Black Hole Swallowing a Star

[Atheist-Lite]

You can return to your bomb-bay now?

[GrahamH]

The energy burst is still visible by telescope more than two-and-a-half months later, the researchers report in the journal Science.

Actually, 4 billion years, two and a half months later!

Good point!

Since the black holes produce immense gravitational fields, and the field slows time / stretched distance, how long is our two and a half months for the star?
Could we be seeing two years of Gamma-Ray emissions from the star compressed into 2.5 months of remote observation? Does that make the event look brighter?

Are there any physicists in the house?

[GrahamH]

Dark Star

[Xamonas Chegwé]

At the event horizon, time stops completely. Beyond that, nobody, not even Stephen Hawking, knows!

[GrahamH]

At the event horizon, time stops completely. Beyond that, nobody, not even Stephen Hawking, knows!

I don't think time stops at the event horizon. It is the boundary within which everything, including photons, all fall in. Escape velocity > C. I think that relativistic physics still applies inside the E.H.

[devogue]

Saw the thread title and thought Hugh Grant was up to his old tricks again.

[Xamonas Chegwé]

At the event horizon, time stops completely. Beyond that, nobody, not even Stephen Hawking, knows!

I don't think time stops at the event horizon. It is the boundary within which everything, including photons, all fall in. Escape velocity > C. I think that relativistic physics still applies inside the E.H.

The closer you approach the EH, the slower time becomes (from the POV of anyone observing you, of course, you wouldn't notice it changing at all.) At the EH, an observer would see you stop completely. What you would see is anyone's guess! The closer you got, the faster things away from the black hole would move - you would see galaxies spinning and colliding in real time. Once you hit the EH, you would observe things moving infinitely fast - well, no, you wouldn't, not really - you'd actually be sucked into the black hole and that would probably not be a good thing!

All of the maths of GR break down at the EH of a black hole - beyond it things are unknowable using any tools we currently possess. QM doesn't offer any real solutions either. Like I said, nobody knows!

[Atheist-Lite]

The Second Coming
by WB Yeats

TURNING and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere
The ceremony of innocence is drowned;
The best lack all conviction, while the worst
Are full of passionate intensity.

Surely some revelation is at hand;
Surely the Second Coming is at hand.
The Second Coming! Hardly are those words out
When a vast image out of Spiritus Mundi
Troubles my sight: somewhere in sands of the desert
A shape with lion body and the head of a man,
A gaze blank and pitiless as the sun,
Is moving its slow thighs, while all about it
Reel shadows of the indignant desert birds.
The darkness drops again; but now I know
That twenty centuries of stony sleep
Were vexed to nightmare by a rocking cradle,
And what rough beast, its hour come round at last,
Slouches towards Bethlehem to be born?

http://www.eldritchdark.com/writings/sh ... f-the-dust

A singularity is the abode of the impossible.

[DRSB]

The Second Coming
by WB Yeats

TURNING and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere
The ceremony of innocence is drowned;
The best lack all conviction, while the worst
Are full of passionate intensity.

Surely some revelation is at hand;
Surely the Second Coming is at hand.
The Second Coming! Hardly are those words out
When a vast image out of Spiritus Mundi
Troubles my sight: somewhere in sands of the desert
A shape with lion body and the head of a man,
A gaze blank and pitiless as the sun,
Is moving its slow thighs, while all about it
Reel shadows of the indignant desert birds.
The darkness drops again; but now I know
That twenty centuries of stony sleep
Were vexed to nightmare by a rocking cradle,
And what rough beast, its hour come round at last,
Slouches towards Bethlehem to be born?

http://www.eldritchdark.com/writings/sh ... f-the-dust

A singularity is the abode of the impossible.

This is about the weirdo Alistair Crowley.

[Atheist-Lite]

The Second Coming
by WB Yeats

TURNING and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere
The ceremony of innocence is drowned;
The best lack all conviction, while the worst
Are full of passionate intensity.

Surely some revelation is at hand;
Surely the Second Coming is at hand.
The Second Coming! Hardly are those words out
When a vast image out of Spiritus Mundi
Troubles my sight: somewhere in sands of the desert
A shape with lion body and the head of a man,
A gaze blank and pitiless as the sun,
Is moving its slow thighs, while all about it
Reel shadows of the indignant desert birds.
The darkness drops again; but now I know
That twenty centuries of stony sleep
Were vexed to nightmare by a rocking cradle,
And what rough beast, its hour come round at last,
Slouches towards Bethlehem to be born?

http://www.eldritchdark.com/writings/sh ... f-the-dust

A singularity is the abode of the impossible.

This is about the weirdo Alistair Crowley.

