Blackholes: Accretion Vs Expulsion

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Re: Blackholes: Accretion Vs Expulsion

Postby geckzilla » Fri Mar 31, 2017 1:00 am

BDanielMayfield wrote:From much earlier, there was this exchange:
Chris Peterson wrote:
rstevenson wrote:If the black hole conveniently passes through the Sun from pole to pole, there should be no terrible consequences for our system of planets. Everything should just keep rolling around where it's supposed to roll.

Ever play around with a gravity simulator program? Throw another stellar mass in our system, even passing through from north to south, and it's game over for planetary orbits. Everything will be rolling in a new place. Not good.

Does anyone reading this have such a "gravity simulator program"? It would be nice to get a report of what such a program would show with this scenario.

Try Universe Sandbox. ...Well, I'd say try it, but I just checked and apparently the free trial version is gone. Well, it's probably worth the $25, anyway. Better than movie tickets...
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Re: Blackholes: Accretion Vs Expulsion

Postby BDanielMayfield » Fri Mar 31, 2017 3:06 am

geckzilla wrote:
BDanielMayfield wrote:From much earlier, there was this exchange:
Chris Peterson wrote:Ever play around with a gravity simulator program? Throw another stellar mass in our system, even passing through from north to south, and it's game over for planetary orbits. Everything will be rolling in a new place. Not good.

Does anyone reading this have such a "gravity simulator program"? It would be nice to get a report of what such a program would show with this scenario.

Try Universe Sandbox. ...Well, I'd say try it, but I just checked and apparently the free trial version is gone. Well, it's probably worth the $25, anyway. Better than movie tickets...


Thanks geck. Perphaps someone already has a copy and can run a simulation.

Then there's the brute force number crunching do it [to] yourself with a humongous spreadsheet approach. Hey Doum ... :lol2:

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Re: Blackholes: Accretion Vs Expulsion

Postby rstevenson » Fri Mar 31, 2017 3:10 am

geckzilla wrote:Try Universe Sandbox. ...Well, I'd say try it, but I just checked and apparently the free trial version is gone. Well, it's probably worth the $25, anyway. Better than movie tickets...

I just bought it because it seems it will do the simulation I need. The install process was a major PITA, but it's done now, and I'll give it a try tomorrow.

Rob

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Re: Blackholes: Accretion Vs Expulsion

Postby geckzilla » Fri Mar 31, 2017 5:54 am

It's really fun to play around with and has come in useful many times for me when I want to understand some less-than-intuitive physics thing. Pulse some light particles out and watch them crawl at the mind-numbingly slow speed of light...
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Re: Blackholes: Accretion Vs Expulsion

Postby BDanielMayfield » Fri Mar 31, 2017 12:49 pm

Does this software come with our solar system preloaded?
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Re: Blackholes: Accretion Vs Expulsion

Postby rstevenson » Fri Mar 31, 2017 1:59 pm

BDanielMayfield wrote:Does this software come with our solar system preloaded?

Yes, and it runs as the default when I start the program. There are several other simulations included too. I haven't gone looking yet, but I assume there are others available to be downloaded.

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Re: Blackholes: Accretion Vs Expulsion

Postby Doum » Sun Apr 02, 2017 4:18 am

BDanielMayfield wrote:
geckzilla wrote:
BDanielMayfield wrote:From much earlier, there was this exchange:

Does anyone reading this have such a "gravity simulator program"? It would be nice to get a report of what such a program would show with this scenario.

Try Universe Sandbox. ...Well, I'd say try it, but I just checked and apparently the free trial version is gone. Well, it's probably worth the $25, anyway. Better than movie tickets...


Thanks geck. Perphaps someone already has a copy and can run a simulation.

Then there's the brute force number crunching do it [to] yourself with a humongous spreadsheet approach. Hey Doum ... :lol2:

Bruce


Done my share. I dont know enough to do it. :) i will look at that universe sandbox. it might be fun. And less painfull in the head .

