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rickman
Guest

Mon Jan 09, 2017 4:20 pm   



On 1/9/2017 12:27 AM, bill.sloman_at_ieee.org wrote:
Quote:
On Monday, January 9, 2017 at 3:06:11 PM UTC+11, rickman wrote:
On 1/8/2017 8:53 PM, bill.sloman_at_ieee.org wrote:
On Monday, January 9, 2017 at 9:07:33 AM UTC+11, rickman wrote:
On 1/8/2017 11:01 AM, Albert van der Horst wrote:
In article <np54eh$dpd$2_at_dont-email.me>, rickman <gnuarm_at_gmail.com> wrote:
On 8/18/2016 4:55 AM, David Brown wrote:
On 16/08/16 19:56, rickman wrote:
On 8/16/2016 1:42 PM, George Herold wrote:
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.

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.

That is one way of understanding it.

Unfortunately, general relativity is not amenable to nice mechanical
explanations. And quantum effects are even less amenable to such
explanations. And with black holes, you've got the most extreme
situations for the relativity effects /and/ the most extreme quantum
effects. You are never going to get a nice, clear, intuitive "bouncing
ball bearings" picture here.

Fine, but quantum theory has been verified repeatedly. Hawking
radiation has not.

You can't do that to physics theories. The Hawking radiation fits into
and completes a picture we have of a universe. It predicts very faint
radiation of largish black holes that we can predict not to be observable
by the means we have available now.

And therefore it has *not* been verified. Simple enough, no?

Not exactly. The LIGO gravity wave detector has "seen" a couple of relatively small black holes in the process of merging to make a slightly bigger small black hole, so we do know that they exist. Their properties can be deduced from regular physics.

You mean what we *assume* are black holes... Regardless. Even if they
exist, that says nothing about Hawking radiation.

We don't "assume" black holes - we postulate them to explain facts that otherwise seem impossible to explain. Electrons are equally hypothetical.


There is little observational evidence about black holes that require
them to be black holes. Mostly it is the lack of other things like
radiation, but then the black holes are actually known by all the
indirect radiation. We have to postulate, as you say, because we have
yet to observe a black hole directly.

Regardless, it is Hawking radiation we were talking about.

> Hawking radiation is a necessary consequence of Dirac pair production and an event horizon.

Except that we don't fully understand black holes... so we may have this
wrong.

> The problem with modern physics is that it is a package deal - you get the counter-intuitive bits as part of the package. Reject them and you are back to flint axes.

It's not a question of what is intuitive, it is a matter of what is
proven. We fully expected the Higgs boson, but we looked for it to
prove it. We fully believed the theory of relativity, but we looked for
proof for a very long time and are still happy when we can find
something new that verifies it.


Quote:
I too like a nice mechanical explanation - but here you are going to
have to accept weird things if you want to understand. (Not that I am
claiming to understand this stuff.)

I don't have problems with weird things. It's not the weirdness that is
at issue. It's the lack of connection between the particle pair and the
black hole.

Huh? The particle pairs are everywhere. The black hole only makes them
visible, but not to the naked eye.

They would be visible to the naked eye, if the eye was close enough to black hole. No human eye could survive there, but the effect would be visible at a greater distance, for a sufficiently small black hole that was emitting Hawking radiation sufficiently rapidly.

Someday we will create black holes in the lab and may observe Hawking
radiation. My understanding is that the strength of the radiation would
be *inversely* proportional to the size of the black hole, so if we created
a very small one it would in essence explode immediately. I think we could
detect that.

Or something considerably larger, and sufficiently long-lived that we could move it off to safe distance before it came apart.



--

Rick C

Phil Hobbs
Guest

Mon Jan 09, 2017 11:07 pm   



On 01/08/2017 11:06 PM, rickman wrote:
Quote:
On 1/8/2017 8:53 PM, bill.sloman_at_ieee.org wrote:
On Monday, January 9, 2017 at 9:07:33 AM UTC+11, rickman wrote:
On 1/8/2017 11:01 AM, Albert van der Horst wrote:
In article <np54eh$dpd$2_at_dont-email.me>, rickman <gnuarm_at_gmail.com
wrote:
On 8/18/2016 4:55 AM, David Brown wrote:
On 16/08/16 19:56, rickman wrote:
On 8/16/2016 1:42 PM, George Herold wrote:
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.


Unfortunately, general relativity is not amenable to nice mechanical
explanations. And quantum effects are even less amenable to such
explanations. And with black holes, you've got the most extreme
situations for the relativity effects /and/ the most extreme quantum
effects. You are never going to get a nice, clear, intuitive
"bouncing
ball bearings" picture here.

Fine, but quantum theory has been verified repeatedly. Hawking
radiation has not.

