Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.physics > #557549

Re: Massive gamma ray burst detected after black hole merger

Followups directed to: sci.physics.relativity

Show all headers | View raw

7 wrote:

> Sylvia Else wrote:
>> On 27/02/2016 8:33 PM, 7 wrote:
>>> Massive gamma ray burst detected after black hole merger
>>> --------------------------------------------------------
>>>
>>> http://www.gizmag.com/gravitational-waves-black-hole/42028/
>>>
>>>
>>> The gravitational wave detected by LIGO was follwed
>>> 0.4 seconds later by a massive gamma ray burst.
>>>
>>> To me this is no surprise at all.
>>>
>>> As I was saying before, when black holes try to
>>> merge, the net gravity in the middle between the two
>>> black holes fall off to zero
>> 
>> You can find a point somewhere on the line joining their centres where
>> gravity is zero,

Nonsense.  The gravitational potential (which is negative) approaches only 
zero as the distance from the source of gravity approaches *infinity*.  IOW, 
there is no *definite* position anywhere where gravity is exactly zero.  
AISB, that gravitational forces cancel each other out in the center of mass, 
or IOW that the gravitational potential has a local minimum, or spacetime 
curvature has a local maximum, at a point, does not mean that gravity is 
zero there.

In the same sense, “Zero G(ravity)” is only a laymen’s term; scientists 
speak of “microgravity” instead when referring to the laymen’s 
“weightlessness” in orbit (like in the ISS).

>> but as soon as you move off that line, non-zero gravity is again present.

In the wrong terminology that you used above, that statement is actually 
correct.
 
> Great news for photons in a gamma ray burst. It can leave.

So it cannot, in that scenario.
 
>> In any case, the field at the centre of a black hole is presumably zero
>> as well,

Utter nonsense.  The gravitational potential is infinitely small there, and 
the spacetime curvature is infinitely large there.  Which is why there is a 
*singularity* and everything is pulled towards it (or in GR terms, has a 
spacetime trajectory that ends there¹).

>> and that doesn't result in the emission of matter.
> 
> […] 
> Emit to where exactly?

Can’t you read?  She said (correctly) that there is *no* emission of matter 
from a black hole.


F'up2 sci.physics.relativity

PointedEars
___________
¹  unless it is a certain type of rotating black hole
-- 
Q: What did the female magnet say to the male magnet?  
A: From the back, I found you repulsive, but from the front
   I find myself very attracted to you.
(from: WolframAlpha)

Back to sci.physics | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-27 09:33 +0000
  Massive gamma ray burst detected after black hole merger HVAC <mr.hvac@gmail.com> - 2016-02-27 03:40 -0800
    Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-27 12:30 +0000
      Re: Massive gamma ray burst detected after black hole merger john <johnsefton288@gmail.com> - 2016-02-27 04:47 -0800
        Re: Massive gamma ray burst detected after black hole merger HVAC <mr.hvac@gmail.com> - 2016-02-27 05:06 -0800
        Re: Massive gamma ray burst detected after black hole merger Sam Wormley <swormley1@gmail.com> - 2016-02-27 08:04 -0600
      Re: Massive gamma ray burst detected after black hole merger HVAC <mr.hvac@gmail.com> - 2016-02-27 05:02 -0800
        Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-27 13:35 +0000
          Re: Massive gamma ray burst detected after black hole merger HVAC <mr.hvac@gmail.com> - 2016-02-27 06:01 -0800
            Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-27 16:37 +0000
              Re: Massive gamma ray burst detected after black hole merger HVAC <mr.hvac@gmail.com> - 2016-02-27 09:17 -0800
              Re: Massive gamma ray burst detected after black hole merger HVAC <mr.hvac@gmail.com> - 2016-02-27 09:30 -0800
            Re: Massive gamma ray burst detected after black hole merger benj <none@gmail.com> - 2016-02-27 15:16 -0500
              Re: Massive gamma ray burst detected after black hole merger Sam Wormley <swormley1@gmail.com> - 2016-02-27 18:56 -0600
              Re: Massive gamma ray burst detected after black hole merger Odd Bodkin <bodkinodd@gmail.com> - 2016-02-29 09:00 -0600
                Re: Massive gamma ray burst detected after black hole merger HVAC <mr.hvac@gmail.com> - 2016-02-29 07:08 -0800
          Re: Massive gamma ray burst detected after black hole merger Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-27 17:15 +0100
            Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-27 16:26 +0000
              Re: Massive gamma ray burst detected after black hole merger Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-27 17:51 +0100
                Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-27 18:13 +0000
      Re: Massive gamma ray burst detected after black hole merger Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-27 17:13 +0100
        Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-27 16:22 +0000
          Re: Massive gamma ray burst detected after black hole merger Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-27 17:53 +0100
            Re: Massive gamma ray burst detected after black hole merger john <johnsefton288@gmail.com> - 2016-02-27 09:07 -0800
              Re: Massive gamma ray burst detected after black hole merger HVAC <mr.hvac@gmail.com> - 2016-02-27 09:26 -0800
              Re: Massive gamma ray burst detected after black hole merger Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-27 18:47 +0100
              Re: Massive gamma ray burst detected after black hole merger Odd Bodkin <bodkinodd@gmail.com> - 2016-02-27 11:56 -0600
            Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-27 18:01 +0000
              Re: Massive gamma ray burst detected after black hole merger Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-27 19:06 +0100
                Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-27 18:16 +0000
                Re: Massive gamma ray burst detected after black hole merger Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-27 19:39 +0100
  Re: Massive gamma ray burst detected after black hole merger Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-27 17:09 +0100
    Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-27 16:18 +0000
      Re: Massive gamma ray burst detected after black hole merger Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-27 18:22 +0100
        Re: Massive gamma ray burst detected after black hole merger "hanson" <hanson@quick.net> - 2016-02-27 10:55 -0800
  Re: Massive gamma ray burst detected after black hole merger Yousuf Khan <bbbl67@spammenot.yahoo.com> - 2016-02-27 19:52 -0500
    Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-28 10:09 +0000
      Re: Massive gamma ray burst detected after black hole merger Yousuf Khan <bbbl67@spammenot.yahoo.com> - 2016-02-29 10:48 -0500
  Re: Massive gamma ray burst detected after black hole merger Sylvia Else <sylvia@not.at.this.address> - 2016-02-28 11:59 +1100
    Re: Massive gamma ray burst detected after black hole merger 7 <7@enemygadgets.com> - 2016-02-28 10:05 +0000
      Re: Massive gamma ray burst detected after black hole merger Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-28 14:39 +0100
  Re: Massive gamma ray burst detected after black hole merger "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-02-29 09:59 -0800
    Re: Massive gamma ray burst detected after black hole merger Sam Wormley <swormley1@gmail.com> - 2016-02-29 12:01 -0600
    Re: Massive gamma ray burst detected after black hole merger Sam Wormley <swormley1@gmail.com> - 2016-02-29 20:01 -0600
  Re: Massive gamma ray burst detected after black hole merger "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-03-01 11:34 -0800
    Re: Massive gamma ray burst detected after black hole merger HVAC <mr.hvac@gmail.com> - 2016-03-01 14:10 -0800

csiph-web