The expanding Universe and Galactic collisions

I have a mediocre knowledge of geology, but you don't see me sharing my opinion that plate tectonic doesn't sit well with me. I have a mediocre knowledge of spinal surgery. Yet, I didn't say a word when my aunt had spinal surgery some weeks ago.So, you see, there are a lot of things in this world, and outside of this world, that we don't completely understand. This is why we have experts. You answered your own question with.. In logic, we would call your question the composition fallacy. An example is since the atom of a plant is colorless then we must assume that the plant is colorless. This is, of course, absurd.Just because 2 galaxies attract each other and collide doesn't mean that the universe as a whole isn't expanding. Don't know for the first question.For the second question, if the universe has enough mass for gravity to overcome the expansion, then it will ultimately end up in a big crunch. If the universal mass is below the critical point, then it will ultimately wither away with light years seperating each atom. If it's just the right mass, it could last forever.The better question is why are you worried about this right now? You still have tens of billions of years before you start to see any obvious signs of either doomsday scenario. You plan to live that long?

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

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He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

You're welcome. The reason I asked why you are worrying (or concern yourself) about this is because you seem to be lacking in the most basic knowledge of physics. My mentor used to tell me that in order to be an artist one must first learn how to use a paint brush. You simply can't understand the BB theory unless you first have to familiarize yourself with the basic stuff.Not only is the universe expanding, the rate of expansion is increasing. Astronomy currently doesn't have a clue as to why this is, and some are attributing this to dark energy, a very hypothetical form of energy that is responsible for the acceleration outward.Do you understand the implication of this? Some unknown force is driving the accelerated rate of expansion of the universe while a very well known force (gravity) is locally grouping objects together.Other than that, I don't know what to tell you.

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Disclaimer:

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

To be fair, let me explain a little further why I decided to dismantle your question rather than answer it directly. Consider the following question.If a plant is green, how come the plant's atoms are colorless?Can this question be answered directly? Sure, it can. But one can't really answer this question honestly without pointing out the obvious logical fallacy of division. Just because the plant is green doesn't necessarily mean its atoms are green. Trying to apply the behavior of the whole on the individual components is never a good idea. And neither is trying to apply the behavior of the individual components onto the whole system.My other main point in my first reply to you is that I really really really hope you will learn to refrain from having an opinion about everything. We live in an age where everyone seems to have an opinion on everything. Having been an educator and is now considering going back to it permanently, I've seen too many cases of students not agreeing with something as simple as gravity only to later show they know nothing about it. How on earth can you disagree with something you know little to nothing about? So, I guess my goal has always been to try to convince people that a little humility here and there wouldn't hurt. And by example, you will find that I hardly ever comment on geology. Even a middle schooler would know more about geology than I do.You don't have to agree with everything the experts say. In fact, you can disagree all you want. Just remember that you have the power to vote like everyone else. At least show the experts the courtesy of learning a little about the subject before having and sharing your opinion on it. (Otherwise, we'd get another Bush in the oval office in 2008.)

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Disclaimer:

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

Mind expanding on this a little more?

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Disclaimer:

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

Look up the idea of inflation as a modification to the BB. Well... I know you've heard this a million times before, so I guess one more time wouldn't hurt.You are thinking too 3-dimensionally. Imagine that the universe is 2-dimensional and that it exists solely on the surface of an expanding balloon. There are many dots on the surface of this balloon. As the balloon expands, these dots grow further apart from each other.If you were to ask where the center of this two dimensional universe is, noone can really give you an answer. There is no center. I know you are tempted to say the inside of the balloon is the center, but in this scenario you've wandered outside of the universe. Dark matter pretty much is a hypothetical form of matter that accounts for 2/3 of the total mass of the universe. It's probably non-baryonic in nature, but I guess we'll never know until we get ourselves some dark matter to analyze. Well, explosion isn't exactly the best way to describe what happenned at the beginning of time. Try to think of it more as an expansion of space-time from a single point. It wasn't so much as an explosion as simply a sudden expansion of space-time and matter. And yes, we could always improve on the current model Just remember that the BB made at least one very prominent prediction. It predicted the existence of a cosmic background radiation that should exist everywhere in the universe. And voila, we have detected exactly the cosmic background radiation predicted by the theory. So, I guess it's not perfect but it does explain a lot and have some very powerful predictive power.

