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rickman
Guest

Tue Aug 16, 2016 10:51 pm   



On 8/16/2016 12:16 PM, Cursitor Doom wrote:
Quote:
On Tue, 16 Aug 2016 01:04:28 -0400, rickman wrote:

While falling and on reaching the center I believe the theoretically
liquid core would fall into the black hole. However, the energy
released by falling into the black hole would create pressure that
limits the rate of matter entering the black hole. I have no idea how
fast or slow this would be. The earth might be stable like this for
many, many years as the earth's core falls into the black hole while
being repelled by the energy released. Or the entire earth might
collapse into the black hole as fast as it can fall.

It's called a "strangelet" by those who've already considered this
possibility and if your analysis of the damped oscillation is correct,
then it's hard to see how we wouldn't be instantly (or more or less
instantly) destroyed. Fortunately the experts reckon they can create
strangelets with no adverse consequences. Smile


I don't understand your thinking. How is it definite that we would be
instantly destroyed? The gravitational attraction of the black hole is
only as strong as the matter inside it. Initially that would be very
little. As some have pointed out, it would most likely be far too small
to even interact with other matter in any short time and would likely
evaporate before it does.

--

Rick C

rickman
Guest

Tue Aug 16, 2016 11:56 pm   



On 8/16/2016 1:42 PM, George Herold wrote:
Quote:
On Tuesday, August 16, 2016 at 12:47:18 PM UTC-4, rickman wrote:
On 8/16/2016 12:30 PM, George Herold wrote:
On Tuesday, August 16, 2016 at 12:20:24 PM UTC-4, Tim Wescott wrote:
On Tue, 16 Aug 2016 01:23:34 -0400, bitrex wrote:

On 08/16/2016 01:04 AM, rickman wrote:
I was explaining black holes to a friend who asked about the LHC and
thought about what might happen if a tiny black hole were created.

I believe matter falling into a microscopic black hole would still
enter it in a similar manner to large black holes elsewhere in the
universe by orbiting the tiny black hole while being accelerated
causing energy to be emitted before crossing the event horizon.

A microscopic black hole, if such a thing could exist, would radiate
itself away via Hawking radiation before it had much of a chance to do
anything.


https://en.wikipedia.org/wiki/
Micro_black_hole#Stability_of_a_micro_black_hole

If such a thing as Hawking radiation exists.
IIRC Hawking radiation mostly follows from thermo-dynamics.
It's like black body radiation... Black holes have some temperature.
(Finding the temperature of a black hole is the hard part... :^)

I'm not sure that is a valid way to look at it. Everything that makes
up a black hole is on the other side of the event horizon. It may well
have a temperature, but we'll never feel any effect from it as nothing
can cross back through the event horizon. In a sense, the event horizon
of a black hole is an infinite heat sink at 0 °K. There may be
radiation from the space around the black hole, but nothing from the
black hole itself.

--

Rick C

Ahh, Rick I understand you are a smart guy. There are plenty of other smart guys
out there. I think the best (clearest) explanation I've seen/ read
(and it's been a while) was in a set of video lectures by Leonard Susskind.
Googling he's got a bunch... I don't recall which ones. Advanced stat. mech.
or maybe QM.

Black holes have a temperature. That's pretty cool. (NPI)
Here's wiki...(I only looked at the first few paragraphs.)
https://en.wikipedia.org/wiki/Hawking_radiation


Trouble is all of this is speculation and none is proven. I like a nice
mechanical explanation. Saying matter leaves a black hole by it
swallowing matter is not a very good argument. That's what Hawking
Radiation says.

--

Rick C

nuny@bid.nes
Guest

Wed Aug 17, 2016 12:09 am   



On Tuesday, August 16, 2016 at 1:56:39 AM UTC-7, David Brown wrote:
Quote:
On 16/08/16 07:04, rickman wrote:
I was explaining black holes to a friend who asked about the LHC and
thought about what might happen if a tiny black hole were created.

I believe matter falling into a microscopic black hole would still enter
it in a similar manner to large black holes elsewhere in the universe by
orbiting the tiny black hole while being accelerated causing energy to
be emitted before crossing the event horizon.


