One of the jobs of science is to teach us how very deceptive appearances can be. Cells are not just blobs of goo, but entire cities of information. Blue eyes contain no blue pigment; the scattering of light makes unpigmented eyes appear blue, just as Rayleigh scattering gives a blue color to the sky. And black holes may not exist after all, despite Zathura and other wonderful movies that show small children getting sucked into them.
From our youths we are taught about black holes, those giant vacuums at the centers of galaxies, around which billions of stars swirl in lovely spirals. Observatory scientists capture images of these spiral galaxies with the Hubble Space Telescope and Chandra X-Ray Observatory, and they puzzle about the full nature of black holes and big ideas like general relativity and quantum theories of gravity. Black holes are believed to be the result of giant stars that collapsed into insanely dense balls of matter that create intense gravity. Once particles, space chunks, stars and even light pass over the event horizon — the no-going-back lip of the black hole — they get pulled in and crammed into the same tight space, adding their mass and gravity to the singularity at the center.
Now, one physics professor argues that black holes are mathematically impossible. Laura Mersini-Houghton, a physics professor at the University of North Carolina at Chapel Hill, recently finished a paper describing problems with black holes forming in the first place. Famous physicist Stephen Hawking predicted in 1974 that black holes give off a small bit of radiation, which has been called Hawking radiation as spots consistent with this radiation have been detected across the Universe. Mersini-Houghton argues that in the process of collapsing under their own gravity, giant stars would continue to give off Hawking radiation, losing mass in the process. The shedding of mass as the stars collapsed would prevent them from continuing to collapse into a singularity, a single point in space. An event horizon would never develop, and therefore black holes would never form.
The press release says something very interesting and controversial: “Many physicists and astronomers believe that our universe originated from a singularity that began expanding with the Big Bang. However, if singularities do not exist, then physicists have to rethink their ideas of the Big Bang and whether it ever happened.”
Denying that black holes exist? Questioning the Big Bang? The atoms are already flying in little explosive bursts throughout the scientific community. Mersini-Houghton’s math had better be faultless or other physicists will dust bin her ideas without even a nod.
Mersini-Houghton did not work the math all alone. Harald Peiffer, an expert on numerical relativity at the University of Toronto, collaborated with her on the effort. Yet, physicist and science writer Matthew R. Francis faulted the media for jumping on the idea that black holes don’t really exist, especially since the paper hasn’t been peer-reviewed. Francis read Mersini-Houghton’s paper, and he says, “The calculations are perfectly correct, as far as I can tell. However, the authors seem to have a lot more Hawking radiation in their model than other similar calculations—and the entire conclusion seems to be based on that large amount. Since the Hawking radiation at any given point in time is small for a realistic stable black hole, there seems to be something amiss.”
Something is amiss because black holes do exist, Francis insists, echoing the cry of his peers. Physicists have been studying black holes for decades. At least, by all accounts, large sources of massive gravity do sit at the center of spiral galaxies. Physicists have measured the speeds of gas clouds swirling around the center of the M87 galaxy and have determined that an object 3 billion times more massive than our sun exists in a space smaller than our solar system. X-ray emissions from Cygnus X–1 (and a dozen other galaxies) offer evidence for black holes at their centers.
Stephen Hawking himself made headlines this spring when he said black holes didn’t exist. The media jumped on that one too, but Hawking’s paper actually declared that black holes had a different nature than previously thought. He attempted to deal with the “information paradox” associated with black holes. Black holes have long been thought to utterly annihilate the ‘information’ in the particles that get crushed into their singularities – and yet, quantum mechanics predicts that information cannot be destroyed. Hawking argued that black holes do not have an event horizon past which nothing can ever escape for all eternity. He suggested black holes instead have an apparent horizon, one past which objects do get sucked into the black hole, but information can eventually escape.
If there are variables we can’t measure, though, our ideas might be altogether wrong. If our fundamental assumptions about light wave data are off, our mathematical speculations might be in error. There may be high-gravity massively dense objects at the centers of galaxies that are not black holes, and so all the worries about information paradoxes might be moot.
The fact is that nobody has ever gone to visit a black hole, and so all the theorizing we have must be based on the information we can gather from distant light sources (including X-ray emissions). We can capture light wave data from a multitude of galaxies. We can see the swirling pattern of the stars in those galaxies, and we can attempt to measure the rate of the swirling and then calculate the size and gravity of the central objects that cause the vortex. Yet, the speed of light may have been slowing down since the beginning of the Universe (see link below) confusing our measurements about the rate that galaxies spin. No matter how comfortable our current models, scientists must be always open to alternative ideas, especially when we have conflicting information coming our way. One of the jobs of science is, after all, to show us how deceptive appearances can be.
Black Holes Exist. So Does Bad Science — The Daily Beast
Rethinking the Origins of the Universe (Link to Mersini-Houghton Papers) — UNC Press Release
M51: Chandra Captures Galaxy Sparkling in X-rays — Chandra X-Ray Observatory
The Controversy Continues: Speed of Light Slowing Down? — Koinonia House