If black holes are at the center of the galaxy, how is the universe expanding?

Question

?????? i understand that their mass sorta hold the galaxy on its orbit, but if so, is it pulling everything in, even though we its not noticeable, should the galaxy really be falling inside, unlike the popular claim that the universe is expanding?

Answer 1

For material to fall into a black hole it has to be close to the black hole, close enough to cross the "event horizon".

For starters, a black hole isn't really a hole at all. It's a high mass star that has ended it's stellar life cycle by exploding as a supernova. The black hole is just the remnant stellar core, and it's very dense and tightly packed with matter. So dense, in fact, that it has incredible gravity.
This gravity is so strong that nothing, even light, can escape. That's why it's called a black hole; because it can't be "seen". We have other ways of detecting them, of course.

The event horizon is just a name given to the point in space where the black hole's gravity becomes inescapable.

I hope this helps.

Answer 2

If a black hole could exist and they resided at galactic centers,eventually it would consume all the matter in the galaxy and continue to expand as if nothing had happened.
If the universe is finite [which it likely is] the black holes would some how have to be gotten rid of.
The universe would eventually become invisible as all light emission would,in time, stop.
Probably a galaxy is an end stage in the evolution of the universe and as the stars migrate towards the galactic center
they merge into a neutron density type matter which drives the annihilation of matter,reduces the density of space causing the galaxy to collapse at an accelerated rate towards the center.

Answer 3

A black hole is simply a 'special' form of mass. As far as mechanics are concerned, its effect is the same as any mass.

For example, if we were to replace the Sun with a black hole that has the same mass as the Sun, the orbits of the planets would not change (the force holding the planets in their orbits depends on the mass and distance to the central object).

Of course, because nothing can leave a black hole (e.g., light, heat), life on Earth would suddenly become dark and cold. But we would not be 'sucked in' the black hole any more than we are into the Sun (and we are not), simply because the 'sucking in' force depends on the mass, not on the form of the mass.

So, whether the mass of each galaxy is made up of gas, stars, black holes or dark matter, it changes nothing to the manner in which each galaxy affects itself and the rest of the universe. (It does affect the quantity and nature of the light it emits, but that is something else).

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Each individual galaxy is microscopic compared to the universe and its expansion. The total mass of all the galaxies (recently re-estimated with greater precision by WMAP -- a probe) is far from sufficient to stop the expansion.

In addition, there maybe something we understand even less -- dark energy -- that makes expansion go even faster.

The expansion of the universe is not a mere "popular claim". It has been (and can still be) observed and measured. It is an established fact.

What is less established is the reason why. It may take years to understand.

Answer 4

A galaxy may have billion stars. The universe may have trillions galaxies.
Surely all the large galaxies have a massive black hole at the center.
As the galaxies rotates, the centrifugal force stabilizes the stars from a collapse.
The Universe is expanding because the distance between the galaxies is increasing. As the universe not rotates, only that expansion can stabilizes the galaxies from a big collapse.

Answer 5

I think you're confusing the galaxy with the universe... a galaxy is a collection of stars. In our galaxy, the milkyway, our sun is only 1 of about 400 billion other stars orbiting the center.

The universe, on the other hand, is what our galaxy is in. It stretches for billions of light years, whereas our galaxy is 'only' 100,000 light years across. The universe is expanding - the distance between our galaxy and other galaxies is growing greater.

The black hole at the center of our galaxy does, occasoinally, pull other stars & debris inside; but, like the moon orbiting Earth, as long as a star keeps it's distance - the black hole can't get it.

Answer 6

yet another, black hollow on the middle of the universe? No, there is not any black hollow in the middle of the universe. you are able to desire to have observed the enormous merchandise in the middle of the image voltaic structures and the galaxy. enormous gadgets make different bodies circle it. for this reason, the image voltaic structures orbit the black hollow on the middle of the galaxy. whether, the universe, isn't orbiting a black hollow because of the fact it would not have a center. If there replace right into a black hollow in the midst of the universe, it would not have the skill to seize all the mass in the universe because of the fact the gravity decreases with the gap. So, for a gravitational field to hide the entire universe, it might opt to be enormous. greater enormous than a black hollow.

Answer 7

"Galaxy" and "Universe" are two separate things.

As for the non-collapse of a galaxy, it is the same as the non-collapse of a solar system. The Sun has great gravity, but the Earth does not fall into it because it is in an orbit. It is being pulled in, and that pulling it on its tangential velocity make it orbit rather than falling in or flying away, much like the action of the string if you swing a weight tied to a string in a circle over your head.

Answer 8

Easy - the force of gravity is quite weak. Whatever is driving the expansion of the Universe is stronger.

There are many millions of galaxies. Most of them are moving apart from each other. Over short distances, that is up to a few million light years, gravity tends to keep some together in groups and some collide or merge. These groups are called clusters or super-clusters.

Answer 9

You've gotten a lot of complicated answers, but let me see if I can simplify everything for you. When you think of the universe expanding think of its *space* expanding...and we're talking immense volumes of space. Space that's close to a black hole --- even a super-massive black hole --- 'feels' the effects, but as you move outward from the black hole its effects decrease rapidly. As little as 5 light years from the super-massive black hole objects in space are well outside the zone from which they can't escape. Now think about some 13.7-billion light years of space and you can see that the effects of black holes scattered throughout that volume of space have no noticeable *overall* effect on universal expansion.

Answer 10

Additionally, some scientists believe that the gravity at the center of the universe will eventually overcome the intertia of the stars and planets and the universe will stop expanding and eventually be sucked back into the center and things will start over with another big bang (or Horrendous Space Kablooee!)