We take it from your comments on last week's SciShow News that
a lot of you really, really do not like or
at least don't care about american football.
We totally get it.
Message received.
So how about this:
Are you ready for some physics?
Every now and again we've got to clarify
some important concepts
that come up in the news
that the news doesn't...
particularly cover very well.
That happened last week
when none other than Stephen Hawking
appeared on Google News home pages
and Tumblr dashes everywhere,
under headlines announcing that
Hawking had suddenly declared
that "Black Holes Do Not Exist!"
The exact quote that you might've heard
was Hawking having written in a recent paper
"There are no black holes"
That's right.
Actually,
it's not at all right.
But, it is what a lot of the headlines said.
Naturally,
the whole of the internet
took the "TL;DR" route
and didn't bother actually reading
what Hawking wrote.
I understand that
that's what we're here for
instead a lot of people took it to mean
that there was some kind of major
breakthrough in astrophysics
or maybe
some major breakdown in astrophysics
or as one news site put it
maybe Hawking just changed his mind
to better understand what Hawking is actually talking about
lets dial it back like, maybe, like forty years
that's when Hawking first introduced
the idea that black holes
aren't really what we thought
the prevailing model of black holes
the one that you are probably
familiar with
is that of an infinitely dense
powerful singularity
surrounded by a boundary known as
an event horizon
and anything that's inside
of this event horizon
get's sucked into the black hole
anything that's outside of it
can't see
cannot observe
the stuff beyond the event horizon
but 1975
Hawking blew minds
everywhere with his calculations
that showed
that black holes actually
radiate energy
it's that all bunch of ramification for the universe as we know it,
but one of them was the implication that black holes will in time
eventually radiate out all of their energy until they simply vanish
so this, in turn raise the question of what actually happens to all the stuff that's gotten sucked
into the black hole before it disappears and by stuff
i don't just mean matter or light or anything else that you can actually detect
i'm also talking about properties of that matter and light
that define those things at a particular point in time
physicist referred to this simply as information
one of the many challenges posed by Hawking's evaporating black hole idea
was the fact the laws of physics at least as we understand them
require that all of the information in the universe be conserved
even if the information gets sucked into a black hole, it has to go somewhere
it can't just fade away.
So to make room for this law, Hawking has revisited the idea of the event horizon
in his latest paper given as a model lovely title of Information Preservation and
Weather Forecasting for Black Holes
Hawking suggest that maybe black holes don't have event horizons,
maybe instead they have what he calls apparent horizons
boundaries that are essentially as temporary as the black holes themselves
so, when the black hole evaporates, the apparent horizon goes with it
and theoretically at least all that precious information that was
hoovered into the black hole gets released back out in the universe somewhere, sometime
So a lot of us heard Hawkings saying there are no black holes
but, what he really said was the absence of event horizons means there are no black holes
in the sense of regimes from which light can't escape to infinity
there are, however apparent horizons which persist for a period of time.
Sounds a little different when you hear the whole sentence
and Nooo,
it is not an issue of Hawking changing his mind, although it would have been
perfectly fine if he did. In fact, in Hawking's latest paper he does the opposite
and reinforces the revolutionary ideas that he first introduced forty years ago--
--ideas that helped make him one of the most important physicists of our time.
This of course is the formatted version of what Hawking says about black holes
we've included the link to his paper in the notes below for you to look at yourself
because this stuff is complicated, just a little bit more complicated than football.
Thanks for watching this episode of SciShow news which is brought to you
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