If the universe is constantly expanding, will it ever stop?

Current theory

Spacetime is unfolding into quantum emptiness. Within our spacetime envelope the vaccuum of space is not a completely empty space - about 3 molecules of atomic hydrogen exists per cubic metre, plus photons plus virual particles pairs pop into and out of existence as fast as 10 ^ -35 of a second - lasting only billionths of a billionth of a second.

This last factor means space has a non zero energy and mass - and by its position most space is away from the centre of universe so its centre of gravity is away from the centre of balance - meaning this is pulling space apart at every increasing rates. This is called qunitenssence.

Remember gravity by our best theories (Einstein) isn't mysterious graviton partilces - its the actual warping of spacetime itself by mass.

Space tells matter how to move, whilst matter tells space how to warp.

We don't theoretically understand what exists outside the envelope of our Universe.

At present observation indicates the Universe exploded, slowed its expansion due to gravity, then is accelerating again faster now then before.

So if current indications are correct and the last step in a steady state (unknown) - the Universe will strech into nothingness forever becomming very, very diluted.

truth
As I understand it, when everything was condensed into the speck that eventually exploded as the Big Bang. That speck was not surrounded by space. When the Big Bang occured and spread out, it involved the spreading of space as well, not just objects spreading in space. I find this ungraspable. But I don't have to grasp it for it to have occurred.

Correct theoretical understanding. Space unfolded where there weren't these dimensions before. If spacetime where already present and then the singularity that was the pre-big bang entity tunnelled through into our reality it would be expected to implode not explode! This model assumes that a Higgs field (i.e. gravity) exists and takes effect before the singularity can rip itself apart. For the big bang them Higgs field is part of our universes reality so until the big bang went bang the Higgs bosons weren't outside the singularity preventing it from exploding. Difficult concepts - especially when you realise that the event horizon of a singularity of a black hole with energy/mass = our universe would have a diameter larger than our Universe has reached through expansion today (10 ^ 30 metres vs estimated boundardy of the Universe = 40 billion light years or 4 * 10 ^27 metres)!

We have minimal models of what was before spacetime - because we have no way of observing it - and our knowledge of what sub-atomic particles is incomplete. We know certain things these particles can do - we may not know everything these particles can do.

For all we know our whole universe may just be the boundary between two or more other universes with different dimensions/characteristics and things might leak to an from our universe into other realities.

We have a long way to go still I think.

truth
g___day. VERY interesting. Thanks.

I think space and time are psychological, which of course raises the question: If that were so how is it that the objective universe existed billions of years ago? But then we don't know. If existence is dependent on observation and we are ignorant about that which observes we simply lack any knowledge to answer the question.

Self ignorance is universe ignorance.

I think the mathematics of theoretical physics is extremely hairy.

One has to propose particles and forces an pass so many observational based tests - e.g. guage bosons http://www.innerx.net/personal/tsmith/See.html

Its like reading Greek!

Maybe in 2006 / 2007 with the LHC at CERN we might get new data to advance our theories.

Physics is wonderful to bad that its language (math) is evil just kidding, just difficult.

Anyways about this ever expanding universe, balloon, or the dissipation of matter/energy debate. The first theory i read about the universe's 'end' was that the universe is umm heh "inside" a cone which is connected to another cone the openings facing.. kind of like this

/\
\/

so the 'big bang' happened at one point and the 'next one' will happen when the universe retracts into itself because the cone will force it to.. it was a theory attempting to actually give a definite answer to something we cannot grasp ( I believe ) because it is above our 3rd dimensional grasp. hell look at thee '4th' dimension we can barely observe 'time' and cannot accurately measure it (as we measure it, it disappears) and the universe on a whole seems to me to be on at least the 5th dimension because there have been experiments which have been altered by that which 'disappeared'

these virtual particles that dont violate the law of the conservation of energy yet appear then disappear. one person i read annotated this as being particles from another space/time or dimension.

Looking at what G_Day wrote about matter bending space time and space time telling matter where to go is very interesting. I've read it before in my pursuit of learning more about 'black holes' only to discover lol more questions about the 'fabric' of space-time. but yea will the universe expand forever? heh

to touch on what twyvel said and i mean no offense but lol.. you are speaking about the egocentric laws of the universe. does the universe exist for us to discover? does the 'grand unified theory' exist for us to discover? if the G.U.T. does exist then it would ditract weather or not we actually discover it.. so what if it dictates that we DO NOT discover it.. ya.. ever saying we lack the ability to discover something or saying that its 'meant' we don't discover something is blind.. if you wish to feel that way go ahead... i'd be happy to waste my life in the pursuit of the unachievable such as this. if it is actually 'above us' then we are working to be more than the sum of our parts and im happy with that.

Re: If the universe is constantly expanding, will it ever st
Icaras:

<<<It is apparent to some scientists that our universe is forever increasing in its size, and this can be determined by looking out into space, im led to believe.

However, logically, it can not carry on doing this forever. It seems inconceivable that something can always move into more space. Surely, there will be a time whereby it has to stop. will it just meet the other end of the universe, and collide, perhaps ending everything that is contained within it?

im puzzled, and thoughts would be helpful>>>


When you consider primordial questions THAT big, human logic itself implodes into the philosophical equivalent of a black hole. The mystery is so inherently profound down inside there that rational thought itself can never come up out of it. In other words, asking if an ever expanding universe will ever stop is as pointless as asking if an ever expanding philosophical quest to answer it will.

In philosophy, Kant and many others pointed out questions like that are called antinomies. You can agrue equally persuasively from both sides of the coin. But no one ever resolves it once and for all. How could they?

RP

Re: If the universe is constantly expanding, will it ever st


in one theory i mentioned is the 'balloon theory' and it can be observed by look at the commonly refered to 'red shift observation' of distant objects. using that observation it looks as if all the universe is uniformly expanding like if you used a marker to put a bunch of points on a perfect 'sphere baloon' (being blown up from transporting air into the middle of it rather than it having a blow hole) using this thory the dots on the balloon's surface would expand till the baloon popped then it would cave in on its self perhaps or space time would act like the fabric of the balloon and just rip apart.. end of existance or just of this universe. or the space time would 'bounce' at one point and pull the universe back in with a force tocreate an inward motion which would overcome the 'expansion motion' caused by the big bang. or the elastisity of space time would simply run out and the expansion caused by the big bang would simply push matter/energy so far appart that the net energy of the universe would reach 0 and it'd lie stagnant... relative to what? to its current state.

The theories have to develop. We have several contenders:

1. Loop Quantum gravity - more like big bang / big crashes where each rebound creates a new universe, time can go negative but volume and area swap dimensions for a while and so does left and right permanently!

2. String theory - doesn't really know what space is

3. Membrane Theory - diffuse to all hell until we collide with another reality and dissappear

4. Relativity - looks like 3) but we fade away

And then again something else or a new force could come into effect once the Universe reaches a certain size - who knows.