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(Forbes)   2018 will be the year that we see a black hole's event horizon for the first time   ( forbes.com) divider line
    More: Cool, event horizon, black hole, black holes, Event Horizon Telescope, Sagittarius A*, General Relativity, radio telescopes  
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2136 clicks; posted to Geek » on 27 Dec 2017 at 2:30 PM (7 weeks ago)   |   Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



39 Comments     (+0 »)
 
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2017-12-27 11:18:48 AM  
There's a "your Mom" joke in that article somewhere.
 
2017-12-27 11:29:21 AM  
img.fark.netView Full Size
 
2017-12-27 02:35:46 PM  
Trump
Chris Christie
Subby's mom


There. It's done.
 
2017-12-27 02:42:19 PM  
img.fark.netView Full Size


/I'll see myself out
 
2017-12-27 02:43:01 PM  
I'm hoping 2018 will be the year we stop getting Forbes greenlights.

/and a pony
 
2017-12-27 02:46:52 PM  
img.fark.netView Full Size
 
2017-12-27 02:51:48 PM  

Mad_Radhu: [img.fark.net image 294x172][View Full Size image _x_]


Came here not needing eyes to see. Leaving happy.
 
2017-12-27 03:05:26 PM  
Ah, black hole, exactly where I jammed into your mother last night Trebek!

img.fark.netView Full Size
 
2017-12-27 03:10:40 PM  
If you double the mass, you don't double the radius.  You double the volume enclosed by the event horizon.

Or am I wrong?  I don't even math, but it seems intuitive.
 
2017-12-27 03:11:19 PM  

Keyser_Soze_Death: I'm hoping 2018 will be the year we stop getting Forbes greenlights.

/and a pony


Maybe the Forbes Paywall is the Event Horizion in question!!

/make it two ponies
 
2017-12-27 03:12:18 PM  
Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?
 
2017-12-27 03:14:24 PM  

ko_kyi: If you double the mass, you don't double the radius.  You double the volume enclosed by the event horizon.

Or am I wrong?  I don't even math, but it seems intuitive.


I'd heard that a black hole's mass is 1:1 proportional to the area of its event horizon.

It's the kind of thing I nod along to when bright people say it, but I don't really have any idea.
 
2017-12-27 03:18:25 PM  
Aren't they bleaching those things white these days.
 
2017-12-27 03:43:17 PM  

Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?


Why would that be wrong?  He says sphere-like to account for fluctuations, which would be a bit too in depth for a general article, but the event horizon should be generally sphere-like, as are almost all massive objects throughout the universe.  The pull would be generally equalized in all directions from the center of gravity.  This would also occur for light.

Maybe I'm not understanding your question.
 
2017-12-27 03:43:49 PM  
Is this about Trump's ass?  I will not click until I know.
 
2017-12-27 03:55:46 PM  

FitzShivering: Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?

Why would that be wrong?  He says sphere-like to account for fluctuations, which would be a bit too in depth for a general article, but the event horizon should be generally sphere-like, as are almost all massive objects throughout the universe.  The pull would be generally equalized in all directions from the center of gravity.  This would also occur for light.

Maybe I'm not understanding your question.


You're not, but that's because it was unclear. I understand that the event horizon encloses a sphere, but it is just a theoretical boundary, not the spherical volume that it defines.

FTA: "Surrounding this singularity is a sphere-like region known as the event horizon"

The article describes the event horizon as a region, when it is not.
 
2017-12-27 04:01:14 PM  

ko_kyi: If you double the mass, you don't double the radius.  You double the volume enclosed by the event horizon.

Or am I wrong?  I don't even math, but it seems intuitive.


Here's a pretty decent pop-sci article that can explain the confusion: https://io9.gizmodo.com/th​e-more-mass-​you-add-to-black-holes-the-lighter-the​y-1680822945
 
2017-12-27 04:02:26 PM  
I've seen plenty of black hole event horizons on PornHub.
 
2017-12-27 04:04:27 PM  

Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?


I'm no expert but to me the event horizon would be a sphere. imagine approaching the blackhole from left or right or top or bottom. The event horizon surrounds the singularity from all directions and so would be a sphere.
 
2017-12-27 04:08:09 PM  

chasd00: Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?

I'm no expert but to me the event horizon would be a sphere. imagine approaching the blackhole from left or right or top or bottom. The event horizon surrounds the singularity from all directions and so would be a sphere.


It is a boundary that encloses a sphere, but is not a region (TFA says it's a region). Sort of like how an eggshell  defines an egg-shaped region but is not itself an egg. I agree it is sphere-shaped.
 
2017-12-27 04:08:54 PM  

Charletron: FitzShivering: Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?

Why would that be wrong?  He says sphere-like to account for fluctuations, which would be a bit too in depth for a general article, but the event horizon should be generally sphere-like, as are almost all massive objects throughout the universe.  The pull would be generally equalized in all directions from the center of gravity.  This would also occur for light.

Maybe I'm not understanding your question.