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Re: Blackholes: Accretion Vs Expulsion

Postby BDanielMayfield » Fri Apr 21, 2017 1:46 pm

So, how did the simulations go? My guess is that no planets would stay bound to the Sun. Were any captured by the BH, or did they all go rogue?

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Re: Blackholes: Accretion Vs Expulsion

Postby rstevenson » Fri Apr 21, 2017 6:47 pm

I've been busy with life. I keep trying to get back to the sim, but not so far. I'll drop in the results when I do.

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Re: Blackholes: Accretion Vs Expulsion

Postby BDanielMayfield » Fri Apr 21, 2017 8:57 pm

rstevenson wrote:I've been busy with life. I keep trying to get back to the sim, but not so far. I'll drop in the results when I do.

Rob


And we thought you were busy with fiction, writing your epic sci-fi masterpiece.

Doum, sounded like you where going to get the software too. Have you, and how doomed is the solar system?

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Re: Blackholes: Accretion Vs Expulsion

Postby Doum » Sat Apr 22, 2017 3:23 pm

BDanielMayfield wrote:
rstevenson wrote:I've been busy with life. I keep trying to get back to the sim, but not so far. I'll drop in the results when I do.

Rob


And we thought you were busy with fiction, writing your epic sci-fi masterpiece.

Doum, sounded like you where going to get the software too. Have you, and how doomed is the solar system?

Bruce


I've been busy at my father's maplefarm (He's 88 years old). Being retired permit me that. Also, been busy traveling in a solar system simulation (Kerbal space program). It work with Newton laws and aerodynamics laws. Building rocket and trying to reach moons and other planet without dying. i have 5 KIA (Kill in action :x :cry: ). It's quite instructive.

I will look at the software at some point. But spring bring work to do around.

i supose that planets will be kick out of the sun ( Left behind). The Sun will always be the closest to the black hole with the North South path we have. So the Sun should accelerate faster toward the blackhole leaving the planet wondering here and there behind. After the black hole pass the sun center then planets will have more gravity influence from the blackhole. So they should get farther away from the sun.

Sim will tell.
First get it. Then try to figure out how it work. Then how to use it. Then see how wrong i am. Lot of fun.

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Re: Blackholes: Accretion Vs Expulsion

Postby warmingwarmingwarming » Wed Apr 26, 2017 1:33 am

I posted this in another thread but it might fit better here .. if a Black Hole is devouring anything that comes near it .. isn't it devouring space time itself? And if so, as it devours space time, it must be drawing matter closer to itself. What think ye?

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Re: Blackholes: Accretion Vs Expulsion

Postby BDanielMayfield » Wed Apr 26, 2017 3:44 am

warmingwarmingwarming wrote:I posted this in another thread but it might fit better here .. if a Black Hole is devouring anything that comes near it .. isn't it devouring space time itself? And if so, as it devours space time, it must be drawing matter closer to itself. What think ye?


No, it is just bending spacetime. The curvature of space by gravity, if I understand things correctly, is why something sent off in any random direction will curve, (like planets orbiting a star) instead of just continuing in a straight line. And BH's, like all other massive bodies (planets and stars) only capture objects that are moving slower than the massive body's escape velocity edit: which drops off as the inverse square of the distance. (so the farther away, the weaker the effect.)

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Re: Blackholes: Accretion Vs Expulsion

Postby Chris Peterson » Wed Apr 26, 2017 4:44 am

warmingwarmingwarming wrote:I posted this in another thread but it might fit better here .. if a Black Hole is devouring anything that comes near it .. isn't it devouring space time itself? And if so, as it devours space time, it must be drawing matter closer to itself. What think ye?

You'd have to begin with a mathematical description, within the framework of GR, of what "devouring space time" even means.
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Re: Blackholes: Accretion Vs Expulsion

Postby neufer » Wed Apr 26, 2017 4:48 am

BDanielMayfield wrote:
warmingwarmingwarming wrote:
I posted this in another thread but it might fit better here .. if a Black Hole is devouring anything that comes near it .. isn't it devouring space time itself? And if so, as it devours space time, it must be drawing matter closer to itself. What think ye?