You can't do that to physics theories. The Hawking radiation fits into
and completes a picture we have of a universe. It predicts very faint
radiation of largish black holes that we can predict not to be
observable
by the means we have available now.

And therefore it has *not* been verified. Simple enough, no?

Not exactly. The LIGO gravity wave detector has "seen" a couple of
relatively small black holes in the process of merging to make a
slightly bigger small black hole, so we do know that they exist. Their
properties can be deduced from regular physics.

You mean what we *assume* are black holes... Regardless. Even if they
exist, that says nothing about Hawking radiation.


I too like a nice mechanical explanation - but here you are going to
have to accept weird things if you want to understand. (Not that
I am
claiming to understand this stuff.)

I don't have problems with weird things. It's not the weirdness
that is
at issue. It's the lack of connection between the particle pair
and the
black hole.

Huh? The particle pairs are everywhere. The black hole only makes them
visible, but not to the naked eye.

They would be visible to the naked eye, if the eye was close enough to
black hole. No human eye could survive there, but the effect would be
visible at a greater distance, for a sufficiently small black hole
that was emitting Hawking radiation sufficiently rapidly.

Someday we will create black holes in the lab and may observe Hawking
radiation. My understanding is that the strength of the radiation would
be proportional to the size of the black hole, so if we created a very
small one it would in essence explode immediately. I think we could
detect that.


Man, I hope nobody is stupid enough to do that. A miscalculation could
literally destroy the planet.

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


Guest

Tue Jan 10, 2017 3:48 am   



On Tuesday, January 10, 2017 at 12:09:42 PM UTC+11, rickman wrote:
Quote:
On 1/9/2017 5:01 AM, bill.sloman_at_ieee.org wrote:
On Monday, January 9, 2017 at 8:20:45 PM UTC+11, rickman wrote:
On 1/9/2017 12:27 AM, bill.sloman_at_ieee.org wrote:
On Monday, January 9, 2017 at 3:06:11 PM UTC+11, rickman wrote:
On 1/8/2017 8:53 PM, bill.sloman_at_ieee.org wrote:
On Monday, January 9, 2017 at 9:07:33 AM UTC+11, rickman wrote:
On 1/8/2017 11:01 AM, Albert van der Horst wrote:
In article <np54eh$dpd$2_at_dont-email.me>, rickman <gnuarm_at_gmail.com> wrote:
On 8/18/2016 4:55 AM, David Brown wrote:
On 16/08/16 19:56, rickman wrote:
On 8/16/2016 1:42 PM, George Herold wrote:
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
and thought about what might happen if a tiny black hole were
LHC 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.

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.

That is one way of understanding it.

Unfortunately, general relativity is not amenable to nice mechanical
explanations. And quantum effects are even less amenable to such
explanations. And with black holes, you've got the most extreme
situations for the relativity effects /and/ the most extreme quantum
effects. You are never going to get a nice, clear, intuitive
"bouncing ball bearings" picture here.

Fine, but quantum theory has been verified repeatedly. Hawking
radiation has not.

You can't do that to physics theories. The Hawking radiation fits into
and completes a picture we have of a universe. It predicts very faint
radiation of largish black holes that we can predict not to be
observable by the means we have available now.

And therefore it has *not* been verified. Simple enough, no?

Not exactly. The LIGO gravity wave detector has "seen" a couple of relatively small black holes in the process of merging to make a slightly bigger small black hole, so we do know that they exist. Their properties can be deduced from regular physics.

You mean what we *assume* are black holes... Regardless. Even if they
exist, that says nothing about Hawking radiation.

We don't "assume" black holes - we postulate them to explain facts that otherwise seem impossible to explain. Electrons are equally hypothetical..

There is little observational evidence about black holes that require
them to be black holes. Mostly it is the lack of other things like
radiation, but then the black holes are actually known by all the
indirect radiation. We have to postulate, as you say, because we have
yet to observe a black hole directly.

http://hubblesite.org/reference_desk/faq/answer.php.id=64&cat=exotic

We can see the stars orbiting about a black hole - telling us its mass - and we can see them close enough to the black hole to know that the total mass in the volume available implies a black hole. That's as visible as a black hole is ever going to get.

Regardless, it is Hawking radiation we were talking about.

Hawking radiation is a necessary consequence of Dirac pair production and an event horizon.

Except that we don't fully understand black holes... so we may have this
wrong.

We understand them well enough to know that they are going to have an event horizon, which is all you need for Hawking radiation.

See, that's the problem. We have invented something we call Hawking
radiation and without ever making an observation to confirm the idea, we
are convinced it must happen.


