Does Dark Energy Exist?

[I_Hate_Infinity]

I know this is a topic still in the realms of theory and we have little data but would my debate my opinion of an external force creating the expansion we see?

Is dark energy really an anit-gravitational force, pushing the Universe outwards? Or is it that the Universe is expanding into a vacuum that is sucking space outwards to fill the void?

What makes us conclude it is an internal force/process acting on space-time to expand it in all directions, instead of an external imbalance that nature is trying to equal out?

An external vacuum should also create the condition of an accelerating, expending Universe that we see, right? If the opposite is true and there is an internal source of repulsive energy, what do we know about it that makes it real? Is 'dark energy' just a label for a the conflicting data from theory (rate of expansion from big bang with only gravity as the pervasive force acting on space-time) and the observed physics (of an expanding universe which is increasing in speed) which makes us believe another force is at work here...

I believe we've allocated about 78% of the constitution of the Universe to Dark Energy, 18% to Dark Matter and 4% to Matter (please correct)

I'd like to here your thoughts on this.

Infinity

[wildwood]

I've got a headache just reading your question, let alone trying to answer it.

[Teddio]

Imagine an infinite void
Into that void place a stationary Earth-sized bomb
The bomb explodes throwing material in all directions, the sum of all the momenta equalling zero.
Using Newton's laws of gravitation it is possible to predict the expansion of the debris.
Now suppose the expansion is greater than that predicted by Newton (neglecting any relativistic effects). Then we have to envisage some kind of pushing force. This, as I understand it, is Dark Energy.

[annieigma]

Teddio,
Is that theory going to stand if objects from the explosion are of different sizes,would the larger particles push the host object away towards the smaller particles? would the law of gravity still stand? or would there be no back pressure as it is in a void? I can not get my head round the big bang theory, as I need someone to explain how nothing suddenly went bang and created a universe. I respect scientists very much, and as many of them agree on the big bang theory I accept that is what they think. but.......

[Teddio]

Annie,
Gravity is an attractive force. After the explosion, every fragment would attract every other fragment. Therefore each fragment would slow down relative to its starting position.
Depending on the initial velocities of the fragments and the mass of the bomb, it is possible that the fragments will slow down, stop, then accelerate back towards their origin.
This is analogous to a Closed Universe and the "Big Crunch".
I can't explain how or why the Big Bang happened or what existed "before" the Big Bang.

[Old_Geezer]

Nothing went "bang" because of the uncertainty principle. There appear to be some pairs of things that one can not know both for sure. This is not a practical 'measuring issue', but a fundamental 'maths shows it can't be done issue'. So, one can not guarantee certain things, such as that nothing won't explode into something, so it inevitably does. You need to dig deep in to quantum theory and the associated maths if you want more detail.

[I_Hate_Infinity]

Okay, some very good comments so far but I will bring us back to the point of "internal vs external." Has anyone in the world of physics offered my theory of an external 'suck' which causes the inflation of the Universe? Have there been papers released theorising this?

It is in my opinion that, we must not rule out my alternative possibility to Dark Energy. The fact that we have measured the Universe and know it is not only expanding but the rate of expansion is speeding up, suggests to me an opportunity to theorise the conditions outside our universe, to which the universe is expanding into.

Is Dark Energy just the easiest way to express this phenomena?
e.g. "The rate of expansion in the universe is increasing therefore there must be a 'force' pushing space-time apart, stretching it in all directions. The maths tells us that the force required to allow the increasing rate of expansion observed, must occupy over 70% of the Universe's constitution to fit the data."
Like Einstein's leap of imagination into the bizarre and non-experimental world, from Newtonian gravity to the warping of space-time, might we be excluding the the possibility of natural forces and conditions in our external environment just because it is hard to prove/explain?? Maybe no one has the guts to go all out and suggest our universe has an external, calculable environment that may conform to our internal physical laws e.g. Nature abhors a imbalance and instability, so when presented with a source of matter/energy/space-time in a vacuum, it 'sucks' on it to equalize the pressure difference...

What is the argument FOR the existence of dark energy? Why must it be internal?

Infinity

[Old_Geezer]

There isn't supposed to be an external vacuum to suck from. The universe doesn't expand into anything, it expands by creating space throughout itself.

That stated, I'll let somone else discuss how that fits in to the idea of brane universes in a higher dimensional space. :-)

[vascop]

Your questions are such that they need answers the size of a book! I suggest you read the following book:

Black Holes, Worm Holes,and Time Machines by Jim Al-Khalili Second Edition.

