Random Thoughts About 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 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.



A Cosmos Unto Infinity: Part Two

The nature of, the size, the shape and the duration of our Universe has been speculated and debated upon ever since humans gazed in wonder at the night sky. Though ideas have waxed and waned, and though modern cosmology is more focused than ever on actual observations, speculations, well that’s still the case today. My take, albeit slightly more philosophically inclined, is that our Universe is just part of an overall infinite in space and infinite in duration cosmos. 

Continued from Part One

As we noted in the example of the fridge and your body, it takes energy to reverse entropy or at least hold it at bay. A reversal of entropy is sort of like that closed box with Maxwell’s Demon (representing energy) that controls a slot that the Demon can either open or close that’s in the middle of that closed box that’s of a uniform temperature.  The Demon opens the slot whenever a rapidly moving (hot) molecule heads toward the left side or when a slower moving (cold) molecule heads toward the right side. After a while, the left side of the box will be containing just hot stuff (rapidly moving molecules) and the right side cold stuff (slowly moving molecules). Maxwell’s Demon is like a kid expending energy sorting a bag of 1000 various coloured marbles (maximum disorder) into piles of reds and greens and blues and yellows (maximum order).  Of course our infinite cosmos contains no demons, and marble-sorting kids need not apply if there’s ever a job ad for restoring order to an infinite cosmos.

Okay, without demons (or entropy reversing kids), our infinite cosmos heads towards a state of maximum entropy or maximum disorder or maximum uniformity. The cosmic temperature will be the same everywhere; matter will be evenly distributed. But, can an infinite cosmos ever reach such a state? It could or should take an infinite amount of time, but that’s also assumed. 

Yet alas, what even an infinite cosmos needs is a Maxwell’s Demon. The cosmos, if it is to retain a state of vitality for an infinite duration, needs something that recycles stuff that’s at maximum entropy (maximum disorder) back to the basics of minimum entropy (or minimum disorder) where useful things can continue to happen.

* The Role of Gravity

Gravity seems to be a Maxwell Demon’s kind of force that keeps on keeping on. As long as you have two bits of matter, even just two electrons, you have gravity. Radiation (electromagnetism) could be dispersed evenly in infinite space over infinite time, but it is hard to imagine that situation with gravity. The only real way gravity could be rendered inert and useless as an energy source would be if it was 100% concentrated in just one place – like a super ultra mother of all cosmic Black Holes. The only other way gravity could be nullified would be in matter were distributed so absolutely evenly such that every bit of matter were being gravitationally pulled on absolutely evenly in each and every direction. But the slightest nudge or deviation from this ideal theoretical state (inevitable given quantum fluctuations) would throw everything out of equilibrium. But because matter is energy and energy is matter, if gravity can disrupt the distribution of matter from a state of near perfect uniformity, then energy will follow the short and curly material bits. Light (photons) reacts to gravity as much as electrons do. Further, the one extra nice property that gravity has is that it can’t be blocked. You can block out light or shield yourself from electromagnetic effects, but nothing will shield you from gravity.

* The Recycling Role of Radioactivity

Fortunately, there are several basic ways of recycling complex cosmic stuff back into the cosmos in the form of simple stuff. The first of these however has issues. Gravity can contract and pull together interstellar gas and dust into a proto-star which will ignite under pressure via thermonuclear fusion to form a radiant star. Stars however fuse lighter elements into heavier elements, and when a star goes nova, or becomes a supernovae, those heavier elements increasingly form the next generation of interstellar gas and dust. Eventually, after many generations of enrichment, interstellar gas and dust is lacking in those lighter elements (mainly hydrogen and helium) which easily undergoes fusion. Heavy elements, like iron, just won’t fuse any more and so the continued formation of radiant stellar stuff grinds to a halt. But, there is an escape clause.

Among the heavy elements; elements that stars manufacture, are radioactive elements with unstable atomic nuclei. Radioactive decay re-releases back into the cosmos those fundamental bits and pieces that can reform into those lighter elements that are the basic building blocks for forming radiant stellar objects. There is cosmic recycling from the simple to the complex and back to the simple again.