If there wasn't any Hawking radiation, we'd have to reconstruct quite a lot of physics. We can be pretty confident that it exists. It took Hawking to realise that it had to exist, but it did turn out to be a rather useful insight.

Quote:
The problem with modern physics is that it is a package deal - you get the counter-intuitive bits as part of the package. Reject them and you are back to flint axes.

It's not a question of what is intuitive, it is a matter of what is
proven. We fully expected the Higgs boson, but we looked for it to
prove it.

Not the same problem. We fully expected a Higgs boson, but nobody knew exactly how heavy it was going to be.

Of course it's the same problem. The reason we looked for the Higgs
boson is because its existence has to do with theory that we are still
developing.


The bit of theory that said that there had to be a Higgs boson wasn't all that specific about how heavy it had to be.

Quote:
We fully believed the theory of relativity, but we looked for
proof for a very long time and are still happy when we can find
something new that verifies it.

We test the theory of relativity whenever we can, and are happy when it comes up trumps once again. We've got to the point where anything that replaces the theory of relativity has got to make the same predictions with remarkably high precision.

That's not the point.


That's exactly the point. Science doesn't accept any theory as proven - it's merely not yet falsified, if you take Popper seriously.

Quote:
Newtonian physics didn't explain the precession of the orbit of Mercury, and it was recognised as problem before Einstein came up with his explanation..

http://physics.ucr.edu/~wudka/Physics7/Notes_www/node98.html

Einstein's relativity still hasn't been reconciled with quantumn theory, but that's a different class of problem.

None of the above is relevant. The point is that it had to be verified
and has been many, many times. Hawking radiation, not so much.


For some value of "verified", which means "proved to be true". "Not yet falsified" is what science offers - verification is strictly for theologians and mathematicians, whose propositions exist only within their minds.


Quote:
I too like a nice mechanical explanation - but here you are going to
have to accept weird things if you want to understand. (Not that I
am claiming to understand this stuff.)

I don't have problems with weird things. It's not the weirdness that
is at issue. It's the lack of connection between the particle pair
and the black hole.

Huh? The particle pairs are everywhere. The black hole only makes them
visible, but not to the naked eye.

They would be visible to the naked eye, if the eye was close enough to black hole. No human eye could survive there, but the effect would be visible at a greater distance, for a sufficiently small black hole that was emitting Hawking radiation sufficiently rapidly.

Someday we will create black holes in the lab and may observe Hawking
radiation. My understanding is that the strength of the radiation would
be *inversely* proportional to the size of the black hole, so if we
created a very small one it would in essence explode immediately. I
think we could detect that.

Or something considerably larger, and sufficiently long-lived that we could move it off to safe distance before it came apart.

You are still looking for something that fits your intuitions, even if it doesn't feel that way to you.

Not sure who you are responding to here. It would appear to be yourself.


If you expect every posted line to be an immediate response to the line above it. In fact your problem - as spelled out at length in a series of responses that I'm unwilling to snip because they do make a more or coherent exposition of a somewhat incoherent objection - is that you find Hawking radiation counter-intuitive and get shirty when we point out that this isn't a useful observation.

--
Bill Sloman, Sydney


Guest

Tue Jan 10, 2017 3:55 am   



On Tuesday, January 10, 2017 at 12:11:14 PM UTC+11, rickman wrote:
Quote:
On 1/9/2017 11:07 AM, Phil Hobbs wrote:
On 01/08/2017 11:06 PM, rickman wrote:
On 1/8/2017 8:53 PM, bill.sloman_at_ieee.org wrote:
On Monday, January 9, 2017 at 9:07:33 AM UTC+11, rickman wrote:
On 1/8/2017 11:01 AM, Albert van der Horst wrote:
In article <np54eh$dpd$2_at_dont-email.me>, rickman <gnuarm_at_gmail.com
wrote:
On 8/18/2016 4:55 AM, David Brown wrote:
On 16/08/16 19:56, rickman wrote:
On 8/16/2016 1:42 PM, George Herold wrote:
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.


Unfortunately, general relativity is not amenable to nice mechanical
explanations. And quantum effects are even less amenable to such
explanations. And with black holes, you've got the most extreme
situations for the relativity effects /and/ the most extreme quantum
effects. You are never going to get a nice, clear, intuitive
"bouncing
ball bearings" picture here.

Fine, but quantum theory has been verified repeatedly. Hawking
radiation has not.

You can't do that to physics theories. The Hawking radiation fits into
and completes a picture we have of a universe. It predicts very faint
radiation of largish black holes that we can predict not to be
observable
by the means we have available now.

And therefore it has *not* been verified. Simple enough, no?

Not exactly. The LIGO gravity wave detector has "seen" a couple of
relatively small black holes in the process of merging to make a
slightly bigger small black hole, so we do know that they exist. Their
properties can be deduced from regular physics.