No, it is just bending spacetime. The curvature of space by gravity, if I understand things correctly, is why something sent off in any random direction will curve, (like planets orbiting a star) instead of just continuing in a straight line. And BH's, like all other massive bodies (planets and stars) only capture objects that are moving slower than the massive body's escape velocity edit: which drops off as the inverse square of the distance. (so the farther away, the weaker the effect.)

The Black Hole is bending spacetime such that, at least, some of it terminates at the Black Hole's singularity.

In that sense it is devouring spacetime (and/or space).

Objects outside the event horizon can travel on paths in spacetime that avoid the event horizon and thus do not end at the Black Hole's singularity. [All the steps on a down escalator get 'devoured' at the bottom but if you are quick enough (and head in the up direction) you can avoid the same fate.]
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Re: Blackholes don't bite

Postby BDanielMayfield » Wed Apr 26, 2017 7:13 am

Chris Peterson wrote:
warmingwarmingwarming wrote:I posted this in another thread but it might fit better here .. if a Black Hole is devouring anything that comes near it .. isn't it devouring space time itself? And if so, as it devours space time, it must be drawing matter closer to itself. What think ye?

You'd have to begin with a mathematical description, within the framework of GR, of what "devouring space time" even means.


Isn't spacetime a four dimensional field? Black holes move through spacetime just like stars and planets, but none of these objects, even the most Super Massive Black Holes, cause any damage to spacetime. The curvature of spacetime returns to normal after the hole moves away. No rips or bites out of spacetime are allowed, I would think.
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Re: Blackholes: Accretion Vs Expulsion

Postby BDanielMayfield » Wed Apr 26, 2017 7:41 am

neufer wrote:[All the steps on a down escalator get 'devoured' at the bottom but if you are quick enough (and head in the up direction) you can avoid the same fate.]


I recommend walking down the down escalator, using a gravitational assist to slingshot past the jaws of death at the bottom. :wink:
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Re: Blackholes: Accretion Vs Expulsion

Postby neufer » Wed Apr 26, 2017 10:47 am

BDanielMayfield wrote:
neufer wrote:
[All the steps on a down escalator get 'devoured' at the bottom but if you are quick enough
(and head in the up direction) you can avoid the same fate.]

I recommend walking down the down escalator, using a gravitational assist to slingshot past the jaws of death at the bottom. :wink:

Just re-trace the steps of Prof. Otto Posterman Lidenbrock and you may pop out near Mt. Etna.
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Re: Blackholes don't bite

Postby Chris Peterson » Wed Apr 26, 2017 1:43 pm

BDanielMayfield wrote:
Chris Peterson wrote:
warmingwarmingwarming wrote:I posted this in another thread but it might fit better here .. if a Black Hole is devouring anything that comes near it .. isn't it devouring space time itself? And if so, as it devours space time, it must be drawing matter closer to itself. What think ye?

You'd have to begin with a mathematical description, within the framework of GR, of what "devouring space time" even means.


Isn't spacetime a four dimensional field? Black holes move through spacetime just like stars and planets, but none of these objects, even the most Super Massive Black Holes, cause any damage to spacetime. The curvature of spacetime returns to normal after the hole moves away. No rips or bites out of spacetime are allowed, I would think.

Spacetime isn't a field.

In any case, however, my earlier comment stands: if people want to talk about bending, or ripping, or devouring spacetime, those concepts need to be framed in the math of GR. The words by themselves mean little or nothing.
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Re: Blackholes don't bite

Postby neufer » Wed Apr 26, 2017 2:27 pm

Chris Peterson wrote:
Spacetime isn't a field.

A field is simply space: "a parcel of land marked off and used for pasture or tillage."