* The Recycling Role of Cosmic Black Holes

The second way of cosmic recycling is, believe it or not, via cosmic Black Holes. Astronomical Black Holes, via the vacuum energy (quantum foam or fluctuations) and quantum tunnelling, can release elementary particles back into the cosmos. As mentioned earlier, this is known as Hawking Radiation, after theoretical cosmologist/astrophysicist Stephen Hawking. Complex stuff can go into a Black Hole, but just very simple stuff ultimately comes back out again.

* The Recycling Role of Life

Life can be an entropy buster as in the case of Maxwell’s Demon, the kid who sorts the marbles, the mum who does the housework, the bird or beaver who gathers up forest debris to make a nest. But, it takes outside energy to accomplish these things and at the end you haven’t decreased complexity – the marbles are still marbles; twigs are still twigs. But microbes like bacteria, etc. can break down complex stuff (like twigs) and turn it into less complex stuff which can be recycled into hundreds of new and different complex things. So, when our home planet eventually meets its Waterloo, and gets scattered back into the cosmic winds, thanks to bacteria, there will be more simple stuff floating around than would otherwise be the case

So complex stuff gets recycled back into simple stuff, all brought together again by gravity to ultimately form complex stuff again. The cosmos receives recycled stuff back, from which it can keep on keeping on!    

* A Fly in the Ointment

In a cosmos that’s both infinite in space and infinite in duration, here’s an interesting ‘angels on the head of a pin’ question. There are two forces which in theory can extend their influence indefinitely, that is, unto infinity. They are electromagnetism (of which light is a prime example) and gravity. So, can the influence of a force cross an infinite space if it has an infinite amount of time to do it in?

Perhaps Maxwell Demon’s ‘closed box’ isn’t really an appropriate ‘container’ for an infinite cosmos. If the cosmos is infinite, can it be described as a closed system? 

The Multiple You

And so finally, consider and reconsider the quantum mantra: “Anything that isn’t forbidden is compulsory; anything that can happen will happen”. That’s even more the case when you have infinite time and space to play around with! So, I add to that mantra “and will happen again and again and again, an infinite number of times”. That actually means, or at least very strongly suggests that every possible scenario, every possible history, and every possible variation on each and every scenario or on any theme that you care to think of or think up will happen again and again and again. That, by the way, includes you. You are a scenario, and you, and every possible variation of you and your history will transpire numerous times; actually an infinite number of times. If that isn’t spooky, I don’t know what is, but it’s a logical consequence of having an infinite cosmos. 

A Cosmos Unto Infinity: Part One

The nature of, the size, the shape and the duration of our Universe has been speculated and debated upon ever since humans gazed in wonder at the night sky. Though ideas have waxed and waned, and though modern cosmology is more focused than ever on actual observations, speculations, well that’s still the case today. My take, albeit slightly more philosophically inclined, is that our Universe is just part of an overall infinite in space and infinite in duration cosmos. 

In the infinite beginning there was something rather than pure nothing – a finite amount of something in an infinite void of nothingness. This scenario eliminates the philosophical quandary of what’s beyond the boundary - that only other alternative. This eliminates the philosophical quandary of how much stuff there is. An infinite amount of stuff doesn’t leave you much elbow room.

In the infinite beginning, well there was no beginning; there can ever be an end. No Alpha – no Omega. This eliminates the philosophical quandary of what comes before the ‘beginning’ and what comes after ‘the end’. 

Okay, having postulated an infinite cosmos in space and in duration, well, other certain and not so philosophical issues come to the fore. If they can be addressed, well that’s all to the good. If not, well it’s back to the drawing board.

I’ll start with…

Olber’s Paradox

The night sky should be as bright as the daytime sky since in whatever direction you look, sooner or later you should see a star or galaxy that’s in your line of sight. That’s Olber’s Paradox because the night-time sky isn’t as bright as the daytime sky. One resolution is that our observable Universe is finite and there are only a finite number of stars and galaxies and thus, there will be lines of sight that do not intersect with an object that’s emitting light.