You mean what we *assume* are black holes... Regardless. Even if they
exist, that says nothing about Hawking radiation.


I too like a nice mechanical explanation - but here you are going to
have to accept weird things if you want to understand. (Not that
I am
claiming to understand this stuff.)

I don't have problems with weird things. It's not the weirdness
that is
at issue. It's the lack of connection between the particle pair
and the
black hole.

Huh? The particle pairs are everywhere. The black hole only makes them
visible, but not to the naked eye.

They would be visible to the naked eye, if the eye was close enough to
black hole. No human eye could survive there, but the effect would be
visible at a greater distance, for a sufficiently small black hole
that was emitting Hawking radiation sufficiently rapidly.

Someday we will create black holes in the lab and may observe Hawking
radiation. My understanding is that the strength of the radiation would
be proportional to the size of the black hole, so if we created a very
small one it would in essence explode immediately. I think we could
detect that.


Man, I hope nobody is stupid enough to do that. A miscalculation could
literally destroy the planet.

How is that?

BTW, I think you overvalue the planet.


Having a black hole eat the entire planet would be a bad outcome,

Quote:
We are headed for a planet that
won't sustain life in not so many centuries anyway.


We aren't. You've been listening to John Larkin again.

Anthropogenic global warming may take the planet into a state that's incompatible with modern industrial society, creating a human population crash, but - as even John Larkin points out - individual humans would do fine on a warmer world, though they have to change where they got their food and what they ate (which is a point that John Larkin tends to skate over).

Quote:
I'd like to see
some cool stuff before then.


Try to learn enough to let you appreciate what's actually cool - like Hawking radiation.

--
Bill Sloman, Sydney

rickman
Guest

Tue Jan 10, 2017 8:09 am   



On 1/9/2017 5:01 AM, bill.sloman_at_ieee.org wrote:
Quote:
On Monday, January 9, 2017 at 8:20:45 PM UTC+11, rickman wrote:
On 1/9/2017 12:27 AM, bill.sloman_at_ieee.org wrote:
On Monday, January 9, 2017 at 3:06:11 PM UTC+11, rickman wrote:
On 1/8/2017 8:53 PM, bill.sloman_at_ieee.org wrote:
On Monday, January 9, 2017 at 9:07:33 AM UTC+11, rickman wrote:
On 1/8/2017 11:01 AM, Albert van der Horst wrote:
In article <np54eh$dpd$2_at_dont-email.me>, rickman <gnuarm_at_gmail.com> wrote:
On 8/18/2016 4:55 AM, David Brown wrote:
On 16/08/16 19:56, rickman wrote:
On 8/16/2016 1:42 PM, George Herold wrote:
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
and thought about what might happen if a tiny black hole were
LHC 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.

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.

That is one way of understanding it.

Unfortunately, general relativity is not amenable to nice mechanical
explanations. And quantum effects are even less amenable to such
explanations. And with black holes, you've got the most extreme
situations for the relativity effects /and/ the most extreme quantum
effects. You are never going to get a nice, clear, intuitive
"bouncing ball bearings" picture here.

Fine, but quantum theory has been verified repeatedly. Hawking
radiation has not.

You can't do that to physics theories. The Hawking radiation fits into
and completes a picture we have of a universe. It predicts very faint
radiation of largish black holes that we can predict not to be
observable by the means we have available now.

And therefore it has *not* been verified. Simple enough, no?

Not exactly. The LIGO gravity wave detector has "seen" a couple of relatively small black holes in the process of merging to make a slightly bigger small black hole, so we do know that they exist. Their properties can be deduced from regular physics.

You mean what we *assume* are black holes... Regardless. Even if they
exist, that says nothing about Hawking radiation.

We don't "assume" black holes - we postulate them to explain facts that otherwise seem impossible to explain. Electrons are equally hypothetical.

There is little observational evidence about black holes that require
them to be black holes. Mostly it is the lack of other things like
radiation, but then the black holes are actually known by all the
indirect radiation. We have to postulate, as you say, because we have
yet to observe a black hole directly.

http://hubblesite.org/reference_desk/faq/answer.php.id=64&cat=exotic

We can see the stars orbiting about a black hole - telling us its mass - and we can see them close enough to the black hole to know that the total mass in the volume available implies a black hole. That's as visible as a black hole is ever going to get.

Regardless, it is Hawking radiation we were talking about.

Hawking radiation is a necessary consequence of Dirac pair production and an event horizon.

Except that we don't fully understand black holes... so we may have this
wrong.

We understand them well enough to know that they are going to have an event horizon, which is all you need for Hawking radiation.


