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Why is the Andromeda Galaxy moving towards us if the universe is expanding? originally appeared on Quora: the place to gain and share knowledge, empowering people to learn from others and better understand the world.
Answer by Viktor T. Toth, IT pro, part-time physicist, on Quora:
The universe is expanding.
The Local Group of galaxies is not. It is a gravitationally bound structure.
Let me explain.
The early universe was filled pretty much uniformly with gas that was expanding everywhere. However, it had small “density perturbations”: In some places, it was a little denser, in some places it was a little less dense.
Wherever it was denser, it had more gravity. Gravity that was pulling it together. If the density was high enough, gravity was sufficient to overcome the expansion: those bits of matter stopped flying apart and instead, ended up in gravitationally bound structures.
These structures are the largest gravitationally bound structures today, clusters of galaxies such as the Local Group, to which Andromeda and the Milky Way both belong.
So clusters of galaxies do not individually expand, but clusters of galaxies do still fly apart from each other everywhere.
Having said that, there is also a degree of randomness involved. Take the Virgo cluster, for instance. It is a cluster of galaxies some 50–60 million light years from here, moving away from us at nearly a thousand kilometers per second. But within that cluster, galaxies move about rather rapidly, in chaotic orbits in their mutual gravitational field. So there is M86, for instance, a member of the Virgo cluster that happens to be moving toward the Milky Way at the moment. It is still gravitationally bound within Virgo, and a few billion years from now, it will be receding from us just as rapidly as it is in a different segment of its trajectory within Virgo.
To make sense of it, imagine that you are looking at a child on a merry-go-round. Say you are slowly backing away from the merry-go-round, so the distance between you and the merry-go-round steadily increases. But if the merry-go-round spins fast enough, for every half revolution the child may actually be approaching you. Yet the child is still bound to the merry-go-round and, averaged over several revolutions, the distance between you and the child will continue to increase.
This question originally appeared on Quora – the place to gain and share knowledge, empowering people to learn from others and better understand the world. You can follow Quora on Twitter, Facebook, and Google+. More questions:
- Big Bang Cosmology: The Big Bang is still a theory, so why is everyone so certain of the age of the universe?
- Physics: How can the sun have gravitational pull on all the other planets if it’s not even solid?
- Time: Since scientists have discovered how to make a black hole. Does this mean they can now figure out a way to slow or even stop time?
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(************ ) Why is the Andromeda Galaxy moving towards us if deep space is broadening? initially appeared on Quora:(*************
) the location to acquire and share understanding, empowering individuals to gain from others and much better comprehend the world(***************** ).
(****************** ) Response(***************
) by Viktor T. Toth(*************** ), IT pro, part-time physicist, on Quora:(*********** )
Deep space is broadening.
The Resident Group of galaxies is not. It is a gravitationally bound structure.(*********** )(************ )
Let me discuss.
(********************** )The early universe was filled basically evenly with gas that was broadening all over. Nevertheless, it had little “density perturbations”: In some locations, it was a little denser
, in some locations it was a little less thick.
Wherever it was denser, it had more gravity. Gravity that was pulling it together. If the density was high enough, gravity sufficed to conquer the growth: those littles matter stopped flying apart and rather, wound up in gravitationally bound structures.
These structures are the biggest gravitationally bound structures today, clusters of galaxies such as the Resident Group, to which Andromeda and the Galaxy both belong.
So clusters of galaxies do not separately broaden, however clusters of galaxies do still fly apart from each other all over.
Having stated that, there is likewise a degree of randomness included. Take the Virgo cluster, for example. It is a cluster of galaxies some 50–60 million light years from here, moving far from us at almost a thousand kilometers per second. However within that cluster, galaxies move about rather quickly, in disorderly orbits in their shared gravitational field. So there is M86, for example, a member of the Virgo cluster that occurs to be approaching the Galaxy at the minute. It is still gravitationally bound within Virgo, and a couple of billion years from now, it will be declining from us simply as quickly as it remains in a various sector of its trajectory within Virgo.
To understand it, think of that you are taking a look at a kid on a merry-go-round. State you are gradually retreating from the merry-go-round, so the range in between you and the merry-go-round progressively increases. However if the merry-go-round spins quick enough, for each half transformation the kid might in fact be approaching you. Yet the kid is still bound to the merry-go-round and, balanced over numerous transformations, the range in between you and the kid will continue to increase.
This concern initially appeared on Quora – the location to acquire and share understanding, empowering individuals to gain from others and much better comprehend the world. You can follow Quora on Twitter, Facebook, and Google+ More concerns:
- Huge Bang Cosmology : The Huge Bang is still a theory, so why is everybody so particular of the age of deep space?
- Physics : How can the sun have gravitational pull on all the other worlds if it’s not even strong?
- Time : Considering that researchers have actually found how to make a great void.
Does this mean they can now determine a method to slow or perhaps stop time?
” readability =”60 950240219629″ >
Why is the Andromeda Galaxy moving towards us if deep space is broadening? initially appeared on Quora : the location to acquire and share understanding, empowering individuals to gain from others and much better comprehend the world
.
Response by Viktor T. Toth , IT pro, part-time physicist, on Quora :
Deep space is broadening.
The Resident Group of galaxies is not. It is a gravitationally bound structure.
Let me discuss.
The early universe was filled basically evenly with gas that was broadening all over. Nevertheless, it had little “density perturbations”: In some locations, it was a little denser, in some locations it was a little less thick.
Wherever it was denser, it had more gravity. Gravity that was pulling it together. If the density was high enough, gravity sufficed to conquer the growth: those littles matter stopped flying apart and rather, wound up in gravitationally bound structures.
These structures are the biggest gravitationally bound structures today, clusters of galaxies such as the Resident Group, to which Andromeda and the Galaxy both belong.
So clusters of galaxies do not separately broaden, however clusters of galaxies do still fly apart from each other all over.
Having stated that, there is likewise a degree of randomness included. Take the Virgo cluster, for example. It is a cluster of galaxies some 50– 60 million light years from here, moving far from us at almost a thousand kilometers per second. However within that cluster, galaxies move about rather quickly, in disorderly orbits in their shared gravitational field. So there is M 86, for example, a member of the Virgo cluster that occurs to be approaching the Galaxy at the minute. It is still gravitationally bound within Virgo, and a couple of billion years from now, it will be declining from us simply as quickly as it remains in a various sector of its trajectory within Virgo.
To understand it, think of that you are taking a look at a kid on a merry-go-round. State you are gradually retreating from the merry-go-round, so the range in between you and the merry-go-round progressively increases. However if the merry-go-round spins quick enough, for each half transformation the kid might in fact be approaching you. Yet the kid is still bound to the merry-go-round and, balanced over numerous transformations, the range in between you and the kid will continue to increase.
This concern initially appeared on Quora – the location to acquire and share understanding, empowering individuals to gain from others and much better comprehend the world. You can follow Quora on Twitter , Facebook , and Google + More concerns:
.