But what if the cosmos is infinite in size and has existed for an infinite amount of time? Does that resurrect or reinstate the validity or viability of Olber’s Paradox? Not necessarily.

Why is there something rather than nothing? That’s been a prime philosophical question that has raged for eons. But, on reflection, overall, there is a great deal more of nothing than of something. If everything was something, it would be rather difficult to move. There would be no elbow room. In other words, just because the cosmos is infinite in duration and in volume doesn’t mean that there has to be an infinite amount of something within.

Let’s say that pure nothing is a perfect vacuum. Then something within that nothing makes for an imperfect vacuum. One could image a cosmos so dilute that there could literally be gaps of pure nothingness between the bits and pieces of something. Or, one could imagine a universe that contained just one final cosmic Black Hole that had over all the infinite eons gobbled up everything else that had been a something within the cosmos, and thus 99.99999% of that cosmos would contain absolutely nothing. 

That aside…

Stars, like people, are born, and thus their light may not have yet reached us.

Stars, like people, die, and thus their light has ceased to reach us. It has all now passed by.

In an infinite space, stars maybe so far distant that by the time their light reaches us, it’s so diluted or spread out that only one photon per hour hits the eye and that threshold is too low to stimulate the optic nerve and thus register.  

Ever present cosmic Black Holes have gobbled up a lot of the radiation that is emitted and reflected. In fact, in a cosmos that’s infinite, why haven’t those astronomical Black Holes sucked up everything that can be sucked up thus terminating any and all evolving universes within that cosmos? Well the answer is Hawking radiation which theoretically predicts, on pretty substantial grounds, that eventually Black Holes will radiate away their mass. Once input is less than Hawking radiation output, the Black Hole will slowly, ever so slowly, radiate away, giving back to the cosmos what it once took away. There will be more on the significance of that shortly.

Entropy and Cosmic Recycling

Another concept that needs addressing is entropy or the Second Law of Thermodynamics, otherwise known as the ‘arrow of time’ or sometimes as ‘time’s arrow’. If one considers an infinite universe to be a closed box or closed system, then over time, and we have an infinite amount of it, that closed box should reach absolute equilibrium and no further cosmic evolution would be possible. There would be a maximum amount of disorder, and there would be no further energy available to reverse that level of disorder.

It should be noted from the outset that in any closed box or closed system, entropy rules. Things will go from a state of order to a state of disorder without outside interference, that being an external source of energy to reverse the natural trend. The commonly cited example is if you have a closed box (the kitchen), and you turn off the fridge, the kitchen and the fridge will eventually reach absolute equilibrium, the same temperature. The kitchen warms up the fridge; the fridge cools down the kitchen, until both are at the same temperature – maximum disorder. It takes an outside energy source – electricity – to keep the fridge colder than the kitchen and thus in a state is disequilibrium or a state where entropy has not been maximalized. Trouble is, once energy is evenly spread out throughout a closed system (like the fridge in the kitchen), no matter how much of it there is, it’s useless in terms of doing useful things – like initiating change.

Another example: Your own body is a closed system. Your body’s energy is in equilibrium. You are at 98.6 degrees Fahrenheit from head to toe. Within that state of affairs, your body can not do useful things. Fortunately, there’s a larger closed system that your body is a part of (like the fridge is part of the kitchen) that enables you to disrupt your body’s equilibrium and thus provide the means for your body to initiate change. Your outside energy source is food, which is good since once you invoke that larger closed system that contains you, that larger system absorbs your body heat that gets radiated away into it. So the fridge needs outside energy to replenish its supply of cold; you need energy to replenish your body heat and to provide the ways and means to keep you keeping on. Of course as we all know, that’s just postponing the inevitable. Sooner or later the fridge breaks down with wear; ditto you too. But in the meantime, and for a little while, you can keep your body’s entropy under control.  

Now any attempt to tunnel around various laws, principles and relationships of physics might be in vain, but not a total waste of time. The laws, principles and relationships of physics are constantly being refined, even overturned as in Einstein refined Newton’s gravity; the Sun going around the Earth got overturned by Copernicus. However, anyone attempting to tunnel over, around, or through the Second Law of Thermodynamics should abandon all hope. If you try to butt heads with entropy you’ll just end up with a sore head. You’d have better luck patenting a ‘perpetual motion’ machine, itself a violation of the ways and means of the entropy concept. In fact entropy is why you can’t construct a perpetual motion machine and why any patent officer worthy of the name would refuse you a patent for one.