See, that's the problem. We have invented something we call Hawking
radiation and without ever making an observation to confirm the idea, we
are convinced it must happen.


Quote:
The problem with modern physics is that it is a package deal - you get the counter-intuitive bits as part of the package. Reject them and you are back to flint axes.

It's not a question of what is intuitive, it is a matter of what is
proven. We fully expected the Higgs boson, but we looked for it to
prove it.

Not the same problem. We fully expected a Higgs boson, but nobody knew exactly how heavy it was going to be.


Of course it's the same problem. The reason we looked for the Higgs
boson is because its existence has to do with theory that we are still
developing.


Quote:
We fully believed the theory of relativity, but we looked for
proof for a very long time and are still happy when we can find
something new that verifies it.

We test the theory of relativity whenever we can, and are happy when it comes up trumps once again. We've got to the point where anything that replaces the theory of relativity has got to make the same predictions with remarkably high precision.


That's not the point.


Quote:
Newtonian physics didn't explain the precession of the orbit of Mercury, and it was recognised as problem before Einstein came up with his explanation..

http://physics.ucr.edu/~wudka/Physics7/Notes_www/node98.html

Einstein's relativity still hasn't been reconciled with quantumn theory, but that's a different class of problem.


None of the above is relevant. The point is that it had to be verified
and has been many, many times. Hawking radiation, not so much.


Quote:
I too like a nice mechanical explanation - but here you are going to
have to accept weird things if you want to understand. (Not that I am
claiming to understand this stuff.)

I don't have problems with weird things. It's not the weirdness that
is at issue. It's the lack of connection between the particle pair
and the black hole.

Huh? The particle pairs are everywhere. The black hole only makes them
visible, but not to the naked eye.

They would be visible to the naked eye, if the eye was close enough to black hole. No human eye could survive there, but the effect would be visible at a greater distance, for a sufficiently small black hole that was emitting Hawking radiation sufficiently rapidly.

Someday we will create black holes in the lab and may observe Hawking
radiation. My understanding is that the strength of the radiation would
be *inversely* proportional to the size of the black hole, so if we created
a very small one it would in essence explode immediately. I think we could
detect that.

Or something considerably larger, and sufficiently long-lived that we could move it off to safe distance before it came apart.

You are still looking for something that fits your intuitions, even if it doesn't feel that way to you.


Not sure who you are responding to here. It would appear to be yourself.

--

Rick C

rickman
Guest

Tue Jan 10, 2017 8:11 am   



On 1/9/2017 11:07 AM, Phil Hobbs wrote:
Quote:
On 01/08/2017 11:06 PM, rickman wrote:
On 1/8/2017 8:53 PM, bill.sloman_at_ieee.org wrote:
On Monday, January 9, 2017 at 9:07:33 AM UTC+11, rickman wrote:
On 1/8/2017 11:01 AM, Albert van der Horst wrote:
In article <np54eh$dpd$2_at_dont-email.me>, rickman <gnuarm_at_gmail.com
wrote:
On 8/18/2016 4:55 AM, David Brown wrote:
On 16/08/16 19:56, rickman wrote:
On 8/16/2016 1:42 PM, George Herold wrote:
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.


Unfortunately, general relativity is not amenable to nice mechanical
explanations. And quantum effects are even less amenable to such
explanations. And with black holes, you've got the most extreme
situations for the relativity effects /and/ the most extreme quantum
effects. You are never going to get a nice, clear, intuitive
"bouncing
ball bearings" picture here.

Fine, but quantum theory has been verified repeatedly. Hawking
radiation has not.

You can't do that to physics theories. The Hawking radiation fits into
and completes a picture we have of a universe. It predicts very faint
radiation of largish black holes that we can predict not to be
observable
by the means we have available now.

And therefore it has *not* been verified. Simple enough, no?

Not exactly. The LIGO gravity wave detector has "seen" a couple of
relatively small black holes in the process of merging to make a
slightly bigger small black hole, so we do know that they exist. Their
properties can be deduced from regular physics.

You mean what we *assume* are black holes... Regardless. Even if they
exist, that says nothing about Hawking radiation.


I too like a nice mechanical explanation - but here you are going to
have to accept weird things if you want to understand. (Not that
I am
claiming to understand this stuff.)

I don't have problems with weird things. It's not the weirdness
that is
at issue. It's the lack of connection between the particle pair
and the
black hole.

Huh? The particle pairs are everywhere. The black hole only makes them
visible, but not to the naked eye.

They would be visible to the naked eye, if the eye was close enough to
black hole. No human eye could survive there, but the effect would be
visible at a greater distance, for a sufficiently small black hole
that was emitting Hawking radiation sufficiently rapidly.