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Disclaimer:

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

So many questions...We cannot speak of energy without matter and matter without energy. The two are interchangable. When cosmologists refer to dark energy, they are referring to the missing roughly 2/3 of the overall energy observed in the visible universe.Let's summarize how how all of these mumble jumbles came about. In the 20's and 30's, Fritz Zwicky painstakingly observed and calculated the revolution of the stars in relative of the galactic center. Now, remember that he had to do all of these without modern computers to do the calculations for him. Anyhow, what he found was that the galaxies were behaving more like a solid object than what the laws of gravity tell us.Imagine it this way. If you have a solid disk and you rotate it, every point on the disk would have the same angular velocity with each other. If you look at a planetary system like our solar system, you find that the farther out an object is from sol, the slower its angular velocity is. The stars of the galaxy, however, almost have the same angular velocity as each other. From what we know of gravity, the further the stars are from the galactic center the slower it should be travelling. In other words, there must be a hell of a lot more mass in the galaxy than what we can see, mainly the stars.Not counting the non-visible baryonic matter like MACHOs and WIMPs, there is still 2/3 of the total mass missing. Hence, we call it dark matter because we don't have a clue what it is.I believe it was in 1996 or 98 that 2 independent astro groups attempted to calculate the rate of expansion of the universe by tracing the rate of recession of certain super novas. They discovered that not only is the universe expanding, it is expanding at an accelerated speed.But hang on. We know of 4 fundamental forces in the universe. The strong nuclear force, the weak nuclear force, gravity, and electromagnetism. So, what's responsible for the accelerated rate of expansion? Is there another force we don't know about, some kind of repulsion force?The energy responsible for the outward acceleration is called dark energy because, like dark matter, we can observe what it does but we don't have a clue what the hell it is. At this point in time, we might as well attribute it to the tooth fairy.Now, it had been known for a very long time that if there was enough matter in the universe gravity will eventually win out and the universe will begin to contract. If, however, there isn't enough matter in the universe then the expansion will continue on forever. The discovery of accelerated rate of expansion pretty much told us what it's gonna be.PS - Jon, sometimes I wonder how you are able to pass your English classes. Your reading comprehension is sometimes impressively lacking.Added by edit.To add to what Rahvin was saying, if I were to explain the BB to you in a less popularized way, I'd have to fill this forum up with math equations. Even what we have explained to you so far doesn't even come close to how this info would be presented in physics 101 (let alone upper classmen level). Just remember this much. These theories didn't just come out of people's asses. We are oversimplifying whole lifetimes' work here.Edited by Taz, : No reason given.

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Disclaimer:

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

Because the universe is by definition all things and all wheres that obey the same natural laws that we observe. If you want to wander outside of the universe, go right ahead. Noone is going to stop you. In fact, I dare you to. Ask yourself this question. Can you at least conceptualize more than the 3-dimensional space you live in plus time? You are having trouble conceptualizing this stuff because, as the borg queen once said to Captain picard, "You think in such 3 dimensional term."

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Disclaimer:

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

No, it's a dimension. This is why we say space-time, not just space. Yes, because everything that we know of is bounded by space-time. Can you explain how you arrived at this? I'm having trouble following your logic.

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Disclaimer:

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Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

Now, you are wandering into a whole new realm of physics that is still in its infancy. The only people who have even attempted to answer this question are string theorists. Even then, only a hand full seem to be able to explain this without having their heads explode.Look, you can pick up some books to read about these things, you can even apply to one of your local colleges and take some classes, you can wait for science to progress further before getting some more layman explanations, or you can do what the creationists do and proclaim "goddunit". The choice is yours.My question to you is is the BB still not sitting well with you or are you ready to admit that you will need further research and study before having an opinion on it?

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Disclaimer:

​

Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

You misunderstand me.You seem like a reasonable person, so I am just trying to give you a nudge toward the right direction. And the right direction is recognizing one's own limits with regard to knowledge and refrain from being opinionated about that which one's own knowledge is lacking. You don't have to accept the BB. In academia, we often come face to face with things which are obvious to others but are not so obvious to us. If you decide further explore the wonderful world of science, sometimes you have to accept that you're not going to know everything.Just remember that my goal isn't to convince you to accept the BB, relativity, or whatnot. You can make up your own mind AFTER you've had sufficient knowledge.

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Disclaimer:

​

Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!

I think this is a problem that has been plaguing intellectuals and academics of all fields since the beginning of civilization. Forgive my bluntness, but the ordinary folks have always tried to pass themselves off as the "wisemen" by nitpicking the hell out of simplified versions of a specific field. This is also why scientists more often than not are made out to look like fools in a live debate situation.I once attended a lecture on how quantum computers work. This was a lecture intended for grad students and professors, so the lecturer went into some rather complicated math stuff. To be honest, I was able to follow him the first 20 minutes or so before he lost me. There were, of course, some physics enthusiasts who attended and at the end of the lecture some of them admitted that they were lost the moment the lecturer wrote the first equation on the board. See, at the time, I had taken several quantum mechanics class so I was able to follow the first 20 minutes or so until I started asking myself "how did he get from there to here?"Most of this stuff you just can't explain in plain english.The creationists have made it a popular idea that you could quantify/simplify all of the theories and all of the mathematical concepts down to mere english words. This certainly makes Mister Joe Smith with his high school diploma feel a lot better about himself...

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Disclaimer:

​

Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

​

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!