The key point about a tiny black hole created by the LHC is that it
would be /tiny/. Really, really, /really/ tiny. So small that even
bacteria would need a bacteria microscope to see it, as one of my kids
used to say.

The collisions in the LHC are at 13 TeV. That's about 14 K atomic
masses - the weight of 1000 nitrogen atoms. So even assuming the entire
collision energy goes into making a black hole, it is not a very big
one. It is 2.3e-23 kg, with an event horizon radius of about 3.4e-50 m.
For comparison, a proton is about 0.9e-15 m in radius, and the Planck
length is 1.6 e-35 m.

So if and when a hydrogen nucleus, a proton, touches this black hole,
the acceleration due to gravity will be G.m/r², or 0.002 m/s². At room
temperature, atomic vibrations will be moving the proton in the region
of 10e-11 m at about 10e13 Hz, with RMS speeds of about 2200 m/s.

These numbers are all simplistic, because they are based on a "billiard
balls" model of the particles. But I think the numbers speak for
themselves - the black hole would be so tiny, with such a low mass, that
it would have totally negligible influence on anything around it.


Since protons and neutrons are composite particles a MBH *might* snag a quark out of a nucleon, but that would leave a color-charged diquark particle as well as giving the MBH naked color, which Isn't Allowed.

Most likely result is that the color force would immediately pull anti-colored quarks out of the vacuum; one to neutralize the diquark, and the other would fall into the MBH neutralizing its color.

But as you say, this would be rare indeed whether or not the MBH evaporates (which it would, rapidly).

OTOH it could easily eat point particles like electrons but would also rapidly build up charge and stop eating them due to Coulomb repulsion.

Photons? Sure, but MBHs are HOT and radiate very very brightly; we're talking petawatts bright with a blackbody spectrum that peaks in the really short gammas.

Quote:
It would simply pass through matter (the earth included) without affecting
it measurably, in the same way that neutrinos do, continuing in a path
determined by its initial direction and speed when it was created.


That's really the bottom line. When it finishes evaporating things will be locally somewhat exciting, but a mere blip on geological energy scales.


Mark L. Fergerson

Tim Wescott
Guest

Wed Aug 17, 2016 12:37 am   



On Tue, 16 Aug 2016 09:30:13 -0700, George Herold wrote:

Quote:
On Tuesday, August 16, 2016 at 12:20:24 PM UTC-4, Tim Wescott wrote:
On Tue, 16 Aug 2016 01:23:34 -0400, bitrex wrote:

On 08/16/2016 01:04 AM, rickman wrote:
I was explaining black holes to a friend who asked about the LHC and
thought about what might happen if a tiny black hole were created.

I believe matter falling into a microscopic black hole would still
enter it in a similar manner to large black holes elsewhere in the
universe by orbiting the tiny black hole while being accelerated
causing energy to be emitted before crossing the event horizon.

A microscopic black hole, if such a thing could exist, would radiate
itself away via Hawking radiation before it had much of a chance to
do anything.


https://en.wikipedia.org/wiki/
Micro_black_hole#Stability_of_a_micro_black_hole

If such a thing as Hawking radiation exists.
IIRC Hawking radiation mostly follows from thermo-dynamics.
It's like black body radiation... Black holes have some temperature.
(Finding the temperature of a black hole is the hard part... :^)


Read Hawking's "A Brief History of Time". Computing Hawking radiation
from the amount of curvature of space and computing it from the ratio of
entropy to total surface area gives the same answers. At the time this
was a fall-on-the-floor astonishing result, and one that gave a lot of
credence to the result.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I'm looking for work -- see my website!

Tim Wescott
Guest

Wed Aug 17, 2016 12:39 am   



On Tue, 16 Aug 2016 12:50:57 -0400, bitrex wrote:

Quote:
On 08/16/2016 12:20 PM, Tim Wescott wrote:
On Tue, 16 Aug 2016 01:23:34 -0400, bitrex wrote:

On 08/16/2016 01:04 AM, rickman wrote:
I was explaining black holes to a friend who asked about the LHC and
thought about what might happen if a tiny black hole were created.