Someday we will create black holes in the lab and may observe Hawking
radiation. My understanding is that the strength of the radiation would
be proportional to the size of the black hole, so if we created a very
small one it would in essence explode immediately. I think we could
detect that.


Man, I hope nobody is stupid enough to do that. A miscalculation could
literally destroy the planet.


How is that?

BTW, I think you overvalue the planet. We are headed for a planet that
won't sustain life in not so many centuries anyway. I'd like to see
some cool stuff before then.

--

Rick C


Guest

Tue Jan 10, 2017 2:13 pm   



On Tuesday, January 10, 2017 at 8:26:19 PM UTC+11, David Brown wrote:
Quote:
On 10/01/17 02:55, bill.sloman_at_ieee.org wrote:
On Tuesday, January 10, 2017 at 12:11:14 PM UTC+11, rickman wrote:
On 1/9/2017 11:07 AM, Phil Hobbs wrote:
On 01/08/2017 11:06 PM, rickman wrote:

snip

This newsgroup would be a lot nicer if you folks would learn how to snip
posts!

Someday we will create black holes in the lab and may observe Hawking
radiation. My understanding is that the strength of the radiation would
be proportional to the size of the black hole, so if we created a very
small one it would in essence explode immediately. I think we could
detect that.


Man, I hope nobody is stupid enough to do that. A miscalculation could
literally destroy the planet.

How is that?

BTW, I think you overvalue the planet.

Having a black hole eat the entire planet would be a bad outcome,


Sure, having a black hole eat the planet would be bad. But how would
that relate to creating black hole in the lab? The idea that even a
tiny black hole would be catastrophic is great for science fiction, but
/very/ far from reality.

http://www.livescience.com/4210-rumors-black-hole-factory-destroy-earth.html

https://www.quora.com/Is-it-possible-to-create-a-miniature-black-hole-on-earth-inside-a-lab-without-creating-a-massive-catastrophy

http://www.askamathematician.com/2012/07/q-is-it-possible-for-an-artificial-black-hole-to-be-created-or-something-that-has-the-same-effects-if-so-how-small-could-it-be-made/


That's interesting. I'd never actually noticed the point that small - low mass - black holes would have to be very dense. The Chandrasekhar limit is 1..3 solar masses, and the Tolman–Oppenheimer–Volkoff limit is between 1.5 and 3 solar masses.

Anything heavier can collapse into a black hole under the influence of gravity alone. Black hole candidates in X-ray binaries seem to lie in the mass range from 3 to 20 solar masses.

The black hole fusion observed by LIGO in 2015 was of two black holes of 36 times and 29 times the mass of the Sun respectively, and the post-merger black hole had a mass of about 62 times the Sun's mass.

Black holes at the centre of galaxies are much more massive, and can be built up of much less dense matter.

--
Bill Sloman, Sydney


Guest

Tue Jan 10, 2017 3:04 pm   



Quote:
Sure, having a black hole eat the planet would be bad.  But how would
that relate to creating black hole in the lab?  The idea that even a
tiny black hole would be catastrophic is great for science fiction, but
/very/ far from reality.


Okay, you sound very sure about that. Which of course you ought to be, considering that the wager you propose is the lives of billions of people plus all of human civilization forever (plus a few dogs and cats and wild animals) versus some asshole's curiosity.

I wonder what odds Jimmy the Greek would offer on that one.

Cheers

Phil Hobbs


Guest

Tue Jan 10, 2017 3:16 pm   



Theoreticians are horrible at naming things.

http://www.gocomics.com/calvinandhobbes/2012/06/24

Cheers

Phil Hobbs

David Brown
Guest

Tue Jan 10, 2017 4:26 pm   



On 10/01/17 02:55, bill.sloman_at_ieee.org wrote:
Quote:
On Tuesday, January 10, 2017 at 12:11:14 PM UTC+11, rickman wrote:
On 1/9/2017 11:07 AM, Phil Hobbs wrote:
On 01/08/2017 11:06 PM, rickman wrote:


<snip>

This newsgroup would be a lot nicer if you folks would learn how to snip
posts!

Quote:
Someday we will create black holes in the lab and may observe Hawking
radiation. My understanding is that the strength of the radiation would
be proportional to the size of the black hole, so if we created a very
small one it would in essence explode immediately. I think we could
detect that.


Man, I hope nobody is stupid enough to do that. A miscalculation could
literally destroy the planet.

How is that?

BTW, I think you overvalue the planet.

Having a black hole eat the entire planet would be a bad outcome,


Sure, having a black hole eat the planet would be bad. But how would
that relate to creating black hole in the lab? The idea that even a
tiny black hole would be catastrophic is great for science fiction, but
/very/ far from reality.

