, UV, radio, microwave, gamma-ray, etc.) photons, not to mention neutrinos and cosmic rays, would have gobbled up and removed from the Universe's inventory by being sucked into and forever residing in the insides of Black Holes. Since all astronomical observations, hence conclusions about the state of the Universe, rely on the detection of that which is emitted or reflected by cosmic faucets, then it stands to reason that in order to arrive at valid conclusions, what cosmic sinks and drains remove from the Big EM Picture must be taken into account. But is it? I've never read any account where the removal of EM photons from the Universe's inventory has been considered.

# Black Holes won't ultimately evaporate via Hawking radiation since input of matter and energy will exceed output. In other words, more matter and energy will find there way into a Black Hole than will escape via that Hawking radiation.

SINGULARITIES: THE HEART OF BLACK HOLES AND THE BIG BANG

Singularities are fascinating objects and places, yet entirely 'inaccessible' in the sense that you can't actually go there on vacation and send back a postcard, or travel to one on a government grant as a scientific expedition and report back via a peer-reviewed article in a technical scientific journal about the local environment, geography, inhabitants, etc. In a sense singularities are like Heaven in terms of accessibility. You have to rely on intuition or theory or second-hand observations as to what's what and who's who.

Okay, for those readers I've already befuddled, I'd better tell you exactly what a singularity is! You've all heard of the phrase 'Black Hole' and not the one in Calcutta either! I refer to astronomical or cosmic Black Holes. Black Holes are 'black' because they have packed inside them so much stuff, so much mass, and hence so much gravity that not even particles of electromagnetic energy (photons) can escape their gravitational clutches. If photons, and that includes visible light photons, are jailed, can not pass go, can not collect $200, then they might as well as, as far as your perception of them is concerned, not exist. If what you don't see exists, that existence is of no matter (well lots of matter actually). Translated, Black Holes are black because visible light can't get from them to your eyeball! The absence of light is well, blackness.

So, is a Black Hole just a big lump of stuff, albeit stuff you can't see? Well, 'yes' and 'no'. First off, we can 'see' Black Holes indirectly because of their gravitational influence on stellar objects we can see. I mean if you see a star whirling around something you can't see, then the logical interpretation is that the star you can see is in orbit around something you can't see - i.e. a Black Hole. Well 'no', you can't 'see' a Black Hole because light from the Black Hole can't get away from the crush of that Black Hole's gravity.

What's all this got to do with singularities? Well, the stuff composing a Black Hole, all that stuff that clumps together and is the centre of the massive all-encompassing gravity that prohibits the photons to escape the house (Hole) that Jack built is the Black Hole's singularity. An analogy: The extent of the Black Hole is the extent of the Earth's outer atmosphere; the singularity is the solid Earth proper. So think of a nebulous outer edge with a solid core of stuff in the middle. The stuff in the middle generates the intense gravity; the nebulous outer edge marks the boundary between gravity below the threshold of light escaping and light not escaping. That boundary is referred to as the 'event horizon'; the stuff in the middle is the singularity.

Now the idea of a singularity doesn't stop with the idea behind an astronomical Black Hole. No, a singularity is any concentration of stuff or mass that has such a massive amount of gravity as to prevent photons from leaving the gravitational well or prison so created. What's the ultimate Black Hole - the Mother of all Black Holes? Well, if bits of our Universe can clump together to form astronomical Black Holes, then our entire Universe, when clumped together and in a relativity tiny state, would have been the Mother of all Black Holes and hence the Mother of all singularities. When was our Universe in such a state? Well, in the beginning!

Our Universe is expanding. That's verified by direct cosmological observation. Every cluster of galaxies has such astronomically bad 'body odour' that every other cluster of galaxies is moving out of the vicinity quick-smart! Well actually you can't have 'body odour' in space, so that's not the real reason. The real reason is that in the beginning or once upon a time, there was some sort of explosive oomph event that started the expansion process. We call that the 'Big Bang' event. At the time of the Big Bang event, our entire Universe had a close encounter with, well, our entire Universe. Our entire Universe was roughly all in the same space at the same time. Translated, if you run the film of an expanding Universe backwards, you eventually get the entire contents of our Universe on collectively very intimate terms. Such a massive collection of stuff, matter, mass, hence gravity, all of the stuffs, matter or mass that the Universe possesses, well let's just say you'd have the Mother of all singularities - in the Big Bang beginning; or anyway once upon a Big Bang time at least .

Well surely one didn't have this Mother of all singularities just sitting around for aeons then for no apparent reason go 'poof' and thus have an explosive oomph moment which kick-started things off as far as our Universe is concerned. The intense gravity of the Mother of all singularities probably would have muted any oomph to begin with; the birth of our Universe stalled at the onset.

But, let's throw some momentum into the mix. What's the opposite of a Big Bang? It's a Big Crunch! So let's propose that we have this other universe which, the bits and pieces thereof, under all those mutual gravitational attractions, is slowly, ever so slowly, but ever so surely, coming together. And as it comes together, the contracting velocity gets faster, and faster, and faster. Eventually, you have this massive collection of stuff rushing together to meet at a single point in space and in time at a fantastic velocity. There is such momentum present that the contracting Big Crunch universe just can't stop on a dime any more than an automobile going a hundred miles an hour can stop with inside of a foot of having the brakes applied. The Big Crunch at the omega point obviously forms the Mother of all Black Holes and singularities, but the sheer momentum of that contracting universe just tears the fabric of things (space and time) apart, and like a glove turning inside-out, the contraction passes through the omega point, spewing its guts out, becoming an alpha point, which is our Big Bang event and the start of our new expanding Universe.

