Hawking with
Nobel laureate Gerard t'Hooft in Stockholm. (KTH)
On Tuesday,
famed physicist Stephen Hawking presented new theories on black holes to a
crowd of esteemed scientists and members of the media at KTH Royal Institute of Technology in
Stockholm.
Hawking
focused on something called the information paradox, which continues to puzzle
scientists who study black holes. In a nutshell, the paradox involves the fact that
information about the star that formed a black hole seems to be lost inside it,
presumably disappearing when the black hole inevitably disappears. These things
cannot be lost, according to the way we think the universe works, and
physicists generally believe that they aren't really lost. But
where does the information go when the black hole that's absorbed it goes
kaput?
It's brainy
stuff, but without an explanation for the apparent paradox, some of the most
basic laws we think exist in the universe are at stake. At a public lecture in Stockholm on
Monday, Hawking implied that our concept of time
itself could fall apart if black holes proved to be exempt from such laws.
see video below
On Tuesday,
he explained his new theory: "I propose that the information is stored not
in the interior of the black hole as one might expect, but in its boundary, the
event horizon," Hawking said. The event horizon is the sort of shell
around a black hole, past which all matter will be drawn into the dense
object's powerful embrace.
According to
Hawking's idea, the particles that enter a black hole leave traces of their
information on the event horizon. When particles come back out — in a
phenomenon called Hawking Radiation — they carry some of that information back
out, preserving it. Technically, anyway.
"The
information is stored in a super translation of the horizon that the ingoing
particles [from the source star] cause," he explained, for those of you
who like a little more physics lingo. "The information about ingoing
particles is returned, but in a chaotic and useless form. For all practical
purposes the info is lost."
At Monday's public lecture, he explained this jumbled return of
information was like burning an encyclopedia: You wouldn't technically lose any
information if you kept all of the ashes in one place, but you'd have a hard
time looking up the capital of Minnesota.
The translations that
occur form a sort of hologram of the original particles, Hawking said — a hologram in the sense that
3-D information is recorded on a 2-D surface. When radiation leaves the black hole, it carries some of that
information preserved on the event horizon with it.
Nobel
laureate Gerard t'Hooft, who was present for the discussion, has been
thinking about information loss in a similar way, and he cited several papers he has published on
the subject. It will take more
discussion — and much comparing of math equations — to establish what's new
about Hawking's theories in relation to t'Hooft's, and whether Hawking has
overcome some of the issues associated with earlier iterations of the idea.
It's worth noting
that Hawking — who drew a large crowd of Swedish journalists on the morning of
his announcement — is not alone in presenting big new ideas on black holes this
week. Hawking's presentation was part of a week-long conference on black holes
organized by University of North Carolina at Chapel Hill physicist Laura Mersini-Houghton and The Nordic Institute for Theoretical Physics (Nordita).
Hawking and his colleagues — some of the greatest minds in theoretical physics
— are hoping to answer some of science's most burning questions about how black
holes work. You can read more about the conference here.
The Washington Post
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