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Re: Massive gamma ray burst detected after black hole merger

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7 wrote:

> Thomas 'PointedEars' Lahn wrote:
>> 7 wrote:
>>> Thomas 'PointedEars' Lahn wrote:
>>>>> As I was saying before, when black holes try to merge,
>>>> Black holes do not “try to” merge; either they merge or they do not.
>>>> They do not have will, but just have to follow laws of nature.  Saying
>>>> that black holes try to merge is as nonsensical as saying that a ball
>>>> dropped tries to fall down.
>>> Well if it didn't try, it couldn't have fallen.
>> Incorrect.
> 
> Which is utter bullocks

No, it is not.  An inanimate object like a ball does not try.  It cannot; it 
just moves, and *how* it moves is governed by laws of nature.

> as so is this synthesis:
> 
>> […]

That you do not accept without reason what I wrote does not make it wrong.
Humans have come a long way in the almost two and a half millenia since 
Aristotle’s natural philosophy in which he claimed that the ball would fall 
down because it would, because of its nature of being heavy, wanting to be 
with the Earth, which he thought to be the center of the universe.  Your 
ignorance of what has been learned does not change the knowledge.

>>>>> the net gravity in the middle between the two black holes fall off
>>>>> to zero […]
>>>> How did you get that idea?
>>> You know I did some thought experiments with a planets
>>> and figured the centre of a planet has zero gravity.
>> Imprecise at best.
> 
> False. 100% accurate.

No, as I just explained, in Newtonian mechanics gravity is still not zero, 
and in general relativity the spacetime curvature is still not zero.
 
>> There is no *net* force on a test mass in the center
>> *of mass* of a planet because the gravitational forces pulling from all
>> sides
>> *cancel each other out*.  However, as I just stated, there is still
>> gravity there, and in GR terms the spacetime curvature reaches a local
>> maximum there.
> 
> Which is precisely wrong because it contradicts your
> first assertion about test mass.

No, it does not.  If forces pull equally on a test mass from *all* sides, 
then those forces cancel each other out.  If we define everything that has a 
greater distance from the center of mass of the planetary body than the test 
mass there to be “above”, then everything above the test mass located in the 
center of mass of the planetary body pulls on it (and the test mass pulls on 
it, but that is negligible).  The fact that nothing can pull it towards the 
center of mass does not mean that the force of gravity has just disappeared.
 
> As much as I would like to believe you,
> I draw the line somewhere and choose to believe
> the physics of what is happening at the centre belongs precisely to
> the story of what is happening to the test mass.

You have misunderstood the physics of what is happening.  The stuff above 
the test mass has not disappeared, and it still *also* has mass, thereby 
exerting a gravitational force on other objects with mass, according to 
Newton.
 
> Alternative interpretations have no power of persuasion if they
> have no power of prediction unless you care to make
> one that could be tested now or in the future.

It really is very simple: Newton said that *every* object with mass exerts a 
gravitational force on other objects with mass.  That *includes* the stuff 
above the test mass (the planet’s matter) when it is located in the center 
of mass of a planetary body.

The test mass in our scenario can be thought of to be located in an 
infinitesimal sphere, where the flow of the gravitational force points 
outwards, perpendicular to the sphere’s surface.  So there is no *net* 
gravitational force within the sphere, but that does not mean that there is 
no flow of force.  If I drew you an ASCII art of the scenario indicating the 
flow of force that showed this, would you accept that?

>>> Ergo black hole gravity collapses in the same way when
>>> black holes are trying to merge.
>> Black holes are based on general relativity, not Newtonian gravity, so
>> saying that “black holes gravity collapses” is *at least* referring to an
>> ill-defined concept.
>> 
>> What actually happens is that the curvature of spacetime increases
>> towards the singularity of the black hole where it approaches positive
>> infinity. That means that as black holes merge, the spacetime curvatures
>> of the black holes *add up*.  Given that the curvature is positive in and
>> around both black holes, how could it become zero between them as they
>> get closer together and finally merge?
> 
> Which is why I told you to make a precise
> prediction with your interpretation of the science.

I do not employ an interpretation of science.  I am telling you what the 
current scientific knowledge actually is, contrary to your misconceptions.
 
> You could predict for example Lagrange points are figments
> of the imagination.

But if the mathematics were not enough, at the latest the fact that human-
made observatories have relatively stable positions near some of those L-
points (e.g., LISA Pathfinder is orbiting Sol–Terra L₁ since 2016-01-22 – in 
order to improve detection of gravitational waves, no less –, SOHO is 
orbiting it since 1996; the Gaia probe is orbiting Sol–Terra L₂ since 2013), 
falsifies that prediction.  So the theory, if any, that predicted the 
absence of L-points were demonstrated to be wrong.
 
> I choose to believe in what happens to a test mass.

See, that is the relevant difference between us.  I choose not to believe, 
but to look (up), therefore to know, to think about it (and write about it), 
and to understand.

> The g forces sum to zero

At the center of mass of a planet, yes (a different situation), and that 
requires that gravitational forces are still there.  So we have ascertained 
now that gravity is _not_ zero there.

Neither is it zero between black holes.  Suppose the black holes have equal 
properties, and a test mass is located between them, then a nudge in any 
direction sends it towards one of those black holes, even if slowly at 
first.

> and any test mass is free to escape,

No, it is not.  Because the moment a test mass leaves the position where the 
gravitational forces cancel out, it is pulled back.

> and so is any light such as gamma rays.

You cannot apply Newton’s law of universal gravitation to light to begin 
with.  And according to general relativity, which you can apply to light, 
nothing can escape a black hole, not even light (which travels at the 
fastest possible speed).  That is why the black hole *itself* is invisible 
to the human observer (phenomena like gravitational lensing and relativistic 
jets, and observatories like LIGO notwithstanding), and is therefore called 
a *black* hole.


PointedEars
-- 
Two neutrinos go through a bar ...

(from: WolframAlpha)

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Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-27 17:58 +0000
  Re: Massive gamma ray burst detected after black hole merger Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-27 22:57 +0100

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