How an Astronaut Falling Into a Black Hole Would Die Part 2 263
First time accepted submitter ydrozd writes "Until recently, most physicists believed that an observer falling into a black hole would experience nothing unusual when crossing its event horizon. As has been previously mentioned on Slashdot, there is a strong argument, initially based on observing an entangled pair at the event horizon, that suggests that the unfortunate observer would instead be burned up by a high energy quanta (a.k.a "firewall") just before crossing the black hole's event horizon. A new paper significantly improves the argument by removing reliance on quantum entanglement. The existence of black hole "firewalls" is a rare breakthrough in theoretical physics."
Pay wall crap. (Score:2, Informative)
The only new information cited is behind a $25 pay wall. Kill it with fire.
Non-paywalled link (Score:5, Informative)
Except that black hole "firewalls" don't exist (Score:5, Informative)
Black hole firewalls don't really exist.
Here's a summary:
http://arxiv.org/abs/1310.6334 [arxiv.org]
and the long paper:
http://arxiv.org/abs/1310.6335 [arxiv.org]
Resolving the issue.
In short, the black hole paradox doesn't exist and can be explained.
Motl has a really nice summary as well:
http://motls.blogspot.com/2013/10/raju-papadodimas-isolate-reasons-why.html [blogspot.com]
Re:So what should the family do? (Score:5, Informative)
FTFY: and getting mass to 1/3 the speed of light is currently impossible
Actually, it's very possible; about every accelerator in the world does it regularly.
Having said that, getting a macroscopic mass to 1/3 the speed of light is currently impossible. Well, at least when considered from the frame of reference in which it originally was at rest.
Re:Nearest we can see (Score:5, Informative)
That's correct. On a 1-stellar mass black hole, the tidal force across a human body at the event horizon would shredded well before you get to the event horizon. But on a supermassive black hole, no such thing would hapen.
Re:So what should the family do? (Score:5, Informative)
First off, New Horizons is travelling at 35,000 MPH, not kph. Second, those escape velocities would be at the surface of the body for unpowered bodies. Escape velocity decreases with distance from the body. It's possible to simply accelerate directly away from an object and never reach speeds anywhere close to escape velocity, until you are far enough away that you have simply exceeded (that now much lower) escape velocity threshold. So I'm not sure what point you're trying to make.
Re:Pay wall crap. (Score:5, Informative)
Fortunately, in physics, nearly everyone posts a manuscript version on arxiv.org (i.e. the same article but with the authors' own formatting, rather than the journal's layout). And indeed that is the case here [arxiv.org].
Re:Long before the event horizon (Score:5, Informative)
Find the tidal forces over that 1.5 meters. It's not a whole lot. However you start to get into time dilation, again over 1.5 meters it isn't that much.
Really now. And how did you arrive at it not being "a whole lot"? Let's insert some numbers, shall we? The mass of the sun is about 2e30 kg. Its Schwartzschild radius is, as you say, 2950 km. The acceleration according to Newtonian gravity at that point is 1.5211095e13 m/s^2. 1.5 meters further out (that's a short astronaut, by the way), the acceleration is 1.5195660e13 m/s^2. The difference is 2.057e10 m/s^2. I.e. roughly 2 billion g. Most of us would find it hard to stay together under such tension, but I guess you're made of stronger stuff!
(Of course, Newtonian gravity doesn't work very well for such strong gravitational fields. But it's enough to tell you that you're in a lot of trouble.)
Re:So what should the family do? (Score:2, Informative)
If our astronaught started to journey thence, at the beginning of the Bronze age, it would be conceivable that he'd arrive there sometime in the next couple hundred years
Nitpick: thence, hence and whence denote movement from, whereas thither, hither, and whither denote movement to. The astronaut would have to already be there to start a journey thence. Compare the well known expression "go back whence you came".
Given the rarity of these terms in modern English, I believe it is safe to assume that anyone using them is attempting to speak correctly with an air of erudition, which is why I have tried to bring this to your attention, even if this comment will likely be buried by downmodding.
Re:So what should the family do? (Score:4, Informative)
Of course space isn't really black; rather it is completely transparent.
Of course you are correct that it's not black. However, it's also not "completely transparent". It's "mostly transparent". There are stray atoms and molecules wandering around, and even gigantic clouds of gas and other matter, which all scatter light and other radiation.
If we're going to be real, then let's be real.