Wednesday, September 15, 2010
Black Holes are quite real- You can take it to the bank!
Artist's depiction of a black hole.
Over the years in assorted capacities, as both an astronomy lecturer and writer, I've often encountered the would-be iconoclast, who somehow has the notion he can overturn solid science using a few quotations, or obscure cited papers, or some mathematical mumbo jumbo. Twenty years ago it was one Dr. Stephen Gift, from Trinidad, who avowed he'd not only "disproven" general and special relativity, but used the basis of his disproof to show a supernatural "something" existed.
It took something like four full exposes of his research methods, including pointing out his carelessness with locating his clocks vis-a-vis his "disproof" examples. As I pointed out to him, the primary condition to ensure consistency of results, is that both observers (on Earth and in the moving craft with velocity v~ c) have at least two clocks that are properly synchronized. Thus both sets of observers must include stationary clocks (or stationary 1m rules – for lengths) in their reference frames, for comparative measurements.
The coup-de-grace was administered when I requested Dr. Gift to provide an alternative explanation for the equivalence of mass and energy (via E= mc^2) validated in nuclear fission experiments, and reactions - since that famous association arose directly from special relativity. Up to now Gift hasn't provided anything - and it's been nearly twenty years! So much for mathematicians who dabble in physics and believe they can overturn formidable physical theories.
More recently, a blog commentator has come up with a new twist, arguing that black holes don't really exist but were simply a meme implanted into modern astrophysics by mathematician Kurt Gödel, as some kind of "vengeance". Evidently, he acquired this screwed-up notion from a paper by Frank Tipler, C. J. S. Clarke and G. F. R. Ellis, entitled “Singularities and horizons: A review article”, appearing in General Relativity and Gravitation: One Hundred Years after the Birth of Albert Einstein, Vol. 2, Ed. A Held (Plenum Press, New York, 1980), p. 97.
According to this contrarian, and believe me I'm not surprised here to learn Tipler (author of two crackpot books, 'The Physics of Immortality' and 'The Physics of Christianity') is the lead author, claims that Gödel "created these black holes as a proper location for the mathematical physicists who abused his good friend Albert Einstein--with a time reversal twist so that after 40 years or so they return to where they began in 1950".
Well, coming from a character (Tipler) who believes "resurrections" can emerge from physics, as well as the Virgin Mary, pardon me if I give a long loud belch. Pardon me also if I'm not astounded at the limits and levels of human gullibility, but there you are!
However, make no mistake that whatever nefarious intents or delirious visions of retribution that Gödel may have had, they were emphatically not realized in black holes. Rather, the latter emerged out of Kurt Schwarzschild's specific solution of Einstein's general relativity equations, viz.
ds^2 = -(1- 2M/r)dt^2 + dr^2/1 - 2M/r + r^2 (dq^2 +sin^2 qdf^2)
where I use 'q' in place of theta, and f in place of phi, for simplicity in symbols.
Now granted, no one has ever seen a black hole but we know how to recognize the physical evidence for its existence: very powerful and periodic bursts of x-rays, registered on sensitive satellite detectors. Mathematically, the very brief periods of less than a millisecond betray an extremely compact volume. The x-rays indicate accretion to a large mass. Together, these can be matched to predictions given in the Einstein general relativity equations and Voila! the black hole emerges as an object consistent with the observations.
In general black hole identification is predicated upon observing its effects as a member of a binary (double) star system. Thereby, the black hole presence is inferred from x-rays given off when the companion star’s gaseous layers are sucked into it. As those accreting gaseous layers are pulled through the hole's event horizon, they are condensed and the impacting plasma leads to intense heating and x-rays.
Of course, we are also aware that black holes in toto are a component of the total of dark matter that makes up the cosmos. (The total of dark matter is currently estimated at ~ 23%). One million solar masses worth of black holes in the center of our galaxy (probably a conservative number- most estimates put it at 3 million solar masses) represent a lot of dark matter. Multiply that by billions of other galaxies, in similar scenarios, and one has an enormous store of dark matter. In fact, given the number of massive stars in our galaxy, it is likely that eventually, 90 percent or more will have collapsed into black holes, especially with currently accepted lower mass thresholds for black hole formation.
Meanwhile, the total current assay of black holes may be dramatically underestimated. This is a result of difficulty of detection, as is the case with all forms of dark matter. Despite that, the research thrust goes on, along with black hole identifications in a variety of formats and scenarios.
Those who want to investigate more, can consult any or all of this sampling of research papers, from The Astrophysical Journal, on the American Astronomical Society website:
1) On the Correlations of Massive Black Holes with Their Host Galaxies
2) The Jet Power, Radio Loudness, and Black Hole Mass in Radio-loud Active Galactic Nuclei
3) Binary Mergers and Growth of Black Holes in Dense Star Clusters
4) Black Hole Advective Accretion Disks with Optical Depth Transition
5) Black Hole Masses and Eddington Ratios at 0.3 less than z less than 4http://iopscience.iop.org/0004-637X/648/1/128/fulltext
Dozens and dozens of other papers are also available, which show in concert that the black hole is no mere macguffin created by some math genius, but a valid object of inquiry worthy of serious scientific investigation.
Who were the ones that got fooled here? Seems like Kurt Gödel, Frank J. Tipler (not surprising) and all the people gullible enough to buy into what they're selling.
Will this be it for dedicated contrarians and their iconoclast brethren? Hardly! There's always one more theory, claim or imagined "sacred cow" that they're intent on goring - never mind they end up looking more like Don Quixote tilting at windmills.