<http://www.livescience.com/4210-rumors-black-hole-factory-destroy-earth.html>

<https://www.quora.com/Is-it-possible-to-create-a-miniature-black-hole-on-earth-inside-a-lab-without-creating-a-massive-catastrophy>

<http://www.askamathematician.com/2012/07/q-is-it-possible-for-an-artificial-black-hole-to-be-created-or-something-that-has-the-same-effects-if-so-how-small-could-it-be-made/>


Guest

Tue Jan 10, 2017 4:36 pm   



On Wednesday, January 11, 2017 at 12:08:02 AM UTC+11, Jeroen Belleman wrote:
Quote:
On 2017-01-10 13:13, bill.sloman_at_ieee.org wrote:
On Tuesday, January 10, 2017 at 8:26:19 PM UTC+11, David Brown
wrote:
On 10/01/17 02:55, bill.sloman_at_ieee.org wrote:
On Tuesday, January 10, 2017 at 12:11:14 PM UTC+11, rickman
wrote:
On 1/9/2017 11:07 AM, Phil Hobbs wrote:
On 01/08/2017 11:06 PM, rickman wrote:


<snip>

Quote:
The black hole fusion observed by LIGO in 2015 was of two black holes
of 36 times and 29 times the mass of the Sun respectively, and the
post-merger black hole had a mass of about 62 times the Sun's mass.

There is the issue that 3 solar masses were apparently radiated
away, some of it *after* the merger. Quite a feat for an object
that was supposed to be 'black'.


The signal was observed some 12 billion years later, and a very long way away.

Creating gravitational waves does use up energy - presumably three solar masses worth in this case - so the two object presumably stopped being entirely black while they were merging.

--
Bill Sloman, Sydney

Jeroen Belleman
Guest

Tue Jan 10, 2017 8:07 pm   



On 2017-01-10 13:13, bill.sloman_at_ieee.org wrote:
Quote:
On Tuesday, January 10, 2017 at 8:26:19 PM UTC+11, David Brown
wrote:
On 10/01/17 02:55, bill.sloman_at_ieee.org wrote:
On Tuesday, January 10, 2017 at 12:11:14 PM UTC+11, rickman
wrote:
On 1/9/2017 11:07 AM, Phil Hobbs wrote:
On 01/08/2017 11:06 PM, rickman wrote:

snip

This newsgroup would be a lot nicer if you folks would learn how to
snip posts!

Someday we will create black holes in the lab and may
observe Hawking radiation. My understanding is that the
strength of the radiation would be proportional to the size
of the black hole, so if we created a very small one it
would in essence explode immediately. I think we could
detect that.


Man, I hope nobody is stupid enough to do that. A
miscalculation could literally destroy the planet.

How is that?

BTW, I think you overvalue the planet.

Having a black hole eat the entire planet would be a bad
outcome,


Sure, having a black hole eat the planet would be bad. But how
would that relate to creating black hole in the lab? The idea that
even a tiny black hole would be catastrophic is great for science
fiction, but /very/ far from reality.

http://www.livescience.com/4210-rumors-black-hole-factory-destroy-earth.html



https://www.quora.com/Is-it-possible-to-create-a-miniature-black-hole-on-earth-inside-a-lab-without-creating-a-massive-catastrophy

http://www.askamathematician.com/2012/07/q-is-it-possible-for-an-artificial-black-hole-to-be-created-or-something-that-has-the-same-effects-if-so-how-small-could-it-be-made/


That's interesting. I'd never actually noticed the point that small -
low mass - black holes would have to be very dense. The Chandrasekhar
limit is 1.3 solar masses, and the Tolman–Oppenheimer–Volkoff limit
is between 1.5 and 3 solar masses.

Anything heavier can collapse into a black hole under the influence
of gravity alone. Black hole candidates in X-ray binaries seem to lie
in the mass range from 3 to 20 solar masses.

The black hole fusion observed by LIGO in 2015 was of two black holes
of 36 times and 29 times the mass of the Sun respectively, and the
post-merger black hole had a mass of about 62 times the Sun's mass.


There is the issue that 3 solar masses were apparently radiated
away, some of it *after* the merger. Quite a feat for an object
that was supposed to be 'black'.

Jeroen Belleman

John Devereux
Guest

Tue Jan 10, 2017 8:25 pm   



pcdhobbs_at_gmail.com writes:

Quote:
Sure, having a black hole eat the planet would be bad.  But how would
that relate to creating black hole in the lab?  The idea that even a
tiny black hole would be catastrophic is great for science fiction, but
/very/ far from reality.

Okay, you sound very sure about that. Which of course you ought to be,
considering that the wager you propose is the lives of billions of
people plus all of human civilization forever (plus a few dogs and
cats and wild animals) versus some asshole's curiosity.