I believe matter falling into a microscopic black hole would still
enter it in a similar manner to large black holes elsewhere in the
universe by orbiting the tiny black hole while being accelerated
causing energy to be emitted before crossing the event horizon.

A microscopic black hole, if such a thing could exist, would radiate
itself away via Hawking radiation before it had much of a chance to do
anything.


https://en.wikipedia.org/wiki/
Micro_black_hole#Stability_of_a_micro_black_hole

If such a thing as Hawking radiation exists.

It kind of has to, or else what we think we know about quantum field
theory must be pretty much wrong

The main question is not whether Hawking radiation exists, but what
happens to the information.

https://en.wikipedia.org/wiki/Black_hole_information_paradox


Well, true, and it probably does, but it hasn't been observed yet.

Quantum field theory doesn't predict either dark energy or dark matter,
yet astronomical measurements say they must exist. So quantum field
theory is kind of behind the 8-ball right now on explaining how the
universe works.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I'm looking for work -- see my website!

Phil Hobbs
Guest

Wed Aug 17, 2016 12:39 am   



On 08/16/2016 12:47 PM, rickman wrote:
Quote:
On 8/16/2016 12:30 PM, George Herold wrote:
On Tuesday, August 16, 2016 at 12:20:24 PM UTC-4, Tim Wescott wrote:
On Tue, 16 Aug 2016 01:23:34 -0400, bitrex wrote:

On 08/16/2016 01:04 AM, rickman wrote:
I was explaining black holes to a friend who asked about the LHC and
thought about what might happen if a tiny black hole were created.

I believe matter falling into a microscopic black hole would still
enter it in a similar manner to large black holes elsewhere in the
universe by orbiting the tiny black hole while being accelerated
causing energy to be emitted before crossing the event horizon.

A microscopic black hole, if such a thing could exist, would radiate
itself away via Hawking radiation before it had much of a chance to do
anything.


https://en.wikipedia.org/wiki/
Micro_black_hole#Stability_of_a_micro_black_hole

If such a thing as Hawking radiation exists.
IIRC Hawking radiation mostly follows from thermo-dynamics.
It's like black body radiation... Black holes have some temperature.
(Finding the temperature of a black hole is the hard part... :^)

I'm not sure that is a valid way to look at it. Everything that makes
up a black hole is on the other side of the event horizon. It may well
have a temperature, but we'll never feel any effect from it as nothing
can cross back through the event horizon. In a sense, the event horizon
of a black hole is an infinite heat sink at 0 °K. There may be
radiation from the space around the black hole, but nothing from the
black hole itself.

Hawking radiation is caused by half of a virtual particle-antiparticle
pair falling into the event horizon and the other half escaping.

CHeers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

George Herold
Guest

Wed Aug 17, 2016 1:02 am   



On Tuesday, August 16, 2016 at 5:32:17 PM UTC-4, rickman wrote:
Quote:
On 8/16/2016 5:17 PM, Dave Platt wrote:
In article <novtns$hg0$1_at_dont-email.me>, rickman <gnuarm_at_gmail.com> wrote:

Hawking radiation is caused by half of a virtual particle-antiparticle
pair falling into the event horizon and the other half escaping.

Think about that. Matter falls into a black hole which leaves the black
hole with less matter?

As I understand it (layman's explanation): each virtual
particle/antiparticle pair which appears, draws the energy of its
creation from the energy of the strongly-curved space-time in the
vicinity of the black hole. The same is true for any virtual-
particle-pair creation event... it "borrow" energy from the vacuum.

If the two virtual particles recombine, the energy is returned to
spacetime. This is what happens in the case of the vast majority of
such particle events, especially in flat or near-flat spacetime
regions.

If, on the other hand, one of the two virtual particles escapes (and
the other falls into the black hole), half of the "borrowed" energy
escapes. The total mass-energy in the region drops by that amount.

Don't ask me to try to lay out the math for this... I don't pretend to
understand the equations :-)

I'm not asking for math, I'm looking for an understanding. If something
can be extracted from the black hole by any mechanism, there would seem
to be a fundamental conflict with the idea that the black hole is
inexcapable.