You're not, but that's because it was unclear. I understand that the event horizon encloses a sphere, but it is just a theoretical boundary, not the spherical volume that it defines.

FTA: "Surrounding this singularity is a sphere-like region known as the event horizon"

The article describes the event horizon as a region, when it is not.


I misread your comment. Yeah I understand it as just a boundary. Like the point of no return. I believe Hawking radiation comes from a particle splitting in two right at the event horizon, one side falls in while the other does not (or something like that). And for some reason I'm too lazy to lookup it costs the black hole mass. So for very tiny black holes Hawking radiation can cause then to "evaporate". All this coming from memories in HS when I was really into Hawking so I could be totally wrong.
 
2017-12-27 04:08:58 PM  

Charletron: FitzShivering: Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?

Why would that be wrong?  He says sphere-like to account for fluctuations, which would be a bit too in depth for a general article, but the event horizon should be generally sphere-like, as are almost all massive objects throughout the universe.  The pull would be generally equalized in all directions from the center of gravity.  This would also occur for light.

Maybe I'm not understanding your question.

You're not, but that's because it was unclear. I understand that the event horizon encloses a sphere, but it is just a theoretical boundary, not the spherical volume that it defines.

FTA: "Surrounding this singularity is a sphere-like region known as the event horizon"

The article describes the event horizon as a region, when it is not.


It is, depending on the definition, a region, especially when you start digging into the arguments over how an event horizon would be physically represented and what is actually happening, there.   I do agree with you that if you don't give him the benefit of the doubt here (I've read his book, so I do, he's a very smart guy, and excellent at physics), that it can be read as implying that the event horizon is the entirety of the black hole from singularity to point of no return.  In retrospect, it's somewhat sloppy writing on his part.  He likely should have said "boundary" rather than "region", though that also, when you get into it, isn't necessarily entirely correct.  Though certainly more correct.

For what it's worth, not that anyone is beholden to doing so, but he's pretty quick on correcting his articles if you point out any sloppy language, and generally updates the article to include that he's done so.  One of the thing I like about them.
 
2017-12-27 04:14:33 PM  

FitzShivering: Charletron: FitzShivering: Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?

Why would that be wrong?  He says sphere-like to account for fluctuations, which would be a bit too in depth for a general article, but the event horizon should be generally sphere-like, as are almost all massive objects throughout the universe.  The pull would be generally equalized in all directions from the center of gravity.  This would also occur for light.

Maybe I'm not understanding your question.

You're not, but that's because it was unclear. I understand that the event horizon encloses a sphere, but it is just a theoretical boundary, not the spherical volume that it defines.

FTA: "Surrounding this singularity is a sphere-like region known as the event horizon"

The article describes the event horizon as a region, when it is not.

It is, depending on the definition, a region, especially when you start digging into the arguments over how an event horizon would be physically represented and what is actually happening, there.   I do agree with you that if you don't give him the benefit of the doubt here (I've read his book, so I do, he's a very smart guy, and excellent at physics), that it can be read as implying that the event horizon is the entirety of the black hole from singularity to point of no return.  In retrospect, it's somewhat sloppy writing on his part.  He likely should have said "boundary" rather than "region", though that also, when you get into it, isn't necessarily entirely correct.  Though certainly more correct.

For what it's worth, not that anyone is beholden to doing so, but he's pretty quick on correcting his articles if you point out any sloppy language, and generally updates the article to include that he's done so.  One of the thing I like about them.


Yeah you bring up a good point haha. Poor human brains aren't so good at thinking about such crazy things. At least not mine since i'm a biochemist, not a physicist
 
2017-12-27 04:14:41 PM  

chasd00: Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?

I'm no expert but to me the event horizon would be a sphere. imagine approaching the blackhole from left or right or top or bottom. The event horizon surrounds the singularity from all directions and so would be a sphere.


That depends on whether the black hole is rotating.

It's also really hard to observe an event horizon, relativistically.
 
2017-12-27 04:19:38 PM  

FitzShivering: chasd00: Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?

I'm no expert but to me the event horizon would be a sphere. imagine approaching the blackhole from left or right or top or bottom. The event horizon surrounds the singularity from all directions and so would be a sphere.

That depends on whether the black hole is rotating.

It's also really hard to observe an event horizon, relativistically.


Wait what happens when it spins
 
2017-12-27 04:27:46 PM  

Charletron: FitzShivering: chasd00: Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?

I'm no expert but to me the event horizon would be a sphere. imagine approaching the blackhole from left or right or top or bottom. The event horizon surrounds the singularity from all directions and so would be a sphere.

That depends on whether the black hole is rotating.

It's also really hard to observe an event horizon, relativistically.

Wait what happens when it spins


The event horizon itself should still be generally an absolute sphere, but the black hole itself can become an oblate spheroid, just like the Earth, in the ergosurface.  Generally related to frame dragging.  For the purposes of his question, the ergosurface is what you're going to end up observing.  It is admittedly so long since I've studied this I'm probably describing it poorly.  Haven't done astrophysics in decades, and spend most of my mathematical abilities calculating beer prices.
 