I wonder what odds Jimmy the Greek would offer on that one.


With respect to neart term capabilities, the argument I have seen is
that the collisions involved have happened billions of times on Earth
already. Due to atmospheric collisions by the higher energy cosmic rays.

It reminds me of the early nuclear weapon tests. They did a calculation
to check if the device would ignite the atmosphere...



--

John Devereux

David Brown
Guest

Tue Jan 10, 2017 8:27 pm   



On 10/01/17 13:13, bill.sloman_at_ieee.org wrote:
Quote:
On Tuesday, January 10, 2017 at 8:26:19 PM UTC+11, David Brown
wrote:
On 10/01/17 02:55, bill.sloman_at_ieee.org wrote:
On Tuesday, January 10, 2017 at 12:11:14 PM UTC+11, rickman
wrote:
On 1/9/2017 11:07 AM, Phil Hobbs wrote:
On 01/08/2017 11:06 PM, rickman wrote:

snip

This newsgroup would be a lot nicer if you folks would learn how to
snip posts!

Someday we will create black holes in the lab and may
observe Hawking radiation. My understanding is that the
strength of the radiation would be proportional to the size
of the black hole, so if we created a very small one it
would in essence explode immediately. I think we could
detect that.


Man, I hope nobody is stupid enough to do that. A
miscalculation could literally destroy the planet.

How is that?

BTW, I think you overvalue the planet.

Having a black hole eat the entire planet would be a bad
outcome,


Sure, having a black hole eat the planet would be bad. But how
would that relate to creating black hole in the lab? The idea that
even a tiny black hole would be catastrophic is great for science
fiction, but /very/ far from reality.

http://www.livescience.com/4210-rumors-black-hole-factory-destroy-earth.html



https://www.quora.com/Is-it-possible-to-create-a-miniature-black-hole-on-earth-inside-a-lab-without-creating-a-massive-catastrophy

http://www.askamathematician.com/2012/07/q-is-it-possible-for-an-artificial-black-hole-to-be-created-or-something-that-has-the-same-effects-if-so-how-small-could-it-be-made/


That's interesting. I'd never actually noticed the point that small -
low mass - black holes would have to be very dense. The Chandrasekhar
limit is 1.3 solar masses, and the Tolman–Oppenheimer–Volkoff limit
is between 1.5 and 3 solar masses.


/All/ black holes are very dense. Even ignoring considerations of
different sizes of black holes having different densities, a small mass
black hole is going to be extremely small. It is also going to have
extremely low mass. This means its gravitational pull is going to be
extremely small, and it is extremely unlikely to capture any other
matter within its pull.

So if we assume there is no Hawking radiation and black holes can grow
but not "evaporate", if we made a black hole in the lab it would move
under the influence of gravity just like a point mass. It would not
interact with other matter in any significant way, as it would simply
pass through any atoms (just like neutrinos). Depending on its mass and
initial speed, it is likely to end up in orbit around the earth's centre
of gravity. Based on the values given in the links above (which I have
no reason to doubt), it would perhaps swallow a proton every hundred
years or so. It is not exactly a disaster.

Note also that while CERN have managed to make collisions with
impressively high energies, we are regularly hit by cosmic rays with
/much/ higher energies. If we had the remotest chance of making a black
hole in the lab, and if that black hole posed the remotest danger, then
we would already have been gobbled up by a black hole from a cosmic ray
collision.

Quote:

Anything heavier can collapse into a black hole under the influence
of gravity alone. Black hole candidates in X-ray binaries seem to lie
in the mass range from 3 to 20 solar masses.

The black hole fusion observed by LIGO in 2015 was of two black holes
of 36 times and 29 times the mass of the Sun respectively, and the
post-merger black hole had a mass of about 62 times the Sun's mass.

Black holes at the centre of galaxies are much more massive, and can
be built up of much less dense matter.


David Brown
Guest

Tue Jan 10, 2017 8:29 pm   



On 10/01/17 14:04, pcdhobbs_at_gmail.com wrote:
Quote:
Sure, having a black hole eat the planet would be bad. But how
would that relate to creating black hole in the lab? The idea that
even a tiny black hole would be catastrophic is great for science
fiction, but /very/ far from reality.

Okay, you sound very sure about that. Which of course you ought to
be, considering that the wager you propose is the lives of billions
of people plus all of human civilization forever (plus a few dogs and
cats and wild animals) versus some asshole's curiosity.


Yes, I /am/ very sure about it.

And I can't lose. Or at least, if I lose, the other side can't collect!

Quote:
I wonder what odds Jimmy the Greek would offer on that one.

Cheers

Phil Hobbs


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