This is written for non-physicists and is bang up-to-date. While you are reading it make notes and then and only then formulate some questions and post them on Answer Bank. We can't write a book on here and short answers to questions such as yours are always unsatisfactory and just beg further questions. Take my advice and read.

[RATTER15]

Ask Goodlife, im sure he will be able to tell you how his God created it, he does appear to have "inside" information unavailable to the rest of us.

[LazyGun]

@IHI It is my understanding that your question is irrelevant, simply because there is no "external void" into which the "expanding universe" is expanding.

That balloon analogy that is often used to illustrate the expanding universe is ok as a very simple analogy, but it reinforces the erroneous idea that there is an external void ( ie the room in which the balloon is being expanded) and that there is a "boundary" between the universe and the external void.

Your question only has relevance, I think, if you can demonstrate that there is an external void into which the universe is expanding :)

[I_Hate_Infinity]

@LazyGun

The very nature of my question is to postulate the idea that we may have stumbled upon evidence that there is an external space and it has characteristics. If you first provide evidence that there is no space into which the universe is expanding and explain your conclusion that it has no boundary? I will then personally check if there is anything there :)

And I'll go nuts if you try to evoke infinity!!

Infinity

[DangerUXD]

Dark energy/matter are names given to things that need to exist for the equations to work. So what we are really saying is that in order for our understanding of what happens to be right we need to invent names for things. Eg Dark matter is what we call the "stuff" that must exist for galaxies to coalesce. Beyond that we really have no clue. Similarly Dark energy is the name we give to and unknown effect that pushes galaxies apart. The nature of how it works is entirely open to speculataion. Your hypotheses is as valid as any other all we know is the effect we can observe how it is actually caused we have no clue.

[Bazile]

I struggle with this concept that the universe is everything and everywhere - yet it is expanding .

But then , i'm only a lowly star ship captain :-)

[LazyGun]

@IHI I haven't seen any evidence to suggest that there is a void into which the universe is expanding - do you have any? or any references?

An inflationary universe definitely has some theoretical problems, but the idea of a void into which the universe is "expanding" is fraught with even more, so I understand - although i am not a cosmologist, physicist or mathematician, so am quite happy to look at any evidence.

Fact is, such questions stretch the boundaries of our current knowledge, so everything kind of collapses into uncertainty :)

[Old_Geezer]

From my point of view the universe has to be finite since we believe it started from a single point: so being finite once it would need infinite acceleration at some point to be infinite now. This just doesn't seem reasonable to me, so I take it as read that, that didn't occur.

I don't believe the universe can have a boundary either since, as an explanation of reality, it just opens up a whole load of other questions; such as what is behind the "brick wall" boundary ? It doesn't really explain anything for me so I do not favour it.

Therefore I have to be attracted to the idea that space curves somehow and go far enough and you find yourself heading back to where you started. I hope that if all today's measurements seem to suggest a flat universe then that is somehow down to how very large the universe is, that we've yet to pick up the curve evidence. Otherwise I've no idea what 'Explanation B' is.

So from the above, no boundary, but finite. May not have the proof yet but it works for me, for today at least. So no void of sucking vacuum.

[heathfield]

Scientists don't know what 'Dark Energy' is, but it has a name. Hmm. So did 'phlogiston'. Anyway...

http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/

[vascop]

Old_Geezer
//From my point of view the universe has to be finite since we believe it started from a single point: so being finite once it would need infinite acceleration at some point to be infinite now. This just doesn't seem reasonable to me, so I take it as read that, that didn't occur. //

This is considered wrong. See Jim Al-Khalili's book cited in my post above.
The Big Bang occurred everywhere at once. I wasn't like an explosion with everything flying away from a central point.

[vascop]

Sorry that should be "It wasn't...."

[I_Hate_Infinity]

@vascop
It's a wonder why you force yourself to participate in any of these threads, when I assume your solution for all TheAnswerBank user's questions is to pick up a book.
Let's forget for a moment that Humans by nature are social creatures, developing themselves by exchanging ideas with each other, and let's focus on the important bit. You post on this website because you clearly are intellectual and highly knowledgeable and have answers to questions people want answered (not necessarily correctly but honestly.)
And without analysing the android cold delivery of your comments on posts and the growing seed of a superiority complex; we must now ask for one more post from you; (because you know all that really...)
Can you, vascop 'the wise', tell me your honest belief... Internal or External??
[But if insist on using Prof J.Al-khlili's book as reference, I would recommend a summary]
[[And if I hadn't just replied to you like Arnold Rimmer would belittle Kryton, I would've simply said: "I want your opinion, not a dumbed-down text book" (No offence intended)]]

R.S.V.P x

[Old_Geezer]

But that everywhere was a finite point.