Jay

I agree. also when you bring in black holes in to the equation, at some point of time, the whole of universe would be chewed off by one mega black hole, which may result in another big-bang type of explosion..may be I'm hallucinating.

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Officer of Engineers

That's where your misunderstanding is. There is no space outside the universe. Space is defined within the universe. Space itself is curved. That is to say, you cannot travel outside the universe. You go in a straight line long enough, you'll end back right back where you started from (assuming everything stays still). So, space is expanding and by extension, the universe is expanding.

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Jay

Sir,
If there is no space outside the universe then certainly you cannot travel outside of it. I agree, but still I dont get the point that space and universe can expand.

Officer of Engineers

We cannot see outside the universe. Therefore, we don't know what's there. All we have is evidence within the universe and the evidence within the universe tells us space is expanding.

Jay

may be is it something like we are expanding on one side and contracting on the other, like a blob on pressure??

Sombra

Well that is our problem because we live only in our 3 dimensions. If we could perceive another dimension like time perhaps it would make more sense.

Stephen Hawking put the problem into an analogy: Imagine yourself the dots and lines in the piece of paper in front of you are in reality people, building etc. a whole world. In this world the people knows 2 dimensions width and length. They don’t know what the third dimension is, their world is flat. You can only move forward, backwards, to the left, to the right but not up.
Imagine know these poor people live on a globe and they notice a strange thing if you move long enough forward in a straight line somehow you get back where you started. Perhaps they have an A.Einstein who explains to them that there is something more to the world that it isn´t flat but has another dimension, some physics can describe the problem but still it would be mostly something the people in flatland would not be able to really understand.

This is more or less what happens to us. As Officer of Engineers explained the universe is like an ever expanding bubble and we are living on the surface of this bubble which is our 3 dimensional universe, the fourth dimension would be the diameter of the globe or the inside. If we move fast enough in a straight line and the universe would be frozen in place we would end up where we started.

Bulgaroctonus

Albert Einstein believed in an expanding universe, and I will defer to him on matters of theoretical physics. The evidence for an expanding universe is plentiful. For example, almost all galaxies exhibit the red shift optic phenomenon that indicates that those galaxies are moving away from Earth.

At least we can agree that evolution does not violate the laws of thermodynamics.

Let this good cosmological conversation continue.

Anon

Your observation and statement is hopelessly flawed because we simply DON'T KNOW what exists outside the boundries of our universe, and yes, it IS expanding- well, if Stephen Hawking can be believed it is.

Ballguy

He is the smartest man in the world, is he not?

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Praxus

If something exists, it is exists as a part of the Universe.

Praxus

Look what your saying. Your talking about Galaxies moving away from each other. That is substantially different from suggesting that the Universe- the totality of existence- is expanding. Where, may I ask, is it expanding to?

Jay

Err...All the galaxies would move "away" from earth, if Earth is say at one corner of the Milky way and Milky way is in the farthest corner of Universe.

But we all know thats not the case. I would go with Dalem's explanation, different galaxies exhibit different properties and for the direction part some may move away, some may move towards Milky way, remember Milky way is also shifting in its own speed.

dalem

I will grant you that we are discussing a mathematical concept in words and that that can cause confusion, but 75 years of cosmology and physics back my position up, and nothing backs yours up. So you are wrong, and the universe is expanding.

-dale

Bulgaroctonus

I don't fully understand your point. However, it has been said that most galaxies are all expanding from each other. That is, even an observer in another universe would see all the galaxies (unless there were local attractions) expanding away from him. This leads to the trick question,

"What is the center of the universe?"

"Everywhere."

At least that is what a very intelligent friend of mine said.

Bulgaroctonus

I need to think more on this.

There's the rub. I really don't know. I'll do some reading and thinking and get back to you on that.

It might be expanding into nothingness, quite simply. It is hard to visualize though.

I think very few humans, and probably no one on this board (no offense), have the necessary expertise in cosmology to speak with affirmation here.