we know that stars which orbit black holes and some stars float in space . but what makes galaxies to be safe in space, i heard some kind of dark energy or black mandir line which guides the galaxies in universe, i want to know the exact how galaxies floating in universe is galaxies orbiting anything and that orbiting may be invisible to us.
2011-04-05T08:17:14Z
if you say galaxies not orbiting anything means how galaxies guide or its just floating in universe. dark energy is not explained well by any scientists
Daryl S2011-04-05T08:04:33Z
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Galaxies like all other objects in space, exist in the fabric of space/time. Gravity is what holds galaxies together and it is theorized that dark matter plays a big part of this. Galaxies are still moving through the universe as it continues to expand (dark energy is believed to be behind the expansion of the universe). However, galaxies do not "orbit" anything.
<EDIT> As I said, galaxies aren't out there "floating". They are MOVING at incredible speeds with the expansion of the universe. But they DO NOT orbit anything. I think you are being thrown by the optical illusion that they seem to stand still or "float." They don't. An "orbit" indicates movement around a central point. There is no such point in the universe that galaxies move around. An example is the Andromeda Galaxy moving at about 120 kilometers per second. http://www.scientificamerican.com/article.cfm?id=when-milky-way-and-andromeda-collide-earth-could-find-itself-far-from-home
Galaxies exist because of gravity. Masses of stars, gas, and dust, if given enough time, will condense into a cloud; that cloud will, eventually, flatten out into what we see as a galaxy. (Some irregular galaxies don't have the matter needed to accomplish this.) Most galaxies are part of 'groups' - like the Milkyway is one of two major galaxies in what we call the 'local group' - bound together by gravity, they are moving in the same general direction and speed. Other groups of galaxies are moving away from us; the further they are away, the faster they're moving - like fragments from a bomb. That's the evidence of the Big Bang. As time moves forward, the distance between these groups of galaxies increases; if there's enough matter in the universe, this expansion will stop, and they'll all fall back together. If there's NOT enough matter in the universe, expansion will continue, forever. Recently - in the last 10 or 15 years - scientists had thought that the expansion should be slowing, due to gravity. However, what the measurements show - expansion is actually speeding up... they have no idea why or what's causing it. This is what is called "Dark Energy" - some force or energy that is *increasing* the rate of expansion - even over the gravitational pull of all the matter in the universe.
Galaxies are not "floating in space" as rubber balloon in the atmosphere, it may sink at bottom some day. There is no top no bottom no up no down in the universe. No floating no sinking.
"Floating" word is used on the earth to give a sense of going away from surface of earth into atmosphere, the "floating object" may return back [sinking back] on the surface after some time due to gravitational pull of the earth.
The infinite universe is expanding into infinite space , constantly, uniformly, regularly in all possible directions to avoid colliding or collapsing.
All the galaxies are rotating on its axis as well as they are orbiting round the center of the universe giving appearance of expanded and rotating universe.
Galaxies "float" because there isnt any gravity that makes them fall towards something. Gravity is what keeps everything held together. Galaxies dont orbit anything.
Most scientists believe that galaxies are still travelling in the direction that they were ejected from the "Big Bang" and that only the influence of gravity from other galaxies or the mysterious dark matter has changed their trajectories.