(However, a field-day is spacetime.)

http://www.etymonline.com/index.php?all ... arch=field wrote:
field (n.) Old English feld "plain, pasture, open land, cultivated land" (as opposed to woodland), also "a parcel of land marked off and used for pasture or tillage," probably related to Old English folde "earth, land,"
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Re: Blackholes: Accretion Vs Expulsion

Postby warmingwarmingwarming » Wed Apr 26, 2017 11:21 pm

neufer wrote:
No, it is just bending spacetime. The curvature of space by gravity, if I understand things correctly, is why something sent off in any random direction will curve, (like planets orbiting a star) instead of just continuing in a straight line. And BH's, like all other massive bodies (planets and stars) only capture objects that are moving slower than the massive body's escape velocity edit: which drops off as the inverse square of the distance. (so the farther away, the weaker the effect.)

The Black Hole is bending spacetime such that, at least, some of it terminates at the Black Hole's singularity.

In that sense it is devouring spacetime (and/or space).

Objects outside the event horizon can travel on paths in spacetime that avoid the event horizon and thus do not end at the Black Hole's singularity. [All the steps on a down escalator get 'devoured' at the bottom but if you are quick enough (and head in the up direction) you can avoid the same fate.][/quote]


Okay .. some of spacetime terminates at the singularity .. I'm thankful you used the term 'devouring' also. My limited understanding indicates matter also terminates at the singularity, but that eventually the acretion disc will itself disappear into the BH. It seems to me that some of spacetime also must disappear into the BH, and that if it is not continually being replenished, spacetime must be diminishing because it is being terminated in Black Holes. Neufer, can you give a picture of how spacetime is being replenished? Or is spacetime truly diminishing in quantity or perhaps density?
Last edited by warmingwarmingwarming on Wed Apr 26, 2017 11:34 pm, edited 1 time in total.

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Re: Blackholes don't bite

Postby warmingwarmingwarming » Wed Apr 26, 2017 11:23 pm

Chris Peterson wrote:
BDanielMayfield wrote:
Chris Peterson wrote:You'd have to begin with a mathematical description, within the framework of GR, of what "devouring space time" even means.


Isn't spacetime a four dimensional field? Black holes move through spacetime just like stars and planets, but none of these objects, even the most Super Massive Black Holes, cause any damage to spacetime. The curvature of spacetime returns to normal after the hole moves away. No rips or bites out of spacetime are allowed, I would think.

Spacetime isn't a field.

In any case, however, my earlier comment stands: if people want to talk about bending, or ripping, or devouring spacetime, those concepts need to be framed in the math of GR. The words by themselves mean little or nothing.


In other words a person needs to have super advanced degrees in the mathematics of cosmology to participate in discussions here?
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Re: Blackholes don't bite

Postby warmingwarmingwarming » Wed Apr 26, 2017 11:29 pm

Chris Peterson wrote:Spacetime isn't a field.

In any case, however, my earlier comment stands: if people want to talk about bending, or ripping, or devouring spacetime, those concepts need to be framed in the math of GR. The words by themselves mean little or nothing.


This quote from Oxford University may interest you. "It seems that all the paradigm properties of spacetime are described
by the metric field. I will thus finish by discussing whether there are good reasons
for regarding the metric field as describing spacetime completely," http://www.spacetimesociety.org/conferences/2006/docs/Lehmkuhl.pdf
I think I think, though I'm not sure if I all the thoughts I think I think, or if they come to me from .. goodness knows where. :)

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Re: Blackholes don't bite

Postby rstevenson » Thu Apr 27, 2017 12:24 am

warmingwarmingwarming wrote:In other words a person needs to have super advanced degrees in the mathematics of cosmology to participate in discussions here?

Of course not. But some subjects can't be sensibly framed in common English, so any attempt to ask or answer questions devolves into a discussion of nomenclature rather than the subject itself.

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Re: Blackholes don't bite

Postby Chris Peterson » Thu Apr 27, 2017 1:19 am

warmingwarmingwarming wrote:
Chris Peterson wrote:In any case, however, my earlier comment stands: if people want to talk about bending, or ripping, or devouring spacetime, those concepts need to be framed in the math of GR. The words by themselves mean little or nothing.

In other words a person needs to have super advanced degrees in the mathematics of cosmology to participate in discussions here?

To participate in discussions? Certainly not. To suggest new theories or new interpretations of mainstream theory? Yes, such qualifications are likely to be important.
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