I totally don't understand the idea of there being energy inherent in
the curvature of space-time.

I've also never understood the details of spontaneous generation of
particle pairs from the vacuum. Even if they recombine, they create a
pair of photons. What happens to the photons?

--

Rick C


Sit down and wathc the video I posted.
Smart guy talking about the "physics" of black
holes. You have to do the math!
To me it is a lot of fun.
(I watched it again...
some smart questions from the class too.)
The sun is a good analog for a black hole,
I missed that the first time.

He doesn't talk about the mechanism of exchange.
(I've said this before, but you have this
supieriority(sp) thing, which is kinda ugly.)
George H.

George Herold
Guest

Wed Aug 17, 2016 1:27 am   



On Tuesday, August 16, 2016 at 6:37:58 PM UTC-4, Tim Williams wrote:
Quote:
"George Herold" <gherold_at_teachspin.com> wrote in message
news:e11e60a2-4673-47a0-ab83-ff31865a8988_at_googlegroups.com...
IIRC Hawking radiation mostly follows from thermo-dynamics.
It's like black body radiation... Black holes have some temperature.
(Finding the temperature of a black hole is the hard part... :^)

Right, it's the kind of "so obviously true" thing, that thermodynamics is so
good at. The mechanism doesn't matter: the temperature will be there.

The emissivity of that temperature reservoir might not be very good (like,
consider the tiny and poorly coupled heat capacity of nuclear spins in most
matter), or there might be secondary effects that don't invalidate the
thermo but nonetheless do weird things (like if the death throes of a micro
BH are quantized into extremely high energy emission states, to the extent
that there's a stable ground state instead of complete evaporation).

As for the mechanism, you can also think of it as tunneling.

Consider: nothing inside the BH event horizon is actually "inside", to any
significant meaning to an outside observer.

As matter falls in, it appears to slow down. Eventually, it appears to be
just at the event horizon -- at the same point it has red-shifted to
infinity.

So, realize: to an outside observer, /the entire black hole is at its
surface/. It's a shell mass.

Gauss tells us that gravity doesn't care, so there's nothing at all strange
about this idea. We have the same outside observations, regarding the
region's mass, charge and spin.

But it's all at the surface, so it really shouldn't be surprising that:
- The entropy is proportional to area (that's where all the "stuff" is)
- The entropy is maximal (because a maximal amount of "stuff" is packed onto
the surface)
- Tunneling can carry contents from the shell to the outside, with a
probability determined by steepness of the potential at the surface, not by,
say, distance from center.

NB: I forget if the actual mechanics of Hawking radiation have different
statistics. I've heard of tunneling expressed as virtual pairs doing the
same thing, and it's been long enough since school that I haven't worked
these problems myself...

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com


Tim, Yeah I think all that is right.
If you've got an hour to kill and the BW
the Susskind video I posted says all of that.
(with order of magnitude math/physics equations.)
The sun is a good analog for a black hole.
(I know I'm repeating myself. :^)

As far as the mechanism, (which only realy matters
if you want to try and measure it.)
I don't see tunneling as right...
it's more like boiling water off a surface*.
The BH has some energy (temperature) and can impart
that to 1/2 of a virtual particle pair at the
surface... which then has to "get out" of the
gravity well... not all have enough energy.

George H.
*I think I stole that from Susskind.

rickman
Guest

Wed Aug 17, 2016 2:40 am   



On 8/16/2016 2:39 PM, Phil Hobbs wrote:
Quote:
On 08/16/2016 12:47 PM, rickman wrote:
On 8/16/2016 12:30 PM, George Herold wrote:
On Tuesday, August 16, 2016 at 12:20:24 PM UTC-4, Tim Wescott wrote:
On Tue, 16 Aug 2016 01:23:34 -0400, bitrex wrote:

On 08/16/2016 01:04 AM, rickman wrote:
I was explaining black holes to a friend who asked about the LHC and
thought about what might happen if a tiny black hole were created.

I believe matter falling into a microscopic black hole would still
enter it in a similar manner to large black holes elsewhere in the
universe by orbiting the tiny black hole while being accelerated
causing energy to be emitted before crossing the event horizon.

