A Trip Inside A Black Hole: Part Two

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 crewmember willing to boldly go. What might she expect? For that matter what might a chickenhearted outside observer expect to see?

Continued from yesterday’s blog…

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 antineutrino. 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 shortcut 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 starstuff – and so shall we (or what’s left of our remains) all ultimately return to become starstuff again a millennia of millennia from now. 

Gamma-Ray SETI

Gamma-ray bursts are cosmic phenomena. As far as terrestrial astronomers go, they are unexpected (you can’t point your telescope in advance knowing where and when one will happen) and they are short-lived (so when one is detected you have a rather limited window of opportunity to point your telescope). Now, the question arises, are they all totally natural phenomena, or could some be manufactured, and like artificially generated radio waves, perhaps contain a message in a cosmic bottle? - A message of interest to those who seek out new life and new civilizations.

SETI (Search for ExtraTerrestrial Intelligence) scientists search for ET’s intelligent messages in the radio spectrum; and also in the visible region of the electromagnetic spectrum. Should they, despite the inherent difficulties, take the opportunity to analyse gamma-ray bursts for a signal in the gamma radiation noise? If they in fact they already have been examined for a signal I’m unaware of it or any such analysis and conclusions. It’s those unexpected and short-lived aspects that make gamma-ray SETI difficult in the extreme. It’s like sometime in the next 24 hours, on just one radio station, in some unspecified part of the world, lasting for only ten seconds, you will hear a voice. Good luck picking it up.

Gamma-ray bursts were discovered accidentally by the Vela series of satellites. The Vela satellites were sent up by the Americans to keep tabs on those naughty commies and to make sure they didn’t violate the Nuclear Test Ban Treaty. The Vela satellites indeed picked up one of the telltale signatures of atmospheric nuclear explosions (gamma-rays), except they weren’t coming from Terra Firma or within our atmosphere, but somewhere out there – way, way, way out there. Though first detected in 1967, the anomalous nitty-gritty details weren’t made public until about six years later – well these after all were top secret military spy-in-the-sky satellites.

Anyway, it was quickly realized that these cosmic gamma-ray bursts were coming from really, really far away. They weren’t sourced locally; they weren’t sourced at interplanetary distances, or even at interstellar distances. They were happening in galaxies far, far away, so far, far away that they happened a long, long time ago too (since it takes electromagnetic radiation, of which gamma-rays are a part thereof, finite times to cross finite distances). To cross such vast distances with such energy intensities suggested that gamma-ray bursts were not akin to a galaxy what a firecracker is to Planet Earth. Rather, it was more a galactic case of, well a terrestrial super-duper nuclear explosion on Planet Earth. 

Now gamma-rays are very high energy electromagnetic photons, more energetic than ultraviolet and X-rays. Even before the detection of those intergalactic gamma-ray bursts, we knew about gamma-rays since they are a natural product of electron – positron annihilation and of some radioactive decay processes.

So much for some background on gamma-rays and astronomical bursts of gamma radiation, how might that apply to SETI? Let’s assume that there is at least one highly advanced technological extraterrestrial civilization somewhere out there, who wishes to draw attention to themselves via a signal of some sort (which is not quite the same thing as actual one-on-one communication).  That desire might be akin to a more relevant terrestrial analogy like an anomous show-off graffiti artist – “here I am; I exist”. How would, or at least could, our ET do it?

Now what’s the biggest cosmic bang advertisement for your buck you can get? My understanding would be matter-antimatter annihilation. If an electron meets a positron, you get a gamma-ray. So, I wonder whether the rather anomalous and unpredictable gamma-ray bursts that are somewhat common, but not too common in the cosmos, might, or at least some of them might, be artificially created by that highly technological extraterrestrial civilization or perhaps, if plural, those extraterrestrial civilizations. An alien ‘message’ (as it were) or signal, in plain sight.

Here’s another possible scenario. Say once upon a time, billions of years ago, you had various, even numerous, high-tech extraterrestrial civilizations in various galaxies. In the classification scale of ET civilizations they would fall somewhere between a Type II (mastery of the energy output of a stellar object) and a Type III civilization (mastery over the energy resources of an entire galaxy). They shared information (‘communication’ in real time being out of the question due to the intergalactic distances involved) via radio waves, laser beams, etc. It’s efficient to send an electromagnetic packet of info in a tightly compressed, and short-lived, burst. In-person travel to and on-site visitations, possible in interplanetary and interstellar scenarios, are impossible when it comes to intergalactic scenarios. The distances are just too vast.

Now, Cosmology 101, the expanding universe, tells us that most galaxies are moving away from most other galaxies. To keep intergalactic ‘communications’ or data sharing viable over the long term, you need to shout louder as time goes by; as your neighbouring or nearby galaxies gets farther and farther away from you. Gamma-ray bursts are ‘louder’ than most other energetic phenomena in the Universe. The basic data sending principle is the same. If you can use light waves or radio waves, etc. to send a message, why not a gamma-ray?

The drawback is that this is really high-energy expenditure. But, if you are a Type II or Type III civilization, ‘burning’ this amount of energy is akin to a billionaire lighting a match.

Now the odds are very high that in all probability, gamma-ray bursts are a totally natural phenomenon, albeit still a very mysterious one. But, you never know. I think it premature to rule out ET, at least until such time as we have a better grounding in the theory behind them and/or do a detailed analysis of a typical gamma-ray burst happening looking for some signal in the cosmic noise but not finding any.