Black holes are weirder?

[GrahamH]

At the event horizon, time stops completely. Beyond that, nobody, not even Stephen Hawking, knows!

I don't think time stops at the event horizon. It is the boundary within which everything, including photons, all fall in. Escape velocity > C. I think that relativistic physics still applies inside the E.H.

The closer you approach the EH, the slower time becomes (from the POV of anyone observing you, of course, you wouldn't notice it changing at all.) At the EH, an observer would see you stop completely. What you would see is anyone's guess! The closer you got, the faster things away from the black hole would move - you would see galaxies spinning and colliding in real time. Once you hit the EH, you would observe things moving infinitely fast - well, no, you wouldn't, not really - you'd actually be sucked into the black hole and that would probably not be a good thing!

All of the maths of GR break down at the EH of a black hole - beyond it things are unknowable using any tools we currently possess. QM doesn't offer any real solutions either. Like I said, nobody knows!

Maybe, but I'm not sure about that.
Wikipedia says:

any object approaching the horizon from the observer's side appears to slow down and never quite pass through the horizon, with its image becoming more and more redshifted as time elapses. The traveling object, however, experiences no strange effects and does, in fact, pass through the horizon in a finite amount of proper time.

So an object is seen to slow and fade to black.

Time and relativity seem normal to any observer inside the event horizon, and they never observe their own arrival at the EH.

An observer crossing a black hole event horizon can calculate the moment they've crossed it, but will not actually see or feel anything special happen at that moment. In terms of visual appearance, observers who fall into the hole perceive the black region constituting the horizon as lying at some apparent distance below them, and never experience crossing this visual horizon.[7] Other objects that had entered the horizon along the same radial path but at an earlier time would appear below the observer but still above the visual position of the horizon, and if they had fallen in recently enough the observer could exchange messages with them before either one was destroyed by the gravitational singularity.[8] Increasing tidal forces (and eventual impact with the hole's singularity) are the only locally noticeable effects.

Where GR really breaks down is in a gravitational singularity, which is not at the EH. GR doesn't describe some phenomena thought to be associated with the EH, such as Hawking Radiation.

On my original point of appearing brighter, I think I have that backward. Time Dilation would result in fewer photons observed per unit time. The light output would reduce and red-shift to lower energy producing a fade to black at the EH.

[laklak]

huh huh huh huh
he said black hole
huh huh huh huh huh

[electricwhiteboy]

The Second Coming
by WB Yeats

TURNING and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere
The ceremony of innocence is drowned;
The best lack all conviction, while the worst
Are full of passionate intensity.

Surely some revelation is at hand;
Surely the Second Coming is at hand.
The Second Coming! Hardly are those words out
When a vast image out of Spiritus Mundi
Troubles my sight: somewhere in sands of the desert
A shape with lion body and the head of a man,
A gaze blank and pitiless as the sun,
Is moving its slow thighs, while all about it
Reel shadows of the indignant desert birds.
The darkness drops again; but now I know
That twenty centuries of stony sleep
Were vexed to nightmare by a rocking cradle,
And what rough beast, its hour come round at last,
Slouches towards Bethlehem to be born?

http://www.eldritchdark.com/writings/sh ... f-the-dust

A singularity is the abode of the impossible.

This is about the weirdo Alistair Crowley.

I thought it was about the First World War. Yes the poem is influenced by occult thinking, but not Crowley's ideas. Crowley and Yeats were both in a magic society called the Golden Dawn, but Yeats prevented Crowley taking over the London lodge by calling the police to get him kicked out. It's not impossible that Yeats bore a grudge for 20 years before writing The Second Coming, but it's not a theory that I've heard.

[mistermack]

The Second Coming
by WB Yeats

TURNING and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere
The ceremony of innocence is drowned;
The best lack all conviction, while the worst
Are full of passionate intensity.

Surely some revelation is at hand;
Surely the Second Coming is at hand.
The Second Coming! Hardly are those words out
When a vast image out of Spiritus Mundi
Troubles my sight: somewhere in sands of the desert
A shape with lion body and the head of a man,
A gaze blank and pitiless as the sun,
Is moving its slow thighs, while all about it
Reel shadows of the indignant desert birds.
The darkness drops again; but now I know
That twenty centuries of stony sleep
Were vexed to nightmare by a rocking cradle,
And what rough beast, its hour come round at last,
Slouches towards Bethlehem to be born?

That's shite. He was obviously pissed, and it doesn't even rhyme.

[Berthold]

Traditional gamma ray bursts involve a deluge of high-energy photons bursting through the air.

Through the air? Really? Whatever happened to science reporting?

Well, eventually (for a surface-based human observer) they do.