A microscopic black hole, if such a thing could exist, would radiate
itself away via Hawking radiation before it had much of a chance to do
anything.


https://en.wikipedia.org/wiki/
Micro_black_hole#Stability_of_a_micro_black_hole

If such a thing as Hawking radiation exists.
IIRC Hawking radiation mostly follows from thermo-dynamics.
It's like black body radiation... Black holes have some temperature.
(Finding the temperature of a black hole is the hard part... :^)

I'm not sure that is a valid way to look at it. Everything that makes
up a black hole is on the other side of the event horizon. It may well
have a temperature, but we'll never feel any effect from it as nothing
can cross back through the event horizon. In a sense, the event horizon
of a black hole is an infinite heat sink at 0 °K. There may be
radiation from the space around the black hole, but nothing from the
black hole itself.

Hawking radiation is caused by half of a virtual particle-antiparticle
pair falling into the event horizon and the other half escaping.


Think about that. Matter falls into a black hole which leaves the black
hole with less matter?

--

Rick C

Dave Platt
Guest

Wed Aug 17, 2016 3:17 am   



In article <novtns$hg0$1_at_dont-email.me>, rickman <gnuarm_at_gmail.com> wrote:

Quote:
Hawking radiation is caused by half of a virtual particle-antiparticle
pair falling into the event horizon and the other half escaping.

Think about that. Matter falls into a black hole which leaves the black
hole with less matter?


As I understand it (layman's explanation): each virtual
particle/antiparticle pair which appears, draws the energy of its
creation from the energy of the strongly-curved space-time in the
vicinity of the black hole. The same is true for any virtual-
particle-pair creation event... it "borrow" energy from the vacuum.

If the two virtual particles recombine, the energy is returned to
spacetime. This is what happens in the case of the vast majority of
such particle events, especially in flat or near-flat spacetime
regions.

If, on the other hand, one of the two virtual particles escapes (and
the other falls into the black hole), half of the "borrowed" energy
escapes. The total mass-energy in the region drops by that amount.

Don't ask me to try to lay out the math for this... I don't pretend to
understand the equations Smile

Phil Hobbs
Guest

Wed Aug 17, 2016 3:19 am   



On 08/16/2016 04:40 PM, rickman wrote:
Quote:
On 8/16/2016 2:39 PM, Phil Hobbs wrote:
On 08/16/2016 12:47 PM, rickman wrote:
On 8/16/2016 12:30 PM, George Herold wrote:
On Tuesday, August 16, 2016 at 12:20:24 PM UTC-4, Tim Wescott wrote:
On Tue, 16 Aug 2016 01:23:34 -0400, bitrex wrote:

On 08/16/2016 01:04 AM, rickman wrote:
I was explaining black holes to a friend who asked about the LHC and
thought about what might happen if a tiny black hole were created.

I believe matter falling into a microscopic black hole would still
enter it in a similar manner to large black holes elsewhere in the
universe by orbiting the tiny black hole while being accelerated
causing energy to be emitted before crossing the event horizon.

A microscopic black hole, if such a thing could exist, would radiate
itself away via Hawking radiation before it had much of a chance
to do
anything.


https://en.wikipedia.org/wiki/
Micro_black_hole#Stability_of_a_micro_black_hole

If such a thing as Hawking radiation exists.
IIRC Hawking radiation mostly follows from thermo-dynamics.
It's like black body radiation... Black holes have some temperature.
(Finding the temperature of a black hole is the hard part... :^)

I'm not sure that is a valid way to look at it. Everything that makes
up a black hole is on the other side of the event horizon. It may well
have a temperature, but we'll never feel any effect from it as nothing
can cross back through the event horizon. In a sense, the event horizon
of a black hole is an infinite heat sink at 0 °K. There may be
radiation from the space around the black hole, but nothing from the
black hole itself.

Hawking radiation is caused by half of a virtual particle-antiparticle
pair falling into the event horizon and the other half escaping.

Think about that. Matter falls into a black hole which leaves the black
hole with less matter?


