Starship Asterisk*

Stephen Hawking is this year's Reith Lecturer on the BBC.
(John Reith founded the BBC, and these lectures are an annual even, given by some prominent person, in his memory and that of the values that he set the BBC, "To inform, educate and entertain")

The first is here: http://www.bbc.co.uk/programmes/p03gl17j

I've just heard the start of the second lecture, in which Prof.Hawking says that a BH the mass of the Sun would be very dim in terms of Hawking radiation, but one the mass of a mountain would provide more radiated energy than the World today needs, which puts in to words what alter-ego described. He may go on to talk about the Firewall Paradox in the second lecture, so listen up!
John

neufer wrote:

Ron-Astro Pharmacist wrote:

Chris Peterson wrote: Zeno's paradox really doesn't work with black hole evaporation because when the hole gets half as small it's radius decreases at a rate four times as fast (i.e., eight times as fast relative to it's size). Radioactive material is only half as radioactive after a half life and would, in fact, (Zeno-like) last forever if not for the fact that there are only a discreet number of atoms.

That argument seems right Art but it's even "less than halfway decent".

If Zeno shot an arrow at the black hole and it hit the radius. Then for every half the distance it traveled the radius would diminish eight times as fast. Wouldn't the arrow, exponentially, get infinitely far from the radius?

Hawking doesn't! Talk about the Firewall, that is.

Her's his second: http://www.bbc.co.uk/programmes/b06qjzv8
Cleverly illustrated by blackboard sketches by an artist!

John

Ron-Astro Pharmacist wrote:

neufer wrote:
Zeno's paradox really doesn't work with black hole evaporation because when the hole gets half as small it's radius decreases at a rate four times as fast (i.e., eight times as fast relative to it's size). Radioactive material is only half as radioactive after a half life and would, in fact, (Zeno-like) last forever if not for the fact that there are only a discreet number of atoms.

That argument seems right Art but it's even "less than halfway decent".

• "Less than halfway descent"

Ron-Astro Pharmacist wrote:
If Zeno shot an arrow at the black hole... Then for every half the distance it traveled the radius would diminish eight times as fast. Wouldn't the arrow, exponentially, get infinitely far from the radius?

If Zeno shot an arrow at a typical (i.e., non mini) black hole the arrow would at first speed up to near the light speed and then (as time slows down) appear to freeze just before the event horizon.

If Zeno shot an arrow at an evaporating mini-black hole the arrow would at first speed up and then pass harmlessly through the spot where the mini-black hole used to be (unless it was destroyed by Hawking Radiation).

neufer wrote:

Ron-Astro Pharmacist wrote:

neufer wrote:
Zeno's paradox really doesn't work with black hole evaporation because when the hole gets half as small it's radius decreases at a rate four times as fast (i.e., eight times as fast relative to it's size). Radioactive material is only half as radioactive after a half life and would, in fact, (Zeno-like) last forever if not for the fact that there are only a discreet number of atoms.

That argument seems right Art but it's

even

... "less than halfway decent".

• "Less than halfway descent"

Ron-Astro Pharmacist wrote:

Referring to frame three

...but not very well.