Episode 5: Black Holes and Beyond
This episode is about strange things in space: black holes, neutron stars,
quasars...the stuff I grew up reading about in sci-fi stories (e.g. the
Hugo award-winning short story, "Neutron Star" by Larry Niven).
The story starts with Seth Shostak, project leader for the search for
extra-terrestrial intelligence (SETI). In 1959 radio astronomy was first
used in the search for ET and accidentally found objects which emitted
radio waves. Although optical telescopes saw nothing unusual, spectroscopy
of the radio-star's (C273) light revealed a previously unknown chemical
composition. The spectrum also demonstrated that the "star" was moving
away extremely rapidly, and so must be 2 billion light years away. Based
upon the intensity of the signal, the quasi-stellar radio source (quasar)
is extremely bright, 100-1000 times brighter than our entire galaxy!
The discovery of quasars helped the acceptance of black holes, as the
latter could explain the former. Hawking himself explains that black holes
are a theoretical outflow from general relativity. Einstein and
Oppenheimer disagreed on the possibility of total gravitational collapse.
John Wheeler thought he should ?stick up for something,? and was convinced
by Oppenheimer?s calculations, but had to deal with Einstein, his
colleague. Einstein felt his theory could only go so far before defying
reality. Wheeler coined the term, ?black hole?. A century earlier, Pierre
Laplace had pondered the possibility of black holes.
In the late 60's, Richard White at Lawrence Livermore used the 1st
supercomputer (built in 1956 for nuclear bomb design) to model the collapse
of large stars and found that black holes would be formed.
Though theoretically possible, a significant experimental problem
remained: ?how could we detect one?? It would be ?sighting the unseeable.?
Gregory Banford, science fiction writer, is interviewed. Black holes
are touted as the monsters, the unstoppable eaters. But ?science fact was
way ahead of science fiction,? says Hawking.
Roger Penrose delved into the structure of black holes. What would
the inside of a black hole look like? Black holes would break the laws of
physics?a singularity. Which means a point of infinite density, which is
self-contradictory. Hawking?s Ph. D. thesis was that the beginning of the
universe would also have a singularity.
Back to quasars, the largest explosions we know of besides the Big
Bang.
Soldovitch described indirect ways to observe black holes: a binary star
system, a galactic jet. In 1988, Fillipenko observed an intense X-ray
emission. After waiting for system to quiet down, his visual inspection of
the star?s motion indicated a large gravity well was influencing it, which
could be explained by the presence of a black hole. When you have a class
of objects that can be explained with one theory, trying to explain each
object with individual theories ?doesn?t sit well.?
There are still plenty of mysteries left in the cosmos. Some galaxies
appear to have black holes at their centers, perhaps old quasars. Recently,
radiation has been shown to be able to escape black holes by quantum
tunneling, called Hawking radiation. Does this radiation contain
information? If so, we could look inside a black hole.
Back to where we started, with SETI. The confirmation of black holes
shows us that ?it?s unwise to resist unlikely ideas.? The supposed logical
conclusion is that SETI is OK. Theory says it?s reasonable that the
galaxies are teaming with life. The difference is that 36 years of
research hasn?t turned up anything. There may be civilizations way more
advanced than us.
This was Carl Sagan's statement of faith, which was most recently
preached in the movie _Contact_. IMHO, the jury is still out on whether
"theory says it's reasonable." The Drake equation is an attempt to
estimate the probability that intelligent life is out there. It contains
seven variables,[1] five of which we can't begin to estimate their values
(such as the probability of life evolving on a suitable planet and the
fraction of planets with life that develop intelligent life).
In any case, it's quite a logical leap to suggest that if a computer
model can calculate it, then it must occur, however unlikely it seems.
Other bizarre ideas mentioned in the program: wormholes, time-travel.
?Mathematically, it?s all possible.? Maybe advanced civilizations use
black holes for travel, communications. ?What is today?s unthinkable is
tomorrow?s convention.? Well, sometimes?
Throughout this episode, Hawking's interjections about his life and
work seem mere self-aggrandizement. For example, although he had
theoretically demonstrated the existence of black holes, he needed someone
to provide physical evidence so that his theories would be accepted.
Therefore, he bet Kipthorn that black hole?s *don?t* exist in reality. He
eventually lost the bet and so awarded Kipthorn with a year's subscription
to "Penthouse." What does this have to do with cosmology? Although one
can argue whether or not there is a distinctly Christian way to do
astronomy, this example from Hawking's life demonstrates that there
certainly is an un-Christian way to be a scientist.
References
1. G. O. Abell, D. Morrison, S. C. Wolff, _Realm of the Universe_,
Saunders: New York (1988), pp. 485-7.