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Stephen Hawking's Last Paper Is Now Online (vice.com)
An anonymous reader quotes a report from Motherboard: When Stephen Hawking died in March at the age of 76, the world mourned a beloved and visionary scientist. But it is some consolation that Hawking's final paper has now been published on the preprint journal ArXiv, demonstrating that even during his last days, he was still pursuing the epic cosmic questions that defined his career. Entitled "Black hole entropy and soft hair," the paper was authored by Hawking along with physicists Sasha Haco, Malcolm Perry, and Andrew Strominger. The work is the third in a series from the team and addresses Hawking's famous brainchild -- the black hole information paradox. Like many physics conundrums, the paradox emerges from the lack of coherence between quantum field theory and general relativity. On the smallest scales of matter, where atoms and quarks abound, there exists a different and seemingly contradictory set of rules to the largest scale of matter, involving stars and galaxies. The search for a "theory of everything" that reconciles these two models is one of the holy grails of modern physics, and was a lifelong fascination for Hawking.
Black holes are notable flashpoints for this tension between quantum field theory and general relativity. According to the quantum rulebook, it should be impossible for information about a particle -- its spin, configuration, mass, and other features -- to be permanently deleted from the universe. But what about matter that falls into black holes, objects with a reputation of not letting anything escape once it passes the event horizon? Can information be scrubbed inside black holes? Hawking suggested that information could indeed be deleted through Hawking radiation, which is a type of theoretical radiation that can escape from inside a black hole. This process has never been empirically observed, but the radiation would supposedly be stripped of all information about its original properties -- and that would violate the rules of the universe as we know them. In his last paper, Hawking and his colleagues speculated that a phenomenon called "soft hair" might resolve the black hole information paradox. The idea is that trails of light and gravity particles might encircle the event horizon, and could store, at the very least, entropic information about matter that fell into the black hole.
Black holes are notable flashpoints for this tension between quantum field theory and general relativity. According to the quantum rulebook, it should be impossible for information about a particle -- its spin, configuration, mass, and other features -- to be permanently deleted from the universe. But what about matter that falls into black holes, objects with a reputation of not letting anything escape once it passes the event horizon? Can information be scrubbed inside black holes? Hawking suggested that information could indeed be deleted through Hawking radiation, which is a type of theoretical radiation that can escape from inside a black hole. This process has never been empirically observed, but the radiation would supposedly be stripped of all information about its original properties -- and that would violate the rules of the universe as we know them. In his last paper, Hawking and his colleagues speculated that a phenomenon called "soft hair" might resolve the black hole information paradox. The idea is that trails of light and gravity particles might encircle the event horizon, and could store, at the very least, entropic information about matter that fell into the black hole.
Having had several hard drives fail I would like to assure the physics community that information can in fact be deleted.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
Having deleted several Facebook profiles worth of data, I can assure you, data can be lost. Wait.. Mark - Are you seriously telling me that you retain everything? Hmm... Just as I thought. Facebook is a Black Hole.
"Hawking's last paper gives new insights on physics" would have been juicy, but "last paper is online" resembles the note that left my grandma on the fridge before passing away, except she was much less famous.
Slashdot, fix the reply notifications... You won't get away with it...
... wherein bright theoretical scientists try to straighten a persistent bend in their discipline that moves away from their area of expertise.
Hawking essentially says that the information comes out of the black hole, but not in a useful form that could, in theory, be used to construct an original.
Useful to whom?
Just because we can't recognize the processed information and trace it back to its original state doesn't mean shit.
The universe made us. It doesn't need use to put it back together again.
Einstein went down a similar path. He worked all his life trying to extend his theories to perfection.
With almost predictable regularity, Einstein came up with a new Theory of Everything and, like Hawking, provided no opportunity to test the ideas.
Meanwhile, younger theorists, about the same age as Albert had been in his prime, had moved on.
Einstein died trying to take dice away from God.
Hawking, like Newton and Einstein, was one of the rare talents that pop up throughout history and he deserves accolades and honours for his work.
It little behooves the best of us to comment on the rest of us.
Consider an object P positioned at (x,y,z) at time t. I'm just gonna write this event as (x,y,z,t). How do you feel about this?
In an Euclidean universe that would still just be a sequence of concurrent observations like (x,y,z,1), (x,y,z,2), (x,y,z,3) and so on. It's a bit like I can have however many space dimensions I want if they're a constant 0. It doesn't get interesting until you have the theory of relativity with curved spacetime where objects have different velocities through time. The math of time dilation is pretty well tested and proven by now, we can send an atomic clock up in a GPS satellite and predict how much it will be off compared to a clock on the ground.
I guess what the GP is saying is that this is a form of illusion, time is constant it's our time-keeping devices that are off. But it also slows down every other natural process, like if you put a radioactive isotope on a GPS satellite it would decay slower than here on earth. It really is the pulse of the universe slowing down as it moves quicker through space, not just a flaw in our clocks which means to redefine time you'd also have to redefine all the formulas that use time.
So you could define time t0 in the unaccelerated frame but to every formula you'd add an unaccelerated-to-accelerated correction factor exactly equal to the Lorentz factor 1/sqr(1-v^2/c^2). So distance would not be v*t but v*t0*1/sqr(1-v^2/c^2). Except most of the time that would be a gigantic pain in the ass as we are in the same frame of reference and the formulas work quite fine without converting out to an absolute time and back again. Those who need to deal with different frames or change of frames understand the math just fine and for the rest of us time is best defined as "local" time.
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