Black Holes
Aren't
(20 June 2007) "Nothing there," is
what Case Western Reserve University physicists concluded about black holes
after spending a year working on complex formulas to calculate the formation of
new black holes.
In nearly 13 printed pages with a host of
calculations, the research may solve the information loss paradox that has
perplexed physicists for the past 40 years.
Case physicists Tanmay
Vachaspati, Dejan Stojkovic and Lawrence Krauss report in the article,
"Observation of Incipient Black Holes and the Information Loss Problem," that
has been accepted for publication by Physical Review D.
"It's
complicated and very complex," noted the researchers, regarding both the
general problem and their particular approach to try to solve it.
The
question that the physicists set out to solve is: what happens once something
collapses into a black hole? If all information about the collapsing matter is
lost, it defies the laws of quantum physics. Yet, in current thinking, once the
matter goes over the event horizon and forms a black hole, all information
about it is lost.
"If you define the black hole as some place where you
can lose objects, then there is no such thing because the black hole evaporates
before anything is seen to fall in," said Vachaspati.
The masses on the
edge of the incipient black hole continue to appear into infinity that they are
collapsing but never fall over inside what is known as the event horizon, the
region from which there is no return, according to the researchers.
By
starting out with something that was non-singular and then collapsing that
matter, they were determined to see if an event horizon formed, signalling the
creation of a black hole.
The mass shrinks in size, but it never gets to
collapse inside an event horizon due to evidence of pre-Hawking radiation, a
non-thermal radiation that allows information of the nature of what is
collapsing to be recovered far from the collapsing mass.
"Non-thermal
radiation can carry information in it unlike thermal radiation. This means that
an outside observer watching some object collapse receives non-thermal
radiation back and may be able to reconstruct all the information in the
initial object and so the information never gets lost," they
said.
According to the researchers, if black holes exist, information
formed in the initial state would disappear in the black hole through a burst
of thermal radiation that carries no information about the initial
state.
Using the functional Schrodinger formalism, the researchers
suggest that information about the energy from radiation is long evaporated
before an event horizon forms.
"An outside observer will never lose an
object down a black hole," said Stojkovic. "If you are sitting outside and
throwing something into the black hole, it will never pass over but will stay
outside the event horizon even if one considers the effects of quantum
mechanics. In fact, since in quantum mechanics the observer plays an important
role in measurement, the question of formation of an event horizon is much more
subtle to consider."
The physicists are quick to assure astronomers and
astrophysicists that what is observed in gravity pulling masses together still
holds true, but what is controversial about the new finding is that "from an
external viewer's point it takes an infinite amount of time to form an event
horizon and that the clock for the objects falling into the black hole appears
to slow down to zero," said Krauss, director of Case's Center for Education and
Research in Cosmology.
He continued "this is one of the factors that led
us to rethink this problem, and we hope our proposal at the very least will
stimulate a broader reconsideration of these issues."
If black holes
exist in the universe, the astrophysicists speculate they were formed only at
the beginning of time.
(source: Case Western Reserve
University)