No, the hole loses mass turning the virtual particle into a real one.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

rickman
Guest

Wed Aug 17, 2016 3:32 am   



On 8/16/2016 5:17 PM, Dave Platt wrote:
Quote:
In article <novtns$hg0$1_at_dont-email.me>, rickman <gnuarm_at_gmail.com> wrote:

Hawking radiation is caused by half of a virtual particle-antiparticle
pair falling into the event horizon and the other half escaping.

Think about that. Matter falls into a black hole which leaves the black
hole with less matter?

As I understand it (layman's explanation): each virtual
particle/antiparticle pair which appears, draws the energy of its
creation from the energy of the strongly-curved space-time in the
vicinity of the black hole. The same is true for any virtual-
particle-pair creation event... it "borrow" energy from the vacuum.

If the two virtual particles recombine, the energy is returned to
spacetime. This is what happens in the case of the vast majority of
such particle events, especially in flat or near-flat spacetime
regions.

If, on the other hand, one of the two virtual particles escapes (and
the other falls into the black hole), half of the "borrowed" energy
escapes. The total mass-energy in the region drops by that amount.

Don't ask me to try to lay out the math for this... I don't pretend to
understand the equations Smile


I'm not asking for math, I'm looking for an understanding. If something
can be extracted from the black hole by any mechanism, there would seem
to be a fundamental conflict with the idea that the black hole is
inexcapable.

I totally don't understand the idea of there being energy inherent in
the curvature of space-time.

I've also never understood the details of spontaneous generation of
particle pairs from the vacuum. Even if they recombine, they create a
pair of photons. What happens to the photons?

--

Rick C

rickman
Guest

Wed Aug 17, 2016 3:34 am   



On 8/16/2016 5:19 PM, Phil Hobbs wrote:
Quote:
On 08/16/2016 04:40 PM, rickman wrote:
On 8/16/2016 2:39 PM, Phil Hobbs wrote:
On 08/16/2016 12:47 PM, rickman wrote:
On 8/16/2016 12:30 PM, George Herold wrote:
On Tuesday, August 16, 2016 at 12:20:24 PM UTC-4, Tim Wescott wrote:
On Tue, 16 Aug 2016 01:23:34 -0400, bitrex wrote:

On 08/16/2016 01:04 AM, rickman wrote:
I was explaining black holes to a friend who asked about the LHC
and
thought about what might happen if a tiny black hole were created.

I believe matter falling into a microscopic black hole would still
enter it in a similar manner to large black holes elsewhere in the
universe by orbiting the tiny black hole while being accelerated
causing energy to be emitted before crossing the event horizon.

A microscopic black hole, if such a thing could exist, would radiate
itself away via Hawking radiation before it had much of a chance
to do
anything.


https://en.wikipedia.org/wiki/
Micro_black_hole#Stability_of_a_micro_black_hole

If such a thing as Hawking radiation exists.
IIRC Hawking radiation mostly follows from thermo-dynamics.
It's like black body radiation... Black holes have some temperature.
(Finding the temperature of a black hole is the hard part... :^)

I'm not sure that is a valid way to look at it. Everything that makes
up a black hole is on the other side of the event horizon. It may well
have a temperature, but we'll never feel any effect from it as nothing
can cross back through the event horizon. In a sense, the event
horizon
of a black hole is an infinite heat sink at 0 °K. There may be
radiation from the space around the black hole, but nothing from the
black hole itself.

Hawking radiation is caused by half of a virtual particle-antiparticle
pair falling into the event horizon and the other half escaping.

Think about that. Matter falls into a black hole which leaves the black
hole with less matter?


No, the hole loses mass turning the virtual particle into a real one.


So a "virtual" particle has negative mass? The black hole captures one
virtual particle and the other becomes real. What exactly is the
difference between a virtual particle and a real one?

This sounds a bit like tunneling. Matter leaves the black hole without
ever crossing the event horizon.