Still, in an infinite cosmos, a cosmos that keeps on keeping on, there probably needs to be a way to go from a state of disorder (high entropy) back to a state of order (low entropy).

  

To be continued…

Olbers’ Paradox and Black Holes

Unless you are blind, it’s obvious to the rest of us that there is quite a difference between daytime and night-time. At night, the sky is dark! Why? Well, it’s obviously dark at night because the Sun isn’t shining in our night sky – wrong answer. In fact, if you stop to think about it, the night sky should be as bright as the daytime sky. That it’s not means there’s a paradox, usually referred to as Olbers’ Paradox (after German astronomer Heinrich Wilhelm Olbers). Resolutions have been around for yonks; I introduce another one here. 

Olbers’ Paradox: Why is the night sky dark? In our vast Universe, assuming it is static and infinite in space and time, with an infinite number of stars (or galaxies or some sort of radiating objects) in it, it would seem that no matter in what direction you looked, sooner or later your line of sight would intersect or intercept a star or galaxy or some sort of radiating object. Thus, the night sky should be as close to infinitely bright as makes no odds. Of course you know and I know that’s not the case. 

Perhaps there are massive interstellar clouds of gas and dust which, like window blinds blocking out sunlight, block out the stars, galaxies and related. Trouble is, you can only absorb radiation for just so long before the substance doing the absorption can’t absorb any more before reradiating it. Your window blinds eventually feel the heat and you will too when you touch them. However, there’s one exception to that rule and the point of this revisitation – see below.

The most logical resolution to the paradox is that there’s only a finite number of radiating objects out there and thus our line of sight could extend out to infinity and not intersect or intercept any radiating objects.

Then too, our Universe is expanding and therefore many astronomical objects (distant galaxies mainly) exhibit Doppler Effect red-shifts. This is just the Doppler Effect for an emitter of light that’s receding from us as opposed to the more familiar shift in sound to lower frequencies such as a train blowing its whistle drops in pitch as it passes and recedes away from us: same principle. Anyway, their visible light is red-shifted into the infrared which we can’t see and so therefore our line of sight assumes there’s nothing there. Two problems: firstly that just substitutes heat for light so the sky should be hot; secondly, radiation at shorter wavelengths than visible light, like ultraviolet, should be red-shifted down into the visible range.

Since our Universe is expanding, maybe the light from vastly distant objects hasn’t had time yet to reach our eyeballs and telescopes, so we can’t yet intersect or intercept their light. In fact, over time, because our Universe is expanding, distant cosmic objects are constantly slipping beyond and over our observable horizon, just like a ship at sea sailing away from us disappears over the observable horizon.

The Exception to the Rule: Here’s my new explanation, which is a supplement, not a substitute, in explaining the paradox. It’s a variation on those massive interstellar clouds of gas and dust which block out the stars, galaxies and related. 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. Maybe I haven’t read widely enough – maybe. 

One example that springs to mind of the possible significance of Black Holes is the minor temperature variations in the cosmic microwave background radiation (CMBR), that leftover heat from the Big Bang event 13.7 billion years ago – perhaps those slightly cooler spots in the CMBR are due to large Black Holes between our measuring devices and the CMBR that is sucking up those CMBR microwaves before they reach our measuring telescope or space probe or high altitude balloon. I seem to recall cosmologist George Gamow back in the 1940’s making a theoretical prediction that the (then undetected) CMBR would be somewhere between 5 to 7 degrees Kelvin, instead of the roughly 2.7 degrees Kelvin that eventuated. Perhaps, the overall cooler CMBR was due to Black Holes sucking up lots of those CMBR photons over all those billions of years.

So another reason why the night sky is dark is because in many cases when you look outwards, you intersect or intercept a Black Hole in your line of sight that’s between you and some sort of cosmic faucet further on.