Cosmic Expansion... with Hubbles observations of cosmic expansion in mind, how is it that some galaxies are moving towards each other?

2017-09-03 10:50 pm
更新1:

..and thereby seemingly NOT emanating from a central point (Big Bang Theory)

回答 (7)

2017-09-04 9:49 pm
✔ 最佳答案
Its called gravity, or basically two masses moving away from a central point can still converge at a point provided that point is still moving away from that central point.
2017-09-03 11:03 pm
Gravity is a function of mass. Galaxies have mass ... lots of it. It seems reasonable they might attract each other while still generally expanding outwards.
2017-09-03 11:53 pm
It's galactic *clusters* that move apart from each other. Within those clusters, galaxies are gravitationally bound to each other - and orbit a common center of gravity. Occasionally, two or more galaxies *do* move toward each other (like the Milky Way and Andromeda galaxies)...
2017-09-04 3:13 am
Galaxies are present in local groups too. And the groups are present in clusters (many local groups together).So it's those galaxies in the local groups that tend to attract each other, while the cluster they are in is expanding along with the others.
Our Milky Way, besides being in a local group consisting of about 55 dwarf galaxies, is also neighbor to the bigger Andromeda. In fact, Andromeda and our Galaxy are gradually coming closer to meet and absorb one another in the far future.
So to summarize, galaxies in local groups attract each other by gravity, while the clusters they are in are swarming outwards.
2017-09-03 11:09 pm
ahhh .. GRAVITY / MASS .. overlooking the obvious thank you... and i assume then we do have evidence of galaxies colliding?
2017-09-08 2:58 am
Basically Galaxies are floating in the fluid of space.If the containment of the universes is deemed to be near spherical,it would mean that Galaxies are moving in different latitude and latitudes are parallels.Hence the Universe can be analyzed in terms of buoyancy of celestial bodies in a permeating celestial fluid.
2017-09-04 3:23 am
I think it would be odder if they weren't.


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