Okay, so we have two sources that have singularities - singularities at the centre of astronomical Black Holes, and the Mother of all singularities residing inside the Mother of all Black Holes, the one that existed at the Big Bang beginning of the Universe.

We of course can't see a singularity directly (unless you're willing to take a one-way trip down a Black Hole, but even if you survived that and landed safely on the singularity, you couldn't ever broadcast back your findings - that speed of light restriction that by definition a Black Hole imparts regarding sending stuff out). So, we have to rely 100% on what theoretical equations predict a singularity to be. Unfortunately, those equations, when pushed to the sorts of mass and gravitational extremes that a singularity would represent, well you get nonsense answers. Translated, if taken at face value, the equations note that the intense gravity crushes the stuff that itself is responsible for that gravity down to a point of zero dimensions and hence infinite density.

The essential problem behind this nonsense is that gravity is represented by Einstein's Theory of General Relativity which is a classical physics smooth continuum phenomenon. That is, you can have this gravitational value, and that gravitational value, and every possible value in-between. However, tiny objects, which is what a singularity is postulated to be, is in the realm of the quantum, which is a non-continuum phenomena. Think of a staircase. You can be on this step, or the next step, but there is no step in-between the two. That is, you can have this value, or that value, but only certain other values in-between. It's also like money - you can have a five dollar bill, and a ten dollar bill, but not a six-and-a-third dollar bill, or an eight-and-three-quarters dollar bill, or even a seven or a nine dollar bill. Money and staircases are non-continuum quantum-like; money and staircases are not a smooth continuum like gravity is.

So, to adequately come to terms with the really real properties of singularities, you need a theory of quantum gravity. Alas, despite the best efforts of thousands of theoretical physicists over many, many decades, no quantum gravity theory to be had. There's no quantum gravity dice.

So, let's abandon that theoretical track and go back to common sense predictions.

Either Black Hole singularities, or the Big Bang singularity, are infinitely dense and have zero volume, or they do not. If they do not (and the alternative defies common sense and is IMHO ridiculous), then singularities have a finite volume and can grow in size as more stuff is added on. You have an original tiny singularity with extremely high, but not infinite density. You keep piling stuff onto it. For a while, the density keeps on increasing, but since it can't become infinite, there will be a point reached where further increases cease. As more and more stuff continues to be piled on, the only other option is that the size of the singularity must grow. The volume increases, and increases and increases. The upshot is that singularities can reach a size where quantum effects become negligible. Or, in other words, singularities can grow to where they aren't quantum objects any more, and while theories of quantum gravity might be still be useful in explaining their properties, it's probably no longer essential. Singularities have entered the realm of classical physics.

One property of singularities I find interesting is that the stuff that eventually forms the singularity isn't the same sort of stuff that went down the Black Hole's throat in the first place. There's been a phase transition of one kind of stuff to another kind of stuff. You're quite familiar with phase transitions in your day-to-day life. There's nothing mysterious about the concept. The most common example is steam or water vapour condensing to liquid water condensing or freezing to ice; ice melting to liquid water hence boiling or evaporating into steam or water vapour. Apart from your division into solid, liquid and gas, there's also plasma. Now the sort of matter that composes a singularity is probably something else yet again, a phase transition that only extreme gravity can achieve. That such a new state of matter exists is predicted by the following: If you have an ordinary matter star, and if it should happen to collide with an antimatter star, what you get is one hell of a big Ka-Boom; the annihilation of matter/antimatter into pure energy. However, say your matter star implodes into a Black Hole with singularity. And say your antimatter star implodes into a Black Hole with singularity. Now have these two Black Holes collide. No Ka-Boom results, just a larger Black Hole!

I don't agree, BH exists and furthermore have a rule of recycling and production and also a rule of motion.

And me who thinks that they are sphères with a mass and cosmposed by quantum sphères.

They exist,fortunally furthermore for the rotations Inside our universal sphere around the central black hohe.They permit with their enormous mass to embark stars simply.

Regards

Of course it exists several kinds of BH , sphères.But they have alsays the same rules.

A stellar BH it is the same when the carburants are finished, so it is a recycling.

A supermassif BH is central to galaxies

A primordial BH was the center of our Universe before the BB,

It is so simple that this.

The micro BH them are in our quantum world with the same relative logic considering the volumes of sphères.

Sometimes I say me , but how isit possible that so many scientists interpret our Universe like that ????

Ask to Schwarzschild ,and you shall see their diameters,11 millions for pour galaxy the milky way.

Cheers

It is not complicated when you see the GENERAL simplicity of our universal sphere in evolution and complexification of mass.

All has a rule of complementarity.If they exist, there are reasons,they have a mass, a volume, a density, an intrinsic energy,....If they were not there, how do you want that stars turn around it and be embarked around the central BH.

It is not a door you know or this or thant????