Astrophysics: Fire in the hole! (Black hole firewalls, relativity vs. quantum mechanics)

Nature ^ | 4/3/13 | Zeeya Merali

[LibWhacker]

n March 2012, Joseph Polchinski began to contemplate suicide — at least in mathematical form. A string theorist at the Kavli Institute for Theoretical Physics in Santa Barbara, California, Polchinski was pondering what would happen to an astronaut who dived into a black hole. Obviously, he would die. But how?

According to the then-accepted account, he wouldn’t feel anything special at first, even when his fall took him through the black hole’s event horizon: the invisible boundary beyond which nothing can escape. But eventually — after hours, days or even weeks if the black hole was big enough — he would begin to notice that gravity was tugging at his feet more strongly than at his head. As his plunge carried him inexorably downwards, the difference in forces would quickly increase and rip him apart, before finally crushing his remnants into the black hole’s infinitely dense core.

But Polchinski’s calculations, carried out with two of his students — Ahmed Almheiri and James Sully — and fellow string theorist Donald Marolf at the University of California, Santa Barbara (UCSB), were telling a different story1. In their account, quantum effects would turn the event horizon into a seething maelstrom of particles. Anyone who fell into it would hit a wall of fire and be burned to a crisp in an instant.

The team’s verdict, published in July 2012, shocked the physics community. Such firewalls would violate a foundational tenet of physics that was first articulated almost a century ago by Albert Einstein, who used it as the basis of general relativity, his theory of gravity.

[Jonty30]

I’d prefer to hit that firewall myself, then be continually stretched and spaghettified.

It does make sense that, at some point, you would hit something in the black hole. As small as those particles would be, they’d be clumped together to be like cement.

[WhiskeyX]

The reason the astronaut cannot tell thee difference is because he/she is stretched only from the perspective of an eexternal observer. From the astronaut’s point of view the space is almost normal, aside from the distortion of the field of view.. By the time the astronaut is about able to observe a difference, thee astronaut is virtually frozen in time and thought at the same time as being disintegratedd as the space becomes dimensionless.

[SargeK]

Ford: “It’s unpleasantly like being drunk.”

Arthur: “What’s unpleasant about being drunk?”

Ford: “Ask a glass of water.”

[mikrofon]

I fell into a burnin’ ring of fire
I went down, down, down
And the flames went higher,
And it burns, burn, burns,
The ring of fire, the ring of fire.

[SunkenCiv]

Thanks LibWhacker.

[SunkenCiv]

Thanks LibWhacker.

Polchinski’s calculations, carried out with two of his students -- Ahmed Almheiri and James Sully -- and fellow string theorist Donald Marolf at the University of California, Santa Barbara (UCSB), were telling a different story1. In their account, quantum effects would turn the event horizon into a seething maelstrom of particles. Anyone who fell into it would hit a wall of fire and be burned to a crisp in an instant. The team’s verdict, published in July 2012, shocked the physics community. Such firewalls would violate a foundational tenet of physics that was first articulated almost a century ago by Albert Einstein, who used it as the basis of general relativity, his theory of gravity.

Einstein? What a loser. ;')

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[left that other site]

LOL.

First it was Aristotle.
Then he got displaced by Galileo and Copernicus.

Then it was Newton.

But he got outpaced by Einstein.

And we though Einstein settled things.
But then came these guys and their theory of strings!
These new theories have everyone talking
And good grief, what has become of Stephen Hawking?

[Fred Hayek]

The astronaut would be killed first by the X-rays from the superheated gasses falling into the black hole. Then burned. Whatever is left over would be rent asunder by the gravity gradient before hitting the event horizon.

[Born to Conserve]

They have no idea, but they take our grant money, and have to say something. They get together and have meetings about what direction to take their theories, with the number one criterion being the maximization of grants. They are fools. Expensive, egotistical fools. What they say is lies.

They don’t even know if Einstein’s equations are correct out to the “limits”. They just assume. And get grants.

And when they get senile, they become “Discover Channel Commentators”.

Arrogant fools.

[dr_lew]

The reason the astronaut cannot tell thee difference is because he/she is stretched only from the perspective of an eexternal observer. From the astronaut’s point of view the space is almost normal, aside from the distortion of the field of view..

This is incorrect. The "stretching" etc. is due to tidal effects, which are no different than those responsible for the Roche limit for bodies in orbit. Inside this limit they will be disrupted by "tidal", or differential effects of gravity, even though they are in free fall.

The difference is that as one approaches a black hole, these effects become very large even over small distances. For example, if the earth were shrunk to 1/100 its radius, making it 1 million times as dense, then a pair of objects in the new LEO, would have a radial stretching tidal field of about 1 g/meter, so if they were tethered together by a 1 meter rope in the radial direction, the tension in the rope would be the same as if one of the objects were hanging by it in the real 1 g gravitational field of earth. Here's my calculation ... really!

[steve86]

I take it you live in one of those alternate multiverses they talk about?

[WhiskeyX]

You neglected the time dilation effects as the approach to the event horizon begins to freeze the external perception even as the internal perception seems to be normal. Don’t forget the broadeening of the physical space from the external view which will ultimately smear the dimension across the horizon even as the longitudinal axis is being stretched.

[LibWhacker]

I’d prefer to hit that firewall myself, then be continually stretched and spaghettified.

Yes, me too! Spaghettification makes being drawn and quartered sound like fun.

[FroggyTheGremlim]

WhiskeyX - are you a relativity physicist?

[mosaicwolf]

The illusion of the physical universe is no longer projected by the ego and simply disappears.

[WhiskeyX]

The answer to that question could be uncertain in a random sort of a way.

[dr_lew]

The extreme tidal effects are not specifically associated with the event horizon. The equation I derived was a classical rule of thumb for the tidal stretching on a scale of "d" in terms of "g" at a distance "r" from an object of 1 Earth Mass:

a = g R²d / r³ , using R for the radius of earth

This is the "tidal force" between two objects at distance d along a radius from the central mass. For a = g we require r = (R²d)^1/3 or

r = (d/R)^1/3 R

Suppose we deem a tidal force field of 1 g/cm to be utterly disruptive of the human body, which it seems it surely would be. Then

(d/R)^1/3 R = ( 6.4e8 )^-1/3 R = R/861 = 7.4 km

But the Schwarzschild radius of earth is about 1 cm, so there could be no question of any kind of familiar object even approaching the event horizon there.

[dr_lew]

I ain't none of that, but I'm loaded for bear!

[FroggyTheGremlim]

Two copies of Misner, Thorne & Wheeler?

You need two copies?