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Thread: Black hole questions

  1. #1
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    Black hole questions

    Hello fellow members,

    I am new here and came across this board off the net. I have been reading up recently about black holes which I know nothing about and came across a few recent articles about the possibility of a super massive black whole destroying the universe. The article does not specify a timeframe which gave me the jitters. Can anyone shed some light to this and possibly a time frame.

    Also came across articles about our black hole getting 75 times brighter. How would this affect us?

    Thank you in advance and I apologize if my questions seem dumb. Everyone had to start learning somewhere.

  2. #2
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    Our SMBH (Sgr A*) got 75 times brighter for a short time, and the effect on us was that we had some sensitive instruments capable of noticing it.

    As to the other issues, I would have to see the study you are talking about, but it is a safe bet that it won't happen in your lifetime, if ever. Some studies explore unlikely ideas that aren't excluded by current models, and this sounds like one of those.
    Forming opinions as we speak

  3. 2019-Aug-17, 12:37 AM
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  4. 2019-Aug-17, 12:40 AM
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  5. 2019-Aug-17, 12:41 AM
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  6. #3
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    Quote Originally Posted by Sinbad View Post
    Hello fellow members,

    I am new here and came across this board off the net. I have been reading up recently about black holes which I know nothing about and came across a few recent articles about the possibility of a super massive black whole destroying the universe.
    Hello and welcome!

    So the article said it could destroy the whole universe? Thats.....a bit optomistic. Lets try just one galaxy and see if a black hole of any size can destroy only that. (these are rough calculations, take them with a grain of salt):

    Our galaxy: 100,000 light years across
    Mass: 1 trillion solar masses
    Our galaxy's central black hole: 0.000001 light years across
    Mass: 4 million solar masses
    Gravitational force on the Earth from this black hole: 8*10^-15 N, which is a very small force.

    So, the Milky way black hole clearly isn't big enough. Lets replace that one with the biggest black hole in the entire universe that we've ever discovered, which is about a thousand times larger then the Milky way one.

    M87 black hole: 0.002 light years across
    Mass: about 6 billion solar masses
    Gravitational force on the Earth (IF it was in the center of our own galaxy): 5*10^-12 N, which is still pitifully small.

    So, even the largest black hole in existence couldn't even destroy one galaxy. It's size is nothing compared to the size of the galaxy (0.002 light years compared to 100,000 light years), and the force it generates is also nothing compared to local gravitational forces. And if it can't destroy one galaxy, the universe as a whole is pretty safe.

    So I wouldn't worry about any black hole destroying the entire universe, as powerful as they are they are still just too puny to effect the entire universe. Though I would be very interested to read that article which stated this.

  7. #4
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    I think this is probably related to the psi Ikura of a black hole triggering a collapse of the false vacuum. It has been theorized that it could happen, but the caveat is that if it hasn’t happened yet, it won’t happen because the universe is full of black holes but has not been destroyed.

    So it isn’t something to worry about.


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    As above, so below

  8. 2019-Aug-17, 09:27 AM
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  9. #5
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    I have tried 3 times to post this for about 12 hours now and it won’t appear on the board. I am replying to the request for the article I was referring to

    https://www.ibtimes.com/newly-discov...t-warn-2814136

  10. #6
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    Sinbad, your questions are dumb only if you don't ask them. This is a good place to pick our brains about astronomy and space science questions.

  11. #7
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    Quote Originally Posted by Sinbad View Post
    ...a few recent articles about the possibility of a super massive black whole destroying the universe.....
    Ain't gonna happen. Many if not most galaxies have massive black holes in their centers (if not supermassive). Stars orbit these things just like they were some other massive bodies.
    Everyone is entitled to his own opinion, but not his own facts.

  12. #8
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    Quote Originally Posted by Sinbad View Post
    I have been reading up recently about black holes which I know nothing about and came across a few recent articles about the possibility of a super massive black whole [sic] destroying the universe.
    Can you tell us where to find these articles? It is usually the case that journalists sensationalize such claims in order to draw rearrange.

