Big Bang Question Please

[Grendelyn]

If our universe is indeed expanding and all telescopic light that we see is supposedly red shifted, how is it possible for our Milky Way Galaxy to be on a collision course with the Andromeda Galaxy that should be moving away from us if the Big Bang Theory is correct? Andromeda must be emitting blue shifted light to us, does it not? And finally please, I'm confused when we speak of red and blue shifted light . . . can I assume this is refracted light through a prism of some sort?

I'm hoping you intelligent ones out there will show a little mercy on me by not making too much fun of what in all likelihood is probably an easy question to answer. I should have been paying more attention in my high school science classes rather than thinking about the opposite sex . . . however, it's never to late to learn and am hoping, too, that those that truly have intelligence will take the view that no question is a dumb question. Thank you. ~ Susan

 

[JakeStarkey]

Great question.

 

[TheOldSchool]

Not all of the light we see is red shifted. There have been an infinite number of collisions that have happened since the since the big bang. Those collisions happened because of the ways that various forces interact with each other attracting and repelling matter. That happens on a galactic level too. So I think that's the simplest explanation to your question.

The reason we know the universe is expanding is because while we are on a collision course with Andromeda, nearly every other galaxy that we've observed shows the red shift you are referring to. There are a couple of galaxies moving closer to us but every other galaxy we've observed (well over 99% of those discovered) is moving away from us. And we've discovered millions of galaxies.

 

[Coloradomtnman]

It isn't that all galaxies are moving away from eachother, it is that the actual fabric of space is expanding. Because space is expanding at such an infinitesimal rate that the expansion is negligible the relatively tiny human scales that we perceive in our personal experiences; however, when one takes into account the galactic scale of space, it becomes more noticeable. The interesting thing about this is that at some point in the distant future, the most distant objects in the universe, as they move away from us, and as the fabric of space expands, will disappear from sight because the inconceivable lengths of space between us will expand, cumulatively and virtually, faster than the speed of light.

Red or blue shifted light has to do with the Doppler effect: light emitted from an object moving away from the viewer has elongated waves which shifts the light closer to the red end of the light spectrum. The opposite end of the spectrum is ultraviolet, so an object moving toward the viewer would emit light with shorter wavelengths which would shift the light to blue end of the spectrum. That's not a very good description of the phenomenon, but it isn't easy to fully descibe while avoiding a wall of text.

Think of the sound of a car as it nears you: the sound seems to get higher in pitch as the sound waves shorten, but as it passes the sound waves lengthen and the sound of the car grows deeper in pitch. That is an example the Doppler effect.

 

[Steven_R]

We need to remember that galaxies aren't uniformly distributed or evenly sized. The Milky Way and Andromeda are just two galaxies in our local galactic cluster. The Milky Way has about 300 billion stars while Andromeda has a trillion but the Milky Way as about twice the mass. Some galaxies are clustered together, some are isolated. It just so happens that in the Local Galactic Cluster, the Milky Way and Andromeda are close enough to affect each other.

 

[CrusaderFrank]

All that assumes that the speed of light has remained constant since the start of the Universe

 

[Coloradomtnman]

All that assumes that the speed of light has remained constant since the start of the Universe

Were the speed of light not constant, it would affect the ratio of energy to mass in every system which would have so greatly changed the forming of everything, from galaxies to atoms, that chaotic, high-energy "soup" is all that would be. It is an unreasonable assumption to believe the speed of light is not constant, or that it varies more than infinitesimally.

 

[Coloradomtnman]

Bump

 

[Grendelyn]

I wish to thank everyone making a response to this subject . . . your input is very much appreciated. Although I'm an atheist, I did take the biblical advice 'to seek and ye shall find' and believe I did come up with a solution to my question. The answer seems to lie in the fact that galaxies cluster (which I had no idea that they do . . . . duhhhh) such as with our own Milky Way Galaxy clustering with several others, the largest being Andromeda, next, as mentioned, our own Milky Way, then Messier 33, followed by a multitude of dwarves. Due to gravitational pull, these cluster galaxies circle each other and because their density is high, collisions such as that predicted with Andromeda can occur. If anyone is interested, I link below a video on cluster galaxies that I enjoyed viewing. Thank you all again. ~ Susan
PS Realizing how vast space actually is, makes one feel soooo insignificant, does it not (?) . . . relatively speaking, considering that our lives are so short it makes one wonder, too, just why we fight and kill each other for what seems to be no reason at all, particularly killing each other for the sake of mythical religions which, in my view, all of them are.

 

[Steven_R]

PS Realizing how vast space actually is, makes one feel soooo insignificant, does it not (?) . . .

"Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."
--- Douglas Adams, The Hitchhiker's Guide to the Galaxy

Rather than feeling so small and insignificant, I feel lucky to be a part of the whole thing and take comfort in knowing that the atoms and molecules and electrons and whatnot that make up my physical being will always exist and will always be a part of the universe (at least until proton decay sets in.. It's a kind of an immortality.

 

[Grendelyn]

PS Realizing how vast space actually is, makes one feel soooo insignificant, does it not (?) . . .

"Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."
--- Douglas Adams, The Hitchhiker's Guide to the Galaxy

Rather than feeling so small and insignificant, I feel lucky to be a part of the whole thing and take comfort in knowing that the atoms and molecules and electrons and whatnot that make up my physical being will always exist and will always be a part of the universe (at least until proton decay sets in.. It's a kind of an immortality.

Yes it is, but unfortunately it's not a living immortality . . . thank you for your response. ~ Susan

 

[Grendelyn]

PS Realizing how vast space actually is, makes one feel soooo insignificant, does it not (?) . . .

"Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."
--- Douglas Adams, The Hitchhiker's Guide to the Galaxy

Rather than feeling so small and insignificant, I feel lucky to be a part of the whole thing and take comfort in knowing that the atoms and molecules and electrons and whatnot that make up my physical being will always exist and will always be a part of the universe (at least until proton decay sets in.. It's a kind of an immortality.

Yes it is, but unfortunately it's not a living immortality . . . thank you for your response. ~ Susan

Rats, Steven . . . I forgot to put my 'punch line' video in my response to you ~ Susan