A significant implication is that it is impossible to ever directly observe a black hole from outside the event horizon.* That's right, you will never see a black hole. So, how does one observe a black hole? Thankfully, due to the nature of black holes, scientists have developed several effective methods of observing black holes indirectly, essentially deducing their presence and properties by the black hole's effect on other, observable phenomena. Some of these techniques include:
- Gravitational lensing—Strong gravitational fields will cause light (including all electromagnetic radiation) to curve as it passes by a massive object. In a way, the light trapped within a black hole's event horizon is simply light whose path has been curved by gravity to such an extreme that it bends completely back around on itself inside the event horizon. Light passing a great distance from the black hole will be unaffected. But light passing near the black hole will indeed take a curved path, and this curving can be detected by observing objects (such as stars or galaxies) that are out of their expected positions or by noticing multiple images of one object (known as a gravitational mirage).
- Accretion discs—Black holes will attract gas particles, which will then form a disc spiraling into the black hole which can be observed directly. Although many cosmic bodies can create an accretion disc, the presence of an accretion disc with no observable center object is indicative of a black hole.
- X-rays—As gas is drawn into the black hole from the accretion disc, it will superheat, releasing energy, in particular X-rays, which can be detected. In fact, this is one of the most energy-efficient processes ever observed, transforming up to 40% of the matter to energy. This process occurs just outside the event horizon, enabling the x-rays to escape the black hole's gravitational field. In many cases, the x-rays will be released from electromagnetic poles perpendicular to the accretion disc via relativistic jets (often shown on diagrams of black holes, such as those below).
- Black hole binary star systems—In some binary star systems (where two stars orbit around a common point), one of the stars is a black hole which cannot be seen, but its gravitational effect on the companion star can be detected. A famous example is Cygnus X-1.
- Gamma ray bursts—These are short bursts of high energy radiation which occur when a large star collapses into a black hole after a supernova, or when two black holes or a black hole and a star collide to form a bigger black hole.
- Quasars—Quasars are supermassive black holes at the centers of young galaxies that emit a high volume of x-rays from a large accretion disk.
- Gravitational waves—Fluctuations or distortions in space-time are caused by the movements of certain massive objects, including black holes, and those distortions then ripple out from the object. Although the techniques are still experimental, scientists hope to eventually detect black holes by detecting gravitational waves.
So, what do black holes have to do with poker? Well, other than the obvious analogy that poker seems to suck all of the interpersonal skills and human decency out of the souls of some players ...
Black holes came to mind during my last live poker session because of the concept of indirect detection. I sat down at a 2/5 NLHE table, and there were a few regulars as well as a few players I did not know (which is rather unusual for the Meadows ATM). Two of the regulars are players whose games I respect. One is rather loose preflop, the other is rather tight, but both players are solid postflop players, aggressive when possible, cautious when necessary, but rarely putting chips into the pot without a good reason. Early on, I was fairly card dead, so I wasn't playing a lot of hands. However, by watching the two players I did know, I got a feel for the table. Two of the newbies could be bullied. One was a calling station. Most importantly, there was one newbie with a bigger stack who was given respect by the players I knew. When this newbie played a hand, the regulars showed respect to his bets and raises, and never made moves on him. Clearly, then, two players who I respected felt that this newbie was a solid player and stayed out of his way.
So, about an hour into the session, I found AQ on the button. Limped to me, I made a standard raise, solid new guy was the only caller in early position. Flop was A-K-Q rainbow. Yahtzee! New guy checked, I bet 1/2 pot, new guy check-raised for 3x my bet, his standard raise. Now, there are some players who check-raise that flop with any two cards, hoping I have a pocket pair under the board. But given that the regulars respected him, I was worried about the check-raise. A hand that limp-called preflop out of position, then check-raised the flop could easily be something like AK or QQ, possibly JTs. There weren't many hands a tight player would play that way that I could beat. I finally laid it down, deciding there were softer spots at the table. Though I rarely do it, I mucked face up, and the newbie smiled and obligingly showed AK.
So, even if you don't have personal history with a player, you can still get a read on him from observing how he interacts with other players, and how other players react to him. Also, a cool way to deal with table d-bags is to throw them into a black hole.
* It's also pragmatically impossible to observe a black hole from inside the event horizon, even setting aside the impossibility of ever sending a signal from inside the event horizon to anyone outside the event horizon to describe any observations that might be made. As an observer crossed the event horizon, he would be destroyed as gravitational tidal forces caused spaghettification—essentially, if falling feet first, his feet would be accelerate faster than his head due to stronger gravitational forces, causing his body to be stretched and eventually ripped apart. However, all the observer's matter would eventually join the singularity, which would be a rather cool way to go, if you ever get to pick the way you go.