    Fred
    Hey, you! "It's" with an apostrophe means "it is" or "it has." "Its" without an apostrophe means "belongs to it."

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    Earth's sole legacy will be a very slight increase (0.01%) of the solar metallicity.

  13. #9
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    My apologies to all. It is not allowing me to post the article, The article was off the IBL website on Aug 16th. It basically spoke of the find of a new black hole. 60 million times bigger than previously found. It also spoke about the possibility of sucking in the universe.
    I just want to clarify I am not a spammer or troll just trying to cause trouble. I generally do not astronomy and science so reading the article does not make sense in my mi d and was just hoping to get a better Understanding of it

    This is the article

    https://www.ibtimes.com/newly-discov...t-warn-2814136
    Last edited by Sinbad; 2019-Aug-18 at 02:55 AM.

  14. #10
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    The astronomer named in the article is quoted as saying that there are theories that in an unimaginably long time everything in the universe could fall into black holes. That is a far cry from being a warning of some sort of impending doomsday. If I am not mistaken that long time is billions of times the present age of the universe as we know it, and the theory has been around for some 40 years.

  15. #11
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    Thank you for putting it into terms that make more sense to me. It’s funny but for some reason when I read astronomy or science , it’s reads to me like the adults sound in the Charlie Brown cartoons. Wierd now that I think of it my wife sounds that way also.
    Last edited by Sinbad; 2019-Aug-18 at 02:58 PM.

  16. #12
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    Quote Originally Posted by Hornblower View Post
    The astronomer named in the article is quoted as saying that there are theories that in an unimaginably long time everything in the universe could fall into black holes.
    Black holes; plural.?

    At first I was assuming the idea was that the whole universe could be gobbled up by one superdupermassive BH, and that would require the universe to stop expanding and collapse back on itself. Which would be indistinguishable from the "Big Crunch" conjecture anyway.
    Last edited by DaveC426913; 2019-Aug-19 at 02:44 PM.

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    David Whitehouse: “This one is enormous, so perhaps there are even bigger black holes out there,” he said. “And there are some theories which suggest that eventually in the vast length of time, more time in the future than we can imagine, everything will end up in a black hole. The whole universe.”
    Whitehouse has written a number of books about the solar system. He does not appear to be a specialist in black holes, and he does not say anything more about the referenced theories about everything ending up "in a black hole," or how such theories square with black hole evaporation and Hawking radiation.

    When one is talking about a future billions of times the current age of the universe, it's easy to speculate about what could "possibly" happen.
    Everyone is entitled to his own opinion, but not his own facts.

  18. #14
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    There you have it. A scientist who perhaps is out of his area of expertise made some vague references. In doing so he gave this publication an inch and they took a mile, apparently driven in part by the misbegotten misconception of a black hole sucking in stuff as if it was a vacuum cleaner.

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    Magnetars would probably be a greater threat to metal spacecraft than a black hole

  20. #16
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    Quote Originally Posted by publiusr View Post
    Magnetars would probably be a greater threat to metal spacecraft than a black hole
    A black hole itself is no threat to anything that stays outside that radius of no escape. Radiation from accreting matter around it could be a different story.

  21. #17
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    You could orbit a black hole closer than you could a "burning" star--but wouldn't a magnetar's magnetic field behave more like the popular notion of gravity--something that very well could yank you down.
    A small magnet beats a whole planet's worth of gravity on a paper clip, after all.

  22. #18
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    Quote Originally Posted by publiusr View Post
    A small magnet beats a whole planet's worth of gravity on a paper clip, after all.
    Only because you are a LOT close to the center of the paper clip then to the center of the Earth. Put the paper clip at a distance of 6,000 miles so it's a fair contest, then try using a magnet on it and the Earths gravity will win by a large margin.

    Also, another difference between magnetism and gravity is that magnetic strength falls off with the cube root of distance, whereas gravitational strength falls off with the square root of distance. So it doesn't really act much like gravity I'm afraid.

  23. 2019-Sep-12, 06:52 AM
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