--

Rick C

Phil Hobbs
Guest

Wed Aug 17, 2016 3:44 am   



On 08/16/2016 05:34 PM, rickman wrote:
Quote:
On 8/16/2016 5:19 PM, Phil Hobbs wrote:
On 08/16/2016 04:40 PM, rickman wrote:
On 8/16/2016 2:39 PM, Phil Hobbs wrote:
On 08/16/2016 12:47 PM, rickman wrote:
On 8/16/2016 12:30 PM, George Herold wrote:
On Tuesday, August 16, 2016 at 12:20:24 PM UTC-4, Tim Wescott wrote:
On Tue, 16 Aug 2016 01:23:34 -0400, bitrex wrote:

On 08/16/2016 01:04 AM, rickman wrote:
I was explaining black holes to a friend who asked about the LHC
and
thought about what might happen if a tiny black hole were created.

I believe matter falling into a microscopic black hole would still
enter it in a similar manner to large black holes elsewhere in the
universe by orbiting the tiny black hole while being accelerated
causing energy to be emitted before crossing the event horizon.

A microscopic black hole, if such a thing could exist, would
radiate
itself away via Hawking radiation before it had much of a chance
to do
anything.


https://en.wikipedia.org/wiki/
Micro_black_hole#Stability_of_a_micro_black_hole

If such a thing as Hawking radiation exists.
IIRC Hawking radiation mostly follows from thermo-dynamics.
It's like black body radiation... Black holes have some temperature.
(Finding the temperature of a black hole is the hard part... :^)

I'm not sure that is a valid way to look at it. Everything that makes
up a black hole is on the other side of the event horizon. It may
well
have a temperature, but we'll never feel any effect from it as nothing
can cross back through the event horizon. In a sense, the event
horizon
of a black hole is an infinite heat sink at 0 °K. There may be
radiation from the space around the black hole, but nothing from the
black hole itself.

Hawking radiation is caused by half of a virtual particle-antiparticle
pair falling into the event horizon and the other half escaping.

Think about that. Matter falls into a black hole which leaves the black
hole with less matter?


No, the hole loses mass turning the virtual particle into a real one.

So a "virtual" particle has negative mass? The black hole captures one
virtual particle and the other becomes real. What exactly is the
difference between a virtual particle and a real one?

This sounds a bit like tunneling. Matter leaves the black hole without
ever crossing the event horizon.


It's a lot like tunnelling. For the rest, it's because quantum field
theory.

Cheers

Phil Hobbs



--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

Tim Williams
Guest

Wed Aug 17, 2016 4:37 am   



"George Herold" <gherold_at_teachspin.com> wrote in message
news:e11e60a2-4673-47a0-ab83-ff31865a8988_at_googlegroups.com...
Quote:
IIRC Hawking radiation mostly follows from thermo-dynamics.
It's like black body radiation... Black holes have some temperature.
(Finding the temperature of a black hole is the hard part... :^)


Right, it's the kind of "so obviously true" thing, that thermodynamics is so
good at. The mechanism doesn't matter: the temperature will be there.

The emissivity of that temperature reservoir might not be very good (like,
consider the tiny and poorly coupled heat capacity of nuclear spins in most
matter), or there might be secondary effects that don't invalidate the
thermo but nonetheless do weird things (like if the death throes of a micro
BH are quantized into extremely high energy emission states, to the extent
that there's a stable ground state instead of complete evaporation).

As for the mechanism, you can also think of it as tunneling.

Consider: nothing inside the BH event horizon is actually "inside", to any
significant meaning to an outside observer.

As matter falls in, it appears to slow down. Eventually, it appears to be
just at the event horizon -- at the same point it has red-shifted to
infinity.

So, realize: to an outside observer, /the entire black hole is at its
surface/. It's a shell mass.

Gauss tells us that gravity doesn't care, so there's nothing at all strange
about this idea. We have the same outside observations, regarding the
region's mass, charge and spin.

But it's all at the surface, so it really shouldn't be surprising that:
- The entropy is proportional to area (that's where all the "stuff" is)
- The entropy is maximal (because a maximal amount of "stuff" is packed onto
the surface)
- Tunneling can carry contents from the shell to the outside, with a
probability determined by steepness of the potential at the surface, not by,
say, distance from center.

NB: I forget if the actual mechanics of Hawking radiation have different
statistics. I've heard of tunneling expressed as virtual pairs doing the
same thing, and it's been long enough since school that I haven't worked
these problems myself...

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com

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