2017-12-27 04:30:03 PM  

Charletron: FitzShivering: chasd00: Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?

I'm no expert but to me the event horizon would be a sphere. imagine approaching the blackhole from left or right or top or bottom. The event horizon surrounds the singularity from all directions and so would be a sphere.

That depends on whether the black hole is rotating.

It's also really hard to observe an event horizon, relativistically.

Wait what happens when it spins


Here, if you want to break your brain a bit, this is what the LIGO folks captured (rotating black hole pair): https://en.wikipedia.org/wiki/​Kerr_met​ric
 
2017-12-27 04:37:46 PM  
img.fark.netView Full Size

Does NOT approve....
 
2017-12-27 04:39:51 PM  
Maybe an event horizon is simply a place where time slows to a near stop.  Gravitational time dilation to an extreme.
 
2017-12-27 04:47:51 PM  

FitzShivering: Here's a pretty decent pop-sci article that can explain the confusion: https://io9.gizmodo.com/the​-more-mass-you-add-to-black-holes-the-​lighter-they-1680822945


Thanks, very helpful
 
2017-12-27 06:04:47 PM  
First with the appropriate music....
Soundgarden - Black Hole Sun
Youtube 3mbBbFH9fAg

RIP Chris....
 
2017-12-27 08:05:15 PM  
Frederik Pohl consolable.
 
2017-12-27 08:07:23 PM  

TwilightZone: Is this about Trump's ass?  I will not click until I know.


No. But trump is hiring big trucks to block cameras from taking pictures of him golfing!
img.fark.netView Full Size
 
2017-12-27 08:36:23 PM  

Circusdog320: TwilightZone: Is this about Trump's ass?  I will not click until I know.

No. But trump is hiring big trucks to block cameras from taking pictures of him golfing!
[img.fark.net image 425x226][View Full Size image _x_]


A couple of parked cars could put an end to that nonsense real quick.
 
2017-12-27 10:03:18 PM  
Is Pamela Anderson still sexually active?
 
2017-12-27 11:31:00 PM  

Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?


I don't think so. The large black sphere is the event horizon. The actual singularity and lump of mass is much smaller physically and lies at the center of that black sphere. We will never image the singularity until the millipedes that drive the Ted Cruz skin-suit grant us the technology to do so.
 
2017-12-28 12:03:43 AM  
img.fark.netView Full Size

This is why Forbes gets greened. It's not science, it's Forbes
 
2017-12-28 01:34:27 AM  

Mad_Radhu: [img.fark.net image 294x172]


Event Horizon is the best horror movie of the last few decades. Unchallenged.
 
2017-12-29 02:42:32 AM  

Myria: Maybe an event horizon is simply a place where time slows to a near stop.  Gravitational time dilation to an extreme.


No.  The event horizon of a Schwarzschild black hole has no special properties.  Depending on the mass of the black hole, you can pass through the event horizon without even noticing.  The more massive the black hole, the farther out the event horizon is from any area of significant spacetime curvature (which is where you would experience novel effects, like spaghettification).

To a distant observer, it would appear that your clock slowed to a stop (and became more and more red-shifted) as you approached and crossed the event horizon, but in your reference frame, you would pass through it in a normal, finite amount of time, and your clock would continue to tick normally in proper time until you hit the singularity.

FitzShivering: Charletron: FitzShivering: chasd00: Charletron: Article does not describe an event horizon accurately... afaik.

Event horizon is the theoretical boundary beyond which light can't escape. Article describes it as the entire spherical region surrounding the singularity. Isn't that wrong?

I'm no expert but to me the event horizon would be a sphere. imagine approaching the blackhole from left or right or top or bottom. The event horizon surrounds the singularity from all directions and so would be a sphere.

That depends on whether the black hole is rotating.

It's also really hard to observe an event horizon, relativistically.

Wait what happens when it spins

The event horizon itself should still be generally an absolute sphere, but the black hole itself can become an oblate spheroid, just like the Earth, in the ergosurface.  Generally related to frame dragging.  For the purposes of his question, the ergosurface is what you're going to end up observing.  It is admittedly so long since I've studied this I'm probably describing it poorly.  Haven't done astrophysics in decades, and spend most of my mathematical abilities calculating beer prices.


A Kerr black hole actually has two event horizons (neither of which is spherical- they are oblate proportional to the hole's angular speed), and an ergosphere (the region where spacetime is dragged and twisted due to the ringularity's angular momentum).

It doesn't really make sense to talk about the difference between the event horizon and "the black hole itself."  The "black hole itself" is the combination of all of the above phenomena and a few others.  The regions of space inside and outside the event horizon of a non-rotating black hole are not fundamentally different or distinguishable from one another.  They just look different to a distant observer.  The region between the event horizon and Cauchy horizon of a Kerr black hole is only special because the radial coordinate of an infalling particle becomes timelike there due to frame-dragging.  Once the particle crosses the Cauchy horizon, the r coordinate behaves like a spatial coordinate again.
 
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