joe
Lv 4

will gravity eventually overcome universal expansion?

leaving out the concept of nothingness and space, concerning only matter, one theory regarding the demise of the universe is through entropy and the eventual expansion of everything into an evenly spaced nothingness, with no one part of the universe having measurable mass. but black holes shoot down that theory quick because they never reach critical mass, and never explode. so, unlike stars which have the potential to scatter their atoms through the cosmos, a black hole will only ever collect matter. so, will the expansion of the universe be overcome by gravity, which is indefinate? there are models that show that the universe is expanding, however there are clusters of matter known as galaxies, which are held together through gravity and occasionally come together to form one larger galaxy. so, the supermassive black holes in their centers, combined with the total mass of the galaxies are pulled together through gravity, despite the universal expansion. will one day the black holes consume everything in existence then eventually fall together to form a single titanic supermassive black hole?

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  • 2 months ago
    Favourite answer

    >>will gravity eventually overcome universal expansion?

    Way back in the olden days, like 1985, the big question was if the Big Bang's expansion was powerful enough to overcome the gravity of all the matter in the universe... in other words, did all the galactic clusters have escape velocity from each other?  

    It was naturally assumed that the expansion must be slowing due to gravity, so astronomers worked to find out and measure the speed of expansion... 

    In the 90s, it was discovered that the expansion isn't slowing - it's *speeding up*.  They don't know why... the effect is called "Dark Energy" - basically, there's unknown energy being applied to galactic clusters which are accelerating their speed away from each other. 

    Given that information... It doesn't look like gravity will stop universal expansion. 

    >>leaving out the concept of nothingness and space, concerning only 

    >>matter, one theory regarding the demise of the universe is through 

    >>entropy and the eventual expansion of everything into an evenly spaced 

    >>nothingness, with no one part of the universe having measurable mass. 

    >>but black holes shoot down that theory quick because they never reach 

    >>critical mass, and never explode. 

    True... and, assuming matter itself doesn't simply degrade into energy, it's beginning to look like 'Heat Death' may be the final result. 

    >>so, unlike stars which have the potential to scatter their atoms through

    >>the cosmos, a black hole will only ever collect matter. 

    Hmmm... Well, dying stars do explode; our sun will slough off it's outer layers as it becomes a red giant, but in the end - they'll be dense, massive objects that no longer burn through fusion. Giant stars become black holes and pulsars; smaller stars will be just masses of helium and carbon for the most part - also collecting atoms through gravity.

    >>so, will the expansion of the universe be overcome by gravity, which 

    >>is indefinate? there are models that show that the universe is expanding, 

    >>however there are clusters of matter known as galaxies, which are held 

    >>together through gravity and occasionally come together to form one 

    >>larger galaxy. 

    True... and, as time goes on, hydrogen needed for new stars will reach a point where the element is so diffuse and so rare that no new stars will be able to form. You'd have huge, dark galaxies, filled with nothing but black holes, neutron stars, and former white dwarfs...

    >>so, the supermassive black holes in their centers, combined with the 

    >>total mass of the galaxies are pulled together through gravity, despite 

    >>the universal expansion. 

    That's true of a singular galactic cluster; maybe even a super cluster... but if the expansion of the universe continues in the manner we see - where clusters of galaxies are flying apart from each other - then, you'd have a grouping of black holes (or, maybe one, supergiant supermassive black hole) flying away from other groupings of black holes...

    >>will one day the black holes consume everything in existence then eventually 

    >>fall together to form a single titanic supermassive black hole?

    I don't know about a *single* one... but maybe millions or billions of supermassive ones... Maybe. 

  • 1 month ago

    Black holes eventually do evaporate.

  • 2 months ago

    No one knows, but many current hypotheses say no.the expansion of the space in the Universe is accelerating. 

  • neb
    Lv 7
    2 months ago

    You have a serious misunderstanding of black holes. Black holes evaporate through Hawking radiation. Black holes will eventually evaporate and disappear. 

    Whether the universe will collapse - or not - depends on the critical matter/energy density of the universe as well as the effects of dark energy. Dark energy increases as the universe expands keeping a constant energy density in the new space created by expansion. This means that dark energy will increasing dominate over normal matter/energy since the universe is increasing in size. Dark energy generates a negative pressure which per general relativity acts gravitationally to expand the universe.

    So, if dark energy does in fact exist, then the universe will expand to maximum entropy. There is always the possibility of some sort of phase transition such as a transition to a lower energy vacuum that might halt expansion but that’s purely speculative.

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  • 2 months ago

    Totally unknown.

    I would go so far as to say there are not even theories on the subject. Only speculation any hypotheses, most of which is more of the amusing variety rather than edifying.

    We are dealing with something that is way beyond anything we can currently measure, observe or predict. IMAO time is running out, science and technology relevant to the question has peaked, and we will never know the answer to this question.

    Fortunately there are other questions in astronomy that we can ask which can plausibly be answered, and there are other fields of science and technology for enquiring minds to pursue.

  • cosmo
    Lv 7
    2 months ago

    Given that we understand neither Dark Energy or Dark Matter, it is clear that we really don't know enough physics to answer your question in any definitive way at the present time.

  • 2 months ago

    I think you may be misunderstanding the concept of the Cosmic expansion. The current theory is that the various galaxies are not moving away from each other in a velocity sense, i.e. they are not traveling *through* space. The various galaxies are said to be "at rest" with respect to each other. Instead, what is expanding is space itself. This stretching of space does put more and more distance between galaxies as time goes on, but this is not a velocity in the strictest sense, i.e space is not being traversed. Likewise, the stretching of space over time causes light waves to be stretched redder and redder. But calling this a "Doppler" effect is wrong, and a misnomer, since there is no true velocity at play. 

    So you must ask yourself, if it is space itself that is expanding, how would gravity interact with space? Could gravity cause space to stop expanding? Maybe gravity could cause a true velocity that more than counterbalances and compensates for the otherwise expanding space? It is fun to think about. 

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